ES2370450T3 - DISCLOSURE DEVICE AND IMAGE FORMATION APPLIANCE USING THE SAME. - Google Patents

Abstract

A developing device (4), comprising: a developer carrier (5), which rotates while transporting a developer on a surface thereof, supplies a toner to a latent image on a surface of a latent image carrier (1) in a section where the developer carrier (5) faces the latent image carrier (1), and which reveals the latent image; a developer transport path (9), which features a developer transport element (8) that transports the developer, and transports the developer while supplying the developer to the developer carrier (5) in a developer supply region in that which the developer is supplied to the developer carrier (5); a developer discharge hole (94), which is provided in the developer transport path (9), and which discharges the developer outside the developer device, at a predetermined height level of a position at which the volume of the developer increases or decreases as the amount of developer in the developer transport path (9) increases or decreases; and a spreader developer discharge prevention element (3) that is shaped to block a path through which the spreader developer as a result of a transport operation of the developer transport element (8) moves towards the orifice of developer download (94); characterized in that the spreading developer discharge prevention element (3) is provided to block a straight line path connecting the lowest point of the developer discharge port (94) with the top of a top part of a part winged (8b) of the developer transport element (8).

Description

Development device and imaging device that uses it

one.

Field of the Invention

The present invention relates to a developing device that is used in a copier, a facsimile device, a printer, and the like, and an imaging device that uses the developing device.

2.

Description of the prior art

Conventionally, an imaging device with a developing device using a two-component developer consisting of a toner and a magnetic carrier has been widely used. Like this type of imaging apparatus, there is an imaging apparatus in which the toner is replenished, as necessary, from a toner container to a developer contained in a developing device that consumes toner as it develops. the development, and therefore the developer toner density is maintained within a predetermined range. In such a configuration, since the carrier contained in the developer is used repeatedly without having been consumed significantly, the layer covered on the surface layer of the carrier wears out when an image is printed, or an additive or resin of Toner adheres to the coating layer. Consequently, the ability of the carrier to load the toner gradually decreases, deteriorating the carrier. The amount of toner charge decreases as the deterioration of the carrier continues, causing the formation of spots or spreading of the toner. Therefore, a technician is regularly sent to the user of this type of imaging apparatus to replace the carrier. For this reason, the maintenance cost and the cost per image formation increase.

Japanese patent application pending examination number 2005-292511 describes a developing device in which a developer premixed with a mixture of carrier and toner is replenished in the developer contained in the developing device to recover the density of the toner, and at at the same time the developer increase is downloaded from the development device. In such a configuration, the old carrier is slowly unloaded from the developing device by unloading the developer, and at the same time the new carrier within the premixed developer is replenished in the developer contained in the developing device. Then, the bearer is replaced with a new bearer, gradually unloading and resupplying, so the task of replacing the bearer can be omitted.

In addition, in this developing device, a developer discharge port is provided to discharge the developer out of the device at a predetermined height level of the position in which the developer volume increases or decreases as the amount of developer in The entire developer transport path increases or decreases. In this developing device, when the premixed toner is replenished and the amount of developer within the developing device increases, the volume of the developer increases in a supply transport path. At this time, the developer who has reached the level of the developer discharge orifice in the position provided with the developer discharge orifice is discharged from the developer discharge orifice outside the developer.

However, the developer transported within the developer transport path spreads due to its driving force or the rotational force of a transport element that gives the developer a transport force when the transport element is a transport screw. developer, and the scattered developer is sometimes downloaded from the developer download hole. The spread developer is discharged, even if the developer is transported in the developer transport path in an appropriate amount or less. In this situation, the developer is downloaded even if the amount of developer inside the developing device has not increased. If the developer is discharged from the developer discharge port even though the amount of developer is less than the appropriate amount, the amount of developer within the developing device may be below the required amount destabilizing the supply of the developer to a bearer of latent images. If the developer's supply to the bearer of latent images is destabilized, an omission in the image and other defective images may occur.

These problems are not limited to a developer device that uses a two-component developer, and therefore can occur in any developer device that uses a one-component developer, provided that such a developer device is configured so that a developer is replenished by developer resupply means and then the developer increment within the developer device is discharged by developer download means.

Technologies related to the present invention are also disclosed in, for example, the Japanese patent application pending examination number H05-127537, the Japanese patent application pending examination number H11-007195, the Japanese patent application pending examination number H11 -024382, the Japanese patent application pending examination number 2000-047474 and also in the Japanese patent application number

2,891,845 and in US Patent US-A-4 101 211.

SUMMARY OF THE INVENTION

The present invention has been conceived in view of the above problems, and an object of the present invention is to provide a developing device that can stably supply a developer to a latent image carrier, preventing the spread developer from being discharged despite that the amount of developer within the developing device does not increase, and also provide an imaging device that uses the developing device.

Claim 1 defines such developing device of the present invention, while advantageous embodiments thereof are defined in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing objects and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken together with the accompanying drawings, in which:

Fig. 1 is a view showing a schematic configuration of a copier according to embodiment 1 of the present invention;

Fig. 2 is a view showing schematic configurations of a developing device and a copier photoreceptor;

Fig. 3 is an external perspective sectioned view showing a part of the developing device to explain a flow of a developer;

Fig. 4 is a schematic representation showing the flow of the developer within the developing device;

Fig. 5 is a cross-sectional view showing the configuration of the developing device;

Fig. 6 is a schematic diagram showing a flow of the developer within a developing device that has a different shape to that shown in fig. 4;

Fig. 7 is an external perspective view showing the configuration of the developing device;

Fig. 8 is an explanatory diagram in cross section of the developing device according to example 1 of the present embodiment;

Fig. 9 is a perspective view showing the configuration near a near side end portion of the developing device of Example 1, which is obtained after removing a stirring screw, a recovery screw, and a tangent blade from the developing device of developing device;

Fig. 10 is a perspective view showing the configuration near the near side of the developing device of example 1 shown in fig. 9, which is obtained after removing a supply screw from the developing device;

Fig. 11 is an explanatory diagram in perspective showing the configuration near a near side of the developing device of example 1 shown in fig. 10, which is obtained after removing a developing roller from the developing device;

Fig. 12 is a perspective view in which the developing device of example 1 shown in fig. 11 is seen from a different direction than that of fig. eleven;

Fig. 13 is a cross-sectional view showing the configuration of the developing device according to example 2 of the present embodiment;

Fig. 14 is a cross-sectional view showing the configuration of the developing device in which the length of a plate-like element is shorter than that of example 2;

Fig. 15 is a cross-sectional view showing the configuration of the developing device in which the position of a developer discharge orifice is inferior to that of example 2;

Fig. 16 is a view showing the configuration near one end downstream of a supply transport path of the developing device according to example 3 of the present embodiment;

Fig. 17 is a view showing a wall surface located at the downstream end;

Fig. 18 is a side cross-sectional view showing the developing device according to example 4 of the present embodiment;

Fig. 19 is a side cross-sectional view showing the developing device according to example 5 of the present embodiment;

Fig. 20 is a side cross-sectional view showing the developing device according to example 6 of the present embodiment;

Fig. 21 is a view showing schematic configurations of the developing device and the photoreceptor according to a modification of the present embodiment; Y

Fig. 22 is a cross-sectional view showing the configuration of the conventional developing device having a developer discharge hole.

DESCRIPTION OF THE PREFERRED EMBODIMENT (S)

[Embodiment 1]

As the imaging apparatus to which the present invention is applied, an embodiment (simply referred to as "embodiment 1" hereinafter) of a color laser tandem copier (referred to simply as "copier" hereinafter) will be described below. which a plurality of photoreceptors are arranged in parallel with each other.

Fig. 1 shows a schematic configuration of the copier according to embodiment 1. This copier has a printing part 100, a sheet feeding device 200 on which the printing part is placed, a scanner 300 fixedly placed on the part of 100 print, and the like. The copier also features an automatic original transport device 400 that is fixedly placed on the scanner 300.

The printing part 100 has an imaging unit 20 consisting of four process cartridges 18Y, M, C and K for imaging with the color yellow (Y, yellow), magenta (M), cyan

(C) and black (K, black), respectively. Y, M, C and K provided at the end of the reference numbers indicate the elements for the colors yellow, magenta, cyan and black, respectively (the same in the following). An optical writing unit 21, an intermediate transfer unit 17, a secondary transfer device 22, a pair of protective rollers 49, a belt fixing device 25 and the like are arranged in addition to the process cartridges 18Y , M, C and K.

The optical writing unit 21 has a light source, a polygonal mirror, an f-0 lens, a reflecting mirror, and the like, (not shown), and emits a laser beam on the surface of a photoreceptor that will be described later. based on image data.

Each of the process cartridges 18Y, M, C and K has a drum-like photoreceptor 1, a charging unit, a developing device 4, a drum cleaning device, a destabilization unit, and the like.

Next, the yellow process cartridge 18 will be described.

The surface of a 1Y photoreceptor is charged uniformly by the charging unit that functions as a charging medium. The surface of the photoreceptor 1Y that is subject to charge processing is irradiated with a laser beam that is modulated and deflected by the optical writing unit 21. Consequently, the potential of the irradiated part (exposed part) is attenuated. Due to this attenuation, an electrostatic latent image Y is formed on the surface of the 1Y photoreceptor. The electrostatic latent image Y formed is revealed by a developing device 4Y that serves as a developing means, whereby a toner image Y is obtained.

The toner image Y formed in the photoreceptor Y 1Y is first transferred to an intermediate transfer belt 110 which will be described later. The residual transfer toner on the surface of the photoreceptor 1Y is cleaned by the drum cleaning device after the toner image Y is transferred first.

In the Y 18Y process cartridge, the 1Y photoreceptor that is cleaned by the drum cleaning device is destabilized by the destabilization unit. Then, the photoreceptor 1Y is charged uniformly by the charging unit and therefore returns to the initial state. The series of processes described above is the same for the other process cartridges 18M, C and K.

Next, the intermediate transfer unit will be described.

The intermediate transfer unit 17 has the intermediate transfer belt 110, a belt cleaning device 90, and the like. The intermediate transfer unit 17 also has a tension roller 14, a drive roller 15, a secondary transfer reserve roller 16, four primary transfer bias rollers 62Y, M, C and K, and the like.

The intermediate transfer belt 110 is tensioned by a plurality of rollers including the tensioner roller

14. The intermediate transfer belt 110 is then moved in an endless path clockwise in the drawing by rotating the drive roller 15 which is driven by a belt drive motor (not shown).

Each of the four primary transfer polarization rollers 62Y, M, C and K is arranged in contact with the inner peripheral surface of the intermediate transfer belt 110, and a primary transfer polarization is applied from a power source, not shown In addition, the inner peripheral surface of the intermediate transfer belt 110 is pressed against the photoreceptors 1Y, M, C and K to form primary transfer contact points. At each of the primary transfer contact points an electric primary transfer field is formed between each photoreceptor and each primary transfer polarization roller due to the influence of the primary transfer polarization.

The aforementioned Y-toner image formed in the Y 1Y photoreceptor is first transferred over the intermediate transfer belt 110 due to the influence of the contact point pressure or the primary electric transfer field. The toner images M, C and K formed in the photoreceptors M, C and K, 1M, C and K overlap sequentially and are first transferred onto the toner image Y. A four-color superimposed toner image (referred to as " four-color toner image " hereafter), that is, the multiple toner image, is formed on the intermediate transfer belt 110 due to the primary transfer performed by superimposing the toner images.

The four-color toner image that is transferred on the intermediate transfer belt 110 is transferred secondly on a transfer sheet, that is, a recording medium not shown, by a secondary transfer contact point described below. The residual transfer toner that remains on the surface of the intermediate transfer belt 110 after the developer has passed through the secondary transfer contact point is cleaned by the belt cleaning device 90 that holds the belt between this device belt cleaning and drive roller 15 located on the left side of the drawing.

Next, the secondary transfer device 22 will be described.

The secondary transfer device 22 tensioning a sheet transport belt 24 by means of two tension rollers 23 is arranged on the lower side of the intermediate transfer unit 17 as shown. The sheet conveyor belt 24 moves in an endless path in the opposite direction to the clockwise in the drawing when at least one of the tension rollers 23 is driven and rotated. Of the two tension rollers 23, the roller disposed on the right side of the drawing holds the intermediate transfer belt 110 and the sheet transport belt 24 between the tensioner roller and the secondary reserve roller 16 of the intermediate transfer unit 17. Accordingly, the point is formed of secondary transfer contact in which the intermediate transfer belt 110 of the intermediate transfer unit 17 makes contact with the sheet transport belt 24 of the secondary transfer device 22. Then, a tensioning polarization 23 is applied to this tensioning roller 23 secondary transfer that has a polarity opposite to the polarity of the toner, by means of the power supply not shown. Due to this application of the secondary transfer polarization, a secondary transfer electric field is formed at the secondary transfer contact point that electrostatically displaces the four-color toner image on the intermediate transfer belt 110 of the transfer unit intermediate transfer 17 from the belt side to this tension roller 23. The four-color toner image affected by the pressure of the contact point or the secondary transfer electric field is transferred secondly onto the transfer sheet which is sends to the secondary transfer contact point, by means of the pair of protective rollers 49 described above, in synchronization with the four-color toner image formed on the intermediate transfer belt 110. It should be noted that a magazine for loading the transfer sheet in a contactless way it can be provided instead of the system of secondary transfer that applies a secondary transfer polarization to this tensioner roller 23.

In the sheet feeding device 200 provided in a lower section of the main body of the copier, a plurality of sheet feeding cassettes 44, each of which may contain a plurality of stacked transfer sheets, are arranged vertically in a stacked way. Each of the sheet feed cassettes 44 pushes the upper transfer sheet of the transfer sheets stacked against a sheet feed roller 42. Then, by rotating the sheet feed roller 42, the upper transfer sheet is sent towards a sheet feeding path 46.

The sheet feed path 46 received by the transfer sheet sent from the sheet feed cassette 44 has a plurality of pairs of transport rollers 47 and the pair of protective rollers 49 provided near one end of the travel path. leaf feeding. The sheet feed path 46 conveys the transfer sheet to the pair of protective rollers 49. The transfer sheet transported to the pair of protective rollers 49 is sandwiched between the roller parts of the pair of protective rollers 49. On the other hand, In the intermediate transfer unit 17, the four-color toner image formed in the intermediate transfer belt 110 enters the secondary transfer contact point as the belt moves in an endless path. The pair of protective rollers 49 sends the transfer sheet sandwiched between the roller parts at the moment when the transfer sheet adheres to the four-color toner image at the secondary transfer contact point. In this way, the four-color toner image formed on the intermediate transfer belt 110 adheres to the transfer sheet at the secondary transfer contact point. Then, the four-color toner image is transferred secondly on the transfer sheet and, therefore, becomes a full color image on the white transfer sheet. The transfer sheet on which the full color image is formed in this way leaves the secondary transfer contact point as the sheet transport belt 24 moves in an endless path, and then is sent from the part upper of the sheet transport belt 24 towards the fixing device 25.

The fixing device 25 has a belt unit that is moved in an endless path during tensioning of a fixing belt 26 by means of two rollers, and a pressure roller 27 that is pushed against one of the rollers of the drive unit. belt. The fixing belt 26 and the pressure roller 27 make contact with each other to form a fixing contact point, and the transfer sheet received from the sheet transport belt 24 is sandwiched by this contact point. Of the two rollers of the belt unit, the roller pushed by the pressure roller 27 has a heat source therein, not shown, and applies pressure on the fixing belt 26 using the heat generated by the heat source. The fixing belt 26 to which pressure is applied then heats the interleaved transfer sheet by means of the fixing contact point. Due to the application of heat or the pressure of the contact point, the full color image is fixed on the transfer sheet.

The transfer sheet subjected to the fixing process in the fixing device 25 is stacked in a stacking portion 57 provided outside a plate of a printer coating on the left side of the drawing, or returned to the secondary transfer contact point mentioned above in order to form a toner image on the other side of the transfer sheet.

When a copy of an original (not shown) is made, for example, a set of original sheets is arranged on an original plate 30 of the automatic original transport device 400. However, if this original is an original with only one registration delimited by the contents of the document, the set of original sheets is arranged on a contact glass 32. Before this arrangement operation, the automatic original transport device 400 is open with respect to the main body of the copier and, by therefore, the contact glass 32 of the scanner 300 is exposed. Then, the single-register original is pushed by the closed automatic original transport device 400.

After the original is arranged in this way, a copy start switch (not shown) is pressed, whereby the scanner 300 performs an operation of reading the original. However, if an original sheet is arranged in the automatic original transport device 400, the automatic original transport device 400 automatically moves the original sheet towards the contact glass 32 before the original reading operation is performed. When the reading operation of the original is performed, a first displacement body 33 and a second displacement body 34 begin to displace together first, and a light is emitted from a source of light provided in the first displacement body 33. Then, the light reflected from the surface of the original is reflected by a mirror provided in the second displacement body 34, crosses an imaging lens 35 and then penetrates a reading sensor 36. The reading sensor 36 constructs information Image based on reflected light.

In parallel to this operation of reading the original, each element within each of the process cartridges 18Y, M, C and K, the intermediate transfer unit 17, the secondary transfer device 22 and the fixing device 25 start their drive Then, the optical writing unit 21 is operated and controlled based on the image information constructed by the reading sensor 36, and toner images Y, M, C and K are formed in the photoreceptors 1Y, M, C and K respectively. These toner images become a four-color toner image by superimposing and transferring these toner images onto the intermediate transfer belt

110.

In addition, basically at the same time as when the reading operation of the original is performed, a sheet feed operation is initiated in the sheet feed device 200. In this sheet feed operation one of the sheets is selected and rotated sheet feed rollers 42 and transfer sheets are sent from one of the sheet feed cassettes 44 that are stored at multiple levels in a sheet bank 43. The sent transfer sheets are separated one by one by a separation roller. 45. Each sheet enters a reverse sheet feed path 46 and then is transported to the secondary transfer contact point by the pair of transport rollers 47. The sheets are sometimes inserted from a hand tray 51 instead of the sheet feed cassettes 44. In this case, after selecting and rotating a feed roller 50 for manual sheets for To send transfer sheets placed in the manual tray 51, the separation roller 52 separates the transfer sheets one by one and inserts each sheet into a feed path 53 of manual sheets of the printing part 100.

In the present copier, when another color image is formed consisting of toners of two or more colors, the intermediate transfer belt 110 is tensioned so that an upper tensioning surface thereof is arranged substantially horizontally, and all photoreceptors 1Y, M, C and K make contact with the upper tensioning surface. On the other hand, when a monochrome image consisting only of the toner K is formed, the intermediate transfer belt 110 tilts down to the left of the drawing using a mechanism not shown, and the upper tensioning surface is separated from Y, M and C and of the photoreceptors 1Y, M and C. Then, of the four photoreceptors 1Y, M, C and K, only the photoreceptor K 1K rotates in the opposite direction to the clock hands in the drawing to form only a toner image K. At this time, for Y, M and C the actuation of the photoreceptors 1 thereof as well as development stops to prevent the photoreceptors and the developer from unnecessarily depleting.

The present copier has a control unit, not shown, which is configured by means of a CPU and the like, which controls the following elements of the copier, and an operation display part, not shown, which is configured by a liquid crystal display. , several keys and the like. An operator can select one of three print modes on one side to form an image on one side of a transfer sheet, by sending a command to the control unit based on the implementation of an operation entered by keyboard on the display part of operation. The three single-sided printing modes are a direct download mode, a reverse download mode and a reverse decal download mode.

Fig. 2 shows the developing device 4 provided in one of the four process cartridges 18Y, M, C and K and the photoreceptor 1. Apart from the fact that they manipulate different colors, the configurations of the four process cartridges 18Y, M, C and K are essentially identical and, therefore, the letters Y, M, C and K applied to "4" of the drawing have been omitted.

The surface of the photoreceptor 1 is charged by the charging device (not shown), as it rotates in the direction of the arrow G in the drawing shown in fig. 2. The toner is supplied from the developing device 4 to a latent image formed as an electrostatic latent image on the surface of the charged photoreceptor 1 by a laser beam irradiated from an exposure device (not shown), to form a toner image .

The developing device 4 has a developing roller 5 that serves as a developer carrier that supplies the toner to reveal the latent image of the surface of the photoreceptor 1 during surface movement in the direction of the arrow I of the drawing. The developing device 4 also has a supply screw 8 which serves as a supply transport element for, during the delivery of the developer to the development roller 5, to transport the developer in the direction towards the remote side of fig. 2. The supply screw 8 is a developer transport screw that has a rotation axis and a winged portion provided on this rotation axis, and that transports the developer in the axial direction by rotation.

A tangent development blade 12 is provided, which serves as a developer adjustment element to regulate the thickness of the developer supplied to the developer roller 5 to a suitable thickness for development, on the downstream side in the direction of surface movement of the developer roller 5 from a part facing the supply screw 8.

A recovery screw 6 is provided, which serves as the recovery transport element to recover the developer that has passed through the development part and that has been used for the development and to transport the recovered recovery developer in the same direction as the direction of the supply screw 8, on the downstream side in the direction of the surface movement of the developing roller 5 from the developing part that constitutes a part facing the photoreceptor 1. A supply transport path 9 presenting the screw of Supply 8 is arranged in the lateral direction of the developing roller 5, and a recovery transport path 7 serving as the recovery transport path that the recovery screw 6 has is arranged in parallel below the development roller 5.

An agitation transport path 10 is provided in the developing device 4 in parallel with the recovery transport path 7 below the supply transport path 9. The agitation transport path 10 has an agitation screw 11 serving as a stirring / transport element for, during agitation of the developer, to transport it in the opposite direction to the direction of the supply screw 8, the opposite direction being oriented on the near side of the drawing.

The supply transport path 9 and the agitation transport path 10 are separated by a first separation wall 133 that serves as the separation element. An opening part is formed in part of the first separation wall 133 that separates the supply transport path 9 and the agitation transport path 10 at both ends on the near side and on the far side of the drawing to connect with each other. the supply transport path 9 and the agitation transport path 10.

Note that the supply transport path 9 and the recovery transport path 7 are also separated by the first separation wall 133, but there is no opening part provided in the part where the first partition wall 133 separates the path of Supply transport 9 and recovery transport path 7.

The two transport paths, that is, the agitation transport path 10 and the recovery transport path 7, are also separated by a second separation wall 134 that serves as the separation element. An opening part is formed in the second separation wall 134 on the near side of the drawing to connect the stirring transport path 10 and the recovery transport path 7 to each other.

The supply screw 8, the recovery screw 6 and the stirring screw 11 which serve as the transport elements of the developer are made of resin or metal. The diameter of each screw is set to φ22 [mm]. The supply screw has a thread pitch of 50 [mm] in the form of a double winding, and the recovery screw 6 and the stirring screw 11 each have a thread pitch of 25 [mm] in the form of a single winding The revolution speed of each screw is set to 600 [rpm].

The developer that is made thinner by the stainless tangent development blade 12 on the developer roller 5 is transported to a developer region facing the photoreceptor 1 to perform the development. The surface of the developer roller 5 formed from a set of Al or SUS ducts with a diameter of φ25 [mm] has a V-shaped notch or is sandblasted. The size of the gap formed between the tangent development blade 12 and the photoreceptor 1 is approximately 0.3 [mm].

The developer obtained after development is recovered by the recovery transport path 7, then transported to the near side of the cross section of fig. 2, and then transferred to the agitation transport path 10 in the opening portion of the first separation wall 133 provided in a region without images. It should be noted that the toner is replenished from a toner replenishment opening provided above the agitation transport path 10 to the agitation transport path 10, near the opening portion of the first separation wall 133 on the side upstream in the direction of developer transport in the agitation transport path 10.

Next, the circulation of the developer in the three developer transport paths will be described.

Fig. 3 shows a developer flow in the developer transport paths. The arrows in the drawing indicate the directions of movement of the developer.

In addition, fig. 4 shows a flow of the developer in the developing device 4. As in fig. 3, the arrows in the schematic diagram indicate the directions of movement of the developer.

In the supply transport path 9 in which the developer is supplied from the agitation transport path 10, the developer is transported to the downstream side in the direction of transport of the supply screw 8, while it is supplied to the feed roller. development 5. The excess developer that is supplied to the developer roller 5 and that is transported to a downstream end in the direction of transport of the supply transport path 9 without being used in the development is supplied to the path of stirring transport 10 through an excess opening part 92 of the first separation wall 133 (arrow E in fig. 4).

The recovery developer that is supplied from the development roller 5 to the recovery transport path 7 and which is transported to the downstream end in the direction of transport of the recovery transport path 7 by the recovery screw 6 is supplied to the agitation transport path 10 through a recovery opening part 93 of the second separation element 134 (arrow F of Fig. 4).

The stirring transport path 10 agitates the excess developer supplied and the recovery developer, therefore, transports the mixture obtained to the upstream side in the direction of transport of the supply screw 8, which constitutes the downstream side in the direction of transport of the stirring screw 11, and supplies it to the supply transport path 9 through a supply opening part 91 of the first separation wall 133 (arrow D in fig. 4).

In the agitation transport path 10, the recovery developer, the excess developer and the replenished toner from a transport part as needed are agitated and transported in the opposite direction to that of the developer of the recovery path 7 and of supply path 9 using the stirring screw

11. The agitated developer is transported to the upstream side in the direction of transport of the supply transport path 9 which is communicated on the downstream side in the direction of transport. Note that a toner density detector (not shown) is provided below the agitation transport path 10, and a toner refill control device (not shown), is actuated by the sensor output so that the toner It is replenished from a part that contains toner, not shown.

In the developing device 4 shown in fig. 4 presenting the supply transport path 9 and the recovery transport path 7, since the developer is supplied and recovered in different developer transport paths, the developer used for the development is prevented from mixing in the path of supply transport 9. Therefore, the toner density of the developer supplied to the developer roller 5 is prevented from decreasing as the developer is sent to the downstream side in the direction of transport of the supply transport path 9 In addition, since the developing device has the recovery transport path 7 and the agitation transport path 10 and since the developer recovers and is agitated on different developer transport paths, losses of the developer used in the development while it is stirring. Therefore, since the insufficiently agitated developer is supplied to the supply transport path 9, insufficient agitation of the developer to be supplied to the supply transport path 9 can be prevented. Since the density is prevented from decreasing toner of the developer of the supply transport path 9 and thus insufficient agitation of the developer in the supply transport path 9 is prevented, a constant image density can be ensured throughout development.

As shown in fig. 4, the developer travels from the bottom of the developing device 4 to the top of it only in the direction of the arrow D. The developer moves in the direction of the arrow D to raise the developer and deliver the developer to the supply transport path 9 by pushing the developer using the rotation of the stirring screw 11.

Such movement of the developer causes tension in the developer, reducing the life of the developer.

When the developer rises as described above, tension is generated in the developer, whereby a scraping of a carrier film and a toner consumption in the tensioned part of the developer is produced and, therefore, no longer Stable image quality can be maintained.

Therefore, the life of the developer can be increased by mitigating the tension that is generated in the developer when the developer moves in the direction of the arrow D. By increasing the life of the developer it is possible to provide a developing device that can prevent that the developer degrades and that it can provide stable image quality without irregularities in image density.

In the developing device 4 of this embodiment 1, the supply transport path 9 is disposed above the agitation transport path 10 obliquely, as shown in fig. 2. By arranging the supply transport path 9 obliquely, the tension generated in the developer when moving the developer in the direction of arrow D can be further mitigated compared to the case in which the transport path of Supply 9 is provided directly above the agitation transport path 10 to raise the developer.

Furthermore, in the developing device 4, the supply transport path 9 and the agitation transport path 10 are arranged obliquely, whereby an upper wall surface of the agitation transport path 10 is arranged in a position higher than a lower wall surface of the supply transport path 9, as shown in fig. 2.

When the supply transport path 9 is arranged above in a direction perpendicular to the agitation transport path 10, the developer rises due to the pressure of the stirring screw 11 against the force of gravity, thereby generating tension in the developer. However, by arranging the upper wall surface of the stirring transport path 10 in a position higher than the lower wall surface of the supply transport path 9, the developer exiting at the highest point of the path The agitation transport 10 can flow to the lowest point of the supply transport path 9 without fighting gravity, and therefore the tension generated in the developer can be reduced.

It should be noted that a fin element can be provided on the axis of the stirring screw 11, which is a section in which the agitation transport path 10 and the supply transport path 9 communicate with each other on the downstream side of the developer transport path of the agitation transport path 10. This fin element is a plate-like element configured on one side parallel to the axial direction of the stirring screw 11 and on one side perpendicular to the axial direction of the stirring screw. By raising the developer using the flap element, the developer can be effectively delivered from the agitation transport path 10 to the supply transport path 9.

Furthermore, in the developing device 4, the supply transport path 9 and the agitation transport path 10 are arranged so that the distance A between the centers of the development roller 5 and the supply transport path 9 is shorter than the distance B between the centers of the roller 5 and the stirring transport path 10. In this way, the developer can be supplied from the supply transport path 9 to the developing roller 5 in a natural way, and The size of the device can be reduced.

In addition, the stirring screw 11 rotates counterclockwise as seen from the near side of Fig. 2 (direction of arrow C in the drawing), so that the developer rises along the shape of the stirring screw 11 and is transported to the supply transport path 9. Accordingly, the developer can be raised efficiently and also the tension generated therein can be reduced.

Fig. 5 is a cross-sectional view of the center of rotation of the supply screw 8 of the developing device 4, the center of rotation being seen in the direction of the arrow J shown in fig. 3. The reference number H in the drawing shows a developing region in which the developing roller 5 serving as a developer carrier supplies the toner to the photoreceptor 1 serving as a latent image carrier. The width of the developing region H in the direction of the axis of rotation of the developing roller 5 is the width α of the developing region.

As shown in fig. 5, the developing device 4 is provided, within the width α of the developing region, of the supply opening part 91 to raise the developer from the agitation transport path 10 to the supply transport path 9, and of the excess opening part 92 to drop the developer from the supply transport path 9 to the agitation transport path 10.

Fig. 6 shows a flow of the developer within the developing device 4 which has a different configuration with respect to the developing device shown in fig. Four.

In the developing device 4 shown in fig. 6, the supply opening part 91 and the excess opening part 92 are provided outside the width α of the developing region. Since the supply opening part 91 is provided outside the width α of the development region, the upstream side in the direction of transport of the supply transport path 9 is longer than the development roller 5 by a region β upstream of the supply transport path. In addition, since the excess opening part 92 is provided outside the width α of the developing region, the downstream side in the direction of transport of the supply transport path 9 is longer than the development roller 5 by a γ region downstream of the supply transport path.

On the other hand, in the developing device 4 with the configuration shown in fig. 4, since the supply opening part 91 is provided within the width α of the developing region, the upstream side in the direction of transport of the supply transport path 9 can be made shorter than the developing device 4 shown in fig. 6 eliminating the β region upstream of the supply path. Furthermore, since the excess opening part 92 is provided within the width α of the developing region, the downstream side in the direction of transport of the supply transport path 9 can be made shorter than the developing device 4 shown in fig. 6 eliminating the γ region downstream of the supply transport path.

Since the supply opening part 91 and the excess opening part 92 of the developing device 4 shown in fig. 4 are provided within the width α of the developing region as described above, more space can be saved in the upper part of the developing device 4 compared to the developing device 4 shown in fig. 6.

Next, the position in which the toner is replenished in the developer transport paths constituted by the supply transport path 9, the agitation transport path 10 and the recovery transport path 7 of the developing device 4 will be described. Fig. 7 shows the outside of the developing device 4.

As shown in fig. 7, the toner refill hole 95 for replenishing the toner is provided on top of an upstream end portion in the direction of transport of the agitation transport path 10 that the agitation screw 11 presents. Since this refill hole Toner 95 is provided on the outer side of the end portion in the direction of the width of the developer roller 5, is located outside the width α of the developer region.

The section provided with the toner refill port 95 is an extension of the direction of transport of the supply transport path 9 and corresponds to an empty space of the region γ downstream of the supply transport path shown in fig. 6. By providing the toner refill hole 95 in the empty space obtained by providing the excess opening portion 92 within the width α of the developing region, the size of the developing device 4 can be reduced.

The toner refill port 95 may be provided not only above the upstream end portion in the direction of transport of the agitation transport path 10, but also above a downstream end portion of the recovery transport path 7.

In addition, the toner refill hole 95 can be provided immediately above the recovery opening portion 93, which is a section in which the developer is supplied from the recovery transport path 7 to the agitation transport path 10 The space immediately above the recovery opening part 93 is also the empty space obtained by providing the excess opening part 92 within the width α of the developing region, and therefore the size of the developing device 4 can be reduced by providing the toner refill hole 95 in this position. In addition, in the recovery opening part 93 serving as the delivery part, the developer mixes easily, and therefore the developer can be agitated more efficiently by resupplying in this position.

As in the developing device 4 described with reference to fig. 4, the supply opening portion 91 is provided within the width α of the developing region to supply the developer from the downstream end in the direction of transport of the agitation transport path 10 to the upstream end in the direction of transport of the supply transport path 9, and the excess opening portion 92 for supplying the developer from the downstream end of the supply transport path 9 to the upstream end in the direction of transport of the transport path of agitation 10. Therefore, in comparison with the conventional developing device 4, space can be saved in the upper part of the developing device 4 and space can also be saved in the entire developing device 4.

In addition, the toner refill hole 95 is provided in the empty space that is obtained by providing the excess opening portion 92 within the width α of the developing region, and therefore the size of the developing device 4 can be reduced.

Since the toner is replenished from the top of the recovery opening part 93 which serves as a supply part to deliver the developer from the recovery transport path 7 to the agitation transport path 10, the developer can be agitated by effective way.

In addition, the developing device 4 is provided as a developing means of the printing part 100 of the copier, that is, of the imaging apparatus, and therefore space in the entire apparatus can be saved.

Next, the replacement of the developer in the developing device 4 will be described.

The toner refill control device (not shown), which serves as a developer refill means, replenishes the toner stored in the toner container (not shown), from the toner refill hole 95 to the developer device 4 In the developing device 4 of embodiment 1, the developer presenting toner and carrier is replenished from the toner refill hole 95 of the developing device 4. Hereinafter, the developer presenting a mixture of toner and carrier and which is replenished in developing device 4 will be referred to as "premixed toner".

In addition, the supply transport path 9 has a developer discharge port 94 for downloading part of the developer of the supply transport path 9 outside the development device 4 when the developer volume exceeds a predetermined volume, and a path of discharge transport 2 having a discharge transport screw 2a for transporting the unloaded developer from the developer discharge hole 94 to the outside of the developing device 4. The discharge transport path 2 is arranged on the downstream side at the direction of transport of the supply transport path 9 so that it is adjacent to the supply transport path 9 with a separation wall 135 therebetween. The developer discharge craft 94 is an opening provided in the separation wall 135 so that the supply transport path 9 and the discharge transport path 2 communicate with each other.

Next, the conventional developing device 4 having the developer discharge port 94 will be described.

Fig. 22 shows the configuration near the downstream end in the direction of transport of the supply transport path 9 of the conventional development device 4 having the development discharge hole 94, the development device 4 being viewed from the same direction as in fig. 2.

Note that the position near the downstream end in the direction of transport of the supply transport path 9 is the same as the position of, for example, the developer supply part for supplying the developer from the supply transport path 9 to the agitation transport path 10 in the direction of transport of the supply transport path 9.

In addition, the direction of rotation of the supply screw 8 in the supply transport path 9 is the clockwise direction in fig. 8 (direction of arrow M), which is a direction in which the developer rises from the bottom side and is then supplied to the developer roller 5. In this case, if the direction of rotation of the supply screw 8 is changed counterclockwise and the developer is sprayed on the developer roller 5, the developer is supplied in a scattered manner to the developer roller 5. However, if the direction of rotation of the supply screw 8 is the direction clockwise as shown in fig. 8, the developer that accumulates in the lower part of the supply transport path 9 is raised from the bottom side and supplied to the developer roller 5. The supply properties of the developer can be stabilized by raising the developer from the bottom, instead of supplying the developer in a scattered way. For this reason, the direction of rotation of the supply screw 8 of the developing device 4 is fixed clockwise as shown in fig. 8.

In particular, when the developer supplied to the developing roller 5 is recovered in the recovery transport path 7 without being returned to the supply transport path 9 as in the developing device 4 of the present embodiment, the amount of developer decreases to as it is sent downstream of the supply transport path 9. Therefore, the developing device in which the developer accumulated at the bottom is raised and supplied to the developing roller 5 is excellent in regard to to the developer's delivery properties.

In this case, the developer transported within the developer transport path 9 is spread by its driving force or by the rotational force of the supply screw 8 that serves as the developer transport screw. In addition, as shown in fig. 22, if the developer discharge port 94 is simply disposed at a predetermined height level of the supply transport path 9 that serves as the developer transport path, the spread developer could rise in the path indicated by the arrow T in fig. 22 and discharged through the developer discharge hole 94. When the developer spreads and discharges, there is a possibility that the spread developer is discharged even if an appropriate or smaller amount of developer is transported to the position of the developer path. Supply transport 9 provided with the developer discharge hole 94. If the spread developer is discharged in this manner, there is a possibility that the developer of the developer device 4 is discharged from the developer discharge hole despite the amount of this developer is less than or equal to an appropriate amount. Therefore, the amount of developer within the developer device 4 falls below a necessary amount, so that the developer cannot be supplied to the photoreceptor 1 stably. Then, if the developer is supplied to the photoreceptor 1 in an unstable manner, an omission in the image and other defective images occurs.

Note that the path through which the spread developer moves to the developer discharge hole 94 is shown by arrow T in fig. 22. The arrow T schematically shows the path through which the spread developer travels to the developer discharge hole 94, but the arrow T is not the only component to show the path through which the spread developer moves through the developer discharge hole 94.

Examples

Example 1

Next, the first example (referred to as "example 1" hereinafter) which presents the characteristics of the developing device 4 of this embodiment 1 will be described.

Fig. 8 shows the configuration of the developing device 4 of example 1. Fig. 9 shows the configuration near an end portion on the near side of the developing device 4 of embodiment 1 in which the stirring screw 11, the recovery screw 6 and the tangent developing blade 12 have been removed therefrom. . Fig. 10 is a view showing the immediate vicinity of the developing device 4 of example 1 in which in addition the supply screw 8 has been removed from the configuration shown in fig. 9, the developing device being viewed from a different direction with respect to fig. 9. Fig. 11 shows the developing device 4 of example 1 in which in addition the developing roller 5 has been removed from the configuration shown in fig. 10. Fig. 12 is a view of the developing device 4 of example 1 in which the developing device 4 having the same configuration as that shown in fig. 11 is seen from substantially the same direction as in fig. 3.

As shown in fig. 8, the developing device 4 of example 1 presents the blocking element 3 which serves as a prevention element for spreading the developer's discharge to block a path (arrow T in fig. 22) through which the spread developer moves towards the developer discharge hole 94, the scattered developer being obtained by rotating the supply screw 8, which is the developer transport element, to transport the developer. Since the developing device has the blocking element 3 to block the path through which the developer spread as a result of a transport operation performed by the supply screw 8 moves towards the developer discharge hole 94, it can the spread developer can be prevented from downloading and, therefore, the developer may be prevented from downloading even though the amount of developer within the developer device 4 has not increased. For this reason, a necessary amount of developer can be ensured within the developer device 4, and the developer can be supplied to the photoreceptor 1 stably. Therefore, the electrostatic latent image in the photoreceptor 1 can be correctly transformed into a toner image, an omission in the image and other defective images can be prevented, and excellent image formation can be carried out.

In addition, the developing device 4 of example 1 is provided with the blocking element 3 for blocking a straight line (L1 in fig. 8) that connects the lowest point of the developer discharge hole 94 (Q in fig. .8) and the top of the top of the supply screw 8 (P in fig. 8). The blocking element 3 is provided in a section facing the developer discharge hole 94. In addition, the developer discharged from the developer discharge hole 94 reaches the developer discharge hole 94 through the space surrounded by the separation wall 135 located at the bottom of the developer discharge hole 94, the blocking element 3, a side wall 3f located on the near side of the blocking element 3, and a side wall 3b located on the side away from the blocking element 3 By providing the blocking element 3 to cut the straight line L1, it is possible to prevent the developer from spreading from the top P of the top of the supply screw 8 in the tangential direction of a circumference drawn by a winged part , go through the developer discharge hole 94. In addition, as shown in fig. 8, since the blocking element 3 is arranged to cut the straight line L1 from the covering of the developing device 4 at the top of the supply transport path 9, the path can be prevented from blocking (arrow T in the Fig. 22) through which the developer scattered above the straight line L1 moves towards the developer discharge hole 94. Therefore, it can be safely prevented that the spread developer reaches the developer discharge port 94.

In addition, the blocking element 3 is an element whose lower surface is made of a rounded resin that follows the shape of the supply screw 8 at the top of the supply transport path 9. Since the blocking element has In a rounded way to follow the shape of the supply screw 8, the entire lower surface of the locking element 3 can approach the supply screw 8 to cover the entire supply screw 8. Therefore, the upper part of the supply screw 8 which causes the developer to spread is covered, so that the developer spread by the supply screw 8 can be prevented from rising to the developer discharge hole 94.

Therefore, as shown in fig. 12, since the blocking element 3 protrudes at the periphery of the developer discharge hole 94 of the supply transport path 9, the section of the supply transport path provided with the blocking element 3 becomes narrower than the supply transport path 9 on the upstream side in the direction of transport of the supply screw 8 with respect to the locking element 3. Therefore, the amount of developer in relation to the capacity of the supply transport path 9 it is greater in the position provided with the blocking element 3 than on the upstream side in the direction of transport with respect to the position provided with the blocking element 3. Therefore, in the vicinity of the lower end part in the direction of transport of the supply transport path 9 where the developer is no longer applied with a transport force, the developer ascends between the side wall of the element of b Locking 3 and the separation wall 135. Accordingly, the supply screw 8 is covered by the developer, and the developer is prevented from spreading due to the rotation of the supply screw 8. In addition, near the developer discharge hole 94, the change in the developer surface that occurs when the supply screw tilts when the upper part of the winged part of the supply screw 8 is exposed from the developer surface can be mitigated. Therefore, an accurate discharge can be expected with respect to the increase or decrease in the amount of developer within the developing device 4.

By providing such a blocking element 3, when the developer volume increases when the developer is supplied, the developer increase is poured through the developer discharge hole 94.

Note that in the developing device 4, the premixed toner is replenished in the developing device 4 by the toner refill control device (not shown), and that when the amount of developer within the developing device 4 increases, the volume of the developer near the downstream end in the direction of transport of the supply transport path 9.

Next, the fact that the volume of the developer near the downstream end in the direction of transport of the supply transport path 9 increases when the amount of developer within the developing device 4 increases.

In the developing device 4, the trends of the developer vary according to the change in the amount of developer to be transported by the stirring screw 11 when the premixed developer is replenished and according to the amount of developer to be supplied from the trajectory of agitation transport 10 to the supply transport path 9.

For example, if the amount of developer to be transported by means of the stirring screw 11, after the ready-mixed toner has been replenished, does not change significantly, the amount of developer to be supplied to the upstream side in the sense of Transport of supply transport path 9 does not change. In addition, if the amount of developer to be supplied from the agitation transport path 10 to the supply transport path 9 is close to the upper limit of the supply quantity when the developer has not been replenished, the amount of developer that is to be supplied to the upstream side in the direction of transport of the supply transport path 9 does not change significantly.

In the developing device 4 with the above configuration, even if the premixed toner has been replenished, the amount of developer to be transported through the supply transport path 9 does not change, and the amount of developer to be supplied from the supply transport path 9 to the developing roller 5 is substantially constant, whereby the amount of developer that is sent per hour near the downstream end in the direction of transport of the supply transport path 9 by Supply screw 8 does not change significantly.

On the other hand, in case the amount of developer to be transmitted through the agitation transport path 10 does not change significantly, the increased developer accumulates near the upstream end in the direction of transport of the transport path. of agitation 10 once the premixed toner has been replenished from the refill toner port 95. In case the amount of developer to be supplied from the agitation transport path 10 to the supply transport path 9 does not change, the developer increase accumulates in the agitation transport path 10 and near the upstream end in the direction of transport.

When the developer accumulates near the upstream end in the direction of transport, the developer in the agitation transport path 10 blocks the excess opening part 92 in which the developer is supplied from the supply transport path 9 to the agitation transport path 10. When the excess opening part 92 is blocked by the developer, the developer cannot move from the supply transport path 9 to the agitation transport path 10. However, the developer will constantly transported by means of the supply screw 8, the developer accumulates near the downstream end in the direction of transport of the supply transport path 9, whereby the volume of the developer increases. Then, when the volume of the developer accumulated near the downstream end in the direction of transport of the supply transport path 9 increases to the height level of the developer discharge hole 94, the developer P is discharged into the transport path of discharge 2 and then outside the developing device 4 through the discharge transport path 2.

In this configuration, when the agitation transport path 10 is filled with the developer, the developer is poured through the excess opening part 92 that supplies and transports the excess developer to the agitation transport path 10, the excess being transported from developer to the lowest flow in the direction of transport of the supply transport path 9 without being used for development. Accordingly, the displacement of the developer from the supply transport path 9 to the agitation transport path 10 can be regulated and as a result, the developer can be driven to the developer discharge hole 94 and discharged.

In this way, the amount of developer to be supplied from the agitation transport path 10 to the supply transport path 9 does not change significantly even if the amount of developer within the developing device 4 increases, but the developer within the development device 4 can be replaced by arranging the developer discharge port 94 at the downstream end in the direction of transport of the supply transport path 9.

In addition, once the premixed toner has been replenished, the amount of developer to be supplied to the upstream side in the direction of transport of the supply transport path 9 increases, but in some cases there is a limit to the amount of developer to be supplied from the supply transport path 9 to the agitation transport path 10.

In the developing device 4 having such a configuration, once the premixed toner has been replenished, the amount of developer to be transported to the agitation transport path 10 increases as the amount of developer increases, and the amount of developer to be supplied from the agitation transport path 10 to the supply transport path 9 also increases. Accordingly, the amount of developer to be supplied to the upstream end portion in the direction of transport of the supply transport path 9 increases, and the amount of developer to be transported within the supply transport path 9 also increases. However, since the amount of developer to be supplied from the supply transport path 9 to the developer roller 5 does not change, the amount of developer that arrives per hour near the downstream end in the direction of transport of the supply transport path 9 changes. In addition, if the amount of developer that arrives per hour near the downstream end in the direction of transport of the supply transport path 9 exceeds the upper limit of the amount of developer to be supplied per hour from the trajectory of Supply transport 9 to the agitation transport path 10, the developer accumulates near the downstream end in the direction of transport of the supply transport path 9 and, therefore, the volume of the developer increases. When the volume of the developer that accumulates near the downstream end in the direction of transport of the supply transport path 9 increases to the height level of the developer discharge hole 94, the developer P is discharged into the transport path of discharge 2 and then outside the developing device 4 through the discharge transport path 2.

Thus, even if the configuration in which the amount of developer to be delivered per hour from the agitation transport path 10 to the supply transport path 9 increases when the amount of developer within the development device 4 increases , the developer within the developing device 4 can be replaced by arranging the developer discharge port 94 at the downstream end in the direction of transport of the supply transport path 9.

As described above, by providing the developer discharge port 94 near the downstream end of the supply transport path 9, which is a section where the volume of the developer fluctuates according to the amount of developer within the delivery device. development 4, the developer within the development device 4 can be effectively replaced.

In addition, once the premixed toner has been replenished, that is, once the amount of developer on all developer transport paths has increased, the amount of developer to be supplied to the upstream side in the direction of transport of the supply transport path 9 increases. Accordingly, the developer discharge port 94 can be provided in any position in the direction of developer transport within the supply transport path 9. The reason is that the amount of developer to be supplied to the upstream side in the direction of transport of the supply transport path 9 increases because the developer volume increases in any position in the direction of transport of the developer within the supply transport path 9.

However, when the volume of the developer to be transported in the supply transport path 9 fluctuates irregularly in the configuration in which the developer discharge port 94 is provided in the middle of the width α of the supply region of the developer of the supply transport path 9, if a part of the developer having a large volume is discharged into the developer discharge port 94, there is a possibility that the section below the position provided with the discharge port of Developer 94 doesn't have enough developer. If a developer shortage occurs within the width α of the developer supply transport region of the supply transport path 9, sufficient developer cannot be supplied to the developer roller 5 and, therefore, the sufficient developer from the developer roller 5 to the photoreceptor 1, causing an omission in the image or other defective images. In response to this problem, the downstream end of the developer discharge port 94 is positioned outside the width α of the developer supply transport region by providing the developer discharge hole 94 near the downstream end of the trajectory of supply transport 9 and, therefore, a partial shortage of developer can be prevented.

By providing the locking element 3 as shown in fig. 8, the developer can be prevented from spreading and moving towards the developer discharge hole 94. However, when the amount of developer within the developing device 4 increases and, therefore, the volume of the developer increases towards the position in which the developer discharge hole 94 is provided, there is a possibility that the developer is blocked by the lower surface of the blocking element 3. If the developer is blocked by the lower surface of the blocking element 3 when the volume of the developer is increasing, the tension in the developer increases, deteriorating the developer.

However, using a sponge or other elastic material as the material of the blocking element 3, the volume of the developer increases until it reaches the lower surface of the blocking element 3, and the blocking element 3 deforms when the volume of the developer increases further . Such deformation can prevent the increase in tension in the developer that occurs when the developer is blocked by the lower surface of the blocking element 3.

Example 2

Next, the second example will be described (referred to as "example 2" hereinafter) which presents the characteristics of the developing device 4 of this embodiment 1.

Fig. 13 shows the configuration of the developing device 4 of this example 2.

Since the only difference between the configuration of Example 2 and the configuration of Example 1 is the shape of the spread developer prevention element spread and the rest of the configurations are identical, only the difference will be described.

As shown in fig. 13, in the developing device 4 of example 2, a plurality of plate-like elements 3a are arranged in intervals to obtain the spreading developer discharge prevention element. Even with such a configuration presenting the plate-like elements 3a, as blocking element 3 of example 1, it is possible to block the path through which the developer spread as a result of the transport operation of the supply screw 8 moves to the developer discharge hole 94. Therefore, the spread developer can be prevented from being discharged and the developer can also be prevented from being discharged even though the amount of developer within the developer device 4 has not increased . For this reason, a quantity of developer required within the developing device 4 can be guaranteed, and the developer can be supplied to the photoreceptor 1 stably. Accordingly, the electrostatic latent image of the photoreceptor 1 can be correctly transformed into a toner image, an omission in the image and other defective images can be prevented, and excellent imaging can be performed.

In addition, when the amount of developer within the developing device 4 increases and, therefore, the volume of the developer increases, the developer increase is introduced into a space between the elements as a plate 3a. Accordingly, the spreading effect of the developer can be safely removed without applying pressure to the developer, and only the increase in the developer can be conducted to the developer discharge hole 94. Each plate-like element 3a can be formed using a resin material highly rigid that does not easily deform, but an elastic material can be used. For example, polyethylene terephthalate (PET) polyethylene terephthalate having a thickness of 0.1 to 0.2 [mm] can be provided as a plate-like element 3a. According to such a configuration, when the developer spreads, the mylar serves as a wall so that the developer does not enter directly into the developer discharge hole 94, and when the developer volume increases, the mylar deforms and conducts the developer to the developer discharge hole

94.

The scattered developer discharge prevention elements of Example 1 and Example 2 described above are arranged to cut the straight line L1 from the top cover of the developing device 4 above the supply transport path 9. Although not part of the invention as defined in claim 1, another arrangement of scattered developer discharge prevention elements is shown in fig. 14, specifically a configuration in which the plate-like elements 3a that are not long enough to reach the straight line L1 are disposed within the upper covering. By using an element that blocks the space that serves as a path through which the spread developer moves toward the developer discharge hole 94, the spread developer can be prevented from ascending and reaching the developer discharge hole 94, as opposed to therefore of the developing device 4 without conventional spreading developer discharge prevention elements shown in fig. 22. Therefore, the shortage of the developer within the developing device 4 can be prevented and, therefore, the developer can be supplied to the photoreceptor 1 stably. Note that the spreading developer discharge prevention elements that are not long enough to reach the straight line L1 are not limited to the plate-like elements 3a shown in fig. 14. For example, the short block elements 3 shown in fig. 8.

In the configuration of the developing devices 4 shown in fig. 8, in fig. 13 and in fig. 14, the lowest point Q of the developer discharge hole 94 is located in a position higher than the top part P of the upper part of the supply screw 8. With respect to the position of the developer discharge hole 94, the lowest point Q of the developer discharge hole 94 is sometimes located in a lower position than the top part P of the upper part of the supply screw 8, as in the developing device 4 shown in fig. . 15. In the case of the developing device 4 shown in fig. 15, the scattered developer discharge prevention elements (the plate-like elements 3a in Fig. 15) are arranged to prevent the tangential line drawn from the lowest point Q of the developer discharge hole 94 to a circumference drawn by an end portion in the cross-sectional direction of the winged part of the supply screw 8. By thus arranging the spread developer prevention elements spread, the spread developer is prevented from ascending and passing through the opening of developer download 94, as in example 1 or example 2.

Example 3

The scattered developer discharge prevention elements of Example 1 and Example 2 described above mainly prevent the developer spread in the direction of rotation of the supply screw 8 from being discharged from the developer discharge hole 94.

In the supply transport path 9, the developer spreads not only in the direction of rotation of the supply screw 8 but also in the axial direction of the supply screw 8. Next, the third example will be described (referred to as " example 3 "hereinafter) which presents the characteristics of the developing device 4 of embodiment 1, in which the developer scattered in the axial direction of the supply screw 8 is prevented from being discharged.

Fig. 16 shows the configuration near the downstream end of the supply transport path 9 in the developing device 4 of example 3.

Since the only difference between the configuration of Example 3 and the configuration of Example 1 is the shape of the spread prevention prevention element spread and the rest of the configurations are identical, only the difference will be described.

As shown in fig. 16, in the developing device 4 of example 3, the upstream side in the direction of transport of the supply screw 8 with respect to the developer discharge hole 94 is provided, as a scattered developer discharge prevention element, with a upstream side wall element 38 having a wall surface 38f that is perpendicular to the transport direction of the supply screw 8 serving as a developer transport element (arrow S in fig. 16), and of a normal line whose direction extends in the opposite direction to the direction of the arrow S.

By providing the upstream side wall element 38, the developer T1 ascending in the direction of transport of the supply screw 8 from the upstream side in the direction of developer transport relative to the developer discharge hole 94 makes contact with the wall surface 38f of the upstream side wall element 38. Accordingly, it becomes possible to block the path through which the developer T1 ascending in the direction of transport of the axial direction of the supply screw 8 moves towards the developer discharge hole 94. Therefore, the developer T1 ascending in the direction of transport can be prevented from being discharged directly from the developer discharge hole 94.

In addition, as shown in fig. 16, in the developing device 4 of example 3, the downstream side in the direction of transport of the supply screw 8 with respect to the developer discharge hole 94 is provided, as a scattered developer discharge prevention element, with a downstream side wall element 39 having a wall surface 39f that is perpendicular to the transport direction of the supply screw 8 (arrow S in fig. 16), and of a normal line whose direction extends in the same direction that arrow S.

By providing the downstream side wall element 39, the developer T2 ascending in the opposite direction to the transport direction of the supply screw 8 from the downstream side in the direction of developer transport relative to the developer discharge hole 94 , makes contact with the wall surface 39f of the downstream side wall element 39. Accordingly, it becomes possible to block the path through which the developer T2 ascends in the opposite direction to the direction of transport of the axial direction of the Supply screw 8 travels to the developer discharge hole 94. Therefore, the developer T2 that ascends in the opposite direction to the direction of transport can be prevented from being discharged directly from the developer discharge hole 94.

In addition, a lower end portion of the upstream side wall 38e and a lower end portion of the downstream side wall 39e which are the lower ends of the wall elements of the upstream side wall element 38 and of the side waterside element below 39 respectively, are located below the lower end of the developer discharge hole 94, as shown in fig. 16. By arranging them in this way, it can be safely prevented that the developers (T1, T2) ascending in the axial direction of the supply screw 8 are discharged directly from the developer discharge hole 94.

The shape of the lower end portion of the upstream side wall 38e and the shape of the lower end portion of the downstream side wall 39e located at the lower ends of the upstream side wall element 38 and the downstream side wall element 39 respectively, are identical to the shape of the lower surface of the locking element 3 of example 1, that is, the rounded shape that follows the shape of the supply screw 8. Since the lower end portion of upstream side wall 38e and the lower end part of the downstream side wall 39e have a rounded shape to follow the shape of the supply screw 8, the lower end part of the upstream side wall 38e and the lower end part of the downstream side wall 39e can approaching the supply screw 8. By bringing the lower end portion of the upstream side wall 38e and the lower end portion of the downstream side wall 39e to the supply screw 8, it can be safely prevented that the developers (T1, T2) ascending in the axial direction of the supply screw 8 are discharged directly from the developer discharge hole 94.

It should be noted that if the developer discharge hole 94 is at the lower end in the direction of developer transport of the supply transport path 9, it can be sufficiently prevented that the developer ascending in the axial direction of the screw of Supply 8 is discharged directly from the developer discharge port 94, even if only the upstream side wall element 38 is present as a wall element.

In addition, in the developing device 4 of embodiment 1, the downstream side of the developer discharge hole 94 of the supply transport path 9 is provided with a downstream end wall surface that is perpendicular to the direction of transport of the supply screw 8 and of a normal line whose direction extends in the opposite direction to the transport direction of the supply screw 8, and which prevents the movement of the developer in the transport direction.

Fig. 17 shows a downstream end wall surface 9e.

As shown in Fig. 17, the downstream end wall surface 9e is provided on the downstream side of the developer discharge hole 94 in those in the supply transport path 9. The discharge hole of developer 94 is provided so that the developer sediments that are prevented from being transported and therefore accumulate and increase due to the downstream side wall surface 9e are trapped in the developer discharge hole 94. At arrange the developer discharge hole 94 so that the developer sediments are trapped therein, the developer sediments are discharged through the developer discharge hole 94 when the developer accumulates and rises on the upstream side of the downstream end wall surface 9e and, therefore, the volume of the developer increases. Therefore, the developer discharge port 94 can be prevented from becoming clogged due to the developer.

Note that in example 1 and example 2, an end surface at the downstream end in the direction of transport of the supply screw 8 in the coating that forms the supply transport path 9, functions as a wall surface of downstream end 9e. In addition, in example 3, the back of the wall surface 39f of the downstream side wall element 39 functions as the downstream end wall surface 9e.

The developer device 4 of this embodiment 1 has the developer discharge port 94 in the supply transport path 9, which is the developer supply transport path in which the developer is transported by the supply screw 8 which It serves as a developer transport screw for transporting the developer in the developer supply region of the developer transport path. In addition, the developer roller 5 serving as the developer carrier is disposed on the side where the winged part of the supply screw 9 moves from the lower side to the upper side as it rotates (right side in Fig. 8) . In addition, the developer discharge port 94 is disposed on the side where the winged part of the supply screw 8 moves from the upper side to the lower side as it rotates (left side in Fig. 8). By arranging the developer roller 5 on the side where the winged part of the supply screw 8 moves from the lower side to the upper side, the developer within the supply transport path 9 can be raised by the supply roller 5 and then stably supplied to the developer roller 5. Furthermore, by providing the developer discharge hole 94 on the opposite side of the developer roller 5 through the supply screw 8, the developer discharge hole 94 can be provided inside of the developer supply transport region α with respect to the axial direction of the supply screw 8, the developer supply transport region being a region that supplies the developer to the developer roller 5. Accordingly, the size can be reduced of the developing device 4.

[Embodiment 2]

In the embodiment 1 described above, the developing device 4 is described which is provided with the spread developer prevention elements scattered to prevent the spread developer from ascending and reaching the developer discharge hole 94, the developer being scattered to the transport the developer using the supply screw 8 that serves as the developer transport element. The configuration to prevent the developer from spreading and being discharged from the developer discharge hole 94 even if the amount of developer within the developer device 4 has not increased, can be configured to prevent the developer from spreading.

Next, the configuration of embodiment 2 will be described in which the developer is prevented from spreading and, therefore, is prevented from being discharged even if the amount of developer within the developing device has not increased.

Example 4

Next, the first example (referred to as "example 4" hereinafter) which presents the characteristics of the developing device 4 of embodiment 2 will be described.

It should be noted that the configuration of example 4 differs from the configuration of example 1 in that no spread developer prevention element is provided and in that the shape of the supply screw 8 is different, but the rest of the configurations are identical and, therefore, only the differences will be described.

Fig. 18 shows a lateral cross section of the developing device 4 of example 4.

As shown in fig. 18, the developing device 4 of example 4 has a rotation axis 8a, winged parts 8b which are provided in a spiral shape on the rotation axis 8a, and the supply screw 8 which serves as a developer transport screw for transporting the developer in the axial direction by rotating it. An external diameter R2 of the winged portion 8b within a developer discharge region η provided with the developer discharge port 94 with respect to the developer transport direction of the supply transport path 9 is smaller is an external diameter R1 of the winged part 8b located upstream side in the direction of developer transport of the developer discharge region η.

In the developing device 4 of example 4, the external diameter R1 of the winged part 8b on the water side in the direction of developer transport of the developer discharge region η is φ22 [mm], and the external diameter R2 of the winged part 8b within the developer discharge region η is φ18 [mm].

In Example 4, since the outer diameter R2 of the winged part 8b within the developer discharge region η is smaller than the outer diameter R1 of the winged part 8b located on the upstream side in the conventional developer sense In the developer download region η, the transport speed of the developer within the developer download region η can be slowed than the transport speed of the developer elsewhere. If the transport speed is low, the developer's driving force becomes weak, so that the developer does not spread easily. Furthermore, by making the outer diameter s small, the force of the developer that moves in the direction of the outer diameter of the winged parts 8b becomes weak, so that the developer does not readily disperse. In this way, the rotation of the supply screw 8 can prevent the developer from spreading in the developer discharge region η. Therefore, the spread developer cannot easily reach the developer discharge port 94 and its discharge is prevented. In addition, the developer is prevented from downloading even if the amount of developer within the developing device 4 has not increased. Therefore, a necessary amount of developer can be ensured within the developing device 4, and the developer can be stably supplied to the bearer of latent images.

Example 5

Next, the second example will be described (referred to as "example 5" hereinafter) which presents the characteristics of the developing device 4 of embodiment 2.

Example 5 differs from example 4 in regard to the shape of the supply screw 8 in the developer discharge region η, but the rest of the configurations are identical and, therefore, only the difference will be described.

Fig. 19 shows the configuration of the developing device 4 of example 5.

As shown in fig. 19, the developing device 4 of Example 5 has the axis of rotation 8a, the winged parts 8b which are provided in a spiral shape on the axis of rotation 8a, and the supply screw 8 which serves as the developer transport screw for transport the developer in the axial direction by rotating it. A thread passage P2 of the winged part 8b within a developer discharge region η provided with the developer discharge hole 94 with respect to the developer transport direction of the supply transport path 9, is narrower than a passage of thread P1 of the winged part 8b located on the upstream side in the direction of developer transport of the developer discharge region η.

In Example 5, since the thread pitch P2 of the winged portion 8b within the developer discharge region η is narrower than the thread pitch P1 of the winged portion 8b located on the upstream side in the conventional sense In the developer download region η, the transport speed of the developer within the developer download region η can be slower than the transport speed of the developer within another part. If the transport speed is slow, the driving force of the developer becomes weak, so that the developer does not spread easily. In this way, the rotation of the supply screw 8 can prevent the developer from spreading in the developer discharge region η. Therefore, the spread developer cannot easily reach the developer discharge port 94 and its discharge is prevented. In addition, the developer is prevented from downloading even if the amount of developer within the developing device 4 has not increased. Therefore, a necessary amount of developer can be guaranteed within the developing device 4, and the developer can be stably supplied to the bearer of latent images.

Example 6

Next, the third example (referred to as "example 6" hereafter) which presents the characteristics of the developing device 4 of embodiment 2 will be described.

Example 6 differs from example 4 in regard to the shape of the supply screw 8 in the developer discharge region η, but the rest of the configurations are identical and, therefore, only the difference will be described.

Fig. 20 shows a lateral cross section of the developing device 4 of example 6.

As shown in fig. 20, the developing device 4 of example 6 has the axis of rotation 8a, the winged parts 8b which are provided in a spiral shape on the axis of rotation 8a, and the supply screw 8 which serves as the developer transport screw for transport the developer in the axial direction by rotating it. The supply screw 8 within the developer discharge region η provided with the developer discharge hole 94 with respect to the developer transport direction of the supply transport path 9 does not have the winged parts 8b but the axis of rotation 8a .

In example 6, without the winged parts 8b within the developer discharge region η, the rotation of the supply screw 8 can prevent the developer from spreading in the developer discharge region η. Therefore, the spread developer cannot easily reach the developer discharge port 94 and its discharge from it is prevented. In addition, the developer is prevented from downloading even if the amount of developer within the developing device 4 has not increased. Therefore, a necessary amount of developer can be guaranteed within the developing device 4, and the developer can be supplied to the latent image carrier stably.

The developing device with the configuration described in embodiment 1 and the developing device with the configuration described in embodiment 2 can be combined.

For example, the developing device 4 with the blocking element 3 shown in fig. 8 you can use the supply screw 8 that does not have the winged parts 8b within the developer discharge region η, such as supply screw 8 shown in fig. 19. According to such a configuration, the spread developer can be safely prevented from downloading, and the developer can be downloaded in an amount as the developer volume increases.

In the developing device 4 which circulates the developer in a unidirectional manner and presenting the supply transport path 9, the agitation transport path 10 and the recovery transport path 7, the developer that reaches the downstream end at The transport direction of the supply transport path 9 is the excess developer that does not contribute to the development. In the developing device 4 which circulates the developer in a unidirectional manner, it is suitable that the developer augmented by the replenishment of the premixed toner is discharged in the position where the excess developer accumulates. The reasons will be described below.

Since the recovery transport path 7 transports the developer carried by the development roller 5 and is passed through the development region, the amount of developer transported within the recovery transport path 7 changes very little even if the amount of developer within the developing device 4 changes. Therefore, the developer cannot be downloaded due to the increase in developer volume.

In the agitation transport path 10, the amount of developer to be transported increases and, therefore, the volume of the developer increases as the amount of the developer within the development device 4 increases. However, even if the developer does not increase, the developer is discharged due to irregularities in the spread of the developer and in the amount of developer to be transported and, therefore, there is a possibility that a necessary amount of developer cannot be supplied to the supply transport path 9. For this reason, it is not appropriate to discharge the developer when the developer volume increases within the agitation transport path 10. In addition, the developer discharge configuration in the middle of the path of supply transport 9 is not appropriate due to the possibility that the volume of the developer increases even if the amount of developer within the developing device 4 does not increase and, therefore, a shortage of developer on the downstream side occurs in the direction of transport instead of in the position where the developer is unloaded.

For these reasons, in the developing device 4 which circulates the developer in a unidirectional manner, it is appropriate that an increase in the developer obtained by replenishing the premixed toner is discharged in the position where the developer accumulates until it reaches the downstream end in the direction of transport of the supply transport path 9.

In the developing device 4 of this embodiment, although the excess opening part 92 has a larger opening than the developer discharge hole 94, the developer discharge hole 94 may have a larger opening than the opening part of excess 92.

With reference to the configuration applied to the developing device 4 shown in fig. 4, the foregoing embodiments have described the configuration in which when the volume of the developer leaving in the vicinity of the downstream end in the direction of transport of the supply transport path 9 exceeds a predetermined height level, the discharge means Developer download part of this developer. The configuration to which the characteristics of the present invention can be applied is not limited to that shown in fig. 4 and, therefore, the features of the present invention can be applied in a similar manner to the developing device 4 having the configuration shown in fig. 6 and in fig. twenty-one.

In addition, the above embodiments have described the developing device that uses, as a developer, a two-component developer consisting of a carrier and a toner. The developing device to which the features of the present invention apply is not limited to the developing device that uses two component development. A developer device that uses a one-component developer can also be applied as long as it has a configuration in which the developer is replenished by the developer refueling means and an increase in the developer within the developer device is discharged by the download medium of developer.

As described above, according to embodiment 1, Example 1 presents the blocking element 3 as a prevention element for spreading the spread of the developer to block the path in which the developer spreads as a result of the transport operation of the supply screw 8 acting as a developer transport element travels towards the developer discharge port 94. Accordingly, the spread developer can be prevented from reaching the developer discharge hole 94 and is discharged therefrom, and the developer can be prevented from is discharged despite the fact that the amount of developer inside developer device 4 has not increased. Therefore, a necessary amount of developer can be ensured within the developing device 4, and the developer can be stably supplied to the bearer of latent images.

Also, the blocking element 3 is provided to block the straight line L1 that connects the lowest point Q of the developer discharge hole 94 with the top part P of the upper part of the winged part 8b of the supply screw 8. Accordingly, the developer that is scattered from the top P of the top of the supply screw 8 in the tangential direction of a circumference drawn by a winged part is prevented from passing through the developer discharge hole 94. On the other part, as shown in fig. 8, since the blocking element 3 is arranged so that it cuts the straight line L1 from the covering of the developing device 4 at the top of the supply transport path 9, the path can be prevented from blocking through which the developer scattered above the straight line L1 moves towards the developer discharge port 94 (arrow T in fig. 22). Therefore, it can be safely prevented that the spread developer reaches the developer discharge port 94.

Furthermore, using a sponge or other elastic material as the material of the blocking element 3, the volume of the developer increases until it reaches the lower surface of the blocking element 3, and the blocking element 3 deforms when the volume of the developer increases further. Such deformation can prevent the increase in tension in the developer that occurs when the developer is blocked by the lower surface of the blocking element 3.

On the other hand, in example 2, the plurality of plate-like elements 3a is arranged at intervals as prevention elements for spreading developer discharge. Therefore, when the amount of developer within the developing device 4 increases and thereby increases the volume of the developer, the developer increase is introduced into a space between the plate-like elements 3a. Therefore, the developer spreading effect can be safely removed without applying pressure on the developer, and only the developer increase can be conducted to the developer discharge hole 94.

In example 3, the upstream side in the direction of transport of the supply screw 8 with respect to the developer discharge port 94 is provided, as a scattered developer discharge prevention element, with an upstream side wall element 38 , which is a wall element with the wall surface 38f that is perpendicular to the transport direction of the supply screw 8 which serves as a developer transport element, and a normal line whose direction extends in the opposite direction to the transport direction of the supply screw 8. Accordingly, the developer T1 that ascends in the direction of transport of the axial direction of the supply screw 8 can be prevented from being discharged directly from the developer discharge hole 94.

On the other hand, in example 3, the downstream side in the direction of transport of the supply screw 8 with respect to the developer discharge hole 94 is provided, as a scattered developer discharge prevention element, with a wall element downstream side 39 which is a wall element with the wall surface 39f that is perpendicular to the transport direction of the supply screw 8 serving as a developer transport element, and a normal line whose direction extends in the same direction as the direction of transport of the supply screw 8. Accordingly, the developer T2 that ascends in the direction opposite to the direction of transport of the axial direction of the supply screw 8 can be prevented from being discharged directly from the developer discharge hole 94.

On the other hand, the downstream side of the developer discharge port 94 of the supply transport path 9 serving as a developer transport path is provided with a downstream end wall surface 9e that is perpendicular to the direction of transport of the supply screw 8 which serves as a developer transport element and a normal direction whose direction extends in the direction opposite to the transport direction of the supply screw 8, and which prevents the movement of the developer in the transport direction. The developer discharge hole 94 is provided so that the developer sediments that are prevented from being transported and therefore increased due to the downstream side wall surface 9e are trapped in the developer discharge hole 94. Therefore, the developer discharge port 94 can be prevented from becoming clogged due to the developer.

On the other hand, the lower end part of the upstream side wall 38e and the lower end part of the downstream side wall 39e which are at the lower ends of the wall elements of the upstream side wall element 38 and the downstream side wall element 39 respectively are placed below the lower end of the developer discharge hole 94. Therefore, the developers (T1, T2) that ascend in the axial direction of the supply screw can be safely prevented 8 are discharged directly from the developer discharge hole 94.

The developer transport element within the supply transport path 9 is the developer transport screw 8 which has the axis of rotation and the winged parts that are spirally provided on the axis of rotation and transports the developer in the rotational axial direction by rotating it. Therefore, the developer can be transported within the supply transport path 9 using the simple configuration.

On the flat surface that is perpendicular to the direction of transport of the supply screw 8 that serves as the developer transport screw, the shape of the lower end part of the upstream wall 38e and the shape of the lower end part of the downstream wall 39e located at the lower ends of the upstream side wall element 38 and the downstream side wall element 39 which serves as a scattering developer discharge element scattered respectively have a round shape so as to follow the shape of the upper part of the winged part of the supply screw 8. Accordingly, it can be safely prevented that the developers (T1, T2) ascending in the axial direction of the supply screw 8 are discharged directly from the developer discharge hole 94 .

The above example has the developer discharge hole 94 in the supply transport path 9, which is the developer supply transport path to which the developer is transported by the supply screw 8 which serves as the transport screw of developer to transport the developer to the developer supply region de of the developer transport path. Also, the developer roller 5 serving as the developer carrier is disposed on the side where the winged part of the supply screw 8 travels from the lower side to the upper side while rotating. Accordingly, the developer can be stably supplied to the developer roller 5. On the other hand, the developer discharge hole 94 is arranged on the side where the winged portion of the supply screw 8 travels from the upper side to the lower side while rotating, that is, on the side opposite to the developing roller 5 through the supply screw 8. Accordingly, the size of the developing device 4 can be reduced.

According to embodiment 2, example 4 has the axis of rotation 8a, the winged parts 8b which are provided in a spiral shape on the axis of rotation 8a and the supply screw 8 for transporting the developer in the rotational axial direction by means of rotation thereof, wherein the outer diameter R2 of the winged portion 8b within a developer discharge region  provided with the developer discharge port 94 with respect to the transport direction of the developer of the supply transport path 9 is smaller than the outer diameter R1 of the winged portion 8b located on the upstream side in the direction of developer transport of the developer discharge region . Therefore, the transport speed of the developer within the developer discharge region  can be made less than the transport speed of the developer within another part. If the transport speed is low, the developer's driving force becomes weak, so that the developer does not spread easily. On the other hand, by making the outer diameter small, the force of the developer moving in the direction of the outer diameter of the winged parts 8b becomes weak, so that the developer does not spread easily. In this way, the rotation of the supply screw 8 can prevent the developer from spreading in the developer discharge region . Therefore, the spread developer cannot easily reach the developer discharge port 94 and its discharge is prevented. In addition, the developer is prevented from downloading even if the amount of developer within the developing device 4 has not increased. Therefore, a necessary amount of developer can be ensured within the developing device 4, and the developer can be stably supplied to the bearer of latent images.

In addition, in example 5, the thread pitch P2 of the winged part 8b within the developer discharge region  is adjusted so that it is narrower than the thread pitch P1 of the winged portion 8b placed on the water side above in the conventional developer direction in the developer download region , and thus the transport speed of the developer within the developer download region  can be slowed down than the transport speed of the developer within another part, such as in the case of example 4. Therefore, as in the case of example 4, a necessary amount of developer can be secured within the developing device 4, and the developer can be stably supplied to the bearer of latent images.

In example 6, the supply screw 8 within the developer discharge region  has no winged parts 8b but a rotation axis 8a, and thus, as in the case of example 4, the transport speed of the developer within the developer discharge region  may be slower than the transport speed of the developer within another part. Therefore, as in the case of example 4, a necessary amount of developer can be secured within the developing device 4, and the developer can be stably supplied to the bearer of latent images.

The supply screw 8 provided in the developing device 4 presenting the configuration of the embodiment 2 can be applied to the developing device 4 presenting the configuration of the embodiment 1. Therefore, it can be safely prevented that the spread developer download, and the developer may also be prevented from downloading even if the amount of developer within the developing device 4 has not increased.

In the developing device 4 which circulates the developer in a unidirectional manner and presenting the supply transport path 9, the agitation transport path 10 and the recovery transport path 7, the developer is discharged into the position in the that the developer accumulates to reach the downstream end in the direction of transport of the supply transport path 9. Therefore, the increase in the developer obtained by replenishing the premixed toner can be properly discharged.

By providing the developing device 4 as the developing means of the copier serving as an image forming apparatus, the life of the developing means can be prolonged by replacing the developer, and at the same time the appearance of omission of images and other images can be prevented anomalous so that excellent imaging can be obtained.

MODIFICATION

Note that the developing devices 4 of embodiment 1 and embodiment 2 are configured so that the supply transport path 9 is disposed in a position higher than the agitation transport path 10 and that the transport path of recovery 7. Such a configuration is not limited to the developing device 4 to which the space saving configuration of the upper part of the developing device 4 shown in fig. 4. Next, a modification of the developing device will be described in which the three developer transport paths, ie the supply transport path 9, the agitation transport path 10 and the recovery transport path 7, They are arranged substantially at the same height. Note that since the only difference between the modification and the embodiment 1 is the shape of the developing device 4 and the rest of the configurations are identical, the developing device 4 will be described, which is the only difference.

Fig. 21 shows a schematic configuration of the developing device 4 according to this modification.

As shown in fig. 21, since the photoreceptor 1 rotates in the direction of the arrow G, the surface of the photoreceptor is charged by a scorchron charger 103. On the charged surface of the photoreceptor 1 an electrostatic latent image is formed by a laser beam irradiated from a exposure device, (not shown), and the toner is supplied from the developing device 4 to the latent image, whereby the toner image is formed.

The developing device 4 has a developing roller 5 that serves as a developer carrier that supplies the toner to reveal the latent image of the surface of the photoreceptor 1 during surface movement in the direction of the arrow I of the drawing. The developing device 4 also has a supply screw 8 which serves as a supply transport element for, during the delivery of the developer to the development roller 5, to transport the developer in the direction towards the rear side of fig. twenty-one.

A tangent blade 12 which serves as a developer adjustment element for regulating the thickness of the developer supplied to the developer roller 5 to a suitable thickness for the developer, is provided on the downstream side in the direction of the surface movement of the developer roller 5 from a part facing the supply screw 8.

A recovery screw 6 that serves as a recovery transport element for recovering the developer that has passed through the developing part and that has been used for the development and for transporting the recovered recovery developer in the same direction as the direction of the supply screw 8, is provided on the downstream side in the direction of the surface movement of the developing roller 5 from the developing part that constitutes a part facing the photoreceptor 1. The supply transport path 9 provided by the screw of supply 8 and the recovery transport path 7 provided by the recovery screw 6, are arranged parallel to each other below the development roller 5. The two transport paths, the supply transport path 9 and the transport path recovery 7, are separated by the separation wall 134 which serves as the separation element .

An agitation transport path 10 serving as the agitation transport path is provided in the developing device 4 in parallel with the opposite side of the recovery transport path 7 of the supply recovery path 9. The transport path of agitation 10 has the agitation screw 11 which serves as a stirring / transport element for, during agitation of the developer, to transport it in the opposite direction to that of the supply screw 8, the opposite direction being oriented on the near side in the drawing. The supply transport path 9 and the agitation transport path 10 are separated by a first separation wall 133 that serves as the separation element. An opening part is formed in the first separation wall 133 at both ends on the near side and on the far side of the drawing to connect the supply transport path 9 and the agitation transport path 10 to each other. To the path In excess of developer, excess developer is supplied which is supplied to the supply transport path 9 and which is transported to the downstream end in the direction of transport of the supply transport path 9 without being used for development, and the recovery developer that is transported by the recovery screw 6 towards the downstream end in the transport direction of the recovery transport path 7. The agitation transport path 10 agitates the excess developer supplied and the recovery developer and transport them to the downstream side in the direction of transport of the stirring screw 11. Then, the p Supply opening art 91 which is provided in the first separation wall 133 supplies the developer to the supply transport path 9 on the upstream side in the direction of transport of the screw 8.

In the second separation wall 134, the end on the far side of the schematic diagram that is located on the lower flow side in the transport direction of the recovery screw 6, is configured as an opening part to communicate the transport path supply 9 with the recovery transport path 7. The three transport paths, ie the downstream end in the transport direction of the recovery screw 6, the downstream end in the transport direction of the supply screw 8 , and the upstream end in the direction of transport of the stirring screw 11, are communicated with each other.

The recovery developer that is transported to the downstream end in the direction of transport of the recovery transport path 7 is transported to the supply transport path 9. In addition, the recovery developer and the developer that is transported by the screw of supply 8 but which has not been supplied to developer 5, are transported to the connected agitation transport path 10.

In the agitation transport path 10, the recovery developer, the excess developer and the refilled toner from a transport section according to the needs, are agitated and transported in the opposite direction to that of the developer of the recovery path 7 and of the supply path 9 by means of the stirring screw 11. The agitated developer is transported to the upstream side in the direction of transport of the supply transport path 9 which is communicated on the downstream side in the direction of transport. Note that a toner density sensor 127 is provided below the agitation transport path 10, and a toner refill device (not shown) is actuated by the output of the sensor so that the toner is replenished from the section of transport.

The coating of the developing device 4 is configured from a lower covering 112 and an upper covering 113 which are molded in a integral manner and divided into an upper part and a lower part by means of the shaft parts of the three transport screws. The first separation wall 133 is a part of the lower covering 112, and the second separation wall 134 is secured by the upper covering 113 and attached to the lower covering 112.

Note that a system using a known mohno pump can be adopted as a toner refill control device mentioned above. According to this system, there is no restriction on the installation positions of the toner cartridge, so this system is advantageous in terms of allocating space in the imaging apparatus. In addition, since the toner can be replenished periodically, it is not necessary to provide the developing device 4 with a large toner storage space. Therefore, a reduced size of the developing device 4 can be achieved.

As shown in fig. 21, an upper screw portion 114 of the supply screw 8, located at the highest part of the supply element, is disposed in a position lower than the center of rotation 115 of the developing roller 5. In the developing device 4, the angle θ1 between the straight line connecting the center of rotation 115 of the developing roller 5 with the top screw 114 and the horizontal straight line that passes through the center of rotation 115, is fixed at 30 [º]. The angle θ1 changes according to the diameter of the supply screw 8, but is preferably set between 10 [º] and 40 [º] in regard to the design in order to achieve a reduced size of the developing device 4.

The developer is supplied to the developer roller 5 since a magnetic pole provided within the developer roller 5 attracts the magnetic carrier contained in the developer. As described above, the upper screw portion 114 is disposed in a position lower than the center of rotation 115 of the developer roller 5, whereby the magnitude of the magnetic force contributes to the amount of developer supplied to the roller. developed, without presenting an effect of the weight of the developer on the amount of developer supplied to the developer roller 5. Accordingly, the developer to be transported by the supply transport path 9 is safely supplied from the top of the developer and, therefore, an appropriate amount of developer can be supplied to the developer roller 5 even if the volume of the developer in the supply transport path 9 is not uniform in the direction of transport of the supply screw 8.

In the developing device in which the three conventional developer transport paths are arranged at the same height, the supply opening part for supplying the developer from the agitation transport path 10 to the supply transport path 9 is provided outside the width α of the developing region. Therefore, in comparison with the developing roller 5 and the recovery transport path 7, the upstream end portions in the transport directions of the agitation transport path 10 and the supply transport path 9, They stand out greatly.

In the developing device 4 of the modification, since the supply opening part is provided within the width α of the developing region, such projections of the agitation transport path 10 and the supply transport path 9 which they are larger than those of the developing roller 5 and the recovery transport path 7 are eliminated, so that space saving in the developing device 4 can be achieved.

Furthermore, in the developing device 4 of the modification, since the recovery transport path 7, the agitation transport path 10 and the supply transport path 9 are arranged substantially at the same height, the tension generated in the Developer can be mitigated so that the developer's lifespan can be increased. Specifically, by providing all three developer transport paths at the same height, the developer does not have to rise in the developer transport paths, since the tension generated in the developer can be mitigated. Consequently, the deterioration of the developer can be prevented and can be maintained

5 nerse a stable image quality.

As described above, according to the present invention, the developer is prevented from unloading, even though the amount of developer within the developing device has not increased. Therefore, the present invention has the excellent effects that a necessary amount of developer can be ensured within the

10 developing device, and that the developer can be stably supplied to the bearer of latent images.

Various modifications will be possible for those skilled in the art after having received the teachings of the present description without departing from the scope of claim 1.

Claims (18)

1. A developing device (4), comprising: A developer carrier (5), which rotates while transporting a developer on a surface thereof, supplies a toner to a latent image on a surface of a latent image carrier (1) in a section where the developer carrier (5) it is facing the bearer of latent images (1), and that reveals the latent image; a developer transport path (9), which presents a developer transport element (8) that transports the developer, and transports the developer while supplying the developer to the developer carrier (5) in a developer supply region in the that the developer is supplied to the developer carrier (5); a developer discharge hole (94), which is provided in the developer transport path (9), and which discharges the developer outside the developer device, at a predetermined height level of a position at which the volume of the developer increases or decreases as the amount of developer in the developer transport path (9) increases or decreases; Y a spreader developer discharge prevention element (3) that is shaped to block a path through which the spreader developer as a result of a transport operation of the developer transport element (8) moves toward the discharge hole developer (94);  characterized because The spreading developer discharge prevention element (3) is provided to block a straight line path that connects the lowest point of the developer discharge hole (94) with the top of a top of a winged part ( 8b) of the developer transport element (8). 2. The developing device according to claim 1, further comprising: developer resupply means to replace the developer in the developer transport path (9).

3.

 The developing device (4) according to one of claims 1 or 2, wherein the developer transport element (8) is a developer transport screw having a rotation axis (8a) and a winged part (8b ) provided in a spiral shape on the axis of rotation (8a), and which conveys the developer in a direction of the axis of rotation (8a) by rotation.

Four.

 The developing device (4) according to claim 3, wherein a transport force of the winged part (8b) within a developer discharge region is smaller than a transport force of the winged part (8b) placed on an upstream side in the developer discharge direction of the developer download region.

5.

 The developing device (4) according to one of claims 1 to 4, wherein the scattered developer discharge prevention element (3) is made of an elastic material.

6.

 The developing device (4) according to one of claims 1 to 5, wherein the spread developer prevention element (3) is obtained by arranging a plurality of plate-like elements (3) in intervals.

7.

 The developing device (4) according to one of claims 1 to 6, wherein a wall element (38) having a wall surface (38f) that is perpendicular to the transport direction of the developer transport element ( 8) and a normal line whose direction extends in the opposite direction to the direction of transport of the developer transport element (8) is provided as a prevention element for the discharge of spread developer (3) on an upstream side in the direction of transport of the developer transport element (8), with respect to the developer discharge port (94).

8.

 The developing device (4) according to one of claims 1 to 7, wherein a wall element (38) having a wall surface (38f) that is perpendicular to the transport direction of the developer transport element ( 8) and a normal line whose direction extends in the same direction as the direction of transport of the developer transport element (8) is provided as a prevention element for the discharge of spread developer (3) on a downstream side in the direction of transport of the developer transport element (8), with respect to the developer discharge port (94).

9.

 The developing device (4) according to one of claims 1 to 8, further comprising, on a downstream side of the developer discharge port (94) within the developer transport path (9), a wall surface downstream end (9e), which is perpendicular to the transport direction of the developer transport element (8), a normal line whose direction extends in the opposite direction to the transport direction of the developer transport element (8), and that prevents the developer from moving in the direction of transport;

wherein the developer discharge port (94) is provided so that the developer sediments that are prevented from being transported and therefore rise due to the downstream end wall surface (9e), become trapped in the developer discharge hole (94).

10.

 The developing device (4) according to claim 7, wherein a lower end of the wall element (38) is located in a lower position than a lower end of the developer discharge hole (94).

eleven.

 The developing device (4) according to claim 3, wherein a lower end of the developer discharge prevention element scattered (3) on a flat surface perpendicular to the transport direction of the developer transport screw (8) has a rounded shape to follow the shape of an upper part of the winged part (8b) of the developer transport screw (8).

12.

 The developing device (4) according to claim 3;

wherein the developer discharge port (94) is provided within a developer supply transport path (9) through which the developer is transported by a supply screw (8) that serves as a transport screw of developer (8) transporting the developer in the developer supply region of the developer transport path (9); the developer carrier (5) is arranged on a side where the winged part (8b) of the supply screw moves from a lower part to an upper part as the supply screw (8) rotates; Y The developer discharge port (94) is arranged on one side where the winged part (8b) of the supply screw (8) moves from the top to the bottom as the supply screw (8) broken. 13. The developing device (4) according to one of claims 1 to 12, further comprising: a supply transport path (9) having a supply transport element (8) for transporting the developer along an axis line direction of the developer carrier (5) and for supplying the developer to the developer carrier (5); a recovery transport path (7) having a recovery transport element (6) for transporting the recovered developer from above the developer carrier (5) after the developer passes through the section facing the image carrier dormant (1), along the axis line direction of the developer carrier (5) and in the same direction as the direction of the supply transport element (8); Y an agitation transport path (10) having an agitation transport element (11) which is supplied with excess developer transported to the lower flow in the direction of transport of the supply transport path (9) without it has been used for development, and recovery developer recovered from the developer carrier (5) and transported to the lower flow in the direction of transport of the recovery transport path (7), and which conveys the excess developer and the recovery developer in the opposite direction to the direction of the supply transport element (8) while stirring the excess developer and the recovery developer, also supplying the agitation transport path (10) the agitated developers to the transport path supply (9); wherein the developer transport path is configured by said three developer transport paths, that is, the recovery transport path (9), the supply transport path and the agitation transport path (10), and presents the recovery transport element (6), the supply transport element (8) and the agitation transport element (11) as the developer transport element.

14.

 The developing device (4) according to claim 13, wherein the developer discharge orifice (94) is disposed near a downstream end in the developer transport direction of the supply transport path (9).

fifteen.

 The developing device (4) according to claim 3, wherein an outer diameter (R2) of the winged portion (8b) located within the developer discharge region provided with the developer discharge hole (94) is smaller that an outer diameter (R1) of the winged portion (8b) located on the upstream side in the direction of developer transport of the developer discharge region.

16.

 The developing device (4) according to claim 3, wherein a thread passage (P2) of the winged part (8b) located within the developer discharge region provided with the developer discharge hole (94) is more narrow that a thread pitch (P1) of the winged portion (8b) located on the upstream side in the direction of developer transport of the developer discharge region.

17.

 The developing device (4) according to claim 3, wherein the developer transport screw (8) located

within the developer discharge region provided with the developer discharge port (94) the winged part (8b) does not have. 18. An image forming apparatus, comprising: at least one latent image carrier (1); loading means for loading the surface of the latent image carrier (1); 10 latent imaging means to form an electrostatic latent image in the latent image carrier (1); Y a developing device (4) according to one of claims 1 to 17. 15