JP2012042839A - Development device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a development device capable of simply and uniformly supplying a developer to individual portions of a developing roller from a developer supply member.SOLUTION: There is provided an image forming apparatus forming a quality image with density non-uniformity suppressed as that much by adopting such a development device for at least one development device. A buffer chamber 400 is disposed at a position proximity to a developer supply member 44 and upstream of a development region Da in the moving direction of the surface of a developing roller 41, and the buffer chamber 400 includes a mass regulating section 401 in proximity to the supply member 44 with a gap. Of the developer being supplied to the developing roller 41 from the supply member 44, an excessive amount of developer relative to an amount thereof required for developing an electrostatic image on a photoreceptor 1 is regulated by the mass regulating section 401, while an amount of shortage is supplied to the supply member 44 by an amount regulated by the mass regulating section 401.

Description

  The present invention relates to a developing device that develops an electrostatic latent image formed on an electrostatic latent image carrier by an electrophotographic method, an electrostatic recording static method, and the like, and an image forming apparatus including the developing device.

  Various types of developing devices for developing an electrostatic latent image formed on an electrostatic latent image carrier by an electrophotographic method or an electrostatic recording static method are known. Are classified into a dry developing apparatus using liquid and a wet developing apparatus using liquid developer. Today, dry developing devices are widely used.

  The dry developing device is a so-called one-component developing device that uses a toner-based developer, commonly referred to as a one-component developer, and a toner- and carrier-based developer that is commonly referred to as a two-component developer. Can be broadly classified into so-called two-component developing devices using the above.

  There are various types of dry developing devices in terms of their configuration, and in order to carry the developer to the developing area where the electrostatic latent image on the electrostatic latent image carrier is developed. And a developer supplying member that supplies developer to the developing roller. The developer supplying member is disposed in parallel with the developing roller and is rotated to drive the developer. Some are supplied to the developing roller while being conveyed in parallel with the developing roller. This type of developing device may be a one-component developing device, but is often found in a two-component developing device.

In any case, the developer supply member in this type of developing device is mainly of the screw conveyor type in which a spiral blade is provided around the rotation shaft, and therefore has the following difficulties.
That is, as shown in FIG. 3B, when the developer supply member is of a screw conveyor type in which a spiral blade is provided around the rotation shaft, the spiral blade is supplied to the developer conveyed along the developing roller. Unevenness of conveyance according to the pitch occurs, so that it is difficult to uniformly supply the developer to each part of the developing roller, and as a result, unevenness of image density may occur in the toner image to be developed and formed.

  As shown in FIG. 3C, there has been proposed a developer supply member in which not only a spiral blade but also a paddle is provided on a rotating shaft, but development in which not only a spiral blade but also a paddle is provided on a rotating shaft. Even when the agent supply member is employed, as shown in FIG. 3C, the developer conveyed along the developing roller was unevenly conveyed according to the spiral blade pitch and the paddle arrangement pitch.

  In this regard, for example, Japanese Patent No. 4269385, Japanese Patent Laid-Open No. 2007-102097, Japanese Patent Laid-Open No. 2007-86603, Japanese Patent Laid-Open No. 2006-337871, Japanese Patent Laid-Open No. 2006-154151, Japanese Patent Laid-Open No. 2006-259183 Describes a developing device which is devised to supply the developer uniformly to each part of the developing roller in the two-component developing device.

In Japanese Patent No. 4269385, a developer reservoir portion is provided in the developer transport path, and the developer reservoir portion suppresses fluctuations in the developer upper surface, commonly referred to as a developer liquid surface, with respect to the developing roller. Are listed.
Japanese Patent Application Laid-Open No. 2007-102097 describes that a developer supplying member facing a developing roller employs a rotating shaft provided with a plurality of spiral blades.

Japanese Patent Application Laid-Open No. 2007-86603 describes that a uniformizing member for equalizing a developer supply amount is disposed between a developing roller and a developer supplying member facing the developing roller.
Japanese Patent Laid-Open No. 2006-337871 describes that a magnet is arranged on the screw shaft, and the retention of the developer is prevented and the dispersibility is improved by a magnetic force in the longitudinal direction toward the developing roller.

Japanese Unexamined Patent Publication No. 2006-154151 describes that the developer supply member is swung in the axial direction while rotating.
Japanese Patent Laid-Open No. 2006-259183 describes that a developer height regulating member is disposed above the developer supply member on the developing roller side.

Japanese Patent No. 4269385 JP 2007-102097 JP 2007-86603 A JP 2006-337871 A JP 2006-154151 A JP 2006-259183 A

  However, like the developing device described in Japanese Patent No. 4269385 and Japanese Patent Application Laid-Open No. 2006-259183, the developer is supplied to the developing roller in a configuration in which the upper surface (liquid level) of the developer in the developing tank is kept constant. It is not possible to suppress the developer conveyance unevenness caused by the developer supply member.

  In the developing device described in Japanese Patent Application Laid-Open No. 2007-102097, it is necessary to increase the number of spiral blades of the developer supply member in order to suppress uneven developer supply to the developing roller. The original developer agitating function of the supply member and the conveying function are deteriorated.

In the developing device described in Japanese Patent Application Laid-Open No. 2007-86603, if there is a change in the liquid level of the developer in the developing tank, the developer supply unevenness cannot be suppressed.
In the developing device described in Japanese Patent Application Laid-Open No. 2006-337871, although there is an effect of suppressing uneven developer supply of the screw-type developer supply member, the carrier supply is restrained by a magnetic field, so that the developer supply amount decreases accordingly.

  As in the developing device described in Japanese Patent Application Laid-Open No. 2006-154151, in order to produce an effect of suppressing the developer supply unevenness by swinging the rotation shaft of the developer supply member, high-speed swing is required, which is difficult to realize. is there.

  Accordingly, the present invention provides a developing roller that can be driven to rotate and conveys the electrostatic latent image on the electrostatic latent image carrier to a developing area for developing the developer, and the developer that supplies the developer to the developing roller. A developer supply member that is arranged in parallel with the developing roller and is driven to rotate so as to feed the developer to the developing roller while being conveyed in parallel with the developing roller. It is a first object of the present invention to provide a developing device capable of easily and uniformly making the developer supply from the developer supply member to each part of the developing roller.

  The present invention also provides an image forming apparatus capable of forming an electrostatic latent image corresponding to a target image on an electrostatic latent image carrier and developing the electrostatic latent image with a developing device to form a toner image. Another object of the present invention is to provide an image forming apparatus capable of uniformizing the developer supply from the developer supply member to each part of the developing roller in at least one developing apparatus and forming a good image as much.

In order to solve the first problem, the present invention provides:
A rotation-driveable developing roller for carrying the developer and transporting the electrostatic latent image on the electrostatic latent image carrying member to a developing area; and a developer supplying member for supplying the developer to the developing roller And the developer supply member is disposed in parallel with the developing roller, and is a developing device that is driven to rotate and supplies the developer to the developing roller while being conveyed in parallel with the developing roller,
A buffer chamber facing the developer supply member upstream of the development area in the moving direction of the developing roller surface, the buffer chamber including a cut-out portion facing the developer supply member with a gap; The buffer chamber is a developer amount required for developing an electrostatic latent image on the electrostatic latent image carrier among the developers to be supplied to the developing roller from each part of the developer supply member. For the excess developer part, the excess part is damped by the scraping part and held in the buffer chamber, while for the insufficient developer part, the buffer chamber developer is scraped and measured by the scraping part. A developing device for discharging and supplying the developer supplying member is provided.

  In order to solve the second problem, the present invention forms an electrostatic latent image corresponding to a target image on an electrostatic latent image carrier, and develops the electrostatic latent image with a developing device to form a toner image. An image forming apparatus that can be formed, wherein at least one developing device is a developing device according to the present invention.

  According to the developing device of the present invention, immediately before the developer is supplied from the developer supply member to the developing roller, the excess portion is blocked by the cut-off portion of the buffer chamber at a portion where the developer is more than necessary, so that the buffer chamber The developer is supplied from the buffer chamber at the portion where the developer is insufficient and the developer is insufficient.

  More specifically, of the developer to be supplied to the developing roller from each part of the developer supply member, the amount of developer required for developing the electrostatic latent image on the electrostatic latent image carrier. For the excess developer part, the excess part is blocked by the scraping part and held in the buffer chamber, while for the lacking developer part, the buffer chamber developer is ground at the scraping part. The developer is supplied to the developer supply member.

  As described above, by adopting the buffer chamber having the cut-off portion, the developer is simply supplied uniformly to the developing roller in a state in which the developer amount unevenness is entirely suppressed.

  According to the image forming apparatus of the present invention, at least one developing device is the developing device according to the present invention, and in the developing device, the developer supply from the developer supply member to each part of the developing roller can be made uniform, A good image can be formed accordingly.

  In the developing device according to the present invention, the scraping portion can be exemplified by the case where it faces the developer supply member in a region above the horizontal plane including the rotation center axis of the developer supply member.

  As a typical example of the developer supply member, a screw conveyor type member in which a spiral blade is provided around a rotation shaft can be exemplified.

  As described above, according to the present invention, the developer roller that carries the developer and transports the electrostatic latent image on the electrostatic latent image carrier to the developing area for developing the developing roller and the developing roller are provided. A developer supplying member for supplying the developer, the developer supplying member being arranged in parallel with the developing roller, and being driven to rotate to convey the developer in parallel with the developing roller; A developing device that can easily and uniformly make the developer supply from the developer supply member to each part of the developing roller.

  According to the present invention, there is also provided an image forming apparatus capable of forming an electrostatic latent image corresponding to a target image on an electrostatic latent image carrier and developing the electrostatic latent image with a developing device to form a toner image. Thus, it is possible to provide an image forming apparatus capable of uniformizing the supply of the developer from the developer supply member to each part of the developing roller in at least one developing apparatus and forming a good image as much.

1 is a diagram schematically illustrating an example of an image forming apparatus according to the present invention. FIG. 2 is a diagram illustrating a configuration of a developing device in the image forming apparatus of FIG. 1. 3A and 3B are diagrams showing uneven developer supply to each part of the developing roller. FIG. 3A shows the case of the developing device according to the present invention, and FIG. 3B shows the case of the conventional developing device example. FIG. 3C shows the case of the developing device of FIG. 3B in which the developer supply member is also provided with a paddle.

  Hereinafter, an example of an image forming apparatus according to the present invention and an example of a developing apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the configuration of an example of an image forming apparatus according to the present invention.
An image forming apparatus 10 shown in FIG. 1 is an electrophotographic image forming apparatus that forms a monochrome image on a recording sheet S such as recording paper.

  The image forming apparatus 10 includes a drum-type photoconductor 1, and a charger 2, an image exposure device 3, a developing device 4, a transfer roller 5, and a cleaning device 6 are arranged around the photoconductor 1 in this order. . In addition to these, the image forming apparatus 10 includes a recording sheet supply unit (not shown), and the fixing device 7 and the sheet are disposed downstream of the transfer roller 5 in the conveyance direction of the sheet S supplied from the recording sheet supply unit. A discharge tray (not shown) is provided.

The photoreceptor 1 is a negatively chargeable photoreceptor, and the surface of the photoreceptor 1 can be uniformly charged to a predetermined negative potential.
The image exposure device 3 forms an electrostatic latent image corresponding to an image to be formed by exposing the photosensitive member charged area by the charger 2 to an image to be formed. Image exposure is performed according to image information provided from a machine or the like.

  The developing device 4 is a two-component developing device that develops an electrostatic latent image on the photoreceptor 1 using a two-component developer containing toner and a magnetic carrier. The electrostatic latent image is developed by reversal development with negatively charged toner. A visible toner image is obtained. The developing device 4 will be further described later.

According to the image forming apparatus 10, a toner image can be formed on the sheet S as follows.
The surface of the photosensitive member 1 that is driven to rotate clockwise in the drawing by a photosensitive member driving motor (not shown) is uniformly charged to a predetermined potential by a charger 2 to which a charging voltage is applied from a charging power source (not shown). . An image is exposed from the image exposure device 3 to the charged area to form an electrostatic latent image corresponding to the image to be formed, and the electrostatic latent image is developed by the two-component developing device 4 to form a toner image.

  On the other hand, the recording sheet S is supplied from a recording sheet supply unit (not shown) to the timing roller TR, and the recording sheet S is transferred to the photoreceptor 1 at the timing at which the toner image is transferred to the image formation target area by the timing roller TR. It rushes into and passes through the transfer part between the rollers 5. At this time, a transfer voltage is applied to the transfer roller 5 from a transfer power supply (not shown), and the toner image on the photoreceptor 1 is transferred to the sheet S.

The recording sheet S to which the toner image has been transferred in this manner passes through the fixing device 7 so that the toner image is fixed under heat and pressure, and is discharged to the sheet discharge tray.
The surface of the photoreceptor 1 after the toner image transfer is cleaned by a cleaning device 6 and is prepared for the next image formation.

The two-component developing device 4 will be further described.
FIG. 2 shows a schematic sectional structure of a two-component developing device 4 employed in the image forming apparatus of FIG.

  The developing device 4 includes a developing housing 40 containing a so-called two-component developer D including toner and a magnetic carrier, a developing roller 41 rotatably attached to the developing housing 40, and a magnetic field generator 42 built in the developing roller 41. And a developer regulating member 43 that is provided adjacent to the developing roller 41 with a developer amount regulating gap g1 therebetween.

  The developing roller 41 is a member in the form of a sleeve and is also referred to as a developing sleeve, and the surface has an appropriate roughness for transporting the developer D by blasting or the like. Although not limited thereto, the outer diameter is 16 mm in this example.

  The developing roller 41 faces the photosensitive member 1 through an opening opened toward the photosensitive member 1 of the developing housing 40, and can be driven to rotate clockwise CW in FIG. 2 by a developing motor (not shown). is there. The developing roller 41 is formed long in the direction of the rotation center line CL so as to correspond to the width in the direction perpendicular to the conveyance direction of the recording sheet S on which an image is formed.

  The developing device 4 further includes a pair of developer conveying members 44 and 45. The developer transport members 44 and 45 transport the developer along the longitudinal direction (the direction of the rotation center line CL) of the developing roller 41 while stirring the developer (thus charging the toner frictionally). The developer is distributed to each part that should hold the developer.

  The developer conveying members 44 and 45 are rotatably disposed in the developing housing 40 in parallel with the developing roller 41. In this example, the developer conveying member 44 is a screw conveyor type conveying member in which a spiral blade 442 is provided around a shaft 441, and can be rotationally driven by a developing motor (not shown) via a transmission mechanism.

  The developer conveying member 45 is rotatably disposed in the developing housing 40 in parallel with the conveying member 44. In this example, the developer conveying member 45 is also a screw conveyor type conveying member in which a spiral blade 452 is provided around the shaft 451, and can be rotationally driven by a developing motor (not shown) via a transmission mechanism.

  Each of the conveying members 44 and 45 has an outer diameter of 16 mm, a shaft diameter of 6 mm, and a spiral blade (screw) pitch of 25 mm.

  In FIG. 2, the developer D is transported from the near side to the far side by one transport member 44, and the other side is opened from an opening (not shown) formed in the rear side portion of the partition wall 46 provided between the both transport members. It moves to the conveying member 45, is conveyed from the back side to the near side by the conveying member 45, and is circulated and conveyed so that it moves from the opening (not shown) formed in the near side portion of the partition wall 46 to the conveying member 44. .

  The conveying member 44 facing the developing roller 41 distributes and supplies the developer to each part of the developing roller while conveying the developer D along the longitudinal direction of the developing roller 41. The conveying member 44 is a so-called developer supply member that supplies the developer to the developing roller 41.

   The magnetic field generator 42 adsorbs the developer D used for development in the developing housing 40 to the surface of the developing roller 41, but returns to the developing housing 40 while being adsorbed on the developing roller 41 without being developed. The low magnetic field LM for separating the developer D from the developing roller 41 is provided.

  More specifically, the magnetic field generator 42 is not limited thereto, but in this example, the permanent magnets are combined and arranged in a roll shape, and have S and N poles as magnetic poles on the peripheral surface. .

The magnetic field generator 42 uses, as magnetic poles, the catch pole S2 that sucks up the developer D to the developing roller 41, the regulation pole N2 at a position corresponding to the regulation member 43, and the developer that has passed through the developer amount regulation gap g1 by the regulation member 43. A repulsive magnetic field is formed between the transport pole S1 for transporting the electrostatic latent image on the photoreceptor 1 to the development area Da for developing, the development pole N1 corresponding to the development area Da, and the catch pole S2. The developer separation pole S3 that forms the low magnetic field LM is provided.
The magnetic pole arrangement in the magnetic field generator 42 is not limited to this. It is possible to employ other magnetic pole arrangements within a range that does not hinder electrostatic latent image development.

  The developing device 4 further includes a buffer chamber 400 that holds excess developer. The buffer chamber 400 is formed above the developer transport member 44 that supplies a developer to the developing roller 41 using a part of the developing housing 40. The buffer chamber 400 is partitioned by a plate-shaped partition 401 on the side facing the regulating member 43.

  The partition portion 401 faces the developer supply member 44 in a region above the horizontal plane including the rotation center axis CL ′ of the developer supply member 44, and with respect to the developer supply member 44 (with respect to the rotation region of the member 44). In this example, a gap g2 of 1 mm is set.

  The partition portion 401 is also a scraping portion that can measure the developer supply amount by passing the developer D to be supplied to the developing roller 41 under the rotation of the conveying member 44 under the self. In FIG. 2, the solid line arrow indicates the rotation direction of the member, and the dotted line arrow indicates the general flow state of the developer.

According to the developing device 4, the developer adsorbed on the surface of the developing roller 41 by the magnetic force of the catch pole S <b> 2 of the magnetic field generator 42 is conveyed to the developer amount regulating gap g <b> 1 under the action of friction force by the rotation of the developing roller 41. Therefore, it is regulated to a predetermined amount and conveyed to the development area Da in the form of a spike of developer, and is used for developing the electrostatic latent image on the photoreceptor 1.
The developer D returning to the developing housing 40 while being held by the developing roller 41 without being consumed in the developing area Da is peeled off from the developing roller 41 in the low magnetic force area LM.

  It should be noted here that the developing device 4 is provided with a buffer chamber 400 having a cut-out portion 401.

  According to the developing device 4, immediately before the developer D is supplied from the developer supply member 44 to the developing roller 41, an excessive amount of developer is blocked by the scraping portion 401 of the buffer chamber 400 in a portion where the developer D is more than necessary. Thus, the developer D is supplied from the buffer chamber 400 in the portion where the developer D is accumulated and the developer D is insufficient.

  More specifically, of the developer to be supplied from each part of the developer supply member 44 to the developing roller 41, the developer is excessive with respect to the amount of developer required for developing the electrostatic latent image on the photoreceptor 1. With respect to the portion, the excess portion is blocked by the scraping portion 401 and held in the buffer chamber 400, while the developer portion that is insufficient is developed to the extent that the developer in the buffer chamber 400 is ground and measured by the scraping portion 401. It is supplied to the agent supply member 44.

Thus, by adopting the buffer chamber 400 having the scraping portion 401, as shown in FIG. 3A, the developer height at the developer supply position from the developer supply member (developer transport member) 44 to the developing roller 41 is increased. The developer can be uniformly supplied to the developing roller 41 in a state where unevenness in the developer amount is suppressed as a whole.

  In addition, by adopting a simple configuration in which the buffer chamber 400 having the scraping portion 401 is adopted, the developer can be uniformly supplied to the developing roller 41 in a uniform manner with the developer amount unevenness being suppressed as a whole. Can do.

  Further, according to the image forming apparatus 10, since the developing device 4 is employed, in the developing device 4, the developer supply from the developer supply member 44 to each part of the developing roller 41 can be made uniform, resulting in uneven developer supply. A good image can be formed while suppressing occurrence of uneven image density.

here,
(1) Experimental examples 1 and 2 in which image formation was performed using the image forming apparatus of the type shown in FIG. 1 employing the developing device 4 and it was visually checked whether or not unacceptable image density unevenness occurred. 2) In the developing device 4, an image is formed using the image forming device of the type shown in FIG. 1 which employs a developing device without the buffer chamber 400, and it is visually checked whether or not unacceptable image density unevenness has occurred. The results of Comparative Experimental Examples 1 and 2 are summarized in the following table.

In the following table, the particle size of the toner in the developer is 6.5 μm. “◯” indicates that there is no density unevenness, and “X” indicates that there is density unevenness.
As can be seen from the following table, it is understood that the occurrence of image density unevenness can be suppressed by employing the developing device 4 including the buffer chamber 400 having the scraping portion 401.

Developer 1 used Developer 2 used
Carrier 1 (particle size 20 μm) Carrier 2 (particle size 50 μm)
Number of Images Formed Experimental Example 1 Comparative Experimental Example 1 Experimental Example 2 Comparative Experimental Example 2
(10,000 sheets) 0 ○ ○ ○ ○
5 ○ × ○ ×
10 ○ × ○ ×

The image forming apparatus described above is a monochrome image forming apparatus, but the present invention can also be applied to a so-called tandem type, cycle type color image forming apparatus. In that case. One or more of the plurality of developing devices can be used as the developing device according to the present invention.
The developing device described above is a two-component developing device, but the present invention can also be applied to a one-component developing device using a one-component developer.

  The present invention provides a developing device that can easily uniformize the developer supply from the developer supplying member to each part of the developing roller, and adopts such a developing device as at least one developing device, thereby suppressing density unevenness accordingly. The present invention can be used to provide an image forming apparatus that can perform good image formation.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus S Recording sheet 1 Photoconductor 2 Charger 3 Image exposure apparatus 5 Transfer roller 6 Cleaning apparatus 7 Fixing apparatus TR Timing roller 4 Two-component developing apparatus 4
40 Developing housing 41 Developing roller 42 Magnetic field generator S2 Catch pole N1 Restricting pole S1 Conveying pole N2 Developing pole S3 Separating pole 43 Developer regulating member 44, 45 Developer conveying member 441, 451 Shaft 442, 452 Spiral blade 46 Between conveying member Partition wall 400 Buffer chamber 401 Partition part (grinding part)
D Developer g1 Developer amount regulating gap g2 Gap between scraping portion 401 and development supply member 44 Da Development area

Claims (4)

A rotation-driveable developing roller for carrying the developer and transporting the electrostatic latent image on the electrostatic latent image carrying member to a developing area; and a developer supplying member for supplying the developer to the developing roller And the developer supply member is disposed in parallel with the developing roller, and is a developing device that is driven to rotate and supplies the developer to the developing roller while being conveyed in parallel with the developing roller,
A buffer chamber facing the developer supply member upstream of the development area in the moving direction of the developing roller surface, the buffer chamber including a cut-out portion facing the developer supply member with a gap; The buffer chamber is a developer amount required for developing an electrostatic latent image on the electrostatic latent image carrier among the developers to be supplied to the developing roller from each part of the developer supply member. For the excess developer part, the excess part is blocked by the scraping part and held in the buffer chamber, while for the insufficient developer part, the buffer chamber developer is ground and measured by the scraping part. And a developer supply member.  The developing device according to claim 1, wherein the scraping portion faces the developer supply member in a region above a horizontal plane including a rotation center axis of the developer supply member.   The developing device according to claim 1, wherein the developer supply member is a screw conveyor type member having a spiral blade provided around a rotation shaft. An image forming apparatus capable of forming an electrostatic latent image corresponding to a target image on an electrostatic latent image carrier and developing the electrostatic latent image with a developing device to form a toner image, at least one developing device An image forming apparatus according to claim 1, wherein the image forming apparatus is a developing device according to claim 1.