JP2006119549A - Toner carrying screw and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain good toner carrying performance even in the case an image forming apparatus is made small in size. <P>SOLUTION: The toner carrying screw 33 is used for the image forming apparatus for forming an image by developing an electrostatic latent image formed on a photoreceptor drum with toner as a toner image, then, directly or indirectly transferring the toner image to a recording paper. The toner carrying screw is provided with a rotating shaft 41 and a blade part 42 spirally arranged on the outer peripheral surface of the rotating shaft, and the blade part is provided with a plurality of blades 42a. The blade is formed to a nearly elliptical shape, and a rib 43 is integrally formed with the blade along the major axis direction of the blade. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus using an electrophotographic process such as a printer, a facsimile machine, or a copying machine, and more particularly to a toner conveying screw used in the image forming apparatus.

  In general, in an image forming apparatus using an electrophotographic process, an image is formed by a series of steps of charging, exposure, development, transfer, and cleaning. In such an image forming apparatus, toner is conveyed to the developing device. For this purpose, a toner conveying screw is provided, and further, a toner conveying screw for conveying the residual toner is provided in a cleaning unit for cleaning the toner remaining on the image carrier such as a photosensitive drum. Here, the cleaning unit will be outlined. Untransferred residual toner adhering to the surface of the photosensitive drum after the transfer step is scraped off by the cleaning blade and the rubbing roller in the cleaning unit, and the upstream of the photosensitive drum in the rotation direction. The toner is conveyed in a direction perpendicular to the photosensitive drum by the conveying roller arranged on the side, and then the residual toner is conveyed in the axial direction of the photosensitive drum by the toner conveying screw, and the residual toner is collected in the toner collecting container.

  In such a cleaning unit, in order to prevent scattering of residual toner at the time of cleaning, the conveying roller has an elliptical shape and is applied with a potential that is opposite to the charging potential of the residual toner. Yes (see Patent Document 1).

  Further, in order to efficiently collect the residual toner in the toner collection container, for example, as shown in FIG. 4, the toner collection device 1 includes a waste toner collection container 2 that contains toner, and a waste toner collection container 2. There is a toner conveying screw member 3 that conveys toner from the waste toner receiving port to the inside of the waste toner collecting container 2, and a paddle portion 3C is formed between the screw blade portions 3B of the toner conveying screw member 3. .

  On the other hand, a toner conveying screw is also used in the developing device. For example, in order to suppress the toner adhesion to the background portion on the photosensitive member where the toner should not adhere, the photosensitive member 4 has a structure as shown in FIG. And a first developer agitating member 6 and a second developer agitating member 7 for agitating and conveying the toner in the opposite front-rear direction along the developing sleeve 5, respectively. Between the developer stirring member 6 and the second developer stirring member 7, a partition member 8 having a shape that secures a communication path is provided at both ends, and the toner is circulated in a loop. The second developer agitating member 7 is formed with a taper screw portion 7a that becomes smaller as a whole as the outer diameter of the blade approaches the communication path on the side of transferring the toner to the first developer agitating member 6. The taper screw portion 7a is fitted with a guide member 7b whose inner diameter is tapered. The toner is compressed by the taper screw portion 7a, and the specific charge of the toner is increased by compression friction.

  Further, in order to stir at a high speed even if the amount of replenished toner is large, for example, as shown in FIG. 6, the developer having a carrier and toner is transported to the latent image carrier and supplied. A stirring screw 9 that stirs the toner and the developer. The stirring screw 9 has a relatively small-diameter helical screw 9a coaxially indicated by L1 and a relatively large-diameter helical screw 9b indicated by L2. The surface layer stirring means is provided with a small-diameter spiral screw and stirred while being conveyed by the surface so that the surface layer is sufficiently stirred without applying stress to the developer. I have to.

  In addition, in order to supply a predetermined amount of developer into the developing unit without excess or deficiency, as shown in FIG. 7, the supply port 11 provided in the hopper container bottom plate 10 is connected with a dome 12 whose both ends are opened. When the developer stored in the hopper container is guided into the dome 12 according to the rotation of the conveying screw 13 that covers and passes through the dome 12, the developer is supplied to the developer via the supply port 11. Some ribs 14 and 15 are provided between the blades of the conveying screw 13 located in the vicinity of the mouth in the developer conveying direction.

  Further, in order to easily balance the developer due to the difference in the developer conveyance speed in the developer circulation path, the developer conveyance speed in the developer circulation path by the first agent agitating and conveying member is set to a toner replenishing unit using a screw. Is faster than the transport speed of the agent agitating and circulating section using a large-diameter elliptical plate and the transport speed of the developer concentration detecting section using a small-diameter elliptical plate, However, there is one that is set so as to be faster than the conveyance speed of the developer concentration detection unit using a small-diameter elliptical plate.

Japanese Patent No. 3199614

  By the way, when downsizing an image forming apparatus such as a copying machine, it is necessary to reduce the diameter (diameter) of the toner conveying screw and the unit housing in which the toner conveying screw is accommodated. The toner conveying screw is preferably made of a resin that can be reduced in weight. On the other hand, the length in the longitudinal direction of the toner conveying screw and the unit casing (the length in the photosensitive drum axial direction) is determined by the size of the recording paper, and the length in the longitudinal direction of the unit casing and the toner conveying screw is increased. When the toner conveying screw is made of resin, the distance between the toner conveying screw and the inner surface of the unit housing is inevitably narrowed, and the toner is conveyed well due to toner friction. It becomes difficult.

  In any of the above-described conventional examples, when the image forming apparatus is downsized, the length of the unit casing and the toner conveying screw in the longitudinal direction is increased, the diameter is decreased, and the toner conveying screw is made of resin. Therefore, there is a problem that the decrease in toner transportability caused when the image forming apparatus is downsized cannot be improved. In other words, if the toner conveying screw is made of resin, warping tends to occur along the longitudinal direction, and if warping occurs, the toner conveying screw may come into contact with the inner surface of the unit housing, resulting in a decrease in toner conveying performance. There is a problem of doing it.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a toner conveying screw that can maintain good toner conveying property even if the image forming apparatus is downsized.

  Accordingly, in order to solve such a problem, the present invention provides a rotating shaft body and a rotating shaft in a toner conveying screw capable of conveying the toner used in an image forming apparatus that forms an image on recording paper or the like using toner. A blade portion spirally disposed on the outer peripheral surface of the body, a plurality of substantially elliptical blades provided in the blade portion, and integrally formed with the blade along the major axis direction of the blade It is characterized by providing the rib which was made.

  In the present invention, the rib has, for example, a substantially right triangle shape, and one of the two sides defining a right angle is positioned on the outer peripheral surface of the rotating shaft body and extends along the axial direction of the rotating shaft body, The other side of the two sides extends radially outward along the major axis of the blade. Moreover, you may make it make flat surface shape by notching the outer peripheral end of the major axis direction of the said blade | wing.

  According to the present invention, in an image forming apparatus that forms an image on recording paper or the like using toner, a toner transport screw that can transport the toner, a holding unit that rotatably holds the toner transport screw, A driving source for applying a driving force for rotation to the toner conveying screw, the toner conveying screw, a rotating shaft body, a blade portion disposed in a spiral shape on the outer peripheral surface of the rotating shaft body, An image forming apparatus comprising a plurality of substantially elliptical blades provided in the blade portion and ribs integrally formed with the blade along the blade is obtained.

  It is desirable that the rib be formed integrally with the blade along the substantially major axis direction of the blade.

  In the present invention, the rib has an outer peripheral surface of the rotating shaft body extending in the axial direction of the rotating shaft body, and the other side extending substantially in the radial direction of the position of the major axis of the blade. It has a triangular shape.

  In the present invention, the rib has, for example, a substantially right triangle shape, and one of the two sides defining a right angle is positioned on the outer peripheral surface of the rotating shaft body and extends along the axial direction of the rotating shaft body, The other side of the two sides extends radially outward along the major axis of the blade.

  In this invention, it is desirable to provide the flat surface part formed in the outer peripheral end of the position of the said substantially long diameter of the said blade | wing.

  As described above, in the toner conveying screw according to the present invention, the blades are formed in a substantially elliptic shape, and the ribs for reinforcing the blades are provided along the long diameter of the blades. As a result, the toner conveying screw is hardly warped, and the toner conveying screw does not come into contact with the inner surface of the unit casing, so that the toner conveying property is not lowered.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  First, an image forming apparatus using a toner conveying screw according to the present invention will be described with reference to FIG. Here, the toner conveying screw will be described as a toner conveying screw used in a cleaning unit that cleans and collects residual toner remaining on the photosensitive drum. However, the same applies to a toner conveying screw used in a developing device. Can be used.

  A charger 22, an exposure unit 23, a developing unit 24, a transfer unit 25, and a cleaning unit 26 are disposed around the photosensitive drum 21 serving as an image carrier, and the surface of the photosensitive drum 21 is charged by the charger 22. Then, the photosensitive drum 21 is exposed by the exposure unit 23 according to the image data, and an electrostatic latent image is formed on the surface of the photosensitive drum 21. The electrostatic latent image is developed by the developing device 24 to be a toner image.

  A toner image on the photosensitive drum 21 is transferred by a transfer unit 25 onto a recording sheet conveyed from a sheet feeding unit (not shown) via a sheet feeding path, and the recording sheet is conveyed to a fixing unit through a sheet conveyance path. Here, after the toner image on the recording sheet is fixed, the toner image is discharged to the discharge tray through the discharge path. After the transfer, the toner remaining on the photosensitive drum 21 is removed by the cleaning unit 26 and discarded in the toner recovery container 27.

  As shown in the figure, the cleaning unit 26 has a unit casing 31, in which a cleaner roller 32 and a toner conveying screw 33 are disposed, and the unit casing 31 has a cleaner blade. 34 and a scraper 35 are attached. In the illustrated example, the photosensitive drum 21 is rotationally driven in the direction indicated by the solid line arrow (clockwise) in the figure, and the cleaner blade 34 is disposed downstream of the cleaner roller 32 in the rotational direction of the photosensitive drum 21. The leading end is in contact with the surface of the photosensitive drum 21. On the other hand, the cleaner roller 32 is rotationally driven in the direction indicated by the solid line arrow (counterclockwise) in the drawing to rub the surface of the photosensitive drum 21.

  The scraper 35 is a sheet-like member. One end (base end) of the scraper 35 is fixed to the inner surface of the unit housing 31, and the other end (tip end) is in contact with the cleaner roller 32. The scraper 35 faces downward from the front end side to the base end side. It is arranged so as to be inclined. A toner conveying screw 33 is disposed on the upper side of the scraper 35 behind the cleaner roller 32. The inner surface of the unit housing 31 corresponding to the toner conveying screw 33 is formed in a cylindrical peripheral surface, and a slight gap exists between the outer peripheral end of the toner conveying screw 33 and the cylindrical peripheral surface. That is, the diameter of the toner conveying screw 33 is slightly smaller than the diameter of the cylindrical peripheral surface.

  Residual toner on the photosensitive drum 21 is cleaned by the cleaner roller 32, and residual toner that has not been removed by the cleaner roller 32 is further cleaned by the cleaner blade 34. In the illustrated example, the residual toner removed by the cleaner blade 34 falls on the cleaner roller 32. This residual toner is scraped off by the scraper 35 together with the residual toner removed by the cleaner roller 32, and the scraper is removed. It moves in the direction of the toner conveying screw 33 along the surface of 35. Then, the residual toner is conveyed in the direction of the toner collection container 27 by the toner conveying screw 33.

  FIG. 2 is a perspective view illustrating an example of the toner conveying screw 33, and FIG. 3 is a diagram illustrating the toner conveying screw 33 from the side. Referring to FIGS. 2 and 3, the illustrated toner conveying screw 33 includes a rotating shaft body 41 and a blade portion 42 arranged in a spiral shape on the outer peripheral surface of the rotating shaft body 41. 42 has a plurality of blades 42a. And the rotating shaft body 41 and the blade | wing part 42 are integrally resin-formed by injection molding.

  As described above, although the toner conveying screw 33 is made of resin (made of plastic) for cost and weight reduction, distortion may inevitably occur during molding, and this distortion is warped along the longitudinal direction. It will occur. Further, when the length of the toner conveying screw 33 in the longitudinal direction is long, the warp becomes large. As a result, the toner conveying screw 33 comes into contact with the inner surface of the unit housing 31 to generate a frictional noise, and the rotational torque of the toner conveying screw 33 is increased to deteriorate the toner conveying property.

  For this reason, here, the blades 42a have a substantially elliptical shape, and the ribs 43 are provided along the major axis thereof. That is, as shown in the drawing, the rib 43 is integrally formed with the rotary shaft body 41 and the blade portion 42 along the major axis of the blade 42a. The rib 43 has a substantially right triangle shape, and forms a right angle. One of the sides is positioned on the outer peripheral surface of the rotating shaft 41 and extends in the axial direction, and the other side extends radially outward along the major axis of the blade 42a.

  If the ribs 43 are provided along the long diameter in this way, the blade portions 42 are reinforced by the ribs 43, and the toner conveying screw 33 is hardly warped. The screw 33 does not come into contact with the inner surface of the unit casing 31, and the toner transportability does not deteriorate.

  Further, since the ribs 43 are provided corresponding to the long diameter portions, the ribs 43 can be enlarged. As a result, not only the function as a reinforcing material is enhanced, but also the ribs 43 can be easily formed. Further, since the ribs 43 are provided, even if the toner conveying screw 33 is warped, the toner conveying screw 33 is warped in the minor axis direction, so that the toner conveying screw 33 and the inner surface of the unit housing 31 are warped. There is no contact.

  Further, in the illustrated example, a cutout is provided in a part of the outer peripheral end of the blade 42a to form a flat surface 42b. That is, the outer peripheral end of the blade 42a corresponding to the long diameter is a flat surface 42b. If the flat surface 42b is formed in this way, even if the toner conveying screw 33 is slightly warped, the outer peripheral end is the flat surface 42a, and therefore the outer peripheral end of the long diameter portion is the outer end of the unit casing 31. There is no risk of contact with the inner surface, and toner transportability is not reduced. In other words, if a notch is formed at the outer peripheral end corresponding to the long diameter portion of the blade 42a, even if a slight warp occurs in the toner conveying screw 33, the outer peripheral end at the long diameter portion is at the unit housing. There is no risk of contact with the inner surface of the body 31, and the toner transportability does not deteriorate.

  In the above-described example, the toner conveying screw used in the photosensitive drum cleaning unit in the monochrome image forming apparatus has been described. However, the intermediate transfer drum cleaning unit in the color image forming apparatus having an intermediate transfer body such as an intermediate transfer drum. It can be similarly applied to the toner conveying screw used in the above.

  Since the blades are formed into an approximately elliptical shape and ribs are provided to reinforce the blades along the long diameter of the blades, the blades are reinforced by the ribs and the toner conveying screw is warped. As a result, the toner conveying screw does not come into contact with the inner surface of the unit casing and the toner conveying property is not deteriorated. As a result, the toner conveying screw can be applied to a screw for conveying toner in the image forming apparatus.

1 is a diagram schematically illustrating an image forming apparatus in which a toner conveying screw according to Embodiment 1 of the present invention is used. FIG. 2 is a perspective view showing a toner conveying screw shown in FIG. 1. FIG. 2 is a side view of the toner conveying screw shown in FIG. 1. FIG. 2 is a diagram illustrating an example of a toner recovery device used in an image forming apparatus. It is a figure for demonstrating an example of the developer stirring member used with a developing device. It is a figure for demonstrating an example of the stirring screw used with a developing device. It is a figure for demonstrating an example of the conveyance screw used with a developing device.

Explanation of symbols

21 Photosensitive drum 22 Charger 23 Exposure unit 24 Developer 25 Transfer device 26 Cleaning unit 27 Toner recovery container 31 Unit housing 32 Cleaner roller 33 Toner transport screw 34 Cleaner blade 35 Scraper 41 Rotating shaft 42 Blade portion 42a Blade 43 Rib

Claims (4)

In a toner conveying screw capable of conveying the toner used in an image forming apparatus for forming an image on a recording paper or the like using toner,
A rotating shaft body;
Blade portions disposed in a spiral shape on the outer peripheral surface of the rotating shaft body;
A plurality of substantially elliptical blades provided in the blade portion;
A toner conveying screw, comprising: a rib integrally formed with the blade along a major axis direction of the blade. In an image forming apparatus that forms an image on a recording sheet or the like using toner,
A toner conveying screw capable of conveying the toner;
A holding portion for rotatably holding the toner conveying screw;
A driving source for applying a driving force for rotation to the toner conveying screw,
The toner conveying screw is
A rotating shaft body;
Blade portions disposed in a spiral shape on the outer peripheral surface of the rotating shaft body;
A plurality of substantially elliptical blades provided in the blade portion;
An image forming apparatus comprising: a rib formed integrally with the blade along the blade.   The rib has a substantially triangular shape in which one side is the outer peripheral surface of the rotary shaft body and extends in the axial direction of the rotary shaft body, and the other side extends in the radial direction of the position of the major axis of the blade. The image forming apparatus according to claim 2.   4. The image forming apparatus according to claim 2, further comprising a flat surface portion formed at an outer peripheral end of the blade having a substantially long diameter.

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