JP2017026649A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device with which it is possible to suppress unevenness in the rotation of a developer carrier.SOLUTION: An image formation device 1 comprises an electrostatic latent image carrier 50, a development unit 52, and a drive gear 81. The drive gear 81 drives the development unit 52. The development unit 52 includes a developer carrier 65, a driven gear 71, and a housing CS. The driven gear 71 is coupled to the drive gear 81 and rotates the developer carrier 65. The housing CS accommodates a developer and the developer carrier 65. The development unit 52 is capable of rotating around a revolving shaft 67 and is urged toward the electrostatic latent image carrier 50. The rotation shaft center 81C of the drive gear 81 is located at a position different from the shaft line 67AX of the revolving shaft 67 and located on a straight line SL passing through the shaft center 67C of the revolving shaft 67 and the rotation shaft center 71C of the driven gear 71.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus.

  The image forming apparatus described in Patent Document 1 includes a developing device, an electrostatic latent image carrier, and a drive gear. The developing device can rotate around a rotation axis and can approach or contact the electrostatic latent image carrier. The developing device includes a developer carrier and a driven gear. The developer carrying member is driven by a driven gear coupled to the driving gear.

JP-A-2-43581

  However, in the image forming apparatus described in Patent Document 1, the developer carrier is connected to the driven gear by a gear train. The gear train is formed by connecting a plurality of gears. Therefore, extremely small misalignments may be accumulated when the teeth of the gears connected to each other are engaged with each other. As a result, rotation unevenness may occur in the developer carrier. The rotation unevenness indicates that the rotation speed of the developer carrying member is not kept constant but varies slowly. Further, depending on the arrangement of the drive gear, rotation irregularity may occur in the developer carrying member regardless of the presence or absence of the gear train.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can suppress uneven rotation of a developer carrier.

  According to one aspect of the present invention, an image forming apparatus includes an electrostatic latent image carrier, a developing unit, and a drive gear. The electrostatic latent image carrier carries an electrostatic latent image. The developing unit develops the electrostatic latent image by attaching a developer to the electrostatic latent image. The drive gear drives the developing unit. The developing unit includes a developer carrying member, a driven gear, and a housing. The developer carrier carries the developer and supplies the developer to the electrostatic latent image carrier. The driven gear is connected to the driving gear and rotates the developer carrying member. The housing accommodates the developer and the developer carrier. The developing unit is rotatable around a rotation axis and is urged toward the electrostatic latent image carrier. The rotation axis of the drive gear is located at a position different from the axis of the rotation shaft, and is located on a straight line passing through the axis of the rotation shaft and the rotation axis of the driven gear.

  According to another aspect of the present invention, an image forming apparatus includes an electrostatic latent image carrier, a developing unit, and a drive gear. The electrostatic latent image carrier carries an electrostatic latent image. The developing unit develops the electrostatic latent image by attaching a developer to the electrostatic latent image. The drive gear drives the developing unit. The developing unit includes a developer carrying member, a driven gear, and a housing. The developer carrier carries the developer and supplies the developer to the electrostatic latent image carrier. The driven gear is connected to the driving gear and rotates the developer carrying member. The housing accommodates the developer and the developer carrier. The developing unit is rotatable around a rotation axis and is urged toward the electrostatic latent image carrier. The drive gear is disposed on the opposite side of the rotation shaft with respect to the driven gear.

  According to the present invention, uneven rotation of the developer carrying member can be suppressed.

1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view showing a developing device of an image forming apparatus according to an embodiment of the present invention. 2 is a cross-sectional view illustrating a developing device of the image forming apparatus according to the exemplary embodiment of the present invention. It is a perspective view showing a developing device of an image forming apparatus according to a comparative example. It is sectional drawing which shows the image development apparatus of the image forming apparatus concerning a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated.

  An image forming apparatus 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the image forming apparatus 1. The image forming apparatus 1 forms an image on the sheet P. In the present embodiment, the image forming apparatus 1 is a printer. The image forming apparatus 1 employs a tandem method and includes a feeding unit 10, a transport unit 20, an image forming unit 30, and a discharge unit 100.

  The feeding unit 10 includes a cassette 11 that stores a plurality of sheets P. The sheet P is, for example, a sheet made of paper or a synthetic resin. The feeding unit 10 feeds the sheet P from the cassette 11 to the conveyance unit 20. The conveyance unit 20 conveys the sheet P to the image forming unit 30. The image forming unit 30 forms an image on the sheet P. The conveyance unit 20 conveys the sheet P on which an image is formed to the discharge unit 100. The discharge unit 100 discharges the sheet P to the outside of the image forming apparatus 1.

  The image forming unit 30 includes an exposure unit 31, a unit 32a, a unit 32b, a unit 32c, a unit 32d, an intermediate transfer belt 33, a secondary transfer roller 34, and a fixing unit 35.

  The exposure unit 31 irradiates each of the units 32a to 32d with light based on the image data, and forms an electrostatic latent image on each of the units 32a to 32d.

  The unit 32a forms a yellow developer image based on the electrostatic latent image, the unit 32b forms a magenta developer image based on the electrostatic latent image, and the unit 32c based on the electrostatic latent image. A cyan developer image is formed, and the unit 32d forms a black developer image based on the electrostatic latent image.

  The intermediate transfer belt 33 rotates in the rotation direction R1. On the outer surface of the intermediate transfer belt 33, four color developer images are superimposed and transferred from the units 32a to 32d to form an image. The secondary transfer roller 34 transfers the image formed on the outer surface of the intermediate transfer belt 33 to the sheet P. The fixing unit 35 heats and pressurizes the sheet P to fix the image on the sheet P.

  Each of the units 32a to 32d includes a photosensitive drum 50 (electrostatic latent image carrier), a charger 51, a developing device 52 (developing unit), a primary transfer roller 53, a static eliminator 54, and a cleaner 55. The plurality of photosensitive drums 50 are in contact with the outer surface of the intermediate transfer belt 33 and are disposed along the rotation direction R1 of the intermediate transfer belt 33. The plurality of primary transfer rollers 53 are provided corresponding to the plurality of photosensitive drums 50, and face the plurality of photosensitive drums 50 via the intermediate transfer belt 33.

  In each of the units 32 a to 32 d, the charger 51, the developing device 52, the primary transfer roller 53, the static eliminator 54, and the cleaner 55 are sequentially arranged along the peripheral surface of the photosensitive drum 50.

  The photosensitive drum 50 rotates in the rotation direction R2. The charger 51 charges the peripheral surface of the photosensitive drum 50. Light is irradiated on the peripheral surface of the photosensitive drum 50 by the exposure unit 31 to form an electrostatic latent image. That is, the photosensitive drum 50 carries an electrostatic latent image.

  The developing device 52 attaches a developer to the electrostatic latent image, develops the electrostatic latent image, and forms a developer image on the peripheral surface of the photosensitive drum 50. That is, the photosensitive drum 50 carries a developer image.

  Further, the developing device 52 is detachably attached to the image forming apparatus 1 through an attachment / detachment port 12 formed in the image forming apparatus 1. The developing device 52 includes a developing roller 65 (developer carrier). In the state where the developing device 52 is mounted on the image forming apparatus 1, one end portion (hereinafter referred to as “first end portion”) of both end portions in the longitudinal direction of the developing roller 65 is an attachment / detachment port. 12 with respect to the other end of the developing roller 65 in the longitudinal direction (hereinafter referred to as “second end”). On the other hand, the second end of the developing roller 65 is located on the side of the attachment / detachment opening 12.

  The primary transfer roller 53 transfers the developer image carried by the photosensitive drum 50 onto the outer surface of the intermediate transfer belt 33. The static eliminator 54 neutralizes the peripheral surface of the photosensitive drum 50. The cleaner 55 removes the developer remaining on the peripheral surface of the photosensitive drum 50.

  The image forming apparatus 1 is a printer. However, the image forming apparatus 1 may be a copying machine, a facsimile, or a multifunction machine. The multi-function peripheral includes, for example, at least two devices among a copying machine, a printer, a facsimile, and a scanner. Further, the image forming apparatus 1 is compatible with color, but may be compatible with monochrome.

  Next, the driving of the developing device 52 will be described with reference to FIG. FIG. 2 is a perspective view showing the developing device 52.

  As shown in FIG. 2, the image forming apparatus 1 further includes a drive unit 80 and a drive gear 81. The drive unit 80 rotates the drive gear 81. The drive unit 80 includes, for example, a motor and a gear train. The drive gear 81 drives the developing device 52. The drive gear 81 is disposed on the first end portion 65 </ b> A side of the developing roller 65.

  In addition to the developing roller 65, the developing device 52 further includes a roller gear 66, a driven gear 71, a supply port 83, a discharge unit 85, and a housing CS. The roller gear 66, the driven gear 71, the supply port 83, and the discharge portion 85 are disposed on the first end portion 65A side of the developing roller 65. The supply port 83 is an opening for supplying the developer into the housing CS. The discharge unit 85 discharges the developer from the casing CS. This is for replacing the developer to extend the life. Specifically, the discharge unit 85 has a discharge port. Then, the developer is discharged from the discharge port. In addition, the discharge port does not appear in FIG.

  The roller gear 66 is attached to the first end 65 </ b> A of the developing roller 65. The roller gear 66 is connected to the driven gear 71. The driven gear 71 is connected to the driving gear 81. Therefore, when the drive gear 81 rotates, the driven gear 71 and the roller gear 66 rotate. As a result, the developing roller 65 rotates. That is, the driving gear 81, the driven gear 71, and the roller gear 66 rotate the developing roller 65. The drive gear 81, the driven gear 71, and the roller gear 66 are spur gears. However, in FIG. 2, the teeth of the drive gear 81 and the driven gear 71 are omitted for simplification of the drawing.

  According to this embodiment, the driven gear 71 is connected to the roller gear 66, and no gear train is disposed between the driven gear 71 and the roller gear 66. Therefore, the driven gear 71 and the roller gear 66 can be meshed with high accuracy. As a result, rotation unevenness of the developing roller 65 can be suppressed. That is, the rotation of the developing roller 65 can be stabilized.

  In FIG. 2, the first end 65A of the developing roller 65 appears, but the second end 65B of the developing roller 65 does not appear.

  Next, the internal structure of the developing device 52 will be described with reference to FIG. FIG. 3 is a cross-sectional view showing the developing device 52.

  As shown in FIG. 3, the developing device 52 further includes a first conveying screw 61, a second conveying screw 62, a rotating shaft 67, and an urging unit 69.

  The developing device 52 can rotate around the rotation shaft 67 and is urged toward the photosensitive drum 50 by the urging unit 69. As a result, the developing roller 65 is arranged at a fixed interval with respect to the photosensitive drum 50. Note that the developing roller 65 may be brought into contact with the photosensitive drum 50. The urging unit 69 has an elastic member (for example, a spring) and urges the developing device 52 by the elastic force of the elastic member.

  The housing CS accommodates the first conveying screw 61, the second conveying screw 62, the developing roller 65, and the developer. In this embodiment, the developer is a toner containing a magnetic material. The casing CS includes a first transport path 61a and a second transport path 62a that are substantially parallel to each other. The 1st conveyance screw 61 is arrange | positioned at the 1st conveyance path 61a. A second transport screw 62 is disposed in the second transport path 62a. The 1st conveyance screw 61 and the 2nd conveyance screw 62 are arrange | positioned substantially parallel.

  The first conveying screw 61 rotates and conveys the developer in the first conveying path 61a while stirring the developer. In addition, the second conveying screw 62 rotates and conveys the developer in the second conveying path 62a while stirring the developer. As a result, the developer is conveyed while circulating between the first conveyance path 61a and the second conveyance path 62a. The second conveying screw 62 supplies a developer to the developing roller 65.

  The developing roller 65 carries the developer and supplies the developer to the photosensitive drum 50. The developing roller 65 faces the second conveying screw 62 and is rotatably supported by the casing CS. Specifically, the developing roller 65 includes a sleeve 65S and a magnet 65M. The sleeve 65S is rotatable and has a cylindrical shape. The magnet 65M is fixed inside the sleeve 65S so as not to rotate. That is, the sleeve 65S rotates while the magnet 65M is stationary.

  Next, the arrangement of the drive gear 81 and the driven gear 71 will be described with reference to FIG. As shown in FIG. 3, the rotation axis 81 </ b> C of the drive gear 81 is located at a position different from the axis 67 </ b> AX of the rotation shaft 67. In addition, the rotation axis 81 </ b> C is located on a straight line SL that passes through the axis 67 </ b> C of the rotation shaft 67 and the rotation axis 71 </ b> C of the driven gear 71. Therefore, even when the position of the driven gear 71 is displaced along the arc CA, the change in the meshing state between the driving gear 81 and the driven gear 71 is small. As a result, according to this embodiment, the rotation unevenness of the developing roller 65 can be further suppressed. That is, the rotation of the developing roller 65 can be further stabilized.

  A driven gear 71 and a roller gear 66 are disposed between the driving gear 81 and the rotating shaft 67. The drive gear 81 is disposed on the opposite side of the rotation shaft 67 with respect to the driven gear 71. Therefore, a configuration that avoids the supply port 83 and the discharge portion 85 (for example, addition of a gear train) is unnecessary. As a result, according to the present embodiment, the rotation unevenness of the developing roller 65 can be further suppressed, and the cost can be reduced by reducing the number of parts. The driven gear 71 is disposed on the opposite side of the rotation shaft 67 with respect to the roller gear 66. Therefore, the driven gear 71 can be driven without providing a gear train between the roller gear 66 and the rotating shaft 67. As a result, it is possible to reduce the rotation unevenness of the developing roller 65 and reduce the cost by reducing the number of parts.

  In FIG. 3, the teeth of the drive gear 81, the driven gear 71, and the roller gear 66 are omitted for simplification of the drawing. The axis 67AX passes through the axis 67C.

  Next, the image forming apparatus 1 according to this embodiment and the image forming apparatus 200 according to the comparative example will be described with reference to FIGS. FIG. 4 is a perspective view showing the developing device 252 of the image forming apparatus 200 according to the comparative example. FIG. 5 is a cross-sectional view showing the developing device 252.

  As shown in FIGS. 4 and 5, the image forming apparatus 200 includes a developing unit 252, a driving unit 280, a driving gear 281, and a photosensitive drum 250. The developing device 252 includes a developing roller 265, a roller gear 266, a driven gear 271, a plurality of idle gears 273, a supply port 283, a discharge unit 285, a first conveying screw 261, and a second conveying screw 262. A rotation shaft 267, an urging portion 269, and a housing 254.

  The developing device 252 can rotate around the rotation shaft 267 and is urged toward the photosensitive drum 250 by the urging unit 269.

  The drive gear 281 is disposed such that the rotation axis 281C of the drive gear 281 is positioned on the axis 267AX of the rotation shaft 267. This is for suppressing rotation unevenness of the developing roller 265. The drive gear 281 is driven by the drive unit 280.

  Since the drive gear 281 is disposed on the axis 267AX, the driven gear 271 connected to the drive gear 281 is disposed between the roller gear 266 attached to the developing roller 265 and the drive gear 281. As a result, a plurality of idle gears 273 are arranged between the driven gear 271 and the roller gear 266 so as to avoid the supply port 283 and the discharge unit 285. Adjacent idle gears 273 are connected to each other. Of the plurality of idle gears 273, the lowest idle gear 273 is connected to the driven gear 271, and the uppermost idle gear 273 is connected to the roller gear 266.

  When the drive gear 281 rotates, the driven gear 271, the plurality of idle gears 273, and the roller gear 266 rotate. As a result, the developing roller 265 rotates.

  In the image forming apparatus 200 according to the comparative example, there may be a case where extremely small deviations are accumulated when the teeth of the idle gear 273 coupled to each other are engaged with each other. As a result, rotation unevenness may occur in the developing roller 265. In particular, the image forming apparatus 200 that forms a color image has a limited space, and thus it is necessary to provide many relatively small idle gears 273. Accordingly, in the image forming apparatus 200 for forming a color image, rotation unevenness is likely to occur in the developing roller 265 and the number of parts is increased as compared with an image forming apparatus dedicated to monochrome images.

  In contrast, as shown in FIG. 3, the image forming apparatus 1 according to the present embodiment does not include the idle gear 273. Therefore, the rotation unevenness of the developing roller 65 can be suppressed without depending on color and monochrome, and the cost can be reduced by reducing the number of parts.

  In addition, according to this embodiment, the rotation axis 81 </ b> C of the drive gear 81 is arranged on the straight line SL, so that the rotation of the developing roller 65 can be performed without providing the drive gear 81 on the axis 67 </ b> AX of the rotation shaft 67. Unevenness can be further suppressed.

  In the image forming apparatus 200 according to the comparative example, the driving mechanism (the driving gear 281, the driven gear 271, the plurality of idle gears 273, and the roller gear 266) and the developer loading / unloading mechanism (the replenishing port 283 and the discharging unit 285) Is arranged on the first end portion 265A side which is one end portion of both end portions of the developing roller 265. Therefore, in the comparative example, it is required to provide a plurality of idle gears 273 so as to avoid the developer entering / exiting mechanism. The replenishing port 283 is an opening for replenishing the developer to the developing unit 252, and the discharge unit 285 discharges the developer from the developing unit 252.

  In contrast, in the image forming apparatus 1 according to the present embodiment, both the driving mechanism (the driving gear 81, the driven gear 71, and the roller gear 66) and the developer loading / unloading mechanism (the replenishing port 83 and the discharging unit 85) are provided. Are disposed on the first end portion 65A side of the developing roller 65, the plurality of idle gears 273 are unnecessary. As a result, even when both the drive mechanism and the developer in / out mechanism are arranged on the first end portion 65A side of the developing roller 65, uneven rotation of the developing roller 65 can be suppressed and the number of parts can be reduced. Cost reduction can be realized.

  Further, in the image forming apparatus 200 according to the comparative example, the developing device 252 is detachably attached to the image forming apparatus 200 through an attachment / detachment opening formed in the image forming apparatus 200. Then, in a state where the developing device 252 is mounted on the image forming apparatus 200, the driving mechanism (the driving gear 281, the driven gear 271, the plurality of idle gears 273, and the roller gear 266) and the developer entering / exiting mechanism (the replenishing port 283 and The discharge unit 285) is located deeper in the image forming apparatus 200 than the attachment / detachment port. Therefore, even when the image forming apparatus 200 is opened, the developer entering / exiting mechanism is not exposed. As a result, the developer adhering to the developer loading / unloading mechanism can be prevented from entering the user's field of view.

  On the other hand, in a state where the developing device 252 is mounted on the image forming apparatus 200, the drive mechanism can be disposed behind the image forming apparatus 200 with respect to the attachment / detachment opening, and the developer loading / unloading mechanism can be disposed on the attachment / detachment opening side. In this case, since the plurality of idle gears 273 do not need to avoid the developer in / out mechanism, the number of idle gears 273 can be reduced. As a result, cost can be reduced. However, when the image forming apparatus 200 is opened, the developer entering / exiting mechanism is exposed. Therefore, the developer attached to the developer entering / exiting mechanism may enter the user's field of view. As a result, the user may feel uncomfortable.

  On the other hand, as shown in FIGS. 1 and 2, in the image forming apparatus 1 according to the present embodiment, the first end 65 </ b> A of the developing roller 65 with the developing device 52 attached to the image forming apparatus 1. Is located behind the second end 65 </ b> B of the developing roller 65 with respect to the attachment / detachment opening 12. Furthermore, the second end portion 65B is located on the side of the attachment / detachment port 12. In addition to the drive mechanism (drive gear 81, driven gear 71, and roller gear 66), the developer in / out mechanism (supply port 83 and discharge portion 85) is also arranged on the first end portion 65A side. Accordingly, not only the drive mechanism but also the developer entering / exiting mechanism is located behind the image forming apparatus 1 with respect to the attachment / detachment opening 12. As a result, even when the image forming apparatus 1 is opened, the developer entering / exiting mechanism is not exposed and the developer attached to the developer entering / exiting mechanism can be prevented from entering the user's field of view. In addition, since the idle gear 273 is not required, rotation unevenness of the developing roller 65 can be suppressed, and cost can be reduced by reducing the number of parts.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined. In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, interval, etc. of each component shown in the drawings are actual for convenience of drawing. May be different. In addition, the material, shape, dimensions, and the like of each component shown in the above embodiment are merely examples, and are not particularly limited, and various changes can be made without departing from the effects of the present invention. is there.

  For example, the drive gear 81 is disposed on the straight line SL, but may not be disposed on the straight line SL. If the drive gear 81 is disposed on the opposite side of the rotation shaft 67 with respect to the driven gear 71, a configuration that avoids the supply port 83 and the discharge portion 85 (for example, addition of a gear train) is unnecessary. For this reason, it is possible to realize reduction in rotation unevenness of the developing roller 65 and cost reduction by reducing the number of parts.

  The present invention relates to an image forming apparatus and has industrial applicability.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 12 Removable opening 50 Photosensitive drum (electrostatic latent image carrier)
52 Developer (Developer)
65 Development roller (developer carrier)
67 Rotating shaft 67C Shaft center 67AX Axis 71 Driven gear 71C Rotating shaft center 81 Drive gear 81C Rotating shaft center 83 Replenishment port 85 Discharge portion CS Housing

Claims (5)

An electrostatic latent image carrier carrying an electrostatic latent image;
A developing unit that attaches a developer to the electrostatic latent image and develops the electrostatic latent image;
A drive gear for driving the developing unit,
The developing unit is
A developer carrier for carrying the developer and supplying the developer to the electrostatic latent image carrier;
A driven gear connected to the driving gear and rotating the developer carrier;
A housing for housing the developer and the developer carrier,
The developing unit is rotatable around a rotation axis and is biased toward the electrostatic latent image carrier.
The rotation axis of the drive gear is located at a position different from the axis of the rotation shaft, and is located on a straight line passing through the axis of the rotation shaft and the rotation axis of the driven gear. .   The image forming apparatus according to claim 1, wherein the driving gear is disposed on an opposite side of the rotation shaft with respect to the driven gear. The developing unit further includes a replenishment port for replenishing the developer in the housing, and a discharge unit for discharging the developer from the housing,
The drive gear, the driven gear, the replenishing port, and the discharge portion are arranged on a first end portion side that is one end portion of both end portions in the longitudinal direction of the developer carrier. The image forming apparatus according to claim 1 or 2. The developing unit is detachable from the image forming apparatus through an attachment / detachment port formed in the image forming apparatus,
In a state in which the developing unit is mounted on the image forming apparatus, a second end that is the other end of the both ends of the developer carrier is located on the side of the attachment / detachment opening, and the first The image forming apparatus according to claim 3, wherein the end portion is located behind the second end portion with respect to the attachment / detachment port. An electrostatic latent image carrier carrying an electrostatic latent image;
A developing unit that attaches a developer to the electrostatic latent image and develops the electrostatic latent image;
A drive gear for driving the developing unit,
The developing unit is
A developer carrier for carrying the developer and supplying the developer to the electrostatic latent image carrier;
A driven gear connected to the driving gear and rotating the developer carrier;
A housing for housing the developer and the developer carrier,
The developing unit is rotatable around a rotation axis and is biased toward the electrostatic latent image carrier.
The image forming apparatus, wherein the driving gear is disposed on the opposite side of the rotation shaft with respect to the driven gear.

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