JP2011085764A - Driving device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving device and an image forming apparatus which prevent misalignment of an image to be transferred to a moving member or a recording medium from image carriers when a plurality of image carriers and one moving member are driven with one driving source. <P>SOLUTION: A driving unit 70 has one motor 72, a first gear train 80 that rotates a plurality of photoreceptors 34, a second gear train 90 that rotates a driving gear 96 for driving an intermediate transfer belt 32, a speed setting gear 92 for setting relative speed of a driving roll 54 and the photoreceptors 34, and an adjusting gear 94 that adjusts rotation phases of the second gear train 90 and the driving gear 96. To drive the plurality of photoreceptors 34 and one intermediate transfer belt 32 with one motor 72, there is an integer ratio relationship between the number of teeth of the adjusting gear 94 and the number of teeth of the driving gear 96, while the integer ratio relationship of the number of gear teeth is broken by the speed setting gear 92, thereby preventing misalignment of the image when a toner image is transferred to the intermediate transfer belt 32. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a drive device and an image forming apparatus.

  In the image forming apparatus of Patent Document 1, a single gear train having a drum driving gear for driving a photosensitive member and a belt driving gear for driving an intermediate transfer belt is connected to one motor, and the drum driving gear is provided. Is arranged downstream of the gear train from the belt drive gear.

  The image forming apparatus of Patent Document 2 represents a positional deviation amount of a toner image on a transfer material that changes with the passage of time as a mechanism for driving a photoreceptor corresponding to yellow, magenta, and cyan toners. Using the position shift curve, the circumferential position of the magenta photoconductor gear is adjusted so that the magenta position shift curve is positioned within the phase difference between the yellow position shift curve and the cyan position shift curve.

  In the image forming apparatus disclosed in Patent Document 3, as a mechanism for driving a photoreceptor corresponding to each of yellow, magenta, and cyan, a cyan photoreceptor gear and a magenta photoreceptor gear are meshed with a drive gear, and a magenta photoreceptor. The idler gear meshed with yellow meshes with the gear. The yellow photoconductor gear has a reference position at a position shifted by an angle θ downstream of the position where the yellow photoconductor gear meshes with the idler gear.

JP 2006-259678 A JP 2005-308799 A JP 2009-122480 A

  The present invention relates to a driving device capable of suppressing the positional deviation of an image transferred from an image holding body to a moving member or a recording medium when a plurality of image holding bodies and one moving member are driven by one driving source. An object is to obtain an image forming apparatus.

  According to a first aspect of the present invention, there is provided a driving device including a driving source for rotating a gear and a plurality of image holding members for holding a developer image obtained by development after light irradiation via a connecting member. A gear for the image carrier that is coaxially and integrally rotated, and a gear for the plurality of image carriers that rotates the drive source gear so that the plurality of image carriers are rotated respectively. A plurality of developer images transferred from the plurality of image carriers to a first gear train to be transmitted and an endless moving member disposed opposite to the plurality of image carriers or a recording medium conveyed by the moving member Of the transfer positions, a circumferential length is set to be an integral number of an interval between the adjacent transfer positions, a rotating member that moves the moving member in the circumferential direction, and via the rotating member and the connecting member Rotating member mounted coaxially and integrally for rotation And a second gear train that transmits the rotation of the gear of the drive source to the gear for the rotating member so that the moving member is moved, and the first gear train and the second gear train Either of the gears in mesh with each other has a relationship of an integral multiple or a fraction of an integer, and the other of the first gear train or the second gear train is a gear of the image carrier gear. An integer gear that has a total number of teeth or a total number of teeth that is an integral multiple or a fraction of an integer of the total number of teeth of the gear for the rotating member and meshes with the gear for the image carrier or the gear for the rotating member A relative speed between the image holding member and the moving member, which is provided closer to the drive source than the integer gear, and is allowed for transfer from the image holding member to the recording medium or the moving member. And a speed setting gear for setting the range.

  In the drive device according to claim 2 of the present invention, the first gear train has a relationship in which the total number of teeth of the meshing gears is an integral multiple or a fraction of an integer, and in the second gear train, the speed is The setting gear meshes with the integer gear.

  In the driving device according to claim 3 of the present invention, the first gear train has a relationship in which the total number of teeth of the meshing gears is an integral multiple or a fraction of an integer, and the gear for the image carrier is: A gear whose number of teeth corresponding to the length from the light irradiation position where light is irradiated on the outer periphery of the image carrier to the transfer position meshes with the image carrier gear in the first gear train It is an integral multiple of the total number of teeth.

  In the drive device according to claim 4 of the present invention, the total number of teeth of the image carrier gear and the total number of teeth of the gear meshing with the image carrier gear are an integral multiple or an integral number. 1 relationship.

  In the driving device according to claim 5 of the present invention, the image carrier is provided corresponding to a black, blue, red, and yellow developer, respectively, and the first gear train includes blue and Transmission that transmits rotation to the red image carrier gear, and transmission of rotation of the blue and red image carrier gears to the black and yellow image carrier gears Has gears.

  In the drive device according to claim 6 of the present invention, the transmission gear has a total number of teeth corresponding to a length from a light irradiation position where light is irradiated on an outer periphery of the image holding body to the transfer position. This is 1 / integer of the number of teeth of the image carrier gear.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising: the driving device according to any one of the first to sixth aspects; and a plurality of image holding members rotated by rotation of a gear for the image holding member. A moving member that is disposed opposite to the plurality of image holding members and is moved by rotation of the gear for the rotating member, a charging unit that charges an outer peripheral surface of the image holding member, and charged by the charging unit. A light irradiating means for irradiating the image carrier with light to form an electrostatic latent image; a developing means for developing the electrostatic latent image formed by the light irradiating means with a developer; and developing at the transfer position. And transfer means for transferring the agent image to the moving member or a recording medium conveyed by the moving member.

  According to the first aspect of the present invention, when a plurality of image carriers and one moving member are driven by a single driving source, it is possible to suppress the positional deviation of the image transferred from the image carrier to the moving member or the recording medium. .

  According to the second aspect of the present invention, as compared with the case where the speed setting gear is arranged immediately before the gear for the rotating member, the influence of the rotational fluctuation of the driving system of the rotating member on the positional deviation between the developer images. Can be reduced.

  According to a third aspect of the present invention, the number of teeth of the image carrier gear corresponding to the length from the light irradiation position to the transfer position on the outer periphery of the image carrier is meshed with the image carrier gear. As compared with the case where the number of teeth is not an integral multiple, the positional deviation of the developer image of each color can be reduced.

  In the invention of claim 4, the number of teeth of the gear for the image carrier and the number of teeth of the gear meshed with the gear for the image carrier are not an integer multiple or a fraction of an integer. The phases of the plurality of image carriers at each transfer position can be matched.

  The invention according to claim 5 is a blue developer image, as compared to the transmission of the rotation of the black and yellow image carrier gears to the blue and red image carrier gears, The positional deviation of the red developer image can be reduced.

  According to the sixth aspect of the present invention, the total number of teeth of the transmission gear is an integral number of the number of teeth of the gear for the image carrier corresponding to the length from the light irradiation position to the transfer position on the outer periphery of the image carrier. Compared to those not formed, the positional deviation of the developer images of the respective colors can be reduced.

  According to the seventh aspect of the present invention, when a plurality of image carriers and one moving member are driven by a single driving source, it is possible to suppress the positional deviation of the image transferred from the image carrier to the moving member or the recording medium. .

1 is an overall view of an image forming apparatus according to an embodiment of the present invention as viewed from the back side. 1 is a configuration diagram of an image forming unit according to an embodiment of the present invention. FIG. (A) It is a block diagram of the drive unit which concerns on embodiment of this invention. (B) It is explanatory drawing which shows the arrangement | positioning state of the photoconductor and drive roll which concern on embodiment of this invention. It is a schematic diagram which shows the arrangement | positioning and meshing state of each gear which concern on embodiment of this invention. FIG. 6 is a schematic diagram showing a phase alignment state of the photoconductor gear according to the embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a relationship between a light irradiation position and a transfer position of the photoconductor and the total number of teeth of the photoconductor gear according to the embodiment of the present invention. (A) It is a schematic diagram which shows arrangement | positioning of the adjustment gear which concerns on embodiment of this invention. (B) It is a graph of the angular velocity error produced | generated by the drive in the adjustment gear which concerns on embodiment of this invention, and the angular velocity error transmitted to an adjustment gear. 6 is a graph showing a relationship between a period and an angular velocity error in each gear on the side for driving the photosensitive member according to the embodiment of the present invention. 6 is a graph showing the relationship between the period and the angular velocity error in each gear on the drive roll side that drives the intermediate transfer belt according to the embodiment of the present invention. It is a schematic diagram which shows the arrangement | positioning and meshing state of each gear which are the other Examples of this invention.

  An example of a drive device and an image forming apparatus according to an embodiment of the present invention will be described.

  As shown in FIG. 1, in the apparatus main body 10 </ b> A of the image forming apparatus 10 according to the present embodiment, a sheet feeding unit 20 for feeding a sheet P as a recording medium, and a sheet P from the sheet feeding unit 20. A sheet conveying path 18 that conveys upward, an image forming unit 30 that forms toner images (developer images) of different colors, and a moving member to which a toner image formed by the image forming unit 30 is transferred The intermediate transfer unit 40 having the intermediate transfer belt 32 as an example, the fixing unit 60 that fixes the toner image transferred from the intermediate transfer unit 40 to the paper P, and the control unit 50 that controls the operation of each unit of the image forming apparatus 10. And are provided. FIG. 1 illustrates a state in which the image forming apparatus 10 is viewed from the back side. In the drawing, an arrow Z indicates a vertically upward direction, and an arrow X indicates a horizontal direction.

  The paper feed unit 20 is provided at the bottom of the apparatus main body 10A, and includes a first storage unit 22 and a second storage unit 24 that store paper P of different sizes. Each of the first storage unit 22 and the second storage unit 24 is provided with a paper feed roll 23 for taking out the stored paper P. The paper P is placed on the downstream side of the paper feed roll 23 in the paper transport direction. A pair of transport rolls 26 for transporting one sheet at a time to the transport path 18 is provided.

  The paper transport path 18 is provided with a plurality of transport roll pairs 27 for transporting the paper P transported by the transport roll pairs 26 upward. A position adjustment roll pair 28 is provided on the downstream side of the conveyance roll pair 27 in the sheet conveyance direction, and the sheet P is stopped once and sent to a secondary transfer position described later at a predetermined timing.

  The image forming unit 30 includes four image forming units 31Y corresponding to the respective colors of yellow yellow (Y), red magenta (M), blue cyan (C), and black black (K). It consists of 31M, 31C, and 31K. In the image forming units 31Y, 31M, 31C, and 31K, the position of the image forming unit 31Y on which the yellow (Y) toner image transferred to the intermediate transfer belt 32 is first formed is high, and finally transferred to the intermediate transfer belt 32. The image forming units 31K on which the black (K) toner images are formed are arranged in an inclined state with respect to the arrow H direction so as to be lowered.

  These four image forming units 31Y, 31M, 31C, and 31K are basically composed of the same members. In the following description, in each member constituting the image forming apparatus 10, when distinguishing each toner color, a letter (Y, M, C, K) corresponding to each toner color is added to the code, When not distinguished, characters corresponding to each toner color are omitted.

  As shown in FIG. 2, each toner color image forming unit 31 holds an electrostatic latent image formed by light irradiation and rotated in the arrow + R direction (clockwise direction shown) by a driving means (not shown). A photosensitive member 34 as an example of an image holding member is provided. On the upstream side in the rotation direction of the photoconductor 34, a charging roll 36 as an example of a charging unit that charges the surface of the photoconductor 34 by a potential difference generated by energization by an energizing unit (not shown) is provided. The charging roll 36 is configured to rotate in the arrow -R direction (the counterclockwise direction in the drawing).

  Further, on the downstream side of the rotation direction of the photosensitive member 34 with respect to the charging roll 36, light corresponding to each toner color is irradiated (exposed) on the outer peripheral surface of the photosensitive member 34 charged by the charging roll 36 to cause electrostatic latent. An exposure device 38 is provided as an example of light irradiation means for forming an image. Here, a position where light is irradiated on the surface of the photoconductor 34 is defined as a light irradiation position PL. In this embodiment, an LED (Light Emitting Diode) is used as the exposure device 38. However, the present invention is not limited to this. For example, a laser beam may be scanned by a polygon mirror.

  Further, on the downstream side of the rotation direction of the photosensitive member 34 with respect to the exposure device 38, a developing roll 44 that develops the electrostatic latent image formed on the surface of the photosensitive member 34 with toner of each color and visualizes it as a toner image. A developing device 42 is provided as an example of the developing means. The developing roll 44 is rotated in the arrow -R direction by a motor (not shown).

  As shown in FIG. 1, in the apparatus main body 10A, above the intermediate transfer belt 32, yellow (Y), magenta (M), cyan (C), and black (K) developing devices 42 are provided with toner. Toner cartridges 46Y, 46M, 46C, and 46K are provided. Since the toner cartridge 46K containing black (K) toner is used frequently, it is larger than the other color toner cartridges 46Y, 46M, and 46C.

  As shown in FIG. 2, as an example of a transfer unit for transferring a toner image formed on the surface of the photosensitive member 34 to the intermediate transfer belt 32 on the opposite side of the photosensitive member 34 with the intermediate transfer belt 32 interposed therebetween. A primary transfer member 48 is provided. The primary transfer member 48 is composed of a rotating body that rotates following the movement of the intermediate transfer belt 32 in the direction of the arrow -R, and the potential set by energizing the cored bar of the rotating body by an energizing means (not shown). Held in. A position where the toner image is transferred from the photosensitive member 34 to the intermediate transfer belt 32 is defined as a primary transfer position PA.

  Further, on the downstream side of the primary transfer member 48 in the rotation direction of the photoconductor 34, a cleaning member 52 for cleaning residual toner that is not transferred from the photoconductor 34 to the intermediate transfer belt 32 and remains on the surface of the photoconductor 34 is provided. It has been.

  On the other hand, as shown in FIG. 1, an intermediate transfer unit 40 is provided above each image forming unit 31. The intermediate transfer unit 40 has an endless intermediate transfer belt 32 onto which the toner image formed by the image forming unit 31 of each toner color is transferred. The intermediate transfer belt 32 includes a driving roll 54 as an example of a rotating member for applying a driving force (rotational force) to the intermediate transfer belt 32, and a driven roll 56 that applies tension to the intermediate transfer belt 32 and rotates in a driven manner. It is wrapped around Then, the intermediate transfer belt 32 is driven by the drive unit 70 (see FIG. 3A), which will be described later, so that the drive roll 54 is rotated in the direction of the arrow -R, and the driven roll 56 is driven to rotate in the direction of the arrow -R. Circulation drive is performed in the direction of arrow A. The drive unit 70 is driven and controlled by a control unit 50 that is provided in the apparatus main body 10A and controls the start or stop of the operation of each unit of the image forming apparatus 10. A cleaning unit 53 for cleaning residual toner remaining on the surface of the intermediate transfer belt 32 is provided at a position facing the drive roll 54 outside the intermediate transfer belt 32.

  Here, a secondary image for secondary transfer of the toner image primarily transferred onto the intermediate transfer belt 32 onto the paper P is located at a position facing the driven roll 56 across the intermediate transfer belt 32 on the paper conveyance path 18. A transfer member 62 is provided. The secondary transfer member 62 is a rotating body that is provided so as to be rotatable in the direction of the arrow + R. The toner image is secondarily transferred onto the paper P by being energized by an energizing unit (not shown) and having a set potential. A position where the driven roll 56 and the secondary transfer member 62 face each other with the intermediate transfer belt 32 interposed therebetween is defined as a secondary transfer position PB.

  A fixing unit 60 for fixing the toner image onto the paper P on which the toner image is transferred by the secondary transfer member 62 is provided above the secondary transfer member 62 on the paper transport path 18. The fixing unit 60 is provided with a heating roll 64 disposed on the toner image surface side of the paper P and a pressure roll 66 that pressurizes the paper P toward the heating roll 64. Further, a discharge roll pair 68 for discharging the paper P on which the toner image is fixed from the discharge port 13 formed in the apparatus main body 10A is provided on the downstream side of the paper conveyance path 18 in the conveyance direction of the paper P from the fixing unit 60. It has been. As a result, the paper P discharged by the discharge roll pair 68 is stacked on the stacking unit 69 provided at the upper part of the apparatus main body 10A.

  Here, an image forming process of the image forming apparatus 10 will be described.

  In the image forming apparatus 10, first, based on image data sent from an external device such as an image reading device (not shown) or a personal computer, each exposure device 38 (Y, M, C, K) receives an image processing unit (not shown). The image data for each color is sequentially output. The light emitted from these exposure devices 38 (Y, M, C, K) according to the image data exposes the surface of each corresponding photosensitive member 34. Thereby, an electrostatic latent image is formed on the surface of each photoconductor 34.

  Subsequently, the electrostatic latent image formed on the surface of each photoconductor 34 is yellow (Y), magenta (M), cyan (C), and cyan by each developing device 42 (Y, M, C, K). It is developed as a black (K) color toner image. The yellow (Y), magenta (M), cyan (C), and black (K) toner images respectively formed on the surface of each photoconductor 34 are intermediately transferred by the primary transfer member 48 at the primary transfer position PA. Primary transfer is sequentially performed on the belt 32. Further, the toner image on the intermediate transfer belt 32 subjected to the primary transfer is moved to the secondary transfer position PB.

  On the other hand, the paper P is conveyed from the paper supply unit 20 toward the secondary transfer position PB in accordance with the timing at which the toner image on the intermediate transfer belt 32 is moved to the secondary transfer position PB. The conveyance of the sheet P is temporarily stopped before reaching the secondary transfer position PB, and the position adjustment roll pair 28 rotates in accordance with the movement timing of the intermediate transfer belt 32, thereby aligning the toner image on the sheet P. Is done.

  Subsequently, at the secondary transfer position PB, the sheet P that has been transported in time is sandwiched between the intermediate transfer belt 32 and the secondary transfer member 62. At this time, the toner image energized (voltage applied) to the secondary transfer member 62 and held on the intermediate transfer belt 32 is secondarily transferred onto the paper P at once.

  Subsequently, the sheet P on which the toner image is secondarily transferred is conveyed to the fixing unit 60. In the fixing unit 60, the toner image on the paper P is heated and pressed by the heating roll 64 and the pressure roll 66 and fixed on the paper P. The paper P after the toner image fixing is discharged out of the image forming apparatus 10 by the discharge roll pair 68. In this way, image formation by the image forming apparatus 10 is performed.

  Next, the drive unit 70 as an example of the drive device will be described.

  As shown in FIG. 3A, a drive unit 70 for driving each photoconductor 34 and the drive roll 54 (see FIG. 3B) is attached to the side plate 11 of the apparatus main body 10A. The drive unit 70 includes a housing 71 serving as a main body. The housing 71 is fixed to the side plate 11 with screws (not shown) and rotatably supports gears described later.

  The drive unit 70 rotates coaxially and integrally with a motor 72 as an example of a drive source in which a pinion 73 is attached to the tip of a rotation shaft (not shown) and the photosensitive members 34Y, 34M, 34C, and 34K (see FIG. 1). Photosensitive member gears 84Y, 84M, 84C, 84K as an example of a holding member gear, and a driving gear as an example of a rotating member gear that is coaxially and integrally rotated with the driving roll 54 (see FIG. 1). 96, a first gear train 80 as an example of a first gear train that transmits the rotation of the pinion 73 to each of the photoreceptor gears 84Y, 84M, 84C, and 84K, and a first gear train that transmits the rotation of the pinion 73 to the drive gear 96. And a second gear train 90 as an example of a two-gear train. Incidentally, the total number of teeth of the pinion 73 is 9, the diameter of the pitch circle is 4.19 mm, the total number of teeth of the photoconductor gears 84Y, 84M, 84C, 84K is 143, and the diameter of the pitch circle is 66.6 mm. The total number of teeth of the drive gear 96 is 124, and the diameter of the pitch circle is 72.6 mm.

  Here, the photoconductor gear 84K is for black toner (developer), and the photoconductor gear 84C is for cyan toner. Further, the photoconductor gear 84M is for magenta toner, and the photoconductor gear 84Y is for yellow toner. The photoconductor gears 84C and 84M are arranged on the upstream side of the drive transmission path from the motor 72 relative to the photoconductor gears 84Y and 84K.

  As shown in FIG. 3B, the photoconductor gears 84Y, 84M, 84C, and 84K are provided at one end of the shafts 35Y, 35M, 35C, and 35K that are the rotation axes of the photoconductors 34Y, 34M, 34C, and 34K. The drive gear 96 is coaxially attached to one end portion of the shaft 55 that is the rotation shaft of the drive roll 54 via the connection member 39. The drive gear 96 is coaxially attached via the connection members 37Y, 37M, 37C, and 37K. It is attached. Thus, when the photoconductor gears 84Y, 84M, 84C, and 84K rotate, the photoconductors 34Y, 34M, 34C, and 34K rotate, and when the drive gear 96 rotates, the drive roll 54 rotates.

  FIG. 4 shows a schematic diagram of the arrangement and meshing state of the gears constituting the drive unit 70. FIG. 4 shows a state in which the drive unit 70 is viewed in the arrow Y direction (from the front side) in FIG. 3A, and the meshing portions of the respective gears are shown in a simplified manner.

  As shown in FIGS. 3A, 3 </ b> B, and 4, the drive unit 70 has a cover member 75 fixed to the housing 71 with screws so that each gear is sandwiched between the drive unit 70 and the connection. The members 37Y, 37M, 37C, and 37K protrude from the opposite side of the housing 71 to the cover member 75. On the other hand, from the side plate 11, one end portions of the shafts 35Y, 35M, 35C, and 35K of the photosensitive members 34Y, 34M, 34C, and 34K are exposed. Here, with one end of the shaft 35Y and the connecting member 37Y, one end of the shaft 35M and the connecting member 37M, one end of the shaft 35C and the connecting member 37C, and one end of the shaft 35K and the connecting member 37K being connected, The drive unit 70 is fixed to the side plate 11 by fastening the housing 71 to the side plate 11 with screws. Thus, the drive unit 70 can be attached and detached independently. When the image forming apparatus 10 is viewed from the back side, the drive roll 54 is disposed on the upper left side of the photoconductor 34Y, and the drive gear 96 is disposed on the front side of the photoconductor gear 84Y.

  As shown in FIG. 4, the first gear train 80 meshes with the pinion 73 and is provided so as to be rotatable, and the first gear train 80 is meshed with the relay gear 78, the photoconductor gear 84 </ b> M, and the photoconductor gear 84 </ b> C so as to be rotatable. An idler gear 82 provided, an idler gear 86 as an example of a transmission gear that is rotatably engaged with the photoreceptor gear 84Y and the photoreceptor gear 84M, and meshed with the photoreceptor gear 84C and the photoreceptor gear 84K, and rotatable. And an idler gear 88 as an example of the provided transmission gear.

  The relay gear 78 has a total number of teeth of 72 and a pitch circle diameter of 33.5 mm, and the idler gear 82 has a total number of teeth of 72 and a pitch circle diameter of 33.5 mm. The idler gear 86 has a total number of teeth of 72 and a pitch circle diameter of 33.5 mm, and the idler gear 88 has a total number of teeth of 72 and a pitch circle diameter of 33.5 mm. Thus, in the first gear train 80, the number of teeth of each gear is in an integer multiple relationship.

  On the other hand, the second gear train 90 meshes with the pinion 73 and is provided rotatably, and the second gear train 90 meshes with the relay gear 91 and is provided rotatably. ) And a moving speed of the intermediate transfer belt 32 (hereinafter referred to as moving speed V2), a specific range (for example, allowed for transfer from the photosensitive member 34 to the paper P or the intermediate transfer belt 32). (V2-V1) / V1 × 100 relative speed ratio range 0% to 0.5% range) speed setting gear 92 as an example of a speed setting gear, and speed setting And an adjustment gear 94 as an example of an alignment gear that meshes with the gear 92 and is rotatably provided.

  The relay gear 91 has a total number of teeth of 72 and a pitch circle diameter of 33.5 mm. Further, the adjustment gear 94 has a total number of teeth of 62 and a pitch circle diameter of 36.3 mm, and the total number of teeth is half of the number of teeth of the drive gear 96 (one-integer). Here, the speed setting gear 92 includes a gear 92A having a total number of teeth of 71 and a pitch circle diameter of 33.1 mm, and a gear 92A having a total number of teeth of 82 and a pitch circle diameter of 48.0 mm and a larger diameter than the gear 92A. The gear 92A and the relay gear 91 are engaged with each other, and the gear 92B and the adjustment gear 94 are engaged with each other.

  With the above configuration, when the motor 72 is driven and the pinion 73 rotates on the first gear train 80 side, the rotation is transmitted in the order of the relay gear 78 and the idler gear 82, and the rotation is transmitted from the idler gear 82 to the photoconductor gears 84C and 84M, respectively. Communicated. The rotation of the photoconductor gear 84C is transmitted to the photoconductor gear 84K through the idler gear 88, and the rotation of the photoconductor gear 84M is transmitted to the photoconductor gear 84Y through the idler gear 86. In this way, the photoconductors 34Y, 34M, 34C, and 34K (see FIG. 3B) rotate in the same direction (arrow + R direction in FIG. 2).

  On the other hand, on the second gear train 90 side, when the motor 72 is driven and the pinion 73 rotates, the rotation is transmitted in the order of the relay gear 91, the speed setting gear 92 (gear 92A, gear 92B), the adjustment gear 94, and the drive gear 96. Then, the drive roll 54 (see FIG. 3B) rotates in the direction of the arrow -R (see FIG. 1).

  Next, phase adjustment of each gear in the drive unit 70 will be described.

  FIG. 5 is a schematic diagram showing the phase alignment state of the photoconductor gear 84. In FIG. 5, the pinion 73, the relay gear 91, the speed setting gear 92, and the adjustment gear 94 are not shown.

  As shown in FIG. 5, the primary transfer positions PA on the photosensitive members 34Y, 34M, 34C, and 34K are set as transfer positions PA (Y), PA (M), PA (C), and PA (K), respectively. The distance from the transfer position PA (Y) to PA (M), the distance from the transfer position PA (M) to PA (C), and the distance from the transfer position PA (C) to PA (K) are all. The photoconductors 34Y, 34M, 34C, and 34K are arranged so as to be the distance L.

  The diameters of the photoconductors 34Y, 34M, 34C, and 34K are D1 (= 30.0 mm), and the diameter of the drive roll 54 is D2 (= 22.6 mm). The drive roll 54 has a diameter D2 such that nX = distance L, where X is the circumference of one rotation and n is an integer.

  On the other hand, each of the photoconductor gears 84Y, 84M, 84C, and 84K is formed with a triangular mark MK serving as a mark (reference position) at one place in the circumferential direction when viewed in the rotation axis direction. The rotation center of each photoconductor 34 (rotation center of each photoconductor gear 84) is defined as O, and the radial line connecting the rotation center O and the mark MK and the outer circumference circle of the photoconductors 34Y, 34M, 34C, and 34K. Let positions E, F, G, and H be the positions at which X and Y intersect.

  Here, a rotation speed error (angular speed error (angular speed fluctuation)) occurs during rotation of each gear due to an error during manufacture of each gear constituting the drive unit 70, and this error causes the error on the intermediate transfer belt 32. It is generally known that the image positional deviation of 1 appears. This angular velocity error is, for example, an error due to eccentricity that occurs in accordance with the precision (deviation from the design value) of each gear mold, and includes an accumulated pitch error and a single-tooth engagement error.

  The drive unit 70 of this embodiment has a structure in which the rotation of the photoconductor gears 84M and 84C that are driven to rotate by the idler gear 82 is transmitted to the photoconductor gears 84Y and 84K via the idler gears 86 and 88, respectively. For this reason, the positional deviation of the image due to the angular velocity error when the toner images are superimposed at the respective transfer positions PA (Y, M, C, K) on the intermediate transfer belt 32 is only the angular velocity error of the photoconductor gears 84M, 84C. Since it is also influenced by the angular velocity error of the meshed photoconductor gears 84Y, 84K, it is necessary to adjust the arrangement angle (phase) of each photoconductor gear 84Y, 84M, 84C, 84K.

  In the present embodiment, when each photoconductor gear 84 is attached, first, the mark MK of the photoconductor gear 84M is made to coincide with the position where the photoconductor gear 84M and the idler gear 82 mesh. In this state, the angle θ1 (here θ1 = 360 ° × L / (π × (D1))) from the position where the mark MK of the photoconductor gear 84C meshes with the idler gear 82 to the upstream side in the rotation direction (arrow + R direction). The photoconductor gear 84C is arranged so as to be displaced by only a distance. Subsequently, the photoconductor gear 84Y is arranged so as to deviate from the position where the mark MK of the photoconductor gear 84Y meshes with the idler gear 86 by an angle θ2 (where θ2 = θ1 + α) downstream in the rotation direction (arrow + R direction). The angle α is a phase correction term described later.

  Further, the photoconductor gear 84K is arranged so as to be shifted from the position where the mark MK of the photoconductor gear 84K meshes with the idler gear 88 by an angle θ1 + angle θ3 (where θ3 = θ1 + β) upstream in the rotation direction (arrow + R direction). That is, in the photoconductor gear 84K, the position shifted from the position where the mark MK meshes with the idler gear 88 to the upstream side by the angle θ1 is the position of the mark MA indicated by the dotted line, and further shifted from the mark MA to the upstream side by the angle θ3. The mark MK is arranged at the position. The angle β is a phase correction term.

  Note that the angle α is set so as to cancel the influence of the toner image position shift due to the difference in accuracy between the driving tooth surface and the driven tooth surface of the photoconductor gear 84M. The angle β is set so as to cancel the influence of the toner image position shift due to the difference in accuracy between the driving tooth surface and the driven tooth surface of the photoconductor gear 84C. For example, for the angle α, the horizontal axis is the period (angle), and the vertical axis is the image displacement (+ is the position advanced from the set position in the moving direction, − is the position delayed from the set position relative to the moving direction). Is obtained for each of the photoconductor gears 84M and 84Y, the characteristic diagram of the photoconductor gear 84Y is shifted by an angle θ1, and is superimposed on the characteristic diagram of the photoconductor gear 84M. It is only necessary to set the angle θ2, that is, the angle α, so that the fluctuation of the image position shift obtained as the difference (the fluctuation range of + and − centered on the error 0) becomes small. Regarding the angle β, the characteristic diagrams may be compared in the same procedure for the photoconductor gear 84C and the photoconductor gear 84K.

  Next, the setting of the number of teeth of the photoconductor gear 84 will be described.

  FIG. 6 shows a photoreceptor 34M and a photoreceptor gear 84M as an example. On the outer peripheral surface of the photoreceptor 34M, the central angle θ4 from the light irradiation position PL to the transfer position PA (M) is set to 181.3 °. The angle θ4 is an angle on the side facing the developing roll 44 (see FIG. 2).

  Here, since the total number of teeth of the photoconductor gear 84M is 143, the number of teeth corresponding to the length from the light irradiation position PL to the transfer position PA (M) in the photoconductor gear 84M is 143 × 181.3 °. / 360 ° ≈72, which is an integral multiple (1 times) of the total number of teeth 72 of the idler gear 82 provided immediately before the photoconductor gear 84M. That is, one rotation of the idler gear 82 is synchronized with the movement of the photosensitive member 34M from the light irradiation position PL to the transfer position PA (M). Similarly, the rotation of the idler gear 86, the idler gear 82, and the idler gear 88 and the rotation of the photosensitive members 34Y, 34C, and 34K from the light irradiation position PL to the transfer positions PA (Y), PA (C), and PA (K). Although the movement is synchronized, illustration and description are omitted.

  Next, the speed setting gear 92 will be described.

  As shown in FIG. 7A, in the speed setting gear 92, a position where the relay gear 91 and the gear 92A mesh with each other is a position C, and a position where the gear 92B and the adjustment gear 94 mesh with each other is a position D. The gear 92A and the gear 92B are attached to a shaft 92C that is a rotating shaft. At the position C, an angular velocity error (due to the accumulated pitch error of the gear 92A) occurs due to the gear 92A being rotationally driven by the relay gear 91, and at the position D, the adjusting gear 94 is rotationally driven by the gear 92B. An angular velocity error (due to a cumulative pitch error of the gear 92B) occurs.

  Here, the phase of the characteristic line of the angular velocity error obtained for each of the gear 92A and the gear 92B (the relative positional relationship between the position C and the position D with respect to the rotation direction) is variously shifted in the range from 0 ° to 360 °, When the position fluctuation of the adjustment gear 94 was measured, as shown in FIG. 7B, the phase of the angular velocity error at the position D of the gear 92B is shifted by 180 ° with respect to the phase of the angular velocity error at the position C of the gear 92A. In this case, it was confirmed that the position variation of the adjustment gear 94 is minimized. In FIG. 7B, + indicates the direction of advance from the reference position, and-indicates the direction of delay from the reference position. For this reason, in the present embodiment, in FIG. 7A, the phase of the angular velocity error at the position D of the gear 92B is shifted by 180 ° from the phase of the angular velocity error at the position C of the gear 92A. The installation angle is adjusted and attached to the shaft 92C.

  Further, in the speed setting gear 92, the total number of teeth of the gear 92A is set to 71 and the total number of teeth of the gear 92B is set to 82, and the intermediate transfer belt 32 (see FIG. 5) is relative to each photosensitive member 34 (see FIG. 5). The speed is adjusted. In this adjustment, the intermediate transfer belt 32 and the photosensitive member 34 driven by a driving roll 54 (see FIG. 5) having a diameter different from that of the photosensitive member 34 are driven by one motor 72 (see FIG. 4). The purpose is to set the relative speed between the peripheral speed V1 of the photosensitive member 34 and the moving speed V2 of the intermediate transfer belt 32 within the above-mentioned specific range. That is, here, the total number of teeth of the gear 92A and the gear 92B is set so that the circumferential speed V1≈the moving speed V2.

  Next, the operation of this embodiment will be described.

  FIG. 8 shows the relationship between the period and the angular velocity error in each gear on the side that drives the photosensitive member 34 (see FIG. 2). Here, for easy understanding of the driving state of the photoconductor 34, the rotation of the pinion 73 for 16 cycles (corresponding to one cycle of the photoconductor gear 84) is used as a reference.

  In FIG. 8, since the total number of teeth of the pinion 73 is 9 and the total number of teeth of the relay gear 78 is 72 (8 times the total number of teeth of the pinion 73), the pinion 73 is rotating in 16 cycles. The relay gear 78 rotates in two cycles. Since the total number of teeth of the idler gear 82 is 72 (one times the total number of teeth of the relay gear 78), when the relay gear 78 rotates in two cycles, the idler gear 82 also rotates in two cycles.

  Further, since the total number of teeth of the photoconductor gears 84C and 84M is 143 (almost twice that of the idler gear 82), when the idler gear 82 rotates in two cycles, the photoconductor gears 84C and 84M each have one cycle. Rotate with. Since the total number of teeth of the photoconductor gears 84K and 84Y is 143 (approximately twice the idler gears 86 and 88), the photoconductor gears 84C and 84M rotate in one cycle and the idler gears 86 and 88 in two cycles. When rotating, each of the photoconductor gears 84K and 84Y rotates in one cycle. As described above, since the total number of teeth from the pinion 73 to the idler gear 82 and the total number of teeth of the idler gears 86 and 88 are aligned by an integral multiple, the angular velocity errors of the photoconductor gears 84Y, 84M, 84C, and 84K The same phase is repeated for each period of rotation of the body gears 84Y, 84M, 84C, 84K.

  In addition, as shown in FIGS. 5 and 6, one rotation of the idler gears 82, 86, and 88, and from the light irradiation position PL to the transfer positions PA (Y), PA (M), PA (C), and PA (K). Since the movements of the photoconductors 34Y, 34M, 34C, and 34K are synchronized, the photoconductors 34Y, 34M, 34C, and 34K move from the light irradiation position PL to the transfer positions PA (Y), PA (M), and PA (C ), The angular velocity error between the idler gears 82, 86, 88 and the pinion 73 is canceled before reaching PA (K).

  On the other hand, FIG. 9 shows the relationship between the cycle and the angular velocity error in each gear on the drive roll 54 (see FIG. 1) side that drives the intermediate transfer belt 32. Here, for easy understanding of the driving state of the intermediate transfer belt 32, the rotation of the pinion 73 for 11.9 cycles (corresponding to one cycle of the drive gear 96) is displayed as a reference.

  In FIG. 9, since the total number of teeth of the pinion 73 is 9 and the total number of teeth of the relay gear 91 is 72 (8 times the total number of teeth of the pinion 73), the pinion 73 rotates in 11.9 cycles. The relay gear 91 rotates at 1.49 cycles. Subsequently, in the speed setting gear 92, since the total number of teeth of the gear 92A is 71, when the relay gear 91 rotates in the 1.49 cycle, the gear 92A rotates in the 1.51 cycle. Similarly, the coaxial gear 92B also rotates at 1.51 cycles.

  Subsequently, when the gear 92B having a total number of teeth of 82 rotates in a cycle of 1.51, the adjustment gear 94 having a total number of teeth of 62 rotates in a cycle of 2. When the adjustment gear 94 having the total number of teeth 62 rotates in two cycles, the drive gear 96 having the total number of teeth 124 (twice the total number of teeth of the adjustment gear 94) rotates in one cycle. . As described above, even when the number of teeth of the relay gear 91 and the number of teeth of the speed setting gear 92 are not an integral multiple or a fraction of an integer, 94 and the total number of teeth of the drive gear 96 are an integral multiple (twice), so that the drive gear 96 and the adjustment gear 94 mesh at the same place, and the angular velocity error of the drive gear 96 has the same phase every cycle.

  Here, as shown in FIG. 5, in the photoconductor gears 84Y, 84M, 84C, and 84K, the rotation phases are aligned with respect to the mark MK. Further, the distance L between the transfer positions PA is synchronized with the outer peripheral length of one rotation (one cycle) of the drive roll 54. For this reason, the angular velocity error of each gear is reduced, and the toner image formed with the position E of the photoreceptor 34Y as the starting point is transferred to the intermediate transfer belt 32 at the transfer position PA (Y) and moved by a distance L in the direction of arrow A. At this time, at the transfer position PA (M), a toner image starting from the position F of the photosensitive member 34M is transferred to the toner image. Subsequently, at the transfer position PA (C) moved by a distance 2L in the direction of arrow A from the transfer position PA (Y), the toner image starting from the position G of the photoconductor 34C is transferred to the toner image. At the transfer position PA (K) moved by a distance 3L in the direction of the arrow A from the transfer position PA (Y), the toner images starting from the position H of the photosensitive member 34K are sequentially superimposed and transferred.

  With the above-described operation, according to the present embodiment, the position of the toner image transferred to the intermediate transfer belt 32 advances, for example, in the moving direction of the intermediate transfer belt 32 with respect to the reference position (error 0). When the toner images of M, C, and K are transferred while being shifted to the positive position (+), the remaining M, C, and K toner images are also transferred with a shift to the position advanced in the moving direction of the intermediate transfer belt 32 with respect to the reference position (error 0). It will be. When the Y toner image is transferred to the position (−) delayed in the moving direction of the intermediate transfer belt 32 with respect to the reference position (error 0), the remaining M, C, and K toner images are also the reference. The transfer is shifted to a position delayed in the moving direction of the intermediate transfer belt 32 with respect to the position (error 0). For this reason, the positional deviation of the Y, M, C, and K toner images from the reference position becomes small.

  Further, according to the present embodiment, as shown in FIGS. 5 and 6, the photoconductors 34Y, 34M, 34C, and 34K are moved from the light irradiation position PL to the transfer positions PA (Y), PA (M), and PA (C). , PA (K), the angular velocity errors of the photoconductor gears 84Y, 84M, 84C, and 84K with respect to the idler gears 82, 86, and 88 are in the same phase, so that the positional deviation of each toner image becomes smaller.

  Furthermore, according to the present embodiment, as shown in FIGS. 7A and 7B, the phase of the angular velocity error characteristic line for the gear 92A and the gear 92B that are coaxially attached to the shaft 92C is changed to the position of the gear 92A. Since the phase of the angular velocity error at the position D of the gear 92B is shifted by 180 ° with respect to the phase of the angular velocity error at C, the overall angular velocity error is adjusted by delaying the phase advanced at the position C at the position D. The angular velocity error (unevenness of rotation) in the adjustment gear 94 and the drive gear 96, which are the driving targets of the subsequent stage of the speed setting gear 92, is reduced, and as a result, the positional deviation of each toner image is reduced.

  Further, according to the present embodiment, as shown in FIG. 4, the photoreceptor gears 84M and 84C are disposed on the side closer to the motor 72, and the photoreceptor gears 84Y and 84K are disposed on the side away from the motor 72. The photoconductor gears 84M and 84C, in which rotation is directly transmitted from the motor 82, are not easily affected by the angular velocity error caused by the idler gears 86 and 88.

  In addition, this embodiment is not limited to said structure.

  The speed setting gear 92 and the adjustment gear 94 may be provided in the first gear train 80, and the rotational phase between the first gear train 80 and the photoconductor gears 84Y, 84M, 84C, 84K may be adjusted. In addition, a recording medium that is conveyed on the sheet conveying belt by providing a sheet conveying belt (sheet conveying device) instead of the intermediate transfer belt 32 and arranging the photosensitive members 34Y, 34M, 34C, and 34K on the sheet conveying belt. You may apply to the image forming apparatus which transfers a toner image to (paper P).

  Further, in the drive unit 70, the photosensitive member 34K may be driven by a motor different from the motor 72, and the photosensitive members 34Y, 34M, 34C and the intermediate transfer belt 32 may be driven by one motor 72. . Further, the number of the photosensitive members 34 driven by the motor 72 is not limited to four, and may be three, for example. The total number of teeth of each gear and the diameter of the pitch circle can be freely set. For example, the total number of teeth of each photoconductor gear 84 may be 144 instead of 143.

  Further, as another embodiment of the drive unit 70, a drive unit 100 shown in FIG. 10 may be used. Note that the same reference numerals as those of the drive unit 70 are given to the same components as those of the drive unit 70 described above, and the description thereof is omitted. The drive unit 100 has a housing (not shown), and this housing rotatably supports gears described later. Further, the drive unit 100 replaces the first gear train 80 with a first gear train 110 as an example of a first gear train that transmits the rotation of the pinion 73 to each of the photoreceptor gears 84Y, 84M, 84C, and 84K. It differs from the drive unit 70 in the point provided.

  The first gear train 110 includes a relay gear 78, an intermediate gear 102 that is rotatably engaged with the relay gear 78, and an intermediate gear 104 that is rotatably engaged with the intermediate gear 102 and the idler gear 82 (82 </ b> A). An intermediate gear 106 that is rotatably engaged with the relay gear 78 at a position different from the intermediate gear 102, and an intermediate gear 108 that is rotatably engaged with the intermediate gear 106 and the idler gear 82 (82B). It is comprised including. The idler gear 82A meshes with the photoconductor gear 84C and the photoconductor gear 84K, and is rotatably provided. The idler gear 82B meshes with the photoconductor gear 84Y and the photoconductor gear 84M, and is rotatably provided. The intermediate gears 102, 104, 106, 108 have the same number of teeth and the same pitch circle diameter as the relay gear 78. As described above, the first gear train 110 may be constituted by two gear trains from the relay gear 78.

10 Image forming apparatus 32 Intermediate transfer belt (moving member)
34 Photoconductor (image carrier)
36 Charging roll (charging means)
37Y connecting member 37M connecting member 37C connecting member 37K connecting member 38 exposure apparatus (light irradiation means)
39 Connecting member 42 Developer (Developing means)
48 Primary transfer member (transfer means)
54 Drive roll (rotating member)
70 Drive unit (drive device)
72 Motor (drive source)
73 Pinion (drive source)
78 Relay gear (first gear train)
80 First gear train (first gear train)
82 idler gear (first gear train)
84Y photoconductor gear (gear for image carrier)
84M photoconductor gear (gear for image carrier)
84C photoconductor gear (gear for image carrier)
84K photoconductor gear (gear for image carrier)
86 idler gear (transmission gear, first gear train)
88 idler gear (transmission gear, first gear train)
90 Second gear train (second gear train)
91 Relay gear (second gear train)
92 Speed setting gear (speed setting gear, second gear train)
94 Adjustment gear (aligned gear, second gear train)
96 Drive gear (gear for rotating member)
110 First gear train (first gear train)
P paper (recording medium)
PA Primary transfer position (transfer position)
PL light irradiation position

Claims (7)

A drive source for rotating the gear;
A gear for an image carrier attached to each of a plurality of image carriers for holding a developer image obtained by development after light irradiation so as to rotate coaxially and integrally through a connecting member;
A first gear train for transmitting rotation of the gears of the driving source to the gears for the plurality of image carriers so that the plurality of image carriers are respectively rotated;
Adjacent of a plurality of transfer positions where a developer image is transferred from the plurality of image carriers to an endless moving member disposed opposite to the plurality of image carriers or a recording medium conveyed by the moving member. A circumferential member whose circumference is set to be 1 / integer of the interval between the transfer positions, and a rotating member that moves the moving member in the circumferential direction;
A gear for a rotating member attached so as to rotate coaxially and integrally via the rotating member and a connecting member;
A second gear train that transmits the rotation of the gear of the driving source to the gear for the rotating member so that the moving member is moved,
Either one of the first gear train and the second gear train has a relationship in which the number of teeth of meshing gears is an integral multiple or a fraction of an integer,
The other of the first gear train or the second gear train is
The image carrier gear or the rotation member has a total number of teeth that is an integral multiple or a fraction of an integer of the total number of teeth of the image carrier gear or the rotation member gear. An integer gear that meshes with the gear for
A specific range that is provided closer to the drive source than the integer gear and allows a relative speed between the image carrier and the moving member to be transferred from the image carrier to the recording medium or the moving member; Speed setting gears to
A driving device having: In the first gear train, the total number of teeth of meshing gears is in an integer multiple or a fraction of an integer,
The drive device according to claim 1, wherein in the second gear train, the speed setting gear and the integer gear are meshed with each other. In the first gear train, the total number of teeth of meshing gears is in an integer multiple or a fraction of an integer,
The gear for the image carrier has the number of teeth corresponding to the length from the light irradiation position where the light is irradiated on the outer periphery of the image carrier to the transfer position, in the first gear train. The driving device according to claim 1 or 2, wherein the driving device is an integral multiple of the total number of teeth of the gear meshing with the body gear.   The total number of teeth of the image carrier gear and the total number of teeth of the gear meshed with the image carrier gear are in an integer multiple or a fraction of an integer. The driving device according to any one of the above. The image carriers are respectively provided corresponding to black, blue, red, and yellow developers,
The first gear train transmits rotation to the blue and red image carrier gears, and the rotation of the blue and red image carrier gears is black and yellow. The drive device according to any one of claims 1 to 4, further comprising a transmission gear that transmits the image carrier gear.   In the transmission gear, the total number of teeth is an integral number of the number of teeth of the gear for the image carrier corresponding to the length from the light irradiation position where light is irradiated on the outer periphery of the image carrier to the transfer position. The driving device according to claim 5, wherein The drive device according to any one of claims 1 to 6,
A plurality of image carriers rotated by rotation of the image carrier gear;
A moving member that is disposed to face the plurality of image carriers and is moved by rotation of a gear for the rotating member;
Charging means for charging the outer peripheral surface of the image carrier;
Light irradiating means for irradiating the image carrier charged by the charging means with light to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image formed by the light irradiation means with a developer;
Transfer means for transferring the developer image to the moving member or a recording medium conveyed by the moving member at the transfer position;
An image forming apparatus.

Images