JP5250579B2 - Driving device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a driving device and an image forming apparatus including the driving device.

  In general, an image forming apparatus such as a copier, a printer, or a facsimile machine includes a plurality of image carriers (photosensitive drums), a developer that converts an electrostatic latent image formed on the image carrier into a toner image, A transfer unit that transfers the toner image formed on the image carrier to a transfer material such as paper; and a fixing unit that fixes the toner image transferred to the transfer material to the transfer material.

  In image forming apparatuses, high image quality and low cost are required, and along with these demands, a drive mechanism is required to have a structure that can be easily assembled while maintaining high dimensional accuracy.

  The drive mechanism having high dimensional accuracy includes, for example, a sheet metal part, a shaft supported by the sheet metal part, a drum part supported by the shaft, and a drive part firmly assembled to the sheet metal. There has been proposed a drive mechanism in which a drive gear assembled to the output shaft is meshed with a driven gear assembled to a drum portion (see, for example, Patent Document 1). According to the description in Patent Document 1, since the drive unit and the shaft are assembled to the sheet metal part, the drive mechanism can increase the accuracy between the axes of the drive gear and the driven gear.

Japanese Patent Laid-Open No. 5-127442

  In the drive mechanism described in Patent Document 1, after the shaft and the drive unit (output shaft) are firmly assembled to the sheet metal unit, the drum unit having the driven gear is assembled to the shaft while moving in the direction in which the shaft extends. Assembled in. Therefore, when the work of assembling the drum portion to the shaft is performed, the distance between the shaft and the output shaft is maintained with high accuracy, so there is no allowance in the direction in which the shaft is separated from the output shaft (in other words, In this state, the driven gear and the driven gear do not have a sufficient rotational direction), and the driven gear must be engaged with the drive gear, resulting in poor assembly workability. Such a problem also exists in other general rotation transmission mechanisms such as gears and wheels.

  An object of the present invention is to provide a drive device that can be easily assembled while maintaining the accuracy of the inter-axis distance of the rotation transmission mechanism, and an image forming apparatus including the drive device.

  The present invention includes a rotation transmission wheel having a first insertion hole formed corresponding to a rotation shaft, and a cover member having a holding portion that holds the rotation transmission wheel so as to be movable in a direction orthogonal to the rotation shaft; A drum portion having a drum main body portion and a drum portion that is inserted through the drum portion, and one end portion in the rotation axis direction is inserted into the first insertion hole of the rotation transmission wheel so that the rotation transmission wheel is rotated. The present invention relates to a drive mechanism that includes a shaft that is positioned in a direction orthogonal to and a sheet metal part that supports the one end of the shaft.

  Furthermore, it is preferable to include a positioning portion formed in the drum main body portion, which is inserted into the rotation transmission wheel and positions the rotation transmission wheel in a direction orthogonal to the rotation axis of the rotation transmission wheel.

  The rotation transmission wheel has a first cylindrical inner side surface portion formed on the drum portion side of the first insertion hole in the rotation axis direction, and the positioning portion is rotatably inserted into the shaft. It is preferable to have a second insertion hole and a second cylindrical outer surface portion that is rotatably inserted into the first cylindrical inner surface portion.

  The inner side surface portion of the first cylinder is a side surface of an insertion hole having an inner diameter larger than the inner diameter of the first insertion hole, and the outer surface surface of the second cylinder is a cylinder having an outer diameter substantially equal to the inner diameter of the inner surface portion of the first cylinder. A side surface is preferable.

  It is preferable that the rotation transmission wheel has a rotation transmission wheel main body and a flange portion extending to the drum portion side of the rotation transmission wheel main body, and the first cylindrical inner side surface portion is formed on the flange portion. .

  Furthermore, it is preferable to provide a coupling portion that engages the rotation transmission wheel and the drum portion in a relatively non-rotatable manner.

  The present invention also provides one or more image carriers on which electrostatic latent images are formed on the surface, and a developer for developing a toner image on the electrostatic latent images formed on the one or more image carriers. A transfer unit that directly or indirectly transfers a toner image formed on the image carrier to a transfer material; a fixing unit that fixes the toner image transferred to the transfer material to the transfer material; The present invention relates to an image forming apparatus including any one of the drive mechanisms described above.

  According to the present invention, it is possible to provide a drive device that can be easily assembled while maintaining the accuracy of the inter-axis distance of the rotation transmission mechanism, and an image forming apparatus including the drive device.

FIG. 2 is a front view for explaining the arrangement of each component in the printer as the embodiment of the present invention. It is a perspective view for demonstrating the image formation part GK. FIG. 6 is a partial cross-sectional view seen from the front of a drive mechanism 100a used in the image forming unit GK. It is a partially expanded sectional view of FIG. It is an expanded sectional view which a part of drive mechanism 100a decomposed. FIG. 6 is an enlarged cross-sectional view for explaining an assembly procedure of the drive mechanism 100a following FIG.

Hereinafter, embodiments of an image forming apparatus of the present invention will be described with reference to the drawings.
The overall structure of the printer 1 as the image forming apparatus of the first embodiment will be described with reference to FIG. FIG. 1 is a front view for explaining the arrangement of each component in the printer 1 as the first embodiment of the present invention.

  In the following description, as viewed from the user standing on the front side of the printer 1, the left-right direction is the direction of arrow X, the front-rear (depth) direction is the direction of arrow Y, and the up-down direction is the direction of arrow Z.

  As shown in FIG. 1, a printer 1 as an image forming apparatus includes an apparatus main body M, an image forming unit GK that forms a toner image on a sheet T as a sheet-like transfer material based on predetermined image information, A paper supply / discharge unit KH that supplies the paper T to the image forming unit GK and discharges the paper T on which the toner image is formed.

  The outer shape of the apparatus main body M is configured by a case body BD as a casing.

  As shown in FIG. 1, the image forming unit GK includes photosensitive drums 2a, 2b, 2c, and 2d as image carriers (photosensitive members), charging units 10a, 10b, 10c, and 10d, and a laser as an exposure unit. Scanner units 4a, 4b, 4c, 4d, developing devices 16a, 16b, 16c, 16d, toner cartridges 5a, 5b, 5c, 5d, toner supply units 6a, 6b, 6c, 6d, drum cleaning unit 11a, 11b, 11c, 11d, static eliminators 12a, 12b, 12c, 12d, intermediate transfer belt 7, primary transfer rollers 37a, 37b, 37c, 37d, secondary transfer roller 8, counter roller 18, fixing Part 9.

  As shown in FIG. 1, the paper feed / discharge unit KH includes a paper feed cassette 52, a manual paper feed unit 64, a conveyance path L for paper T, a registration roller pair 80, a plurality of rollers or roller pairs, A paper unit 50. As will be described later, the transport path L is an aggregate of a first transport path L1, a second transport path L2, a third transport path L3, a manual transport path La, and a return transport path Lb.

Hereinafter, each configuration of the image forming unit GK and the paper supply / discharge unit KH will be described in detail.
First, the image forming unit GK will be described.
In the image forming unit GK, the charging units 10a, 10b, 10c, and 10d are sequentially applied to the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d in order as the photosensitive drums 2a, 2b, 2c, and 2d rotate during image formation. Charging by 10d, exposure by laser scanner units 4a, 4b, 4c and 4d, development by developing devices 16a, 16b, 16c and 16d, primary transfer by intermediate transfer belt 7 and primary transfer rollers 37a, 37b, 37c and 37d, Static elimination by the static eliminators 12a, 12b, 12c, and 12d and cleaning by the drum cleaning units 11a, 11b, 11c, and 11d are performed.

  Further, in the image forming unit GK, secondary transfer by the intermediate transfer belt 7, the secondary transfer roller 8 and the counter roller 18, and fixing by the fixing unit 9 are performed.

  Each of the photosensitive drums 2a, 2b, 2c, and 2d is formed of a cylindrical member and functions as a photosensitive member or an image carrier. Each of the photosensitive drums 2a, 2b, 2c, and 2d has an arrow shown in FIG. 1 around a rotation axis extending in a direction orthogonal to the traveling direction of the intermediate transfer belt 7 (rotation axis direction CX in FIG. 2). It is arrange | positioned so that rotation is possible. As shown in FIG. 2, each of the photosensitive drums 2a, 2b, 2c, and 2d is aligned in a row so as to be parallel to each other and extend in the rotation axis direction CX, and the driving mechanisms 100a, 100b, It is assembled to each of 100c and 100d. The photosensitive drums 2a, 2b, 2c, and 2d and the driving mechanisms 100a, 100b, 100c, and 100d form a driving unit 100. An electrostatic latent image can be formed on the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d.

  As shown in FIG. 1, each of the charging units 10a, 10b, 10c, and 10d is disposed to face the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the charging units 10a, 10b, 10c, and 10d uniformly charges the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d to be positive (plus polarity).

  The laser scanner units 4a, 4b, 4c, and 4d function as exposure units, and are spaced apart from the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the laser scanner units 4a, 4b, 4c, and 4d includes a laser light source (not shown), a polygon mirror, a polygon mirror driving motor, and the like.

  Each of the laser scanner units 4a, 4b, 4c, and 4d scans and exposes the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d based on image information input from an external device such as a PC (personal computer). The scanning exposure is performed by each of the laser scanner units 4a, 4b, 4c, and 4d, thereby removing the charges on the exposed portions of the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. Thereby, electrostatic latent images are formed on the respective surfaces of the photosensitive drums 2a, 2b, 2c, and 2d.

  The developing units 16a, 16b, 16c, and 16d are provided corresponding to the photosensitive drums 2a, 2b, 2c, and 2d, respectively, and are disposed to face the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. . Each of the developing units 16a, 16b, 16c, and 16d attaches toner of each color to a portion where the electrostatic charge image formed on the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d is removed, Color toner images are formed on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the developing devices 16a, 16b, 16c, and 16d corresponds to four colors of yellow, cyan, magenta, and black. Each of the developing devices 16a, 16b, 16c, and 16d includes a developing roller disposed opposite to the surface of the photosensitive drums 2a, 2b, 2c, and 2d, a stirring roller for stirring the toner, and the like.

  Each of the toner cartridges 5a, 5b, 5c, and 5d is provided corresponding to each of the developing devices 16a, 16b, 16c, and 16d, and each color toner supplied to each of the developing devices 16a, 16b, 16c, and 16d. To accommodate. Each of the toner cartridges 5a, 5b, 5c, and 5d accommodates yellow toner, cyan toner, magenta toner, and black toner.

  The toner supply units 6a, 6b, 6c, and 6d are provided corresponding to the toner cartridges 5a, 5b, 5c, and 5d and the developing devices 16a, 16b, 16c, and 16d, respectively. The toners of the respective colors accommodated in 5d are supplied to the developing devices 16a, 16b, 16c, and 16d, respectively. The toner supply units 6a, 6b, 6c, and 6d are connected to the developing devices 16a, 16b, 16c, and 16d by toner conveying devices 500a, 500b, 500c, and 500d, respectively.

  To the intermediate transfer belt 7, the toner images of the respective colors formed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially primary-transferred. The intermediate transfer belt 7 is stretched over a driven roller 35, a counter roller 18 that functions as a driving roller, a tension roller 36, and the like. Since the tension roller 36 biases the intermediate transfer belt 7 from the inside to the outside, a predetermined tension is applied to the intermediate transfer belt 7.

  Primary transfer rollers 37a, 37b, 37c, and 37d are arranged to face each other on the side opposite to the photosensitive drums 2a, 2b, 2c, and 2d with the intermediate transfer belt 7 interposed therebetween.

  The intermediate transfer belt 7 is sandwiched between the primary transfer rollers 37a, 37b, 37c, and 37d and the photosensitive drums 2a, 2b, 2c, and 2d, respectively. The sandwiched portion is pressed against the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d. Primary transfer nips N1a, N1b, N1c, and N1d are formed between the photosensitive drums 2a, 2b, 2c, and 2d and the primary transfer rollers 37a, 37b, 37c, and 37d, respectively. In the primary transfer nips N1a, N1b, N1c, and N1d, the toner images of the respective colors formed on the photoreceptor drums 2a, 2b, 2c, and 2d are sequentially primary-transferred onto the intermediate transfer belt 7, respectively. As a result, a full-color toner image is formed on the intermediate transfer belt 7.

  To the primary transfer rollers 37a, 37b, 37c, and 37d, toner images of the respective colors formed on the photosensitive drums 2a, 2b, 2c, and 2d are respectively transferred to the intermediate transfer belt 7 by a primary transfer bias applying unit (not shown). A primary transfer bias for transferring the toner image is applied.

  The static eliminators 12a, 12b, 12c, and 12d are arranged to face the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d, respectively. The static eliminators 12a, 12b, 12c, and 12d respectively irradiate the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d to irradiate light, and the photosensitive drums 2a, 2b, and 2c after the primary transfer is performed. 2d, each surface is neutralized (charge is removed).

  Each of the drum cleaning units 11a, 11b, 11c, and 11d is disposed to face the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the drum cleaning units 11a, 11b, 11c, and 11d removes toner and adhering matter remaining after the primary transfer on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d, and removes the removed toner and the like to a predetermined level. It is transported to the collection mechanism and collected.

  The secondary transfer roller 8 secondarily transfers the full-color toner image primarily transferred to the intermediate transfer belt 7 onto the paper T. A secondary transfer bias for transferring the full color toner image formed on the intermediate transfer belt 7 to the paper T is applied to the secondary transfer roller 8 by a secondary transfer bias applying unit (not shown).

  The secondary transfer roller 8 contacts or separates from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is configured to be movable between a contact position where the secondary transfer roller 8 is in contact with the intermediate transfer belt 7 and a spaced position where the secondary transfer roller 8 is separated from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is disposed at a contact position when the full-color toner image primarily transferred onto the surface of the intermediate transfer belt 7 is secondarily transferred to the paper T, and in other cases. It is arranged at a separated position.

  A counter roller 18 is disposed on the opposite side of the intermediate transfer belt 7 from the secondary transfer roller 8. The intermediate transfer belt 7 is sandwiched between the secondary transfer roller 8 and the opposing roller 18. Then, the paper T is pressed against the outer surface of the intermediate transfer belt 7 (the surface on which the toner image is primarily transferred). A secondary transfer nip N <b> 2 is formed between the intermediate transfer belt 7 and the secondary transfer roller 8. At the secondary transfer nip N2, the full-color toner image primarily transferred to the intermediate transfer belt 7 is secondarily transferred to the paper T.

  The fixing unit 9 melts and presses the toner of each color constituting the toner image secondarily transferred onto the paper T and fixes the toner on the paper T. The fixing unit 9 includes a heating rotator 9a heated by a heater and a pressure rotator 9b pressed against the heating rotator 9a. The heating rotator 9a and the pressure rotator 9b sandwich and pressurize the paper T onto which the toner image has been secondarily transferred, and convey the paper T. When the paper T is conveyed while being sandwiched between the heating rotator 9a and the pressure rotator 9b, the toner transferred to the paper T is fixed on the paper T by being melted and pressurized. Is done.

Next, the paper supply / discharge unit KH will be described.
As shown in FIG. 1, a paper feed cassette 52 that stores paper T is disposed below the apparatus main body M. The paper feed cassette 52 is configured to be able to be pulled out from the case body BD of the apparatus main body M in the horizontal direction. In the paper feed cassette 52, a placement plate 60 on which the paper T is placed is disposed. In the paper feed cassette 52, the paper T is stored in a state of being stacked on the placement plate 60. The paper T placed on the placement plate 60 is sent out to the transport path L by the cassette paper feed unit 51 disposed at the paper feed side end of the paper feed cassette 52 (the right end in FIG. 1). ing. The cassette paper feeding unit 51 includes a forward feed roller 61 for taking out the paper T on the placement plate 60 and a paper feed roller pair 81 for feeding the paper T one by one to the transport path L. Is provided.

  A manual paper feed unit 64 is provided on the right side surface (right side in FIG. 1) of the apparatus main body M. The manual paper feed unit 64 is provided mainly for supplying paper T having a size and type different from the paper T set in the paper feed cassette 52 to the apparatus main body M. The manual paper feed unit 64 includes a manual feed tray 65 that forms part of the right side surface of the apparatus main body M in the closed state, and a paper feed roller 66. The lower end of the manual feed tray 65 is attached to the vicinity of the paper feed roller 66 so as to be rotatable (openable and closable). The paper T is placed on the open manual feed tray 65. The paper feed roller 66 feeds the paper T placed on the open manual feed tray 65 to the manual feed path La.

  The conveyance path L for conveying the paper T includes a first conveyance path L1 from the cassette paper feeding unit 51 to the secondary transfer nip N2, a second conveyance path L2 from the secondary transfer nip N2 to the fixing unit 9, and a fixing unit. 9 to the paper discharge unit 50, the manual conveyance path La for joining the paper supplied from the manual paper feed unit 64 to the first conveyance path L1, and the third conveyance path L3 from the downstream side to the upstream side. And a return conveyance path Lb for reversing the sheet conveyed to the side and returning it to the first conveyance path L1.

  Moreover, the 1st junction part P1 and the 2nd junction part P2 are provided in the middle of the 1st conveyance path L1. A first branch portion Q1 is provided in the middle of the third transport path L3.

The first joining part P1 is a joining part where the manual feed path La joins the first transport path L1. The second junction P2 is a junction where the return conveyance path Lb merges with the first conveyance path L1.
The first branch portion Q1 is a branch portion where the return transport path Lb branches from the third transport path L3.
In the middle of the first conveyance path L1 (specifically, between the second joining portion P2 and the secondary transfer nip N2), a paper detection sensor (not shown) for detecting the paper T, A registration roller pair 80 is arranged for adjusting the timing with skew (oblique feeding) correction and toner image formation in the image forming unit GK. The paper detection sensor is disposed immediately before the registration roller pair 80 in the transport direction of the paper T (upstream in the transport direction). The registration roller pair 80 conveys the paper T by performing the above-described correction and timing adjustment based on detection signal information from the paper detection sensor.

  An intermediate roller pair 82 is disposed between the first joining portion P1 and the second joining portion P2 in the first transport path L1. The intermediate roller pair 82 is disposed on the downstream side in the paper transport direction with respect to the paper feed roller pair 81, sandwiches the paper T transported from the paper feed roller pair 81, and transports the paper T to the registration roller pair 80.

  The return conveyance path Lb is a conveyance path provided in order to make the opposite surface (unprinted surface) opposite to the already printed surface to the intermediate transfer belt 7 when performing duplex printing on the paper T. By the return conveyance path Lb, the paper T conveyed from the first branching section Q1 to the paper discharge section 50 side is reversed and returned to the first conveyance path L1, and is disposed on the upstream side of the secondary transfer roller 8. It can be conveyed to the upstream side of the roller pair 80. A toner image is transferred to the non-printed surface of the paper T that has been turned upside down by the return conveyance path Lb in the secondary transfer nip N2.

  A rectifying member 58 is provided in the first branch portion Q1. The rectifying member 58 rectifies the transport direction of the paper T that is carried out of the fixing unit 9 and transports the third transport path L3 from the upstream side toward the downstream side in a direction toward the paper discharge unit 50 and the paper discharge unit 50. The conveyance direction of the paper T that is conveyed from the downstream side toward the upstream side of the third conveyance path L3 is rectified in a direction toward the return conveyance path Lb.

  A paper discharge unit 50 is formed at the end of the third transport path L3. The paper discharge unit 50 is disposed on the upper part of the apparatus main body M. The paper discharge unit 50 opens toward the left side of the apparatus main body M (left side in FIG. 1). The paper discharge unit 50 discharges the paper T to the outside of the apparatus main body M. The paper discharge unit 50 includes a discharge roller pair 53. The discharge roller pair 53 discharges the paper T conveyed from the upstream side to the downstream side in the third conveyance path L3 to the outside of the apparatus main body M, and reverses the conveyance direction of the paper T in the paper discharge unit 50. The paper T can be transported toward the upstream side of the third transport path L3.

  On the opening side of the paper discharge unit 50, a paper discharge stacking unit M1 is formed. The paper discharge stacking unit M1 is formed on the upper surface (outer surface) of the apparatus main body M. The paper discharge stacking unit M1 is a part formed by the upper surface of the apparatus main body M being depressed downward. The bottom surface of the paper discharge stacking unit M1 constitutes a part of the top surface of the apparatus main body M. In the paper discharge stacking unit M1, sheets T formed with a predetermined toner image and discharged from the paper discharge unit 50 are stacked and stacked.

  A paper detection sensor (not shown) is disposed at a predetermined position on each conveyance path.

Next, the operation of the printer 1 of the first embodiment will be briefly described with reference to FIG.
First, a case where single-sided printing is performed on the paper T stored in the paper feed cassette 52 will be described.
The paper T accommodated in the paper feed cassette 52 is sent out to the first transport path L1 by the forward feed roller 61 and the paper feed roller pair 81, and then intermediated via the first joining portion P1 and the first transport path L1. It is conveyed to the registration roller pair 80 by the roller pair 82.

  In the registration roller pair 80, skew correction of the paper T and timing adjustment with toner image formation in the image forming unit GK are performed.

  The paper T discharged from the registration roller pair 80 is introduced between the intermediate transfer belt 7 and the secondary transfer roller 8 (secondary transfer nip N2) via the first conveyance path L1. A toner image is transferred onto the paper T between the intermediate transfer belt 7 and the secondary transfer roller 8.

  Thereafter, the paper T is discharged from between the intermediate transfer belt 7 and the secondary transfer roller 8, and is interposed between the heating rotator 9a and the pressure rotator 9b in the fixing unit 9 via the second conveyance path L2. Introduced into the fixing nip. Then, the toner melts in the fixing nip, and the toner is fixed on the paper T.

  Next, the paper T is transported to the paper discharge unit 50 through the third transport path L3, and is discharged from the paper discharge unit 50 to the paper discharge stacking unit M1 by the discharge roller pair 53.

In this way, single-sided printing of the paper T stored in the paper feed cassette 52 is completed.
When single-sided printing is performed on the paper T placed on the manual feed tray 65, the paper T placed on the manual feed tray 65 is sent out to the manual feed path La by the paper feed roller 66, and then the first joining portion. It is conveyed to the registration roller pair 80 via P1 and the first conveyance path L1. Subsequent operations are the same as the one-side printing operation of the paper T accommodated in the paper feed cassette 52 described above, and a description thereof will be omitted.

Next, the operation of the printer 1 when performing duplex printing will be described.
In the case of single-sided printing, as described above, the paper T on which single-sided printing has been performed is discharged from the paper discharge unit 50 to the paper discharge stacking unit M1, and the printing operation is completed.

  On the other hand, when performing double-sided printing, the paper T on which single-sided printing has been performed is reversed from the time of single-sided printing and conveyed again to the registration roller pair 80 via the return conveyance path Lb. Then, double-sided printing is performed on the paper T.

  More specifically, the operation is the same as the above-described single-sided printing operation until the paper T on which single-sided printing has been performed is discharged from the paper discharge unit 50 by the discharge roller pair 53. Thus, in the case of double-sided printing, in a state where the paper T on which single-sided printing has been performed is held by the discharge roller pair 53, the rotation of the discharge roller pair 53 is stopped and rotated in the reverse direction. When the discharge roller pair 53 is thus rotated in the reverse direction, the paper T held by the discharge roller pair 53 moves in the reverse direction (the direction from the paper discharge unit 50 toward the first branching unit Q1) along the third conveyance path L3. ).

  As described above, when the paper T is transported in the reverse direction on the third transport path L3, the paper T is rectified to the return transport path Lb by the rectifying member 58, and then, via the second junction P2. Then, it joins the first transport path L1. Here, the paper T is turned upside down from the one-side printing.

  Further, the paper T is corrected or adjusted by the registration roller pair 80, and is introduced into the secondary transfer nip N2 through the first conveyance path L1. Since the unprinted surface of the sheet T passes through the return conveyance path Lb and faces the intermediate transfer belt 7, the toner image is transferred to the unprinted surface, and as a result, duplex printing is performed.

<Drive unit>
Next, details of the drive unit 100 and the drive mechanisms 100a, 100b, 100c, and 100d in the printer 1 of the first embodiment will be described with reference to FIGS.
As shown in FIG. 2, the image forming unit GK includes the driving units 100 having the corresponding driving mechanisms 100a, 100b, 100c, and 100d on the photosensitive drums 2a, 2b, 2c, and 2d, respectively.
The drive unit 100 is a unit obtained by housing the drive mechanisms 100a, 100b, 100c, and 100d in one housing.

<Drive mechanism>
The following description will focus on the driving mechanism 100a corresponding to the photosensitive drum 2a, and description of the driving mechanisms 100b, 100c, and 100d corresponding to the photosensitive drums 2b, 2c, and 2d having the same configuration will be omitted. Here, the configurations of the drive mechanisms 100b, 100c, and 100d are the same as the configuration of the drive mechanism 100a, and the description of the drive mechanism 100a can be cited.

  As shown in FIGS. 3 and 4, the drive mechanism 100a includes a driven gear 110 as a rotation transmission wheel, a cover member 120 having a holding portion 122 for holding the driven gear 110, and a photosensitive drum 2a as a drum portion. The shaft 130 and the sheet metal part 140 are provided.

<Driving gear>
As shown in FIG. 4, the driven gear 110 is accommodated in the internal space 122 a and the flange holding space 122 b of the holding portion 122 formed in the cover member 120. The driven gear 110 is held by the holding portion 122 so as to be movable in a direction orthogonal to the rotation axis C before the shaft 130 is inserted through the first insertion hole 112a. Further, the driven gear 110 is positioned by the holding portion 122 in a direction orthogonal to the rotation axis C after the shaft 130 is inserted into the first insertion hole 112a. The holding part 122 has a boss shape having an inner peripheral surface of a cylindrical side surface extending in the rotation axis direction CX.

  The driven gear 110 includes a gear main body 114a and a flange 114b that protrudes toward the photosensitive drum 2a of the gear main body 114a in the rotation axis direction CX.

The gear main body 114a has a plurality of teeth that can mesh with a plurality of teeth of the drive gear 115 coupled to a drive body (motor). The plurality of teeth are integrally formed on the outer peripheral surface of the cylindrical portion. The gear main body 114 a is disposed in an internal space 122 a formed by the holding portion 122 of the cover member 120 so as to be movable in a direction orthogonal to the rotation axis C.
The flange portion 114b is formed integrally with the gear main body portion 114a. The flange portion 114b is disposed in a columnar flange holding space 122b formed by the holding portion 122 of the cover member 120 so as to be movable in a direction orthogonal to the rotation axis C.

The driven gear 110 has an insertion hole portion 112 formed so as to extend in the rotation axis direction CX around the rotation axis C.
The insertion hole 112 has a first insertion hole 112a and a third insertion hole 112c in the rotation axis direction CX.
The first insertion hole 112a is formed on the gear main body 114a side in the rotation axis direction CX. In the rotation axis direction CX, the first insertion hole 112a opens on the side surface of the gear main body 114a on the side opposite to the photosensitive drum 2a.
The shaft 130 is inserted through the first insertion hole 112a. The driven gear 110 is positioned in a direction orthogonal to the rotation axis C by inserting the shaft 130 through the first insertion hole 121a.

The third insertion hole 112c is formed in the flange portion 114b on the photosensitive drum 2a side of the first insertion hole 112a so as to extend in the rotation axis direction CX around the rotation axis C. The third insertion hole 112c is a portion through which the shaft 130 passes during assembly and the positioning portion 202 is inserted after assembly.
Here, the outline of the third insertion hole 112c is formed by the first cylindrical inner side surface portion 112b.
The driven gear 110 includes a cylindrical first cylindrical inner side surface portion 112b arranged so as to surround the third insertion hole 112c so as to extend in the rotation axis direction CX.
The center of the first cylindrical inner side surface portion 112b is the same as the center of the first insertion hole 112a. The inner diameter of the first cylindrical inner side surface portion 112b is larger than the inner diameter of the first insertion hole 112a.

  In the rotation axis direction CX, the gear main body 114a side of the third insertion hole 112c configured by the first cylindrical inner side surface part 112b is connected to the flange part 114b side of the first insertion hole 112a. In the rotation axis direction CX, the photosensitive drum 2a side of the third insertion hole 112c opens to the side surface of the flange portion 114b. Therefore, the third insertion hole 112c and the first insertion hole 112a form an insertion hole 112 that penetrates the center of the driven gear 110 in the rotation axis direction CX. The insertion hole portion 112 has a structure in which the inner diameter gradually decreases from the flange portion 114b side toward the gear main body portion 114a side. Therefore, the third insertion hole 112c is an insertion hole having an inner diameter larger than the inner diameter of the first insertion hole 112a.

<Photosensitive drum and positioning part>
As shown in FIG. 4, the photosensitive drum 2 a includes a cylindrical drum main body 201 and a positioning portion 202 formed at one end of the drum main body 201 on the driven gear 110 side.

  The positioning portion 202 is relatively rotatable with the first cylindrical inner side surface portion 112b of the driven gear 110 and is relatively rotatable with respect to the second cylindrical outer surface portion 202a, and with respect to the main body portion 130b of the shaft 130. It has a substantially cylindrical shape having a second insertion hole 202b of a size that allows relative sliding.

  The second cylindrical outer surface portion 202a of the positioning portion 202 is sized to be inserted into the first cylindrical inner surface portion 112b so as to be relatively rotatable. The second cylindrical outer surface portion 202a is formed so that the outer diameter is substantially equal to the inner diameter of the first cylindrical inner surface portion 112b. The 2nd penetration hole 202b of the positioning part 202 is penetrated so that it can rotate relatively to the main-body part 130b of the shaft 130 mentioned later.

  The positioning unit 202 positions the driven gear 110 in a direction perpendicular to the rotation axis C while being inserted into the first cylindrical inner side surface portion 112b of the driven gear 110 of the second cylindrical outer surface portion 202a.

<Cover member>
The cover member 120 is disposed on the photosensitive drum 2a side in the sheet metal part 140 described later.
The cover member 120 has a holding portion 122 that holds the driven gear 110. The holding unit 122 holds the driven gear 110 that is movable in a direction orthogonal to the rotation axis C.
The cover member 120 has an internal space 122a that holds the gear main body portion 114a and a flange holding space 122b that holds the flange portion 114b.
Specifically, in the holding portion 122, the internal space 122a holds the gear body portion 114a so as to be movable in a direction orthogonal to the rotation axis C, and the flange portion 114b moves in a direction orthogonal to the rotation axis C. It is held in the flange holding space 122b as possible.
That is, the holding portion 122 holds the driven gear 110 so as to be movable in a direction orthogonal to the rotation axis C before the main body portion 130b of the shaft 130 is inserted into the driven gear 110 (a state in which the main body portion 130b is not inserted). . Further, the holding unit 122 holds the driven gear 110 so as to be rotatable around the rotation axis C in a state after the shaft 130 described later is inserted into the driven gear 110 (a state in which the shaft 130 is inserted).

<Shaft>
As shown in FIG. 3, the shaft 130 is a columnar (rod-shaped) member that is longer than the photosensitive drum 2a in the rotation axis direction CX. The shaft 130 has a main body portion 130b and one end portion 130a having a truncated cone portion 130c.

  As shown in FIG. 4, the shaft 130 is disposed such that one end portion 130a is inserted into a second insertion hole 202b formed in the positioning portion 202 of the photosensitive drum 2a so as to be relatively slidable and relatively rotatable. At the same time, the driven gear 110 is inserted into the first insertion hole 112 a of the driven gear 110 to position the driven gear 110 in a direction orthogonal to the rotation axis C.

  The shaft 130 is disposed so that the truncated cone portion 130 c of the one end portion 130 a passes through the positioning hole 144 formed in the sheet metal portion 140 and the one end portion 130 a is fitted into the positioning hole 144. Therefore, the shaft 130 is accurately positioned in the direction orthogonal to the rotation axis C by the positioning hole 144 formed in the sheet metal part 140.

  The shaft 130 is assembled in the positioning hole 144 of the sheet metal part 140 so as not to be relatively rotatable, and holds the driven gear 110 so as to be relatively rotatable. Thereby, the driven gear 110 is rotatably held by the shaft 30 while being positioned with respect to the sheet metal part 140.

<Sheet metal part>
The sheet metal part 140 is formed with an insertion hole 142 into which the gear support shaft 116 that supports the drive gear 115 that can mesh with the driven gear 110 is fitted. The drive gear 115 is firmly and rotatably supported on the sheet metal part 140 via a gear support shaft 116.

The sheet metal part 140 is held in a state where the drive gear 115 is positioned. Here, the sheet metal part 140 holds the driven gear 110 in a state of being positioned via the shaft 130.
Therefore, the sheet metal part 140 holds the drive gear 115 and the driven gear 110 at a highly accurate center distance.
More specifically, the sheet metal part 140 moves the driven gear 110 by the shaft 130 being inserted into the positioning hole 144 of the sheet metal part 140, and is held at a predetermined position with a high precision distance between the drive gear 115 and the axis. To do.

<Coupling part>
The drive mechanism 100a includes a coupling portion 210 that can connect the driven gear 110 and the photosensitive drum 2a so as not to be relatively rotatable. The coupling part 210 has a hub part 210a formed on the flange part 114b and a hub part 210b formed on the photosensitive drum 2a that meshes with the hub part 210a. The hub portion 210a is a plurality of pillar members having a fan-shaped bottom surface around the first cylindrical inner side surface portion 112b formed on the end surface of the flange portion 114b on the photosensitive drum 2a side. The hub portion 210b is a plurality of pillar members having a fan-shaped bottom surface provided around the second cylindrical outer surface portion 202a of the positioning portion 202 formed on the end surface of the driven gear 110 of the drum main body portion 201. The hub portion 210a and the hub portion 210b have a structure in which the hub portion 210a and the hub portion 210b mesh with each other so as not to be relatively rotatable in the direction around the rotation axis C.

As shown in FIGS. 5 and 6, the drive mechanism 100a is assembled as follows.
First, the operator inserts the shaft 130 into the second insertion hole 202b of the positioning portion 202 of the photosensitive drum 2a. Since the inner diameter of the second insertion hole 202b and the outer diameter of the shaft 130 are substantially the same, the shaft 130 is inserted into the positioning portion 202 so as to be slidable in the extending direction of the rotating shaft C and the rotating direction of the rotating shaft C. Is done.

  Next, the operator inserts the one end portion 130 a of the shaft 130 into the third insertion hole 112 c of the driven gear 110. At this time, since the operator can move the driven gear 110 in the direction orthogonal to the rotation axis C by the holding portion 122, the shaft 130 can be easily inserted into the third insertion hole 112c.

  As shown in FIG. 6, the operator further inserts one end portion 130 a of the shaft 130 into the third insertion hole 112 c of the driven gear 110. At this time, since the one end portion 130a of the shaft 130 is a truncated conical portion 130c having a tapered shape, the operator inserts the shaft 130 into the first insertion hole 112a having an inner diameter smaller than that of the third insertion hole 112c. Can be inserted easily.

  Further, when the shaft 130 is inserted into the driven gear 110, the truncated cone portion 130 c of the one end portion 130 a of the shaft 130 is inserted into the positioning hole 144. At this time, as the shaft 130 is inserted into the positioning hole 144, the driven gear 110 is positioned while moving in the direction orthogonal to the rotation axis C. The positioned driven gear 110 meshes with the drive gear 115 to constitute the rotation transmission mechanism 101. Since both the drive gear 115 and the driven gear 110 are assembled to the sheet metal part 140, the accuracy of the inter-axis distance of the rotation transmission mechanism 101 can be maintained.

  Further, when the shaft 130 is inserted through the driven gear 110, the second cylindrical outer side surface portion 202a of the positioning portion 202 is fitted to the first cylindrical inner side surface portion 112b. Accordingly, the driven gear 110 is configured such that the first insertion hole 112a and the shaft 130 are fitted, the first cylindrical inner side surface portion 112b and the second cylindrical outer side surface portion 202a are fitted, and the second insertion hole 202b. And the main body portion 130b of the shaft 130 are fitted to each other and supported by the shaft 130.

  Further, when the shaft 130 is inserted into the driven gear 110, the hub portion 210a and the hub portion 210b of the coupling portion 210 are engaged as shown in FIG. 4, and the rotation of the driven gear 110 causes the coupling portion 210 to rotate. Via the photosensitive drum 2a.

  As described above, according to this embodiment, it is possible to provide a drive device that can be easily assembled and an image forming apparatus including the drive device while maintaining the accuracy of the inter-axis distance of the rotation transmission mechanism. That is, since the driven gear 110 is supported by the cover member 120 so as to be movable in a direction perpendicular to the rotation axis of the driven gear 110, the shaft 130 is inserted into the driven gear 110. Positioning in a direction perpendicular to the rotation axis is performed. Therefore, the shaft 130 can be inserted into the driven gear 110 in a state where the driven gear 110 is accurately engaged with the drive gear 115.

<Other embodiments>
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various forms can be adopted.
The type of the image forming apparatus of the present invention is not particularly limited, and may be a copier, a printer, a facsimile, or a complex machine thereof.
The sheet-shaped transfer material is not limited to paper, and may be a film sheet, for example.
Although the shaft 130 has been described as being relatively non-rotatably assembled to the positioning hole 144, the present invention is not limited thereto, and the shaft 130 may be assembled to the positioning hole 144 so as to be relatively rotatable.

  C: Rotating shaft, 100: Driving unit, 100a, 100b, 100c, 100d ... Driving mechanism, 110 ... Driven gear (rotation transmission wheel), 112 ... Insertion hole portion, 112a ... First insertion hole, 112b... First cylindrical inner side surface portion, 112c... Third insertion hole, 114a... Gear body portion, 114b .. Flange portion, 115... Drive gear, 116. ...... Holding part, 122a ... Internal space, 122b ... Flange holding space, 130 ... Shaft, 130a .... One end part, 130b..Main body part, 130c. ····························································································································· Part, 210a, 210b ...... hub portion

Claims (7)

A rotation transmission wheel having a first insertion hole formed corresponding to the rotation shaft;
A cover member having a holding portion for holding the rotation transmission wheel so as to be movable in a direction perpendicular to the rotation axis;
A drum portion having a drum body portion;
A shaft that is disposed so as to be inserted through the drum portion and that has one end portion in the direction of the rotation axis inserted into the first insertion hole of the rotation transmission wheel to position the rotation transmission wheel in a direction orthogonal to the rotation axis; ,
And a sheet metal part that supports the one end part of the shaft. The positioning unit further includes a positioning unit formed in the drum main body unit, the positioning unit being inserted into the rotation transmission wheel and positioning the rotation transmission wheel in a direction orthogonal to a rotation axis of the rotation transmission wheel. The drive mechanism described. The rotation transmission wheel is
A first cylindrical inner side surface portion formed on the drum portion side of the first insertion hole in the rotation axis direction;
The positioning part is
A second insertion hole that is rotatably inserted into the shaft;
The drive mechanism according to claim 2, further comprising a second cylindrical outer surface portion that is rotatably inserted into the inner surface portion of the first cylinder. The first cylindrical inner side surface is a side surface of the insertion hole having an inner diameter larger than the inner diameter of the first insertion hole,
The drive mechanism according to claim 3, wherein the second cylindrical outer surface portion is a cylindrical side surface having an outer diameter substantially equal to an inner diameter of the first cylindrical inner surface portion. The rotation transmission wheel has a rotation transmission wheel main body, and a flange portion extending to the drum portion side of the rotation transmission wheel main body,
The drive mechanism according to claim 3 or 4, wherein the first cylindrical inner side surface portion is formed on the flange portion. Furthermore, the drive mechanism in any one of Claim 1 to 5 provided with the coupling part which engages the said rotation transmission wheel and the said drum part relatively non-rotatably. One or more image carriers on which electrostatic latent images are formed; and
A developer for developing a toner image on the electrostatic latent image formed on the one or more image carriers;
A transfer unit that directly or indirectly transfers the toner image formed on the image carrier to a transfer material;
A fixing unit for fixing the toner image transferred to the transfer material to the transfer material;
An image forming apparatus comprising: the drive mechanism according to claim 1.

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