JP6610996B2 - Driving force transmission device and image forming apparatus having the same - Google Patents

Description

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

  2. Description of the Related Art Conventionally, there is known an image forming apparatus configured to be detachable from a main body of an image forming apparatus in order to cope with deterioration or damage of a rotating body mounted on the image forming apparatus with time. .

  For example, in Patent Document 1, a drive shaft of an image forming apparatus body is passed through each insertion hole formed in both end walls of a hollow cylindrical photosensitive body (rotating body), and the photosensitive body is attached to the image forming apparatus body. An image forming apparatus to be mounted is disclosed. In this image forming apparatus, the driving force from the driving source of the main body of the image forming apparatus is transmitted to the rotating body via the drive shaft, thereby rotating the rotating body.

  In general, a rotating body that is detachable with respect to the image forming apparatus main body is required to have a high accuracy of the rotation center position with respect to the image forming apparatus main body. With the image forming apparatus disclosed in Patent Document 1, since both ends of the photosensitive member (rotating body) are positioned on the same drive shaft on the image forming apparatus main body, high accuracy is achieved with respect to the rotation center position of the rotating body. It's easy to do. However, in order to realize this, in addition to a high part accuracy required for the drive shaft, the drive shaft is a long member extending between both end portions of the rotating body, and therefore sufficient for bending or bending. It is required to ensure rigidity. For this reason, conventional drive shafts are often manufactured by cutting stainless steel round bars with high precision, and the cost of drive shaft parts is reduced due to high material costs and low yield due to high part precision. There was a problem of being expensive.

In order to solve the above-described problem, the present invention relates to the rotation that is mounted in a state in which the drive shaft of the image forming apparatus main body passes through both ends in the rotation axis direction of the rotating body that is detachable from the image forming apparatus main body. the body, the driving force transmission device for transmitting the driving force through the driving shaft, the drive shaft is composed of at least two flat plate portions flat surface is not parallel with the long axially, wherein A fitting member that fits to the inner surface of a support hole formed in the support portion of the image forming apparatus main body that rotatably supports the tip end portion of the drive shaft is attached to the drive shaft. A first fitting member that fits into the inner surface of the support hole, and a second fitting member that fits into the inner surface of the through hole formed at the end of the rotating shaft on the distal end side of the drive shaft. Having an outer peripheral surface of the first fitting member than an outer peripheral surface of the second fitting member. Characterized that they are not protrude radially outward of the drive shaft.

  According to the present invention, sufficient rigidity of the drive shaft can be ensured at low cost, so that an excellent effect is achieved that high accuracy can be realized at low cost with respect to the rotation center position of the rotating body.

FIG. 2 is a cross-sectional view schematically showing a photosensitive drum in a state where a front side plate is attached after the process cartridge in the embodiment is mounted on the copying machine main body. 1 is an overall schematic diagram of a copier according to an embodiment. 2 is an external perspective view of the process cartridge when viewed from the front side of the copying machine main body. FIG. FIG. 3A is a perspective view showing a positional relationship between a photosensitive drum and a developing roller in a process cartridge as viewed from the front side of the copying machine main body. FIG. 2B is a perspective view showing the positional relationship between the photosensitive drum and the developing roller in the process cartridge as viewed from the back side of the copying machine main body. FIG. 2 is a perspective view showing a schematic configuration of a mounting space of a copying machine main body in which the process cartridge is mounted. (A) is a perspective view showing a drum shaft of an embodiment, (b) is a perspective view showing a drum shaft in a state where a photosensitive drum is mounted. It is sectional drawing which shows the cross section orthogonal to the axial direction in the axial part of the drum shaft. It is sectional drawing which shows the cross section orthogonal to the axial direction in the axial part of the drum axis | shaft which concerns on a modification. It is sectional drawing which shows the cross section orthogonal to the axial direction in the axial part of the drum axis | shaft which concerns on another modification. It is sectional drawing which shows the cross section orthogonal to the axial direction in the axial part of the drum axis | shaft which concerns on another modification. It is a perspective view which shows the state which the guide member on the axial part of a drum shaft fits in the inner surface of the bearing member provided in the front side board. It is the perspective view which expanded the front-end | tip part of the drum axis | shaft. It is the perspective view which expanded the rear side part of the drum axis | shaft. It is sectional drawing which shows the rear side part of the state in which the photoconductive drum was mounted | worn with the same drum axis | shaft. (A) is a top view when a fitting member is seen from an axial direction, (b) is an enlarged view of the part enclosed with the broken line in the figure (a).

Hereinafter, an embodiment in which the present invention is applied to an electrophotographic color copier as an image forming apparatus will be described with reference to the drawings.
First, an overall outline of the copying machine 500 of this embodiment will be described.
FIG. 2 is an overall schematic diagram of the copying machine 500 according to the present embodiment.
The copier 500 in the present embodiment is a so-called tandem image forming apparatus, and employs a dry two-component developing system using a dry two-component developer. The copying machine 500 includes a copying machine main body 100, a paper feed table 200 on which the copying machine main body 100 is placed, a scanner 300 mounted on the copying machine main body 100, and an automatic document feeder 400 mounted on the scanner 300. Yes.

  The copier 500 receives image data that is image information read from the scanner 300 or print data from an external device such as a personal computer to perform image forming processing. As shown in the figure, the copying machine main body 100 includes a cylindrical latent image carrier as four rotating bodies for each color of yellow (Y), magenta (M), cyan (C), and black (Bk). The photosensitive drums 1Y, 1M, 1C, and 1Bk are arranged in parallel. These photosensitive drums 1Y, 1M, 1C, and 1Bk are arranged along the belt moving direction so as to contact the endless belt-shaped intermediate transfer belt 5 supported by a plurality of rotatable rollers including a driving roller. Has been placed.

  Further, around the photosensitive drums 1Y, 1M, 1C, and 1Bk, chargers 2Y, 2M, 2C, and 2Bk, developing devices 9Y, 9M, 9C, and 9Bk corresponding to the respective colors, and cleaning devices 4Y, 4M, 4C, and 4B, respectively. Electrophotographic process members such as 4Bk and static elimination lamps 3Y, 3M, 3C, and 3Bk are arranged in the order of processes. An optical writing device 17 is provided above each photosensitive drum 1. In addition, primary transfer rollers 6Y, 6M, 6C, and 6Bk, which are primary transfer units, are disposed at positions facing each other through the intermediate transfer belt 5 of each photosensitive drum 1.

  The intermediate transfer belt 5 is stretched around stretching rollers 11, 12, 13 and a tension roller 14, and is driven to rotate by the rotation of the stretching roller 12, which is a driving roller that is rotationally driven by a driving source. A belt cleaning device 19 is provided at a position where the stretching roller 13 faces through the intermediate transfer belt 5 to remove residual toner remaining on the intermediate transfer belt 5 after the secondary transfer. The stretching roller 11 is a secondary transfer facing roller that faces the secondary transfer roller 7 that is a secondary transfer unit, and is interposed between the secondary transfer roller 7 and the secondary transfer roller 7 via the intermediate transfer belt 5. Forming part.

  On the downstream side of the secondary transfer nip portion in the transfer sheet conveyance direction, a transfer sheet conveyance belt 15 stretched around a tension roller pair 16 is provided, and the transfer sheet on which the toner image is secondarily transferred is fixed to the fixing device. Transport to 18. The fixing device 18 includes a fixing roller pair 8, and heat and pressure are applied at the fixing nip portion to fix the unfixed toner image on the transfer paper.

Next, the copying operation of the copying machine 500 in this embodiment will be described.
When a full-color image is formed by the copying machine 500 according to the present embodiment, first, a document is set on the document table 401 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 301 of the scanner 300, and the automatic document feeder 400 is closed and pressed. Thereafter, when the user presses the start switch, when the document is set on the automatic document feeder 400, the document is conveyed onto the contact glass 301. Then, the scanner 300 is driven and the first traveling body 302 and the second traveling body 303 start traveling. Thereby, the light from the first traveling body 302 is reflected by the document on the contact glass 301, and the reflected light is reflected by the mirror of the second traveling body 303 and guided to the reading sensor 305 through the imaging lens 304. . In this way, the image information of the original is read.

  When the start switch is pressed by the user, the motor is driven, the stretching roller 12 as a driving roller is rotated, and the intermediate transfer belt 5 is rotated. At the same time, the photoconductor drum 1Y is uniformly charged by the charger 2Y while being driven to rotate in the direction of the arrow in the drawing by a photoconductor drive device described later. Thereafter, a light beam Ly from the optical writing device 17 is irradiated to form a Y electrostatic latent image on the photosensitive drum 1Y. This Y electrostatic latent image is developed with Y toner in the developer by the developing device 9Y. During development, a predetermined developing bias is applied between the developing roller 91 and the photosensitive drum 1Y, and the developing roller is formed in a predetermined gap (developing gap) formed between the developing roller 91 and the photosensitive drum 1Y. The Y toner on 91 is electrostatically attracted to the Y electrostatic latent image portion on the photosensitive drum 1Y.

  The Y toner image developed and formed in this way is conveyed to a primary transfer position where the photosensitive drum 1Y and the intermediate transfer belt 5 come into contact with the rotation of the photosensitive drum 1Y. At the primary transfer position, a predetermined bias voltage is applied to the back surface of the intermediate transfer belt 5 by the primary transfer roller 6Y. The Y toner image on the photosensitive drum 1Y is drawn toward the intermediate transfer belt 5 by the primary transfer electric field generated by this bias application, and is primarily transferred onto the intermediate transfer belt 5. Thereafter, similarly, the M toner image, the C toner image, and the Bk toner image are also primarily transferred so as to sequentially overlap the Y toner image on the intermediate transfer belt 5. The transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer is removed by the belt cleaning device 19.

  When the user presses the start switch, the paper feed roller 202 of the paper feed table 200 corresponding to the transfer paper selected by the user rotates, and the transfer paper is sent out from one of the paper feed cassettes 201. The transferred transfer paper is separated into one sheet by the separation roller 203 and enters the paper feed path 204, and is transported to the paper feed path 101 in the copying machine main body 100 by the transport roller 205. The transfer paper conveyed in this way is stopped when it strikes the registration roller 102. When using transfer paper that is not set in the paper feed cassette 201, the transfer paper set on the manual feed tray 105 is fed out by the paper feed roller 104 and separated into one sheet by the separation roller 108, and then the manual paper feed path. It is conveyed through 103. Then, it stops when it hits the registration roller 102.

  The toner images having the four colors superimposed on the intermediate transfer belt 5 are conveyed to a secondary transfer position facing the secondary transfer roller 7 as the intermediate transfer belt 5 rotates. Further, the registration roller 102 starts to rotate in accordance with the timing at which the composite toner image formed on the intermediate transfer belt 5 as described above is conveyed to the secondary transfer position, and the transfer paper is moved to the secondary transfer position. Transport. At this secondary transfer position, a predetermined bias voltage is applied to the back surface of the transfer paper by the secondary transfer roller 7, and due to the secondary transfer electric field generated by the bias application and the contact pressure at the secondary transfer position, The toner image on the intermediate transfer belt 5 is secondarily transferred onto the transfer paper at once. Thereafter, the transfer paper onto which the toner image has been secondarily transferred is conveyed to the fixing device 18 by the transfer paper conveying belt 15 and subjected to fixing processing by the fixing roller pair 8 provided in the fixing device 18. The transfer sheet on which the fixing process has been performed is discharged and stacked in a discharge tray 107 provided outside the apparatus by a discharge roller pair 106.

  In the present embodiment, the photosensitive drums 1Y, 1M, 1C, and 1Bk for each color and the developing devices 9Y, 9M, 9C, and 9Bk arranged around these are processes that are detachable from the copying machine main body 100 for each color. It consists of a cartridge. Specifically, the process cartridges for the respective colors are photosensitive drums 1Y, 1M, 1C, 1Bk, chargers 2Y, 2M, 2C, 2Bk, developing devices 9Y, 9M, 9C, 9Bk, cleaning devices 4Y, 4M, 4C, 4Bk and static elimination lamps 3Y, 3M, 3C, and 3Bk are integrally supported. Any process cartridge including at least the photosensitive drums 1Y, 1M, 1C, and 1Bk and the developing devices 9Y, 9M, 9C, and 9Bk may be used.

Next, the configuration of the process cartridge in the present embodiment will be described.
The process cartridges of the respective colors have substantially the same configuration except that the color of the toner to be used is different, so that the color-coded symbols are appropriately omitted below.

FIG. 3 is an external perspective view of the process cartridge according to the present embodiment when viewed from the front side of the copying machine main body.
FIG. 4 is a perspective view showing the positional relationship between the photosensitive drum 1 and the developing roller 91 in the process cartridge according to the present embodiment, and FIG. 4A is a perspective view when viewed from the front side of the copying machine main body. FIG. 4B is a perspective view when viewed from the back side of the copying machine main body. 4A and 4B illustrate the positional relationship between the photosensitive drum and the developing roller, and the charger 2, the cleaning device 4, the stirring screws 92 and 93 of the developing device 9, and the like are omitted. is there.
FIG. 5 is a perspective view showing a schematic configuration of a mounting space of the copying machine main body 100 in which the process cartridge of the present embodiment is mounted.

  The process cartridge according to the present embodiment is mounted on the copying machine main body 100 by being inserted into the mounting space in the copying machine main body 100 from the front side to the back side of the apparatus in the direction indicated by arrow A in the drawing. As shown in FIG. 5, a drum shaft 50 is provided in the mounting space in the copying machine main body 100 so as to protrude from the structure of the copying machine main body located on the back side of the mounting space. When the process cartridge is inserted into the copying machine main body 100, the drum shaft 50 provided in the copying machine main body 100 is inserted into the photosensitive drum in the process cartridge.

  In the process cartridge according to the present embodiment, the photosensitive drum 1 and the developing roller 91 of the developing device 9 are each a front side plate member formed by a single member that is a common support member at each end in the rotation axis direction. 61 and a rear side plate member 62 are rotatably supported. The front side plate member 61 is a plate-like member in which a through hole 61a into which the shaft of the photosensitive drum is inserted and a through hole 61b into which the shaft of the developing roller is inserted are integrally formed. Similarly, the rear side plate member 62 is a plate-like member in which a through hole 62a into which the shaft of the photosensitive drum is inserted and a through hole 62b into which the shaft of the developing roller is inserted are integrally formed. As a result, the distance between the through holes that receive the respective axes is kept constant.

FIG. 1 is a cross-sectional view schematically showing the photosensitive drum 1 with a front side plate attached after the process cartridge is mounted on the copying machine main body.
In the process cartridge of this embodiment, the photosensitive drum 1 is held in a temporarily positioned state in the process cartridge by a cartridge frame 68 of the process cartridge. In FIG. 1, the cartridge frame 68, front side plate member 61, and rear side plate member 62 of the process cartridge are omitted. When the process cartridge is inserted into the copying machine main body 100, the drum shaft 50 provided in the copying machine main body 100 includes a rear side through hole provided in the rear side plate member 62 of the process cartridge and a rear side through hole in the cartridge frame 68. Is inserted from.

  The drum shaft 50 has a shaft portion 50a as a drive shaft that is long in the axial direction, and an end portion of the shaft portion 50a on the back side (rear side) of the copying machine main body is a motor as a drive source via a speed reducer 74. 75. When the motor 75 is driven, the driving force is transmitted to the shaft portion 50a via the speed reducer 74, and the drum shaft 50 is rotationally driven.

On the shaft portion 50 a of the drum shaft 50, there is provided a bearing portion 73 formed of a ball bearing that is fitted into a support hole 72 a provided in the rear side plate 72 of the copying machine body. And is supported rotatably.
Further, on the shaft portion 50 a of the drum shaft 50, a bearing portion 65 including a ball bearing that is fitted into the rear side plate member 62 of the process cartridge and the rear side through hole of the cartridge frame 68 is provided. As a result, the rear side plate member 62 and the cartridge frame 68 of the process cartridge are supported so as to be rotatable relative to the drum shaft 50.

A drive gear 51 is fixed on the shaft portion 50a of the drum shaft 50 on the front side (front side) of the copier body of the bearing portion 65. When the process cartridge is inserted into the copying machine main body 100, the driving gear 51 is connected to a driven gear 63 provided at the rear side end of the photosensitive drum 1.
In the present embodiment, as will be described later, since the shaft portion 50a of the drum shaft 50 has an irregular cross-sectional shape that is not a circular cross section, the rear side end portion of the photosensitive drum 1 is positioned with respect to the shaft portion 50a. A fitting member 66 is provided on the shaft portion 50a. The fitting member 66 has a circular cross-sectional shape orthogonal to the axial direction, and is fitted into a circular through hole 63a formed at the axial center of the driven gear 63 of the photosensitive drum 1 so as to be photosensitive. The rear end of the body drum 1 is positioned with respect to the drum shaft 50.

  Further, a positioning member 64 that fits into a through hole 1 a provided at the front side end portion of the photosensitive drum 1 is also provided on the shaft portion 50 a of the drum shaft 50. In this embodiment, in order to position the front side end portion of the photosensitive drum 1 with higher accuracy with respect to the drum shaft 50, a bearing member made of a ball bearing is used as the positioning member 64. 1 does not rotate relative to the drum shaft 50.

  Further, on the shaft portion 50a of the drum shaft 50, an inner surface of a bearing member 71 formed of a ball bearing provided on a front side plate 70 installed on the front side of the process cartridge after the process cartridge is mounted on the copying machine main body 100. A guide member 67 that fits in is provided. The guide member 67 includes a cylindrical portion 67a having a circular cross section perpendicular to the axial direction, and a tapered portion 67b continuous from the cylindrical portion 67a to the front side. The cylindrical portion 67 a of the guide member 67 is fitted into the inner surface 71 a of the bearing member 71 of the front side plate 70, so that the front side end portion (tip portion) of the drum shaft 50 is rotatably supported with respect to the front side plate 70. .

  When the process cartridge is inserted into the copying machine main body 100, the front end side (front side) of the drum shaft 50 first passes through the rear side through hole of the process cartridge and is provided on the rear side end portion of the photosensitive drum 1. It passes through the circular through hole 63a of the drive gear 63, and further passes through the through hole 1a provided at the front side end of the photosensitive drum 1, and is inserted into the front side through hole of the cartridge frame. As a result, the bearing portion 65 of the drum shaft 50 is inserted into the rear side through hole of the process cartridge, and the fitting member 66 of the drum shaft 50 is inserted into the circular through hole 63a of the driven gear 63 of the photosensitive drum 1. The positioning member 64 of the shaft 50 is inserted into the through hole 1 a of the photosensitive drum 1. When the process cartridge is inserted into the copying machine main body 100 until the driving gear 51 on the drum shaft 50 is connected to the driven gear 63 of the photosensitive drum 1, the process cartridge is mounted on the copying machine main body 100. Become.

  In the present embodiment, the drive gear 51 on the drum shaft 50 constitutes a spline coupling together with the driven gear 63 of the photosensitive drum 1. Specifically, the external gear formed on the drive gear 51 meshes with the internal gear formed on the driven gear 63 of the photosensitive drum 1. In the photosensitive drum 1, the fitting member 66 of the drum shaft 50 is fitted into the circular through hole 63 a of the driven gear 63 of the photosensitive drum 1, and the positioning member 64 of the drum shaft 50 is the photosensitive drum 1. By being fitted into the through hole 1a, the drum shaft 50 is positioned with high accuracy.

  In this embodiment, after the process cartridge is mounted on the copying machine main body 100, as shown in FIG. 1, the front side plate 70 is attached to the copying machine main body 100 located on the front side of the process cartridge. The front side plate 70 is fixed to the front body frame of the copying machine main body 100 by, for example, screw fastening. The front side plate 70 is provided with a bearing member 71 for bearing the drum shaft 50 via a guide member 67. By attaching the front side plate 70, the front side of the drum shaft 50 is rotatable with respect to the front side plate 70. Supported. As a result of the drum shaft 50 being stably positioned with respect to the copying machine main body 100 in this way, the photosensitive drum 1 positioned with respect to the drum shaft 50 is also stably positioned with respect to the copying machine main body 100. .

Next, the shaft portion 50a of the drum shaft 50 in the present embodiment will be described in detail.
FIG. 6A is a perspective view showing the drum shaft 50, and FIG. 6B is a perspective view showing the drum shaft 50 with the photosensitive drum 1 mounted thereon.
FIG. 7 is a cross-sectional view showing a cross section orthogonal to the axial direction in the shaft portion 50a of the drum shaft 50 of the present embodiment.
The shaft portion 50a of the drum shaft 50 conventionally has a circular cross-sectional shape (a cross-sectional shape orthogonal to the axial direction; the same applies hereinafter), but in this embodiment, as shown in FIG. The shape is a non-circular shape. Specifically, the shaft portion 50a of the present embodiment has a shape having at least one flat plate portion having a plane parallel to the axial direction and long in the axial direction. The shaft portion 50a illustrated in FIG. The two flat plate portions 50a-1, 50a-2, 50a-3 are radially arranged from the axial center.

Thus, if the shaft portion 50a has a deformed shape having the flat plate portions 50a-1, 50a-2, and 50a-3, it becomes possible to perform shape processing by rolling that facilitates high-precision processing, and as a result, the shaft A relatively inexpensive rolled material can be used as the material of the portion 50a. Thereby, it becomes possible to produce the axial part 50a at low cost.
Moreover, the flat plate portion has low rigidity with respect to the bending from the normal direction with respect to the plane (if the flat plate portion 50a-1 in FIG. 7 is bent from the horizontal direction in FIG. 7), Rigidity is high with respect to bending from a parallel direction (if the flat plate portion 50a-1 in FIG. 7 is bent from the vertical direction in FIG. 7). Therefore, if the shaft portion 50a is configured such that the planes of the flat plate portions 50a-1, 50a-2, 50a-3 forming the shaft portion 50a are parallel to the direction of bending or bending that can occur in the drum shaft 50. Sufficient rigidity can be ensured.

  As the irregular shape, in addition to those illustrated in FIG. 7, for example, as shown in FIG. 8, four flat plate portions 50a-1, 50a-2, 50a-3, 50a-4 are radially arranged from the axial center. A shape in which three or more flat plate portions are arranged radially from the axial center can be given.

  Further, as shown in FIG. 9, the flat plate portions 50 a-1, 50 a-2, and 50 a-3 are combined in a H-shaped cross section so that the plane directions of the flat plate portions are mutually different. The shape may be a combination of two or more flat plate portions so as to be different (for example, so as to be orthogonal to each other).

  Moreover, as an irregular shape, as shown in FIG. 10, the cross-sectional hexagon which has the hollow part enclosed by six flat plate part 50a-1, 50a-2, 50a-3, 50a-4, 50a-5, 50a-6. A shape having a hollow portion surrounded by three or more flat plate portions may be used.

  Here, the detachable members such as the photosensitive drum 1 and the front side plate 70 that are attached to and detached from the drum shaft 50 are normally holes 63a and 1a formed in the detachable members when positioned with respect to the drum shaft 50. , 71a, the drum shaft 50 is fitted and positioned. Since the hole formed in the detachable member is required to be formed with high positional accuracy, it is usually a hole having a circular cross section. On the other hand, in the drum shaft 50 of the present embodiment, the shaft portion 50a fitted into the holes 63a, 1a, 71a has an irregular shape, and the cross section thereof is non-circular. Therefore, it is difficult to stably maintain the fitted state of the irregularly shaped shaft portion 50a with respect to the holes 63a, 1a, 71a formed in the detachable member.

  Therefore, in this embodiment, as described above, in order to stably maintain the fitting state with the holes 63a, 1a, 71a formed in the photosensitive drum 1 which is the detachable member and the front side plate 70, the drum shaft Fitting members such as a fitting member 66, a positioning member 64, and a guide member 67 are provided on the shaft portion 50 a of 50.

FIG. 11 is a perspective view showing a state in which the guide member 67 on the shaft portion 50a of the drum shaft 50 is fitted in the inner surface of the bearing member 71 provided on the front side plate 70. FIG.
When the front side plate 70 is attached to the copying machine main body, the cylindrical portion 67 a of the guide member 67 is fitted into the inner surface of the bearing member 71 provided on the front side plate 70. Thereby, the front side end (tip) of the drum shaft 50 is rotatably supported with respect to the front side plate 70 and is stably positioned.

FIG. 12 is an enlarged perspective view of the front end portion of the drum shaft 50.
In the present embodiment, the positioning member 64 provided on the shaft portion 50 a of the drum shaft 50 is fitted into the through hole 1 a provided on the front side end portion of the photosensitive drum 1. Since positioning of the photosensitive drum 1 with respect to the drum shaft 50 requires a particularly high accuracy, as described above, a bearing member formed of a ball bearing is used as the positioning member 64 in the present embodiment. At this time, the guide member 67 disposed in the vicinity of the positioning member 64 may partially enter the through hole 1 a of the photosensitive drum 1. In that case, when the guide member 67 hits the inner surface of the through hole 1 a of the photosensitive drum 1, the high positioning accuracy of the photosensitive drum 1 with respect to the drum shaft 50 realized by the positioning member 64 may be deteriorated.

  Therefore, in this embodiment, the outer peripheral surface of the guide member 67 (first fitting member) does not protrude outward in the radial direction of the drum shaft 50 from the outer peripheral surface of the positioning member 64 (second fitting member). The outer diameter of the guide member 67 (first fitting member) is shorter than the outer diameter of the positioning member 64. Thereby, even if the guide member 67 is mounted in a state of partially entering the through hole 1a of the photosensitive drum 1, the guide member 67 does not hit the inner surface of the through hole 1a of the photosensitive drum 1, and positioning is performed. High positioning accuracy of the photosensitive drum 1 with respect to the drum shaft 50 realized by the member 64 can be maintained.

  Moreover, it is also possible to comprise the guide member 67 and the positioning member 64 adjacent to the guide member 67 as a single member. However, since the required functions are different between the guide member 67 and the positioning member 64, they are configured as separate members in this embodiment.

Specifically, when the process cartridge is inserted into the copying machine main body 100, the guide member 67 has a front end side (front side) of the drum shaft 50 on the rear side through hole of the process cartridge and the circular through hole of the photosensitive drum 1. 63a is required to have low slidability so that it can pass smoothly even if it hits the through hole 1a of the photosensitive drum 1. Further, the guide member 67 is also required to have flexibility for fitting into the inner surface of the bearing member 71 of the front side plate 70. In order to realize these functions, it is preferable to form the guide member 67 from a material excellent in slidability and flexibility, for example, a material such as polyacetal.
On the other hand, since the positioning member 64 is required to be fitted into the through hole 1a of the photosensitive drum 1 and to position the photosensitive drum 1 with respect to the drum shaft 50 with high accuracy, high part accuracy is required. . When such a positioning member 64 is formed of a material such as polyacetal having excellent slidability and flexibility as in the case of the guide member 67, it is difficult to obtain the required high part accuracy.

  In addition, the guide member 67 of the present embodiment includes a truncated cone-shaped tapered portion 67b that is tapered from the cylindrical portion 67a toward the tip end side (front side) of the drum shaft 50. Thus, when the process cartridge is inserted into the copying machine main body 100, the drum shaft 50 is inserted into the rear side through hole of the process cartridge, the circular through hole 63a of the photosensitive drum 1, and the through hole 1a of the photosensitive drum 1. It becomes easy to do. In particular, in the present embodiment, as shown in FIG. 12, the end surface 67c of the front side portion of the taper portion 67b is rounded to have an R shape, so that when the process cartridge is inserted into the copying machine main body 100, the process is performed. The drum shaft 50 is further easily inserted into the rear side through hole of the cartridge, the circular through hole 63a of the photosensitive drum 1, and the through hole 1a of the photosensitive drum 1.

  The guide member 67 of this embodiment is inserted and attached to the shaft portion 50 a of the drum shaft 50 from the tip end side, and the tip end side of the guide member 67 is secured by the E-ring member 52.

FIG. 13 is an enlarged perspective view of the rear side portion of the drum shaft 50.
FIG. 14 is a cross-sectional view showing a rear side portion in a state where the photosensitive drum 1 is mounted on the drum shaft 50.
The fitting member 66 of the present embodiment is fitted into a circular through hole 63 a formed in the driven gear 63 of the photosensitive drum 1, so that the rear side end portion of the photosensitive drum 1 is located with respect to the drum shaft 50. Position it. The fitting member 66 passes through the rear through hole of the process cartridge and the circular through hole 63a of the photosensitive drum 1 when the process cartridge is inserted into the copying machine main body 100. In order to achieve this, a taper portion 66a that is tapered toward the tip end side (front side) of the drum shaft 50 is provided.

  In the present embodiment, in order to hold the drive gear 51 on the irregularly shaped shaft portion 50a, a part of the fitting member 66 is provided between the shaft portion 50a and the drive gear 51 as shown in FIG. It is configured to intervene. The inner wall surface of the drive gear 51 is circular in cross section, and it is difficult to hold it directly on the drive gear 51 having a non-circular cross section. As in the present embodiment, the rear side portion of the fitting member 66 is extended to between the shaft portion 50 a and the drive gear 51, and the extension portion 66 b is driven to be interposed between the shaft portion 50 a and the drive gear 51. If the gear 51 is attached, the drive gear 51 can be easily held on the shaft portion 50a. The drive gear 51 and the fitting member 66 are formed with through holes, and the drive gear 51 is held on the shaft portion 50a by fitting parallel pins into these through holes.

Fig.15 (a) is a top view when the fitting member 66 is seen from an axial direction, FIG.15 (b) is an enlarged view of the part enclosed with the broken line in Fig.15 (a).
The fitting member 66 is formed with an insertion hole 66d corresponding to the cross-sectional shape of the shaft portion 50a having a deformed shape along the axial direction, and is inserted and attached from the tip end side of the shaft portion 50a. At this time, it is important in terms of positioning accuracy of the photosensitive drum 1 with respect to the drum shaft 50 to ensure the coaxiality between the outer peripheral center of the fitting member 66 and the shaft center of the shaft portion 50a. However, it is necessary to allow the fitting member 66 to be attached by inserting the insertion hole 66d of the fitting member 66 from the distal end side of the shaft portion 50a.

  Therefore, in the present embodiment, a pair of protrusions 66c that sandwich the flat plate portions 50a-1, 50a-2, 50a-3 of the shaft portion 50a are formed on the inner surface of the insertion hole 66d of the fitting member 66. Since the fitting member 66 having the pair of protrusions 66c has a rotationally symmetric shape with respect to the axial center, the outer peripheral center of the fitting member 66 and the shaft portion inserted into the insertion hole 66d of the fitting member 66. It is easy to ensure the coaxiality with the axis center of 50a. Further, in the present embodiment, the distance between the pair of protrusions 66c is slightly narrower than the thickness of the flat plate portions 50a-1, 50a-2, 50a-3 of the shaft portion 50a sandwiched between the pair of projections 66c. be able to.

  As with the fitting member 66, the guide member 67 has a pair of protrusions formed on the inner surface of the insertion hole, and the same effect can be obtained.

  In this embodiment, an example in which the rotating body is the photosensitive drum 1 has been described. However, the primary transfer rollers 6Y, 6M, 6C, and 6Bk, the secondary transfer roller 7, the developing roller 91, the cleaning roller, and the like. The rotating body can be similarly applied as long as the rotating body can be attached to and detached from the copying machine main body in the direction of the rotation axis and is mounted with the driving shaft of the copying machine main body penetrating both ends. .

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect A)
The drive shaft such as the shaft portion 50a of the drum shaft 50 of the image forming apparatus main body passes through both ends in the rotation axis direction of the rotating body such as the photosensitive drum 1 that can be attached to and detached from the image forming apparatus main body such as the copying machine main body 100. In the driving force transmission device that transmits the driving force to the rotating body mounted in a state of being mounted through the driving shaft, the driving shaft is long in the axial direction and has at least two flat plates that are not parallel to each other. It is characterized by being composed of sections 50a-1, 50a-2, 50a-3, 50a-4, 50a-5, and 50a-6.
As in this aspect, if the drive shaft is composed of at least two flat plate portions that are long in the axial direction and the flat plate surfaces are not parallel, a relatively inexpensive rolled material is used and high-precision machining is easy. The drive shaft can be produced by a simple rolling process. Moreover, the flat plate portion has low rigidity against bending or bending due to an external force from the normal direction to the flat plate surface, but is rigid against bending or bending due to an external force from a direction parallel to the flat plate surface. Is expensive. Since the drive shaft in this aspect is in a state in which the flat plate surfaces of at least two flat plate portions are non-parallel, at least part of the external force from the normal direction to the flat plate surface of one flat plate portion, the other flat plate portion has its It can be received as an external force from a direction parallel to the flat plate surface. Therefore, it is possible to ensure sufficient rigidity against bending or bending that can occur in the drive shaft.

(Aspect B)
In the aspect A, the drive shaft has a shape in which three or more flat plate portions 50a-1, 50a-2, 50a-3, and 50a-4 are radially arranged from the axial center.
According to this, since the shape of the cross section orthogonal to the axial direction of the drive shaft is rotationally symmetric with respect to the shaft center, it is easy to ensure the shaft position accuracy of the drive shaft, and sufficient for bending or bending of the drive shaft Easy to ensure high rigidity.

(Aspect C)
In the aspect A, the drive shaft has a hollow portion surrounded by three or more flat plate portions 50a-1, 50a-2, 50a-3, 50a-4, 50a-5, and 50a-6. It is characterized by that.
According to this, since the shape of the cross section orthogonal to the axial direction of the drive shaft is rotationally symmetric with respect to the axis center, it is easy to ensure the axial position accuracy of the drive shaft.

(Aspect D)
In any one of the aspects A to C, the drive shaft includes inner surfaces of through holes 63a and 1a formed at least one end portion in the rotation axis direction of the rotating body, or a tip of the drive shaft. A fitting member 66, a positioning member 64, and a guide member that are fitted to the inner surface of the support hole (the inner surface 71a of the bearing member 71) formed in the support portion such as the front side plate 70 of the image forming apparatus main body that rotatably supports the image forming apparatus. A fitting member such as 67 is attached.
When mounting the rotating body and the support part attached to and detached from the drive shaft on the drive shaft having the shape including the flat plate part described above, the drive shaft is fitted into the through hole of the rotary body and the support hole of the support part. It is simple and preferable. However, since the drive shaft has an irregular shape having the flat plate portion as described above, it is difficult to stably fit such a drive shaft into the through hole of the rotating body or the support hole of the support portion. According to this aspect, since the drive shaft is fitted into the through hole of the rotating body or the support hole of the support portion via the fitting member attached to the drive shaft, it is stable without being affected by the shape of the drive shaft. A fitting state can be maintained.

(Aspect E)
In the aspect D, the fitting member has tapered portions 67b and 66a that are tapered toward the tip end side of the drive shaft.
According to this, when the rotating body is mounted on the main body of the image forming apparatus, the fitting member on the drive shaft can pass smoothly without being caught in the through hole of the rotating body.

(Aspect F)
In the aspect D or E, the drive shaft includes an inner surface of the support hole formed in the support portion such as the front side plate 70 of the image forming apparatus main body that rotatably supports the tip end portion of the drive shaft (the bearing member 71). A first fitting member such as a guide member 67 fitted to the inner surface 71a), a positioning member 64 fitted to the inner surface of the through hole 1a formed at the end of the rotating shaft on the tip end side. And the outer peripheral surface of the first fitting member does not protrude outward in the radial direction of the drive shaft from the outer peripheral surface of the second fitting member.
According to this, it can suppress that the positioning accuracy of the rotary body with respect to the drive shaft implement | achieved by the 2nd fitting member deteriorates by the 1st fitting member.

(Aspect G)
In any one of the aspects D to F, the fitting member is made of polyacetal.
According to this, the fitting member which can maintain the stable fitting state is obtained. Further, since it becomes easy to improve the slidability, when the rotating body is mounted on the image forming apparatus main body, the fitting member on the drive shaft slides in the through hole of the rotating body and can pass smoothly without being caught. A fitting member is also easy to obtain.

(Aspect H)
In any one of the aspects D to G, the fitting member is formed with an insertion hole 66d through which the flat plate portion is inserted along the axial direction of the drive shaft, and is formed on the inner surface of the insertion hole. Is characterized in that a pair of protrusions 66c for sandwiching the flat plate portion are formed.
According to this, it is easy to ensure the coaxiality of the external shape center of a fitting member, and the axial center of the drive shaft inserted in the insertion hole of the fitting member. Further, the fitting member can be assembled to the drive shaft by light press fitting, and the assembling work is simple.

(Aspect I)
In an image forming apparatus including a rotating body such as the photosensitive drum 1 and a driving force transmitting unit that transmits a driving force from a driving source such as a motor 75 to the rotating body, the driving force transmitting unit may include the mode A. The driving force transmission device according to any one of the aspects ~ H is used.
According to this, it is possible to perform image formation using a rotating body that realizes high rotational center position accuracy at low cost.

(Aspect J)
In the aspect I, the rotating body includes a latent image carrier such as the photosensitive drum 1 and a developer such as a developing roller 91 that rotates with a developer that develops the latent image on the latent image carrier on the surface. It is at least one of a developer conveying member such as a stirring screw 92 and 93 that rotates in a developer accommodating portion that accommodates the developer carried on the developer bearing member and conveys the developer. Features.
According to this, it is possible to form an image using the latent image carrier, the developer carrier, and the developer conveying member that are realized at low cost and high rotational center position accuracy.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 1a Through-hole 2 Charger 4 Cleaning device 5 Intermediate transfer belt 6 Primary transfer roller 7 Secondary transfer roller 9 Developing device 17 Optical writing device 18 Fixing device 50 Drum shaft 50a Shaft portions 50a-1 to 50a- 6 flat plate portion 51 driving gear 61 front side plate member 62 rear side plate member 63 driven gear 63a circular through hole 64 positioning member 65 bearing portion 66 fitting member 66a taper portion 66b extending portion 66c protrusion 66d insertion hole 67 guide member 67a cylinder Portion 67b taper portion 68 cartridge frame 70 front side plate 71 bearing member 72 rear side plate 72a support hole 73 bearing portion 74 speed reducer 75 motor 91 developing roller 92, 93 stirring screw 100 copying machine main body

JP 2013-83863 A

Claims (9)

Driving force is transmitted via the drive shaft to the rotating body that is mounted with the drive shaft of the image forming apparatus main body penetrating through both ends in the rotational axis direction of the rotating body that can be attached to and detached from the image forming apparatus main body. In the driving force transmission device
The drive shaft is composed of at least two flat plate portions that are long in the axial direction and have non-parallel flat plate surfaces ;
A fitting member that is fitted to the inner surface of a support hole formed in the support portion of the image forming apparatus main body that rotatably supports the tip end portion of the drive shaft is attached to the drive shaft.
As the fitting member, a first fitting member that fits into the inner surface of the support hole, and a second fitting member that fits into the inner surface of a through hole formed at the end of the rotating shaft on the distal end side. A fitting member,
The outer peripheral surface of the first fitting member, the driving force transmitting device which is characterized that you than the outer peripheral surface does not project radially outwardly of the drive shaft of the second fitting member.   The driving force transmission device according to claim 1,
  The fitting member has an insertion hole through which the flat plate portion is inserted along the axial direction of the drive shaft.
  A driving force transmission device, wherein a pair of protrusions that sandwich the flat plate portion are formed on the inner surface of the insertion hole.   Driving force is transmitted via the drive shaft to the rotating body that is mounted with the drive shaft of the image forming apparatus main body penetrating through both ends in the rotational axis direction of the rotating body that can be attached to and detached from the image forming apparatus main body. In the driving force transmission device
  The drive shaft is composed of at least two flat plate portions that are long in the axial direction and have non-parallel flat plate surfaces;
  A fitting member that is fitted to the inner surface of a support hole formed in the support portion of the image forming apparatus main body that rotatably supports the tip end portion of the drive shaft is attached to the drive shaft.
  The fitting member has an insertion hole through which the flat plate portion is inserted along the axial direction of the drive shaft.
  A driving force transmission device, wherein a pair of protrusions that sandwich the flat plate portion are formed on the inner surface of the insertion hole. The driving force transmission device according to any one of claims 1 to 3 ,
The drive shaft has a shape in which three or more flat plate portions are arranged radially from the center of the shaft. The driving force transmission device according to any one of claims 1 to 3 ,
The driving force transmission device according to claim 1, wherein the driving shaft has a hollow portion surrounded by three or more flat plate portions. The driving force transmission device according to any one of claims 1 to 5 ,
The driving force transmitting device, wherein the fitting member has a tapered portion that is tapered toward a tip end side of the driving shaft. The driving force transmission device according to any one of claims 1 to 6,
The driving force transmission device, wherein the fitting member is made of polyacetal. In an image forming apparatus comprising: a rotating body; and a driving force transmitting unit that transmits a driving force from a driving source to the rotating body.
As the driving force transmitting means, the image forming apparatus characterized by using the driving force transmission apparatus according to any one of claims 1乃optimum 7. The image forming apparatus according to claim 8 .
The rotating body includes a latent image carrier, a developer carrier that rotates a developer for developing a latent image on the latent image carrier, and a developer carried on the developer carrier. An image forming apparatus, wherein the image forming apparatus is at least one of a developer conveying member that rotates in a developer accommodating portion to convey the developer.

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