JP2016024442A - Image holding body, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image holding body that can suppress, when a plurality of C-shape contact members are supported inside a cylindrical body, the positions in the circumferential direction of the plurality of contact members from being shifted from each other with respect to the cylindrical body, and an image forming apparatus.SOLUTION: A projection 106 extending in an apparatus depth direction is formed on the inner surface 108A of a cylindrical body 108. Contact members 116A and 116B are supported inside the cylindrical body 108 so that the projection 106 of the cylindrical body 108 is arranged in separation spaces 140A and 140B of the contact members 116A and 116B. This configuration suppresses the positions in the circumferential direction of the contact members 116A and 116B from being shifted from each other with respect to the cylindrical body 108.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image carrier and an image forming apparatus.

  In Patent Document 1, in order to reduce charging noise, image formation is provided with a sliding contact member (contact member) that comes into contact with an inner wall surface of a photosensitive drum (cylinder) and presses the inner wall surface with a predetermined frictional force. An apparatus is described. And this sliding contact member is made into C shape seeing from the axial direction of a cylinder.

JP 2000-315036 A

  Conventionally, an outer peripheral surface of a C-shaped contact member presses an inner surface of a cylinder, so that the contact member is supported inside the cylinder. However, since the pressing force that presses the inner surface of the cylindrical body by the outer peripheral surface of the contact member varies in the circumferential direction of the contact member, the cross section of the cylindrical body may be deformed into an oval shape. Furthermore, when supporting a plurality of the contact members inside the cylinder, if the circumferential position is shifted between one contact member and another contact member, the cross-sectional shape of the cylinder changes in the axial direction of the cylinder. Resulting in.

  The subject of this invention suppresses that the position of the circumferential direction of a some contact member will mutually shift with respect to a cylinder, when two or more C-shaped contact members are supported inside a cylinder. It is.

  The image holding body according to claim 1 rotates and is supported by being in contact with the inside of the cylindrical body, the cylindrical body on which an image is formed on the surface, and when viewed from the axial direction of the cylindrical body, A plurality of contact members along the inner side surface of the cylindrical body and arc-shaped with both ends opposed to each other, and a space formed between the opposed both ends viewed from the axial direction of the cylindrical body And a restricting structure for restricting the circumferential positions of the plurality of contact members with respect to the cylindrical body so as to be positioned in the same direction with respect to the axial center of the cylindrical body.

  The image holding body according to claim 2 is the image holding body according to claim 1, wherein the restriction structure protrudes from an inner surface of the cylindrical body and is disposed in the separation space, and A protrusion extending in the axial direction is provided from one end to the other end in the axial direction.

  The image holding body according to claim 3 is the image holding body according to claim 1, wherein the restriction structure includes a concave or convex uneven portion formed on an inner surface of the cylindrical body, and an outer periphery of the contact member. And a fitting portion that is formed on the surface and fits with the concavo-convex portion.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising: the image holding body according to any one of the first to third aspects; and a surface of the image holding body by applying a superimposed voltage obtained by superimposing an AC voltage on a DC voltage. A charging member that charges the image, an image forming member that forms an image on the surface of the charged image carrier, and a transfer member that transfers an image formed on the surface of the image carrier to a transported recording medium. It is characterized by providing.

  The image forming apparatus according to a fifth aspect is the image forming apparatus according to the fourth aspect, wherein the contact member is disposed on at least one of the cylindrical bodies and the other in the axial direction of the cylindrical body. A correction unit that corrects density unevenness of an image caused by the deformation of the cylindrical body caused by the contact member arranged on the surface and the deformation of the cylindrical body caused by the contact member arranged on the other side of the cylindrical body; It is characterized by providing.

  According to the image holding body of the first aspect, the C-shaped contact member is a cylinder as compared with the case where a restriction structure for restricting the circumferential positions of the plurality of contact members is not provided for the cylinder. When a plurality of members are supported inside the body, it is possible to prevent the circumferential positions of the plurality of contact members from being shifted from each other with respect to the cylinder.

  According to the image holding body of the second aspect, the protrusion can be formed in the same process when the cylinder is formed by drawing or extruding.

  According to the image holding body of the third aspect, the axial position of the contact member with respect to the cylindrical body can be regulated.

  According to the image forming apparatus of the fourth aspect, the image is transferred to the recording medium in the width direction of the recording medium as compared with the case where the image holding body according to any one of the first to third aspects is not provided. It is possible to suppress density unevenness in the image.

  According to the image forming apparatus of the fifth aspect, the image is transferred to the recording medium in the width direction of the recording medium and the conveyance direction of the recording medium, as compared with the case where the correction unit for correcting the density unevenness of the image is not provided. It is possible to suppress density unevenness in the image.

It is the perspective view which showed the cylinder provided in the image holding body which concerns on 1st Embodiment of this invention, and the contact member. It is the disassembled perspective view which showed the cylinder provided in the image holding body which concerns on 1st Embodiment of this invention, and a contact member. (A) (B) It is sectional drawing which showed the cylinder provided in the image holding body which concerns on 1st Embodiment of this invention, and the contact member. (A) (B) It is sectional drawing which showed the state with which the cylindrical body with which the image holding body which concerns on 1st Embodiment of this invention was equipped, and the contact member deform | transformed. It is the perspective view which showed the contact member with which the image holding body which concerns on 1st Embodiment of this invention was equipped. (A) (B) It is drawing which showed the image which output the halftone image to the sheet | seat member using the image forming apparatus which concerns on 1st Embodiment of this invention. 3 is a graph showing a relationship between an inner diameter of a cylindrical body provided in the image holding body according to the first embodiment of the present invention, an outer diameter of a contact member, and an ambient temperature. 1 is a diagram illustrating an image carrier and a charging roll provided in an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a configuration diagram illustrating an image forming unit provided in the image forming apparatus according to the first embodiment of the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention. (A) (B) It is sectional drawing which showed the cylinder provided in the image holding body which concerns on the comparison form with respect to the image holding body of 1st Embodiment of this invention, and the contact member. (A) (B) It is sectional drawing which showed the state with which the cylindrical body with which the image holding body which concerns on the comparison form with respect to the image holding body of 1st Embodiment of this invention was equipped, and the contact member deform | transformed. It is the perspective view which showed the image holding body which concerns on the comparison form with respect to the image holding body of 1st Embodiment of this invention. It is drawing which showed the deformation | transformation of the cylinder with which the image holding body which concerns on the comparison form with respect to the image holding body of 1st Embodiment of this invention was equipped. 4 is a diagram illustrating an image obtained by outputting a halftone image to a sheet member using the image forming apparatus according to a comparative example with respect to the image carrier of the first embodiment of the present invention. (A) (B) It is sectional drawing which showed the cylinder provided in the image holding body which concerns on 2nd Embodiment of this invention, and the contact member. It is the disassembled perspective view which showed the cylinder provided in the image holding body which concerns on 2nd Embodiment of this invention, and the contact member.

<First Embodiment>
An example of the image carrier and the image forming apparatus according to the first embodiment of the present invention will be described with reference to FIGS. In the drawing, an arrow H indicates the vertical direction of the apparatus (vertical direction), an arrow W indicates the apparatus width direction (horizontal direction), and an arrow D indicates the depth direction of the apparatus (horizontal direction).

(overall structure)
As illustrated in FIG. 10, the image forming apparatus 10 according to the first embodiment includes a storage unit 14 that stores a sheet member P serving as a recording medium, and a conveyance path for the sheet member P stored in the storage unit 14. 28, an image forming unit 20 that forms an image on the sheet member P conveyed by the conveying unit 16 from the storage unit 14, and an original reading unit 22 that reads the read original G. Yes. In the image forming apparatus 10, the storage unit 14, the transport unit 16, the image forming unit 20, and the document reading unit 22 are arranged in this order from the bottom to the top in the vertical direction (arrow H direction). Yes. Furthermore, the image forming apparatus 10 includes a control unit 32 (an example of a correction unit) that controls each unit, and a manual sheet feeding unit 26 that manually supplies the sheet member P.

(Image forming part)
As shown in FIG. 9, the image forming unit 20 is charged based on a cylindrical image carrier 56, a charging roll 58 (an example of a charging member) that charges the surface of the image carrier 56, and image data. An exposure device 60 (an example of an image forming member: see FIG. 10) that irradiates the surface of the image carrier 56 with exposure light to form an electrostatic latent image, and develops and visualizes the electrostatic latent image as a toner image. And a developing device 62 (an example of an image forming member).

  Further, the image forming unit 20 includes a transfer roll 64 (an example of a transfer member) that transfers the toner image formed on the surface of the image holding member 56 to the sheet member P conveyed along the conveyance path 28, and the sheet member P. And a fixing device 66 (see FIG. 10) for fixing the toner image on the sheet member P by heating and pressurizing the toner image. The image forming unit 20 is disposed on the downstream side with respect to the transfer position T formed by the image holding member 56 and the transfer roll 64 in the conveyance direction of the sheet member P, and is transferred to the sheet member P. The density sensor 30 for detecting the density of the light is provided.

  As shown in FIG. 10, a toner cartridge 72 connected to the developing device 62 via a supply pipe (not shown) is disposed obliquely above the exposure device 60. The toner cartridge 72 stores toner to be supplied to the developing device 62 via a supply pipe.

  In this configuration, the sheet member P sent out from the storage unit 14 to the conveyance path 28 by the conveyance unit 16 is conveyed to a transfer position T configured by the image holding body 56 and the transfer roll 64, and the image holding body 56 and the transfer member It is nipped and conveyed between the rolls 64. As a result, the toner image formed on the image carrier 56 is transferred to the sheet member P. Further, the fixing device 66 fixes the toner image transferred onto the sheet member P to the sheet member P, and the sheet member P on which the toner image is fixed is discharged from the apparatus main body to the outside.

(Main part configuration)
Next, the image carrier 56 and the charging roll 58 will be described.

[Charging roll]
As shown in FIG. 8, the charging roll 58 has a shaft portion 58A that extends in the depth direction of the apparatus and is formed of a metal material (for example, stainless steel), and a cylindrical shape in which the shaft portion 58A passes through. And a formed roll part 58B.

  Further, both end portions of the shaft portion 58 </ b> A are exposed to the outside from the roll portion 58 </ b> B and are rotatably supported by the pair of bearing members 102. Further, a biasing member 104 that biases each bearing member 102 toward the image holding body 56 is disposed on the opposite side of the image holding body 56 with the shaft portion 58A interposed therebetween.

  With this configuration, when the roll portion 58B of the charging roll 58 is pressed against the image holding body 56 and the image holding body 56 rotates, the charging roll 58 is driven to rotate. Then, a superimposed voltage obtained by superimposing an AC voltage (1 kHz to 2 kHz) on a DC voltage from a power source (not shown) is applied to the shaft portion 58 </ b> A, whereby a current flows from the charging roll 58 to the image carrier 56, and the image carrier 56. The surface of the battery is charged.

(Image carrier)
As shown in FIG. 8, the image holding body 56 includes a cylindrical tube 108 extending in the device depth direction, and one end side (upper side in the drawing) in the device depth direction (the same direction as the axial direction of the tube 108). And a transmission member 110 fixed to the cylinder 108 so as to close the opening of the cylinder 108. Further, the image carrier 56 includes a support member 112 fixed to the cylinder 108 so as to close the opening of the cylinder 108 on the other end side in the apparatus depth direction (the lower side in the drawing). Further, the image holding body 56 includes a contact member 116A and a contact member 116B that are disposed inside the cylinder 108 and suppress the vibration of the cylinder 108.

The cylindrical body 108 is obtained by forming a photosensitive layer on the outer peripheral surface of a base material formed into a cylindrical shape by a drawing process using aluminum which is a metal material. As an example, the thickness of the cylinder 108 is 0.8 [mm], the outer diameter of the cylinder 108 is 23 [mm], and the length of the cylinder 108 in the apparatus depth direction is 250 [mm]. It is said that. The linear expansion coefficient of aluminum is 23 × 10 ⁻⁶ / K.

  The transmission member 110 is formed of a resin material in a disk shape, and is fixed to a portion on one end side of the cylinder body 108 by being partially fitted into the cylinder body 108. Further, the transmission member 110 is formed with a cylindrical through hole 110 </ b> A on the axial center F of the cylindrical body 108. In addition, a plurality of recesses 110B are formed on the outer surface of the transmission member 110 facing the outside in the apparatus depth direction so as to sandwich the through hole 110A.

  The motor shaft 122B of the motor 122 that generates the rotational force transmitted to the transmission member 110 (image holding body 56) passes through the through hole 110A of the transmission member 110. In addition, the front end portion 128A of the bracket 128 attached to the motor shaft portion 122B is bent and inserted into the concave portion 110B of the transmission member 110.

  On the other hand, the support member 112 is formed of a resin material into a disk shape, and is fixed to the other end portion of the cylinder body 108 by being partially fitted into the cylinder body 108. Further, a cylindrical through hole 112 </ b> A is formed in the support member 112 on the axial center F of the cylindrical body 108.

  The shaft portion 130A of the shaft member 130 that rotatably supports the support member 112 (image holding body 56) passes through the through hole 112A, and the support member 112 functions as a so-called slide bearing with respect to the shaft portion 130A. .

  Further, on the inner side surface 108A of the cylindrical body 108, the protrusion 106 disposed in the later-described spaced spaces 140A and 140B of the contact members 116A and 116B in a state where the contact members 116A and 116B are supported inside the cylindrical body 108. (An example of a regulation structure) is formed (see FIG. 3B). As shown in FIG. 1, the protrusion 106 is formed to extend in the apparatus depth direction from one end to the other end of the cylinder 108 in the apparatus depth direction. Further, the protrusion 106 is formed in the same process when the cylindrical body 108 is formed in the drawing process.

  In this configuration, the rotational force generated by the motor 122 is transmitted to the transmission member 110 (image holding body 56) via the bracket 128, and the image holding body 56 rotates around the axis center F.

[Contact member]
Next, the contact members 116A and 116B supported inside the cylindrical body 108 will be described.

  As shown in FIG. 8, the contact member 116 </ b> A is disposed on the transmission member 110 side, and the contact member 116 </ b> B is disposed on the support member 112 side. Further, the contact member 116A and the contact member 116B have the same configuration. For this reason, when it is not necessary to distinguish, "A" and "B" attached to a code | symbol are abbreviate | omitted.

  As shown in FIG. 3B, the contact member 116 is configured such that the arc-shaped outer peripheral surface 118 of the contact member 116 contacts the inner side surface 108 </ b> A of the cylindrical body 108 and presses the inner side surface 108 </ b> A. Is supported inside.

Specifically, the contact member 116 is formed using an ABS resin (acrylonitrile butadiene styrene) which is a resin material. When the contact member 116 is supported inside the cylindrical body 108, the contact member 116 is C-shaped with both ends facing each other along the inner side surface 108 </ b> A of the cylindrical body 108 when viewed from the depth direction of the apparatus. Arc-shaped). In addition, a space 140 that is partially spaced apart in the circumferential direction is formed between the opposite ends. And the contact member 116 is extended in the apparatus depth direction, as FIG. 5 shows. As an example, the thickness of the general portion of contact member 116 (the portion excluding groove 142 described later) is 4 [mm], and the length of contact member 116 in the apparatus depth direction is 100 [mm]. . The linear expansion coefficient of the ABS resin is 74 × 10 ⁻⁶ / K, which is a larger value than the linear expansion coefficient of aluminum.

  Further, as shown in FIG. 3B, in a state where the contact member 116 is supported inside the cylinder body 108, the contact member 116 on the opposite side of the separation space 140 across the axial center F of the cylinder body 108. A groove 142 extending in the apparatus depth direction is formed on the outer peripheral surface 118.

  Further, in a state where the contact member 116 is not supported inside the cylindrical body 108 (free state), as shown in FIG. It is formed symmetrically with respect to an axis C passing through the groove 142. Specifically, the contact member 116 is formed by connecting a circular hole-shaped arc portion 144 on the right side in the drawing and a circular hole-shaped arc portion 146 on the left side in the drawing by a groove 142.

  When viewed from the depth direction of the apparatus, the separation distance K1 (see FIG. 3A) in the separation space 140 of the contact member 116 in the free state is the separation in the state where the contact member 116 is supported inside the cylindrical body 108. It is longer than the distance K2 (see FIG. 3B).

  Further, the radius of the outer peripheral surface 118 of the arc portions 144 and 146 of the contact member 116 in the free state when viewed from the apparatus depth direction is R1, and the radius of the inner side surface 108A of the cylinder 108 is R2 (when viewed from the apparatus depth direction). (See FIG. 3B). Then, the radius R1 is equal to or larger than the radius R2 (details will be described later).

FIG. 7 is a graph showing the relationship between the values of the radii R1 and R2 (vertical axis) and the ambient temperature (horizontal axis). In the graph, the radius R1 is indicated by a broken line and the radius R2 is indicated by a solid line. Has been. As described above, the linear expansion coefficient of the ABS resin used in the contact member 116 is a 74 × ^{10 -6} / K, the linear expansion coefficient of aluminum used in the cylindrical body 108 is 23 × 10 ^{- 6} / K. For this reason, as the temperature rises, the radius R1 becomes larger than the radius R2.

  As described above, the arcuate outer peripheral surface 118 of the contact member 116 contacts the inner side surface 108 </ b> A of the cylindrical body 108 and presses the inner side surface 108 </ b> A, whereby the contact member 116 is supported by the cylindrical body 108. That is, the contact member 116 is disposed inside the cylindrical body 108 in a bent state, and the outer peripheral surface 118 of the contact member 116 contacts the inner side surface 108A of the cylindrical body 108 to press the inner side surface 108A. Yes. For this reason, the radius R1 needs to be equal to or larger than the radius R2, and P1 [° C.] in the graph shown in FIG. 7 is the lower limit value of the assumed use temperature of the image carrier 56.

  In this configuration, when the contact members 116A and 116B are arranged inside the cylinder 108, first, the contact member 116A is gripped, and the groove 142A is deformed so that the separation distance K1 is shortened (FIGS. 1 and 2). reference). Then, the contact member 116A is bent, and the contact member 116A is inserted into the cylindrical body 108 in this bent state. Here, the contact member 116A is inserted into the cylindrical body 108 such that the protrusion 106 of the cylindrical body 108 is disposed in the separation space 140A of the contact member 116A.

  Further, the gripping force for gripping the contact member 116A is released, and the contact member 116A is pushed into the cylindrical body 108. Thereby, the outer peripheral surface 118A of the contact member 116A is in contact with the inner side surface 108A of the cylindrical body 108, and the contact member 116A is supported by the cylindrical body 108 and disposed inside the cylindrical body 108.

  Next, the contact member 116B is gripped, and the groove 142B is deformed so that the separation distance K1 is shortened. Then, the contact member 116B is bent, and the contact member 116B is inserted into the cylindrical body 108 in this bent state. Here, the contact member 116B is inserted into the cylindrical body 108 so that the protrusion 106 of the cylindrical body 108 is disposed in the separation space 140B of the contact member 116B.

  Further, the gripping force for gripping the contact member 116B is released, and the contact member 116B is pushed into the cylindrical body 108. As a result, the outer peripheral surface 118B of the contact member 116B comes into contact with the inner side surface 108A of the cylindrical body 108, and the contact member 116B is supported by the cylindrical body 108 and arranged inside the cylindrical body 108.

  As described above, the contact members 116A and 116B are supported inside the cylinder 108 so that the protruding portion 106 of the cylinder 108 is disposed in the separation spaces 140A and 140B of the contact members 116A and 116B. For this reason, the circumferential position of the contact members 116 </ b> A and 116 </ b> B is restricted with respect to the cylindrical body 108. When viewed from the depth direction of the apparatus, the separation space 140A of the contact member 116A and the separation space 140B of the contact member 116B are positioned in the same direction with respect to the axis center F. In the first embodiment, as an example, the spacing spaces 140A and 140B of the contact members 116A and 116B with respect to the axial center F are located above the apparatus in the vertical direction when viewed from the apparatus depth direction (FIG. 3). (See (B)).

  In this configuration, when the surface of the image carrier 56 is charged, a superimposed voltage obtained by superimposing an AC voltage (1 kHz to 2 kHz) on a DC voltage from a power source is applied to the shaft portion 58A of the charging roll 58 (see FIG. 8). ). An alternating electric field is generated between the charging roll 58 and the image carrier 56 by the alternating voltage that forms the superimposed voltage. Thereby, a periodic (2 kHz to 4 kHz) electrostatic attraction force is generated between the image carrier 56 and the charging roll 58. For this reason, the cross section of the cylindrical body 108 tends to periodically change (vibrate) between a circular shape and an oval shape. However, the outer peripheral surface 118 is in contact with the inner side surface 108 </ b> A of the cylindrical body 108 and the contact member 116 is supported inside the cylindrical body 108. For this reason, even if the cross section of the cylinder 108 changes periodically, the vibration of the cylinder 108 is suppressed.

  As described above, the vibration of the cylinder 108 can be suppressed by the contact member 116, but it is conceivable that the cylinder 108 is deformed by supporting the contact member 116 inside the cylinder 108.

  Accordingly, first, the image carrier 200 of the image forming apparatus 190 according to a comparative example with respect to the image forming apparatus 10 according to the first embodiment will be described. As shown in FIG. 13, no protrusion is formed on the inner peripheral surface 208 </ b> A of the cylinder 208 of the image carrier 200 according to the comparative embodiment. For this reason, the circumferential position of the contact member 116 supported inside the cylindrical body 208 is not restricted. For other specifications, the cylinder 208 according to the comparative embodiment is the same as the cylinder 108 according to the first embodiment.

  The circumferential position of the contact member 116 is not restricted. As shown in FIG. 11B, the separation space 140 </ b> A of the contact member 116 </ b> A is located on one side in the apparatus width direction with respect to the shaft center F as viewed from the apparatus depth direction. 11A, the separation space 140B of the contact member 116B is located above the axial center F in the vertical direction of the apparatus.

  The contact member 116 </ b> B is supported inside the cylindrical body 208 when the arc-shaped outer peripheral surface 118 </ b> B contacts the inner side surface 208 </ b> A of the cylindrical body 208 and presses the inner side surface 208 </ b> A. Here, the pressing force that presses the inner surface 208A of the cylindrical body 208 by the outer peripheral surface 118B of the contact member 116B varies in the circumferential direction of the contact member 116B. Specifically, since the contact member 116B is supported in the cylindrical body 208 in a bent state, the pressing force on both end sides (free end side) of the contact member 116B is different from that of the contact member 116B when viewed from the apparatus depth direction. Larger than the area.

  In particular, when the ambient temperature is higher, the radius R1 is larger than the radius R2 than when the ambient temperature is low. For this reason, the difference between the pressing force at both ends and the pressing force in other regions becomes large (see FIG. 7).

  In FIG. 14, the cross section of the cylindrical body 208 deformed by pressing the inner side surface 208A with the outer peripheral surface 118B of the contact member 116B is exaggeratedly shown. The vertical direction in FIG. 14 is the same as the vertical direction in FIG. 14 shows the deformation of the cylinder 208 when the contact member 116B is supported inside the cylinder 208 at the lower limit value of the assumed use temperature of the image carrier 200, and the solid line L2 indicates the inside of the apparatus. The deformation | transformation of the cylinder 208 when the inside atmospheric temperature becomes high is shown. A two-dot chain line L3 in FIG. 14 indicates the shape (circular shape) of the cylindrical body 208 in a state where the contact member 116B is not supported therein.

  As described above, the pressing force at both ends in the circumferential direction of the contact member 116 is larger than the pressing force in other regions. Further, when the ambient temperature is higher, the radius R1 is larger than the radius R2 as compared with the case where the ambient temperature is low. Therefore, the cylindrical body 208 (broken line L1 in the figure) when the contact member 116B is supported inside the cylindrical body 208 at the lower limit value of the assumed use temperature of the image holding body 56 is the cylindrical body 208 before deformation (in the figure). Compared with the two-dot chain line L3), it extends in the vertical direction in the figure. Further, in the cylinder 208 (solid line L2 in the figure) when the atmospheric temperature in the apparatus becomes high, the contact member 116B is supported inside the cylinder 208 at the lower limit value of the assumed use temperature of the image carrier 200. Compared with the case 208 (broken line L1 in the figure), it extends in the vertical direction in the figure.

  Thus, in the part where the contact member 116B is supported in the cylinder 208, as shown in FIG. 12A (cross section J1-J1 in FIG. 13), the cylinder 208 extends in the vertical direction of the apparatus. Deforms into a circle.

  On the other hand, the separation space 140A of the contact member 116A supported inside the cylinder 208 is located on one side in the apparatus width direction with respect to the axial center F. For this reason, in the part where the contact member 116A is supported in the cylinder 208, as shown in FIG. 12B (J2-J2 cross section in FIG. 13), the cylinder 208 is an ellipse extending in the apparatus width direction. It deforms into a shape.

  As described above, in the cylindrical body 208 of the comparative form, the positions of the contact members 116A and 116B in the circumferential direction are not restricted, so that the cross section of the cylindrical body 208 changes in the apparatus depth direction of the cylindrical body 208.

  Further, when a halftone image is formed on the sheet member P using the image forming apparatus 190 provided with the image carrier 200 whose cross section is deformed in this way, as shown in FIG. In the direction of arrow H in the figure, staggered density unevenness occurs in the output image. In the drawings used to explain the density unevenness, the shading is exaggerated so that the density unevenness can be easily understood.

  On the other hand, as described above, the protrusion 106 extending in the depth direction of the apparatus is formed on the inner side surface 108A of the cylindrical body 108 of the image holding body 56 of the first embodiment. As a result, as described above, the circumferential positions of the contact members 116A and 116B are restricted, and the spacing spaces 140A and 140B of the contact members 116A and 116B with respect to the axial center F when viewed from the depth direction of the apparatus are It is located above in the vertical direction (see FIG. 3B). For this reason, in the portion where the contact member 116B is supported in the cylinder 108, as shown in FIG. 4A (cross section M1-M1 in FIG. 1), the cylinder 108 is an ellipse extending in the vertical direction of the apparatus. It deforms into a shape. Further, in the portion of the cylindrical body 108 where the contact member 116A is supported, the cylindrical body 108 is an ellipse extending in the vertical direction of the apparatus as shown in FIG. Transforms into

  As described above, in the image holding body 56 of the first embodiment, the positions of the contact members 116A and 116B in the circumferential direction are restricted. The portion in which the contact member 116B is supported is deformed in the same manner. In other words, the change of the cross section of the cylinder 108 in the apparatus depth direction is suppressed.

  Then, a halftone image is formed on the sheet member P using the image forming apparatus 10 including the image holding body 56 in which the change in the cross section of the cylinder 108 in the apparatus depth direction is suppressed. Then, as shown in FIG. 6A, the occurrence of density unevenness in the sheet width direction (N direction in the figure) is suppressed, and density unevenness occurs in the process direction (arrow H direction in the figure).

  On the other hand, by operating the density sensor 30 of the image forming apparatus 10, the density of the toner image transferred to the sheet member P is detected by the density sensor 30 (see FIG. 9), and the control unit 32 (see FIG. 10) The density correction is performed by comparing the density of the detected toner image with a reference density based on the image data. For example, the density unevenness in the process direction is corrected (density correction) by periodically changing the charge amount of the image holding body 56 in the circumferential direction of the image holding body 56. Here, as described above, since the occurrence of density unevenness in the sheet width direction (N direction in the figure) is suppressed, the occurrence of density unevenness after the density correction is executed is shown in FIG. As shown in FIG. In the image forming apparatus 190 according to the comparative embodiment, staggered density unevenness occurs in the output image, and thus correction by adjusting the charge amount of the image carrier 56 becomes difficult.

  As described above, in the image carrier 56 according to the first embodiment, the protrusions 106 are formed on the inner side surface 108 </ b> A of the cylinder 108, so that the C-shaped contact members 116 </ b> A and 116 </ b> B are formed inside the cylinder 108. When the contact members 116 </ b> A and 116 </ b> B are supported by each other, the circumferential positions of the contact members 116 </ b> A and 116 </ b> B are prevented from being shifted from each other.

  In addition, since the displacement of the circumferential positions of the contact members 116A and 116B is suppressed, a change in the cross section of the cylindrical body 108 in the apparatus depth direction can be achieved as compared with the image holding body 200 according to the comparative form. It is suppressed.

  Further, by suppressing the change in the cross section of the cylinder 108 in the apparatus depth direction, the occurrence of density unevenness in the sheet width direction (N direction in the figure) of the image formed on the sheet member P is suppressed.

  Further, the density correction is performed by the control unit 32, thereby suppressing the occurrence of density unevenness in the process direction (H direction in the figure) of the image formed on the sheet member P.

  Further, the protrusion 106 is formed to extend in the apparatus depth direction from one end to the other end of the cylinder 108 in the apparatus depth direction. For this reason, when the cylindrical body 108 is formed in the drawing process, the protrusion 106 is formed in the same process.

Second Embodiment
Next, an example of an image carrier and an image forming apparatus according to the second embodiment of the present invention will be described with reference to FIGS. In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected, the description is abbreviate | omitted, and a different part from 1st Embodiment is mainly demonstrated.

  As shown in FIG. 17, the cylindrical body 174 of the image carrier 172 provided in the image forming apparatus 170 according to the second embodiment is not formed with a protrusion extending in the depth direction of the apparatus. Two hemispherical protrusions 176 (an example of an uneven portion) are formed on the inner surface 174A.

  The two protrusions 176 are spaced apart in the apparatus depth direction, and are formed at the same position in the circumferential direction of the cylindrical body 174.

  On the other hand, the outer peripheral surface 118 of the contact member 116 is formed with a recess 180 (an example of a fitting portion) into which the protrusion 176 enters while the contact member 116 is supported inside the cylindrical body 174.

  When the contact members 116A and 116B are supported inside the cylindrical body 174, as shown in FIGS. 16A and 16B, the respective protrusions 176 enter the recesses 180A and 180B, and the contact members 116A. , 116B are positioned above the axial center F in the vertical direction of the apparatus.

  As a result, the circumferential positions of the contact members 116A and 116B with respect to the cylinder 174 are restricted, and the positions of the contact members 116A and 116B with respect to the cylinder 174 in the apparatus depth direction are restricted. For this reason, compared with the case where the position of the contact members 116A and 116B in the apparatus depth direction with respect to the cylinder 174 is not regulated, the offset of the contact member in the apparatus depth direction is suppressed, and the cylinder 108 in the apparatus depth direction is suppressed. A change in the cross section is suppressed, and a decrease in the silencing effect of the contact member is suppressed.

  Further, in this embodiment, the position of the contact members 116A and 116B in the apparatus depth direction is restricted by the protrusion 176, and therefore, when the position of the contact member is to be restricted by the pressing force of the contact member into the cylindrical body 174. In comparison, the pressing force can be set small, and deformation of the cylindrical body 174 due to the pressing force can be suppressed.

  The operation of the other second embodiment is the same as that of the first embodiment.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. This will be apparent to those skilled in the art. For example, in the above embodiment, the cylinders 108 and 174 are formed of aluminum, which is a metal material, but may be formed of other metal materials.

  Moreover, in the said embodiment, although the contact member 116 was formed with the ABS resin which is a resin material, you may form with another resin material.

  Moreover, in the said 1st Embodiment, although the cylinder 108 was formed in the extraction process, you may form in an extrusion process. In this case, the protrusion 106 may be formed by this extrusion process.

  Further, in the second embodiment, the hemispherical protrusion 176 is formed on the inner surface 174A of the cylindrical body 174, and the concave portion 180 into which the protrusion 176 enters the outer peripheral surface 118 of the contact member 116. A recess may be formed on the inner peripheral surface 174 </ b> A, and a protrusion may be formed on the outer peripheral surface 118 of the contact member 116.

  Moreover, in the said embodiment, although the two contact members 116 are arrange | positioned inside the cylinders 108 and 174, three or more may be arrange | positioned.

  In the above-described embodiment, the outer peripheral surface of the contact member 116 and the inner side surface 108A of the cylindrical body 108 are in contact with each other in the entire circumferential direction. The portion may be in contact with the inner surface of the cylinder. In this case, the protruding portion needs to be formed with a thin region and another region.

10 Image Forming Device 32 Control Unit (Example of Correction Unit)
56 Image carrier 58 Charging roll (an example of a charging member)
60 exposure apparatus (an example of an image forming member)
62 Developing Device (Example of Image Forming Member)
64 Transfer roll (an example of a transfer member)
106 Protrusion (an example of a restriction structure)
108 cylindrical body 108A inner side surface 116A contact member 116B contact member 140 separation space 170 image forming apparatus 172 image holding body 174 cylindrical body 174A inner side surface 176 protrusion (an example of uneven portion)
180 recess (an example of a fitting part)

Claims (5)

A cylindrical tube that rotates and forms an image on the surface;
A plurality of contact members that are supported in contact with the inside of the cylindrical body, are arc-shaped with both ends facing each other along the inner side surface of the cylindrical body as viewed from the axial direction of the cylindrical body;
When viewed from the axial direction of the cylindrical body, a plurality of spaces are formed with respect to the cylindrical body so that a spaced space formed between the opposite ends is located in the same direction with respect to the axial center of the cylindrical body. A regulating structure for regulating the circumferential position of the contact member;
An image carrier comprising:   The restriction structure includes a protrusion that protrudes from an inner surface of the cylindrical body, is disposed in the spaced space, and extends in the axial direction from one end to the other end of the cylindrical body. Item 2. The image carrier according to Item 1. The regulatory structure is:
A concave or convex concavo-convex portion formed on the inner surface of the cylindrical body,
A fitting portion that is formed on the outer peripheral surface of the contact member and fits with the concave-convex portion;
The image carrier according to claim 1, comprising: The image carrier according to any one of claims 1 to 3,
A charging member that charges the surface of the image carrier by applying a superimposed voltage obtained by superimposing an AC voltage on a DC voltage;
An image forming member that forms an image on the surface of the charged image carrier;
A transfer member for transferring an image formed on the surface of the image carrier to a recording medium to be conveyed;
An image forming apparatus comprising: The contact members are respectively disposed on at least one and the other of the cylinders in the axial direction of the cylinder,
Density unevenness of an image caused by deformation of the cylindrical body caused by the contact member arranged on one side of the cylindrical body and deformation of the cylindrical body caused by the contact member arranged on the other side of the cylindrical body. The image forming apparatus according to claim 4, further comprising a correcting unit that corrects the image.