JP2015084098A - Contact member, image holding body, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact member configured to prevent a cross section of an image holding body from being periodically deformed, an image holding body and an image forming apparatus.SOLUTION: Contact sections 136 in contact with an inner peripheral surface 108A of a cylindrical body 108 in a contact member 116 are formed in three directions on an outer peripheral surface 118. Even if the cross section of the cylindrical body 108 is to be elliptically deformed due to periodic electrostatic attraction generated between an image holding body 56 and a charging roll 58, the cross section of the cylindrical body 108 can be prevented from being elliptically deformed by the contact sections 136 formed in the three directions. In charging a surface of the image holding body by the charging roll, the cross section of the cylindrical body 108 is prevented from being periodically deformed.

Description

  The present invention relates to a contact member, an image carrier, and an image forming apparatus.

  The image forming apparatus described in Patent Literature 1 includes a sliding contact member that contacts an inner wall surface of a photosensitive drum (image holding member) and presses the inner wall surface with a predetermined force. The charging noise is reduced by the sliding contact member.

JP 2000-315036 A

  An object of the present invention is to prevent the cross section of the image carrier from being periodically deformed.

  According to a first aspect of the present invention, the contact member is formed in a cylindrical shape in which a part spaced apart in the circumferential direction is formed, and is fitted into a cylindrical cylindrical body constituting the image holding body. The cylindrical body shaft is supported by the cylindrical body in contact with the inner peripheral surface of the cylindrical body at the contact portions formed in three regions in the circumferential direction of the cylindrical body, and is supported in the cylindrical body. When viewed from the direction, the angles formed by two straight lines out of the straight lines passing through the respective contact portions and the axial center of the cylindrical body are all greater than 90 degrees.

  A contact member according to a second aspect of the present invention is the contact member according to the first aspect, wherein the contact member is opposite to the spaced-apart portion with the axial center viewed from the axial direction in a state of being arranged inside the cylindrical body. A groove portion extending in the axial direction is formed on the side, the groove portion is formed in one of the contact portions, and the groove portion is arranged in the cylindrical body in a bent state with a separation distance of the separation portion narrowed. And

  The contact member according to claim 3 of the present invention is the contact member according to claim 1 or 2, wherein at least one of the contact portions is smaller than the radius of the inner peripheral surface of the cylindrical body when viewed from the axial direction. It has a circular arc shape with a radius.

  An image holding body according to a fourth aspect of the present invention is a cylindrical body that holds an image on a surface thereof, and the contact member according to any one of claims 1 to 3 disposed inside the cylindrical body. And.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus according to the fourth aspect, a charging device for charging the surface of the image holding body, and exposing the surface of the charged image holding body to static. An exposure apparatus that forms an electrostatic latent image; and a developing apparatus that develops an electrostatic latent image formed on the surface of the image carrier as a toner image.

  According to the contact member of the first aspect of the present invention, it is possible to prevent the cross section of the image carrier from being periodically deformed as compared with the case where the configuration is not provided.

  According to the contact member of claim 2 of the present invention, it is possible to bring all the contact portions into contact with the inner peripheral surface of the image carrier in a balanced manner as compared with the case where this configuration is not provided.

  According to the contact member of claim 3 of the present invention, compared to the case where the contact portion in contact with the inner peripheral surface is not an arc shape having a radius smaller than the radius (inner radius) of the inner peripheral surface of the cylindrical body, It can suppress that the position which a contact part and an internal peripheral surface contact | connect varies.

  According to the image carrier of claim 4 of the present invention, the cross section of the image carrier is periodically deformed as compared with the case where the contact member according to any one of claims 1 to 3 is not provided. Can be suppressed.

  According to the image forming apparatus of the fifth aspect of the present invention, compared to the case where the image holding body according to the fourth aspect is not provided, the sound generated by the cyclic deformation of the cross section of the image holding body is suppressed. can do.

(A) (B) (C) It is the perspective view and sectional drawing which showed the contact member which concerns on 1st Embodiment of this invention. It is sectional drawing which showed the image holding body etc. which concern on 1st Embodiment of this invention. 1 is a schematic configuration diagram illustrating an image forming unit used in an image forming apparatus according to a 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. 2A and 2B are a perspective view and a cross-sectional view illustrating a deformed state of an image carrier according to a comparative example with respect to the image carrier according to the first embodiment of the present invention. (A) (B) (C) It is the perspective view and sectional drawing which showed the deformation | transformation state of the image holding body which concerns on the comparative example with respect to the image holding body which concerns on 1st Embodiment of this invention. (A) (B) It is sectional drawing which showed the image holding body which concerns on the comparative example with respect to the image holding body which concerns on 1st Embodiment of this invention. (A) (B) (C) It is sectional drawing which showed the contact member which concerns on 2nd Embodiment, 3rd Embodiment, and 4th Embodiment of this invention. (A) and (B) are a sectional view and an enlarged sectional view showing a contact member according to a fifth embodiment of the present invention. It is drawing which showed the evaluation result of the contact member which concerns on 5th Embodiment of this invention with the table | surface. (A) (B) (C) It is sectional drawing which showed the contact member which concerns on the comparative example with respect to the contact member which concerns on 5th Embodiment of this invention. It is sectional drawing which showed the contact member which concerns on 6th Embodiment of this invention. It is the expanded sectional view which showed the modification of the contact member which concerns on 5th, 6th embodiment of this invention.

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

(overall structure)
As shown in FIG. 4, the image forming apparatus 10 according to the present embodiment includes an accommodating portion 14 that accommodates a sheet member P as a recording medium from below to above in the vertical direction (arrow H direction). , A conveyance unit 16 that conveys the sheet member P accommodated in the accommodation unit 14, an image forming unit 20 that forms an image on the sheet member P conveyed by the conveyance unit 16 from the accommodation unit 14, and an original that reads the read original G The reading unit 22 is provided in this order. Further, the image forming apparatus 10 includes a manual sheet feeding unit 90 that manually feeds the sheet member P.

[Container]
The accommodating portion 14 includes an accommodating member 26 that can be pulled out from the apparatus main body 10 </ b> A of the image forming apparatus 10 to the near side in the apparatus depth direction, and the sheet member P is stacked on the accommodating member 26. Further, the accommodating portion 14 is provided with a delivery roll 32 that sends the stacked sheet members P to the conveyance path 28 that constitutes the conveyance portion 16.

[Transport section]
The conveying unit 16 is disposed on the downstream side in the conveying direction of the sheet member P with respect to the delivery roll 32 (hereinafter simply referred to as “downstream side in the conveying direction”), and separates and conveys the sheet members P one by one. A separation roll 34 is provided.

  Further, in the conveyance path 28, the sheet member P is stopped once at the downstream side in the conveyance direction with respect to the separation roll 34, and the alignment roller 36 that sends the sheet member P to a transfer position T described later at a predetermined timing. Is arranged.

  Further, a discharge roll 76 that discharges the sheet member P on which the image is formed by the image forming unit 20 to a discharge unit 74 formed above the image forming unit 20 is disposed on the terminal end side of the conveyance path 28. .

  On the other hand, in order to form images on both sides of the sheet member P, a duplex conveying unit 78 that reverses the front and back of the sheet member P is provided on the side of the apparatus main body 10A. The duplex conveying unit 78 includes a reversing path 82 through which the sheet member P conveyed by reversing the discharge roll 76 is fed. Further, a plurality of conveying rolls 84 are arranged along the reversing path 82, and the sheet member P conveyed by these conveying rolls 84 is conveyed again to the alignment roll 36 with the front and back sides reversed. ing.

[Manual Feeder]
Further, a foldable manual sheet feeding unit 90 is provided next to the duplex conveying unit 78. The manual paper feed unit 90 includes a manual paper feed member 92 that can be opened and closed. Further, a sheet feeding roll 94 for conveying the sheet member P fed from the opened manual sheet feeding member 92 and a plurality of conveyance rolls 96 are provided in the manual sheet feeding unit 90, and are conveyed by the conveyance roll 96. The sheet member P is conveyed to the alignment roll 36.

[Original reading section]
On the other hand, the original reading unit 22 provided on the upper side of the image forming apparatus 10 has a read original G carried on the platen glass 42 on the read original G conveyed by the automatic original conveying apparatus 40 that conveys the read original G. A light source 44 for irradiating light is provided.

  Further, the original reading unit 22 has a full-rate mirror 46 that reflects the reflected light that is irradiated from the light source 44 and reflected from the read original G in a direction parallel to the platen glass 42, and the reflected light that is reflected by the full-rate mirror 46 is downward. The half-rate mirror 48 that reflects to the platen, the half-rate mirror 50 that reflects and reflects the reflected light reflected by the half-rate mirror 48 in a direction parallel to the platen glass 42, and the reflected light that is folded by the half-rate mirror 50 are incident. And an imaging lens 52 are provided.

  In addition, the document reading unit 22 includes a photoelectric conversion element 54 that converts the reflected light imaged by the imaging lens 52 into an electrical signal, and further performs image processing on the electrical signal converted by the photoelectric conversion element 54. An image processing unit 24 is provided.

  The light source 44, the full rate mirror 46, the half rate mirror 48, and the half rate mirror 50 are movable along the platen glass 42. When reading the read original G placed on the platen glass 42, the read original G placed on the platen glass 42 while moving the light source 44, the full rate mirror 46, the half rate mirror 48 and the half rate mirror 50. The reflected light reflected from the read original G is imaged on the photoelectric conversion element 54.

  When reading the read document G conveyed by the automatic document conveying device 40, the light source 44, the full rate mirror 46, the half rate mirror 48 and the half rate mirror 50 are stopped and the reading conveyed by the automatic document conveying device 40 is performed. The light source 44 irradiates the original G with light, and the reflected light reflected from the read original G forms an image on the photoelectric conversion element 54.

(Image forming part)
As shown in FIG. 3, the image forming unit 20 includes an image carrier 56, a charging roll 58 that charges the surface of the image carrier 56, and exposure light on the surface of the image carrier 56 that is charged based on image data. And an exposure device 60 (see FIG. 4) for forming an electrostatic latent image and a developing device 62 for developing the electrostatic latent image and visualizing it as a toner image.

  Further, the image forming unit 20 includes a transfer roll 64 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, a heating roll 66H, and a pressure roll 66N. And a fixing device 66 (see FIG. 4) that heats and presses the toner image on the sheet member P to fix it on the sheet member P, and the toner remaining on the image carrier 56 after the toner image is transferred. And a cleaning blade 68 that scrapes off the image carrier 56 to clean the image carrier 56.

  As shown in FIG. 4, a toner cartridge 72 connected to the developing device 62 through a supply pipe (not shown) is disposed obliquely above the exposure device 60. The toner cartridge 72 is filled with toner to be supplied to the developing device 62 through a supply pipe.

  In this configuration, the sheet member P fed from the alignment roll 36 is conveyed to a transfer position T constituted by the image holding body 56 and the transfer roll 64, and is sandwiched between the image holding body 56 and the transfer roll 64. Be transported. As a result, the toner image formed on the image carrier 56 is transferred to the sheet member P.

  Here, the image carrier 56, the charging roll 58, the developing device 62, and the cleaning blade 68 constitute an image forming unit 70, and the image forming unit 70 is detachable from the apparatus main body 10A. .

  Details of the image carrier 56 and the charging roll 58 will be described later.

(Operation of the overall configuration)
In the image forming apparatus 10, an image is formed as follows.

  First, the charging roll 58 to which a voltage has been applied uniformly charges the surface of the image carrier 56 uniformly at a predetermined potential. Subsequently, the exposure device 60 irradiates the surface of the image carrier 56 charged by the exposure device 60 based on image data read by the document reading unit 22 or data input from the outside to form an electrostatic latent image. .

  As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the image carrier 56. Further, the electrostatic latent image is developed by the developing device 62 and visualized as a toner image.

  Therefore, the sheet member P sent out from the storage member 26 to the transport path 28 by the sending roll 32 or fed from the manual sheet feeding member 92 to the transport path 28 is determined by the alignment roll 36. Sent to the transfer position T at the same timing. At the transfer position T, the sheet member P is nipped and conveyed between the image carrier 56 and the transfer roll 64, whereby the toner image formed on the surface of the image carrier 56 is transferred to the surface of the sheet member P.

  The toner image transferred to the sheet member P is fixed to the sheet member P when the sheet member P passes between a heating roll 66H and a pressure roll 66N provided in the fixing device 66. Then, the sheet member P with the toner image fixed on the surface is discharged to the discharge portion 74 by the discharge roll 76.

  On the other hand, when an image is also formed on the back surface of the sheet member P, the discharge roller 76 is reversed without discharging the sheet member P to the discharge unit 74, and the sheet member P on which the toner image is formed is reversed. Send to path 82. As a result, the front and back of the sheet member P are reversed, and the transport roll 84 transports the sheet member P to the alignment roll 36 again.

  This time, the toner image is transferred to the back surface of the sheet member P at the transfer position T, and the sheet member P on which the toner image is transferred to the back surface is discharged to the discharge unit 74 in the above-described procedure.

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

[Charging roll]
As shown in FIG. 2, the charging roll 58 extends in the depth direction of the apparatus, and has a shaft portion 58A formed of a metal material (for example, stainless steel) and a cylindrical shape into which the shaft portion 58A is inserted. The roll part 58B shape | molded by this.

  Further, both end sides of the shaft portion 58A are exposed to the outside from the roll portion 58B 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.

  Further, a superimposed voltage obtained by superimposing an AC voltage on a DC voltage is applied to the shaft portion 58A from a power source (not shown).

(Image carrier)
As shown in FIG. 2, the image holding body 56 includes a cylindrical cylinder 108 extending in the apparatus depth direction, and the apparatus depth direction in the cylinder 108 (in this embodiment, the same direction as the axial direction of the cylinder 108). And a support member 112 fixed to the other end side (lower side in the figure) of the cylindrical body 108 in the apparatus depth direction. Further, the image holding body 56 includes a contact member 116 that is disposed inside the cylinder body 108 and suppresses deformation of the cross section of the cylinder body 108.

  The cylinder 108 is obtained by forming a photosensitive layer on the outer surface of a base material formed by cylindrically molding a metal material (for example, aluminum).

  The transmission member 110 is formed into a disk shape with a resin material, and is fixed to one end side of the cylinder body 108 by being partially fitted inside the cylinder body 108, and closes one end side of the opened cylinder body 108. Yes. 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. A plurality (two in FIG. 2) 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 support member 112 is formed into a disk shape with a resin material, and is fixed to the other end side of the cylinder body 108 by being partially fitted inside the cylinder body 108, and the other end side of the opened cylinder body 108 is closed. doing. 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.

  As shown in FIG. 2, the contact member 116 is fitted inside the cylinder 108 and arranged on the center side in the apparatus depth direction of the cylinder 108. As shown in FIG. Is in contact with the inner peripheral surface 108A of the cylinder 108 and is supported by the cylinder 108.

  Specifically, the contact member 116 is formed of a resin material (for example, ABS resin (acrylonitrile, butadiene, styrene)), and a part of the contact member 116 is separated in the circumferential direction as shown in FIGS. 116A is formed, and a cylindrical shape (C-shape) extending in the apparatus depth direction is formed. Further, as shown in FIG. 1C, in a state where the contact member 116 is disposed inside the cylinder 108, the contact member 116 on the opposite side of the spacing portion 116A across the axial center F of the cylinder 108 is sandwiched. On the outer peripheral surface 118, a groove 116B extending in the apparatus depth direction is formed.

  Further, as shown in FIG. 1C, a contact portion 136 that is in contact with the inner peripheral surface 108A of the cylindrical body 108 extends in the apparatus depth direction and projects in the radial direction on the outer peripheral surface 118 of the contact member 116. Has been. And this contact part 136 is formed in 3 area | regions (3 places) of the outer peripheral surface 118. FIG. More specifically, a contact portion 136A composed of a pair of protrusions 138 disposed on both sides of the groove portion 116B when viewed from the apparatus depth direction, and one side (counterclockwise side in the drawing) with respect to the contact portion 136A. A contact portion 136B composed of the protrusions 140 to be disposed and a contact portion 136C composed of the protrusions 142 disposed on the other side (clockwise side in the drawing) with respect to the contact portion 136A are formed on the outer peripheral surface 118 Has been. That is, the groove part 116B is formed in the contact part 136A.

  As shown in FIG. 1C, in the state where the contact member 116 is disposed (supported) inside the cylinder 108, the circumferential center of each contact portion 136 and the cylinder 108 (image carrier). 56), the angles formed by two straight lines out of the straight lines passing through the axial center F are all 120 degrees (angle N shown in FIG. 1C).

  Further, as shown in FIGS. 1B and 1C, the separation distance (distance K in the drawing) in the separation portion 116 </ b> A in a state where the contact member 116 is not disposed inside the cylindrical body 108 is the contact member 116. Is longer than the case where it is arranged inside the cylinder 108.

  In this configuration, when the contact member 116 is disposed inside the cylindrical body 108, the contact member 116 is gripped and the contact member 116 is bent by deforming the groove 116B so that the separation distance of the separation portion 116A is shortened. . In this state, the contact member 116 is inserted into the cylindrical body 108 to release the gripping force. As a result, the contact portions 136A, 136B, and 136C of the contact member 116 are in contact with the inner peripheral surface 108A of the cylindrical body 108, and the contact member 116 is supported by the cylindrical body 108 and disposed inside the cylindrical body 108.

  That is, the contact member 116 is disposed inside the cylinder 108 in a bent state.

[Others]
As shown in FIG. 2, a motor 122 as an example of a drive source that generates a rotational force transmitted to the image carrier 56 (transmission member 110) is disposed on one end side of the image carrier 56 in the apparatus depth direction. Has been.

  A main body 122A of the motor 122 is attached to a plate-like frame 124 disposed in the apparatus main body 10A (see FIG. 4). Further, the motor shaft portion 122B of the motor 122 extends on the axial center F of the cylindrical body 108, passes through the through hole 126A formed in the housing 126 of the image forming unit 70 (see FIG. 3), and the through hole of the transmission member 110. 110A is inserted. Further, a plate-like bracket 128 that is bent and inserted into the recess 110B of the transmission member 110 is fixed to the outer peripheral surface of the motor shaft portion 122B. Thereby, the transmission member 110 is assembled | attached integrally (with no backlash) with respect to the motor shaft part 122B. The transmission member 110 transmits the rotational force generated by the motor 122 to the cylindrical body 108.

  On the other hand, a shaft member 130 having a cylindrical shaft portion 130C that rotatably supports the image carrier 56 (support member 112) is disposed on the other end side of the image carrier 56 in the apparatus depth direction.

  The shaft member 130 is formed of a resin material (for example, ABS), and a pedestal portion 130A that is attached to the inner surface 126B of the housing 126, and a step portion 130B that is disposed on the image carrier 56 side through the step from the pedestal portion 130A. And have. Further, the shaft member 130 has the above-described shaft portion 130 </ b> C that extends from the stepped portion 130 </ b> B onto the shaft center F of the cylindrical body 108 and is inserted into the through hole 112 </ b> A of the support member 112.

  The support member 112 functions as a so-called sliding bearing with respect to the shaft portion 130C, and a gap is provided between the inner peripheral surface of the through hole 112A and the outer peripheral surface of the shaft portion 130C.

  In this configuration, when the motor 122 is operated, the motor shaft 122B rotates. The rotation of the motor shaft portion 122 </ b> B is transmitted to the cylinder body 108 through the bracket 128 and the transmission member 110 fixed to one end side of the cylinder body 108. Then, the support member 112 fixed to the other end side of the cylindrical body 108 rotates with respect to the shaft portion 130 </ b> C, so that the image holding body 56 rotates about the axis center F.

(Effects of main components)
Next, functions of the image carrier 56, the charging roll 58, and the like will be described.

  When the motor 122 is operated, the image carrier 56 rotates. When the image carrier 56 rotates, the charging roll 58 is driven to rotate. In order to charge a photosensitive layer (not shown) of the image carrier 56, a superimposed voltage obtained by superimposing an AC voltage on a DC voltage is applied from a power source to the shaft portion 58 </ b> A of the charging roll 58.

  An alternating electric field is generated between the charging roll 58 and the image carrier 56 by the alternating voltage (1 kHz to 3 kHz) constituting the superimposed voltage. Thereby, a periodic (2 kHz to 6 kHz) electrostatic attraction force is generated between the image carrier 56 and the charging roll 58.

  Here, an image carrier 200 as a first comparative example with respect to the image carrier 56 of the present embodiment will be described with reference to FIGS. 5 and 6, and a second comparison with respect to the image carrier 56 of the present embodiment. An image carrier 204 as an example will be described with reference to FIG.

  First, the image carrier 200 will be described. The image carrier 200 has the same configuration as the image carrier 56 except that the contact member 116 is not provided.

  5A and 5B, an example of a deformed state of the cylindrical body 108 of the image holding body 200 when a periodic electrostatic attraction force is generated between the image holding body 200 and the charging roll 58 is exaggerated. It is shown as Since the transmission member 110 or the support member 112 is fixed to both sides of the cylinder 108 in the apparatus depth direction (see FIG. 2), the deformation of the cross section of the cylinder 108 at both ends of the cylinder 108 in the apparatus depth direction is It is suppressed. On the other hand, on the center side in the apparatus depth direction of the cylinder 108, as shown in FIG. 5B, the cross section of the cylinder 108 is periodically deformed into an elliptical shape.

  Similarly, FIGS. 6A, 6 </ b> B, and 6 </ b> C show the cylindrical body 108 of the image carrier 200 when a periodic electrostatic attraction force is generated between the image carrier 200 and the charging roll 58. Another example of the deformed state is exaggerated. As described above, the deformation of the cross section of the cylinder 108 at both ends of the cylinder 108 in the apparatus depth direction is suppressed. On the other hand, between the central portion of the cylinder 108 in the apparatus depth direction and one end of the cylinder 108, as shown in FIG. As shown in FIG. 6C, the cross section of the body 108 is periodically deformed into a vertically long elliptical shape, and between the central part of the cylinder 108 in the apparatus depth direction and the other end of the cylinder 108, The cross section of the cylinder 108 is periodically deformed into a horizontally long elliptical shape.

  Next, the image carrier 204 will be described. The image carrier 204 has the same configuration as the image carrier 56 except that the shape of the contact member 206 is different from that of the contact member 116.

  The contact member 206 has the same configuration as that of the contact member 116 except that the contact member 136 is formed with four regions instead of three regions with respect to the contact member 116. Specifically, each contact portion 136 in the contact member 206 is composed of one protrusion 208 as shown in FIGS. In the state where the contact member 206 is disposed inside the cylindrical body 108, an angle formed by two adjacent straight lines among the straight lines passing through the respective contact portions 136 and the axial center F of the cylindrical body 108 (image holding body 204). Are all 90 degrees (angle M shown in FIG. 7B).

  For this reason, in the image carrier 204, as shown in FIGS. 7A and 7B, when the cross section of the cylindrical body 108 is periodically deformed into a vertically long elliptical shape and when it is deformed to a horizontally long elliptical shape. Moreover, the cross-sectional deformation of the cylinder 108 is not suppressed.

  However, in the image carrier 56 according to the present embodiment, unlike the image carriers 200 and 204 according to the comparative example, the image carrier 56 is provided with a contact member 116, and as shown in FIG. The contact portion 136 of the contact member 116 is formed in three regions on the outer peripheral surface 118. Further, in a state where the contact member 116 is disposed inside the cylinder 108, the angles formed by two straight lines out of the straight lines passing through the respective contact portions 136 and the axial center F of the cylinder 108 (image holding body 56) are all. It is 120 degrees (angle N shown in FIG. 1C).

  For this reason, even when the cross section of the cylindrical body 108 is about to be deformed into an elliptical shape, it is suppressed that the cross section of the cylindrical body 108 (image holding body 56) is deformed into an elliptical shape by the contact portion 136 in the three regions. The In other words, when the surface of the image holding member 56 is charged by the charging roll 58, it is possible to prevent the cross section of the cylindrical body 108 from being periodically deformed.

  Further, since the cross section of the cylindrical body 108 is suppressed from being periodically deformed, the sound generated when the cross section of the cylindrical body 108 is periodically deformed is suppressed.

  In addition, since the contact portion 136 is formed in the three regions of the outer peripheral surface 118, the contact region 136 in the three regions is formed on the cylindrical body 108 even when manufacturing variations occur in the heights of the protrusions 138, 140, and 142. It contacts the inner peripheral surface 108A.

  Further, the separation portion 116A and the groove portion 116B are formed in the contact portion 136A, and the contact member 116 is disposed inside the cylindrical body 108 in a state where the groove portion 116B is deformed and the contact member 116 is bent. That is, the contact member 116B is formed in a state where the contact member 136B is formed on one side with respect to the groove 116B and the contact member 136C is formed on the other side with respect to the groove 116B. 108 is disposed inside. Thereby, compared with the case where the contact portion is formed in two regions on one side with respect to the groove portion 116 </ b> B, the contact portion 136 in the three regions contacts the inner peripheral surface 108 </ b> A of the cylindrical body 108 with a good balance.

<< Second Embodiment >>
Next, an example of the contact member, the image carrier, and the image forming apparatus according to the second embodiment of the present invention will be described with reference to FIG. 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.

  The groove portion 170B of the contact member 170 of the second embodiment is formed on the inner peripheral surface 172 of the contact member 170 on the opposite side of the spacing portion 116A across the axial center F of the cylindrical body. And contact part 136D is comprised from one protrusion 174 arrange | positioned on the opposite side of the groove part 170B seeing from an apparatus depth direction. About an effect | action, it is the same as that of 1st Embodiment.

«Third embodiment»
Next, an example of the contact member, the image carrier, and the image forming apparatus according to the third embodiment of the present invention will be described with reference to FIG. In addition, about the same member as 2nd Embodiment, the same code | symbol is attached | subjected, the description is abbreviate | omitted, and a different part from 2nd Embodiment is mainly demonstrated.

  The groove part 180 </ b> B of the contact member 180 of the third embodiment is formed in two regions of the inner peripheral surface 182 of the contact member 180. Specifically, a groove portion 180 </ b> B is formed on an inner peripheral surface 182 between the protrusion 140 and the protrusion 174 and an inner peripheral surface 182 between the protrusion 142 and the protrusion 174. About an effect | action, it is the same as that of 2nd Embodiment.

<< Fourth Embodiment >>
Next, an example of the contact member, the image carrier, and the image forming apparatus according to the fourth embodiment of the present invention will be described with reference to FIG. In addition, about the same member as 2nd Embodiment, the same code | symbol is attached | subjected, the description is abbreviate | omitted, and a different part from 2nd Embodiment is mainly demonstrated.

  The contact member 190 according to the fourth embodiment is not cylindrical but triangular. About an effect | action, it is the same as that of 2nd Embodiment.

«Fifth embodiment»
Next, an example of a contact member, an image carrier, and an image forming apparatus according to a fifth 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.

(Constitution)
As shown in FIGS. 9A and 9B, the contact member 220 of the fifth embodiment is formed with a separation portion 220 </ b> A that is partially separated in the circumferential direction. Further, in a state where the contact member 220 is disposed inside the cylinder body 108, the outer surface 222 of the contact member 220 on the opposite side of the separation portion 220 </ b> A across the axis center F of the cylinder body 108 has a device depth direction (axis Groove 220B extending in the direction) is formed.

  Further, the outer peripheral surface 222 of the contact member 220 includes a pair of protrusions 238 disposed on both sides of the groove 220B when viewed from the depth direction of the apparatus, and a contact portion 236A that contacts the inner peripheral surface 108A of the cylindrical body 108 is formed. ing. Further, the outer peripheral surface 222 has a contact portion 236B composed of a protrusion 240 disposed on one side (counterclockwise side in the drawing) with respect to the contact portion 236A, and the other side (in the drawing in the drawing). And a contact portion 236 </ b> C composed of a protrusion 242 arranged on the clockwise side).

  The contact portions 236B and 236C are formed in an arc shape having a radius smaller than the radius (inner radius) of the inner peripheral surface 108A of the cylindrical body 108 when viewed from the apparatus depth direction. In the present embodiment, as an example, the radius of the inner peripheral surface 108A of the cylinder 108 (radius R1 in the drawing) is 14.25 [mm], and the radius of the contact portion 236 (radius R2 in the drawing) is 10 [ mm].

(Evaluation)
Next, the contact member 220 according to the present embodiment is arranged inside the cylinder 108, and the contact portion 236 and the cylinder when the ambient temperature is low (10 ° C.), room temperature (20 ° C.), and high temperature (50 ° C.). The evaluation result evaluated about the position which contact | connects the internal peripheral surface 108A of the body 108 is demonstrated. The evaluation was performed using a finite element method simulation.

  Furthermore, when performing the evaluation, the material of the cylinder 108 was aluminum, and the material of the contact member 220 was ABS resin. Further, as described above, the radius of the inner peripheral surface 108A of the cylindrical body 108 is 14.25 [mm], and the radius of the contact portion 236 is 10 [mm].

  The vertical axis of the graph shown in FIG. 10 represents the angle R (angle L) shown in FIG. 9A, and the horizontal axis is the ambient temperature around the cylinder 108 in which the contact member 220 is disposed. As shown in FIG. 9A, the angle R (angle L) includes a line segment Y that passes through the center of the groove 220B from the axis center F, and an inner part of the contact part 236B (contact part 236C) from the axis center F. This is an angle formed by a line segment X (line segment P) passing through a position where the peripheral surface 108A contacts.

  In a room temperature state, the angle R (angle L) is 120 degrees. When the ambient temperature is raised or lowered, the shape of the cylinder 108 and the shape of the contact member 220 change relatively due to the difference between the linear expansion coefficient of the cylinder 108 and the linear expansion coefficient of the contact member 220. Thereby, the contact position between the contact portion 236B (contact portion 236C) and the inner peripheral surface 108A changes. However, since the shapes of the contact portions 236B and 236C are arcuate, as shown in the graph of FIG. 10, even when the ambient temperature becomes low or high, the angle R is smaller than that of the comparative example described later. The change in (angle L) is small.

  In the comparative example, as shown in FIG. 11A, the contact portion and the inner peripheral surface 108A are in surface contact at room temperature. However, as shown in FIGS. 11B and 11C, at a low temperature or a high temperature, the contact position moves due to a relative change in the shape of the cylindrical body 108 and the contact member.

(Action / Summary)
The shapes of the contact portions 236B and 236C are arcuate when viewed from the apparatus depth direction. For this reason, compared with the case where a contact part and the internal peripheral surface 108A are surface-contacting, it is suppressed that the position which the contact part 236 and the internal peripheral surface 108A contact | abut is changed by atmospheric temperature change.

  The contact portions 236B and 236C have a circular arc shape when viewed from the depth direction of the apparatus. For this reason, the position where the contact portion 236 and the inner peripheral surface 108A are in contact with each other varies depending on the design of the single-piece shape of the cylindrical body 108 or the single-piece shape of the contact member 220, similar to the effect due to the change in the ambient temperature. Is suppressed.

  In addition, the variation in the position where the contact portion 236 and the inner peripheral surface 108A are in contact is suppressed, so that the natural frequency of the image carrier 56 is suppressed from varying.

  In addition, in the image holding member 56, unevenness in charging is suppressed by suppressing the natural frequency from varying.

<< Sixth Embodiment >>
Next, an example of the contact member, the image carrier, and the image forming apparatus according to the sixth embodiment of the present invention will be described with reference to FIG. In addition, about the same member as 5th Embodiment, the same code | symbol is attached | subjected, the description is abbreviate | omitted, and a different part from 5th Embodiment is mainly demonstrated.

  As shown in FIG. 12, unlike the fifth embodiment, the spacing portion 250A of the contact member 250 according to the sixth embodiment is disposed across the protrusion 238, and the groove portion of the contact member 250 according to the sixth embodiment. Unlike the fifth embodiment, 250B is disposed on the opposite side of the groove 250B with respect to the axial center F.

  For this reason, when deforming the groove portion 250B and bending the contact member 250 in the direction of the arrow S in the drawing to place the contact member 250 inside the cylinder 108, the contact portion 236B (236C) is changed to the arrow T in the drawing. The inner peripheral surface 108A is pressed in the direction. For this reason, the contact portion 236B (236C) is formed in the inner portion as compared with the case where the inner peripheral surface 108A is pressed in the tangential direction of the contact portion 236B (236C) at the position where the contact portion 236B (236C) and the inner peripheral surface 108A contact. The pressing force that presses the peripheral surface 108A is effectively transmitted to the cylindrical body 108.

  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-described embodiment, in a state where the contact members 116, 170, 180, and 190 are disposed inside the cylindrical body 108, they pass through the respective contact portions 136 and the axial center F of the cylindrical body 108 (image holding body 56). The angles formed by the two straight lines out of the straight lines are all set to 120 degrees, but may not be 120 degrees as long as the angles formed by the two straight lines are all made larger than 90 degrees.

  Although not particularly described in the above embodiment, when a plurality of protrusions are formed in the contact portion, each protrusion and the axial center F of the cylindrical body 108 in the protrusion formed in the adjacent contact portion. The angle formed by two straight lines out of the straight lines passing through (angle J shown in FIG. 1C) may be 90 degrees or more.

  Although not specifically described in the above embodiment, the shape of the grooves 116B, 170B, and 180B formed in the contact members 116, 170, 180, and 190 may be rectangular or V-shaped. It may be U-shaped.

  Moreover, in the said embodiment, although the protrusion was formed in the contact member over the apparatus depth direction, a part may be spaced apart.

  Moreover, in the said embodiment, although the groove part 116B, 170B, 180B was formed in the contact member 116,170,180,190, it does not need to be specifically formed.

  Moreover, in the said embodiment, although the contact part was extended and formed in the apparatus depth direction, you may form in a helical form in the outer peripheral surface of a contact member.

  Moreover, in the said embodiment, although the contact member was shape | molded by ABS resin, you may shape | mold by other materials (resin material, metal material) etc.

  In the fifth and sixth embodiments, the contact portions 236B and 236C are arcuate, but at least one contact portion 236 may be arcuate.

  Further, in the fifth and sixth embodiments, the contact portions 236B and 236C are formed in an arc shape, but all the contact portions 236 may be formed in an arc shape by shifting the groove portion or the separation portion.

  In the fifth and sixth embodiments, the entire protrusions 240 and 242 are formed in an arc shape, so that the contact portions 236B and 236C are formed in an arc shape. It suffices if the portion that contacts with the circular arc is in the shape of an arc, and as shown in FIGS. Good.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 56 Image holding body 58 Charging roll (an example of charging device)
60 exposure apparatus 108 cylindrical body 108A inner peripheral surface 116 contact member 116A separation part 116B groove part 136 contact part 170 contact member 170B groove part 180 contact member 180B groove part 190 contact member 220 contact member 220A separation part 220B groove part 236 contact part 250 contact member 250A separation Part 250B Groove part

Claims (5)

  Formed in three regions in the circumferential direction of the cylindrical body that is formed in a cylindrical shape in which a part of the circumferentially separated space is formed and is fitted inside a cylindrical cylindrical body constituting the image holding body. The contact portions are in contact with the inner peripheral surface of the cylindrical body and are supported by the cylindrical body, and are supported in the cylindrical body and viewed from the axial direction of the cylindrical body. A contact member in which the angles formed by two straight lines out of the straight lines passing through the axis of the body are all greater than 90 degrees. A groove portion extending in the axial direction is formed on the opposite side of the spacing portion across the shaft center when viewed from the axial direction in a state of being disposed inside the cylindrical body,
2. The contact member according to claim 1, wherein the groove portion is formed in one of the contact portions, and is disposed inside the cylindrical body in a state where the groove portion is bent and narrowed.   The contact member according to claim 1, wherein at least one of the contact portions has an arc shape having a radius smaller than a radius of an inner peripheral surface of the cylindrical body when viewed from the axial direction. A cylindrical body holding an image on the surface;
The contact member according to any one of claims 1 to 3, which is disposed inside the cylindrical body,
An image carrier comprising: An image carrier according to claim 4,
A charging device for charging the surface of the image carrier;
An exposure device that exposes the surface of the charged image carrier to form an electrostatic latent image; and
A developing device for developing an electrostatic latent image formed on the surface of the image carrier as a toner image;
An image forming apparatus comprising:

Images