JP2009287590A - Bearing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device having reduced friction force along the rotation of a rotor, and also to provide an image forming device having the same. <P>SOLUTION: The image forming device 10 has a photoreceptor 20, and the bearing device 100 for supporting a shaft 46 of the photoreceptor 20. The bearing device 100 has: a rotary sleeve 102 fixed to the rotating shaft 46 at least in the rotating direction of the shaft 46; a fixed sleeve 150 fixed to an image forming structure body 36 supporting the shaft 46 at least in the rotating direction of the shaft 46; and a cover member 180 for thrusting the rotary sleeve 102 and the fixed sleeve 150 to abut on each other in the direction of the shaft 46. The rotary sleeve 102 and the fixed sleeve 150 have contact portions for contacting each other, at least one of which is formed as a part of the conical surface with an axis 48 of the shaft 46 as a center line. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  Patent Document 1 includes a lower case made of synthetic resin, an upper case made of synthetic resin combined with the lower case, and a thrust sliding bearing means made of synthetic resin disposed between the upper and lower cases. The lower case has a cylindrical portion having an inner surface as an insertion hole, an annular wide flange extending on the outer peripheral surface of the end of the cylindrical portion, and an annular groove formed on the upper surface of the wide flange. An annular protrusion formed upright, an annular recess formed by the annular protrusion and the upper surface of the wide flange portion, and an annular engagement protrusion formed upright on the outer peripheral edge of the wide flange portion, The upper case includes a cylindrical portion, an annular wide flange extending on the outer peripheral surface of the end of the cylindrical portion, an annular flange extending radially inward at the other end of the cylindrical portion, and an outer side of the wide flange. And an annular engagement hanging portion that hangs down at the periphery, and the upper case has an inner peripheral surface of the cylindrical portion and an outer periphery of the cylindrical portion of the lower case. A radial bearing portion is formed between the lower case, the lower surface of the annular flange portion faces the end surface of the cylindrical portion of the lower case, and the annular engagement hanging portion is elastically attached to the annular engagement protrusion of the lower case. There is disclosed a synthetic resin bearing characterized in that the thrust slide bearing means is disposed between the facing surfaces of the annular concave portion of the lower case and the annular wide flange portion of the upper case (Patent Document). 1).

JP-A-9-72339

  An object of the present invention is to provide a bearing device capable of reducing a frictional force accompanying rotation of a rotating body and an image forming apparatus having such a bearing device.

  The first feature of the present invention is that the shaft is fixed to a rotating shaft at least in the rotational direction of the shaft, and the support portion that supports the shaft is fixed at least in the rotational direction of the shaft. And a pressing means for pressing the first bearing portion and the second bearing portion so as to abut against each other in the axial direction, and the first bearing portion and The second bearing portion has contact portions that contact each other, and at least one of the contact portions is in a bearing device that forms a part of a conical surface having the center of the shaft as a center line.

  Preferably, the pressing means includes a biasing member that is assembled to the second bearing member and biases the first bearing portion in the direction of the second bearing portion.

  Preferably, the urging member includes a mounting portion that is mounted on the second bearing portion, an elastic portion that is integral with the mounting portion and elastically deforms in a direction away from the first bearing portion. Have.

  Preferably, the apparatus further includes a holding portion that is formed between the second bearing portion and the first bearing portion and holds the lubricant.

  Preferably, the first bearing portion and the second bearing portion have at least two contact portions, and one of these contact portions is the first bearing portion and the second bearing portion. An annular first convex portion formed on one of the bearing portions, and the other one of these contact portions is an annular second convex portion formed outside the first convex portion. The holding portion is formed between the first convex portion and the second convex portion.

  Preferably, the first bearing portion and the second bearing portion are made of materials in which at least the contact portions are different from each other.

  Preferably, at least one of the first bearing portion and the second bearing portion is such that at least the contact portion is made of polycarbonate, and one of the first bearing portion and the second bearing portion. On the other hand, at least the contact portion is made of polyacetal.

  The second feature of the present invention is that it includes a rotating body that rotates during image formation, and a bearing device that supports a shaft of the rotating body, and the bearing device includes at least the shaft. A first bearing portion fixed in the rotation direction of the shaft; a second bearing portion fixed in at least the rotation direction of the shaft to a support portion supporting the shaft; the first bearing portion and the second bearing portion; The first bearing portion and the second bearing portion have contact portions that are in contact with each other, and the contact portions are in contact with each other in the axial direction. At least one of the parts is in an image forming apparatus that forms a part of a conical surface with the center of the axis as a center line.

  ADVANTAGE OF THE INVENTION According to this invention, the bearing apparatus which can reduce the frictional force accompanying rotation of a rotary body, and the image forming apparatus which has such a bearing apparatus can be provided.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an image forming apparatus 10 according to a first embodiment of the present invention.
The image forming apparatus 10 includes an image forming apparatus main body 12, a discharge unit 16 is provided on the upper part of the image forming apparatus main body 12, and an image forming unit 14 and an image forming unit are provided in the image forming apparatus main body 12. A paper supply unit 50 that supplies paper to 14 is mounted, and a paper conveyance path 18 through which the paper is conveyed is formed in the image forming apparatus main body 12.

  The image forming unit 14 is of an electrophotographic type, and is used as an image holding member, a drum-shaped photosensitive member 20 used as a rotating member that rotates during image formation, and a charging device 22 that uniformly charges the photosensitive member 20. An optical writing device 24 that writes a latent image on the photosensitive member 20 charged by the charging device 22 with light, and a developing device that develops and visualizes the latent image of the photosensitive member 20 formed by the optical writing device 24 with a developer. 26, a transfer device 28 composed of, for example, a transfer roll for transferring the developer image visualized by the developing device 26 to a sheet, a cleaning device 30 for cleaning the developer remaining on the photosensitive member 20, and a transfer device 28. And a fixing device 32 for fixing the developer image on the sheet to the sheet. Among the members constituting the image forming unit 14, the photoconductor 20, the charging device 22, the developing device 26, and the cleaning device 30 are integrated as an image forming structure 34, for example, on the front side of the image forming apparatus main body 12 ( The image forming apparatus main body 12 can be attached to and detached from the right side in FIG.

  The photoconductor 20 is provided on the left side plate (front side plate in FIG. 1) of the image forming structure main body 36 with respect to the image forming structure main body 36 which is a housing of the image forming structure, and serves as a rotating body support device. The bearing device 100 used as an image forming rotating body support device and a bearing member 200 provided on the right side plate (the side plate on the back side in FIG. 1) of the image forming structure main body 36 are used so as to be rotatable. Has been. As described above, in this embodiment, the bearing device 100 and the bearing member 200 connect the photosensitive member 20 to the image forming apparatus main body 12 via the image forming structure main body 36 attached to the image forming apparatus main body 12. Although supported indirectly, the bearing device 100 and the bearing member 200 may be used so as to directly support the photosensitive member 20 with respect to the image forming apparatus main body 12. That is, the bearing device 100 and the bearing member 200 may be directly attached to the image forming apparatus main body 12.

The paper supply unit 50 includes a paper storage container 52, a pickup roll 54, a delivery roll 56, and a separating roll 58.
The paper storage container 52 stores paper used as a recording medium in a stacked state, and the paper storage container 52 can be pulled out, for example, to the front side of the image forming apparatus main body 12. The image forming apparatus main body 12 can be attached to and detached from the front side, and the paper can be replenished while being pulled out or removed from the image forming apparatus main body 12.

  The pick-up roll 54 is used to take out the paper located at the top of the papers stacked in the paper storage container 52. The delivery roll 56 is used to send out the paper taken out by the pickup roll 54 toward the downstream side in the paper transport direction. Further, when the paper roll 58 is supplied in a state where the paper is overlapped from the pickup roll 54 side, the paper roll 58 has a function of picking up and separating the paper in the overlapped state.

  In the image forming apparatus main body 12, the paper supply unit 50, the registration roll 40, the transfer device 28, and the fixing device 32 described above are sequentially provided along the paper transport path 18 from the upstream side in the paper transport direction. And a discharge roll 42 are provided. The registration roll 40 is used to supply the sheet fed from the sheet supply unit 50 to the contact portion between the photoconductor 20 and the transfer device 28 in accordance with the timing at which the image forming unit 14 forms an image. The discharge roll 42 is used to discharge the sheet on which the developer image has been fixed by the fixing device 32 to the discharge unit 16.

  In the image forming apparatus 10 configured as described above, the photosensitive member 20 is uniformly charged by the charging device 22, and light emitted from the optical writing device 24 based on the image signal is applied to the charged photosensitive member 20. Irradiation forms a latent image, and this latent image is developed by the developer of the developing device 26 to form a developer image. On the other hand, the paper loaded in the paper storage container 52 is sent to the registration roll 40, and the transferred paper 28 and the photosensitive member are synchronized with image formation performed by the registration roll 40 in the image forming unit 14. The developer image is transferred to the supplied paper by the transfer device 28. The transferred developer image is fixed on the sheet by the fixing device 32, and the sheet on which the developer image is fixed is discharged to the discharge unit 16 by the discharge roll 42.

FIG. 2 shows the photoreceptor 20, the bearing device 100, and the bearing member 200.
The photoreceptor 20 includes a photoreceptor body 21 and a shaft 46. The shaft 46 is used as a rotating shaft, and the center of the shaft 46 is a central shaft 48. The shaft 46 is attached to the photoconductor main body 21 so as to protrude from both ends in the longitudinal direction of the photoconductor main body 21. A drive source 250 made of a motor is connected to the photoreceptor 20 via, for example, a drive transmission mechanism (not shown) made of a gear train, for example, and the drive is transmitted from the drive source 250 to the photosensitive member 20. The photoconductor 20 rotates around the central shaft 48 as a unit with the photoconductor body 21 and the shaft 46.

  The bearing member 200 is made of a sliding bearing made of, for example, a resin, the outer peripheral side is fixed to the right side plate of the image forming structure main body 36, and the shaft 46 is rotatably inserted into the inner peripheral surface. The bearing device 100 is fixed to the left side plate of the image forming structure main body 36 and supports the shaft 46 rotatably.

FIG. 3 is a perspective view showing the bearing device 100.
As shown in FIG. 3, the bearing device 100 includes a rotating sleeve 102, a fixed sleeve 150, and a cover member 180. The rotating sleeve 102 is used as a first bearing portion, the fixed sleeve 150 is used as a second bearing portion, and the cover member 180 is used as a pressing means and also as an urging member. ing.

  4 is a cross-sectional view showing the bearing device 100, FIG. 5 is a perspective view showing the rotating sleeve 102, FIG. 6 is a perspective view showing the fixed sleeve 150, and FIG. 7 is a perspective view showing the cover member 180. It is.

  As shown in FIGS. 4 and 5, the rotating sleeve 102 is fixed to the shaft 46 at least in the rotational direction of the shaft 46. In this embodiment, the rotating sleeve 102 is fixed to the shaft 46 also in the longitudinal direction of the shaft 46 (the direction of the central shaft 48), but the rotating sleeve 102 is fixed to the shaft 46 at least in the rotating direction of the shaft 46. What is necessary is just to be able to move so that it may slide in the longitudinal direction of the axis | shaft 46.

  The rotating sleeve 102 has a pressed surface 104 that is a surface substantially perpendicular to the central axis 48 on the photosensitive member 20 side, and has a tapered surface 106 on the fixed sleeve 150 side. The pressed surface 104 is a part with which the cover member 180 comes into contact, and at least a part of the cover member 180 comes into contact with the pressed surface 104. A first convex portion 110 and a second convex portion 112 are formed on the tapered surface 106. The first convex portion 110 and the second convex portion 112 are used as contact portions that come into contact with the fixed sleeve 150, respectively.

  The first protrusion 110 is an annular protrusion centered on the central axis 48 and is in contact with the fixed sleeve 150. The second convex portion 112 is an annular protrusion having the central axis 48 as the center like the first convex portion 110, and is formed outside the first convex portion 110 with respect to the central axis 48. Similarly to the first convex portion 110, the fixed sleeve 150 is in contact with the first convex portion 110. Further, the rotating sleeve 102 is formed with a through hole 120 having a circle passing through the central axis 48 as a cross-sectional shape, and the shaft 46 of the photosensitive member 20 is inserted into the through hole 120, and the fit is an interference fit. Yes. For this reason, the rotating sleeve 102 rotates together with the photosensitive member 20 and the shaft 46.

  As shown in FIGS. 4 and 6, the fixing sleeve 150 is fixed to the image forming structure main body 36 at least in the rotational direction of the shaft 46. In this embodiment, the fixing sleeve 150 is fixed to the image forming structure body 36 in the longitudinal direction of the shaft 46, but the fixing sleeve 150 is fixed to the image forming structure body 36 at least in the rotation direction of the shaft 46. The image forming structure main body 36 may be movable so as to slide in the longitudinal direction.

The fixed sleeve 150 has a tapered surface 152 and an outer surface 154.
The outer surface 154 is a cylindrical surface centered on the central axis 48, and the bearing device 100 is configured so that the outer surface 154 is inserted into a through hole formed in the image forming structure body 36. 36 is fixed. The fit between the outer surface 154 and the image forming structure body 36 is an interference fit.

  The tapered surface 152 forms a part of a conical surface having a central axis 48 that is the center of the shaft 46 as a center line. That is, the tapered surface 106 is a part of a conical side surface whose apex is located on the central axis 48. Further, the first convex portion 110 and the second convex portion 112 are in contact with the tapered surface 152. That is, a part of the tapered surface 152 is used as a contact portion that contacts the rotating sleeve 102. In this embodiment, the entire tapered surface 152 is a part of a conical surface having the central axis 48 that is the center of the shaft 46 as a center line. However, the tapered surface 152 has at least the first convex portion 110. The contact portion that contacts and the contact portion that the second convex portion 112 contacts may be a part of a conical surface having the center axis 48 that is the center of the shaft 46 as a center line.

  Further, for example, two assembly holes 156 are formed in the fixed sleeve 150. The assembly hole 156 is used for assembling the cover member 180 to the fixed sleeve 150, and is formed so as to penetrate from the center shaft 48 side to the outer surface 154 side, for example. Further, the two assembly holes 156 are formed at positions symmetrical to each other with respect to the central axis 48. Further, a through hole 158 is formed in the fixed sleeve 150 so that a portion protruding from the rotating sleeve 102 of the shaft 46 to the opposite side of the photoreceptor 20 passes therethrough.

  As shown in FIGS. 4 and 7, the cover member 180 is used as a pressing unit that presses the rotating sleeve 102 and the fixed sleeve 150 so as to contact each other in the direction of the shaft 46 (longitudinal direction of the shaft 46). At the same time, it is assembled to the fixed sleeve 150 and used as a biasing member for biasing the rotating sleeve 102 in the direction of the fixed sleeve 150. Part 190.

  The plate portion 182 is disposed substantially perpendicular to the central axis 48, and a through hole 184 through which the shaft 46 of the photoreceptor 20 passes is formed in the plate portion 182. The mounting projections 186 are used as mounting portions to be mounted on the fixed sleeve 150, and two plate projections 186 are provided corresponding to the assembly holes 156 so as to protrude toward the fixed sleeve 150. ing. The cover member 180 is mounted and assembled to the fixed sleeve 150 so that the two mounting projections 186 and 186 are inserted into the assembly holes 156 and 156, respectively.

  The leaf spring portion 190 is integrated with the mounting projection 186 and is used as an elastic portion that comes into contact with the rotating sleeve 102 and elastically deforms away from the rotating sleeve 102, and each is formed integrally with the plate portion 182. The leaf springs 190 adjacent to each other are arranged so that the angles with respect to the central axis 48 are equal. Further, each of the leaf spring portions 190 is separated from the plate portion 182 by a U-shaped notch 188 formed in the plate portion 182, and a part thereof is continuous with the plate portion 182. Further, contact protrusions 192 are formed at positions on the opposite side of the leaf spring portion 190 from, for example, a position continuous with the leaf portion 182.

  The contact protrusion 192 is a protrusion formed to protrude toward the rotating sleeve 102, and comes into contact with the pressed surface 104 of the rotating sleeve 102 when the cover member 180 is assembled to the fixed sleeve 150. At this time, when the contact protrusion 192 contacts the pressed surface 104, each of the leaf spring portions 190 is elastically deformed in the opposite direction to the rotating sleeve 102. For this reason, the rotating sleeve 102 is biased toward the fixed sleeve 150 and pressed against the fixed sleeve 150 by receiving a force from the leaf spring portion 190.

  The bearing device 100 includes a lubricant holding chamber 196 that is formed between the rotating sleeve 102 and the fixed sleeve 150 and is used as a holding portion that holds the lubricant. The lubricant holding chamber 196 is formed between the first convex portion 110 and the second convex portion 112, and includes the first convex portion 110, the second convex portion 112, the tapered surface 106, and the tapered surface 152. Consists of enclosed space. The lubricant holding chamber 196 holds the lubricant G used to reduce friction between the rotating sleeve 102 and the fixed sleeve 150. As the lubricant G, for example, paste grease is used.

  The rotary sleeve 102 and the fixed sleeve 150 are made of different materials. More specifically, the rotary sleeve 102 is made of polycarbonate, and the fixed sleeve 150 is made of polyacetal. Instead of using the rotating sleeve 102 made of polycarbonate and the fixed sleeve 150 made of polyacetal, the rotating sleeve 102 made of polycaracetal and the fixed sleeve 150 made of polycarbonate may be used. The rotating sleeve 102 and the fixed sleeve 150 do not necessarily need to be made of different materials. The contact portion that contacts at least the fixed sleeve 150 of the rotary sleeve 102 and the contact portion that contacts at least the rotary sleeve 102 of the fixed sleeve 150. It is sufficient to use different materials.

  The rotating sleeve 102 and the fixing sleeve 150 may be made of different materials. Instead of rotating the rotating sleeve 102 and the fixing sleeve 150 from polycarbonate and the other from the polyacetal, the rotating sleeve 102 and the fixing sleeve 150 are rotated. One of the sleeve 102 and the fixed sleeve 150 is made of any one of polyacetal resin, polyamide resin, polyester resin such as polybutylene terephthalate resin, polyolefin resin such as polyethylene resin and polypropylene resin, polycarbonate resin and fluororesin, The other of the rotation sleeve 102 and the fixed sleeve 150 may be made of another material selected from the above-described material group.

FIG. 8 shows a modification of the cover member 180 used in the first embodiment of the present invention.
In the first embodiment described above, each of the leaf spring portions 190 is formed so as to be separated from the plate portion 182 by a U-shaped notch 188 formed in the plate portion 182. On the other hand, in this modified example, the notch 188a and the notch 188b formed on the plate portion 182 on the concentric circle with the center axis 48 as the center so that the angles from the center axis 48 are substantially equal. Are formed, and the four regions formed between the notch 188a and the notch 188b are the leaf spring portions 190, respectively. Further, each of the contact protrusions 192 is formed at a substantially central portion of the leaf spring portion 190.

FIG. 9 shows a bearing device 100 included in the image forming apparatus 10 according to the second exemplary embodiment of the present invention.
In the first embodiment described above, the first convex portion 110 and the second convex portion 112 are formed on the tapered surface 106 of the rotating sleeve 102, whereas in the second embodiment, The first convex portion 160 and the second convex portion 162 are formed on the tapered surface 152 of the fixed sleeve 150. A lubricant holding chamber 196 is formed between the first convex portion 160 and the second convex portion 162. The lubricant holding chamber 196 includes a space surrounded by the first convex portion 160, the second convex portion 162, the tapered surface 106, and the tapered surface 152. The lubricant holding chamber 196 includes the first embodiment. The lubricant G is retained in the same manner as in FIG.

  In the second embodiment, at least a portion of the tapered surface 106 that contacts the first protrusion 110 and a portion that contacts the second protrusion 162 are centered on the central axis 48 that is the center of the shaft 46. Part of the conical surface. In addition, about the same part as 1st Embodiment, the same number is attached | subjected to FIG. 9, and description is abbreviate | omitted.

FIG. 10 shows a bearing device 100 included in the image forming apparatus 10 according to the third exemplary embodiment of the present invention.
In the first embodiment and the first embodiment described above, the bearing device 100 has the rotating sleeve 102, and the shaft 46 of the photosensitive member 20 is attached to the rotating sleeve 102. On the other hand, in the third embodiment, the shaft 46 protruding from the right end of the photoreceptor 20 forms a part of the bearing device 100 and is supported so as to be directly rotatable without any other member. Has been. That is, in the third embodiment, the shaft 46 is used as a rotating shaft and is used as a first bearing portion fixed to the rotating shaft.

  Further, in the first embodiment and the second embodiment described above, a plurality of convex portions including the first convex portion 110 and the second convex portion 112 are formed. In the third embodiment, one convex portion is formed. That is, the tapered surface 130 is formed on the shaft 46, and one convex portion 132 is formed on the tapered surface 130.

  Further, in the first embodiment and the second embodiment described above, the bearing device 100 includes the fixing sleeve 150, the tapered surface 152 is formed on the fixing sleeve 150, and the fixing sleeve 150 is the image forming structure. It was attached to the main body 36. On the other hand, in the third embodiment, a part of the image forming structure body 36 forms a part of the bearing device 100, and the image forming structure body 36 is formed with a tapered surface 170. In other words, in the third embodiment, the image forming structure main body 36 is used as a support portion that supports the shaft 46 and also as a second bearing portion that is fixed to the support portion.

  In the first embodiment and the second embodiment described above, the rotating sleeve 102 is pressed against the fixed sleeve 150 by the cover member 180 assembled to the fixed sleeve 150. In contrast, in the third embodiment, the photoconductor 20 is pressed against the right side surface of the image forming structure main body 36 by the pressing member 172. The pressing member 172 is made of an elastic body such as a coil spring, for example, and is attached to the left side portion of the photoconductor 20, for example.

  As described above, the present invention provides an image of a copier, a facsimile machine, a copier, etc., which has a bearing device, a rotating body such as a drum-shaped photoconductor, and a bearing device that supports the shaft of the rotating body. It can be applied to a forming apparatus or the like.

1 is a left side view illustrating an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a state in which the photosensitive drum is supported in the image forming apparatus according to the first embodiment of the present invention, and showing a cross section taken along line AA in FIG. 1. The bearing which concerns on the 1st Embodiment of this invention is shown, Fig.3 (a) is a perspective view from the left rear, FIG.3 (b) is a perspective view from the right front. FIG. 2 is a cross-sectional view showing the bearing according to the first embodiment of the present invention and enlarging a cross section taken along line AA in FIG. 1. It is a perspective view which shows the casing member which the bearing which concerns on the 1st Embodiment of this invention has. It is a perspective view which shows the rotating member which the bearing which concerns on the 1st Embodiment of this invention has. It is a perspective view which shows the press member which the bearing which concerns on the 1st Embodiment of this invention has. It is a perspective view which shows the modification of the press member which the bearing which concerns on the 1st Embodiment of this invention has. It is sectional drawing which shows the bearing which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the bearing which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 14 Image forming part 20 Photoconductor 46 Axis 48 Center axis 100 Bearing apparatus 102 Rotating sleeve 106 Tapered surface 110 First convex part 112 Second convex part 120 Through-hole 130 Tapered surface 132 Convex Portion 150 Fixed sleeve 152 Tapered surface 156 Assembly hole 158 Through hole 160 First convex portion 162 Second convex portion 170 Tapered surface 172 Press member 180 Cover member 182 Plate portion 18 Mounting projection 190 Plate spring portion 196 Lubricant holding chamber G Lubricant

Claims (8)

A first bearing portion fixed to the rotating shaft at least in the rotational direction of the shaft;
A second bearing portion fixed at least in the rotational direction of the shaft to a support portion supporting the shaft;
A pressing means for pressing the first bearing portion and the second bearing portion so as to contact each other in the axial direction;
Have
The first bearing portion and the second bearing portion have contact portions that contact each other, and at least one of the contact portions forms a part of a conical surface with the center of the shaft as a center line. .   The bearing device according to claim 1, wherein the pressing unit includes a biasing member that is assembled to the second bearing member and biases the first bearing portion toward the second bearing portion. The biasing member is
A mounting portion mounted on the second bearing portion;
An elastic part that is integral with the mounting part and elastically deforms in a direction away from the first bearing part;
The bearing device according to claim 2.   The bearing device according to claim 1, further comprising a holding portion that is formed between the second bearing portion and the first bearing portion and holds a lubricant. The first bearing portion and the second bearing portion have at least two contact portions, and one of these contact portions is provided on one of the first bearing portion and the second bearing portion. It is composed of an annular first convex portion formed, and the other one of these contact portions is composed of an annular second convex portion formed outside the first convex portion,
The bearing device according to claim 4, wherein the holding portion is formed between the first convex portion and the second convex portion.   The bearing device according to claim 1, wherein the first bearing portion and the second bearing portion are made of materials having at least the contact portions different from each other.   At least one of the first bearing part and the second bearing part is made of polycarbonate, and at least one of the first bearing part and the second bearing part is at least the contact. The bearing device according to claim 6, wherein the portion is made of polyacetal. A rotating body that rotates during image formation;
A bearing device for supporting the shaft of the rotating body;
Have
The bearing device includes:
A first bearing portion fixed to the shaft at least in the rotational direction of the shaft;
A second bearing portion fixed at least in the rotational direction of the shaft to a support portion supporting the shaft;
A pressing means for pressing the first bearing portion and the second bearing portion so as to contact each other in the axial direction;
Have
The first bearing portion and the second bearing portion have contact portions that contact each other, and at least one of the contact portions forms an image of a part of a conical surface with the center of the shaft as a center line. apparatus.

Images