JP4350082B2 - Drum unit - Google Patents

Description

The present invention relates to sensing the light Doramuyuni' door.

  In electrophotographic copying machines and printers, a cylindrical photosensitive drum is rotated to form an electrostatic latent image on its running surface, and toner is attached by development to form a toner image, which is transferred. An image is obtained by transferring and fixing on a material.

  In such an image forming apparatus, jitter and image unevenness occur in the output image when a speed fluctuation occurs in the rotating photosensitive drum due to some influence. This is particularly noticeable in digital electrophotographic technology in which writing on the surface of the photosensitive drum is performed by scanning with a semiconductor laser, and fluctuations in the rotational speed of the photosensitive drum are caused by speed fluctuations in the sub scanning direction of the writing system. As a result, a slight shift occurs in the interval between the write lines, which causes a significant deterioration in image quality.

  Various factors can be cited as factors that deteriorate the driving accuracy of the photosensitive drum. As for the photosensitive member drive system that is responsible for driving the photosensitive member itself, there are main motor drive unevenness, motor shaft flutter, characteristic frequency components inherent in motor-specific structural problems, and the like. With respect to the gear train constituting the drive system, there is a gear one-tooth or one-turn fluctuation due to gear accuracy, in particular, tooth profile accuracy, tooth trace accuracy, and gear flutter accuracy (such as eccentricity). Even when the drive system is composed of motors, gears, etc., the positional relationship between the motor shaft and gear shaft, especially the distance between the shafts, directly affects the backlash amount of the gear. It is a factor that generates vibration at the meshing part.

  Further, the driving accuracy of the photosensitive drum is affected not only by the driving system of the photosensitive drum but also when the peripheral units are operated. That is, since the developing unit, the cleaning unit, the transfer unit and the transport unit, or the transfer / transport unit in which these units are integrated also include the movable portion, vibration is always generated. These vibrations are transmitted to the photosensitive drum through the photosensitive drum unit or the frame of the photosensitive drum, and the main body skeleton, and fluctuations in the frequency of each vibration are transmitted to the photosensitive drum or the driving system of the photosensitive drum. The driving accuracy of the photosensitive drum is deteriorated.

  Therefore, in order to prevent such a decrease in image quality, Patent Document 1 discloses, as shown in FIG. 10, a photosensitive drum 10, a casing 30 that houses the photosensitive drum 10, and a drive to the photosensitive drum 10. And a drive unit (not shown) that transmits force, and is formed on the flange 101 on the side surface of the photosensitive drum 10 from two layers: a viscoelastic layer 142 and a surface layer 141 that protects the viscoelastic layer 142. It is disclosed that the ring-shaped sliding member 140 is rubbed against the inner surface of the casing 30 facing the sliding member 140 by driving the photosensitive drum 10.

According to this, a load due to friction of the sliding member 140 is generated with respect to the rotation of the photosensitive drum 10 to increase the torque value, and as a result, the sensitivity to the speed variation of the rotation of the photosensitive drum 10 becomes dull. Is eliminated, and the image is rotated at a stable speed, and a high-quality image is obtained.
JP 2002-357987 (summary, FIG. 9)

  However, in the above-described conventional configuration, when the hardness or thickness of the viscoelastic layer 142 is increased in order to obtain a high torque (for example, 2 kgf · cm or more), the compression is caused by individual differences between the length of the photosensitive drum 10 and the width of the casing 30. The rate changes and the torque value is not stable. Further, the surface layer 141 is made of a resin sheet having a thickness of 10 to 100 μm and having a small coefficient of friction, and is slippery on the inner surface of the casing 30, so that the torque value is as expected even if the thickness of the viscoelastic layer 142 is slightly increased. It was difficult to control the torque value.

  Therefore, as a measure for solving such a problem, the present inventor, as shown in FIGS. 11 and 12, prior to the present application, ring-shaped sliding members are provided on the flanges 101 and 102 on the side surface of the photosensitive drum 10. 153, and a stationary member 150 formed of two layers of a viscoelastic layer 152 and a surface layer 151 protecting the viscoelastic layer 152 on the inner surface of the casing 30 facing the side surface of the photosensitive drum 10, The sliding member 153 has a raised surface, and is made of a material (artificial leather or the like) having a larger friction coefficient than the surface layer 151 of the stationary member 150, and the sliding member 153 is driven by the photosensitive drum 10. It has been proposed that the surface layer 151 of the stationary member 150 is rubbed (Japanese Patent Application No. 2004-155433).

  According to this, a stable high torque value can be obtained by sliding friction between the sliding member 153 and the surface layer 151 of the stationary member 150 without increasing the hardness and thickness of the viscoelastic layer 152. It is driven and rotated at a constant peripheral speed, so that a higher quality image can be obtained.

  The stationary member 150 as described above is provided on the inner surfaces on both sides of the casing 30. Further, since the torque is obtained by the repulsion of the compressed viscoelastic layer 152, as shown in FIG. 13, the overall length of the photosensitive drum 10 is the distance between the stationary members 150 and 150. It is set to be larger.

  Then, when a serviceman or an assembly worker attaches the photosensitive drum 10 to the casing 30, even if the photosensitive drum 10 is held horizontally and put in parallel as indicated by an arrow H in FIG. As shown in FIG. 14, the photosensitive drum 10 is held at an angle, and one side surface of the photosensitive drum 10 is pressed against one stationary member 150 as shown by an arrow S as shown in FIG. Thus, the other side is gradually pushed in.

  At that time, if the pressure contact force applied to the photosensitive drum 10 is insufficient, the edge portion of the other side surface of the photosensitive drum 10 comes into contact with the upper part of the peripheral surface of the other stationary member 150, and an excessive force is applied. The attachment between the elastic layer 152 and the casing 30 and the attachment between the surface layer 151 and the viscoelastic layer 152 may be peeled off, and the attachment workability is extremely poor.

The present invention has been made in view of the above-described conventional problems. The photosensitive drum can be easily attached, and the fluctuation in the speed of the photosensitive drum can be efficiently reduced. it is intended to provide a Doramuyuni' bets that can be driven with a steady rotation speed.

In order to achieve the above object, a drum unit of the present invention is a drum unit having a photosensitive drum and a casing for housing the photosensitive drum, and the photosensitive drum is attached to a cylindrical body and one end of the cylindrical body. The first flange and the second flange attached to the other end, the first flange has a hole that penetrates in the axial direction, and the first member is fixed to the outer surface, A cavity is formed in the end surface portion of the second flange and provided with a shaft portion, a second member is fixed to the inner surface of the recess, and the third member is fixed and penetrates in the axial direction. Is inserted into the recess so that the fixed surface of the third member is on the inside, and the shaft portion of the second flange is inserted into the cavity of the holder. The casing has one side The wall has a rotary shaft insertion portion and the fourth member is fixed inside, the cylindrical body is attached to the other side wall, the photosensitive drum is inserted into the casing, and is fixed to the first flange. The first member is brought into contact with the fourth member fixed to one side wall surface of the casing, and the holder and the cylindrical body fitted into the recess of the second flange The photosensitive drum is press-fitted, and a rotating shaft is inserted in the axial direction from the outside of the casing into the hole portion of the first flange of the photosensitive drum and the shaft portion of the second flange. Any one of the first member and the fourth member includes a first viscoelastic layer, and any one of the second member and the third member includes a second viscoelastic layer. characterized by comprising.

A drum unit having a photosensitive drum and a casing for housing the photosensitive drum, wherein the photosensitive drum is attached to a cylindrical body, a first flange attached to one end of the cylindrical body, and the other end; The first flange is formed at the end surface portion of the first flange and the first shaft portion is provided, and a first shaft portion is provided on the back surface of the first recess. The first holder that fixes the member, the second member is fixed, and the first cavity that penetrates in the axial direction is formed, so that the fixed surface of the second member is inside. The first shaft portion of the first flange is inserted into the first cavity of the first holder, and the first shaft portion of the first flange is inserted into the first cavity of the first holder. 2 recesses are formed and a second shaft portion is provided, and the second recess is provided on the inner surface of the second recess. The second member in which the fourth member is fixed and the second cavity formed in the axial direction is formed so that the fixed surface of the fourth member is on the inside. The second recess is fitted into the second cavity, the second shaft portion of the second flange is inserted into the second cavity of the second holder, and the casing has a first wall on one side wall. And the second cylindrical body is attached to the other side wall, the photosensitive drum is inserted into the casing, and is fitted in the first recess of the first flange. The second holder and the second cylinder fitted into the second recess of the second flange while bringing the combined first holder and the first cylinder into contact with each other The photosensitive drum is press-fitted to contact the photosensitive drum from the outside of the casing. A rotary shaft is inserted in the axial direction into the first shaft portion of the first flange and the second shaft portion of the second flange, and the first member has the first viscoelastic layer. And the third member includes a second viscoelastic layer, or the second member includes a first viscoelastic layer and the fourth member includes a second viscoelastic layer. And

Further , since the tapered portion is provided at the contact portion, the press-fitting of the photosensitive drum can be performed more easily.

According to the present invention, when worn on the casing of the photosensitive drum, the photosensitive light drum can be easily pressed. Moreover, sensitive light drum is eliminated speed variations, is rotated at a stable speed. Therefore, the photosensitive drum is always driven and rotated at a constant peripheral speed even when subjected to vibration inherent in the driving system and fluctuations in the load during image formation, and as a result, particularly the image generated in the sub-scanning direction of the writing system. Density unevenness and color unevenness are remarkably improved, and a high-quality image can be recorded.

  The best mode for carrying out the present invention will be described below with reference to the drawings. First, the configuration and operation of the image forming apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus of the present invention, and FIG. 2 is a perspective view showing drive formation of a photosensitive drum in a drum unit.

  In FIG. 1, reference numeral 10 denotes a photosensitive drum as an image bearing member, which is an OPC photosensitive member coated on a drum, which is grounded and rotated clockwise. In FIG. 1, reference numeral 12 denotes a scorotron charger, which gives a uniform charge of VH to the circumferential surface of the photosensitive drum 10 by a corona discharge using a grid held by VG and a corona discharge wire. Prior to the charging by the scorotron charger 12, in order to eliminate the history of the photoconductor up to the previous print, exposure by the PCL 11 using a light emitting diode or the like is performed to neutralize the peripheral surface of the photoconductor.

  As shown in FIG. 2, the photosensitive drum 10 is attached to and detached from the apparatus main body as a drum unit that is housed in a casing 30 together with the charger 12, the transfer roller 18, and the cleaning device 22. The photosensitive drum 10 has an integral rotating shaft 103 supported on both side walls of the casing 30 by bearings 31 (see FIG. 4). When the drum unit is mounted, a helical gear G using the motor m shown in FIG. It is connected and rotated by a predetermined speed in the clockwise direction while receiving thrust in the axial direction.

  After the photoreceptor is uniformly charged, the image exposure unit 13 performs image exposure based on the image signal. The image exposure means 13 is scanned by a polygon mirror 131 rotating with a laser diode (not shown) as an emission light source, an fθ lens, etc., and the optical path is bent by a reflection mirror 132, and the photosensitive drum 10 is rotated (sub-scanning). A latent image is formed. In this embodiment, the character portion is exposed to form an inverted latent image in which the character portion has a lower potential VL.

  At the periphery of the photosensitive drum 10, there are provided developing devices 14 each containing a developer composed of toner such as yellow (Y), magenta (M), cyan (C), and black (K) and a carrier. The development of the first color is performed by a developing sleeve 141 that contains a magnet and rotates while holding the developer. Subsequently, an image forming process similar to that for the first color is performed for the second color, the third color, and the fourth color, and a four-color visible image is formed on the circumferential surface of the photosensitive drum 10. At this time, the neutralization by the PCL 11 performed in the first color image forming process is not performed because the toner adhering to the image portion of the first color scatters due to a rapid decrease in the surrounding potential.

  On the other hand, the recording paper P carried out from a paper feed cassette (not shown) is temporarily stopped and fed to the transfer area by the rotation operation of the paper feed roller 17 when the transfer timing is ready.

  In the transfer area, the transfer roller 18 is pressed against the peripheral surface of the photosensitive drum 10 in synchronism with the transfer timing, and the fed recording paper P is sandwiched to transfer the multicolor images all at once.

  Next, the recording paper P is neutralized by the separation brush 19 brought into a pressure contact state almost simultaneously, separated by the peripheral surface of the photosensitive drum 10 and conveyed to the fixing device 20, and the toner is heated and pressed by the heat roller 201 and the pressure roller 202. Are then discharged to the outside of the apparatus via the paper discharge roller 21. The transfer roller 18 and the separation brush 19 are retracted away from the peripheral surface of the photosensitive drum 10 after the recording paper P has passed to prepare for the next toner image formation.

  On the other hand, the photosensitive drum 10 from which the recording paper P has been separated removes and cleans residual toner by the pressure contact of the blade 221 of the cleaning device 22, and again undergoes charge removal by the PCL 11 and charging by the charger 12 for the next image forming process. enter. The blade 221 moves immediately after cleaning the photoreceptor surface and retracts from the circumferential surface of the photoreceptor drum 10.

  The drum unit according to the present invention will be described with some embodiments.

  First, a first embodiment of a drum unit according to the present invention will be described. 3 is a perspective view showing a support structure of the side surface on the driving side of the photosensitive drum 10, and FIG. 4 is a cross-sectional view of the support structure on both side surfaces of the photosensitive drum 10 as viewed from the direction A in FIG. 5 is a cross-sectional view taken along the line yy of FIG.

  The photosensitive drum 10 includes a cylindrical body 100, a pair of flanges 101 and 102 attached to both ends of the cylindrical body 100, and a rotating shaft 103 fixed to the flanges 101 and 102.

  A ring-shaped sliding member 43 is fixed to the outer surface of the flange 101 that supports one end of the cylindrical body 100, and a ring-shaped stationary member 40 is fixed to the opposing surface of the casing 30. A donut-shaped recess 102a is formed in the end surface portion of the flange 102 that supports the other end of the cylinder pair 100, so that a cylindrical shaft portion 102b that is integrally formed with the flange 102 is provided at the center thereof. . The inner surface of the recess 102a is parallel to the end surface of the flange 102, and the ring-shaped sliding member 50 is fixed thereto. Further, the end of the flange 102 is one step higher than the portion inserted into the photosensitive drum 10, and the helical gear G is integrally formed around the end.

  Reference numeral 54 denotes a holder fitted into the recess 102a. The holder 54 includes a donut-shaped disc portion 54a, a cylindrical portion 54b integrally formed on one end surface of the disc portion 54a, and a pair of parallel flat plate portions 54c integrally formed on a side surface portion of the cylindrical portion 54b. , 54c. The flat plate portion 54c is set to have an axial dimension longer than that of the cylindrical portion 54b so that the tip end portion extends from the end face of the cylindrical portion 54b and faces each other. And the ring-shaped stationary member 53 is being fixed to the other end surface of the disc part 54a. The holder 54 configured in this manner is fitted into the recess 102a so that the fixed surface of the stationary member 53 is on the inside. At this time, the shaft portion 102b of the flange 102 is inserted into a cavity that passes through the center portion of the disk portion 54a and the cylindrical portion 54b of the holder 54 in the axial direction, so that the holder 54 has the stationary member 53, the sliding member 50, and Can be slid in the recess 102a in the axial direction.

  Reference numeral 56 denotes a cylinder attached through the side wall of the casing 30. The cylindrical body 56 includes a large-diameter portion 56 a that is fixed to the casing 30 and a small-diameter portion 56 b that protrudes inside the casing 30. A bearing 31 that rotatably supports the rotating shaft 103 is fixed in the large-diameter portion 56a. As shown in FIG. 5, the small-diameter portion 56b is formed in a cross-sectional oval shape so as to have a pair of parallel flat portions 56c and 56c on the side surface. Here, the distance L between the pair of flat portions 56c and 56c of the cylindrical body 56 is set to be substantially equal to the distance between the pair of flat plate portions 54c and 54c of the holder 54, and the photosensitive drum 10 is placed in the casing. 3 and 5, the flat plate portions 54c of the holder 54 are engaged with the flat surface portions 56c of the cylindrical body 56, respectively, so that the movement of the holder 54 in the rotational direction is restricted, as shown in FIGS. It has become.

  Next, a procedure for mounting the photosensitive drum 10 to the casing 30 in the drum unit of this embodiment will be described with reference to FIG. 6A is a cross-sectional view of the photosensitive drum 10 before the photosensitive drum 10 is mounted on the casing 30, and FIG. 6B shows the mounting direction of the photosensitive drum 10 and the casing 30 during mounting (b) and after mounting (c). On the other hand, it is a plan view seen from the side.

  First, as shown by an arrow in FIG. 6A, the holder 54 is fitted into the recess 102a so that the fixed surface of the stationary member 53 is inside. At this time, the shaft portion 102b of the flange 102 is inserted into a cavity that penetrates the center portion of the disc portion 54a and the cylindrical portion 54b of the holder 54 in the axial direction. As a result, the holder 54 can slide in the recess 102a in the axial direction with the stationary member 53 and the sliding member 50 facing each other.

  Next, as shown in FIG. 6 (b), the photosensitive drum 10 tilted so that one end on the flange 101 side is low and the other end on the flange 102 side is high is inserted into the casing 30, and the flange 101 is inserted. While pressing the one end side of the photosensitive drum 10 so that the upper part of the sliding member 43 fixed to the upper surface of the surface layer 41 of the stationary member 40 fixed to the inner surface of one side wall of the casing 30 is pressed, The other end side of the photosensitive drum 10 is pushed down. At this time, it is necessary to align the position of the holder 54 in the rotational direction so that each flat plate portion 54 c of the holder 54 can be engaged with each flat surface portion 56 c of the cylindrical body 56. Thus, the photosensitive drum 10 can be easily press-fitted while the holder 54 and the cylindrical body 56 are brought into contact with each other and the viscoelastic layer 52 of the sliding member 50 is compressed (see FIG. 6C).

  In addition, as shown by a circle enclosed by a broken line in the same figure, the respective contact portions of the holder 54 and the cylindrical body 56 (the lower end of the cylindrical portion 54b of the holder 54 and the upper end of the small diameter portion 56b of the cylindrical body 56, or the holder) If the tapered portions 54d and 56d are provided at the lower end of the flat plate portion 54c and the upper end of the large-diameter portion 56a of the cylindrical body 56, the press-fitting of the photosensitive drum 10 may be facilitated. .

  Finally, the rotation shaft 103 (see FIG. 2) is inserted in the axial direction from the outside of the casing 30 to the center of the bearing 31 and the flanges 101 and 102 of the photosensitive drum 10, and the rotation shaft 103 is fixed to the flanges 101 and 102. (See FIG. 3), the mounting of the photosensitive drum 10 is completed. A configuration in which the photosensitive drum 10 is rotated around the rotation shaft 103 without transmitting the rotation of the helical gear G integrated with the flange 102 to the rotation shaft 103 without fixing the rotation shaft 103 to the flanges 101 and 102. It does not matter.

  As a result, each flat plate portion 54c of the holder 54 engages with each flat surface portion 56c of the cylindrical body 56, and the movement of the holder 54 in the rotation direction can be restricted. Further, the surface layer 41 of the stationary member 40 and the sliding member 43 are in pressure contact with each other, and the surface layer 51 of the sliding member 50 and the stationary member 53 are in pressure contact with each other, giving a load to the rotational drive of the photosensitive drum 10. it can.

  With this configuration, the sliding surface of the stationary member 40 on the casing 30 side that faces the surface of the sliding member 43 fixed to the flange 101 by the thrust in the direction indicated by the arrow in FIG. In addition, the surface of the sliding member 50 fixed to the flange 102 is pressed against the sliding surface of the stationary member 53 fixed to the holder 54, and is slid along with the rotation of the photosensitive drum 10. Yes.

  The stationary member 40 includes a surface layer 41 in contact with the sliding member 43 and a viscoelastic layer 42 fixed to the casing 30 side. Also, the sliding member 50 has a similar laminated structure, and is composed of a surface layer 51 in contact with the stationary member 53 and a viscoelastic layer 52 fixed to the flange 102 side.

  The surface layers 41 and 51 are for protecting the viscoelastic layers 42 and 52 and for ensuring the slipperiness of the surface. When the surface of the sliding member 43 or the stationary member 53 is rubbed, the surface layers 41 and 51 are braked. In order to drive the photosensitive drum 10 smoothly, a material having an appropriate hardness and friction coefficient is used.

  The viscoelastic layers 42 and 52 are for absorbing the speed fluctuation generated when the photosensitive drum 10 is driven by the viscoelasticity and reducing the absolute value of the speed fluctuation. The polymer member has both viscosity and elasticity. Is used. When the thickness of the viscoelastic layer 42 is increased, the force for pressing the flange 101 of the photosensitive drum 10 is increased. On the other hand, when the thickness of the viscoelastic layer 52 is increased, the force for pressing the side wall of the casing 30 via the holder 54. When the photosensitive drum 10 requires a large torque to drive the photoconductor drum 10 and a load is applied to the motor m. On the other hand, when the thickness of the viscoelastic layer 42 is small and the pressing force is small, the above-described reduction in speed fluctuation is small. The effect cannot be expected. For this reason, the thickness of the viscoelastic layers 42 and 52 is determined after taking these into consideration.

  Further, since the space inside the flange 102 can be secured relatively freely, as shown in FIG. 7, by preparing a plurality of types of flanges 102 having different depth dimensions of the recess 102a, the axial position of the surface layer 51 can be obtained. Without changing the thickness, the thickness of the viscoelastic layer 52 can be increased, and torque adjustment for rotational driving of the photosensitive drum 10 can be easily performed. Further, by providing the sliding member 50 in the recess 102 a in this way, even if the sliding member 50 is compressed by the holder 54, the adhesive such as an adhesive that adheres the viscoelastic layer 52 and the surface layer 51 is used. The component does not protrude and stain the flange 102 and the photosensitive drum 10.

  Specifically, examples of the material of the surface layers 41 and 51 include a wear-resistant resin sheet having a small friction coefficient, for example, Teflon (registered trademark) felt, PET film, and the like. Fixed to the layers 42 and 52. In particular, Teflon (registered trademark) felt is excellent in adhesive strength to the viscoelastic layers 42 and 52.

  Examples of the material of the viscoelastic layers 42 and 52 include foamed resin materials such as urethane and silicon, and are fixed to the casing 30 or the flange 102 via a double-sided tape or an adhesive.

  Moreover, as a material of the said sliding member 43 or the stationary member 53, while having a raised surface, it has a friction coefficient more than the surface layer 41 of the said stationary member 40 or the surface layer 51 of the said sliding member 50. A large material (for example, a nonwoven fabric (felt) having a raised surface or a synthetic leather having a raised surface) can be used, and is fixed to the flange 101 or the holder 54 via a double-sided tape or an adhesive. When comparing a nonwoven fabric having a raised surface with a synthetic leather having a raised surface, it was confirmed that the former is more preferable because the woven fibers are consumed more by friction. Further, it was confirmed that rubber, which is a representative high friction material, is unsuitable as a material for the sliding member 43 or the stationary member 53 because the adhesive strength to the flange 101 is weak.

  By using the stationary members 40 and 53 and the sliding members 43 and 50, the photosensitive drum 10 can be rotated at a stable speed because the speed fluctuation is eliminated. Therefore, the photosensitive drum 10 is always driven and rotated at a constant peripheral speed even if it receives vibrations inherent in the driving system and fluctuations in load during image formation, and as a result, an image generated particularly in the sub-scanning direction of the writing system. Density unevenness and color unevenness are remarkably improved, and a high-quality image can be recorded.

Further, to fix a ring-shaped sliding member 44 of the previous SL of the stationary member 40 and the same structure on the outer surface side of the flange 101, the ring-shaped stationary member 45 of the sliding member 43 and the same member of the casing 30 The same effect can be obtained even if the surface layer 41 is fixed to the opposing surfaces and rubbed with the stationary member 45 on the inner surface of the casing 30 as a sliding surface.

  Next, a second embodiment of the drum unit according to the present invention will be described. FIG. 8 is a cross-sectional view of the support structure on both side surfaces of the photosensitive drum 10 as viewed from the direction A in FIG. In this figure, the same parts as those of the drum unit in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, a recess 101a and a shaft portion 101b are formed in the flange 101 on one side end of the photosensitive drum 10 as well as the flange 102 on the other end of the photosensitive drum 10 in the first embodiment. The sliding member 50 is fixed to the inner surface of the recess 101a, and the holder 54 having the stationary member 53 fixed to the recess 101a is fitted. At this time, the shaft portion 101b of the flange 101 is inserted into a cavity that passes through the center portion of the disc portion 54a and the cylindrical portion 54b of the holder 54 in the axial direction, so that the holder 54 has the stationary member 53, the sliding member 50, and Can be slid in the recess 102a in the axial direction.

  Further, the same cylindrical body 56 as that of the other side wall of the casing 30 in the first embodiment is attached to one side wall of the casing 30 so as to penetrate therethrough.

  Next, a procedure for mounting the photosensitive drum 10 to the casing 30 in the drum unit of this embodiment will be described with reference to FIG. FIG. 9 is a cross-sectional view (a) of the photosensitive drum 10 before mounting the photosensitive drum 10 to the casing 30, in the mounting direction of the photosensitive drum 10 and the casing 30 during mounting (b) and after mounting (c). On the other hand, it is a plan view seen from the side.

  First, as indicated by arrows in FIG. 9A, the holders 54 and 54 are fitted into the recesses 101a and 102a so that the fixed surface of the stationary member 53 is on the inside. At this time, the shaft portions 101b and 102b of the flanges 102 are inserted into cavities penetrating through the center portions of the disk portion 54a and the cylindrical portion 54b of the holders 54 in the axial direction. As a result, the holder 54 can slide in the recess 102a in the axial direction with the stationary member 53 and the sliding member 50 facing each other.

  Next, as shown in FIG. 9B, the photosensitive drum 10 held substantially horizontally is inserted into the casing 30 and pushed down in parallel. At this time, it is necessary to align the positions of the holders 54 in the rotational direction so that the flat plate portions 54c of the holders 54 can be engaged with the flat surface portions 56c of the cylindrical bodies 56, respectively. Thus, the photosensitive drum 10 can be easily press-fitted while the holders 54 and the cylindrical bodies 56 are brought into contact with each other and the viscoelastic layer 52 of each sliding member 50 is compressed (see FIG. 9C). ).

  In addition, as surrounded by a broken-line circle in the same figure, each contact portion of each holder 54 and each cylindrical body 56 (the lower end of the cylindrical portion 54b of each holder 54 and the distal end of the small-diameter portion 56b of each cylindrical body 56) If the taper portions 54d and 56d are provided on the upper portion or the lower end of the flat plate portion 54c of each holder 54 and the upper end of the large-diameter portion 56a of each cylindrical body 56, it is easier to press-fit the photosensitive drum 10. May be able to.

  Finally, the rotation shaft 103 (see FIG. 2) is inserted in the axial direction from the outside of the casing 30 to the center of the bearing 31 and the flanges 101 and 102 of the photosensitive drum 10, and the rotation shaft 103 is fixed to the flanges 101 and 102. (See FIG. 3), the mounting of the photosensitive drum 10 is completed. A configuration in which the photosensitive drum 10 is rotated around the rotation shaft 103 without transmitting the rotation of the helical gear G integrated with the flange 102 to the rotation shaft 103 without fixing the rotation shaft 103 to the flanges 101 and 102. It does not matter.

  As a result, each flat plate portion 54c of each holder 54 engages with each flat surface portion 56c of each cylindrical body 56, and the movement of each holder 54 in the rotational direction can be restricted. Further, the surface layer 41 of each stationary member 40 and each sliding member 43 are in pressure contact with each other, and the surface layer 51 of each sliding member 50 and each stationary member 53 are in pressure contact with each other to load the rotational drive of the photosensitive drum 10. Can be given.

  With this configuration, the surfaces of the sliding members 50 and 50 fixed to the flanges 101 and 102 are fixed to the holders 54 and 54 by the thrust in the direction indicated by the arrow in FIG. By being in pressure contact with the sliding surfaces of the stationary members 53, 53, they are slid along with the rotation of the photosensitive drum 10.

  By using the stationary members 53 and 53 and the sliding members 50 and 50, the photosensitive drum 10 can be rotated at a stable speed because the speed fluctuation is eliminated. Therefore, the photosensitive drum 10 is always driven and rotated at a constant peripheral speed even if it receives vibrations inherent in the driving system and fluctuations in load during image formation, and as a result, an image generated particularly in the sub-scanning direction of the writing system. Density unevenness and color unevenness are remarkably improved, and a high-quality image can be recorded.

  Although not shown, the ring-shaped sliding member having the same configuration as that of the stationary member 53 is fixed to the inner surface of the recesses 101a and 102a of the flanges 101 and 102, and is the same member as the sliding member 50. Even if the ring-shaped sliding member is fixed to the opposing surface of the holder 54, the same effect can be obtained.

  In the present embodiment, the image forming apparatus using the photosensitive drum 10 has been described. However, the present invention uses an image using a belt-shaped photosensitive member that is circulated and conveyed between a pair of rotating rollers. The present invention can also be applied to a forming apparatus. In this case, the stationary member 40 and the sliding member 43 are provided on the side end of a sliding roller, for example, a rotating roller.

  The present invention relates to the driving of a photosensitive drum of an image forming apparatus that forms an image by a digital method using an electrophotographic method, and in particular, superimposes a single color toner image developed by arranging a plurality of developing devices around the photosensitive drum. By combining them, the image forming apparatus can form a color toner image.

1 is a cross-sectional configuration diagram of an image forming apparatus of the present invention. FIG. 3 is a perspective view showing a driving configuration of a photosensitive drum in a drum unit. These are perspective views which show the support structure of the side surface by the side of the drive of the photosensitive drum in the drum unit of 1st Embodiment. FIG. 3 is a cross-sectional view of the support structure on both side surfaces of the photosensitive drum as viewed from the direction A in FIG. FIG. 6 is a cross-sectional view taken along line yy of FIG. 4. FIG. 4 is a cross-sectional view of the photosensitive drum before mounting the photosensitive drum on the casing (a), during mounting (b), and after mounting (c), viewed from the side with respect to the mounting direction of the photosensitive drum and casing. FIG. These are principal part sectional drawings which show the relationship between the depth dimension of the recess of the flange of said photoconductor drum, and the thickness of a viscoelastic layer. These are perspective views which show the support structure of the side surface by the side of the drive of the photosensitive drum in the drum unit of 2nd Embodiment. FIG. 4 is a cross-sectional view of the photosensitive drum before mounting the photosensitive drum on the casing (a), during mounting (b), and after mounting (c), viewed from the side with respect to the mounting direction of the photosensitive drum and casing. FIG. These are principal part sectional drawings of an example of the conventional drum unit. These are principal part sectional drawings of the other example of the conventional drum unit. These are top views of the conventional drum unit. FIG. 6 is a cross-sectional view of the photosensitive drum and the casing before being mounted on the casing of the photosensitive drum in the conventional drum unit. These are the top views which looked at the photoconductive drum and casing in the middle of mounting | wearing of the said photoconductive drum from the side with respect to the mounting direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photosensitive drum 12 Charging device 13 Image exposure means 14 Developing device 17 Paper feed roller 18 Transfer roller 19 Separation brush 20 Fixing device 21 Paper discharge roller 22 Cleaning device 30 Casing 40, 45, 53 Static member 41, 51 Surface layer 42, 52 Viscoelastic layer 43, 50 Sliding member 44 Sliding member 54 Holder 54a Disk portion 54b Tube portion 54c Flat plate portion 54d Taper portion 56 Tube body 56a Large diameter portion 56b Small diameter portion 56c Plane portion 101, 102 Flange 101a, 102a Concave Location 101b, 102b Shaft portion 103 Rotating shaft 131 Polygon mirror 132 Reflecting mirror 140 Sliding member 141 Surface layer 141 Developing sleeve 142 Viscoelastic layer 150 Static member 151 Surface layer 152 Viscoelastic layer 153 Sliding member 201 Heat roller 202 Pressure roller 221 The Over de G helical gear m motor P recording paper

Claims (3)

A drum unit having a photosensitive drum and a casing for storing the photosensitive drum,
The photosensitive drum has a cylindrical body, a first flange attached to one end of the cylindrical body, and a second flange attached to the other end.
The first flange has a hole penetrating in the axial direction and the first member is fixed to the outer surface;
Forming a recess in the end face of the second flange and providing a shaft;
Fixing the second member to the inner surface of the recess;
A holder in which a third member is fixed and a cavity penetrating in the axial direction is formed,
Fitting in the recess so that the fixed surface of the third member is inside, inserting the shaft portion of the second flange into the cavity of the holder,
The casing has a rotating shaft insertion portion on one side wall and fixes the fourth member on the inside, and is attached to the other side wall through the cylinder,
The photosensitive drum is inserted into the casing, and the first member fixed to the first flange is brought into contact with the fourth member fixed to one side wall surface of the casing. Press the photoconductive drum by pressing the holder and the cylinder fitted in the recess of the second flange;
A rotating shaft is inserted in the axial direction from the outside of the casing into the hole portion of the first flange of the photosensitive drum and the shaft portion of the second flange,
Either one of the first member and the fourth member includes a first viscoelastic layer,
Either one of the second member and the third member has a second viscoelastic layer.
A drum unit characterized by that. A drum unit having a photosensitive drum and a casing for storing the photosensitive drum,
The photosensitive drum has a cylindrical body, a first flange attached to one end of the cylindrical body, and a second flange attached to the other end.
Forming a first recess in the end face of the first flange and providing a first shaft;
Fixing the first member to the inner surface of the first recess;
A first holder in which a second cavity is fixed and a first cavity penetrating in the axial direction is formed, and the first recess is arranged so that a surface to which the second member is fixed is inside. The first shaft portion of the first flange is inserted into the first cavity of the first holder,
Forming a second recess in the end face of the second flange and providing a second shaft;
Fixing a third member to the inner surface of the second recess;
A second holder in which a fourth cavity is fixed and a second cavity penetrating in the axial direction is formed, and the second recess is arranged such that the fixed surface of the fourth member is on the inside. The second shaft portion of the second flange is inserted into the second cavity of the second holder,
The casing is attached through one side wall through the first cylinder and attached through the second cylinder through the other side wall.
The photosensitive drum is inserted into the casing, the first holder fitted in the first recess of the first flange is brought into contact with the first cylindrical body, and the second cylinder Press-fitting the photosensitive drum by bringing the second holder fitted into the second recess of the flange into contact with the second cylindrical body;
A rotating shaft is inserted in the axial direction from the outside of the casing through the first shaft portion of the first flange of the photosensitive drum and the second shaft portion of the second flange,
The first member includes a first viscoelastic layer and the third member includes a second viscoelastic layer, or the second member includes a first viscoelastic layer and the fourth The member comprises a second viscoelastic layer
A drum unit characterized by that. The drum unit according to claim 1, wherein a taper portion is provided at the contact portion.

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