JP5531687B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In recent years, there has been an image forming apparatus that uses a detachable structure (process cartridge) including a photosensitive drum that is detachably mounted on a mounting portion of the apparatus main body. For example, the following is known.

  An electrophotographic image forming apparatus for detachably attaching a process cartridge to form an image on a recording medium, comprising: a. An electrophotographic photosensitive drum, a developing roller for developing a latent image formed on the electrophotographic photosensitive drum, and an apparatus main body provided in the apparatus main body when a process cartridge is attached to the apparatus main body When the apparatus main body coupling member rotates in a state of being engaged with the coupling member, a driving force for rotating the electrophotographic photosensitive drum is drawn from the apparatus main body in a state of being pulled in the direction of the apparatus main body coupling member. A drum coupling provided at one end of the electrophotographic photosensitive drum for transmitting the rotational force of the electrophotographic photosensitive drum to the developing roller; A drum helical gear having a twisting direction that generates a thrust force in a direction in which the cartridge coupling member is provided; A developing roller helical gear provided at one end of the developing roller for receiving a rotational force for rotating the drum from the helical gear, and thrust in a direction opposite to the cartridge coupling member. A developing roller helical gear having a twisting direction that generates a force; and a longitudinal direction of the developing roller, the developing roller is provided on a side where a thrust force received by the developing roller is generated by the rotation of the helical gear. A developing bias contact electrically connected to the developing roller for receiving a developing bias to be applied to the developing means from the apparatus main body when the process cartridge is mounted on the apparatus main body; Mounting means for removably mounting the process cartridge; b. A main body developing bias contact for electrically connecting to the developing bias contact of the process cartridge mounted on the mounting means; c. There is known an image forming apparatus having a conveying unit for conveying the recording medium (Patent Document 1).

  In addition, in an electrophotographic image forming apparatus in which a process cartridge is detachable and forms an image on a recording medium, (a) a cylinder provided with a photoconductor on the peripheral surface, and a twist in the axial direction of the cylinder on one end side of the cylinder A flange having a convex portion, a first helical gear provided on the end side having the convex portion and twisted in a direction opposite to the twisting direction of the convex portion, and the side of the cylinder on which the flange is provided For developing an electrophotographic photosensitive drum provided on the side end portion and having a second helical gear having the same twisting direction as that of the convex portion, and an electrostatic latent image formed on the electrophotographic photosensitive drum A developing means for detachably mounting the process cartridge, and (b) the protrusion when the process cartridge is mounted on the main body of the image forming apparatus. (C) a developing roller gear that engages with the first gear; (d) a transfer roller gear that engages with the second gear; ) A motor for rotating the drive shaft in a direction in which the concave portion pulls the convex portion in the axial direction when the concave portion is engaged with the convex portion, and (f) conveyance for conveying the recording medium An image forming apparatus having the above-mentioned means is known (Patent Document 2).

  Further, in an electrophotographic image forming apparatus in which a process cartridge is detachable and forms an image on a recording medium, a. An electrophotographic photosensitive member, process means acting on the electrophotographic photosensitive member, a driven gear coupled to the electrophotographic photosensitive member and receiving a driving force from a driving gear of an image forming apparatus main body, and coupled to the electrophotographic photosensitive member A transfer means driving gear for transmitting driving to the transfer means of the image forming apparatus main body, and a driven gear for receiving a driving force from the driving gear of the image forming apparatus main body, and the transfer means driving gear, respectively. A mounting means for detachably mounting a process cartridge which is a helical gear and the twisting direction of the tooth trace of each gear is the same; b. A drive gear for driving the driven gear; c. Transfer means having a transfer gear meshing with the transfer means drive gear; d. An image forming apparatus having a conveying unit for conveying the recording medium is known (Patent Document 3).

Japanese Patent Laid-Open No. 10-20743 JP 2002-328563 A JP 2000-98809 A

  Even if the configuration in which the photosensitive member is detachably mounted in a state where the developing device remains in the apparatus main body, the present invention performs the operation of mounting the photosensitive member on the apparatus main body to perform the work. The present invention provides an image forming apparatus capable of maintaining a normal distance between a developing roller and a developing roll of a developing device.

The image forming apparatus of the present invention (A1)
A photoreceptor that rotates about an axis protruding from both ends;
A developing device provided with a developing roll that rotates in a state of facing the surface of the photoreceptor at a desired interval;
The photosensitive member or provided at both end portions of the developing roller, the spacing holding member for holding the two in a state spaced the distance in contact with the both end portions of the developing roller or photoconductor facing each other,
An apparatus main body to which the photosensitive member is detachably mounted and to which the developing device is attached;
A V-shaped shaft support portion provided in the apparatus main body and detachably supporting the shaft of the photoreceptor;
A guide unit provided in the apparatus main body and holding and guiding the developing device so as to move in a direction approaching and separating from the photoconductor when supported by the shaft support unit;
A pressing member that is provided in the apparatus main body and pushes the developing device in a direction approaching the photoconductor when supported by the shaft support;
Have
When the shaft of the photosensitive member is supported by the shaft support portion, the photosensitive member and the developing device have a rotational center of the photosensitive member that is above the rotational center of the developing roll in the gravitational direction, The photosensitive member is disposed so as to be in contact with the developing roll via the spacing member.

  The image forming apparatus of the invention (A2) is the image forming apparatus of the invention A1, wherein the developing device is provided with a guided shaft that is held and guided by the guide portion, and the pressing member has a direction of the pressing force. Is extended between the rotation center of the developing roll and the center of the guided shaft.

  In the image forming apparatus according to the invention (A3), in the image forming apparatus according to the invention A2 or A3, the shaft support portion has an acute angle with the direction of the pressing force of the pressing member and is separated from the developing roll. It is formed in a shape having an inclined portion that is inclined downward, and an opposing portion that contacts the shaft of the photosensitive member together with the inclined portion and makes the shaft rest at a required position.

The image forming apparatus according to the present invention (A4) has a drive device for transmitting rotational power to the developing roll in the image forming apparatus according to any one of the inventions A1 to A3,
The developing device is provided with a guided shaft that is held and guided by the guide portion, and is provided with a transmitted gear that first receives rotational power transmitted from the driving device,
The transmission gear is arranged such that the rotation center thereof overlaps the axial center of the guided shaft when viewed from the axial direction.

  In the image forming apparatus of the invention (A5), in the image forming apparatus of the invention A4, the direction of the pressure angle in the final transmission gear of the driving device that meshes with the transmitted gear is aligned with the direction in which the guide portion guides. It is configured.

  The image forming apparatus according to the present invention (A6) is the image forming apparatus according to any one of the above-described inventions A1 to A5, wherein the apparatus main body has a first drive device for transmitting rotational power to the photosensitive member, and the developing roll has rotational power. A second drive device that transmits the first and second drive devices, wherein the first drive device is disposed on one end side in the axial direction of the photoconductor, and the second drive device is disposed on the other end side in the axial direction. is there.

  The image forming apparatus according to the invention (A7) is the image forming apparatus according to any one of the inventions A1 to A5, wherein a plurality of the photoconductors are present and the same number of the developing devices as the photoconductors are present.

  According to the image forming apparatus of the invention A1, the photoconductor is mounted on the apparatus main body even when the configuration in which the photoconductor is detachably mounted with the developing device remaining in the apparatus main body is employed. By performing the operation, the distance between the photosensitive member and the developing roll of the developing device can be maintained in a normal state.

  According to the image forming apparatus of the invention A2, the developing roller of the developing device may receive a force from the contact with the developing roller when the photosensitive member is attached to the apparatus main body, compared to the case where the configuration of the invention is not provided. However, the moment generated by the developing device (the action of the force to rotate it) is reduced, and the distance between the photosensitive member and the developing roll can be maintained in a normal state.

  According to the image forming apparatus of the invention A3, even if the shaft of the photosensitive member supported by the shaft support portion receives the pressing force of the pressing member received via the developing device, compared with the case where the configuration of the invention is not provided. Deviation is regulated in the shaft support portion, and the distance between the photoconductor and the developing roll can be maintained in a normal state.

  According to the image forming apparatus of the invention A4, the moment generated in the developing device can be suppressed to a small value even when the transmitted gear receives the rotational power from the driving device, compared with the case where the configuration of the invention is not provided. The distance between the photoconductor and the developing roll can be maintained in a normal state.

  According to the image forming apparatus of the invention A5, the moment generated in the developing device can be kept small even when the transmitted gear receives the rotational power from the driving device, compared with the case where the configuration of the invention is not provided. The distance between the photoconductor and the developing roll can be maintained in a normal state.

  According to the image forming apparatus of the invention A6, as compared with the case where the configuration of the invention is not provided, that is, both the first drive device and the second drive device are arranged together at one end in the axial direction of the photoreceptor. Even when the accuracy of the size and shape of the portion corresponding to the support position of the shaft or the like in the main body is inferior, the distance between the photoconductor and the developing roll of the developing device can be maintained in a normal state.

  According to the image forming apparatus of the invention A7, the plurality of photoconductors are mounted on the apparatus main body even when the same plurality of photoconductors and developing devices exist as compared with the case where the configuration of the invention is not provided. By performing this operation, the intervals between the plurality of photoconductors and the developing rolls of the plurality of developing devices can be easily maintained in a normal state.

1 is a schematic cross-sectional view showing a main part of an image forming apparatus according to an embodiment. FIG. 2 is a schematic cross-sectional view illustrating one state of the image forming apparatus of FIG. FIG. 2 is an explanatory view showing a mounting structure of the photosensitive drum unit of FIG. 1 and a mounting structure of a developing device. FIG. 4 is a schematic perspective view showing the developing device of FIG. 3. It is a perspective view which shows the state to which the developing device was attached. FIG. 3 is an explanatory perspective view illustrating a structure of a photosensitive drum unit mounting structure, a developing device mounting structure, and a developing device drive device; It is explanatory drawing which shows the structure of the drive device for photosensitive drums. FIG. 4 is an explanatory diagram showing an arrangement state of a driving device for a photosensitive drum and a driving device for a developing device. FIG. 6 is an explanatory diagram illustrating a state where the developing device is attached (a state where the photosensitive drum unit is not attached). FIG. 6 is an explanatory diagram showing a mounted state of the photosensitive drum unit and a mounted state of the developing device associated therewith. FIG. 10 is another explanatory diagram showing a mounted state of the photosensitive drum unit and a mounted state of the developing device associated therewith. It is explanatory drawing which shows the attachment state of a developing device, and the structure of the drive device.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “embodiments”) will be described with reference to the accompanying drawings.

  1 and 2 show an image forming apparatus 1 according to the first embodiment. FIG. 1 is a cross-sectional view showing a main part of the image forming apparatus 1, and FIG. 2 is a cross-sectional explanatory view showing one state of the image forming apparatus 1 (a state where a photosensitive unit is attached / detached with an opening / closing cover opened). .

  The image forming apparatus 1 includes an apparatus main body 10 composed of a support material, an exterior material, and the like. A paper supply device 40 that houses and supplies recording paper 9 as a recording medium on which an image is to be formed is disposed at the lower part of the apparatus main body 10. On the upper part of the apparatus main body 10, there is formed a discharge storage portion 11 for discharging and storing the recording paper 9 after the image is formed. A part of the apparatus main body constituting the discharge accommodating part 11 swings outward with the first hinge (shaft) 12 as a fulcrum, and an upper opening / closing part that can open and close a part of the upper part of the apparatus main body 10. 13.

  The paper supply device 40 includes a paper container 41 that stores a plurality of recording papers 9 in a stacked state. The paper container 41 is structured to be drawn out to the front side of the apparatus main body 10 (left side of the apparatus main body 10 in FIG. 1), and the recording paper 9 is replenished in the drawn state. Above one end of the sheet container 41, a supply roll 42 that contacts the uppermost sheet of the stacked recording sheets 9 is disposed, and a separating roll 43 is disposed opposite the supply roll 42. Yes.

  In the paper supply device 40, the uppermost paper of the paper container 41 is fed by the supply roll 42, and then the paper 9 is turned up and fed one by one by the cooperation of the supply roll 42 and the separating roll 43. The fed sheet 9 is temporarily stopped by the conveyance adjusting roll 44, and then between an intermediate transfer unit 30 and a secondary transfer device 36 (to be described later) at a required timing (a timing to match a secondary transfer process to be described later) ( (Secondary transfer position)

  An image forming device 20 as an image forming unit, an intermediate transfer unit 30, a secondary transfer device 37, a fixing device 50, and the like are disposed inside a housing constituted by the apparatus main body 10. The image forming device 20 includes four image forming devices 20Y, 20M, 20C, which respectively form developer (toner) images of four colors of yellow (Y), magenta (M), cyan (C), and black (K). It is configured using 20K. The image forming device 20 (Y, M, C, K) in the first embodiment is in a state where the position gradually increases in the order of black, cyan, magenta, and yellow (inclination) except for the optical writing device (24) described later. Arranged).

  The image forming device 20 (Y, M, C, K) includes a photoconductor unit 21 (Y, M, C, K) that is detachably mounted on the apparatus main body 10 and light as a latent image forming unit. The writing device 24 includes a plurality of developing devices 25 (Y, M, C, K). As shown in FIG. 3, each of the photosensitive units 21 (Y, M, C, K) has a photosensitive drum 22 and a charging device 23 that charges the surface (photosensitive layer) of the photosensitive drum 22 to a required potential. And a cleaning device 29 that removes unnecessary materials such as toner remaining on the surface of the photosensitive drum 22 are integrated into a unit as a detachable part. In FIG. 1 and the like, the charging device 23 and the cleaning device 29 are representatively shown only for the black photosensitive drum unit 21K. Details of the photoreceptor unit 21 and the developing device 25 will be described later.

  The optical writing device 24 is disposed at a position below the four image forming devices 20 (Y, M, C, K). The optical writing device 24 is provided with a light source such as a semiconductor laser (not shown), a lens that guides and scans light emitted from the light source to the photosensitive drum 22, and optical components such as a mirror, etc. inside a light shielding housing. Yes. The optical writing device 24 irradiates the charged photosensitive drum 22 in each photosensitive unit 21 with light of each color component (an alternate long and short dash line with arrows) configured based on the image information. An electrostatic latent image is formed. On the upper surface of the housing of the optical writing device 24, a light output portion (not shown) for emitting light for forming a latent image in accordance with the irradiation position of each photosensitive drum 22 is formed.

  The developing device 25 (Y, M, C, K) is arranged between the photosensitive unit 21 (Y, M, C, K) and the optical writing device 24. Each of the developing devices 25 has a developing roll 26 that rotates in a state of facing each photosensitive drum 22 with a predetermined interval. The developing device 25 holds a developer of a required color component on the developing roll 26 and supplies the developer to a developing area facing each photosensitive drum 22, and the electrostatic latent image formed on the photosensitive drum 22 by the developer. Develop (visualize) the image. That is, it is formed as a toner image of the four colors composed of developer (toner). Each developing device 25 is replenished with a new developer from a developer replenishing device (not shown) according to the consumption of the developer.

  The intermediate transfer unit 30 includes an endless intermediate transfer belt 31 on which toner images formed on the photosensitive drums 22 of the respective image forming devices 20 (Y, M, C, and K) are transferred to the outer peripheral surface, and an intermediate transfer unit 31. A plurality of support rolls 32 a, 32 b, 32 c, 32 d, and 32 e that are wound around the transfer belt 31 so as to be in contact with the respective photosensitive drums 22 and rotated in the directions indicated by the arrows, and the toner images on the respective photosensitive drums 22 are arranged. A primary transfer device 33 for primary transfer to the outer peripheral surface of the intermediate transfer belt 31;

  Of the plurality of support rolls, the support roll 32b is a drive roll, and rotational power is transmitted from a rotation drive device (not shown) to rotate the intermediate transfer belt 31 in the direction indicated by the arrow. The primary transfer device 33 is disposed in a state in which the primary transfer device 33 is in contact with the inner peripheral surface of the intermediate transfer belt 31 and presses the outer peripheral surface of the belt 31 against the surface of each photosensitive drum 22, and a primary transfer bias voltage is applied. A roll 33 is employed.

  Further, the intermediate transfer unit 30 is equipped with a belt cleaning device 35 that removes unnecessary materials such as toner remaining on the outer peripheral surface of the intermediate transfer belt 31. The belt cleaning device 35 has an elastic blade 35a disposed so as to contact the outer peripheral surface portion of the intermediate transfer belt 31 supported by the support roll 32c.

  The intermediate transfer unit 30 is integrally attached to the back side of the upper opening / closing part 13 that is a part of the discharge accommodating part 11. As a result, as shown in FIG. 2, the intermediate transfer unit 30 is displaced to a state where the intermediate transfer unit 30 has moved to the outside of the apparatus main body 10 by swinging around the first hinge 12 during the opening / closing operation of the upper opening / closing part 13. By moving the intermediate transfer unit 30 to the outside of the apparatus main body 10, the four photosensitive drum units 21 are exposed to the outside, so that the photosensitive drum unit 21 can be attached and detached. It has become.

  The secondary transfer device 37 secondarily transfers the toner image primarily transferred onto the outer peripheral surface of the intermediate transfer belt 31 onto the recording paper 9. The secondary transfer device 37 is disposed so as to be driven and rotated in contact with the outer peripheral surface of the intermediate transfer belt 31 in a portion hung on a support roll 32b as a drive roll, and a secondary transfer bias voltage is applied. A secondary transfer roll 37 is employed. At the time of image formation, a toner image in which a plurality of color toner images are superimposed on the outer peripheral surface of the intermediate transfer belt 31 or a single color toner image is primarily transferred.

  The fixing device 50 fixes an unfixed toner image that has been secondarily transferred onto the recording paper 9, and is disposed at a position above the secondary transfer device 37. The fixing device 50 includes a roll-type and belt-type heating rotator 51 having a fixing surface heated to a required temperature by a heating unit, and an unfixed toner that contacts the fixing surface of the heating rotator 51 with a required pressure. It is composed of a pressure-type rotating body 52 in the form of a roll and a belt that forms a fixing unit through which a recording medium 9 (fixed object) that holds an image passes. The recording medium 9 holding the unfixed toner image is heated and pressed through a fixing processing section between the heating rotator 51 and the pressure rotator 52, so that the unfixed toner image is melted. Then, it is fixed on the recording paper 9.

  Inside the apparatus main body 10, in addition to the main transport path PR1 for transporting the recording paper 9, a reverse transport path PR2 and the like are formed. Incidentally, the apparatus main body 10 includes a side opening / closing section in which a portion disposed on the outside of the reversal conveyance path PR2 and an exterior material are divided along the reversal conveyance path PR2, and swings outward via the second hinge 14 to open and close. 15 is configured. The opening / closing operation of the upper opening / closing part 13 which is a part of the discharge accommodating part 11 is performed after the side opening / closing part 15 is opened first.

  The main transport path PR1 transports the recording paper 9 supplied from the paper supply device 40 to the transfer position and fixing position of the toner image, and discharges the recording paper 9 on which the image has been formed to the discharge container 11. Used for. A discharge roll 45 is disposed between the fixing device 50 in the main transport path PR1 and a discharge port 11a formed at a position immediately before the discharge storage portion 11.

  The reverse conveyance path PR2 is a conveyance path used for conveying the recording sheet 9 on which an image is formed on one side, to the secondary transfer position which is a part of the image forming unit again with the front and back sides reversed. is there. In the reverse conveyance path PR2, for example, two conveyance rolls 46 and 47 are arranged on a path from the discharge roll 45 to a position before the conveyance adjustment roll 44 and the position where it merges with the main conveyance path PR1. In the reverse conveyance path PR2, when the rear end portion of the recording paper 9 on which the image is formed is sandwiched between the discharge rollers 19, the discharge roller 45 is rotated in the reverse direction so that the recording paper 9 is conveyed from the rear end portion to the conveyance roller. Then, the paper is sequentially transferred to 46 and 47 and conveyed toward the upstream position of the conveyance adjustment roll 44.

  A power supply unit 49 is disposed inside the apparatus main body 10. The power supply units 49 and the like, for example, a voltage (current) required for power supply to the charging device 23, the image writing device 24, the developing roll 26 of the developing device 25, the primary transfer roll 33, the secondary transfer roll 37, the fixing device 50, and the like. Is applied.

  Next, the photosensitive drum unit 21 and the developing device 25 will be described in detail.

  As shown in FIG. 3, each of the photosensitive drum units 21 (Y, M, C, K) has a photosensitive drum 22 centered on a shaft 221 inside a housing-like unit main body 210 that is partially open. In this state (the shaft itself does not rotate), it is rotatably attached. The opening of the unit main body 210 includes a first opening 211 formed in a side surface portion opposite to a portion that becomes an irradiation area at the time of forming a latent image of the photosensitive drum 22 and a developing area at the time of development, and a primary of the photosensitive drum 22. There is a second opening 212 formed in the upper surface portion facing the portion to be the transfer position. The second opening 222 is provided with a covering member (not shown) that is opened in conjunction with the closing operation when the intermediate transfer unit 30 is closed (returned to the operating position). At both ends of the photosensitive drum 22, contact surface portions 223 with which a contact disk (261) of the developing roll 26 contacts are formed.

  In addition, a charging roll as the charging device 23 is attached to the inside of the unit main body 210 so that it can be driven and rotated in contact with the surface (circumferential surface) of the photosensitive drum 22, and elastic as the cleaning device 29. The blade is attached in contact with the surface of the photosensitive drum 22. Thus, in each photosensitive drum unit 21, the surface of the photosensitive drum 22 is charged to a desired potential by the charging device 23, and the surface after the primary transfer of the photosensitive drum 22 is cleaned by the cleaning device 29. The open space present in the lower portion of the unit main body 210 is used as a collection space for collecting unnecessary materials such as toner removed by the cleaning device 29. Reference numeral 229 in FIG. 3 and the like is a developer recovery container for recovering excess developer discharged from each developing device 25.

  Further, in each of the photosensitive drum units 21 (Y, M, C, K), the shaft 221 of the photosensitive drum 22 protrudes from the left and right side surfaces in the longitudinal direction (same as the axial direction) of the unit main body 210 to the outside. (The projected one shaft portion 221a and the other shaft portion 221b are formed. See FIG. 10). The shafts 221a and 221b of the photosensitive drum 22 protruding from both ends of the unit main body 210 are detachably supported with respect to a shaft support groove (15) formed in the apparatus main body 10 to be described later. Thus, the photosensitive drum unit 21 is configured to be used by being detachably attached to the apparatus main body 10. One shaft 221a supports a driven gear 225 that is driven by rotational power transmitted from a driving device (70) for a photosensitive drum, which will be described later (FIGS. 6 and 11).

  The support structure that is detachably attached to the apparatus main body 10 of the photosensitive drum 21 is configured as follows.

  As shown in FIGS. 3, 6, and the like, the support structure of the photosensitive drum 21 is configured such that the photosensitive drum 22 (Y, M, C, K) is provided with shaft support grooves 15 (Y, M, C, and K) that removably support the shafts 221a and 221b at both ends of the photosensitive drum 22, respectively, at the position that is the mounting position of K). . FIG. 6 shows a state in which only the photosensitive drum 22M is extracted from the photosensitive drum unit 21M, and the photosensitive drum 22M is supported with its shaft 216 mounted in the shaft support groove 15M.

  The shaft support groove 15 is formed in a shape that is cut downward substantially along the gravity direction G. The shaft support groove 15 supports the shaft 221 in contact with the inner portion of the groove, and the photosensitive drum 22 is positioned at a position where the shaft 221 contacts and stops when the mounting is completed. It has become so. Details of the shape of the shaft support groove 15 will be described later. In the first embodiment, the shaft support groove 15 is formed in the support plates 103 and 104 different from the side support members 101 and 102, and the support plates 103 and 104 are fixed to the side support members 101 and 102. ing. However, the shaft support groove 15 may be formed directly on the side support materials 101 and 102.

  As shown in FIG. 4 and the like, the developing device 25 (Y, M, C, K) accommodates a developer of a required color and holds the developing roll 26 rotatably with a part of the developing roll 26 exposed to the outside. It has an apparatus main body (housing) 250. The developing roll 26 is a contact disk (tracking roll) that holds both ends of the developing roller 26 in contact with both ends (220a, 200b) of the photosensitive drum 22 and keeps a predetermined distance S from the surface of the photosensitive drum 22. 261 is provided. Further, a driven gear 262 that is driven by rotational power transmitted from a developing device driving device (80) described later is attached to a shaft 26a at one end of the developing roll 26.

  Further, as shown in FIG. 4 and the like, the developing device 25 has cylindrical support shafts 61 and 62 projecting outward along the axial direction on the side surface portions at both ends in the axial direction of the developing roll 26 of the apparatus main body 250. Is provided. Of these two support shafts, the first support shaft 61 disposed on the side where the transmission gear 262 does not exist is held by being fitted into a guide holding portion (16) described later. On the other hand, the second support shaft 62 disposed on the side where the transmitted gear 262 is present rotatably supports the transmitted gear 263 that first receives the rotational power transmitted from the developing device drive device (80). Used as an axis.

  The developing device 25 (Y, M, C, K) is attached to the developing device mounting position on the pair of left and right side support members 101, 102 of the apparatus main body 10 in the following state.

  That is, as shown in FIGS. 3, 5, 9, 11, etc., the developing device 25 has a first support shaft 61 provided at the developing device mounting position on one of the side surface support members 101, 102 (101). The second support shaft 62 is fitted into a positioning hole (round hole) (not shown) formed in the other side surface support member 102. Further, in the developing device 25, both end portions of the rear end portion 250 b on the side opposite to the installation position of the developing roll 26 in the apparatus main body 250 are between the pressing surface portions 105 formed on the side support members 101 and 102. It is installed in a state where it is elastically pressed by the spring force F1 of the coil spring 16 installed in.

  That is, as shown in FIG. 11 and the like, the developing device 25 is configured such that the first support shaft 61 is held by the guide holding portion 15 and the second support shaft 62 is held by the positioning hole, and then the rear of the apparatus main body. The both ends of the end portion 250b are mounted on the apparatus main body 10 (between the side support members 101 and 102) in a state where both end portions are pressed by the spring force F1 generated by the coil spring 16. FIG. 5 shows a state in which four developing devices (Y, M, C, K) are attached to the apparatus main body 10. The developing device 25 is not in a normal mounting state at this stage (the stage where the photosensitive drum unit 21 is not mounted) (FIG. 9), and the photosensitive drum unit 21 is mounted in the shaft support groove 15 as described later. Thus, it is configured to be in a regular wearing state (FIG. 10).

  The driving device 70 for the photosensitive drum and the driving device 80 for the developing device are separately provided at both ends in the axial direction A of the photosensitive drum 22 as shown in FIG.

  The photosensitive drum driving device 70 is installed on the side of one shaft 221a of the photosensitive drum 22, as shown in FIGS. The driving device 70 for the photosensitive drum is divided into a driving device 70A for black and a driving device 70B for color (yellow, cyan, magenta).

  The black driving device 70A includes a motor 71 and a gear train 72 that transmits the rotational power of the motor 71 to the driven gear 225 in the black photosensitive drum 22K. Specifically, the drive shaft 71a of the motor 71 is connected to the driven gear 225 of the photosensitive drum 22 via a gear train 72 including, for example, a first transmission gear 72a, a second transmission gear 72b, and a final transmission gear 72c. It is connected. The transmission gear 72e in the black driving device 70A transmits rotational power to the driving roll 32b of the intermediate transfer unit 30. The color driving device 70B includes a motor 75 and a gear train 76 that transmits the rotational power of the motor 75 to the driven gears 225 in the photosensitive drums 22Y, 22M, and 22C for yellow, cyan, and magenta. It is configured. Specifically, the drive shaft 75a of the motor 75 is, for example, a photosensitive drum 22 via a gear train 76 including a first transmission gear 76a, a second transmission gear 76b, a third transmission gear 76c, and a final transmission gear 76d. The driven gear 225 is connected.

  The driving devices 70A and 70B for the photosensitive drum are attached to the side support material 101. Further, the final transmission gears 72c and 76d are provided so as to protrude inward of the side surface support member 101, and are driven by the photosensitive drums 22 mounted slightly below the shaft support groove 15. It arrange | positions in the position which can mesh | engage with the gear 225 (FIG. 6). 5, 6, 8, etc., 107 is a side plate that covers the motors 71, 75, the gear trains 72, 76, and the like.

  The developing device drive device 80 is provided for each of the four color developing devices 25 (Y, M, C, K). That is, the driving device 80 (Y, M, C, K) for the developing device uses four motors 81 (Y, M, C, K) and the rotational power of each motor 81 to each developing device 25 (Y, M, C, K) and a gear train 82 (Y, M, C, K) for transmitting to the first transmitted gear 263 in the developing roll 26. Specifically, the drive shaft 81a of each motor 81 is, for example, each gear train including a first transmission gear 82a, a second transmission gear 82b, a third transmission gear 82c, a fourth transmission gear 82d, and a final transmission gear 82e. The first transmission gear 263 in the developing roll 26 of each developing device 25 is connected to the developing device 25 via 82.

  The driving device 80 (Y, M, C, K) is attached to the side support member 102. Reference numeral 108 (Y, M, C) in FIG. 6 is a protective cover that covers each gear train 82 (Y, M, C).

  As shown in FIG. 9 and the like, the guide holding unit 16 employed in the mounting structure of the developing device 25 is a direction in which the developing device 25 approaches and separates from the photosensitive drum 22 supported by the shaft support groove 15. The guide member is held and guided so as to be moved to C and D. The guide holder 16 in the first embodiment is a guide lower surface 15a that holds the first support shaft 61 (the cylindrical portion thereof) of the developing device 25 held by the holder 16 movably along the guide directions C and D. A guide upper surface 15b that is substantially parallel to the guide lower surface 15a with a gap slightly wider than the outer diameter of the first support shaft 61 from the guide lower surface 15a, and a direction C in the direction of approaching the photosensitive drum 22 of the guide lower surface 15a. It is formed in a shape having a guide stop surface 16c connected to the guide upper surface 12b in a curved state at the downstream end.

  Further, as shown in FIG. 9 and the like, the coil spring 17 employed in the mounting structure of the developing device 25 is a direction D in which the developing device 25 approaches the photosensitive drum 22 supported by the shaft support groove 15. It is a spring that exerts a spring force (F) that pushes it. In the first embodiment, two coil springs 17 are installed at the left and right ends in the axial direction of the developing roll 26 of the developing device 25 and used in total. The number of coil springs 17 may be one or three or more.

  Further, the photosensitive drum unit 21 and the developing device 25 are arranged so as to satisfy the following conditions.

  First, when the shaft 221 of the photosensitive drum 22 is formally supported by the shaft support groove 15, the rotation center of the photosensitive drum 22 (P1: the axis of the shaft 221) is the rotation center of the developing roll 26 (P2). : Axial center of the shaft 26a) and arranged so as to exist above the gravity direction. Actually, for example, the shape and position of the portion that finally supports the shaft 221 of the photosensitive drum 22 in the shaft support groove 15 are set to satisfy the above conditions. Secondly, when the shaft 221 of the photosensitive drum 22 is formally supported by the shaft support groove 15, the photosensitive drum 22 is disposed in contact with the developing roll 26 via the contact disk 261. . Actually, the developing roller 26 (contact disk 261) of the developing device 25 is in a position where it abuts against and contacts the photosensitive drum 22 (contact surface portion 223) that moves downward in the gravity direction G along the shaft support groove 15. Thus, the mounting position of the developing device 25 is set. By arranging so as to satisfy such conditions, the developing device 25 is shifted to the normal mounting state (FIG. 10) by performing the operation of mounting the shaft 221 of the photosensitive drum 22 in the shaft support groove 15. Can be adjusted (adjusted).

  Further, as shown in FIG. 9 and the like, the shaft support groove 15 is opposed to the opposing portion (first portion) extending substantially downward along the gravitational direction G with an interval wider than the diameter of the shaft 221 of the photosensitive drum 22. The opposing portion 15a, the second opposing portion 15b), and the inclined portion 15c that inclines downward as the distance from the developing roll 22 increases at the bottom of the opposing portions 15a, 15b.

  The inclined portion 15c is formed in a shape in which an angle α between the inclined portion and the direction C of the pressing force (F) of the coil spring 17 is an acute angle (preferably in a range of 55 to 65 °). In addition, the second facing portion 15b present at a position relatively distant from the developing roll 26 has a shape that can contact the shaft 221 of the photosensitive drum 22 together with the inclined portion 15c so that the shaft 221 can be stopped at a required position. It is formed with. That is, even if the shaft 221 of the photosensitive drum 22 receives a pressing force by the spring force (F1) of the coil spring 17 via the developing device 25 (the developing roll 26), the second facing portion 15b What is necessary is just the shape which exhibits the function hold | maintained in the state which contacted the 2nd opposing part 15b and was stationary, without lifting up along the 2nd opposing part 15b.

  As shown in FIG. 10, the shaft support groove 15 finally sandwiches the shaft 221 of the photosensitive drum 22 in a V-shaped space formed by the second facing portion 15b and the inclined portion 15c. It is configured to support at a required position by supporting it in a state where it is brought into contact at two locations M1 and M2. Further, the shaft 221 of the photosensitive drum 22 is finally supported in the above-described state by the weight of the photosensitive drum unit 21. Incidentally, in the first embodiment, in order to prevent the shaft 221 from being lifted from the shaft support groove 15 during operation, the shaft 221 is moved after the shaft 221 of the photosensitive drum 22 is finally supported by the shaft support groove 15. A pressing member (not shown) that presses from above to the bottom of the shaft support groove 15 is provided.

  Next, a mounting operation of the photosensitive drum unit 21 and a change in the mounting state of the developing device 25 accompanying the operation will be described.

  First, as shown in FIG. 9, the developing device 25 is in a state where it can be moved in the direction of the arrow C by being pushed by the spring force F of the coil spring 17 when the photosensitive drum unit 21 is not mounted. Actually, the developing device 25 at this time is in a stopped state in which the first support shaft 61 abuts against the guide stop surface 16 c of the guide holding portion 16. On the other hand, the second support shaft 62 is fitted into the positioning hole of the side support member 102 of the apparatus main body 10 and is in a state where the position is substantially fixed (see FIG. 11). As a result, the developing device 25 is maintained in a state in which the end portion (contact disk 261) of the developing roll 26 on the side where the first support shaft 61 is provided is displaced to a position close to the photosensitive drum 22. The coil spring 17 at this time is held at a required length L1 close to the free length.

  When the photosensitive drum unit 21 is mounted on the apparatus main body 10, the shaft 221 of the photosensitive drum 22 moves downward in the gravity direction G along the shaft support groove 15, and the contact surface portion of the photosensitive drum 22 is moved in the middle of the movement. 223 contacts the contact disk 261 on the developing roll 26 of the developing device 25 attached to the apparatus main body 10 (see the state of the photosensitive drum 22 indicated by a two-dot chain line in FIG. 9).

  Subsequently, when the photosensitive drum 22 further moves downward in the gravity direction G by its own weight, the shaft 221 contacts the inclined surface 15c of the shaft support groove 15 and then descends along the inclined surface as shown in FIG. It stops against the facing portion 15b.

  At this time, the shaft 221 of the photosensitive drum 22 is finally supported while being sandwiched between the second facing portion 15b of the shaft support groove 15 and the inclined surface 15c and in contact with the two locations M1 and M2, as described above. Thereby, it is positioned at a required position. At this time, even if the shaft 221 of the photosensitive drum 22 supported by the shaft support groove 15 receives the spring force (F) of the coil spring 17 received via the developing device 25, the shaft 221 is displaced and displaced in the shaft support groove 15. There is no.

  At this time, the photosensitive drum 22 pushes the developing roll 26 (contact disk 261) of the developing device 22 with a force (weight) J that peels downward. As a result, the developing device 25 receives the force J from the photosensitive drum 22, so that the first support shaft 61 moves away from the photosensitive drum 22 in the guide holding portion 16 against the spring force F <b> 1 of the coil spring 17. Stop after moving to D. The coil spring 17 at this time has a length L2 (<L1) slightly contracted compared to when the photosensitive drum unit 21 is not mounted, and exhibits a spring force F1 that increases in correspondence with the slightly compressed state. Thus, the developing device 25 is continuously pushed in the direction C approaching the photosensitive drum 22.

  As described above, in the developing device 25, as shown in FIG. 11 and the like, the contact disk 261 of the developing roll 26 is in contact with the photosensitive drum 22 (the contact surface portion 223 thereof) positioned by the shaft support groove 15. Therefore, the surface of the photosensitive drum 22 and the surface of the developing roll 22 are kept in a state where a predetermined interval S is left by the contact disk 261. Further, the developing device 25 is in a regular mounting state at this stage.

  In the image forming apparatus 1, as shown in FIGS. 9, 10, etc., for the coil spring 17, an extension line (a dashed line in the figure) EL in the direction C of the spring force F that is the pushing force is the developing roll. It is set so as to pass between the rotation center P2 of 22 and the axis center P3 of the first support shaft 61. In the first embodiment, the extension line EL is set so as to pass through a substantially middle point between the rotation center P2 of the developing roll 22 and the axis center P3 of the first support shaft 61.

  For this reason, even if the developing roller 26 of the developing device 25 receives the force J from the photosensitive drum 22 when the photosensitive drum unit 21 is attached to the apparatus main body 10, the moment generated in the developing device 25 (first The action of force to rotate the support shaft 61 and the second support shaft 62 as a fulcrum is reduced. As a result, since the mounting posture of the developing device 25 does not shift due to an unnecessary moment, the interval between the photosensitive drum 22 and the developing roll 26 can be maintained in a normal state.

  Each of the photosensitive drum units 21 (Y, M, C, K) is shown in FIGS. 6, 7, 11, etc. when the shaft 221 of each photosensitive drum 22 is mounted in the shaft support groove 15. As described above, the driven gear 225 provided on one end side of each photosensitive drum 22 is engaged with and coupled to the final transmission gears 72c and 76d in the driving device 70 for the photosensitive drum. Accordingly, as shown in FIG. 7 and the like, when the motors 71 and 75 of the driving device 70 start to rotate in the required directions, the rotational power of the photosensitive drums 22 (Y, M, C, and K) is changed to the respective gear trains. It is transmitted to the driven gear 225 via 72 and 76 and rotates in a required direction.

  In the developing device 25 (Y, M, C, K), the driven gear 262 on one shaft 26a of the developing roll 26 is supported by the second support shaft 62 as shown in FIGS. Further, the transmitted gear 263 is also engaged with and coupled to the final transmission gear 82e in the driving device 80 for the developing device. As a result, when each of the developing rolls 26 of the developing device 25 (Y, M, C, K) starts rotating in the required direction, the rotational power of the motor 81 of the driving device 80 passes through each gear train 82. It is transmitted to the transmitted gear 263 and rotates in a required direction.

  Further, in the image forming apparatus 1, as shown in FIGS. 10 to 12, the shaft center P <b> 3 of the first support shaft 61 whose rotation center P <b> 4 (FIG. 12) is held by the guide holding unit 16. (FIG. 10) and are arranged so as to overlap with each other when viewed in the axial direction. 11 is a line indicating the axial direction passing through the axial center P3 of the first support shaft 61, and this is the axial center of the second support shaft 62 that rotatably supports the transmitted gear 263 (transmitted). The same state as that of the rotation center P4 of the gear 263 is shown.

  Thus, even when the transmitted gear 263 in the developing device 25 receives rotational power from the driving device 80, the transmitted gear 263 receives a force from the final transmission gear 82e to the second support shaft 62 of the developing device 25. Even if a force directed in the direction K of the pressure angle of the final transmission gear 82e described later (a two-dot chain line with arrows in FIG. 12) is applied, the axial center of the first support shaft 61 and the axial center of the second support shaft 62 are applied. Are substantially equal to each other, so that the moment generated in the developing device 25 can be kept small. As a result, since the mounting posture of the developing device 25 does not shift due to an unnecessary moment, the interval S between the photosensitive drum 22 and the developing roll 26 can be maintained in a normal state.

  Furthermore, in the image forming apparatus 1, as shown in FIG. 12, the direction K of the pressure angle in the final transmission gear 82e of the driving device 80 that meshes with the transmission gear 263 in the developing device 25 is the direction C in which the guide holding unit 16 guides. , D. Specifically, the direction K of the pressure angle of the final transmission gear 82e is set so that the intersecting angle with the guide directions C and D of the guide holding part 16 is in the range of 0 ° to 20 °.

  Thus, even when the transmission gear 263 in the developing device 25 receives rotational power from the final transmission gear 82e of the driving device 80, the direction of the external force received by the engagement with the final transmission gear 82e is changed. Since the guide holding portion 16 is in a state that coincides with or substantially follows the guide directions C and D, the second support shaft 62 that supports the transmission gear 263 is affected by a force that bites the guide holding portion 16. Is suppressed. As a result, even if the second support shaft 62 slides with respect to the guide holding portion 16 during the rotation of the developing roller 26 due to eccentricity existing on the photosensitive drum 22, it smoothly slides (tracks). As a result, the distance S between the photosensitive drum 22 and the developing roll 26 can be maintained in a normal state.

  In addition to this, in the image forming apparatus 1, the driving device 70 for the photosensitive drum and the driving device 80 for the developing device are separately provided on both ends in the axial direction A of the photosensitive drum 22.

  For this reason, as shown in FIG. 8, the width W in the axial direction A of the photosensitive drum 22 including the driving devices 70 and 80 is combined into the same side (one side) of the driving devices 70 and 80 in the axial direction A. The image forming apparatus 1 can be made relatively small as compared with the case of installation, and the image forming apparatus 1 can be downsized. When arranging them together on the same side, for example, it is necessary to displace gear trains corresponding to the respective driving devices in the axial direction A of the photosensitive drum 22, and the width in the axial direction A increases accordingly. It becomes easy.

  Further, when both drive devices 70 and 80 are arranged separately on both sides in the axial direction A, there are the following advantages. That is, generally, the shaft or the like that is the end on the side that receives the rotational power from the drive through the meshing of the gear is attached to the apparatus main body 10 with almost no excess gap (backlash), and the opposite end These shafts and the like are attached to the apparatus main body 10 with a slight allowance for excess gaps (backlash).

  For this reason, when the driving device is arranged on the same end side in the axial direction A, the end receiving the rotational power of the photosensitive drum 22 and the end receiving the rotational power of the developing device 25 are on the same side in the axial direction A. Therefore, a support shaft (61) for providing the shaft 221 of the photosensitive drum 22 and the transmission gear 263 of the developing device 25 is attached to the apparatus main body 10 without an extra gap, and thereby the distance between the shafts. To a fixed state. However, in this case, when the accuracy of the size and shape is inferior in the portion where the shaft of the photosensitive drum 22 of the apparatus main body 10 and the support shaft of the developing device 25 are attached, the distance between the shafts on the side receiving the rotational power. And the distance S between the photosensitive drum 22 and the developing roll 22 may also vary.

  In this regard, when the driving device is distributed and arranged at the end opposite to the axial direction A, as shown in FIG. 11, the end receiving the rotational power of the photosensitive drum 22 and the rotational power of the developing device 25 are used. Since the receiving end portion exists on the opposite side in the axial direction A, the mounting state of the shaft of the photosensitive drum 22 and the mounting state of the end portion of the developing device 25 are the same as the mounting side without an extra gap. The side that allows a large gap is alternately arranged. Further, in this case, if the shafts at both ends of the photosensitive drum 22 are fixed, the end portion (first support shaft 61) on the side that does not receive the rotational power of the developing device 25 is in a state that allows an extra gap. By attaching (holding on the guide holding portion 16), even if the shaft 221 of the photosensitive drum 22 is displaced, the end on the side not receiving the rotational power of the developing device 25 is displaced by a necessary amount to follow. (Correction) can be performed. Therefore, even when the accuracy of the size and shape of the apparatus main body 10 is inferior, the distance between the axes of the photosensitive drum 22 and the developing roll 26 can be suppressed, and the photosensitive drum 22 and the developing roll 22 can be prevented from being different. Fluctuation of the interval S can also be suppressed.

[Other embodiments]
In the first embodiment, the transmitted gear 263 is attached to the second support shaft 62. However, the transmitted gear 263 may not be attached. The contact disks 261 that are spacing members can also be provided at both ends of the photosensitive drum 22.

  In the first embodiment, the case where a plurality (four) of the photosensitive drums 22 and the developing devices 25 are used is exemplified. However, the present invention is also applied to an image forming apparatus that uses a single photosensitive drum 22 and the developing device 25. Can be applied. Further, the present invention can be applied to an image forming apparatus using a plurality of photosensitive drums 22 and developing devices 25 other than four.

  In addition, when the image forming apparatus to which the present invention is applied is an image forming apparatus capable of forming a color image, a method that does not use the intermediate transfer device 3 (so-called recording paper P in each image forming unit 2). A direct transfer format in which the toner image is directly transferred onto a recording sheet by being conveyed so as to pass through each primary transfer position may be employed. The image forming apparatus to which the present invention is applied is represented by, for example, an image forming apparatus such as a printer, a copier, and a facsimile, a print function, a copy function, a facsimile function (image input / output transmission / reception function), and the like. An image forming apparatus in which each function is combined is exemplified.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Apparatus main body 15 ... Shaft support groove (shaft support part)
15b ... 2nd opposing part (opposing part)
15c ... inclined part 16 ... guide holding part (guide part)
17 ... Coil spring (pushing member)
22 ... Photoconductor drum (photoconductor)
25 ... developing device 26 ... developing roll 61 ... first support shaft (guided shaft)
62 ... Second support shaft (guided shaft)
70 ... Drive device for photosensitive drum (second drive device)
80... Driving device for the developing device (first driving device)
101, 102 ... Side support material (part of the device main body)
103, 104 ... support plate (part of the device body)
221... Axis (photoconductor axis)
263: Transmitted gear (transmitted gear that receives rotational power first)
A ... Axial direction C ... Approaching direction D ... Separating direction G ... Gravitational direction S ... Spacing F ... Spring force (pressing force)
EL: Extension line P1 in the direction of pressing force: Axis center (rotation center of the photoconductor)
P2: Development roll rotation center P3: First support shaft rotation center P4: Transmitted gear rotation center CD: Guiding direction K: Pressure angle direction

Claims (7)

A photoreceptor that rotates about an axis protruding from both ends;
A developing device provided with a developing roll that rotates in a state of facing the surface of the photoreceptor at a desired interval;
The photosensitive member or provided at both end portions of the developing roller, the spacing holding member for holding the two in a state spaced the distance in contact with the both end portions of the developing roller or photoconductor facing each other,
An apparatus main body to which the photosensitive member is detachably mounted and to which the developing device is attached;
A V-shaped shaft support portion provided in the apparatus main body and detachably supporting the shaft of the photoreceptor;
A guide unit provided in the apparatus main body and holding and guiding the developing device so as to move in a direction approaching and separating from the photoconductor when supported by the shaft support unit;
A pressing member that is provided in the apparatus main body and pushes the developing device in a direction approaching the photoconductor when supported by the shaft support;
Have
When the shaft of the photosensitive member is supported by the shaft support portion, the photosensitive member and the developing device have a rotational center of the photosensitive member that is above the rotational center of the developing roll in the gravitational direction, An image forming apparatus, wherein the photosensitive member is disposed so as to be in contact with the developing roll via the spacing member.
A guide shaft that is held and guided by the guide unit is provided in the developing device;
The image forming apparatus according to claim 1, wherein the pressing member is configured such that an extension line in a direction of the pressing force passes between a rotation center of the developing roll and an axis center of the guided shaft.   The shaft support portion is in contact with the shaft of the photosensitive member together with the inclined portion that is inclined downward as the angle formed with the direction of the pressing force of the pressing member becomes an acute angle and is separated from the developing roll. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed in a shape having an opposing portion that makes the shaft stop at a required position. A driving device for transmitting rotational power to the developing roll;
The developing device is provided with a guided shaft that is held and guided by the guide portion, and is provided with a transmitted gear that first receives rotational power transmitted from the driving device,
4. The image forming apparatus according to claim 1, wherein the transmission gear is arranged such that a rotation center thereof overlaps with an axis center of the guided shaft when viewed from the axial direction. 5.   The image forming apparatus according to claim 4, wherein a direction of a pressure angle in a final transmission gear of the driving device that meshes with the transmitted gear is configured to be along a direction in which the guide portion guides. The apparatus main body is provided with a first drive device that transmits rotational power to the photoconductor and a second drive device that transmits rotational power to the developing roll,
6. The image formation according to claim 1, wherein the first driving device is disposed on one end side in the axial direction of the photoconductor, and the second driving device is disposed on the other end side in the axial direction. apparatus.   The image forming apparatus according to claim 1, wherein a plurality of the photoconductors are present, and the same number of the developing devices as the photoconductors are present.

Images