JP2008191233A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately position an SD gap without changing the relative positions of respective component members in an image forming apparatus including a developing device having twin-sleeve constitution. <P>SOLUTION: Respective developing sleeves 31 and 32 are rotatably supported in a developing container 30, and butting rollers 36a, 36b, 37a and 37b are disposed on the respective developing sleeves, and then the developing device 16 is energized to butting blocks 38a and 38b so as to abut the rollers on them. The image forming apparatus is equipped with fitting parts comprising shaft parts 41a and 41b and hole parts 40a and 40b where the developing device 16 and the butting blocks 38a and 38b are fit in order to keep the axial lines of the developing sleeves 31 and 32 on the developing device 16 side parallel with the axial line of a photoreceptor drum 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a printer that visualizes an electrostatic image on a photosensitive drum as an image carrier using a developer (hereinafter, toner).

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine, an electrostatic latent image formed on the surface of a drum-type photoreceptor is developed as a toner image by a developing device, transferred to a recording medium such as paper, and fixing means. Is used to obtain a recorded image after fixing.

  Here, in the developing device, a developer carrying member (hereinafter referred to as a developing sleeve) is arranged with a certain gap with respect to the photosensitive member. As a means for maintaining the gap, an abutment roller system is generally used. This is determined by the difference between the outer diameter of the regulating member (abutment roller) disposed on the same axis as the developing sleeve and the outer diameter of the developing sleeve. Is guaranteed. There is also a system in which the abutting roller abuts against a supporting member that rotatably supports the photosensitive member.

  2. Description of the Related Art In recent years, there have been developing devices that are provided with two developing sleeves and can cope with high speed and high image quality in accordance with the improvement (high speed) and high image quality of copiers and printers. A developing container includes a first developing sleeve located upstream of the image forming process and a second developing sleeve located downstream. Each of the two developing sleeves in the developing container is supported so as to be movable in the normal direction of the photosensitive member. Then, as the abutting roller is urged and abutted in the direction of the photoconductor, the roller is appropriately moved in the normal direction of the photoconductor. Alternatively, the first developing sleeve is rotatably supported by the developing container, and the second developing sleeve is pivotally supported so as to be swingable about the rotation axis of the first developing sleeve (see, for example, Patent Document 1). ).

The relative positioning (bus line alignment) between the developing container and the developing sleeve is determined by being guided by a pair of parallel plates that circumscribe the abutting roller (for example, see Patent Document 2).
Japanese Patent Laid-Open No. 2002-351111 (Section 13, FIG. 3) Japanese Patent Laying-Open No. 2003-307930 (Section 7, FIG. 4)

However, further improvement in performance has been demanded for the above-described conventional technology.

An object of the present invention is to provide an image forming apparatus capable of accurately positioning the distance between a developer carrier and an image carrier with a simple configuration.

  A typical configuration of the image forming apparatus according to the present invention for achieving the above object includes an image carrier, a support member that rotatably supports the image carrier, and an electrostatic formed on the image carrier. An image forming apparatus comprising: a first developer carrying member that supplies a developer to an image; and a developing device that rotatably includes a second developer carrying member, wherein the developing device includes the first developing member. Positioned on the same axis line of the developer carrier and the second developer carrier, are rotatably connected, and contact the support member to contact the first developer carrier and the second developer carrier. An abutting member that maintains a constant distance from the image carrier, and maintains the axis of the first developer carrier and the second developer carrier and the axis of the image carrier in parallel; And a fitting portion formed by a shaft portion and a hole portion into which the developing device and the support member are fitted. And butterflies.

  According to the present invention, it is possible to provide an image forming apparatus capable of accurately positioning the distance between the developer carrier and the image carrier with a simple configuration.

  FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus according to the present invention. This image forming apparatus is an electrophotographic digital copying machine, and includes an image reading unit (reader unit) 1 and an image forming unit (printer unit) 2.

  The image reading unit 1 is an image reader that photoelectrically reads image information of a document. A document 4 to be copied is placed on the platen glass 3 with the image surface facing downward according to a predetermined placement standard, and a document pressing plate (not shown) is placed thereon. When a copy button of an operation unit (not shown) is pressed, the image reading mechanism unit 5 operates to photoelectrically read the downward image surface of the document 4 on the glass 3. The image reading mechanism 5 is an optical system moving type image reader, and includes an original illumination lamp 6, reflection mirrors 7 to 9, an imaging lens system 10, an image reading element 11 such as a CCD sensor, and the like. The electrical information of the manuscript image photoelectrically read by the image reading element 11 is input to a control unit 12 as a control means, and is subjected to image processing to become a digital image signal subjected to image modulation. The control unit 12 controls the image forming operation of the entire copying machine.

  The image forming unit 2 forms a toner image corresponding to the digital image signal on the recording material P by electrophotographic process means. That is, the image forming unit 2 includes a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 13 as a rotatable image carrier. Further, it has a charger 14 as an electrophotographic process means acting on the photosensitive drum 13, a laser scanner unit 15 as an exposure unit, a developing device 16, a transfer charger 17, a cleaner 18, and the like.

  The photosensitive drum 13 is driven to rotate at a predetermined speed in a clockwise direction B indicated by an arrow. The surface of the rotating photosensitive drum 13 is uniformly charged by the charger 14 to a predetermined polarity and potential. The charged surface of the photosensitive drum 13 is image-exposed by the laser scanner unit 15. The laser scanner unit 15 includes a laser oscillator, a polygon scanner, a lens, a mirror, and the like. The laser scanner unit 15 outputs a laser beam L modulated in accordance with an image-processed digital image signal input from the control unit 12, and the photosensitive drum 13. The charged surface is scanned and exposed. Thereby, an electrostatic image corresponding to the scanning exposure pattern is formed on the photosensitive drum surface. The latent image is visualized as a toner image by the developing device 16.

  On the other hand, the sheet feeding roller 19 of the sheet feeding unit is driven at a predetermined control timing, and the sheet-like recording material P such as sheets stacked and accommodated in the sheet feeding cassette 20 is separated and fed. . The recording material P is sent to a timing roller (registration roller) 23 through a paper conveyance path 22 including a conveyance roller 21. The timing roller 23 stops rotating until the recording material P arrives, and the skew of the recording material P is corrected by receiving the leading end of the recording material P against the nip portion. Next, the timing roller 23 conveys the recording material P to a transfer portion that is a facing portion between the photosensitive drum 13 and the transfer charger 17 so as to be synchronized with the leading end of the toner image formed on the photosensitive drum 13. That is, the timing roller 23 conveys the recording material P so that the leading end portion of the toner image formed on the photosensitive drum 13 and the leading end portion of the recording material P correspond to each other at the transfer portion.

  The recording material P conveyed to the transfer portion is given a charge opposite in polarity to the toner by the transfer charger 17, and the toner image on the photosensitive drum 13 side is electrostatically transferred onto the surface of the recording material P.

  The recording material P exiting the transfer portion is separated from the surface of the photosensitive drum 13, guided by the guide member 24, and introduced into the fixing device 25. The fixing device 25 is a heat-pressure fixing device having a roller pair of a heating roller 25a and a pressure roller 25b as basic constituent members, and the recording material P is introduced into a fixing nip portion, which is a pressure contact portion of the roller pair, and is nipped and conveyed. Being subjected to heat and pressure. As a result, the toner image is fixed as a fixed image on the surface of the recording material P, and is discharged and conveyed to a paper discharge unit (not shown).

  Further, the surface of the photosensitive drum 13 from which the recording material has been separated after passing through the transfer section is cleaned by receiving and removing the transfer residual toner by the cleaner 18 and repeatedly used for image formation.

  Here, the conveyance of the recording material P in the copying machine is the central reference conveyance at the center of the recording material width in the entire conveyance path. With respect to the recording material, the width is a size of the recording material in a direction orthogonal to the conveyance direction of the recording material.

(2) Developing device 16
FIG. 2 is an enlarged schematic view of the developing device 16 portion of FIG. FIG. 3 is an external perspective view of the developing device 16.

  In the following description, the front side and the back side of the copying machine or developing device or the members constituting the copying machine or developing device are the photosensitive drum 13 that is an image carrier or the developing sleeve that is a developer carrier, respectively. These are one end side and the other end side in the rotation center axis direction.

  2 and 3, reference numeral 30 denotes a developing container as a housing (developing device frame) of the developing device 16. The developing container 30 has an opening facing the photosensitive drum 13 as an image carrier. First and second developer carriers, which are arranged in parallel in the opening in the vertical direction and supply developer to the latent image formed on the photosensitive drum 13, and second developer carriers. Cylindrical developing sleeves (or developing rollers) 31 and 32 are provided. The first and second developing sleeves 31 and 32 respectively have bearing members on the front side and the back side with respect to the first and second walls 30a and 30b on the front side and the back side of the developing container 30 respectively. It is positioned and supported (axially supported) via a shaft. Further, first and second developer agitating / conveying screws 33 and 34 are arranged inside the developing container 30 in parallel in the vertical direction. The first and second developer agitating / conveying screws 33 and 34 also have front and rear end portions on the front and rear side first and second side walls 30a and 30b of the developing container 30, respectively. Thus, it is positioned and supported (supported by a shaft) via a bearing member. The developing container 30 is provided with a developing blade 35 with a doctor blade for regulating the amount of developer coating on the surface of the first developing sleeve 31 positioned and fixed. Although not shown in the drawing, developer (toner) is accommodated in the developing container 30.

  The first and second developing sleeves 31 and 32 and the first and second developer agitating and conveying screws 33 and 34 are substantially parallel to each other in the rotation center axis, It is positioned and supported with respect to the first and second side walls 30a and 30b on the back side. The developing blade 35 is also positioned and fixed with respect to the developing container 30. Therefore, the relative positions of the developing sleeves 31 and 32 and the developer agitating and conveying screws 33 and 34 and the structure such as a developing container forming the developing device are maintained.

  As shown in FIG. 2, the developing device 16 is arranged such that the first and second developing sleeves 31 and 32 hold a predetermined constant gap (SD gap) d with respect to the photosensitive drum 13. The rotation center axes of the first and second developing sleeves 31 and 32 are substantially parallel to the rotation center axis of the photosensitive drum 13. The first developing sleeve 31 is positioned on the upstream side (upstream side of the image forming process) with respect to the rotation direction of the photosensitive drum 1, and the second developing sleeve 32 is positioned on the downstream side (image) with respect to the rotation direction of the photosensitive drum 1. Located downstream of the formation process.

  The developer in the developer container 30 is cyclically conveyed along the length of the screw while being stirred in the developer container 30 by driving the first and second developer agitating and conveying screws 33 and 34. . The first and second developing sleeves 31 and 32 are respectively rotated at a predetermined speed in the counterclockwise direction indicated by the arrow A, and the developer in the developing container 30 is a thin layer having a uniform thickness on the surface thereof. To be supported. A thin layer of developer formed on the surfaces of the first and second developing sleeves 31 and 32 is transported to a developing region which is a portion opposite to the photosensitive drum 13 and the developing sleeve by the rotation of the sleeve. The developer on the developing sleeve side selectively moves to the photosensitive drum 13 corresponding to the latent image pattern by the action of the developing bias applied to the developing sleeve, so that the latent image pattern on the photosensitive drum 13 side is changed. Developed as a toner image.

  As shown in FIG. 3 and FIG. 4, the first developing sleeve 31 is positioned on the same axis as the abutting member on the front side and the rear end side, respectively. Two rollers 36a and 36b are rotatably connected. Further, the first and second rollers 37a and 37b as the abutting members are also rotated on the front side and the back end side of the second developing sleeve 32 on the same axis as the developing sleeve, respectively. They are freely connected.

  As shown in FIG. 5, the photosensitive drum 13 serving as an image carrier has shaft ends on the near side and the back side, respectively, and front and back side first and second support blocks 38a,. 38b is rotatably positioned and supported (supported) via a bearing member. And it is rotationally driven at a predetermined speed in the direction of arrow B by a driving means (not shown). The first and second support blocks 38a and 38b include first rollers 36a and 37a on the front side of the first and second developing sleeves 31 and 32, and second rollers 36b and First and second abutting surfaces 39a and 39b that abut on 37b are provided. Then, as shown in FIG. 6, the contact between the photosensitive drum 13 and the first developing sleeve 31 is caused by the contact between the contact surface 39a and the rollers 36a and 37a and the contact surface 39b and the rollers 36b and 37b. The gap d and the gap d between the photosensitive drum 13 and the first developing sleeve 31 are maintained. The gap d in the present embodiment is processed with high accuracy so that both the first developing sleeve 31 and the second developing sleeve 32 are 0.35 mm.

  In other words, the developing device 16 is positioned on the same axis line of the developing sleeves 31 and 32, is rotatably connected, and is in contact with the support blocks 38a and 38b to keep the distance between the developing sleeve and the photosensitive drum constant. 36 (a · b) and 37 (a · b).

  On the other hand, in order to keep the axis (bus line) of the developing sleeves 31 and 32 inside the developing device 16 parallel to the axis of the photosensitive drum 13, support blocks 38 a and 38 b that are supporting members of the developing device 16 and the photosensitive drum 13. Is provided with a fitting portion formed by a shaft portion and a hole portion.

  That is, the first and second support blocks 38a and 38b that support the photosensitive drum 13 are provided with first and second fitting holes 40a and 40b as the hole portions, respectively, as shown in FIG. I'm allowed. Further, on the developing container 30 side, as shown in FIG. 3, first and second pins 41a as shaft portions that are fitted in correspondence with the first and second fitting holes 40a and 40b, respectively. 41b is provided.

  The first and second developing sleeves 31 and 32 are positioned and held in the developing container 30 so as to be rotatable relative to each other. Therefore, as shown in FIG. 6, the fitting holes 40a and 40b and the pins 41a and 41b are fitted to keep the axes of the photosensitive drum 3 and the developing sleeves 31 and 32 parallel. it can.

  As described above, the gap d between the photosensitive drum 13 and the developing sleeves 31 and 32 is a contact surface of a total of four abutting rollers 36a and 36b, 37a and 37b disposed in the two developing sleeves 31 and 32. It is maintained by contact with 39a and 39b. The rollers 36a and 36b and 37a and 37b are in contact with the contact surfaces 39a and 39b on the front side and the back side of the developing device 16 by the first and second pressurizing means 42a and 42b, respectively. It is maintained by being pressed against the support blocks 38a and 38b.

  Here, the plane is determined at three points in the space, that is, the relative position between the photosensitive drum 13 and the developing device 16 is determined by the three abutting rollers. However, in actuality, the developing container 30 is made rigid by urging the developing device 16 in the direction of the first and second support blocks 38a and 38b by the first and second pressurizing means 42a and 42b. In contrast, the support blocks 38a and 38b are bent to cause bending. Therefore, the four abutting rollers 36a and 36b, 37a and 37b abut on the abutting surfaces 39a and 39b of the first and second support blocks 38a and 38b, and the gap between the developing sleeves 31 and 32 and the photosensitive drum 13 is reached. d is maintained at the desired amount (0.35 mm in this example).

  It is desirable that the developing device 16 be formed with high accuracy, and that the positions of the four abutting rollers 36a, 36b, 37a, 37b be on the same plane as much as possible (no twist). In the developing device 16 of the present embodiment, if the position of the remaining one abutting roller is 0.5 mm or less with respect to the plane formed by the three abutting rollers due to twisting of the developing container 30 or the like, The four abutting rollers abut on the abutting surfaces 39a and 39b at a force of 9.6 N (2 kgf) or less. Accordingly, the gap d between the developing sleeves 31 and 32 and the photosensitive drum 13 can be maintained without applying an extreme biasing force.

  As described above, the first and second developing sleeves 31 and 32 are rotatably positioned and supported by the first and second side walls 30a and 30b on the near side and the far side of the developing container 30. Similarly, the first and second developer agitating / conveying screws 33 and 34 are positioned by the first and second side walls 30a and 30b on the near side and the far side of the developing container 30, respectively. For this reason, the relative positions of the developing sleeves 31 and 32 and the developer stirring and conveying screws 33 and 34 and the structure such as a developing container forming the developing device are maintained.

  Further, the developing device 16 has contact between the contact surfaces 39a and 39b of the first and second support blocks 38a and 38b and the rollers 36a and 36b, 37a and 37b, and the fitting holes 40a and 40b and the pins 41a and 41a. The relative position with respect to the photosensitive drum 13 is determined by the fitting with 42b. However, in actuality, as shown in FIGS. 7A and 7B, the developing device 16 is caused by errors in the contact surfaces 39a and 39b, errors in outer diameters of the rollers 36a and 36b, and 37a and 37b. For example, a slight inclination difference such as an angle α or an angle β occurs. At this time, the insertion tip portions of the pins 41a and 41b on the developing device 16 side that fit into the fitting holes 40a and 40b on the first and second support blocks 38a and 38b side are spherical as shown in FIG. Set to part a. That is, the portions of the pins 41a and 41b that are the shaft portions that are in contact with the fitting holes 40a and 40b that are the holes are formed into a sphere. Accordingly, as shown in FIGS. 7A and 7B, the fitting holes 40a and 40b and the pins 41a and 41b are fitted even if the attitude of the developing device 16 (the inclination α and the inclination β) changes. However, it is movable in the x direction and regulates the y direction and has a degree of freedom of rotation. Therefore, the posture of the developing device 16, that is, the contact of the rollers 36a and 36b and 37a and 37b with the contact surfaces 39a and 39b is not hindered. Since the rotation fulcrum of the developing device 16 is the center of the spherical portion a of the pins 41a and 41b, the first and second pins 41a and 41b disposed on the front side and the back side of the developing device 16 are provided. It is desirable that the line connecting the centers of the spherical portions a be parallel to the axis of the developing sleeves 31 and 32.

  In the present embodiment, as shown in FIG. 9, the maximum sheet passing width of the recording material that can be used in the apparatus is A3 length (297 mm × 420 mm). It is set to 300 mm with some allowance. Paper is passed on a central basis. O is the center of the image (central paper passing reference line: virtual line). In the developing device 16, the near side and the far side of the first developing sleeve 31 and the second developing sleeve 32 are supported at a position of 182 mm from the image center O, respectively. The first and second abutting rollers 36a and 36b of the developing sleeves 31 and 32 are disposed at a position 201.5 mm from the image center O, respectively. Further, the positions of the first and second pins 41a and 41b fitted into the first and second fitting holes 40a and 40b are positions 202.5 mm from the image center O, respectively. The urging positions for urging the developing device 16 by the first and second pressure units 43a and 43b are positions 185 mm from the image center O, respectively. Further, the front and back mounting positions of the developing blade 35 with the doctor blade for regulating the developer coating amount on the surface of the first developing sleeve 31 with respect to the developing container 30 are 170 mm from the image center O, respectively.

  The developing blade 35 is disposed at a position close to a plane parallel to a plane orthogonal to the axial center of the photosensitive drum 13. For this reason, as described above, a minute twist occurs when the developing device 16 is pressurized, but a phenomenon such as a change in the gap between the first developing sleeve 31 and the developing blade 35 due to the twist is minimized. it can. In the configuration of this embodiment, the amount of change in the gap between the first developing sleeve 31 and the developing blade 35 due to pressurization is 3 to 6 μm, and the influence on the image forming process is negligible.

  In this embodiment, the diameter of the spherical portion a of the first and second pins 41a and 41b is formed with Φ4.5. The abutting rollers 36a and 36b and 37a and 37b are substantially the same as the outer diameter of the developing sleeve in the structure (in the case of the present embodiment, Φ24). In FIG. 6, for the sake of convenience, the rollers 36 a and 36 b and 37 a and 37 b are drawn with a smaller diameter than the developing sleeves 31 and 32. In order to enable the developing device 16 to be inserted / removed from the front side of the image forming apparatus, the separation amount in the case of the configuration described in the conventional example requires about 25 mm. On the other hand, since the spherical portions a of the pins 41a and 41b of this embodiment have a small diameter, it is sufficient that the separation amount is 6 mm or more. For this reason, in particular, in a so-called in-line type color image forming apparatus in which a plurality of developing devices are arranged in parallel, it is possible to reduce the space for the separation amount, so that the size of the apparatus is not increased.

  In addition, the shape of the first and second support blocks 38a and 38b is such that the positions of the contact surfaces 39a and 39b that contact the abutting rollers and the fitting holes 40a and 40b that fit the pins 41a and 41b are accurately determined. All you need to do is process. Therefore, the first and second support blocks 38a and 38b are not extremely expensive.

  As described above, the two developing sleeves 31 and 32 are positioned in the developing device. Therefore, the relative position relationship with the other developing sleeve, the inner wall of the developing container, the end seal, the screw that is incorporated in the developing container and that stirs and conveys the developer does not change, and the developer agent in the developing container does not change. It does not affect the circulation. Accordingly, it is possible to provide a stable image forming apparatus which does not have a developer coating defect on the developing sleeve or a developer recovery defect.

  Further, the fitting of the fitting portion for holding the photosensitive drum 13 and the developing sleeves 31 and 32 in parallel does not affect the operation of maintaining the gap d between the photosensitive drum 13 and the developing sleeves 31 and 32. A forming apparatus can be provided.

  Furthermore, it is possible to provide an image forming apparatus excellent in exchangeability of the developing device without causing an increase in size of the apparatus.

  FIG. 10 is a schematic sectional view of the pins 41a and 41b on the developing device 16 side and the fitting holes 40a and 40b on the first and second support blocks 38a and 38b side in this embodiment. The pins 41a and 41b have a cylindrical shape, and a spherical rotor 44 is provided in the fitting holes 40a and 40b. That is, the member constituting the hole is made rotatable. Like the ball joint, the rotor 44 is supported in the fitting holes 40a and 40b so as to be rotatable around the center of rotation, and has a hole b that fits into the pins 41a and 41b.

  When the pins 41a and 41b on the side of the developing device 16 are fitted into the hole b of the rotor 44, the rotor 44 has a degree of freedom of rotation, so that the developing device 16 is rotatably supported around the rotation center. . Therefore, the posture of the developing device 16, that is, the contact of the rollers 36a and 36b and 37a and 37b with the contact surfaces 39a and 39b is not hindered.

  In this embodiment, the rotation center of the rotor 44 is provided at a position where the axis of the pins 41a and 41b passes. That is, the hole member 44 is rotatable about one point on the center axis of the hole. However, the present invention is not limited to this. For example, the hole b that fits with the pins 41a and 41b of the rotor 44 may be formed near the arm-shaped tip, and the other end may be the center of oscillation.

  In this embodiment, the pins 41a and 41b are provided on the developing device 16 side, and the fitting holes 40a and 40b are provided on the first and second support blocks 38a and 38b. -You may arrange | position by reversing the relationship between 41b and the fitting holes 40a and 40b. That is, the fitting holes 40a and 40b may be provided on the developing device 16 side, and the pins 41a and 41b may be provided on the first and second support blocks 38a and 38b.

  In addition, the configuration in which the pins 41a and 41b are arranged below the second developing sleeve 32 has been described as an example. However, the pins 41a and 41b are arranged between the first and second developing sleeves 31 and 32, for example. It may be arranged.

  Although the image forming apparatus according to the embodiment is a monochromatic image forming apparatus, the present invention is a tandem type image forming apparatus having a plurality of image forming units, or a one-drum type image forming apparatus having a plurality of switching type developing devices. It can also be applied to an image forming apparatus.

  In the present invention, the image forming method of the image forming apparatus is not limited to an electrophotographic process using a photoconductor as an image carrier, and an electrostatic recording process using an electrostatic recording dielectric or a magnetic recording magnetic material as an image carrier. Or a magnetic recording process.

Schematic configuration diagram of image forming apparatus of embodiment Enlarged view of the developing device portion in FIG. Perspective view of developing device A perspective view of the first and second developing sleeves and the first and second rollers Perspective view of photosensitive drum supported by support block Schematic illustration of the development device Explanatory drawing of slight inclination difference of developing device Explanatory drawing of fitting part Illustration of positional relationship Explanatory drawing of the fitting part in Example 2

Explanation of symbols

  1 .... Document reading unit 2 .... Image forming unit 13 .... Photosensitive drum (image carrier), 38a, 38b ... Support block (support member) 16 .... Developing device 31, 32 ... Developing sleeve (Developer carrier), 36a, 36b, 37a, 37b, abutment roller (abutment member), 41a, 41b, pin (shaft), 40a, 40b, fitting hole (hole)

Claims (5)

An image carrier, a support member that rotatably supports the image carrier, a first developer carrier and a second developer carrier that supply developer to an electrostatic image formed on the image carrier. In an image forming apparatus comprising a developing device having a rotatable body,
The developing device is located on the same axis line of the first developer carrier and the second developer carrier, is rotatably connected, and contacts the support member to contact the first developer carrier. An abutting member for maintaining a constant distance between the image carrier and the image developer and the second developer carrier.
In order to keep the axis of the first developer carrier and the second developer carrier and the axis of the image carrier in parallel, a shaft and a hole in which the developing device and the support member are fitted With a fitting part by
An image forming apparatus.   The image forming apparatus according to claim 1, wherein a portion of the shaft portion in contact with the hole portion is a sphere.   The image forming apparatus according to claim 1, wherein a member constituting the hole is rotatable.   The image forming apparatus according to claim 1, wherein a member constituting the hole portion is rotatable about one point of a center axis of the hole.   The image forming apparatus according to claim 1, wherein the hole is disposed in the support member.

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