JP2013088491A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of preventing the variation of a gap between a photoreceptor and a developing roll, when a developing device including a plurality of developing rolls is used.SOLUTION: A force is applied to a developing device 175 by the elastic force of a spring 59 in the direction of an arrow A2, so that a butting part 56 is pressed and brought into contact with a butting part 58. In this state, the force is further applied to the developing device 175 by the elastic force of the spring 59 in the direction of the arrow A2, so that the developing device 175 is rotated around a contact position P1 between the butting part 56 and the butting part 58 as a rotation center in the direction of an arrow A3 and a butting part 57 is pressed and brought into contact with the butting part 58 by the rotation.

Description

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

  In an image forming apparatus that performs an image forming process using an electrophotographic method, a technique using a developing device including a plurality of developing rolls has been proposed. In such an apparatus using a plurality of developing rolls, the gap between the photosensitive member and each developing roll varies due to the floating of the separating member between the photosensitive member and each developing roll. This variation may cause problems such as image quality degradation. In order to avoid this, in Patent Document 1, in a developing device having two developing rolls, one developing roll is supported in a pendulum manner with the other developing roll as a rotation center, and the two developing rolls are There has been proposed a technique for preventing the separation member between the photosensitive member and the developing roll from being lifted by bringing each member close to the photosensitive member by a pressure spring independently.

JP 2002-351111 A

  SUMMARY An advantage of some aspects of the invention is that it provides a technique for suppressing a variation in a gap between an image carrier and a developing roll when a developing device including a plurality of developing rolls is used.

  According to a first aspect of the present invention, there is provided a developing device, wherein the image holding member is rotatably provided in the case along a rotation direction of a casing forming an outer shape of the developing device and a cylindrical image holding member. A first developing roll and a second developing roll for developing the electrostatic latent image formed on the surface, and an axial direction of the image holding member provided at both axial ends of the first developing roll of the housing A first abutting portion that is abutted against a third abutting portion provided at both ends; and an axially opposite end of the second developing roll of the housing; and an axially opposite end of the image carrier. A second abutting portion that abuts against the provided fourth abutting portion; and the third abutting portion after the first abutting portion is abutted against the third abutting portion. And applying a force in a direction in which the housing rotates with the contact position between the first abutting portion and the first abutting portion as a rotation center, Characterized by abutting a pressing means for pressing a portion of the provided.

In the developing device according to claim 2 of the present invention, in the developing device, the pressing means is configured to cause the casing to be elastically applied when the third abutting portion and the first abutting portion are in contact with each other. It is a member which pushes.
In the developing device according to claim 3 of the present invention, in the developing device, the direction of the force by the pressing means is viewed from a contact position between the third abutting portion and the first abutting portion, The direction is inclined toward the contact position between the fourth abutting portion and the second abutting portion.

  According to a fourth aspect of the present invention, there is provided an image forming device comprising the developing device and the image carrier that forms an image on a recording medium using a developer supplied by the developing device. It is characterized by that.

According to the first and fourth aspects of the present invention, there is provided a pressing means for applying a force in a direction in which the casing rotates with the contact position between the third abutting portion and the first abutting portion as a rotation center. Compared with the case where the image carrier is not, the variation in the gap between the image carrier and each developing roll is suppressed.
According to the second aspect of the present invention, the configuration of the apparatus is simplified as compared with the case where the pressing member is not a member that presses the casing by elastic force.
According to the third aspect of the present invention, the direction of the force by the pressing means is not the direction inclined toward the contact position between the fourth abutting portion and the second abutting portion. And variation in the gap between the developing rolls.

2 is a block diagram illustrating an example of a hardware configuration of an image forming apparatus. FIG. 2 is a diagram illustrating an example of a configuration of an image forming unit. FIG. It is a figure which shows the structure of a developing device, a photoreceptor, and a support mechanism. It is a figure which shows the one part outline of a developing device, a photoreceptor, and a support mechanism. It is sectional drawing seen from the arrow IV-IV direction in FIG. 3A. It is a figure which shows the operation | movement by a support mechanism. It is a figure which shows the structure of the image development apparatus by the modification (1), a photoreceptor, and a support mechanism. It is a figure which shows the structure of the image development apparatus by the modification (2), a photoreceptor, and a support mechanism. It is a figure which shows the structure of the image development apparatus by the modification (5), a photoreceptor, and a support mechanism.

<Configuration>
FIG. 1 is a block diagram showing an example of the configuration of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 is an apparatus that forms an image by an electrophotographic method, and corresponds to an example of an image forming apparatus according to the present invention. The image forming apparatus 1 includes an image forming function for forming an image on a recording medium such as a sheet, a copying function for copying an image, and an image formed on the recording medium in accordance with data sent from another computer such as a personal computer. A scanning function for reading
The functions provided in the image forming apparatus 1 are not limited to these functions, and may include, for example, a facsimile function. Further, the image forming apparatus 1 is not limited to the one having all the functions described above. For example, the image forming apparatus 1 may have a configuration having an image forming function and a copying function and not having other functions. The recording medium on which an image is formed by the image forming apparatus 1 is not limited to paper, and may be a transparent synthetic resin sheet such as an OHP (Over-Head Projector) sheet. Other materials may be used.

  As illustrated, each part of the image forming apparatus 1 is connected to a bus 11, and data is exchanged between each part via the bus 11. In the figure, the control unit 12 includes a CPU (Central Processing Unit) 121, a ROM (Read Only Memory) 122, and a RAM (Random Access Memory) 123, and forms an image according to a computer program stored in the ROM 122 or the storage unit 13. The apparatus 1 is controlled. The storage unit 13 is a storage unit such as a hard disk, and stores various programs such as a program related to the control of the image forming apparatus 1. The UI unit 14 includes a liquid crystal display that functions as a touch panel, and the user of the image forming apparatus 1 performs various operations by touching the liquid crystal display. The communication unit 18 is connected to the communication line 2 with a communication cable, and performs data communication with other devices connected to the communication line 2. Examples of the communication line 2 include a telephone line and a LAN (Local Area Network).

  The image reading unit 15 includes an optical system member (not shown), optically reads an image formed on a recording medium, and generates image data representing the read image. The image processing unit 16 performs various types of image processing such as color correction and gradation correction on the image represented by the input image data, and yellow (Y), magenta (M), cyan (from the image processed image). C) Image data of each color image of black (B) is generated, and the generated image data is output to the image forming unit 17. The image processing unit 16 is configured by an integrated circuit such as an ASIC (Application Specific Integrated Circuit).

The image forming unit 17 forms an image on a recording medium by electrophotography. The image forming unit 17 corresponds to an example of an image forming unit according to the present invention. FIG. 2 is a diagram illustrating an example of the configuration of the image forming unit 17. In the figure, cylindrical photoconductors 171Y, 171M, 171C, and 171K are photoconductors each having a photoconductive layer such as an organic photosensitive material formed on the surface thereof. The chargers 172Y, 172M, 172C, and 172K apply charges to the surfaces of the photoconductors 171Y, 171M, 171C, and 171K with a charging bias in which AC (alternating current) and DC (direct current) are superimposed, and uniformly charge them. It is a charger. The exposure device 173 is an exposure device including a beam emission source such as a laser diode. The exposure unit 173 exposes the photoconductors 171Y, 171M, 171C, and 171K according to the image data supplied from the image processing unit 16, and forms electrostatic latent images on the surfaces of the photoconductors 171Y, 171M, 171C, and 171K. To do.
The photoreceptors 171Y, 171M, 171C, and 171K correspond to an example of the image carrier according to the present invention.

The toner cartridges 174Y, 174M, 174C, and 174K contain developers of yellow, magenta, cyan, and black, respectively, and supply them to the developing devices 175Y, 175M, 175C, and 175K as necessary. The developer used in the image forming apparatus 1 is a so-called two-component developer composed of toner (colored particles) finally attached to a sheet and powder as a carrier for charging the toner. The developing devices 175Y, 175M, 175C, and 175K form toner images by attaching toner to the electrostatic latent images formed on the surfaces of the photoreceptors 171Y, 171M, 171C, and 171K, respectively. The primary transfer rolls 176Y, 176M, 176C, and 176K face the photoconductors 171Y, 171M, 171C, and 171K through the intermediate transfer belt 177, respectively, and transfer the toner images to the intermediate transfer belt 177 at the facing positions. The intermediate transfer belt 177 holds the toner images transferred by the primary transfer rolls 176Y, 176M, 176C, and 176K, respectively. The intermediate transfer belt 177 is supported by a plurality of support rolls 178 and moves while circling in a direction indicated by an arrow A1 in the drawing. The secondary transfer roll 179 transfers the toner image transferred to the intermediate transfer belt 177 to the conveyed recording medium.
In the following description, for convenience of description, when it is not necessary to distinguish the photoreceptors 171Y, 171M, 171C, and 171K, they are referred to as “photoreceptors 171”. Further, when it is not necessary to distinguish the developing devices 175Y, 175M, 175C, and 175K, they are referred to as “developing devices 175”.

  In the image forming apparatus 1 according to the present embodiment, the developing device 175 can be replaced with the image forming apparatus 1. That is, the developing device 175 is pulled out in the longitudinal direction of the developing device 175 by opening a door (not shown) formed in the housing of the image forming device 1 to release the support of the developing device 175. On the other hand, when the developing device 175 is mounted, the developing device 175 is inserted into the space from which the developing device 175 has been removed and the door is closed, whereby a support mechanism described later operates and the developing device 175 is attached to the image forming apparatus 1. Installed.

  The transport roll 180 transports the recording medium to the secondary transfer roll 179. The transport roll 180 transports a recording medium stored in a storage unit (not shown) that stores the recording medium, or transports a recording medium inserted by a user. The fixing device 181 fixes the toner image on the recording medium by heating and pressing the recording medium on which the toner image is transferred by the secondary transfer roll 179.

FIG. 3A is a diagram showing a configuration of the developing device, the photosensitive member, and the support mechanism, and FIG. 4 is a cross-sectional view seen from the direction of arrows IV-IV in FIG. 3A.
The housing 175A of the developing device 175 is formed of a material such as ABS resin, for example. In the casing 175A, a developer accommodating portion 50 that accommodates a developer (toner) is formed. In the housing 175A, the developing roll 51 and the developing roll 52 are provided at positions where their rotational axes are substantially parallel. An opening for exposing the developing rolls 51 and 52 is formed at a position facing the photoreceptor 171 in the housing 175A. The casing 175A is provided with developer agitating / conveying members 53 and 54 for conveying the toner in the developing container 50 to the developing rolls 51 and 52. The developing device 175 is provided on the surface of the developing rolls 51 and 52. The toner inside is formed and held in a thin layer having a substantially uniform thickness.

In the developing device 175, the developer accommodated in the developer accommodating portion 50 is conveyed to the developing rolls 51 and 52 by the developer agitating and conveying members 53 and 54 provided inside the developing container. Development is performed by supplying toner to the electrostatic latent image formed on the photoreceptor 171 via the developing roll 52. In this embodiment, since the photoconductor 171 rotates in the direction of arrow A14, after the toner conveyed by the second developing roller 52 adheres to the electrostatic latent image on the surface of the photoconductor 171, the first development is further performed. The developer conveyed by the roll 51 adheres to the electrostatic latent image on the surface of the photoreceptor 171.
The developing roll 51 corresponds to an example of a first developing roll according to the present invention, and the developing roll 52 corresponds to an example of a second developing roll according to the present invention.
In the following description, for convenience of explanation, the developing roll 52 is referred to as an upstream developing roll, and the developing roll 51 is referred to as a downstream developing roll.

  As shown in FIG. 4, the rotating shafts 51A, 52A of the developing rolls 51, 52 are rotatably supported by the housing 175A of the developing device 175 by bearings 55, 55,. On one end side of the developing roll 51 and the developing roll 52, gears 511 and 521 for providing a rotational driving force to the developing rolls 51 and 52 are provided, and these gears 511 and 521 are driven by a motor (not shown). By being driven, each developing roll 51, 52 rotates.

Next, the support mechanism of the developing device 175 will be described. The support mechanism includes a first abutting portion 56, a second abutting portion 57, a third abutting portion 58, and a spring 59.
As shown in FIG. 4, the first abutting portions 56, 56 are formed in the housing 175 </ b> A located at both axial ends of the first developing roll 51. As shown in FIGS. 3A and 3B, the first abutting portion 56 has a semicircular contact portion 56 </ b> A formed at a portion facing the photoconductor 171. The first abutting portion 56, together with the third abutting portion 58 on the photoconductor 171 side, secures a gap between the photoconductor 171 and the first developing roll 51. The first abutting portions 56 and 56 correspond to an example of a first abutting portion according to the present invention.
As shown in FIG. 4, the second abutting portions 57, 57 are formed on the housing 175 </ b> A located at both axial ends of the second developing roll 52. As shown in FIGS. 3A and 3B, the second abutting portion 57 is formed with a fan-shaped contact portion 57 </ b> A at a portion facing the photoconductor 171. The second abutting portion 57, together with the third abutting portion 58 on the photoconductor 171 side, secures a gap between the photoconductor 171 and the second developing roll 52. The second abutting portions 57 and 57 correspond to an example of a second abutting portion according to the present invention.
The third abutting portions 58 and 58 are provided at portions that support the photoconductor 171 located at both axial ends of the photoconductor 171. As shown in FIGS. 3A and 3B, the third abutting portion 58 is formed with a fan-shaped contact portion 58A at a portion facing the developing rolls 51 and 52, and the first abutting portion of the contact portion 58A. A raised portion 58 </ b> B protruding outward in the radial direction is formed in a portion facing 56. The raised portion 58B has a shape that gradually extends in the radial direction from the arc of the fan toward the side facing the first abutting portion 56. The third abutting portion 58 corresponds to an example of a third abutting portion according to the present invention.
As shown in FIG. 3A, the points where the first abutting portion 56 and the third abutting portion 58 are in contact are the first contact position P1, the second abutting portion 57 and the third abutting portion 58. A point where the two come into contact with each other is defined as a second contact position P2.

  When the developing device 175 is attached to the image forming apparatus 1, the contact portion 56 </ b> A of the first abutting portion 56 is formed by the raised portion 58 </ b> B formed in the third abutting portion 58. The third abutting portion 58 contacts before the contact portion 57A. Furthermore, by forming the contact portion 56A of the first abutting portion 56 in a semicircular shape, the area of the contact position P1 becomes smaller than when the contact portion 56A is formed in a fan shape.

  As shown in FIG. 3A, the spring 59 is a pressing unit that applies a force in the direction of the arrow A2 to the housing 175A of the developing device 175. The direction of the arrow A2 is a direction in which force is applied in the direction in which the housing 175A rotates around the first contact position P1. In the case of this embodiment, the direction of the force of the spring 59 is a direction applied to the outside of the second contact position P2 when viewed from the first contact position P1. In the drawing, the spring 59 is illustrated as being in direct contact with the housing 175A, but in reality, a force is applied via a member covering the housing 175A. Furthermore, a plurality of springs 59 may be provided along the longitudinal direction of the housing 175A.

  FIG. 5 is a diagram illustrating an operation by the support mechanism. When the distance r1 is between the arrow A2 indicating the direction of the force of the spring 59 and the contact position P1, and the distance r2 is between the contact positions P1 and P2, r1> r2. That is, the direction of the force by the spring 59 acts on the outside of the second contact position P2 when viewed from the first contact position P1.

FIG. 5 shows a state before the second abutting portion 57 is abutted against the third abutting portion 58, and FIG. 3A shows the second abutting portion 57 abutted against the third abutting portion 58. Indicates the state.
At the stage where the developing device 175 is inserted into the image forming apparatus 1, the force by the spring 59 does not act on the developing device 175. Depending on the shape of the first abutting portion 56, the second abutting portion 57, and the third abutting portion 58, the first abutting portion 56 and the third abutting portion 58 may be connected to the second abutting portion. Contact is made before contact between the portion 57 and the third abutting portion 58. At this time, a gap S1 is formed between the contact portion 57A of the second abutment portion 57 and the contact portion 58A of the third abutment portion 58. In the example shown in FIG. 5, the gap S <b> 1 between the third abutting portion 58 and the second abutting portion 57 is illustrated to be larger than actual in order to facilitate understanding of the description. .

  Thereafter, when the force of the spring 59 is generated, for example, by closing the door, a force is generated to push the developing device 175 in the direction of the arrow A2. The developing device 175 that has received the force rotates in the direction of the arrow A3 with the contact position P1 previously contacted as the rotation center, and the contact portion 57A is pressed against and contacts the contact portion 58A.

  The first abutting portions 56, 56 provided at both ends in the axial direction of the developing roll 51 and the third abutting portions 58, 58 provided at both ends in the axial direction of the photosensitive member 171 are arranged on the photosensitive member 171 (developing roll). 51) at two points on both ends in the axial direction. The second abutting portions 57 and 57 provided at both ends in the axial direction of the developing roll 52 and the third abutting portions 58 and 58 provided at both ends in the axial direction of the photosensitive member 171 are provided on the photosensitive member 171 ( Contact is made at two points on both ends in the axial direction of the second developing roll 52). That is, the third abutting portion 58 contacts the first abutting portion 56 and the second abutting portion 57 at a total of four points. Here, since the developing roll 51 and the developing roll 52 are fixed to a flexible casing 175A, some distortion is allowed. When the housing 175A receives a force from the spring 59, the housing 175A is slightly distorted. As a result, the contact portions 57A located at both axial ends of the developing roll 52 are pressed against and contact the contact portions 58A. . Here, the allowable distortion in the housing 175A includes the shaft connecting the two contact points between the first abutting portion 56 and the third abutting portion 58, the second abutting portion 57, and the third abutting portion. The distortion is such as to allow torsion between the contact point 58 and the shaft connecting the two contact points.

  As described above, in this embodiment, the first abutting portion 56 of the developing roll 51 is brought into contact with the third abutting portion 58 of the photoconductor 171 before the second abutting portion 57 of the developing roll 52. After that, the developing device 175 is rotated with the first contact position P1 between the first abutting portion 56 and the third abutting portion 58 as the center of rotation, and the second abutting portion 57 is moved to the third abutting portion. Press against the contact 58 to make contact. That is, the four points to be abutted against the photoconductor 171 are decomposed into “two points to be abutted first and two points to be abutted later”, and pressure is applied in a multistage and efficient manner. By doing so, it is possible to prevent a part of the first abutting portion 56 and the second abutting portion 57 from floating from the third abutting portion 58 of the photosensitive member 171, and the developing rolls 51 and 52. And the occurrence of variation in the gap between the photosensitive member 171 and the photosensitive member 171.

  Further, in the present embodiment, the direction of the force by the spring 59 is directed outward from the second contact position P2 when viewed from the first contact position P1, and therefore the spring 59 having the contact position P1 as the rotation center. The moment by the force of is secured. As a result, the developing device 175 can be rotated with a small force compared to the case where no force is generated in this direction.

<Modification>
(1) Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented in various other forms. An example is shown below. In addition, you may combine each following aspect suitably.
In the above-described embodiment, after the first abutting portion 56 is brought into contact with the third abutting portion 58, the developing device 175 is rotated to bring the second abutting portion 57 into contact with the third abutting portion 58. Although the supporting mechanism is illustrated as an example, the present invention is not limited to this, and after the second abutting portion 57 is brought into contact with the third abutting portion 58, the first abutting portion 56 is changed to the third abutting portion 58. You may make it contact.
The configuration in this case is shown in FIG. The configuration shown in FIG. 6 is different from the configuration shown in FIG. 3A in that the shape of the abutment portions 560B, 570B, and 580B is different from the direction of the elastic force of the spring 59B. This is the same as that shown in FIG. 3A described above. Therefore, in the following description, the same components as those shown in FIG. 3A are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

In FIG. 6, the shape of the first abutting portion 560 is the same as the shape of the second abutting portion 57 according to the above-described embodiment, and the shape of the second abutting portion 570 is the first abutting portion. The shape of the third abutting portion 580 is the same as the shape obtained by inverting the third abutting portion 58.
That is, the first abutting portion 560 is formed with a fan-shaped contact portion 560A at a portion facing the photoreceptor 171 and the second abutting portion 570 is a semicircular contact with a portion facing the photoreceptor 171. Part 570A is formed. The third abutting portion 580 is formed with a fan-shaped contact portion 580A at a portion facing the developing rolls 51 and 52, and further, a portion of the contact portion 580A facing the second abutting portion 570 is radially outward. A raised portion 580B that protrudes is formed.

The direction of the force of the spring 59B is directed to the arrow A4 direction. That is, the direction of the force of the spring 59B is directed to the first contact position P1 side when viewed from the second contact position P2.
Even in the support mechanism configured as described above, after the second abutting portion 570 is brought into contact with the third abutting portion 580, the developing device 175 is rotated about the second contact position P2. Then, the first abutting portion 560 is pressed against and contacted with the third abutting portion 580. Thereby, the dispersion | variation in the space | gap of the developing rolls 51 and 52 and the photoreceptor 171 is suppressed.

(2) In the above-described embodiment, the shape of the abutting portions 56, 57, 58 is shown in FIG. 3A, but the shape of the abutting portions 56, 57, 58 is not limited to this. Other shapes may be used. Specifically, for example, the shape shown in FIG. In the example shown in FIG. 7, both the abutting portions 561 and 571 are formed with fan-shaped contact portions 561 </ b> A and 571 </ b> A at portions facing the abutting portion 581. Further, the third abutting portion 581 has a fan-shaped contact portion 581 </ b> A formed at a portion facing the developing rolls 51 and 52. The direction of the force generated from the spring 59C is a direction in which the abutting portion 561 abuts against the abutting portion 581 before the abutting portion 571, and the developing roller 52 is applied to the photosensitive member 171 with the contact position P1 as the rotation center. It is provided in a direction that rotates in the approaching direction.
In addition, the shape of the abutting portion 561 and the abutting portion 581 is such that at least one of the abutting portion 561 and the abutting portion 581 is convex so that the area of the contact position serving as the rotation center is reduced. Also good. Further, in order to prevent the contact position between the abutting portion 561 and the abutting portion 581 from shifting when rotating, the direction of the drag force from the abutting portion 581 and the direction of the elastic force of the spring are not close to perpendicular. Such a shape may be used.

(3) In the above-described embodiment, the spring 59 is provided in the position and orientation shown in FIG. 3A. However, the position and orientation of the spring 59 is not limited to this, and is provided in other positions and orientations. Also good. Specifically, for example, the spring 59D (shown by a chain line in FIG. 3A) may be provided at a position and orientation. In short, in the spring and the developing device, the direction of the elastic force of the spring is a direction in which the abutting portion 56 abuts against the abutting portion 58 before the abutting portion 57, and the first contact position P1 is set. It is only necessary that the developing roll 52 is provided so as to rotate in a direction approaching the photoconductor 171 as the rotation center.
In addition, the direction of the force of the spring 59D is such that the direction of the drag force from the abutment portion 58 and the force of the spring 59D are prevented from shifting when the contact position between the abutment portion 56 and the abutment portion 58 rotates. The direction may be such that the direction is not close to perpendicular.

(4) In the above-described embodiment, the spring 59 is used as the pressing unit that presses the developing device 175 against the photoconductor 171. However, the pressing unit is not limited to the spring. For example, the developing device is driven by a motor. The pushing mechanism may move the developing device 175 around the contact position P1 between the first abutting portion 56 and the third abutting portion 58 as a center of rotation. Any device may be used as long as it applies force to the.

(5) In the above-described embodiment, the first abutting portion 56 and the third abutting portion 58 are brought into contact with the developing device 175 by the elastic force of the spring 59 and the second abutting portion 57 is contacted. And the third abutting portion 58 may be moved to a position where they do not come into contact with each other. In other words, the pressing means (including a spring and a driving mechanism) is configured such that the developing device 175 contacts the first abutting portion 56 and the third abutting portion 58 and the second abutting portion 57 and the second abutting portion 57. 3 is moved to a position where it does not come into contact with the abutment portion 58 (hereinafter referred to as “first operation”), and a force is applied in the direction of rotation about the contact position P1 as a rotation center (hereinafter referred to as “second operation”). , Two operations may be performed.

  As another aspect, the first operation is performed (the developing device 175 is configured such that the first abutting portion 56 and the third abutting portion 58 are in contact with each other, and the second abutting portion 57 and the third abutting portion 57 are in contact with each other). Moving means for moving to a position where it does not come into contact with the abutting portion 58 and pushing means for performing the second operation (applying a force in the direction of rotation about the contact position P1) as separate bodies. It is good also as a structure to provide. Specifically, for example, as shown in FIG. 8, a spring 59E is provided as a moving means for performing the first operation, and a spring 59F is provided as a pressing means for performing the second operation. After the first operation is performed by applying force in the direction of arrow A5 to the body 175A, the spring 59F performs the second operation by applying force in the direction of arrow A6 to the housing 175A. Also good. The moving means for performing the first operation is not limited to a spring, and may be, for example, a guide rail or a drive mechanism driven by a motor. The developing device 175 is connected to the first abutting portion 56 and the first abutting portion. Any one may be used as long as it moves to a position where the third abutting portion 58 contacts and the second abutting portion 57 does not contact the third abutting portion 58.

(6) In the above-described embodiment, the developing device 175 provided with the two developing rolls 51 and 52 has been described. However, the number of developing rolls provided in the developing device is not limited to two and may be larger than this. Even in this case, as in the above-described embodiment, after the abutting portion of the first developing roll is abutted against the abutting portion of the photosensitive member, the developing device is rotated about the abutting position as the rotation center. Thus, the abutting portion of the other developing roll may be abutted against the abutting portion of the photosensitive drum. By doing so, variation in the gap between the photoconductor and the developing roll is suppressed.
In the above-described embodiment, the abutting portion 56 is formed in the housing 175A and does not rotate with the rotation of the first developing roll 51. However, the configuration is not limited thereto, and the first developing roll 51 is not limited thereto. A cylindrical member that rotates with the rotation may be used. The same applies to the abutting portions 57 and 58, and a cylindrical member that rotates with the rotation of the second developing roll 52 or the photoreceptor 171 may be used.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 16 ... Image processing part, 17 ... Image forming part, 51, 52 ... Developing roll, 53, 54 ... Developer stirring conveyance member, 56, 56B, 56C, 57, 57B, 57C, 58, 58B , 58C: abutting portion, 59, 59B, 59C, 59D, 59E, 59F ... spring, 171 ... photoconductor, 175 ... developing device

Claims (4)

A housing forming the outer shape of the developing device;
A first developing roller and a second developing roller that are rotatably provided on the casing along the rotation direction of the cylindrical image carrier surface, and develop the electrostatic latent image formed on the surface of the image carrier. Roles,
A first abutting portion that is provided at both axial ends of the first developing roll of the housing and is abutted against third abutting portions provided at both axial ends of the image carrier;
A second abutting portion that is provided at both axial ends of the second developing roll of the housing and abuts against fourth abutting portions provided at both axial ends of the image carrier;
After the first abutting part is abutted against the third abutting part, the housing rotates with the contact position between the third abutting part and the first abutting part as a rotation center. And a pressing unit that applies a force in a direction to press the second abutting part against the fourth abutting part. The developing device according to claim 1, wherein the pressing unit is a member that presses the housing by an elastic force when the third abutting portion and the first abutting portion come into contact with each other. apparatus. The direction of the force by the pressing means is determined between the fourth abutting portion and the second abutting portion when viewed from the contact position between the third abutting portion and the first abutting portion. The developing device according to claim 1, wherein the developing device is inclined toward the contact position. 4. An image forming unit comprising: the developing device according to claim 1; and the image holding member that forms an image on a recording medium using a developer supplied by the developing device. An image forming apparatus.

Images