Developing device and image forming device

Abstract

To generate pressing force with which a developing unit is pressed against a photoreceptor drum by a simple configuration as compared with a configuration using a member that generates the pressing force with which the developing unit is pressed against the photoreceptor drum.SOLUTION: The developing device comprises: a photoreceptor drum 31; a developing unit 33 having a developing roll 332 for supplying a developer to the photoreceptor drum 31 on which an electrostatic latent image has been formed; a support member 50 for retractably supporting the developing unit 33 with respect to the photoreceptor drum 31; a contact support part 312 and a contact part 33a which are provided at edges on the photoreceptor drum 31 side of the support member 50, and which respectively serve as a first positioning part for positioning the developing unit 33, and a second positioning part for positioning the developing unit 33 while holding a predetermined clearance between the developing roll and the photoreceptor drum 31, with the developing unit 33 positioned by the first positioning part and fallen to the photoreceptor drum 31 side.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a developing device and an image forming apparatus. [Background technology]

[0002] In an electrophotographic image forming apparatus, in order to ensure a high degree of accuracy in the gap (hereinafter, "clearance") between the image carrier and the developer carrier, the image carrier unit including the image carrier and the developer unit including the developer carrier are butted against each other to position and fix the developer unit. In order to prevent the clearance from fluctuating due to a reaction force when the developer is driven or an external force from another part of the image forming apparatus, there is a conventional technique in which the developer unit is pressed against the image carrier unit by the load of the developer unit itself.

[0003] Patent Document 1 discloses an image forming apparatus having a developer support member whose vertical movement is restricted but which can move left and right, a pressing force generating member which presses the developer against a photosensitive drum, and a tracking mechanism which maintains the distance between the photosensitive drum (image carrier) and the developing roll (developer carrier) at a predetermined value when a pressing force is applied by the pressing force generating member, in which when the photosensitive side member and the developing roll side member in the tracking mechanism are in contact with each other, the height of the center position of the photosensitive unit is positioned at or below the height of the developing roll, and the developing roll side tracking member presses the photosensitive side tracking member from above. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4655569 Summary of the Invention [Problem to be solved by the invention]

[0005] In a large image forming apparatus, the developing unit is large, and therefore the reaction force during driving is also large, so the mechanism for pressing the developing unit against the photosensitive drum against this reaction force during driving is complicated.

[0006] The present invention aims to generate a pressing force for pressing a developing unit against a photosensitive drum with a simpler configuration than a configuration that uses a member that generates a pressing force for pressing a developing unit against a photosensitive drum. [Means for solving the problem]

[0007] The present invention according to claim 1 is an image carrier unit having an image carrier; a developing unit having a developer carrier that supplies a developer to the image carrier on which an electrostatic latent image is formed; a support portion that supports the developing unit so as to be movable toward and away from the image carrier unit; a first positioning portion provided at an end of the support portion on the image carrier unit side and configured to position the developing unit; a second positioning portion that positions the developing unit by maintaining a predetermined gap between the developer carrier and the image carrier when the developing unit is positioned by the first positioning portion and is in a state of being tilted toward the image carrier unit; The developing device is characterized by comprising: The present invention according to claim 2 is the support portion has a guide path for guiding the developing unit, The first positioning portion is configured to incline an end of the guide path so that the image carrier unit side is lowered, and to have an abutment portion against which the developing unit abuts at a position where the guide path is inclined. The developing device according to claim 1 is characterized in that: The present invention according to claim 3 is The first positioning portion further includes a pressing member that restricts movement of the developing unit when the developing unit abuts against the abutting portion. The developing device according to claim 2 is characterized in that: The present invention according to claim 4 is the guide path of the support portion includes two rails arranged in parallel along a direction in which the developing unit advances and retreats, The first positioning portion is configured by inclining the ends of each of the two rails and having the abutment portion at one end of the two rails. The developing device according to claim 2 is characterized in that: The present invention according to claim 5 is the developing unit is not fixed on the rail that does not have the abutment portion, of the two rails in the first positioning portion; The developing device according to claim 4 is characterized in that: The present invention according to claim 6 is The support portion is a lower guide path that supports and guides a lower portion of the developing unit and has the first positioning portion; an upper guide path that supports and guides an upper portion of the developing unit; The developing unit is separated from the upper guide path in a state where the developing unit is positioned by the first positioning portion of the lower guide path, and falls toward the image carrier unit. The developing device according to claim 1 is characterized in that: The present invention according to claim 7 is The upper guide path of the support portion is switchable between a contact state in which the developer unit is supported and a retracted state in which the developer unit is separated from the developer unit, at least when the developer unit is in a position positioned by the first positioning portion of the lower guide path. The developing device according to claim 6 is characterized in that: The present invention according to claim 8 is the upper guide path of the support portion has two rails arranged in parallel along a direction in which the developing unit advances and retreats, One of the two rails in the upper guideway is switchable between the contact state and the retracted state, the other of the two rails in the upper guide path is shorter than the moving distance of the developing unit and does not come into contact with the developing unit when the developing unit is in a position positioned by the first positioning portion of the lower guide path; The developing device according to claim 7 is characterized in that: The present invention according to claim 9 is a drive mechanism for rotating a drive shaft of the developing unit to transmit a drive force to the developing unit, The drive mechanism is capable of changing the position of the axis of a joint portion that is connected to the drive shaft and rotates the drive shaft. The developing device according to claim 1 is characterized in that: The present invention according to claim 10 comprises: An image forming apparatus including the developing device according to any one of claims 1 to 9. Effect of the Invention

[0008] According to the invention of claim 1, the developer can be pressed against the photosensitive drum with a simple configuration that uses the weight of the developer unit, compared to a configuration that uses a member that generates a pressing force to press the developer against the photosensitive drum. According to the invention of claim 2, since the developing unit is positioned by its own weight, the structure can be simplified compared to a structure in which a mechanism for fixing the developing unit is provided. According to the invention of claim 3, the movement of the developing unit can be more reliably regulated compared to a configuration in which the movement of the developing unit is regulated only by the inclination of the guide path and the abutting portion. According to the invention of claim 4, a simpler configuration can be achieved compared to a configuration in which each rail has an abutment portion. According to the invention of claim 5, the positioning of the developer unit can be facilitated and the load on the developer unit and the first positioning portion can be reduced, compared to a configuration in which the developer unit is fixed on each rail. According to the invention of claim 6, since the developing unit is positioned by its own weight, the structure can be simplified compared to a structure in which a mechanism for fixing the developing unit is provided. According to the seventh aspect of the present invention, the developer unit can be prevented from tipping over, as compared to a configuration in which the upper guide path does not support the developer unit in the first positioning portion. According to the invention of claim 8, a simpler configuration can be achieved compared to a configuration in which each rail is switchable between a contact state and a retracted state. According to the invention of claim 9, it is possible to accommodate deviations in the axis due to individual differences in developing units and changes over time, compared to a configuration in which the axis position of the drive mechanism is fixed. According to the invention of claim 10, in a developing device provided in an image forming apparatus, the developing device can be pressed against the photosensitive drum with a simple configuration that uses the load of the developing device unit, compared to a configuration that uses a member that generates a pressing force to press the developing device against the photosensitive drum. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an image forming apparatus to which the present embodiment is applied. [Diagram 2] FIG. 2 is a diagram showing an internal configuration of a developing unit. [Diagram 3] FIG. 2 illustrates an example of the configuration of an image forming unit. [Figure 4] FIG. 2 is a diagram showing the overall configuration of a developing unit. [Diagram 5] These are schematic diagrams showing the support structure of the developing unit, where Figure 5(A) shows the support structure on the front side of the lower support roll, Figure 5(B) shows the support structure on the rear side of the lower support roll, Figure 5(C) shows the support structure on the front side of the upper support roll, and Figure 5(D) shows the support structure on the rear side of the upper support roll. [Figure 6] 6A and 6B are diagrams illustrating a state in which the developing unit is retracted, with FIG. 6A illustrating the state on the front side and FIG. 6B illustrating the state on the rear side. [Figure 7] 7A and 7B are diagrams illustrating a state in which the developing unit is moving from a retracted position to a set position, with FIG. 7A illustrating the state on the front side and FIG. 7B illustrating the state on the rear side. [Figure 8]8A and 8B are diagrams illustrating a state in which the movement of the developing unit to the set position has been completed, with FIG. 8A illustrating the state on the front side and FIG. 8B illustrating the state on the rear side. [Figure 9] 9A and 9B are diagrams showing a state in which the developing unit is set, with FIG. 9A showing the front side and FIG. 9B showing the rear side. [Figure 10] FIG. 2 is a diagram showing a driving mechanism of the developing unit. [Figure 11] 11A and 11B are diagrams showing an adjustment procedure for the axis center of a drive mechanism for a developing unit, in which FIG. 11A shows a first state and FIG. 11B shows a second state. [Figure 12] 12A and 12B are diagrams showing an adjustment procedure for the axis center in the drive mechanism of the developing unit, FIG. 12A showing a third state, and FIG. 12B showing a fourth state. [Figure 13] 13A and 13B are diagrams showing an adjustment procedure for the axis center of the drive mechanism of the developing unit, with FIG. 13A showing a fifth state and FIG. 13B showing a sixth state. [Figure 14] 14A and 14B are diagrams showing an adjustment procedure for the axis center of the drive mechanism of the developing unit, with FIG. 14A showing a seventh state and FIG. 14B showing an eighth state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Configuration of Image Forming Apparatus> 1 is a diagram illustrating an image forming apparatus 1 to which this embodiment is applied. The image forming apparatus 1 according to this embodiment includes a paper feed unit 1A, a printing unit 1B, and a paper discharge unit 1C. The paper feed unit 1A includes a first paper storage section 11 to a fourth paper storage section 14 that store paper P as an example of a recording medium. The paper feed unit 1A also includes feed rolls 15 to 18 that are provided corresponding to the first paper storage section 11 to the fourth paper storage section 14, respectively, and that feed paper P stored in each paper storage section to a transport path connected to the printing unit 1B.

[0011] The printing unit 1B includes an image forming section 20 that forms an image on paper P. The printing unit 1B also includes a control section 21 that controls each section of the image forming device 1. The printing unit 1B also includes an image processing section 22. The image processing section 22 performs image processing on image data transmitted from the image reading device 4 and a personal computer (PC) 5. The printing unit 1B also includes a UI (User Interface) 23 that is composed of a touch panel or the like and that notifies the user of information and accepts information input from the user.

[0012] Image forming section 20, which is an example of an image forming means, is provided with six image forming units 30T, 30P, 30Y, 30M, 30C, and 30K (hereinafter, sometimes simply referred to as "image forming units 30") that are arranged in parallel at regular intervals. Each image forming unit 30 is provided with a photoconductor drum 31 on which an electrostatic latent image is formed while rotating in the direction of arrow A, a charging roll 32 that charges the surface of photoconductor drum 31, a developing device 33 that develops the electrostatic latent image formed on photoconductor drum 31, and a drum cleaner 34 that removes toner and the like from the surface of photoconductor drum 31.

[0013] The image forming section 20 is also provided with an exposure device 26 that exposes the photoconductor drum 31 of each image forming unit 30 with laser light. The exposure of the photoconductor drum 31 by the exposure device 26 is not limited to using laser light. For example, a light source such as an LED (Light Emitting Diode) may be provided for each image forming unit 30, and the photoconductor drum 31 may be exposed using light emitted from the light source.

[0014] Each image forming unit 30 is configured similarly, except for the toner contained in the developer 33. The image forming units 30Y, 30M, 30C, and 30K form toner images in yellow (Y), magenta (M), cyan (C), and black (K), respectively. The image forming units 30T and 30P form toner images using toner corresponding to the corporate color, foaming toner for Braille, fluorescent toner, toner for improving gloss, and the like. In other words, the image forming units 30T and 30P form toner images using toner of a special color.

[0015] The image forming section 20 is also provided with an intermediate transfer belt 41 onto which the toner images of each color formed on the photoconductor drums 31 of the image forming units 30 are transferred. The image forming section 20 is also provided with a primary transfer roll 42 that transfers the toner images of each color of the image forming units 30 onto the intermediate transfer belt 41 at a primary transfer section T1. The image forming section 20 is also provided with a secondary transfer roll 40 that collectively transfers the toner images transferred onto the intermediate transfer belt 41 onto the paper P at a secondary transfer section T2. ​​The image forming section 20 is also provided with a belt cleaner 45 that removes toner, etc. from the surface of the intermediate transfer belt 41, and a fixing device 80 that fixes the secondarily transferred image onto the paper P.

[0016] The image forming section 20 performs an image forming operation based on a control signal from the control section 21. Specifically, in the image forming section 20, first, image processing is performed by the image processing section 22 on the image data input from the image reading device 4 or the PC 5, and the image data after the image processing is supplied to the exposure device 26. Then, for example, in the magenta (M) image forming unit 30M, after the surface of the photoconductor drum 31 is charged by the charging roll 32, the exposure device 26 irradiates the photoconductor drum 31 with laser light modulated by the image data obtained from the image processing section 22.

[0017] As a result, an electrostatic latent image is formed on the photoconductor drum 31. The formed electrostatic latent image is developed by the developer 33, and a magenta toner image is formed on the photoconductor drum 31. Similarly, yellow, cyan and black toner images are formed in the image forming units 30Y, 30C and 30K, and special color toner images are formed in the image forming units 30T and 30P.

[0018] The color toner images formed in the image forming units 30 are sequentially electrostatically transferred onto an intermediate transfer belt 41 rotating in the direction of arrow C in Fig. 1 by a primary transfer roll 42, and superimposed toner images are formed on the intermediate transfer belt 41. The superimposed toner images formed on the intermediate transfer belt 41 are transported to a secondary transfer section T2 constituted by a secondary transfer roll 40 and a backup roll 49 as the intermediate transfer belt 41 moves.

[0019] On the other hand, the paper P is taken out of the first paper storage unit 11 by, for example, the delivery roll 15, and then transported to the position of the registration roll 74 via the transport path. When the superimposed toner image is transported to the secondary transfer unit T2, the paper P is supplied from the registration roll 74 to the secondary transfer unit T2 in accordance with the timing. Then, at the secondary transfer unit T2, the superimposed toner image is electrostatically transferred onto the paper P all at once due to the action of the transfer electric field formed between the secondary transfer roll 40 and the backup roll 49.

[0020] Thereafter, the paper P onto which the superimposed toner image has been electrostatically transferred is transported to the fixing device 80. In the fixing device 80, pressure and heat are applied to the paper P on which the unfixed toner image has been formed, and the toner image is fixed to the paper P. Then, the paper P which has undergone the fixing process passes through a curl correction section 81 provided in the paper discharge unit 1C, and is then transported to a paper stacking section (not shown).

[0021] <Configuration of Developer 33> Fig. 2 is a diagram showing the internal configuration of developing unit 33. Fig. 2 is a perspective view of developing unit 33 seen from the front side (the front side of the paper in Fig. 1) of printing unit 1B of image forming apparatus 1 shown in Fig. 1 toward the rear side (the rear side of the paper in Fig. 1), and is a cross-sectional view with the front side broken away.

[0022] The developing device 33 has a housing 331 that is adjacent to the photosensitive drum 31 and is configured to extend from the front side to the rear side of the printing unit 1B. The housing 331 has an opening 331a at a position facing the photosensitive drum 31. Inside the housing 331, a developing roll 332, a pickup roll 333, a first conveying section 334, a second conveying section 335, a third conveying section 336, a regulating member 337, and a removing member 338 are housed together with the developer. Each member inside the housing 331 is a long member having approximately the same length and is arranged approximately in parallel. The developer housed in the housing 331 is composed of a mixture of toner for forming an image and carrier, which is magnetic particles for transporting the toner. The developing device 33 is an example of a developing unit.

[0023] The developing roll 332 includes a cylindrical shaft member and a cylindrical sleeve that covers the shaft member. The developing roll 332 is disposed so that a part of the side surface is exposed from the opening 331a of the storage section 331, and the exposed surface faces the photosensitive drum 31. The shaft member of the developing roll 332 has a magnetic force, and the sleeve rotates around the shaft member in the direction of the arrow shown in the figure. The developing roll 332 attracts a developer onto the surface of the sleeve by the magnetic force of the shaft member, transports the developer to the opening 331a by rotating the sleeve, and develops an electrostatic latent image by attaching the toner to the charged photosensitive drum 31. The developing roll 332 is an example of a developer holder.

[0024] The pickup roll 333 is provided adjacent to and parallel to the developing roll 332. The pickup roll 333 includes a cylindrical shaft member and a cylindrical sleeve that covers the shaft member. The shaft member has a magnetic force, and the sleeve rotates around the shaft member. The pickup roll 333 attracts the developer onto the surface of the sleeve by the magnetic force of the shaft member, and conveys the developer by rotating the sleeve to transfer it to the developing roll 332.

[0025] The first conveying section 334, the second conveying section 335, and the third conveying section 336 are augers having spiral blades around a rotation axis. The first conveying section 334, the second conveying section 335, and the third conveying section 336 are arranged inside the storage section 331 with their rotation axes parallel to the developing roll 332 and the pick-up roll 333. By rotating the first conveying section 334, the second conveying section 335, and the third conveying section 336 around their respective rotation axes, the developer is agitated and conveyed in a direction along the rotation axis of each of the conveying sections 334 to 336. In addition, the developer is conveyed in the order of the first conveying section 334, the second conveying section 335, and the third conveying section 336 in accordance with the rotational operation of the first conveying section 334, the second conveying section 335, and the third conveying section 336, and is supplied from the third conveying section 336 to the pick-up roll 333.

[0026] The regulating member 337 is provided along the side surface of the developing roll 332, downstream of the position where the developing roll 332 faces the pickup roll 333, and upstream of the position where the developing roll 332 faces the photoconductor drum 31. Here, the downstream side and the upstream side refer to the downstream side and the upstream side in the rotation direction of the developing roll 332. The regulating member 337 scrapes off the developer supplied from the pickup roll 333 and held on the surface of the developing roll 332, and regulates it to a certain height. The developer scraped off by the regulating member 337 is collected inside the storage section 331 and returns to the transport path configured by the first transport section 334, the second transport section 335, and the third transport section 336.

[0027] The removing member 338 is provided along the side surface of the developing roll 332, downstream of the position where the developing roll 332 faces the photosensitive drum 31. The downstream side is the downstream side in the rotation direction of the developing roll 332. The removing member 338 scrapes off the developer remaining on the surface of the developing roll 332 after the developing roll 332 supplies the developer to the photosensitive drum 31. The developer scraped off from the developing roll 332 by the removing member 338 is collected inside the storage section 331 and returns to the transport path configured by the first transport section 334, the second transport section 335, and the third transport section 336.

[0028] <Configuration of Image Forming Unit 30> Fig. 3 is a diagram showing an example of the configuration of the image forming unit 30. Note that Fig. 3 shows the photosensitive drum 31, the developing device 33, and the drum cleaner 34, but does not show the charging roll 32. The photosensitive drum 31, the developing device 33, the drum cleaner 34, and the charging roll 32 (not shown) are arranged to extend from the front side to the rear side of the printing unit 1B.

[0029] As shown in Fig. 3, the photoconductor drum 31 and the developing device 33 are disposed adjacent to each other. More specifically, the photoconductor drum 31 and the developing device 33 are disposed such that the axial directions of the photoconductor drum 31 and the developing roll 332 (see Fig. 2) of the developing device 33 are parallel to each other, and a predetermined gap is maintained between the surface of the photoconductor drum 31 and the surface of the developing roll 332. The gap between the photoconductor drum 31 and the developing roll 332 is, for example, about 0.2 mm with a tolerance of 30 µm. The drum cleaner 34 is disposed on the opposite side of the developing device 33 across the photoconductor drum 31.

[0030] The photosensitive drum 31 is rotatably supported at both front and rear ends by drum holding parts 311. Each of the front and rear drum holding parts 311 is provided with a contact support part 312 used for positioning the developing device 33. FIG. 3 illustrates the contact support part 312 provided on the front drum holding part 311. The photosensitive drum 31 and the drum holding part 311 are an example of an image carrier unit. Note that, although the contact support part 312 is provided on each of the front and rear drum holding parts 311 here, it may be configured to be provided on only one of them.

[0031] The developing unit 33 is supported by a frame 330. Among the members constituting the frame 330, the members on the front side and the rear side are provided with contact portions 33a corresponding to the contact support portions 312 of the drum holding portion 311. In FIG. 3, the contact portion 33a provided on the front side is illustrated. Although described in detail later, the developing unit 33 is supported by the frame 330 and a support member 50 located under the developing unit 33 so as to lean toward the photosensitive drum 31 side. Then, as the developing unit 33 leans toward the photosensitive drum 31 side, the contact portion 33a hits the contact support portion 312 of the drum holding portion 311, and the developing unit 33 is positioned relative to the photosensitive drum 31. The developing unit 33 including the frame 330 is an example of a developing unit unit. The contact support portion 312 of the drum holding portion 311 and the contact portion 33a of the developing unit 33 are an example of a second positioning portion. In this embodiment, the contact portions 33a are provided on the front and rear sides of the frame 330, respectively. However, if the contact support portion 312 is provided on only one of the front and rear sides, the contact portions 33a may be provided on only one of the front and rear sides in correspondence with the contact support portion 312.

[0032] <Support structure of developing unit 33> FIG. 4 is a diagram showing the overall configuration of the developing device 33. Support rolls 330a, 330b for supporting the developing device 33 are provided at the lower and upper parts of a frame 330 supporting the developing device 33. The lower support roll 330a and the upper support roll 330b are placed on and supported by a supporting member 50 (see FIG. 3). As will be described in detail later, the supporting member 50 has rails for supporting the lower support roll 330a and the upper support roll 330b, respectively. The supporting member 50 has, for example, two rails for each of the lower support roll 330a and the upper support roll 330b, provided on the front side and the rear side of the printing unit 1B. The lower support roll 330a and the upper support roll 330b are placed on the rails of the supporting member 50, so that the developing device 33 can move along the rails of the supporting member 50. The supporting member 50 is an example of a supporting part.

[0033] In the illustrated example, the lower support roll 330a is provided at the lower right when viewed from the front side of the printing unit 1B, and the upper support roll 330b is provided at the upper left. More specifically, the lower support roll 330a is provided behind the center of gravity of the developing unit 33, with the side of the developing unit 33 facing the photosensitive drum 31 (see FIG. 3) being the front side. The upper support roll 330b is provided ahead of the center of gravity of the developing unit 33. The position of the upper support roll 330b is not limited to the position shown in FIG. 4, as long as it can stably support the developing unit 33 together with the lower support roll 330a. By providing the lower support roll 330a and the upper support roll 330b in this way, when the upper support roll 330b comes off the rail and the developing unit 33 is supported only by the lower support roll 330a behind the center of gravity, the developing unit 33 falls forward.

[0034] Fig. 5 is a diagram showing a schematic support structure of the developing device 33, Fig. 5(A) shows the support structure on the front side of the lower support roll 330a, Fig. 5(B) shows the support structure on the rear side of the lower support roll 330a, Fig. 5(C) shows the support structure on the front side of the upper support roll 330b, and Fig. 5(D) shows the support structure on the rear side of the upper support roll 330b. As shown in Figs. 5(A) to (D), rails are provided as the support member 50, one each on the front side and rear side of the lower support roll 330a, and one each on the front side and rear side of the upper support roll 330b. The rail corresponding to the front side of the lower support roll 330a shown in Figure 5(A) is the lower first support part 51, the rail corresponding to the rear side of the lower support roll 330a shown in Figure 5(B) is the lower second support part 52, the rail corresponding to the front side of the upper support roll 330b shown in Figure 5(C) is the upper first support part 53, and the rail corresponding to the rear side of the upper support roll 330b shown in Figure 5(D) is the upper second support part 54.

[0035] As shown in Fig. 5(A), the lower first support part 51 has an inclined part 51a at one end side that is inclined downward toward the tip, and a substantially horizontal retracted part 51b at the other end side. An abutting part 51c extending upward is formed at the tip of the inclined part 51a. The lower support roll 330a placed on the lower first support part 51 is located at the inclined part 51a (indicated by a solid line in Fig. 5(A)) during normal operation when an image is formed, and retracts to the retracted part 51b (indicated by a dashed line in Fig. 5(A)) when the developing device 33 is pulled out from the printing unit 1B for replacing parts or developer, etc.

[0036] When the lower support roll 330a is located at the inclined portion 51a, a force is applied to the lower support roll 330a downward (toward the tip end) along the inclination of the inclined portion 51a due to the load of the developing unit 33. The lower support roll 330a then abuts against an abutment portion 51c at the tip end of the inclined portion 51a and is positioned. In addition, in order to prevent the lower support roll 330a from moving backward in the direction up the inclination of the inclined portion 51a due to vibrations or the like during image formation, a pressing member 55 is attached to the lower first support portion 51 when the lower support roll 330a abuts against the abutment portion 51c, and the movement of the lower support roll 330a is restricted by the pressing member 55.

[0037] As shown in Fig. 5(B), the lower second support part 52 has an inclined part 52a at one end side that is inclined downward toward the tip, and has a substantially horizontal retracted part 52b at the other end side. The positions and lengths of the inclined part 52a and the retracted part 52b correspond to the inclined part 51a and the retracted part 51b of the lower first support part 51 described with reference to Fig. 5(A). The lower support roll 330a placed on the lower second support part 52 is located at the inclined part 52a (indicated by a solid line in Fig. 5(B)) during normal operation in which image formation is performed, and retracts to the retracted part 52b (indicated by a dashed line in Fig. 5(B)) when the developing device 33 is pulled out from the printing unit 1B for replacing parts or developer, etc.

[0038] The lower second support portion 52 is not provided with a configuration for restricting the movement of the lower support roll 330a, such as the abutting portion 51c and the pressing member 55 of the lower first support portion 51. Therefore, the lower support roll 330a can move on the inclined portion 52a of the lower second support portion 52 even during normal operation. In other words, the positioning of the lower support roll 330a by the lower second support portion 52 is performed only by placing the lower support roll 330a on the lower second support portion 52, and is looser than the positioning by the lower first support portion 51. This is to avoid excessive physical load on the developing unit 33. The positioning of the developing unit 33 during normal operation is performed at four points: the contact support portion 312 of the drum holding portion 311 and the contact portion 33a of the frame 330 of the developing unit 33, the lower first support portion 51, and the lower second support portion 52. Here, if the position is fixed at all four points, excessive physical load may be applied to the developing unit 33 due to vibration or load. Therefore, the lower support roll 330a is loosely positioned at the lower second support portion 52 to reduce the load acting on the developing unit 33. The lower first support portion 51 and the lower second support portion 52 are an example of a lower guide path and an example of a first positioning portion.

[0039] As shown in FIG. 5(C), the upper first support portion 53 has an inclined portion 53a at one end that is inclined downward toward the tip, and a substantially horizontal retracted portion 53b at the other end. An upwardly protruding support piece 53c is formed at the tip of the inclined portion 53a. The upper support roll 330b placed on the upper first support portion 53 moves to the position of the inclined portion 53a when the developing device 33 is set to a position during normal operation in which image formation is performed (shown by a solid line in FIG. 5(C)). When the developing device 33 is pulled out of the printing unit 1B for replacing parts or developer, the upper support roll 330b retracts to the retracted portion 53b (shown by a dashed line in FIG. 5(C)).

[0040] Moreover, the upper first support portion 53 is configured so that the inclined portion 53a and the support piece 53c can be retracted downward as shown by the dashed line in FIG. 5C. Specifically, for example, a rotation shaft (not shown) is provided under the retracted portion 53b, and the upper first support portion 53 is retracted by rotating the upper first support portion 53 in the direction of arrow D around the rotation shaft. When the upper first support portion 53 is retracted downward, the upper support roll 330b is removed from the upper first support portion 53. Although the details will be described later, during normal operation in which image formation is performed, the upper first support portion 53 is in a retracted state after positioning the upper support roll 330b at the inclined portion 53a. Hereinafter, the state of the upper first support portion 53 when the upper support roll 330b contacts the inclined portion 53a of the upper first support portion 53 will be referred to as the first state, and the state of the upper first support portion 53 when the upper first support portion 53 is retracted and separated from the upper support roll 330b will be referred to as the second state.

[0041] As shown in FIG. 5(D), the upper second support portion 54 is composed of a substantially horizontal portion. The position and length of the upper second support portion 54 correspond to the retracted portion 53b of the upper first support portion 53 described with reference to FIG. 5(C). Therefore, when the developing device 33 is pulled out from the printing unit 1B for replacing parts or developer, the upper support roll 330b is placed on the upper second support portion 54 (shown by a dashed line in FIG. 5(D)). When the developing device 33 is set to a position during normal operation where image formation is performed, the upper support roll 330b is separated from the upper second support portion 54 (shown by a solid line in FIG. 5(D)). The upper first support portion 53 and the upper second support portion 54 are an example of an upper guide path.

[0042] <Operation when installing developer 33> 6 to 9 are diagrams showing the operation of the developing unit 33 when it is set. FIG. 6 is a diagram showing the state in which the developing unit 33 is retracted, FIG. 6(A) is a diagram showing the state on the front side, and FIG. 6(B) is a diagram showing the state on the rear side. FIG. 7 is a diagram showing the state in which the developing unit 33 is moving from the retracted position to the set position, FIG. 7(A) is a diagram showing the state on the front side, and FIG. 7(B) is a diagram showing the state on the rear side. FIG. 8 is a diagram showing the state in which the developing unit 33 has been moved to the set position, FIG. 8(A) is a diagram showing the state on the front side, and FIG. 8(B) is a diagram showing the state on the rear side. FIG. 9 is a diagram showing the state in which the developing unit 33 is set, FIG. 9(A) is a diagram showing the state on the front side, and FIG. 9(B) is a diagram showing the state on the rear side. Note that FIG. 6(B), FIG. 7(B), FIG. 8(B), and FIG. 9(B) show the rear side as seen from the front side, so the outer shapes of the photosensitive drum 31 and the developing unit 33 are shown by imaginary lines (broken lines).

[0043] The developing unit 33 is in the retracted state when the developing unit 33 is pulled out from the printing unit 1B for replacing parts or a developer, etc. When the developing unit 33 is in the retracted state, as shown in Figures 6(A) and (B), the lower support roll 330a is located in the retracted portion 51b (see Figure 5) of the lower first support portion 51 and in the retracted portion 52b (see Figure 5) of the lower second support portion 52. In addition, the upper support roll 330b is located in the retracted portion 53b (see Figure 5) of the upper first support portion 53 and in the upper second support portion 54 in the first state.

[0044] When the developing unit 33 transitions from the retreated state to a set state for using the image forming apparatus 1, the developing unit 33 moves from the retreated position toward the photosensitive drum 31. That is, as shown in Figs. 7A and 7B, the lower support roll 330a moves from the retreated portion 51b of the lower first support portion 51 toward the inclined portion 51a (see Fig. 5) and from the retreated portion 52b of the lower second support portion 52 toward the inclined portion 52a (see Fig. 5). The upper support roll 330b moves from the retreated portion 53b of the upper first support portion 53 in the first state toward the inclined portion 53a (see Fig. 5) and moves the upper second support portion 54 toward the end portion on the photosensitive drum 31 side.

[0045] When the movement of the developing device 33 is completed, the developing device 33 is in a set preparation state. When the developing device 33 is in the set preparation state, as shown in Figs. 8(A) and (B), the lower support roll 330a is located at the inclined portion 51a of the lower first support portion 51 and the inclined portion 52a of the lower second support portion 52. Also, the upper support roll 330b is located at the inclined portion 53a of the upper first support portion 53 in the first state and is separated from the upper second support portion 54. In the set preparation state, the developing device 33 is supported by the lower first support portion 51 and the lower second support portion 52, and is supported by the inclined portion 53a and the support piece 53c (see Fig. 5) of the upper first support portion 53 to prevent it from falling toward the photosensitive drum 31. As shown in Fig. 8(B), in the set preparation state, the upper second support portion 54 is separated from the upper support roll 330b and does not support the developing device 33.

[0046] When the upper first support portion 53 transitions from the first state to the second state in the setting preparation state, as shown in FIGS. 9A and 9B, the support by the inclined portion 53a and the support piece 53c of the upper first support portion 53 is lost, and the developing unit 33 falls toward the photosensitive drum 31 side. Then, the contact portion 33a provided on the frame 330 (see FIG. 3) of the developing unit 33 comes into contact with the contact support portion 312 of the drum holding portion 311 of the photosensitive drum 31 to support the developing unit 33 that falls toward the photosensitive drum 31 side. Then, as shown in FIG. 9A, the pressing member 55 is attached to the lower first support portion 51 on the front side, and the lower support roll 330a is fixed by the inclined portion 51a, the abutting portion 51c, and the pressing member 55 of the lower first support portion 51. As a result, the developing unit 33 is positioned and the attitude of the developing unit 33 is stabilized.

[0047] <Drive mechanism> Next, a drive mechanism of the developing device 33 will be described. The developing device 33 includes a motor as a drive source, and supplies the developer contained in the developing device 33 to the developing roll 332 by transmitting the drive force of the motor to the developing roll 332, the pickup roll 333, the first conveying section 334, the second conveying section 335, and the third conveying section 336 (see FIG. 2). Then, the photoconductor drum 31 is developed with the toner of the developer held by the developing roll 332.

[0048] FIG. 10 is a diagram showing a drive mechanism of the developing device 33. The drive mechanism 60 is provided at one end (for example, the front end) of the developing device 33, and has a motor 61 as a drive source. The motor 61 is connected to a drive shaft 63 via a gear, and the rotation of the drive shaft 63 around the axis by the motor 61 is transmitted to a transmission shaft 339 of the developing device 33. The rotation of the transmission shaft 339 around the axis is distributed via gears and the like to drive the developing roll 332, the pickup roll 333, and the first to third transport sections 334 to 336. In FIG. 10, the gear connecting the motor 61 and the drive shaft 63 is housed in a case 64.

[0049] Here, the developing unit 33 may have a deviation in the axial center position of the transmission shaft 339 due to individual differences and changes over time. As described with reference to FIGS. 5 and 6, the developing unit 33 has a part of the lower support roll 330a fixed by the lower first support part 51, while the lower second support part 52 has a certain degree of freedom in positioning. This support structure may cause a deviation in the axial center position of the transmission shaft 339. Therefore, in the drive mechanism 60 including the motor 61, a configuration is adopted in which the position of the axial center of the shaft coupling (coupling) 66 that connects the drive shaft 63 and the transmission shaft 339 of the developing unit 33 is changeable.

[0050] 11 to 14 are diagrams showing the procedure for adjusting the axis of the drive mechanism 60 of the developing unit 33. FIG. 11(A) is a diagram showing a first state, and FIG. 11(B) is a diagram showing a second state. FIG. 12(A) is a diagram showing a third state, and FIG. 12(B) is a diagram showing a fourth state. FIG. 13(A) is a diagram showing a fifth state, and FIG. 13(B) is a diagram showing a sixth state. FIG. 14(A) is a diagram showing a seventh state, and FIG. 14(B) is a diagram showing an eighth state.

[0051] As shown in FIG. 11A, the drive mechanism 60 includes a motor 61, and a gear 62 and a drive shaft 63 that transmit the driving force of the motor 61. The gear 62 and the drive shaft 63 are housed in a case 64, and one end of the drive shaft 63 protrudes from the case 64. Rotation of the shaft of the motor 61 is transmitted to the drive shaft 63 via the gear 62. Then, the part of the drive shaft 63 exposed from the case 64 rotates and supplies the driving force to the outside. The case 64 is attached to the frame 330 of the developing device 33 by a screw 64a. The screw hole (not shown) into which the screw 64a of the case 64 is inserted is, for example, an elongated hole, and the position of the case 64 with respect to the frame 330 can be adjusted by tightening the screw 64a at a different position of the screw hole.

[0052] When adjusting the axis of the drive mechanism 60 (i.e., the position of the axis of the drive shaft 63), as shown in FIG. 11(B), first, an adjustment jig 65 is attached to the part of the drive shaft 63 exposed from the case 64. The adjustment jig 65 is a cylindrical jig made of metal or the like. Next, as shown in FIGS. 12(A) and 12(B), the position of the drive shaft 63 of the drive mechanism 60 to which the adjustment jig 65 is attached is aligned with the transmission shaft 339 of the developing device 33. In the state shown in FIG. 12(A), the positions of the drive shaft 63 and the transmission shaft 339 are not aligned. Therefore, the screw 64a is removed, and the case 64 is shifted to align the positions of the drive shaft 63 and the transmission shaft 339 as shown in FIG. 12(B). Then, the adjustment jig 65 of the drive shaft 63 is slid so that the adjustment jig 65 straddles the drive shaft 63 and the transmission shaft 339.

[0053] Next, as shown in FIG. 13A, the drive shaft 63 and the transmission shaft 339 are aligned with each other by the adjustment jig 65, and the case 64 is fixed to the frame 330 of the developing unit 33 by the screw 64a. After the case 64 is fixed, the transmission shaft 339 of the developing unit 33 is removed from the adjustment jig 65 as shown in FIG. 13B, and then, as shown in FIG. 14A, the adjustment jig 65 is removed from the drive shaft 63, and instead, a shaft coupling 66 is attached to the drive shaft 63. Then, the other end of the shaft coupling 66 attached to the drive shaft 63 is attached to the transmission shaft 339 of the developing unit 33. Through the above steps, the axial centers of the drive shaft 63 of the drive mechanism 60 and the transmission shaft 339 of the developing unit 33 are adjusted, and they are connected via the shaft coupling 66.

[0054] Although the embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the above embodiment. Various modifications and alternative configurations that do not depart from the scope of the technical idea of ​​the present invention are included in the present invention.

[0055] <Additional Notes> (((1))) a developing device comprising: an image carrier unit having an image carrier; a developing unit having a developer carrier that supplies developer to the image carrier on which an electrostatic latent image is formed; a support portion that supports the developing unit so that it can move forward and backward relative to the image carrier unit; a first positioning portion provided at an end of the support portion on the image carrier unit side and that positions the developing unit; and a second positioning portion that positions the developing unit by maintaining a predetermined gap between the developer carrier and the image carrier when the developing unit is positioned by the first positioning portion and leans toward the image carrier unit. (((2))) The developing device described in (((1))), characterized in that the support portion has a guide path that guides the developing unit, and the first positioning portion is configured to incline an end of the guide path so that the image carrier unit side descends, and to have an abutment portion against which the developing unit abuts at the inclined position of the guide path. (((3))) The developing device described in (((1))) or (((2))), characterized in that the first positioning portion further includes a pressing member that restricts movement of the developing unit when the developing unit abuts against the abutment portion. (((4))) The developing device described in either (((2))) or (((3))), characterized in that the guide path of the support part has two rails arranged parallel to the direction in which the developing unit moves forward and backward, and the first positioning part is configured by inclining each end of the two rails and having the abutment part at the end of one of the two rails. (((5))) The developing device described in (((4))), wherein the developing unit is not fixed on the rail that does not have the abutment portion, of the two rails in the first positioning portion. (((6))) The developing device described in any one of (((1))) to (((5))), characterized in that the support portion supports and guides a lower portion of the developing unit, and is provided with a lower guide path having the first positioning portion, and an upper guide path that supports and guides an upper portion of the developing unit, and the developing unit is separated from the upper guide path and leans down toward the image carrier unit when the developing unit is positioned by the first positioning portion of the lower guide path. (((7))) The developing device described in (((6))), characterized in that the upper guide path of the support part is switchable between a contact state in which the developing unit is supported and a retracted state in which the developing unit is separated from the developing unit, at least when the developing unit is in a position positioned by the first positioning part of the lower guide path. (((8))) The developing device described in (((7))), characterized in that the upper guide path of the support part has two rails arranged parallel to the direction in which the developer unit moves forward and backward, one of the two rails in the upper guide path is switchable between the contact state and the retracted state, and the other of the two rails in the upper guide path is shorter than the movement distance of the developer unit and does not contact the developer unit when the developer unit is in a position positioned by the first positioning portion of the lower guide path. (((9))) A developing device as described in any one of (((1))) to (((8))), further comprising a drive mechanism that rotates a drive shaft of the developing unit to transmit a driving force to the developing unit, the drive mechanism being capable of changing the position of an axis of a joint portion that is connected to the drive shaft and rotates the drive shaft. (((10))) An image forming apparatus comprising the fixing device according to any one of ((1))) to (((9))).

[0056] According to the developing device of (((1))), the developer can be pressed against the photosensitive drum with a simple configuration that uses the weight of the developer unit, compared to a configuration that uses a member that generates a pressing force to press the developer against the photosensitive drum. According to the developing device of (((2))), since the developing unit is positioned by its own weight, the structure can be simplified compared to a structure in which a mechanism for fixing the developing unit is provided. According to the developing device of (((3))), it is possible to more reliably suppress the restriction of the movement of the developing unit compared to a configuration in which the movement of the developing unit is restricted only by the inclination of the guide path and the abutment portion. The developing device according to ((4)) can have a simpler configuration than a configuration in which each rail has an abutment portion. According to the developing device of (((5))), the positioning of the developing unit can be made easier and the load on the developing unit and the first positioning portion can be reduced compared to a configuration in which the developing unit is fixed on each rail. According to the developing device of (((6))), since the developing unit is positioned by its own weight, the structure can be simplified compared to a structure in which a mechanism for fixing the developing unit is provided. According to the developing device of (((7))), the developer unit can be prevented from tipping over, as compared to a configuration in which the upper guide path does not support the developer unit in the first positioning portion. The developing device according to ((8)) can have a simpler configuration than a configuration in which each rail is switchable between a contact state and a retracted state. The developing device according to ((9)) can accommodate deviations in the axis due to individual differences in developing units and changes over time, compared to a configuration in which the axis position of the drive mechanism is fixed. According to the image forming apparatus of (((10))), the developing device can press the developing device against the photosensitive drum with a simple configuration that uses the weight of the developing device unit, compared to a configuration that uses a member that generates a pressing force to press the developing device against the photosensitive drum. [Explanation of symbols]

[0057] 1...image forming apparatus, 1B...printing unit, 31...photosensitive drum, 311...drum holding portion, 312...contact support portion, 33...developing device, 33a...contact portion, 330...frame, 330a...lower support roll, 330b...upper support roll, 331...accommodating portion, 331a...opening, 332...developing roll, 333...pickup roll, 334...first conveying portion, 335...second conveying portion, 336...third conveying portion, 337...regulating member, 338...removal member, 51...lower first support portion, 51a...inclined portion, 51b...retracting portion, 51c...butting portion, 52...lower second support portion, 52a...inclined portion, 52b...retracting portion, 53...upper first support portion, 53a...inclined portion, 53b...retracting portion, 53c...support piece, 54...upper second support portion

Claims

1. an image carrier unit having an image carrier; a developing unit having a developer carrier that supplies a developer to the image carrier on which an electrostatic latent image is formed; a support portion that supports the developing unit so as to be movable toward and away from the image carrier unit; a first positioning portion provided at an end of the support portion on the image carrier unit side and configured to position the developing unit; a second positioning portion that positions the developing unit by maintaining a predetermined gap between the developer carrier and the image carrier when the developing unit is positioned by the first positioning portion and is in a state of being tilted toward the image carrier unit; A developing device comprising:

2. the support portion has a guide path for guiding the developing unit, The first positioning portion is configured to incline an end of the guide path so that the image carrier unit side is lowered, and to have an abutment portion against which the developing unit abuts at a position where the guide path is inclined.

2. The developing device according to claim 1,

3. The first positioning portion further includes a pressing member that restricts movement of the developing unit when the developing unit abuts against the abutting portion.

3. The developing device according to claim 2,

4. the guide path of the support portion includes two rails arranged in parallel along a direction in which the developing unit advances and retreats, The first positioning portion is configured by inclining the ends of each of the two rails and having the abutment portion at one end of the two rails.

3. The developing device according to claim 2,

5. The developing unit is not fixed on the rail that does not have the abutment portion, out of the two rails in the first positioning portion.

5. The developing device according to claim 4,

6. The support portion is a lower guide path that supports and guides a lower portion of the developing unit and has the first positioning portion; an upper guide path that supports and guides an upper portion of the developing unit; The developing unit is separated from the upper guide path in a state where the developing unit is positioned by the first positioning portion of the lower guide path, and falls toward the image carrier unit.

2. The developing device according to claim 1,

7. The upper guide path of the support portion is switchable between a contact state in which the developer unit is supported and a retracted state in which the developer unit is separated from the developer unit, at least when the developer unit is in a position positioned by the first positioning portion of the lower guide path.

7. The developing device according to claim 6,

8. the upper guide path of the support portion has two rails arranged in parallel along a direction in which the developing unit advances and retreats, One of the two rails in the upper guideway is switchable between the contact state and the retracted state, The other of the two rails in the upper guide path is shorter than the moving distance of the developing unit, and does not come into contact with the developing unit when the developing unit is in a position positioned by the first positioning portion of the lower guide path.

8. The developing device according to claim 7,

9. a drive mechanism for rotating a drive shaft of the developing unit to transmit a drive force to the developing unit, The drive mechanism is capable of changing the position of the axis of a joint portion that is connected to the drive shaft and rotates the drive shaft.

2. The developing device according to claim 1,

10. 10. An image forming apparatus comprising the developing device according to claim 1.

Images