Image forming apparatus

Abstract

To suppress deterioration of removal performance for removing powder from an image holding body as compared with a case where a position where the powder is removed from an outer peripheral surface of the image holding body by a removal part is above a virtual horizontal plane including a rotation axis.SOLUTION: The image forming apparatus is equipped with a photoreceptor drum 31 which is provided rotatably around a rotary shaft 31b and holds an image, and a blade 62 which comes into contact with the front face of the rotating photoreceptor drum 31 and removes powder sticking to the front face of the photoreceptor drum 31. 301 302, in the set of image forming parts or at least one image forming unit 301 of the plurality of sets of image forming parts, a contact position 62a where the blade 62 comes into contact with the photoreceptor drum 31 is lower than a virtual horizontal plane H passing through the rotation axis 31b of the photoreceptor drum 31.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] For example, Patent Document 1 discloses a collection device having a plurality of waste toner collection units, a collection box for storing the waste toner collected by the waste toner collection units, and a waste toner transport path for transporting the waste toner collected by the waste toner collection units to the collection box. Of the plurality of waste toner collection units, a waste toner collection unit that collects waste toner with poor fluidity is connected downstream of the other waste toner collection units on the waste toner transport path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-91038 Summary of the Invention [Problem to be solved by the invention]

[0004] Consider an image forming apparatus having a configuration including a rotatable image carrier and a removal unit that removes powder adhering to the outer peripheral surface of the rotating image carrier. When a large amount of powder needs to be removed, if the position where the removal unit removes the powder from the outer peripheral surface of the image carrier is above an imaginary horizontal plane including the rotation axis, the following problem may occur: The removed powder may not move downward but may remain at the removal location. If the amount of powder remaining at the removal location becomes excessive, the removal performance of the removal unit in removing the powder from the outer peripheral surface of the image carrier may be reduced. The object of the present invention is to suppress a decrease in the removal performance of removing powder from the image carrier compared to when the position at which the removal section removes powder from the outer surface of the image carrier is above a virtual horizontal plane including the rotation axis. [Means for solving the problem]

[0005] The invention described in claim 1 is an image forming apparatus comprising an image carrier that is rotatable around a rotation axis and holds an image, and a removal unit that contacts the outer peripheral surface of the rotating image carrier and removes powder adhering to the outer peripheral surface of the image carrier, wherein one or more sets of image forming units that have the image carrier and the removal unit and form an image are provided, and in the set of image forming units or at least one of the sets of image forming units, the contact position where the removal unit contacts the outer peripheral surface of the image carrier is below a virtual horizontal plane that passes through the rotation axis of the image carrier. The invention described in claim 2 is the image forming apparatus described in claim 1, characterized in that, when a plurality of sets of the image forming units are provided, the image carrier in one of the image forming units whose contact position is below the virtual horizontal plane is defined as one image carrier, the removal unit in one of the image forming units whose contact position is below the virtual horizontal plane is defined as one removal unit, the contact position at which the one removal unit contacts the outer peripheral surface of the one image carrier is defined as a first contact position, and a position at which another removal unit provided corresponding to another image carrier in another of the plurality of sets of image forming units contacts the outer peripheral surface of the other image carrier is defined as a second contact position, a first angle which is the angle at which a line connecting the rotation axis of the one image carrier and the first contact position intersects with the virtual horizontal plane, and a second angle which is the angle at which a line connecting the rotation axis of the other image carrier and the second contact position intersects with the virtual horizontal plane of the one image carrier are different from each other. The invention described in claim 3 is the image forming device described in claim 2, characterized in that the first angle and the second angle are different from each other because the attitude of the one image forming unit relative to the main body of the image forming device and the attitude of the other image forming unit relative to the main body of the image forming device are different from each other. The invention described in claim 4 is the image forming apparatus described in claim 1, characterized in that it comprises a storage section that stores the powder removed by the removal section and moving downward, and a conveying section that rotates around an axis to convey the powder stored in the storage section in the axial direction, and the image forming section further has the storage section and the conveying section, and a virtual vertical line extending downward from the contact position passes through the conveying section. The invention described in claim 5 is the image forming apparatus described in claim 4, characterized in that it includes a forming member that is arranged at a position opposite the image carrier and forms a space between the outer surface of the image carrier and a gap that allows the powder removed by the removal section to temporarily remain and allows the powder in the space to pass downward, and the image forming section further has the forming member, and an imaginary vertical line extending downward from the lower end of the forming member passes through the conveying section. The invention described in claim 6 is the image forming apparatus described in claim 5, characterized in that the virtual vertical line passes through a part of the conveying section that moves the powder contained in the storage section toward the bottom of the storage section. [Effects of the Invention]

[0006] According to the invention of claim 1, the deterioration of the removal performance of removing powder from the image carrier can be suppressed compared to when the position at which the removal unit removes powder from the outer peripheral surface of the image carrier is above a virtual horizontal plane including the rotation axis. According to the invention of claim 2, the first angle, which is the angle at which the line connecting the rotation axis of one image holder and the first contact position intersects with the virtual horizontal plane, and the second angle, which is the angle at which the line connecting the rotation axis of another image holder and the second contact position intersects with the virtual horizontal plane of the one image holder, can suppress a decrease in the removal performance of removing powder from the image holder compared to when a configuration that is not different from each other is adopted. According to the invention of claim 3, since the attitude of one image forming unit relative to the main body of the image forming device is different from the attitude of the other image forming unit relative to the main body of the image forming device, it is possible to share components compared to a case where a configuration in which the first angle and the second angle are different from each other is not adopted. According to the invention of claim 4, the image forming unit is provided with a storage section that stores the powder removed by the removal section and moving downward, and a conveying section that rotates around an axis to convey the powder stored in the storage section in the axial direction, and the image forming unit further has a storage section and a conveying section, and the virtual vertical line extending downward from the contact position can more reliably transport the powder in the conveying section compared to a case in which a configuration is not adopted in which the imaginary vertical line passes through the conveying section. According to the invention of claim 5, the virtual vertical line extending downward from the lower end of the forming member can more reliably transport powder in the transport section compared to a case in which a configuration that does not pass through the transport section is not adopted. According to the invention of claim 6, the virtual vertical line can transport the powder in the transport section more quickly than in a case where a configuration is not adopted in which the virtual vertical line passes through the part of the transport section that moves the powder contained in the storage section toward the bottom of the storage section. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating a developing device of the image forming apparatus. [Figure 3] FIG. 2 is a diagram illustrating the photosensitive drum and its surroundings of the image forming apparatus. [Figure 4] 1A and 1B are diagrams illustrating an example of the positional relationship between photosensitive drums and drum cleaners in multiple sets of image forming units according to the first embodiment, where (a) shows one set of image forming units and (b) shows another set of image forming units. [Figure 5] 10A and 10B are diagrams illustrating another example of the positional relationship between photosensitive drums and drum cleaners in a plurality of sets of image forming units, where FIG. 10A shows one set of image forming units, and FIG. 10B shows another set of image forming units. [Figure 6] 1A and 1B are diagrams illustrating an example of the positional relationship between a blade and a conveying member in a drum cleaner, where FIG. 1A shows an example in which a partition member is provided, and FIG. 1B shows another example in which a partition member is not provided. [Figure 7] FIG. 2 is a diagram showing an example of an arrangement of a plurality of image forming units together with an intermediate transfer belt. [Figure 8] FIG. 10 is a diagram showing another example of the arrangement of a plurality of sets of image forming units together with the intermediate transfer belt. [Figure 9] 10A and 10B are diagrams illustrating an example of a drum cleaner in a plurality of sets of image forming units according to a second embodiment, where FIG. 10A shows one set of image forming units, and FIG. 10B shows another set of image forming units. [Figure 10] 10A and 10B are diagrams illustrating another example of a drum cleaner in a plurality of sets of image forming units, where FIG. 10A shows one set of image forming units, and FIG. 10B shows another set of image forming units. [Figure 11] FIG. 2 is a diagram showing an example of an arrangement of a plurality of image forming units together with an intermediate transfer belt. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram illustrating an image forming apparatus 1 according to the present embodiment. 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 for storing paper P therein. The paper feed unit 1A is also provided with feed rolls 15 to 18 corresponding to the first paper storage section 11 to the fourth paper storage section 14. The feed rolls 15 to 18 feed the paper P stored in each paper storage section to a transport path connected to the printing unit 1B.

[0009] The printing unit 1B includes an image forming section 20 that forms an image on paper P. The image forming section 20 is positioned and attached to a unit body 1D of the printing unit 1B. The unit body 1D is an example of a body of an image forming apparatus. The printing unit 1B is also provided with a control unit 21 that controls each part of the image forming apparatus 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 the personal computer (PC) 5. The printing unit 1B is also provided with a UI (User Interface) 23 that is configured with a touch panel, etc. The UI 23 notifies the user of information and accepts information input from the user.

[0010] The image forming section 20 is provided with six image forming units 30T, 30P, 30Y, 30M, 30C, and 30K (hereinafter, sometimes simply referred to as "image forming units 30" or "multiple sets of image forming units 30") that are arranged in parallel at regular intervals. The multiple sets of image forming units 30 in this case are devices that form color images and are an example of multiple sets of image forming sections. It is possible that the image forming section 20 is composed of only the image forming unit 30K. In such a case, the image forming apparatus 1 is an apparatus that forms black and white images, and the image forming unit 30K is an example of a set of image forming sections.

[0011] Each image forming unit 30 includes a photosensitive drum 31 on which an electrostatic latent image is formed while rotating in the direction of arrow A, and a charging roll 32 that charges the surface of the photosensitive drum 31. Each image forming unit 30 also includes a developing device 33 that develops the electrostatic latent image formed on the photosensitive drum 31. Furthermore, each image forming unit 30 includes a drum cleaner 34 that removes toner and the like from the surface of the photosensitive drum 31.

[0012] The image forming section 20 is also provided with a laser exposure device 26 that exposes the photosensitive drum 31 of each image forming unit 30 to laser light. The exposure of the photosensitive drum 31 by the laser 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 photosensitive drum 31 may be exposed using light emitted from the light source.

[0013] Each image forming unit 30 is configured similarly except for the toner stored in the developing device 33. Image forming units 30Y, 30M, 30C, and 30K form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Furthermore, the image forming units 30T and 30P form toner images using toner corresponding to the corporate color, foam toner for Braille, fluorescent color toner, toner for improving gloss, etc. In other words, the image forming units 30T and 30P form toner images using toner of a particular color.

[0014] The image forming section 20 is also provided with an intermediate transfer belt 41 onto which the toner images of each color formed by the photosensitive drums 31 of the image forming units 30 are transferred. The image forming section 20 is also provided with primary transfer rolls 42 that transfer the respective color toner images of the image forming units 30 onto the intermediate transfer belt 41 at the primary transfer section T1. The image forming unit 20 is also provided with a secondary transfer roll 40 that transfers the toner images transferred onto the intermediate transfer belt 41 onto the paper P at a secondary transfer unit T2. Furthermore, the image forming unit 20 is provided with a belt cleaner 45 that removes toner and the like from the surface of the intermediate transfer belt 41, and a fixing device 80 that fixes the secondarily transferred image onto the paper P.

[0015] The image forming unit 20 performs an image forming operation based on a control signal from the control unit 21 . Specifically, in the image forming unit 20, first, image processing is performed by the image processing unit 22 on image data input from the image reading device 4 or the PC 5. Then, the image data after the image processing is supplied to the laser exposure device 26. For example, in the magenta (M) image forming unit 30M, the surface of the photosensitive drum 31 is charged by the charging roll 32. Thereafter, the laser exposure device 26 irradiates the photosensitive drum 31 with laser light modulated by image data obtained from the image processing unit 22.

[0016] As a result, an electrostatic latent image is formed on the photosensitive drum 31 . The formed electrostatic latent image is developed by the developing unit 33, and a magenta toner image is formed on the photosensitive 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.

[0017] The color toner images formed by each image forming unit 30 are sequentially electrostatically transferred onto an intermediate transfer belt 41 rotating in the direction of arrow C in Figure 1 by a primary transfer roll 42, forming superimposed toner images on the intermediate transfer belt 41. The superimposed toner image formed on the intermediate transfer belt 41 is transported to a secondary transfer portion T2 constituted by a secondary transfer roll 40 and a backup roll 49 as the intermediate transfer belt 41 moves.

[0018] On the other hand, the paper sheet P is taken out from 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 portion T2, the paper P is supplied from the registration roll 74 to the secondary transfer portion T2 in accordance with this timing. Then, at the secondary transfer portion T2, the superimposed toner images are electrostatically transferred onto the paper P in a lump due to the action of a transfer electric field formed between the secondary transfer roll 40 and the backup roll 49.

[0019] Thereafter, the paper P onto which the superimposed toner images have been electrostatically transferred is transported to the fixing device 80. In the fixing device 80, the paper P on which the unfixed toner image has been formed is pressurized and heated, and the toner image is fixed to the paper P. Then, the paper P on which the fixing process has been performed passes through a curl correction section 81 provided in the paper discharge unit 1C, and is then conveyed to a paper stacking section (not shown).

[0020] 1 employs a configuration in which the image forming unit 30 transfers a toner image to the intermediate transfer belt 41, but the present invention is not limited to this. That is, it is also possible to employ a configuration in which the image forming unit 30 transfers a toner image to the paper P.

[0021] FIG. 2 is a diagram for explaining the developing unit 33 of the image forming apparatus 1, and is a schematic front view of the developing unit 33 when viewed from the same direction as that shown in FIG. 2, the developing unit 33 includes a storage section 331 that stores a developer (not shown) therein. The storage section 331 is made up of a resin storage housing 332. The developer is made up of a magnetic carrier and a colored toner, and is a so-called two-component developer. The housing 332 of the developing unit 33 is disposed so as to extend in a direction perpendicular to the plane of the paper in Fig. 2, which is the direction from the front side to the rear side of the image forming apparatus 1 (see Fig. 1). The housing 332 has a front member (not shown) on the front side and a rear member (not shown) on the rear side.

[0022] An opening 333 is provided in the housing 332 at a location facing the photosensitive drum 31 (see FIG. 1). A developing roll 334 that adheres developer to the surface of the photosensitive drum 31 is provided in this opening 333. The developing roll 334 holds the developer to be supplied to the photosensitive drum 31. The position where the developer from the developing roll 334 is supplied to the photosensitive drum 31 is sometimes referred to as the developing position. The developing roll 334 is formed in a cylindrical shape and is arranged to extend in a direction from the front side to the rear side of the image forming apparatus 1. In addition, the developing roll 334 is arranged along the longitudinal direction of the developing unit 33.

[0023] The developing roll 334 is provided with a developing sleeve 334G that is made of a cylindrical body and is driven to rotate, and a magnet roll 334H that is disposed inside the developing sleeve 334G. The developing sleeve 334G is made of metal such as SUS, etc. The developing sleeve 334G rotates in the direction of arrow D in the figure.

[0024] Furthermore, in this embodiment, at the primary transfer portion T1 (see FIG. 1) between the developing roll 334 and the photosensitive drum 31, the developing sleeve 334G and the photosensitive drum 31 rotate so that they move in the same direction. The developing device 33 is provided with a layer regulating member 335 that regulates the layer thickness of the developer held on the developing roll 334 .

[0025] 2, the developing device 33 is provided with a first conveying section 336, a second conveying section 337, and a third conveying section 338 that convey the developer. Hereinafter, the first conveying section 336, the second conveying section 337, and the third conveying section 338 may be referred to as conveying sections 336 to 338.

[0026] The transport sections 336 to 338 are provided on the opposite side of the developing roll 334 from the side on which the photosensitive drum 31 (see FIG. 1) is installed. Each of the transport sections 336 to 338 includes rotating members 51, 52, and 53 extending along the rotation axis of the developing sleeve 334G that is driven to rotate. Each of the transport sections 336 to 338 rotates around the rotating members 51 to 53. That is, the transport sections 336 to 338 are disposed substantially parallel to the photosensitive drum 31 (see FIG. 1).

[0027] 3 is a diagram illustrating the photosensitive drum 31 and its surroundings of the image forming apparatus 1. Each of the image forming units 30 has the photosensitive drum 31 shown in FIG.

[0028] Around the photosensitive drum 31, the above-mentioned charging roll 32, developing roll 334, primary transfer roll 42, and drum cleaner 34 are arranged in the direction of arrow A. The drum cleaner 34 will be described in more detail below.

[0029] The drum cleaner 34 cleans the surface 31a of the photosensitive drum 31 downstream of the primary transfer portion T1 in the direction of arrow A, and removes toner and other matter remaining on the surface 31a after transfer. The drum cleaner 34 also collects the removed matter.

[0030] The drum cleaner 34 includes a main body 61 , a blade 62 , a partition member 63 , a conveying member 64 , and a contact member 65 . The main body 61 holds components such as a blade 62 .

[0031] The blade 62 is attached to the main body 61 so as to be inclined in the direction opposite to the direction of arrow A relative to the surface 31a of the photosensitive drum 31, and the tip of the blade 62 that comes into contact with the surface 31a cleans the surface 31a. In this embodiment, the blade 62 is used to scrape off powder such as toner adhering to the surface 31a of the photosensitive drum 31, but this is not limiting. Instead of the blade 62, it is also possible to use, for example, a brush (not shown) that removes powder by rotation.

[0032] The partition member 63 is positioned between the main body 61 and the surface 31 a of the photosensitive drum 31 , and forms a space S for accommodating the material removed by the blade 62 .

[0033] The transport member 64 is disposed in the space S and extends along the rotation axis of the photosensitive drum 31. The transport member 64 is a member that extends spirally. The transport member 64 transports the removed material by rotating, thereby collecting the removed material. The transport direction by the transport member 64 is the direction perpendicular to the plane of the paper in FIG. 3.

[0034] The contact member 65 is positioned so as to cover the gap between the main body 61 and the partition member 63, and forms a space S together with the partition member 63. More specifically, the contact member 65 is disposed from the main body 61 toward the surface 31 a of the photosensitive drum 31 .

[0035] More specifically, one end of contact member 65 is attached to main body 61 so as to be inclined in the direction of arrow A. The other end, tip portion 65a, contacts surface 31a. A part of tip portion 65a itself deforms, for example, to follow the shape of surface 31a.

[0036] More specifically, the toner, etc. that passes between the tip 65a of the contact member 65 and the surface 31a of the photosensitive drum 31 is distinguished from the toner, etc. that does not pass between them. Settings are made for each image forming unit 30 according to conditions such as the size of the toner supplied from the developing roll 334 to the photosensitive drum 31. These settings relate to the degree of deformation due to the material and thickness of the contact member 65, the gap between the tip 65a and the surface 31a, etc. As a result, the toner and other matter remaining on the surface 31a of the photosensitive drum 31 after transfer passes between the surface 31a and the tip 65a of the contact member 65 and moves to the position of the blade 62. On the other hand, the removed matter contained in the space S is restricted from moving out of the main body 61. The contact member 65 of this embodiment may be made of, for example, a soft resin film.

[0037] Here, the partition member 63, together with the contact member 65 and the surface 31a of the photosensitive drum 31, forms a reservoir 66 for accumulating the powder removed from the photosensitive drum 31 by the contact member 65. By accumulating the powder in the reservoir 66, the contact member 65 can slide smoothly when it comes into contact with the surface 31a of the photosensitive drum 31.

[0038] Furthermore, the partition member 63 has a gap 67 between it and the surface 31a of the photosensitive drum 31 below the accumulation portion 66, through which the powder falls. The gap 67 is an outlet through which the powder flows out of the accumulation portion 66. The powder flowing downward from the gap 67 falls along the wall surface 611 of the main body 61 and is contained in the main body 61. In this embodiment, the gap 67 is a space between the partition member 63 and the contact member 65.

[0039] The main body 61 of the drum cleaner 34 has a storage section 61a that stores powder that has fallen along a wall surface 611. The storage section 61a is located below the main body 61. A conveying member 64 is rotatably disposed in the storage section 61a.

[0040] Here, the photosensitive drum 31 is an example of an image carrier, and the surface 31a of the photosensitive drum 31 is an example of an outer peripheral surface. The blade 62 is an example of a removal section and an example of a scraping section. The partition member 63 is an example of a forming member and an example of a placement member. The storage section 61a is an example of a storage section that stores powder. The conveying member 64 is an example of a conveying section. The intermediate transfer belt 41 is an example of a transfer member. The image forming unit 30 is an example of one or more sets of image forming sections, and is an example of multiple image forming sections.

[0041] Next, a first embodiment and a second embodiment of the present invention will be described. The first embodiment will be described with reference to Figures 4 to 8. The second embodiment will be described with reference to Figures 9 to 11.

[0042] First Embodiment First, the first embodiment will be described. Here, the powder scraped off by the blade 62 in the image forming unit 30 shown in FIG. 3 flows downward from the accumulation portion 66 through the gap 67 and is stored in the storage portion 61a. However, if the amount of powder scraped off by the blade 62 is large, the powder accumulated in the accumulation portion 66 may have difficulty moving downward through the gap 67. As the amount of powder in the accumulation portion 66 increases, the tip portion 65a of the contact member 65 is pushed toward the photosensitive drum 31. This makes it difficult for the powder to pass between the tip portion 65a of the contact member 65 and the surface 31a of the photosensitive drum 31. This may cause the powder on the surface 31a to be directly scraped off by the tip portion 65a. There is a concern that the powder scraped off by the tip portion 65a of the contact member 65 may soil the image forming unit 30, the intermediate transfer belt 41, etc. Such concerns apply not only to cases where the image forming apparatus 1 includes only one set of image forming units 30, but also to cases where the image forming apparatus 1 includes multiple sets of image forming units 30.

[0043] Furthermore, the amount of powder scraped off by blade 62 in each of the multiple sets of image forming units 30 is not always the same and varies depending on, for example, the toner ratio of the developed image. For example, the amount of powder scraped off by blade 62 may differ between image forming units 30Y, 30M, 30C, and 30K. Furthermore, of the multiple sets of image forming units 30, the amount of powder scraped off by image forming units 30T and 30P is generally greater than that of image forming units 30Y, 30M, 30C, and 30K. In image forming unit 30 where a large amount of powder is scraped off, it is conceivable that the removed powder may not be smoothly discharged from accumulation portion 66 and may remain there. If the amount of accumulated powder becomes excessive, the removal performance of blade 62 in removing powder from surface 31a of photosensitive drum 31 may be reduced. Therefore, in the first embodiment, the powder removed from the blade 62 is smoothly discharged from the accumulation portion 66, thereby making it possible to suppress a decrease in removal performance.

[0044] 4A and 4B are diagrams illustrating an example of the positional relationship between the photosensitive drum 31 and the drum cleaner 34 in a plurality of sets of image forming units according to the first embodiment. FIG. 4A shows one set of image forming units 301 among the plurality of sets of image forming units, and FIG. 4B shows another set of image forming units 302. In FIG. 4A, the developing device 33 (see FIG. 1) and other components are omitted from illustration. The image forming unit 301 in FIG. 4A will be described as having a larger amount of powder removed by the blade 62 than the image forming unit 302 in FIG. 4B. It should be noted that in the case where only one set of image forming units is provided, rather than a case where a plurality of sets of image forming units are provided, the configuration shown in FIG. 4(a) is employed.

[0045] 4(a), the photosensitive drum 31 is rotatably provided around a rotation shaft 31b. More specifically, the photosensitive drum 31 rotates clockwise, i.e., in the direction of arrow A, around the rotation shaft 31b. The blade 62 of the drum cleaner 34 comes into contact with the surface 31a of the rotating photosensitive drum 31 to remove powder such as toner adhering to the surface 31a of the photosensitive drum 31. The blade 62 comes into contact with the surface 31a of the photosensitive drum 31 at a contact position 62a.

[0046] In image forming unit 301 shown in Fig. 4(a), contact position 62a is below imaginary horizontal plane H that passes through rotation shaft 31b. On the other hand, in image forming unit 302 shown in Fig. 4(b), contact position 62a is above imaginary horizontal plane H that passes through rotation shaft 31b. Therefore, wall surface 611 of main body 61 in image forming unit 301 has a steeper slope than wall surface 611 in image forming unit 302, making it easier for powder removed by blade 62 to slide off. With this configuration, the powder removed from blade 62 can be smoothly discharged from reservoir 66. Reservoir 66 is an example of a space where the powder removed by the remover temporarily stays. Also, gap 67 (see FIG. 3) described above is an example of a gap that allows the powder in the space to pass downward.

[0047] 4(a) and 4(b), consider a case where the rotation axis 31b is the origin of a Cartesian coordinate system, the virtual horizontal plane H is the X-axis, and the virtual vertical plane V1 is the Y-axis. The X-axis and Y-axis are not shown in FIG. The area where the X-axis value is negative and the Y-axis value is positive is called the second quadrant, and the area where both the X-axis value and the Y-axis value are negative is called the third quadrant. The contact position 62a shown in Figure 4(a) is in the third quadrant, and the contact position 62a shown in Figure 4(b) is in the second quadrant. The photosensitive drum 31 is an example of an image carrier, and the blade 62 is an example of a removal unit. The image forming unit 301 shown in Figure 4(a) is an example of a set of image forming units, and is also an example of at least one image forming unit among a plurality of sets of image forming units.

[0048] Furthermore, in the photosensitive drum 31 shown in FIGS. 4(a) and 4(b), consider the angle at which a line segment 62b connecting the contact position 62a and the rotation shaft 31b intersects with a virtual horizontal plane H. In the case shown in FIG. 4(a), the angle is θ1, and in the case shown in FIG. 4(b), the angle is θ2. The angles θ1 and θ2 are mutually different. If the clockwise direction is defined as negative and the counterclockwise direction as positive, the angle θ1 is positive and the angle θ2 is negative. The clockwise direction here is the same direction as the direction of arrow A on the photosensitive drum 31, and the counterclockwise direction is the opposite direction to the direction of arrow A. The arrow directions of the lead lines for angles θ1 and θ2 in FIG. 4 indicate whether they are clockwise or counterclockwise. In the example shown in FIG. 4, the absolute value of the angle θ1 is greater than the absolute value of the angle θ2, and when compared using positive and negative signs, the angle θ1 is greater than the angle θ2 (+θ1>−θ2). The difference between the angle θ1 and the angle θ2 can be realized by shifting the entire drum cleaner 34 in the vertical direction or in the circumferential direction of the photosensitive drum 31. The line segment 62b is an example of a line connecting the rotation axis of one image carrier and the first contact position, and is an example of a line connecting the rotation axis of another image carrier and the second contact position.

[0049] As described above, the amount of powder removed by blade 62 in image forming unit 301 shown in Figure 4(a) is greater than that in image forming unit 302 shown in Figure 4(b). However, in image forming unit 301, contact position 62a is below imaginary horizontal plane H. Therefore, wall surface 611 of main body 61 in image forming unit 301 has a steep slope, which prevents the powder removed by blade 62 from accumulating.

[0050] 4A, contact position 62a in image forming unit 301 is an example of a first contact position, and angle θ1 is an example of a first angle. Contact position 62a in image forming unit 302 in FIG. 4B is an example of a second contact position, and angle θ2 is an example of a second angle.

[0051] 5A and 5B are diagrams illustrating another example of the positional relationship between the photosensitive drum 31 and the drum cleaner 34 in a plurality of sets of image forming units according to the first embodiment. FIG. 5A shows one set of image forming units 303 among the plurality of sets of image forming units, and FIG. 5B shows another set of image forming units 304. FIG. 5 corresponds to FIG. 4, and like FIG. 4, the developing device 33 (see FIG. 1) and the like are not shown. Also, in FIG. 5, descriptions of matters common to FIG. 4 may be omitted. The image forming unit 303 in FIG. 5A will be described assuming that the amount of powder removed by the blade 62 is greater than that of the image forming unit 304 in FIG. 5B.

[0052] 5(a) is in the third quadrant of the image forming unit 303, and the contact position 62a in the image forming unit 304 shown in FIG. 5(b) is also in the third quadrant of the image forming unit 303. In this respect, it differs from the case of FIG. 4. 5(a), the angle at which line segment 62b intersects with imaginary horizontal plane H is angle θ3, and in FIG. 5(b), the angle at which line segment 62b intersects with imaginary horizontal plane H is angle θ4. Angles θ3 and θ4 are different from each other. More specifically, angle θ3 is greater than angle θ4 (θ3>θ4). Therefore, wall surface 611 of main body 61 in image forming unit 303 has a steeper slope than wall surface 611 in image forming unit 304. The difference between the angle θ3 and the angle θ4 can be achieved by shifting downward not the entire drum cleaner 34 but a part of it, namely, the blade 62. The arrows on the lead lines for the angles θ3 and θ4 in FIG. 5 indicate whether they are clockwise or counterclockwise.

[0053] As described above, the amount of powder removed by blade 62 in image forming unit 303 shown in Figure 5(a) is greater than that in image forming unit 304 shown in Figure 5(b). However, in image forming unit 303, contact position 62a is below imaginary horizontal plane H. Therefore, wall surface 611 of main body 61 in image forming unit 303 has a steep slope, which prevents the powder removed by blade 62 from accumulating.

[0054] 5A, contact position 62a in image forming unit 303 is an example of the first contact position, and angle θ3 is an example of the first angle. Contact position 62a in image forming unit 304 in FIG. 5B is an example of the second contact position, and angle θ4 is an example of the second angle.

[0055] 6A and 6B are diagrams illustrating an example of the positional relationship between the blade 62 and the conveying member 64 in the drum cleaner 34 according to the first embodiment. Fig. 6A shows an example in which the partition member 63 is provided, and Fig. 6B shows another example in which the partition member 63 is not provided. 6(a) and 6(b), a transport member 64 is provided in a storage section 61a of a main body 61 capable of storing powder. The transport member 64 rotates clockwise around a shaft 64a located within the storage section 61a. The transport member 64 performs uniform circular motion, rotating in one direction.

[0056] 6(a), an imaginary vertical line V2 extending downward from the contact position 62a of the blade 62 passes through the conveying member 64. In addition, in the example shown in the same figure (a), an imaginary vertical line V3 extending downward from the lower end 63a of the partition member 63 passes through the conveying member 64. In other words, the length of the partition member 63 is adjusted to be short so that the imaginary vertical line V3 passes through the conveying member 64. Therefore, the powder scraped off by the blade 62 does not slide down the wall surface of the main body 61, but falls directly onto the conveying member 64 and piles up on the wall surface.

[0057] 6(a), consider a case where the conveying member 64 is divided into a left half 64b and a right half 64c by an imaginary vertical line V4 passing through the shaft 64a of the conveying member 64. The left half 64b is located away from the photosensitive drum 31. The right half 64c is located closer to the photosensitive drum 31. The range of the left half 64b is indicated by diagonal lines slanting upward to the right. The range of the right half 64c is indicated by diagonal lines slanting downward to the right. Since the conveying member 64 rotates clockwise around the shaft 64a, the left half 64b is a section that moves the powder in the container 61a upward, and the right half 64c is a section that rotates the powder in the container 61a downward. In other words, the right half 64c is a section that moves the powder contained in the container 61a toward the bottom 61b of the container 61a.

[0058] In this way, since the imaginary vertical lines V2 and V3 pass through the right half 64c of the conveying member 64, it is possible to quickly convey the powder that has fallen from the gap 67 (see Figure 3) in the axial direction compared to when they pass through the left half 64b. The imaginary vertical line V2 is an example of an imaginary vertical line extending downward from the contact position, and the imaginary vertical line V3 is an example of an imaginary vertical line extending downward from the lower end of the arrangement member. The right half 64c is an example of a portion that moves the powder contained in the container toward the bottom of the container.

[0059] 6(b), there is no partition member 63 shown in FIG. 6(a). Even in this case, the imaginary vertical line V2 passes through the right half 64c of the conveying member 64, which is to the right of the imaginary vertical line V4. This makes it possible to quickly convey the powder that has fallen through the gap 67 in the axial direction.

[0060] 7 is a diagram showing an example of the arrangement of a plurality of sets of image forming units according to the first embodiment, together with intermediate transfer belt 41. In FIG. 7, developing device 33 (see FIG. 1) and the like are not shown. In the example shown in FIG. 7, the intermediate transfer belt 41 rotates in the direction of arrow C, and a plurality of sets of image forming units are arranged side by side in the horizontal direction. Image forming units 30Y, 30M, 30C, 30K, and 30P are arranged in this order from the upstream side to the downstream side of intermediate transfer belt 41. That is, image forming unit 30P, which forms a toner image using a special color toner, is at the most downstream side. In Figure 7, image forming unit 30T (see Figure 1) is not arranged, but it may be arranged between image forming units 30K and 30P.

[0061] 7, focusing on contact position 62a, image forming unit 30P is below imaginary horizontal plane H, and image forming unit 30K is also below imaginary horizontal plane H. Note that other image forming units 30Y, 30M, and 30C are also below imaginary horizontal plane H, just like image forming unit 30K.

[0062] 7, when we look at the angle at which line segment 62b intersects with virtual horizontal plane H, image forming unit 30P has angle θ5, and image forming unit 30K has angle θ4. Angle θ5 is larger than angle θ4 (θ5>θ4). Note that the other image forming units 30Y, 30M, and 30C also have angle θ4, just like image forming unit 30K.

[0063] The image forming units 30Y, 30M, 30C, and 30K can use the image forming unit 304 (see FIG. 5(b)). This is the reason why the reference numerals for the image forming units 30Y, 30M, 30C, and 30K in FIG. 7 are each accompanied by the number "304."

[0064] The example shown in FIG. 7 will be further explained. The up-down direction Y1 of the image forming unit 30K alone is the same direction as the imaginary vertical plane V1 when the image forming unit 30K is positioned relative to the unit body 1D of the printing unit 1B (see FIG. 1), and the up-down direction Y1 and the imaginary vertical plane V1 are parallel to each other. Similar to the image forming unit 30K, the up-down direction Y1 and the imaginary vertical plane V1 of the image forming units 30Y, 30M, and 30C are the same direction as each other. In FIG. 7, the imaginary vertical plane V1 and the up-down direction Y1 are shown overlapping each other for each of the image forming units 30Y, 30M, 30C, and 30K.

[0065] On the other hand, image forming unit 30P differs from image forming unit 30K in that the up-down direction Y1 and the imaginary vertical plane V1 are not parallel to each other but intersect. In image forming unit 30P, the up-down direction Y1 is tilted counterclockwise with respect to the imaginary vertical plane V1. In other words, the entire image forming unit 30P is rotated counterclockwise. The up-down direction Y1 of image forming unit 30P intersects with the imaginary vertical plane V1 at an angle θ6.

[0066] The angle θ6 here is the difference between the above-mentioned angle θ5 of image forming unit 30P and the above-mentioned angle θ4 of image forming unit 30K. In other words, the above-mentioned angle θ5 of image forming unit 30P is the sum of the angle θ4 of image forming unit 30K and the angle θ6 of image forming unit 30P. Therefore, image forming unit 30P is different from image forming unit 303 (see FIG. 5(a)). In FIG. 7, image forming unit 30P is indicated with the reference numeral "305" instead of "303."

[0067] In this way, the orientation of image forming unit 30P relative to unit main body 1D is different from the orientations of image forming units 30Y, 30M, 30C, and 30K relative to unit main body 1D. This causes angle θ5 of image forming unit 30P to be different from angle θ4 of image forming unit 30K, etc. Angle θ5 is an example of a first angle, and as described above, angle θ4 is an example of a second angle.

[0068] The orientation of image forming unit 30P is different from the orientations of image forming units 30Y, 30M, 30C, and 30K. That is, in the case shown in Fig. 7, the mounting angle of image forming unit 30P relative to unit main body 1D is different from the mounting angles of image forming units 30Y, 30M, 30C, and 30K relative to unit main body 1D. As a result, even if the same units are used for image forming units 30Y, 30M, 30C, and 30K and image forming unit 30P, adjusting the mounting angle makes it possible to accommodate image forming unit 30P, which generates more powder.

[0069] 8 is a diagram showing another example of the arrangement of a plurality of sets of image forming units according to the first embodiment, together with intermediate transfer belt 41. In FIG. 8, the developing device 33 (see FIG. 1) and the like are omitted. Also, among the reference numerals shown in FIG. 8, the explanation of the reference numerals mentioned above may be omitted. In the example shown in Figure 8, as in the case of Figure 7 described above, the intermediate transfer belt 41 rotates in the direction of arrow C, and image forming units 30Y, 30M, 30C, 30K, and 30P are arranged in order from the upstream side to the downstream side of the intermediate transfer belt 41.

[0070] In the example shown in FIG. 8, the image forming section 20 has a first image forming section 20A that includes image forming units 30Y, 30M, 30C, and 30K, and a second image forming section 20B that includes an image forming unit 30P.

[0071] The first image forming section 20A is equipped with a laser exposure device 26A, and the second image forming section 20B is equipped with a laser exposure device 26B. In the first image forming section 20A, the photosensitive drum 31 of each of the image forming units 30Y, 30M, 30C, and 30K is exposed by the laser exposure device 26A. In the second image forming section 20B, the photosensitive drum 31 of the image forming unit 30P is exposed by the laser exposure device 26B.

[0072] The laser exposure device 26A and the laser exposure device 26B have different exposure methods. The laser exposure device 26A includes an optical box and is equipped with, for example, a rotating polygon mirror, a scanning lens, a folding mirror, a separating polygon mirror, a reflecting mirror, and a cylindrical mirror. The laser exposure device 26A acquires image data for each color from the image processing unit 22 (see FIG. 1). The laser exposure device 26A then scans and exposes the photosensitive drums 31 of the image forming units 30Y, 30M, 30C, and 30K with four laser beams whose illumination is controlled based on the acquired image data.

[0073] Laser exposure device 26B includes an LED array having a plurality of light-emitting elements, a circuit board on which the LED array and a circuit for driving the LED array are mounted, and a rod lens array that focuses the light emitted from the LED array onto the surface of photosensitive drum 31. Laser exposure device 26B is disposed vertically above photosensitive drum 31 and exposes photosensitive drum 31 from vertically above.

[0074] The image forming units 30Y, 30M, 30C, and 30K of the first image forming section 20A can use the image forming unit 302 (see FIG. 4(b)). This is why the reference numerals of the image forming units 30Y, 30M, 30C, and 30K in FIG. 8 are each accompanied by the number "302."

[0075] The image forming unit 30P of the second image forming section 20B can use the image forming unit 301 (see FIG. 4(a)). For this reason, the image forming unit 30P in FIG. 8 is also labeled "301."

[0076] To explain further, in the second image forming section 20B, the drum cleaner 34 of the image forming unit 30P is disposed at a position shifted counterclockwise compared to, for example, the image forming unit 30K. In the second image forming section 20B, a laser exposure device 26B is provided in the space created above the image forming unit 30P by such an arrangement.

[0077] The second image forming section 20B also includes an image forming unit 30P that forms a toner image using a special color toner, and a laser exposure device 26B that exposes the image forming unit 30P. This makes it easy to add the second image forming section 20B to an image forming apparatus 1 that prints only in YMCK colors.

[0078] <Second embodiment> Next, a second embodiment will be described. Here, the powder scraped off by the blade 62 in the image forming unit 30 shown in FIG. 3 flows downward from the accumulation portion 66 through the gap 67 and is stored in the storage portion 61a. However, if the amount of powder scraped off by the blade 62 is large, the powder accumulated in the accumulation portion 66 may have difficulty moving downward through the gap 67. As the amount of powder in the accumulation portion 66 increases, the tip portion 65a of the contact member 65 is pushed toward the photosensitive drum 31. This makes it difficult for the powder to pass between the tip portion 65a of the contact member 65 and the surface 31a of the photosensitive drum 31. This may cause the powder on the surface 31a to be directly scraped off by the tip portion 65a. There is a concern that the powder scraped off by the tip portion 65a of the contact member 65 may soil the image forming unit 30, the intermediate transfer belt 41, etc.

[0079] Furthermore, the amount of powder scraped off by blade 62 in each of the multiple sets of image forming units is not always the same and varies depending on, for example, the toner ratio of the developed image. For example, the amount of powder scraped off by blade 62 may differ between image forming units 30Y, 30M, 30C, and 30K. Furthermore, of the multiple sets of image forming units, the amount of powder scraped off by image forming units 30T and 30P is generally greater than that of image forming units 30Y, 30M, 30C, and 30K. Consider a case where the volume of storage section 61a is the same for an image forming unit that scrapes off a large amount of powder and an image forming unit that scrapes off a small amount of powder. In the image forming unit that scrapes off a large amount of powder, the upper surface of the powder stored in storage section 61a becomes high enough to approach gap 67, making it difficult for the powder to pass through gap 67, which may reduce the ability of blade 62 to scrape off the powder from surface 31a of photosensitive drum 31. Therefore, in the second embodiment, the powder is prevented from being stored in the storage portion 61a to such a height that it becomes difficult for the powder to pass through the gap 67, thereby making it possible to suppress a decrease in removal performance.

[0080] 9A and 9B are diagrams illustrating an example of a drum cleaner 34 in a plurality of sets of image forming units according to the second embodiment. FIG. 9A shows one set of image forming units, 306, among the plurality of sets of image forming units, and FIG. 9B shows another set of image forming units, 307. Developing device 33 (see FIG. 1) and other components are omitted from FIG. 9B. The image forming unit 307 in FIG. 9B will be described as having a larger amount of powder removed by blade 62 than the image forming unit 306 in FIG. 9A.

[0081] The photosensitive drum 31 of the image forming unit 306 shown in FIG. 9(a) and the photosensitive drum 31 of the image forming unit 307 shown in FIG. 9(b) are at the same position in the up-down direction Y1 or at the same height. The relationship between the drum cleaner 34 of the image forming unit 306 and the drum cleaner 34 of the image forming unit 307 will be described, including their positional relationship with respect to the photosensitive drum 31. As described above, the drum cleaner 34 includes the main body 61, the blade 62, the partition member 63, and the conveying member 64. In Figure 9, the main body 61 of the image forming unit 306 and the main body 61 of the image forming unit 307 are the same.

[0082] The positional relationship between the photosensitive drum 31 and the partition member 63 in the image forming unit 306 is different from the positional relationship between the photosensitive drum 31 and the partition member 63 in the image forming unit 307. More specifically, the positions in the up-down direction Y1 of the lower end 63a of the partition member 63 are different between image forming unit 306 and image forming unit 307. The lower end 63a of image forming unit 307 is located higher than the lower end 63a of image forming unit 306. As shown in Fig. 9, when an imaginary horizontal plane H1 passing through the lower end 63a of image forming unit 306 is compared with an imaginary horizontal plane H2 passing through the lower end 63a of image forming unit 307, imaginary horizontal plane H2 is located higher than imaginary horizontal plane H1. The height positions of the imaginary horizontal planes H1 and H2 are examples of the positions of the lower ends of the arrangement members in the up-down direction.

[0083] The positional relationship between the photosensitive drum 31 and the main body 61 in the image forming unit 306 is the same as the positional relationship between the photosensitive drum 31 and the main body 61 in the image forming unit 307. More specifically, the positions in the up-down direction Y1 of the lower end 61c of the main body 61 are the same for the image forming units 306 and 307. As shown in FIG. 9, a virtual horizontal plane H3 passing through the lower end 61c of the image forming unit 306 also passes through the lower end 61c of the image forming unit 307.

[0084] If the difference in elevation between the virtual horizontal planes H1 and H3 is a distance L1, and the difference in elevation between the virtual horizontal planes H2 and H3 is a distance L2, then the distance L2 is longer than the distance L1 (L2>L1). The distances L1 and L2 are examples of the length in the up-down direction between the lower end of the arrangement member and the lower end of the accommodation portion.

[0085] In the case shown in FIG. 9, the positions of the blade 62 in the vertical direction Y1 are different between the image forming units 306 and 307, but it is also possible to make the positions in the vertical direction Y1 the same.

[0086] The volume of the storage section 61a of the main body 61 in FIG. 9 will be described. The amount of powder that can be stored in the storage section 61a differs between the image forming units 306 and 307. That is, the volume of the storage section 61a in the image forming units 306 and 307 differs from each other.

[0087] More specifically, the amount of powder that can be accommodated in the accommodation portion 61a of the image forming unit 307 is greater than the amount of powder that can be accommodated in the accommodation portion 61a of the image forming unit 306. As described above, this is because the amount of powder removed from the blade 62 is greater in the image forming unit 307 than in the image forming unit 306. This configuration prevents the powder from being stored in the storage portion 61a to a height that would make it difficult for the powder to pass through the gap 67 (see, for example, FIG. 3). The volume of the container 61a of either image forming unit 306 or image forming unit 307 is an example of the volume of one container, and the volume of the other container 61a is an example of the volume of the other container.

[0088] One example of such different volumes is realized by the positional relationship between the storage compartment 61a of the image forming units 306 and 307 and the imaginary horizontal planes H1 and H2, as shown in Fig. 9. That is, the volume of a portion R1 of the storage compartment 61a located below the imaginary horizontal plane H1 is different from the volume of a portion R2 of the storage compartment 61a located below the imaginary horizontal plane H2. The volume of the portion R2 is larger than the volume of the portion R1 (R2>R1).

[0089] 9, as described above, the main body 61 of the image forming unit 306 and the main body 61 of the image forming unit 307 are the same. Also, as described above, the imaginary horizontal plane H3 passes through the lower end 61c of the image forming unit 306 and also passes through the lower end 61c of the image forming unit 307. Therefore, in order to make the volumes different in the case of FIG. 9, the positions of the lower end 63a of the partition member 63 in the up-down direction Y1 are made different between the image forming unit 306 and the image forming unit 307.

[0090] 10A and 10B are diagrams illustrating another example of drum cleaner 34 in a plurality of sets of image forming units according to the second embodiment. Figure 10A shows one set of image forming units 308 among the plurality of sets of image forming units, and Figure 10B shows another set of image forming units 309. Image forming unit 309 in Figure 10B will be described as having a larger amount of powder removed by blade 62 than image forming unit 308 in Figure 10A.

[0091] The photosensitive drum 31 of the image forming unit 308 shown in FIG. 10(a) and the photosensitive drum 31 of the image forming unit 309 shown in FIG. 10(b) are at the same position in the up-down direction Y1 or at the same height.

[0092] The positional relationship between the photosensitive drum 31 and the partition member 63 in the image forming unit 308 is the same as the positional relationship between the photosensitive drum 31 and the partition member 63 in the image forming unit 309. More specifically, the positions in the up-down direction Y1 of the lower ends 63a of the partition members 63 are the same in the image forming units 308 and 309. As shown in Figure 10, a virtual horizontal plane H4 passing through the lower end 63a of the image forming unit 308 also passes through the lower end 63a of the image forming unit 309.

[0093] The positional relationship between the photosensitive drum 31 and the main body 61 in the image forming unit 308 is different from the positional relationship between the photosensitive drum 31 and the main body 61 in the image forming unit 309. More specifically, the positions in the up-down direction Y1 of the bottom end 61c of the main body 61 are different between the image forming units 308 and 309. The bottom end 61c of the image forming unit 309 is located lower than the bottom end 61c of the image forming unit 308. As shown in Fig. 10, when an imaginary horizontal plane H5 passing through the bottom end 61c of the image forming unit 308 is compared with an imaginary horizontal plane H6 passing through the bottom end 61c of the image forming unit 309, the imaginary horizontal plane H6 is located lower than the imaginary horizontal plane H5. The vertical position of the lower end 61c of the main body 61 is an example of the position of the lower end of the storage section.

[0094] If the difference in elevation between the virtual horizontal planes H4 and H5 is a distance L3, and the difference in elevation between the virtual horizontal planes H4 and H6 is a distance L4, then the distance L4 is longer than the distance L3 (L4>L3). The distances L3 and L4 are examples of the length in the up-down direction between the lower end of the arrangement member and the lower end of the accommodation portion.

[0095] 10, the main bodies 61 of the image forming units 308 and 309 are different from each other. That is, the size of the accommodating portion 61a of the image forming unit 309 is larger than the size of the accommodating portion 61a of the image forming unit 308, but this is not limited to this. It is also possible to make the accommodating portion 61a of the image forming unit 308 and the accommodating portion 61a of the image forming unit 309 the same size.

[0096] The volume of the storage section 61a of the main body 61 in FIG. 10 will be described. The amount of powder that can be stored in the storage section 61a differs between the image forming units 308 and 309. That is, the volume of the storage section 61a in the image forming units 308 and 309 differs from each other. More specifically, the amount of powder that can be accommodated in the accommodation portion 61a of the image forming unit 309 is greater than the amount of powder that can be accommodated in the accommodation portion 61a of the image forming unit 308. As described above, this is because the amount of powder removed from the blade 62 is greater in the image forming unit 309 than in the image forming unit 308. The volume of the container 61a of either the image forming unit 308 or the image forming unit 309 is an example of the volume of one container, and the volume of the other container 61a is the volume of the other container.

[0097] One example of such different volumes is realized by the positional relationship between the storage compartment 61a of the image forming units 308 and 309 and the imaginary horizontal planes H5 and H6, as shown in Fig. 10. That is, the volume of a portion R3 of the storage compartment 61a located above the imaginary horizontal plane H5 is different from the volume of a portion R4 of the storage compartment 61a located above the imaginary horizontal plane H6. The volume of the portion R4 is larger than the volume of the portion R3 (R4>R3).

[0098] 10, as described above, the virtual horizontal plane H4 passes through the lower end 63a of the image forming unit 308 and also passes through the lower end 63a of the image forming unit 309. Therefore, in order to make the volumes different from each other in the case of FIG. 9, the positions in the up-down direction Y1 of the lower end 61c of the main body 61 are made different between the image forming unit 308 and the image forming unit 309. In FIG. 10, the portion of main body 61 that forms storage portion 61a is configured differently between image forming unit 308 and image forming unit 309, but it is also possible to configure them to be the same.

[0099] 11 is a diagram showing an example of the arrangement of a plurality of sets of image forming units according to the second embodiment, together with an intermediate transfer belt 41. In FIG. 11, the developing device 33 (see FIG. 1) and the like are omitted from the illustration. The intermediate transfer belt 41 is an example of a transfer member. In the example shown in Fig. 11, intermediate transfer belt 41 rotates in the direction of arrow C, and multiple sets of image forming units are arranged side by side in the horizontal direction. Fig. 11 shows image forming units 30K and 30P, and omits other image forming units 30Y, 30M, 30C, etc. Note that image forming unit 30T (see Fig. 1) is not arranged in Fig. 11, but it may be arranged between image forming unit 30K and image forming unit 30P.

[0100] The intermediate transfer belt 41 is provided with a facing portion 411 that is disposed at a location facing the image forming units 30K and 30P, and an inclined portion 412 that is connected to the facing portion 411 and extends obliquely downward.

[0101] 11, image forming unit 30K is disposed at opposing portion 411 of intermediate transfer belt 41. Opposite inclined portion 412 is disposed storage portion 61a for image forming unit 30P. As described above, the amount of powder generated in image forming unit 30P is greater than the amount of powder generated in image forming unit 30K. When accommodating portion 61a of image forming unit 30P is disposed in facing portion 411, the size of accommodating portion 61a is limited to prevent interference with intermediate transfer belt 41.

[0102] By providing the inclined portion 412 on the intermediate transfer belt 41, a space 413 is formed on the surface side of the intermediate transfer belt 41. In the example shown in Fig. 11, such space 413 is utilized to provide the storage portion 61a of the image forming unit 30P at a location opposite the inclined portion 412. This does not limit the size of the storage portion 61a in the image forming unit 30P, and the volume of the storage portion 61a can be increased.

[0103] This will be explained in more detail. 11, the difference in height between the lower end 63a of the partition member 63 and the lower end 61c of the main body 61 in the image forming unit 30P is defined as a distance L5. The difference in height between the lower end 63a of the partition member 63 and the lower end 61c of the main body 61 in the image forming unit 30K is defined as a distance L6. Distance L5 in image forming unit 30P is longer than distance L6 in image forming unit 30K (L5>L6). As shown in FIG. 11, the portion of main body 61 that forms accommodating portion 61a in image forming unit 30P is larger than the portion of main body 61 that forms accommodating portion 61a in image forming unit 30K. Thus, in the example shown in FIG. 11, the volume of the container 61a in the image forming unit 30P is larger than the volume of the container 61a in the image forming unit 30K. The container 61a of either one of the image forming units 30K and 30P is an example of one container in one set, and the container 61a of the other is an example of the other container in the other set.

[0104] <Additional Notes> (((1))) an image carrier that is rotatable around a rotation axis and that holds an image; a removal unit that contacts the outer peripheral surface of the rotating image carrier and removes powder adhering to the outer peripheral surface of the image carrier; An image forming apparatus comprising: one or more image forming units each having the image carrier and the removing unit and forming an image are provided; a contact position where the removal unit contacts the outer peripheral surface of the image carrier in the set of image forming units or at least one of the sets of image forming units is below a virtual horizontal plane passing through the rotation axis of the image carrier; Image forming device. (((2))) A plurality of sets of the image forming units are provided, the image carrier in the one image forming unit, the contact position of which is below the virtual horizontal plane, is defined as one image carrier; the removal unit in the one image forming unit, the contact position of which is below the virtual horizontal plane, is defined as one removal unit; a contact position where the one removal portion contacts the outer peripheral surface of the one image carrier is defined as a first contact position; When a position where another of the removal units provided corresponding to another of the image carriers of another of the plurality of sets of image forming units contacts the outer peripheral surface of the other of the image carriers is defined as a second contact position, a first angle, which is an angle at which a line connecting the rotation axis of the one image carrier and the first contact position intersects with the virtual horizontal plane, and a second angle, which is an angle at which a line connecting the rotation axis of the other image carrier and the second contact position intersects with the virtual horizontal plane of the one image carrier, are different from each other; The image forming apparatus according to (((1))) is characterized in that (((3))) an attitude of the one image forming unit relative to the main body of the image forming apparatus and an attitude of the other image forming unit relative to the main body of the image forming apparatus are different from each other, so that the first angle and the second angle are different from each other; The image forming apparatus according to (((2))) is characterized in that (((4))) a storage section that stores the powder removed by the removal section and moving downward; a conveying unit that rotates around an axis to convey the powder contained in the container in the axial direction; Equipped with the image forming unit further includes the storage unit and the conveying unit, an imaginary vertical line extending downward from the contact position passes through the conveying unit; The image forming apparatus according to any one of (((1))) to (((3))) is characterized in that: (((5))) a forming member disposed opposite the image carrier, the forming member forming a space between the outer peripheral surface of the image carrier and the space in which the powder removed by the removing unit temporarily remains, and forming a gap through which the powder in the space passes downward; the image forming unit further includes the forming member, a virtual vertical line extending downward from the lower end of the forming member passes through the conveying section; The image forming apparatus according to (((4))) is characterized in that (((6))) the virtual vertical line passes through a portion of the conveying unit that moves the powder contained in the container unit toward the bottom of the container unit; The image forming apparatus according to (((5))) is characterized in that

[0105] According to the invention (((1))), it is possible to suppress a decrease in the removal performance of removing powder from the image carrier, compared to when the position at which the removal unit removes powder from the outer peripheral surface of the image carrier is above a virtual horizontal plane including the rotation axis. According to the invention (((2))), the first angle, which is the angle at which the line connecting the rotation axis of one image carrier and the first contact position intersects with the virtual horizontal plane, and the second angle, which is the angle at which the line connecting the rotation axis of another image carrier and the second contact position intersects with the virtual horizontal plane of the one image carrier, can suppress a decrease in removal performance for removing powder from the image carrier compared to when a configuration that is not different from each other is adopted. According to the invention of (((3))), since the attitude of one image forming unit relative to the main body of the image forming device is different from the attitude of the other image forming unit relative to the main body of the image forming device, it is possible to share components compared to a case where a configuration in which the first angle and the second angle are different from each other is not adopted. According to the invention of (((4))), the image forming unit is provided with a storage section that stores the powder removed by the removal section and directed downward, and a conveying section that rotates around its axis to convey the powder stored in the storage section in the axial direction, and the image forming unit further has the storage section and the conveying section, and the virtual vertical line extending downward from the contact position can more reliably convey the powder in the conveying section compared to when a configuration is not adopted in which the virtual vertical line passes through the conveying section. According to the invention (((5))), the virtual vertical line extending downward from the lower end of the forming member can more reliably transport powder in the transport section than in the case where a configuration passing through the transport section is not adopted. According to the invention of (((6))), the virtual vertical line can transport the powder in the transport section more quickly than in the case where a configuration is not adopted in which the virtual vertical line passes through the part of the transport section that moves the powder contained in the container section toward the bottom of the container section. [Explanation of symbols]

[0106] 1...image forming apparatus, 1D...unit body, 30, 30T, 30P, 30Y, 30M, 30C, 30K...image forming unit, 31...photosensitive drum, 31a...surface, 31b...rotation shaft, 61a...accommodation section, 61b...bottom, 62...blade, 62a...contact position, 62b...line segment, 63...partition member, 63a...lower end, 64...conveying member, 64c...right half, 66...reservoir section, 67...gap, H...virtual horizontal plane, V2, V3...virtual vertical line, θ1, θ2, θ3, θ4, θ5...angle

Claims

1. an image carrier that is rotatable around a rotation axis and that holds an image; a removal unit that contacts an outer peripheral surface of the rotating image carrier and removes powder adhering to the outer peripheral surface of the image carrier; An image forming apparatus comprising: one or more image forming units each having the image carrier and the removing unit and forming an image are provided; a contact position where the removal unit contacts the outer peripheral surface of the image carrier in the set of image forming units or at least one of the sets of image forming units is below a virtual horizontal plane passing through the rotation axis of the image carrier; Image forming device.

2. A plurality of sets of the image forming units are provided, the image carrier in the one image forming unit, the contact position of which is below the virtual horizontal plane, is defined as one image carrier; the removal unit in the one image forming unit, the contact position of which is below the virtual horizontal plane, is defined as one removal unit; a contact position where the one removal portion contacts the outer peripheral surface of the one image carrier is defined as a first contact position; When a position where another of the removal units provided corresponding to another of the image carriers of another of the plurality of sets of image forming units contacts the outer peripheral surface of the other of the image carriers is defined as a second contact position, a first angle, which is an angle at which a line connecting the rotation axis of the one image carrier and the first contact position intersects with the virtual horizontal plane, and a second angle, which is an angle at which a line connecting the rotation axis of the other image carrier and the second contact position intersects with the virtual horizontal plane of the one image carrier, are different from each other; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. an attitude of the one image forming unit relative to the main body of the image forming apparatus and an attitude of the other image forming unit relative to the main body of the image forming apparatus are different from each other, so that the first angle and the second angle are different from each other; 3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. a storage section that stores the powder removed by the removal section and moving downward; a conveying unit that rotates around an axis to convey the powder contained in the container in the axial direction; Equipped with the image forming unit further includes the storage unit and the conveying unit, a virtual vertical line extending downward from the contact position passes through the conveying unit; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. a forming member disposed opposite the image carrier, the forming member forming a space between the outer peripheral surface of the image carrier and the space in which the powder removed by the removing unit temporarily remains, and forming a gap through which the powder in the space passes downward; the image forming unit further includes the forming member, a virtual vertical line extending downward from the lower end of the forming member passes through the conveying section; 5. The image forming apparatus according to claim 4.

6. the imaginary vertical line passes through a portion of the conveying unit that moves the powder contained in the container unit toward the bottom of the container unit; 6. The image forming apparatus according to claim 5,

Images