Image forming apparatus

Abstract

An image forming apparatus includes: a first image generating unit that forms a toner image on an image holding body with a colored toner that does not contain a metallic pigment, and collects a waste toner removed from the image holding body; a second image generation unit that forms a toner image on an image holding body with a special color toner having an average toner particle diameter at least 20% larger than the colored toner, and that recovers waste toner removed from the image holding body; and a retention unit that, when recovering the waste toner removed from the image holding body, causes an amount of the waste toner temporarily retained on the image holding body to be substantially the same in the first image generation unit and the second image generation unit.

Description

Technical Field

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

[0002] A waste toner recovery device is known, which includes multiple waste toner recovery sections, a recovery box for storing the waste toner recovered by the waste toner recovery sections, and a waste toner conveying path for conveying the waste toner recovered by the waste toner recovery sections to the recovery box. Among the multiple waste toner recovery sections, a waste toner recovery section for recovering waste toner with poor fluidity is connected to the downstream side of the waste toner conveying path relative to the other waste toner recovery sections (Japanese Patent Laid-Open No. 2006-91038).

[0003] Also known is an image forming device comprising: a black image retaining body for retaining a black colorant image; a yellow image retaining body for retaining a yellow colorant image; a magenta image retaining body for retaining a magenta colorant image; a cyan image retaining body for retaining a cyan colorant image; a special color image retaining body for retaining a toner image of a special color other than black, yellow, magenta, and cyan; and a first recovery unit for recovering waste toner removed from the black image retaining body and waste toner removed from the special color image retaining body, and multiple recovery units for respectively recovering waste toners (Japanese Patent Gazette No. 2021-157051). Summary of the Invention

[0004] The present invention suppresses variation in the amount of waste toner temporarily retained on each image holding member when collecting waste toner removed from a plurality of image holding members.

[0005] According to a first embodiment of the present invention, there is provided an image forming apparatus comprising: a first image generating unit, which forms a toner image on an image retaining member using a colored toner that does not contain a metallic pigment and recovers waste toner removed from the image retaining member; a second image generating unit, which forms a toner image on an image retaining member using a special color toner having an average toner particle size that is at least 20% larger than that of the colored toner and recovers waste toner removed from the image retaining member; and a retention unit, which, when recovering the waste toner removed from the image retaining member, makes the amount of the waste toner temporarily retained on the image retaining member substantially the same in the first image generating unit and the second image generating unit.

[0006] According to the second embodiment of the present invention, in the image forming apparatus according to the first embodiment, the retention unit is formed by the image retaining body, the cleaning body that contacts the surface of the image retaining body and scrapes the waste colorant, and a sheet body that is arranged opposite to the image retaining body and forms an opening for discharging the waste colorant to form a space, so that the waste colorant scraped by the cleaning body is temporarily retained in the space.

[0007] According to the third aspect of the present invention, in the image forming device involved in the second aspect, the thickness of the sheet of the retention unit in the second image generating unit is made thinner than the thickness of the sheet of the retention unit in the first image generating unit, and the amount of the waste colorant temporarily retained on the image retaining body is made substantially the same.

[0008] According to the fourth scheme of the present invention, in the image forming device involved in the second or third scheme, the cut width of the sheet of the retention unit in the second image generating unit is made wider than the cut width of the sheet of the retention unit in the first image generating unit, and the amount of the waste colorant temporarily retained on the image retaining body is made substantially the same.

[0009] According to the fifth embodiment of the present invention, in the image forming device involved in any one of the second to fourth embodiments, the opening of the retention unit in the second image generating unit is made larger than the opening of the retention unit in the first image generating unit, and the amount of the waste colorant temporarily retained on the image retaining body is made substantially the same.

[0010] According to the sixth embodiment of the present invention, in the image forming device involved in any one of the second to fifth embodiments, the distance between the sheet body and the image retaining body of the retention unit in the second image generating unit is made larger than the distance between the sheet body and the image retaining body of the retention unit in the first image generating unit, and the amount of the waste colorant temporarily retained on the image retaining body is made substantially the same.

[0011] According to the seventh embodiment of the present invention, in the image forming device involved in any one of the second to sixth embodiments, the Young's modulus of the sheet of the retention unit in the second image generating unit is made smaller than the Young's modulus of the sheet of the retention unit in the first image generating unit, and the amount of the waste colorant temporarily retained on the image retaining body is made substantially the same.

[0012] According to the eighth embodiment of the present invention, in the image forming device involved in any one of the second to seventh embodiments, the angle of the retention unit in the second image generating unit relative to the plumb direction of the sheet is made smaller than the angle of the retention unit in the first image generating unit relative to the plumb direction of the sheet, and the amount of the waste colorant temporarily retained on the image retaining body is made substantially the same.

[0013] According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, the image holding member is uniformly charged by contact charging.

[0014] (Effect)

[0015] According to the first aspect, when collecting waste toner removed from a plurality of image holding members, it is possible to suppress variations in the amount of waste toner temporarily retained on each image holding member.

[0016] According to the second aspect, the contact between the cleaning element and the image holding element can be stabilized.

[0017] According to the third aspect, it is possible to prevent an increase in the amount of waste toner temporarily retained in the second image generating unit.

[0018] According to the fourth aspect, it is possible to prevent an increase in the amount of waste toner temporarily stagnating in the second image generating unit.

[0019] According to the fifth aspect, it is possible to prevent an increase in the amount of waste toner temporarily retained in the second image generating unit.

[0020] According to the sixth aspect, it is possible to prevent an increase in the amount of waste toner temporarily stagnating in the second image generating unit.

[0021] According to the seventh aspect, it is possible to prevent an increase in the amount of waste toner temporarily retained in the second image generating unit.

[0022] According to the eighth aspect, it is possible to prevent an increase in the amount of waste toner temporarily retained in the second image generating unit.

[0023] According to the ninth aspect, the image generating unit can be miniaturized. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic cross-sectional view showing an example of a schematic structure of an image forming apparatus;

[0025] Figure 2 is a schematic longitudinal sectional view showing a photosensitive body unit and a developing device;

[0026] Figure 3(a) is a schematic cross-sectional view illustrating image formation on colored paper or a transparent label in an image forming apparatus, Figure 3 (b) is an explanatory diagram showing an example of an image structure of a recording medium having an image formed on colored paper or a transparent label;

[0027] Figure 4 (a) is a schematic cross-sectional view schematically showing the thickness direction of the bright toner particles. Figure 4 (b) is a schematic cross-sectional view illustrating reflection of light by the bright toner after fixation;

[0028] Figure 5 is a schematic cross-sectional view showing the structure of a cleaning device in a photoreceptor unit;

[0029] Figure 6 is a schematic diagram showing an example of a blocking member;

[0030] Figure 7 It is a cross-sectional schematic diagram illustrating the structure around the cleaning blade in the cleaning device and the toner accumulation area;

[0031] Figure 8 A diagram illustrating a toner accumulation location when the thickness of the sealing member is changed;

[0032] Figure 9 A diagram illustrating a toner accumulation location when the opening of the blocking member is changed;

[0033] Figure 10 A diagram illustrating a toner accumulation location when the distance between the sealing member and the photosensitive drum is changed;

[0034] Figure 11 This is a diagram illustrating a toner pool when the angle of the sealing member with respect to the plumb bob direction is changed. DETAILED DESCRIPTION

[0035] Next, the present invention will be described in further detail with reference to the accompanying drawings by giving embodiments and specific examples below, but the present invention is not limited to these embodiments and specific examples.

[0036] In the following description using the drawings, it should be noted that the drawings are schematic, ratios of dimensions, etc. are different from actual dimensions, and illustrations other than components necessary for easy understanding are omitted as appropriate.

[0037] (1) Overall structure and operation of image forming apparatus

[0038] (1.1) Overall Structure of Image Forming Apparatus

[0039] Figure 1is a schematic cross-sectional view showing an example of a schematic structure of the image forming apparatus 1 according to the present embodiment. Figure 2 It is a schematic longitudinal sectional view showing the photoconductor unit 13 and the developing device 14 .

[0040] The image forming apparatus 1 includes an image forming unit 10, a paper feeding device 20 installed below the image forming unit 10, a paper discharge unit 30 provided at one end of the image forming unit 10 for discharging printed paper, an operation display unit 40, and an image processing unit 50 for generating image information based on print information sent from a host device.

[0041] The image forming unit 10 includes a system control device 11, an exposure device 12, a photosensitive unit 13, a developing device 14, a transfer device 15, paper conveying devices 16a, 16b, 16c, and a fixing device 17, and forms the image information received from the image processing unit 50 as a colorant image on the recording medium fed from the paper feeding device 20.

[0042] The paper feeding device 20 supplies recording media to the image forming unit 10. Specifically, the paper feeding device 20 includes a plurality of paper loading sections for accommodating recording media of different types (e.g., material, thickness, paper size, or paper strands), and is configured to supply the image forming unit 10 with a recording medium discharged from any of the plurality of paper loading sections.

[0043] The paper discharge unit 30 discharges recording media that have been image-output by the image forming unit 10. Therefore, the paper discharge unit 30 includes a paper accommodating portion T1 for discharging recording media after image output. Alternatively, the paper discharge unit 30 may be a component that performs post-processing such as cutting or stapling the bundle of paper output from the image forming unit 10.

[0044] The operation display unit 40 is used for inputting various settings and instructions and displaying information. Specifically, it is composed of components corresponding to a so-called user interface, and specifically, is composed of a combination of a liquid crystal display panel, various operation buttons, a touch panel, and the like.

[0045] (1.2) Structure and Operation of Image Forming Unit

[0046] In the image forming apparatus 1 having such a configuration, a recording medium discharged from a paper loading portion designated for each sheet printed in a print job in the paper feed device 20 is fed into the image forming unit 10 in timing with image formation.

[0047] The photoreceptor units 13 (Y, M, C, K, X, W: hereinafter referred to as photoreceptor units 13 unless otherwise specified) are arranged in parallel below the exposure device 12 and include a photoreceptor drum 31 serving as a rotationally driven image holder. Along the rotational direction of the photoreceptor drum 31 (indicated by the arrow in the figure), a charging roller 32, an exposure device 12, a developing device 14, a primary transfer roller 52, and a cleaning device 33 are arranged. The cleaning device 33 is provided with a cleaning blade 37 for removing toner remaining on the photoreceptor drum 31. The cleaning blade 37 contacts the surface of the photoreceptor drum 31 and scrapes off the toner remaining on the surface of the photoreceptor drum 31. In the following description, the cleaning device 33 provided in each of the photoreceptor units 13Y, 13M, 13C, 13K, 13X, and 13W may be referred to as cleaning devices 33Y, 33M, 33C, 33K, 33X, and 33W.

[0048] The photoreceptor units 13Y, 13M, 13C, and 13K respectively form images of yellow (Y), magenta (M), cyan (C), and black (K) (hereinafter, the colors of the colored toners that do not contain metallic pigments are sometimes marked as ordinary colors.). In addition, the photoreceptor unit 13X forms an image of a special color that is different from the ordinary colors. Here, the special color is a color that is different from the ordinary color, for example, a color that is difficult to achieve by using the ordinary color toners of yellow (Y), magenta (M), cyan (C), and black (K). As such special colors, specifically, metallic colors such as gold and silver colored with brilliant colorants containing metallic pigments can be cited. The photoreceptor unit 13W uses a white toner (W) to form a white toner image. In addition, in Figure 1 In the figure, photoreceptor unit 13X and photoreceptor unit 13W are shown arranged downstream of photoreceptor unit 13K in the direction of movement of intermediate transfer belt 51. However, photoreceptor units 13X and 13W can also be selected and replaced in accordance with the image being formed. Furthermore, special colors are not limited to metallic colors; examples include red, green, and blue. It is known that the average toner particle size of these special colors is at least 20% larger than that of standard colors, and their fluidity is lower than that of standard colors.

[0049] The developing device 14 includes a developing housing 41 that contains a developer. A developing roller 42 is disposed within the developing housing 41 so as to face the photosensitive drum 31. The developer with a controlled layer thickness is supplied to the developing roller 42, and a toner image is formed on the photosensitive drum 31.

[0050] Each developing device 14 (Y, M, C, K, X, W: hereinafter referred to as the developing device 14 when no distinction is required) is constructed in a roughly similar manner except for the developer contained in the developing housing 41, and forms colorant images of yellow (Y), magenta (M), cyan (C), black (K), special color (X), and white (W), respectively.

[0051] Disposed above the developing device 14 are replaceable toner cartridges TC storing toner and a toner supply device (not shown) that supplies toner and carrier from each toner cartridge TC to the developing device 14 .

[0052] The surface of the rotating photosensitive drum 31 is charged by the charging roller 32, and an electrostatic latent image is formed by latent image forming light emitted from the exposure device 12. The electrostatic latent image formed on the photosensitive drum 31 is developed into a toner image by the developing roller 42.

[0053] The transfer device 15 includes an intermediate transfer belt 51 that transfers the color toner images formed on the photosensitive drum 31 of each photosensitive unit 13 multiple times, a primary transfer roller 52 that sequentially transfers (primary transfer) the color toner images formed on each photosensitive unit 13 to the intermediate transfer belt 51, and a secondary transfer roller 53 that transfers (secondary transfer) the color toner images overlapped and transferred on the intermediate transfer belt 51 to a recording medium once.

[0054] The color toner images formed on the photosensitive drums 31 of the photosensitive body units 13 are sequentially electrostatically transferred (primary transfer) to the intermediate transfer belt 51 by the primary transfer roller 52 to which a predetermined transfer voltage is applied from a power supply device (not shown) controlled by the system control device 11, thereby forming overlapping colorant images in which the color toners of each color overlap.

[0055] The superimposed toner images on the intermediate transfer belt 51 are conveyed on the support roller 65 via the intermediate transfer belt 51 as the intermediate transfer belt 51 moves to the secondary transfer portion TR where the secondary transfer roller 53 is arranged in pressure contact.

[0056] When the overlapping toner images are conveyed to the secondary transfer section TR, a recording medium is supplied to the secondary transfer section TR from the paper feed device 20 in accordance with this timing. A predetermined secondary transfer voltage is then applied from a power supply device (not shown) controlled by the system control device 11 to the backup roller 65, which faces the secondary transfer roller 53 across the intermediate transfer belt 51. The multiple layers of toner images on the intermediate transfer belt 51 are transferred onto the recording medium at once.

[0057] The residual toner on the surface of the photosensitive drum 31 is removed by the cleaning blade 37 of the cleaning device 33 and collected in a waste toner storage box (not shown). The surface of the photosensitive drum 31 is recharged by the charging roller 32 .

[0058] The fixing device 17 includes an endless fixing belt 17a rotating in one direction and a pressure roller 17b rotating in one direction in contact with the peripheral surface of the fixing belt 17a. A nip portion (fixing area) is formed by the pressure contact area between the fixing belt 17a and the pressure roller 17b.

[0059] In the transfer device 15, the recording medium to which the toner image has been transferred is conveyed to the fixing device 17 via the paper conveying device 16a while the toner image is not fixed. The recording medium conveyed to the fixing device 17 passes through a pair of fixing belts 17a and a pressure roller 17b, where the toner image is fixed by pressure and heat.

[0060] The recording medium after fixing is fed to the paper discharge section 30 and loaded on the paper discharge storage section T1. In addition, post-processing such as cutting and stapling (binding) is performed as needed.

[0061] (1.3) Image formation on a colored or transparent recording medium other than white

[0062] Figure 3 (a) is a schematic cross-sectional view illustrating image formation on colored paper CP or transparent label CS in the image forming apparatus 1, Figure 3 (b) is an explanatory diagram showing an example of an image structure of a recording medium in which an image is formed on colored paper CP or a transparent label CS.

[0063] In the image forming device 1 of this embodiment, a color image including yellow colorant (Y), magenta colorant (M), cyan colorant (C), and black colorant (K) as common colors is formed on a recording medium with colors other than white, such as black, blue, red, etc., i.e., colored paper CP or a transparent label CS.

[0064] Furthermore, the following image forming operation can be performed: a white toner image WT is formed using a white toner (W), a special color different from the normal colors, so as to form the bottom layer of the image forming surface of the colored paper CP or the transparent label CS, where a color image is formed. Here, the white toner (W) has an average toner particle size that is at least 20% larger than that of the normal color toners (Y, M, C, K), thereby improving the concealment of the colored paper CP and the transparent label CS.

[0065] like Figure 3As shown in (a), in the image forming device 1, the photosensitive unit 13W and the developing device 14W, which are the second image generating unit for forming a white colorant image WT using white colorant (W), are arranged on the downstream side of the rotational movement direction of the intermediate transfer belt 51 than the photosensitive unit 13Y, 13M, 13C, 13K and the developing devices 14Y, 14M, 14C, 14K, which are the first image generating unit for forming overlapping colorant images (YMCK) of each color using colorants of yellow (Y), magenta (M), cyan (C), and black (K) as ordinary colors.

[0066] In the image forming apparatus 1 configured as described above, when transferring an image from the intermediate transfer belt 51 onto colored paper CP or a transparent label CS, a superimposed toner image, in which color images of yellow (Y), magenta (M), cyan (C), and black (K) are superimposed, is first formed on the intermediate transfer belt 51. A white toner image (WT) is then primarily transferred to overlap the superimposed toner image (YMCK). The colored paper or transparent label is then fed from the paper feed device 20 to the secondary transfer section (TR), where the color image, with the white toner image WT, which was primarily transferred to the outer peripheral surface of the intermediate transfer belt 51, is secondarily transferred to the colored paper or transparent label.

[0067] Therefore, if Figure 3 As schematically shown in (b), a recording medium is produced in which the background color of the colored paper is masked by a white toner image and a superimposed toner image (YMCK) is formed by superimposing color images of each color. Separately, a recording medium is produced in which a transparent label CS is masked by a white toner image so as not to be transmissive and a superimposed toner image (YMCK) is formed by superimposing color images of each color.

[0068] (1.4) Image formation of metal image

[0069] Figure 4 (a) is a schematic cross-sectional view schematically showing the thickness direction of the bright toner particles S. Figure 4 (b) is a schematic cross-sectional view illustrating reflection of light by the bright toner after fixing.

[0070] In this embodiment, the photoreceptor unit 13X and the developing device 14X, which form an image in a special color (X) as needed, are arranged downstream of the photoreceptor units 13Y, 13M, 13C, and 13K and the developing devices 14Y, 14M, 14C, and 14K for normal colors in the direction of rotation of the intermediate transfer belt 51. Examples of the special color (X) include bright toners that contain a metallic pigment, a predetermined pigment, and a binder resin and impart a metallic luster (metallic) to the image.

[0071] like Figure 4 As shown schematically in (a), the bright toner is a flat bright toner particle S with an equivalent circle diameter longer than its thickness L, and contains a scaly metallic pigment G, a type of bright pigment. Bright toners such as gold and silver are flattened so that the bright pigment inside the toner is oriented parallel to the long axis of the toner. As a result, the bright pigment of the toner transferred to a medium MD such as paper or film is parallel to the medium, as shown in FIG. Figure 4 As shown in (b), the reflection of light from the pigment is enhanced in the image after fixing, thereby exhibiting high brilliance and creating a metallic feel.

[0072] When forming a metallic image using brilliant toner, special colors (X) such as yellow (Y), magenta (M), cyan (C), black (K), gold, or silver (brilliant) are first multiply transferred onto the intermediate transfer belt 51. The recording medium is then fed from the paper feed device 20 to the secondary transfer section (TR). The color image, which includes the special color toner image and has been primarily transferred to the outer peripheral surface of the intermediate transfer belt 51, is then secondary transferred onto the recording medium and then fixed by heat and pressure in the fixing device 17.

[0073] (2) Cleaning device

[0074] Figure 5 is a schematic cross-sectional view showing the structure of the cleaning device 33 in the photoreceptor unit 13, Figure 6 1 is a schematic diagram showing an example of a blocking member 38. Figure 7 3 is a schematic cross-sectional view illustrating the structure around the cleaning blade 37 in the cleaning device 33 and the toner accumulation area. Figure 8 1 is a diagram illustrating a toner accumulation location when the thickness of the sealing member 38 is changed. Figure 9 1 is a diagram illustrating a toner accumulation location when the opening G of the blocking member 38 is changed. Figure 10 3 is a diagram illustrating a toner accumulation location when the distance between the sealing member 38 and the photosensitive drum 31 is changed. Figure 11 This is a diagram illustrating a toner pool when the angle θ of the sealing member 38 with respect to the plumb line direction is changed.

[0075] Next, the recovery of residual toner in the image forming apparatus 1 including the photoreceptor unit 13 and the developing device 14 for special colors in addition to normal colors will be described with reference to the drawings.

[0076] (2.1) Structure of cleaning device

[0077] The main parts of the cleaning device 33 are composed of the following components: a shell 34 arranged at a position opposite to the photosensitive drum 31; a sealing component 35 supported by the lower edge of the opening provided in the shell 34; a colorant recovery screw conveyor 36 that transports the waste colorant recovered in the shell 34; a cleaning scraper 37 arranged in contact with the surface of the photosensitive drum 31 to scrape off the recovered material on the photosensitive drum 31; and a sealing component 38 as an example of a sheet body arranged at the front end portion of the support component 37A that fixes and supports the cleaning scraper 37 on the shell 34 on the opposite side to the cleaning scraper 37.

[0078] The cleaning device 33 is detachably attached to the image forming apparatus 1 as a photoconductor unit 13 integrally formed with the photoconductor drum 31 and the like.

[0079] The housing 34 temporarily stores toner and paper dust removed from the surface of the photosensitive drum 31 by the cleaning blade 37 and has an opening OP facing the photosensitive drum 31. The cleaning blade 37 and the sealing member 35 are provided in the opening OP and are in contact with the photosensitive drum 31.

[0080] The sealing member 35 is fixedly supported at the lower end of the opening on the lower side of the housing 34, and seals the gap between the photosensitive drum 31 and the housing 34 to prevent the recovered toner recovered in the cleaning device 33 from leaking out of the cleaning device 33. For example, a thermoplastic polyurethane film with a thickness of 0.1 mm can be used for the sealing member 35.

[0081] The toner recovery auger 36 is composed of a screw, and conveys the waste toner and the like removed from the surface of the photosensitive drum 31 and stored in the housing 34 to a waste toner box (not shown) while stirring the waste toner.

[0082] The cleaning blade 37 is made of a material having excellent mechanical properties such as wear resistance, notch resistance, and creep resistance, such as polyurethane rubber such as thermosetting polyurethane rubber, and is fixedly supported on the housing 34 by a support member 37A having an L-shaped cross-section. The front end 37a of the cleaning blade 37 contacts the surface of the photosensitive drum 31 at a predetermined contact pressure, thereby removing toner, paper dust, and the like from the surface of the photosensitive drum 31.

[0083] The blocking member 38 blocks the toner scraped from the surface of the photosensitive drum 31 and accumulates it upstream in the rotation direction of the photosensitive drum 31 (in the direction of the arrow in the figure) at the contact position between the cleaning blade 37 and the photosensitive drum 31 .

[0084] As described later, the sealing member 38 is a sheet having a predetermined thickness, and its longitudinal width (length in the axial direction of the photosensitive drum 31 ) is adjusted to be approximately the same as the longitudinal width of the cleaning blade 37 .

[0085] Examples of the material of the blocking member 38 include resins such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), and polyurethane (PU). Among them, polyethylene terephthalate (PET) is preferred.

[0086] As will be described later, the thickness of the sealing member 38 is set according to the type of the recovered toner, that is, whether it is toner of a normal color or toner of a special color.

[0087] In addition, if Figure 6 As shown, the blocking member 38 has cutouts 38A (slits) opened from the front end with a cutout width W formed at regular intervals over the entire area in the longitudinal direction.

[0088] As a result, part of the toner accumulated in the toner reservoir leaks out of the cutout through the sealing member 38 , making it easier to replace the toner. This suppresses aggregation of toner particles and external additives, and facilitates improved cleanability.

[0089] In this embodiment, as will be described later, the cutout width W of the cutout 38A is set according to the type of toner to be collected, that is, whether it is toner of a normal color or toner of a special color.

[0090] (2.2) Function of cleaning device

[0091] The cleaning device 33 cleans the recovered material on the photosensitive drum 31 after the toner image is primarily transferred to the intermediate transfer belt 51. The recovered material includes residual developer (toner and external additives) and foreign matter such as paper dust attached to the photosensitive drum 31 from the recording medium.

[0092] The corner 37a at the front end of the cleaning scraper 37 contacts the surface of the photosensitive drum 31 at an acute angle relative to the rotation direction of the photosensitive drum 31 (ink scraping method) to form a cleaning bite portion N (hereinafter referred to as the bite portion N), which removes the recovered materials on the photosensitive drum 31 by scraping them off.

[0093] like Figure 7 As shown, when the photosensitive drum 31 is driven to rotate in the direction of the arrow, the colorant T that has not been transferred and remains (indicated by a white circle in the figure) is blocked at the front end of the nip portion N (the area on the upstream side of the rotation direction of the photosensitive drum 31 where the cleaning scraper 37 contacts the photosensitive drum 31, hereinafter also referred to as the "front nip area PN"), forming a colorant accumulation area P surrounded by the sealing component 38, the cleaning scraper 37, and the surface of the photosensitive drum 31.

[0094] On the other hand, when toner particles containing an external additive AD are applied to the image forming apparatus 1, the external additive AD is released from the toner particles due to external forces, such as mechanical loads during agitation in the developing device 14 and mechanical loads caused by scraping at the cleaning nip. When the released external additive AD (represented by dots in the figure) reaches the nip N, it is intercepted in the pre-nip region PN at a position closer to the contact point between the cleaning blade 37 and the photosensitive drum 31 than the toner reservoir P, forming an aggregate (hereinafter also referred to as the "external additive reservoir AP") that is gathered by the pressure from the cleaning blade 37. It is known that this external additive reservoir AP improves cleaning performance (toner scraping performance).

[0095] Since the cleaning device 33 of this embodiment includes a sealing member 38 on the back side of the cleaning blade 37, the amount of toner remaining in the toner reservoir P is generally increased compared to a case without the sealing member 38. This also facilitates the supply of the external additive AD to the external additive reservoir AP formed in the front nip portion PN, closer to the contact point with the photosensitive drum 31. As a result, the external additive reservoir AP is stably and easily formed at the front end of the nip portion N, ensuring lubricity in the nip portion N.

[0096] On the other hand, in the photoreceptor unit 13W and the photoreceptor unit 13X, which are the second image generating units, white toner (W) and brilliant toner (X) are used, which are different from the normal colors of yellow (Y), magenta (M), cyan (C), and black (K). It is known that the average toner particle size of the white toner (W) is at least 20% larger than that of the normal color toners (Y, M, C, K), and the fluidity is low. In addition, as Figure 4 As schematically shown in (a), the shape of the brilliant colorant (X) is flat, so that the brilliant pigment G inside the colorant is oriented parallel to the long axis direction of the colorant. Typically, this brilliant colorant (X) has an average long axis length of 7 μm or more and 20 μm or less, and an average thickness of 1 μm or more and 3 μm or less. Therefore, it is known that it has a high uniaxial collapse stress and low fluidity compared to ordinary color toners (Y, M, C, K). Therefore, in the photoreceptor unit 13W using white toner (W) and the photoreceptor unit 13X using brilliant toner (X), the amount of accumulated toner in the toner storage area P is greater than that in the photoreceptor units 13Y, 13M, 13C, and 13K using ordinary color toners (Y, M, C, K), and there is a possibility that the toner deposits that are difficult to recover into the housing 34 will become lumps and fall "dripping".

[0097] In this embodiment, a cleaning device 33 is provided, which, when recovering the residual colorant removed from the photosensitive drum 31 (the residual colorant recovered by the cleaning scraper is sometimes referred to as "waste colorant"), makes the amount of waste colorant temporarily retained on the photosensitive drum 31 substantially the same in the photosensitive units 13Y, 13M, 13C, and 13K serving as the first image generating unit and the photosensitive unit 13W and the photosensitive unit 13X serving as the second image generating unit.

[0098] Specifically, a toner storage space is formed by the photosensitive drum 31, the cleaning scraper 37 that contacts the surface of the photosensitive drum 31 and scrapes away waste toner, and the sealing member 38 that is arranged opposite to the photosensitive drum 31 and forms an opening G for discharging the waste toner, so that the amount of waste toner scraped by the cleaning scraper 37 and temporarily retained in the toner storage space is substantially the same in the photosensitive units 13Y, 13M, 13C, 13K and the photosensitive unit 13W, 13X.

[0099] More specifically, if Figure 8 As shown, by making the thickness t of the blocking member 38 in the photoreceptor unit 13W and the photoreceptor unit 13X thinner than the thickness of the blocking member 38 in the photoreceptor units 13Y, 13M, 13C, and 13K, the blocking member 38 is easily bent toward the housing 34 (see arrow R in the figure), thereby suppressing the amount of waste toner temporarily retained in the toner reservoir space and keeping it substantially the same. This prevents an increase in the amount of waste toner temporarily retained in the photoreceptor unit 13W and the photoreceptor unit 13X.

[0100] In addition, the cutout width W (see FIG. 1 ) of the sealing member 38 in the photoreceptor unit 13W and the photoreceptor unit 13X is set to Figure 6 The width W in the cutouts (W) is wider than the cutout width W of the sealing member 38 in the photoreceptor units 13Y, 13M, 13C, and 13K, thereby suppressing the amount of waste toner temporarily stagnating in the toner reservoir space to be substantially the same. This prevents an increase in the amount of waste toner temporarily stagnating in the photoreceptor units 13W and 13X.

[0101] In addition, if Figure 9 As shown, the opening G of the sealing member 38 in the photoreceptor unit 13W and the photoreceptor unit 13X is made larger than the opening G of the sealing member 38 in the photoreceptor units 13Y, 13M, 13C, and 13K, thereby suppressing the amount of waste toner temporarily stagnating in the toner reservoir space and making them substantially the same. This prevents an increase in the amount of waste toner temporarily stagnating in the photoreceptor units 13W and 13X.

[0102] In addition, if Figure 10As shown, the distance δ between the sealing member 38 and the photoreceptor drum 31 in the photoreceptor units 13W and 13X is set larger than the distance between the sealing member 38 and the photoreceptor drum 31 in the photoreceptor units 13Y, 13M, 13C, and 13K, so that the amount of waste toner temporarily retained on the photoreceptor drum 31 is substantially the same. This prevents an increase in the amount of waste toner temporarily retained in the photoreceptor units 13W and 13X.

[0103] Furthermore, by making the Young's modulus of the sealing member 38 in the photoreceptor unit 13W and the photoreceptor unit 13X smaller than the Young's modulus of the sealing member 38 in the photoreceptor units 13Y, 13M, 13C, and 13K, the amount of waste toner temporarily accumulated on the photoreceptor drum 31 is suppressed to be substantially the same. This prevents an increase in the amount of waste toner temporarily accumulated in the photoreceptor units 13W and 13X.

[0104] In addition, if Figure 11 As shown, the angle θ of the blocking member 38 relative to the plumb line in the photoreceptor units 13W and 13X is made smaller than the angle θ of the blocking member 38 relative to the plumb line in the photoreceptor units 13Y, 13M, 13C, and 13K, thereby suppressing the amount of waste toner temporarily retained on the photoreceptor drum 31 to be substantially the same. This prevents an increase in the amount of waste toner temporarily retained in the photoreceptor units 13W and 13X.

[0105] (Note) (((1)))

[0107] An image forming apparatus comprising:

[0108] a first image forming unit that forms a toner image on an image holding member using a colored toner that does not contain a metallic pigment and collects waste toner removed from the image holding member;

[0109] a second image forming unit that forms a toner image on an image holding member using a special color toner having an average toner particle size at least 20% larger than that of the color toners, and collects waste toner removed from the image holding member; and

[0110] The accumulation unit makes the amount of the waste toner temporarily accumulated on the image holding member substantially the same in the first image generating unit and the second image generating unit when collecting the waste toner removed from the image holding member. (((2)))

[0112] The image forming apparatus according to (((1))), wherein

[0113] The retention unit is formed by the image retaining body, a cleaning body that contacts the surface of the image retaining body and scrapes the waste toner, and a sheet body that is arranged opposite to the image retaining body and forms an opening for discharging the waste toner to form a space, so that the waste toner scraped by the cleaning body is temporarily retained in the space. (((3)))

[0115] The image forming apparatus according to (((2))), wherein

[0116] The thickness of the sheet of the accumulation unit in the second image generating unit is made thinner than the thickness of the sheet of the accumulation unit in the first image generating unit, and the amount of the waste toner temporarily accumulated on the image holding member is made substantially the same. (((4)))

[0118] The image forming apparatus according to (((2))) or (((3))), wherein

[0119] The slit width of the sheet of the accumulation unit in the second image generating unit is made wider than the slit width of the sheet of the accumulation unit in the first image generating unit, and the amount of the waste toner temporarily accumulated on the image holding member is made substantially the same. (((5)))

[0121] The image forming apparatus according to any one of (((2))) to (((4))), wherein

[0122] The opening of the accumulation unit in the second image generating unit is made larger than the opening of the accumulation unit in the first image generating unit, and the amount of the waste toner temporarily accumulated on the image holding member is made substantially the same. (((6)))

[0124] The image forming apparatus according to any one of (((2))) to (((5))), wherein

[0125] The distance between the sheet of the retention unit in the second image generating unit and the image retaining member is made larger than the distance between the sheet of the retention unit in the first image generating unit and the image retaining member, and the amount of the waste colorant temporarily retained on the image retaining member is made substantially the same. (((7)))

[0127] The image forming apparatus according to any one of (((2))) to (((6))), wherein

[0128] The Young's modulus of the sheet of the retention unit in the second image generating unit is made smaller than the Young's modulus of the sheet of the retention unit in the first image generating unit, and the amount of the waste toner temporarily retained on the image holding member is made substantially the same. (((8)))

[0130] The image forming apparatus according to any one of (((2))) to (((7))), wherein

[0131] The angle of the retention unit in the second image generating unit relative to the plumb line direction of the sheet is made smaller than the angle of the retention unit in the first image generating unit relative to the plumb line direction of the sheet, and the amount of the waste colorant temporarily retained on the image retaining member is made substantially the same. (((9)))

[0133] The image forming apparatus according to any one of (((1))) to (((8))), wherein

[0134] The image holding member is uniformly charged by contact charging.

[0135] According to (((1))), when collecting waste toner removed from a plurality of image holding members, it is possible to suppress variation in the amount of waste toner temporarily retained on each image holding member.

[0136] According to (((2))), the contact between the cleaning element and the image holding element can be stabilized.

[0137] According to (((3))), it is possible to prevent the amount of waste toner temporarily retained in the second image generating unit from increasing.

[0138] According to (((4))), it is possible to prevent the amount of waste toner temporarily stagnating in the second image generating unit from increasing.

[0139] According to (((5))), it is possible to prevent the amount of waste toner temporarily retained in the second image generating unit from increasing.

[0140] According to (((6))), it is possible to prevent the amount of waste toner temporarily stagnating in the second image generating unit from increasing.

[0141] According to (((7))), it is possible to prevent the amount of waste toner temporarily retained in the second image generating unit from increasing.

[0142] According to (((8))), it is possible to prevent the amount of waste toner temporarily retained in the second image generating unit from increasing.

[0143] According to (((9))), the image generation unit can be miniaturized.

Claims

1. An image forming apparatus, characterized in that: have: a first image forming unit that forms a toner image on an image holding member using a colored toner that does not contain a metallic pigment and collects waste toner removed from the image holding member; a second image forming unit that forms a toner image on an image holding member using a special color toner having an average toner particle size at least 20% larger than that of the color toner, and collects waste toner removed from the image holding member; as well as The accumulation unit makes the amount of the waste toner temporarily accumulated on the image holding member substantially the same in the first image generating unit and the second image generating unit when collecting the waste toner removed from the image holding member.

2. The image forming apparatus according to claim 1, wherein The retention unit is formed by the image retaining body, a cleaning body that contacts the surface of the image retaining body and scrapes the waste toner, and a sheet body that is arranged opposite to the image retaining body and forms an opening for discharging the waste toner to form a space, so that the waste toner scraped by the cleaning body is temporarily retained in the space.

3. The image forming apparatus according to claim 2, wherein: The thickness of the sheet of the accumulation unit in the second image generating unit is made thinner than the thickness of the sheet of the accumulation unit in the first image generating unit, and the amount of the waste toner temporarily accumulated on the image holding member is made substantially the same.

4. The image forming apparatus according to claim 2 or 3, wherein: The slit width of the sheet of the accumulation unit in the second image generating unit is made wider than the slit width of the sheet of the accumulation unit in the first image generating unit, and the amount of the waste toner temporarily accumulated on the image holding member is made substantially the same.

5. The image forming apparatus according to any one of claims 2 to 4, wherein The opening of the accumulation unit in the second image generating unit is made larger than the opening of the accumulation unit in the first image generating unit, and the amount of the waste toner temporarily accumulated on the image holding member is made substantially the same.

6. The image forming apparatus according to any one of claims 2 to 5, wherein: The distance between the sheet of the retention unit in the second image generating unit and the image retaining member is made larger than the distance between the sheet of the retention unit in the first image generating unit and the image retaining member, and the amount of the waste colorant temporarily retained on the image retaining member is made substantially the same.

7. The image forming apparatus according to any one of claims 2 to 6, wherein: The Young's modulus of the sheet of the retention unit in the second image generating unit is made smaller than the Young's modulus of the sheet of the retention unit in the first image generating unit, and the amount of the waste toner temporarily retained on the image holding member is made substantially the same.

8. The image forming apparatus according to any one of claims 2 to 7, wherein: The angle of the retention unit in the second image generating unit relative to the plumb line direction of the sheet is made smaller than the angle of the retention unit in the first image generating unit relative to the plumb line direction of the sheet, and the amount of the waste colorant temporarily retained on the image retaining member is made substantially the same.

9. The image forming apparatus according to any one of claims 1 to 8, wherein The image holding member is uniformly charged by contact charging.

Images