Belt device, transfer device, image forming device

Abstract

To reduce a force applied to a transmission unit that transmits a driving force to a holding member.SOLUTION: A transfer device 20 comprises: an intermediate transfer belt 2 that travels in circle; a holding member 101 that holds down the intermediate transfer belt 2; and a transmission unit that transmits a driving force to the holding member 101. The holding member 101 is provided to be able to reciprocate between a holding attitude where it holds down the intermediate transfer belt 2 and a retreat attitude where it retreats from the intermediate transfer belt 2. The transmission unit transmits the driving force to the holding member 101, and thereby the holding member 101 is changed to the retreat attitude. The holding member 101 is changed by its own weight to a side of the holding attitude.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a belt device, a transfer device, and an image forming apparatus including the transfer device. [Background Art]

[0002] A belt member such as an intermediate transfer belt may warp toward the outer peripheral side under the influence of temperature rise at the widthwise end of the belt, indoor humidity and other factors.

[0003] In contrast, providing a pressing member that presses the belt member from the outer peripheral surface side can improve the warpage of the belt.

[0004] For example, the image forming apparatus disclosed in Patent Document 1 (Japanese Patent No. 6394151) is provided with a pressing member that presses the end portion of the belt member. The pressing member is mounted on a rotatable holding member. A contact / separation mechanism that brings each primary transfer roller into contact with and separates from the photoconductor rotates the holding member, thereby allowing the pressing member to be brought into contact with and separated from the belt member.

[0005] However, in the image forming apparatus of Patent Document 1, the mechanism for bringing each primary transfer roller into contact with and separated from the photoconductor is interlocked with the mechanism for bringing the belt presser into contact with and separated from the belt member. For this reason, operating the belt presser requires a large force to perform the contact / separation operation of the belt presser, for example, an operation of separating all primary transfer rollers from the photoconductor is required to operate the belt presser. As a result, each member of the transmission portion that transmits driving force to the belt presser is prone to damage, and corresponding strength is required for these members to prevent damage. For this reason, there have been problems such as restrictions on the design of each member of the transmission portion and increased cost. [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] An object of the present invention is to reduce the force applied to a transmission portion that transmits driving force to a pressing member. [Means for Solving the Problem]

[0007] To solve the above problems, the present invention provides a belt device comprising a belt member that travels in a circular motion, a pressing member that holds down the belt member, and a transmission unit that transmits driving force to the pressing member, wherein the pressing member is provided to be able to reciprocate between a pressing position that holds down the belt member and a retracted position that is retracted from the belt member, and the transmission unit transmits driving force to the pressing member so that the pressing member changes to the retracted position, and the pressing member changes its position toward the pressing position due to its own weight. The device comprises a first shaft that transmits driving force to the transmission unit by its own rotation, and a fixing member provided on the first shaft that applies force to the first shaft in the pressing position to fix the phase of the first shaft. It is characterized by the following: [Effects of the Invention]

[0008] According to the present invention, the force applied to the transmission part that transmits driving force to the retaining member can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of the image forming apparatus. [Figure 2] This is a perspective view of the transfer device. [Figure 3] This is a perspective view showing the configuration of the transmission section that transmits driving force to the retaining member, and depicts the retracted position. [Figure 4] This is a perspective view showing the configuration of the transmission section that transmits driving force to the pressing member, and depicts the state of the pressing position. [Figure 5] This is a perspective view showing the structure around the retaining member. [Figure 6] This diagram shows the configuration around the retaining member, specifically the retracted position. [Figure 7] This diagram shows the configuration around the retaining member and the state of the retaining position. [Figure 8] This is a front view of the unit in its retracted state with the release lever removed. [Figure 9] This is a front view of the device in the pressed-down position with the release lever removed. [Figure 10]It is a perspective view showing a lever fixing shaft and first to fourth link members. [Figure 11] It is an exploded perspective view of the first to fourth link members. [Figure 12] It is a front view in a retracted state showing the operation of the first to fifth link members. [Figure 13] It is a front view showing the operation of the first to fifth link members, which is a diagram in the middle of transition from the retracted state to the pressing state. [Figure 14] It is a front view in a pressing state showing the operation of the first to fifth link members. [Figure 15] It is a rear view showing the configuration around the most downstream primary transfer unit in the retracted state. [Figure 16] It is a rear view showing the configuration around the most downstream primary transfer unit in the pressing state. [Figure 17] It is a perspective view showing a second shaft and the peripheral configuration thereof. [Figure 18] It is a perspective view showing a state where each shaft portion constituting the second shaft is separated from FIG. 17. [Figure 19] It is a diagram showing a separated state of a central shaft portion and one end side shaft portion. [Figure 20] It is a diagram showing a separated state of the central shaft portion and the other end side shaft portion. [Figure 21] It is a diagram showing a first cam and a cam follower. [Figure 22] It is a schematic configuration diagram of a transfer device, where (a) is a diagram showing each primary transfer unit in an abutting state, and (b) is a diagram showing all primary transfer units in a separated state. [Figure 23] It is a perspective view showing a cam member. [Figure 24] It is a perspective view of the cam member and the peripheral configuration thereof as viewed from the rear side. [Figure 25] It is a diagram of the contact / separation configuration for the intermediate transfer belt of the most downstream primary transfer unit as viewed from the rear side of the image forming apparatus, showing the "separated" state. [Figure 26] It is a plan view showing the configuration around a first arm and a second arm. [Figure 27] It is a perspective view showing the second arm and the peripheral configuration thereof. [Figure 28] This is a perspective view of the second arm and its surrounding components, seen from the rear. [Figure 29] This is a plan view showing the contact and separation configuration of the detection sensor and sensor bracket. [Figure 30] This is a plan view showing the positioning of the second sensor bracket in the "separated" state. [Figure 31] This diagram shows the configuration around the release lever, and is a front view with the lever in the retracted position. [Figure 32] This diagram shows the configuration around the release lever, and is a front view of the lever in the pressed position. [Figure 33] This is a plan view showing the contact and separation configuration between the central primary transfer unit and the uppermost primary transfer section and the intermediate transfer belt. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be simplified or omitted as appropriate.

[0011] Figure 1 shows the configuration of an image forming apparatus 1 according to one embodiment of the present invention. The image forming apparatus 1 shown in Figure 1 is a color printer with a tandem configuration in which multiple photoreceptors as latent image carriers are arranged side by side. Each photoreceptor can form a toner image of a color corresponding to color separation using toner as a developer supplied from a developing device. After superimposing and transferring the toner images formed on each photoreceptor onto a transfer belt, the superimposed image is transferred all at once to a sheet such as recording paper, thereby forming a multicolor image on the sheet. In the present invention, the image forming apparatus is not limited to a color printer, but also includes color copiers, facsimile machines, and printing presses, of course.

[0012] In Figure 1, the image forming apparatus 1 has an image forming unit 1A positioned near the center in the vertical direction, a paper feeding unit 1B below it, and a document scanning unit 1C equipped with a document placement table 1C1 positioned above the image forming unit 1A. An intermediate transfer belt 2 is positioned in the image forming unit 1A. The intermediate transfer belt 2 has a horizontally stretched surface. Above the intermediate transfer belt 2, a configuration is provided for forming an image of a color separation color and a color complementary to that color.

[0013] One embodiment of the belt member of the present invention is a transfer belt for transferring images. The intermediate transfer belt 2 of this embodiment is an example of such a transfer belt. However, the examples of the belt member of the present invention are not limited to the intermediate transfer belt 2 as an intermediate transfer body. For example, the belt member of the present invention may be a transport belt that transports a recording medium and forms a transfer nip with a photoreceptor.

[0014] The image forming unit 1A is provided with multiple PCDU10 (Photo Conductor Development Units), which are latent image carrier units. Each PCDU10K, 10C, 10M, 10Y, and 10T can form images using complementary color toners (yellow, magenta, cyan, and black) and glossy images using transparent toner. Each PCDU10K, 10C, 10M, 10Y, and 10T has photoreceptors 3K, 3C, 3M, 3Y, and 3T (transparent toners) that can carry images and are arranged side by side along the tensioned surface of the intermediate transfer belt 2. In the following description, if the content is common to all photoreceptors, the photoreceptor will be indicated by reference numeral 3. Also, PCDU10K, 10C, 10M, 10Y, and 10T will also be referred to as PCDU10. Each PCDU10 comprises at least one photoreceptor 3 and, in this embodiment, includes a developing device and the like.

[0015] Each photoreceptor 3K, 3C, 3M, 3Y, and 3T consists of a drum that can rotate in the same direction (counterclockwise in Figure 1), and around it are a charging device, a writing device 5, a developing device 6, a primary transfer roller 7 as a primary transfer member, and a cleaning device that perform image formation processing during the rotation process (for convenience, the reference numeral T is added to the symbols of each device, with photoreceptor 3T as the target).

[0016] The transfer device 20, as a belt device, comprises an intermediate transfer belt 2, a plurality of primary transfer rollers 7 (for convenience, only the primary transfer roller 7T is indicated with a reference numeral), and a plurality of rollers 2A to 2C, which serve as transfer members.

[0017] The intermediate transfer belt 2 sequentially transfers toner images from the PCDU 10, each equipped with a photoreceptor 3. The intermediate transfer belt 2 is wrapped around multiple rollers 2A to 2C, and multiple rollers not indicated in Figure 1, allowing it to travel in a circular motion in the direction of the arrows in Figure 1. Rollers 2A and 2B tension the intermediate transfer belt 2 on both sides of the outer side in the direction of travel of the intermediate transfer belt 2, at opposing positions facing each photoreceptor 3 of the intermediate transfer belt 2. The secondary transfer opposing roller 2C faces the secondary transfer device 9 across the intermediate transfer belt 2.

[0018] The secondary transfer device 9 has a secondary transfer roller 9A. The secondary transfer roller 9A forms a secondary transfer nip between itself and the secondary transfer opposing roller 2C, with the intermediate transfer belt 2 in between. The secondary transfer opposing roller 2C is subjected to a secondary transfer bias of the same polarity as the toner, while the secondary transfer roller 9A is grounded. As a result, a secondary transfer field is formed in the secondary transfer nip that electrostatically moves the multicolor toner image on the intermediate transfer belt 2 from the belt side towards the secondary transfer roller 9A side. This secondary transfer nip transfers the multicolor toner image to the sheet that has been transported to the secondary transfer nip.

[0019] Paper, to be used as a recording medium, is fed from the paper feeding unit 1B to the secondary transfer position. The paper feeding unit 1B comprises multiple paper feed cassettes 1B1 and multiple transport rollers 1B2. The multiple transport rollers 1B2 are arranged in the transport path for the paper fed from the paper feed cassettes 1B1.

[0020] The writing device 5 irradiates the photoreceptors 3K, 3C, 3M, 3Y, and 3T with writing light, forming an electrostatic latent image on the photoreceptors 3K, 3C, 3M, 3Y, and 3T corresponding to the image information. This image information is obtained by scanning the original document on the original document tray 1C1 of the original document scanning unit 1C, or from image information output from a computer.

[0021] The document scanning unit 1C is equipped with a scanner 1C2 and an automatic document feeder 1C3. The scanner 1C2 exposes and scans the document on the document tray 1C1. The automatic document feeder 1C3 is positioned on the upper surface of the document tray 1C1. The automatic document feeder 1C3 is configured to be able to flip the document as it is fed onto the document tray 1C1, allowing scanning of both the front and back sides of the document.

[0022] The electrostatic latent image formed on the photoreceptor 3 by the writing device 5 is processed into a visible image by the developing device 6 (indicated by the symbol 6T in Figure 1 for convenience) and primary transferred to the intermediate transfer belt 2. Once the toner images of each color are superimposed and transferred onto the intermediate transfer belt 2, they are collectively secondary transferred to the paper by the secondary transfer device 9.

[0023] The paper that has been secondarily transferred has the unfixed image on its surface fixed by the fixing device 11. The fixing device 11 has a belt fixing structure that includes a fixing belt heated by a heating roller and a pressure roller that is in contact with the fixing belt. By providing a contact area between the fixing belt and the pressure roller, i.e., a nip area, the heating area on the paper can be expanded compared to a hot roller fixing method.

[0024] The paper that has passed through the fuser 11 has its transport direction switched by a transport path switching claw located behind the fuser 11. Specifically, the transport path switching claw selects the transport direction to either the transport path toward the paper discharge section 13 or the reverse transport path RP.

[0025] In the image forming apparatus 1 having the above configuration, an electrostatic latent image is formed on a uniformly charged photoreceptor 3 by exposure scanning of a document placed on the document placement table 1C1, or by image information from a computer. After the electrostatic latent image is processed into a visible image by the developing device 6, the toner image is first transferred to the intermediate transfer belt 2. The above-mentioned PCDU 10, writing device 5, transfer device 20, secondary transfer device 9, fixing device 11, etc. constitute the image forming unit that forms the image.

[0026] The toner image transferred to the intermediate transfer belt 2 is transferred directly to the paper fed from the paper feed unit 1B in the case of a single-color image, and in the case of a multi-color image, the primary transfer is repeated to superimpose the images before being transferred to the paper all at once in a secondary transfer. After the secondary transfer, the unfixed image on the paper is fixed by the fuser unit 11, and then fed to the paper discharge unit 13 or inverted and fed again towards the secondary transfer position.

[0027] In Figure 1, the intermediate transfer belt 2 is constructed by forming a single or multiple layer of PVDF (vinyldenine fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), etc., with conductive materials such as carbon black dispersed within it. The volume resistivity of the intermediate transfer belt 2 is set to 10 8 ~10 12 Ωcm, and surface resistivity of 10 9 ~10 13The resistance is adjusted to be within the range of Ωcm. A release layer may be coated onto the surface of the intermediate transfer belt 2 as needed. Suitable coating materials include, but are not limited to, fluororesins such as ETFE (ethylene-tetrafluoroethylene copolymer), PTFE (polytetrafluoroethylene), PVDF (vinyldenide fluoride), PEA (perfluoroalkoxy fluororesin), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), and PVF (vinyl fluoride). The intermediate transfer belt 2 can be manufactured by casting, centrifugal molding, etc., and its surface may be polished as needed. If the volume resistivity of the intermediate transfer belt 2 exceeds the above-mentioned range, the bias required for transfer becomes higher, leading to increased power costs, which is undesirable. Furthermore, the charge potential of the intermediate transfer belt 2 increases during the transfer process and transfer paper peeling process, and self-discharge becomes difficult, necessitating the provision of static elimination means. Furthermore, if the volume resistivity and surface resistivity fall below the above range, the charge potential decays more quickly, which is advantageous for static discharge, but the current during transfer flows in the surface direction, causing toner to splatter. Therefore, it is preferable that the volume resistivity and surface resistivity of the intermediate transfer belt 2 in this embodiment are within the above range. The volume resistivity and surface resistivity were measured by connecting an HRS probe (inner electrode diameter 5.9 mm, ring electrode inner diameter 11 mm) to a high-resistivity resistivity meter (Mitsubishi Chemical Corporation: High Resista IP), applying a voltage of 100 V (500 V for surface resistivity) to both sides of the intermediate transfer belt 2, and using the measured values ​​after 10 seconds.

[0028] The intermediate transfer belt 2 is wrapped around at least one pair of rollers, rollers 2A and 2B, and a secondary transfer opposing roller 2C located at the secondary transfer position. By setting the drive roller 2A to rotate clockwise, the intermediate transfer belt 2 can move in the direction of the arrow shown inside the intermediate transfer belt 2 in Figure 1. The transfer surface of the belt moving between rollers 2A and 2B faces the photoreceptors 3K, 3Y, 3C, 3M, and 3T of each imaging unit. At positions facing each photoreceptor across the intermediate transfer belt 2, primary transfer rollers 7 (indicated by the symbol 7T in Figure 1, referring to special toner) are positioned, which correspond to transfer members for electrostatically transferring the visible image on the photoreceptor.

[0029] The primary transfer roller 7 used in this embodiment is made by coating a foaming resin agent onto a metal core (iron, stainless steel, aluminum alloy, etc.). The thickness of the foaming resin agent is 2 mm to 10 mm. Known blade-shaped or brush-shaped transfer members can also be used.

[0030] In this embodiment, in addition to the toner used for full-color image formation, white toner is used to form a white background on the image. Alternatively, transparent toner may be used to improve the gloss and transferability of the image, and light cyan toner, light magenta toner, etc., may be selected to increase the color gamut. In some cases, metallic toners such as gold toner or silver toner may be used as a background to create colored metallic colors such as reddish-bronze or bronze.

[0031] Incidentally, in belt members that travel in a circular motion, such as the intermediate transfer belt 2, the widthwise end of the belt tends to curve outward due to the effects of temperature rise and humidity, as well as the stretching of the tensioned belt. In response to this, this embodiment provides a retaining member that presses down on the widthwise end of the intermediate transfer belt 2 from the outer side. The retaining member and the mechanism for changing the orientation of the retaining member will be described below.

[0032] As shown in Figure 2, the inner cover 20A, which is part of the transfer frame, is provided with a release lever 71 as an operating member. The release lever 71 has a lever portion 71a as an operating part. The transfer device 20 also has a plurality of pressing members 101. The pressing members 101 can press the outer surface of the intermediate transfer belt 2 at the widthwise end side. In this embodiment, pressing members 101A to 101D are arranged at two locations in the running direction on both sides of the widthwise direction of the intermediate transfer belt 2.

[0033] Such a configuration with a pressing member 101 is particularly suitable for belt members having an elastic layer and multiple layers made of different materials. Because the expansion rates with respect to temperature and humidity differ for each layer, such belt members are prone to warping at the widthwise end, and the above-mentioned pressing member can effectively correct the warping of the belt member. The intermediate transfer belt 2 of this embodiment has multiple layers, with an elastic layer on the photoreceptor side and a base layer on the primary transfer roller side.

[0034] The pressing member 101 can reciprocate between a pressing position in contact with the surface of the intermediate transfer belt 2 and pressing down on the belt end, and a retracted position in which it is moved away from the intermediate transfer belt 2. For example, during image formation, the pressing member 101 assumes the retracted position, and during maintenance, the pressing member 101 assumes the pressing position to correct the curvature of the end of the intermediate transfer belt 2.

[0035] The operator can change the orientation of the intermediate transfer belt 2 by rotating the lever portion 71a. Specifically, when the lever portion 71a is in the position shown in Figure 3, the retaining member 101 is in the retracted position, and when the lever portion 71a is rotated to the position shown in Figure 4, the retaining member 101 is in the pressed position. Hereinafter, the position of the lever portion 71a in Figure 3 will also be referred to as the retracted position where the retaining member 101 is in the retracted position, and the position of the lever portion 71a in Figure 4 will be referred to as the pressed position where the retaining member 101 is in the pressed position. The state in which the retaining member 101 is positioned in the retracted position will also be referred to as the retracted state, and the state in which it is positioned in the pressed position will also be referred to as the pressed state.

[0036] The operating force of the lever portion 71a is transmitted to the fourth link member 76 shown in Figure 3 via the first link member, the second link member, and the third link member.

[0037] One end of the fourth link member 76 is connected to the other end of the fifth link member 77. One end of the second shaft 102 is inserted into the fifth link member 77, and it rotates around the second shaft 102. The operating force of the lever portion 71a is transmitted to the fifth link member 77 via the fourth link member 76, causing the fifth link member 77 to rotate around the second shaft 102. In other words, the second shaft 102 rotates due to the operating force of the lever portion 71a. First cams 82 are provided on both sides of the second shaft 102 in the axial direction.

[0038] As shown in Figure 5, the first cam 82, which is provided on the second shaft 102, contacts the cam follower 83. The slide mechanism 105 is linked to the cam follower 83. The slide mechanism 105 has a pin 105a that is inserted into the hole 101d of the retaining member 101.

[0039] The retaining member 101 has a retaining portion 101a and a holding portion 101b. The holding portion 101b holds the retaining portion 101a. The holding portion 101b is molded from a resin material. The retaining portion 101a has a support portion 101a1 and a felt member 101a2 as a contact portion. The support portion 101a1 supports the felt member 101a2. The felt member 101a2 is the part that contacts the surface of the intermediate transfer belt 2. By bringing the felt member 101a2 into contact with the intermediate transfer belt 2, damage to the surface of the intermediate transfer belt 2 can be prevented. Also, since the support portion 101a1 is not a part that slides against the intermediate transfer belt 2, it is molded from a resin material with an emphasis on strength.

[0040] Next, the change in the position of the retaining member 101 due to the rotation of the first cam 82 will be explained using Figures 6 and 7. Figure 6 shows the retaining member 101 in the retracted position, and Figure 7 shows it in the pressed position.

[0041] As shown in Figure 6, the retaining member 101 rotates around the pivot point 101e provided on the holding portion 101b. This rotation causes the retaining member 101 to reciprocate between a retracted position and a pressed position. In the retracted position shown in Figure 6, the pin 105a of the slide mechanism 105 is positioned on the right end side of the hole 101d of the retaining member 101 in Figure 6. This restricts the counterclockwise rotation of the retaining member 101 around the pivot point 101e, and the retaining member 101 is positioned in the retracted position.

[0042] As shown in Figure 6 → Figure 7, the rotation of the first cam 82 presses the cam follower 83 to the left in Figure 6, causing the cam follower 83 and the linked slide mechanism 105 to move to the left in Figure 6. This causes the pin 105a to move to the left in Figure 6 within the hole 101d. This releases the force that the pin 105a exerts on the retaining member 101 to restrict its counterclockwise rotation, and the retaining member 101 rotates counterclockwise in Figure 6 due to its own weight. As a result, as shown in Figure 7, the retaining member 101 changes from a retracted position to a pressed position and comes into contact with the intermediate transfer belt 2.

[0043] Conversely, as shown in Figure 7 → Figure 6, the rotation of the first cam 82 causes the slide mechanism 105 to move to the right in Figure 7, pushed by the first cam 82. This causes the pin 105a to press against the retaining member 101 (transmitting driving force to the retaining member 101), causing the retaining member 101 to rotate clockwise. This returns the retaining member 101 to its retracted position. The retaining member 101 maintains its retracted position due to its own weight and the restriction imposed by the pin 105a.

[0044] Next, the first to third link members, which are provided between the lever portion 71a and the fourth link member 76 shown in Figure 3 and transmit the operating force of the lever portion 71a to the fourth link member 76, will be explained using Figures 8 and 9. Figures 8 and 9 show the inner cover and operating lever removed, with Figure 8 showing the retaining member 101 in the retracted position and Figure 9 showing it in the pressed position.

[0045] Figure 8 shows the lever fixing shaft 71b, which is the rotation axis of the lever portion 71a shown in Figure 3. The first link member 73 is attached to the transfer frame via the lever fixing shaft 71b. The lever fixing shaft 71b is a rotation axis that rotates due to the operating force applied by the operator to the lever portion 71a. The first link member 73 rotates around the lever fixing shaft 71b. The lever fixing shaft 71b is one embodiment of the first shaft of the present invention.

[0046] The first link member 73 is connected to the second link member and the third link member, which will be described later, at the connecting portion 73a. One end of a spring 78 is attached to the mounting portion 73b of the first link member 73. The other end of the spring 78 is fixed to the transfer frame.

[0047] Due to the tensile force of the spring 78, the first link member 73 is subjected to a rotational force that causes it to rotate clockwise around the lever fixing shaft 71b in the direction shown in Figure 8. This tensile force causes the lever portion 71a to be positioned in the retracted position shown in Figure 3. On the other hand, when the operator rotates the lever portion 71a of the release lever 71 in the direction from Figure 3 to Figure 4, the first link member 73 rotates counterclockwise against the tensile force of the spring 78 and is positioned in the position shown in Figure 9. Thus, the spring 78 is a biasing member that biases the first link member 73 in the direction of the rotational phase in the retracted position.

[0048] The rotational force of the first link member 73 is transmitted to the fifth link member 77 via the second, third, and fourth link members 76, which will be described later. As a result, as shown in Figure 8 → Figure 9, the fourth link member 76 moves to the left in Figure 9, and the fifth link member 77 rotates clockwise around the second axis 102 in Figure 9. This causes the retaining member 101 to change its position as described above. In addition, regulating members 72C and 72 are attached to the fourth link member 76, and their position changes in conjunction with the fourth link member 76.

[0049] Next, the second link member, the third link member, and the first link member 73 and fourth link member 76 connected to them will be described using Figures 10 and 11. Figure 10 is a perspective view of Figure 9 with the restricting member 72T removed, and Figure 11 is an exploded perspective view of each link member.

[0050] As shown in Figures 10 and 11, the connecting portion 73a of the first link member 73 is inserted into holes provided at one end 74a of the second link member 74 and one end 75a of the third link member 75, respectively. This connects the first link member 73 to the second link member 74 and the third link member 75. An E-ring is interposed between one end 74a of the second link member 74 and one end 75a of the third link member 75 to reduce the contact area between the two ends.

[0051] The other end of the second link member 74, the insertion portion 74b, is inserted into the hole 76a of the fourth link member 76, connecting the second link member 74 to the fourth link member 76. The other end of the third link member 75, the insertion portion 75b, is inserted into the elongated hole 76b of the fourth link member 76, and the insertion portion 75b is provided to be movable relative to the elongated hole 76b. The first link member 73 has an insertion hole 73c into which the lever fixing shaft 71b is inserted. As shown in Figure 10, E-rings are also interposed between the first link member 73 and the lever fixing shaft 71b, between the connecting portion 73a and the third link member 75, between the insertion portion 75b and the fourth link member 76, and between the insertion portion 74b and the fourth link member 76.

[0052] Next, the rotation of the first link member 73 around the lever fixing shaft 71b transmits rotational force to the fourth link member 76 via the second link member 74 and the third link member 75, causing the fourth link member 76 to move in the left-right direction as shown in Figure 8. This will be explained using Figures 12 to 14. Figure 12 shows the retracted state, Figure 13 shows the transition from the retracted state to the pressed state, and Figure 14 shows the pressed state. For convenience, the E-ring interposed between the insertion part 75b and the fourth link member 76 is omitted from Figures 13 and 14.

[0053] In Figures 12 to 14, the lever fixing shaft 71b and the second shaft 102 are fixed to the transfer frame and their positions do not change.

[0054] As shown in Figures 12 and 13, when the first link member 73 rotates counterclockwise around the lever fixing shaft 71b, the second link member 74 and the third link member 75, which are connected to the first link member 73 at the connecting portion 73a, change their positions in conjunction with the first link member 73. As the second link member 74 and the third link member 75 move, the fourth link member 76, which is connected to the second link member 74 at the insertion portion 74b, moves in the left-right direction in Figure 12, and the fifth link member 77 rotates around the second shaft 102.

[0055] The insertion portion 75b of the third link member 75 is inserted into the elongated hole 76b of the fourth link member 76, thereby determining the position to which the fourth link member 76 moves. In other words, the lever fixing shaft 71b and the second shaft 102 are fixed to the transfer frame, and the positions of the second link member 74 and the fourth link member 76, which are positioned between these two points, are variable. Therefore, simply connecting the second link member 74 and the fourth link member 76 would not allow the position of the fourth link member 76 to be fixed in response to the position change caused by the rotation of the first link member 73. However, by restricting the range of movement of the insertion portion 75b, which is the other end of the third link member 75, to the elongated hole 76b of the fourth link member 76, the relative position between the third link member 75 and the fourth link member 76 is restricted. This allows the positions of the first link member 73 and the fourth link member 76 to correspond one-to-one, and the fourth link member 76 can be moved to a predetermined position in response to the rotation of the first link member 73. In the retracted position shown in Figure 12, the insertion portion 75b of the third link member 75 is positioned at one end of the elongated hole 76b of the fourth link member 76, restricting the fourth link member 76 from moving further to the left in Figure 12. In the held position shown in Figure 14, the insertion portion 75b is positioned at the other end of the elongated hole 76b, restricting the fourth link member 76 from moving further to the right in Figure 14.

[0056] The first link member 73 rotates counterclockwise as shown in Figure 12 and moves to the pressed position shown in Figure 14 by the operating force applied by the operator to rotate the lever portion 71a (see Figure 2) of the release lever 71. On the other hand, since a clockwise force is applied to the first link member 73 by the spring 78, if the operating force is released from a position other than the pressed position, it automatically returns to the retracted position shown in Figure 12.

[0057] On the other hand, in the pressed state shown in Figure 14, the first link member 73 is fixed in that position. Therefore, even if the operator releases the operating force on the lever portion 71a in the pressed state, the lever portion 71a and the first link member 73 do not return to the retracted position. The fixing mechanism that fixes the lever portion 71a and the first link member 73 in the pressed position will be explained using Figures 15 and 16. Figures 15 and 16 are views of the transfer device from the rear side of the image forming apparatus, with Figure 15 showing the retracted state and Figure 16 showing the pressed state.

[0058] As shown in Figure 15, one end of a spring 79 is connected to a front slider 32, which is a mechanism for moving the primary transfer roller 7T toward and away from it. The other end of the spring 79 is fixed to the transfer frame and biases the front slider 32 to the left in Figure 15. A cam follower 81 is attached to the front slider 32.

[0059] A cam 80 is attached as a fixing member to the lever fixing shaft 71b, which is the rotation axis of the release lever. In the retracted state shown in Figure 15, the cam 80 is not in contact with the cam follower 81. On the other hand, in the pressed state shown in Figure 16, the cam 80 rotates when the release lever is operated, causing the cam 80 to come into contact with the cam follower 81. The cam follower 81 provided on the front slider 32 is biased to the left in Figure 16. When the cam follower 81 comes into contact with the cam 80, the position of the cam 80, that is, the rotational phase of the lever fixing shaft 71b, is fixed. As a result, the lever portion 71a of the release lever 71 is fixed in the pressed position.

[0060] As described above, by configuring the lever portion 71a to automatically return to the retracted position when not in the pressing position, it is possible to prevent the lever portion 71a from being positioned in an intermediate position between the pressing position and the retracted position. Therefore, the pressing member 101 (see Figure 6) can be positioned in either the pressing position or the retracted position.

[0061] To summarize the above operations, first, the retaining member 101 is positioned in the retracted position shown in Figure 6 by the rotation of the first cam 82 to a predetermined phase due to the tensile force of the spring 78 shown in Figure 12. In other words, the tensile force of the spring 78 is transmitted in the following order: spring 78 (see Figure 12) → first link member 73 → second link member 74 (third link member 75) → fourth link member 76 → fifth link member 77 → second shaft 102 → first cam 82 (see Figure 6). Then, the rotation of the first cam 82 moves the cam follower 83 and the slide mechanism 105. The pin 105a of the slide mechanism 105 moves to the right in Figure 7 within the hole 101d, and the retaining member 101 rotates clockwise to be positioned in the retracted position. The second link member 74, the third link member 75, the fourth link member 76, and the fifth link member 77 are other link members that transmit driving force between the first link member 73 and the first cam 82 and the second shaft 102.

[0062] On the other hand, when the operator rotates the lever portion 71a as shown in Figure 3 → Figure 4, the first link member 73 rotates, and a force acts on the slide mechanism 105 in the same order as above. As a result, the pin 105a of the slide mechanism 105 moves to the left in Figure 6 within the hole portion 101d. This allows the retaining member 101 to rotate counterclockwise, and the retaining member 101 rotates counterclockwise due to its own weight as shown in Figure 6 → Figure 7, and the retaining member 101 is positioned in the retaining position.

[0063] In this embodiment, the retaining member 101 changes its position to the retaining position due to its own weight. Therefore, it is not necessary to apply force such as the spring force of a spring to move the retaining member 101 to the retaining position. Consequently, the force acting on each component constituting the transmission unit that transmits the driving force to the retaining member 101 can be reduced. Consequently, the force on each component constituting the transmission unit can be reduced, and damage to these components can be suppressed. Alternatively, the strength of these components can be relatively reduced by forming them from materials with low strength, thereby improving design flexibility and reducing costs. The transmission unit is the part that transmits the driving force to the retaining member 101 and changes it to the retracted position, and includes a first link member 73, a second link member 74, a third link member 75, a fourth link member 76, a fifth link member 77, a second shaft 102, a first cam 82, a cam follower 83, a slide mechanism 105, and the like.

[0064] Furthermore, when the lever portion 71a is positioned in the pressed position as shown in Figure 4, the tensile force of the spring 79 is transmitted to the cam 80 via the cam follower 81, as shown in Figure 16, and the rotational phase of the lever fixing shaft 71b is fixed. As a result, the slide mechanism 105 is held in the position shown in Figure 7, and the pressing member 101 maintains its pressing position by its own weight. In other words, the pressing member 101 can maintain its pressing position by its own weight simply by fixing the rotational phase of the lever fixing shaft 71b. Therefore, the force acting on each component constituting the transmission part can be reduced, similar to when the pressing member 101 changes from the retracted position to the pressing position.

[0065] As described above, in this embodiment, the forces acting on each component constituting the transmission unit can be reduced when changing from the retracted position to the pressing position and when maintaining the pressing position. For example, the first cam 82 is subjected only to the sliding load with the cam follower 83 due to rotation, the force due to the weight of the pressing member 101, and the reaction force due to the pressing member 101 pressing the intermediate transfer belt.

[0066] Next, the procedure for disassembling and removing the second shaft 102 will be explained using Figures 17 to 20. In the following explanation, of the first cams 82 provided on both axial sides of the second shaft 102, one side will be referred to as the first cam 82A, and the other side as the first cam 82B.

[0067] As shown in Figure 17, the central shaft portion 1021 constituting the second shaft 102 is screwed to the end shaft portions via first cams 82A and 82B on both sides of its axial direction. The second shaft 102 is constructed by connecting the central shaft portion 1021 with the end shaft portions 1022 (see Figure 19) and 1023 (see Figure 20) via the first cams 82A and 82B.

[0068] When disassembling the second shaft 102 and removing it from the transfer device, first remove screws 107 and 108. Removing screw 107 separates the first cam 82A from the central shaft portion 1021. Removing screw 108 separates the first cam 82B from the end shaft portion 1022. Then, move the first cam 82B in the direction of arrow C to reach the state shown in Figure 18. This makes the central shaft portion 1021 removable. In other words, as shown in Figure 19, moving the first cam 82B in the direction of arrow C separates the central shaft portion 1021 from the end shaft portion 1022, which were connected via the first cam 82B in Figure 17. Also, as shown in Figure 20, on the other axial side, the other axial end of the central shaft portion 1021 is inserted into the cylindrical portion 821 of the first cam 82A. In the state shown in Figure 17, the central shaft portion 1021 and the other end shaft portion 1023 are connected via the first cam 82A by a screw 107. Therefore, by removing the screw 107, the central shaft portion 1021 and the other end shaft portion 1023 are separated. From the state shown in Figure 18, the central shaft portion 1021 can be removed by pushing the central shaft portion 1021 and the first cam 82B in an oblique direction to pull the central shaft portion 1021 out of the cylindrical part of the first cam 82A.

[0069] As described above, in this embodiment, the force applied to the second shaft 102 and the first cams 82A and 82B is small when maintaining the pressing position, so the central shaft portion 1021 and the end shaft portions 1022 and 1023 can be attached in a simple screw-fastening configuration. Accordingly, the second shaft 102 and the central shaft portion 1021 can be easily disassembled and removed, as described above. This makes it easier to replace and maintain parts inside the image forming apparatus that are located further back than the second shaft 102.

[0070] Furthermore, as shown in Figure 20, the first cam 82 has a cylindrical portion 821 and a cam portion 822 for inserting the second shaft 102. In other words, the first cam 82 also serves as a connecting portion for linking the cam portion 822, which transmits the driving force, with the multiple shaft portions 1021, 1022, and 1023 that make up the second shaft 102. This reduces the number of parts.

[0071] Next, a mechanism that limits the rotation range of the release lever 71 to the range from the retracted position in Figure 3 to the pressed position in Figure 4 will be explained using Figure 21.

[0072] The rotation range of the release lever 71 is limited by restricting the rotation range of the fifth link member 77 shown in Figure 12, and by restricting the movement range of the insertion portion 76c to within the elongated hole 75b. The rotation range of the fifth link member 77 is restricted by restricting the rotation range of the first cam 82, which is coaxial with the fifth link member 77. In other words, the rotation range of the first cam 82 is restricted to the range from the retracted position shown in Figure 6 to the pressed position shown in Figure 7.

[0073] As shown in Figure 21, the cam follower 83 has a first contact surface 83a as a first contacted portion and a second contact surface 83b as a second contacted portion that abuts against the first cam 82. The first cam 82 also has a first contact portion 82a that abuts against the first contact surface 83a and a second contact portion 82b that abuts against the second contact surface 83b. In Figure 6, the position of the cam follower 83 is restricted by the first contact portion 82a abutting against the second contact surface 83b, and in Figure 7, the position of the cam follower 83 is restricted by the first contact portion 82a abutting against the first contact surface 83a.

[0074] In this way, by arranging the contact surfaces of the cam follower 83 on both sides of the first cam 82, the first cam 82 can contact the cam follower 83 and move the slide mechanism 105 regardless of the direction in which the first cam 82 rotates. Therefore, it is no longer necessary to keep the first cam 82 in constant contact with the cam follower 83 for sliding, and the need for springs or the like is eliminated.

[0075] The distance B2 between the first contact surface 83a and the second contact surface 83b is set to be smaller than the distance B1 between the first contact portion 82a and the second contact portion 82a. This allows the rotation range of the first cam 82 to be restricted as described above. The distance B1 between the first contact portion 82a and the second contact portion 82a is the maximum distance between the first contact portion 82a and the second contact portion 82a that passes through the center of the second shaft 102 on a plane perpendicular to the second shaft 102.

[0076] In this embodiment, the primary transfer roller provided in the transfer device is configured to move in a direction away from the photoreceptor. The primary transfer roller can be moved away from the photoreceptor in conjunction with the operation of the lever portion 71a, which changes the position of the pressing member. The mechanism for moving the primary transfer roller away from the photoreceptor will now be described.

[0077] As shown in Figure 22(a), the primary transfer roller 7T forms a special color transfer nip NT between itself and the photoreceptor 3T via the intermediate transfer belt 2. The primary transfer roller 7C forms a cyan transfer nip NC between itself and the photoreceptor 3C via the intermediate transfer belt 2. The primary transfer roller 7M forms a magenta transfer nip NM between itself and the photoreceptor 3M via the intermediate transfer belt 2. The primary transfer roller 7Y forms a yellow transfer nip NY between itself and the photoreceptor 3Y via the intermediate transfer belt 2. The primary transfer roller 7K forms a black transfer nip NK between itself and the photoreceptor 3K via the intermediate transfer belt 2.

[0078] The transfer device 20 includes an upstream primary transfer section 201 located on the upstream side in the direction of travel of the intermediate transfer belt 2, a downstream primary transfer section 203 located on the downstream side, and a central primary transfer unit 202 consisting of a plurality of primary transfer sections located between the upstream primary transfer section 201 and the downstream primary transfer section 203. In this embodiment, the upstream primary transfer section 201 transfers a black toner image using a black transfer nip NK, the central primary transfer unit 202 transfers cyan toner images, magenta toner images, and yellow toner images using cyan transfer nip NC, magenta transfer nip NM, and yellow transfer nip NY, and the downstream primary transfer section 203 transfers a special color toner image using a special color transfer nip NT, all to the intermediate transfer belt 2. In the following description, the upstream or downstream side in the direction of travel of the intermediate transfer belt 2 will also be simply referred to as the upstream side or the downstream side.

[0079] In the direction of travel of the intermediate transfer belt 2, a driven roller 21A acting as a tensioning member and a detection sensor 22 acting as a detection mechanism are provided between the primary transfer roller 7C and the primary transfer roller 7T. The driven roller 21A tensions the intermediate transfer belt 2. The detection sensor 22 detects the scale on the intermediate transfer belt 2 and detects the travel speed of the intermediate transfer belt 2. By controlling the speed of the intermediate transfer belt 2 based on this detection result, misalignment of the toner images of each color transferred to the intermediate transfer belt 2 can be suppressed.

[0080] In Figure 22(a), the primary transfer roller 7K located in the uppermost primary transfer section 201 is the uppermost primary transfer member, the primary transfer rollers 7Y, 7M, and 7C located in the central primary transfer unit 202 are the central primary transfer members, and the primary transfer roller 7T located in the lowermost primary transfer section 203 is the lowermost primary transfer member. The direction of travel of the intermediate transfer belt 2 is indicated by arrow A in Figure 22(a). Furthermore, the primary transfer rollers 7K, 7Y, 7M, and 7C located upstream of the primary transfer roller 7T are also upstream primary transfer members.

[0081] In this embodiment, the special color can be transferred in either the upstream primary transfer unit 201 or the downstream primary transfer unit 203. This makes it possible to transfer the special color toner in the required order.

[0082] In the direction of travel of the intermediate transfer belt 2, a driven roller 21A acting as a second tensioning roller and a detection sensor 22 acting as a detection mechanism are provided between the primary transfer roller 7C and the primary transfer roller 7T. The driven roller 21A tensions the intermediate transfer belt 2. The detection sensor 22 detects the scale on the intermediate transfer belt 2 and detects the travel speed of the intermediate transfer belt 2. By controlling the speed of the intermediate transfer belt 2 based on this detection result, misalignment of the toner images of each color transferred to the intermediate transfer belt 2 can be suppressed.

[0083] In the transfer apparatus 20 of this embodiment, each primary transfer roller 7 contacts or separates from the photoreceptor 3 via the intermediate transfer belt 2, according to the mode during image formation. For example, as shown in Figure 22(b), all primary transfer rollers 7T can be separated from the photoreceptor 3T. Figure 22(b) is an example, and the contact and separation states of each primary transfer roller 7 in the uppermost primary transfer section 201, the central primary transfer unit 202, and the lowermost primary transfer section 203 can be switched.

[0084] In conjunction with the contact and separation movement of the downstream primary transfer roller 7T with respect to the photoreceptor 3T, the driven rollers 21A and 33A, which act as tensioning members for tensioning the intermediate transfer belt 2, and the detection sensor 22 also move in the direction of contact and separation from the photoreceptor 3, which is the vertical direction in Figure 22. The first contact and separation mechanism for moving these members will be explained below using Figures 15 and 23 to 30. Figure 15 is a diagram of the retracted state described above, but it is also a diagram of the primary transfer roller 7T in the "contact" state. In the following explanation, we show the case where a special color toner image is transferred in the downstream primary transfer section 203, but a black toner image may also be transferred.

[0085] As shown in Figure 15, the primary transfer roller 7T is provided at one end of the rotating member 34. The rotating member 34 is rotatable around a pivot point 34a. The rotating member 34 has a hole 34b at the end opposite to the side on which the primary transfer roller 7T is provided. A pin 32b provided on the front slider 32 is inserted into the hole 34b. The spring 35 is fixed to the housing of the image forming apparatus and biases the rotating member 34 to rotate clockwise around the pivot point 34a in Figure 15. Due to the biasing force of this spring 35, the primary transfer roller 7T is in contact with the intermediate transfer belt 2. A driven roller 33A, which is one of the tensioning members that tensions the intermediate transfer belt 2, is provided at one end of the rotating member 33. The rotating member 33 is rotatable around a pivot point 33a. The rotating member 33 has a hole 33b at the end opposite to the side on which the driven roller 33A is provided. An insertion portion 32a, provided on the front slider 32, is inserted into the hole 33b. The insertion portion 32a is constructed by press-fitting a ball bearing into a shaft fixed to the front slider 32. Furthermore, a driven roller 21A is provided on one end of the rotating member 21. The rotating member 21 is rotatable around a pivot point 21a. The rotating member 21 is subjected to a force by the spring 39 that causes it to rotate clockwise around the pivot point 21a.

[0086] The first contact / disengagement mechanism 91 is provided with a cam member 31 that transmits the driving force of the motor. As shown in Figure 23, the cam member 31 has a cam 31A and a cam 31B, and is rotatably mounted around the rotation shaft 31a. The cam 31B is a ball bearing with an outer ring and is an eccentric cam with respect to the rotation shaft 31a.

[0087] The cam 31A has small diameter, medium diameter, and large diameter sections, each with a diameter of 120 degrees. As shown in Figure 24, the cam 31A contacts the cam follower 36, which is made of ball bearings. By rotating the cam 31A, the surface on which the cam 31A contacts the cam follower 36 is changed, allowing the front slider 32 to be moved in the left-right direction as shown in Figure 15.

[0088] Figure 25 shows the "separated" state in which the primary transfer roller 7T is separated from the photoreceptor. The rotation of the cam 31A moves the front slider 32 to the right of the position shown in Figure 15, creating a "separated" state. In other words, as the front slider 32 moves to the right from Figure 15 to Figure 25, the insertion part 32a, pin 32b, and pin 32c provided on the front slider 32 press against the rotating members 33, 34, and 21, respectively, causing the rotating members 33, 34, and 21 to rotate counterclockwise. As a result, the driven roller 33A, the primary transfer roller 7T, and the driven roller 21A move downward in Figure 25, away from the photoreceptor. The movement of the driven rollers 33A and 21A causes the tension position of the intermediate transfer belt 2 stretched over these rollers to move downward in Figure 25.

[0089] Furthermore, as shown from Figure 15 to Figure 25, the front slider 32 moves, causing the detection sensor 22 to move downwards in Figure 25. This allows the detection sensor 22 to be moved in accordance with the tension position of the intermediate transfer belt 2. The mechanism for moving this detection sensor 22 will be described below.

[0090] As shown in Figures 24 and 26, the first arm 37 grips the cam 31B at two points, gripping portions 37c1 and 37c2. The rotation of the cam 31B causes the first arm 37 to rotate around the pivot point 37a. As the front slider 32 moves from Figure 15 to Figure 25, the first arm 37 rotates clockwise around the pivot point 37a as shown in Figure 26.

[0091] As shown in Figure 24, a thrust stopper member 60, which acts as both a restricting member and a retaining member, is attached to the first arm 37. The thrust stopper member 60 restricts the relative direction of movement of the first arm 37 with respect to the cam 31B by restricting the position of the outer circumferential surface of the cam 31B with its restricting portion 60b. In other words, it can restrict the first arm 37 from moving in a direction other than along the outer circumferential surface of the cam 31B, for example, in the sliding direction relative to the cam 31B.

[0092] Figure 27 is a front perspective view of the area around the first arm 37 and the second arm 38. Figure 28 is a rear perspective view of the first arm 37 and the second arm 38.

[0093] As shown in Figure 27, the second arm 38, as a second link member, has other elongated holes 38a and 38b at both ends. One end 37b of the first arm 37 is inserted into the other elongated hole 38a. As shown in Figure 28, the one end 37b of the first arm 37 has a bearing 40. The bearing 40 is provided so as to be able to move relative to the other elongated hole 38a. The bearing 40 is the other insertion part into the other elongated hole 38a.

[0094] As shown in Figure 27, a bearing 41 is inserted into the elongated hole 38b. The bearing 41 is fixed to the first sensor bracket 43, which acts as a retaining member, by a stepped screw 42. The bearing 41 is provided to be movable within the elongated hole 38b. The bearing 41 is the insertion part for the elongated hole 38b.

[0095] The rotation of the cam member 31 moves the front slider 32 to the right of Figure 15 from the state shown in Figure 15, placing the downstream primary transfer section 203 in a "separated" state. This causes the cam 31B to rotate, and the first arm 37 rotates clockwise around the pivot point 37a. As a result, one end 37b of the first arm 37 moves downward in Figure 15. As a result, as shown in Figure 25, one end 37b moves to one end of the other elongated hole 38a and contacts the wall surface forming the other elongated hole 38a, pulling the second arm 38 downward in Figure 25. As a result, the bearing 41 moves relative to one end of the elongated hole 38b and contacts the wall surface forming the elongated hole 38b. Then, the second arm 38 pulls the first sensor bracket 43 downward in Figure 25.

[0096] Figure 29 shows the configuration around the first sensor bracket 43 and the detection sensor 22, and is a diagram showing the state with the rotating member 21 removed from Figure 15 and other figures. For convenience, the detection sensor 22 and the second sensor bracket 44 are shown in a simplified manner in Figure 29.

[0097] As shown in Figure 29, the first sensor bracket 43 is rotatably mounted around a pivot point 43a. The first sensor bracket 43 is subjected to a force by a spring 45 fixed to the housing of the image forming apparatus, which causes it to rotate counterclockwise around the pivot point 43a as shown in Figure 29. A regulating bracket 63 is also fixed to the first sensor bracket 43. The pin 32d of the front slider 32 is inserted into the hole 63a of the regulating bracket 63. In the "contact" state shown in Figure 15, the pin 32d contacts the wall surface forming the hole 63a, causing the front slider 32 to apply a force to the first sensor bracket 43 that causes it to rotate clockwise around the pivot point 43a as shown in Figure 29.

[0098] The second sensor bracket 44 is fixed to the first sensor bracket 43 via a stud 43b provided on the first sensor bracket 43. The second sensor bracket 44 holds the detection sensor 22. The second sensor bracket 44 has a hook 44a to which one end of a spring 62 (see Figure 15) is attached, a first contact portion 44b, and a second contact portion 44c.

[0099] In the "contact" state shown in Figure 15, the second sensor bracket 44 is biased by the spring 62 and moves in a direction that rotates clockwise around the pivot point 43a, and is positioned so that the first contact portion 44b contacts the stud 64 provided on the housing of the image forming apparatus.

[0100] Furthermore, in the "separated" state shown in Figure 25, as the pin 32d moves to the right, the force that the pin 32d exerts on the restricting bracket 63 to the left in Figure 29 is released, as shown in Figure 29. Simultaneously, as described above, the second arm 38 pulls the first sensor bracket 43 towards the lower left of Figure 29, causing the first sensor bracket 43 to rotate clockwise around the pivot point 43a in Figure 29. As a result, the second sensor bracket 44, which is fixed to the first sensor bracket 43 via the stud 43b, moves upward in Figure 29, and the detection sensor 22 also moves upward in Figure 29. At this time, as shown in Figure 30, the second sensor bracket 44 is positioned so that its second contact portion 44c contacts the positioning portion 21b of the rotating member 21. In other words, the upward movement of the second sensor bracket 44 and the detection sensor 22 in Figure 29 is restricted, and the detection sensor 22 is positioned.

[0101] As described above, in this embodiment, when the front slider 32 moves from Figure 15 to Figure 25, in the direction to the right in Figure 25, the primary transfer roller 7T, driven roller 21A, driven roller 33A, and detection sensor 22 each move in a direction away from the photoreceptor.

[0102] The above explanation showed the case where the front slider 32 moves due to the driving force of the motor, but the front slider 32 can also be moved to the right in Figure 25 by the operating force applied to the lever portion 71a. The movement of the front slider 32 by operating the lever portion 71a will be explained below.

[0103] As shown in Figures 3 and 4 above, moving the lever portion 71a from the retracted position to the pressed position causes the lever fixing shaft 71b, which is the pivot point of the lever portion 71a, to rotate as shown in Figures 15 and 16. During this process, the cam 80 comes into contact with the cam follower 81 attached to the front slider 32, and the cam follower 81 moves the front slider 32 to the right as shown in Figures 15 and 16. This allows the primary transfer roller 7T, driven roller 21A, driven roller 33A, and detection sensor 22 to move away from the photoreceptor, similar to when the cam member 31 is rotated by the motor and moved from the "contact" state to the "separated" state as shown in Figures 15 and 15.

[0104] In this embodiment, the tensioning member that tensions the primary transfer roller and intermediate transfer belt can be moved away from the photoreceptor in conjunction with the operation of changing the pressing position of the pressing member 101. This reduces the number of work steps required during maintenance.

[0105] The cam 80, which is the fixing member in this embodiment, only needs to contact the cam follower 81 in a predetermined region where it changes from the pressing position and the retracted position to the pressing position, and does not need to have a cam surface over its entire circumferential area. Furthermore, if the purpose is merely to hold the pressing member 101 in the pressing position, the fixing member only needs to contact the cam follower 81 at the phase of the pressing position and fix the lever fixing shaft 71b at the phase of the pressing position. In this case, the fixing member does not necessarily need to have a cam shape like in this embodiment; for example, it can be a projection extending in a specific direction in the circumferential direction of the lever fixing shaft 71b.

[0106] Incidentally, the PCDU 10 (see Figure 1) provided in the image forming apparatus 1 is detachably attached to the main body of the image forming apparatus 1. A restricting member that restricts the movement of the PCDU 10 in the removal direction is provided in the transfer apparatus 20. This restricting member will be described below.

[0107] As shown in Figure 31, the PCDU 10 is positioned above the transfer device 20. The PCDU 10 can be attached to and detached from the image forming apparatus body by moving it in the direction perpendicular to the plane of the paper in Figure 31.

[0108] The detection sensor 22, provided on the transfer device 20, is positioned to interfere with the PCDU 10 during the removal operation of the PCDU 10. Therefore, when attaching or detaching the PCDU 10, the detection sensor 22 is moved away from the PCDU 10. Thus, the detection sensor 22 is a contact / separation part provided on the transfer device 20 that moves toward and toward the PCDU 10. The direction of moving away from the PCDU 10 is the direction of arrow D1 in Figure 31, and the direction of moving toward the PCDU 10 is the direction of arrow D2 in Figure 31.

[0109] The transfer device 20 has a restricting member 72. The restricting member 72 in Figure 31 is positioned to interfere with the PCDU 10 during the removal operation of the PCDU 10. That is, it is positioned to overlap with the PCDU 10 on the plane of Figure 31, which is perpendicular to the removal direction of the PCDU 10. By interfering with the PCDU 10, the restricting member 72 restricts the movement of the PCDU 10 in the direction toward the front of the plane of Figure 31, which is the removal direction of the PCDU 10 from the image forming apparatus.

[0110] The restricting member 72 contacts the PCDU 10 at a position before the PCDU 10 contacts the detection sensor 22 in the removal direction, thereby restricting the removal of the PCDU 10. Although Figure 31 shows the case where the restricting member 72 is provided on PCDU 10T and 10C, the restricting member 72 can be provided at any position on the five PCDU 10s mentioned above.

[0111] By rotating the release lever 71 from Figure 31 to Figure 32, the detection sensor 22 can be moved away from the photoreceptor, as described above. This allows the detection sensor 22 to be positioned so as not to interfere with the PCDU 10 during the PCDU 10 removal operation, as shown in Figure 32. Similarly, by rotating the release lever 71 from Figure 31 to Figure 32, the restricting member 72 can be positioned so as not to interfere with the PCDU 10 during the PCDU 10 removal operation. Note that the position of the release lever 71 in Figure 31 is the position where the retaining member 101 shown in Figure 3 etc. is in the retracted position, and the position in Figure 32 is the position where the retaining member 101 is in the pressed position.

[0112] Next, we will explain how the restricting member 72 changes its position in conjunction with the operation of the release lever 71.

[0113] As described above, the operator can rotate the release lever 71 from the position shown in Figure 3 to the position shown in Figure 4. This allows the retaining member 101 to move from the retracted position to the retained position. Furthermore, the rotation of the release lever 71 from the retracted position shown in Figure 31 to the retained position shown in Figure 32 allows the regulating member 72 to rotate. As described above, the rotation of the release lever 71 causes the first link member 73 to rotate counterclockwise around the lever fixing axis 71b, as shown in Figures 8 and 9. This rotational force is transmitted to the fourth link member 76 via the second link member 74 and the third link member 75, causing the fourth link member 76 to move to the left in Figure 9.

[0114] The restricting members 72C and 72T are attached to the fourth link member 76 at one end. Therefore, the movement of the fourth link member 76 from Figure 8 to Figure 9 causes the restricting members 72C and 72T to change their orientation.

[0115] The restricting members 72C and 72T are provided with elongated holes 72a. Shafts 84 and 85, fixed to the transfer frame, are inserted into the elongated holes 72a, respectively. The orientation of the restricting members 72C and 72T is restricted to the extent that shaft 84 or shaft 85 can move relative to each other within the elongated holes 72a. Due to this restriction, the restricting members 72C and 72T reciprocate between the orientations shown in Figure 8 or Figure 9 as the fourth link member 76 moves. In other words, they reciprocate between a position that interferes with the PCDU 10 in Figure 31 and a position that does not interfere with the PCDU in Figure 32.

[0116] As described above, in this embodiment, the restriction on the movement of the PCDU in the removal direction by the restricting member 72 can be released by operating the release lever 71. In other words, in this embodiment, by operating the release lever 71, the restriction on the restricting member 72 can be released, the retaining member 101 (see Figure 3) can be moved from the retracted position to the retaining position, and the primary transfer roller 7 and detection sensor 22 (see Figure 22) can be moved away from the photoreceptor 3 simultaneously. In other words, by simultaneously releasing the restriction on the restricting member 72, moving the retaining member 101 to the retaining position, and moving the detection sensor 22 away from the photoreceptor 3, the PCDU 10 can be made removable from the main body of the image forming apparatus 1. Since these can be done by operating only the release lever 71, the operation of removing the PCDU 10 from the main body of the image forming apparatus 1 can be simplified. Furthermore, it is possible to prevent situations where the removal operation of the PCDU 10 is started while a specific member is not moved, such as by neglecting to release the restriction on the restricting member 72. However, these operations do not necessarily need to be linked.

[0117] The above explanation shows the case where the primary transfer roller 7T of the downstream primary transfer section moves away from the photoreceptor in conjunction with the pressing member 101, but any other primary transfer roller may move away from the photoreceptor.

[0118] Next, the second contact / separation mechanism 92, which acts as a second moving mechanism to bring the primary transfer rollers 7C, 7M, and 7Y provided in the central primary transfer unit 202 into contact with and separate from the intermediate transfer belt 2, and the third contact / separation mechanism 93, which acts as a third moving mechanism to bring the primary transfer roller 7K provided in the uppermost primary transfer section 201 into contact with and separate from the intermediate transfer belt 2, will be explained with reference to Figure 33.

[0119] As shown in Figure 33, the second contact / separation mechanism 92 includes rotating members 46-48, a cam 51, and a cam follower 52. The third contact / separation mechanism 93 includes a rotating member 49, a cam 53, and a cam follower 54. The second contact / separation mechanism 92 is equipped with a motor as a drive source for rotating the cam 51, and the third contact / separation mechanism 93 is equipped with a motor as a drive source for rotating the cam 53.

[0120] Rotating members 46, 47, 48, and 49 are rotatably mounted around pivot points 46a, 47a, 48a, and 49a. A primary transfer roller 7C is provided at one end of rotating member 46. A primary transfer roller 7M is provided at one end of rotating member 47. A primary transfer roller 7Y is provided at one end of rotating member 48. A primary transfer roller 7K is provided at one end of rotating member 49. Each of the rotating members 46 to 49 is biased by a spring to rotate in the clockwise direction shown in Figure 33, and each primary transfer roller 7 is brought into contact with the photoreceptor via the intermediate transfer belt 2.

[0121] The rotation of the cam 51 causes the cam follower 52 to rotate, moving the front slider 50 of the uppermost primary transfer section 201 to the right in Figure 33. This presses the ends of the rotating members 46-48 opposite to the side on which the primary transfer rollers 7 are installed, causing each rotating member 46-48 to rotate counterclockwise in Figure 33 against the biasing force of the spring. This causes each primary transfer roller 7C, 7M, and 7Y to move away from each photoreceptor. The rotation of the cam 53 also causes the cam follower 54 to rotate, pressing the end of the rotating member 49 opposite to the side on which the primary transfer roller 7K is installed. This causes the rotating member 49 to rotate counterclockwise in Figure 33 against the biasing force of the spring, causing the primary transfer roller 7K to move away from the photoreceptor. As described above, the primary transfer roller 7K of the uppermost primary transfer section 201 and the primary transfer rollers 7C, 7M, and 7Y of the central primary transfer unit 202 independently perform contact and separation operations with respect to each photoreceptor.

[0122] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

[0123] In the above description, the operating member is shown as being provided in the transfer device, but it may also be provided at an appropriate location within the image forming apparatus, such as in the housing of the image forming apparatus.

[0124] Recording media include plain paper (P), as well as cardboard, postcards, envelopes, thin paper, coated paper (such as coated paper and art paper), tracing paper, OHP sheets, plastic film, prepreg, copper foil, and the like.

[0125] Examples of the present invention are as follows: <1> A belt component that travels in a circular motion, A pressing member that holds down the belt member, A belt device comprising a transmission unit that transmits driving force to the aforementioned pressing member, The pressing member is provided to be able to reciprocate between a pressing position that holds the belt member and a retracted position that is retracted from the belt member. The transmission unit transmits driving force to the retaining member, thereby changing the retaining member to the retracted position. The aforementioned pressing member is a belt device characterized by changing its posture toward the pressing position due to its own weight. <2> A first shaft that transmits driving force to the transmission unit by its own rotation, The device comprises a fixing member provided on the first shaft, which applies force to the first shaft in the pressing position to fix the phase of the first shaft. <1> The belt device described above. <3> The aforementioned transmission unit is A first link member having the first axis as its axis of rotation, A first cam that transmits driving force to the retaining member through its own rotation, One or more other link members that transmit driving force between the first link member and the first cam, The system includes a biasing member that biases the first link member in the direction of the rotational phase of the first link member in the retracted position. <2> The belt device described above. <4> The device comprises an operating member fixed to the first shaft. <2> or <3> The belt device described above, This belt device allows the first shaft to be rotated by operating the aforementioned operating member. <5> The belt member is composed of multiple layers, each having at least an elastic layer and made of different materials. <1> from <4> The belt device is one of the following: <6> The second shaft is composed of multiple shaft portions, The plurality of shaft portions are connected via the first cam. <3> ,or, <3> related <4> ,or, <3> related <5> The belt device described above. <7> The aforementioned transmission unit The first cam is provided on a second shaft, which receives driving force from the other link member, The system includes a cam follower that swings due to the rotation of the first cam. <3> ,or, <3> related <4> ,or, <3> related <5> ,or, <6> The belt device described above, The cam follower has a first contact portion and a second contact portion that contact the first cam in the retracted position or the pressing position, The first cam is a belt device positioned between the first contact portion and the second contact portion. <8> The first cam has a first contact portion and a second contact portion that contact the first contact portion and the second contact portion, The distance between the first contact portion and the second contact portion is smaller than the distance between the first contact portion and the second contact portion. <7> The belt device described above. <9> <1> from <8> A transfer device equipped with one of the belt devices described above. <10> Transfer member equipped <9> The transfer apparatus described above, The first axis is a transfer device that moves the transfer member away from the latent image carrier by rotating the pressing member in a direction that changes the pressing member from the retracted position to the pressing position. <11> <9> or <10> This is an image forming apparatus equipped with the transfer device described above. [Explanation of Symbols]

[0126] 1. Image forming apparatus 2. Intermediate transfer belt (belt member or intermediate transfer body) 3. Photoreceptor (latent image carrier) 7. Primary transfer roller (primary transfer member) 20 Transfer device (belt device) 20A Inner Cover (Transfer Frame) 22 Detection sensor (contact / separation part) 71 Release lever (operating component) 71a Lever section (operating section) 71b Lever fixing axis (first axis) 73 First link member 74. Second link member (other link member) 75 Third link member (other link members) 76. Fourth link member (other link members) 77. Fifth link member (other link members) 78. Spring (biasing member) 80 Cam (fixing member) 82 First Cam 83 Come Followers 101 Retaining member 102 The second axis 1021 Central shaft portion (shaft portion constituting the second shaft) 1022, 1023 End-side shaft portion (shaft portion constituting the second shaft) [Prior art documents] [Patent Documents]

[0127] [Patent Document 1] Patent No. 6394151

Claims

1. A belt component that travels in a circular motion, A pressing member that holds down the belt member, A belt device comprising a transmission unit that transmits driving force to the aforementioned pressing member, The pressing member is provided to be able to reciprocate between a pressing position that holds the belt member and a retracted position that is retracted from the belt member. The transmission unit transmits driving force to the retaining member, thereby changing the retaining member to the retracted position. The aforementioned pressing member changes its orientation toward the pressing position due to its own weight. A first shaft that transmits driving force to the transmission unit by its own rotation, A belt device characterized by comprising a fixing member provided on the first shaft, which applies force to the first shaft in the pressing position to fix the phase of the first shaft.

2. The aforementioned transmission unit is A first link member having the first axis as the axis of rotation, A first cam that transmits driving force to the pressing member through its own rotation, One or more other link members that transmit driving force between the first link member and the first cam, The belt device according to claim 1, further comprising a biasing member that biases the first link member in the direction of the rotational phase of the first link member in the retracted position.

3. A belt device according to claim 1, comprising an operating member fixed to the first shaft, A belt device that can rotate the first shaft by operating the operating member.

4. The belt device according to claim 1, wherein the belt member has at least an elastic layer and is composed of a plurality of layers of different materials.

5. It further comprises a second shaft composed of multiple shaft sections, The belt device according to claim 2, wherein the plurality of shaft portions are connected via the first cam.

6. The aforementioned transmission unit The first cam is provided on a second shaft, which receives driving force from the other link member, A belt device according to claim 2, comprising a cam follower that swings due to the rotation of the first cam, The cam follower has a first contact portion and a second contact portion that contact the first cam in the retracted position or the pressing position, A belt device in which the first cam is positioned between the first contact portion and the second contact portion.

7. The first cam has a first contact portion and a second contact portion that contact the first contact portion and the second contact portion, The belt device according to claim 6, wherein the distance between the first contact portion and the second contact portion is smaller than the distance between the first contact portion and the second contact portion.

8. A transfer device comprising a belt device according to any one of claims 1 to 7.

9. A belt device and A transfer member and a transfer apparatus comprising, The aforementioned belt device is A belt component that travels in a circular motion, A pressing member that holds down the belt member, A transmission unit that transmits driving force to the aforementioned retaining member, It has a first shaft that transmits driving force to the transmission unit by its own rotation, The pressing member is provided to be able to reciprocate between a pressing position that holds the belt member and a retracted position that is retracted from the belt member. The transmission unit transmits driving force to the retaining member, thereby changing the retaining member to the retracted position. The aforementioned pressing member changes its orientation toward the pressing position due to its own weight. A transfer apparatus characterized in that the first axis rotates in a direction that changes the pressing member from the retracted position to the pressing position, thereby moving the transfer member in a direction that separates it from the latent image carrier.

10. An image forming apparatus comprising the transfer apparatus described in claim 8.

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