Pressure release mechanism, pressure device and image forming apparatus

Abstract

To provide a depressurization mechanism that can reduce an operating force when an operator closes an opening and closing member.SOLUTION: A depressurization mechanism of a pressure device applies pressure to a pressure target body with a pressure body, and the mechanism comprises: an attitude change member 203 that can take a pressurization attitude and a depressurization attitude according to attitude change; a contact member 230 that applies a contact force toward the depressurization attitude to the attitude change member 203 taking the pressurization attitude; and an opening and closing member 81 that can be opened and closed with respect to the pressure device and is installed with the contact member. The contact member 230 is rotatably attached to the opening and closing member 81 and has, between its leading end and base end, an entry part 233 for a leading end of the attitude change member 203.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a pressure release mechanism, a pressure device, and an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a pressure release mechanism of a pressure device that presses a pressurizing body against a pressurized body is known. For example, Patent Document 1 describes the following image forming apparatus equipped with such a depressurizing mechanism. This image forming apparatus has a pressurizing mechanism that pressurizes a pressurizing body against a pressure-receiving body, and an open / close member that can be opened and closed relative to the apparatus main body that houses the pressurizing mechanism. When the open / close member is opened, a first pressing portion (abutting member) of the open / close member presses a pressed member (position-changing member) of the apparatus main body, thereby releasing the pressurized state of the pressurizing mechanism. When the open / close member is closed, a second pressing portion of the open / close member presses a pressed member of the apparatus main body, thereby placing the pressurizing mechanism in a pressurized state. Summary of the Invention [Problem to be solved by the invention]

[0003] In a pressure release mechanism in which a contact force is applied to a posture change member that is in a pressure release posture by contacting a contact member installed on the opening / closing member, there was a problem in that, depending on the specific structure of the contact member, a large operating force was required by the operator to close the opening / closing member. [Means for solving the problem]

[0004] In order to solve the above-mentioned problems, the present invention provides a decompression mechanism for a pressurizing device that pressurizes a pressurized body against a pressurized body, the decompression mechanism comprising: a position-changing member that can take a pressurizing position and a decompression position by changing its position; a contact member that applies a contact force to the position-changing member that takes the pressurizing position toward the decompression position; and an opening / closing member that is openable and closable relative to the pressurizing device and on which the contact member is installed, the contact member being rotatably attached to the opening / closing member; a base end portion attached to the rotation shaft, and a front Tip of the posture change member Progress Enter a through hole and a tip end portion located on the opposite side of the base end portion across the through hole; Yes The abutting member is configured to rotate with the tip end portion in contact with the tip portion of the position-changing member in the pressure-applying position as the opening / closing member is closed from the open state, and then the tip end portion rotates beyond the tip of the position-changing member until it is positioned on the opposite side of the position-changing member in the opening / closing direction of the opening / closing member, and the width of the through hole in the axial direction of the rotation at the tip end side of the through hole portion is wider the closer to the base end portion.The present invention is characterized by the following. [Effects of the Invention]

[0005] According to the present invention, the operating force required by the operator to close the opening / closing member can be reduced. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of a printer according to an embodiment. [Figure 2] FIG. 3 is an explanatory diagram of a pressure / depressurization mechanism of the fixing device. [Figure 3] FIG. 10 is an explanatory diagram of a release hook according to a comparative example. [Figure 4] 10A and 10B are explanatory diagrams of a cover closing operation using a release hook of a comparative example. [Figure 5] 5A and 5B are explanatory diagrams of a release hook according to the embodiment. [Figure 6] 10A and 10B are explanatory diagrams illustrating the operation of closing the device cover by the release hook according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] An embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described below as an image forming apparatus to which the present invention is applied. First, the general configuration of the printer will be described. FIG. 1 is a schematic diagram showing the configuration of this printer. Printer 100 is a color printer that uses a tandem system in which image forming units that form multiple color images are arranged side by side along the extension direction of the belt, but the present invention is not limited to this system and can also be applied to not only printers but also copiers, facsimile machines, etc.

[0008] The printer 100 has four image stations as an image forming section each equipped with a photosensitive drum 20Y, 20C, 20M, and 20Bk, an optical writing device 8 as an optical writing device arranged below and facing the four image stations, a transfer belt unit 10 arranged above and facing the four image stations and equipped with a transfer belt 11 and primary transfer rollers 12Y, 12C, 12M, and 12Bk, a secondary transfer roller 5 as a transfer member arranged opposite the transfer belt 11 and driven by and rotating with the transfer belt 11, and an intermediate transfer cleaning device 13 arranged opposite the transfer belt 11 for cleaning the surface of the transfer belt 11.

[0009] The four image stations are photosensitive drums 20Y, 20C, 20M, and 20Bk, arranged in this order from the upstream side in the A1 direction. Each photosensitive drum 20Y, 20C, 20M, and 20Bk is provided in an image station for forming a yellow, cyan, magenta, or black image, respectively. Devices for forming an image in accordance with the rotation of the photosensitive drum are arranged around each photosensitive drum. Focusing on photosensitive drum 20Bk, which forms a black image, a charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk are arranged in the direction of rotation of photosensitive drum 20Bk, which perform the image formation process.

[0010] The optical writing device 8 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, and a rotating polygonal mirror as a deflection means, and is configured to emit writing light Lb corresponding to each color to each photosensitive drum 20Y, 20C, 20M, and 20Bk (in Figure 12, for convenience, only the image station for the black image is labeled, but the same applies to the other image stations), thereby forming electrostatic latent images on the photosensitive drums 20Y, 20C, 20M, and 20Bk.

[0011] In addition to the transfer belt 11 and primary transfer rollers 12Y, 12C, 12M, and 12Bk, the transfer belt unit 10 also has an elastic roller 72 around which the transfer belt 11 is wound, and a driven roller 73. The driven roller 73 also functions as a tension applying means for the transfer belt 11, and for this reason, a biasing means such as a spring is provided on the driven roller 73. The transfer belt unit 10, primary transfer rollers 12Y, 12C, 12M, and 12Bk, secondary transfer roller 5, and intermediate transfer cleaning device 13 constitute a transfer device 71.

[0012] The intermediate transfer cleaning device 13 has a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 11, and uses the cleaning brush and cleaning blade to scrape off and remove foreign matter such as residual toner on the transfer belt 11, thereby cleaning the transfer belt 11. The intermediate transfer cleaning device 13 also has a discharge means for carrying out and discarding the residual toner removed from the transfer belt 11.

[0013] The printer 100 has a sheet feeding device 61 serving as a paper feed cassette that holds recording sheets S that are transported toward between the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11. The sheet feeding device 61 is disposed in the lower part of the main body of the printer 100 and has a feed roller 3 that serves as a paper feed roller that contacts the upper surface of the uppermost recording sheet S. When the feed roller 3 is driven to rotate counterclockwise, the uppermost recording sheet S is fed toward the pair of registration rollers 4.

[0014] The printer 100 also has a pair of registration rollers 4 that feed the recording paper S transported from the sheet feeding device 61 toward the transfer section between each photosensitive drum 20Y, 20C, 20M, 20Bk and the transfer belt 11 at a predetermined timing that coincides with the timing of the formation of the toner image by the image station, and a sensor that detects when the leading edge of the recording paper S has reached the pair of registration rollers 4.

[0015] The printer 100 has a fixing device 200 as a fixing unit of a roller fixing type for fixing a toner image onto recording paper S onto which the toner image has been transferred. The fixing device 200 has a fixing roller 121 equipped with a heating means and a pressure roller 131, and is configured to fix the toner image onto the surface of recording paper S by applying heat and pressure to the recording paper S carrying the toner image. However, this configuration is not limited, as long as pressure is used for fixing.

[0016] The printer 100 is equipped with a paper discharge roller 7 that discharges the fixed recording paper S outside the main body of the printer 100, a paper discharge tray 17 that is disposed at the top of the main body of the printer 100 and that stacks the recording paper S that has been discharged outside the main body of the printer 100 by the paper discharge roller 7, and toner bottles 9Y, 9C, 9M, and 9Bk that are located below the paper discharge tray 17 and are filled with toner of each color: yellow, cyan, magenta, and black.

[0017] In printer 100, the visible images formed on each of the photosensitive drums 20Y, 20C, 20M, and 20Bk undergo a primary transfer process to an intermediate transfer body (hereinafter referred to as the transfer belt) 11, which is an endless belt that can move in the direction of arrow A1 while facing each of the photosensitive drums 20Y, 20C, 20M, and 20Bk, and the respective images are transferred in a superimposed manner.

[0018] The superimposed transfer onto the transfer belt 11 is performed by applying voltage from primary transfer rollers 12Y, 12C, 12M, and 12Bk arranged opposite each photosensitive drum 20Y, 20C, 20M, and 20Bk across the transfer belt 11, with the timing shifted from upstream to downstream in the A1 direction, so that the visible images formed on each photosensitive drum 20Y, 20C, 20M, and 20Bk are superimposed and transferred to the same position on the transfer belt 11 as the transfer belt 11 moves in the A1 direction.

[0019] The visible image superimposed and transferred onto the transfer belt 11 is then transferred all at once to a recording sheet or other recording paper S by performing a secondary transfer process with a secondary transfer roller 5. The recording paper S onto which the toner image has been transferred all at once has the toner image fixed by a fixing device 200, and the fixed recording paper S is discharged outside the main body of the printer 100 by a paper discharge roller 7.

[0020] This printer 100 has an apparatus cover 81 (exterior cover) as an opening / closing member that is rotatably attached by a rotation shaft 82 provided at the bottom end. A contact member of a depressurization mechanism, which will be described later, is installed on this apparatus cover 81. The apparatus cover 81 supports rollers on the apparatus cover 81 side across the conveyance path that constitutes the secondary transfer roller 5 and the pair of registration rollers 4.

[0021] Next, a description will be given of the pressure application / release mechanism of the fixing device 200, which is a pressure application device in this embodiment. Figure 2 is an explanatory diagram of the pressure application / release mechanism of the fixing device 200. It comprises a pressure application lever 201, a pressure application spring 202, and a pressure release lever 203. The upper end of the pressure application lever 201 is rotatably supported by a shaft 204. One end of the pressure application spring 202 is engaged with the lower end of the pressure application lever 201, and the other end is engaged with a position near the lower end of the pressure release lever 203. The lower end of the pressure release lever 203 is rotatably supported by a shaft 205. The pressure release lever 203 corresponds to a position change member that can take a pressure application position and a pressure release position by changing its position.

[0022] The position shown in Figure 2(a) is the pressurized state. Pressure release lever 203 is biased by pressure spring 202 and fixed in the position shown in the figure. When pressure release lever 203 is rotated by θ from the position shown in Figure 2(a), it reaches the position shown in Figure 2(b), which is the inflection point (dead point). When rotated further, it is biased to the position shown in Figure 2(c) and fixed. At the position shown in Figure 2(c), fixing roller 121 connected to pressure lever 201 moves away from pressure roller 131.

[0023] The operation of shifting the pressure release lever 203 from the position in Figure 2(a) to the position in Figure 2(c) (changing from the pressurized state to the released state) is performed by a release hook installed on the device cover 81. The release hook corresponds to an abutting member that applies a contact force to the posture change member in the pressurized posture toward the depressurized posture.

[0024] When a paper jam occurs, in conjunction with the opening operation of the device cover 81, a release hook installed on the device cover 81 tilts down the pressure release lever 203 (swing lever), which is part of the separation mechanism between the fixing roller 121 and the pressure roller 131, separating the pressure roller 131 from the fixing roller 121, making it easier to remove the jammed paper. In this embodiment, the release hook has been improved.

[0025] 3 is an explanatory diagram of a release hook 210 according to a comparative example. This release hook 210 is composed of a horizontal portion 211 extending horizontally from the device cover 81 and a hanging portion 212 extending downward from the tip of the horizontal portion 211. The base end of the horizontal portion 211 is fixed to the device cover 81.

[0026] FIG. 3(a) shows the pressurized state. In this position, the lower part of hanging part 212 faces pressure release lever 203 from the side opposite device cover 81. FIG. 3(b) shows the separated state. In order to have the lower part of hanging part 212 face pressure release lever 203 from the side opposite device cover 81 as shown in FIG. 3(a), the dimension shown by A in the figure (height difference between the top end of the pressure release lever and the top end of the cover; the top end of the cover is at least higher than the cover mounting portion of release hook 210) is required due to the dimensions of hanging part 212. This becomes an obstacle when it comes to lowering the vertical height of the device. The release hook of this embodiment has also been improved in this respect, as will be described later.

[0027] 4 is an explanatory diagram of the operation of the release hook 210 of the comparative example in which the pressure release lever 203 transitions (from a separated state to a pressurized state) in conjunction with the cover closing operation. FIG. 4(a) shows a state in which the device cover 81 is closed in the direction of arrow A41, and the release hook 210 (tip) on the device cover 81 comes into contact with the pressure release lever 203. FIG. 4(b) shows a state in which the release hook 210 (tip) further presses the pressure release lever 203. In this state, the position of the device cover 81 is the same as the position shown in FIG. 4(d) when the cover is closed.

[0028] Figure 4(c) shows the moment when the release hook 210 (tip) passes over the tip of the pressure release lever 203. When it passes over, the reaction force moves the pressure release lever 203 as shown by arrow A42, returning it to the position shown in Figure 4(a). At the moment shown in Figure 4(a), the device cover 81 is positioned further into the device body than its closed position. In other words, an overstroke state occurs.

[0029] 4(d) shows the state after the cover closing operation is completed. The device cover 81 is biased in the direction of arrow A43 by the conveying roller or the like, and the device cover 81 returns to the position where the latch claw 222 provided on the top of the device cover 81 contacts the pin 221 installed on the device body.

[0030] As described above, the release hook 210 of the comparative example requires the device cover 81 to overstroke relative to the main body, as shown in Figures 4(c) and 4(d), and the reaction force of the pressure release lever 203 is applied, resulting in a large operating force. The release hook of this embodiment, as will be described later, reduces this operating force. Note that even with a mechanism that does not generate a reaction force from the pressure release lever 203, the operating force will still be large even with just the overstroke against the biasing force of the conveying roller or the like, as shown by arrow A43 in Figure 4(d).

[0031] FIG. 5 is an explanatory diagram of the release hook of this embodiment. The release hook of this embodiment is rotatably attached to the device cover 81, and has an insertion portion for the tip of the pressure release lever 203 between its tip end and base end. Specifically, as shown in FIG. 5(a), the release hook 230 is rotatably attached to the device cover 81 by a rotation shaft 232. The center of the rotation shaft 232 becomes the rotation center 231. The release hook 230 is held in position by a stopper shape at the position shown in FIG. 5(a). And, as shown in FIG. 5(b) viewed from direction B, the release hook 230 has a through-hole 233 as an insertion portion. This through-hole 233 is shaped so that the tip of the pressure release lever 203 can be inserted into it.

[0032] The release hook 230 has a shape that allows the pressure release lever 203 to pass through, and the release hook 230 can be installed at a position closer to the rotation center 231 of the pressure release lever 203 than the tip of the pressure release lever 203. As a result, the dimension A (the difference in height between the top end of the pressure release lever and the top end of the cover) shown in FIG. 5(a) is smaller than in the comparative example. This makes it possible to lower the vertical height of the device. In other words, the release hook 230 does not limit the machine height.

[0033] As shown in Figure 5(b), it is preferable that the hole width E near the tip of the release hook 230 away from the rotation center 231 is narrower than the hole width D close to the rotation center 231. This is to reduce the risk that when the pressure release lever 203 enters (is inserted into) the release hook 230, the pressure release lever 203 will shift in the X direction (direction parallel to the rotation center 231) in Figure 5(b), causing pressure deviation or damage to the lever.

[0034] As shown in FIG. 5(c), the hole width E near the tip is preferably such that the width E1 on the insertion entrance side is wider than the width E2 on the exit side so that the tip of the pressure release lever 203 can be easily inserted.

[0035] Figure 6 is an explanatory diagram of the closing operation of the device cover 81 by the release hook 230 of the embodiment. Figure 6(a) shows a state in which the device cover 81 is closed in the direction of arrow A61, and the release hook 230 (tip) on the device cover 81 comes into contact with the pressure release lever 203. Figure 6(b) shows a state in which the release hook 230 (tip) does not push the pressure release lever 203, but the release hook 230 rotates and the tip of the pressure release lever 203 enters the hole. Figure 6(c) shows a state in which the cover closing operation is completed. Unlike the release hook 230 of the comparative example, an overstroke state is not required.

[0036] As described above, the device of this embodiment includes a first member (fixing roller 121) extending in the axial direction, a second member (pressure roller 131) that presses against the first member to form a nip, a pressure member (pressure lever 201) that presses either the first or second member, a pressing member (spring) connected to the pressure member and applying a load to form the nip, and a load adjustment member (pressure release lever 203) that has a connecting portion connected to the pressing member and changes the load on the pressing member by rotating or moving. The device also includes a contact member (release hook 230) with a contact portion that contacts the load adjustment member, and a pressure release mechanism with an exterior member on which the contact member is installed. This contact member rotates, and the portion where the load adjustment portion of the contact member contacts is ring-shaped.

[0037] Therefore, when the cover is closed, there is no overstroke state as in the comparative example, and the reaction force from the pressure release lever 203 is small, so usability is superior to the comparative example. When the mounting member is closed (when pressure is applied), the pressure release lever 203 can be inserted into the ring portion of the abutting member, so the height of the abutting member is lower than the tip of the pressure release lever 203, and as a result, the height of the abutting member does not limit the machine height. Note that depressurization does not only mean zero pressure, but also includes cases where pressure is reduced. [Explanation of symbols]

[0038] 2: Manuscript figure 3: Feed roller 4: Registration roller pair 5: Secondary transfer roller 7: Paper ejection roller 8: Optical writing device 9Bk: Toner bottle 9C: Toner bottle 9M: Toner bottle 9Y: Toner bottle 10: Transfer belt unit 11: Transfer belt 12Bk: Primary transfer roller 12C: Primary transfer roller 12M: Primary transfer roller 12Y: Primary transfer roller 13: Intermediate transfer cleaning device 17: Paper output tray 20Bk: Photosensitive drum 20C: Photosensitive drum 20M: Photosensitive drum 20Y: Photosensitive drum 30Bk: Charging device 0032 :Paragraph 40Bk:Developing device 50Bk: Cleaning device 61: Sheet feeding device 71: Transfer device 72: Elastic roller 73: Driven roller 81: Device cover 82: Rotating shaft 100: Printer 121: Fuser roller 131: Pressure roller 200: Fixing device 201: Pressure lever 202: Pressure spring 203: Pressure release lever 210: Release hook 211:Horizontal part 212: Drooping part 221: Pin 222: Latch claw 230: Release hook 231: Center of rotation 232: Rotating shaft 233: Through hole A: Dimensions A1: Arrow A41: Arrow A42: Arrow A43: Arrow A61: Arrow direction D: Hole width E: Hole width E2:Exit side Lb: Writing light S: Recording paper [Prior art documents] [Patent documents]

[0039] [Patent Document 1] Japanese Patent Publication No. 2020-024355

Claims

1. In a depressurization mechanism of a pressurizing device that presses a pressurizing body against a pressurized body, a position-changing member that can take a pressure-applying position and a pressure-relieving position by changing its position; a contact member that applies a contact force to the position-changing member in the pressure-applying position, in order to move the position-changing member in the pressure-applying position toward the pressure-relieving position; an opening / closing member that is openable and closable relative to the pressure device and on which the abutment member is installed, the abutment member is rotatably attached to the opening / closing member, and has a base end attached to the axis of rotation, a through hole into which the tip of the posture changing member can enter, and a tip end located on the opposite side of the through hole from the base end, the abutment member is configured to rotate while bringing the tip portion into contact with the tip portion of the posture change member in the pressure position as the opening / closing member is closed from the open state, and then rotate until the tip portion passes the tip of the posture change member and is positioned on the opposite side of the posture change member in the opening / closing direction of the opening / closing member, The pressure release mechanism is characterized in that the width of the through hole in the axial direction of the rotation becomes wider as it approaches the base end.

2. In the decompression mechanism described in claim 1, The pressure release mechanism is characterized in that the width of the through hole in the axial direction of the rotation becomes wider toward the upstream side in the direction in which the tip of the posture changing member enters.

3. A first member; a second member that is pressed against the first member to form a nip; a pressing member that applies a load to form the nip; a pressure-relieving mechanism having a connecting portion connected to the pressing member and including a position-changing member that can take a pressure-relieving position and a pressure-relieving position by changing its position, A pressure-relieving mechanism according to claim 1 or 2, wherein the pressure-relieving mechanism is a pressure-relieving mechanism.

4. The pressure release mechanism according to claim 1 or 2 An image forming apparatus comprising the pressure device according to claim 3.

Images