Image forming apparatus

Abstract

This technology provides a way to suppress the force of the pressurizing member from becoming resistance when closing the opening / closing part. [Solution] An image forming apparatus for forming an image on recording material transported through a transport path, comprising: an apparatus body having a receiving portion arranged on the transport path; an opening / closing portion that can move between an open position that exposes the transport path and a closed position that covers the transport path; a roller provided on the opening / closing portion; a pressurizing portion that pressurizes the roller; a separating portion provided on the apparatus body that moves between a first position and a second position, where the roller and the receiving portion are in contact and the receiving portion is pressurized when in the first position, and where the roller separates from the receiving portion when in the second position; a switching device for switching the position of the separating portion; a control unit; and a detection unit for detecting the opening and closing of the opening / closing portion, wherein the separating portion is in the second position and the opening / closing portion is in the open position, and the separating portion is moved to the first position.

Description

Technical Field

[0006] ,

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

Background Art

[0002] An image forming apparatus has a configuration in which a recording material is pressed and conveyed by a plurality of roller pairs. For example, in a transfer unit that transfers a developer image from a photosensitive drum or an intermediate transfer body to a recording material, and a transport roller pair that transports the recording material on a transport path, there are a driving roller that rotates by receiving a driving force from a driving source, a driven roller that is opposed to the driving roller via a transport path and rotates in a driven manner, a bearing that rotatably supports each roller, and a pressing member that presses the driven roller against the driving roller with a predetermined contact force.

[0003] Regarding the transfer unit, in a configuration having an opening / closing door that can be opened and closed and that opens and closes the space inside the main body of the image forming apparatus, a counter roller as a driving roller is provided on the main body side, and a transfer roller as a driven roller is provided on the opening / closing door side (Patent Document 1).

[0004] In Patent Document 1, by moving the transfer roller, a state in which a secondary transfer nip between the transfer roller and the counter roller is formed and a state in which the secondary transfer nip is opened are switched.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In an image forming apparatus in which the apparatus main body has a receiving portion and an opening / closing portion that can be opened and closed with respect to the apparatus main body includes a roller and a pressing portion that presses the roller toward the receiving portion, when closing the opening / closing portion, the force of the pressing member may become a resistance.

[0007] One of the objectives of the present invention is to provide a technology that can suppress the force of the pressurizing member from becoming resistance when closing the opening / closing part. [Means for solving the problem]

[0008] This invention employs the following configuration: An image forming apparatus that forms an image on a recording material transported through a transport path, The device body having a receiving portion arranged in the aforementioned transport path, The device body is provided with an opening / closing section that can move between an open position where the transport path is exposed to the outside and a closed position where the transport path is covered. A roller provided in the opening / closing section, which is positioned in the transport path when the opening / closing section is closed, A pressurizing section is provided in the opening / closing section and pressurizes the roller, A separation portion provided on the main body of the apparatus, which is movable between a first position and a second position, and when in the first position, the roller is in contact with the receiving portion and the force of the pressurizing portion is received by the receiving portion, and when in the second position, the separation portion holds the roller in a position away from the receiving portion against the force, A switching device that can switch the position of the separated portion between the first position and the second position. and, A control unit that controls the switching device, An opening / closing detection unit for detecting the opening / closing state of the opening / closing part, It has, When it is detected that the separating portion is in the second position and the opening / closing portion is in the open position, the control unit controls the switching device so that the separating portion moves from the second position to the first position. This is an image forming apparatus characterized by the following features. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a technique capable of suppressing the force of the pressing member from becoming a resistance when closing the opening / closing portion.

Brief Description of the Drawings

[0010] [Figure 1] Cross-sectional view of the image forming apparatus according to the first embodiment of the present invention [Figure 2] Cross-sectional view of the opening / closing door of the first embodiment of the present invention in the opened state [Figure 3] Perspective view of the intermediate transfer unit of the first embodiment of the present invention [Figure 4] Perspective view of the roller separation mechanism of the first embodiment of the present invention [Figure 5] Partial perspective view of the transfer unit of the first embodiment of the present invention [Figure 6] Cross-sectional view of the image forming apparatus according to the first embodiment of the present invention [Figure 7] Perspective view of the roller separation mechanism of the first embodiment of the present invention [Figure 8] Cross-sectional view of the operation of closing the opening / closing door of the first embodiment of the present invention [Figure 9] Cross-sectional view of the operation of closing the opening / closing door of the first embodiment of the present invention [Figure 10] Perspective view of the roller separation mechanism according to the second embodiment of the present invention [Figure 11] Cross-sectional view of the image forming apparatus according to the third embodiment of the present invention [Figure 12] Cross-sectional view of the image forming apparatus according to the third embodiment of the present invention

Mode for Carrying Out the Invention

[0011] Hereinafter, with reference to the drawings, modes for carrying out the present invention will be exemplarily and specifically described based on embodiments. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. That is, the scope of the present invention is not intended to be limited to the following embodiments.

[0012] [Example 1] (Schematic description of the image forming apparatus) FIG. 1 is a cross-sectional view of an image forming apparatus A of a color electrophotographic system using a laser beam method in Example 1. The image forming apparatus A includes a paper feed cassette 1 that is horizontally arranged below in the vertical direction and on which a recording material S is placed, an intermediate transfer unit 20 arranged above the paper feed cassette 1, four process cartridges (PY, PM, PC, PK) arranged side by side above the intermediate transfer unit 20 and corresponding to different colors, and a laser scanner unit 6 that is an optical means arranged above the process cartridge P.

[0013] The paper feed cassette 1 is movable in the direction of arrow TR between the inside and outside of the apparatus main body A1, and when it is pulled out to the outside of the apparatus main body, the user can replenish the recording material S. The recording material S in the paper feed cassette 1 is conveyed by a paper feed roller 2. When the conveyed recording material S passes through a registration unit composed of a registration roller pair 3, the deviation of the leading end in the conveyance direction is corrected, and it is conveyed to the nip between the transfer roller 4 of the secondary transfer unit 48 and the counter roller 22. Any number of conveyance rollers may be provided in the conveyance path 10.

[0014] On the other hand, the laser scanner unit 6 writes an electrostatic latent image on a photosensitive drum 51 which is an image carrier in the process cartridge P based on image data. The four process cartridges P are arranged side by side in the order of yellow PY, magenta PM, cyan PC, and black PK, and constitute four-color image forming stations. The toner images formed at these four-color stations are superposed and primary-transferred onto the intermediate transfer belt 21, whereby a full-color toner image is formed on the intermediate transfer belt 21.

[0015] Then, the toner image on the intermediate transfer belt 21 is transferred to the recording material S sent to the nip of the secondary transfer unit 48, whereby a full-color toner image is formed at a predetermined position on the recording material. The recording material S onto which the toner image has been transferred is sent to a fixing unit 7, and heat and pressure are applied at the fixing nip, whereby the toner image is fixed on the surface of the recording material. Thereafter, the recording material S is discharged to a paper discharge tray 8 arranged above the apparatus.

[0016] In this embodiment, the image forming apparatus A has a paper feed cassette 1 positioned at the bottom in the vertical direction, and a transport path 10 is formed along the front of the image forming apparatus A (right side in Figure 1) in a substantially vertical direction for transporting the recording material S (shown by a dashed line). As the recording material S passes through the transport path 10, it passes through the register roller pair 3, the secondary transfer unit 48, and the fixing unit 7, and an image is recorded before it is discharged into the uppermost output tray 8.

[0017] In Figure 1, the right side of the transport path 10 for the recording material S is an opening / closing door 30 pivoted on an axis 31. The opening / closing door 30 is an opening / closing part pivotally supported on the main body A1 of the device. The opening / closing door 30 is movable between an open position in which the transport path 10 is exposed to the outside and a closed position in which it covers the transport path 10. If the recording material S jams in the transport path, the opening / closing door 30 can be opened to open the transport path 10 and remove the jammed recording material S.

[0018] Figure 2 shows the opening / closing door 30 in the open position. The opening / closing door 30 holds the driven roller 3b of the register roller pair 3, and when the opening / closing door 30 is opened, the register roller nip is released, making it easier to remove jammed recording material S from the transport path 10. The transfer roller 4 is a roller supported by the transfer frame 40, which is the frame part. The transfer roller 4 is supported so that it can rotate and slide toward the intermediate transfer belt 21. The transfer frame 40 is a unit that can rotate around an axis 40a different from that of the opening / closing door 30, and opens and closes the transfer nip in conjunction with the opening and closing of the opening / closing door 30.

[0019] Image forming apparatus A is equipped with a door switch 35 as an open / close detection unit that detects the open / closed state of the open / closed door 30. When the open / closed door 30 opens with the shaft 31 at the lower right of the main body as a pivot point, the opening of the open / closed door 30 is detected when the open / closed door 30 moves away from the door switch 35. More specifically, the state of the signal output from the door switch 35 (hereinafter referred to as the signal state) differs depending on whether the open / closed door 30 is open or closed. The signal state of the door switch 35 switches, for example, ON-OFF or High-Low, in accordance with the opening and closing of the open / closed door 30. The signal from the door switch 35 is sent to the control board 9 of image forming apparatus A and used to control the apparatus. The control board 9 is a control unit that controls each component of image forming apparatus A. The control board 9 can perform scanning of the laser scanner unit 6 based on image data received from an external device, timing control of image formation and transport of recording material S at each image forming station, detection of the open / closed state of the open / closed door 30, and notification to the user.

[0020] (Intermediate transfer unit) Figure 3 shows a perspective view of the intermediate transfer unit 20. The intermediate transfer unit 20 tensions the intermediate transfer belt 21 with opposing rollers 22, tension rollers 23, and assist rollers 24. The opposing rollers 22, tension rollers 23, and assist rollers 24 are connected to the intermediate transfer frame 25. It is rotatably supported. When the opening / closing door 30 is opened, the user can attach and detach this intermediate transfer unit 20 to the image forming apparatus A. The intermediate transfer unit 20 is positioned by abutting the rotation axis of the opposing roller 22, which is a rotating body, against a frame (not shown) of the image forming apparatus A. The intermediate transfer frame 25 is provided with a groove 25a that slidably supports the protrusion 4a1 (see Figure 5) of the transfer bearing 4a of the transfer roller 4.

[0021] A drive coupling 26 for driving the intermediate transfer belt 21 is fixed to the rotation axis of the opposing roller 22. The driving force from the motor 55, which is a drive source provided in the main body A1 of the device, is transmitted via the main body coupling and then via the drive coupling 26, causing the opposing roller 22 to rotate (arrow R1). As a result, the surface of the intermediate transfer belt 21 moves in the direction of arrow FS at a predetermined speed. The motor 55 is a drive source that generates power to rotate various rotating bodies in the device. The number of motors 55 is not limited to one, and multiple drive sources may be provided depending on the rotating body. The driving force from the motor 55, which is a drive source, is transmitted to the object to be driven via any transmission member such as a coupling member, gear, or belt.

[0022] In this configuration of the intermediate transfer unit 20, positioning and drive transmission are concentrated on the rotation axis of the opposing roller 22, allowing for high-precision alignment of the drive coupling 26 and the main body coupling. A separation coupling 27 is provided near the drive coupling 26. The separation coupling 27 receives drive force from a drive train (not shown) that is different from the drive coupling 26.

[0023] Inside the intermediate transfer frame 25, a gear 27a is positioned coaxially with the separation coupling 27 (see Figure 4). Also inside the intermediate transfer frame 25, a separation cam 28, which acts as a separation part, is rotatably supported on the rotation axis 22a of the opposing roller 22. The separation cam 28 is integrally constructed by aligning a cam 28a, which can move toward and away from the contact surface 4a2 of the transfer bearing 4a, and a gear 28b in the direction of the rotation axis. Gears 27a and 28b are connected by an intermediate gear 29, and the rotational force from the separation coupling 27 is transmitted to gear 28b, causing the separation cam 28 to rotate. The opposing roller 22 can contact the inner circumference of the intermediate transfer belt 21, and the intermediate transfer belt 21 can contact the recording material S being transported along the transport path 10.

[0024] (Transfer unit) Figure 5 shows a partial perspective view centered on a portion of the transfer frame 40 of the transfer unit (secondary transfer unit 48). A transfer bearing 4a is slidably supported on the transfer frame 40 in the direction of arrow R2, and a transfer spring 42, which is a pressurizing part, is positioned between the transfer frame 40 and the transfer bearing 4a. The transfer spring 42 is a biasing means that can be compressed and extended, and it presses against the transfer bearing 4a, generating a predetermined pressurizing force such that the transfer roller 4 (secondary transfer roller) moves toward the opposing roller 22. The transfer roller 4 is rotatably supported on the transfer bearing 4a, so that it is slidable and rotatable relative to the transfer frame 40. The transfer roller 4 can be removed from the transfer frame 40 together with the transfer bearing 4a, making it detachable from the image forming apparatus A.

[0025] When the opening / closing door 30 is in the open position, the transfer roller 4 is away from the transport path 10, and when the opening / closing door 30 is in the closed position, the transfer roller 4 is located on the transport path 10. When the opening / closing door 30 is in the closed position, the part that receives force from the transfer roller 4 is called the receiving part. The receiving part is located on the transport path 10. The opposing roller 22 can be said to be in a position to receive force from the transfer roller 4 via the transport path 10 and the intermediate transfer belt 21. Therefore, the receiving part includes the opposing roller 22 and the part of the intermediate transfer belt 21 that is sandwiched between the opposing roller 22 and the transfer roller 4.

[0026] The transfer bearing 4a has a protrusion 4a1 that is coaxial with the rotation axis of the transfer roller 4. The protrusion 4a1 is shown in Figure By fitting into the groove 25a of the intermediate transfer frame 25 shown in 3, the transfer roller 4 is positioned relative to the intermediate transfer unit 20 in a direction perpendicular to the sliding direction.

[0027] As shown in Figure 2, in this embodiment, when the opening / closing door 30 is opened, the transfer roller 4 pushes the intermediate transfer belt 21 due to the elastic force of the transfer spring 42. The transfer frame 40 is located below the transfer roller 4 and rotates relative to the image forming apparatus A around a pivot axis 40a that is different from the axis 31 of the opening / closing door 30. Due to the center of gravity balance of the transfer unit, the transfer roller 4 rotates in a direction away from the intermediate transfer belt 21, opening the transfer nip. This makes it easy to remove the recording material S even if the recording paper jams in the transfer section.

[0028] (Roller separation mechanism) When the image forming apparatus A transports the recording material S, the transfer roller 4 is pressed against the intermediate transfer belt 21 by a transfer spring 42. When pressing, a force of approximately 2 to 8 kgf is applied to both ends, for example. Therefore, if the transfer roller 4 is left pressed against the intermediate transfer belt 21 for a long period of time, creep deformation may occur in the intermediate transfer belt 21 and the transfer roller 4. To address this, a roller separation mechanism 44 is provided to separate the transfer roller 4 from the intermediate transfer belt 21 if no operation instruction is given to the image forming apparatus A for a predetermined period of time. The roller separation mechanism 44 in this embodiment includes at least a separation cam 28.

[0029] Figure 7(a) shows the state in which the roller separation mechanism 44 separates the transfer roller 4 from the intermediate transfer belt 21. This is the state during image forming operation, or when the elapsed time since the previous image forming operation is within a predetermined time. In this case, the cam 28a of the separation cam 28 is stopped at a position where the R-shaped part 28a1 faces the contact surface 4a2 of the transfer bearing 4a. This position is also called the first position. When the separation cam 28 is in the first position, as shown in Figure 1, the transfer roller 4 is in contact with the intermediate transfer belt 21 with a predetermined pressure, and this state is defined as the contact state of the roller separation mechanism 44. Since the separation cam 28 is rotatably supported by the opposing roller 22, even if the opposing roller 22 rotates due to the driving force from the drive coupling 26, the separation cam 28 remains stopped and its position relative to the transfer bearing 4a does not change. For this reason, the roller separation mechanism 44 can maintain the contact state even during image forming operation.

[0030] If no operation command is given for a predetermined time after the image forming operation has stopped, the control board 9 sends a drive command to the motor 55, which is the drive source for the roller separation mechanism 44, and moves the roller separation mechanism 44 to the separated state shown in Figure 7(b). This is shown in Figures 6 and 7(b). When the separation coupling 27 rotates, the separation cam 28 rotates through the rotation of gear 27a (arrow F1), gear 29 (arrow F2), and gear 28b (arrow G1), moving from the first position to the second position. The separation cam 28 has a surface that includes a small R portion 28a1 and a large R portion 28a2, extending in a direction perpendicular to the axis of rotation. The control board 9 moves the separation cam 28 to the second position, bringing the large R portion 28a2 into contact with the contact surface 4a2 of the transfer bearing 4a.

[0031] As shown in the figure, when the R-shaped part 28a2 and the contact surface 4a2 of the transfer bearing 4a are in contact, the transfer bearing 4a pushes in the transfer spring 42 (arrow G2), causing the transfer roller 4 to move to a position separated from the intermediate transfer belt 21. This separated state releases contact between the transfer roller 4 and the intermediate transfer belt 21, thus preventing creep deformation of the intermediate transfer belt 21 and the transfer roller 4. In this way, the control board 9 controls a switching device including the motor 55 and gears 27a, 28b, and 29 to switch the position of the separation cam 38, which acts as the separation part, between a first position and a second position, thereby switching between the contact state and the separated state of the transfer roller 4 and the opposing roller 22.

[0032] When the image forming apparatus A is instructed to perform an image forming operation while in the separated state, the control board 9 moves the roller separation mechanism 44 to the contact state shown in Figures 7(a) and 1, and the transfer roller The part 4 is brought into contact with the intermediate transfer belt 21. This makes the image forming operation possible.

[0033] (Door closing operation) Next, the operation of the roller separation mechanism 44 when closing the opening / closing door 30 will be described. When closing the opening / closing door 30, which is in the open state, the opening / closing door 30 rotates around the shaft 31 on the lower side of the device and comes into contact with the transfer frame 40 during the closing operation (see Figure 8). As the closing operation continues, the transfer frame 40, pushed by the transfer roller 4, rotates around the pivot axis 40a. As the closing operation continues further, the protrusion 4a1 of the transfer bearing 4a engages with the groove 25a of the intermediate transfer frame 25, restricting the vertical position of the transfer roller 4 relative to the intermediate transfer unit 20. As the closing operation continues further, the transfer roller 4 approaches the intermediate transfer belt 21 due to the linked rotation of the transfer frame 40. In other words, the transfer frame 40 and the opening / closing door 30 are movable relative to each other, and after coming into contact during the closing operation of the opening / closing door 30, they rotate in the same direction in conjunction to close.

[0034] When the roller separation mechanism 44 is in contact (see Figure 7(a)), the R-shaped part 28a1 of the separation cam 28 faces the contact surface 4a2 of the transfer bearing 4a. Therefore, the separation cam 28 and the transfer bearing 4a do not come into contact, and the transfer roller 4 comes into contact with the intermediate transfer belt 21. During the subsequent closing operation of the opening / closing door 30, the transfer spring 42 is compressed between it and the transfer frame 40. When the opening / closing door 30 and the transfer frame 40 are completely closed (see Figure 1), the transfer spring 42 applies a predetermined pressure, causing the transfer roller 4 to pressurized contact with the intermediate transfer belt 21. At this time, the resistance of the transfer spring 42 when closing the opening / closing door 30 is the reaction force of the pressure applied when the transfer roller 4 is transporting the recording material S that is in pressurized contact with the intermediate transfer belt 21. When the opening / closing door 30 is completely closed, the end of the opening / closing door 30 comes into contact with the door switch 35. The door switch 35 then detects that the opening / closing door 30 has been closed. In other words, the control board 9 is notified that the door switch 35 has changed signal status and that the door 30 has closed. As a result, the control board 9 determines that the image forming apparatus A is now ready to operate.

[0035] Here, if the roller separation mechanism 44 is in the separated state and the opening / closing door 30 is closed, as shown in Figure 9, the contact surface 4a2 of the transfer bearing 4a contacts the large radius portion 28a2 of the separation cam 28 before the transfer roller 4 contacts the intermediate transfer belt 21. When the opening / closing door 30 is completely closed, the contact surface 4a2 of the transfer bearing 4a is pushed in by the large radius portion 28a2 of the separation cam, and the transfer bearing 4a compresses the transfer spring 42 more than when it is in contact (see Figures 6 and 7(b)). In other words, when the opening / closing door 30 is closed, the amount of deformation of the transfer spring 42 in the separated state is greater than the amount of deformation of the transfer spring 42 in the contact state. Therefore, the transfer frame 40 receives a larger reaction force than when it is in contact, and this force biases the opening / closing door 30 in the direction of opening. When the roller separation mechanism 44 is in the separated state, the reaction force of the transfer spring 42 generated when closing the opening / closing door 30 becomes greater than when it is in the contact state, thus increasing the operating force required to close the opening / closing door 30.

[0036] Thus, when the roller separation mechanism 44 is in the separated state, the operating force increases, which may cause the user to stop closing the opening / closing door 30 midway. If the opening / closing door 30 is not completely closed, the door switch 35 does not detect that the opening / closing door 30 is closed, and the control board 9 notifies the user of the message "opening / closing door 30" via the operation panel or other means. As a result, even though the user believes they have closed the opening / closing door 30, the image forming apparatus A prompts them to close the opening / closing door 30, which may lead the user to believe that the image forming apparatus A has malfunctioned.

[0037] (Processing in this embodiment) To avoid this situation, the following process is performed in this embodiment. When the roller separation mechanism 44 is in the separated state shown in Figure 7(b), the opening / closing door 30 is opened, and the door switch 3 When the control board 9 detects that the door 30 has opened, it issues a drive command to the motor 55, which is the drive source for the separation coupling 27, causing the roller separation mechanism 44 to transition to the contact state shown in Figure 7(a). Specifically, based on the change in the signal state of the door switch 35 due to the opening of the door 30, the control board 9 issues a drive command to the motor 55, which is the drive source for the separation coupling 27, causing the roller separation mechanism 44 to transition to the contact state shown in Figure 7(a). If the door 30 is opened while the roller separation mechanism 44 is in the contact state, it maintains that contact state. In other words, in this embodiment, when the door 30 is open, the roller separation mechanism 44 is in the contact state.

[0038] As a result, when closing the opening / closing door 30, the roller separation mechanism 44 is always in contact, thus suppressing an increase in the operating force of the opening / closing door 30.

[0039] The roller separation mechanism 44 separates the transfer rollers 4 to prevent creep deformation of the intermediate transfer belt 21 and transfer rollers 4, which may occur if they are left in contact for a long period of time. Therefore, even if the opening / closing door 30 transitions to a contact state while it is in the open state, problems such as creep deformation will not occur.

[0040] Furthermore, the roller separation mechanism 44 is located inside the intermediate transfer unit 20, and the drive train that drives the separation coupling 27 is also located inside the image forming apparatus. Therefore, even if the roller separation mechanism 44 is driven after detecting that the opening / closing door 30 has opened, the user will not come into contact with the rotating parts of the gears or separation cam 28. Consequently, there is no possibility of the user being injured by touching the rotating parts, and there are no safety concerns.

[0041] Furthermore, it is preferable that the timing of transitioning to the contact state be immediately after the door switch 35 detects that the opening / closing door 30 has opened, so that the drive noise of gears, etc., is masked by the operating noise of the opening / closing door 30. In other words, it is preferable that the transition of the roller separation mechanism 44 to the contact state occurs after the signal state of the door switch 35 changes due to the opening of the opening / closing door 30, but before the opening / closing door 30 reaches the open position.

[0042] In this embodiment, the transfer frame 40 and the opening / closing door 30 have been described as rotating on different axes of rotation. However, the functions and effects described above can also be obtained if the transfer frame 40 is held and moved by the opening / closing door 30, or if the transfer roller 4 is supported by the opening / closing door 30.

[0043] As mentioned above, when the opening / closing door 30 is open, no problems such as deformation occur even if it is in contact with the door. However, if the opening / closing door 30 is closed by the user, problems such as deformation may occur if it remains in contact with the door for a long time. Therefore, if a predetermined time has elapsed after the opening / closing door 30 has been closed without any image forming operations being performed, the control board 9 uses the roller separation mechanism 44 to transition it to a separated state.

[0044] [Example 2] In Example 1, a roller separation mechanism 44 was used in which a separation cam rotatably mounted on the opposing roller 22 was used as the pressing member. On the other hand, in Example 2, a roller separation mechanism 45 using a slider as the pressing member will be described. The details explained in Example 1 will be omitted.

[0045] In this embodiment, the separation coupling 27 has a cam 27c inside the intermediate transfer frame 25, as shown in Figures 10(a) and (b). A protrusion 27c1 is provided at a position away from the rotation center of the cam 27c. Furthermore, inside the intermediate transfer frame 25, there is a slider 34 that has a recess 34a at one end that engages with the cam 27c and is slidably supported by the intermediate transfer frame 25. The other end of the slider 34 is connected to the axis of the opposing roller 22 and There is a pressing portion 34b that slides between the axes of the assist roller 24.

[0046] When the control board 9 drives the separation coupling 27, the cam 27c rotates. As shown in Figure 10(a), when the convex portion 27c1 of the cam 27c is on the opposite side from the opposing roller 22, the concave portion 34a is engaged with the cam 27c, so the slider 34 is in a position where it is housed inside the intermediate transfer frame 25. At this time, the pressing portion 34b of the slider 34 is away from the contact surface 4a2 of the transfer bearing 4a, and the transfer roller 4 makes pressurized contact with the intermediate transfer belt 21 due to the spring force of the transfer spring 42. In this embodiment, this state is referred to as the contact state.

[0047] On the other hand, as shown in Figure 10(b), when the cam 27c rotates and the protrusion 27c1 moves toward the opposing roller, the pressing portion 34b of the slider 34 moves to a position where it protrudes from the intermediate transfer frame 25. At this time, the pressing portion 34b of the slider 34 contacts the contact surface 4a2 of the transfer bearing 4a, pushing the transfer roller 4 against the spring force of the transfer spring 42. As a result, the transfer roller 4, pushed together with the transfer bearing 4a by the pressing portion 34b, separates from the intermediate transfer belt 21. In this embodiment, this state is referred to as the separated state.

[0048] When the roller separation mechanism 45 is in the separated state, the transfer spring 42 is compressed more than in the contact state, thus generating a stronger spring force. In this state, if you try to close the opening / closing door 30, the operating force required to close the opening / closing door 30 will be greater than in the contact state.

[0049] Therefore, in this embodiment as well, in order to prevent the operating force of the opening / closing door 30 from changing depending on the state of the roller separation mechanism 45, the control board 9 moves the roller separation mechanism 45 to the contact state when it detects that the opening / closing door 30 has opened. Furthermore, if the roller separation mechanism 45 is in the contact state when the opening / closing door 30 is opened, it maintains that state. In this embodiment as well, the operating force required to close the opening / closing door 30 can be kept constant.

[0050] [Example 3] Examples 1 and 2 described a roller separation mechanism for the transfer roller 4. However, the roller separation mechanism is not limited to the transfer section. This example describes the operation when a roller separation mechanism is provided for a pair of register rollers. Explanations that overlap with Examples 1 and 2 are omitted.

[0051] Figures 11 and 12 show the configuration of the register roller pair 39 of this embodiment. The register roller pair 39 comprises a register bearing 36, a register spring 37, a register drive roller 39a, and a register driven roller 39b. The register drive roller 39a is a rotating body that is rotatably supported on the frame of the image forming apparatus A and rotates by receiving a driving force from the motor 55. The register bearing 36 is slidably supported on the opening / closing door 30. The register driven roller 39b is a rotating body that is rotatably supported on the register bearing 36 and rotates by contacting the register drive roller 39a. The register spring 37 biases the register bearing 36 toward the register drive roller between the register bearing 36 and the opening / closing door 30, thereby pressurizing the register driven roller 39b into contact with the register drive roller 39a with a predetermined pressure.

[0052] A separation cam 38 is rotatably supported on the rotation axis of the register drive roller 39a. The separation cam 38 is integrally configured with a gear (not shown) aligned in the direction of the rotation axis, and is capable of contacting and separating from the contact surface 36a of the register bearing 36. The gear meshes with a drive source different from the drive train of the register drive roller 39a, and the separation cam 38 can rotate independently of the register drive roller 39a. The roller separation mechanism 46 of this embodiment includes at least the separation cam 38 and the register bearing 36.

[0053] The roller separation mechanism 46 has a coaxial portion 38a of the separation cam 38 that contacts the contact surface 36a of the resistor bearing 36. The device can take on two states: a contact state where the two are facing each other (see Figure 11), and a separated state where the convex portion 38b of the separating cam 38 is in contact with the contact surface 36a of the resistor bearing 36 (see Figure 12).

[0054] In the contact state, the separation cam 38 and the register bearing 36 are separated, and the register drive roller 39a and the register driven roller 39b are in pressurized contact due to the pressure applied by the register spring 37. As a result, the register roller pair 39 can transport the recording material S by the rotational force of the register drive roller 39a and the pressure applied by the register driven roller 39b. Since the register drive roller 39a is positioned to receive pressure from the register driven roller 39b via the transport path 10, the register drive roller 39a can be called a receiving part located on the transport path 10.

[0055] Then, if a predetermined time has elapsed after an image forming operation and there is no instruction for the next image forming operation, the roller separation mechanism 46 rotates the separation cam 38 (arrow H1). The protrusion 38b then contacts the contact surface 36a of the resistor bearing 36, pushing the resistor bearing 36 in (arrow H2), and separating the resistor roller pair 39. In this state, the resistor driven roller 39b is separated from the resistor driven roller 39a, which prevents creep deformation and the like.

[0056] When the resistor spring 37 is separated, it is compressed more than when it is in contact, so the spring pressure is higher. Therefore, when the resistor roller pair 39 is separated, the operating force required to close the opening / closing door 30 is greater than when the resistor roller pair 39 is in contact.

[0057] Therefore, in this embodiment, in order to prevent the operating force required to close the opening / closing door 30 from changing depending on the state of the roller separation mechanism 46, the roller separation mechanism 46 is set to a contact state when the opening / closing door 30 is in the open state. To this end, when the control board 9 detects that the opening / closing door 30 has opened while the roller separation mechanism 46 is in the separated state, it transitions the roller separation mechanism 46 to a contact state, similar to embodiments 1 and 2. On the other hand, if the roller separation mechanism 46 is in a contact state when the opening / closing door 30 is open, no state transition is performed.

[0058] According to this embodiment, the operating force required to close the opening / closing door 30 can be kept constant. Therefore, it is possible to prevent situations where the user is unable to completely close the opening / closing door 30, and to prevent confusion for the user when they see the indicator that the door is open.

[0059] [Configuration 1] An image forming apparatus that forms an image on a recording material transported through a transport path, The device body having a receiving portion arranged in the aforementioned transport path, The device body is provided with an opening / closing section that can move between an open position where the transport path is exposed to the outside and a closed position where the transport path is covered. A roller provided in the opening / closing section, which is positioned in the transport path when the opening / closing section is closed, A pressurizing section is provided in the opening / closing section and pressurizes the roller, A separation portion provided on the main body of the apparatus, which is movable between a first position and a second position, and when in the first position, the roller is in contact with the receiving portion and the force of the pressurizing portion is received by the receiving portion, and when in the second position, the separation portion holds the roller in a position away from the receiving portion against the force, A switching device that can switch the position of the separated portion between the first position and the second position, A control unit that controls the switching device, An opening / closing detection unit for detecting the opening / closing state of the opening / closing part, It has, When it is detected that the separating portion is in the second position and the opening / closing portion is in the open position, the control unit moves the separating portion from the second position to the first position. Controlling the aforementioned switching device, An image forming apparatus characterized by the following: [Configuration 2] The receiving portion includes a rotating body that contacts the roller. The image forming apparatus according to configuration 1, characterized in that it is a picture forming apparatus. [Configuration 3] The rotating body is a transfer belt that can come into contact with the recording material. The receiving portion includes opposing rollers that contact the inner circumference of the transfer belt. When the opening / closing portion is in the closed position and the separating portion is in the first position, the roller is pressed toward the opposing roller by the pressurizing portion. The image forming apparatus according to configuration 2, characterized in that... [Structure 4] The rotating body is a conveying roller that can come into contact with the recording material. The image forming apparatus according to configuration 2, characterized in that... [Composition 5] The opening and closing section includes an opening and closing door and a frame section that opens and closes in conjunction with the opening and closing of the opening and closing door, and is provided with the roller and the pressurizing section. An image forming apparatus according to any one of configurations 1 to 4, characterized by the features described above. [Composition 6] The pressurizing section is provided in the opening / closing section and is a biasing means that biases the roller toward the receiving section. An image forming apparatus according to any one of configurations 1 to 5, characterized by the above. [Composition 7] When the opening / closing portion is in the closed position, the amount of deformation of the biasing means when the separating portion is in the second position and the roller is away from the receiving portion is greater than the amount of deformation of the biasing means when the separating portion is in the first position and the roller is in contact with the receiving portion. The image forming apparatus according to configuration 6, characterized by the features described therein. [Structure 8] The separation portion is a cam, and the switching device includes a drive source and a transmission member that transmits the driving force of the drive source to the separation portion. An image forming apparatus according to any one of configurations 1 to 7, characterized by the above. [Composition 9] The separation portion is a slider, and the switching device includes a drive source and a transmission member that transmits the driving force of the drive source to the separation portion. An image forming apparatus according to any one of configurations 1 to 7, characterized by the above. [Configuration 10] If the control unit detects that the opening / closing section has been closed and a predetermined time has elapsed without any image forming operation being performed, the control unit controls the switching device so that the separating section moves from the first position to the second position. An image forming apparatus according to any one of configurations 1 to 9, characterized by the features described above. [Composition 11] The opening / closing detection unit is a switch provided on the main body of the device that contacts a part of the opening / closing unit when the opening / closing unit is closed. An image forming apparatus according to any one of configurations 1 to 10, characterized by the above. [Composition 12] The control unit notifies the user when the opening / closing detection unit detects that the opening / closing unit is open. An image forming apparatus according to any one of configurations 1 to 11, characterized by the features described above. [Explanation of symbols]

[0060] 3: Resist roller pair, 4: Transfer roller, 9: Control board, 10: Transport path, 22: Opposing roller, 27a, 28b, 29: Gear, 28: Separation cam, 35: Door switch, 39: Resist roller pair, 42: Transfer spring, 55: Motor, A: Image forming apparatus, A1: Apparatus body

Claims

1. An image forming apparatus that forms an image on a recording material transported through a transport path, The device body having a receiving portion arranged in the aforementioned transport path, The device body is provided with an opening / closing section that can move between an open position where the transport path is exposed to the outside and a closed position where the transport path is covered. A roller provided in the opening / closing section, which is positioned in the transport path when the opening / closing section is closed, A pressurizing section is provided in the opening / closing section and pressurizes the roller, A separation portion provided on the main body of the apparatus, which is movable between a first position and a second position, and when in the first position, the roller is in contact with the receiving portion and the force of the pressurizing portion is received by the receiving portion, and when in the second position, the separation portion holds the roller in a position away from the receiving portion against the force, A switching device that can switch the position of the separated portion between the first position and the second position, A control unit that controls the switching device, An opening / closing detection unit for detecting the opening / closing state of the opening / closing part, It has, When it is detected that the separating portion is in the second position and the opening / closing portion is in the open position, the control unit controls the switching device so that the separating portion moves from the second position to the first position. An image forming apparatus characterized by the following features.

2. The receiving portion includes a rotating body that contacts the roller. The image forming apparatus according to feature 1.

3. The rotating body is a transfer belt that can come into contact with the recording material. The receiving portion includes opposing rollers that contact the inner circumference of the transfer belt. When the opening / closing portion is in the closed position and the separating portion is in the first position, the roller is pressed toward the opposing roller by the pressurizing portion. The image forming apparatus according to feature 2.

4. The rotating body is a conveying roller that can come into contact with the recording material. The image forming apparatus according to feature 2.

5. The opening and closing section includes an opening and closing door and a frame section that opens and closes in conjunction with the opening and closing of the opening and closing door, and is provided with the roller and the pressurizing section. The image forming apparatus according to any one of claims 1 to 4.

6. The pressurizing section is provided in the opening / closing section and is a biasing means that biases the roller toward the receiving section. The image forming apparatus according to any one of claims 1 to 4.

7. When the opening / closing portion is in the closed position, the amount of deformation of the biasing means when the separating portion is in the second position and the roller is away from the receiving portion is greater than the amount of deformation of the biasing means when the separating portion is in the first position and the roller is in contact with the receiving portion. The image forming apparatus according to feature 6.

8. The separation portion is a cam, and the switching device is a drive source and the driving force of the drive source Includes a transmission member that transmits to the separated portion. The image forming apparatus according to any one of claims 1 to 4.

9. The separation portion is a slider, and the switching device includes a drive source and a transmission member that transmits the driving force of the drive source to the separation portion. The image forming apparatus according to any one of claims 1 to 4.

10. If the control unit detects that the opening / closing section has been closed and a predetermined time has elapsed without any image forming operation being performed, the control unit controls the switching device so that the separating section moves from the first position to the second position. The image forming apparatus according to any one of claims 1 to 4.

11. The opening / closing detection unit is a switch provided on the main body of the device that contacts a part of the opening / closing unit when the opening / closing unit is closed. The image forming apparatus according to any one of claims 1 to 4.

12. The control unit notifies the user when the opening / closing detection unit detects that the opening / closing unit is open. The image forming apparatus according to any one of claims 1 to 4.

Images