Image forming apparatus

Abstract

To improve positional accuracy of a conveyance guide relative to a registration roller.SOLUTION: An image forming apparatus comprises: a registration roller pair 23 having a registration driven roller 23b, and a registration drive roller 23a that forms a nip for sandwiching a sheet with the registration driven roller 23b when an opening and closing door is at a closed position; a first conveyance guide 24b that is provided upstream of the registration roller pair 23 in a sheet conveyance direction, and is provided located relative to an apparatus body; a second conveyance guide 24a that is provided in a movable unit part, and faces the first conveyance guide 24b to guide the sheet with the first conveyance guide 24b to the registration roller pair 23 when the opening and closing door is at the closed position; and an abutting part 26 that is provided on the second conveyance guide 24a, and is pressed by the first conveyance guide 24b to locate the second conveyance guide 24a relative to the first conveyance guide 24b when the opening and closing door is at the closed position.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus for forming an image on a sheet. [Background technology]

[0002] Conventionally, as an electrophotographic image forming apparatus, one that transfers toner images of each color in a superimposed manner onto an intermediate transfer belt, and transfers the toner images carried on the intermediate transfer belt to a sheet, which is a recording material, all at once by a secondary transfer roller is known. In such an image forming apparatus, in order to facilitate jam removal by a user, one that is configured to be able to separate the secondary transfer roller from the intermediate transfer belt when removing a jam is widely used. Specifically, a rotatable opening and closing door is provided on the main body of the apparatus, and the secondary transfer roller and the intermediate transfer belt are separated in conjunction with the opening and closing of the opening and closing door. In addition, a configuration has been developed in which the secondary transfer roller is positioned relative to the main body of the apparatus so as to reduce the user's operating force when the secondary transfer roller contacts the intermediate transfer belt, and the visibility of the transport path is ensured in order to improve jam removal (see Patent Document 1).

[0003] On the other hand, by providing one of the pair of registration rollers on the side of the door and opening the nip of the pair of registration rollers in conjunction with the pivoting movement of the door, the visibility of the conveying path is improved. By making the pair of registration rollers separable, it is necessary to improve the positional accuracy of the pair of registration rollers relative to the device body when passing paper. For this reason, a locking member is provided directly on the device body, and the locking member is assisted (linked) by the opening and closing movement of the door to determine the position relative to the device body.

[0004] With this configuration, when the door is closed, the secondary transfer roller, intermediate transfer belt, and device body are precisely positioned by the locking mechanism. The registration roller pair, which has a locking mechanism independent of this configuration, is also positioned on the engine side, so the positional precision of the registration roller pair can be guaranteed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-227907 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the above-mentioned image forming apparatus, the conveying guide that guides the sheet to the registration roller pair is attached to the transfer unit that supports the secondary transfer roller. Therefore, the positional accuracy of the conveying guide depends on the secondary transfer roller and the intermediate transfer belt side. This makes it difficult to guarantee the relative position of the registration roller pair and the conveying guide, and there is a possibility that variations occur when guiding the sheet to the registration roller pair, and the accuracy of the registration function of the registration roller pair may decrease. In addition, the accuracy of guiding the sheet to the nip of the registration roller pair may decrease, and wrinkles may occur on the sheet. Furthermore, since the angle of the conveying guide may vary with respect to the registration roller pair, when the registration roller pair temporarily stops the sheet to generate a loop, there is a possibility that the size of the loop may vary. This may result in a decrease in the sheet variation registration performance, or conversely, the loop may become large and hit the conveying guide hard, deteriorating quietness.

[0007] SUMMARY OF THE DISCLOSURE An object of the present invention is to provide an image forming apparatus capable of improving the positional accuracy of a transport guide with respect to a pair of registration rollers. [Means for solving the problem]

[0008] One aspect of the present invention is a printing apparatus including: a main unit; an opening / closing unit that is rotatable about a rotation axis relative to the main unit and that is rotatable between a closed position in which a sheet transport path is formed and an open position in which the sheet transport path is open; a movable unit section that is movably attached to the opening / closing unit; an image forming section that forms an image on a sheet at an image forming position; a first roller provided in the main unit; a second roller that is provided in the movable unit section and that forms a nip between the first roller and the second roller when the opening / closing unit is located at the closed position; The image forming apparatus is characterized by comprising: a positioning section which positions the registration roller pair relative to the main unit; a first transport guide which is provided upstream of the registration roller pair in the sheet transport direction and positioned relative to the main unit; a second transport guide which is provided in the movable unit section and faces the first transport guide to guide the sheet to the registration roller pair between the first transport guide and the second transport guide; and a stop section which is provided on the second transport guide and is pressed against the first transport guide when the opening / closing unit is located in the closed position to position the second transport guide relative to the first transport guide. Effect of the Invention

[0009] According to the present invention, the positional accuracy of the transport guide with respect to the pair of registration rollers can be improved. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a front view showing the opening and closing door according to the first embodiment. [Diagram 3] FIG. 2 is a perspective view showing the opening and closing door according to the first embodiment. [Figure 4]FIG. 2 is a front view showing a state in which the opening and closing door according to the first embodiment is in an open position. [Diagram 5] 1A and 1B are perspective views showing a holding mechanism when the opening and closing door according to the first embodiment is in an open position, in which (a) shows a state in which the regulating member is lowered to the lowest position, and (b) shows a state in which the regulating member is slightly raised. [Figure 6] 1A and 1B are oblique views showing a holding mechanism when the opening and closing door in the first embodiment is near the closed position, in which (a) is the state just before being positioned at the closed position, and (b) is the state when positioned at the closed position. [Figure 7] FIG. 4 is a perspective view showing the rear side of the first transport guide according to the first embodiment. [Figure 8] FIG. 4 is a front view showing the pair of registration rollers when the opening / closing door according to the first embodiment is in a closed position. [Figure 9] FIG. 4 is a perspective view showing a second transport guide according to the first embodiment. [Figure 10] 5A and 5B are front views showing the registration roller pair and the conveying guide according to the first embodiment, where FIG. 5A shows the door in an open position, and FIG. 5B shows the door in a closed position. [Figure 11] 1A and 1B are front views of the opening / closing door according to the first embodiment when the door is in a closed position, where (a) shows a pair of registration rollers and (b) shows a conveying guide. [Figure 12] 5 is a cross-sectional view showing the sheet registration behavior by the pair of registration rollers when the opening and closing door according to the first embodiment is in a closed position. FIG. [Figure 13] FIG. 11 is a front view showing a state in which the opening and closing door according to the second embodiment is in a closed position. [Figure 14] FIG. 11 is a front view showing a state in which the opening and closing door according to the second embodiment is in an intermediate position. [Figure 15] FIG. 11 is a front view showing a state in which the opening and closing door according to the second embodiment is in an open position. [Figure 16] FIG. 11 is a cross-sectional view showing a pressing unit according to a second embodiment. [Figure 17] FIG. 11 is a front view showing the pressing unit when the opening and closing door is in the closed position according to the second embodiment. [Figure 18] FIG. 11 is a front view showing the pressing unit when the opening and closing door is in an intermediate position according to the second embodiment. [Figure 19] FIG. 11 is a front view showing the pressing unit when the opening and closing door is in the open position according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <First embodiment> A first embodiment of the present invention (disclosure) will be described in detail below with reference to Figs. 1 to 12. First, a schematic configuration of an image forming apparatus 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing a schematic configuration of the image forming apparatus 1 according to this embodiment. The image forming apparatus 1 is a tandem type intermediate transfer type laser beam printer that utilizes an electrophotographic process. The image forming apparatus 1 can form and output a full-color or monochrome image corresponding to print image data on a sheet S, which is a recording medium.

[0012] [Image forming equipment] The image forming apparatus 1 has an image forming unit 2 that forms an image on a sheet at a transfer nip 3, which is an example of an image forming position. The image forming unit 2 has process cartridges Py, Pm, Pc, and Pk corresponding to the colors of yellow (Y), magenta (M), cyan (C), and black (K). The process cartridges Py, Pm, Pc, and Pk of each color have the same configuration except for the color of the toner, so only the process cartridge Py for yellow (Y) will be described here, and descriptions of the other process cartridges Pm, Pc, and Pk will be omitted.

[0013] The process cartridge Py has a photosensitive drum 11, a charging roller 12, a developing unit 14, and a drum cleaner 15. After the surface of the photosensitive drum 11 is uniformly charged by the charging roller 12, an electrostatic latent image is formed on the photosensitive drum 11 by a laser scanner 13 driven based on a signal of transmitted image information. The electrostatic latent image is visualized as a toner image by the developing unit 14. The toner image on the photosensitive drum 11 is primarily transferred to an intermediate transfer belt 61 by a primary transfer roller 17 applying a predetermined pressure force and an electrostatic load bias. The intermediate transfer belt 61 is an example of an image carrier, and is positioned relative to the apparatus main body 1a to carry the toner image. After the transfer, a small amount of residual toner remaining on the photosensitive drum 11 is removed and collected by the drum cleaner 15, and is again prepared for the next image formation.

[0014] Meanwhile, the sheets S are fed one by one from the feeding cassette 20 and conveyed to the registration roller pair 23. The leading edge of the sheet S is made to follow the nip of the registration roller pair 23 to form a loop, thereby correcting the skew. Thereafter, the registration roller pair 23 conveys the sheet S between the transfer drive roller 62, which drives the intermediate transfer belt 61, and the secondary transfer outer roller 35 in synchronization with the toner image carried on the intermediate transfer belt 61. The secondary transfer outer roller 35 is integrally assembled to the secondary transfer unit 30 (see FIG. 2), which will be described later, and is separated from the intermediate transfer belt 61 and the transfer drive roller 62 when the opening and closing door 90 is opened and closed.

[0015] A predetermined pressure and electrostatic load bias are applied at the nip between the transfer drive roller 62 and the secondary transfer outer roller 35 disposed opposite to each other. As a result, the color toner image on the intermediate transfer belt 61 is secondarily transferred to the sheet S. After the transfer, the small amount of residual toner remaining on the intermediate transfer belt 61 is removed and collected by the belt cleaner 70, and is prepared for the next image formation. The toner image transferred onto the sheet S is fixed by the fixing device 40 through application of heat and pressure, and is discharged onto the discharge tray 50 by the discharge roller pair 41. Here, the intermediate transfer belt 61 and a plurality of tension rollers including the transfer drive roller 62 that tensions the intermediate transfer belt 61 are integrated into a unit to constitute the intermediate transfer unit 60.

[0016] That is, the image forming section 2 has an intermediate transfer belt 61 and a secondary outer transfer roller 35. The secondary outer transfer roller 35 is an example of a transfer member, and is provided in a secondary transfer unit 30 described later, and when an opening / closing door 90 is located at a closed position, the secondary outer transfer roller 35 comes into contact with the intermediate transfer belt 61 to form a transfer nip 3, which is an image forming position. The secondary outer transfer roller 35 transfers the toner image carried on the intermediate transfer belt 61 to the sheet S in the transfer nip 3.

[0017] [Opening and closing door] An opening / closing door 90 that can be opened and closed relative to the device main body 1a is formed on the right side of the image forming apparatus 1 in FIG. 1. The device main body 1a is an example of a main unit, and supports the opening / closing door 90 so as to be rotatable. The opening / closing door 90 of this embodiment has a rotation shaft 90a at its lower part and rotates around the rotation shaft 90a. A locking portion 90b is formed at the upper part of the opening / closing door 90, and the locking portion 90b is locked to a locked portion formed on the device main body 1a. The opening / closing door 90 is closed relative to the device main body 1a by being locked by the locking portion 90b. That is, the opening / closing door 90 is an example of an opening / closing unit, and is provided so as to be rotatable around the rotation shaft 90a relative to the device main body 1a, and is provided so as to be openable and closable by rotation between a closed position where a sheet transport path is formed and an open position where the sheet transport path is opened.

[0018] The relationship between the opening / closing door 90 and its surrounding parts will be described with reference to Figs. 2 and 3. Fig. 2 is a side view of the opening / closing door 90 in a closed state at the closed position, and Fig. 3 is an exploded perspective view of the opening / closing door 90 and its surroundings in the closed state. As shown in Fig. 2, the opening / closing door 90 rotates about a rotation shaft 90a and is an exterior member that forms part of the exterior of the apparatus main body 1a. As shown in Figs. 2 to 4, a unit holding part 91 is integrally provided inside the opening / closing door 90. The unit holding part 91 is provided with a movable unit part 4 that is attached movably relative to the opening / closing door 90. The movable unit part 4 has a secondary transfer unit 30 and a guide unit 22.

[0019] The secondary transfer unit 30 is an example of a transfer unit, has a secondary transfer outer roller 35, and is provided movable relative to the opening / closing door 90 when the opening / closing door 90 is in the open position. The unit holding portion 91 holds the secondary transfer unit 30 including the secondary transfer outer roller 35 at both longitudinal ends.

[0020] The unit holding part 91 is provided with an engagement mechanism for holding the secondary transfer unit 30. That is, a cylindrical upper regulating part 30a provided on the secondary transfer unit 30 engages with an upper regulating guide hole 91a provided on the upper part of the unit holding part 91. Meanwhile, a cylindrical lower regulating part 30b provided on the secondary transfer unit 30 engages with a lower regulating guide hole 91b provided on the lower part of the unit holding part 91. As shown in FIG. 3, the opening and closing door 90 has a floating spring 92 that urges the secondary transfer unit 30 toward the intermediate transfer unit 60. With this configuration, the secondary transfer unit 30 is held so as to be movable integrally with the unit holding part 91 provided on the opening and closing door 90 while being urged toward the intermediate transfer unit 60 by the floating spring 92.

[0021] [Secondary transfer unit] Next, the configuration around the secondary transfer unit 30 will be described with reference to Figs. 2 to 4. Fig. 4 is a side view showing the open state where the opening and closing door 90 is in the open position. A cylindrical positioning portion 30c is provided on the upper part of the secondary transfer unit 30 on the inside side of the device, i.e., on the intermediate transfer unit 60 side. In order to position and fix the positioning portion 30c to the device main body 1a, a transfer lock arm 104 is provided on the device main body 1a. The transfer lock arm 104 rotates around a rotation center 104a to lock the positioning portion 30c, thereby fixing the secondary transfer unit 30 in the closed state shown in Fig. 2.

[0022] In the secondary transfer unit 30, a fitting protrusion 30d for engaging with the device main body 1a is provided below the secondary transfer outer roller 35 and closer to the intermediate transfer unit 60 than the lower regulating portion 30b. As shown in Figures 2 and 4, a U-shaped fitting groove 101 for engaging with the fitting protrusion 30d is formed in the device main body 1a. The fitting protrusion 30d fits into the fitting groove 101, and the secondary transfer unit 30 is configured to be rotatable with respect to the device main body around the fitting protrusion 30d as a rotation center when the opening and closing door 90 is opened and closed.

[0023] That is, the secondary transfer unit 30 has a fitting protrusion 30d, which is an example of an axis portion whose central axis is in the width direction intersecting with the sheet conveying direction. The device main body 1a has a fitting groove 101, which is an example of a groove portion with which the fitting protrusion 30d engages. When the opening and closing door 90 rotates from the open position to the closed position, the fitting protrusion 30d engages with the fitting groove 101, and the secondary transfer unit 30 rotates around the fitting protrusion 30d and is positioned with respect to the device main body 1a. With this configuration, the secondary transfer unit 30 is positioned with respect to the image forming device 1.

[0024] That is, above the secondary transfer unit 30, the positioning portion 30c is positioned by the transfer lock arm 104, and below, the fitting protrusion 30d is positioned by the fitting groove 101. In this embodiment, the positioning portion 30c, the transfer lock arm 104, the fitting protrusion 30d, and the fitting groove 101 correspond to the second positioning portion 6. When the opening / closing door 90 is located in the closed position, the second positioning portion 6 positions the secondary transfer unit 30 with respect to the device main body 1a, thereby positioning the secondary transfer outer roller 35 with respect to the intermediate transfer belt 61.

[0025] In addition, when the secondary transfer unit 30 is in the closed state, it is also positioned with respect to the intermediate transfer unit 60. As shown in Fig. 4, a fitting groove 30e is formed so as to open to the intermediate transfer unit 60 side of the secondary transfer unit 30. Therefore, as shown in Fig. 2, when the opening and closing door 90 is closed, the positioning protrusion 60a formed on the intermediate transfer unit 60 fits into the fitting groove 30e of the secondary transfer unit 30, and the secondary transfer unit 30 is positioned with respect to the intermediate transfer unit 60.

[0026] [Registration roller pair positioning configuration] The secondary transfer unit 30 is provided with a registration roller holding portion 30f that holds a registration drive roller bearing 23c at a longitudinal end of one of the registration roller pairs 23, the registration drive roller 23a. The registration drive roller 23a is held so as to be rotatable relative to the secondary transfer unit 30 and movable in the rotation direction of the opening / closing door 90 and in the up-down direction. When the opening / closing door 90 is closed, the registration drive roller bearing 23c is positioned in the device body 1a by a U-shaped fitting groove 106 and a registration lock arm 105 provided in the device body 1a. A specific positioning configuration of the registration roller pair 23 will be described below.

[0027] First, the registration roller pair 23 has a registration drive roller 23a and a registration driven roller 23b, and conveys the sheet S toward the transfer nip 3. The registration driven roller 23b is an example of a first roller, and is provided in the apparatus main body 1a. The registration drive roller 23a is an example of a second roller, and is provided in the movable unit portion 4, and forms a nip 23n (see FIG. 8) that sandwiches the sheet S between the registration drive roller 23a and the registration driven roller 23b when the opening / closing door 90 is located at the closed position.

[0028] The positioning configuration of the registration roller pair 23 will be described with reference to Figs. 5(a) to 8. Figs. 5(a) and 5(b) are perspective views showing the holding mechanism when the opening / closing door 90 is in an open state. Figs. 6(a) and 6(b) are perspective views showing the holding mechanism when the opening / closing door 90 is in a closed state. Fig. 7 is a perspective view showing the rear side of the conveying surface of the first conveying guide 24b. Fig. 8 is a side view showing the registration roller pair 23 when the opening / closing door 90 is in a closed state.

[0029] As shown in Figures 5(a) and 5(b), the registration lock arm 105 is set to be freely rotatable around an arm rotation center 105a with respect to the apparatus main body 1a, and is attached by an arm engagement claw 105b provided on the apparatus main body 1a. When the opening and closing door 90 is open, the registration lock arm 105 abuts against an arm restriction portion 107, thereby determining the standby angle of the registration lock arm 105. In this embodiment, a configuration is adopted in which the registration lock arm 105 is biased toward the arm restriction portion 107 by its own weight. However, the present invention is not limited to this, and an elastic member that biases the registration lock arm 105 toward the arm restriction portion 107 may be provided.

[0030] The registration lock arm 105 has a cylindrical arm shaft 105c, and is set so that its posture is determined by abutting against a guide groove 108 provided on the opening / closing door 90 side. That is, when the opening / closing door 90 is open, the registration lock arm 105 abuts against an arm regulating portion 107 and enters a released state. From there, at a certain angle during the operation of closing the opening / closing door 90, the arm shaft 105c comes into contact with the guide groove 108, and the angle of the registration lock arm 105 changes to the lifting side, and when the opening / closing door 90 is closed from there, the registration lock arm 105 enters a locked state.

[0031] That is, the registration lock arm 105 has an arm shaft 105c, which is an example of a guided portion, and is provided rotatably with respect to the apparatus main body 1a. The guide groove 108 is an example of a guide portion, and when the opening / closing door 90 rotates from the open position to the closed position, it guides the arm shaft 105c to rotate the registration lock arm 105, which is located in the release position. Also, when the opening / closing door 90 is located in the closed position, it positions the registration lock arm 105 in the restricting position.

[0032] The registration lock arm 105 is provided with a registration roller holding portion 105d that restricts the registration drive roller bearing 23c to the opening / closing door 90 side in the above-mentioned locked state. During a series of opening and closing operations of the opening / closing door 90, the registration lock arm 105 rotates to embrace the registration drive roller bearing 23c from below, and the registration drive roller bearing 23c is restricted in the vertical direction by the U-shaped fitting groove 106. Thus, the registration drive roller 23a is restricted from moving in the vertical direction by the fitting groove 106, and restricted in the left-right direction by the registration roller holding portion 105d toward the opening / closing door 90 side, but is in a temporarily held state in which it can move toward the registration driven roller 23b side.

[0033] On the other hand, the registration driven roller 23b of the registration roller pair 23 is set so as to be restricted in the conveying direction side with respect to the first conveying guide 24b. On the other hand, it is movable in the nip direction of the registration roller pair 23 and is biased toward the opening and closing door 90 side by the pressing member 25. In this embodiment, the pressing force of the pressing member 25 is set as follows. The registration roller pair 23 having a registration function is not affected by other rollers when conveying a sheet, and when registering the sheet S, the leading edge of the sheet is stopped so that the leading edge of the sheet does not protrude from the nip 23n. To achieve this, in this embodiment, the pressing force is set to about 4000 gf. However, it is not limited to about 4000 gf and can be set appropriately depending on conditions such as the size of the loop and the type of sheet used.

[0034] That is, the registration drive roller 23a in the temporarily held state is pressed toward the opening and closing door 90 by the pressing member 25, so that the position of the registration drive roller 23a is positioned with high accuracy with respect to the apparatus main body 1a. As described above, the registration drive roller bearing 23c is restricted in the up and down direction by the fitting groove 106, and the registration drive roller 23a is pressed toward the registration roller holding portion 105d by the registration driven roller 23b, so that it is restricted in the nip direction. As a result, the position of the registration roller pair 23 is positioned with high accuracy with respect to the apparatus main body 1a.

[0035] The image forming apparatus 1 also has a first positioning section 5, which is an example of a positioning section that positions the registration roller pair 23 relative to the apparatus main body 1a when the opening / closing door 90 is located at the closed position. The first positioning section 5 has a registration lock arm 105 and a pressing member 25. The registration lock arm 105 is an example of a regulating member, is provided on the apparatus main body 1a, and is movable between a regulating position and a release position. As shown in FIG. 6(b), the regulating position is a position on the opposite side of the registration driven roller 23b across the registration driving roller 23a in the direction of a virtual line connecting the rotation centers of the registration driving roller 23a and the registration driven roller 23b when the opening / closing door 90 is located at the closed position. The release position is a position retracted from the regulating position. The pressing member 25 is an example of a second biasing section, which is provided on the registration driven roller 23b and biases the registration driven roller 23b toward the registration driving roller 23a.

[0036] When the opening / closing door 90 is in the closed position, the registration lock arm 105 is in the restricted position, and the pressing member 25 urges the registration driven roller 23b toward the registration drive roller 23a. Then, the registration drive roller bearing 23c of the registration drive roller 23a is brought into contact with the registration lock arm 105, and the registration roller pair 23 is positioned relative to the apparatus body 1a. When the opening / closing door 90 is in the open position, the registration lock arm 105 is in the released position, and the positioning of the registration drive roller 23a is released.

[0037] [Guide unit positioning configuration] The positioning configuration of the guide unit 22 will be described with reference to Figs. 9 to 12. Fig. 9 is a perspective view showing the second transport guide 24a. Figs. 10(a) and 10(b) are side views showing the registration roller pair 23 and the transport guide when the opening / closing door 90 is open. Figs. 11(a) and 11(b) are side views showing the registration roller pair 23 and the transport guide when the opening / closing door 90 is open. Fig. 12 is a side view showing the sheet registration behavior of the registration roller pair 23 and the transport guide.

[0038] The guide unit 22 is provided so as to be movable relative to the secondary transfer unit 30 when the opening / closing door 90 is located at the open position. The guide unit 22 has a registration drive roller 23a, a registration drive roller bearing 23c, a second transport guide 24a that is rotatable about the registration drive roller 23a as a rotation center, and an abutment portion 26 provided at an end of the second transport guide 24a in the longitudinal direction.

[0039] The registration roller holding portion 30f and the regulating portion 27 are provided at the bottom of the secondary transfer unit 30. That is, the first conveying guide 24b is provided upstream of the registration roller pair 23 in the sheet conveying direction, and is positioned relative to the device main body 1a. The second conveying guide 24a is provided in the movable unit portion 4, and when the opening and closing door 90 is located at the closed position, the second conveying guide 24a faces the first conveying guide 24b and guides the sheet S to the registration roller pair 23 between the first conveying guide 24b and the second conveying guide 24a. The abutting portion 26 is provided in the second conveying guide 24a, and when the opening and closing door 90 is located at the closed position, the abutting portion 26 is pressed by the first conveying guide 24b to position the second conveying guide 24a relative to the first conveying guide 24b. In this embodiment, the second conveying guide 24a is supported by the rotation shaft of the registration driving roller 23a, and the registration driving roller 23a is rotatable relative to the second conveying guide 24a. This improves the accuracy of positioning the registration roller pair 23 and the second transport guide 24a. Also, compared to a configuration in which the second transport guide 24a is attached to the secondary transfer unit 30, the position accuracy of the second transport guide 24a relative to the registration roller pair 23 can be improved.

[0040] The guide unit 22 is held by the registration roller holding portion 30f when the opening / closing door 90 is open, and is set to be movable within that range. In addition, at the rotatable angle, the regulating portion 27 abuts against the protrusions 28a and 28b provided in the rotation direction of the secondary transfer unit 30, and is regulated, but is set to be rotatable within that range. Although it is rotatable, the regulating portion 27 is maintained in a state in which it is always in contact with the protrusion 28b side by the pressing portion 28 described later. The protrusions 28a and 28b are an example of abutted portions, and the regulating portion 27 abuts against the rotation direction of the guide unit 22 to regulate the rotation range of the guide unit 22. Here, if the protrusions 28a and 28b are not provided, as an example of an extreme behavior, the opening / closing door 90 may be located in the closed position when the guide unit 22 is rotated 180 degrees, and the guide unit 22 may be positioned in a posture different from the design. In contrast, in this embodiment, the protrusions 28a and 28b are provided to restrict the rotation angle, so that such a risk can be eliminated.

[0041] When the opening / closing door 90 is closed, the vertical direction is restricted by the U-shaped fitting groove 106, similar to the above-mentioned movement in which the registration drive roller 23a is positioned relative to the apparatus body 1a. The left-right direction is determined by the registration roller holding portion 105d and the registration driven roller 23b, so that the second transport guide 24b is positioned relative to the apparatus body 1a. Then, the abutting portion 26 provided on the second transport guide 24a abuts against the first transport guide 24b, and is biased by the pressing portion 28 provided on the opening / closing door 90, so that the positioning angle of the guide unit 22 relative to the apparatus body 1a is determined.

[0042] The pressing portion 28 is an example of a first biasing portion, and is provided on the opening / closing door 90. When the opening / closing door 90 is in the closed position, the pressing portion 28 biases the second transport guide 24a toward the first transport guide 24b, and the abutting portion 26 abuts against and presses the first transport guide 24b. In this embodiment, the abutting portion 26 directly abuts against and presses the first transport guide 24b, but this is not limited to this. For example, the abutting portion 26 may be abutted against a frame of the device main body 1a. In this case, the abutting portion 26 indirectly abuts against the first transport guide 24b.

[0043] 12, when the sheet S is registered, it creates a loop and hits the first conveying guide 24b, pushing the guide unit 22 towards the opening and closing door 90. For this reason, it is necessary to set the pressing force of the pressing part 28 so that it is not smaller than the force pressed by the loop. In this embodiment, it is set to about 1000 gf. However, it is not limited to about 1000 gf, and can be set appropriately depending on conditions such as the size of the loop and the type of sheet used.

[0044] In this embodiment, the secondary transfer unit 30 has a regulating portion 27, and the guide unit 22 has protrusions 28a and 28b. However, this is not limited to the above, and the secondary transfer unit 30 may have two paired protrusions, and the guide unit 22 may have a regulating portion that is movable between the two protrusions. That is, one of the secondary transfer unit 30 and the guide unit 22 has a contact portion, and the other has a contacted portion.

[0045] As described above, according to the image forming apparatus 1 of the present embodiment, when the opening / closing door 90 is in the closed position, the abutting portion 26 positions the second transport guide 24a with respect to the first transport guide 24b. This makes it possible to improve the positioning accuracy of the second transport guide 24a with respect to the registration roller pair 23, compared to a configuration in which the second transport guide 24a is attached to the secondary transfer unit 30.

[0046] In addition, the registration drive roller 23a is positioned by the registration lock arm 105, the registration roller holding portion 30f, and the registration driven roller 23b, and the position of the second conveying guide 24a is determined by the abutting portion 26 coming into contact with the first conveying guide 24b. This allows the position of the guide unit 22 relative to the apparatus main body 1a to be highly accurate. Therefore, the sheet conveying path of the registration roller pair 23 is opened in conjunction with the opening operation of the opening / closing door 90, and it is possible to provide an image forming apparatus 1 equipped with the registration roller pair 23 that has good visibility even when a sheet jam occurs and can convey a sheet with high accuracy.

[0047] Furthermore, according to the image forming apparatus 1 of this embodiment, the second transport guide 24a is supported by the rotation shaft of the registration drive roller 23a, and the registration drive roller 23a is rotatable relative to the second transport guide 24a. Therefore, the second transport guide 24a becomes a transport guide that rotates around the registration drive roller 23a without degrading jamming performance. This improves the positional accuracy of the second transport guide 24a and the first transport guide 24b relative to the registration roller pair 23, and provides an image forming apparatus 1 that can improve the accuracy of the registration function of the registration roller pair 23.

[0048] In the above embodiment, the image forming apparatus 1 is applied to an electrophotographic printer, but the present invention is not limited to this and may be applied to an inkjet printer. In this case, the present invention may be applied to a registration roller pair for a recording unit, which is an image forming unit, and a conveying guide in the upstream vicinity thereof.

[0049] <Second embodiment> Next, a second embodiment of the present invention will be described in detail with reference to Fig. 13 to Fig. 19. This embodiment is different from the first embodiment in that the relative position of the pressing unit 29 capable of pressing the second transport guide 24a with respect to the second transport guide 24a changes depending on the position of the opening and closing door 90. However, other configurations are the same as those of the first embodiment, so the same reference numerals are used and detailed description will be omitted.

[0050] When the configuration described in Patent Document 1 is adopted, the movement of the sheet conveying guide relative to the opening and closing door when the opening and closing door is opened and closed due to jam processing or attachment and detachment of parts does not regulate the protruding amount relationship to the upstream conveying guide to the conveying path. Therefore, if the protruding amount to the upstream guide is reversed, there is a risk of a jam. In order to avoid a jam due to the reversal of the protruding amount, the shape of the moving guide may become complex, or the structure may become weak in strength near the transfer part with the upstream guide, and it is necessary to move on a trajectory that assumes that the conveying roller and the conveying guide will dynamically contact each other. Therefore, there is a concern that the desired conveying path space cannot be obtained due to the deformation of the guide, or that the conveying roller will be scratched. On the other hand, even when regulating the moving area to avoid the above-mentioned problems or adding a member to maintain the shape of the part that carries the conveying path, a simple one is desired from the viewpoint of arrangement space and cost. Therefore, in this embodiment, a movement trajectory of the conveying guide member is established to ensure conveying performance with space saving and low cost.

[0051] The movement of each unit during the opening and closing operation of the opening / closing door 90 will be described with reference to Figs. 13 to 16. Fig. 13 is an explanatory diagram of the closed position (paper passing state, standby state) of the opening / closing door 90 according to this embodiment, Fig. 14 is an explanatory diagram of the intermediate position (jam clearing position) of the opening / closing door, and Fig. 15 is an explanatory diagram of the open position (parts replacement position) of the opening / closing door 90. The opening / closing door 90 mainly moves arbitrarily among three positions: the closed position, the intermediate position, and the open position. The closed position is a position where the opening / closing door 90 is stored in the image forming apparatus 1 (paper passing state, standby state). The intermediate position is a position between the closed position and the open position, and is a position (jam clearing position) where an operator clears sheet jams and the like. The open position is a position (parts replacement position) where an operator replaces parts and the like.

[0052] During the moving operation, the secondary transfer unit 30 is movable relative to the opening / closing door 90 by a floating spring 92. In each of the three positions, the relative positions of the opening / closing door 90, the secondary transfer unit 30, the guide unit 22, and the pre-registration guide 36, which is fixed to the opening / closing door 90 and located upstream of the guide unit 22, are different. The pre-registration guide 36 is fixed to the opening / closing door 90, for example. The pre-registration guide 36 is an example of a third conveying guide, and is provided upstream of the second conveying guide 24a in the sheet conveying direction, and is provided on the opening / closing door 90. In this embodiment, a pressing unit 29, which will be described later, is provided on the pre-registration guide 36.

[0053] As shown in Fig. 13, when the opening / closing door 90 is in the closed position, the amount of protrusion of the transfer portion between the guide unit 22 and the pre-registration guide 36 from the transport path must be greater for the pre-registration guide 36 in order to avoid jamming. As shown in Fig. 14, when the opening / closing door 90 is in a position during opening / closing operation (intermediate position), the amount of protrusion of the transfer portion between the guide unit 22 and the pre-registration guide 36 from the transport path must be greater for the guide unit 22 in order to realize the positional relationship required for the closed state. As shown in Fig. 15, when the opening / closing door 90 is in the open position, it is desirable for the guide unit 22 and the pre-registration guide 36 to retract in order to improve workability.

[0054] [Press unit configuration] Next, the configuration near the pressing unit 29 will be described with reference to Figs. 16 to 19. Fig. 16 is a diagram showing the configuration of the pressing unit 29. Fig. 17 is a cross-sectional view showing the relationship between the guide unit 22 and the pressing unit 29 when the opening / closing door 90 is in the closed position. Fig. 18 is a cross-sectional view showing the relationship between the guide unit 22 and the pressing unit 29 when the opening / closing door 90 is in the intermediate position. Fig. 19 is a cross-sectional view showing the relationship between the guide unit 22 and the pressing unit 29 when the opening / closing door 90 is in the open position. In this embodiment, the pressing unit 29 is an example of a first biasing portion.

[0055] 16, the pressing unit 29 has a pressing portion 31, a biasing spring 32, and a slide guide member 33. The pressing portion 31 has a guide pressing surface 31a and a spring seat surface 31b. The pressing portion 31 is supported by slide guide portions 33a and 33b of the fixed member, or by a biasing spring 32 having a diameter sufficiently larger than that of the pressing portion 31, or by both, so as to be held from tilting. This allows the pressing unit 29 to perform its function with a desired pressure force even when it has both a pressing function and a guiding function.

[0056] As shown in FIG. 17, in order to realize a desired transport path space when the opening / closing door 90 is closed, the pressing unit 29 plays a role of abutting the second transport guide 24a against the first transport guide 24b via the guide unit 22 to determine the posture. Here, the opposing member against which the second transport guide 24a abuts may not be a transport guide, but may be a main body frame or a fixed member for positioning. This allows the postures of the second transport guide 24a and the guide unit 22 when the opening / closing door 90 is closed to be determined uniformly without being affected by position changes that occur each time the opening / closing door 90 is opened or closed. Therefore, the relationship of the protruding amount of the second transport guide 24a and the pre-registration guide 36 in the direction approximately normal to the transport path is also determined uniformly, so that the desired transport path can be formed.

[0057] In the transition state between the closed state and the open position of the opening / closing door 90, in other words, in the state in which the opening / closing door 90 is in the opening / closing operation, the pressing unit 29 restricts the movement area of ​​the guide unit 22. FIG. 18 shows the state in which the opening / closing door 90 is in the intermediate position as a part of the opening / closing operation. During the opening / closing operation, the second transport guide 24a freely rotates about the registration drive roller 23a that is integral with the second transport guide 24a. Therefore, it is difficult to control the positional relationship with the pre-registration guide 36 upstream of the transport path.

[0058] To solve this problem, the pressing unit 29 presses a part of the movable guide unit 22. This guides the guide unit 22 to move along a path that maintains a relationship in which the amount of protrusion of the second transport guide 24a at the transfer portion between the second transport guide 24a and the pre-registration guide 36 is greater than that of the second transport guide 24a. This makes it possible to prevent the guide unit 22 from accidentally colliding with the registration drive roller 23a or the pre-registration guide 36 during movement.

[0059] 19, when the opening / closing door 90 is in the open position, the pressing unit 29 is separated from the second transport guide 24a. This positional relationship increases the amount of retraction of the guide unit 22 when the opening / closing door 90 is in the open position, which is expected to improve the workability when clearing jams or replacing parts.

[0060] In this embodiment, the second transport guide 24a is movable in a direction intersecting the biasing direction of the pressing unit 29. When the opening / closing door 90 is located in a range from the closed position to the intermediate position, the second transport guide 24a is in a position overlapping with the biasing direction of the pressing unit 29, and the second transport guide 24a is biased by the pressing unit 29 (see FIGS. 17 and 18). When the opening / closing door 90 is located in the open position, the second transport guide 24a moves to a position not overlapping with the biasing direction of the pressing unit 29 (see FIG. 19).

[0061] In the state shown in Fig. 18, the weight of the secondary transfer unit 30 connected to the second transport guide 24a urges the second transport guide 24a to the left, and if no external force acts, the state will be as shown in Fig. 17. On the other hand, when the opening and closing door 90 is opened slightly from the state shown in Fig. 18 and the second transport guide 24a moves away from the pressing unit 29, the weight of the secondary transfer unit 30 urges the second transport guide 24a to the right, and if no external force acts, the state will be as shown in Fig. 19.

[0062] As described above, according to the image forming apparatus 1 of the present embodiment, the trajectory guidance of the second transport guide 24a and the pressure for maintaining the posture can be performed by a single pressing unit 29. Therefore, the establishment of the movement trajectory of the second transport guide 24a for ensuring the transport performance and the pressure for maintaining the posture can be realized in a space-saving and low-cost manner. In addition, since the above-mentioned effects can be obtained by using the pressing unit 29 having the pressing function and the guiding function of the second transport guide 24a, it is possible to provide an image forming apparatus 1 that ensures the transport performance and the ease of operation when clearing jams or replacing parts.

[0063] Furthermore, according to the image forming apparatus 1 of this embodiment, when the opening / closing door 90 is placed in the open position, the second transport guide 24a moves away from the pressing unit 29, so that the second transport guide 24a is not pushed upward and moves down by its own weight. This allows the second transport guide 24a to not get in the way during maintenance such as replacing the intermediate transfer belt 61, improving workability. When the opening / closing door 90 is closed, the second transport guide 24a protrudes once from the pre-registration guide 36 and then moves away from the sheet transport path from the pre-registration guide 36. This allows smooth transport of the sheet when the opening / closing door 90 is closed. [Explanation of symbols]

[0064] 1...image forming apparatus, 1a...apparatus main body (main unit), 2...image forming section, 3...transfer nip, 4...movable unit section, 5...positioning section (first positioning section), 6...second positioning section, 22...guide unit, 23...pair of registration rollers, 23a...registration drive roller (second roller), 23b...registration driven roller (first roller), 23n...nip, 24a...second conveying guide, 24b...first conveying guide, 25...pressing member (second biasing section), 26...butting section, 27...regulating section ( abutting portion), 28...pressing portion (first urging portion), 28a, 28b...projecting portion (contacted portion), 29...pressing unit (first urging portion), 30...secondary transfer unit (transfer unit), 30d...engaging projection (shaft portion), 35...secondary transfer outer roller (transfer member), 36...pre-registration guide (third conveying guide), 61...intermediate transfer belt (image carrier), 90...opening / closing door (opening / closing unit), 105...registration lock arm (regulating member), 105c...arm shaft (guided portion), 108...guide groove (guiding portion), S...sheet

Claims

1. A main unit; an opening / closing unit that is rotatably provided around a rotation axis with respect to the main unit and that is openable and closable by rotation between a closed position where a sheet transport path is formed and an open position where the sheet transport path is opened; A movable unit portion movably attached to the opening / closing unit; an image forming section that forms an image on a sheet at an image forming position; a registration roller pair including a first roller provided in the main unit and a second roller provided in the movable unit portion and forming a nip between the first roller and the second roller when the opening / closing unit is located at the closed position, the registration roller pair conveying the sheet toward the image forming position; a positioning unit that positions the registration roller pair with respect to the main unit when the opening / closing unit is located at the closed position; a first conveying guide provided upstream of the pair of registration rollers in a sheet conveying direction and positioned relative to the main unit; a second conveying guide provided in the movable unit portion, facing the first conveying guide and guiding a sheet to the pair of registration rollers between the first conveying guide and the second conveying guide when the opening / closing unit is located at the closed position; a stopper portion provided on the second transport guide and configured to position the second transport guide relative to the first transport guide by being pressed against the first transport guide when the opening / closing unit is located at the closed position; 1. An image forming apparatus comprising:

2. the second conveying guide is supported by a rotation shaft of the second roller, The second roller is rotatable relative to the second transport guide.

2. The image forming apparatus according to claim 1,

3. a first biasing portion that is provided in the opening / closing unit and biases the second transport guide toward the first transport guide when the opening / closing unit is located at the closed position, and causes the abutment portion to abut against and press the first transport guide; 2. The image forming apparatus according to claim 1,

4. the second conveying guide is movable in a direction intersecting a biasing direction of the first biasing portion, When the opening / closing unit is located in a range from the closed position to an intermediate position between the open position and the closed position, the second transport guide is in a position overlapping with the biasing direction of the first biasing portion, and the second transport guide is biased by the first biasing portion, When the opening / closing unit is located at the open position, the second transport guide moves to a position where it does not overlap with the first biasing portion in the biasing direction.

4. The image forming apparatus according to claim 3.

5. a third conveying guide provided on the opening / closing unit and disposed upstream of the second conveying guide in the sheet conveying direction; the first biasing portion is provided on the third transport guide, 5. The image forming apparatus according to claim 4.

6. the positioning portion is a first positioning portion, The image forming unit includes: an image carrier that is positioned relative to the main unit and that carries a toner image; a transfer member that is provided in the movable unit portion, and that contacts the image carrier to form a transfer nip that is the image forming position when the opening / closing unit is located at the closed position, and transfers a toner image carried on the image carrier to a sheet at the transfer nip, a second positioning portion that positions the transfer member with respect to the image carrier when the opening / closing unit is located at the closed position; 2. The image forming apparatus according to claim 1,

7. The movable unit portion is a transfer unit having the transfer member and movable relative to the opening / closing unit when the opening / closing unit is located at the open position; a guide unit including the second roller and the second transport guide, the guide unit being movable relative to the transfer unit when the opening / closing unit is located at the open position; the second positioning portion positions the transfer unit with respect to the main unit when the opening / closing unit is located at the closed position, thereby positioning the transfer member with respect to the image carrier.

7. The image forming apparatus according to claim 6,

8. the transfer unit has a shaft portion whose central axis is in a width direction intersecting a sheet conveying direction, The main unit has a groove with which the shaft portion engages, When the opening / closing unit rotates from the open position to the closed position, the shaft portion engages with the groove portion, and the transfer unit rotates around the shaft portion to be positioned relative to the main unit.

8. The image forming apparatus according to claim 7,

9. one of the transfer unit and the guide unit has a contact portion, the other of the transfer unit and the guide unit has a contacted portion that restricts a rotation range of the guide unit by contacting the contact portion in a rotation direction of the guide unit; 8. The image forming apparatus according to claim 7,

10. The positioning portion is a restricting member provided in the main unit and movable between a restricting position located on the opposite side of the first roller with respect to the second roller in a direction of an imaginary line connecting rotation centers of the first roller and the second roller when the opening / closing unit is located at the closed position, and a release position retracted from the restricting position; a second biasing portion provided in the main unit and configured to bias the first roller toward the second roller, When the opening / closing unit is located at the closed position, the regulating member is located at the regulating position, and the second urging portion urges the first roller toward the second roller to bring the rotation shaft of the second roller into contact with the regulating member, thereby positioning the registration roller pair with respect to the main unit, When the opening / closing unit is located at the open position, the regulating member is located at the release position, and the positioning of the second roller is released.

2. The image forming apparatus according to claim 1,

11. The regulating member has a guided portion and is rotatably provided with respect to the main unit. The opening / closing unit has a guide portion that guides the guided portion to rotate the regulating member located at the release position when the opening / closing unit rotates from the open position to the closed position, and that positions the regulating member at the regulating position when the opening / closing unit is located at the closed position.

11. The image forming apparatus according to claim 10.

Images