Sheet conveyance device and image formation apparatus

Abstract

To provide a sheet conveyance device and an image formation apparatus in which generation of half-closing of an opening / closing member can be suppressed.SOLUTION: An opening / closing cover as an opening / closing member in which a lower end part is rotatably supported on a device body, and which opens / closes a sheet conveyance passage is provided with: pressure rollers as pressure members which pressurize a conveyance roller as a member to be pressurized in the device body; and a hook member which is engaged with an engagement shaft as an engagement member of the device body and holds the opening / closing cover at a closed position. Further, the opening / closing cover comprises adjustment members 30 as adjustment means which adjust at least one of the pressure force of the pressure rollers 4 and the protrusion amount of the pressure members to a cover side guide part as a peripheral member.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to a sheet conveying device and an image forming apparatus. [Background technology]

[0002] Conventionally, there has been known a sheet transport device that includes an opening / closing member whose lower end is rotatably supported on the device body and that opens and closes a sheet transport path, a pressure member provided on the opening / closing member that presses a pressure-receiving member on the device body, and a hook member that engages with an engaging member on the device body and holds the opening / closing member in a closed position.

[0003] Patent Document 1 describes a sheet conveying device that includes a cover member that is rotatably supported on the device body with its lower end as a fulcrum and serves as an opening / closing member that opens and closes a reverse conveying path that is a sheet conveying path. The cover member is biased in the closing direction of the cover member by a compression coil spring and includes a second conveying roller that serves as a pressure member that is in pressure contact with a first conveying roller that is a pressure-receiving member of the device body when the cover member is closed. In addition, the cover member has a hook member at its upper portion that engages with an engagement member provided on the device body to hold the cover member in a closed state. Summary of the Invention [Problem to be solved by the invention]

[0004] However, depending on the configuration of the hook member and the engaging member, there is a risk that the opening and closing member serving as the cover member may be held in an unclosed state, that is, so-called half-closed state. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a sheet transport device comprising an opening / closing member whose lower end is rotatably supported on the device main body and which opens and closes a sheet transport path, a pressure member provided on the opening / closing member which presses a pressurized member of the device main body, and a hook member which engages with an engaging member of the device main body and holds the opening / closing member in a closed position, the sheet transport device further comprising a biasing member which biases the hook member so as to maintain engagement with the engaging member, the hook member is configured to slide against the engaging member and rotate against the biasing force of the biasing member to overcome the engaging member and engage with the engaging member, and further comprising an adjustment means for adjusting at least one of the pressure force of the pressure member and the amount of protrusion of the pressure member relative to the surrounding members. Effect of the Invention

[0006] According to the present invention, it is possible to prevent the opening / closing member from becoming half-closed. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a front view of the image forming apparatus according to the embodiment. [Diagram 2] FIG. 1 is a schematic diagram illustrating an internal structure of an image forming apparatus. [Diagram 3] FIG. [Figure 4] FIG. 4 is a diagram showing the vicinity of the paper feed unit with the access cover open. [Diagram 5] FIG. 4 is a schematic diagram showing the configuration when the opening / closing cover is closed. [Figure 6] FIG. 4 is a schematic diagram showing the configuration when the opening / closing cover is open. [Figure 7] 13 is a schematic perspective view showing a mechanism for releasing the engagement between the hook member and the engagement shaft. FIG. [Figure 8] FIG. [Figure 9] 11A to 11C are diagrams illustrating disengagement between the hook member and the engagement shaft. [Figure 10] 6A to 6C are diagrams illustrating engagement between a hook member and an engagement shaft. [Figure 11]11A and 11B are diagrams illustrating the relationship of forces acting on a contact point between a lower end of a hook member and an engagement shaft when the opening / closing cover is closed. [Figure 12] FIG. [Figure 13] 5A and 5B are diagrams illustrating adjustment of the protrusion amount of the pressure roller by an adjustment member. [Figure 14] 13 is a graph showing the relationship between an adjustment force F4 acting on a contact point between a lower end of the hook member and an engagement shaft, a difference value F12 between a closing force F2 and an opening force F1, and a holding force F3. [Figure 15] 13A and 13B are diagrams illustrating adjustment of the protrusion amount by the adjustment member when half-closed occurs. [Figure 16] FIG. 6 is a flow diagram of position adjustment control of the adjustment member. [Figure 17] 13 is a schematic perspective view showing a configuration in which an adjustment member on one axial side and an adjustment member on the other axial side are connected by a connecting member. FIG. [Figure 18] 10A and 10B are diagrams showing an example of an adjustment flow in which an adjustment member is moved in a vertical direction by a driving device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The best mode for carrying out the present invention will be described below with reference to the drawings. Note that a person skilled in the art can easily modify and alter the present invention within the scope of the claims to create other embodiments, and these modifications and alterations are included in the scope of the claims. The following description is an example of the best mode for carrying out the present invention, and does not limit the scope of the claims.

[0009] FIG. 1 is a front view of an image forming apparatus 101 according to this embodiment. 1, the image forming apparatus 101 has an image forming section 107, a paper feed section 110 arranged below the image forming section 107, and an image reading device 140 arranged above the image forming section 107. The image forming apparatus 101 also has an operation display section 130 that displays and performs operations for an operator to operate when performing image formation using the image forming apparatus 101. As indicated by the arrow in the figure, paper fed from paper feed unit 110 is transported vertically upward, an image is formed on the paper by image forming unit 107, and the paper is then discharged to paper discharge unit 109.

[0010] FIG. 2 is a schematic diagram showing the internal structure of the image forming apparatus 101. As shown in FIG. The paper feed section 110 is equipped with four paper feed cassettes 103 as sheet stacking sections that are detachable from the device body, each of which stores a different type of paper 102. The paper 102 stacked in the paper feed cassette 103 is fed from the paper feed cassette 103 by a paper feed roller 111a, separated into sheets by a pair of separation rollers 111b, and then fed to a conveying path 112 that extends in a substantially up-down (vertical) direction to a paper discharge section 109.

[0011] A manual feed tray 104 serving as a sheet stacking section is disposed on the right side of the apparatus main body in the figure. Paper 102 stacked on the manual feed tray is fed to a conveying path 112 by a manual paper feed device 105 .

[0012] The image forming section 107 has a photoconductor 115 as an image carrier. A charging device, a developing device, a transfer roller 113, a cleaning unit, and the like are arranged around the photoconductor 115. The charging device uniformly charges the photoconductor 115, and the developing device applies toner to the electrostatic latent image on the photoconductor 115 to make it visible. The transfer roller 113 transfers the toner image formed by the developing device onto the transported paper 102. The cleaning unit cleans the photoconductor 115 by removing toner and the like remaining on the photoconductor 115 after transfer.

[0013] Image forming unit 107 also has an optical writing device that forms an electrostatic latent image on photoconductor 115. The optical writing device exposes the surface of photoconductor 115 to laser light and performs optical writing based on image data from image reading device 140 or image information input from a personal computer or the like, thereby forming an electrostatic latent image on the surface of photoconductor 115.

[0014] In addition, the image forming unit 107 is disposed downstream of the transfer roller 113 in the paper transport direction, and has a fixing device 114 that heats and pressurizes the toner image transferred to the paper 102 by the transfer roller 113 to fix it to the paper 102.

[0015] Paper 102 is selectively fed from upper and lower paper feed cassettes 103 and manual feed tray 104, and conveyed through conveyance path 112. Paper 102 conveyed to conveyance path 112 is temporarily stopped at registration roller pair 106 provided upstream of transfer roller 113 in the paper conveyance direction, and the paper's posture is corrected. Then, at a predetermined timing, the paper is sent by registration roller pair 106 to a transfer nip portion between transfer roller 113 and photoconductor 115. Then, a toner image is transferred from photoconductor 115 to paper 102 at the transfer nip portion.

[0016] The paper 102 onto which the toner image has been transferred in the transfer nip is transported to a fixing device 114, where the toner image is fixed to the paper 102 by heat and pressure, and the paper is then discharged by a pair of discharge rollers 116 to a paper discharge section 109 provided outside the device.

[0017] In the image forming apparatus 101 of this embodiment, double-sided printing is also possible. In this case, after a toner image is fixed on the front side of the paper 102, the conveying path is switched by a branch claw 117 and the paper 102 is conveyed to the reversing roller pair 118 side.

[0018] The pair of reversing rollers 118 rotates in the reverse direction after partially discharging the sheet 102 onto the reversing tray 119, and sends the sheet 102 to the double-sided conveying path 120. The sheet 102 sent to the double-sided conveying path 120 is conveyed again to the position of the pair of registration rollers 106 in a reversed state.

[0019] Then, a toner image is transferred from a photoconductor 115 to the back side of the paper 102 sent from a pair of registration rollers 106 to the transfer nip section, and the toner image is then fixed to the paper 102 by a fixing device 114, and the paper is discharged to a paper discharge section 109 by a pair of paper discharge rollers 116.

[0020] FIG. 3 is a perspective view of the image forming apparatus 101. As shown in FIG. As shown in Fig. 3, an opening / closing member, an opening / closing cover 10, is provided on the side of image forming apparatus 101 on which manual tray 104 is provided so as to be freely opened and closed. By operating handle 20, opening / closing cover 10 is opened as shown in Fig. 4, and the paper transport path of paper feeder 110 is exposed, allowing paper 102 jammed in paper feeder 110 to be removed.

[0021] FIG. 5 is a schematic diagram showing the configuration of opening-closing cover 10 in a closed state, and FIG. 6 is a schematic diagram showing the configuration of opening-closing cover 10 in an open state. At the lower end of the opening / closing cover 10, a support shaft 10a is provided which is rotatably supported on the device body. The open / close cover 10 also includes a conveyor belt 6 stretched between a pressure roller 4, which is a pressure member, and a drive roller 5. The pressure roller 4 is biased toward the main body of the apparatus by a compression spring 7, and comes into contact with a conveyor roller 3, which is a pressure-receiving member of the main body of the apparatus, via the conveyor belt 6, forming a conveyor nip.

[0022] The pressure roller 4 is held by the opening / closing cover 10 so as to be movable within a predetermined range in the left-right direction in the figure (the opening / closing direction of the opening / closing cover). When the opening / closing cover 10 is opened as shown in Fig. 6, the pressure roller 4 protrudes a predetermined amount from a cover-side guide portion 9 serving as a surrounding member. When the opening / closing cover 10 is closed and the pressure roller 4 abuts against the conveying roller 3, it compresses the compression spring 7 and moves from the position indicated by the solid line in Fig. 6 to the position indicated by the dashed line, and presses the conveying roller 3 with the biasing force of the compression spring 7.

[0023] The opening / closing cover 10 is also provided with a hook member 1 that holds the opening / closing cover 10 in the closed position. The hook member 1 has a tip inclined portion 1a that is inclined downward from the tip so that the opening / closing cover 10 can be closed without operating the handle 20, as will be described later.

[0024] As shown in Fig. 5, the opening / closing cover 10 is held in the closed position by hooking the hook member 1 onto the engagement shaft 2, which is an engagement member provided on the paper feed frame 110b. By operating the above-mentioned handle 20, the hook member 1 rotates clockwise in Fig. 5, disengaging from the engagement shaft 2 and allowing the opening / closing cover 10 to open. As shown in Fig. 6, the opening / closing cover 10 opens to expose the paper feed transport path, making it easy to remove paper jammed in the paper feed transport path.

[0025] FIG. 7 is a schematic perspective view showing a mechanism for releasing the engagement between hook member 1 and engagement shaft 2 by operating handle 20, and FIG. 8 is a perspective view showing the periphery of handle 20 of opening / closing cover 10. As shown in FIG. As shown in Fig. 7, the hook members 1 are provided on both ends of a holding member 11 extending in the axial direction of the pressure roller 4 (the front-rear direction of the device). The holding member 11 is rotatably supported by the opening-closing cover 10. The holding member 11 has a pressed portion 11a, the upper part of which faces the pressing portion 20b of the handle 20 and is pressed by the pressing portion 20b of the handle 20. The holding member 11 is biased by a torsion spring 12, which is a biasing member, so as to rotate in the opposite direction to the rotation direction that releases the engagement between the hook member 1 and the engagement shaft 2. The biasing force of the torsion spring 12 causes the pressed portion 11a to abut against the pressing portion 20b of the handle 20.

[0026] Handle 20 has a hook-shaped operating part 20c, a support shaft 20a rotatably supported by opening / closing cover 10, and pressing part 20b described above. Operating part 20c is provided so as to be exposed from recess 10b of opening / closing cover 10 as shown in FIG.

[0027] When an operator inserts his / her finger into the operating portion 20c of the handle 20 from the recess 10b of the opening / closing cover shown in Fig. 8 and pushes the operating portion 20c towards himself / herself, the handle 20 rotates in the direction of the arrow A shown in Fig. 7, with the support shaft 20a as a fulcrum. As the handle 20 rotates in the direction of the arrow A in the figure, the pressing portion 20b of the handle 20 presses the pressed portion 11a of the holding member 11 against the biasing force of the torsion spring 12. This causes the holding member 11 to rotate in the direction of the arrow B in the figure, and the hook members 1 provided on both ends of the holding member 11 to rotate in the direction of the arrow C in the figure.

[0028] FIG. 9 is a diagram illustrating disengagement between the hook member 1 and the engagement shaft 2. As shown in FIG. As shown in FIG. 9(a), when the opening / closing cover 10 is closed, the hook member 1 is hooked on an engagement shaft 2 provided on the paper feed frame 110b, and the opening / closing cover 10 is held in the closed position.

[0029] As explained with reference to Fig. 7, when an operator operates operating portion 20c of handle 20 to rotate hook member 1 in the direction of arrow C in Fig. 7, as shown in Fig. 9(b), lower end portion 1b, which is the lower end of tip inclined portion 1a of hook member 1, is positioned above the top of engagement shaft 2. This releases the engagement between hook member 1 and engagement shaft 2, allowing opening / closing cover 10 to be opened.

[0030] FIG. 10 is a diagram illustrating the engagement between the hook member 1 and the engagement shaft 2. As shown in FIG. When the operator pushes the opening / closing cover 10 toward the device body from an open state to close the opening / closing cover 10, the tip inclined portion 1a of the hook member 1 comes into contact with the engagement shaft 2. When the opening / closing cover 10 is further closed from this state, the tip inclined portion 1a is pushed into the engagement shaft 2, and the hook member 1 rotates clockwise in the figure against the biasing force of the torsion spring 12. As a result, the engagement shaft 2 moves relatively downward along the tip inclined portion 1a.

[0031] When the engagement shaft 2 moves relatively to the lower end of the inclined tip portion 1a and the opening-closing cover 10 is further closed from that state, the lower end portion 1b of the hook member 1 slides up the outer circumferential surface of the engagement shaft 2. When the lower end portion 1b gets over the top of the engagement shaft 2, as shown in Fig. 10(a), the urging force of the torsion spring 12 causes the hook member 1 to rotate in the direction of arrow C in the figure, and the lower end portion 1b slides down the outer circumferential surface of the engagement shaft 2. Then, as shown in Fig. 10(b), the hook member 1 engages with the engagement shaft 2 and the opening-closing cover 10 is closed.

[0032] In this embodiment, when the lower end 1b of the hook member 1 gets over the top of the engagement shaft 2, the opening / closing cover is automatically closed by the biasing force of the torsion spring 12. This allows the opening / closing cover 10 to be closed even if the worker mistakenly thinks that the opening / closing cover 10 is closed and releases his / her hand from the opening / closing cover 10 before the opening / closing cover 10 is completely closed.

[0033] When the operator releases the opening / closing cover 10 before the lower end 1b of the hook member 1 passes over the top of the engagement shaft 2, the force of opening the opening / closing cover 10 due to its own weight is strong, so the opening / closing cover 10 rotates in the opening direction. However, if the operator releases the opening / closing cover immediately after the lower end 1b of the hook member 1 passes over the top of the engagement shaft 2, the opening / closing cover 10 may remain in place and become half-closed. When the opening / closing cover 10 is half-closed in this way, the operator may mistakenly think that the opening / closing cover is closed, and paper feeding may start in the half-closed state ... paper fed from the paper feed cassette may not be transported correctly, and a paper jam may occur.

[0034] FIG. 11 is a diagram for explaining the relationship of forces acting on contact point C between lower end portion 1b of hook member 1 and engagement shaft 2 when opening / closing cover 10 is closed. 11, a biasing force Fb of the torsion spring and a force (hereinafter referred to as an opening force Fa) due to the weight of the opening-closing cover 10 act at a contact point C between the hook member 1 and the engagement shaft 2. The biasing force Fb acts in a direction perpendicular to a line segment S1 connecting the rotation center O1 of the hook member 1 and the contact point C. The opening force Fa acts in a direction perpendicular to a line S2 connecting the fulcrum of rotation of the opening-closing cover 10 (the center of the support shaft 10a) and the contact point C.

[0035] After the lower end 1b of the hook member 1 gets over the top of the engagement shaft 2, the vector component in the tangential direction of the contact point C of the biasing force Fb becomes a closing force F2 that moves the lower end 1b down while sliding against the outer circumferential surface of the engagement shaft 2. The vector component in the tangential direction of the contact point C of the opening force Fa becomes an opening force F1 that moves the lower end 1b up the top of the engagement shaft 2 while sliding against the outer circumferential surface of the engagement shaft 2.

[0036] 11, the angle between the tangent to the contact point C and the biasing force Fb becomes smaller, and the closing force F2 becomes larger. On the other hand, the angle between the tangent to the contact point C and the opening force Fa becomes larger, and the angle between the tangent to the contact point C and the opening force Fa becomes larger, as the contact point C is shifted to the left from the position in FIG. 11. Also, the angle between the direction of the weight of the opening-closing cover 10 (vertical direction) and the line segment S2 becomes smaller, as the contact point C is shifted to the left from the position in FIG. 11. As a result, the opening force Fa, which is the vector component in the direction perpendicular to the line segment S2 of the weight of the opening-closing cover 10, also becomes smaller. Therefore, the opening force F1 becomes smaller. As a result, the closer the contact point C is to the device body, the more dominant the closing force F2 due to the biasing force Fb of the torsion spring 12 becomes, and the opening-closing cover 10 is automatically closed.

[0037] On the other hand, the further to the right (the opening side of the opening-closing cover 10) the contact point C is shifted from the position in Fig. 11, the larger the angle between the tangent to the contact point C and the biasing force Fb becomes, and the smaller the closing force F2 becomes. On the other hand, the further to the right the contact point C is shifted from the position in Fig. 11, the smaller the angle between the tangent to the contact point C and the opening force Fa becomes. Also, the further to the right the contact point C is shifted from the position in Fig. 11, the larger the angle between the direction of the weight of the opening-closing cover 10 (the vertical direction) and the line segment S2 becomes, and the opening force Fa becomes larger. As a result, the closer the contact point C is to the opening side of the opening-closing cover, the more dominant the opening force Fa due to the weight of the opening-closing cover becomes, and the opening cover 10 opens automatically.

[0038] In addition, a holding force F3 that holds the lower end 1b in place, such as a frictional force between the lower end 1b of the hook member 1 and the engagement shaft 2, also acts at the contact point C. Then, while the lower end 1b passes over the top of the engagement shaft 2 and advances a certain angle, the absolute value of the difference between the closing force F2 and the opening force F1 is small and may fall below the holding force F3. As a result, the lower end of the hook member 1 does not move around the outer periphery of the engagement shaft 2 and remains in place, causing the opening / closing cover 10 to be in a half-closed state.

[0039] Therefore, in this embodiment, the amount of protrusion of the pressure roller 4 from the cover side guide portion 9 is made adjustable, and the reaction force from the conveying roller 3 when the pressure roller 4 contacts the conveying roller 3 ensures that the absolute value of the difference between the closing force F2 and the opening force F1 does not fall below the holding force F3.

[0040] FIG. 12 is a schematic diagram of an adjustment member 30 for adjusting the amount of protrusion of the pressure roller 4 from the cover-side guide portion 9. As shown in FIG. As shown in FIG. 12, the adjustment members 30 are provided on both ends of the shaft 4a of the pressure roller 4. Each adjustment member 30 has a through hole 32 that is long in the vertical direction and through which the shaft 4a of the pressure roller 4 passes. The surface of the through hole 32 on the device body side has three stepped surfaces 32a, 32b, and 32c. Each adjustment member 30 is held by the opening and closing cover 10 so as to be movable within a predetermined range in the vertical direction. Each adjustment member 30 also has a knob portion 31 with a concave-convex shape that an operator places his / her finger on when operating the adjustment member 30. By making the knob portion 31 have a concave-convex shape, the operator's finger can slide the adjustment member 30 in the vertical direction without slipping relative to the adjustment member 30.

[0041] FIG. 13 is a diagram illustrating adjustment of the protrusion amount of the pressure roller 4 from the cover side guide portion 9 by the adjustment member 30. As shown in FIG. 13(a), initially, the adjustment member 30 is located at the top of its vertical movement range, and at this time, the shaft 4a of the pressure roller 4 abuts against the lowest step surface 32a among the three step surfaces 32a, 32b, and 32c. The gap in the left-right direction in the figure (opening / closing cover opening / closing direction) at the position of the lowest step surface 32a of the through hole 32 is larger than the diameter of the shaft 4a of the pressure roller. Therefore, even when the shaft 4a of the pressure roller 4 abuts against the lowest step surface 32a, it is still possible to move the through hole 32 in the left-right direction in the figure.

[0042] As shown in Fig. 13(a), initially, the shaft 4a of the pressure roller 4 abuts against the lowermost step surface 32a, reducing the amount of protrusion of the pressure roller 4 from the cover-side guide portion 9. As described above, the open-close cover 10 rotates about the support shaft 10a at the lower end as a fulcrum, and when the open-close cover is closed, the pressure roller 4 moves obliquely upward while tracing an arc-shaped trajectory. If the pressure roller 4 protrudes too much from the cover-side guide portion 9, the pressure roller 4 may hit the transport roller 3 from obliquely below, and the transport nip may not be formed at the desired position.

[0043] On the other hand, as shown in Fig. 13(a), by minimizing the amount of protrusion of the pressure roller 4 from the cover-side guide portion 9, the pressure roller 4 can be brought into contact with the transport roller 3 as close as possible to the time immediately before the open-close cover 10 is closed. This allows the pressure roller 4 to be brought into contact with the transport roller 3 from a substantially horizontal direction, and the transport nip can be formed at a target position with high precision. Therefore, when half-closure does not occur, the adjustment member 30 is positioned so that the shaft 4a of the pressure roller 4 shown in Fig. 13(a) comes into contact with the lowest step surface 32a.

[0044] When the operator operates the knob 31 to lower the adjustment member 30 and bring the shaft 4a of the pressure roller 4 into contact with the stepped surface 32b in the vertical center as shown in Fig. 13(b), the amount of protrusion of the pressure roller 4 from the cover side guide 9 increases. As a result, the pressure roller 4 comes into contact with the transport roller 3 at an earlier stage than in Fig. 13(a), and the open-close cover 10 receives a reaction force from the transport roller 3 in the opening direction at an earlier stage than in Fig. 13(a).

[0045] Furthermore, when the operator operates the knob portion 31 to further lower the adjustment member 30 and bring the shaft 4a of the pressure roller 4 into contact with the uppermost step surface 32c as shown in Fig. 13(c), the amount of protrusion of the pressure roller 4 from the cover side guide portion 9 becomes maximum. As a result, the pressure roller 4 comes into contact with the conveying roller 3 at an earlier stage than in Fig. 13(b), and the open-close cover receives a reaction force from the conveying roller 3 in the opening direction at an earlier stage.

[0046] 13(a), 13(b), and 13(c), the amount of protrusion of pressure roller 4 from cover-side guide portion 9 when opening / closing cover 10 is closed is the same, and the amount of compression of compression spring 7 is the same. Therefore, the contact pressure of pressure roller 4 against conveying roller 3 when opening / closing cover 10 is closed is constant, and the conveying nip pressure can be optimized for conveying paper.

[0047] Fig. 14 is a graph showing the relationship between the force (hereinafter referred to as adjustment force F4) in the tangential direction of the contact point C of the contact point C of the lower end 1b of the hook member 1 and the engagement shaft 2, the difference F12 (=F1-F2) between the closing force F2 and the opening force F1, and the holding force F3. The horizontal axis X in Fig. 14 is the horizontal position of the contact point C of the lower end 1b of the hook member 1 and the engagement shaft 2.

[0048] As described above, the opening force F1 decreases as the opening-closing cover 10 is closed, but the closing force F2 increases as the opening-closing cover 10 is closed. Therefore, as shown in Fig. 14, the difference value F12 between the opening force F1 and the closing force F2 gradually decreases as the opening-closing cover 10 is closed, and halfway through, the difference value F12 becomes negative and becomes a force in the closing direction (closing force).

[0049] The holding force F3 shown in Fig. 14 is the maximum value of the holding force F3 at each position, and when the difference value F12 is an opening force, the holding force F3 acts as a closing force, and when the difference value F12 is a closing force, the holding force F3 acts as an opening force. In the shaded area in Fig. 14, the difference value F12 may fall below the holding force F3, and the lower end 1b of the hook member 1 may not slide on the engagement shaft 2 and may remain in place, causing the opening / closing cover 10 to be in a half-closed state.

[0050] 11 at the contact point C between the lower end 1b of the hook member 1 and the engagement shaft 2. As a result, the adjustment force F4, which is a vector component in the tangential direction of the contact point C of the reaction force of the conveying roller 3 acting on the contact point C, increases the opening force F1, which is a force in the direction in which the lower end 1b of the hook member 1 moves up toward the top of the engagement shaft 2.

[0051] The reaction force from the conveying roller 3 acting on the contact point C increases as the opening-closing cover 10 is closed (as the contact point C moves to the left in the figure (towards the device body)). On the other hand, as the opening-closing cover 10 is closed, the angle between the reaction force acting in the same direction as the opening force Fa shown in FIG. 11 and the tangent to the contact point C at the contact point C increases, and the adjustment force F4 acts in a decreasing direction. In this embodiment, the decrease in the adjustment force F4 due to the increase in the angle between the tangent to the contact point C exceeds the increase in the reaction force. As a result, as shown in FIG. 14, the adjustment force F4 gradually decreases as the cover is closed. However, as can be seen from FIG. 14, the adjustment force F4 is greater than the maximum value of the holding force F3 at each position, and therefore the application of the adjustment force F4 causes the opening-closing cover 10 to be opened without being in a half-closed state.

[0052] As shown in Fig. 14, there is a point where the opening force F1 and the closing force F2 are balanced, and the difference value F12 between the opening force F1 and the closing force F2 is 0. At this point, the difference value F12 is less than the holding force F3, and half-closure occurs. Therefore, when the protrusion amount of the pressure roller from the cover side guide part 9 shown in Fig. 13(a) is the minimum protrusion amount, the pressure roller 4 abuts against the conveying roller 3 at the abutment point C1 before the abutment point between the lower end part 1b of the hook member 1 and the engagement shaft 2 where the difference value F12 is 0, and an adjustment force F4 is generated.

[0053] 13(c), the protrusion amount is set so that the pressure roller 4 abuts against the conveying roller 3 at a stage before the frontmost position C2 of the range where half-closure occurs. Specifically, half-closure may occur after the lower end 1b of the hook member 1 passes the top of the engagement shaft 2. Therefore, the protrusion amount of the pressure roller 4 from the cover side guide portion 9 in FIG. 13(c) is adjusted so that the pressure roller 4 abuts against the conveying roller 3 at a stage where the abutment point between the lower end 1b of the hook member 1 and the engagement shaft 2 is located before the top of the engagement shaft 2. As a result, when the shaft 4a of the pressure roller 4 abuts against the uppermost step surface 32c of the adjustment member 30 as shown in FIG. 13(c), half-closure can be reliably prevented.

[0054] When the half-closed state occurs, the adjustment member 30 is operated to move the position of the pressure roller 4 from the position shown by the dashed line in FIG. 15(a) to the position shown by the solid line in the figure, and the protrusion amount of the pressure roller 4 from the cover side guide portion 9 is increased. As a result, as shown in FIG. 15(b), before the lower end 1b of the hook member 1 reaches the contact point where the openable cover 10 is in the half-closed state, the pressure roller 4 is brought into contact with the conveying roller 3, generating a reaction force Fc in the direction in which the openable cover 10 opens. As a result, the adjustment force F4 acts on the contact point C. As shown in FIG. 14, since the adjustment force F4 is greater than the maximum value of the holding force F3, the adjustment force F4 acts, causing the lower end 1b of the hook member 1 to climb toward the top of the engagement shaft 2, and the openable cover 10 opens. This prevents the openable cover 10 from being in the half-closed state, and makes the operator realize that the openable cover 10 is not closed. This allows the openable cover 10 to be pushed into the device body again to close the openable cover 10 again.

[0055] In this embodiment, the side surface of the through hole 32 of the adjustment member 30 with which the shaft 4a of the pressure roller 4 abuts is stepped, so that the amount of protrusion of the pressure roller 4 from the cover side guide portion 9 changes stepwise. This makes it easy to match the amount of protrusion of the pressure roller 4 on one axial side from the cover side guide portion 9 with the amount of protrusion of the pressure roller 4 on the other axial side from the cover side guide portion 9, and facilitates manual adjustment of the amount of protrusion.

[0056] Also, the side of the through hole 32 of the adjustment member 30 may be inclined toward the main body of the apparatus as it goes upward, so that the amount of protrusion can be adjusted linearly. This allows the amount of protrusion to be finely adjusted, and compared to a case where the amount of protrusion is changed stepwise, the amount of protrusion can be kept small to prevent half-closing. By keeping the amount of protrusion small, the pressure roller 4 can be brought into contact with the transport roller 3 as close as possible to the opening / closing cover 10 being closed, and the transport nip can be formed at the desired position.

[0057] If the vertical position of the adjustment member on one side differs from the vertical position of the adjustment member on the other side, the timing of generation of the reaction force applied to the contact point between the lower end 1b of the hook member 1 on one axial side and the engagement shaft 2 differs from the timing of generation of the reaction force applied to the contact point between the lower end 1b of the hook member 1 on the other side and the engagement shaft 2. As a result, the opening-closing cover 10 may try to open only on one side in the axial direction, causing a risk of twisting or the like in the opening-closing cover 10.

[0058] Therefore, a position detection sensor may be provided to detect the vertical position of the adjustment member 30, and if the vertical position of the adjustment member 30 on one axial side and the vertical position of the adjustment member 30 on the other axial side differ from each other, the operator may be notified of this.

[0059] A distance sensor can be used as the position detection sensor for detecting the position. A distance sensor is provided facing the adjustment member 30 from above or below, and the distance sensor measures the distance to the adjustment member 30, thereby making it possible to detect the vertical position of the adjustment member 30.

[0060] FIG. 16 is a flow diagram of the position adjustment control of the adjustment member 30. For example, when the control unit of the image forming apparatus detects that the opening / closing cover 10 is opened, the control unit periodically detects the vertical positions of the adjustment members 30 using the position detection sensor (S1). If the vertical positions of the adjustment members are the same (Yes in S2), the control ends.

[0061] On the other hand, if the mismatch in the vertical positions of the adjustment members 30 continues for a predetermined time, the operation display unit 130 displays a message that the vertical positions of the adjustment members 30 on one side and the vertical positions of the adjustment members 30 on the other side are different from each other (S3). At this time, it is preferable to display the vertical positions of the adjustment members 30 on one side and the vertical positions of the adjustment members 30 on the other side on the operation display unit 130. By displaying the positions of the adjustment members, it is possible to inform the operator how much one of the two adjustment members needs to be adjusted vertically to make the vertical positions match.

[0062] When the vertical positions of the adjustment members 30 do not match, the operator is notified, thereby preventing the opening-closing cover 10 from being closed in a state in which the protrusion amounts of the pressure roller 4 from the cover-side guide portion 9 are different on one axial side and the other side. As a result, it is possible to prevent twisting of the opening-closing cover 10 when opening and closing the opening-closing cover 10.

[0063] FIG. 17 is a schematic perspective view showing a configuration in which an adjustment member 30 on one axial side and an adjustment member 30 on the other axial side are connected by a connecting member 33. As shown in FIG. 17, by connecting the adjustment member 30 on one axial side and the adjustment member 30 on the other axial side with a connecting member 33, the adjustment member 30 on one axial side and the adjustment member 30 on the other axial side can be moved up and down in conjunction with each other. This simplifies the protrusion amount adjustment work compared to adjusting the protrusion amount of the pressure roller 4 by moving each adjustment member 30 up and down separately. In addition, it is possible to prevent the vertical position of the adjustment member 30 on one side from differing from the vertical position of the adjustment member 30 on the other side, and to prevent the protrusion amount of the pressure roller 4 on one axial side from differing from the protrusion amount of the pressure roller 4 on the other axial side.

[0064] Furthermore, in the above description, the adjustment member 30 is moved vertically manually, but a drive device may be provided so that the adjustment member 30 is moved vertically by the drive device. FIG. 18 is a diagram showing an example of an adjustment flow in which the driving device moves the adjustment member 30 in the up and down direction. When the worker confirms that the opening-closing cover 10 is in a half-closed state (S11), he / she operates the operation display unit 130 to instruct the adjustment operation by the adjustment members 30 (S12). When the adjustment operation is instructed, the control unit drives the drive device to lower the adjustment members 30, changing the state shown in FIG. 13(a) to the state shown in FIG. 13(b), thereby changing the amount of protrusion of the pressure roller 4 relative to the cover-side guide portion 9. When the state shown in FIG. 13(b) is reached, the operation display unit 130 displays a message to confirm whether the opening-closing cover 10 is open or not. When the worker operates the operation display unit 130 to input that the opening-closing cover 10 is confirmed to be open, the adjustment flow ends (S14).

[0065] On the other hand, if the opening / closing cover 10 is not opened and remains in the half-closed state even after changing to the state shown in FIG. 13(b) (Yes in S13), the operator operates the operation display unit 130 to input that the opening / closing cover 10 is in the half-closed state. When the control unit receives the input that the opening / closing cover 10 is in the half-closed state, the control unit drives the drive device again to lower the adjustment members 30 again, and changes the state from that shown in FIG. 13(b) to that shown in FIG. 13(c). As described above, in the state shown in FIG. 13(c), the pressure roller 4 is made to abut against the conveying roller 3 at a stage prior to the region where half-closing occurs (the region with diagonal lines in FIG. 14). As a result, a reaction force of the conveying roller 3 is generated, and the opening / closing cover 10 in the half-closed state is opened. This makes it possible to prevent the opening / closing cover 10 from being half-closed when closing the opening / closing cover 10.

[0066] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the spirit of the present invention described in the claims, unless otherwise specifically limited in the above description.

[0067] For example, in the above description, an example has been described in which the present invention is applied to an opening / closing cover that opens and closes the conveying path of the paper feed unit 110, but the present invention can also be applied to an opening / closing cover that opens and closes the double-sided conveying path 120.

[0068] In the above description, the occurrence of half-closed state is suppressed by adjusting the protruding amount of the pressure roller 4, but a pressure member that abuts against a member of the device body and presses the member of the device body may be provided separately from the pressure roller 4, and the protruding amount of the pressure member may be adjusted. Also, this pressure member may be made to abut against the member of the device body on the near side of the half-closed state area shown by the diagonal lines in Fig. 14, and the pressing force applied to the member of the device body may be adjusted by adjusting the biasing force of a biasing member such as a spring applied to the pressure member. In this case, the reaction force from the member of the device body is increased by adjusting the pressing force, and the force in the opening direction is increased, thereby suppressing the occurrence of half-closed state.

[0069] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) The sheet transport device includes an opening / closing member such as an opening / closing cover 10 whose lower end is rotatably supported by the device body and which opens and closes a sheet transport path, a pressure member such as a pressure roller 4 provided on the opening / closing member which presses a pressured member such as a transport roller 3 of the device body, and a hook member 1 which engages with an engagement member such as an engagement shaft 2 of the device body and holds the opening / closing member in a closed position. The sheet transport device is provided with a biasing member such as a torsion spring 12 which biases the hook member 1 so as to maintain engagement with the engagement member, and is configured so that the hook member 1 slides on the engagement member while rotating against the biasing force of the biasing member, thereby overcoming the engagement member and engaging with the engagement member, and is provided with an adjustment means for adjusting at least one of the pressure force of the pressure member and the amount of protrusion of the pressure member relative to the surrounding members. There is a structure in which the hook member and the engaging member are configured as follows. That is, the engaging member is an axis member, the hook member is supported rotatably relative to the opening / closing member, and is biased by a biasing member so as to maintain engagement with the engaging member. Also, the hook member is provided with a tip inclined portion that is inclined downward as it moves away from the tip. With this configuration, as described below, the hook member slides on the engaging member, rotates against the biasing force of the biasing member, and overcomes the engaging member to engage with the engaging member. Specifically, when the opening / closing member is rotated around the lower end as a fulcrum to close, the tip inclined portion of the hook member abuts against the engaging member. When the opening / closing member is further closed from this state, the hook member rotates in a direction in which the tip moves upward against the biasing force of the biasing member, and the engaging member moves relatively downward along the tip inclined portion of the hook member. Then, after the engaging member reaches the lower end of the tip inclined portion, the lower end of the tip inclined portion slides up the outer circumferential surface of the circumferential engaging member. When the lower end of the inclined tip portion passes the apex of the engagement member, the biasing force of the biasing member rotates the tip of the hook member in a direction moving downward, and the lower end of the inclined tip portion slides down along the outer circumferential surface of the engagement member. The hook member then engages with the engagement member, and the opening / closing member is closed. In this way, when the lower end of the inclined tip portion passes over the apex of the engagement member, the opening / closing member is automatically closed by the biasing force of the biasing member. When the opening / closing member is closed, the weight of the opening / closing member acts as a force in a direction to open the opening / closing member (hereinafter referred to as opening force Fa) on contact point C between the hook member (lower end of the inclined tip portion) and the engaging member, as shown in Figure 11. After passing the top of the engaging member, the vector component of the opening force Fa in the tangential direction of the contact point becomes a force in a direction to move the contact point of the hook member with the engaging member (lower end of the inclined tip portion) up toward the top of the engaging member (hereinafter referred to as opening force F1). Depending on the force relationship between this opening force F1 and the vector component (hereinafter referred to as the closing force F2) tangential to the contact point of the biasing force Fb of the biasing member that moves the contact portion of the hook member with the engaging member down along the outer circumferential surface of the engaging member, the force may be less than the force (hereinafter referred to as the holding force F3) that tries to stop the movement of the contact portion, such as the sliding resistance between the hook member and the outer circumferential surface of the engaging member, and the sliding of the hook member with the engaging member may stop midway, causing the opening / closing member to become half-closed. In the first aspect, by adjusting at least one of the pressure of the pressure member and the amount of protrusion of the pressure member relative to the surrounding members by the adjustment means, it is possible to adjust the reaction force from the pressurized member of the device body when the contact portion of the hook member with the engaging member (the lower end of the inclined tip portion) passes the top of the engaging member and moves down the outer peripheral surface of the engaging member, and the timing at which the reaction force occurs. The reaction force acts as the opening force Fa at the contact point C and increases the opening force F1. By increasing the opening force F1, it is possible to prevent the force relationship between the opening force F1 and the closing force F2 from becoming a force relationship in which the sliding with the outer peripheral surface stops halfway (below the holding force F3). This makes it possible to prevent the opening and closing member from being half-closed.

[0070] (Aspect 2) In the first embodiment, the engaging member such as the engaging shaft 2 is an axial member, and the tip of the hook member 1 is inclined with respect to the vertical direction. According to this, as described in the embodiment, the hook member 1 can slide on an engaging member such as the engaging shaft 2 while rotating against the biasing force of a biasing member such as the torsion spring 12 to overcome the engaging member and engage with it.

[0071] (Aspect 3) In embodiment 1 or 2, an adjustment means such as adjustment member 30 adjusts the amount of protrusion, and during the engagement operation in which hook member 1 slides over an engagement member such as engagement shaft 2 to engage with the engagement member, the adjustment means can adjust the amount of protrusion at which a pressure applying member such as pressure roller 4 abuts against a pressured member such as conveying roller 3 before the abutment portion of hook member 1 with the engagement member, such as lower end portion 1b, reaches the top of the engagement member. According to this, as explained in the embodiment, the force relationship between the opening force F1 and the closing force F2 causes the abutment portion of the hook member, which is the lower end portion 1b, to stop sliding against the engaging member, such as the engaging shaft 2, only after the abutment portion passes over the vertical apex of the engaging member. Therefore, by adjusting the amount of protrusion using the adjustment means, which is the adjustment member 30, so that the pressing member, such as the pressure roller 4, abuts against the member to be pressed, such as the conveying roller 3, before it is positioned at the vertical apex of the engaging member, a reaction force can be generated before the lower end passes over the vertical apex of the engaging member. This can reliably prevent the occurrence of half-closed state.

[0072] (Aspect 4) In any of aspects 1 to 3, the pressurized member is a conveying roller 3, the pressurizing member is a pressurizing roller 4, the surrounding member is a guide member such as a cover side guide portion 9 that guides a sheet such as paper, and an adjustment means such as an adjustment member 30 adjusts the amount of protrusion of the pressurizing roller 4 relative to the guide member. According to this, as described in the embodiment, by adjusting the amount of protrusion of the pressure roller 4 relative to the guide member, the occurrence of half-closing can be suppressed without changing the pressure force of the pressure roller 4 on the conveying roller 3 when an opening / closing member such as the opening / closing cover 10 is closed.

[0073] (Aspect 5) In any of aspects 1 to 4, an adjustment means such as adjustment member 30 is provided on one end side and the other end side of a pressure member such as pressure roller 4 in the axial direction so as to be movable within a predetermined range on an opening / closing member such as opening / closing cover 10, and by moving the adjustment means, at least one of the pressure force and the amount of protrusion is changed in a stepwise manner. With this, compared to when at least one of the pressure force and the protrusion amount changes linearly, the timing at which the reaction force is generated and the pressure force can be easily made the same at one axial end and the other axial end, making manual adjustment easier.

[0074] (Aspect 6) In any of aspects 1 to 5, an adjustment means such as adjustment member 30 is provided on one end and the other end in the axial direction of a pressure member such as pressure roller 4 so as to be movable within a predetermined range on an opening / closing member such as opening / closing cover 10, and at least one of the pressure force and the amount of protrusion is adjusted by moving the adjustment means. If the position of the adjustment means provided at one end in the axial direction differs from the position of the adjustment means provided at the other end in the axial direction, an alarm means such as an operation display unit 130 is provided to alarm an operator. As described in the embodiment, this prevents the position of the adjustment means on one end side from differing from the position of the adjustment means on the other end side, and prevents the adjustment amount from differing between the one end side and the other end side. This makes it possible to make the timing at which the reaction force is generated and the pressure force on the one axial end side and the other end side almost the same, and prevents twisting of the opening / closing member such as the opening / closing cover 10 from occurring when the opening / closing member is opened or closed.

[0075] (Aspect 7) In any of aspects 1 to 5, an adjustment means such as the adjustment member 30 is provided on one end side and the other end side of the axial direction of a pressure member such as the pressure roller 4 so as to be movable within a predetermined range on an opening / closing member such as the opening / closing cover 10, and the adjustment means provided on one end side and the adjustment means provided on the other end side move in conjunction with each other. This simplifies the adjustment process compared to the case where the adjustment means such as the adjustment members 30 are moved up and down separately as described in the embodiment. Also, the position of the adjustment means at one end and the position of the adjustment means at the other end can be prevented from being different from each other, and the adjustment amount at one end and the other end can be prevented from being different from each other. This makes it possible to make the timing and pressure force at which the reaction force is generated at the one axial end and the other axial end almost the same, and suppresses the occurrence of twisting of the opening and closing member when opening and closing the opening and closing member of the opening and closing cover 10.

[0076] (Aspect 8) In any of aspects 1 to 7, an adjustment means such as adjustment member 30 adjusts at least one of the pressure force and the amount of protrusion so that the tangential force acting on contact point C between the lower end of the tip inclined portion 1a, such as the lower end portion 1b of the hook member 1, and an engaging member, such as the engaging shaft 2, is greater than a force, such as holding force F3, that stops the sliding of the outer peripheral surface of the engaging member at the lower end of the tip inclined portion. This makes it possible to prevent the half-closed state from occurring, as described in the embodiment.

[0077] (Aspect 9) In an image forming apparatus equipped with a sheet transport device, the sheet transport device according to any one of the embodiments 1 to 8 was used as the sheet transport device. This makes it possible to prevent the opening / closing member from being partially closed, thereby preventing sheet jams caused by the partially closed state. [Explanation of symbols]

[0078] 1: Hook member 1a:Tip slope 1b: Bottom end 2: Engagement shaft 3: Transport roller 4: Pressure roller 4a: Axis 5: Drive roller 6: Conveyor belt 7: Compression spring 9: Cover side guide 10: Opening and closing cover 10a: Support shaft 10b: Recess 11: Holding member 11a: Pressed part 12: Torsion spring 20: Handle 20a: Support shaft 20b: Pressing part 20c:Operation unit 30: Adjustment parts 31: Knob section 32:Through hole 32a: Step surface 32b: Step surface 32c: Step surface 33: Connecting member 102: Paper 103: Paper feed cassette 110:Paper feed section 110b: Paper feed frame 111: Paper feed roller 111b: Separation roller pair 112: Transport path 120: Double-sided transport path 130: Operation display section C: Contact point F1: Opening force F2: Closing force F3: Holding force F4: Adjustment force Fa: Opening force Fb: Force [Prior art documents] [Patent documents]

[0079] [Patent Document 1] Patent No. 5865868

Claims

1. an opening / closing member whose lower end is rotatably supported by the device body and which opens and closes the sheet transport path; a pressing member provided on the opening / closing member for pressing a pressurized member of the device body; a hook member that engages with an engaging member of the apparatus body and holds the opening / closing member in a closed position, a biasing member for biasing the hook member so as to maintain engagement with the engagement member; The hook member is configured to slide over the engaging member and rotate against the biasing force of the biasing member to overcome the engaging member and engage with the engaging member, A sheet conveying device comprising: an adjustment unit that adjusts at least one of a pressure force of the pressure member and a protrusion amount of the pressure member relative to a surrounding member.

2. 2. The sheet conveying device according to claim 1, the engaging member is a shaft member, A sheet conveying device, wherein a tip of the hook member is inclined with respect to a vertical direction.

3. 2. The sheet conveying apparatus according to claim 1, The adjustment means adjusts the amount of protrusion, The adjustment means is capable of adjusting the amount of protrusion of the pressure applying member against the pressure receiving member before the contact portion of the hook member with the engaging member reaches the top of the engaging member during an engagement operation in which the hook member slides over the engaging member and engages with it.

4. 2. The sheet conveying apparatus according to claim 1, the pressure-receiving member is a conveying roller, and the pressure-applying member is a pressure roller, the surrounding member is a guide member that guides the sheet, The sheet conveying device according to claim 1, wherein the adjusting means adjusts a protruding amount of the pressure roller relative to the guide member.

5. 2. The sheet conveying apparatus according to claim 1, the adjustment means is provided at one end side and the other end side in the axial direction of the pressure member so as to be movable within a predetermined range, A sheet conveying device, characterized in that at least one of the pressure force and the protrusion amount is changed in a stepwise manner by moving the adjustment means.

6. 2. The sheet conveying apparatus according to claim 1, the adjustment means is provided at one end side and the other end side in an axial direction of the pressing member so as to be movable within a predetermined range, and at least one of the pressing force and the protrusion amount is adjusted by moving the adjustment means, A sheet conveying device characterized by having an alarm means for notifying an operator when the position of the adjustment means provided at one end of the axial direction differs from the position of the adjustment means provided at the other end of the axial direction.

7. 2. The sheet conveying apparatus according to claim 1, the adjustment means is movable within a predetermined range on the opening / closing member and is provided on one end side and the other end side in the axial direction of the pressure member, A sheet conveying device, characterized in that the adjustment means provided on the one end side and the adjustment means provided on the other end side move in conjunction with each other.

8. 2. The sheet conveying apparatus according to claim 1, The adjustment means adjusts at least one of the pressure force and the amount of protrusion so that the tangential force acting at the contact point between the hook member and the engaging member when the hook member overcomes the engaging member and engages with it is greater than the force that stops the hook member from sliding on the outer peripheral surface of the engaging member.

9. In an image forming apparatus including a sheet conveying device, 2. An image forming apparatus, comprising the sheet transport device according to claim 1 as said sheet transport device.

Images