Sheet feeding device

Abstract

To provide a sheet feeder by which reduction of operational force is realized when a paper-feeding roller is replaced therewith, while suppressing that the paper-feeding roller moves due to a paper-feeding operation.SOLUTION: A sheet feeder comprises (i) a paper feeding roller unit including a first roller, a second roller, a first engagement part and a second engagement part, (ii) a first engaged part including a holding member configured to engage with the first engagement part, that is movable in a shaft line direction of the first roller, and (iii) an applied pressure arm that energizes the second roller in a sheet direction having a second engaged part that engages with the second engagement part, and a restriction groove provided with a restriction surface. The restriction surface restricts movement in a shaft line direction of the second engagement part, when the second roller is energized in the sheet direction by the applied pressure arm. The restriction given by the restriction surface is released, when the second roller is not energized in the sheet direction by the applied arm.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device that feeds sheets. [Background technology]

[0002] In the past, some image forming apparatuses, such as electrophotographic image forming apparatuses, transport sheets to an image forming section to form an image on the sheets. Some of these image forming apparatuses include a sheet feeding device that detachably mounts a sheet stacking cassette on the image forming apparatus main body and automatically transports sheets stored in the sheet stacking cassette to the image forming section.

[0003] Some sheet feeding devices have a feed roller made of a frictional material such as rubber, and when feeding a sheet, the feed roller contacts the sheet on the sheet stacking cassette and rotates to feed the sheet to the image forming unit.

[0004] In a paper feed device with such a configuration, if the rubber of the feed roller deteriorates due to wear or the like, it may cause a decrease in feeding performance, and therefore the paper feed roller must be replaced periodically by a user or an operator such as a service technician.

[0005] Patent Document 1 discloses a feeding device in which a feeding roller is held by a movable member biased by a biasing means. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-80051 Summary of the Invention [Problem to be solved by the invention]

[0007] As shown in Patent Document 1, in a configuration in which a feed roller (paper feed roller) is held by a biased movable member, when attaching or detaching the feed roller, it is necessary to move the movable member against the biasing force of the biasing member. If the biasing force of this biasing member is too strong, the workability of attaching and detaching the feed roller becomes poor, but if the biasing force is too weak, the feed roller may move due to the paper feeding operation, etc.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a sheet feeding device that reduces the operating force required when replacing a sheet feed roller while suppressing movement of the sheet feed roller during a sheet feeding operation or the like. [Means for solving the problem]

[0009] In order to achieve the above object, a sheet feeding device of the present invention comprises: A sheet feeding device, A device body, a paper feed roller unit having a first roller, a second roller, a first engaging portion, and a second engaging portion; a sheet storage section for storing sheets; a first engaged portion provided on the device body, the first engaged portion having a holding member that is movable in an axial direction of the first roller and configured to engage with the first engaging portion by moving in a first direction; a biasing member provided in the device body and biasing the holding member in the first direction; a pressure arm provided in the device body, the pressure arm having a second engaged portion that engages with the second engaging portion and a regulating groove having a regulating surface, the pressure arm urging the second roller toward the sheet accommodated in the sheet accommodating portion; and the paper feed roller unit is removable from the apparatus body by moving in a second direction that is the opposite direction to the first direction, the regulating surface is configured to regulate movement of the second engaging portion in the axial direction when the second roller is urged toward the sheet by the pressure arm, The second roller is released from the restriction by the restriction surface when the second roller is not biased toward the sheet by the pressure arm. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a sheet feeding device that suppresses movement of the feed roller during a paper feeding operation and reduces the operating force required when replacing the feed roller. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment of the present invention; [Figure 2] FIG. 1 is a schematic cross-sectional view illustrating a configuration of a sheet feeding device according to a first embodiment. [Figure 3] 1 is a schematic perspective view of a paper feed roller unit according to a first embodiment; [Figure 4] FIG. 1 is a schematic perspective view showing a configuration of a paper feed unit according to a first embodiment; [Figure 5] FIG. 1 is a diagram showing the relationship between a pressure arm and a separation arm according to the first embodiment. [Figure 6] FIG. 1 is an enlarged perspective view of a pressure arm according to a first embodiment; [Figure 7] 10A to 10C are schematic cross-sectional views illustrating a procedure for installing the paper feed roller unit according to the first embodiment. [Figure 8] FIG. 10 is a schematic diagram illustrating the movement and posture of the paper feed roller unit when the paper feed cassette is inserted into the device body with the paper feed roller unit supported on the slide shaft according to the first embodiment; [Figure 9] FIG. 1 is an enlarged view showing the relationship between the slide shaft and the paper feed roller unit according to the first embodiment. [Figure 10] 1 is a schematic perspective view showing a removal operation of a paper feed roller unit according to a first embodiment, and a corresponding schematic cross-sectional view; [Figure 11] 1 is a schematic cross-sectional view showing the posture of the paper feed roller unit and the engagement state of the engagement boss of the paper feed roller unit and the cap of the pressure arm according to the first embodiment; FIG. [Figure 12] 10A and 10B are schematic cross-sectional views illustrating a procedure for installing a paper feed roller unit according to a second embodiment. [Figure 13] FIG. 10 is a schematic perspective view showing a state in which the pressure arm according to the second embodiment is retracted; [Figure 14] 10A and 10B are schematic cross-sectional views illustrating a procedure for installing a paper feed roller unit according to a third embodiment. [Figure 15] 10A and 10B are schematic cross-sectional views illustrating a procedure for installing a paper feed roller unit according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Example 1 An image forming apparatus will be described below as an example of an apparatus equipped with a sheet feeding device according to the present invention. Here, an electrophotographic monochrome laser beam printer will be used as an example of the image forming apparatus, and the description will be made with reference to the drawings. Although the image forming apparatus of the present invention is applied to a laser beam printer, the present invention is not limited thereto and may also be applied to a copying machine, inkjet printer, or the like. Furthermore, although the present invention is applied to a paper feed unit of the image forming apparatus in this embodiment, the present invention is not limited thereto and may also be applied to an independent sheet feeding device such as an optional feeder that is attached to the image forming apparatus to feed sheets.

[0013] <Overall configuration of image forming apparatus> First, the schematic configuration of image forming apparatus 1 will be described with reference to Figures 1 and 2. Figure 1 is a schematic cross-sectional view of image forming apparatus 1, and Figure 2 is a schematic cross-sectional view showing the configuration of the sheet feeding device. Figure 2(a) shows a state in which sheet feeding cassette 30 is inserted into sheet feeding device 100 (device main body) and stacking plate 32 is lifted up, Figure 2(b) shows a state before stacking plate 32 is lifted up, and Figure 2(c) shows a state in which sheet feeding cassette 30 has been removed from the device main body.

[0014] The image forming apparatus 1 forms an image using an electrophotographic recording method, transporting a sheet S as a recording material to an image forming section 50 to transfer a toner image, transporting the sheet S to a fixing section 6 to fix the toner image, and then discharging the sheet S to a discharge section 9.

[0015] The image forming apparatus 1 has a sheet feeding device 100, an image forming section 50, a fixing section 6, etc. The sheet feeding device 100 is composed of a paper feed cassette 30, a paper feed roller unit 10, etc., and conveys sheets S one by one from a stack of sheets loaded in the paper feed cassette 30 to a pair of intermediate conveying rollers 41.

[0016] The image forming unit 50 includes a photosensitive drum 51, a laser scanner 53 that forms an electrostatic latent image on the photosensitive drum 51, a transfer roller 52, etc. A toner image is formed by supplying toner to the electrostatic latent image formed on the photosensitive drum 51, and the formed toner image is transferred to a sheet S. A fixing unit 6 fixes the toner image onto the sheet S by heating and pressurizing the sheet S onto which the toner image has been transferred.

[0017] In the sheet feeding device 100, the sheets S are separated one by one from a stack of sheets stacked in the sheet cassette 30 and fed to the intermediate conveying roller pair 41. Thereafter, the sheets are fed one by one to the image forming unit 50 via the registration roller pair 42. At this time, the image forming unit starts forming a toner image on the photosensitive drum 51 in accordance with the timing at which the leading edge of the sheet S is detected by the registration sensor 45 disposed downstream of the registration roller pair 42. In this way, by adjusting the timing of image formation in accordance with the timing at which the leading edge of the sheet S passes the registration sensor 45, the toner image is transferred to the sheet S with high accuracy in the image forming unit.

[0018] The sheet S onto which the toner image has been transferred in the image forming unit 50 is conveyed to the fixing unit 6, where the toner image is fixed onto the sheet S. Thereafter, the sheet S is discharged to a discharge unit 9 by a pair of paper discharge rollers 8.

[0019] <Sheet feeding device> Next, the sheet feeding device 100 in this embodiment will be described with reference to Figures 1 and 2. The sheet feeding device 100 conveys a sheet S to a pair of intermediate conveying rollers 41. The sheet feeding device 100 has a paper feeding unit 20 attached to the image forming apparatus 1, a paper feeding drive unit (not shown), and a paper feeding cassette 30 that can be removed from the sheet feeding device 100 to the right in Figures 1 and 2.

[0020] The sheet feed unit 20 has a sheet feed roller unit 10 and a pressure arm 15. In the sheet feed roller unit 10, a pickup roller 12 serving as a second roller and a feed roller 13 serving as a first roller are rotatably held by a roller holder 11. The sheet feed roller unit 10 is also configured to be detachable from the sheet feed unit 20. In other words, it can also be said that the sheet feed roller unit 10 is detachable from the sheet feeding device 100. When the sheet feed roller unit 10 is attached to the sheet feed unit 20, it is held by the sheet feed unit 20 so as to be rotatable about the rotation axis of the feed roller 13. Furthermore, the sheet feed roller unit 10 is urged against the sheet S by a sheet feed pressure urging member 16, which will be described later, via the pressure arm 15.

[0021] When performing a paper feeding operation, the pickup roller 12 is pressed against the sheet S on the stacking plate 32 with a predetermined biasing force (paper feeding pressure) (see FIG. 2(a)). In this embodiment, when the paper feed cassette 20 is removed from the sheet feeding device 100, the pressure arm 15 is configured to swing the pickup roller 12 around the rotation axis of the feed roller 13 in a direction away from the sheet S (FIG. 2(c)). The holding configuration of the paper feed roller unit 10 relative to the paper feed unit 20 and the attachment and detachment operation will be described in detail later.

[0022] The sheet feed cassette 30 is provided with a swingable stacking plate 32 on which sheets S are stacked in a cassette tray 31 serving as a sheet storage section. When the sheet feed cassette 30 is inserted into the sheet feeding device 100, the stacking plate 32 is swung (lifted up) toward the pickup roller 12 by a drive source (not shown).

[0023] The paper feed cassette 30 is also provided with a separation unit 35. The separation unit 35 has a separation roller 36 and a separation spring 37. A small torque limiter is built into the separation roller 36, and a brake is applied with a predetermined torque in the direction of rotation. When the paper feed cassette 30 is attached to the main body, the separation unit 35 is disposed so that the separation roller 36 faces the feed roller 13, and the biasing force of the separation spring 37 presses the separation roller 36 against the feed roller 13.

[0024] By providing the separation unit 35 to the sheet feed cassette 30, the sheet feed roller unit 10 is exposed by removing the sheet feed cassette 30 from the sheet feeding device 100 (FIG. 2(c)). This provides good visibility and easy access when replacing the sheet feed roller unit 10.

[0025] In this embodiment, the parts of the sheet feeding device 100 excluding the paper feed roller unit 10 and the paper feed cassette 30 can be called the device body of the sheet feeding device 100. The pressure arm 15, a paper feed pressure biasing member 16 (described later), a slide shaft 22, a slide bearing 70, a feed shaft 21, a feed bearing 23, and a slide spring 24 are provided in the device body of the sheet feeding device 100. Note that the device body of the sheet feeding device 100 may have a part corresponding to the paper feed cassette 30.

[0026] <Paper feeding operation> Next, the sheet feeding operation of the sheet feeding device 100 will be described. When the sheet feeding cassette 30 is inserted into the sheet feeding device 100, the stacking plate 32 rises, and the sheet S located at the top of the cassette tray 31 serving as a sheet storage section comes into contact with the pickup roller 12 (FIG. 2(a)). At this time, as described above, the pickup roller 12 comes into contact with the sheet S with a predetermined pressure via the pressure arm 15. Thereafter, the pickup roller 12 and the feed roller 13 are driven by a sheet feeding drive unit (not shown) and both rotate counterclockwise in FIG. 2.

[0027] When the pickup roller 12 starts to rotate, the sheet S starts to move to the right in FIG. 2 due to friction between the pickup roller 12 and the sheet S. The sheet S then reaches the separation nip formed by the feed roller 13 and the separation roller 36. This separation nip has the function of separating the sheets S when two or more sheets S are fed to the separation nip by the pickup roller 12 and sending only one sheet downstream in the sheet conveyance direction.

[0028] As described above, the separation roller 36 has a built-in torque limiter, which applies torque as a resistance force in the direction opposite to the conveyance direction of the sheet S. This torque is set so that when there is only one sheet S in the separation nip, the separation roller 36 rotates in response to the feed roller 13, and stops when two sheets S enter the separation nip. Therefore, the sheets S can be separated one by one in the separation nip and conveyed downstream in the conveyance direction of the sheets S. Thereafter, the sheets are conveyed to the pair of intermediate conveyance rollers 41 by the rotation of the pickup roller 12 and the feed roller 13.

[0029] <Configuration of the paper feed roller unit> Next, the paper feed roller unit 10 will be described with reference to Figures 2 and 3. Figure 3 is a schematic perspective view of the paper feed roller unit 10. As shown in Figure 3, the paper feed roller unit 10 has a pickup roller 12, a feed roller 13, a roller holder 11, and an idler gear 14.

[0030] Pickup roller 12 and feed roller 13 are rotatably held by roller holder 11. Pickup roller 12 and feed roller 13 are provided with gear portions 12a and 13a, respectively, and gear portions 12a and 13a of each roller are connected by an idler gear 14. This idler gear 14 is also rotatably supported by roller holder 11.

[0031] The feed roller 13 is provided with a coupling hole 13b and a slide shaft engaging portion 71, and a coupling portion 21b of the feed shaft 21 (described later) is inserted into the coupling hole 13b for coupling. The rotational drive from the feed shaft 21 is input to the feed roller 13, and the pickup roller 12 is driven in conjunction with the rotation via the idler gear 14.

[0032] Next, the shape of the roller holder 11 will be described. The roller holder 11 is provided with an engagement boss 11a, a cam portion 11b, and a bearing engagement portion 11c. The engagement boss 11a, which serves as a second engagement portion, engages with the pressure arm 15 when the sheet feed roller unit 10 is attached to the device body. When the sheet feed cassette 30 is removed from the sheet feeding device 100, the pickup roller 12 rotates in a direction away from the sheet S.

[0033] The cam portion 11b comes into contact with a rib 22b of a slide shaft 22 serving as a holding member, which will be described later, and controls the posture of the sheet feed roller unit 10 after the sheet feed roller unit 10 is attached to the sheet feeding device 100. The functions of the cam portion 11b and the rib 22b of the slide shaft 22 will be described in detail later.

[0034] <Paper feed unit configuration> Next, the paper feed unit 20 to which the paper feed roller unit 10 is attached will be described with reference to Figures 4 and 5. Figure 4 is a schematic perspective view showing the configuration of the paper feed unit 20, with Figure 4(a) showing the state in which the paper feed roller unit 10 is attached and Figure 4(b) showing the state in which the paper feed roller unit 10 is removed. Figure 5 is a diagram showing the relationship between the pressure arm 15 and the separation arm 25, and is an exploded perspective view of the pressure arm 15 and the separation arm 25.

[0035] The paper feed unit 20 has a feed shaft 21, a slide shaft 22, a feed bearing 23, a slide bearing 70, and a pressure arm 15. In this embodiment, the slide bearing 70 is integrated with the slide shaft 22 and can be said to be part of the slide shaft 22. The paper feed roller unit 10 engages with the slide shaft 22 at the portion where the slide bearing 70 is located. In other words, the slide shaft 22 and the slide bearing 70 both function as holding members.

[0036] In the direction of the rotation axis of the feed roller 13, the feed shaft 21 and the feed bearing 23 are disposed on one end side of the feed roller 13, and the slide shaft 22 and the slide bearing 70 are disposed on the other end side of the feed roller 13. In this embodiment, the feed shaft 21, the slide shaft 22, and the slide bearing 70 are disposed so as to overlap with the rotation axis of the feed roller 13.

[0037] Feed bearing 23 engages with bearing engagement portion 11c. Coupling portion 21b at the tip of feed shaft 21 is inserted into coupling hole 13b of feed roller 13 described above, and transmits rotational driving force from a paper feed drive (not shown) to feed roller 13. A slide shaft 22 is disposed on the other end of feed roller 13, and is biased in the direction of the rotation axis of feed roller 13 (direction P in FIG. 4) by slide spring 24, which serves as a shaft biasing member. Slide shaft 22 engages with slide shaft engagement portion 71.

[0038] This biasing force holds the feed roller unit 10 between the feed bearing 23 and the slide bearing 70, and supports it so that it can swing around the rotation axis of the feed roller 13. The direction in which the slide spring 24 biases the slide shaft 22 and the direction in which the slide shaft 22 moves to engage with the feed roller unit 10 are called the first direction. In other words, the slide spring 24 biases the slide shaft 22 in the first direction.

[0039] The coupling hole 13b, the slide shaft engaging portion 71, and the bearing engaging portion 11c function as a first engaging portion of the paper feed roller unit 10. The feed bearing 23, the slide shaft 22 including the slide bearing 70, and the feed shaft 21 function as a first engaged portion.

[0040] The pressure arm 15 controls the phase of the swingably supported paper feed roller unit 10, and functions to urge the pickup roller 12 toward the sheet S during paper feeding. In other words, the pressure arm 15 functions to press the paper feed roller unit 10 toward the sheets stored in the cassette tray 31. The pressure arm 15 is supported so that it can swing about a fulcrum Q. One end of the pressure arm 15 engages with the boss 11a of the paper feed roller unit 10. The other end is urged by a paper feed pressure urging member 16, which is a tension coil spring. The force of this paper feed pressure urging member 16 becomes the urging force (paper feed pressure) of the pickup roller 12 toward the sheet S. The configuration of the pressure arm 15 and the function of each part will be described in detail later.

[0041] In this embodiment, a separation mechanism is provided that rotates the sheet feed roller unit 10 in a direction away from the sheets S in conjunction with the removal of the sheet feed cassette 30 from the device body. Regarding this configuration, first, a state in which the sheet feed cassette 30 is removed from the device body will be described.

[0042] The pressure arm 15 is supported relative to the apparatus body so as to be rotatable about a rotation axis Q. One end of the pressure arm 15, which is farther from the sheet feed roller unit 10 in the width direction of the sheet S, which is perpendicular to the conveyance direction of the sheet S, is urged upward in the vertical direction by a sheet feed pressure urging member 16. A cap 18 serving as a second engaged portion that engages with an engagement boss 11a serving as a second engaging portion is disposed at the one end of the pressure arm 15 closer to the sheet feed roller unit 10 in the width direction of the sheet S. When the engagement boss 11a and the cap 18 are engaged with each other, when the sheet feed pressure urging member 16 pulls the pressure arm 15 upward, the cap 18 located on the opposite side of the rotation axis Q moves downward.

[0043] Therefore, when the end of pressure arm 15 farther from sheet feed roller unit 10 moves upward while sheet feed cassette 30 is attached to the device body, pickup roller 12 moves downward. Also, as will be described in detail later, when sheet feed cassette 30 is removed from the device body, pickup roller 12 rotates in a direction away from sheet S as shown in FIG. 2(c).

[0044] The following describes the configuration of the separation arm 25, which moves the pickup roller 12 upward in the vertical direction in conjunction with the removal operation of the paper feed cassette 30 from the device body. One end of the separation arm 25, which is farther from the paper feed roller unit 10 in the width direction of the sheets S, is biased downward in the vertical direction by a separation spring 26. In addition, one end, which is closer to the paper feed roller unit 10 in the width direction of the sheets S, is supported by the device body on a rotation axis Q of the pressure arm 15, and the separation arm 25 can also rotate about the rotation axis Q separately from the pressure arm 15. The upper ends of the paper feed pressure biasing member 16 and the separation spring 26 in the vertical direction are engaged with the device body.

[0045] The separation arm 25 is also provided with an arm engaging portion 25b that abuts against the pressure arm 15 and controls the rotation of the pressure arm 15. The arm engaging portion 25b is arranged so as to overlap with the movement trajectory of the pressure arm 15 when the pressure arm 15 rotates around the rotation axis Q. This prevents the end of the pressure arm 15 farther from the sheet feed roller unit 10 in the width direction of the sheet S from moving upward in the vertical direction relative to the end of the separation arm 25 farther from the sheet feed roller unit 10.

[0046] In this embodiment, the separating spring 26 is set to have a greater biasing force than the sheet feed pressure biasing member 16. Therefore, when the sheet feed cassette 30 is removed from the main body of the apparatus, the separating arm 25 is biased by the separating spring 26, and the biased end moves downward in the vertical direction. At the same time, the arm engaging portion 25b biases the pressure arm 15, so that the end of the pressure arm 15 that is biased by the sheet feed pressure biasing member 16 moves downward in the opposite direction to the direction in which the sheet feed pressure biasing member 16 biases and rotates the arm. With this configuration, when the sheet feed cassette 30 is removed from the main body of the apparatus, the pickup roller 12 moves and is held upward in the vertical direction.

[0047] Next, the relationship between the pressure arm 15 and the separating arm 25 when the paper feed cassette 30 is installed in the apparatus body will be described. The separating arm 25 is provided with a cassette contact portion 25a. When the paper feed cassette 30 is installed in the apparatus body, a contact portion (not shown) provided on the paper feed cassette 30 comes into contact with the cassette contact portion 25a of the separating arm 25, and the cassette contact portion 25a is lifted upward as the paper feed cassette 30 is installed. As a result, the end of the separating arm 25 farther from the paper feed roller unit 10 moves upward in the vertical direction.

[0048] Then, arm engaging portion 25b no longer biases pressure arm 15 downward relative to the vertical direction, so the end of pressure arm 15 farthest from paper feed roller unit 10 also rotates upward by paper feed pressure biasing member 16, and pickup roller 12 rotates downward. Then, pickup roller 12 descends to a predetermined position and stops. When stacking plate 32 rotates by attaching paper feed cassette 30 to the device main body, pickup roller 12 and sheet S come into contact with each other, and sheet S is biased with a predetermined pressure.

[0049] <Configuration of pressure arm> Next, the configuration of the pressure arm, which is a characteristic feature of the present invention, will be described with reference to Figures 6 and 7. Figure 6 is an enlarged perspective view of pressure arm 15. Figure 7 is a schematic cross-sectional view showing the procedure for installing paper feed roller unit 10. Pressure arm 15 has arm portion 17, cap 18 (second engaged portion), and cap spring 19. Arm portion 17 is configured to be rotatable about rotation axis Q, so that the entire pressure arm 15 can rotate about rotation axis Q. One end of rotation axis Q of arm portion 17 is provided with spring hook portion 17a to which paper feed pressure biasing member 16 is attached. One end of rotation axis Q of arm portion 17 is pressed against arm engaging portion 25b.

[0050] A cap 18 is attached to the other end of the rotation axis Q of the arm portion 17. In other words, the arm portion 17 has an attachment portion for attaching the cap 18. The cap 18 engages with an engagement boss 11a of the paper feed roller unit 10. The cap 18 is attached to the arm portion 17 so as to be slidable in the U direction in FIG. 6 while being biased by a cap spring 19 serving as a biasing member. The cap 18 is arranged so as to be movable relative to the arm portion 17 in the direction opposite to the U direction against the biasing force of the cap spring 19. The cap 18 also has a tapered portion 18c as an inclined portion and a recessed portion 18a as a restricting groove, as shown in FIG. 7.

[0051] Tapered portion 18c has the function of being pressed by engagement boss 11a of sheet feed roller unit 10 during the installation operation of sheet feed roller unit 10, which will be described later, to generate a force that moves cap 18 in the direction opposite to the U direction in Figure 6. Recess 18a has restriction surface 18d, which acts when pickup roller 12 is in contact with sheet S and has the function of restricting axial movement of sheet feed roller unit 10. The function of recess 18a will be described in detail later.

[0052] <Installing the paper feed roller unit 10> Next, the operation of attaching the sheet feed roller unit 10 to the sheet feed unit 20 will be described with reference to FIG. 7. In FIG. 7, the left side shows the posture of the sheet feed roller unit 10, and the right side shows the relationship between the engagement boss 11a and the pressure arm 15. FIG. 7(a) shows a state in which the sheet feed roller unit 10 is held between the slide bearing 70 and the feed bearing 23 and is not engaged with the pressure arm 15. FIG. 7(b) shows the posture of the sheet feed roller unit 10 while it is rotating, and shows the state after the sheet feed cassette 30 is inserted into the sheet feeding device 100 in the first state described below. FIG. 7(c) shows a state in which the sheet feed roller unit 10 has been rotated and is in contact with the pressure arm 15. FIG. 7(d) shows a state in which the cap 18 has been retracted. FIG. 7(e) shows the state in which the sheet feed roller unit 10 has been attached.

[0053] To install the paper feed roller unit 10, first, the paper feed roller unit 10 is engaged with the slide shaft 22, the feed bearing 23, and the feed shaft 21 at an arbitrary phase. Then, the feed roller 13 is rotated around its rotation axis to engage the paper feed roller unit 10 with the pressure arm 15.

[0054] First, the operator moves the slide shaft 22 in a direction against the slide spring pressure f1. Then, the feed bearing 23 and the bearing engaging portion 11c engage, and the coupling portion 21b of the feed shaft 21 engages with the coupling hole 13b of the feed roller 13. The slide shaft 22 including the slide bearing 70 moves due to the slide spring pressure f1 and engages with the slide shaft engaging portion 71. As a result, the sheet feed roller unit 10 is attached between the slide bearing 70 and the feed bearing 23. At this time, the phase (posture, inclination) of the sheet feed roller unit 10 is arbitrary ( FIG. 7( a) ). The direction opposite (opposite direction) to the direction of the slide spring pressure f1 (first direction) is defined as the second direction.

[0055] The first state of the paper feed roller unit 10 is when the paper feed roller unit 10 is mounted between the slide bearing 70 and the feed bearing 23, and the engagement boss 11a is not engaged with the pressure arm 15. In the first state, the feed bearing 23 is engaged with the bearing engagement portion 11c, the coupling portion 21b of the feed shaft 21 is engaged with the coupling hole 13b of the feed roller 13, and the slide shaft 22 including the slide bearing 70 is engaged with the slide shaft engagement portion 71. Meanwhile, the engagement boss 11a is not engaged with the pressure arm 15. When the paper feed roller unit 10 is then rotated around the rotation axis of the feed roller 13 toward the pressure arm 15, the engagement boss 11a of the paper feed roller unit 10 comes into contact with the cap 18 of the pressure arm 15 (FIGS. 7(b)-(c)).

[0056] In the first state, the feed roller unit 10 is pressed toward the feed bearing 23 by the slide spring pressure f1 of the slide spring 24 that biases the slide shaft 22. In this state, movement of the feed roller unit 10 in the rotational axis direction of the feed roller 13 (parallel to the rotational axis direction of the pick roller 12) is restricted by the slide spring 24. As a result, the position of the engagement boss 11a overlaps with the positions of the tapered portion 18c and the recessed portion 18a of the cap 18 in the rotational axis direction of the feed roller 13.

[0057] As described above, the cap 18 is biased in the U direction. The cap 18 has a tapered portion 18c. When the engagement boss 11a presses the tapered portion 18c as shown in FIG. 7(c), the cap 18 receives a force in the right direction in the figure as shown in FIG. 7(d), and moves rightward. In other words, when the engagement boss 11a moves to engage with the cap 18, the tapered portion 18c is inclined so as to retreat in the opposite direction to the biasing direction of the cap 18. The movement direction of the cap 18 at this time is a direction intersecting the rotation direction of the pressure arm 15 around the rotation axis Q (the same as the rotation direction of the arm portion 17). The cap 18 moves in a direction intersecting the rotation axis Q, away from the rotation axis Q.

[0058] The position where the cap 18 is not retracted (the position in Figure 7(a)) is defined as the normal position. The cap spring 19 urges the cap 18 to be in the normal position. In the direction intersecting the rotation axis Q, the cap spring 19 urges the cap 18 in a direction that moves the cap 18 closer to the rotation axis Q. As a result, the cap 18 moves closer to the rotation axis Q and returns to the normal position. When the cap 18 is in the normal position, the cap spring 19 continues to urge the cap 18, but a part of the cap 18 (the abutment portion) abuts against the arm portion 17, thereby positioning the cap 18.

[0059] Therefore, by rotating the paper feed roller unit 10 from the state shown in FIG. 7(c) toward the pressure arm 15, the cap 18 is retracted in the direction opposite to U (FIG. 7(d)). This retracted position of the cap 18 is defined as the retracted position. Further rotation of the paper feed roller unit 10 toward the pressure arm 15 causes the engagement boss 11a to enter the inside of the cap 18, return to its normal position, and engage with the pressure arm 15 (FIG. 7(e)).

[0060] As described above, the first state refers to a state in which the feed bearing 23 and the bearing engagement portion 11c, the coupling portion 21b and the coupling hole 13b, and the slide shaft 22 and the slide shaft engagement portion 71 are engaged, and the engagement boss 11a and the pressure arm 15 are not engaged. In other words, the first state refers to a state of the sheet feed roller unit 10 in which the first engagement portion and the first engaged portion are engaged, and the second engagement portion and the second engaged portion are not engaged. This position of the sheet feed roller unit 10 is also referred to as the first position. Furthermore, the second position refers to a position in which the first engagement portion and the first engaged portion of the sheet feed roller unit 10 are engaged, and the second engagement portion and the second engaged portion are also engaged.

[0061] As described above, the sheet feed roller unit 10 can be moved from the first position to the second position by rotating about the coupling hole 13b, the slide shaft engaging portion 71, and the bearing engaging portion 11c. The second engaged portion is located in a normal position when the sheet feed roller unit 10 is in the second position. When the sheet feed roller unit 10 moves from the first position to the second position, the second engaging portion presses against the second engaged portion, causing the second engaged portion to swing to a retracted position where it is retracted from the movement trajectory of the second engaging portion.

[0062] In this way, by installing the paper feed roller unit 10 in two steps, first engaging the slide bearing 70 and the feed bearing 23, and then engaging the pressure arm 15, it is possible to concentrate on each task, and the work involved in replacing the paper feed roller unit 10 is easy.

[0063] However, when installing the sheet feed roller unit 10 in two steps like this, it is desirable that the sheet feed roller unit 10 be automatically installed even if the second step is not performed. In this embodiment, if the sheet feed cassette 30 is inserted with only the feed bearing 23, the slide shaft 22 including the slide bearing 70, and the feed shaft 21 engaged with the sheet feed roller unit 10, the sheet feed roller unit 10 engages with the pressure arm 15.

[0064] The details of the configuration will be described with reference to Figures 7, 8, and 9. Figure 8 is a schematic diagram showing the movement and posture of the sheet feed roller unit 10 when the sheet feed cassette 30 is inserted into the sheet feeding device 100 with the sheet feed roller unit 10 supported on the slide shaft 22. Figures 8(a) and 8(b) show the state in the middle of inserting the sheet feed cassette 30. The postures of the sheet feed roller unit 10 in Figures 8(a) and 8(b) correspond to those in Figures 7(a) and 7(b), respectively. Figure 9 is an enlarged view showing the relationship between the slide shaft 22 and the sheet feed roller unit 10 in the states of Figures 8(a) and 8(b), and is an enlarged view of the X portion of Figure 10.

[0065] Assume that an operator has engaged the sheet feed roller unit 10 with the feed bearing 23, the slide shaft 22 including the slide bearing 70, and the feed shaft 21 in the device main body as shown in FIG. 7A. In this state, the operator inserts the sheet feed cassette 30 from the right side in FIG. 8. The cassette tray 31 of the sheet feed cassette 30 is provided with a lifting portion 31a. During the process of inserting the sheet feed cassette 30 into the sheet feeding device 100, the lifting portion 31a comes into contact with the sheet feed roller unit 10, causing the sheet feed roller unit 10 to rotate clockwise in the drawing around the rotation axis of the feed roller 13.

[0066] This lifting portion 31a is provided at the highest position in the vertical direction among the portions that pass under the sheet feed roller unit 10 during the insertion process of the sheet cassette 30. For example, it can be formed on the wall on the upstream side of the sheet feed cassette 30 in the transport direction, or on the sheet regulating plate 33. When the lifting portion 31a passes under the sheet feed roller unit 10 in the first state, the sheet feed roller unit 10 is held in the position shown in Figure 8(b). This holding may be achieved by utilizing the frictional force between the slide shaft engaging portion 71 and the slide bearing 70 due to the slide spring pressure f1.

[0067] In this embodiment, as shown in Figure 9, the cam portion 11b and the rib 22b of the slide shaft 22 are engaged with each other, so that the slide shaft 22 does not return to the position shown in Figure 8(b) from the position shown in Figure 8(a). This configuration will be described in detail.

[0068] In the state shown in Fig. 8(a), the relationship between the slide shaft 22 and the cam portion 11b of the sheet feed roller unit 10 is as shown in Fig. 9(a). The slide shaft 22 is biased in the direction P in Fig. 9 by the slide spring pressure f1. During the insertion process of the sheet feed cassette 30, the sheet feed roller unit 10 rotates in the rotation direction shown in the figure due to the lifting portion 31a of the sheet feed cassette 30, and transitions from the state shown in Fig. 9(a) to the state shown in Fig. 9(b).

[0069] When the sheet feed cassette 30 is inserted and the state transitions from FIG. 8(a) to FIG. 8(b), the relationship between the slide shaft 22 and the cam portion 11b of the sheet feed roller unit 10 becomes the state shown in FIG. 9(b). Because the slide shaft 22 is biased in the direction P, when the sheet feed roller unit rotates in the direction opposite to the rotation direction, the cam portion 11b gets caught on the rib 22b of the slide shaft 22, preventing the sheet feed roller unit 10 from returning to the state (a) from FIG. 9(b). In other words, the rib 22b holds the sheet feed roller unit 10 at a position between the first position and the second position. This position is referred to as the third position.

[0070] When the insertion of the sheet feed cassette 30 into the sheet feeding device 100 is completed, the stacking plate 32 rises, and the sheet S comes into contact with the pickup roller 12. Then, through the process shown in Figures 7(c) to 7(e), the sheet S rotates the sheet feed roller unit 10 to the second position.

[0071] At this time, the force that engagement boss 11a applies to tapered portion 18c is a reaction force of pickup roller 12 pressing sheet S, and is produced by paper feed pressure biasing member 16. The force that engagement boss 11a applies to tapered portion 18c biases cap 18 from the normal position toward the retracted position against the biasing force of cap spring 19. Here, cap spring 19 biases cap 18 from the retracted position toward the normal position. If the biasing force of cap spring 19 is greater than the force with which engagement boss 11a biases cap 18 toward the retracted position, engagement boss 11a cannot engage with cap 18.

[0072] Therefore, the force of the cap spring 19 is set to be small, and when the pickup roller 12 presses the sheet S by the sheet feeding pressure biasing member 16, the cap 18 moves to the retracted position.

[0073] In this manner, in this embodiment, when the sheet feed roller unit 10 is in the first state, the sheet feed cassette 30 is inserted and the stacking plate 32 rises, automatically engaging the engaging boss 11a with the cap 18. As a result, the sheet feed roller unit 10 enters the second state.

[0074] As described above, according to this embodiment, after attaching the sheet feed roller unit 10 to the feed bearing 23, the slide shaft 22 including the slide bearing 70, and the feed shaft 21 at any phase, the sheet feed roller unit 10 can be attached by rotating the sheet feed roller unit 10 toward the pressure arm 15. For this purpose, the tapered portion 18c of the pressure arm 15 and the engagement boss 11a of the sheet feed roller unit 10 are configured to abut against each other during the rotation of the sheet feed roller unit 10. Furthermore, when the engagement boss 11a presses the tapered portion 18c, the cap 18 retracts, and when the engagement boss 11a is attached to the pressure arm 15, the cap 18 returns to its original position.

[0075] Therefore, after attaching the sheet feed roller unit 10 to the slide shaft 22, feed bearing 23, and feed shaft 21, the operator can simply rotate the sheet feed roller unit 10 to engage the sheet feed roller unit 10 with the pressure arm 15. In other words, the sheet feed roller unit 10 can be easily attached. In this embodiment, this function can be achieved by a retractable configuration for the engagement portion (cap 18) of the pressure arm 15 with the sheet feed roller unit 10. Therefore, usability for replacing the sheet feed roller unit 10 can be improved at low cost and in a space-saving manner.

[0076] <Removing the paper feed roller unit 10> Next, the operation of removing the paper feed roller unit 10 in this embodiment will be described with reference to Figure 10. Figure 10 is a schematic perspective view showing the operation of removing the paper feed roller unit 10, and a corresponding schematic cross-sectional view. The schematic cross-sectional views in (a) to (c) represent the cross-sectional view taken along line B-B in Figure 7, with (a) showing the installed state of the paper feed roller unit 10, and (b) and (c) showing the process of removing the paper feed roller unit 10 from the paper feed unit 20.

[0077] In this embodiment, the sheet feed roller unit 10 can be accessed and removed from the downstream side in the conveyance direction of the sheet S (the right side in FIGS. 1 and 2). When an operator such as a user or a service person removes the sheet feed roller unit 10 from the sheet feeding device 100, the sheet feed cassette 30 is removed from the main body.

[0078] This exposes the paper feed roller unit 10, allowing the operator to access it (FIG. 10(a)). At this time, the paper feed roller unit 10 is held by the slide bearing 70, feed bearing 23, and cap 18. The operator grasps the paper feed roller unit 10 at any position and moves the slide shaft 22 against the pressure of the slide spring 24 to move the paper feed roller unit 10 in the direction of the arrow in FIG. 10 (second direction). At this time, the cap 18 is in its normal position.

[0079] Then, the coupling hole 13b and the feed shaft 21 are disengaged, and the bearing engaging portion 11c and the feed bearing 23 are disengaged, and the engaging boss 11a also moves in the direction of the arrow (left) (FIG. 10(b)). At this time, as shown in the cross-sectional view of FIG. 10(b), the engaging boss 11a is in a position where it has been released from the cap 18 of the pressure arm 15.

[0080] 10(c) (a direction intersecting the rotation axis of the feed roller 13), the engagement between the paper feed roller unit 10 and the pressure arm 15 is also released. Then, by releasing the engagement between the slide shaft 22 and the paper feed roller unit 10, the paper feed roller unit 10 can be removed. In other words, the paper feed roller unit 10 can be removed from the device main body by moving it in the second direction.

[0081] The installation of the sheet feed roller unit 10 can also be performed by reversing the removal procedure described above. However, in the reverse procedure of the removal procedure, the sheet feed roller unit 10 must be installed on the slide shaft 22 while controlling its position (tilt) in order to engage the sheet feed roller unit 10 with the pressure arm 15.

[0082] <Using force of slide spring 24> When sliding the sheet feed roller unit 10, the operator must move the sheet feed roller unit 10 against the pressure of the slide spring 24 that biases the slide shaft 22. Therefore, it is desirable that the biasing force of the slide spring 24 be low from the viewpoint of ease of installation and removal of the sheet feed roller unit 10. However, it is necessary to hold the sheet feed roller unit 10 with a certain amount of force so that the sheet feed roller unit 10 does not move due to skew of the sheet S, operation of the sheet feed roller unit 10, or removal of a jam from downstream in the transport direction. In this embodiment, a unique configuration is provided in the cap 18 of the pressure arm 15 to achieve both of the above-mentioned conflicting objectives.

[0083] This configuration will be explained using Figure 11. Figure 11 is a schematic cross-sectional view showing the attitude of the paper feed roller unit 10 and the engagement state between the engagement boss 11a of the paper feed roller unit 10 and the cap 18 of the pressure arm 15. Figure 11(a) shows the state during paper feeding operation, and (b) shows the state after the paper feed cassette 30 has been removed, which correspond to (a) and (c) in Figure 2, respectively.

[0084] As mentioned above, a certain holding force is required to prevent the sheet feed roller unit 10 from moving in the removal direction during sheet feeding or jam clearance. Figure 11(a) shows the state in which the sheet feed cassette 30 is inserted into the main body and the pickup roller 12 is pressing against the sheet S. The sheet feed roller unit 10 is held in the direction P in the schematic diagram on the right by the pressure of the slide spring 24, and the sheet feed roller unit 10 can be removed by moving it to the left in the drawing. In the present invention, as shown in Figure 11(a), when the pickup roller 12 is pressing against the sheet S, the engagement boss 11a of the sheet feed roller unit 10 fits into the recess 18a of the cap 18 of the pressure arm 15.

[0085] In this way, engagement boss 11a is positioned so as to fit into recess 18a when pickup roller 12 and sheet S move upward in the vertical direction due to contact between the pickup roller 12 and sheet S. Recess 18a is positioned by the contact portion of cap 18 contacting arm portion 17.

[0086] When the pickup roller 12 and the sheet S are in contact with each other, a sheet feed pressure N is applied to the engagement boss 11a by the sheet feed pressure biasing member 16. Therefore, when the sheet feed roller unit 10 is moved leftward in the figure, the engagement boss 11a and the regulating surface 18d come into contact with each other, and in addition to the slide spring pressure f1, a force f2 is required to overcome the recess 18a. The slide spring pressure f1 and the recess shape are determined so that this f1 + f2 is a sufficient holding force during sheet feeding and jam clearance. Specifically, the regulating surface 18d is inclined with respect to the axial direction of the feed roller 13 and the vertical direction.

[0087] FIG. 11(b) shows a state in which the sheet feed cassette 30 is removed from the sheet feeding device 100. When an operator such as a user or service person replaces the sheet feed roller unit 10, the operation is performed in this state. At this time, the sheet feed roller unit 10 is lifted by the pressure arm 15 due to the action of the separation mechanism as described above. Therefore, as shown in FIG. 11(b), the engagement boss 11a is in a state in which it is disengaged from the recess 18a (the engagement boss 11a is separated from the recess 18a and the regulating surface 18d). Therefore, in order to move the sheet feed roller unit 10 to the left in the figure, the sheet feed roller unit 10 can be moved only by the force resisting the slide spring pressure f1.

[0088] In other words, when the pickup roller 12 is urged toward the sheet S by the pressure arm 15, the regulating surface 18d comes into contact with the engaging boss 11a, thereby regulating the movement of the engaging boss 11a in the axial direction. When the pressure arm 15 is not urged toward the sheet, the engaging boss 11a and the recess 18a do not come into contact. Furthermore, the regulating surface 18d is released from regulation when the pickup roller 12 is not urged toward the sheet S by the pressure arm 15. This makes it possible to both ensure the holding force of the sheet feed roller unit 10 during use and reduce the operating force required for removal.

[0089] If the movement of the sheet feed roller unit 10 during a paper feed operation or jam clearance is restricted by the slide spring pressure f1 alone, the slide spring pressure f1 needs to be increased. On the other hand, according to the configuration of this embodiment, the movement of the sheet feed roller unit 10 can be restricted by the recess 18a during a paper feed operation or jam clearance (when the pickup roller 12 comes into contact with the sheet S). Therefore, compared to when the movement of the sheet feed roller unit 10 is restricted by the slide spring pressure f1 alone during a paper feed operation or jam clearance, the slide spring pressure f1 can be reduced.

[0090] In this embodiment, the resistance shape during use is realized by providing a boss 11a on the paper feed roller unit 10 and a recess 18a on the pressure arm 15 side. However, the present invention is not limited to this, and any shape of resistance is possible as long as it acts in the direction of movement under pressure. For example, a configuration in which a recess is provided on the paper feed roller unit side and a protrusion is provided on the pressure arm side is also possible. Furthermore, the width of the recess 18a in the direction of the rotation axis may be larger than the width of the engagement boss 11a, so that the engagement boss 11a abuts against the recess 18a when it moves a predetermined distance in the first direction.

[0091] Furthermore, according to this embodiment, when the sheet feed roller unit 10 is pressed against the sheet S, the engagement boss 11a of the sheet feed roller unit 10 fits into the recess 18a of the pressure arm 15, and when the sheet feed roller unit 10 is removed, the engagement boss 11a disengages from the recess 18a. Therefore, since the resistance force of the recess 18a ensures the holding force of the sheet feed roller unit 10 during sheet feeding, the pressure f1 of the slide spring 24 can be reduced. As a result, the operating force of the slide shaft when replacing the sheet feed roller unit 10 can be reduced.

[0092] <Example 2> In the above-described first embodiment, the engagement boss 11a (convex) is provided on the paper feed roller unit 10 side, and the recess 18a is provided on the pressure arm 15. Also, a configuration has been described in which the paper feed roller unit 10 is rotated to abut against the pressure arm 15, and the cap 18 is retracted. In this embodiment, a configuration in which an engagement boss 115a (convex) as a second engaged portion is provided on the pressure arm 115 side, and an engagement slit 111a as a second engaging portion is provided in the roller holder 111 of the paper feed roller unit 110 will be described using Figures 12 and 13. Furthermore, a configuration in which a recess 111c is provided in the engagement slit 111a on the paper feed roller unit 110 side will be described.

[0093] Fig. 12 is a schematic cross-sectional view showing the procedure for installing the paper feed roller unit 111, with the posture of the paper feed roller unit 111 shown on the left and the relationship between the pressure arm 115 and the paper feed roller unit 111 shown on the right. Fig. 13 is a perspective view showing the state when the pressure arm 115 is retracted. Note that parts common to the first embodiment are given the same reference numerals and their description will be omitted.

[0094] Figure 12(a) shows a state in which the paper feed roller unit 111 is held between the slide bearing 70 and the feed bearing 23 and is not engaged with the pressure arm 15. Figure 12(b) shows a state in which the paper feed roller unit 110 has been rotated and the pressure arm has been retracted. Figure 12(c) shows a state in which the paper feed roller unit 110 has been completely installed.

[0095] In this embodiment, roller holder 111 of paper feed roller unit 110 is provided with engagement slit 111a that engages with engagement boss 115a of pressure arm 115, and a recess 111c is provided inside engagement slit 111a. Furthermore, roller holder 111 is provided with tapered portion 111b for retracting pressure arm 115 in the direction of the arrow in Figure 13 during the installation operation of paper feed roller unit 110.

[0096] The tapered portion 111b is inclined so as to retract the pressure arm 115 during the installation operation of the paper feed roller unit 110, which will be described later. Specifically, the tapered portion 111b is configured to extend vertically from the top to the bottom in the direction of the engagement boss 115a when attached to the device body.

[0097] The pressure arm 115 is provided with an engagement boss 115a that fits into the engagement slit 111a of the paper feed roller unit 110 and engages with the paper feed roller unit 110, and is held rotatably about the rotation axis Q, as in the first embodiment. Furthermore, the pressure arm 115 is flexible so that the engagement boss 115a can be retracted in the direction of the rotation axis Q and away from the paper feed roller unit 110 (the direction of the arrow in FIG. 13).

[0098] The operation of installing the paper feed roller will now be described. As in the first embodiment, the operator moves the slide shaft 22 in a direction that resists the slide spring pressure f1, and installs the paper feed roller unit 110 between the slide bearing 70 and the feed bearing 23. At this time, the phase of the paper feed roller unit 110 is arbitrary.

[0099] Thereafter, when the sheet feed roller unit 110 is rotated around the rotation axis of the feed roller 13 toward the pressure arm 115, the tapered portion 110b of the sheet feed roller unit 110 comes into contact with the tip of the engagement boss 115a of the pressure arm 115. When the sheet feed roller unit 110 is then further rotated toward the pressure arm 115, the pressure arm 115 is pushed by the tapered portion 110b of the sheet feed roller unit 110, and the pressure arm 115 bends in the direction of the arrow as shown in Figure 13. The pressure arm 115 then returns to its original position due to its own elastic force, and the engagement boss 115a of the pressure arm 115 engages with the engagement slit 111a of the sheet feed roller unit 110.

[0100] In this embodiment as well, when the force of the paper feed pressure biasing member 16 is applied to the pressure arm 115, the pressure arm 115 bends and retracts before the pressure arm 115 rotates the roller unit 110. Also, as in the first embodiment, when the paper feed roller unit 110 is in the first state and the paper feed cassette 30 is installed, the paper feed roller unit 110 is completely installed.

[0101] In this embodiment, a recess 110c is provided on the side of the sheet feed roller unit 110, and when sheet feed pressure N is applied from the pressure arm 115, the engagement boss 115a of the pressure arm 115 fits into the recess 110c. This ensures the necessary holding force for the sheet feed roller unit 110. The state shown in FIG. 12(c) is a state in which the stacking plate 32 is raised and sheet feed pressure N is applied to the sheet S by the pick roller 12. In this state, sheet feed pressure N is applied to the recess 110c by the sheet feed pressure applying member 16 via the engagement boss 115a.

[0102] Therefore, to move the sheet feed roller unit 110 in the retraction direction of the slide shaft 22, in addition to the pressure f1 of the slide spring 24, a force f3 is required for the engagement boss 115a to overcome the recess 111c. As in the first embodiment, the pressure of the slide spring 24 and the recess shape are determined so that this force is sufficient to hold the sheet during paper feed operation and jam clearance. On the other hand, when removing the sheet feed roller unit 110, the engagement boss 115a of the pressure arm 115 is disengaged from the recess 111c, as in the first embodiment. Therefore, when removing the sheet feed roller unit 110, it can be moved only by the force resisting the pressure f1 of the slide spring 24.

[0103] In this way, by providing a resistance shape (recess 111c) that acts only when the paper feed roller unit 110 is pressed against the pressure arm 115, it is possible to ensure the holding force of the paper feed roller unit 110 during paper feeding and reduce the operating force required to remove the paper feed roller unit 110.

[0104] As explained above, in this embodiment as well, when the sheet feed roller unit 110 is pressed against the sheet S, the engagement boss 115a of the pressure arm 115 fits into the recess 111c of the sheet feed roller unit 110, and when the sheet feed roller unit 110 is removed, the engagement boss 115a disengages from the recess 111c. Therefore, during use, the force f3 described above ensures the holding force of the sheet feed roller unit 110, while the pressure f1 of the slide spring 24 can be reduced. As a result, the operating force required when replacing the sheet feed roller unit 110 can be reduced.

[0105] Furthermore, by performing the installation steps of the paper feed roller unit 110 in two steps, engaging it with the slide shaft 22 and engaging it with the pressure arm 115, it is possible to concentrate on each task, which improves the workability of replacing the paper feed roller unit 110.

[0106] Furthermore, this function can be achieved simply by retracting the engaging portion of the pressure arm 115 with the paper feed roller unit 110. Therefore, usability for replacing the paper feed roller unit can be improved at low cost and in a space-saving manner. Furthermore, although this embodiment requires space for the pressure arm to bend, there is no need to separate the pressure arm as in the first embodiment, which allows for further cost reduction.

[0107] Example 3 In the above-described first and second embodiments, the configuration in which the feed roller unit rotates and contacts the pressure arm, and then the pressure arm retracts, has been described. In this embodiment, the configuration in which the boss on the feed roller side retracts will be described with reference to Figure 14. Note that parts common to the first and second embodiments are given the same reference numerals, and their description will be omitted.

[0108] 14 is a schematic cross-sectional view showing the procedure for installing the paper feed roller unit 210. The left side shows the posture of the paper feed roller unit 210, and the right side shows an enlarged view showing the relationship between the engagement member 212, the boss 212a (second engagement portion) of the engagement member, and the pressure arm 215 that engages with the boss 212a.

[0109] In this embodiment, boss 212a engages with slit 215a (second engaged portion) of pressure arm 215. Figure 14(a) shows a state in which paper feed roller unit 210 is held between slide bearing 70 and feed bearing 23, rotated, and abuts against pressure arm 215. Figure 14(b) shows a state in which engaging member 212 has been retracted. Figure 14(c) shows a state in which paper feed roller unit 210 has been completely installed.

[0110] Unlike the first and second embodiments, the present embodiment is configured such that the engagement member 212 on the paper feed roller unit 210 side is retracted. In the paper feed roller unit 210 of the present embodiment, the engagement member 212 is configured as a separate part, and is biased by an engagement spring 213 as a biasing member. On the other hand, the pressure arm 215 is not provided with a retraction structure like the cap 18 in the first embodiment. The pressure arm 215 is provided with a tapered portion 215b for generating a force for retracting against the engagement spring 213 when the boss 212a abuts against it.

[0111] The operation of installing the sheet feed roller unit 210 will be described with reference to Figure 14. As in the first and second embodiments, the operator moves the slide shaft 22 in a direction resisting the slide spring pressure f1, and installs the sheet feed roller unit 210 between the slide bearing 70 and the feed bearing 23. At this time, the phase of the sheet feed roller unit 210 is arbitrary.

[0112] Thereafter, when the sheet feed roller unit 210 is rotated toward the pressure arm 215 around the rotation axis of the feed roller 13, the boss 212a of the sheet feed roller unit 210 comes into contact with the tapered portion 215b of the pressure arm 215 (FIG. 14(a)). Thereafter, the engaging member 212 is urged toward the pressure arm 215, causing the engaging member 212 to retract to a retracted position in the direction opposite to Y (FIG. 14(b)). When the sheet feed roller unit 210 is further pushed toward the pressure arm 215, the engaging member 212 returns to its normal position, enters the slit 215a inside the pressure arm 215, and engages with the pressure arm 215 (FIG. 14(c)).

[0113] That is, when boss 212a comes into contact with tapered portion 215b of pressure arm 215 in order for sheet feed roller unit 210 to move from the first position to the second position, boss 212a moves in a direction away from pressure arm 215 and slit 215a. More specifically, boss 212a moves in a direction intersecting the rotation axis of sheet feed roller unit 210, in a direction away from pressure arm 215 and slit 215a and in a direction approaching the rotation axis of sheet feed roller unit 210.

[0114] In this embodiment, the engaging member 212 of the paper feed roller unit 210 is set so as to be retractable by the force of the paper feed pressure biasing member 16, and the paper feed roller unit 210 is automatically attached even in the first state, as in the first embodiment.

[0115] In this way, in this embodiment as well, the installation step of the paper feed roller unit 210 is performed in two steps: engaging the slide shaft 22 and engaging the pressure arm 215. This allows the operator to concentrate on each task, improving the workability of replacing the paper feed roller unit 210.

[0116] Furthermore, this function can be achieved simply by retracting the engaging portion (engagement member) with the pressure arm 215 of the paper feed roller unit 210. Therefore, it is possible to improve usability for replacing the paper feed roller unit at low cost and in a space-saving manner. Furthermore, since there is no need to separate the pressure arm as in the first embodiment, there is greater design freedom in terms of increasing the strength of the pressure arm that applies paper feed pressure. Furthermore, although this embodiment has been described as having a configuration in which the engagement member 212 is biased by the engagement spring 213, it is also possible for the engagement member itself or a part of it to be flexible and deformable as in the second embodiment.

[0117] Example 4 In the second embodiment, a configuration in which the entire pressure arm is deflected and retracted has been described. In the present embodiment, a configuration in which a part of the pressure arm is deflected to retract the engagement portion will be described with reference to Fig. 15. Note that parts common to the first and second embodiments are given the same reference numerals, and their description will be omitted.

[0118] Figure 15 is a schematic cross-sectional view showing the procedure for installing the sheet feed roller unit 310. On the left side is the attitude of the sheet feed roller unit 310, and on the right side is an enlarged view showing the relationship between the engagement boss 311a as the second engaging portion and the cap 318 of the pressure arm as the second engaged portion. Figure 15(a) shows the state in which the sheet feed roller unit 310 is held between the slide bearing 70 and the feed bearing 23, and the sheet feed roller unit 310 is rotated and abuts against the cap 318. Figure 15(b) shows the state in which the cap 318 has been retracted. Figure 15(c) shows the state when the sheet feed roller unit 310 has been completely installed.

[0119] Unlike the second embodiment, in this embodiment, only a portion of the cap 318, rather than the entire arm, deforms and retracts. The cap 318 in this embodiment is provided with a deformable deformation portion 315a. Specifically, the deformation portion 315a, which has intentionally reduced strength, is provided at a portion of the tip that engages with the engagement boss 311a of the paper feed roller unit 310. Meanwhile, the paper feed roller unit 310 has the engagement boss 311a provided on the roller holder 311, as in the first embodiment.

[0120] The operation of installing the sheet feed roller unit 310 will be described with reference to Figure 15. As in the first embodiment, the operator moves the slide shaft 22 in a direction resisting the slide spring pressure f1, and installs the sheet feed roller unit 310 between the slide bearing 70 and the feed bearing 23. At this time, the phase of the sheet feed roller unit 310 is arbitrary. After that, when the sheet feed roller unit 310 is rotated around the rotation axis of the feed roller 13 toward the cap 318, the engagement boss 311a of the sheet feed roller unit 310 comes into contact with the cap 318 (Figure 15(a)).

[0121] Here, the deformation portion 315a is formed integrally with the cap 318, and is made flexible by locally thinning the wall. Therefore, when the engagement boss 311a of the paper feed roller unit 310 is urged toward the cap 318, the deformation portion 315a is configured to bend (FIG. 15(b)). When the engagement boss 311a penetrates beyond a certain point, the deformation portion 315a retreats from the movement path of the engagement boss. Thereafter, the deformation portion 315a of the cap 318 returns to its original position by its own elastic force, and engages with the pressure arm 15 (FIG. 15(c)).

[0122] Although the specific configuration of this embodiment shows an example in which the deforming portion 315a is locally bent, this embodiment is not limited to this configuration. Alternatively, the deforming portion 315a may be configured to be curved overall.

[0123] In this embodiment as well, the deformation portion 315a of the cap 318 is set so as to be retractable by the force of the paper feed pressure biasing member 16, and the paper feed roller unit 310 is automatically attached even in the first state, as in embodiment 1. In this way, in this embodiment as well, the attachment step of the paper feed roller unit 10 is performed in two steps, that is, engagement with the slide shaft 22 and engagement with the pressure arm 15, so that it is possible to concentrate on each task, and therefore the workability of replacing the paper feed roller unit 10 is good.

[0124] In this embodiment, the distance that deformed portion 315a must retreat from engagement boss 311a is long, which requires a large space L inside cap 318. However, by forming cap 315a as an integral part and deforming a portion of cap 318 as in this embodiment, it is possible to reduce costs while ensuring the strength of cap 318 itself. [Explanation of symbols]

[0125] 10, 110, 210, 310 Paper feed roller unit 11 Roller holder 11a Engagement boss 12 Pickup roller 13 Feed roller 15 Pressure arm 16 Paper feed pressure biasing member 17 Arm 18 Cap 18a Recess 18b Engagement part 18c tapered section 19 Cap spring 20 Paper feed unit 22 Slide axis (movable axis) 22a Rib 30 Paper cassette 31 Cassette tray 31a Lifting part 100 sheet feeding device 111 Roller holder 115 Pressure Arm 211 Roller holder 212 Engagement member 213 Engagement spring 215 Pressure Arm 311 Roller holder 315 Pressure Arm

Claims

1. A sheet feeding device, A device body, a paper feed roller unit having a first roller, a second roller, a first engaging portion, and a second engaging portion; a sheet storage section for storing sheets; a first engaged portion provided on the device body, the first engaged portion having a holding member movable in the direction of the axis of the first roller and configured to engage with the first engaging portion by moving in a first direction; a biasing member provided in the device body and biasing the holding member in the first direction; a pressure arm provided in the device body, the pressure arm having a second engaged portion that engages with the second engaging portion and a regulating groove having a regulating surface, the pressure arm urging the second roller toward the sheet accommodated in the sheet accommodating portion; and the paper feed roller unit is removable from the apparatus body by moving in a second direction that is the opposite direction to the first direction, the regulating surface is configured to regulate movement of the second engaging portion in the direction of the axis when the second roller is urged toward the sheet by the pressure arm, 2. A sheet feeding apparatus, wherein the restriction by the restriction surface is released when the second roller is not urged toward the sheet by the pressure arm.

2. 2. The sheet feeding device according to claim 1, wherein the first roller is a feed roller that forms a separation nip portion for separating sheets one by one, and the second roller is a pickup roller that contacts the sheets stored in the sheet storage portion.

3. A sheet feeding device as described in claim 1 or 2, characterized in that the width of the regulating groove in the axial direction is larger than the width of the second engagement portion in the axial direction, and the second engagement portion abuts against the regulating surface when moved a predetermined distance in the second direction.

4. 4. The sheet feeding device according to claim 1, wherein the regulating surface is inclined with respect to the direction of the axis and the vertical direction.

5. 5. The sheet feeding device according to claim 1, wherein the second engaging portion and the regulating groove do not come into contact with each other when the pressure arm is not biased toward the sheet.

Images