Sheet storage device and image forming apparatus

Abstract

To provide a sheet storage device capable of positioning a sheet at a fixed position while preventing buckling of the sheet regardless of the amount of loaded sheets.SOLUTION: A regulation part that regulates a position of a rear end part of a sheet in a conveyance direction has a pressing part that presses the sheet. A pressing surface, according to the amount of stored sheets, can take a first state in which an upper part of the pressing surface is positioned on the downstream side of a lower part of the pressing surface in a pressing direction and a second state in which a lower part of the pressing surface is positioned on the downstream of the upper part of the pressing surface in the pressing direction.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a copying machine or a printer, and a sheet storage device used therefor.

Background Art

[0002] Generally, an image forming apparatus that conveys a sheet to an image forming unit to form an image includes a sheet storage device including a sheet stacking tray on which sheets are stacked, and a paper feeding roller (paper feeding member) that conveys the sheet in the conveyance direction from the sheet storage device. In such a sheet storage device, there is one having a regulating unit (rear end regulating unit) that regulates the rear end portion of the sheet in the conveyance direction.

[0003] Some sheet storage devices include a lift plate that lifts the sheet toward the paper feeding roller. The lift plate lifts the front end portion of the sheet in the conveyance direction, thereby maintaining the height of the front end portion of the sheet at a height where it can contact the paper feeding roller with respect to the paper feeding roller. When the amount of sheets stacked on the sheet stacking tray decreases, both the front end portion and the rear end portion of the stacked sheets in the conveyance direction are at low positions. Here, when the amount by which the lift plate lifts up to bring the paper feeding roller closer to the front end portion of the sheet increases, the distance from the rear end portion of the sheet to the paper feeding roller also increases. As a result, the position of the front end portion of the sheet with respect to the paper feeding roller shifts upstream in the conveyance direction. As a result, image defects or jams may occur due to a delay in sheet conveyance.

[0004] In order to solve this problem, a configuration has been proposed in which a pressing portion biased by a biasing member toward the rear end of the sheet is provided in the rear end regulating portion, and the rear end of the sheet is pushed up in accordance with the lift-up angle of the stacked sheet by the pressing portion (Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the configuration of Patent Document 1 has a problem that it is difficult to adjust the biasing force of the biasing member. Details will be described below.

[0007] The pressing portion of the rear end regulating portion is configured to move the entire sheet loaded on the sheet loading tray. Therefore, when pushing out the sheet in a state where a large amount of sheets are loaded, a large biasing force is required. On the other hand, the biasing force needs to be set so that the sheet does not buckle in a state where a small amount of sheets are loaded. If the biasing force is set so that the sheet does not buckle in a state where a small amount of sheets are loaded, the sheet may not be pushed out in a state where a large amount of sheets are loaded.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide a sheet storage device that can prevent buckling of a sheet and bring a paper feed roller into contact with a predetermined position of the sheet regardless of the amount of sheets loaded. Another object of the present invention is to provide an image forming apparatus including such a sheet storage device.

Means for Solving the Problems

[0009] In order to solve the above problems, the present invention A sheet storage device, comprising: a sheet storage unit for storing sheets; a regulating unit provided in the sheet storage unit for regulating the position of the rear end portion of the sheet in the sheet conveyance direction, the regulating unit including a pressing portion having a pressing surface for pressing the rear end portion, a supporting portion for supporting the pressing portion, and a biasing member for biasing the pressing portion so that the sheet is pressed by the pressing surface; and a lifting unit for lifting the front end portion of the sheet in the conveyance direction. On the pressing surface, the position in contact with the lower sheet is defined as the lower part of the pressing surface, and the position in contact with the sheet above the lower sheet is defined as the upper part of the pressing surface. The pressing surface can take a first state and a second state according to the amount of sheets stored in the sheet storage unit, taking the first state when the amount of sheets is a first amount and taking the second state when the amount of sheets is a second amount. When the direction parallel to the horizontal direction and downstream in the conveyance direction is defined as the pushing direction, when the pressing surface is in the first state, the upper part of the pressing surface is located downstream of the lower part of the pressing surface in the pushing direction; when the pressing surface is in the second state, the lower part of the pressing surface is located downstream of the upper part of the pressing surface in the pushing direction. The first amount is more than the second amount. The pressing surface can take a third state when the amount of sheets is a third amount, and the angle formed by the pressing surface and the vertical direction when the pressing surface is in the third state is smaller than the angle formed by the pressing surface and the vertical direction when the pressing surface is in the first state and the angle formed by the pressing surface and the vertical direction when the pressing surface is in the second state. The third amount is more than the first amount.

Effects of the Invention

[0010] According to the present invention, the pressing portion can push up the stacked sheets so that the paper feed roller can contact a predetermined position of the stacked sheets regardless of the amount of stacked sheets, thereby reducing variations in the sheet position at the start of paper feeding.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0012] [Overall Configuration] FIG. 1 is a schematic cross-sectional view showing the overall configuration of an image forming apparatus 1. The image forming apparatus 1 forms an image by an electrophotographic recording method, conveys a sheet (recording material) S to an image forming unit 5 to transfer a toner image, conveys the sheet S to a fixing unit 6 to fix the toner image, and then discharges it to a discharge unit.

[0013] The sheet S is loaded and stored on the loading surface of the sheet storage section 21 of the sheet storage device 2 loaded at the bottom of the device. This sheet S is fed out in order from the upper sheet by a paper feed roller 31 as a conveying means for conveying the sheet in the conveying direction provided in the supply unit 3 for supplying the sheet S to the image forming section 5. The sheet S sent out by the paper feed roller 31 is conveyed to a conveying unit 4 provided downstream in the conveying direction of the sheet storage device 2, and from there it is sent to the image forming section 5 by a pair of conveying rollers 41.

[0014] In the image forming section 5, a laser beam corresponding to the image information is irradiated onto the photosensitive drum 51 by a laser scanner 52, thereby forming an electrostatic latent image on the photosensitive drum 51. Then, toner development is performed in a developing section (not shown) in the process cartridge P. The sheet S sent to the image forming section 5 is biased to the transfer roller 531 in the transfer unit 53, and after the toner image is transferred as an unfixed image, it is sent to the fixing section 6.

[0015] The fixing section 6 includes a heating unit 61 composed of a fixing film and a ceramic heater or the like as a heat generating means disposed on the inner surface side of the fixing film, and a pressure roller 62 that presses against it to form a fixing nip. The sheet S passes through this fixing nip, and the unfixed image is permanently fixed. Then, the sheet S is discharged outside the machine by a pair of discharge rollers 7 via a sheet discharge path and loaded on a discharge tray 8.

[0016] In this embodiment, an electrophotographic image forming process using a transfer section and a fixing section is adopted as the image forming section for forming an image on the sheet S, but the present invention is not limited to this. For example, the present invention may use an inkjet image forming process for forming an image on the sheet S by ejecting an ink liquid from a nozzle.

[0017] [Sheet Storage Device] Next, the detailed configuration of the sheet storage device 2 mounted on the image forming apparatus 1 will be described with reference to FIGS. 2 and 5. FIG. 2 is a plan view showing a schematic configuration of the sheet storage device 2 capable of storing sheets S of different sizes, and FIG. 5 is a cross-sectional view of the regulating unit 24.

[0018] The sheet storage device 2 shown in FIG. 2 includes a sheet storage unit 21 for stacking and storing sheets S of different sizes, a pair of width regulating units 22 and 23 for regulating the side end positions of the sheet S, and a regulating unit 24 for regulating the rear end position of the sheet S. Further, it includes a middle plate 25 that abuts against a rotatable lift arm 26 and is pushed up around the middle plate support shafts 251 and 252, and the stacked sheet S is brought into contact with the paper feed roller 31. Note that the width regulating units 22 and 23 and the regulating unit 24 are arranged at positions that do not affect the rotation operation of the middle plate 25.

[0019] When storing sheets S of different sizes in the sheet storage unit 21, the width regulating units 22 and 23 and the regulating unit 24 are set at the corresponding positions of the sheet S for storage. Thereby, it becomes possible to store the sheet S at an appropriate position. The sheet storage device 2 can be mounted by moving it in the direction of arrow A with respect to the image forming apparatus 1. When transporting the sheet S, the lift arm 26 is rotated by a rotation mechanism (not shown) inside the main body, and the middle plate 25 is rotated upward around the middle plate support shafts 251 and 252. Thereby, the sheet positioned by the width regulating units 22 and 23 and the regulating unit 24 is pressed against the paper feed roller 31.

[0020] Incidentally, the pair of width restricting means 22 and 23 each have rack portions 221 and 231 extending in the paper width direction (the direction of arrow B) on the bottom surface portion of the sheet storage portion 21. Rack teeth (not shown) formed on the rack portions 221 and 231 mesh with each other via a pinion gear (not shown). Thus, when either one of the width restricting portions is moved in the width direction, the other width restricting portion moves in the opposite direction to the one width restricting portion in conjunction with the action of the pinion gear (not shown) and the rack portions 221 and 231. The positioning of the width restricting portions 22 and 23 is determined by fixing means (not shown) provided on the width restricting portions 22 and 23 fitting into grooves provided in the sheet storage portion 21.

[0021] The restricting portion 24 is movable along a groove portion 27 provided along the C direction. The groove portion 27 has uneven portions 28 extending in the C direction, and the positioning of the restricting portion 24 is performed by engaging with a protruding portion 2412 provided on the restricting portion 24. The engagement between the protruding portion 2412 and the uneven portions 28 is released when the user operates the lever member 244. In this state, it can be moved on the groove portion 27 and positioned at an arbitrary position according to the size of the sheet S.

[0022] [Embodiment 1] Next, a first embodiment of the present invention will be described with reference to FIGS. 3 to 7. FIG. 3 shows a cross-sectional view of the sheet storage device 2 of Embodiment 1. FIG. 4 is a perspective view of the restricting portion 24 for positioning the rear end of the sheet S loaded in the sheet storage portion 21, and FIG. 5 shows a cross-sectional view of the restricting portion 24. FIGS. 6 and 7 are diagrams for explaining the movement of the pressing portion 200.

[0023] The regulating part 24 has a pressing part 200, a supporting part 241, and a biasing member 243. The pressing part 200 has a first part 245 and a second part 246. The first part 245 and the second part 246 are swingable with respect to the supporting part 241, and the second part 246 is located below the first part 245. The first part 245 and the second part 246 have a pressing surface for pressing the rear end part of the sheet S. However, the pressing surface here refers to the surface pressing the sheet S, which changes according to the loading amount of the sheet S. Further, the regulating part 24 has a biasing member 243 for biasing the pressing part 200 so that the sheet S is pressed by the pressing surface. Here, the first surface 245c existing on the first part 245 is the surface pressing the sheet S at the time of the third amount described later, and the second surface 246c existing on the second part 246 is a surface capable of contacting the lowermost sheet loaded in the sheet storage part 21. The second surface 246c is the surface pressing the sheet at the time of the first amount and the second amount of the sheet amount described later. In the present embodiment, the second surface 246c is a flat surface.

[0024] The first part 245 is held by the supporting part 241. A part of the first part 245 is fitted to a shaft part (not shown) provided on the supporting part 241, and with the shaft part as a fulcrum, it is swingable.

[0025] The second part 246 is held by the first part 245. An engaging part 246a provided on the second part 246 is engaged with a connecting part 245a provided on the first part 245, and with the engaging part 246a as a swing center, it is swingable.

[0026] Also, in the present embodiment, the engaging part 246a is located at a position closer to the upper end 248 than the lower end 249 of the regulating part 24 in the vertical direction. In a state where the sheet S is not in the sheet storage device 2, the first part 245 and the second part 246 are biased by the biasing member 243 as shown in FIG. 5 and are in a state of swinging rightward in the drawing from the supporting part 241. The swinging of the second part 246 is regulated by an abutting surface 246b provided on itself abutting against a swing regulating part 241b provided on the supporting part 241, and the maximum swing position is determined.

[0027] By swingably attaching the second part 246 to the first part 245, when the biasing force of the biasing member 243 is applied, the upper part of the second part 246 can swing even if the lower part does not move. With this configuration, the second part 246 will preferentially push out the upper side of the loaded seat S.

[0028] Although the force required for the pressing part 200 to push out the one located at the top of the loaded seat S does not depend on the height of the loaded seat S, the greater the load, the more necessary it is to push out the lower seats together. Therefore, the pressing force applied by the second part 246 near the one located at the top of the seat S needs to be greater when the height of the loaded seat S is higher. On the other hand, when there are few loaded seats S, it is necessary to suppress the load so that the bundle of seats S does not buckle under the pressing force of the second part 246. The biasing position and biasing force are set to satisfy the above two conditions.

[0029] The biasing member 243 biases the biased part 247 of the second part 246. In this embodiment, the biased part 247 is provided below the engaging part 246a and at a position closer to the upper end 248 than the lower end 249 of the restricting part 24. In order to obtain the effect of preferentially pushing out the upper seat S more, it is preferable to provide the biased part 247 at such a position. However, the biased part 247 can be provided anywhere as long as it is above the bottom seat of the seats S accommodated in the seat storage part 21.

[0030] The swinging posture of the pressing part 200 is determined so as to ensure the required pressing amount according to the height of the loaded seat S. In addition, the support part 241 is provided with a loaded seat contact surface 241a that contacts the rear end of the seat S when there is a large amount of the loaded seat S.

[0031] Using FIGS. 6 and 7, the states of the first part 245 and the second part 246 when the sheet S is loaded on the sheet storage device 2 will be described by dividing them into three patterns according to the amount of the loaded sheet S, i.e., the case of the third amount, the case of the first amount, and the case of the second amount. FIGS. 6(a) and 7(a) show the case of the third amount, FIGS. 6(b) and 7(b) show the case of the first amount, and FIGS. 6(c) and 7(c) show the case of the second amount, respectively. Here, it is assumed that the third amount is larger than the first amount, and the first amount is larger than the second amount. Specifically, in this embodiment, it will be described as a state in which 90% of the third amount, 50% of the first amount, and 10% of the second amount are respectively accommodated with respect to the allowable capacity of the sheet storage unit 21 to accommodate the sheet S, but these amounts are not limited thereto.

[0032] First, before explaining the configuration of the present embodiment, consider a configuration in which the pressing portion 200 does not exist, the rear end of the sheet S is restricted by the restricting portion, and the front end of the sheet S is lifted up. As shown in FIG. 6(a), when the sheet S is in the state of the third amount, the distance from the rear end of the topmost loaded sheet along the surface of the sheet to the contact point between the sheet and the paper feed roller 31 is L1. As shown in FIG. 6(b), when the sheet S is in the first amount, the distance is L2, and this distance is longer than L1. Further, as shown in FIG. 6(c), when the sheet S is in the second amount, the distance is L3, and this distance is longer than L2.

[0033] Next, the configuration of the present embodiment in which the pressing portion 200 exists will be described. When the loaded sheet S is in the third amount, as shown in FIG. 7(a), the first part 245 and the second part 246 abut against the rear end of the sheet S in a state of urging the sheet S without protruding from the support portion 241. At this time, the angle formed by the pressing surface pressing the sheet S and the vertical direction is smaller (third state) compared to the angles in the first state and the second state described later.

[0034] Here, on the pressing surface, the position in contact with the lower sheet S loaded in the sheet storage unit 21 is called the lower part of the pressing surface, and the position in contact with the sheet S located above the lower sheet is called the upper part of the pressing surface. In other words, on the pressing surface, there are a lower part of the pressing surface in contact with the sheet S and an upper part of the pressing surface in contact with the sheet S above the lower part of the pressing surface.

[0035] When the loaded sheet S is of the first quantity, as shown in FIG. 7(b), when the pressing surface tilts, the first part 245 and the second part 246 swing from the support part 241 in the right direction in the figure. Here, the distance from the rear end of the top sheet to the position where the sheet S contacts the paper feed roller 31 is called the contact distance. Due to the decrease of the loaded sheet S and the lift-up of the middle plate 25, the contact distance becomes longer. When the pressing surface swings, the top sheet S to be fed by the paper feed roller 31 next moves in the conveying direction, and the contact distance becomes shorter. In this way, the increased contact distance is adjusted.

[0036] At this time, the upper part of the pressing surface is called the upper pressing surface 2411b, and the lower part of the pressing surface is called the lower pressing surface 2410b. Here, the position of the lower pressing surface 2410b is the position corresponding to the bottom sheet loaded in the sheet storage unit 21 in the height direction. The position of the upper pressing surface 2411b is the position corresponding to the top sheet. Also, the direction parallel to the horizontal direction and downstream in the conveying direction is defined as the pushing direction. Then, on the contact surface (pressing surface) between the second part 246 and the sheet S, the upper pressing surface 2411b is located downstream of the lower pressing surface 2410b in the pushing direction (the first state). In other words, in the pushing direction, the upper end of the second surface 246c of the second part 246 is in a state of being inclined such that it is located downstream of the lower end of the second surface 246c. In this state, the pressing surface and the second surface 236c face downward in the vertical direction.

[0037] The reason for such inclination is that the force applied from the sheet S to the upper part 2411b of the pressing surface is smaller than the force applied to the lower part 2410b of the pressing surface. As a result, the lower part 2410b of the pressing surface does not swing by the sheet S, and the upper part 2411b of the pressing surface swings by the biasing force and inclines as shown in FIG. 7(b).

[0038] When the second surface 246c and the pressing surface are inclined as described above, the second portion 246 can press the upper sheet S so that the upper sheet S moves toward the paper feed roller 31. That is, when the second surface 246c and the pressing surface are inclined as described above, the second portion 246 does not need to move the entire bundle of sheets stored in the sheet storage portion 21 when the amount of sheets is large.

[0039] When the loaded sheet S is of the second amount, the position on the pressing surface corresponding to the lowermost sheet loaded in the sheet storage portion 21 in the height direction is the lower part 2410c of the pressing surface, and the position corresponding to the uppermost sheet is the upper part 2411c of the pressing surface. Then, on the contact surface (pressing surface) between the second portion 246 and the sheet S, the lower part 2410c of the pressing surface is located on the downstream side of the upper part 2411c in the pushing direction (second state).

[0040] In other words, in a state where the second surface 246c of the second portion 246 is inclined so that the lower end of the second surface 246c is located on the downstream side of the upper end of the second surface 246c in the pushing direction. In this state, the pressing surface and the second surface 236c face upward in the vertical direction.

[0041] Even in this state, when the pressing surface swings, the uppermost sheet S to be fed by the paper feed roller 31 next moves in the conveying direction, and the contact distance becomes shorter. Also, in the second state, the distance for pushing out the uppermost sheet is longer than in the first state. In this way, the increased contact distance is adjusted.

[0042] In addition, in this embodiment, the position of the upper part of the pressing surface and the position of the lower part of the pressing surface corresponded to the position of the bottom sheet and the top sheet loaded in the sheet storage unit 21, but it is not limited to this. For example, when the second part 246 does not contact the bottom sheet loaded in the sheet storage unit 21, the position corresponding to the bottom sheet with which the second part 246 abuts is the position of the lower part of the pressing surface. Similarly, when the second part 246 does not contact the top sheet loaded in the sheet storage unit 21, the position corresponding to the top sheet with which the second part 246 abuts is the position of the upper part of the pressing surface. That is, among the pressing surfaces, the top can also be called the upper part of the pressing surface, and the bottom can be called the lower part of the pressing surface.

[0043] To summarize the above, the pressing surface can take a first state in which the upper part of the pressing surface is located on the downstream side of the lower part of the pressing surface according to the amount of sheets stored in the sheet storage unit in the pushing direction, and a second state in which the lower part of the pressing surface is located on the downstream side of the upper part of the pressing surface in the pushing direction. Here, when the amount of sheets in the first state is the first amount and the amount of sheets in the second state is the second amount, the first amount is larger than the second amount. Further, when the amount of sheets is the third amount, the pressing surface can take a third state in which the angle formed by the pressing surface and the vertical direction is smaller than the angle formed by the pressing surface and the vertical direction in the first state and the angle formed by the pressing surface and the vertical direction when the pressing surface is in the second state. Here, the third amount is larger than the first amount. Note that the angle formed by the pressing surface and the vertical direction is the same as the angle formed by the second surface 246c and the vertical direction.

[0044] By adopting the configuration of the first embodiment, the pressing unit 200 can push up the stacked sheets so that the paper feed roller 31 can abut against a predetermined position of the stacked sheets regardless of the stacking amount of the sheets S. Therefore, variations in the position of the sheet S at the start of conveyance can be reduced, and stable paper feeding is enabled.

[0045] In addition, the restricting unit 24 can correctly set the sheet S without bending the sheet S when a small number of sheets of the sheet S or a set of thin paper are set. It is possible to push up the sheet S during conveyance regardless of the stacking amount of the sheet S.

[0046] In this embodiment, a compression coil spring is used as the biasing member 243, but other members that can generate a biasing force, such as a torsion coil spring or a leaf spring, may also be used.

[0047] [Embodiment 2] Next, a second embodiment of the present invention will be described with reference to FIGS. 8 to 11. In Embodiment 1, a configuration in which two connected pressing portions are used to push out the sheet S was described, but the present invention is not limited to this configuration. In Embodiment 2, an example in which the pressing portion is constituted by a single member and produces a similar effect will be described.

[0048] In this embodiment, the restricting portion 94 includes a support portion 941, a loading sheet contact surface 941a, a pressing portion 900, a pressing member 945, a surface 945c, and a biased portion 947. The pressing portion 900 has a pressing member 945, and the pressing member 945 has a surface 945c. The surface 945c corresponds to the second surface 246c in Embodiment 1. The surface 945c is a surface that can contact the lowermost sheet loaded in the sheet storage portion 21. The surface 945c is a surface that presses the sheet when the amount of the sheet is the first amount and the second amount. In this embodiment, the surface 945c is a flat surface.

[0049] Regarding the components having the same configuration and function as those in the first embodiment, the same numbers as those in the first embodiment are assigned, and repeated description will be omitted. FIG. 8 is a perspective view of the restricting portion 94 that positions the rear end of the sheet S loaded in the sheet storage portion 21, and FIG. 9 shows a cross-sectional view of the restricting portion 94. FIGS. 10 and 11 show the second embodiment of the present invention.

[0050] The pressing member 945 is provided with pressing member shaft portions 945a at both ends, is fitted into a hole portion 941c provided in the support portion 941, can linearly move in the d direction in which the hole portion 941c extends, and can rotate about the pressing member shaft portion 945a. The length of the hole portion 941c in the direction in which the pressing member 945 as a pressing portion linearly moves is longer than the length in the direction orthogonal to the direction in which it linearly moves. That is, the pressing member 945 is supported by the support portion 941 and its hole portion 941c so as to be linearly movable and rotatable.

[0051] Also, the hole portion 941c is located at a position closer to the upper end 248 than the lower end 249 of the restricting portion 94 in the vertical direction. Further, similar to the first embodiment, the pressing member 945 is biased toward the sheet S by a biasing member 243 provided on the restricting portion 94.

[0052] When there is no sheet S in the sheet storage device 2, the pressing member 945 is biased by the biasing member 243 as shown in FIG. 9, and protrudes rightward in the drawing from the support portion 941. The swinging of the pressing member 945 is restricted by the contact of a pressing member contact portion 945b provided on itself with a contact portion 941b provided on the support portion 941.

[0053] Also, the biased portion 947 is located below the hole portion 941c in the vertical direction and at a position closer to the upper end 248 than the lower end 249 of the restricting portion 94. In order to more effectively obtain the effect of preferentially pushing out the upper sheet S, it is preferable to provide the biased portion 247 at such a position. However, the biased portion 947 may be provided anywhere as long as it is above the lowermost sheet of the sheets S accommodated in the sheet storage portion 21.

[0054] The pressing member 945 is configured such that its upper part can swing even if its lower part does not move when the biasing force of the biasing member 243 is applied. With the above-described configuration, the pressing member 945 preferentially pushes out the upper side of the sheet S.

[0055] Similar to the first embodiment, the biasing position and the biasing force are set so as to achieve both the force for pushing out the upper sheet of the stacked sheets S and the force for preventing the bundle of the sheets S from buckling. The swinging posture of the pressing portion is determined so as to ensure the required pressing amount at each height at which the sheet S is stacked.

[0056] Regarding the state of the pressing member 945 when the sheet S is loaded on the sheet storage device 2, with reference to FIGS. 10 and 11, when the amount of the loaded sheet S is the third amount, the first amount, or the second amount, it will be described in three patterns. Although the respective amounts and their relationships are considered to be the same as those in the first embodiment, they are not limited to these amounts.

[0057] First, consider the state where the pressing portion 900 does not exist, the rear end of the sheet S is regulated by the regulating portion, and the front end of the sheet S is lifted up. When the sheet S is in the state of the third amount, as shown in FIG. 10(a), the distance L4 from the rear end of the topmost loaded sheet along the surface of the sheet to the contact point between the sheet and the paper feed roller 31 is the shortest. When the sheet S is in the first amount, the distance is L5 as shown in FIG. 10(b), and this distance is longer than L4. Further, when the sheet S is in the second amount, the distance is L6 as shown in FIG. 10(c), and this distance is longer than L5.

[0058] Next, the configuration of this embodiment where the pressing portion 900 exists will be described. When the amount of the loaded sheet S is the third amount, as shown in FIG. 11(a), the pressing member 945 contacts the rear end of the sheet S while urging the sheet S and without protruding from the support portion 941 (third state).

[0059] When the loaded sheet S is of the first quantity, the pressing member 945 tilts as shown in FIG. 11(b). At this time, the upper part of the pressing surface is referred to as the upper pressing surface 2411b, and the lower part of the pressing surface is referred to as the lower pressing surface 2410b. Here, the position of the lower pressing surface 2410b is the position corresponding to the lowermost sheet loaded in the sheet storage portion 21 in the height direction. The position of the upper pressing surface 2411b is the position corresponding to the uppermost sheet. Also, similar to the first embodiment, the direction parallel to the horizontal direction and downstream in the conveyance direction is defined as the pushing direction. Then, on the contact surface (pressing surface) between the pressing member 945 and the sheet S, the upper pressing surface 2411b is located downstream of the lower pressing surface 2410b in the pushing direction (the first state). In other words, in the pushing direction, the upper end of the surface 945c of the pressing member 945 is in a tilted state such that it is located downstream of the lower end of the surface 945c. In this state, the pressing surface and the surface 945c face downward in the vertical direction.

[0060] Even in this state, when the pressing surface swings, the uppermost sheet S fed by the sheet feeding roller 31 next moves in the conveyance direction, and the contact distance becomes shorter. In this way, the increased contact distance is adjusted.

[0061] The reason for such tilting is that the force applied to the upper pressing surface 2411b from the sheet S is smaller than the force applied to the lower pressing surface 2410b. As a result, the lower pressing surface 2410b does not swing due to the sheet S, and the upper pressing surface 2411b swings due to the biasing force and tilts as shown in FIG. 11(b).

[0062] When the surface 945c and the pressing surface tilt as described above, the pressing member 945 can press the upper sheet S so that the upper sheet S moves toward the sheet feeding roller 31. That is, when the surface 945c and the pressing surface tilt as described above, the pressing member 945 does not need to move the entire bundle of sheets stored in the sheet storage portion 21 when the quantity of the sheets is large.

[0063] When the loaded sheet S is in the second quantity, among the pressing surfaces, the position corresponding to the lowermost sheet loaded in the sheet storage portion 21 in the height direction is the lower pressing surface 2410c, and the position corresponding to the uppermost sheet is the upper pressing surface 2411c. Then, the contact surface (pressing surface) between the pressing member 945 and the sheet S is such that the lower part of the pressing surface is located on the downstream side of the upper pressing surface in the pushing direction (second state). In other words, in the pushing direction, the lower end of the surface 945c is in a state where it is located on the downstream side of the upper end of the surface 945c, and the surface 945c of the pressing member 945 is inclined. In this state, the pressing surface and the surface 945c face upward in the vertical direction.

[0064] Even in this state, when the pressing surface swings, the uppermost sheet S to be fed by the paper feed roller 31 next moves in the conveyance direction, and the contact distance becomes shorter. Also, in the second state, the distance for pushing out the uppermost sheet is longer than in the first state. In this way, the increased contact distance is adjusted.

[0065] Also, in this embodiment as well, the position of the upper pressing surface and the position of the lower pressing surface corresponded to the positions corresponding to the lowermost sheet and the uppermost sheet loaded in the sheet storage portion 21, but it is not limited to this.

[0066] In this way, by adopting the configuration of the second embodiment, as in the first embodiment, the pressing portion 900 can push up the loaded sheet so that the paper feed roller 31 can contact a predetermined position of the loaded sheet regardless of the loading amount of the sheet S. Thereby, the variation in the position of the sheet S at the start of conveyance can be reduced, enabling stable paper feeding.

[0067] Also, similar to the first embodiment, in this embodiment, a compression coil spring is used for the biasing member 243, but other members that generate a biasing force such as a torsion coil spring or a leaf spring may be used.

Explanation of Reference Numerals

[0068] 1 Image forming apparatus 2 Sheet storage device 21 Sheet storage portion 25 Medium Plate 24, 94 Regulation Unit 241 Support Unit 243 Biasing Member 245 First Part 245a Connecting Part 246 Second Part 246a Engaging Part 246b Second Part Contacting Part 941 Support Unit 945 Pressing Member S Sheet

Claims

1. A sheet storage device, comprising a sheet storage unit for storing sheets, a regulating unit provided in the sheet storage unit for regulating the position of the rear end portion of the sheet in the sheet conveyance direction, the regulating unit including a pressing portion having a pressing surface for pressing the rear end portion, a supporting portion for supporting the pressing portion, and a biasing member for biasing the pressing portion so that the sheet is pressed by the pressing surface, a lifting unit for lifting the leading end portion of the sheet in the conveyance direction, and being provided with, on the pressing surface, a position where it contacts the lower sheet is defined as the lower part of the pressing surface, and a position where it contacts the sheet above the lower sheet is defined as the upper part of the pressing surface. The pressing surface can take a first state and a second state according to the amount of sheets stored in the sheet storage unit, taking the first state when the amount of sheets is a first amount, and taking the second state when the amount of sheets is a second amount. When the direction parallel to the horizontal direction and downstream in the conveyance direction is defined as the pushing direction, when the pressing surface is in the first state, the upper part of the pressing surface is located downstream of the lower part of the pressing surface in the pushing direction, and when the pressing surface is in the second state, the lower part of the pressing surface is located downstream of the upper part of the pressing surface in the pushing direction. The first amount is more than the second amount. The pressing surface can take a third state when the amount of sheets is a third amount. The angle formed by the pressing surface in the third state and the vertical direction is smaller than the angle formed by the pressing surface in the first state and the vertical direction, and the angle formed by the pressing surface in the second state and the vertical direction. The third amount is more than the first amount. A sheet storage device characterized by the above.

2. The pressing part has a first part swingably supported by the supporting part and a second part swingably engaged with the first part, and the second part is located below the first part in the vertical direction. The seat storage device according to claim 1, characterized in that.

3. The first part and the second part are engaged by an engaging part, and the engaging part is located at a position closer to the upper end than the lower end of the restricting part in the vertical direction. The seat storage device according to claim 2, characterized in that.

4. The biasing member biases the biased part of the pressing part, and the biased part is, in the vertical direction, Located below the engaging part and at a position closer to the upper end than the lower end of the restricting part. The seat storage device according to claim 3, characterized in that.

5. The supporting part has a hole part that supports the pressing part so as to be linearly movable and rotatable. The seat storage device according to claim 1, characterized in that.

6. The hole part is characterized in that the length in the direction in which the pressing part linearly moves is longer than the length in the direction orthogonal to the direction in which the pressing part linearly moves. The seat storage device according to claim 5, characterized in that.

7. The hole part is located at a position closer to the upper end than the lower end of the restricting part in the vertical direction. The seat storage device according to claim 5 or 6, characterized in that.

8. The biasing member biases the biased part of the pressing part, and the biased part is, in the vertical direction, located below the hole part and at a position closer to the upper end of the restricting part than the lower end of the restricting part. The seat storage device according to claim 7, characterized in that.

9. A seat storage device, A seat storage part for storing a seat, A regulating part provided in the sheet storage part for regulating the position of the rear end part of the sheet in the sheet conveyance direction, the regulating part having a pressing part having a pressing surface for pressing the rear end part, a supporting part for supporting the pressing part, and a biasing member for biasing the pressing part so that the sheet is pressed by the pressing surface. A lifting part for lifting the front end part of the sheet in the conveyance direction. It is provided with. On the pressing surface, the position in contact with the lower sheet is defined as the lower part of the pressing surface, and the position in contact with the sheet above the lower sheet is defined as the upper part of the pressing surface. The pressing surface can take a first state and a second state according to the amount of the sheet stored in the sheet storage part, takes the first state when the amount of the sheet is the first amount, and takes the second state when the amount of the sheet is the second amount. When the direction parallel to the horizontal direction and downstream in the conveyance direction is defined as the pushing direction, when the pressing surface is in the first state, the upper part of the pressing surface is located downstream of the lower part of the pressing surface in the pushing direction, and when the pressing surface is in the second state, the lower part of the pressing surface is located downstream of the upper part of the pressing surface in the pushing direction. The pressing part has a first part swingably supported by the supporting part and a second part swingably engaged with the first part, and the second part is located below the first part in the vertical direction. A sheet storage device characterized by this.

10. The sheet storage device according to claim 9, wherein the first part and the second part are engaged by an engaging part, and the engaging part is located at a position closer to the upper end than the lower end of the regulating part in the vertical direction.

11. The biasing member biases the biased part of the pressing part, and the biased part is, in the vertical direction, It is located below the engaging part and at a position closer to the upper end than the lower end of the regulating part. The sheet storage device according to claim 10.

12. A sheet storage device, A sheet storage part for storing sheets. A regulating part provided in the sheet storage part for regulating the position of the rear end part of the sheet in the sheet conveyance direction, the regulating part having a pressing part having a pressing surface for pressing the rear end part, a supporting part for supporting the pressing part, and a biasing member for biasing the pressing part so that the sheet is pressed by the pressing surface. A lifting part for lifting the front end part of the sheet in the conveyance direction. Comprising. On the pressing surface, the position in contact with the lower sheet is defined as the lower part of the pressing surface, and the position in contact with the sheet above the lower sheet is defined as the upper part of the pressing surface. The pressing surface can take a first state and a second state according to the amount of the sheet stored in the sheet storage part, takes the first state when the amount of the sheet is the first amount, and takes the second state when the amount of the sheet is the second amount. When the direction parallel to the horizontal direction and downstream in the conveyance direction is defined as the pushing direction, when the pressing surface is in the first state, the upper part of the pressing surface is located downstream of the lower part of the pressing surface in the pushing direction, and when the pressing surface is in the second state, the lower part of the pressing surface is located downstream of the upper part of the pressing surface in the pushing direction. The supporting part has a hole part for supporting the pressing part so as to be linearly movable and rotatable. A sheet storage device characterized by the above.

13. The sheet storage device according to claim 12, characterized in that the length of the hole part in the direction in which the pressing part linearly moves is longer than the length in the direction orthogonal to the direction in which the pressing part linearly moves.

14. The sheet storage device according to claim 12 or 13, characterized in that the hole part is located at a position closer to the upper end than the lower end of the regulating part in the vertical direction.

15. The sheet storage device according to claim 14, characterized in that the biasing member biases the biased part of the pressing part, and the biased part is located below the hole part and closer to the upper end of the regulating part than the lower end of the regulating part in the vertical direction.

16. The sheet storage device according to any one of claims 9 to 15, wherein the first amount is greater than the second amount.

17. An image forming apparatus, comprising the sheet storage device according to any one of claims 1 to 16, an image forming unit that forms an image on a sheet, and characterized by having the above.

Images