Sheet Feeding Device and Image Forming Apparatus

Abstract

To provide a sheet supply device that maintains contact of a sheet with a conveyance roller from the time when the sheet is fully conveyed to the time when the final sheet is conveyed, even if it is small.SOLUTION: A sheet supply device for supplying a sheet from a storage space to a downstream side in a conveyance direction includes: conveyance means for contacting and conveying the uppermost sheet located at the top-level of a sheet bundle stored in the storage space; angle adjusting means that changes an angle according to a remaining amount of seats in the storage space: and energization means that gradually energizes a rear end of the uppermost sheet toward the side of the conveyance means according to the remaining amount.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] A sheet feeding device for supplying a recording medium to an image forming apparatus that forms an image on a sheet-like recording medium is known. There are various types of sheet feeding devices, but generally, it has an accommodation space for accommodating sheets as a sheet bundle, and a mechanism for carrying out single sheets from one end of the accommodation space. In addition, a sheet feeding device applied to a small-sized image forming apparatus is often arranged at the bottom surface portion of the image forming apparatus.

[0003] As a mechanism for carrying out a sheet from the accommodation space of the sheet feeding device, a carry-out roller that rotates in contact with the uppermost sheet located at the top of the sheet bundle is arranged, and the sheet is carried out in a predetermined conveyance direction by the operation of the roller. In this case, when the remaining amount of the sheet bundle decreases, the relative position of the leading end portion of the uppermost sheet with respect to the carry-out roller changes, and the contact state between the carry-out roller and the uppermost sheet becomes insufficient, which causes a carry-out failure.

[0004] To prevent this, for example, one end of the bottom plate of the accommodation space is biased in a direction to be lifted by an elastic member such as a spring so that the end portion of the sheet bundle on the sheet carry-out side is held at the contact position with the carry-out roller, and a configuration for maintaining the contact state between the carry-out roller and the uppermost sheet is known.

[0005] In addition, in order to prevent the sheet bundle from shifting in a direction away from the carry-out roller as a whole due to an increase in the inclination of the bottom plate as the remaining amount of the sheet bundle decreases, a technique related to an end fence that biases and supports the sheet bundle in the carry-out direction is also known (see Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the technology disclosed in Patent Document 1, it has been difficult to accurately maintain the contact state between the carry-out roller and the topmost sheet from the fully loaded state where the accommodation space is filled with sheets until the final sheet is carried out. As the remaining amount of the sheet bundle approaches zero, the deviation becomes larger toward the opposite side of the carry-out direction at the tip position of the topmost sheet of the sheet bundle that has become a small amount. In that case, as the remaining amount of the sheet bundle decreases, the extrusion of the sheet bundle in the carry-out direction by the biasing of the end fence is increased.

[0007] As a result, even when using the end fence technology disclosed in Patent Document 1, there has been a problem in accurately preventing sheet carry-out failures from the fully loaded state to the empty state. To increase the extrusion of the sheet bundle, even if the rotational movement amount of the sheet support portion provided by the end fence is the same, the dimension may be increased. However, to increase the dimension of the support portion, it is necessary to increase the height dimension of the sheet supply device, making miniaturization difficult. On the other hand, when the dimension of the support portion is the same and the rotational movement amount of the support portion is increased, a sufficient spring biasing force is required for that purpose. Due to this large biasing force, conversely, the tip of the sheet at the fully loaded time is pressed against the tip restricting portion, making it difficult for the bottom plate to move and resulting in a conveyance failure.

[0008] Therefore, in the prior art, there has been a problem in preventing carry-out failures from the time of sheet full load to the carry-out of the final sheet while making the sheet supply device small (thin).

[0009] An object of the present invention is to provide a sheet supply device that maintains contact between the sheet and the carry-out roller and prevents carry-out failures from the time of sheet full load to the carry-out of the final sheet even if it is small.

Means for Solving the Problems

[0010] In order to solve the above technical problems, one aspect of the present invention is a sheet feeding device that supplies a sheet housed in a housing space, comprising: a carrying-out means for carrying out the uppermost sheet at the top of a sheet bundle composed of a plurality of sheets housed in the housing space in the conveying direction; an angle adjusting means for adjusting the angle of the sheet with respect to the conveying direction according to the remaining amount of the sheet in the housing space; and a biasing means for stepwise biasing the end portion of the uppermost sheet toward the side of the carrying-out means according to the remaining amount of the sheet. The biasing means is an end fence that supports the sheet toward the downstream side in the conveying direction. The end fence includes an end support member that supports the end portion of the sheet bundle, a first biasing means for biasing the end support member toward the downstream side in the conveying direction, and a second biasing means for biasing the end support member toward the downstream side with a biasing force weaker than that of the first biasing means. When the remaining amount of the sheet is equal to or greater than a predetermined amount, the first biasing means and the second biasing means bias the end portion of the uppermost sheet toward the side of the carrying-out means. When the remaining amount of the sheet is less than the predetermined amount, the biasing of the end portion support member by the first biasing means stops, and thereafter, only the second biasing means biases the end portion of the uppermost sheet toward the side of the carrying-out means characterized in that it does the following.

Effect of the Invention

[0011] According to the present invention, even if it is small in size, it is possible to maintain the contact of the sheet with the carrying-out roller from when the sheet is full to the carrying-out of the last sheet, and prevent carrying-out failure.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying out the Invention

[0013] [Summary of Embodiments According to the Present Invention] One embodiment of the sheet feeding device according to the present invention prevents unloading defects that occur due to a change in the relative positional relationship with an unloading mechanism when unloading the sheet as the thickness of the stacked sheet bundle decreases by sequentially unloading the topmost sheet of the stacked sheet bundle. More specifically, it is provided with a configuration that displaces the sheet bundle closer to the unloading mechanism in accordance with the decreasing tendency of the thickness of the sheet bundle with respect to the unloading mechanism that unloads the sheet by contact with the topmost sheet of the sheet bundle. That is, it is provided with a configuration that suppresses the displacement of the remaining amount of the sheet decreasing and the topmost sheet moving away from the unloading mechanism, and supports the sheet bundle so as to maintain the relative position between the topmost sheet and the unloading mechanism at a predetermined position.

[0014] For example, in the case of a sheet feeding device that lifts one end of the bottom of the storage space and brings the end closer to the side where the topmost sheet contacts the unloading mechanism in accordance with the decrease in the remaining amount of the sheet bundle, as the decrease in the sheet bundle progresses, the amount of lifting of one end of the bottom becomes larger. Then, the inclination of the bottom becomes larger, and the inclination of the sheet bundle also becomes larger, so the force that the sheet bundle moves in the direction away from the unloading mechanism becomes larger. Therefore, in the following embodiments, it is provided with a configuration that biases the entire sheet bundle toward the unloading mechanism against the force that tries to move away from the unloading mechanism among the forces applied to the sheet bundle by the inclination of the bottom.

[0015] In addition, as the remaining amount of the sheets decreases, the inclination of the bottom increases. To maintain the relative position between the uppermost sheet and the unloading mechanism, it is necessary to increase the amount of pushing the entire stack of sheets in the unloading direction. Therefore, in the following embodiments, a structure is provided that can vary the amount of pushing the entire stack of sheets according to the remaining amount of the stack of sheets.

[0016] When the stack of sheets is full in the storage space, the structure consists of the first biasing means and the support plate, and the second biasing means and the support plate being integrated into a single thickness. With this configuration, the entire stack of sheets can be biased in the unloading direction. Then, when the sheets are sequentially unloaded from the uppermost sheet of the stack of sheets and the stack of sheets decreases, it prevents the uppermost sheet from moving away from the unloading mechanism. And even when the intermediate stack approaches empty, the position of the tip of the uppermost sheet is maintained at the contact position with the unloading mechanism. As a result, during the period from the intermediate stack to empty, which is likely to occur due to non-contact between the unloading mechanism for unloading the sheet P and the tip portion of the sheet P, the rear end of the stack of sheets is supported and the tip position of the uppermost sheet is maintained at a predetermined position, preventing abnormal unloading.

[0017] [Embodiment of Image Forming Apparatus] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a printer 100 which is an embodiment of an image forming apparatus according to the present invention. As shown in FIG. 1, the printer 100 includes an unloading roller (paper feeding roller) 101, an intermediate roller 102, a registration roller 103, a photoreceptor 104, a charging device 105, an LED 106, a transfer roller 107, a fixing roller 108, a fixed discharge roller 109, a paper discharge roller 110, a paper discharge tray 111, a manual feed tray 112, and a manual feed roller 113 as an unloading means for feeding and unloading the sheet P.

[0018] At the bottom of the printer 100, a sheet feeding device 200, which is an embodiment of the sheet feeding device according to the present invention, is mounted. As will be described later, the sheet feeding device 200 as the sheet feeding unit is installed at the bottom of the printer 100. Note that the printer 100 corresponds to "another device" with respect to the sheet feeding device 200. Therefore, the sheet feeding device 200 is a device that supplies the sheet P, which is a sheet-like recording medium, to another device, the printer 100, and a new sheet feeding device 200 can be added to the bottom of the sheet feeding device 200.

[0019] The sheet feeding device 200 includes a sheet storage space 210 of a sheet feeding tray for storing and feeding the sheet P. In the sheet storage space 210, a bundle of sheets P (sheet bundle Pb) is stored. The top sheet Pt at the top of the sheet bundle Pb stored in the sheet storage space 210 is biased so that the leading end portion contacts the carry-out roller 101 as the carry-out means provided in the printer 100. When the carry-out roller 101 rotates, the top sheet Pt is pulled out in the Y direction by the friction with the carry-out roller 101, passes between the separation rollers 201, and is carried out as a single sheet P toward the relay roller 102 on the downstream side in the sheet conveyance direction of the printer 100.

[0020] The sheet P sent out from the sheet feeding device 200 is conveyed by the relay roller 102 along the conveyance path indicated by the dotted arrow. The sheet P carried out from the sheet storage space 210 is temporarily stopped by the registration roller 103, and the conveyance is restarted at a predetermined timing according to the transfer timing of the toner image. The carry-out roller 101, the relay roller 102, the registration roller 103, the fixed discharge roller 109, and the paper discharge roller 110 constitute a conveyance unit that conveys the sheet P to the image forming unit formed by the photoreceptor 104 and discharges the sheet P with the image transferred outside the device. Note that the printer 100 also includes a manual tray 112 and a manual roller 113 that supplies the sheet P from the manual tray 112 as another sheet supply means different from the sheet feeding device 200.

[0021] The printer 100 includes, around the photoreceptor 104, a charging device 105 that charges the surface of the photoreceptor 104, and an LED 106 as a light source that exposes the charged surface of the photoreceptor 104 according to image information to form an electrostatic latent image on the photoreceptor 104. By the operation of these image forming units, an image to be transferred to the sheet P is formed.

[0022] For the toner image formed on the photoreceptor 104, at a predetermined timing, the conveyance by the registration roller 103 is started, and the sheet P is conveyed between the photoreceptor 104 and the transfer roller 107, so that the toner image on the photoreceptor 104 is transferred to the sheet P.

[0023] Thereafter, the sheet P is conveyed to a fixing roller 108 that fixes the transferred toner image, passes through a discharge roller 109 and a paper ejection roller 110, and is discharged to a paper ejection tray provided on the upper surface of the housing of the printer 100.

[0024] The paper feed tray of the sheet feeding device 200 is a front loading type sheet storage means having a structure that slides in the front direction, which is the X direction in FIG. 1, with respect to the apparatus main body of the printer 100. Note that a drawer that slides in the Y direction may also be used. Further, the carry-out roller 101 may be provided in the apparatus main body of the printer 100 or in the sheet feeding device 200, and may be pulled out integrally with the paper feed tray.

[0025] The sheet feeding device 200 has a bottom plate 230 that forms a sheet storage space 210, which corresponds to the placement surface of the sheet bundle Pb. At the end of the bottom plate 230 on the unloading direction side (the downstream end), a spring 240 is arranged as a bottom plate moving member that biases and moves the end of the bottom plate 230 upward. The end of the bottom plate 230 on the side opposite to the unloading direction (the upstream end) is supported by the sheet feeding device 200 on the upstream side of the conveyance direction from the center of the sheet and on the downstream side of the end fence 220. Also, the end on the unloading direction side is supported by the spring 240. With these configurations, the bottom plate 230 rotates and moves with the opposite end as a pivot point. Therefore, depending on the amount of the sheet bundle Pb placed on the bottom plate 230, the end on the unloading direction side moves in the vertical direction due to the elastic force of the spring 240 as an elastic member.

[0026] When the sheet storage space 210 is full of the sheet P, due to the load of the sheet bundle Pb, the bottom plate 230 is in a state substantially parallel to the placement surface of the sheet feeding device 200. At this time, since the end of the bottom plate 230 on the conveyance direction side is continuously biased upward by the biasing of the spring 240, the leading end portion of the topmost sheet Pt is in a state of being pressed in a tangential direction against the unloading roller 101.

[0027] Therefore, the sheet bundle Pb placed in the sheet storage space 210 is sent downstream in the conveyance direction by the unloading roller 101, and when supplying the sheet P to the printer 100, the separation roller 201 sends out the single sheets of the sheet P one by one into the conveyance path.

[0028] [Embodiment of Sheet Feeding Device] Next, the sheet feeding device 200, which is an embodiment of the sheet feeding device according to the present invention, will be described in detail. FIG. 2 is a cross-sectional view of the sheet feeding device 200 as viewed from the side. As shown in FIG. 2, the sheet feeding device 200 includes an end fence 220 as a support member that supports the rear end portion of the sheet bundle at a portion corresponding to the end of the sheet storage space 210 and opposite to the unloading direction of the sheet P. The end fence 220 has a structure that can be selectively fixed to a predetermined position in the sheet storage space 210.

[0029] The end fence 220 has a vertically long portion 2271 that rotatably holds vertically long support plates (221, 222) for supporting the rear end portion of the sheet bundle Pb, and a bottom portion 2261 that supports the vertically long portion 2271. The bottom portion 2261 extends to the carry-out side and has a structure that can be fixed at a predetermined position in the sheet storage space 210. The height dimension of the end fence 220 is regulated by the depth of the sheet storage space 210, and the height dimensions of the support plates (221, 222) are regulated by the height dimension of the end fence 220.

[0030] The bottom plate 230, which is a sheet support member that constitutes the bottom of the sheet storage space 210, is an angle adjustment means for changing the angle of the bottom plate 230 according to the remaining amount of the sheet bundle Pb. This angle adjustment means also includes a spring 240 that lifts one end of the bottom plate 230 to maintain the contact state with the carry-out roller 101 of the uppermost sheet Pt. When the bottom plate 230 rotates and moves by the spring 240 according to the remaining amount of the sheet bundle Pb, the position of the tip of each uppermost sheet Pt with respect to the carry-out roller 101 shifts to the upstream side, and the angle with respect to the carry-out roller 101 becomes variable from the tangential direction. This shift is adjusted by the end fence 220, and the details will be described later.

[0031] FIG. 2(a) illustrates a state where the sheet bundle Pb is full with respect to the storage capacity of the sheet storage space 210. On the other hand, FIG. 2(b) illustrates a state when the sheet P is carried out and the sheet bundle Pb is nearly empty. Note that various sheet supply methods by the sheet feeding device 200 are known. In the present embodiment, the separation roller (roller) 201 method is exemplified, but the separation pad method may also be used. In the present embodiment, the biasing force for bringing the uppermost sheet Pt into contact with the carry-out roller 101 is realized by a structure that allows one end of the bottom plate 230 to move in the vertical direction. Note that the structure for biasing the uppermost sheet Pt of the sheet bundle Pb stored in the sheet storage space 210 in a direction to continuously contact the carry-out roller 101 is not limited to the structure exemplified in the present embodiment. A structure that biases the end portion of the bottom plate 230 to push it upward from below may be used, or it may be performed by driving a rotating shaft.

[0032] As shown in FIG. 2(a), when the sheet P is in a full-load state or a state close to full-load, the spring 240 extends due to the load of the sheet bundle Pb, the tip portion of the bottom plate 230 descends, and it becomes in a state substantially parallel to the grounding surface of the paper feed tray. Also at this time, since the tip portion of the bottom plate 230 is continuously biased upward by the spring 240, the topmost sheet Pt is pressed in contact at the contact position with the carry-out roller 101.

[0033] Also, in the state of FIG. 2(a), the bottom plate 230 is slightly inclined. Due to this inclination, a load is also applied to the rear end side of the sheet bundle Pb, so that the end fence 220 supports the sheet bundle Pb so as to maintain it at a predetermined position. At this time, by the rear-end pressing force Mp of the load of the sheet bundle Pb as the force applied to the end fence 220 by the sheet bundle Pb, the first support plate 221 and the second support plate 222 as the support members provided with biasing means are in a state of being pushed to the rearmost side. And by these support members, the rear end of the sheet bundle Pb is biased in the carry-out direction, thereby preventing the downstream tip of the topmost sheet Pt from shifting to the rear end side.

[0034] When the single-sheet sheet P is carried out and the remaining amount decreases to a state where the sheet bundle Pb is nearly empty, the load on the bottom plate 230 decreases. In this case, as shown in FIG. 2(b), the tip of the bottom plate 230 rises by the elastic force of the spring 240 as the angle adjusting means, and the state of pressing the topmost sheet Pt against the carry-out roller 101 is maintained.

[0035] Also, in the state of Fig. 2(b), the inclination of the bottom plate 230 is severely large. Therefore, the force trying to move the sheet bundle Pb toward the rear end side of the bottom plate 230 increases. However, the rear end pressing force Mp weakens as the sheet P decreases. Thus, relatively, the biasing force Ms prevails, and due to the biasing force of the first elastic body 223 as the first biasing means provided in the end fence 220, the first support plate 221 as the first support member moves toward the conveyance direction side to support the position of the rear end of the sheet bundle Pb. Further, as will be described later, the end fence 220 also biases the second support plate 222 as the second support member toward the conveyance direction side. This second support plate 222 moves toward the unloading direction side by the biasing force of the second elastic body 224 as the second biasing means to support the position of the rear end of the sheet bundle Pb. As a result, the state where the tip of the uppermost sheet Pt reaches the contact position of the unloading roller 101 can be maintained.

[0036] [First Embodiment] Next, the end fence 220 according to the first embodiment will be described in detail with reference to Figs. 3 to 5. As already described, the end fence 220, which is a rear end regulating member that regulates the rear end of the sheet on the upstream side in the sheet conveyance direction, supports the rear end portion of the sheet bundle Pb (sheet P) placed in the sheet accommodation space 210 provided in the sheet feeding device 200. Thereby, regardless of the amount of the sheet bundle Pb (sheet P), the position where the uppermost sheet Pt contacts the unloading roller 101 can be maintained.

[0037] Fig. 3 illustrates the state of the end fence 220 when the remaining amount of the sheet bundle Pb accommodated in the sheet accommodation space 210 has decreased and is nearly empty. Fig. 4 illustrates the state of the end fence 220 when the sheet bundle Pb is full. Fig. 5 illustrates the state of the end fence 220 when the remaining amount of the sheet bundle Pb has decreased and is near the middle between full and empty.

[0038] The end fence 220 has a structure that fits with the sheet feeding device 200, is disposed on the rear end side of the sheet storage space 210, and has a configuration that can change its position relative to the bottom plate 230 according to the size of the sheet P. The end fence 220 fitted with the sheet feeding device 200 is in a state of supporting the rear end side of the sheet bundle Pb. As a result, when the inclination of the bottom plate 230 becomes steep and large as the unloading of the sheet P continues and the remaining amount of the sheet bundle Pb decreases, it is possible to prevent the leading end portion of the sheet bundle Pb from shifting in the direction opposite to the conveyance direction.

[0039] Using FIG. 3, the structure of the end fence 220 according to the first embodiment will be described. The end fence 220 includes a first support plate 221 as a first support member that constitutes an end support member, and a second support plate 222 as a second support member that also constitutes an end support member. One end of the first support plate 221 is fixed to the upper end portion of the end fence body 227, and the other end side is supported by the end fence body 227 so as to rotate about this one end side as a rotation center. One end of the second support plate 222 is fixed near the middle part below between one end and the other end of the first support plate 221, and the other end side is supported by the first support plate 221 so as to rotate about this one end side as a rotation axis.

[0040] The first support plate 221 is a rectangular plate-like shape having a short dimension substantially equivalent to the height dimension of the end fence 220, and a groove portion 2213 is formed slightly below the vicinity of the center in the longitudinal vertical direction. And with the groove portion 2213 as a boundary, there are a thin plate portion 2212 that becomes a portion with different thicknesses above and below, and a side end portion 2211 that has the same thickness as the upper side and is located in the width direction of the thin plate portion 2212.

[0041] One end of the second support plate 222 is rotatably engaged with the groove portion 2213 of the first support plate 221. The second support plate 222 is a plate member thinner than the first support plate 221. The thickness of the second support plate 222 combines with the thickness of the thin plate portion 2212 of the first support plate 221 to become the same thickness as the first support plate 221.

[0042] Therefore, when the sheet bundle Pb is fully loaded and the bottom plate 230 is in a substantially flat state with the rear end of the sheet bundle Pb approaching the end fence body 227, the second support plate 222 is positioned to be sandwiched between the side end portions 2211 of the first support plate 221. As a result, the sheet bundle Pb can be fully loaded into the sheet storage space 210.

[0043] FIG. 3(b) is a cross-sectional view taken along the line A-A in FIG. 3(a). As shown in FIG. 3(b), a first elastic body 223 as a first biasing means is disposed on the lower end side of the first support plate 221. One end of the first elastic body is attached to the end fence body 227, and the other end is attached to the lower end of the first support plate 221. By the elastic force of the first elastic body 223, the first support plate 221 is biased in the Y direction. That is, the first support plate 221 biases the sheet bundle Pb toward the carry-out roller 101 side and supports it so as to reach a position where the uppermost sheet Pt contacts the carry-out roller 101. The first elastic body 223 is, for example, a spring. Although the first elastic body 223 is described by way of example as a spring in the present embodiment, any elastic member capable of biasing the first support plate 221 as a first support member in a predetermined direction can be applied other than a spring.

[0044] In addition, a second elastic body 224 as a second biasing means is disposed at the lower end of the second support plate 222. One end of the second elastic body is attached to the first support plate 221, and the other end is attached to the lower end of the second support plate 222. By the elastic force of the second elastic body 224, the second support plate 222 is biased in the Y direction. That is, the second support plate 222 supports the sheet bundle Pb toward the carry-out roller 101 side, moves the position of the rear end of the sheet bundle Pb with a reduced remaining amount in the carry-out direction, and supports it, and maintains the position of the leading end portion of the uppermost sheet Pt at the contact position with the carry-out roller 101. The second elastic body 224 is, for example, a spring. Regarding the second elastic body 224 as well, although the description in the present embodiment is given by way of example of a spring, any elastic member capable of biasing the second support plate 222 as a second support member in a predetermined direction can be applied other than a spring.

[0045] In addition, the end fence body 227 is provided with a rail portion 229 that enables it to move relative to the bottom plate 230 in the unloading direction. The rail portion 229 is slidably fitted into a rail groove formed in the sheet feeding device 200. The rail groove is formed along the unloading direction of the sheet P. Therefore, the end fence 220 can move the first support plate 221 and the second support plate 222 to a predetermined position along the rail groove according to the size of the sheet P, and can support the rear end in the conveying direction of the sheet P at the moved position.

[0046] Moreover, at the bottom of the end fence body 227, a first stopper 225 and a second stopper 226 are arranged as restricting means for restricting the operating range of the biasing means. The first stopper 225 is a first stopping member that restricts the moving range of the first support plate 221 in the Y direction, and there are two of them in the width direction of the sheet P. The first stopper 225 is an inclined member that rises from the bottom of the end fence body 227 and has an inclined portion.

[0047] The first stopper 225 is arranged at a position where it contacts the side end portion 2211 of the first support plate 221 that has rotated to a predetermined position due to the biasing of the first elastic body 223. When the side end portion 2211 contacts the first stopper 225, the rotation of the first support plate 221 is restricted. The first stopper 225 has a predetermined height dimension so as to contact above the lower end of the side end portion 2211.

[0048] The first stopper 225 restricts the first support plate 221 biased by the first elastic body 223 from moving too far in the Y direction. Assuming that the first stopper 225 is not provided, when the remaining amount of the sheet bundle Pb runs out, the first support plate 221 can move unrestrictedly in the Y direction by the amount that the first elastic body 223 extends with respect to the Y direction. In that case, when attempting to replenish the sheet bundle Pb into the sheet storage space 210, a gap is formed where a part of the sheet bundle Pb enters between the first support plate 221 and the bottom plate 230. As a result, the sheet bundle Pb cannot be properly biased by the first support plate 221. Therefore, the first stopper 225 is arranged such that the tip of the first stopper 225 is positioned at a predetermined position that restricts the movement of the lower end of the first support plate 221 when the first support plate 221 rotates.

[0049] Also, on the end fence body 227, two second stoppers 226 as second stop members that restrict the movement range of the second support plate 222 in the Y direction are provided at the bottom between the two first stoppers 225 in the sheet width direction. The second stopper 226 is an inclined member that rises from the bottom of the end fence body 227 and has an inclined portion. After the side end portion 2211 of the first support plate 221 that has rotated to a predetermined position contacts the first stopper 225 and the movement of the first support plate 221 in the Y direction is restricted, the portion of the second stopper 226 that engages with the second support plate 222 is formed on the sheet P carry-out direction side rather than the portion of the first stopper 225 that engages with the first support plate 221 so as to restrict the second support plate 222 that moves in the Y direction by the elastic force of the second elastic body 224. The second stopper 226 has a predetermined height dimension so as to contact above the lower end of the second support plate 222.

[0050] The shape of the second stopper 226, similar to the first stopper 225, has an inclined shape that rises from the bottom of the end fence body 227 and has an inclined portion. By placing the rear end of the sheet bundle Pb on this inclined portion, it is possible to prevent the sheet P positioned at the lowermost position of the sheet bundle Pb from entering the gap between the lower ends of the first support plate 221 and the second support plate 222 and the bottom plate 230.

[0051] Next, the operation of the end fence 220 will be described. As shown in FIG. 4, when the sheet bundle Pb is full in the sheet storage space 210, the inclination of the bottom plate 230 is in the loosest state (see FIG. 2(a)). In this state, the front end side of the bottom plate 230 is biased upward by the spring 240, so that the uppermost sheet Pt is kept in pressure contact with the carry-out roller 101. At this time, since a large load of the sheet bundle Pb is applied to the end fence 220 that supports the rear end of the sheet bundle Pb, the rear end pressing force Mp is larger than the biasing force (Ms2) of the second elastic body 224 that biases the second support plate 222. Therefore, the second support plate 222 is in contact with the thin plate portion 2212 of the first support plate 221 and appears to be integrated.

[0052] Also, when the sheet bundle Pb is full in the sheet storage space 210, the rear end pressing force Mp is larger than the biasing force (Ms1) of the first elastic body 223 that biases the full-load first support plate 221. Therefore, the lower end of the first support plate 221 stays at the position closest to the back side of the end fence body 227.

[0053] Note that even when the sheet bundle Pb is full, the first support plate 221 always biases the sheet bundle Pb in the direction of the carry-out roller 101 by the elastic force (Ms1) of the first elastic body 223. Similarly, the second support plate 222 always biases the sheet bundle Pb in the direction of the carry-out roller 101 by the elastic force (Ms2) of the second elastic body 224.

[0054] When the remaining amount of the sheet bundle Pb decreases from the state illustrated in FIG. 4, the rear end pressing force Mp weakens. As a result, first, the elastic force (Ms1) of the first elastic body 223 that exerts a first biasing force having a larger elastic force than the elastic force (Ms2) of the second elastic body 224 that exerts a second biasing force causes the first support plate 221 to move in the Y direction and reach the state shown in FIG. 5.

[0055] Then, as shown in FIG. 5, the first support plate 221 reaches a position where its movement is restricted by the first stopper 225. In this state, the remaining amount of the sheet bundle Pb is reduced slightly from about half of the full load (medium load). At this time, the inclination of the bottom plate 230 is also medium.

[0056] When the sheet P is further discharged from the state shown in FIG. 5 and the sheet bundle Pb decreases, the rear-end pressing force Mp weakens. However, since the inclination of the bottom plate 230 becomes steep and large, the sheet bundle Pb tends to slide down toward the end fence 220 with an increasing tendency. When this state is reached, the second support plate 222 can move in the Y direction by the elastic force (Ms1) of the second elastic body 224 that exerts the second biasing force. FIG. 3 illustrates this state. That is, in the state illustrated in FIG. 3, against the rear-end pressing force Mp, the second biasing force prevents the sheet bundle Pb from sliding in the rear-end direction. As a result, the leading end portion downstream in the conveyance direction of the uppermost sheet Pt can be maintained at an appropriate contact position with the discharge roller 101. That is, although the inclination of the bottom plate 230 is large, the position where the leading end of the uppermost sheet Pt downstream in the conveyance direction contacts the discharge roller 101 is shifted downstream in the conveyance direction and contacts the discharge roller 101 in the tangential direction as in the full-load state.

[0057] As described above, the end fence 220 according to the first embodiment includes the first support plate 221 and the second support plate 222, and has a configuration in which the biasing force for biasing the sheet bundle Pb in the discharge direction is gradually switched from a state of being biased by two elastic bodies to a state of being biased by one elastic body according to the remaining amount of the sheet bundle Pb in the sheet storage space 210. That is, with this configuration, until the remaining amount of the sheet bundle Pb decreases and the inclination of the bottom plate 230 increases, the sheet bundle Pb with a large remaining amount is mainly biased by the first biasing force to restrict the rear end at a predetermined position. Then, when the remaining amount of the sheet bundle Pb decreases and the inclination of the bottom plate 230 increases, the sheet bundle Pb with a small remaining amount is biased by the second biasing force to restrict the rear end at a predetermined position.

[0058] That is, even if the height dimension of the first support plate 221 is shortened to make the end fence 220 smaller without increasing the movement amount of the first support plate 221 that exerts the first biasing force, by using the second support plate 222 together, the rear end of the sheet bundle Pb can be restricted.

[0059] Therefore, according to the end fence 220 according to the first embodiment, even if the height dimension of the first support plate 221 is shortened (even if the end fence 220 is lowered), the state in which the uppermost sheet Pt is in pressure contact with the carry-out roller 101 can be maintained.

[0060] That is, even if the sheet supply device 200 is made thin (small-sized), since the state in which the uppermost sheet Pt appropriately contacts the carry-out roller 101 is maintained from when the sheets are fully loaded until the final sheet is carried out, a sheet supply device 200 that can prevent carry-out failures even if it is small-sized can be obtained.

[0061] [Second Embodiment] Next, the end fence 220a according to the second embodiment will be described in detail with reference to FIGS. 6 and 7. FIG. 6 illustrates the state of the end fence 220a when the remaining amount of the sheet bundle Pb accommodated in the sheet accommodation space 210 has decreased. FIG. 7 illustrates the state of the end fence 220a when the sheet bundle Pb is fully loaded.

[0062] In the following description, for the configurations and functions common to the first embodiment, detailed descriptions will be omitted, and the configurations showing the features of the second embodiment will be described.

[0063] The end fence 220a is disposed on the rear end side of the sheet storage space 210, can change its position relative to the bottom plate 230 according to the size of the sheet P, and can be fixed in a state relative to the bottom plate 230. The end fence 220a fixed to the bottom plate 230 has a structure that always biases toward the unloading direction while supporting the rear end side of the sheet bundle Pb accommodated in the sheet storage space 210. As a result, when the inclination of the bottom plate 230 becomes steep and large as the unloading of the sheet P continues and the remaining amount of the sheet bundle Pb decreases, it is possible to prevent the front end portion of the sheet bundle Pb from shifting in the direction opposite to the conveyance direction.

[0064] The structure of the end fence 220a according to the second embodiment will be described with reference to FIG. 6. The end fence 220a includes a first support plate 221 and a second support plate 222a as end support members. The first support plate 221 is similar to the first support plate 221, one end of which is fixed to the upper end portion of the end fence main body 227, and is supported by the end fence main body 227 so that the other end side rotates about this one end side as a rotation axis.

[0065] The second support plate 222a has a structure different from that of the second support plate 222. That is, the second support plate 222a is a plate-like member having substantially the same height dimension as the first support plate 221. The second support plate 222a has an upper end portion formed by extending upward, an upper end portion 2221a inclined toward the first support plate 221, and a side end portion formed by extending the side end portion and inclined toward the first support plate 221, a side end portion 2221b.

[0066] The upper end portion 2221a is a structure for deflecting and protecting the rear end portion of the sheet bundle Pb that fits into the sheet storage space 210 from above the end fence 220a when the sheet bundle Pb is placed in the sheet storage space 210, so that it does not catch on the second support plate 222a. Assuming a structure without the upper end portion 2221a, the rear end portion of the sheet bundle Pb would catch on the upper end of the second support plate 222a. As a result, problems such as the second support plate 222a peeling off from the first support plate 221 or damaging the sheet P may occur. Therefore, by providing the upper end portion 2221a, it is possible to prevent damage to the end fence 220a and the sheet P when replenishing the sheet bundle Pb into the sheet storage space 210.

[0067] The side end portion 2221b is a structure for protecting the sheet P so that it does not catch on the second support plate 222a when the sheet P is carried out or when the sheet bundle Pb is placed in the sheet storage space 210. Assuming a structure without the side end portion 2221b, the side end portion of the second support plate 222a would be left exposed. In that case, when the sheet P is carried out or the sheet bundle Pb is replenished, the sheet P may catch on the side end portion, causing the rear end of the sheet P to float. When the rear end portion of the sheet P is in a floating state, even if the sheet bundle Pb is urged toward the carry-out roller 101 by the end fence 220a, there is a possibility that the tip of the topmost sheet Pt will not reach the predetermined contact position, leading to an abnormal carry-out.

[0068] Also, the position of the sheet bundle Pb in the width direction in the sheet storage space 210 may be adjusted by a side fence or the like for regulating the position of the sheet bundle Pb in the width direction. At that time, when adjusting while shifting the position of the sheet bundle Pb in the width direction, the rear end portion of the sheet bundle Pb may hit the side end portion of the second support plate 222a.

[0069] Moreover, if the lateral end portion 2221b is absent, the second support plate 222a will not be able to deflect the sheet bundle Pb. As a result, problems such as the second support plate 222a peeling off from the first support plate 221 or damaging the sheet P may occur.

[0070] Note that the lower end portion of the lateral end portion 2221b is shaped obliquely toward the first support plate 221. By making it oblique in this way, it is possible to prevent the sheet bundle Pb with a reduced remaining amount from getting caught on the lateral end portion 2221b. Also, when replenishing the sheet bundle Pb in small amounts instead of filling it to capacity, it is possible to prevent the lowermost sheet P of the sheet bundle Pb from being pinched between the lower end portion of the lateral end portion 2221b and the first stopper 225. If the lowermost sheet P of the sheet bundle Pb is pinched between the lower end portion of the lateral end portion 2221b and the first stopper 225, although it is a small force, a pulling force is required when pulling out the sheet P. If the conveying output of the conveying roller 101 is weak compared to that pulling force, abnormal conveyance will occur.

[0071] Therefore, by providing the lateral end portion 2221b, it is possible to prevent damage to the end fence 220a and damage to the sheet P when replenishing the sheet bundle Pb into the sheet storage space 210. Also, it is possible to prevent the sheet P from being pinched between the second support plate 222a and the first stopper 225 and causing abnormal conveyance.

[0072] At the lower end of the first support plate 221, a first elastic body 223 as a first biasing means is disposed, with one end attached to the end fence body 227 and the other end attached to the lower end of the first support plate 221. The first support plate 221 is configured to be biased in the Y direction by the elastic force of the first elastic body 223. That is, the first support plate 221 is biased in the direction of pressing against the sheet bundle Pb toward the position of the conveying roller 101. When the rear end of the sheet bundle Pb contacts the first support plate 221, the state where the uppermost sheet Pt reaches the contact position with the conveying roller 101 is maintained.

[0073] On the back side of the second support plate 222, a second elastic body 224a as a second biasing means is disposed between the second support plate 222 and the first support plate 221. The second elastic body 224a is composed of any one of rubber, sponge, and other materials that exhibit elastic force, and is a plate-like member having a predetermined thickness.

[0074] The second elastic body 224a exerts a second biasing force and biases the second support plate 222 in the Y direction. The second elastic body 224a biases the entire second support plate 222a uniformly in the Y direction. When the rear end of the sheet bundle Pb with a reduced remaining amount comes into contact with the second support plate 222a, the second elastic body 224a applies the second biasing force to the sheet bundle Pb so as to press the uppermost sheet Pt against the contact position with the carry-out roller 101.

[0075] When the sheet bundle Pb is full, as illustrated in FIG. 7, the second elastic body 224a provided in the end fence 220a is crushed and thinned. At this time, the second support plate 222a is in a state closest to the first support plate 221. As the sheet P is carried out from the state of FIG. 7 and the remaining amount of the sheet bundle Pb decreases, the rear end pressing contact force Mp decreases, and the lower end of the first support plate 221 rotates in the Y direction by the first biasing force (Ms1). Then, when the remaining amount of the sheet bundle Pb further decreases from the position where the rotation of the first support plate 221 is restricted by the first stopper 225, the second support plate 222a moves in the Y direction by the second biasing force (Ms2).

[0076] As described above, the end fence 220a according to the second embodiment includes the first support plate 221 and the second support plate 222a, and has a configuration in which the biasing force for biasing the sheet bundle Pb in the carry-out direction is switched stepwise according to the remaining amount of the sheet bundle Pb in the sheet storage space 210. In other words, the end fence 220a can switch stepwise between holding the uppermost sheet Pt at the contact position by the first support plate 221 and holding the uppermost sheet Pt at the contact position by the second support plate 222a according to the degree of decrease in the remaining amount of the sheet bundle Pb.

[0077] With this configuration, until the remaining amount of the sheet stack Pb decreases and the inclination of the bottom plate 230 increases, the sheet stack Pb with a large remaining amount is biased by the first biasing force. Then, when the remaining amount of the sheet stack Pb decreases and the inclination of the bottom plate 230 increases, the sheet stack Pb with a small remaining amount is biased by the first biasing force and the second biasing force to regulate the rear end at a predetermined position.

[0078] That is, even if the height dimension of the first support plate 221 is shortened without increasing the movement amount of the first support plate 221 that exerts the first biasing force and the end fence 220a is made smaller, by using the second support plate 222a together, the position of the rear end of the sheet stack Pb can be regulated at a predetermined position.

[0079] Note that the present invention can be used not only for the sheet feeding device of the paper feed tray, but also for the sheet feeding device of the manual feed tray, the sheet feeding device of the document feed tray of a copying machine, etc. The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist thereof. All technical matters included in the technical idea described in the claims are the subject of the present invention. The above embodiments show preferred examples, but those skilled in the art can realize various modifications from the disclosed content. Such modifications are also included in the technical scope described in the claims.

Explanation of Reference Numerals

[0080] 100: Printer 101: Discharge roller 102: Relay roller 103: Registration roller 104: Photoconductor 105: Charging device 106: LED 107: Transfer roller 108: Fusing roller 109: Constant discharge roller 110: Paper discharge roller 111: Output tray 112: Manual feed tray 113: Manual feed roller 200: Sheet feeding device 201: Separation roller 210: Sheet storage space 220: End fence according to the first embodiment 220a: End fence according to the second embodiment 221: First support plate according to the first embodiment 222: Second support plate according to the first embodiment 222a: Second support plate according to the second embodiment 223: First elastic body according to the first embodiment 224: Second elastic body according to the first embodiment 224a: Second elastic body according to the second embodiment 225: First stopper 226: Second stopper 227: End fence body 229: Rail part 230: Bottom plate 240: Spring 2211: Side end part 2212: Thin plate part 2213: Groove part 2221a: Upper end part 2221b: Side end part 2261: Bottom part 2271: Vertically long part

Prior art documents

Patent documents

[0081]

Patent Document 1

Claims

1. A sheet feeding device for feeding a sheet accommodated in an accommodation space, comprising: a carrying-out means for carrying out the uppermost sheet at the top of a sheet bundle composed of a plurality of sheets accommodated in the accommodation space in the conveying direction; an angle adjusting means for adjusting the angle of the sheet with respect to the conveying direction according to the remaining amount of the sheet in the accommodation space; a biasing means for stepwise biasing the end portion of the uppermost sheet toward the side of the carrying-out means according to the remaining amount of the sheet; characterized in that it comprises: the biasing means is an end fence for supporting the sheet toward the downstream side in the conveying direction, the end fence comprises an end portion supporting member for supporting the end portion of the sheet bundle, a first biasing means for biasing the end portion supporting member toward the downstream side in the conveying direction, a second biasing means for biasing the end portion supporting member toward the downstream side in the conveying direction with a biasing force weaker than that of the first biasing means; characterized in that it comprises: when the remaining amount of the sheet is equal to or more than a predetermined amount, the first biasing means and the second biasing means bias the end portion of the uppermost sheet toward the side of the carrying-out means; when the remaining amount of the sheet is less than the predetermined amount, the biasing of the end portion supporting member by the first biasing means stops, and thereafter, only the second biasing means biases the end portion of the uppermost sheet toward the side of the carrying-out means. A sheet feeding device characterized by the above.

2. The sheet feeding device according to claim 1, further comprising the carrying-out means as a carrying-out roller for carrying out the uppermost sheet from the accommodation space to the downstream side in the conveying direction, and the angle adjusting means for varying the inclination of the uppermost sheet.

3. The angle adjusting means comprises a bottom plate constituting the bottom of the accommodation space, and a bottom plate moving member for moving the bottom plate in the vertical direction, wherein the bottom plate moving member is an elastic member for moving one end of the bottom plate. The sheet feeding device according to claim 1 or 2.

4. The end portion supporting member biases the sheet bundle by the first biasing means and the second biasing means when the accommodation space is full of the sheets, and biases the sheet bundle by the second biasing means when the amount of the sheets accommodated in the accommodation space decreases. The sheet feeding device according to any one of claims 1 to 3.

5. The end portion supporting member is distinguished into a first supporting member and a second supporting member, the first supporting member biases the sheet bundle by the first biasing means, The second support member biases the sheet bundle by the second biasing means, and the sheet feeding device according to any one of claims 1 to 4.

6. The upper end of the first support member is held by the end fence body, the first biasing means is disposed at the lower end, and the lower end is rotatable about the upper end as a rotation center. The second support member has one end held by the first support member, the second biasing means is disposed at the other end, and the other end is rotatable about the one end as a rotation center. The sheet feeding device according to claim 5.

7. The upper end of the first support member is held by the end fence body, the first biasing means is disposed at the lower end, and the lower end is rotatable about the upper end as a rotation center. The second support member has the second biasing means disposed thereon. The second biasing means is disposed on the first support member. The sheet feeding device according to claim 5 or 6.

8. A first stop member that restricts movement of the first support member toward the carry-out means at a predetermined position; A second stop member that restricts movement of the second support member toward the carry-out means at a predetermined position, and The second stop member is disposed closer to the carry-out means than the first stop member. The sheet feeding device according to any one of claims 5 to 7.

9. The position where the first stop member contacts the first support member is above the lower end of the first support member. The position where the second stop member contacts the second support member is above the lower end of the second support member. The sheet feeding device according to claim 8.

10. The first biasing means and the second biasing means are elastic members. The sheet feeding device according to any one of claims 1 to 9.

11. An image forming unit that forms an image on a sheet; A conveyance unit that conveys the sheet carried out from the accommodation space to the image forming unit; An image forming apparatus including a sheet feeding unit that supplies the sheet to the conveyance unit, wherein The sheet feeding unit is the sheet feeding device according to any one of claims 1 to 10. An image forming apparatus characterized by this.

Images