JP7707560B2 - Sheet feeding device and image forming apparatus - Google Patents

Description

The present invention relates to a sheet feeding device and an image forming device.

Sheet feeders are known that supply recording media to image forming devices that form images on sheet-like recording media. There are various types of sheet feeders, but they generally have a storage space that stores sheets as recording media in a sheet stack, and a mechanism that discharges individual sheets from one end of the storage space. Furthermore, sheet feeders applied to small image forming devices are often located on the bottom of the image forming device.

A known mechanism for ejecting sheets from the storage space of a sheet feeder is one that has an ejection roller that rotates in contact with the top sheet of a sheet stack, and ejects the sheet in a specified transport direction by the operation of the roller. In this case, when the remaining amount of sheets in the stack decreases, the relative position of the leading edge of the top sheet to the ejection roller changes, causing insufficient contact between the ejection roller and the top sheet, resulting in poor ejection.

To prevent this, for example, a configuration is known in which one end of the bottom plate of the storage space is biased in a lifting direction by an elastic member such as a spring so that the end of the sheet stack on the sheet discharge side remains in contact with the discharge roller, thereby maintaining contact between the discharge roller and the topmost sheet.

In addition, a technology is known that relates to an end fence that urges the sheet stack in the discharge direction to support it, in order to prevent the sheet stack as a whole from shifting away from the discharge rollers as the inclination of the bottom plate increases with the remaining amount of the sheet stack (see Patent Document 1).

However, with the technology disclosed in Patent Document 1, it was difficult to accurately maintain contact between the discharge roller and the top sheet from the full-load state in which the storage space is filled with sheets until the last sheet is discharged. When the remaining amount of sheets in the stack approaches zero, the leading edge of the top sheet of the stack, which now has a small number of sheets, shifts significantly toward the opposite side of the discharge direction. In that case, the force of the end fence is increased to push the stack of sheets in the discharge direction as the remaining amount of sheets in the stack decreases.

As a result, even when the end fence technology disclosed in Patent Document 1 is used, there is a problem in accurately preventing sheet discharge failure from full to empty. To increase the pushing out of the sheet stack, the dimensions of the sheet support part of the end fence can be increased even if the rotational movement amount of the part remains the same. However, to increase the length of the support part, it becomes necessary to increase the height dimension of the sheet feeder, which makes miniaturization difficult. On the other hand, if the dimensions of the support part are the same and the rotational movement amount of the support part is increased, a sufficient spring force is required for this. Conversely, this large force causes the leading edge of the sheets when fully loaded to be pressed against the leading edge regulating part, making it difficult to move the bottom plate and causing transport failure.

Therefore, in conventional technology, there was a problem in making the sheet supply device small (thin) while preventing discharge failures from when the sheet is fully loaded until the final sheet is discharged.

The present invention aims to provide a compact sheet feeder that maintains contact of the sheets with the discharge rollers from when the device is fully loaded with sheets until the last sheet is discharged, thereby preventing discharge failures.

In order to solve the above technical problem, one aspect of the present invention is a sheet supplying device that supplies sheets stored in a storage space, the device comprising: a conveying means that conveys, in a conveying direction, a top sheet that is at the top of a sheet stack consisting of a plurality of sheets stored in the storage space; an angle adjustment means that adjusts an angle of the sheet with respect to the conveying direction in accordance with a remaining amount of the sheets in the storage space; and a biasing means that biases an end of the top sheet in a stepwise manner toward the conveying means in accordance with the remaining amount of the sheets, the biasing means being an end fence that supports the sheet toward a downstream side in the conveying direction, the end fence biasing the sheet stack in a stepwise manner. and a second biasing means for biasing the end support member toward the downstream side in the conveying direction with a biasing force weaker than that of the first biasing means, wherein when the remaining amount of the sheets is equal to or greater than a predetermined amount, the end of the uppermost sheet is biased toward the conveying means by the first biasing means and the second biasing means, and when the remaining amount of the sheets is less than the predetermined amount, the biasing of the end support member by the first biasing means is stopped, and thereafter, the end of the uppermost sheet is biased toward the conveying means by only the second biasing means .

According to the present invention, even with a small size, the sheet can be kept in contact with the discharge roller from the time the machine is fully loaded with sheets until the last sheet is discharged, preventing discharge failures.

1 is a schematic diagram showing an internal configuration of a printer as an embodiment of an image forming apparatus according to the present invention. 1A is a side cross-sectional view of a sheet feeding device according to a first embodiment of the sheet feeding device of the present invention, and FIG. 1B is a view illustrating a state where the sheet feeding device is almost empty; 1A is a perspective view illustrating a structure of a first embodiment of an end fence provided in the sheet feeding device and a state when the sheet is nearly empty, and FIG. 1B is a cross-sectional view taken along line AA. 1A is a perspective view illustrating the state of the end fence when the sheet stack is fully loaded, and FIG. 1B is a cross-sectional view taken along line AA. 1A is a perspective view illustrating the state of the end fence when a sheet is placed in the middle, and FIG. 1B is a cross-sectional view taken along line A-A. 13A is a perspective view illustrating a structure of a second embodiment of an end fence provided in the sheet feeding device and a state when the sheet is nearly empty, and FIG. 13B is a cross-sectional view along line B-B. 13A is a perspective view illustrating a structure of the end fence according to a second embodiment and a state in which the fence is fully loaded with sheets; FIG.

[Overview of the embodiment of the present invention]
One embodiment of the sheet feeder according to the present invention prevents a carry-out failure caused by a change in the relative positional relationship with a carry-out mechanism that carries out the sheets when the thickness of the stacked sheet bundle is reduced by sequentially carrying out the top sheet of the stacked sheet bundle. More specifically, the sheet feeder is provided with a configuration for displacing the sheet bundle so as to approach the carry-out mechanism in accordance with the decreasing tendency of the thickness of the sheet bundle, with respect to the carry-out mechanism that carries out the sheets by contacting the top sheet of the sheet bundle. In other words, the sheet feeder is provided with a configuration for supporting the sheet bundle so as to maintain the relative position between the top sheet and the carry-out mechanism at a predetermined position by preventing the top sheet from being displaced away from the carry-out mechanism as the remaining amount of sheets decreases.

For example, in the case of a sheet feeder that raises one end of the bottom of the storage space to bring the end where the top sheet contacts the discharge mechanism closer as the remaining amount of the sheet stack decreases, the end of the bottom is raised more as the number of sheets in the stack decreases. This increases the inclination of the bottom and the inclination of the sheet stack, so that the force moving the sheet stack away from the discharge mechanism increases. Therefore, in the embodiment described below, a configuration is provided that biases the entire sheet stack toward the discharge mechanism against the force acting on the sheet stack due to the inclination of the bottom, which tends to move it away from the discharge mechanism.

In addition, the inclination of the bottom increases as the number of remaining sheets decreases, and in order to maintain the relative position between the top sheet and the discharge mechanism, it is necessary to increase the amount by which the entire sheet stack is pushed in the discharge direction. Therefore, in the embodiment described below, a structure is provided that can change the amount by which the entire sheet stack is pushed out depending on the number of remaining sheets.

When the storage space is full of the sheet stack, this structure is configured so that the first biasing means and support plate and the second biasing means and support plate have an integrated thickness, and this configuration allows the entire sheet stack to be biased in the discharge direction. When the top sheet of the sheet stack is discharged one after another and the sheet stack decreases, the top sheet is prevented from moving away from the discharge mechanism. Even when the stack approaches empty from the middle stack, the leading edge of the top sheet is maintained in a contact position with the discharge mechanism. This supports the rear end of the sheet stack and maintains the leading edge of the top sheet in a specified position, preventing discharge abnormalities that are likely to occur due to non-contact between the discharge mechanism for discharging the sheets P and the leading edge of the sheets P during the period from middle stack to empty.

[Embodiment of Image Forming Apparatus]
Hereinafter, an embodiment 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 a conveying roller (paper feed roller) 101 as a conveying means for feeding and conveying a sheet P, a relay roller 102, a registration roller 103, a photoconductor 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 discharge tray 111, a manual feed tray 112, and a manual feed roller 113.

A sheet feeding device 200, which is an embodiment of a sheet feeding device according to the present invention, is mounted below the printer 100. The sheet feeding device 200, which serves as a sheet supply section, is installed below the printer 100, as described below. Note that the printer 100 corresponds to the "other device" relative to the sheet feeding device 200. Thus, the sheet feeding device 200 is a device that supplies sheets P, which are sheet-shaped recording media, to the printer 100, which is the other device, and a new sheet feeding device 200 can also be added below the sheet feeding device 200.

The sheet feeding device 200 includes a sheet storage space 210 in a paper feed tray for storing and feeding sheets P. A stack of sheets P (sheet stack Pb) is stored in the sheet storage space 210. The topmost sheet Pt of the sheet stack Pb stored in the sheet storage space 210 is biased so that its leading edge comes into contact with a discharge roller 101 as a discharge means provided in the printer 100. When the discharge roller 101 rotates, the topmost sheet Pt is pulled out in the Y direction by friction with the discharge roller 101 and passes between the discharge roller 101 and the separation roller 201, and is discharged as a single sheet P toward the relay roller 102 of the printer 100 downstream in the sheet conveying direction.

The sheet P sent out from the sheet feeder 200 is conveyed by the relay roller 102 to the conveying path indicated by the dotted arrow. The sheet P conveyed out from the sheet storage space 210 is stopped by the registration roller 103, and conveying is resumed at a predetermined timing according to the timing of the transfer of the toner image. The conveying roller 101, the relay roller 102, the registration roller 103, the fixed discharge roller 109, and the discharge roller 110 constitute a conveying section that conveys the sheet P to the image forming section formed by the photoconductor 104 and the like, and discharges the sheet P with the image transferred thereto outside the device. The printer 100 also includes a manual feed tray 112 and a manual feed roller 113 that supplies the sheet P from the manual feed tray 112 as a sheet supplying means separate from the sheet feeder 200.

The printer 100 is equipped with a charging device 105 around the photoconductor 104, which charges the surface of the photoconductor 104, and an LED 106 as a light source that exposes the charged surface of the photoconductor 104 to image information to form an electrostatic latent image on the photoconductor 104. The image to be transferred to the sheet P is formed by the operation of these image forming units.

At a predetermined timing, the registration roller 103 starts transporting the toner image formed on the photoreceptor 104, and the sheet P is transported between the photoreceptor 104 and the transfer roller 107, so that the toner image on the photoreceptor 104 is transferred to the sheet P.

The sheet P is then transported to a fixing roller 108 that fixes the transferred toner image, and is then passed through a fixed discharge roller 109 and a discharge roller 110 before being discharged onto a discharge tray provided on the top surface of the printer 100 housing.

The paper feed tray of the sheet feeder 200 is a front-loading type sheet storage means that has a structure that slides in the front direction, which is the X direction in FIG. 1, relative to the main body of the printer 100. It may also be a pull-out tray that slides in the Y direction. The discharge roller 101 may be located in either the main body of the printer 100 or the sheet feeder 200, and may be pulled out together with the paper feed tray.

In the sheet feeding device 200, the bottom plate 230 constituting the sheet storage space 210 corresponds to the placement surface of the sheet stack Pb. A spring 240 is disposed at the end (downstream end) of the bottom plate 230 in the discharge direction as a bottom plate moving member that urges the end of the bottom plate 230 upward to move it. The opposite end (upstream end) of the bottom plate 230 in the discharge direction is supported by the sheet feeding device 200 downstream of the end fence 220 on the upstream side of the center of the sheet in the conveying direction. The end on the discharge direction side is supported by the spring 240. With these configurations, the bottom plate 230 rotates and moves with the opposite end as a base point. Therefore, depending on the amount of the sheet stack Pb placed on the bottom plate 230, the end on the discharge direction side moves up and down due to the action of the elastic force of the spring 240 as an elastic member.

When the sheet storage space 210 is fully loaded with sheets P, the load of the sheet stack Pb causes the bottom plate 230 to be approximately parallel to the loading surface of the sheet feeder 200. At this time, the end of the bottom plate 230 in the conveying direction continues to be biased upward by the bias of the spring 240, so that the leading edge of the top sheet Pt in the conveying direction is pressed tangentially against the discharge roller 101.

Therefore, the sheet stack Pb placed in the sheet storage space 210 is sent downstream in the transport direction by the discharge roller 101, and when the sheets P are supplied to the printer 100, the individual sheets P are sent out one by one to the transport path by the separation roller 201.

[Embodiment of Sheet Feeding Apparatus]
Next, a sheet feeding device 200 which is an embodiment of a 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 seen from the side. As shown in Fig. 2, the sheet feeding device 200 is provided with an end fence 220 as a support member for supporting the rear end of the sheet stack at an end of the sheet storage space 210, which is the opposite end in the conveying direction of the sheets P. The end fence 220 has a structure that allows it to be selectively fixed to a predetermined position in the sheet storage space 210.

The end fence 220 has a vertically long portion 2271 that rotatably holds the vertically long support plates (221, 222) that support the rear end of the sheet stack Pb, and a bottom portion 2261 that supports the vertically long portion 2271. The bottom portion 2261 extends to the discharge side and has a structure that allows it to 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 dimension of the end fence 220 regulates the height dimension of the support plates (221, 222).

The bottom plate 230, which is a sheet support member that forms the bottom of the sheet storage space 210, is an angle adjustment means that changes the angle of the bottom plate 230 depending on the remaining amount of sheet stack Pb. This angle adjustment means also includes a spring 240 that suspends one end of the bottom plate 230 that maintains the contact state of the topmost sheet Pt with the discharge roller 101. When the bottom plate 230 is rotated by the spring 240 depending on the remaining amount of sheet stack Pb, the position of the tip of each topmost sheet Pt relative to the discharge roller 101 shifts upstream, and the angle relative to the discharge roller 101 changes from the tangential direction. This shift is adjusted by the end fence 220, the details of which will be explained later.

2A illustrates a state in which the sheet stack Pb is fully loaded relative to the storage capacity of the sheet storage space 210. On the other hand, FIG. 2B illustrates a state in which the sheet stack Pb is nearly empty after the sheets P are discharged. Various methods are known for sheet supplying by the sheet feeder 200. In this embodiment, a separation roller 201 method is illustrated, but a separation pad method may also be used. In this embodiment, the biasing force for contacting the top sheet Pt with the discharge roller 101 is realized by a structure that allows one end of the bottom plate 230 to move in the vertical direction. The structure for biasing the top sheet Pt of the sheet stack Pb stored in the sheet storage space 210 in a direction in which it continues to contact the discharge roller 101 is not limited to the structure illustrated in this embodiment. A structure that biases the end of the bottom plate 230 so as to push it upward from below may also be used, or may be performed by a rotary shaft drive.

As shown in FIG. 2A, when the stack of sheets P is fully loaded or nearly fully loaded, the spring 240 is stretched by the load of the stack of sheets Pb, and the tip of the bottom plate 230 descends and becomes nearly parallel to the ground surface of the paper feed tray. Even at this time, the tip of the bottom plate 230 continues to be biased upward by the spring 240, so that the topmost sheet Pt is pressed against the discharge roller 101 at the contact position.

The bottom plate 230 is also slightly tilted in the state shown in FIG. 2(a). This tilt also applies a load to the rear end of the sheet stack Pb, so the end fence 220 supports the sheet stack Pb to maintain it in a specified position. At this time, the first support plate 221 and the second support plate 222, which serve as support members equipped with a biasing means, are pressed toward the rear end by the rear end pressure force Mp due to the load of the sheet stack Pb, which is the force applied to the end fence 220 by the sheet stack Pb. These support members bias the rear end of the sheet stack Pb in the discharge direction, preventing the downstream leading edge of the uppermost sheet Pt from shifting toward the rear end.

When the individual sheets P are discharged and the remaining amount of the sheet stack Pb decreases to a state where it is nearly empty, the load on the bottom plate 230 decreases. In this case, as shown in FIG. 2(b), the elastic force of the spring 240, which serves as an angle adjustment means, raises the tip of the bottom plate 230, and the top sheet Pt is kept pressed against the discharge roller 101.

2B, the inclination of the bottom plate 230 is steep and large. Therefore, the force of the sheet stack Pb moving toward the rear end of the bottom plate 230 increases. However, the rear end pressing force Mp weakens as the number of sheets P decreases. Therefore, the urging force Ms is relatively greater, and the first support plate 221 as the first support member moves toward the conveying direction side by the urging force of the first elastic body 223 as the first urging means provided in the end fence 220, and supports the position of the rear end of the sheet stack Pb. In addition, as described later, the second support plate 222 as the second support member of the end fence 220 is also urged toward the conveying direction side. This second support plate 222 moves toward the conveying direction side by the urging force of the second elastic body 224 as the second urging means, and supports the position of the rear end of the sheet stack Pb. As a result, the leading edge of the top sheet Pt can be maintained in a state where it reaches the contact position of the conveying roller 101.

[First embodiment]
Next, the end fence 220 according to the first embodiment will be described in detail with reference to Fig. 3 to Fig. 5. As already described, the end fence 220, which is a rear end regulating member that regulates the rear end of a sheet on the upstream side in the sheet conveying direction, supports the rear end portion of the sheet stack Pb (sheets P) placed in the sheet storage space 210 provided in the sheet feeder 200. This allows the uppermost sheet Pt to maintain a position in contact with the discharge roller 101 regardless of the amount of the sheet stack Pb (sheets P).

Figure 3 illustrates the state of the end fence 220 when the remaining amount of sheet stack Pb stored in the sheet storage space 210 is low and close to empty. Figure 4 illustrates the state of the end fence 220 when the sheet stack Pb is full. Figure 5 illustrates the state of the end fence 220 when the remaining amount of sheet stack Pb is low and close to halfway between full and empty.

The end fence 220 has a structure that fits with the sheet feeding device 200, is disposed at the rear end side of the sheet storage space 210, and has a structure that allows the position relative to the bottom plate 230 to be changed according to the size of the sheets P. When the end fence 220 fits with the sheet feeding device 200, it is in a state of supporting the rear end side of the sheet stack Pb. As a result, when the sheet P continues to be conveyed out and the remaining amount of the sheet stack Pb decreases, the inclination of the bottom plate 230 becomes steeper and larger, and it is possible to prevent the leading end of the sheet stack Pb from shifting in the opposite direction to the conveying direction.

The structure of the end fence 220 according to the first embodiment will be described with reference to FIG. 3. The end fence 220 includes a first support plate 221 as a first support member constituting an end support member, and a second support plate 222 as a second support member constituting the end support member. The first support plate 221 has one end 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 rotates around the one end side as the center of rotation. The second support plate 222 has one end fixed near the middle below the gap between the one end and the other end of the first support plate 221, and is supported by the first support plate 221 so that the other end rotates around the one end side as the axis of rotation.

The first support plate 221 is a rectangular plate with a short dimension approximately equal to the height dimension of the end fence 220, and has a groove 2213 formed slightly below the center in the vertical direction of its length. The first support plate 221 has a thin plate portion 2212 with different thicknesses above and below the groove 2213, and a side end portion 2211 that is the same thickness as the upper side and is located in the width direction of the thin plate portion 2212.

The second support plate 222 has one end rotatably engaged with the groove portion 2213 of the first support plate 221. The second support plate 222 is a plate member that is thinner than the first support plate 221. The thickness of the second support plate 222 is equal to that of the first support plate 221 when combined with the thickness of the thin plate portion 2212 of the first support plate 221.

Therefore, when the sheet stack Pb is fully loaded, and the bottom plate 230 is substantially flat and the rear end of the sheet stack Pb is close to the end fence body 227, the second support plate 222 fits into a position where it is sandwiched between the side end portion 2211 of the first support plate 221. This allows the sheet storage space 210 to be fully loaded with the sheet stack Pb.

3B is a cross-sectional view of line A-A in FIG. 3A. As shown in FIG. 3B, a first elastic body 223 is disposed on the lower end side of the first support plate 221 as a first biasing means. 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. The first support plate 221 is biased in the Y direction by the elastic force of the first elastic body 223. That is, the first support plate 221 biases the sheet stack Pb toward the carry-out roller 101 side and supports the top sheet Pt so that it reaches a position where it contacts the carry-out roller 101. The first elastic body 223 is, for example, a spring. Note that, although the first elastic body 223 is described as an example of a spring in this embodiment, it can be applied to any elastic member other than a spring as long as it can bias the first support plate 221 as the first support member in a predetermined direction.

In addition, a second elastic body 224 is disposed at the lower end of the second support plate 222 as a second biasing means. 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. The second support plate 222 is biased in the Y direction by the elastic force of the second elastic body 224. That is, the second support plate 222 presses and supports the sheet stack Pb toward the carry-out roller 101 side, moves the rear end of the sheet stack Pb with a small remaining amount in the carry-out direction to support it, and maintains the position of the tip portion of the top sheet Pt at a contact position with the carry-out roller 101. The second elastic body 224 is, for example, a spring. Note that, although the second elastic body 224 is described as an example of a spring in this embodiment, it can be applied to any elastic member other than a spring as long as it can bias the second support plate 222 as a second support member in a predetermined direction.

The end fence body 227 also includes a rail portion 229 that allows the relative position in the discharge direction to be moved with respect to the bottom plate 230. The rail portion 229 slidably fits into a rail groove formed in the sheet feeder 200. The rail groove is formed along the discharge 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 in accordance with the size of the sheet P, and support the rear end of the sheet P in the conveying direction at the moved position.

In addition, a first stopper 225 and a second stopper 226 are arranged at the bottom of the end fence body 227 as a restricting means for restricting the operating range of the biasing means. The first stopper 225 is a first stopping member that restricts the movement 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.

The first stopper 225 is disposed at a position where it contacts the side end 2211 of the first support plate 221 that has been rotated to a predetermined position by the force of the first elastic body 223. When the side end 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 that it contacts above the lower end of the side end 2211.

The first stopper 225 restricts the first support plate 221, which is biased by the first elastic body 223, from moving too far in the Y direction. If the first stopper 225 is not provided, when the remaining amount of the sheet stack Pb is exhausted, the first support plate 221 can move indefinitely in the Y direction by the amount of extension of the first elastic body 223. In that case, when the sheet stack Pb is to be refilled in the sheet storage space 210, a gap is formed between the first support plate 221 and the bottom plate 230 into which a part of the sheet stack Pb enters. As a result, the first support plate 221 cannot bias the sheet stack Pb appropriately. Therefore, the first stopper 225 is arranged so that the tip of the first stopper 225 is located 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.

In addition, the end fence body 227 is provided with a second stopper 226 as a second stopping member for restricting the movement range of the second support plate 222 in the Y direction at the bottom between the two first stoppers 225 in the width direction of the sheet. The second stopper 226 is an inclined member that rises from the bottom of the end fence body 227 and has an inclined portion. The second stopper 226 is formed such that the portion of the second stopper 226 that engages with the second support plate 222 is located on the conveying direction side of the sheet P, relative to the portion of the first stopper 225 that engages with the first support plate 221, so that the second stopper 226 restricts the second support plate 222 that moves in the Y direction due to the elastic force of the second elastic body 224 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 second stopper 226 has a predetermined height dimension so as to contact above the lower end of the second support plate 222.

The second stopper 226, like the first stopper 225, has an inclined shape that rises from the bottom of the end fence body 227 and has an inclined portion. The rear end of the sheet stack Pb rests on this inclined portion, preventing the sheet P located at the bottom of the sheet stack Pb from entering the gap between the bottom end of the first support plate 221 or the second support plate 222 and the bottom plate 230.

Next, the operation of the end fence 220 will be described. As shown in FIG. 4, when the sheet storage space 210 is fully loaded with the sheet stack Pb, the inclination of the bottom plate 230 is at its gentlest (see FIG. 2(a)). In this state, the tip side of the bottom plate 230 is urged upward by the spring 240, so that the top sheet Pt is kept pressed against the discharge roller 101. At this time, the end fence 220 supporting the rear end of the sheet stack Pb is heavily loaded with the load of the sheet stack Pb, so that the rear end pressing force Mp is greater than the urging force (Ms2) of the second elastic body 224 urging 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 is integrated in appearance.

When the sheet storage space 210 is fully loaded with the sheet stack Pb, the rear end pressure contact force Mp is greater than the biasing force (Ms1) of the first elastic body 223 that biases the fully loaded first support plate 221. Therefore, the lower end of the first support plate 221 remains in the position closest to the rear side of the end fence body 227.

Even if the stack of sheets Pb is fully loaded, the first support plate 221 always urges the stack of sheets Pb toward the discharge rollers 101 due to the elastic force (Ms1) of the first elastic body 223. Similarly, the second support plate 222 always urges the stack of sheets Pb toward the discharge rollers 101 due to the elastic force (Ms2) of the second elastic body 224.

As the remaining amount of the sheet stack Pb decreases from the state illustrated in FIG. 4, the rear end pressing force Mp weakens. As a result, the first support plate 221 moves in the Y direction due to the elastic force (Ms1) of the first elastic body 223 that exerts a first biasing force that is greater than the elastic force (Ms2) of the second elastic body 224 that exerts the second biasing force, and reaches the state shown in FIG. 5.

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 sheet stack Pb is slightly less than half the full amount (medium stack). At this time, the inclination of the bottom plate 230 is also moderate.

5, when the sheet P is further conveyed out and the sheet stack Pb decreases, the rear end pressure force Mp weakens, but the inclination of the bottom plate 230 becomes steeper, so the force with which the sheet stack Pb slides down toward the end fence 220 increases. When this state is reached, the second support plate 222 can move in the Y direction due to 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, the second biasing force resists the rear end pressure force Mp, preventing the sheet stack Pb from sliding toward the rear end. This allows the leading edge portion of the uppermost sheet Pt downstream in the conveying direction to be maintained in an appropriate contact position with the conveying roller 101. That is, although the inclination of the bottom plate 230 is large, the position where the leading edge of the uppermost sheet Pt on the downstream side of the transport direction contacts the discharge roller 101 shifts downstream in the transport direction, and contacts the discharge roller 101 in the tangential direction, just as when the sheet is fully loaded.

As described above, the end fence 220 according to the first embodiment includes a first support plate 221 and a second support plate 222, and is configured to gradually switch the force urging the sheet bundle Pb in the discharge direction from two elastic bodies to one elastic body depending on 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 urged mainly by the first urging force, and the rear end is restricted 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 urged by the second urging force, and the rear end is restricted at a predetermined position.

In other words, even if the height dimension of the first support plate 221 is shortened and the end fence 220 is made smaller without increasing the amount of movement of the first support plate 221 that exerts the first biasing force, the rear end of the sheet stack Pb can be regulated by using the second support plate 222 in combination.

Therefore, with 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 uppermost sheet Pt can be kept in pressure contact with the discharge roller 101.

In other words, even if the sheet feeding device 200 is thin (compact), the top sheet Pt maintains proper contact with the discharge roller 101 from the time the device is fully loaded with sheets until the last sheet is discharged, so that a sheet feeding device 200 can be obtained that can prevent discharge failures even though it is compact.

[Second embodiment]
Next, the end fence 220a according to the second embodiment will be described in detail with reference to Fig. 6 and Fig. 7. Fig. 6 illustrates an example of the state of the end fence 220a when the remaining amount of the sheet stack Pb stored in the sheet storage space 210 is low. Fig. 7 illustrates an example of the state of the end fence 220a when the sheet stack Pb is fully loaded.

In the following explanation, detailed explanations of configurations and functions common to the first embodiment will be omitted, and the configuration that exhibits the characteristics of the second embodiment will be described.

The end fence 220a is disposed at the rear end side of the sheet storage space 210, and can be changed in position relative to the bottom plate 230 according to the size of the sheets P, and can be fixed relative to the bottom plate 230. The end fence 220a fixed to the bottom plate 230 has a structure that constantly biases the sheet stack Pb in the discharge direction while supporting the rear end side of the sheet stack Pb stored in the sheet storage space 210. As a result, when the sheet stack Pb continues to be discharged and the remaining amount of the sheet stack Pb decreases, the inclination of the bottom plate 230 becomes steeper and larger, and the leading end of the sheet stack Pb can be prevented from shifting in the opposite direction to the conveying direction.

The structure of the end fence 220a according to the second embodiment will be described with reference to Figure 6. The end fence 220a has 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, and is supported by the end fence body 227 so that one end is fixed to the upper end portion of the end fence body 227 and the other end rotates around the one end as an axis of rotation.

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

The upper end 2221a is a structure for preventing the rear end portion of the sheet stack Pb from getting caught on the second support plate 222a when the sheet stack Pb is placed in the sheet storage space 210 from getting caught on the second support plate 222a. If the structure did not have the upper end 2221a, the rear end portion of the sheet stack Pb would get caught on the upper end of the second support plate 222a. As a result, there is a possibility that the second support plate 222a may peel off from the first support plate 221, damage the sheets P, or other problems may occur. Therefore, by providing the upper end 2221a, damage to the end fence 220a and damage to the sheets P can be prevented when the sheet stack Pb is refilled into the sheet storage space 210.

The side end portion 2221b is a structure for protecting the sheet P from getting caught on the second support plate 222a when the sheet P is transported out or when the sheet stack Pb is placed in the sheet storage space 210. If the side end portion 2221b is not provided, the side end portion of the second support plate 222a would be left cut. In that case, when the sheet P is transported out or the sheet stack Pb is replenished, the sheet P may get caught on the side end portion, causing the rear end of the sheet P to be raised.
If the rear end portion of the sheet P is raised, even if the end fence 220a urges the sheet stack Pb toward the discharge roller 101, there is a possibility that the leading edge of the top sheet Pt will not reach the specified contact position, which may result in a discharge abnormality.

The widthwise position of the sheet stack Pb may be adjusted using a side fence or the like to regulate the widthwise position of the sheet stack Pb in the sheet storage space 210. In this case, when adjusting the widthwise position of the sheet stack Pb by shifting it, there is a possibility that the rear end portion of the sheet stack Pb may come into contact with the side end portion of the second support plate 222a.

In addition, without the side end 2221b, the second support plate 222a would not be able to receive the sheet stack Pb. As a result, there is a possibility that the second support plate 222a may peel off from the first support plate 221, damage the sheets P, or other problems may occur.

The lower end portion of the side end 2221b is inclined toward the first support plate 221. This inclined shape prevents the sheet stack Pb with a reduced remaining amount from getting caught on the side end 2221b. Also, when refilling the sheet stack Pb, if only a small amount is refilled rather than fully refilled, it is possible to prevent the bottom sheet P of the sheet stack Pb from being pinched between the bottom end portion of the side end 2221b and the first stopper 225. If the bottom sheet P of the sheet stack Pb is pinched between the bottom end portion of the side end 2221b and the first stopper 225, a pulling force, although small, is required to pull out the sheet P. If the carrying force of the carry-out roller 101 is weak against the pulling force, a carrying-out abnormality will occur.

Therefore, by providing the side end portion 2221b, damage to the end fence 220a and damage to the sheets P can be prevented when refilling the sheet stack Pb into the sheet storage space 210. In addition, it is possible to prevent the sheets P from being pinched between the second support plate 222a and the first stopper 225, which would cause abnormal transport.

At the lower end of the first support plate 221, a first elastic body 223 is disposed as a first biasing means, 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. In other words, the first support plate 221 is biased in a direction to press and support the sheet stack Pb toward the position of the discharge roller 101. The rear end of the sheet stack Pb comes into contact with the first support plate 221, thereby maintaining the state in which the topmost sheet Pt reaches the contact position with the discharge roller 101.

A second elastic body 224a serving as a second biasing means is disposed between the first support plate 221 and the rear side of the second support plate 222. This second elastic body 224a is made of rubber, sponge, or any other material that exerts elasticity, and is a plate-like member with a predetermined thickness.

The second elastic body 224a exerts a second biasing force, biasing the second support plate 222 in the Y direction. The second elastic body 224a biases the second support plate 222a uniformly in the Y direction as a whole. When the rear end of the sheet stack Pb with a small remaining amount is in contact with the second support plate 222a, the second elastic body 224a applies a second biasing force to the sheet stack Pb so as to press the top sheet Pt against the contact position with the discharge roller 101.

When the sheet stack Pb is fully loaded, as illustrated in FIG. 7, the second elastic body 224a of the end fence 220a is crushed and thinned. At this time, the second support plate 222a is closest to the first support plate 221. As the sheets P are conveyed out from the state shown in FIG. 7 and the remaining amount of the sheet stack Pb decreases, the rear end pressure contact force Mp decreases, and the lower end of the first support plate 221 rotates in the Y direction due to the first biasing force (Ms1). Then, when the remaining amount of the sheet stack Pb decreases further 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 due to the second biasing force (Ms2).

As described above, the end fence 220a according to the second embodiment includes a first support plate 221 and a second support plate 222a, and is configured to gradually switch the force that urges the sheet stack Pb in the discharge direction depending on the remaining amount of the sheet stack Pb in the sheet storage space 210. In other words, the end fence 220a can gradually switch between holding the topmost sheet Pt in the contact position by the first support plate 221 and holding the topmost sheet Pt in the contact position by the second support plate 222a depending on the degree of reduction in the remaining amount of the sheet stack Pb.

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

In other words, the height dimension of the first support plate 221 that exerts the first biasing force can be shortened and the end fence 220a can be made smaller without increasing the amount of movement of the first support plate 221, and the position of the rear end of the sheet stack Pb can be restricted to a predetermined position by using the second support plate 222a in combination.

The present invention can be used not only in sheet supply devices for paper feed trays, but also in sheet supply devices for manual feed trays and sheet supply devices for document feed trays in copiers and the like. The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist of the invention. All technical matters included in the technical ideas described in the claims are covered by the present invention. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims.

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

JP 2004-142892 A

Claims (11)

A sheet supplying device that supplies sheets stored in a storage space,
a conveying means for conveying, in a conveying direction, a top sheet of a sheet stack made up of a plurality of sheets accommodated in the accommodation space;
an angle adjusting unit that adjusts an angle of the sheet with respect to the conveying direction in accordance with a remaining amount of the sheet in the storage space;
a biasing means for biasing an end portion of the uppermost sheet toward the discharge means in a stepwise manner in accordance with the remaining amount of the sheets;
Equipped with
the biasing means is an end fence that supports the sheet toward a downstream side in a conveying direction,
The end fence is:
an end support member for supporting an end of the sheet stack;
a first biasing means for biasing the end support member toward the downstream side in the conveying direction;
a second biasing means for biasing the end support member toward the downstream side in the transport direction with a biasing force weaker than that of the first biasing means;
Equipped with
when the remaining amount of the sheets is equal to or greater than a predetermined amount, the first biasing means and the second biasing means bias an end of the uppermost sheet toward the conveying means;
when the remaining amount of the sheets is less than a predetermined amount, the first biasing means stops biasing the end support member, and thereafter, the end of the top sheet is biased toward the discharge means only by the second biasing means .
A sheet supplying device comprising: the conveying means being a conveying roller for conveying the topmost sheet from the storage space to a downstream side in the conveying direction;
2. The sheet supplying device according to claim 1, further comprising: an angle adjusting means for varying an inclination of the uppermost sheet. The angle adjustment means is
A bottom plate that constitutes a bottom of the storage space;
A bottom plate moving member that moves the bottom plate in a vertical direction,
3. The sheet supplying device according to claim 1, wherein the bottom plate moving member is an elastic member that moves one end of the bottom plate. When the storage space is fully loaded with the sheets, the end support member biases the sheet stack by the first biasing means and the second biasing means,
4. The sheet supplying device according to claim 1, wherein when an amount of the sheets accommodated in the accommodation space decreases, the second urging means urges the sheet stack. The end support member is divided into a first support member and a second support member,
The first support member biases the sheet stack by the first biasing means,
The sheet feeding device according to claim 1 , wherein the second supporting member biases the sheet stack by the second biasing means. the first support member has an upper end held by the end fence body, the first biasing means disposed at a lower end, and the lower end is rotatable around the upper end as a rotation center;
The sheet supplying device according to claim 5 , wherein 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 around the one end as a rotation center. the first support member has an upper end held by the end fence body, the first biasing means disposed at a lower end, and the lower end is rotatable around the upper end as a rotation center;
The second support member includes the second biasing means disposed thereon,
The sheet feeding apparatus according to claim 5 or 6, wherein the second biasing means is disposed on the first support member. a first stop member that restricts the movement of the first support member toward the discharge means at a predetermined position;
a second stop member that restricts the movement of the second support member toward the discharge means at a predetermined position,
The sheet feeding device according to claim 5 , wherein the second stopping member is disposed closer to the discharge means than the first stopping member. The position where the first stop member contacts the first support member is higher than a lower end of the first support member,
The sheet feeding device according to claim 8 , wherein a position where the second stop member contacts the second support member is above a lower end of the second support member. The sheet supplying device according to any one of claims 1 to 9, wherein the first biasing means and the second biasing means are elastic members. an image forming unit that forms an image on a sheet;
a conveying section that conveys the sheet discharged from the accommodation space to the image forming section;
a sheet supply unit that supplies the sheet to the conveying unit,
11. An image forming apparatus, wherein the sheet supplying section is the sheet supplying device according to claim 1.