JPH1129225A - Sheet feeding device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sheet separation function from being degraded because of change in approaching angle for a sheet supported by a sheet loading means and an auxiliary sheet loading means, with respect to a sheet feeding means depending on the magnitude of sheet stiffness in a sheet feeding device. SOLUTION: In a sheet feeding device with a sheet loading means 1 loading a plurality of sheets, a sheet feeding means 4 feeding each sheet out of the aforesaid sheet loading means 1 in order, and with an auxiliary sheet feeding means 2 located at the upstream side of the sheet loading means 1, at the sheet feeding means 4 and the sheet loading part of the sheet loading means 1, since the sheet loading surface of the auxiliary sheet feeding means 2 is isolated from the extension line of a straight line connected with the uppermost stream part in the sheet feeding direction, a sheet high in stiffness is fed over to a line roughly identical to the aforesaid straight line, the rear end part of the sheet is not loaded over to the auxiliary sheet loading means 2, but the rear end part of a sheet low in stiffness is loaded over to the sheet loading means 1, so that the approaching angles of both the sheets can thereby be maintained identical.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for feeding a sheet in a facsimile, a copying machine, a printer, and the like, and an image forming apparatus having the sheet feeding apparatus.

[0002]

2. Description of the Related Art Recently, there has been a demand for an image forming apparatus which can be shared by a plurality of computers and can print on various types of sheet materials at high speed. An example of a printer that meets this need is an electrophotographic laser printer.

A laser printer as an example of an image forming apparatus will be briefly described with reference to FIG. 9 showing one embodiment of the present invention. It should be noted that FIG. 1 schematically shows only the main parts.

[0004] The surface of an electrophotographic photosensitive member (hereinafter referred to as a "photosensitive drum") 18 rotatably supported in the direction of arrow R18 is uniformly charged by a charger 19. The surface of the photosensitive drum 18 is irradiated with laser light emitted from a laser scanner 20 according to an image signal,
The charge of the irradiated portion is removed, and an electrostatic latent image is formed on the photosensitive drum 18. The electrostatic latent image is developed as a toner image by attaching toner to the developing unit 21.

[0005] The toner image is stacked on a stacking tray to be described later, and is transferred by the transfer charger 23 to the surface of the sheet P fed by the feed roller 4. The sheet P to which the toner image has been transferred is discharged outside the printer main body after the surface of the sheet P is heated and fixed by a fixing device (not shown). On the other hand, the photosensitive drum 18 after the transfer of the toner image
The transfer residual toner remaining on the surface is removed by a cleaner (not shown), and is used for the next image formation. In this example, an image forming unit is mainly configured by the photosensitive drum, the developing device, the transfer device, and the fixing device.

[0006] A laser printer is often installed at a location remote from a host computer connected by a network. For this reason, a highly reliable sheet feeding apparatus that is less likely to cause paper jams and double feeds is required.

As a sheet feeding apparatus satisfying such a demand, there is a sheet feeding apparatus using a separation pad system.
Hereinafter, an outline of the sheet feeding apparatus of the separation pad type will be described with reference to FIG.

At the time of paper feeding, the middle plate 5 presses the sheet P against the paper feeding roller 4. In this state, the sheet P is picked up by rotating the sheet feeding roller 4 attached to the sheet feeding shaft 3. In this case, a plurality of sheets may be picked up. The separation pad 9 separates only one of them. Then, the separated one sheet is fed thereafter and supplied to the image forming apparatus main body. In such a separation-pad-type sheet feeding apparatus, the size of the angle between the sheet P and the separation pad 9 causes a paper jam and greatly affects the paper feeding performance of double feeding.

[0009]

In a conventional sheet feeding apparatus of the separation pad type, an auxiliary stacking tray which is an auxiliary sheet stacking means for supporting an upstream side in a sheet conveying direction and a downstream side in a sheet conveying direction are supported. The angle between the sheet stacking side and the stacking tray, which is a sheet stacking unit, is 1 on the sheet stacking side.
80 degrees or less. For this reason, the angle between the sheet and the separation pad at the time of pickup differs depending on the degree of rigidity of the sheet, and a paper jam occurs in a sheet having a high rigidity, and a double feed may occur in a sheet having a low rigidity.

A sub-tray 2, which is an auxiliary stacking tray when the stacked sheets P are fed, a stacking tray 1, a side regulation 13B, a middle plate 5, a feed roller 4, rollers 6A, 6
B, the positional relationship between the separation pads 9 will be described with reference to FIGS. 11 and 12 are side views as seen from the direction of arrow A in FIG. In the drawing, the angle formed by the auxiliary stacking tray 2 and the stacking tray 1 on the sheet stacking side is approximately 180 degrees.

FIG. 11 is a side view showing a state in which a sheet Ph having high rigidity is fed. The middle plate 5 presses the sheet Ph against the paper feed roller 4 by a middle plate spring 14. At this time, the sheet Ph is supported by the sub-tray 2 and is not in contact with the side regulation 13B.

FIG. 12 is a side view showing a state in which a sheet Ps having low rigidity is fed by the sheet feeding apparatus shown in FIG. The middle plate 5 presses the sheet Ps against the paper feed roller 4 by the middle plate spring 14. At this time, since Ps is bent, it is supported by both the uppermost stream portion of the bottom plate of the side regulation 13B in the sheet feeding direction and the sub-tray 2.

Therefore, the angle between the sheet and the separation pad at the time of pickup differs depending on the rigidity of the sheet.

If the angle between the sheet and the pad is large, the sheet is easily separated, but the sheet feeding tends to be poor. Conversely, if the angle is small, the sheet feeding is unlikely to occur, but the double feed tends to occur. Tend to be. Therefore, it is important that the angle does not change due to the rigidity of the sheet.

The present invention provides a sheet feeding apparatus having a stable sheet feeding performance in which an angle formed by a sheet separation pad does not change at the time of pickup depending on the degree of rigidity of a sheet, and the sheet feeding apparatus having the sheet feeding apparatus. It is an object to provide a stable image forming apparatus.

[0016]

In order to achieve the above object, a sheet feeding apparatus according to a first aspect of the present invention comprises a sheet stacking means for stacking a plurality of sheets, and a plurality of sheets on the sheet stacking means. A sheet feeding device that sequentially feeds the sheet from the highest or lowest sheet, and an auxiliary sheet stacking device that is positioned upstream in the sheet feeding direction from the sheet stacking device. The sheet stacking surface of the auxiliary sheet stacking unit is separated from a straight extension line connecting the sheet feeding unit and the sheet stacking unit of the sheet stacking unit and the most upstream portion in the sheet feeding direction. .

According to a second aspect of the present invention, there is provided a sheet stacking means for stacking a plurality of sheets, and a sheet feeding means for sequentially feeding sheets from the highest or lowest one of the plurality of sheets on the sheet stacking means. Sheet movement detecting means for detecting that the last sheet of a plurality of sheets fed from the stacking means by the sheet feeding means has moved, and a sheet feeding direction more than the sheet stacking means. In a sheet feeding apparatus provided with an auxiliary sheet stacking unit located on an upstream side, a sheet of the auxiliary sheet stacking unit is obtained from a straight extension line connecting a portion of the sheet feeding unit and the sheet of the sheet movement detecting unit that comes into contact with a sheet. The loading surface is isolated.

According to a third aspect of the present invention, the sheet movement detecting means blocks the movement of the sheet by blocking the light from the light emitting means to the light receiving means by a disk which is provided with a slit for transmitting light and which is rotated by the sheet. It is characterized by detecting.

According to a fourth aspect of the present invention, the sheet stacking section of the sheet stacking means is a part of the sheet stacking means itself or a part of a side regulation provided in the sheet stacking means.

According to a fifth aspect of the present invention, the sheet stacking surfaces of the sheet stacking means and the auxiliary sheet stacking means intersect at an angle formed by the sheet stacking side greater than 180 degrees.

According to a sixth aspect of the present invention, the sheet feeding means comprises:
It has a feeding roller for feeding a sheet and a separation pad for separating the sheet.

According to a seventh aspect of the present invention, an intermediate plate is provided between the sheet feeding means and the auxiliary sheet stacking means to guide the sheet toward the feeding roller of the sheet feeding means.

According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising: the sheet feeding apparatus according to any one of the first to fifth aspects; and an image forming section for forming an image on a sheet supplied by the sheet feeding apparatus. And a sheet discharging device for discharging a sheet after image formation.

[0024]

Embodiments of the present invention will be described with reference to the drawings.

[First Embodiment] The image forming apparatus of the present invention is mainly characterized by a paper feeder. The basic configuration (for example, an electrophotographic process) of the image forming apparatus is shown in FIG.
As described in the above. Therefore, the description will focus on the paper feeding device.

FIG. 1 is a perspective view showing the first embodiment of the present invention, and shows a state in which a plurality of stacked sheets 1 are sequentially taken out from the top and supplied to the image forming apparatus main body.

As shown in FIG. 1, this sheet feeding device includes a tray 1 as a sheet stacking unit, a sub-tray 2 as an auxiliary sheet stacking unit, a sheet feeding shaft 3, a sheet feeding roller 4, a middle plate 5, rollers 6A and 6B. , A cam 7, a cam follower 8, a separation pad 9, and an electromagnetic clutch 10.
The sub-tray 2 includes a frame 11 and a cover 12 for supporting the above-described components. In the illustrated example, the sub-tray 2 is stored in the cover 12 when the sheet feeding device is not used, and is pulled out of the cover when used.

The tray 1 is for stacking the sheets P, and is attached to the frame 11 and the cover 12. The tray 1 is provided with side restrictions 13A and 13B for restricting the width direction of the sheet P. By appropriately moving these side restrictions according to the size of various sheets, the tray 1 can correspond to various sizes. Has become.

The middle plate 5 presses the sheet P against the paper feed roller 4. The middle plate 5 includes a frame 11
Is mounted so as to be rotatable. Then, it is constantly urged toward the paper feed roller 4 by a middle plate spring 14 (see FIG. 2) disposed on the back side.

The paper feed roller 4 and the separation pad 9 constitute a sheet feeding means. The paper feed roller 4 is for picking up the sheet P, and has a D-cut shape in this example. The paper feed roller 4 is attached to the paper feed shaft 3, and is configured to rotate together with the paper feed shaft 3 by a driving force input via an electromagnetic clutch 10 described later.

The rollers 6A and 6B are rotatably mounted adjacent to both sides of the feed roller 4 of the feed shaft 3.

The cam 7 and the cam follower 8 are for controlling the timing of pressing the middle plate 5 toward the paper feed roller 4. The cam follower 8 is attached to the middle plate 5. On the other hand, the cam 7 is fixed at a position facing the cam follower 8 of the paper feed shaft 3. Cam Follower 8
Is operated in accordance with the cam 7, so that the middle plate 5 is operated (approach / separation to / from the paper feed roller 4).

The separation pad 9 is for separating only the top one of the sheets picked up by the paper feed roller 4. This separation pad 9
It is rotatably attached to the frame 11. Then, the pad spring 15 (see FIG. 2) disposed on the back side constantly urges the sheet supply roller 4. Only one sheet separated by the separation pad 9 is supplied to the image forming apparatus main body. In the illustrated example, the sheet is fed separately from the uppermost sheet, but may be fed from the lowermost sheet.

The electromagnetic clutch 10 is for controlling the timing of sheet feeding. This electromagnetic clutch 10
Transmission of the driving force of the separately provided motor to the paper feed shaft 3 /
Controlling non-transmission.

Next, the positional relationship among the sub-tray 2, the tray 1, the side regulation 13B, the middle plate 5, the feed roller 4, the rollers 6A and 6B, and the separation pad 9 when the stacked sheets P are fed is shown. This will be described with reference to FIG. 2 and 3 are side views as seen from the direction of arrow A in FIG.

FIG. 2 is a side view showing a state of feeding a sheet Ph having high rigidity. The sub-tray 2 and the tray 1 form an angle larger than 180 degrees on the sheet stacking side. The middle plate 5 presses the sheet Ph against the paper feed roller 4 by a middle plate spring 14. At this time, the sheet Ph is supported at the most upstream portion of the side regulation 13B in the sheet feeding direction, and the sub-tray 2 is below the sheet Ph. That is, the sheet feeding means or the sheet advancing portion between the sheet feeding roller and the pad, an extension of a line connecting the most upstream portion of the sheet stacking portion in the sheet feeding direction, and the sheet stacking surface of the sub-tray 1 are isolated. . In this case, the sub tray 1 and the sheet Ph are not in contact with each other, but since the rigidity of the sheet Ph is high, the sheet Ph
Does not hang down to the lower sub-tray side.

FIG. 3 is a side view showing how the sheet feeding apparatus shown in FIG. 2 feeds a sheet Rs having a small rigidity.
The middle plate 5 presses the sheet Ph against the paper feed roller 4 by a middle plate spring 14. At this time, the sheet Ps is supported at the most upstream portion of the side regulation 13B in the sheet feeding direction, and the sub tray 2 is located below the sheet Ps, but supports the most upstream portion of the sheet Ps in the sheet feeding direction. Will not hang down any further. Low rigidity sheet P
s is on a substantially straight line connecting the sheet stacking portion of the side regulation 13B and the feeding means, and is considered to be the same as the approach angle to the separation pad in FIG.

As described above, in the present embodiment, the angle at which the sheet P enters the separation pad at the time of pickup is constant regardless of the magnitude of the rigidity of the sheet. For this reason, paper jams for multiple types of sheet materials and occurrence of double feeding are small. Therefore, by using such a sheet feeding apparatus, it is possible to realize an image forming apparatus which can handle various types of sheet materials and has a stable sheet feeding performance.

When the length of the sheet Ph having a large rigidity is shorter than that of the sub-tray 2, it is apparent that the present invention includes the provision of the projection 2A on the upstream side of the sub-tray 2 in the feeding direction. This form is shown in FIG. In the example shown in FIGS. 2 and 3, the most upstream portion of the tray 1 in the sheet feeding direction and the most upstream portion of the side regulation 13 </ b> B are substantially the same, and the middle portion of the sheet is supported by the side regulation. The present invention can be applied to a known sheet feeding device in which the uppermost stream of the side regulation is located at a position lower than the uppermost stream of the tray 1, and in this case, the sheet is supported by the uppermost stream of the tray 1. Become.

[Second Embodiment] FIG. 5 is a perspective view showing a second embodiment of the present invention, in which a plurality of stacked sheets 1 are sequentially taken out from the top and supplied to the image forming apparatus main body. Is shown.

As shown in FIG. 5, this paper feeder includes a tray 1, a sub-tray 2, a paper feed shaft 3, a paper feed roller 4, a middle plate 5, a roller 6A, a cam 7, a cam follower 8, a separation pad 9, The clutch 10 includes a clutch 10 and a detection roller 16. Further, a frame 11 and a cover 12 for supporting each of the above components are provided.

The tray 1 is for stacking the sheets P, and is attached to the frame 11 and the cover 12. The tray 1 is provided with side restrictions 13A and 13B for regulating the width direction of the sheet P, and can be adapted to various sizes by appropriately moving the sheet P in accordance with the size of the sheet.

The middle plate 5 is for pressing the sheet P against the paper feed roller 4. This middle plate 5 is a frame 11
Is mounted so as to be rotatable. Then, it is constantly urged toward the paper feed roller 4 by a middle plate spring 14 (see FIG. 6) disposed on the back surface side.

The paper feed roller 4 is for picking up the sheet P. The paper feed roller 4 is attached to the paper feed shaft 3 and has an electromagnetic clutch 10 described later.
Is rotated together with the sheet feeding shaft 3 by a driving force input through the sheet feeding shaft 3.

The rollers 6A and 6B are rotatably mounted adjacent to both sides of the feed roller 4 of the feed shaft 3.

The cam 7 and the cam follower 8 are for controlling the timing of pressing the middle plate 5 toward the paper feed roller 4. The cam follower 8 is attached to the middle plate. On the other hand, the cam 7 is a cam follower 8 of the paper feed shaft 3.
Is fixed at a position opposed to. When the cam follower 8 operates in accordance with the cam 7, the intermediate plate 5 is operated (approaching / separating from the paper feed roller 4).

The separation pad 9 is for separating only the top one of the sheets picked up by the paper feed roller 4. This separation pad 9
It is rotatably attached to the frame 11. Then, the pad spring 15 (see FIG. 6) disposed on the back surface constantly urges the sheet supply roller 4 toward the sheet supply roller 4 side. Only one sheet separated by the separation pad 9 is supplied to the image forming apparatus main body.

The electromagnetic clutch 10 controls the timing of sheet feeding. This electromagnetic clutch 10
Transmission of the driving force of the separately provided motor to the paper feed shaft 3 /
Controlling non-transmission.

The detection roller or disk 16 constituting the sheet movement detection means is provided with a slit for transmitting light,
It is freely rotatable. When the lowermost sheet is fed, the detection roller 16 rotates to block light from the light emitting unit to the light receiving unit in the photo interrupter 17 (see FIG. 6) disposed on the back side of the tray 1. . In this way, the end of feeding of the last sheet can be detected.

Next, when the stacked sheets P are fed, the positional relationship among the sub-tray 2, the tray 1, the side regulation 13B, the middle plate 5, the feed roller 4, the rollers 6a and 6B, and the separation pad 9 is shown. 6 and FIG. 6 and 7 are side views as viewed from the direction of arrow A in FIG.

FIG. 6 is a side view showing a state in which a sheet Ph having high rigidity is fed. The middle plate 5 presses the sheet Ph against the paper feed roller 4 by a middle plate spring 14. At this time, the sheet Ph is supported by the uppermost part of the detection roller 16.
The tray 1 and the sub-tray 2 intersect at an angle larger than 180 degrees on the sheet stacking side, and an extension line of a line connecting the sheet feeding means and a portion of the detection roller in contact with the sheet is separated from the stacking surface of the sub-tray. And the sub tray 2 has the sheet Ph
And is not in contact with the sheet Ph, but since the rigidity of the sheet Ph is high, the sheet Ph does not drop downward.

FIG. 7 is a side view showing a state in which a sheet Ps having low rigidity is fed by the sheet feeding apparatus shown in FIG.
The middle plate 5 presses the sheet Ph against the paper feed roller 4 by a middle plate spring 14. At this time, the sheet Ps is
6, the sub-tray 2 is supported by the sheet Ps
However, since the sheet Ps supports the most upstream portion of the sheet Ps in the sheet feeding direction, the sheet Ps does not drop further downward.

As described above, in this embodiment, the angle at which the sheet at the time of pickup enters the feeding means, that is, the separation pad portion, is constant regardless of the magnitude of the rigidity of the sheet. For this reason, paper jams for multiple types of sheet materials and occurrence of double feeding are small. Further, regardless of the magnitude of the rigidity of the sheet, the sheet comes into contact with the detection roller, so that the displacement of the final sheet can be reliably detected. Therefore, immediately after the pickup, it is possible to detect whether the fed sheet is the last sheet or other than the last sheet. Therefore, if such a sheet feeding apparatus is used, it is possible to realize a high-speed image forming apparatus with stable sheet feeding performance for various kinds of sheet materials.

When the length of the rigid sheet Ph is shorter than that of the sub-tray 2, it is apparent that the present invention includes the provision of the projection 2A on the upstream side of the sub-tray 2 in the feeding direction. This is shown in FIG.

[0055]

As described above, according to the present invention,
The sheet stacking means is obtained from a straight line connecting the most upstream portion of the sheet feeding unit and the sheet stacking unit in the sheet feeding direction of the sheet stacking unit or a straight line connecting the sheet feeding unit and the sheet contact portion of the sheet movement detecting unit. By separating the sheet stacking surface, the angle at which the sheet enters the feeding means at the time of pick-up is constant regardless of the rigidity of the sheet. Can be reduced. Also, by providing a means for detecting the displacement of the last sheet, the displacement of the last sheet can be reliably detected, and therefore, whether the sheet being fed immediately after pickup is the last sheet or other than that. Can be detected. Further, by using the above-mentioned sheet feeding apparatus, it is possible to realize a high-speed image forming apparatus with stable sheet feeding performance for various kinds of sheet materials.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a sheet feeding apparatus according to the present invention.

FIG. 2 is a side view of the sheet feeding apparatus shown in FIG. 1 in one operation state.

FIG. 3 is a side view of another operation state of the sheet feeding apparatus shown in FIG. 1;

FIG. 4 is a side view showing a modification of the sheet feeding apparatus shown in FIG.

FIG. 5 is a perspective view showing a second embodiment of the sheet feeding apparatus according to the present invention.

6 is a side view of the sheet feeding device shown in FIG. 5 in one operation state.

FIG. 7 is a side view of another operation state of the sheet feeding apparatus shown in FIG.

FIG. 8 is a side view showing a modification of the sheet feeding apparatus shown in FIG.

FIG. 9 is a schematic diagram showing an embodiment of an image forming apparatus according to the present invention.

FIG. 10 is a perspective view showing an example of a conventional sheet feeding apparatus.

11 is a side view showing one operation state of the sheet feeding apparatus shown in FIG.

FIG. 12 is a side view showing another operation state of the sheet feeding apparatus shown in FIG.

[Explanation of symbols]

 P: Sheet 1: Tray (sheet loading means) 2: Sub-tray (auxiliary sheet loading means) 4: Paper feed roller 9: Separation pad 13A, 13B: Side regulation 16: Detection roller (disk)

Claims (8)

[Claims] 1. A sheet stacking means for stacking a plurality of sheets, a sheet feeding means for sequentially feeding from the highest or lowest sheet of the plurality of sheets on the sheet stacking means, and the sheet In a sheet feeding apparatus provided with an auxiliary sheet stacking unit located on the upstream side in the sheet feeding direction with respect to the stacking unit, the sheet stacking unit of the feeding unit and the sheet stacking unit, and the most upstream portion in the sheet feeding direction may be used. A sheet feeding device, wherein a sheet stacking surface of the auxiliary sheet stacking unit is separated from a connected straight extension line. 2. A sheet stacking means for stacking a plurality of sheets, a sheet feeding means for sequentially feeding from the highest or lowest sheet of the plurality of sheets on the sheet stacking means, and Sheet movement detection means for detecting that the last sheet of the plurality of sheets fed by the sheet feeding means has moved from above the means, and a sheet movement detection means located upstream of the sheet stacking means in the sheet feeding direction. In the sheet feeding apparatus provided with the auxiliary sheet stacking means, the sheet stacking surface of the auxiliary sheet stacking means is separated from a linear extension line connecting a portion of the sheet feeding means and the sheet movement detecting means in contact with the sheet. A sheet feeding device, comprising: 3. The sheet movement detecting means detects the movement of the sheet by blocking the light from the light emitting means to the light receiving means with a disk provided with a slit for transmitting light and rotated by the sheet. Claim 2
The sheet feeding apparatus according to claim 1. 4. The sheet stacking section of the sheet stacking means,
2. The sheet stacking means according to claim 1, wherein the sheet stacking means is a part of the sheet stacking means itself or a part of a side regulation provided in the sheet stacking means.
4. The sheet feeding device according to any one of claims 1 to 3. 5. The sheet stacking surface of each of the sheet stacking means and the auxiliary sheet stacking means has an angle of 1 on the sheet stacking side.
5. The sheet feeding apparatus according to claim 1, wherein the sheet intersects at an angle greater than 80 degrees. 6. The sheet feeding device according to claim 1, wherein said sheet feeding means has a feeding roller for feeding the sheet, and a separation pad for separating the sheet. Feeder. 7. A sheet feeding device according to claim 1, further comprising an intermediate plate between said sheet feeding means and said auxiliary sheet stacking means for guiding toward a feeding roller of said sheet feeding means.
The sheet feeding device according to any one of the above. 8. A sheet feeding device according to claim 1, an image forming section for forming an image on a sheet supplied by the sheet feeding device, and discharging the sheet after image formation. An image forming apparatus comprising: