JP2002356238A - Sheet feeding device and image forming device provided with device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance feeding efficiency of sheets. SOLUTION: The sheet feeding device 50 is provided with a delivery roller 51 with one part of an outer circumference cut out and conveying a sheet by contact rotation, a conveyance roller 52 with one part of an outer circumference cut out, provided coaxially with the delivery roller, capable of rotating independently of the delivery roller, and conveying the sheet by contact rotation, and a rotation regulating mechanism 58 rotating the conveyance roller so as to follow the delivery roller by regulating rotation of the conveyance roller to the delivery roller so that a rotation leading end part of the conveyance roller is positioned in a rotational direction rear of a rotation leading end part of the delivery roller. A radius of curvature of an arced face of the delivery roller contacting the sheet is set larger than a radius of curvature of an arced face of the conveyance roller contacting the sheet.

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 to an apparatus for handling the sheet, and an image forming apparatus incorporating the sheet feeding apparatus as a part of the apparatus.

[0002]

2. Description of the Related Art Conventionally, a sheet feeding apparatus is sometimes incorporated in a main body of an image forming apparatus which is an example of an apparatus for handling sheets.

Some image forming apparatuses use a roll material as a recording medium, and others use a sheet (cut paper). Specifically, a printer, a copier, a facsimile, and a multifunction machine thereof are used. and so on.

FIG. 7 shows a printer 10 as an example of an image forming apparatus. FIG. 8 shows the sheet feeding device 22. The pick-up roller 11 rotates in the direction of arrow P to rotate the tiltable sheet stacking plate 24 stored in the sheet feeding cassette 12.
The upper sheet S is pushed down in the direction of the arrow R against the spring 25 and fed out of the sheet feeding cassette 12. Separating claw 13
Separates the sheets one by one when the sheets are sent out overlapping. The conveying roller pair 14 conveys the sheet, makes the leading end of the sheet abut on the nip of the registration roller pair 15 that has stopped rotating, further continues the conveying, and turns the sheet into a curved shape as indicated by reference numeral Sa. The sheet is bent to correct the skew of the sheet.

On the other hand, a toner image is formed on the photosensitive drum 16 by the laser beam from the scanner unit 17 and the process cartridge 18. Photosensitive drum 16
Is rotated, the registration roller pair 15 starts rotating in accordance with the position of the toner image on the photosensitive drum 16 and feeds the sheet between the photosensitive drum 16 and the transfer roller 19. The transfer roller 19 applies the photosensitive drum 16 to the fed sheet.
Is transferred. The fixing unit 20 fixes the toner image on the sheet. Finally, the discharge roller pair 21 discharges the sheet to the outside of the printer 10. Thus, the image forming operation of the printer 10 on the sheet is completed.

Although only one pair of transport rollers 14 is provided, a plurality of pairs may be provided.

In the above-described printer 10, the sheet feeding cassette 12, the pickup roller 11, the separating claw 13, and the like constitute a sheet feeding device 22.

[0008]

The pickup roller 11 of the conventional sheet feeding device 22 is partially cut out and formed in a half-moon shape. The pick-up roller 11 is formed in a half-moon shape because the pick-up roller 11 feeds the sheet to the pair of conveying rollers 14 and then cuts out the sheet until the sheet is pulled out of the sheet supply cassette by the pair of conveying rollers 14. In order to prevent the sheet from being pulled out by the conveying roller pair 14 so as to prevent the sheet from being pulled out.

Therefore, the conventional sheet feeding device 22
However, since the sheet was not conveyed in the cut-out portion of the pickup roller 11, the sheet supply efficiency was poor.

In addition, the printer 10 having the conventional sheet supply device 22 having a poor sheet supply efficiency requires a pair of transport rollers 14 and a drive mechanism for the pair of transport rollers 14. It was difficult to reduce costs.

Further, in the conventional sheet feeding apparatus 22, the sheet feeding cassette 12 is attached to and detached from the apparatus main body 23 of the printer 10 in the direction of arrow C. It is difficult to reduce the size of the printer 10 that is disposed at a position that does not interfere with the printer 12 and that includes the conventional sheet feeding device 22.

[0012] Even when a conventional sheet feeding apparatus is incorporated as a part of the apparatus into an apparatus main body of an image forming apparatus other than a printer, it is similarly difficult to reduce the size and cost.

According to the present invention, a pickup roller is provided with a function of a pair of conveying rollers to enhance the sheet supply efficiency, and a sheet supplying apparatus is provided, and the conveying roller pair is omitted to reduce the size. It is an object to provide an image forming apparatus.

[0014]

In order to achieve the above object, a sheet feeding apparatus according to the present invention comprises a sheet stacking means on which sheets are stacked, and a sheet feeding means which rotates by contacting the sheet with a part of the outer periphery being cut out. A feed roller that conveys the sheet, the feed roller is disposed so as to coincide with the center of rotation, and the feed roller is rotatable individually, and a part of the outer periphery is cut out to contact the sheet and rotate. The conveying roller that feeds out the sheet, and the rotation of the conveying roller with respect to the feed roller is regulated such that the rotation start end of the feed roller is positioned rearward in the rotation direction of the rotation start end of the feed roller. Rotation restricting means for rotating the transport roller following the delivery roller, wherein the radius of curvature of the arc surface of the delivery roller that contacts the sheet is the transport roller. Wherein it is set larger than the radius of curvature of the arcuate surface which contacts the sheet.

In order to achieve the above object, a sheet feeding apparatus according to the present invention comprises a sheet stacking means on which sheets are stacked, and a feeder which cuts a part of the outer periphery to contact and rotate the sheets and conveys the sheets. A roller and the feed roller are disposed so as to coincide with the center of rotation, and the feed roller is rotatable individually, and a part of the outer periphery is cut out to contact the sheet and rotate to feed the sheet. A transport roller, and regulating the rotation of the transport roller with respect to the delivery roller so that the rotation start end of the transport roller is positioned rearward in the rotation direction of the rotation start end of the delivery roller; A rotation restricting means for rotating the sheet so as to follow the sheet, and a position spaced a predetermined distance from the rotation center of the sheet feeding roller by urging the sheet toward the sheet feeding roller. Sheet urging and positioning means for positioning, provided between the delivery roller and the transport roller, for biasing the transport roller to rotate so that the rotation start end of the transport roller approaches the rotation start end of the delivery roller. When the feed roller and the transport roller rotate in a direction away from the sheet,
The sheet is received by the sheet urging and positioning means, and a gap is formed between the sheet and the feed roller and the transport roller.

The rotation restricting means of the sheet feeding apparatus according to the present invention is configured to restrict the rotation of the transport roller with respect to the delivery roller so that the rotation start end of the transport roller always faces the delivery roller. .

The sheet feeding apparatus according to the present invention further includes a separating unit for separating the sheet when the sheets are stacked and sent out from the sheet stacking unit, and the sheet sending distance of the sending roller is set by the separating unit. The distance is set to be equal to or longer than a distance required for separating the sheet.

In the sheet feeding apparatus of the present invention, a projection is provided at the rotation start end of the transport roller so as to protrude radially from the arc surface of the delivery roller.

The sheet feeding apparatus according to the present invention further comprises a resistance to the rotation of the transport roller between the time when the feed roller contacts the sheet and the time when the transport roller follows the feed roller by the regulating means. Is provided.

The feed roller and the transport roller of the sheet feeding apparatus according to the present invention are configured to stop rotating when the gap is formed between the sheet and the sheet.

The feed roller and the transport roller of the sheet feeding apparatus of the present invention are respectively disposed at substantially the same positions from both edges of the sheet along the sheet transport direction.

The feed roller and the transport roller of the sheet feeding apparatus of the present invention are provided at substantially the same position from both edges of the sheet along the sheet transport direction and corresponding to the size of the sheet. .

According to another aspect of the present invention, there is provided an image forming apparatus including: any one of the above-described sheet supply apparatuses; and image forming means for forming an image on the sheet supplied by the sheet supply apparatus. I have.

In order to achieve the above object, an image forming apparatus according to the present invention includes any one of the above-described sheet feeding apparatuses, and an image forming unit that forms an image on the sheet supplied by the sheet feeding apparatus. The sheet stacking means of the sheet supply device is detachably provided on the apparatus main body.

In order to achieve the above object, an image forming apparatus according to the present invention is arranged such that any one of the above-mentioned sheet feeding devices, and the feed roller and the conveying roller of the sheet feeding device are separated from the sheet and stop rotating. And a drawer-conveying means for conveying the sheet while pulling it out of the sheet supply cassette.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a sheet feeding apparatus according to an embodiment of the present invention and a printer incorporating the sheet feeding apparatus as a part of the apparatus will be described with reference to the drawings.

The sheet feeding apparatus according to the present embodiment can be incorporated as a part of an apparatus main body of an image forming apparatus other than a printer, such as a copying machine, a facsimile, and a composite device thereof. It has become.
Therefore, the sheet feeding apparatus of the present embodiment is not used by being incorporated in only a printer.

(Sheet Feeding Device of First Embodiment) In FIGS. 1 to 3, a sheet feeding device 50 includes a sheet feeding cassette (sheet feeding cassette) 32, a feed roller 51, a conveying roller 52, and a separating claw (separating means). 34 and the like, and are incorporated in a printer (image forming apparatus) 70.

The sheet supply cassette 32 includes a printer 70
The main body 35 is detachably disposed in the direction of arrow C. One end of the sheet stacking plate 36 is connected to the sheet supply cassette 3.
2 is supported by a support shaft 47, and the other end is pushed up by a spring 37. For this reason, the sheet stacking plate 36
Are stored in the sheet supply cassette 32 in a tiltable manner. Separating claws 34 are provided above both ends of the sheet stacking plate 36 on the downstream side in the sheet feeding direction. A spring 37 is provided between the sheet stacking plate 36 and the sheet supply cassette 32. The spring 37 presses the downstream end in the feeding direction of the sheets S stacked on the sheet stacking plate 36 against the separation claw 34. The separation claw 34 and the spring 37 constitute sheet urging positioning means.

FIGS. 2 and 3 show the rollers for feeding the sheet.
The two of the sending roller 51 and the conveying roller 52 shown in FIG.
There is one.

The delivery roller 51 is fixed to the drive shaft 53, and the remaining approximately (1/3) obtained by cutting off about (2/3) of the circle is used.
It is formed in the shape of 3). It is formed in a so-called fan shape. The delivery roller 51 includes a resin body 54 formed in a V-shape and fixed to the drive shaft 53, and a delivery bat 55 attached to the V-shaped valley of the body 54 and integrated with the body 54. Is formed. Delivery bat 55
Are formed in an arc shape using a friction material such as resin or rubber having a large friction coefficient. When the delivery roller 51 rotates, a portion of the delivery bat 55 contacts the sheet and presses the sheet against the separation claw 34. The sheet feeding distance of the feeding roller 51 is set to be equal to or longer than a distance required for separating the sheet by the separation claw 34.

The transport roller 52 is provided on the drive shaft 53 of the feed roller 51 so as to be rotatable separately from the feed roller 51, and the remaining (（) of the circle obtained by cutting out about (２) of the circle. It is formed in the shape of. It is formed in a so-called fan shape. However, the transport roller 52 has a shape with more cutout portions and fewer remaining portions than the feed roller 51.

The transport roller 52 is formed in a V-shape and is provided with a resin main body 56 rotatably provided on a drive shaft 53.
The main body 56 is formed by a transfer bat 57 attached to the V-shaped valley and integrated with the main body 56. Transfer bat 5
Reference numeral 7 is formed in an arc shape using a friction material such as resin or rubber having a large friction coefficient. When the transport roller 52 rotates, the transport butt 57 contacts the sheet, and the sheet is sent to the registration roller pair 38.

The radius of curvature A1 of the arc surface of the delivery bat 55 that contacts the sheet (the arc surface 51b of the delivery roller 51) is the radius of curvature of the arc surface of the delivery bat 57 that contacts the sheet (the arc surface 52b of the delivery roller 52). It is set larger than A2. The rotation start end 52 a of the transport roller 52 is provided with a rotation prevention protrusion (projection) 65 that protrudes in a radial direction from an arc surface of the delivery bat 55.

The rotation angle of the transport roller 52 with respect to the feed roller 51 is regulated by a rotation regulating mechanism (rotation regulating means) 58. Drive shaft 53 of feed roller 51
Rotation restricting groove 61 and rotation restricting protrusion 59 of transport roller 52
Constitute a rotation restricting mechanism 58.

As shown in FIG. 4, a part of the outer periphery of the drive shaft 53 is formed with a projection insertion guide groove 60 in the thrust direction. Further, a rotation restricting groove 61 is formed in the radial direction continuously from the protrusion insertion guide groove 60. The rotation restricting projection 59 protrudes inside the through hole 62 in which the transport roller 52 receives the drive shaft 53.

The incorporation of the transport roller 52 into the drive shaft 53 is performed as follows.

First, the drive shaft 53 is inserted into the through hole 62 of the transport roller 52, and the rotation restricting protrusion 59 is inserted into the protrusion insertion guide groove 60. After that, the transport roller 52 is pushed in the thrust direction of the drive shaft 53 and moved to the rotation regulating groove 61. Then, the rotation restricting projection 59 can be rotated in the radial direction while being guided by the rotation restricting groove 61. In order to prevent the rotation restricting protrusion 59 from returning to the protrusion inserting guide groove 60 from the rotation restricting groove 61, a retaining protrusion 63 is protrudingly provided at the end of the protrusion inserting guide groove 60. When the transport roller 52 is inserted into the drive shaft 53, the rotation restricting protrusion 59 is made of resin, so that it is elastically deformed, passes through the retaining protrusion 63, and is inserted into the rotation restricting groove 61.

As shown in FIG. 3 (a), the rotation start mechanism 52 of the transport roller 52 causes the rotation start end 52a of the feed roller 51 to rotate.
It is regulated so that it is always located behind the rotation direction of a. More specifically, the rotation start end 52 of the transport roller 52
The portion a is always opposed to the delivery roller 51.

In FIG. 2, a rotation start end 5 of the transport roller 52 is provided between the feed roller 51 and the transport roller 52.
A tension spring (urging means) 64 for urging the feed roller 2a toward the rotation start end 51a of the feed roller 51 is provided. Therefore, when the delivery roller 51 rotates, the transport roller 52 is pulled by the tension spring 64 and rotates following the delivery roller 51 to rotate.
2a approaches the rotation start end 51a of the delivery roller 51. For this reason, when the feed roller 51 makes one rotation from the position shown in FIG. 5A described later and returns to the standby position in FIG. 5A, the transport roller 52 is pulled by the tension spring 64 to the standby position. I'm going back. Therefore, when the feed roller 51 returns to the standby position, the tension spring 64 returns the transport roller 52 to the standby state, and the transport roller 52 together with the feed roller 51 passes under the feed roller 51 and the transport roller 52. To prevent the sheet from interfering with the sheet.

It should be noted that the rotation regulating mechanism 58 is
Although it is provided between the drive roller 2 and the drive shaft 53, it may be provided between opposing surfaces of the feed roller 51 and the transport roller 52. That is, one projection (not shown) is provided on one of the feed roller 51 and the transport roller 52, and two projections are provided on both sides of the one projection in the rotation direction of the other roller. The rotation angle of the transport roller 52 with respect to the feed roller 51 may be set according to the interval between the protrusions.

In the above configuration, the sheets are stacked on the sheet stacking plate 36 in FIG. 1, urged upward by the spring 37, and received by the fixed separation claws 34. For this reason, as shown in FIG. 5A, the uppermost sheet S1 is received by the separation claw 34 and positioned at a predetermined height position.

On the other hand, the feed roller 51 and the transport roller 5
2 is waiting at a standby position away from the sheet, as shown in FIG. The drive shaft 53 of the delivery roller 51 is configured to stay at a fixed position and rotate. For this reason, the delivery roller 51 and the transport roller 52
Does not move up and down.

When the drive shaft 53 rotates in the direction of arrow P, the delivery roller 51 also rotates integrally with the drive shaft 53. At this time, the transport roller 52 also has a tension spring 64 (see FIG. 2).
And rotates following the feed roller 51. When the feed roller 51 starts rotating, as shown in FIG. 5B, the portion of the feed bat 55 comes into contact with the uppermost sheet S1 and pushes down the entire sheet against the tension spring 64 to lower the uppermost sheet. Is moved to the downstream side. However, the uppermost sheet S <b> 1 cannot advance because the downstream end portion enters under the separation claw 34. For this reason, as shown in FIG.5 (b), the delivery bat 55 bends and bends the uppermost sheet S1, and
The deflection is increased. On the other hand, since the entire sheet is pushed down by the feed roller 51, a gap is formed between the uppermost sheet S1 and the separation claw.
When the bending of the uppermost sheet S1 is equal to or more than a predetermined bending amount, the sheet S1 is separated from the separation claw 34 by a gap between the sheet S1 and the separation claw 34. At this time, the second sheet S2 cannot come off the separation claw 34.

As shown in FIG. 5C, when the uppermost sheet S1 comes off the separation claw 34, the delivery roller 51 causes the sheet S to move over the separation claw 34 due to friction between the delivery bat 55 and the sheet S. Let it pass.

On the other hand, from the start of rotation of the feed roller 51 in the direction of the arrow P, until the uppermost sheet S1 is removed from the separation claw 34, the transport roller 52 is pulled by the tension spring 64 and follows the feed roller 51. I do. But,
The transport roller 52 includes a rotation preventing protrusion 65 of the transport roller 52.
Rotation is regulated by contacting the sheet at the portion. This rotation is regulated by keeping the delivery roller 52 pulled by the tension spring 64 in the state shown in FIG.
This is performed in order to prevent the sheet from passing over the sheet without being conveyed while rotating over the sheet 1. That is,
The rotation preventing protrusion 65 is provided to prevent the transport roller 52 from passing over the sheet while overlapping the feed roller 51.

The rotation restriction is continued until the rotation restriction surface 61 a of the rotation restriction groove 61 formed on the drive shaft 53 contacts the rotation restriction protrusion 59. Rotation restricting surface 6 of rotation restricting groove 61
When the rotation control protrusion 1a comes into contact with the rotation restricting protrusion 59, as shown in FIG. 5C, the rotational force of the drive shaft 53 is transmitted to the transport roller 52, and the transport roller 52 also starts rotating. That is, the transport roller 52 starts rotating with a phase difference set in the rotation restricting mechanism 58 later than the feed roller 51. At this time, the spring 64 is extended according to a phase difference generated between the feed roller 51 and the transport roller 52.

At the beginning of rotation, the transport roller 52 starts transporting the sheet following the feed roller 51 while pushing down the entire sheet once against the spring 37 at the rotation preventing protrusion 65. Then, the transport roller 52 transports the uppermost sheet S1 at the transport butt 57 portion. At this point, conveyance of the uppermost sheet S1 by the feed roller 51 has been completed, but the feed roller 51
Therefore, the rotation with the drive shaft 53 is continued.

When the transport butt 57 comes into contact with the uppermost sheet S1, the radius of curvature A2 of the transport bat 57 is smaller than the radius of curvature A1 of the feed bat 55. And the uppermost sheet S <b> 1 comes into contact with the transport butt 57.

The reason why the radius of curvature of the delivery bat 55 is different from that of the transport bat 57 is as follows. In order to feed the uppermost sheet S1 into contact with the separation claw 34 and feed the uppermost sheet S1, the feed bat 55 must increase the pressure applied to the uppermost sheet S1 to increase the conveying force. However, the conveying butt 57 does not require a large conveying force since it only feeds the sheet to the registration roller pair 38, and does not need to increase the pressure contact pressure against the uppermost sheet S1 as much as the feeding bat 55.

Therefore, since the transport butt 57 only feeds the uppermost sheet S1 to the pair of registration rollers 38, the uppermost sheet S1 can be transported without slipping even if the pressure contact pressure is small. The rotational driving force of the transport roller 52 can be reduced by the reduced pressure.

When the conveying force for feeding the sheet in contact with the separation claw 34 is small, the radius of curvature of the feeding bat 55 and the conveying bat 57 may be the same.

Thereafter, the transport rollers 52
At the portion 7, the downstream end of the uppermost sheet S <b> 1 is fed to the registration roller pair 38. However, the registration roller pair 38
As described above, after the rotation is stopped, the skew of the sheet is straightened, and the sheet is moved between the photosensitive drum 41 and the transfer roller 42 in accordance with the position of the toner image on the photosensitive drum 41. Supply.

When the pair of registration rollers 38 starts feeding a sheet, the transport roller 52 moves away from the uppermost sheet S1. When the transport roller 52 separates from the uppermost sheet S <b> 1, it is pulled by the tension spring 64 and rotates until the rotation restricting projection 59 contacts the receiving surface 61 b of the rotation restricting groove 61.

The entire sheet is released from the pressing by the conveying roller 52, and the uppermost sheet S1 is conveyed by the registration roller pair 38. The second and subsequent sheets are pushed up by the spring 37, received by the separation claw 34, and held at a predetermined height.

The delivery roller 51 and the transport roller 52 are
Until the top sheet S1 is completely pulled out of the sheet supply cassette 32 by the registration roller pair 38, the rotation is stopped and the apparatus stands by at the standby position. Therefore, a gap is formed between the feed roller 51 and the transport roller 52 and the uppermost sheet S1, and the uppermost sheet S1
Is smoothly pulled out of the sheet supply cassette 32 without coming into contact with the feed roller 51 and the transport roller 52.

When the uppermost sheet S1 is completely pulled out of the sheet supply cassette 32, the feed roller 51
However, the rotation is started again, the second sheet S2 is separated from the third sheet in the same manner as the uppermost sheet S1, and is pushed out from the separation claw 34. The sheet S2 is subsequently conveyed and sent to the registration roller pair 38. The sheet feeding device 50 successively feeds the sheets sequentially to the registration roller pair 38 in the same manner.

In the above-described sheet feeding apparatus 50, the feed roller 51 and the conveying roller 52 stop rotating once at the standby position, but depending on the sheet size, do not stop and return to the standby position. The uppermost sheet can be pulled out while the feed roller 51 contacts the next sheet. Therefore, the feed roller 51 and the transport roller 52 do not necessarily need to stop rotating at the standby position.

The sheet is separated by a separation claw 34. The sheet is separated by bringing the downstream end of the sheet into contact with a separation slope (not shown) provided at the downstream end of the sheet supply cassette 32. It may be. In this case, since the sheet does not need to be pushed up by the spring 37, the sheet is kept stored in the sheet supply cassette 32, and the delivery roller 51 and the conveyance roller 52 are moved closer to and away from the sheet. . Therefore, the feed roller 51 and the transport roller 52 need only be separated from the sheet while the sheet is being pulled out from the sheet supply cassette 32 by the registration roller pair 38, so that when the feed roller 51 is at the standby position, the transport roller 52 is The tension spring 64 for returning to the standby position is not necessarily required.

The feed roller 51 and the transport roller 5
2 is an arrow B which is the sheet conveying direction as shown in FIG.
A pair is provided at substantially the same position from both edges of the sheet along the direction. As a result, the pair of feed rollers 5
1 and the transport roller 52 do not apply a biased transport force to the sheet, so that the sheet can be fed and transported.

If only one size sheet is to be supplied, as shown in FIG. 2, a pair of feed roller 51 and transport roller 52 may be provided. It is necessary to provide the feed roller 51 and the transport roller 52 at substantially the same position from both edges of the sheet along the sheet transport direction, corresponding to the size of the sheet.

The sheet feeder 50 of the second embodiment described above has a configuration in which the notch of the conventional pickup roller is supplemented by the transport roller 52, and the sheet is fed from the sheet feed cassette 32 by the feed roller 51.
The sheet is transported to the registration roller pair 38 by the transport roller 52. Therefore, the sheet feeding device 5
0 indicates that the feed roller 51 and the transport roller 52 on the same axis have both the function of the conventional pickup roller 11 (see FIG. 7) and the function of the transport roller pair 14, and increase the sheet supply efficiency. be able to. Also,
When the feed roller 51 and the transport roller 52 are at the standby position, the sheet feeding device 50
, And the sheet supply cassette 32 is also easily pulled out.

(Printer Equipped with Sheet Feeding Device of First Embodiment) In the printer 70 shown in FIG. 1, the feed roller 51 and the conveying roller 52 of the sheet feeding device 50 use the sheet stored in the sheet feeding cassette 32 to feed the sheet. Send out from 32. The separation claw 34 separates the sheets one by one when the sheets are sent out in an overlapping manner. The feed roller 51 and the conveying roller 52 convey the sheet, make the leading end of the sheet abut the nip of the registration roller pair 38 that is not rotating, further continue the conveyance, and bend the sheet in a curved shape. Correction is made when the sheet is skewed.

On the other hand, a toner image is formed on the photosensitive drum 41 by the laser beam from the scanner unit 43 and the process cartridge 46. Photosensitive drum 41
The registration roller pair 38 starts rotating in accordance with the position of the toner image on the photosensitive drum 41 and feeds a sheet between the photosensitive drum 41 and the transfer roller 42.
The transfer roller 42 applies the photosensitive drum 4 to the fed sheet.
The first toner image is transferred. Then, the fixing unit 44 fixes the toner image on the sheet. Finally, the discharge roller pair 45
Discharges the sheet to the outside of the main body 35 of the printer 70. Thus, the image forming operation of the printer 70 on the sheet is completed. The photosensitive drum 41, the process cartridge 46, and the like constitute an image forming unit.

The printer 70 of this embodiment has a sheet feeding device 50 in which the feed roller 51 and the transport roller 52 have the function of the conventional pickup roller 11 (see FIG. 7) and the function of the transport roller pair 14. Therefore, there is no need to provide the transport roller pair 14 and the drive mechanism of the transport roller pair, which are required in the related art, so that the structure can be simplified, the height can be reduced and the size can be reduced, and the cost can be reduced. Can be achieved.

Further, when it is not necessary to provide the transport roller pair 14, the structure of the printer 70 can be made simple so that the sheet supply cassette 32 can be easily attached to and detached from the main body 35 of the printer 70.

(Sheet Feeding Apparatus of Second Embodiment) First
In the sheet supply device 50 of the embodiment, the transport rollers 5
After the sheet is supplied, the sheet is pulled by a tension spring 64 and rotates to a standby position shown in FIG. 5A. When the feed roller 51 rotates from the standby position, the feed roller 51 Rotate while overlapping,
There is a risk of passing over the sheet without contacting the sheet. In order to prevent this, a rotation preventing protrusion 65 protruding in the radial direction from the delivery roller 51 is provided on the conveyance roller 52, and the rotation prevention protrusion 65 hits the sheet, so that the conveyance roller 52 overlaps the delivery roller 51. The risk of passing over the sheet as it is is prevented.

Therefore, the sheet feeding device 8 of the second embodiment
Numeral 0 is provided on the transport roller 52 with a rotation delay mechanism (rotation resistance means) 81 that functions in the same manner as the rotation prevention protrusion 65.

That is, the rotation delay mechanism 81 includes an arc-shaped friction plate 82 provided on a side surface of the transport roller 52 and an elastic pressure-contacting piece 83 having one end fixed and the other end pressed against the friction plate 82. It is configured.

When the feed roller 51 starts rotating,
The transport roller 52 is pulled by the tension spring 64 and rotates following the feed roller 51 as shown in FIG. When the feed roller 51 rotates to a position where it contacts the sheet, the friction plate 82 comes into contact with the pressure contact piece 83. Then, the transport roller 52 is moved between the friction plate 82 and the pressure contact piece 8.
The rotation is stopped by the friction with 3. However, the feed roller 51 continues to rotate and conveys the sheet.

When the feeding roller 51 finishes conveying the sheet, a rotation regulating groove 61 formed in the drive shaft 53 is formed.
The rotation restricting surface 61a (see FIG. 4) contacts the rotation restricting projection 59. Then, the conveyance roller 52 starts rotating by overcoming the friction between the friction plate 82 and the pressure contact piece 83, and conveys the sheet following the feed roller 51. Friction plate 8
2 is a pressing piece 83 with the rotation of the transport roller 52.
Move away from The arc length of the friction plate 82 is set to a length from when the feed roller 51 comes into contact with the sheet to when the transport roller 52 rotates following the feed roller 51 by the rotation regulating mechanism 58. Therefore, the conveyance roller 52 is not subjected to the frictional resistance between the friction plate 82 and the pressure contact piece 83 by the time the sheet is conveyed, so that the conveyance roller 52 can be rotated by the tension spring 64 to the standby position. .

The sheet feeding device 80 of the second embodiment can improve the sheet feeding efficiency, similarly to the sheet feeding device 50 of the first embodiment.

Further, the sheet feeding device 8 of the second embodiment
0 is different from the sheet supply device 50 of the first embodiment,
Since it does not have the rotation preventing protrusion 65 that protrudes in the radial direction from the feed roller 51, the transport roller 52 does not push down the entire sheet once against the spring 37, and also abruptly applies a short time to the drive source. It rotates smoothly without imposing a heavy load.

Further, in the sheet feeding devices 50 and 80 of the above embodiments, the functions of the pair of the conveying rollers 14 of the conventional example are provided for both the feed roller 51 and the conveying roller 52, but the conventional example is not used. In the case where there are a plurality of pairs of transport rollers as described above, a function for a plurality of pairs of transport rollers from the upstream side may also be provided. Therefore, the sheet supply devices 50 and 80 are not limited to having only the function of one pair of transport rollers, but also have at least the function of the pair of transport rollers closest to the sheet supply cassette. It is necessary to be.

Further, the sheet feeding devices 50 and 80 of the above embodiments are adapted to feed a sheet to the pair of register rollers, but depending on the printer, the distance to the pair of register rollers is long, In some cases, one or a plurality of pairs of transport rollers may be provided halfway between the pairs. In such a case, the sheet feeding devices 50 and 8
A value of 0 means that the sheet is supplied to the most upstream conveying roller pair. Therefore, the sheet feeding devices 50 and 80
The invention is not limited to supplying sheets only to the pair of registration rollers.

[0076]

According to the sheet feeding apparatus of the present invention, the feeding roller and the conveying roller having the same rotation center have the function of the conventional pickup roller and conveying roller pair, so that the sheet feeding efficiency can be improved. it can.

The image forming apparatus of the present invention is provided with a sheet feeder in which the feed roller and the transport roller having the same rotation center have the functions of the conventional pickup roller and transport roller pair, so that the image forming apparatus can be downsized. can do.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view of a printer including a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line FF of FIG. 1;

FIG. 3 is a view taken in the direction of arrows HH in FIG. 2; FIG. 3A is a diagram illustrating a state in which a conveyance roller and a delivery roller overlap each other. (B) It is a figure of a sending-out roller. (C) is a view of a transport roller.

FIG. 4 is a perspective view of a drive shaft.

FIG. 5 is a view illustrating the operation along arrow HH in FIG. 2; (A) is a state diagram before sheet supply is started. FIG. 5B is a diagram illustrating a state in which sheet supply has begun. FIG. 6C is a diagram illustrating a state in which the sheet is separated and supplied by the separation claw, and is started to be sent out from the sheet supply cassette. FIG. 5D is a diagram illustrating a state in which the sheet has been fed to a pair of registration rollers.

FIG. 6 is a diagram illustrating a main part of a sheet feeding apparatus according to a second embodiment.

FIG. 7 is a schematic front sectional view of a printer as an example of an image forming apparatus provided with a conventional sheet supply device.

FIG. 8 is a diagram illustrating the operation of the sheet feeding apparatus of FIG. 7; (A) is a state diagram before sheet supply. (B) It is a figure in the state where a sheet is separated. FIG. 4C is a diagram illustrating a state in which the sheet is being sent out from the sheet supply cassette.

[Explanation of symbols]

S sheet S1 Top sheet S2 Second sheet A1 Curvature radius of feed roller A2 Curvature radius of transport roller 32 Sheet supply cassette (sheet stacking means) 34 Separating claw (separating means, sheet biasing positioning means) 37 Spring ( Sheet urging positioning means) 38 registration roller pair (pull-out conveyance means) 50 sheet feeding device 51 of the first embodiment 51 delivery roller 51a rotation start end of delivery roller 51b arc surface of delivery roller 52 transportation roller 52a rotation end of transportation roller 52b Arc surface of conveyance roller 58 Rotation restricting mechanism (rotation restricting means) 59 Rotation restricting projection 61 Rotation restricting 65 Rotation preventing projection (protrusion) 64 Tension spring (biasing means) 70 Printer (image forming apparatus) 80 Second embodiment Sheet feeding device 81 Rotation delay mechanism (rotation resistance means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03G 15/00 518 G03G 15/00 518 F-term (Reference) 2H072 AB10 BA02 BA03 BA12 BA17 CA01 CB05 JA02 JA08 3F343 FA02 FB02 FB03 FC01 FC15 GA02 GB01 GC01 GD01 HA16 HB03 HC04 HD17 JA03 JA16 JA17 KA06 KB04 KB05 KB14 LA03 LA13 LC11 LC21 LD04 MB03 MB13 MB14

Claims (12)

[Claims] 1. A sheet stacking means on which sheets are stacked, a delivery roller for cutting and rotating the part of the outer periphery to contact the sheet and convey the sheet, and a rotation center coincident with the delivery roller. Arranged,
A feed roller that can rotate independently from the feed roller, and that cuts out a part of the outer periphery to rotate in contact with the sheet and feeds the sheet; and a rotation start end of the feed roller is a rotation start end of the feed roller. Rotation regulating means for regulating the rotation of the transport roller with respect to the feed roller so as to be located rearward in the rotation direction of the portion, and rotating the transport roller to follow the feed roller. Wherein the radius of curvature of the arc surface that contacts the sheet is set to be larger than the radius of curvature of the arc surface that contacts the sheet of the transport roller. 2. A sheet stacking means on which sheets are stacked, a feed roller which cuts a part of an outer periphery to contact and rotate the sheet and conveys the sheet, and a center of rotation of the feed roller coincides with that of the feed roller. Arranged,
A feed roller that can rotate independently from the feed roller, and that cuts out a part of the outer periphery to rotate in contact with the sheet and feeds the sheet; Rotation restricting means for restricting rotation of the transport roller with respect to the feed roller so as to be located rearward in the rotation direction of the unit, and rotating control means for rotating the transport roller to follow the feed roller; and attaching the sheet to the feed roller side. Urging the sheet urging positioning means for positioning the roller at a predetermined distance from the rotation center of the feed roller; and urging the conveying roller provided between the feed roller and the conveying roller to urge the conveying roller. Urging means for bringing the rotation start end of the transport roller closer to the rotation start end of the delivery roller; and When the feed roller rotates in a direction away from the sheet, the sheet is received by the sheet urging and positioning means, and a gap is formed between the feed roller and the transport roller and the sheet. Sheet feeding device. 3. The rotation restricting means restricts the rotation of the transport roller with respect to the delivery roller such that the rotation start end of the transport roller always faces the delivery roller. A sheet feeding device according to claim 1. 4. A sheet separating means for separating the sheets when the sheets are stacked and sent out from the sheet stacking means, and a sheet feeding distance of the feeding roller is necessary for separating the sheets by the separating means. The sheet feeding device according to any one of claims 1 to 3, wherein the sheet feeding device is set to be longer than a predetermined distance. 5. The feed roller according to claim 1, wherein a protrusion protruding radially from an arc surface of the delivery roller is provided at a rotation start end of the transport roller. Sheet feeding device. 6. A rotation resistance means for imparting resistance to the rotation of the transport roller from when the feed roller contacts the sheet to when the transport roller rotates following the feed roller by a regulating means. The sheet feeding apparatus according to any one of claims 1 to 4, wherein: 7. The sheet feeding device according to claim 6, wherein the feed roller and the transport roller stop rotating when the gap is formed between the sheet and the sheet. 8. The apparatus according to claim 1, wherein the feed roller and the transport roller are respectively disposed at substantially the same position from both edges of the sheet along the sheet transport direction. 2. The sheet feeding device according to claim 1. 9. The sheet feeding roller and the conveyance roller are provided at substantially the same position from both edges of the sheet along the sheet conveyance direction and corresponding to the size of the sheet. Claims 1 to 7
The sheet feeding device according to any one of the above. 10. A sheet supply device according to claim 1, further comprising: an image forming unit configured to form an image on the sheet supplied by the sheet supply device. Characteristic image forming apparatus. 11. The sheet, comprising: the sheet supply device according to claim 1; and an image forming unit configured to form an image on the sheet supplied by the sheet supply device. An image forming apparatus, wherein the sheet stacking means of the supply device is detachably provided on the apparatus main body. 12. The sheet supply device according to claim 1, wherein the feed roller and the conveyance roller of the sheet supply device are separated from the sheet and stopped rotating. An image forming apparatus, comprising: a drawer-conveying means for drawing the sheet from the sheet supply cassette and conveying the sheet.