JPH09124169A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent a failure, an overlap, and a skew in paper feeding without respect to paper quality. SOLUTION: A paper feeding pressure is increased by bringing a wide area between the center part and vicinities of both sides of paper with paper feeding rollers 13 by means of paper pressers 20, 27. In this way, special paper other than ordinary one can be surely pulled out toward a paper feeding destination. According to this process, a paper separating member 23 arranged in the center does not need to be brought into pressure contact with the paper feeding roller 13 by unnecessarily intensive pressing force for increasing a paper feeding pressure forcibly, so that the paper separating member 23 is brought into pressure contact with the paper feeding roller 13 by a proper pressure and paper separating performance can be improved. The paper separating member 23 brought into pressure contact with the paper feeding roller 13 with comparatively high pressing force for the purpose of paper separation is arranged in the center part corresponding to the center of the paper, so that resistant against the paper can be distributed evenly to the left side and the right side substantially, and as a result, a skew in paper feeding can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device used for office automation equipment such as printers and copiers for separating stacked sheets one by one and feeding them.

[0002]

2. Description of the Related Art As a sheet feeding device of this type, a sheet feeding roller for pulling out a sheet by frictional force is rotatably provided at an end of a sheet feeding tray that supports sheets in a stacked state,
When the paper separating member formed of an elastic material such as cork is elastically brought into contact with the outer circumference of the paper feeding roller and a plurality of paper sheets pulled out from the paper feeding tray by the paper feeding roller are overlapped, the paper is fed. There is a sheet feeding device configured to pass only one sheet between a roller and a sheet separating member.

[0003]

As the paper sheet to be fed, a strong paper sheet such as a postcard, a cardboard, a continuous paper, or a special paper sheet such as a heavy paper sheet, and the others. There is a normal paper sheet of, but compared with the case of feeding a normal paper sheet, when feeding a special paper sheet, the paper feeding pressure must be set high to ensure that the paper is fed. I can't. In the above-mentioned conventional example, since there is one sheet feeding roller, the desired sheet feeding pressure cannot be obtained unless the sheet separating member is brought into pressure contact with this sheet feeding roller. If the paper feed pressure is increased at one place in this way, when a plurality of paper sheets are pulled out between the paper feed roller and the paper sheet separating member, the frictional force between the paper sheets becomes extremely large, and The separability of the leaves is impaired.

When a plurality of paper feed rollers and paper sheet separating members are arranged along the width direction of the paper sheet, the paper sheet separating members are pressed against the paper feeding roller with an appropriate pressure. Thus, it becomes possible to obtain the sheet feeding pressure suitable for the above-mentioned special sheet while ensuring the sheet separation performance. However, since the sheet feeding roller and the sheet separating member come into contact with each other with a relatively high contact pressure, when a difference occurs in the contact pressure between the plurality of sheet feeding rollers arranged on the left and right and the sheet separating member. Causes a difference in resistance applied to both sides of the sheet, and the sheet may skew.

Further, when a paper sheet is advanced at a small advancing angle with respect to a tangent line passing through a contact portion between the paper sheet separation member and the outer peripheral surface of the paper feed roller, the paper sheet is separated between the paper sheet separation member and the paper feed roller. Although the leaves can easily pass through, a plurality of strong and heavy paper sheets are easily overlapped and easily come out.

[0006]

According to the first aspect of the present invention,
A rotatable paper feed roller that contacts at least the central portion and both sides of the paper leaf, a paper presser that presses the floating of the paper leaf from the outer periphery of the paper feed roller, and a downstream side of the paper presser A paper sheet separating member is elastically pressed against the outer peripheral surface of the paper feed roller at a central position facing the central portion of the paper sheet with a desired pressure. Therefore, the paper feeding force of the paper feeding roller is enhanced by bringing the paper feeding roller into contact with the paper feeding roller over a wide range between the central portion and the portions near both sides of the paper sheet. Further, since the paper sheet separating member that is pressed against the paper feed roller with a relatively high pressure for separating the paper sheet is arranged at the central position facing the center of the paper sheet, the paper sheet separating members are disposed on both sides of the paper sheet separating member. The resistance given to the paper and the difference between those resistances are reduced, and the paper sheet does not skew.

According to a second aspect of the present invention, in the first aspect of the invention, three or more odd numbers are arranged at a central position facing the central portion of the paper sheet and a symmetrical position about this central position. The paper feed roller is rotatably provided coaxially, and the paper sheet separating member is elastically pressed against the outer peripheral surface of one of the paper feed rollers arranged in the center with a desired pressure. Therefore, the paper sheet is brought into contact with three or more paper feed rollers by the paper retainer, and the center and both sides of the paper sheet are pulled by the three or more paper feed rollers, so that the paper feeding force is enhanced. Also,
Since the paper feed roller to which the paper separating member is pressed with a relatively high pressure for separating the paper is one paper feed roller arranged in the center, the paper is separated on both sides of the central paper feed roller. The difference in resistance given is small, and the paper sheet does not skew.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the relationship between a paper feed roller, a paper separating member and a paper retainer, FIG. 2 is a side view showing the relationship between a central paper feed roller, a paper separating member and a paper retainer, and FIG. 4 is a side view showing the relationship between the paper feed roller and the paper presser, FIG. 4 is a side view showing another example of the paper presser, and FIG. 5 is a vertical sectional side view showing the internal structure of the image forming apparatus.

First, the image forming apparatus will be described with reference to FIG. In the figure, 1 is an image forming apparatus main body. A photoconductor 2 is rotatably supported in the center of the image forming apparatus main body 1, and a contact type charger 3 for charging the surface of the photoconductor 2 is provided around the photoconductor 2, and a nonmagnetic one component. A developing device 4 containing toner, a rotatable transfer roller 5, a cleaning unit 6 and the like are provided. An exposure unit that forms an electrostatic latent image on the photoconductor 2 by deflecting and scanning the photoconductor 2 with a polygon mirror 7 that rotates a laser beam modulated according to an image signal is provided below the image forming apparatus main body 1. 8 are provided. Further, a fixing device 9 is provided near the end of the image forming apparatus main body 1.

Further, a paper feed tray 10 that supports sheets of paper in a stacked state is detachably attached to the upper portion of the image forming apparatus main body 1. This paper feed tray 10 is an auxiliary tray 1 that is extended upward when long paper is used.
1 and a paper guide 12 that slides in the left-right direction according to the width of the paper. A plurality of paper feed rollers 13 for drawing out the paper inserted from the paper feed tray 10 are rotatably held together with a drive shaft 14 on the upper part of the image forming apparatus main body 1. Further, a cover 15 for opening and closing the upper surface of the image forming apparatus main body 1 is provided rotatably around the drive shaft 14. The cover 15 holds a pair of conveying rollers 16 and the transfer roller 5 rotatably.

In such an image forming apparatus, the outer periphery of the photoconductor 2 is charged by the charger 3 during the process of driving the photoconductor 2 in the clockwise direction.
The exposure unit 8 deflects and scans the charged portion to form an electrostatic latent image, and the electrostatic latent image is developed by the developing device 4. Then, the developed image on the photoconductor 2 is transferred by the transfer roller 5 onto the paper fed by the paper feed roller 13 and conveyed by the convey roller 16. Then, the transfer image on the paper conveyed by the photoconductor 2 and the transfer roller 5 is fixed by the fixing device 9, and the paper after fixing is discharged by the paper discharge roller 17.

The paper feed tray 10 positions the paper with a center reference by moving the paper guide 12 in a bilaterally symmetric manner even if the paper size changes. The number of the paper feed rollers 13 is three, and the central paper feed roller 13 is arranged at a position where it is always in contact with the center of the paper. As shown in FIGS. 1 and 2, a spring 18 is provided on the outer peripheral surface of the sheet feeding roller 13 arranged in the center.
Paper retainer 20 urged by a support shaft 19 and rotatably held by a support shaft 19, and a support shaft 22 urged by a spring 21.
The sheet separating member 23 as a sheet separating member that is rotatably held by is pressed against. The surfaces of the paper pressing member 20 and the paper separating member 23 that come into contact with the paper feeding roller 13 are formed of elastic materials 24 and 25 such as cork having a relatively high friction coefficient.

Further, as shown in FIGS. 1 and 3, the paper feed roller 13 arranged on both the left and right sides is provided with a paper presser 27 biased by a spring 26 and rotatably held by the support shaft 19. Being touched. These paper retainers 27
Has the purpose of pressing the paper so as not to float from the paper feed roller 13, and is formed of plastic or metal having a low contact pressure with respect to the paper feed roller 13 and a low friction coefficient. A paper guide 28 is provided below the paper feed rollers 13 arranged on both the left and right sides.

Here, the frictional force generated between the paper feed roller 13 and the paper is set to the maximum value, and the frictional force generated between the elastic material 25 of the paper separating member 23 and the paper is the second largest. The frictional force generated between the sheets is set to the smallest value.

In such a structure, the paper retainers 20, 2
By bringing the paper sheet into contact with the three paper feed rollers 13 by 7, the center and both sides of the paper sheet can be pulled by the three paper feed rollers 13. As a result, the feeding power can be increased. Therefore, not only ordinary paper but also strong paper such as postcard, thick paper, continuous paper, or special paper such as heavy paper is used. It can be pulled out securely toward.

Accordingly, it is not necessary to press the paper separating member 23 against the single paper feeding roller 13 arranged in the center with an unnecessarily high pressure contact force to forcibly increase the paper feeding pressure. The paper separating member 2 to the paper feeding roller 13
3 can be pressed. As a result, even when a plurality of sheets of paper are overlapped and entered between the paper feed roller 13 and the paper separating member 23, the frictional force generated between the papers does not become too high. Therefore, the uppermost sheet is pulled out toward the photoconductor 2 by the sheet feeding roller 13 having a high friction coefficient, and the lowermost sheet is prevented from advancing by the frictional force generated between the sheet and the sheet separating member 23. Even when three or more sheets of paper are overlapped and entered, the uppermost sheet of paper pulled by the paper feed roller 13 is pulled out toward the photoconductor 2 while slipping with respect to the next layer of paper. As described above, since the sheet feeding roller 13 to which the sheet separating member 23 is pressed with a relatively high pressure for separating sheets is one sheet feeding roller 13 arranged in the center, the sheet feeding roller 13 at the center is separated. It is possible to reduce the difference in the resistance applied to the paper on both sides of. The paper retainers 27 on both the left and right sides prevent the paper from floating from the paper feed roller 13 and have a small resistance to the paper. Therefore, even if there is a difference in the pressure contact force of the paper retainer 27 with respect to the paper feed roller 13, it is negligibly small. Therefore, the sheet does not skew.

As shown in FIG. 4, the paper presser 27 may be brought into contact with the outer periphery of the lower part of the left and right paper feed rollers 13. In this case, when the sheet is to be admitted from above with a certain advancing angle with respect to the tangent line passing through the contact portion between the paper retainer 27 and the outer peripheral surface of the paper feed roller 13, the end of the paper retainer 27 is directed upstream. Accordingly, by forming the inclined surface 29 that inclines upward, it is possible to easily guide the paper between the paper retainer 27 and the paper feed roller 13.

According to the first aspect of the invention, one long paper feed roller is provided along the width direction of the paper sheet, and the paper sheet is pressed down at least at the central portion and both sides of the paper feed roller. The paper sheet separating member is pressed against the central portion of the paper feeding roller.

[0019]

The invention according to claim 1 is as described above.
The paper pressure can be increased by bringing the paper feed roller into contact with a wide area between the central portion of the paper sheet and the portions near both sides by the paper presser. Therefore, not only ordinary paper sheets, but also postcards, thick paper, etc. Even when using the special paper sheet, it can be reliably pulled out toward the desired paper feed destination. As a result, it is not necessary to press the sheet separating member arranged at the central position against the sheet feeding roller with a pressure force greater than necessary to forcibly increase the sheet feeding pressure, and the sheet feeding roller can be separated with appropriate pressure for sheet separation. The paper sheet separating member can be pressed to improve the paper sheet separating performance. Further, since the paper sheet separating member that is pressed against the paper feed roller with a relatively high pressure for separating the paper sheet is arranged at the central position facing the center of the paper sheet, the paper sheet separating members are disposed on both sides of the paper sheet separating member. It is possible to reduce the resistance given to the sheet and the difference between these resistances, and therefore, it is possible to prevent the skew of the sheet.

According to the second aspect of the present invention, as described above, the paper feeding force can be increased by bringing the paper sheet into contact with the three paper feed rollers by the paper presser. Therefore, even when a special sheet such as a postcard or a cardboard is used, it can be reliably pulled out toward a desired paper feed source. As a result, it is not necessary to press the paper sheet separating member against the single paper feeding roller arranged in the center with an unnecessarily high pressure contact force to increase the paper feeding pressure, and to feed the paper sheet with an appropriate pressure. The paper sheet separating member can be pressed against the paper roller to enhance the paper sheet separating performance. Further, by defining the paper feed roller to which the paper sheet separation member is brought into pressure contact with a relatively high pressure contact force for paper sheet separation as one paper feed roller arranged in the center, both sides of this central paper feed roller are determined. It is possible to reduce the resistance given to the paper sheet and the difference between those resistances, and thus to prevent the paper sheet from skewing.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention and showing a relationship among a sheet feeding roller, a sheet separating member, and a sheet retainer.

FIG. 2 is a side view showing a relationship among a central sheet feeding roller, a sheet separating member, and a sheet retainer.

FIG. 3 is a side view showing the relationship between the paper feed rollers on both sides and the paper retainer.

FIG. 4 is a side view showing another example of the paper retainer.

FIG. 5 is a vertical sectional side view showing the internal structure of the image forming apparatus.

[Explanation of symbols]

 13 Paper Feed Roller 20 Paper Presser 23 Paper Leaf Separation Member 27 Paper Presser

Claims (2)

[Claims] 1. A rotatable paper feed roller in which at least a central portion of the paper sheet and portions near both sides of the paper sheet come into contact with each other, a paper presser for pressing floating of the paper leaf from the outer periphery of the paper feed roller, and a downstream of the paper presser. And a sheet separating member elastically pressed against the outer peripheral surface of the sheet feeding roller with a desired pressure at a central position facing the central portion of the sheet. 2. An odd numbered paper feeding roller of three or more, which is arranged at a central position facing the central portion of the paper sheet and a symmetrical position about the central position, is rotatably provided coaxially, 2. The sheet feeding device according to claim 1, wherein a sheet separating member is elastically pressed against a peripheral surface of one of the sheet feeding rollers arranged in the center with a desired pressure.