JPH1129236A - Paper feeder - Google Patents

Abstract

(57) [Problem] To provide a paper feeding device capable of correcting generated skew each time without individually taking measures against skew factors. A swingable support arm is provided in a paper feed tray having a side fence, and a tension roller is supported at a free end of the support arm. The support arm 13 is provided with an elongated hole for supporting the tension roller 12, and a roller shaft 17 of the tension roller 12 is provided.
(23) can swing in that range. When the paper feed tray 6 is set in the apparatus main body, the free end side of the support arm 13 swings in a direction approaching the upper surface of the transfer paper 2, whereby the tension roller 12 abuts on both surfaces of the transfer paper 2, and its own weight To apply a load to the transfer paper 2. When the transfer paper 2 is fed by the pickup roller 3, the load becomes the back tension, and even if the skew occurs in the transfer paper 2, the transfer paper 2 is reliably corrected by the back tension.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder for an image forming apparatus having a paper feed mechanism, such as a copying machine or a printer. Paper feed tray having side fences to control the skew at the time, and a paper feed roller such as a pick-up roller located at the center of the leading end of the paper feed tray and located on the upper surface of the transfer paper, and a feed roller near the downstream side of the pick-up roller And a sheet feeder comprising:

[0002]

2. Description of the Related Art A paper feed tray having a side fence for positioning a side surface in the width direction of a transfer paper accommodated therein and regulating a skew at the time of paper supply, and a transfer paper at the center of the leading end of the paper feed tray. FIG. 8 shows a conventional example of a sheet feeding device including a pickup roller located on the upper surface of a sheet and feed rollers such as a feed roller near the downstream side of the pickup roller.

FIG. 8 is a plan view of a main part of a conventional sheet feeding device. The paper feed tray 6 is provided with a pair of side fences 14 and 14 for regulating both ends in the width direction of the transfer paper 2 and an end fence 15 for regulating the rear end of the transfer paper 2. Further, a pickup roller 3 is provided at a widthwise central portion of a leading end portion of the sheet feeding tray 6, a feed roller 4 is further provided downstream thereof, and a grip roller 10 is provided further downstream thereof.

As shown in FIG. 8, paper feed rollers such as a pick-up roller 3 and a feed roller 4 are often provided at a central portion in the width direction of the paper feed tray 6. In this case, a slight pressure deviation of the rollers, a difference in the resistance between the right and left sides of the transfer paper at the paper feed unit guide plate entry portion, or a μ deviation due to paper dust or the like causes a deviation in the conveyance direction of the rollers. It deviates from the ideal transport line and causes skew.

In FIG. 8, a skewed transfer sheet is indicated by a chain line. Generally, these irregular elements are prevented by restricting the transport direction to the normal direction by the side fence 14.

[0006]

However, for transfer paper having a small size and a small amount of engagement with the side fence (for example, A5 size paper, etc., especially a transfer paper which is passed in the horizontal direction), the above-described regulation effect is not obtained. Slightly, the sheet may come off the side fence due to the influence of the roller in the conveying direction during paper feeding, and skew may occur.

In the prior art, there is a technique for improving the difference in transport resistance between the left and right of the transfer sheet due to curling (Japanese Patent Laid-Open No. 3-293227) and a technique for improving the pressure distribution of the rollers (Japanese Utility Model Application Laid-Open No. 2-43839).
However, these are improved techniques that do not disturb the transport balance, and there is no way to cope with other disturbances.

SUMMARY OF THE INVENTION The present invention has been made in view of the fact that it is difficult to completely maintain the transport balance in an actual machine. An object of the present invention is to provide a sheet feeding device that can perform correction.

[0009]

According to a first aspect of the present invention, there is provided a side fence for positioning a side surface in a width direction of a transfer sheet housed therein and restricting a skew at the time of sheet feeding. And a feed roller such as a pick-up roller located at the center of the leading end of the feed tray and located on the upper surface of the transfer paper, and a feed roller near the downstream side of the pick-up roller. And a back tension applying means for applying a load to the transfer paper being fed and applying a back tension on the upper surface of the transfer paper on the upstream side in the transfer paper transport direction of the paper feed rollers. .

According to a second aspect of the present invention, in the first aspect of the present invention, the back tension applying means is constituted by a tension roller freely rotating in a transfer paper transport direction.

According to a third aspect of the present invention, in the second aspect of the present invention, the tension roller has its thrust position in the rotation axis direction regulated, and is wound around a surface thereof with a rubber having a high coefficient of friction with transfer paper. It is characterized by comprising.

According to a fourth aspect of the present invention, in the third aspect of the present invention, two or more tension rollers are provided coaxially and connected so that the respective tension rollers rotate simultaneously. Is what you do.

According to a fifth aspect of the present invention, in the third aspect of the invention, the tension rollers are provided on both sides in the width direction with the paper feed rollers interposed therebetween, and at least one tension roller is attached to the side fence. The transfer paper is provided so as to be inclined outward in the direction in which the transfer paper is pushed out.

According to a sixth aspect of the present invention, in the second aspect of the invention, the load on the transfer paper by the tension roller is applied by the weight of the tension roller.

According to a seventh aspect of the present invention, in the first aspect, the back tension applying means is configured to be movable between a back tension applying position and a release position. It is.

According to an eighth aspect of the present invention, in the seventh aspect of the present invention, the back tension applying means is interlocked with opening and closing of the sheet feeding tray, and is released upward when the sheet feeding tray is pulled out. It is.

[0017]

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

FIG. 1 is a configuration diagram of a sheet feeding device showing an embodiment of the present invention. The paper feeder, which is installed in a copying machine, is brought into and out of contact with the transfer paper 2 at a predetermined operation timing by a pickup solenoid (not shown), and the pickup roller 3 for feeding out the transfer paper 2 is fed out by the pickup roller 3. And a feed roller 4 for feeding the transferred transfer paper 2 toward the registration section of the apparatus body of the copying machine.

Further, as a separation method of this embodiment,
The transfer roller 2 is pressed into contact with the feed roller 4 with a predetermined torque.
A reverse separation method (FRR method) including a reverse roller 5 for separating the sheets one by one is adopted. Reference numeral 6 denotes a paper feed tray, and 7 denotes a bottom plate. The transfer paper 2 is placed on the bottom body 7, and the transfer paper is raised to a predetermined position by a pressure lever 9 coupled to a lifting motor (not shown). On the downstream side (front side) of the feed roller 4 in the transfer paper transport direction, a grip roller 10 for transporting the separately fed transfer paper and its driven roller 11 are provided.

The tension roller 12 as back tension applying means according to the present invention is rotatably supported by a support arm 13. The support arm 13 has an end opposite to the side supporting the tension roller 12 on the support shaft 1.
Since the tension roller 12 is swingably supported by the sheet feed tray 6 by the reference numeral 3a, the tension roller 12 can be brought into contact with and separated from the transfer sheet 2, and can be brought into contact with the transfer sheet 2 as necessary, and use the slot. An appropriate load (tension) is applied to the transfer paper 2 by its own weight.

In such a paper feeder, the transfer paper 2 loaded on the bottom plate 7 in the paper feed tray 6 has its upper surface pressed against the pickup roller 3 by a pressure lever 9 at a predetermined paper feed pressure. ing. When the pickup roller 3 rotates in this state, the transfer paper 2 is sent out in order from the top paper, and if there is a double feed at the nip portion between the feed roller 4 and the reverse roller 5, the transfer paper 2 is separated and conveyed one by one to the grip roller 10. Then, the sheet is conveyed to the registration unit by the grip roller 10. Hereinafter, an image is transferred onto the transfer sheet 2 as is well known, and the toner image is fixed while the transfer sheet 2 passes through the fixing device. Thereafter, the transfer sheet 2 is discharged to a discharge section.

FIG. 2 is a perspective view showing a state in which the paper feed tray shown in FIG. 1 is pulled out to the near side of the copying machine main body (apparatus main body). Inside the paper feed tray 6, there are a side fence 14 for regulating the horizontal position of the transfer paper and an end fence 1 for regulating the vertical position.
5. Further, the support arms 13 described above are provided in pairs.

Each of the support arms 13 is rotatably supported at one end on a side surface of the paper feed tray 6 by a support shaft 13a shown in FIG. It is pulled in the counterclockwise direction by the release spring 16 hooked on the anchor. An elongated hole is provided at the other end (free end) of the support arm 13, and a roller shaft 17 supporting the tension roller 12 is rotatably supported so as to be able to move up and down by the elongated hole. .

The paper feed tray 6 can be drawn out of the apparatus main body by a pair of rails 18 so that the transfer paper 2 can be supplied. A groove 19 provided on the lower surface of the tray storage unit on the apparatus body side protrudes from a notch hole 6a (described later) provided on the lower surface of the paper feed tray 6, and a claw portion 20 (described later) at the fulcrum end of the support arm 13 is provided. ), The tension roller 12 is released and set in conjunction with the opening and closing of the paper feed tray 6.

FIG. 3 is an explanatory diagram showing the position of the tension roller when the paper tray is pulled out, and FIG. 4 is an explanatory diagram showing the position of the tension roller when the paper tray is set. As shown in FIG. 3, when the paper feed tray 6 is pulled out, the support arm 13 is rotated counterclockwise by the release spring 16, and its claw portion 20 is formed in the notch hole 6 a on the lower surface of the paper feed tray 6. It is fixed using the edge as a stopper. In this state, the tension roller 12 is largely released upward and the bottom plate 7 is also released downward, so that the transfer paper 2 can be set well. Arrow A indicates transfer paper 2
Shows the setting direction of

On the other hand, as shown in FIG. 4, when the paper feed tray 6 is set and the transfer paper 2 is ready to be fed, the claw portion 20 has the straight portion 21 of the groove 19 (FIG. 2 also). (See FIG. 3), the tension roller 12 rides on the upper surface of the transfer paper 2 and the tension roller 12 is set at an appropriate position such that the tension roller 12 floats from the lower end of the slot. Fixed). With this configuration, a load of the tension roller 12 (more precisely, the roller shaft 17) is applied to the transfer paper 2 by its own weight F. Therefore, a constant load (between the papers) regardless of a change in the height of the transfer paper upper surface. If friction is μ,
μF), and a stable skew correction effect can be expected.

FIG. 5 is a plan view of the sheet feeder showing a state of skew correction by the tension roller of the first specific example.
Two tension rollers 12 attached to roller shaft 17
Is located outside the pickup roller 3 and the feed roller 4 in the width direction of the transfer paper. That is, it is provided so as to sandwich the paper feed rollers. By these two tension rollers 12,
The transfer paper 2 receives a tension B that is pulled backward during paper feeding. Since the tension B acts on the transfer paper 2 in such a direction as to always cancel the force of the paper feed rollers to bend the transfer paper 2, the skew is always corrected.

FIG. 6 is a perspective view showing an example of the tension roller. By winding a high friction member 22 such as rubber having a large μ with the transfer paper 2 on the surface of the tension roller 12 and fixing the thrust position on the roller shaft 17 of the tension roller 12, the transfer paper 2 It is difficult to move left and right on the contact surface.

Further, the tension rollers 12 are fixedly mounted on the roller shaft 17 so that each of the two tension rollers 12 shown in FIG. 5 rotates simultaneously, and the roller shaft 17 rotates together with the elongated hole of the support arm 13. With this configuration, there is no deviation in the feed amount of the transfer paper 2 on each tension roller 12.

With the above configuration, in addition to the skew correcting effect, the skew itself can be suppressed from occurring.

FIG. 7 is a plan view of the sheet feeding device showing a state of skew correction by the tension roller of the second specific example.
It should be noted that an engagement portion between the support arm and the roller shaft is shown in an enlarged manner. In FIG. 7, instead of making the amount of rotation of each tension roller 12 the same, instead of rotating the tension roller 12 in the direction shown in FIG. An example of attachment is shown.

In this case, the tension rollers 12 are supported so as to rotate individually on the roller shaft 23. In addition, as a matter of course, the receiving shape of the support arm 13 in the elongated hole portion is a rotation restricting shape such as an oval shape (the roller shaft 17 has a round cross section) so that the roller shaft 23 itself does not rotate.

With such a configuration, the transferred transfer paper 2 behaves so as to be stretched to both sides along the rotation direction of the tension roller 12 (arrow C), and is pressed against the side fence 14 to be pressed. The skew control effect of the side fence 14 is reliably obtained. Therefore, similarly to the specific example shown in FIG. 5, the skew itself can be hardly caused.

In the paper feeder according to the embodiment of the present invention, a support arm 13 swingable around a support shaft 13a is provided in a paper feed tray 6 having a side fence 14, and the free end of the support arm 13 is provided. The tension roller 12 is pivotally supported.
The support arm 13 is provided with an elongated hole for supporting the tension roller 12, and a roller shaft 17 of the tension roller 12 is provided.
(23) can swing in that range. When the paper feed tray 6 is set in the apparatus main body, the free end side of the support arm 13 swings in a direction approaching the upper surface of the transfer paper 2, whereby the tension roller 12 abuts on both surfaces of the transfer paper 2, and its own weight To apply a load to the transfer paper 2. When the transfer paper 2 is fed by the pickup roller 3, the load becomes the back tension, and even if skew occurs in the transfer paper 2, the transfer paper 2 is reliably corrected by the back tension. As described above, according to the present embodiment, the generated skew of the transfer paper 2 can be corrected each time.

[0035]

According to the first, second and fourth aspects of the present invention, since the back tension is applied to the transfer paper, the skew caused by the deviation in the transport direction (oblique feed) due to the paper feed rollers is reduced. Can be corrected.

According to the third aspect of the present invention, the skew correction effect is improved by wrapping a rubber having a high friction coefficient with the transfer paper on the surface of the tension roller to prevent the transfer paper from laterally shifting on the roller surface. Can be.

According to the fifth aspect of the present invention, in addition to the effect of improving the skew correction effect by applying back tension while the transfer paper is being fed, the transfer roller is provided at an angle such that the tension roller pushes out the transfer paper. Therefore, by pressing the transfer paper end against the side fence, it is possible to obtain an effect of positively correcting the skew at the side fence. This is effective when the transfer paper is not always in contact with the side fence such as curled paper.

According to the sixth aspect of the present invention, since the load is applied by the weight of the tension roller, the transfer paper loading height,
A constant load determined by the sheet interval μ can be applied regardless of the number of sheets. Therefore, a stable skew correction effect can always be obtained.

According to the seventh and eighth aspects of the present invention, since the back tension applying means is released upward when the paper feed tray is pulled out, there is an effect that the setting property of the transfer paper is not impaired.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which a sheet feeding tray shown in FIG. 1 is pulled out to a front side of a copying machine main body.

FIG. 3 is an explanatory diagram showing a position of a tension roller when a paper feed tray is pulled out.

FIG. 4 is an explanatory diagram showing a position of a tension roller when a sheet feeding tray is set.

FIG. 5 is a plan view of the sheet feeding device showing a state of skew correction by the tension roller of the first specific example.

FIG. 6 is a perspective view showing an example of a tension roller.

FIG. 7 is a plan view of a sheet feeding device showing a state of skew correction by a tension roller according to a second specific example.

FIG. 8 is a plan view of a main part of a conventional sheet feeding device.

[Explanation of symbols]

 2 Transfer Paper 3 Pickup Roller 4 Feed Roller 5 Reverse Roller 6 Paper Feed Tray 7 Bottom Plate 9 Pressure Lever 10 Grip Roller 11 Follower Roller 12 Tension Roller 13 Support Arm 13a Support Shaft 14 Side Fence 15 End Fence 16 Release Spring 17 Roller Shaft 22 High friction members

Claims (8)

[Claims] 1. A sheet feed tray having a side fence for positioning a side surface in a width direction of a transfer sheet accommodated therein and restricting a skew at the time of sheet feed, and a transfer sheet located at the center of the front end of the sheet feed tray. In a paper feeding device including a pickup roller located on the upper surface of the paper and paper feed rollers such as a feed roller near the downstream side of the pickup roller, A sheet feeding device comprising a back tension applying means for applying a load to a transfer sheet being fed and applying a back tension. 2. The sheet feeding device according to claim 1, wherein the back tension applying unit is configured by a tension roller that freely rotates in a transfer sheet conveying direction. 3. The feeding roller according to claim 2, wherein the tension roller has a restricted thrust position in the rotation axis direction, and is formed by winding rubber having a high coefficient of friction with transfer paper on the surface. Paper equipment. 4. The sheet feeder according to claim 3, wherein two or more tension rollers are provided coaxially and connected so that the respective tension rollers rotate simultaneously. 5. The tension roller according to claim 3, wherein the tension rollers are provided on both sides in the width direction with the paper feed rollers interposed therebetween, and at least one tension roller is provided in a direction in which the transfer paper is pushed and spread on the side fence. A sheet feeding device provided to be inclined in a direction. 6. The paper feeder according to claim 2, wherein the load on the transfer paper by the tension roller is applied by the weight of the tension roller. 7. The sheet feeding device according to claim 1, wherein the back tension applying means is configured to be movable between a back tension applying position and a release position. 8. The sheet feeding device according to claim 7, wherein the back tension applying means is linked with opening and closing of the sheet feeding tray, and is released upward when the sheet feeding tray is pulled out.