JPH0925025A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stable paper feeding motion according to paper size with a skew prevention member whose structure is simplified. SOLUTION: This paper feeding device is provided with a tray 1 for storing paper P, side fences 11a, 11b and a back fence 12 for guiding the side and rear end of paper P stored in the tray 1 respectively, and a paper feeding roll train consisting of a delivery roll 20, a feed roll 21, and a conveyance roll 22. A skew prevention member 30 protruding onto the paper P is movably-fitted onto the side fence 11a along the side fence 11a on the side where the paper P lifts by skew generation. A skew prevention member 30 is disposed on the rear end located farthest from the deliver roll 20 within a skew generation range L to restrain skew most effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
The present invention relates to a paper feeding device provided in an image forming apparatus such as a laser printer, and more particularly, to a paper feeding device in which a method for providing a skew prevention member used therein is improved.

[0002]

5 and 6 show an example of this type of sheet feeding device. This paper feeding device is composed of a cassette type tray 1 that is detachably set in the main body of an image forming apparatus such as a printer, and a paper feed roll group 2 provided on the main body side of the image forming apparatus. The tray 1 accommodates a large number of stacked sheets P substantially horizontally, and the paper feed roll group 2 pulls out the sheets P from the tray 1. FIG.
The arrow A in FIG. 6 indicates the paper feeding direction, and the paper feed port 10 is formed at the front end of the tray 1 in the paper feeding direction. The tray 1 is provided with a pair of side fences 11 that guide the side surfaces of the paper P and a back fence 12 that guides the rear end surface of the paper P in the paper feeding direction.
The paper feed roll group 2 is composed of a delivery roll 20, a feed roll 21, and a transport roll 22 which are arranged at predetermined intervals along the paper feed direction. These rolls 20,
21 and 22 are arranged on one side of the center line 1 of the sheet P in the sheet feeding direction (in this case, on the left side in the sheet feeding direction).

This paper feeding device has a large number of stacked paper sheets P.
When the sheets are neatly housed in the tray 1 while being guided by the fences 11 and 12, and the paper is fed, the delivery roll 20 first
A sheet of paper P is sent out from the paper feed port 10 of the tray 1 and then passed through a feed roll 21, and then a conveyance roll 22 supplies the main body of the image forming apparatus.

Each roll of the paper feed roll group 2 rotates in the direction of the arrow shown in FIG. 2 and feeds the paper P by the frictional force generated by pressing the paper P. To describe these rolls in detail, the delivery roll 20 is arranged on the paper P, and delivers the uppermost paper P from the paper feed port 10 of the tray 1 to the outside. The feed roll 21 is composed of an upper forward roll 21a and a lower reverse roll 21b, and feeds the paper P fed between the rolls 21a and 21b to the transport roll 22. In particular, the feed roll 21 has a function of, when a plurality of sheets P sent out by the delivery roll 20 become a plurality of sheets at the same time, separating the sheets P one by one from the uppermost sheet P to the transport roll 22. Fulfill The transport roll 22 is composed of a pair of upper and lower forward rotation rolls 22a, and supplies the sheet P fed between these rolls 22a to the main body as described above.

By the way, for the paper P, the paper feed roll group 2
If the frictional force is not applied with an appropriate force, a rotational moment is generated in the direction indicated by the arrow B in FIG. 5, and the paper P is distorted or twisted with respect to the paper feeding direction, so-called “skew”. Occurs. The chain double-dashed line in FIG. 5 indicates the sheet P in a skewed state. Each roll 20, 21, 2
Of the two, the feed roll 20 and the feed roll 21 have relatively unstable frictional forces for holding the paper P, and therefore skew occurs when the two rolls 20 and 21 on the front side are fed.

Therefore, as a technique for preventing the occurrence of such a skew, one side fence provided with a member for preventing the floating of the sheet or the overcoming of the side fence is disclosed in Japanese Utility Model Laid-Open No. 64-537. It is known from Japanese Utility Model Publication No. 1-12103. Further, in Japanese Utility Model Laid-Open No. 3-31136, a skew prevention roll is arranged on the front side of the delivery roll, and the skew prevention roll is rotated at the same peripheral speed as the delivery roll.
A sheet feeding device is described in which both rolls cancel out the skew force to each other to prevent skew.

[0007]

In the former technique described above,
Since the skew prevention member is fixedly provided on the side fence, the length on which the skew prevention member acts differs depending on the size of the paper, that is, the length in the paper feeding direction. The length on which the skew prevention member acts is the distance between the skew prevention member and the trailing end surface of the sheet guided by the back fence in the sheet feeding direction. For this reason, there is a large difference in the skew prevention capability depending on the size of the sheet, and stable sheet feeding cannot be performed. Such an inconvenience can be solved by providing a skew prevention member over the entire length of the side fence, but with such a configuration, the skew prevention member becomes a hindrance when replenishing paper to the tray. Therefore, for example, a means for temporarily retracting the skew prevention member is required, resulting in a complicated device.

On the other hand, in the latter technique, that is, in which the skew prevention roll is arranged in front of the delivery roll,
The anti-skew roll must be driven to rotate at the same peripheral speed as the delivery roll. For this reason, the device is complicated and the number of parts is increased, which is unavoidable in terms of cost.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a sheet feeding apparatus which can obtain a stable sheet feeding operation corresponding to a sheet size without complicating the apparatus.

[0010]

As a means for achieving the above-mentioned object, the present invention stores a sheet substantially horizontally and has a tray having a sheet feeding port at the front end in the sheet feeding direction, and a sheet to be accommodated in the tray. Side fences and back fences that respectively guide the side and rear end faces in the paper feed direction, a feed roll that feeds the paper stored in the tray to the outside of the tray from the paper feed port, and conveys the paper fed by the feed roll to a specified device. And a side fence with a skew prevention member provided in a state of protruding on the paper,
It is characterized in that the skew preventing member is provided so as to protrude on a part of the sheet and is movable along the side fence.

(Operation) According to the paper feeding device of the present invention, since the skew prevention member moves along the side fence,
The skew prevention member can be arranged within the range in which the skew occurs depending on the size of the sheets accommodated in the tray. When a skew occurs, the sheet hits the side fence and tries to float up and climb over the sheet, but the movement is blocked by the skew prevention member and the skew is suppressed. The skew can be effectively suppressed without requiring a complicated structure, and the skew preventing member does not get in the way when the paper is replenished in the tray.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) Configuration of Embodiments Each embodiment of the present invention will be described below with reference to FIGS. 1 to 4. These embodiments are configured as a paper feeding device that is incorporated in an image forming apparatus such as a printer and supplies paper to the apparatus main body.

A. First Embodiment-FIG. 1 [Structure of First Embodiment] FIG. 1 shows a sheet feeding device according to a first embodiment of the present invention. Reference numeral 1 is a cassette type tray for storing a sheet P, and 2 is a sheet tray. Is a paper feed roll group. The tray 1 and the paper feed roll group 2 have the same configuration as that shown in FIGS. That is, the tray 1 accommodates a large number of stacked sheets of paper P substantially horizontally and is set in the image forming apparatus main body. A paper feed port 10 is formed at the front end of the tray 1 in the paper feed direction indicated by arrow A, and further, a pair of side fences 11 for guiding the side surfaces of the paper P and a rear end surface of the paper P in the paper feed direction are guided. The back fence 12 and each are provided. Side fence 11 is tray 1
The tray 1 on the left side in the sheet feeding direction, which also serves as the side wall, extends over the entire length of the tray 1 and the short side on the right side.
Here, the left and right sides are side fences 11
Reference numerals are respectively assigned to a and 11b.

On the other hand, the paper feed roll group 2 provided in the main body of the image forming apparatus includes a delivery roll 20 for pulling out the uppermost paper P in the tray 1 from the paper feed port 10 to the outside, and then the paper P is surely 1 It is composed of a feed roll 21 that works so as to be fed sheet by sheet, and a carrying roll 22 that finally carries the paper P to the image forming apparatus. The feed roll 21 is formed by combining an upper forward rotation roll 21a and a lower reverse rotation roll 21b (see FIG. 6) which is not visible in FIG. 1, and the transport roll 22 is a pair of upper and lower forward rotation rolls 22.
a is a combination. Each roll 20, 21,
The sheets 22 are arranged on one side of the center line 1 of the sheet P in the sheet feeding direction (in this case, on the left side in the sheet feeding direction).

In the sheet feeding device of this embodiment, in addition to the above basic structure, the skew preventing member 30 is provided on one side fence 11a. The skew prevention member 30 is a thin plate piece having an extremely small size as compared with the paper sheet P and a length of, for example, about 1/10 of the side fence 11a and having an L-shaped cross section. The skew prevention member 30 is provided on the side fence 11a so as to project above the sheets P stored in the tray 1. The skew prevention member 30 is provided on the side fence 11a so as to be movable along the side fence 11a and to be held at an arbitrary position by a mounting means such as a screw.

The skew prevention member 30 is arranged at a constant distance from the rear end surface of the paper P stored in the tray 1 in the paper feeding direction, that is, the inner surface of the back fence 12. The distance is at least the distance from the paper feed port 10 which is the front end surface of the paper P in the paper feed direction to the carry-out roll 22 (see FIG. 1).
(Indicated by L) is secured. In other words, the installation position of the skew prevention member 30 is set to an arbitrary position on the side of the paper feed port 10 from the point separated by the distance L from the inner surface of the back fence 12. The position of the carry-out roll 22 is a portion of the nip where a frictional force for feeding the paper P is exerted.

[Operation and Effect of First Embodiment]
Next, operations and effects of the sheet feeding device of the first embodiment will be described. First, a large number of stacked sheets P are guided and guided in the tray 1 by the side fences 11a and 11b and the back fence 12, and the tray 1 is set at a predetermined position of the image forming apparatus main body. By setting in this way, the delivery rolls 2 of the paper feed roll group 2
0 is placed on the front end of the sheet P in the sheet feeding direction, and the sheet feeding port 2 faces the feeding path of the sheet feeding roll group 2.

Subsequently, when feeding paper, each roll of the paper feed roll group 2 is rotationally driven in the direction shown by the arrow in FIG. When the paper feed roll group 2 rotates in this manner, the delivery roll 20 first feeds the uppermost paper P from the paper feed port 10 of the tray 1 to the outside. Subsequently, the feed roll 21 receives the front end portion of the paper P in the paper feed direction, passes the paper P between the forward rotation roll 21a and the reverse rotation roll 21b, and feeds it to the transport roll 22. Here, when the delivery roll 20 delivers a plurality of sheets P at the same time,
By the action of the forward rotation roll 21a and the reverse rotation roll 21b whose rotation directions are opposite to each other, the plural sheets of paper P are separated and sent one by one from the uppermost paper P to the transport roll 22. The transport roll 22 receives the paper P from the feed roll 21 and supplies it to the main body of the image forming apparatus by the upper and lower forward rotation rolls 22a.

By repeating the above operation, a plurality of paper P
Are fed one by one from the tray 1 to the image forming apparatus main body. Next, the operation when the paper sheet P is skewed during the paper feeding will be described. Since the paper feed roll group 2 is biased to the left side of the paper P, the skew is
The rear end portion is generated so as to rotate toward the side fence 11a. Therefore, when this skew occurs, the sheet P hits the left side fence 11a, floats up, and tries to get over it. However, the movement is blocked by the skew prevention member 30, and the skew is suppressed.

The skew is generated when the paper P is conveyed by the transport roll 2
It occurs as described above until the number reaches 2. As for the installation position of the skew prevention member 30 on the side fence 11a, a position where the movement distance L from the back fence 12 to at least the carry-out roll 22 of the paper P is set is secured. That is, since the skew prevention member 30 exists in the range L where the skew occurs, the skew can be suppressed. Since the skew is generated by the rotational moment of the feed roll 20 or the feed roll 21, the skew suppressing force is greatly exerted at positions as far as possible from the rolls 20 and 21. The position farthest from the rolls 20 and 21 within the skew occurrence range is as shown in FIG.
As shown in FIG. 5, the moving distance L from the back fence 12 to the carry-out roll 22 on the front end surface of the paper P is set, and the installation position of the present embodiment is most effective.

According to the first embodiment of the present invention described above, since the installation position of the skew prevention member 30 with respect to the side fence 11a can be arbitrarily set, the skew prevention member is placed at the optimum skew prevention position according to the size of the paper P. 30 can be arranged. As a result, it is possible to reliably suppress the occurrence of skew and perform stable paper feeding. Further, the skew prevention member 30 is small enough to project to a part on the paper P, and coupled with being provided so as to be movable along the side fence 11a, the skew prevention member 30 becomes an obstacle. Paper P without
It is possible to perform the replenishment work, and much less means for temporarily retracting the skew prevention member 30. Therefore, the apparatus is not complicated and the cost is not increased.

B. Second Embodiment-FIG. 2 [Configuration of Second Embodiment] FIG. 2 shows a sheet feeding device according to a second embodiment of the present invention. In this paper feeding device, the skew prevention member 30 shown in the first embodiment is used.
Is added by the motor 40. The motor 40 is located below the tray 1 and on the side fence 1
It is arranged in the front near 1a and is fixed to the tray 1 via a bracket or the like (not shown). A drive shaft (not shown) of the motor 40 extends to the tray 1 side orthogonal to the tray 1, and a pinion gear 41 is mounted on the drive shaft.
A rack 42 that is parallel to the side fence 11a and extends forward in the sheet feeding direction is attached to the skew prevention member 30. The rack 42 and the pinion gear 41 of the motor 40 mesh with each other.

[Operation and Effect of Second Embodiment]
According to the second embodiment, the motor 40 operates and the pinion gear 40 rotates, so that the rack 42 moves along the sheet feeding direction, and the skew prevention member 30 is integrally formed with the rack 42 and the side fence 11a. Move along. The skew prevention member 30 can be moved by the motor 40, and further, the skew prevention member 30 can be held at that position by stopping the operation of the motor 40. Then, the tray 1 is not only moved by the motor 40 as described above.
The size of the sheet accommodated in the sheet is recognized by, for example, a method of determining the position of the back fence 12 of the sheet, and automatic control such as moving the skew prevention member 30 by the motor 40 to a position most suitable for the size of the sheet is performed. It is possible. By providing such automatic control means, it becomes possible to easily and surely arrange the skew prevention member 30 at a constant position from the back fence 12.

C. Third Embodiment-FIG. 3 [Configuration of Third Embodiment] FIG. 3 shows a sheet feeding device according to a third embodiment of the present invention. In this paper feeding device, the skew prevention member 30 shown in the first embodiment is used.
Is movable along the side fence 11a, and the back fence 12 is movable in the paper feeding direction and the opposite direction (front-back direction), and both are interlocked.

The back fence 12 is provided with respect to the tray 1.
It is provided so as to be movable at least in a range corresponding to the size of the paper P stored in the tray 1. The back fence 12 is provided with a rack 50 that is parallel to the side fence 11a and extends forward in the sheet feeding direction. On the other hand, a rack 51 that is parallel to the rack 50 and extends rearward in the sheet feeding direction is attached to the skew prevention member 30. A pair of gears 52 and 53 that mesh with each other and mesh with the racks 50 and 51 are interposed between the racks 50 and 51. These gears 52, 5
3 is pivotally supported by the tray 1.

Each rack 50, 51 and each gear 52, 5
3 is configured as an interlocking mechanism (holding means) 54 that always keeps a constant distance between the back fence 12 and the skew prevention member 30 by interlocking them.
The interlocking mechanism 54 is provided below the tray 1. The interlocking ratios of the skew prevention member 30 and the back fence 12 are set to be equal to each other. The distance between the skew prevention member 30 and the back fence 12 is set to the optimum distance described in the first embodiment, that is, the distance from the front end surface of the paper P to the carry-out roll 22.

[Operation and Effect of Third Embodiment]
When the paper P is stored in the tray 1, the back fence 1 is configured so that the rear end surface of the paper P contacts the inner surface of the back fence 12.
Move 2 back and forth. Then, the rack 50 moves together with the back fence 12, the gears 52 and 53 rotate in mutually opposite directions, and the rack 51 moves in the direction corresponding to the rotation direction of the gear 53, that is, the same direction as the moving direction of the back fence 12. The skew prevention member 30 also moves integrally with the rack 51, and therefore the back fence 1
Simultaneously with the movement of 2, the skew prevention member 30 moves in the same direction by the same distance.

According to the sheet feeding device of the third embodiment, even if the back fence 12 is moved according to the size of the sheet P, the interlocking mechanism 54 keeps the distance between the back fence 12 and the skew prevention member 30. It is always kept constant. As a result, the function of the skew prevention member 30 is properly exerted according to the size of the paper P.

D. Fourth Embodiment-FIG. 4 [Configuration of Fourth Embodiment] FIG. 4 shows a sheet feeding device according to a fourth embodiment of the present invention. In this paper feeding device, the back fence 12 is movable together with the skew prevention member 30 as in the third embodiment, and the interlocking mechanism 5 is used.
In place of 4, the both are integrally connected by a connecting plate (holding means) 60. The connecting plate 60 is an L-shaped plate material in a plan view, is arranged below the tray 1, and is provided at both ends thereof.
The skew prevention member 30 and the back fence 12 are fixed.

[Operation and Effect of Fourth Embodiment]
According to the fourth embodiment, as in the third embodiment, when the back fence 12 is moved according to the size of the sheet P, the skew prevention member 30 together with the back fence 12 have the same distance in the same direction. The distance between the two is always kept constant. As a result, the function of the skew prevention member 30 is properly exerted according to the size of the paper P.

E. Modifications The present invention is not limited to the above embodiments, and various modifications can be made. For example, although one skew prevention member 30 is provided in each embodiment, two or more skew prevention members 30 may be provided. In the case of providing a plurality of sheets in this way, it is desirable that the work of replenishing the paper P to the tray 1 is not hindered.

Further, in the second and third embodiments, the skew prevention member and the back fence are moved by the combination of the rack and the gear, but other movement transmission means such as the combination of the timing belt and the pulley is used. Can be used. Further, although the connecting plate 60 of the fourth embodiment is an L-shaped plate material, this is merely an example, and any shape and member may be used as long as they can be connected. In each of the above embodiments,
The present invention is applied to a cassette type paper feeding device in which the tray is detachably set in the apparatus main body. In addition to this, the tray is provided in the apparatus main body and the paper is directly stored in the tray and supplied. It is also applicable to a paper feeding device of the type.

[0033]

As described above, according to the sheet feeding device of the first aspect of the present invention, the sheet is accommodated substantially horizontally and the tray having the sheet feeding port at the front end in the sheet feeding direction is accommodated in the tray. Side fences and back fences that guide the side and rear end surfaces of the paper in the paper feed direction, a feed roll that feeds the paper stored in the tray to the outside of the tray from the paper feed opening, and a paper that is fed by the feed roll by a predetermined device. In a sheet feeding device provided with a transport roll for transporting to a sheet and a skew prevention member provided on a side fence so as to project onto the sheet, the skew prevention member is projected on a part of the sheet and extends along the side fence. Since the skew prevention member that moves along the side fence is provided according to the size of the paper stored in the tray, Can be arranged within a range to live, so that exhibits the complicated and it occurrence of skew without causing a cost rise can be suppressed reliably with effects such as stable sheet feeding can be performed was with the device.

According to a second aspect of the present invention, in the sheet feeding device according to the first aspect, the skew prevention member is
Since the front end of the paper sent out from the paper feed port of the tray is arranged at the rear end of the paper when it reaches the carry-out roll, the skew prevention member is always arranged within the range where skew can occur. , The power to suppress skew is most effective depending on the size of paper.

In the paper feeding apparatus according to the third aspect of the present invention, the back fence is provided so as to be movable in the paper feeding direction and the opposite direction, and the skew prevention member is always held at a position spaced a certain distance from the back fence. Since the holding means is provided, a stable skew preventing action can be obtained regardless of the size of the paper.

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment of the present invention.

FIG. 2 is a plan view of a second embodiment of the present invention.

FIG. 3 is a plan view of a third embodiment of the present invention.

FIG. 4 is a plan view of a fourth embodiment of the present invention.

FIG. 5 is a plan view showing a general example of a conventional paper feeding device.

FIG. 6 is a side view of a paper feed roll group and its periphery.

[Explanation of symbols]

1 ... Tray, 2 ... Paper feed roll group, 10 ... Paper feed port, 11
a, 11b ... Side fence, 12 ... Back fence,
20 ... Sending roll, 21 ... Feed roll, 22 ... Conveying roll, 30 ... Skew preventing member, 54 ... Interlocking mechanism (holding means), 60 ... Connecting plate (holding means).

Claims (3)

[Claims] 1. A tray that stores paper in a substantially horizontal direction and has a paper feed opening at a front end in the paper feed direction, and a side fence and a back that respectively guide a side face and a rear end face in the paper feed direction of the paper stored in the tray. A fence, a feed roll that feeds the paper stored in the tray to the outside of the tray from the paper feed port, a feed roll that feeds the paper fed by the feed roll to a predetermined device, the side fence, and the A skew prevention member provided in a state of protruding on the paper, the skew prevention member is projected on a part of the paper,
Further, the sheet feeding device is provided so as to be movable along the side fence. 2. The skew prevention member is arranged at a rear end portion in the paper feed direction of the paper fed from the paper feed port in a state where the front end in the paper feed direction reaches the carry-out roll. The sheet feeding device according to claim 1, wherein 3. The back fence is provided so as to be movable in the paper feeding direction and the opposite direction, and the skew prevention member is moved in accordance with the movement of the back fence.
2. The sheet feeding device according to claim 1, further comprising a holding unit that always holds the skew prevention member at a position spaced a certain distance from the back fence.