JPH09208058A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate malfunction caused by paper curling with minimum driving force without degrading ease of the operation of a device, by fitting a height variable guide member at both sides of the end of a paper feeding deck except the central part in the paper feeding direction. SOLUTION: It is assumed that a convex curl exists at both sizes of paper in the orthogonal direction to paper feeding direction R lower than the center. Cams 15, 16 are rotated toward the highest position from the lowest position by a variable motor 14, a worm gear 20, a worm wheel 19 and a driving shaft 17. During this operation, the back surfaces of guide plates 4, 5 are brought into contact with the peripheral parts of cams 15, 16, and the guide plates 4, 5 are pushed up from the original positions. Both the sides of a paper end positioned at the upper parts of the guide plates 4, 5 are lifted up by a change in rotational angle θ as a result of moving guide plates 4, 5 upward. As a result, a difference in height between the central part and both the sides of paper on the top end of 2A side of the paper feeding deck reduces, therefore, it is possible to correct curling at the paper end is straightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device provided with a variable guide member on a sheet feeding table on which sheets are stacked.

[0002]

2. Description of the Related Art In a sheet feeding device for feeding sheets loaded on a sheet feeding table to an image forming section or the like, a large amount of sheets are generally stacked on the sheet feeding table, and especially, the sheets are thin paper or thin paper. If the paper is stacked above, the curl (warpage) of both sides of the paper with respect to the paper feeding direction is promoted as the paper is stacked higher, and both sides of the paper are caught in the entrance portion of the paper feed guide plate during paper feeding, resulting in poor paper feeding. Paper breaks and jams may occur. Therefore, various curl correction (correction) mechanisms for the sheets stacked on the sheet feed tray have been proposed. For example, Japanese Unexamined Patent Publication No. 3-95029 discloses a sheet feeding device in which a portion of a sheet feeding table facing a sheet feeding roller is higher than both ends of the sheet feeding table.
Japanese Patent No. 7029 discloses a sheet feeding device that divides a sheet feeding table into three parts in a direction orthogonal to the sheet feeding direction and changes the height of the dividing part to correct the curl of sheets stacked on the sheet feeding table. Proposed. Further, Japanese Patent Application Laid-Open No. 62-222971 discloses a device that corrects the curl of a sheet stacked on a sheet feeding table by a curl correcting member.

[0003]

However, Japanese Unexamined Patent Publication No. Hei.
In the sheet feeding device described in Japanese Patent Publication No. 95029, the portion of the sheet feeding table facing the sheet feeding roller is made higher than both ends, so that the central portion of the sheets stacked on the sheet feeding table has a convex curl to some extent. In this case, it is possible to correct the escape and curl of the sheet downward, and to feed the sheet while maintaining a good contact state between the sheet feeding roller and the sheet. However, if the paper curls largely and floats from the paper feed table, or if there is a difference in height between the curls on both sides of the paper, there is a risk that the paper may be skewed due to a load when passing through the paper feed guide plate.

In the paper feeding apparatus described in Japanese Patent Laid-Open No. 7-247029, the paper feeding table is divided into three parts and the height of each of the divided parts is changed. Therefore, the driving mechanism and the driving force of the divided parts are increased. This tends to increase the size of the device and increase the cost.

In the paper feeding device disclosed in Japanese Patent Laid-Open No. 62-222971, since the curl generated on the paper is corrected by pressing the curl correcting member, the paper feeding drive system may be loaded when the paper is fed. , The degree of adhesion between stacked sheets increases,
There is a concern that the paper may not be fed or may be stacked.

According to the present invention, a feeding failure such as a feeding failure, a paper break, or a jam caused by a curl of a sheet loaded on the sheet feeding table is prevented from impairing the operability of the apparatus and the driving force is minimized. It is intended to be solved in.

[0007]

In view of the above, according to the present invention, in a sheet feeding device for feeding sheets stacked on a sheet feeding table, the leading edge of the sheet feeding table excluding the central portion located on the sheet feeding direction side. Height-adjustable guide members are provided at both ends.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The paper feeding device of the present invention is provided with variable height guide members at both ends of the leading end of the paper feeding table on which paper is stacked, excluding the central portion located on the paper feeding direction side. Provided,
The paper on the paper feed tray is fed to the image forming unit of the image forming apparatus by the paper feed separating unit having the double feed preventing unit and the feed guide member. When the type and size of paper or the number of stacked paper sheets is input to the image forming apparatus, the height of the guide member is set according to the conditions preset in the image forming apparatus. Therefore, the height of the guide member is automatically adjusted according to the type and size of the paper, and the curl of the paper is corrected.

Further, the height of the guide member is based on the detection information from the height detecting means for detecting the height of the entire leading edge of the stacked sheets, and the height difference between the central portion and both side portions of the leading edge of the sheet is determined. You may control so that it may be lost. In this case, since the curl of the stacked sheets of paper itself is detected, it is possible to cope with the degree of curl of the sheet due to environmental changes (temperature, humidity, etc.) around the apparatus without performing a special operation.

The height difference between the center and both sides of the leading edge of the stacked sheets is detected for each number of sheets fed or the time interval preset in the image forming apparatus, and based on the detection result, the leading edge of the stacked sheets is detected. If the height of the guide member is corrected and controlled so as to eliminate the difference in height between the central portion and both side portions, the curl of the sheet is corrected at the set intervals and the number of fed sheets regardless of the number of stacked sheets.

Further, when the guide member is controlled to return to the same height as the paper feed table when the paper feed table is lowered, there is no difference in height between the paper feed table and the guide member when the paper feed table is lowered. This is effective in reducing the breakage or catching of the paper due to the guide member when the paper is replaced.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. First Embodiment A sheet feeding apparatus indicated by reference numeral 1 in FIG. 1 includes a sheet stacking section A having a sheet feeding table 2 for stacking sheets P, and a double feed preventing unit for feeding the sheets P to an image forming section described later. The sheet P is fed by the sheet feeding / separating unit B and the feeding guide member 3 that are provided. At both ends 2B and 2C of the front end 2A of the paper feed table 2, variable guide members 4 and 5 which are the features of the present invention are arranged.

The sheet stacking section A is provided with an elevating means (not shown) for raising and lowering the sheet feeding table 2 toward the sheet feeding and separating section B, and the sheet P on the sheet feeding table 2 is fed to the sheet feeding and separating section B. It is designed to be in close proximity.

The paper feed separating section B includes a paper feed roller 8 and a paper feed arm 6 which are rotatably supported by a shaft 7 provided on the paper feed arm 6.
Separation roller 1 provided on a drive shaft 9 which is rotatably supported by both ends 6a and 6b of the shaft and driven by a drive mechanism (not shown).
0 and a separating member 11. The paper feed roller 8 and the separation roller 10 are rotatable in the same direction by a belt 10A wound around pulleys (not shown) provided on the shaft 7 and the drive shaft 9. The paper feed roller 8 is arranged above the central portion of the paper feed tray 2 on the side of the tip 2A, and the separation roller 10 is located on the downstream side of the paper feed roller 8 in the paper feed direction indicated by the arrow R, and is a slope 3a of the feed guide member 3. Is located above. Separation member 11
Is provided on the slope 3a facing the separation roller 10 so as to contact the separation roller 10, and the paper P fed by the paper feed roller 8 is sandwiched between the separation roller 10 and It is functioning to prevent double feed. The separating roller 10, the separating member 11, the feeding guide member 3 and the like constitute a double feeding preventing unit.

The guide members 4 and 5 are provided on the upper surface 2a of the paper feed table 2.
It is supported so as to be openable and closable by an appropriate means such as a hinge.
As shown in FIG. 2, both ends of springs 21 and 22 are fixed to the back surfaces of the guide members 4 and 5 and the paper feed tray 2, respectively, and the guide members 4 and 5 are moved toward the closing direction indicated by the arrow a. I am biased. The guide members 4 and 5 are normally placed at a reference position on the same plane as the upper surface 2a, and are driven by the guide varying means 12 according to the state of the paper P to correct the curl of the paper P.

The guide changing means 12 rotates the cams 15 and 16 fixed to the drive shaft 17 by the variable motor 14 fixed to the bracket 13 provided inside the paper feed table 2 to move the guide members 4 and 5 in the vertical direction. It can be rotated. The variable motor 14 is a deceleration motor and is under the control of the control means 33 described later.

The drive shaft 17 is a side plate 2b, 2c of the paper feed table 2.
Is rotatably supported by bearings 18A and 18B, and a worm wheel 19 is fixed to the central portion. The worm wheel 19 is meshed with a worm gear 20 that is fitted into the output shaft 14 a of the variable motor 14. The variable motor 14 transmits its rotation to the drive shaft 17 via the worm gear 20 and the worm wheel 19.

The cams 15 and 16 are circular plates and are eccentrically attached to the drive shaft 17 as shown in FIG. 3 (FIG. 3 shows only one). Cam 1
5, 16 are separated from the guide members 4, 5 when they are at the lowermost position shown by the two-dot chain line in FIG. 3, and contact with the guide members 4, 5 when they are at the neutral position shown by the one-dot chain line. , The upper surface 2 of the guide members 4 and 5 at the uppermost position shown by the solid line.
It is set so that the rotation angle θ between the guide members 4 and 5 and the upper surface 2a is maximized when lifted from a. Upper end portions 2b1 and 2c of the side plates 2b and 2c located on the tip 2A side
1 is formed in a flat surface such that when the guide members 4 and 5 are placed, the upper surfaces of the guide members 4 and 5 and the upper surface 2a are flush with each other.

The sheet feeding device 1 is applied to an image forming apparatus. In this embodiment, the description will be continued below assuming that the image forming apparatus is the stencil printing apparatus 30 shown in FIG. The stencil printing device 30 mainly includes an image forming unit C that forms a print image on the paper P fed from the paper feeding device 1, and a paper ejection tray 31 that ejects the paper P on which the image is formed by the image forming unit C. It is mainly composed of the sheet discharge section D and is arranged on the table section E. The stencil printing machine 30 has an operation panel section 32 arranged on the upper part thereof. From the operation panel 32,
Paper P size (A3, A4, B5, etc.) and type (thickness,
Paper quality, etc.), the number of printed sheets, the number of stacked sheets, etc. can be entered. The input various data are processed by the control means 33.

The image forming section C has a function of forming a punched image according to image information on a master (not shown) and cutting it into a predetermined length, and a plate-making master ("plate-making master"). And a plate cylinder 35 around which the so-called) is wound. In the image forming section C, the plate-making master is set to the plate cylinder 35.
The ink is supplied to the plate-making master by being wound around the outer peripheral surface 35a of the plate and being supplied from an ink supply means (not shown) arranged inside the plate cylinder 35.

The sheet P fed from the sheet feeding device 1 toward the image forming section C is separated into only one sheet by the double feeding preventing means, and the feeding guide member 3 and the guide plate 36 arranged above it. Is guided by the registration roller pair 38 through a conveyance path 37 formed between the plate cylinder 35 and the sheet feeding device 1. In the registration roller pair 38, the leading edge Pa of the sheet P and the leading edge of the image forming area on the plate cylinder 35 are
The paper P is conveyed near the printing pressure roller 39 at the same timing. The printing pressure roller 39 is usually
It is located at a position away from the outer peripheral surface 35a, and is pressed against the outer peripheral surface 35a by a contacting / separating mechanism (not shown) at the printing timing, and presses the paper P fed to the plate-finished master filled with ink. Then, the punched image is printed.

Between the paper discharge section D and the plate cylinder 35, a suction conveyance unit F for conveying and guiding the printed paper P to the paper discharge section D is arranged. In the suction conveyance unit F, the endless perforation belt 42 is wound around the driving roller 40 and the driven roller 41, and the paper P, which has been printed by the suction fan 43 disposed below the endless perforation belt 42, is endlessly perforated. It is designed to be picked up and conveyed. The plate cylinder 3 is provided between the suction conveyance unit F and the plate cylinder 35.
Appropriate separating means such as a separating claw (not shown) for urging the peeling of the paper P from the sheet 5 is arranged.

According to the sheet feeding device 1 having such a structure, when the guide moving means 12 operates the guide members 4 and 5 in accordance with the state of the paper P, the paper P on the guide members 4 and 5 is moved. Both side portions Pb and Pc of the tip end Pa of are moved up and down accordingly. For example, on the paper P, both sides Pb ′, P located in a direction orthogonal to the paper feeding direction R as shown in FIG.
It is assumed that there is a convex curl in which c ′ is lower than the central portion Pd by a height h. In this case, when the variable motor 14 is started, the rotation thereof causes the worm gear 20 and the worm wheel 1 to rotate.
9 is transmitted to the drive shaft 17, and the cams 15 and 16 rotate from the lowermost position shown by the chain double-dashed line in FIG. 3 toward the uppermost position shown by the solid line. 1
The guide plates 4 and 5 are pushed upward from the initial position by making contact with the outer peripheral portions of 5 and 16.

Then, both side portions Pb and Pc at the leading edge Pa of the paper located above the guide members 4 and 5 are lifted upward due to the change of the rotation angle θ due to the upward movement of the guide plates 4 and 5. To be As a result, the central portion Pd of the sheet P and the side portions P of the sheet P on the leading edge 2A side of the sheet feeding table 2
The heights h of b and Pc are reduced, and the curl is corrected (corrected) at the leading edge Pa of the paper P.

Therefore, it is possible to reduce the jam caused by the interference between the guide plates 36 and the feeding guide member 3 and both side portions Pb and Pc of the sheet P when moving in the sheet feeding direction R, and the sheet P can be stably fed. Is possible. Further, since the paper P can be corrected only by rotating the guide members 4 and 5 provided at both ends 2B and 2C on the front end 2A side of the paper feed table 2, the paper feed table 2 as a whole can be moved. The load applied to the guide varying means 12 and the variable motor 14 serving as the drive source is reduced. Therefore, the output of the variable motor 14 can be reduced, and the guide varying means 12 can be downsized.

When the sheet P thus corrected comes into contact with the sheet feeding roller 8 and is fed in the sheet feeding direction R, the curls of both side portions Pb and Pc are curled on the guide members 4 and 5 as the sheet feeding moves. While being upwardly corrected by the separating roller 10 and the separating member 11, double feeding is prevented and the pair of registration rollers 3 from the conveying path 37.
You will be guided to 8. Then, the sheet P is sent between the plate cylinder 35 and the printing pressure roller 39 at the feeding timing, printing is performed by the pressing action of the printing pressure roller 39, and the sheet P is placed on the endless perforation belt 42 of the suction conveyance unit F. While being sucked by the suction fan 43, the sheet is discharged onto the sheet discharge tray 31 of the sheet discharge section D.

In this embodiment, the cams 15 and 16 are connected to the drive shaft 1.
7, the rotation is controlled by one variable motor 14, but cams 15 and 16 are provided on individual drive shafts.
Each of the drive shafts may be rotationally driven by two variable motors. By doing so, the rotations of the cams 15 and 16 can be individually controlled, so that the rotation angles θ of the guide members 4 and 5 can be set and adjusted separately. It is possible to perform the curl correction according to the curl state of the paper P.

Further, in this embodiment, the upper end portions 2b1 and 2c1 of the side plates 2b and 2b are flat surfaces, but as shown by the two-dot chain line in FIG. Formed on the upper surface 2a of the guide members 4 and 5, respectively.
It may be rotatable downward. In this case, the upper end portions 2b1 and 2c1 are arranged so that the back surfaces of the guide members 4 and 5 come into contact with the cams 15 and 16 at the lowest position.
It is preferable to determine the inclination angle of the above because the movements of the cams 15 and 16 are reflected in the rotation angle θ of the guide members 4 and 5 without waste.

With such a configuration, the paper P stacked on the paper feed tray 2 is positioned on both sides P located in a direction orthogonal to the paper feed direction R, which is opposite to the curl direction of the paper P shown in FIG.
Even if b ′ and Pc ′ are curled in a concave shape located above the central portion Pd, the guide members 4 and 5 rotate below the upper surface 2a, so that both side portions Pb and Pc move in the direction of arrow a. Correction (correction) of the concave curl that has occurred on the paper P
It is possible to do. As a result, it is possible to realize the paper feeding device 1 in which the width of curl correction is widened and jams and paper feeding defects are further reduced. The basic rotation angle θ of the guide members 4 and 5 may be set depending on how much the curl of the paper P is corrected.

Further, in the present embodiment, the paper feeding device 1 is provided integrally with the stencil printing device 30. However, as shown in FIG. 6, the paper feeding device 2'has a function of allowing a large amount of paper P to be stacked. It may be formed as the sheet feeding device 1 ′ included therein and configured separately from the stencil printing device 30.

Next, the control of the sheet feeding device 1 which is a modification of the first embodiment will be described. As shown in FIG. 7, the encoder 45 is fixed to the drive shaft 17, the pulse detection sensor 46 is arranged inside the sheet feeding table 2, and the slits of the encoder 45 are counted by the pulse detection sensor 46 to guide the guide members 4, 5. The rotation angle θ of is detected. The detected rotation angle θ is input to the control means 33 as an angle signal.

The control means 33 includes a memory, a CPU and an I / O.
It is mainly composed of a well-known microcomputer having an O port, and judges the turning angle θ of the guide members 4 and 5 based on the input angle signal. The memory of the control means 33 stores guide member control data preset according to conditions such as the size and type of the paper P and the number of sheets of paper stacked.

This guide member control data is, as shown in FIG. 8, a height difference h between the central portion Pd and both side portions Pb, Pc of the paper P, which is obtained in advance by experiments, and a guide for eliminating this height difference h. The map data is created from the set angles θ1 of the members 4 and 5. Here, the guide member control data is set as map data to have a continuously variable characteristic.
The map data may be changed stepwise as indicated by a broken line, or may be calculated by a calculation formula or the like.
The control means 33 controls the variable motor 14 so that the rotation angle θ corresponds to the map data, and stops the variable motor 14 when the guide members 4 and 5 reach the rotation angle θ set by the angle signal. Has become.

Therefore, when predetermined information (paper size, its type, number of stacked sheets) is input from the operation panel 32,
The variable motor 14 drives to rotate the worm gear 2.
0, transmitted from the worm wheel 19 to the drive shaft 17,
The cams 15 and 16 are rotated to an angle corresponding to the predetermined rotation angle θ. When the angle signal from the pulse detection sensor 46 becomes an angle signal corresponding to the predetermined rotation angle θ,
The variable motor 14 stops and the height difference h of the paper P is eliminated. As a result, the guide members 4 and 5 are automatically changed to the appropriate rotation angle θ according to the input condition from the operation panel 32, and the curl correction of the paper P is automatically performed to operate the paper feeding device 1. It improves the sex.

Second Embodiment A sheet feeding device 100 as a second embodiment shown in FIG.
The sheet feeding device 1 shown in the embodiment is provided with a height detection unit 50 that detects the height of the entire leading edge Pa of the sheet P. Therefore, only parts different from the first embodiment will be described here, and the same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The height detecting means 50 is a sensor 5 with a filler provided on an upper portion of a sheet feeding arm 60 which constitutes the sheet separating section B.
1, 52, a sensor 53 with a filler provided above the paper feed arm 60, and levers 54, 55, 56 that rotate in the slits of the sensors 51, 52, 53.
The filler-attached sensors 51 and 52 are arranged at both ends of the paper feed arm 60, and the filler-attached sensor 53 is above the paper feed roller 8 supported by the shaft 7 provided on the paper feed arm 60.
It is fixedly arranged on a base (not shown).

The levers 54 and 55 are used to feed the paper P in the paper feed direction R.
A curved lever that is arranged above both side portions Pb, Pc located on the side and extends toward both side portions Pb, Pc,
It is rotatably supported by the filler-attached sensors 51 and 52, respectively. The lever 56 extends toward the paper feed arm 60 and is rotatably supported by the filler sensor 53. These filler-attached sensors 51, 52, 53
Are connected to the control means 33 ', detect the movable angles of the levers 54, 55, 56 and input them to the control means 33' as angle signals.

As shown in FIG. 10, the paper feed arm 60 rotatably supports a drive shaft 9 for supporting the separation roller 10 in contact with the separation member 11. The drive shaft 9 is rotationally driven by a drive mechanism (not shown) and is rotatably supported at both ends of the paper feed arm 60, so that the paper feed arm 60 can be swung about the drive shaft 9. Therefore, the paper feed roller 8 is usually the separation roller 1
It is located at a position lower than 0, and the paper feed tray 2 is raised and pushed up by the central portion Pd of the paper P. The lever 56 and the paper feed arm 6 are raised to raise the paper feed tray 2.
When the angle signal from 0 and the angle signal from the sensor 53 reach a predetermined angle, it stops. That is, as shown in FIG. 11, the paper feed roller 8 is stopped at the paper feed position where it comes into pressure contact with the paper P.

The control means 33 'is mainly composed of a well-known microcomputer. Here, the central portion Pd and both side portions Pb, Pc of the sheet P are detected from the angle signals inputted from the filler sensors 51, 52. Of the set angle information for varying the rotation angle θ of the guide members 4 and 5 according to the height difference information obtained by the calculation, and the predetermined angle for stopping the paper feed roller 8 at the paper feed position. The variable motor 14 is stored according to this information.
(See FIG. 2) and the amount of movement of an elevating means (not shown) are controlled.

The control means 33 'sets the angle signal from the lever 56 to the height of the central portion Pd of the paper P when the paper feed roller 8 is at the paper feed position, and the paper feed roller 8 is at the paper feed position. Moreover, the angle signals from the levers 54 and 55 when the both side portions Pb and Pc of the sheet P are not curved are stored as the reference angle signals of the both side portions Pb and Pc of the sheet P. When the angle signals from the levers 54 and 55 are smaller than the reference angle signal, the control means 33 'drives the variable motor 14 so as to rotate the guide members 4 and 5 upward, and the angle signal is larger than the reference angle signal. When it is large, the variable motor 14 is driven so as to rotate the guide members 4 and 5 downward.

According to the sheet feeding device 100 having such a configuration, when the sheet feeding table 2 is lifted by the not-shown elevating means, the levers 54 and 55 are rotated by both side portions Pb and Pc of the sheet P, and the sheet P is also moved. Paper feed roller 8 at the central portion Pd of
Is pushed up. Then, when the angle signal from the lever 56 reaches a predetermined angle, the raising of the paper feed tray 2 is stopped and the paper feed roller 8 is positioned at the paper feed position.

Further, the levers 54, 55 cause the sensors 51, 52 with fillers to output the movable angle to the control means 33 'as an angle signal. At this time, if the paper P is not curled, the angle signals from the sensors 51 and 52 become reference angle signals, and thus the curl correction by the guide members 4 and 5 is not executed.

On the other hand, when a convex curl is generated on the paper P, both side parts Pb and Pc are lower than the central part Pd.
The upward rotation of the levers 54 and 55 is smaller than that when the paper P is flat. Then, the angle signals from the sensors 51 and 52 become smaller than the reference angle signal, and the variable motor 1
4 is driven to rotate the guide members 4 and 5 upward.
As a result, both sides Pb and Pc are lifted and the curl correction of the paper P is performed.

On the other hand, when the paper P has a concave curl, both side parts Pb and Pc rise above the central part Pd, so that the levers 54 and 55 are rotated upwards more than when the paper P is flat. growing. Then, the angle signals from the sensors 51 and 52 become larger than the reference angle signal, the variable motor 14 drives the variable motor 14 to rotate the guide members 4 and 5 downward, and both side parts Pb and Pc are lowered. The curl correction of the paper P is performed.

The control means 33 'drives the guide members 4, 5 to perform the curl correction operation until the angle signals from the sensors 51, 52 become the reference angle signal. That is, the height control of the guide members 4 and 5 depends on the height detection means 5.
The process is performed until there is no difference in height between the center portion Pd of the leading edge of the sheets P stacked on the sheet feed tray 2 and the side portions Pb and Pc based on the detection information from 0.

Therefore, even if the curl state of the paper P on the paper feed table 2 changes to a convex shape or a concave shape or the degree of curl changes according to the environmental change of the device or the standing time, the current paper P is changed. Since the curl state is directly detected, the correction can be appropriately performed, which is effective in reducing a paper feed failure, a paper break, a paper jam, and the like.

Further, the control means 33 'is provided with a timer function, a predetermined fetching time is set when the sheet feeding device is operated, and the angle signals from the sensors 51, 52 and 53 are fetched at every predetermined fetching time. Alternatively, the control unit 33 'is provided with a function of counting the number of fed sheets and a predetermined number of fed sheets is set, and the sensor 5 is set for each set number of fed sheets.
The curl correction of the paper P may be performed by taking in the angle signals from 1, 52 and 53 and adjusting the rotation angles of the guide members 4 and 5.

As described above, when the curl correction is performed at a constant number of sheets to be fed or at a certain operating time, even if the degree of curl of the sheets P on the sheet feed table 2 changes due to a change in the number of sheets stacked due to sheet feeding, the operator It is possible to deal with the curl of the paper P that has changed rapidly without performing any special operation. This is effective in reducing the paper feed jam caused by the interference between the paper P and the paper feed guide member 3.

Here, the control means 33 'is provided with a timer function and a function of counting the number of fed sheets to perform curl correction of the sheet P according to time and the number of fed sheets.
The control unit 33 may be provided with a similar function, and the curl correction may be performed by adjusting the rotation angle of the guide members 4 and 5 depending on the time and the number of fed sheets.

Next, the control of the guide members 4 and 5 when the paper feed trays 2 and 2'are lowered will be described. Sensors S1 and S2 for detecting the lowermost positions of the respective paper feed trays 2 and 2 ′ are arranged below the paper feed tray 2 and the paper feed tray 2 ′ shown in FIGS. The sensors S1 and S2 are connected to the control means 33 and the control means 33 ', respectively, and output the lowest position signal. When the lowest position signal is input, the control means 33, 33 'to which the sensors S1, S2 are connected, the variable motor for returning the guide members 4, 5 to the reference positions that are flush with the upper surface 2a and the upper surface 2a'. 14 is driven.

According to this structure, the paper feed trays 2, 2 '
Is moved to the lowermost position by an elevating means (not shown), the variable motor 14 is driven, the cams 15 and 16 rotate, and the guide members 4 and 5 stop at the reference position. Therefore, when the paper P is replenished to the lowermost paper feed trays 2, 2 ', the upper surface 2a,
Since 2a 'is flat, the paper P to be supplied can be supplied without being caught by the guide members 4 and 5, and the operability at the time of paper supply is improved.

Here, the sensors S1 and S2 are used to position the guide members 4 and 5 at the reference positions when the paper feed trays 2 and 2'are lowered to flatten the upper surfaces 2a and 2a 'of the paper feed trays 2 and 2'. However, the present invention is not limited to this. For example,
The control means 33, 33 'is provided with a function of counting the number of fed sheets of paper P, and when the counted value becomes the same as the number of stacked sheets of paper, the variable motor 14 is moved so as to position the guide members 4, 5 at the reference position. In addition to driving, the lifting means (not shown) is driven in the lowering direction. With such a configuration, the guide members 4 and 5 move to the reference position as the sheet feeding trays 2 and 2 ′ at the sheet feeding position move down, so that the sheet feeding trays 2 and 2 ′ reach the lowest position. By the time, the upper surfaces 2a and 2a 'of the paper feed trays 2 and 2'are flattened,
The operability when replenishing paper is improved.

[0053]

According to the first aspect of the present invention, when the guide members whose heights are variable are provided at both ends of the leading end excluding the central portion of the paper feeding table located on the paper feeding direction side, the paper is fed in the paper feeding direction. Since the curl of the sheet is corrected by the guide member when the sheet is moved, it is possible to eliminate the sheet feeding failure such as the sheet curl, the sheet folding, or the jam. Further, unlike the conventional example, the curl correction is performed by moving the entire paper feed tray, but the curl correction is performed by driving the guide members arranged at both ends of the leading end, which is the side in the paper feed direction. It can be made smaller and the device can be made smaller.

According to the second aspect of the invention, the sheet on the sheet feed table is fed to the image forming section of the image forming apparatus by the sheet feeding / separating section having the double feeding preventing means and the sheet feeding guide member. ,
It is possible to eliminate a paper feed failure such as a paper feed failure, a paper break, or a jam when the paper is fed to the image forming unit.

According to the third aspect of the present invention, the height of the guide member is set according to preset conditions when the type and size of the sheet or the number of stacked sheets is input to the image forming apparatus. The height of the guide member can be automatically adjusted according to the type and size of the paper, and the curl of the paper can be corrected with good operability.

According to the fourth aspect of the invention, based on the detection information from the height detecting means for detecting the height of the entire leading edge of the stacked sheets, the height difference between the central portion and both side portions of the leading edge of the sheet. By controlling the height of the guide member to eliminate the curl, it is possible to detect the curl of the stacked paper itself, and the paper curl state due to environmental changes (temperature, humidity, etc.) around the device without special operations. Corresponding curl correction is possible,
The operability of the device is improved.

According to the fifth aspect of the present invention, the height difference between the central portion and the both side portions of the leading edge of the stacked sheets is detected for each preset number of sheets to be fed or every time interval, and based on this detection result. Since the height of the guide member is corrected to eliminate the difference in height between the center and both sides of the leading edge of the stacked sheets, the curl of the sheet is corrected at a set time interval or for each set number of sheets regardless of the number of sheets stacked. To be done. Therefore, curl correction suitable for the current state of the stacked sheets can be performed, and problems such as sheet jams can be further reduced.

According to the sixth aspect of the invention, the guide member is controlled to return to the same height as the paper feed table when the paper feed table is lowered, so that the paper feed table is lowered when the paper feed table is lowered. The height difference from the guide member is eliminated, the folding and catching of the paper due to the guide member at the time of paper replacement are reduced, and the operability at the time of paper supply is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a sheet feeding device showing a first embodiment of the invention.

FIG. 2 is a perspective view showing a configuration of a guide member and its drive mechanism, which are essential parts of the present invention.

FIG. 3 is a side view showing the operation of the guide member and its drive mechanism.

FIG. 4 is a schematic configuration diagram of an image forming apparatus including the paper feeding device of the present invention.

FIG. 5 is a front view showing a curled state of a sheet on a sheet feed tray.

FIG. 6 is a schematic configuration diagram of an image forming apparatus including a modified example of a sheet feeding device.

FIG. 7 is a partially enlarged perspective view showing configurations of a guide member and a drive mechanism thereof.

FIG. 8 is a diagram showing characteristics of a set angle set in the control means.

FIG. 9 is a perspective view of a paper feeding device showing a second embodiment of the present invention.

FIG. 10 is an enlarged view of the vicinity of the sheet feeding unit when the sheet feeding roller is not at the sheet feeding position.

FIG. 11 is an enlarged view of the vicinity of the sheet feeding unit when the sheet feeding roller is at the sheet feeding position.

[Explanation of symbols]

 1,100 Paper Feeding Device 2,2 'Paper Feeding Tables 2B, 2C Both Ends 3 Feed Guide Member 4,5 Guide Member 10 Separation Roller 11 Separation Member 30 Image Forming Device 33,33' Control Means 50 Height Detection Means B Paper Separation Unit C Image Forming Unit P Paper Pb, Pc Both Sides of Paper Edge Pd Center of Paper Edge R Paper Feed Direction

Claims (6)

[Claims] 1. A sheet feeding device for feeding sheets stacked on a sheet feeding table, wherein a height variable type is provided at both ends of a tip of the sheet feeding table excluding a central portion located on a sheet feeding direction side. A sheet feeding device characterized in that a guide member is provided. 2. The sheet feeding device feeds a sheet on the sheet feeding table to an image forming section of an image forming apparatus by a sheet feeding separating section having a double feeding preventing means and a sheet feeding guide member. The paper feeding device according to claim 1. 3. When the type and size of the paper or the number of stacked sheets of paper is input to the image forming apparatus, the guide member provided on the paper feed table is operated in accordance with conditions preset in the image forming apparatus. The sheet feeding device according to claim 1, wherein the height is set. 4. A height detecting means for detecting the height of the entire leading edge of the stacked sheets, and the height difference between the central portion and both side portions of the leading edge of the sheet based on the detection information from this detecting means. 3. The paper feeding device according to claim 1, wherein the height of the guide member is controlled so as to eliminate the problem. 5. The height difference between the central portion and both side portions of the leading edge of the sheet is detected for each preset number of sheets or time intervals set in the image forming apparatus, and the center of the leading edge of the sheet is detected based on the detection result. 5. The paper feeding device according to claim 1, wherein the height of the guide member is controlled so as to eliminate the height difference between the portion and both side portions. 6. The feeding device according to claim 1, wherein the guide member is controlled so as to return to the same height as the paper feeding table when the paper feeding table is lowered. Paper equipment.