JP2548230B2 - Sheet feeding device - Google Patents

Description

The present invention relates to a sheet feeding device of an image forming apparatus such as a copying machine and a laser beam printer, and more particularly to a sheet storage device that stores a large number of sheets ( The present invention relates to a sheet feeding device of a system (cassette system) in which a sheet (hereinafter referred to as a cassette) is attached to a main body of an image forming apparatus and a sheet stored in the cassette is fed.

(B) Prior Art Conventionally, a cassette type sheet feeding device is known, but the sheet feeding device 1 ′ has a sheet feeding table 3 on which a cassette 2 is placed, as shown in FIG. It is equipped with the paper feed table 3
Is a substantially horizontal bottom portion 3a on which the cassette 2 is placed, and the bottom portion 3a
A stopper portion 3b that rises substantially vertically to restrict the insertion of the cassette into the image forming apparatus, an inclined portion 3c inclined at the tip end side of the stopper portion 3b, and the inclined portion 3c. Each of the guide portions 3d extends horizontally. Also,
The cassette 2 is provided with an intermediate plate 5 on which a large number of sheets S are stacked and which is vertically movable, and the intermediate plate 5 has a double bottom. Further, the inner plate 5 is provided inside the paper feed table 3.
A pressure plate 6 for urging the pressure plate 6 is rotatably supported by a shaft 7, and the pressure plate 6 is configured to be rotated by a rotation unit (not shown). A conveyance roller 9 that conveys the sheet S is disposed in the vicinity of the sheet feed table 3, and a separation roller 10 that is a retard roller that separates the sheet S by pressingly contacting the conveyance roller 9 is arranged. It is set up. Further, supporting plates 11 and 11 are rotatably supported on a shaft 9a of the conveying roller 9, and the sheet feeding roller 12 is rotatably supported on the supporting plates 11 and 11 and the supporting plates 11 and 11 are rotatably supported. 11,11
It is designed to rotate together with. On the upstream side of the paper feed roller 12, a positioning sensor 15 fixed to the machine body frame 13 and constituted by a transmissive sensor is provided, and the sensor 15 is turned on by the tip 11a of the support plate 11. O
FF is set. Further, a guide pair 16 for guiding the sheet S is arranged downstream of the conveying roller 9.

Then, the sheets stacked on the intermediate plate 5 are urged to the sheet feeding roller 12 by the pressure plate 6 which is rotated by the rotating means, and the sheet S pushes up the sheet feeding roller 12 and the front end 11 of the support plate 11.
When a is detected by the positioning sensor 15, the rotation of the pressure plate 6 is stopped. Then, when the start key is pressed, the sheet feeding roller 12 rotates to feed the sheet S stacked on the middle plate 5, and the sheet comes into contact with the inclined portion 3c of the sheet feeding table 3 and is fed. It At this time, when a plurality of sheets S ... Are multi-fed, the leading ends of these sheets S ... are separated by the inclined portion 3c. Further, the plurality of sheets S whose leading ends have been separated are separated one by one by the conveying roller 9 and the separating roller 10 and conveyed to the guide pair 16, and are guided downstream by the guide pair 16. The operation of the separation method of the retard roller method, in which the reverse rotation separating force is applied to the separation roller by the torque limiter, is well known, and the description thereof is omitted. By the same operation, the sheets S are sequentially fed, and when the leading end 11a of the support plate 11 is no longer detected by the positioning sensor 15, that is, the number of the sheets S on the middle plate 5 is reduced and the sheet feed roller 12 and the support plate 11 are separated. Rotates counterclockwise and the tip 11a of the support plate 11 moves to the positioning sensor 15
When it is further lowered, the rotating means rotates the pressure plate 6 in the clockwise direction to urge the sheet S on the middle plate 5 upward. Then, when the sheet S pushes the feed roller 12 upward and the positioning sensor 15 detects the tip 11a of the support plate 11, the rotation of the pressure plate 6 is stopped. Then the positioning sensor 15
Each time the front end 11a of the support plate 11 is no longer detected, the intermediate plate 5 is pushed up by the pressure plate 6 until the sensor 15 detects the front end 11a, whereby the paper feed roller 12 enters the paper feed state.

(C) Problems to be Solved by the Invention By the way, in the above-described sheet feeding device 1 ', the intermediate plate 5
Is inclined every time it is pushed up by the pressure plate 6, and is positioned at the position shown in FIG. 8 when the sheets S to be stacked become small. When the sheet S stacked on the intermediate plate 5 is fed by the sheet feeding roller 12, the leading end of the sheet S does not come into contact with the slanted portion 3c of the sheet feeding table 3 and is not separated. It abuts the transport roller 9 (see FIG. 7). At this time, for example, when three sheets S ₁ , S ₂ , and S ₃ are double-fed, these sheets
S ₁ , S ₂ , and S ₃ are fed without the ends being touched and abut against the transport roller 9 (see FIG. 8A). Then, the lowest sheet S _{3 of} the sheets S ₁ , S ₂ , S ₃ contacting the roller 9 first reaches the nip A between the transport roller 9 and the separation roller 10 (FIG. 8 (b)). reference). At this time, the separation roller 10 is rotated along with the conveyance roller 9, and the sheet S ₃ is conveyed to the nip A. Then, the second sheet S ₂ is conveyed to the nip A (see FIG. 8C), and when the separating roller 10 is pushed down by the thickness of these sheets S ₂ and S ₃ , the separating roller 10 is The lowermost sheet S ₃ is pushed back until it passes through the nip A by being connected to a driving means (not shown) and rotating counterclockwise. At this time, the second sheet S ₂ is conveyed by the conveying roller 9 on the sheet S ₃ that is pushed back by the separating roller 10, so that the front and back surfaces of the sheet S ₂ have a significantly different friction state, and The S ₂ sometimes skewed (see FIG. 8 (d)). Furthermore, the top sheet S ₁ is nip A
When the sheet S ₂ is conveyed to, the sheet S ₂ is pushed back until it leaves the nip A by the same operation as described above. At this time the bottom sheet
Since S ₁ is conveyed on the sheet S ₂ that is pushed back by the separation roller, the friction state is significantly different between the front and back of the sheet S ₁ , and especially when the sheet S ₂ is skewed, the front and back of the sheet S ₁ The frictional state changed intricately in each part of the sheet, and this sometimes caused the sheet S ₁ to skew. In addition, even when a fixed brake is used as the separating means or a separating method in which the separating roller (or belt) is always given a reverse rotation force, if a large number of transfer materials overlap and enter the nip part, sufficient double feeding is prevented. There were times when it couldn't be done or skewed.

(D) Means for Solving the Problem The present invention is intended to solve the above-mentioned problems, and is intended to mount a large number of sheets and to support a sheet mounting that is swingably supported in the vertical direction. Means, moving means for moving the sheet placing means upward, and movable up and down in contact with the sheet placed on the sheet placing means to follow the movement of the sheet placing means. A feeding rotating body that is provided for feeding the sheet out from the sheet placing means, and a sheet for feeding the sheet at a contact position between the feeding rotating body and the sheet placed on the sheet placing means. A feeding position detecting means for detecting whether or not it is at the feeding position, and controlling the moving means based on the detection of the feeding position detecting means so that the contact position becomes the sheet feeding position. Control for moving the sheet placing means A sheet feeding device including a step, the feeding position detecting means being provided so as to be movable up and down, and the feeding position detecting means being lowered in accordance with an increase in the swing amount of the sheet placing means. It is characterized by the provision of interlocking means.

(E) Action When the sheet placed on the sheet placing means is fed out by the feeding rotating body, the amount of sheets on the sheet placing means is reduced, and the uppermost sheet surface position on the sheet placing means is changed. It descends, and the feeding rotating body also descends accordingly. When the feeding position detecting means detects that the descending amount of the feeding rotating body reaches a predetermined amount, the control means moves the sheet placing means upward via the moving means based on the detection result. Then, the feeding position detecting means is moved downward by the interlocking means in accordance with the increase in the movement amount of the sheet placing means.
When the feeding position detecting means detects that the contact position between the feeding rotating body and the sheet placed on the sheet placing means is at the sheet feeding position for feeding the sheet, the control means moves the moving means. Stop the operation of. After that, the feeding rotating body sends out the sheet on the sheet placing means.

(F) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

The same portions as those described above are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIGS. 1 to 3, in the sheet feeding device 1, a shaft 9a is rotatably supported by a body frame 24 and a rear side plate 17, and a conveying roller 9 is provided on the front side of the shaft 9a. Is fixed. A pulley 19 is fixed to the tip of the shaft 9a, and a support plate 11 is rotatably supported on the inner side of the shaft 9a with respect to the conveying roller 9. Further, on the back side of the shaft 9a, an input gear 20 connected to a driving means (not shown) is rotatably supported.
It is configured to be connected to and disengaged from the shaft 9a by a clutch 21 supported by the shaft 9a.
A drive gear 22 is fixed near 20. A pin 25 is fixed to the front plate 23 on the axis of the shaft 9a, and a bell crank-shaped sensor holder (interlocking device) 26 in a front view is swingable by the pin 25 and a supporting plate 11 'is provided. It is rotatably supported. A positioning sensor (feed position detecting means) 15 is provided at one end 26a of the center holder 26 extending in the lateral direction, and the support plate is provided between the light emitting portion 15a and the light receiving portion 15b of the sensor 15. The tip of 11 'is positioned. Further, a gear 26c is formed on the other end 26b extending downward of the sensor holder 26.
Is a fan-shaped gear (interlocking means) fixed to a shaft (moving means) 7 rotatably supported by the front side plate 23 and the body frame 24.
It meshes with 27. Then, at the front end of the shaft 7,
A fan-shaped gear 30 meshing with a gear 29 connected to a motor (not shown) is fixed, and a pressure plate (moving means) 6 is fixed to the rear end. The support plate
A shaft 31 is rotatably supported by 11 ′ and 11 ″, and paper feed rollers 12 are fixed to both ends of the shaft 31.
A pulley 32 is fixed to the center of the shaft 31.
A timing belt 33 is stretched between 32 and the pulley 19. The paper feed roller 12 includes a support plate 11 ′ rotatably attached to the pin 25, a support plate 11 ″ rotatably attached to the shaft 9a, the weight of the shaft 31, the pulley 32, and the like, and the paper feed roller 12. Due to the weight of the roller 12 itself, the roller is in contact with the uppermost sheet surface on the intermediate plate 5 as the sheet placing means, and its position is changed according to the change of the uppermost sheet surface position. Is provided with a long hole 24a, and a support member 36 is movably supported in the long hole 24a by a spring 35 having one end fixed to the frame 24.
A shaft 37 is rotatably supported by 36 and the rear plate 17, and a gear 40 that meshes with the drive gear 22 via an idle gear 39 is fixed to the rear end of the shaft 37. Further, a separation roller 10 is rotatably supported on the front end portion of the shaft 37, and an output drum 41 is rotatably supported on the shaft 37 adjacent to the roller 10. An input drum 42 is fixed to the shaft 37 in the vicinity of the output drum 41, and a left-handed clutch spring 43 in a front view is wound around the input drum 42 and the output drum 41. This constitutes a clutch 45 which operates as a torque limiter in the clockwise direction. In the figure, 46 is a clutch spring
It is a clutch case that protects 43.

Since the present embodiment has the above-described configuration, when the cassette 2 is mounted on the paper feed tray 3, the cassette 2 is detected by a cassette sensor (not shown). Then, a control unit (control means) that receives a detection signal from the cassette sensor
Based on a signal from the positioning sensor 15, (not shown) determines whether the tip of the support plate 11 'is detected by the sensor 15, that is, whether the paper feed roller 12 is located at the paper feed position. However, if it is determined that it is located, it waits until a start key (not shown) is pressed. If the positioning sensor 15 does not detect the leading end of the support plate 11 ', the controller rotates the gear (moving means) 29 counterclockwise by a motor (not shown). The fan gear (moving means) 30 is rotated clockwise.
As a result, the shaft 7 rotates in the clockwise direction, and the rotation of the shaft 7 causes the pressure plate 6 to rotate in the clockwise direction to push up the intermediate plate (sheet mounting means) 5 and rotate the fan-shaped gear 27 in the clockwise direction. It moves to swing the sensor holder 26 counterclockwise. As a result, the positioning sensor 15 moves at a predetermined ratio in a direction (downward) opposite to the moving direction of the intermediate plate 5. That is, the positioning sensor 15 moves downward according to the swing amount of the intermediate plate 5.
When the positioning sensor 15 detects the tip of the support plate 11 ', the control unit receiving the signal from the sensor 15 determines that the paper feed roller 12 is at the paper feed position and stops the motor. Then, when the operator presses the start key, the input gear rotated by the motor (not shown) by the clutch 21.
20 is connected to the shaft 9a, and the shaft 9a rotates counterclockwise.
Further, the rotation of the shaft 9a causes the conveyance roller 9 and the pulley 19 to rotate, and the rotation of the pulley 19 causes the shaft 31 to rotate counterclockwise via the timing belt 33 and the pulley 32. And
The paper feed roller 12 rotates integrally with the shaft 31 to feed the uppermost sheet S placed on the middle plate 5, and the sheet S comes into contact with the inclined portion 3c of the paper feed table 3 It is fed to the transport roller 9. At this time, when a plurality of sheets S ... Are fed in a multi-ply manner, the sheets S ... Are separated by abutting the leading ends thereof against the inclined portion 3c (see FIG. 4). Then, a plurality of sheets S whose ends are separated ...
Are separated one by one by the conveying roller 9 and the separating roller 10 and conveyed to the guide pair 16, and are guided downstream by the guide pair 16. By the same operation, the sheets S ... stacked on the middle plate 5 are sequentially fed from the upper side, and the height of the sheets S ... When is lowered and the tip of the support plate 11 'comes off from between the light emitting portion 15a and the light receiving portion 15b of the positioning sensor 15 downward, the sensor 15 is turned on. Then, the control unit which receives the ON signal of the sensor 15 pushes up the intermediate plate 5 by the pressure plate 6 and swings the sensor holder 26 counterclockwise by the same operation as described above. As a result, when the positioning sensor 15 detects the leading end of the support plate 11 ', in the continuous copying mode, the sheet feeding operation is restarted, and the sheet S on the middle plate 5 is fed by the sheet feeding roller 12 to the inclined portion of the sheet feeding table 3. After abutting on 3c, the sheet is fed to the conveying roller 9 (see FIG. 5). In the non-continuous mode, it waits for the next copy.

If a high-friction member such as rubber is attached to the inclined portion 3c of the paper feed table 3, the separation of the sheet S can be further ensured.

(G) Effect of the Invention As described above, according to the present invention, the paper feeding position detecting means is provided so as to be movable up and down, and the interlocking means is provided with the feeding position detecting means in accordance with an increase in the swing amount of the sheet placing means. Since it is designed to lower the sheet, the sheet can be sent out in the optimal sheet feeding direction by the sheet feeding rotating body regardless of the amount of sheets on the sheet stacking means, and problems such as double sheet feeding and sheet feeding failure can occur. Can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a front view showing a sheet feeding device according to the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a side sectional view thereof. 4 and 5 are front sectional views showing the operation of the present invention. Then, FIGS. 6 to 8 (a),
(B), (c), (d) is a figure which shows a prior art example. 1,1 ′, 1a …… Sheet feeding device, 5 …… Middle plate, 6,7,29,30
...... Movement means, 12 …… Feeding rotator, 15 …… Feeding position detection means, 26 …… Sensor holder, 27 …… Fan gear, 26,27 ・ ・ ・
… Interlocking means.

Claims (1)

(57) [Claims] 1. A sheet placing means for placing a large number of sheets and swingably supported in the vertical direction, a moving means for moving the sheet placing means upward, and the sheet placing means. A feed rotating member for contacting a sheet placed on the sheet and capable of moving up and down so as to follow the movement of the sheet placing means, and for feeding the sheet from the sheet placing means; Feed position detecting means for detecting whether or not the contact position between the body and the sheet placed on the sheet placing means is the sheet feeding position for feeding the sheet, and the feeding position detecting means And a control means for moving the sheet placing means so that the contact position becomes the sheet feeding position, the sheet feeding device comprising: The feeding position detection means can be moved up and down To provided the sheet feeding apparatus is characterized by providing the interlocking means for lowering the feed position detecting means in accordance with an increase in the swing amount of said sheet stacking means.