JPH08198471A - Paper feeding device for image forming device - Google Patents

Abstract

PURPOSE: To provide a paper feeding device for image forming device, which can prevent the noise to be generated in a paper feeding roller and a paper separating roller due to the fluctuation of the sliding torque of a torque limiter and which can perform the stabilized paper feeding. CONSTITUTION: A paper separating roller 5 is connected for drive to a driving shaft 7A working as a support shaft of a supporting frame 9, which can be freely oscillated, by a gear transmitting means 16 through a torque limiter, and the driving torque in the direction opposite to the paper feeding direction is applied from the driving shaft 7A to the paper separating roller 5. The gear transmitting means 16 is formed so that the direction of the torque to be applied to the driving shaft 7A and the direction of the moment around the driving shaft 7A to be generated by the frictional force applied from the paper feeding roller 4 side to the surface of the paper separating roller 5 are opposite to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device used in a paper feeding portion of an image forming apparatus such as an electrophotographic copying machine, and more particularly to a paper feeding mechanism in which a paper feeding roller is brought into contact with a paper feeding roller. The present invention relates to a paper feeding device configured so that the pressure is not affected by the driving torque of a paper separating roller.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or a laser printer, sheets taken out from a sheet feeding tray by a pickup roller are separated one by one by a sheet separating mechanism. A sheet feeding device configured to feed a sheet toward a sheet conveying path is used. Examples of the sheet feeding device provided with the sheet separating mechanism are described in, for example, JP-A-59-74841, JP-A-63-139842, and JP-A-3-23125. The device is known. In the paper feeding device as described above, as shown in FIG. 6, a pickup roller 3 supported by a support shaft 3A and an upper portion of the paper feeding tray 1 near the paper feeding side end are provided. The paper 2 accommodated in the paper feed tray 1 is combined with the paper separating mechanism 17 arranged on the downstream side in the paper direction,
The sheet feeding device 15 has a function of sequentially taking out the upper ones and feeding them one by one.

A paper sorting mechanism 17 of the paper feeding device 15
Faces the sheet feeding roller 4 that conveys the sheet 2 in the sheet feeding direction, and the separating roller 5 to which the driving force is applied in the direction opposite to the sheet feeding direction, that is, the direction that returns the sheet 2 to the sheet feeding tray 1. Are arranged to perform a judgment operation on the paper 2. A separating roller gear 6 is attached to the support shaft 5A so that the driving force is transmitted by the drive gear 7 provided on the drive shaft 7A, and between the drive shaft 7A and the drive gear 7. A torque limiter 13 is arranged. The support shaft 5A provided with the separating roller 5 is attached to a support frame 9 that is swingably supported about a drive shaft 7A, and the support frame 9 is also provided.
Is pressed against the sheet feeding roller 4 by a coil spring 10 stretched between a bracket 9A provided on the lower side on the downstream side in the sheet feeding direction and a coil spring fixing portion 12 on the image forming apparatus main body side. Is urged to

As shown in FIG. 7, the paper separating mechanism 17 in the above-described conventional paper feeder 15 is driven by rotating the drive shaft 7A clockwise by a drive source (not shown). Through the gear 7 and the separating roller gear 6, a torque in a direction for rotationally driving the separating roller 5 in the counterclockwise direction is generated. Therefore, when two sheets of paper enter the sheet separating mechanism 17 in a state of being overlapped with each other, slippage occurs between the upper and lower sheets, and the lower sheet in contact with the separating roller 5 is separated by the separating roller 5 Is rotated to the paper feed tray 1 side by the counterclockwise rotation, and only the upper paper that is in contact with the lower surface of the paper feed roller 4 is sent out toward the paper conveyance path 11.

When only one sheet of paper enters the sheet separating mechanism 17, the frictional force between the sheet and the separating roller 5 becomes larger than the transmission force of the torque limiter 13. The torque limiter 13 that transmits torque to the drive shaft 7A slips on the drive shaft 7A, the separating roller 5 is rotated clockwise by the frictional force received from the lower surface of the sheet, and the sheet is rotated by the frictional force from the sheet feeding roller 4. , And is sent to the side of the paper transport path 11. The sheet feeding device shown in FIG. 6 is provided with a sheet separating mechanism called a friction retard system, which is conventionally arranged in a sheet feeding portion of an image forming apparatus, and includes a sheet feeding roller 4
The driving of the separation roller 5 and the pickup roller 3 is performed by a single drive source.

[0006]

When the paper separating mechanism 17 is used as described above, the drive gear 7 provided on the drive shaft 7A is driven by meshing with the separation roller gear 6 provided on the support shaft 5A. As shown in FIG. 7, the drive gear 7 exerts an upward force X on the separating roller gear 6 because the force is transmitted, and the separating roller 5 moves in the horizontal direction from the paper feeding roller 4. The frictional force F will be received. Therefore, the pressure contact force of the separating roller 5 with respect to the sheet feeding roller 4 depends on the urging force Y of the coil spring 10 and the separating roller 5
Is related to the frictional force F acting on the outer periphery of and the force X acting between the drive gear 7 and the separating roller gear 6,
The force F and the force X are proportional to the slip torque of the torque limiter 13. However, in general, the slip torque of the torque limiter 13 tends to fluctuate periodically, so the force F
And X fluctuate, and the pressing force of the separating roller 5 on the sheet feeding roller 4 fluctuates. As a result, there arise problems that the member holding the paper feed roller 4 and the support frame 9 vibrate, noise becomes large, and the paper feed operation is disturbed.

[0007]

SUMMARY OF THE INVENTION The present invention solves the problems of the sheet feeding device in the prior art as described above, and is generated in the supporting portion of the sheet feeding roller or the separating roller due to the fluctuation of the slip torque of the torque limiter. It is an object of the present invention to provide a sheet feeding device of an image forming apparatus that can prevent the noise generated and can perform a stable sheet feeding operation.

[0008]

To achieve the above object, according to the present invention, a separating roller is arranged so as to face a sheet feeding roller which is driven to rotate in the sheet conveying direction, and the separating roller is provided with respect to the sheet feeding roller. And is rotatably supported by a supporting frame which is swingably supported in the contacting / separating direction, and an urging means is connected to the supporting frame so that the separating roller is urged so as to come into pressure contact with the sheet feeding roller. The separating roller is configured such that a drive torque in a direction opposite to the sheet conveying direction is applied to the separating roller from a support shaft of a support frame or a drive shaft on a coaxial center by gear transmission means via a torque limiter. In the paper feeding device of the image forming apparatus, the torque applied to the drive shaft and the moment around the support shaft due to the frictional force acting on the surface of the separating roller from the paper feeding roller side have opposite directions. To so that is obtained by forming the gear transmission unit. In particular, it is preferable to configure the gear transmission means so that the torque and the moment have the same magnitude and opposite directions.

[0009]

The rotation driving force of the drive shaft is transmitted to the separating roller via the gear transmission means, and the separating roller is given a driving torque in the direction opposite to the sheet conveying direction. At this time, the torque transmitted to the separating roller side is limited by the torque limiter interposed in the gear transmission means drivingly connected to the drive shaft. The drive torque applied to the drive shaft tends to rotate the support frame provided so as to be swingable around the support shaft. Since the gear transmission means is configured so that the moment is in the opposite direction to the torque applied to the drive shaft, the moment due to the frictional force from the side of the paper feed roller applied to the surface of the separating roller and the moment are driven. The torque applied to the shaft will cancel each other out. As a result, the separating roller is pressed against the paper feeding roller by a constant urging force of the urging means connected to the supporting frame, and even if the torque transmitted by the torque limiter fluctuates periodically, the separating roller is separated from the paper feeding roller. The fluctuation of the pressure contact force of is reduced. In the above case, in particular, by configuring the gear transmission means so that the moment and the torque are equal in magnitude and opposite in direction, the influence of fluctuations in the torque transmitted by the torque limiter can be completely eliminated.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first sheet feeding device of an image forming apparatus according to the present invention.
In the embodiment, the same numbers are given to members having the same functions as those of the conventional example shown in FIG. In FIG. 1, as in the conventional example, a sheet feeding device 15 feeds out a sheet 2 stored in a sheet feeding tray 1 from a sheet feeding side thereof, and a pickup roller 3 which is rotationally driven around a spindle 3A, It is configured by combining with a sheet separating mechanism 17 located at the downstream portion thereof, and is provided so as to send out the sheets 2 one by one toward the sheet conveying path 11. The paper separating mechanism 17 includes a paper feeding roller 4 arranged at a fixed position on the downstream side of the pickup roller 3.
And a separating roller 5 facing the paper feeding roller 4, and is in contact with the upper surface of the paper 2 in the paper feeding direction.
The separating roller 5 is configured to contact the lower surface of the sheet 2 with respect to the sheet feeding roller 4 which is rotatably driven around the axis A, and a driving torque is applied in a direction of returning the sheet 2 around the support shaft 5A. ing.

The supporting shaft 5A of the separating roller 5 is a drive shaft 7A.
Is attached to a support frame 9 which is swingably supported by a support shaft, and an idle gear which is rotatably supported by an idle gear shaft 8A on the drive gear 7 and the support frame 9 provided on the drive shaft 7A. A gear transmission means 16 composed of a gear 8 and a separating roller gear 6 provided on the support shaft 5A together with the separating roller 5 is configured to transmit the driving torque applied to the drive shaft 7A to the separating roller 5. ing. A bracket 9A is formed on the support frame 9 so as to project from a lower portion of the support frame 9 on the side opposite to the separating roller 5 side with respect to the drive shaft 7A. The bracket 9A is provided on the image forming apparatus main body side. A coil spring 1 as a biasing means is provided between the coil spring fixing portion 12 and the coil spring fixing portion 12.
0 is stretched. As shown in FIG. 2, the gear transmission means 16 has a torque limiter 13 interposed between the drive shaft 7A and the drive gear 7, and slips when the drive torque applied to the drive shaft 7A is a certain value or more. Is configured.

FIG. 3 shows a direction in which a force applied to each part of the paper separating mechanism 17 having the above-described structure acts, and the driving torque externally applied to the driving shaft 7A is as follows. The torque is limited to a value less than or equal to the value set by the torque limiter 13 and transmitted to the drive gear 7, and at the meshing portion between the drive gear 7 and the idle gear 8, as shown in FIG. A force X acts on the separating roller gear 6 via the idle gear 8 to rotate the separating roller 5 rotated integrally with the separating roller gear 6 in the counterclockwise direction. Try to. On the other hand, the separating roller gear 6 receives the tangential frictional force F at the contact position P with the paper feeding roller 4 rotating counterclockwise. Further, the support frame 9 includes the bracket 9A and the coil spring fixing portion 1
The urging force Y is received from the coil spring 10 connected between the two.

As shown in FIG. 4, the center O2 of the drive shaft 7A, which is the swinging fulcrum of the support frame 9, is located at the paper feed roller 4.
The contact position P with the separation roller 5 is provided at a position displaced downward by a vertical distance a with respect to the tangential direction.
Further, the radius R from the center O1 of the support shaft 5A on the outer peripheral surface of the separating roller 5 and the radius r1 of the pitch circle of the separating roller gear 6
, And the radius r2 of the pitch circle of the drive gear 7 are set so that r2 / r1 = a / R. Then, the force X is transmitted by the idle gear 8 and acts on the meshing position between the idle gear 8 and the separating roller gear 6, and the radius r1 of the pitch circle of the separating roller gear 6 and the radius R of the separating roller 5 are applied. Due to the relationship with the contact position P, the separation roller gear 6 is moved to the paper feeding roller 4 at the contact position P.
A force of magnitude X. (r1 / R) acts on the side in the direction opposite to the paper feeding direction, and as a reaction force of the force, the separating roller 5
Receives a force F in the paper feed direction from the paper feed roller 4 side. Therefore, the magnitude of the force F is equal to X (r1 / R), and the force F causes the support frame 9 to generate a clockwise moment aF = aX with respect to the swing fulcrum O2.
・ Receive (r1 / R). Further, the support frame 9 is O
The counterclockwise drive torque from the drive gear 7 is received in two turns. This is because the pitch circle radius of the drive gear 7 is r2.
Therefore, the size is r2.X. From the above relationship, since r2 = r1. (A / R), the magnitude of the driving torque that the support frame 9 receives from the driving gear 7 is aX. (R1 / R), and the moment is The moment that acts on the support frame 9 by canceling out the drive torque applied to the drive gear 7 from the drive shaft 7A is only due to the biasing force of the coil spring 10. Since the above relationship holds regardless of the magnitude of the drive torque applied to the drive shaft 7A, the torque limiter 1
Even if the transmission torque of No. 3 changes periodically, the moment acting on the support frame 9 is only due to the urging force of the coil spring 10, and the influence due to the change of the transmission torque is eliminated.

Next, FIG. 5 shows a second embodiment of the present invention. In this embodiment, the position of the drive shaft 7A is located upstream of the separating roller 5 in the sheet conveying direction. It is located in. A bracket 9A is provided on the lower portion of the support frame 9 on the side of the paper feed tray 1, and a coil spring 10 is provided between the bracket 9A and the coil spring fixing portion 12 fixed to the main body of the image forming apparatus. It is installed horizontally. The coil spring 10
Biases the support frame 9 swingably supported about the drive shaft 7A so as to rotate in the counterclockwise direction in FIG. 5, and the biasing force causes the paper feed roller 4 to rotate. On the other hand, the separating roller 5 is pressed. A torque limiter 13 is interposed between the drive shaft 7A and the drive gear 7 as in the above-described first embodiment. When a load torque of a certain magnitude or more is applied, the torque limiter 13 is applied to the drive shaft 7A. The drive gear 7 side is configured to slip.

In the present embodiment, contrary to the case of the first embodiment described above, the drive torque applied to the drive gear 7 from the drive shaft 7A causes the support frame 9 and the feed roller 4 to move. On the other hand, the counterclockwise rotational force, which is the direction in which the separation roller 5 is pressed, acts, and the frictional force that acts on the support frame 9 from the paper feed roller 4 side is
The support frame 9 acts so as to rotate clockwise. Also in the case of this embodiment, as in the case of the above-described first embodiment, driving by the drive torque applied to the drive shaft 7A and the frictional force acting on the surface of the separating roller 5 from the sheet feeding roller 4 side. The moment around axis 7A is
By configuring the gear transmissions so that the magnitudes are the same and the directions are opposite, fluctuations in the drive torque of the torque limiter 13 can be eliminated.

In each of the embodiments described above, the torque limiter 13 is shown as being interposed between the drive shaft 7A and the drive gear 7, but the position where the torque limiter 13 is provided is determined by the gear transmission means 16. It may be provided between the separation roller 5 and the drive shaft 7A. Further, in each of the above-described embodiments, one idle gear 8 is used in the gear transmission means 16, but the invention is not limited to this, and the drive torque applied to the drive shaft 7A and the separation roller 5 are not limited thereto. It suffices that the gear transmission means be configured such that the direction of the moment about the drive shaft 7A due to the frictional force acting on the surface from the paper feed roller 4 side is opposite. And
Although the drive shaft 7A also serves as the support shaft of the support frame in the above-described embodiment, the support shaft and the drive shaft 7A may be separately provided on the same axis. Further, in each of the above-mentioned embodiments, the gear transmission means 16 is set so that the drive torque applied to the drive shaft 7A and the moment around the drive shaft 7A acting on the support frame 9 are equal in magnitude and opposite in direction. However, even if the sizes are not made equal, if the directions are opposite, the effect of reducing the torque fluctuation acting on the support frame 9 can be obtained.

[0017]

As described above, according to the present invention,
Since the gear transmission is configured so that the torque applied to the drive shaft and the moment around the support shaft of the support frame due to the frictional force acting on the surface of the separation roller from the paper feed roller side are opposite in direction, the separation roller Moments acting on the support frame that supports the parts other than the biasing means are reduced. As a result, the influence of torque fluctuation due to the torque limiter interposed in the drive transmission system that drives the separating roller is reduced, and the holding portion of the sheet feeding roller and the support frame supporting the separating roller are affected by the torque fluctuation. Vibration and noise are prevented, and fluctuations in the contact force of the separation roller with respect to the paper feed roller are reduced,
A stable paper feeding operation can be performed. In particular, when the gear transmission means is configured such that the torque and the moment have the same magnitude and opposite directions, the influence of the torque fluctuation can be completely eliminated. Optimum sheet feeding operation can be performed by a constant moment of only.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of a paper feeding device of the present invention.

FIG. 2 is a plan view showing a configuration of a drive system of a paper separating roller of the paper feeding device shown in FIG.

FIG. 3 is a diagram showing an action direction of a force applied to each part of a paper separating mechanism in the paper feeding device of FIG.

FIG. 4 is a diagram showing a positional relationship of respective members of a paper separating mechanism in the paper feeding device of FIG.

FIG. 5 is a side view showing a second embodiment of the paper feeding device of the present invention.

FIG. 6 is a side view showing an example of a conventional paper feeding device.

FIG. 7 is a diagram showing an action direction of a force applied to each part of the paper separating mechanism in the paper feeding device shown in FIG.

[Explanation of symbols]

1 paper feed tray, 2 paper, 3 pickup roller, 4 paper feed roller, 5 separation roller,
6 Separation roller gears, 7 Drive gears, 8
Idle gear, 9 support frame, 10 coil spring, 11 paper transport path, 12 coil spring fixing part, 13 torque limiter, 15 paper feeding device,
16 gear transmission means, 17 paper separating mechanism.

Claims (2)

[Claims] 1. A support roller is disposed so as to face a paper feed roller that is rotationally driven in the paper transport direction, and the separation roller is supported so as to be swingable in the contact and separation directions with respect to the paper feed roller. The support frame is pivotally supported, and an urging means is connected to the support frame to urge the separating roller so that the separating roller is pressed against the paper feeding roller. The separating roller is a gear transmission means via a torque limiter. In the sheet feeding device of the image forming apparatus, the driving torque in the direction opposite to the sheet conveying direction is applied to the separating roller from the supporting shaft of the support frame or the coaxial driving shaft by the driving shaft. The gear transmission means is configured such that the applied torque and the moment around the support shaft due to the frictional force acting on the surface of the separating roller from the paper feed roller side are opposite in direction. Sheet feeding device of an image forming apparatus according to claim and. 2. The gears so that the torque applied to the drive shaft and the moment around the support shaft due to the frictional force acting on the surface of the separating roller from the paper feed roller side are equal in magnitude and opposite in direction. The sheet feeding device of the image forming apparatus according to claim 1, wherein the sheet feeding device is configured.