JP2830135B2 - Feeding device for recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] In an image forming apparatus for feeding and holding a recording medium to a conveying member for holding and conveying a recording medium and conveying the recording medium to a recording position of a recording unit, the present invention relates to an apparatus for feeding a recording medium. A recording medium feeding device that feeds a recording medium to a transport member that grips and transports a recording medium by a gripping portion, and feeds the recording medium toward the gripping portion, and a part of the periphery thereof is provided. A feeding roller having a cut-out portion having a smaller diameter than other portions, and a roller drive control means for controlling rotation of the feeding roller, wherein the roller drive control means is configured such that the leading end of the fed recording medium is After being gripped by the gripping portion, the cutout portion of the feeding roller is configured to rotate so as to face the recording medium.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus in which a conveying member that grips and transports a recording medium feeds out and grips the recording medium, and transports the recording medium to a recording position of a recording unit. The present invention relates to a recording medium feeding device that removes recording distortion caused by bending.

In an image forming apparatus using an electrophotographic method, in particular, in a recording medium conveyed on a belt using a plurality of photosensitive drums, that is, in a color recording apparatus that forms a color image on recording paper, for example, By using a conveyance member called a gripper, the recording paper is gripped by the gripper and conveyed on a belt, passed through the image transfer position of each photosensitive drum, a toner image is transferred onto the recording paper, and then fixed. , And a color image is recorded.

This color recording apparatus normally uses four photosensitive drums, and forms yellow, magenta, cyan, and black color toner images on each photosensitive drum. First, yellow, then magenta, and then After the cyan and finally black color toner images are transferred, they are fixed.

For this reason, it is necessary to feed out the recording paper from the paper cassette in synchronization with the movement of the clipper, and to make the gripper securely grip the recording paper. Therefore, the recording paper fed from the paper cassette is sandwiched between the registration rollers, and the gripper grips the recording paper, so that when the gripper reaches an optimal position for feeding the recording paper, the registration roller is rotated. The recording paper is fed at a speed slightly higher than the belt conveyance speed.

Therefore, bending occurs after the recording paper is gripped by the gripper, and the recording paper is pushed into the image transfer position of the photosensitive drum for transferring the yellow color toner image due to the bending. The gap occurs,
This shift needs to be prevented in order to reduce the quality of the color image.

[Conventional technology]

 FIG. 8 is a diagram for explaining an example of the prior art.

FIG. 8 shows an example of a color recording apparatus using four photosensitive drums. Y, M, C, and K constitute printing units for printing yellow, magenta, cyan, and black, respectively. Denotes a photosensitive drum, 2 denotes a cleaner, 3 denotes a charger, 4 denotes, for example, a laser beam sent from an exposure system, 5 denotes a developing device, and 6 denotes a transfer device.

The photosensitive drum 1 is cleaned of residual toner by a cleaner 2, and
An electrostatic latent image is formed by projecting the modulated laser beam 4 on the surface charged by the charger 3. Then, the electrostatic latent image is developed by the toner supplied from the developing device 5 by attaching the toner having each color.

The developed toner image is transferred by a transfer unit 6 onto a recording sheet conveyed between the transfer unit 6 and the photosensitive drum 1. The recording sheet is stored in a recording sheet cassette 7 and fed out by a feeding roller. 9, the sheet is fed out of the recording paper cassette 7 and, as shown in the recording paper 8, registration rollers 10 and 11.
Waiting in the state of being hit by.

When the gripper 14, which is driven by the driving pulley 12 and is attached to the belt 13 traveling in the direction of arrow A, reaches an optimal preparation position for gripping the recording paper 8, for example, the registration roller 10 By being driven to rotate, the registration rollers 10 and 11 rotate, and the recording paper 8 is fed out to the gripper 14 at a speed slightly higher than the running speed of the belt 13.

Therefore, the recording paper 8 is fed out from the gripper 14 so as to chase from behind, and the leading end thereof is inserted. When the leading end of the recording paper 8 is inserted, the gripper 14 grips and transports the recording paper 8.

Reference numeral 15 denotes a gripper indicating a state in which the recording paper is gripped, and reference numeral 17 denotes a recording paper gripped by the gripper 15 and being conveyed. The recording paper 17 gripped and conveyed by the gripper 15 has a belt
Along with the movement of 13, the transfer units 6 of the printing units Y, M, C, K sequentially transfer the toner images in an overlapping manner.

When the gripper 15 passes the position of the transfer unit 6 of the printing unit K, the gripping of the recording paper 17 is released by a cam mechanism not shown. Then, as shown in the gripper 16, the recording paper 8
Is conveyed to grasp it.

The recording paper 17 released from the gripper 15 is attracted to the photosensitive drum 1 by the electrostatic force applied from the transfer unit 6 of the printing unit K, and the belt 13 is rotated by the rotation of the photosensitive drum 1.
At the same time, it is conveyed and enters the fixing device 32. The color toner image is fixed on the recording paper 17 by the heat from the fixing roller 18 and the pressure from the pressure roller 19.

[Problems to be solved by the invention]

FIG. 9 is a view for explaining the bending of the recording paper due to the feeding of the registration roller.

The paper is fed out of the recording paper cassette 7 and the registration rollers 10
When the gripper 14 reaches the preparation position where the gripper 14 grips the recording paper 8,
It is fed out by the rotation of the registration rollers 10 and 11.

The preparation position where the gripper 14 grips the recording paper 8 is determined by a gripper detection sensor 20 that detects the position of the gripper 14 that has been conveyed along with the movement of the belt 13 by, for example, contacting the tip of a lever. When the position of the gripper 14 is detected, the determination is made based on a time determined in advance from the moving speed of the belt 13.

Then, when the leading end of the recording paper 8 fed out at a speed slightly higher than the predetermined speed is inserted into the gripper 14 indicated by a dotted line conveyed at a predetermined speed by the belt 13 in the direction of arrow A, the gripper 14 is moved. Grips and conveys the recording paper 8. In this way, the feeding speed of the recording paper 8 is
The reason why the speed is slightly higher than the transport speed is to ensure that the leading end of the recording paper 8 is inserted into the gripper 14.

Therefore, when the gripper 14 grips the recording paper 8, the recording paper 8 that has been fed out more than necessary bends. After the gripping of the recording paper 8 is completed, the rotation speed of the registration rollers 10 and 11 becomes a constant speed rotation (a rotation speed at which the recording paper 8 can be fed out in synchronization with the transport speed of the belt 13), and the feeding of the recording paper 8 is completed Then, the rotation is stopped, but since this bending is not eliminated, as shown by the solid line, after the gripper 14 passes between the photosensitive drum 1 of the printing unit Y and the transfer unit 6, the bending causes the recording paper 8 to move the photosensitive drum 1 A force that is pushed between the transfer device 6 and the transfer device 6 acts.

Therefore, the moving speed of the recording paper 8 at the transfer position of the printing unit Y becomes higher than the predetermined speed, that is, the conveying speed of the belt 13. Accordingly, the recording position of the toner image transferred by the printing unit Y is shifted from the recording position of the toner image transferred by the printing units M, C, and K to be transferred thereafter.

Therefore, there is a problem that the quality of a printed image is reduced.

The present invention has been made in view of the above-described problems, and an object of the present invention is to prevent a deterioration in image quality by eliminating the bending of the recording paper 8.

[Means for solving the problem]

 FIG. 1 is a diagram for explaining the principle of the present invention.

(1) The present invention provides a gripping part (included in the conveying member 34 in FIG. 1).
A feeding device for feeding the recording medium 36 to a transport member 34 that grips and transports the recording medium 36, and feeds the recording medium 36 toward the grip portion, and a part of the periphery thereof. Has a cut-out portion having a cut-out portion having a diameter smaller than that of the other portion (corresponding to the feed-out means 35), and a roller drive control means for controlling the rotation of the feed-out roller. After the leading end of the recording medium 36 is gripped by the gripping section, the cutout portion of the feeding roller rotates so as to face the recording medium 36.

[Action]

The roller drive control means stops the feeding roller so that the peripheral length up to the notch portion becomes the feeding length required for gripping by the transport member 34, and when the transport member 34 reaches a predetermined position, The rotation of the feeding roller is started, and the held recording medium 36 is fed at a speed higher than the conveying speed of the conveying member 34. At the point in time when the recording medium 36 abuts against and is gripped by the conveying member 34, the notch of the feeding roller faces the recording medium 36, so that the holding of the recording medium 36 by the feeding roller is released, and the conveying member 34 and the feeding roller The bending of the recording medium 36 occurring during the period is eliminated.

Therefore, the bending of the recording medium 36 causes the recording medium
Since the force for pushing the 36 into the recording position of the recording means 33 disappears, it is possible to prevent the image quality from lowering.

〔Example〕

FIG. 2 is a block diagram of a circuit showing one embodiment of the present invention, FIG. 3 is a time chart for explaining the operation of FIG. 2, and FIG. 4 is a diagram for explaining the operation of the registration roller.

As described with reference to FIG. 9, when the control circuit 21 receives a signal indicating that a gripper has been detected from the gripper detection sensor 20 as indicated by the gripper detection signal in FIG.
In response, a drive signal is transmitted as shown in FIG.

For this reason, the feed roller driving circuit 22 drives the motor 23 to rotate the feed roller 9, and feeds the recording paper 8 out of the recording paper cassette 7 as shown in FIG. The recording paper 8 is abutted between 10 and 26.

When the control circuit 21 determines that the predetermined time has elapsed since the gripper detection signal was received and the gripper 14 has reached the preparation position for gripping the recording paper 8, the control roller 21 drives the registration roller as shown in FIG. A drive signal is transmitted to the circuit 24.

For this reason, the registration roller drive circuit 24 drives the motor 25 to move the registration roller 26 as shown in FIG.
Rotate in the direction of the arrow. Accordingly, with the rotation of the registration roller 26, the registration roller 10 also rotates, and the recording paper 8 is fed. At this time, the gripper 14 is at the position shown in the figure and has advanced beyond the leading end of the recording paper 8.

The speed at which the registration rollers 10 and 26 pay out the recording paper 8 is as follows.
Since it is slightly faster than the transport speed of the gripper 14, FIG. 4 (c)
As shown in (1), the leading end of the recording paper 8 is inserted into the gripper.

As shown in the drawing, for example, the registration roller 26 has a radius of a part of the roller smaller than a predetermined radius, and the circumference of the portion having the predetermined radius is the gripper in the state shown in FIG. Assuming that the distance from 14 to the contact point between the registration rollers 10 and 26 is L, the distance is slightly larger than L.

Therefore, the recording paper 8 is fed out a little faster than the transport speed of the gripper 14 until the portion where the radius of the registration roller 26 is small is opposed to the registration roller 10, so that FIG.
As shown by the dotted line in FIG.

However, when the portion of the registration roller 26 having a small radius faces the registration roller 10, the control circuit 21 counts a preset time and sends it to the registration roller drive circuit 24 as shown in FIG. In order to stop the driving signal, the registration rollers 10 and 26 are kept released from nipping the recording paper 8 as shown in FIG. 4 (d).

Accordingly, as shown by the solid line, the recording paper 8 releases the bending, and therefore, no deviation of the recording position occurs in the transferred toner image.

The control circuit 21 sends a drive signal to the registration roller driving circuit 24 to count the time when the recording paper 8 is no longer present between the registration rollers 10 and 26 as shown in FIG. Then, as shown in FIG. 4 (e), control is performed such that a portion of the registration roller 26 having a predetermined radius faces the registration roller 10. Then, it waits for the next recording paper 8 to be paid out.

FIG. 5 is a block diagram of a circuit showing another embodiment of the present invention, FIG. 6 is a time chart for explaining the operation of FIG. 5, and FIG. 7 is a diagram for explaining the operation of the electromagnetic solenoid.

When the control circuit 21 receives the gripper detection signal from the gripper detection sensor 20 as shown in FIG. 9 as shown in FIG.
A drive signal is sent to the feed roller 22 as shown in FIG.

For this reason, the feed roller driving circuit 22 drives the motor 23 to rotate the feed roller 9 to feed the recording paper 8 out of the recording paper cassette 7 as shown in FIG. During this time, the recording paper 8 is hit.

When the control circuit 21 determines that the predetermined time has elapsed since the gripper detection signal was received and the gripper 14 has reached the preparation position for gripping the recording sheet 8, the control circuit 21 drives the registration roller as shown in FIG. A drive signal is transmitted to the circuit 24.

For this reason, the registration roller drive circuit 24 drives the motor 25 to rotate the registration roller 11. Accordingly, with the rotation of the registration roller 11, the registration roller 10 also rotates, and the recording paper 8 is fed. At this time, the gripper 14 has advanced beyond the leading end of the recording paper 8 as described above.

The speed at which the registration rollers 10 and 11 pay out the recording paper 8 is as follows.
Since it is slightly faster than the transport speed of the gripper 14, as described above,
The leading end of the recording paper 8 is inserted into the gripper 14.

As shown in FIG. 6, the control circuit 21 counts the time from when the gripper detection signal is received to when the predetermined tip of the gripper 14 is gripped by the gripper 14. The drive current is supplied to the solenoid 28, and the registration roller 11 is separated from the registration roller 10.

The electromagnetic solenoid 28 pulls the registration roller 11 via a spring 31, for example, as shown in FIG. The registration roller 11 is attached to a column 29 that rotates about a fulcrum 30, and is separated from the fixedly attached registration roller 10 by pulling an electromagnetic solenoid 28.

As described above, the rotation of the registration rollers 10 and 11 causes the recording paper 8 to be fed out at a speed slightly higher than the transport speed of the gripper 14, so that bending occurs.

However, when the registration roller 11 is separated from the registration roller 10, the registration rollers 10 and 11 release the nipping of the recording paper 8.

Therefore, since the recording paper 8 releases the bending, the recording position of the transferred toner image does not shift.

The control circuit 21 controls the recording paper 8 as shown in FIG.
When a predetermined time is counted up until the solenoids depart from the positions of the registration rollers 10 and 11, the drive signal sent to the solenoid drive circuit 27 is stopped, and the electromagnetic solenoid 28 is stopped.
Releases the separation of the registration roller 11.

In the present embodiment, the transfer member has been described as a gripper.
The present invention is not limited to this, and it is needless to say that the present invention is also applied to a device that grips recording paper by static electricity, such as an electrostatic attraction belt.

〔The invention's effect〕

As described above, the present invention eliminates the bending that occurs on the recording paper, so that it is possible to prevent the transfer position of the toner image from being shifted. Therefore, it is possible to prevent a decrease in image quality.

[Brief description of the drawings]

1 is a diagram for explaining the principle of the present invention, FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention, FIG. 3 is a time chart for explaining the operation of FIG. 2, and FIG. FIG. 5 is a block diagram of a circuit showing another embodiment of the present invention, FIG. 6 is a time chart for explaining the operation of FIG. 5, and FIG. 7 is a diagram showing the operation of the electromagnetic solenoid. FIG. 8 is a diagram for explaining an example of the prior art, and FIG. 9 is a diagram for explaining the bending of the recording paper due to the feeding of a registration roller. In the figure, 1 is a photosensitive drum, 2 is a cleaner, 3 is a charger, 4 is a laser beam, 5 is a developing device, 6 is a transfer device, 7 is a recording paper cassette, 8 and 17 are recording paper, 9 is a feeding roller, 10, 11, and 26 are registration rollers, 12 is a drive pulley, 13 is a belt, 14, 15, and 16 are grippers, 18 is a fixing roller, 19 is a pressure roller, 20 is a gripper detection sensor, 21 is a control circuit, and 22 is a control circuit. Paper feed roller drive circuit, 23 and 25 are motors, 24 is a registration roller drive circuit, 27 is a solenoid drive circuit, 28 is an electromagnetic solenoid, 29 is a column, 30 is a fulcrum, 31 is a spring, 32 is a fuser, and 33 is a record Means, 34 is a conveying member, 35 is feeding means, and 36 is a recording medium.

Claims (1)

(57) [Claims] An apparatus for feeding a recording medium to feed a recording medium to a transport member that grips and transports the recording medium by a gripping part, wherein the recording medium is fed toward the gripping part.
A feed roller having a cut-out portion in which a part of its periphery is smaller in diameter than other portions; and a roller drive control means for controlling the rotation of the feed roller, wherein the roller drive control means is fed out. An apparatus for feeding a recording medium, characterized in that, after the leading end of the recording medium is gripped by the gripping portion, the cutout portion of the feeding roller rotates so as to face the recording medium.