JP2001013842A - Photoreceptor drive controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the wear of a nip part caused by a speed difference between a photoreceptor and an intermediate transfer belt, by switching a drive signal for an intermediate transfer motor to stop and, at the same time, applying a brake to a photoreceptor motor only for a specific length of time. SOLUTION: In response to a Job completion signal from a CPU 23, a drive signal for an intermediate transfer motor 21 is switched from Low (start) to High (stop), at the same time, a drive signal for a brake means 20 is switched from Low (start) to High (stop) for only a length of X (msec) time, and a short brake is applied to a photoreceptor motor 18 for only the length of X time. Subsequently, in order to reset the short brake, a photoreceptor motor trigger is made High (stop) only for a short time, for example, about 20 (msec) and thereafter made Low (start). After a reverse rotation signal (Low) is inputted to the photoreceptor motor 18 only for a length of Y (msec) time in synchronization with the Low (start) signal, the photoreceptor motor trigger is made High (stop) and stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine using the intermediate transfer method. Specifically, in an image forming apparatus that separately drives the photoconductor and the intermediate transfer belt,
The present invention relates to a photoconductor drive control device for synchronizing a stop operation of a photoconductor with that of an intermediate transfer belt.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a configuration around a photoreceptor in a conventional image forming apparatus using an intermediate transfer system.
In the figure, 0 is a photosensitive drum, 1 is a charging section, 2 is a charge removing section, 3 is a photosensitive body cleaning section, 4 is a PPC (pre-cleaning charge) section, 5 is an intermediate transfer section, 6 is a paper transfer section, 7 Denotes a belt cleaning / lubricant application unit, 8 denotes a paper transfer belt cleaning unit, 9 denotes a paper transfer belt static elimination unit, 1
0 is a paper separation unit, 11 is a pattern detection unit, 12 is a development unit,
Reference numeral 13 denotes a potential detection unit, and 14 denotes an exposure unit. The function of each part is as follows.

Charging unit 1 In the dark, the photosensitive drum 0
Is charged negatively, and the potential on the photosensitive drum 0 is kept constant by the grid.

After cleaning, the entire surface is exposed by a QL lamp (red LED) in order to erase residual charges on the photosensitive drum 0 to prepare for the next copy.

Photoreceptor cleaning section 3 By applying a lubricant to photoreceptor drum 0 with a cleaning brush, the cleaning property of photoreceptor drum 0 is improved, and the toner remaining on photoreceptor drum 0 is removed by a cleaning blade. Scrape off.

The PPC unit 4 responds to the reduction of the first copy time, and
In order to increase the margin for the static elimination and cleaning, AC and negative DC discharge are performed to improve the brush cleaning performance.

The intermediate transfer unit 5 transfers the negatively charged toner image on the photosensitive drum 0 to the intermediate transfer belt 15 by applying a positive charge from the back surface of the intermediate transfer belt 15.

Paper transfer unit 6 The toner image on the intermediate transfer belt 15 is transferred to a paper using a dielectric bias application method. For paper transfer bias,
The constant current bias method is adopted.

Belt cleaning / lubricant application unit 7 A lubricant is applied to the intermediate transfer belt 15 by a brush,
The releasability of the intermediate transfer belt 15 is improved, and the toner is scraped off with a counter blade.

Paper transfer belt cleaning section 8 The blade and the brush roller are constantly brought into contact with the surface of paper transfer belt 16 to clean the surface of the paper transfer belt.

Paper transfer belt static eliminator 9 In order to eliminate the charge on the paper transfer belt 16, a belt neutralization charger facing the drive roller is provided, and the paper transfer belt 16 is neutralized.

Paper separation unit 10 In order to separate the paper, in addition to the curvature separation between the intermediate transfer belt 15 and the paper transfer bias roller, the paper is discharged by a paper discharging charger and the separation is performed by a separation claw. By moving the paper discharging position away from the paper transfer nip, the effect of paper discharging on the paper transfer area is avoided.

Pattern detecting unit 11 A batch pattern developed on the photosensitive drum 0 is detected by a sensor. The data detected by this sensor is
The process condition is controlled by being converted into the toner amount of the photosensitive drum 0.

Developing section 12 A developing bias is applied to the toner charged by triboelectric charging, and the toner adheres to a portion on the photosensitive drum 0 where the electric charge is lower (absolute value) than the developing bias.

Potential detector 13 The surface potential of photosensitive drum 0 is read by a potential sensor to control process conditions.

Exposure section 14 The laser beam emitted from the laser is reflected by a polygon mirror, passes through an fθ lens, a writing mirror, and dust-proof glass, and is projected onto photosensitive drum 0. The laser output forms a latent image depending on the intensity corresponding to the image portion.

[0017]

In the above, the photosensitive drum 0 is driven by a photosensitive motor and the intermediate transfer belt 15
Are driven separately by the intermediate transfer motor,
There were the following problems.

That is, at the end of the copy operation, the drive of the photosensitive drum motor and the drive of the intermediate transfer motor are stopped at the same time.
In order to suppress the speed fluctuation of the photosensitive drum, the photosensitive drum is provided with a large inertia such as a flywheel so that the driving of the photosensitive drum is stopped with respect to the stop time of the driving of the intermediate transfer belt. The time was getting longer.

FIG. 2 is a diagram showing the transition. When the photosensitive drum motor and the intermediate transfer motor are stopped and controlled in synchronization with the end of the job, the stop time of the photosensitive drum is the flywheel inner time. Shading indicates that the time is slower than the stop time of the intermediate transfer belt. For this reason, the photosensitive drum 0 and the nip portion 17 of the intermediate transfer belt 15 are rubbed with each other, causing a problem that the photosensitive drum 0 is damaged and scars appear on an image.

Therefore, an object of the present invention is to prevent rubbing at a nip portion due to a speed difference between a photosensitive member and an intermediate transfer belt,
The purpose is to suppress the occurrence of scratches on the photoconductor.

[0021]

Therefore, in the invention according to claim 1, the photosensitive member is separated by a photosensitive member motor, and the intermediate transfer belt for transferring the toner image on the photosensitive member is separated by an intermediate transfer motor. The image forming apparatus is provided with a brake means for switching the drive signal of the intermediate transfer motor to a stop state and, at the same time, applying a brake to the photoreceptor motor for a predetermined time.

In the case where only a predetermined time of braking is applied to the photoreceptor motor as described above, if the inertia of the flywheel provided on the photoreceptor shaft is large, the photoreceptor motor will be shaken. In some cases, the inertia of the flywheel is superior to the key, and it is difficult to synchronize the stop time. That is, as shown in FIG. 3, the stop speeds of the photoconductor and the intermediate transfer belt are substantially equal, but the stop time of the photoconductor is slightly longer.

Therefore, in the invention according to claim 2, after the brake is operated for a predetermined time by the brake means, the photoreceptor motor is reversely driven for a predetermined time by the photoreceptor motor control means to apply a reverse rotation brake.

However, the photoreceptor motor has a reverse rotation blur.
If the key is applied first, the speed of the photoconductor suddenly decreases as shown in FIG. 4, so that the speed difference from the intermediate transfer belt increases, and even if the stop time can be synchronized, the photoconductor is damaged. May be caused.

Therefore, in the invention according to claim 3, after the braking operation by the braking means for a predetermined time, the photosensitive motor control means switches the drive signal of the photosensitive motor to stop for a short time and then reverses the rotation of the photosensitive motor. Drive. That is, immediately after the short brake is applied to instantaneously stop and control the forward rotation of the photosensitive motor, the reverse rotation brake is applied.

In this manner, as shown in FIG. 5, the transition of the attenuation of the rotation of the photosensitive member and the transition of the attenuation of the intermediate transfer belt become substantially the same, and both stop completely at the same time.

[0027]

Next, an embodiment of the present invention will be described.

The mechanical configuration of this embodiment is the same as that of FIG. 1, but the configuration of the control system of the photoconductor motor and the intermediate transfer motor is different from the conventional one. FIG. 6 is a block diagram of the control system, and FIG. 7 is a timing chart of the operation.

In FIG. 6, a photoreceptor motor 18 for rotating the photoreceptor is controlled in both forward and reverse directions by a photoreceptor motor control means 19 and brakes the normal rotation by a brake means 20. Can be hung. The intermediate transfer motor 21 that rotates the intermediate transfer belt is controlled by an intermediate transfer motor control unit 22. The brake unit 20, the photoconductor motor control unit 19, and the intermediate transfer motor control unit 22 operate according to instructions from the CPU 23.

An operation example will be described with reference to FIG.
In response to the Job end signal from U23, the intermediate transfer motor 2
At the same time, the drive signal of the brake unit 20 is switched from low (start) to high (stop) at the same time as switching the drive signal of (1) from low (start) to high (stop).
(msec) time, and a short brake is applied to the photoreceptor motor 18 for X (msec) time.

Thereafter, for a short brake reset, the photoreceptor motor trigger is set to High (stop) only for a short time, for example, for about 20 (msec).
w (start). In synchronization with the Low (start) signal, the reverse rotation signal (Low) is supplied to the photoconductor motor 18 by Y (m).
sec) After the time has elapsed, the photoreceptor motor trigger is set to Hi.
gh (stop) and stop.

[0032]

The effects of the present invention can be listed for each claim.
It is as follows. According to the first aspect of the present invention, the photoreceptor motor is braked to eliminate the difference in the stop time between the intermediate transfer belt and the photoreceptor and to eliminate the speed difference. Rubbing can be prevented and generation of scratches on the photoreceptor can be suppressed.

Advantageous Effects of the Invention Even when a large inertia body such as a flywheel is provided on the photoreceptor, the stop time of the photoreceptor can be reduced to the stop time of the intermediate transfer belt by using two types of brakes together. It becomes possible to synchronize.

According to the third aspect of the present invention, the short brake time is adjusted so that the stop speed of the photosensitive member is adjusted to the stop speed of the intermediate transfer belt, and when the rotation speed is sufficiently reduced, reverse rotation brake is performed. Since the stop time is synchronized by inserting, the occurrence of rubbing between the photoconductor and the intermediate transfer belt can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram around a photoconductor in a conventional image forming apparatus using an intermediate transfer method.

FIG. 2 is a stop speed curve diagram of the photosensitive member and the intermediate transfer belt when the photosensitive member motor is stopped without applying a brake.

FIG. 3 is a diagram showing a stop speed curve of the photosensitive member and the intermediate transfer belt when a short brake is applied to the photosensitive member motor.

FIG. 4 is a stop speed curve diagram of the photosensitive member and the intermediate transfer belt when a reverse rotation brake is applied to the photosensitive member motor.

FIG. 5 shows a photoreceptor motor after a short brake.
FIG. 7 is a stop speed curve diagram of the photosensitive member and the intermediate transfer belt when reverse rotation braking is applied.

FIG. 6 is a block diagram of a control system of a photoconductor motor and an intermediate transfer motor according to the present invention.

FIG. 7 is a timing chart of an operation example of the control system.

[Explanation of symbols]

 0 Photoconductor 15 Intermediate transfer belt 18 Photoconductor motor 19 Photoconductor motor control means 20 Brake means 21 Intermediate transfer motor 22 Intermediate transfer motor control means 23 CPU

Claims (3)

[Claims] An image forming apparatus for separately driving a photoreceptor by a photoreceptor motor and an intermediate transfer belt for transferring a toner image on the photoreceptor by an intermediate transfer motor. A photoconductor drive control device, comprising: a brake unit that switches a signal to stop and simultaneously activates a brake for the photoconductor motor for a predetermined time. 2. The photoconductor drive control according to claim 1, further comprising a photoconductor motor control unit that reversely drives the photoconductor motor for a predetermined time after a brake operation for a predetermined time by the brake unit. apparatus. 3. The photoreceptor motor control means switches the drive signal of the photoreceptor motor to stop for a short time after the brake operation by the brake means for a predetermined time, and then drives the photoreceptor motor in reverse. Features,
The photoconductor drive control device according to claim 2.