JPH02176673A - Picture forming device - Google Patents

Abstract

PURPOSE:To eliminate color slurring under a simple constitution by providing 1st and 2nd drive control means which control 1s and 2nd driving motors based on a reference signal from a reference signal generating means so that they are synchronized. CONSTITUTION:This device has the 1st driving motor 31 driving plural photosensitive bodies, the 2nd driving motor 40 driving a transfer material carrying belt 2 and the reference signal generating means 39 generating a single control reference signal. The reference signal generated by the reference signal generator 39 is frequency-divided by a frequency divider 38, and the identical reference signals are sent to a photosensitive body drive control part 37 and a belt drive control part 42. The photosensitive body drive control part 37 and the belt drive control part 42 control the photosensitive body driving motor 31 and the belt driving motor 40 based on the same reference signal so as to be at a constant speed. Consequently, a speed change of the two motors can be minimized, whereby a color picture free of color slurring can be formed on a transfer paper 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention involves arranging a plurality of photoreceptors in parallel, forming images of different colors on each photoreceptor, and superimposing these images to produce multicolor images. The present invention relates to an image forming apparatus suitable for, for example, a copying machine, a facsimile machine, a laser beam printer, etc., for forming an image.

[Conventional technology]

There are two types of electrophotographic image forming devices: monochrome and multicolor. In these devices, it is necessary to synchronize the circumferential speed of the photoreceptor and the transport speed of the transfer material, and to suppress fluctuations in both speeds. There is. However, in monochromatic image formation, if there is an extreme deviation in the synchronization speed between the two, the image will become blurry, but a slight deviation in the synchronization speed will only cause the image to partially expand or contract. , there was no significant deterioration in image quality.

On the other hand, in the case of multicolored images, expansion and contraction of the image appears as color blurring, which significantly reduces the image quality. In particular, in image forming apparatuses that are configured to obtain multicolor images by arranging multiple photoreceptors and repeating sequential transfer of each color to a single transfer material, color misregistration (which is difficult to put into words) is prevented. Various techniques have been proposed to deal with color shift.

Among these, for example, JP-A-59-182139 discloses a technique for preventing color misregistration by making the distance between photoreceptors an integral multiple of the conveyor belt driving roller diameter, and JP-A-62-178982
discloses a technique in which each photoreceptor is provided with a driving servo motor, rotational speed fluctuations are detected and fed back to the driving servo motors, and color shift due to speed fluctuations is prevented.

Further, Japanese Patent Laid-Open No. 178988/1983 discloses a technique for preventing color shift caused by variations in rotational speed due to eccentricity of a rotating body driving means.

[Problem to be solved by the invention]

As described above, in image forming apparatuses that form multicolor images using a plurality of photoreceptors, various considerations have been made to prevent color misregistration. However, for boat fishing, it is cost-effective to drive multiple photoconductors and the transfer material conveyance belt with the same drive motor, but this would complicate the drive transmission system and require the use of gears and other bathocratic motors. There is a problem in that it is difficult to obtain synchronization due to the addition of eccentricity and eccentricity.

The present invention has been made in view of the actual state of the prior art as described above, and an object thereof is to provide an image forming apparatus that can suppress the occurrence of color misregistration with a simple mechanism.

[Means to solve the problem]

The above purpose is to arrange a plurality of photoconductors side by side, perform a preset image forming process on these photoconductors to develop each color, and then transport the developed images carried on these photoconductors by a transfer material conveyance belt. In a multicolor image forming apparatus that sequentially transfers color images onto a transfer material, a first drive motor drives a plurality of photoreceptors, a second drive motor drives a transfer material conveyance belt, and a single drive motor drives a transfer material conveyance belt. a reference signal generation means for generating one control reference signal; and first and second drive motors for controlling the first drive motor and the second drive motor in synchronization, respectively, based on the reference signal from the reference signal generation means. This is achieved by providing two drive control means.

[Effect]

According to the above means, the first and second drive control units that respectively control the first drive motor that drives the photoreceptor and the second drive motor that drives the transfer material conveyance belt are controlled by a single control standard. The first and second drive motors, which are drive-controlled based on the signal, are synchronized with high accuracy, and color misregistration due to speed fluctuations of both can be prevented.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an image forming apparatus for obtaining a multicolor image according to an embodiment of the present invention. In the figure, the image forming apparatus has four colors, black B, cyan C, Drum-shaped photoreceptors IB, IC, and IM for magenta M and yellow Y.

It consists of four IY arranged horizontally, and these photoreceptors I
An endless transfer material conveying belt 2 made of, for example, a dielectric film is stretched between a driving roller 3 and a driven roller 4 so as to be in contact with B, IC, IM, and IY. here,
In this embodiment, transfer paper is used as the transfer material, so in the following description, the term transfer paper will be used for convenience.

When forming an image, first, each photoreceptor IB, IC, IM
, IY are uniformly charged by corona discharge by chargers 5B, 5C, 5M, and 5Y connected to a high-voltage power source (not shown).

On the other hand, a laser beam modulated by a recording signal is applied to each photoreceptor IB by a laser writing unit 6.

IC, LM, and IY are irradiated with the light, and by this irradiation, electrostatic latent images are formed on the surfaces of each photoreceptor IB, IC, IM, and IY. These electrostatic latent images are produced by blank, cyan, magenta, and yellow developing devices 7B, 7C, and 7.
M and 7Y, and toner images corresponding to these colors are formed on the photoreceptors IB, IC, IM, and IY.

The transfer paper is fed from one of the paper feed units 8, 9, and 10, and when it reaches the pair of registration rollers 12, the presence or absence of the paper is detected by the paper detection switch 13.

Further, after the leading edge of the transfer paper reaches the registration I/roller pair 12, the registration roller pair 12 starts rotating at a predetermined timing, and as the transfer paper rotates, the transfer paper is transferred. The paper is sent onto the paper transport heel l-2. The transfer paper sent onto the transfer paper conveyance bells 1 and 2 is conveyed by this belt and passes through the portions in contact with the photoreceptors IB, IC, and LMIY.

When the transfer paper passes the first photoreceptor IB, the black toner image is transferred to the transfer charger 1 as a transfer means.
．． The image is transferred to transfer paper by IB.

Next, on the transfer paper, a cyan toner image is transferred to the photoreceptor IC, a magenta toner image is transferred to the photoreceptor IM, and a yellow toner image is transferred to the photoreceptor IY by transfer chargers 14C and 14M, respectively. ,1
Transferred by 4Y.

After the transfer of these developed images, the transfer paper is electrically discharged by a transfer paper electricity removal charger 16 and passed through a fixing roller 17, whereby a fixed color image can be obtained on the transfer paper. On the other hand, each photoreceptor IBIC, 1, M, IY has its surface cleaned by each cleaning device 18B, 18C, 18M,
18Y to remove residual toner. On the other hand, the transfer paper belt 2 is subjected to charge removal by the belt charger 19 and belt cleaning by the belt cleaning device 21.

FIG. 2 is a schematic configuration diagram of the drive unit according to the embodiment. In the same figure, the photoreceptors IB, IC, IM, and IY have flanges 27B fixed to the support shafts 24B, 24C, 24M, and 24Y of each photoreceptor; 27C, 27M27Y, the photoreceptor support shafts 24B, 24. It rotates integrally with C, 24M, and 24Y. These photoreceptor support shafts 24. B, 24C, 24,M,
24Y is a supporter 26B attached to the main body side plate 25
, 26C, 26M, and 26Y, and each has a worm wheel 28 at its tip.
B, 28C, 28M, and 28Y are provided. Also,
The worm shaft bracket 33 is removed from the supports 26B, 26C, 26M26Y, and the shaft support part 3
The worm wheel 28B of the worm shaft 30 is supported by the worm wheel 28B.

Worms 29B, 29C, 29M, and 29Y are attached to positions corresponding to 28C, 28M, and 28Y, respectively. A timing belt drive section 32 is provided at one end of the worm shaft 30, and a photoconductor drive motor 31 as a first drive motor drives each photoconductor IB, IC.
, 1M, and IY. moreover,
Oil boxes 35B, 35C, 35M for sealing lubricating oil are in the meshing parts of each worm 29B, 29C, 29M, 29Y and worm wheel 28B, 28C, 28M, 28Y.
, 35Y are provided.

As shown in FIG. 1, a first encoder 36 is directly connected to the photoconductor driving morph 31 that drives the plurality of photoconductors IB, IC, LM, and IY. A rotation signal from the drive motor 31 is input to a photoreceptor drive control section 37 serving as a first drive control section. On the other hand, a second encoder 41 is directly connected to a transfer paper conveyance belt drive motor 40 as a second drive motor.
This second encoder 41 inputs a rotation signal of the transfer paper conveyance belt drive motor 40 to a belt drive control section 42 serving as a second drive control section.

This circuit also includes a single crystal oscillator reference signal generator 39 and a frequency divider 3 as a single control reference signal generating means.
8, the reference signal generated from the reference signal generator 39 is frequency-divided by the frequency divider 38, and the same reference signal is sent to the photoconductor drive control section 37 and the belt drive control section 42.
are sent to each.

The photoconductor drive control unit 37 compares the reference signal and the rotation signal of the photoconductor drive morph 31 inputted from the first encoder 36, so that the signal from the first encoder 36 is always constant. Controls the photoreceptor drive motor 31. Similarly, the belt drive control unit 42 compares the reference signal with the rotation signal of the belt drive motor 40 input from the second encoder 41, and drives the belt so that the signal from the second encoder 41 is always constant. Controls the motor 40. Therefore, the photoconductor drive control section 37 and the belt drive control section 42 control the photoconductor drive motor 31 and the belt drive motor 4.
0 and 0 are respectively controlled to a constant speed based on the same reference signal.

By controlling the speeds of the photoreceptors IB, IC, IM, and IY and the transfer paper drive belt 2 in this way, the speed changes of both are kept to a minimum, so a color image without color shift is formed on the transfer paper. Ru. Although the belt drive mechanism is not described in detail here, for example, a drive transmission system using a worm and worm wheel similar to the photoconductor drive mechanism is employed.

〔Effect of the invention〕

As is clear from the above description, the first drive motor drives the plurality of photoreceptors, the second drive motor drives the transfer trA conveyor belt, and the reference signal generator generates a single control reference signal. and first and second drive control means for controlling the first drive motor and the second drive motor to synchronize each other based on the reference signal from the reference signal generating means. According to the invention, since the reference signal is output from a single signal generating means, it is easy to synchronize the first and second drive motors, and therefore,
Even if there are multiple motors, the photoreceptor and the conveyor belt can be synchronized with high precision, making it possible to obtain good color images without color shift with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an image forming mechanism of an image forming apparatus according to an embodiment, and FIG. 2 is a schematic configuration diagram showing a photoreceptor drive mechanism. 1B, IC, LM, IY...Photoconductor, 2...
... Transfer material (paper) conveyance belt, 31 ... Photoreceptor drive motor, 36 ... First encoder, 3
7... Photoreceptor drive control section, 38... Frequency divider, 39... Reference signal generator, 40...
. . . Belt drive motor, 41 . . . Second encoder, 42 . . . Belt drive control section.

Claims (1)

[Claims] A plurality of photoconductors are arranged side by side, and each color is developed by applying a preset image forming process to these photoconductors, and the developed image carried on these photoconductors is transferred to a transfer material conveyed by a transfer material conveyance belt. In a multicolor image forming apparatus that sequentially transfers color images to
a second drive motor that drives the transfer material conveyance belt; a reference signal generating means for generating a single control reference signal; An image forming apparatus comprising first and second drive control means for controlling a drive motor and a second drive motor in synchronization with each other.