JP2001154560A - Drive control method for image forming device, drive control device therefor, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive control method for an image forming device and its device excellent in stability of a picture and an image forming device, wherein it is possible to reduce color difference between different transfer materials caused by mis-placement occurring between an image carrier and an endless form carrier such as a transfer material transportation belt and an intermediate transfer belt. SOLUTION: In the drive control method of the image forming device comprising at least one rotary-driven image carrier and a rotary-driven endless carrier and controlling rotary drive of these image carrier and endless form carrier, a difference between an integral multiple of a rotation period of the image carrier and a rotation period of the endless form carrier is detected, and based on the result of the detection, the method is featured to control the rotation period of the image carrier or the endless form carrier so that the integral multiple of the rotation period of the image carrier almost coincides with the rotation period of the endless form carrier, to accomplish the purpose.

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 or the like to which an electrophotographic system or an electrostatic recording system is applied. More specifically, the present invention includes an image carrier such as a photosensitive drum, and transfers an image formed on the image carrier onto a transfer material or an intermediate transfer belt held on a transfer material transport belt. The present invention relates to an image forming apparatus for forming a black-and-white or color image, and in particular, it is possible to reduce a color difference between different transfer materials caused by a positional shift between an image carrier and a transfer material transport belt or an intermediate transfer belt. The present invention relates to a simple image forming apparatus.

[0002]

2. Description of the Related Art In recent years, color processing of documents processed in offices and the like is rapidly progressing, and image forming apparatuses such as copiers, printers, and facsimile machines that handle these documents are also rapidly being colored. At present, these color devices have been further improved in image quality or speed in accordance with higher quality and faster office processing in offices and the like.

Conventionally, a color device which can respond to the demand for higher image quality or higher speed includes a photosensitive drum, and images of different colors sequentially formed on the photosensitive drum are held on a transfer drum. (Hereinafter, referred to as a “transfer drum method”) in which images are transferred in a multiplexed manner onto a transfer paper, and an image having different colors formed on the photosensitive drum is provided with at least one photosensitive drum. Many methods have been proposed, which employ a method of transferring an image onto a transfer sheet held on a sheet transport belt or an intermediate transfer belt and forming an image (hereinafter, referred to as a “transfer belt method”). Have been.

[0004] Among these, the transfer drum type image forming apparatus transfers an image of a different color sequentially formed on the photosensitive drum every time the photosensitive drum makes one rotation. By multiply transferring to paper,
Since a color image is formed, it takes time to form a color image, it is difficult to increase the speed, and the transferability differs depending on the material of the transfer paper, and the type of transfer paper on which an image can be formed is limited. It has a drawback.

[0005] On the other hand, an image forming apparatus of the transfer belt type transfers images of different colors sequentially formed by a plurality of image forming units onto a transfer sheet held on a sheet conveying belt in a multiplex manner. Alternatively, images of different colors sequentially formed by one or a plurality of image forming units are multiplex-transferred onto an intermediate transfer belt once, and then collectively transferred from the intermediate transfer belt to transfer paper. In addition, a color image can be formed, the speed can be increased, or the type of transfer paper on which an image can be formed is not limited.

Among the transfer belt type image forming apparatuses of this type, a so-called tandem type color image forming apparatus is, for example, as follows. As shown in FIG. 23, the tandem type color image forming apparatus includes a black image forming unit 300K for forming a black (K) image and a yellow image forming unit 300Y for forming a yellow (Y) image. And a magenta image forming unit 300M for forming a magenta (M) color image
And four image forming units of a cyan image forming unit 300C for forming a cyan (C) color image. These four image forming units 300K, 300
Y, 300M, and 300C are horizontally arranged at a fixed interval from each other. The toners sequentially formed by the respective image forming units are provided below the image forming units 300K, 300Y, 300M, and 300C for the black (K), yellow (Y), magenta (M), and cyan (C). An intermediate transfer belt 301 for transferring images in a state of being superimposed on each other includes a plurality of rolls 311-
By 314, it is arranged to be driven to rotate in the direction of the arrow. The intermediate transfer belt 301 is formed, for example, by forming a flexible synthetic resin film such as polyimide in a belt shape and connecting both ends of the synthetic resin film formed in a belt shape by means such as welding to form an endless belt. It is configured in a shape. Therefore, as shown in FIG. 24, the intermediate transfer belt 301 necessarily has a seam portion 301a which is a connection portion of a synthetic resin film. If the intermediate transfer belt 301 can be manufactured without forming the seam portion 301a, the intermediate transfer belt 30
Of course, 1 does not have to have the seam portion 301a.

Each of the black (K), yellow (Y), magenta (M), and cyan (C) image forming units 300K,
300Y, 300M, and 300C are all configured similarly, and these four image forming units 300K,
In 00Y, 300M, and 300C, as described above, black, yellow, magenta, and cyan toner images are sequentially formed, respectively. The image forming units 300K, 300Y, 300M, and 30 for each of the above colors
0C includes a photosensitive drum 302, and the surface of the photosensitive drum 302 has a scorotron 30 for primary charging.
After being uniformly charged by 3, the image exposure device 304 scans and exposes an image forming laser beam in accordance with image information to form an electrostatic latent image. The photosensitive drum 302
The electrostatic latent image formed on the surface of each image forming unit 3
00K, 300Y, 300M, 300C developing unit 305
Are developed with toners of black, yellow, magenta, and cyan, respectively, to form visible toner images. These visible toner images are transferred onto the intermediate transfer belt 301 by the transfer charger 306 in a state of being superimposed on each other. Is done. The black, yellow, magenta, and cyan toner images multiplexly transferred onto the intermediate transfer belt 301 are collectively transferred onto a transfer sheet 307 and then subjected to a fixing process by a fixing device 308. , A color image is formed.

In FIG. 23, reference numeral 309 denotes a photosensitive member cleaner, and 310 denotes an intermediate transfer belt cleaner.

The tandem-type color image forming apparatus constructed as described above multiplexes the toner images sequentially formed by the plurality of image forming units 300K, 300Y, 300M, and 300C on the intermediate transfer belt 301. Since the transfer method is used, the speed can be greatly increased. However, the image forming units 300K and 300K for each color are used.
If the densities of the toner images formed in Y, 300M, and 300C are different from the predetermined densities, when the toner images of the respective colors are superimposed, an image of a predetermined color cannot be formed, and a high-quality color image Is difficult to form.

Therefore, as a conventional technique, as shown in FIG. 24, a pattern 315 for controlling image forming conditions (process control) on the intermediate transfer belt 301 is used.
(Hereinafter, referred to as “patch”), the process control patches 315 are detected by the detector 316, and the respective image forming units 300K and 300K are detected.
Various techniques for controlling the image forming conditions in Y, 300M, and 300C have already been proposed, and have already been introduced in actual machines.

[0011]

However, the prior art described above has the following problems. That is, in comparison with the transfer drum method and the transfer belt method, the problem of the present invention will be described. In the image forming apparatus of the transfer drum method, the circumference of the photosensitive drum and the circumference of the transfer drum are set to integral multiples in advance. If the image formation is performed on the basis of the transfer drum, the photosensitive drum and the transfer drum will not be affected even if there is an environmental change such as an increase in the temperature inside the apparatus or a manufacturing error of the components constituting the transfer drum. The image formed on the photoconductor drum is always held on the transfer drum by rotating the photoconductor drum and the transfer drum by connecting them with gears etc. because they are made of a metal cylinder or frame. It can be transferred to the same position on the transferred transfer paper.
Therefore, in the case of the transfer drum type image forming apparatus, even if there is an environmental change such as an increase in the temperature inside the apparatus or a manufacturing error of a component constituting the transfer drum, the photosensitive drum and the transfer drum are initially initialized. By synchronizing the rotation cycle, the image formed on the photosensitive drum can always be transferred to the same position on the transfer sheet held on the transfer drum, and for example, the same image can be transferred between different transfer sheets. Is reproduced, there is no problem with the difference in reproduced colors (color difference).

However, in the case of a transfer belt type image forming apparatus, the circumferential length of the photosensitive drum and the circumferential length of the paper transport belt or the intermediate transfer belt are set to integral multiples in advance, and the photosensitive drum and the paper transport belt or the intermediate transfer belt are set. Even if the transfer belts are connected by gears and used as the same drive system, it is inevitable that the circumference of the transfer belt has an error with respect to the design value due to environmental changes such as an increase in the temperature inside the apparatus and manufacturing errors of parts. . The reason is that the photosensitive drum is made of a metal cylindrical body, but since the paper transport belt and the intermediate transfer belt are made of an endless body made of synthetic resin, it is difficult to maintain the circumferential length with high accuracy. This is because the coefficient of thermal expansion due to temperature fluctuation or the like is large. When the transfer belt has a seam (hereinafter, referred to as a “seam portion”), it is necessary to form an image while avoiding the seam portion of the belt, and the image forming timing is determined based on the position of the transfer belt. Will decide.
Therefore, in the case of a transfer belt type image forming apparatus, due to environmental changes such as an increase in the temperature inside the apparatus, manufacturing errors of parts, and the like,
If the circumference of the transfer belt is different from the design value, when the transfer belt rotates, the image formed on the photosensitive drum is transferred onto the transfer paper or the intermediate transfer belt held on the paper transport belt. The position is gradually shifted, and a color difference (color difference) reproduced between different transfer papers becomes a problem.

FIG. 25 shows photosensitive drums 302K and 302K in the tandem image forming apparatus of the transfer belt type.
Y, 302M, and 302C and the rotation cycle of the intermediate transfer belt 301 are different from each other due to a difference between the rotation cycle of the intermediate transfer belt 301 and the rotation cycle of Y.
FIG. 9 is a schematic diagram for explaining a color difference reproduced between 7.
Here, the circumference of the intermediate transfer belt 301 is set equal to, for example, eight times the circumference of the photosensitive drum 302.
Further, one round of the intermediate transfer belt 301 is divided into n (n) with reference to the seam portion 301a of the intermediate transfer belt 301.
= Integer) as the Pitch (pitch) position,
Based on this pitch position, the photosensitive drums 302K, 30K
The image of each page is written on 2Y, 302M, and 302C.

FIG. 26 shows one of the photosensitive drums 302 when the same image is printed on a plurality of pages (a plurality of sheets) when the circumference of the intermediate transfer belt 301 is in an ideal state equal to the design value. FIG. 3 illustrates positions where the cycle is developed and states of images transferred onto the intermediate transfer belt 301. FIG. FIG. 27 illustrates a state of an image transferred onto the intermediate transfer belt 301 when the circumference of the intermediate transfer belt 301 is shorter than a design value due to an environmental change, a manufacturing error, or the like. Further, FIG. 28 shows a state of an image transferred onto the intermediate transfer belt 301 when the circumference of the intermediate transfer belt 301 becomes longer than a design value due to an environmental change or a manufacturing error.

In this way, if the circumference of the intermediate transfer belt 301 is in an ideal state equal to the design value, an image is formed on the photosensitive drum 302 based on the position of the intermediate transfer belt 301 as shown in FIG. Is formed, and the photosensitive drum 302
When the image formed on the intermediate transfer belt 301 is transferred to the intermediate transfer belt 301 and the same image is printed on a plurality of pages (a plurality of sheets), even if the image transferred on the intermediate transfer belt 301 is the first page, The second page,..., The fourth page always corresponds to the same position on the photosensitive drum 302. Therefore, if the circumference of the intermediate transfer belt 301 is in an ideal state equal to the design value, the position where the image formed on the photosensitive drum 302 is transferred onto the intermediate transfer belt 301 is shown in FIG. As always, it is always at the same position.

On the other hand, if the peripheral length of the intermediate transfer belt 301 becomes shorter or longer than the designed value due to environmental changes or manufacturing errors, as shown in FIG. 27 or FIG. When an image is formed on the photosensitive drum 302 on the basis of, the image formed on the photosensitive drum 302 is transferred to the intermediate transfer belt 301, and the same image is printed on a plurality of pages (a plurality of sheets). The image transferred on the transfer belt 301 has different positions on the photosensitive drum 302 between images corresponding to different transfer papers, such as the first page, the second page,..., The fourth page.

For this reason, if the circumference of the intermediate transfer belt 301 becomes shorter or longer than the design value due to environmental changes, manufacturing errors, or the like, the circumference of the intermediate transfer belt 301 changes and the intermediate transfer belt 301 is placed on the intermediate transfer belt 301. The image transferred to the same position of each page is formed at a position gradually shifted forward or backward on the photosensitive drum 302 as shown in FIG. 30 or 31. That is, if the page on the intermediate transfer belt 301 is different, the position on the photosensitive drum 302 where an image is formed on the corresponding page is different.

As described above, even if the position on the photosensitive drum 302 where the image to be transferred on the transfer paper is formed is different,
If the image forming characteristic of the photosensitive drum 302 is constant over the entire circumference, the difference in the image forming position on the photosensitive drum 302 does not affect the image quality of the image transferred onto the transfer paper.

However, the image forming characteristics of the surface of the photosensitive drum 302 are not constant along the rotating direction of the photosensitive drum 302 but fluctuate along the rotating direction.

That is, the image forming characteristics of the surface of the photosensitive drum 302 include the fluctuation of the gap between the drum surface and the developing device 305 due to the eccentricity of the photosensitive drum 302 and the sensitivity unevenness along the rotation direction of the surface of the photosensitive drum 302. For example, as shown in FIG. 32, it is not constant but fluctuates along the rotation direction. Therefore, in actuality, image forming characteristics such as developing characteristics are different in one round of the photosensitive drum 302, and even if an image of the same density is to be formed, if the image forming position on the photosensitive drum 302 is different, the image is formed. The density of the image changes. Then, the image formed on the photosensitive drum 302 is transferred to the transfer paper or the intermediate transfer belt 30 held on the paper transport belt.
30 or 31, the image density fluctuates due to the image forming position on the photosensitive drum 302, and the color difference reproduced between different transfer papers (Color difference).

That is, as shown in FIG. 30 or FIG.
For example, if the image forming position on the photosensitive drum 302 is different between the image of the first page and the image of the fourth page, as shown in FIG. 32 due to the difference in the image forming position on the photosensitive drum 302, Since the image density formed on the photosensitive drum 302 is different, even if the same image is formed on the first page and the fourth page, the photosensitive drum 302
The density of an image to be formed differs depending on the difference in the image forming position, and a color difference (color difference) reproduced between different transfer sheets appears due to the difference. The color difference reproduced between the different transfer papers is not so problematic in an image with a high density, but it appears remarkably in a high-light image with a relatively low density and is a serious problem.

As a result, in a recent image forming apparatus such as a super-high-quality full-color printer or the like, when printing a plurality of sheets from the same original, a change in image density due to a shift in an image forming position on the photosensitive drum. Appears as a difference in the color difference between the transfer paper held on the paper transport belt and the image transferred on the intermediate transfer belt, and when comparing multiple color prints of the same image, the color difference However, there is a problem that the image is noticeable to human eyes and lacks in image quality stability.

As shown in FIG. 24, a patch 315 for process control is formed on the intermediate transfer belt 301, and the patch 315 for process control is formed.
Is detected by the detector 316 and the density of the toner image of each color is controlled, when the circumference of the transfer belt fluctuates from a design value due to environmental change or manufacturing error, etc. The position on the intermediate transfer belt 301 where the patch 316 is formed changes. Therefore, when the position at which the process control patch 316 is formed on the intermediate transfer belt 301 changes, the position on the intermediate transfer belt 301 that serves as a reference for the density detection of the process control patch 316 also changes. There was a problem that the density of the patch 316 could not be detected with high accuracy, and the stability of image quality also deteriorated.

The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide an image carrier and an endless carrier such as a transfer material conveying belt and an intermediate transfer belt. It is possible to reduce the color difference between different transfer materials due to misregistration that occurs with the body,
An object of the present invention is to provide a drive control method and apparatus for an image forming apparatus having excellent image quality stability, and an image forming apparatus.

[0025]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: at least one image carrier which is rotationally driven; and an endless carrier which is rotationally driven. In a drive control method for an image forming apparatus that controls rotation of the image carrier and the endless carrier, a difference between an integral multiple of the rotation cycle of the image carrier and the rotation cycle of the endless carrier is detected, The rotation cycle of the image carrier or the endless carrier is controlled based on the detection result so that the rotation cycle of the endless carrier substantially equals the integral multiple of the rotation cycle of the image carrier. Of the image forming apparatus.

According to a second aspect of the present invention, there is provided at least one image carrier which is driven to rotate, and an endless carrier which is driven to rotate, and the image carrier and the endless carrier are rotated. In the drive control device of the image forming apparatus for controlling driving, a difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is detected, and the rotation of the image carrier is determined based on the detection result. A driving unit for controlling the rotation cycle of the image carrier or the endless carrier such that an integral multiple of the cycle substantially coincides with the rotation cycle of the endless carrier. It is a control device.

Further, according to the present invention, images of different colors are formed by at least one image forming means having an image carrier which is driven to rotate, and the different colors formed by the image forming means are formed. The image is transferred onto a transfer material or an endless carrier that is carried on the endless carrier that is driven to rotate, and the image forming timing on the image carrier is determined based on the position of the endless carrier. An image forming apparatus that forms an image by determining the image forming timing on the image carrier, based on the position of the endless carrier. The difference between the integral multiple and the rotation cycle of the endless carrier is detected, and based on the detection result, the integer multiple of the rotation cycle of the image carrier and the rotation cycle of the endless carrier substantially match each other. Image carrier or An image forming apparatus characterized by comprising a control means for controlling the rotation period of the endless carrier.

As the image carrier, for example, a photosensitive drum is used, but it is not limited to this.
A dielectric drum or the like for performing electrostatic recording may be used.

Further, as the endless carrier, for example, a paper transport belt for transporting the transfer paper while carrying it is used. However, the present invention is not limited to this, and the image formed on the image carrier is not limited thereto. May be used.

Further, as the control means, for example,
Although control means for controlling the image forming operation of the image forming apparatus is used, a dedicated control means may be provided. Also,
The control means determines the integer multiple of the rotation period of the image carrier and the rotation period of the endless carrier based on the detection result of the difference between the integral period of the image carrier and the rotation period of the endless carrier. The rotation period of the image carrier or the endless carrier is controlled so as to substantially match, and the detection of a difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is controlled. Means may be used, but it goes without saying that other means may be used.

Here, "so that an integral multiple of the rotation period of the image carrier substantially coincides with the rotation period of the endless carrier".
This naturally includes a case in which the rotation period of the endless carrier is made to match the integral multiple of the rotation period of the image carrier, but it is possible to reduce the color difference between the transfer materials. However, there may be a slight difference between the two, and it is not necessary to completely match them.

In the image forming apparatus according to the third aspect, for example, as shown in FIG.
Images of different colors are formed by four image forming units 02K, 02Y, 02M, and 02C having K, 01Y, 01M, and 01C, and the image forming units 02K, 02Y, and 02 are formed.
The transfer material 04 carried on the endless carrier 03 which is driven to rotate by rotating the images of different colors formed by M and 02C.
In the image forming apparatus that forms an image by transferring the image onto the image carrier and determining the image forming timing on the image carrier based on the position of the endless carrier, the rotation cycle of the image carrier 01 is determined. A difference between the integral multiple and the rotation cycle of the endless carrier 03 is detected, and based on the detection result, the integer multiple of the rotation cycle of the image carrier 01 and the rotation cycle of the endless carrier 03 match. And a control unit 06 for controlling the rotation cycle of the image carrier 01 or the endless carrier 03. In FIG. 1, 05K, 05Y, 0
5M and 05C are four image forming units 02K, 02Y,
02M and 02C image carriers 01K, 01Y, 01M,
A drive unit for rotatingly driving 01C is shown.

The image forming apparatus according to the third aspect, for example, as shown in FIG. 2, includes four image forming units 02K, 02Y, and 02C having rotatably driven image carriers 01K, 01Y, 01M, and 01C. 02M and 02C, images having different colors are formed.
Images of different colors formed by Y, 02M, and 02C are directly transferred to the endless carrier 03 that is driven to rotate, and the image forming timing on the image carrier is determined based on the position of the endless carrier. In the image forming apparatus that forms an image, the difference between the integral multiple of the rotation period of the image carrier 01 and the rotation period of the endless carrier 03 is detected, and based on the detection result, A control unit 06 for controlling the rotation cycle of the image carrier 01 or the endless carrier 03 so that the rotation cycle of the endless carrier 03 matches the integral multiple of the rotation cycle of the image carrier 01. You may comprise. In FIG. 2, reference numeral 07 denotes a driving unit that rotationally drives the endless carrier 03, and reference numeral 08 denotes a transfer material transporting unit that transports a transfer material 04 onto which images are transferred collectively from the endless carrier 03. Things.

Further, according to a fourth aspect of the present invention, the difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is a first position for detecting a reference position of the endless carrier. The output interval of the first reference position detection signal output from the reference position detection means, and the output of the second reference position detection signal output from the second reference position detection means for detecting the reference position of the image carrier 4. The image forming apparatus according to claim 3, wherein the image forming apparatus calculates the distance based on an interval or a set rotation period of the image carrier.

According to a fifth aspect of the present invention, the difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier detects the reference position of the endless carrier. The output timing of the first reference position detection signal output from the reference position detection means and the second reference position of the image carrier detected immediately after or immediately before the output timing of the first reference position detection signal. The second output from the reference position detecting means
4. The image forming apparatus according to claim 3, wherein the difference is calculated from the difference between the output timings of the reference position detection signals.

Further, according to the invention described in claim 6, the control means comprises means for controlling a rotation cycle of the image carrier, and the rotation control of the image carrier is performed according to a difference between the detected rotation cycles. 6. The image forming apparatus according to claim 3, wherein the image forming apparatus is performed by changing an average rotation speed of the image carrier.

According to a seventh aspect of the present invention, there is provided a transfer material or an endless carrier supported on a rotatably driven endless carrier according to a change amount of an average rotation speed of the image carrier. 7. The image forming apparatus according to claim 6, wherein the image writing timing in the rotation direction on the image carrier is changed so that an image is formed at a predetermined position on the body.

Further, according to the invention, an image is formed at a predetermined position on a transfer material on which an image is finally formed in accordance with a change amount of the average rotation speed of the image carrier. 8. The image forming apparatus according to claim 6, wherein the transfer timing of the transfer material is changed.

Still further, according to the ninth aspect of the present invention,
In an image forming apparatus including a plurality of image forming units having image carriers that are rotationally driven, the timing of changing the average rotation speed of each image carrier is determined by each image forming unit for the same image. 7. The image forming apparatus according to claim 6, wherein the image is located at the same position of the image to be formed.

Further, the invention described in claim 10 is:
In an image forming apparatus provided with a plurality of image forming means having an image carrier driven to rotate, the average rotation speed of each image carrier is controlled by an image carrier driven by each image carrier or by the same drive control system. 7. The image forming apparatus according to claim 6, wherein the image forming apparatus is set for each body.

Further, according to the present invention, the image writing timing in the rotation direction on each of the image carriers is individually changed in accordance with the change amount of the average rotation speed of each of the image carriers. The image forming apparatus according to claim 10, wherein:

Further, according to a twelfth aspect of the present invention, the control means comprises means for controlling a rotation cycle of the endless carrier, and the rotation control of the endless carrier is based on a difference between the detected rotation cycles. The image forming apparatus according to any one of claims 3 to 5, wherein the image forming apparatus is performed by changing an average rotation speed of the endless carrier in accordance with the following.

According to a thirteenth aspect of the present invention, the writing speed of the image writing means for writing an image on the image carrier is adjusted according to the amount of change in the average rotation speed of the endless carrier. 13. The image forming apparatus according to claim 12, wherein the image forming apparatus is changed.

According to a fourteenth aspect of the present invention, in the image forming apparatus provided with a plurality of image forming means having an image carrier that is driven to rotate, the timing for changing the average rotation speed of the endless carrier is as follows. 14. The image forming apparatus according to claim 12, wherein the setting is performed when all image forming units are not transferring an image.

Further, the invention described in claim 15 is:
When transferring the image on the image carrier to a transfer material carried on the endless carrier or the endless carrier, a speed difference is set between the image carrier and the endless carrier. In the image forming apparatus, the speed difference between the image carrier and the endless carrier is such that “surface speed of the image carrier> surface speed of the endless carrier”. 4. The set value of the peripheral length is set to be equal to or less than an integral multiple of the peripheral length of the image carrier even when the peripheral length of the endless carrier has a maximum fluctuation. An image forming apparatus according to (1).

Further, according to the present invention, when the image on the image carrier is transferred onto a transfer material carried on an endless carrier or onto the endless carrier, the image is transferred to the endless carrier. A speed difference is set between the carrier and the endless carrier, and the speed difference between the image carrier and the endless carrier is expressed as “surface speed of image carrier <surface speed of endless carrier”. In the image forming apparatus having the following relationship, the set value of the circumference of the endless carrier is:
4. The image forming apparatus according to claim 3, wherein even if a maximum fluctuation occurs in the peripheral length of the endless carrier, the peripheral length of the image carrier is set to be an integral multiple or more. 5. is there.

Further, according to the present invention, images of different colors are formed by a single image forming means having an image carrier which is driven to rotate, and images of different colors formed by the image forming means are formed. Is transferred onto a rotatably driven endless carrier, and the image forming timing on the image carrier is determined based on the position of the endless carrier, thereby forming an image. ,
A difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is detected, and based on the detection result, an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier. An image forming apparatus, comprising: a control unit that instantaneously controls the rotational driving of the endless carrier in the non-image portion so that the image forming devices substantially match.

[0048]

According to the first to third aspects of the present invention, basically, a difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is detected, and the difference is detected based on the detection result. And a control unit for controlling the rotation cycle of the image carrier or the endless carrier such that an integral multiple of the rotation cycle of the image carrier substantially coincides with the rotation cycle of the endless carrier. since it is, the circumferential length of the endless carrier member, as shown in FIG. 3 (a), the ideal of the length L _B is a design value, environmental changes such as increase in temperature inside and parts manufacturing error or the like By
As shown in FIG. 3 (b) or (c), the length L _B -L even when stretched or contracted Dari or L _B + L _Y to _X, integer multiples an endless carrier of the rotation period of the image bearing member Control means for detecting the difference between the rotation period of the image carrier and the rotation period of the endless carrier based on the detection result. By controlling the rotation cycle of the endless carrier, the two rotation cycles can be made to substantially coincide with each other, thereby preventing the image forming position from being shifted between the image carrier and the endless carrier. It is possible to reduce a color difference between different transfer materials due to a positional shift between the image carrier and the transfer material conveying belt or the intermediate transfer belt, and to form an image with excellent image quality stability. An apparatus or the like can be provided.

In FIG. 3, if the circumference of the endless carrier is equal to the ideal design value of the length L _B , the circumference L _B of the endless carrier is changed to the circumference L _D of the image carrier. by setting the integer n times, L _B = nL _D the relationship holds.

Next, when the endless carrier shrinks, V
_B = V _D (V _B: a rate of endless carrier, V _D: the image rate of the carrier) When, as shown in FIG. 3 (b), the rear end of the endless carrier, the L _x min Misalignment occurs.

Similarly, when the endless carrier is extended,
When V _B = V _D, as shown in FIG. 3 (c), the rear end of the endless carrier, displacement of L _Y component is generated.

[0052] Therefore, in this invention, even if shown in FIG. 3 (b) or _{(c), (L B -L} X) / V B = nL D / V D (L B + L X) / V B = nL as related in the _D / V _D is satisfied, by the control means, without changing the speed of the endless carrier, either varying the speed of the image carrier, or without changing the speed of the image bearing member, the endless carrier member It is configured to change the speed of.

Here, when the speed of the image carrier is changed by the control means, as described above, the color difference between the different transfer materials can be prevented, but the image on the image carrier is not fixed on the endless carrier. The transfer position at the time of transfer onto the transfer material held on the endless carrier or the endless carrier is changed. If the change in the transfer position of the image is small enough to cause no substantial problem, there is no need to take any other measures.

However, even if the change in the transfer position of the image is small enough to cause no substantial problem, the change in the transfer position or the change in the transfer position is a substantial problem. If there is a fear, as described in claim 7, the transfer material or the transfer material carried on the endless carrier that is driven to rotate in accordance with the amount of change in the average rotation speed of the image carrier. The image writing timing in the rotation direction on the image carrier may be changed so that an image is formed at a predetermined position on the endless carrier.

Further, in addition to changing the image writing timing in the rotating direction on the image carrier, as described in claim 8, the final rotation speed of the image carrier depends on the amount of change in the average rotation speed of the image carrier. The transfer timing of the transfer material may be changed so that the image is formed at a predetermined position on the transfer material on which the image is to be formed.

Further, in the image forming apparatus according to the ninth aspect of the present invention, in the image forming apparatus provided with a plurality of image forming means having the image carriers to be rotationally driven, the average rotation speed of each of the image carriers is changed. Since the timing is configured to be the same position of the image formed by each image forming unit with respect to the same image, each image forming unit changes the average rotation speed of each image carrier during image formation. Even in this case, since the timing for changing the average rotation speed of each image carrier is the same position of the image formed by each image forming unit for the same image, each image forming unit is formed by each image forming unit. The formation positions of images of different colors do not individually change, and it is possible to prevent color shift or the like from occurring in the same image.

Further, according to the present invention, in an image forming apparatus provided with a plurality of image forming means having an image carrier which is driven to rotate, the average rotation speed of each of the image carriers may be different from each other. Since it is configured to be set for each image carrier or each image carrier driven by the same drive control system, even when a plurality of image forming units having image carriers is provided, each By setting the average rotation speed for each image carrier or each image carrier driven by the same drive control system, the rotation speed of each image carrier can be controlled with high accuracy.

According to the eleventh aspect of the present invention, according to the amount of change in the average rotation speed of each of the image carriers,
Since the image writing timing in the rotation direction on each of the image carriers is configured to be individually changed, the average rotation speed is reduced for each image carrier or each image carrier driven by the same drive control system. Even if it is changed, the image writing timing in the rotation direction on each image carrier is individually changed, so that the transfer material carried on the endless carrier that is driven to rotate or the predetermined value on the endless carrier is changed. An image can be formed with high accuracy at the image formation start position.

Further, in the twelfth aspect of the present invention, the control means includes means for controlling a rotation cycle of the endless carrier, and the rotation control of the endless carrier is based on the detected rotation cycle. Since the rotation is performed by changing the average rotation speed of the endless carrier according to the difference, in addition to controlling the rotation cycle of the image carrier as in the invention according to claim 6, the endless carrier is used. By controlling the rotation period of the image carrier, it is possible to prevent the image forming position from being shifted between the image carrier and the endless carrier, and to prevent the image carrier and the transfer material conveying belt or It is possible to reduce a color difference between different transfer materials due to a positional shift occurring with the intermediate transfer belt, and to provide an image forming apparatus with excellent image quality stability.

Here, if the speed of the endless carrier is changed by the control means, the color difference between different transfer materials can be prevented as described above, but the magnification of the image formed on the transfer material is reduced. fluctuate. If the change in the magnification of the image is small enough to cause no substantial problem, no other measures need to be taken.

However, even if the change in the magnification of the image is small enough to cause no substantial problem, the change in the magnification may be corrected or the change in the magnification may become a problem. In some cases, the writing speed of the image writing means for writing an image on the image carrier is also adjusted according to the amount of change in the average rotation speed of the endless carrier. By changing, the configuration may be such that the magnification of the image is prevented from changing.

According to a fourteenth aspect of the present invention, in an image forming apparatus having a plurality of image forming means having a rotatably driven image carrier, the average rotation speed of the endless carrier is changed. Since the timing is set when all the image forming units are not transferring an image, even when the average rotation speed of the endless carrier is changed, it is possible to prevent the occurrence of image disorder. it can.

Further, the invention described in claim 15 is:
When transferring the image on the image carrier to a transfer material carried on the endless carrier or the endless carrier, a speed difference is set between the image carrier and the endless carrier. In the image forming apparatus, the speed difference between the image carrier and the endless carrier is such that “surface speed of the image carrier> surface speed of the endless carrier”. The set value of the circumference is set so as to be equal to or less than an integral multiple of the circumference of the image carrier even when the maximum variation occurs in the circumference of the endless carrier. In an image forming apparatus employing a so-called slip transfer in which a speed difference is set between the image bearing member and the carrier, even when the peripheral length of the endless carrier has a maximum fluctuation, "surface speed of image carrier> endless shape" Surface speed of carrier ''
The following relationship can be maintained, and slip transfer can always be performed favorably.

Further, according to the present invention, when the image on the image carrier is transferred onto a transfer material carried on an endless carrier or onto the endless carrier, the image is transferred to the endless carrier. A speed difference is set between the carrier and the endless carrier, and the speed difference between the image carrier and the endless carrier is expressed as “surface speed of image carrier <surface speed of endless carrier”. In the image forming apparatus having the following relationship, the set value of the circumference of the endless carrier is:
Even if the maximum fluctuation occurs in the circumference of the endless carrier, the peripheral length of the image carrier is set to be an integral multiple or more, so that the speed between the image carrier and the endless carrier is changed. In an image forming apparatus that adopts a so-called slip transfer by setting a difference, “surface speed of image bearing member <surface speed of endless bearing member” even when the peripheral length of the endless bearing member has the largest fluctuation.
The following relationship can be maintained, and slip transfer can always be performed favorably.

Further, according to the present invention, images having different colors are formed by a single image forming means having an image carrier which is driven to rotate, and the images having different colors formed by the image forming means are formed. An image forming apparatus for transferring an image onto a rotatably driven endless carrier and determining an image forming timing on the image carrier based on the position of the endless carrier. Detecting a difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier, and based on the detection result, an integral multiple of the rotation period of the image carrier and the rotation of the endless carrier. Since the non-image portion is provided with control means for instantaneously controlling the rotational drive of the endless carrier so that the period substantially coincides with the image carrier, the image carrier is provided as described in claim 3. Or endless support Of course, the rotation cycle of the image forming apparatus may be controlled. However, in the case of an image forming apparatus that forms images of different colors by a single image forming unit having an image carrier that is driven to rotate, only one image forming unit is provided. Has been
A plurality of image forming means do not form an image at the same time, and instantaneously control the rotation drive of the endless carrier in the non-image portion, so that the image forming positions on the endless carrier are controlled to coincide. And the configuration of the control means can be simplified.

[0066]

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

Embodiment 1 FIG. 4 is an overall configuration diagram showing a tandem-type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention.

In FIG. 4, a document 2 placed on a platen glass 1 is converted into RGB analog image signals by an image scanner having a color CCD sensor 3 via a scanning optical system including a light source and a scanning mirror. Read. The RGB analog image signals read by the color CCD sensor 3 are converted into KYMC image signals by the image processing unit 4 and temporarily stored in a memory provided inside the image processing unit 4 as necessary. You.

As shown in FIGS. 4 and 5, the image processing section 4 outputs image forming units (image forming means) for each color of black (K), yellow (Y), magenta (M), and cyan (C). ) 5K, 5Y, 5M, 5C ROS (Rast)
er Output Scanner) 8K, 8Y, 8
M and 8C sequentially output image data of each color, and laser beams LB emitted from ROS 8K, 8Y, 8M and 8C as image writing means according to the image data.
Is subjected to scanning exposure on the surface of each of the photosensitive drums 6K, 6Y, 6M, and 6C to form an electrostatic latent image. The electrostatic latent images formed on the photosensitive drums 6K, 6Y, 6M, and 6C are respectively subjected to black (K), yellow (Y), magenta (M), and black by developing units 9K, 9Y, 9M, and 9C. The image is developed as a toner image of each color of cyan (C).

The photosensitive drums 6K, 6Y, 6M, 6
As shown in FIG. 5, the transfer paper 14 as a transfer material for transferring the toner image of each color formed on C has a predetermined size from one of the plurality of paper feed cassettes 15, 16 and 17. Is transported through a paper transport path 22 including a paper feed roller 18 and a pair of paper transport rollers 19, 20, and 21. The transfer paper 14 supplied from any one of the paper feed cassettes 15, 16, and 17 is sent out onto a paper transport belt 24 as an endless carrier by a registration roll 23 that is rotated at a predetermined timing. . The paper transport belt 24 is endlessly wound around the drive roll 25, the stripping roll 26, the tension roll 27, and the idle roll 28 with a constant tension, and has excellent constant speed (not shown). Roll 25 driven by a dedicated drive motor
Thus, the circulating drive is performed at a predetermined speed in the direction of the arrow. As the paper transport belt 24, for example, a flexible synthetic resin film such as polyimide is formed in a belt shape, and both ends of the synthetic resin film formed in a belt shape are connected by means of welding or the like, thereby forming an endless belt. A belt-shaped member is used. Therefore, the paper transport belt 24 necessarily has a seam portion 24a which is a connection portion of the synthetic resin film. It should be noted that if the paper transport belt 24 can be manufactured without forming the seam portion 24a, the paper transport belt 24 need not have the seam portion 24a.

The digital color copying machine according to this embodiment is configured to determine the image forming timing on the image carrier with reference to the position of the endless carrier.

That is, the circumferential length of the paper transport belt 24 is set equal to an integral multiple of the circumferential length of the photosensitive drum 6 (eight times in this embodiment). Further, as shown in FIG. 6, an interval obtained by dividing one round of the paper transport belt 24 into n (n = integer, for example, n = 8) is Pitch (pitch) with reference to the seam portion 24 a of the paper transport belt 24.
As the position, the image of each page is written on the photosensitive drums 6K, 6Y, 6M, and 6C with reference to the pitch position.

FIG. 6 shows a case where the size of the transfer paper 14 is the maximum size for convenience of explanation.
Although only four pitches are shown, eight pitches are originally set at half the intervals in FIG.

The leading end of the transfer paper 14 transported by the paper transport belt 24 and the first image forming unit 5K
The paper feed timing and the image writing timing are determined so that the leading end of the image formed on the first photosensitive drum 6K at the lower end of the photosensitive drum 6K coincides with the transfer point. . On the transfer sheet 14 that has reached the transfer point, the visible image on the photosensitive drum 6K is transferred by the corotron 11K for transfer, and further reaches the transfer point directly below the photosensitive drum 6Y. The transfer paper 14 which has reached the transfer point immediately below the photosensitive drum 6Y is transferred to the photosensitive drum 6K in the same manner as the transfer performed by the photosensitive drum 6K.
The visible image on Y is transferred. Similarly, the transfer paper 14 after all the transfer is further conveyed by the paper conveyance belt 24, and when reaching the vicinity of the stripping roll 26, the transfer paper 14 is neutralized by the neutralizing corotron 29 for peeling and the radius of curvature is set to be small. The stripping roll 26 and the stripping claw 30 separate the sheet from the sheet transport belt 24. Thereafter, the transfer paper 14 onto which the four color toner images have been transferred is fixed by a fixing device 31 by a heating roll 32a and a pressure roll 32b, and is discharged onto a discharge tray 34 shown in FIG. The image is copied.

When a full-color image is copied on both sides of the transfer sheet 14, the transfer sheet 14 having the color image formed on one side is not directly discharged by the discharge roll pair 33 as shown in FIG. , Switching plate 35
The transfer direction of the transfer paper 14 is switched downward by
The transfer paper 14 is conveyed onto the paper conveyance belt 24 again through the paper conveyance path 22 in a state where the transfer paper 14 is turned upside down via a paper conveyance path 40 including a pair of paper conveyance rolls 36, 37, 38, and 39. A color image is formed on the back surface of the transfer paper 14 by the same process as described above.

The four image forming units 5K, 5Y, 5M, and 5 for the black, yellow, magenta, and cyan colors described above.
C has the same configuration as shown in FIG. 5, and these four image forming units 5K, 5Y, 5M,
In 5C, as described above, black, yellow, magenta, and cyan toner images are sequentially formed at a predetermined timing. The image forming units 5K, 5Y, 5M, and 5C for the respective colors include photosensitive drums 6K, 6Y, 6M, and 6C as image carriers, and these photosensitive drums 6K, 6Y, 6M, and 6C are provided.
The surface of is a scorotron 7K, 7Y, 7 for primary charging.
After uniformly charged by M and 7C, ROS8K and 8
An image forming laser beam LB emitted according to image data from Y, 8M, 8C is scanned and exposed, and an electrostatic latent image corresponding to each color is formed. The photosensitive drum 6K,
The electrostatic latent images formed on the surfaces of the image forming units 6Y, 6M, and 6C are stored in the developing units 9K of the image forming units 5K, 5Y, 5M, and 5C.
9Y, 9M, 9C, respectively, black, yellow,
Developed with magenta and cyan toners to form visible toner images, these visible toner images are subjected to pre-transfer charging by the pre-transfer chargers 10K, 10Y, 10M, and 10C, and then transferred to the transfer charger 11K, 11Y, 11M, 1
The toner image is sequentially transferred to the transfer paper 14 held on the paper transport belt 24 by the charging of 1C. The above black, yellow color,
The transfer paper 14 to which the magenta and cyan toner images are transferred is separated from the paper transport belt 24,
As described above, the fixing device 31 receives the fixing process,
A color image is formed.

Further, the transfer paper 14 is supplied from any one of the plurality of paper feed cassettes 15, 16 and 17, and is conveyed by the registration roll 23 onto the paper conveyance belt 24 at a predetermined timing. Is held and transported on the paper transport belt 24 by the charging device 41 and the charging roll 42.

The photosensitive drums 6K, 6Y, 6
After the toner image transfer step is completed, the M and 6C are neutralized by the pre-cleaning neutralizers 12K, 12Y, 12M, and 12C, and are cleaned by the cleaners 13K, 13Y, 13M, 1M
3C removes residual toner and the like, and prepares for the next image forming process.

After the transfer paper 14 is peeled off, the paper transport belt 24 is neutralized by a pair of neutralizing corotrons 43 and 44 for the paper transport belt in the orbit around the transfer paper 14. The surface is
The cleaning device 47 including the rotating brush 45 and the blade 46 removes toner, paper dust, and the like.

In the digital color copying machine constructed as described above, as the driving means 48 for rotatingly driving the photosensitive drums 6K, 6Y, 6M and 6C, for example, the following means are used. The photosensitive drum 6K,
6Y, 6M and 6C are rotationally driven by the driving means 48 shown in FIG.
As shown in the figure, each of the photosensitive drums 6K, 6Y, 6M, 6C
The same configuration is provided for each, but here, the photosensitive drum 6K will be described. As shown in FIG. 8, the driving means 48 of the photosensitive drum
A photosensitive drum 6 is provided between a sub-frame 51 attached to a first frame 50 located on the front side of the copying machine main body and a second frame 52 arranged in parallel with the first frame 50.
K to be rotatably supported, and the photosensitive drum 6
A drive shaft 56 connected to the K rotation shaft 54 via a coupling 55 is rotatably supported between the second frame 52 and the third frame 57. The photosensitive drum 6K includes a drive motor 58 including a pulse motor,
A motor shaft gear 60 provided on a rotation shaft 59 of the drive motor 58, a first intermediate gear 61 meshing with the motor shaft gear 60, and a second intermediate gear fixed to the same shaft as the first intermediate gear 61 62 and a photoconductor drive gear 63 fixed to a drive shaft 56 of the photoconductor drum 6 </ b> K that meshes with the second intermediate gear 62. An encoder 64 is attached to the drive shaft 56 of the photosensitive drum 6K. The encoder 64 detects the rotation state of the photosensitive drum 6K, and outputs a detection signal to the C as a control unit as described below.
The rotational speed of the photosensitive drum 6K is controlled so as to be a predetermined speed by feeding back to the drive motor 58 via the PU 65. In the drawing, 67 is the photosensitive drum 6
The flywheel attached to the K rotation shaft 59 is shown.

The drive roll 25 for rotating the paper transport belt 24 is also driven to rotate by the same drive means as the drive means for the photosensitive drum 6. In FIG. 7, reference numeral 68 denotes the photosensitive drum 6.
And a belt encoder for detecting the rotation of the sheet transport belt 24. The belt encoder 68 outputs a signal synchronized with the rotation of the photosensitive drum 6. .

By the way, as described above, the driving means 48 for rotationally driving the photosensitive drums 6K, 6Y, 6M, 6C.
Is similarly provided for each photoconductor drum, and each of the photoconductor drums 6K, 6Y, 6M,
As shown in FIG. 9, the driving means 48 of 6C is driven and controlled by a CPU 65 as a control means via a timer IC 66. The timer IC 66 drives the driving motor 58 at a predetermined rotational speed. The reference clock pulse (REF CLK) of a predetermined frequency (for example, 10 MHz) output from the crystal oscillator 67 is frequency-divided at a cycle designated by the following, and is applied to the drive motor 58 as a drive pulse (Mot CLK). Has become. As the drive motor 58, for example, one that drives the photosensitive drum 6K by one rotation with 200 pulses is used. Also, the belt encoder 6
As the number 8, for example, 360 pulses are output when the belt encoder 68 makes one rotation.

For example, when the rotation speed of each of the photosensitive drums 6K, 6Y, 6M, and 6C is finely adjusted, the driving means 48 is approximately 84 μm / rotation per one rotation of the photosensitive drums 6K, 6Y, 6M, and 6C. It has a step resolution. As a result, when the angle from the exposure position of the photosensitive drum 6 to the transfer position is set to 180 degrees, the correction error of the driving unit 48 can be corrected by a correction resolution per one turn of the photosensitive drum 6 (84 degrees).
μm / step), that is, about 42 μm.

Therefore, improving the correction resolution of the driving means 48 can reduce the frequency of correcting the rotation speed of the photosensitive drum 6 or change the average speed of the photosensitive drum 6 due to color registration or transfer paper transfer. It is desirable to reduce the influence on the registration or to improve the speed difference between the photosensitive drum 6 and the paper transport belt 24.

As a means for improving the correction resolution of the driving means 48, as shown in FIG. 9, a predetermined frequency (for example, 10
MHz) of the reference clock pulse (REF CLK), the frequency dividing circuit may be configured in a plurality of stages, the gear ratio of a drive system for driving the photosensitive drum 6 may be increased,
Increasing the oscillation frequency of the crystal oscillator 67 may be used. Therefore, by taking these measures, the correction resolution of the driving means 48 can be improved, the frequency of correcting the rotation speed of the photosensitive drum 6 can be reduced, and the change in the average speed of the photosensitive drum 6 can be controlled by the color resist. To reduce the effect on the registration and the registration of the transfer paper, or the photosensitive drum 6 and the paper transport belt 2
4 can be improved.

In this embodiment, the drive means 48 of each of the photosensitive drums 6K, 6Y, 6M, 6C uses a common reference clock. That is, the reference clock output from the same reference clock oscillator 67 is input to the driving means 48 of each of the photosensitive drums 6K, 6Y, 6M, 6C. This is because if different reference clocks are used as the control reference clocks for the plurality of photosensitive drums 6K, 6Y, 6M, 6C or the sheet transport belt 24, the drive for a long time will
There is a possibility that their phase relationship may be lost. Therefore,
By using a common reference clock for the plurality of photosensitive drums 6K, 6Y, 6M, 6C or the paper transport belt 24, the phase relationship between the photosensitive drums 6K, 6Y, 6M, 6C or the transfer drum 24 is prevented from being disrupted. can do.

As described above, in the above-described embodiment, in the image forming apparatus including the four image forming units 5K, 5Y, 5M, and 5C having the photosensitive drums 6K, 6Y, 6M, and 6C that are driven to rotate, Each photosensitive drum 6K, 6
The average rotation speeds of Y, 6M, and 6C are the same for all photosensitive drums 6K, 6Y, 6M,
6C, the same speed is set. Therefore, even when four image forming units 5K, 5Y, 5M, and 5C having the photosensitive drums 6K, 6Y, 6M, and 6C are provided, All photosensitive drums 6K, 6Y, 6
By setting the same average rotation speed for M and 6C,
The rotation speed of each of the photosensitive drums 6K, 6Y, 6M, and 6C can be accurately controlled.

In the digital color copying machine constructed as described above, the image forming characteristics of the surface of the photosensitive drum 6 are not constant along the rotating direction of the photosensitive drum 6 but are fixed along the rotating direction. Fluctuating. That is, the image forming characteristics of the surface of the photoconductor drum 6 may be changed due to a change in the gap between the surface of the photoconductor drum 6 and the developing device 9 due to the eccentricity of the photoconductor drum 6, sensitivity unevenness of the surface of the photoconductor drum 6 along the rotation direction, or the like. It is not a constant thing,
As shown in FIG. 2, it fluctuates along the rotation direction.

FIG. 10 is a schematic diagram showing the image forming section of the digital color copying machine together with the control section.

In FIG. 10, reference numeral 70 denotes the sheet transport belt 2
4 is a belt mark for detecting a belt home provided on the reference numeral 4. The belt mark 70 for detecting the belt home is detected by a sensor 71 for detecting the belt home as a first reference position detecting means. The belt mark 70 for detecting the belt home is, for example, the paper transport belt 24.
Is provided near the downstream side of the seam portion 24a.

75K, 75Y, 75M, and 75C are ROS 8K in each of the image forming units 5K, 5Y, 5M, and 5C.
8Y, 8M, 8C, an interface board for sending image signals to the photosensitive drums 6K, 6Y, 6C;
This is a correction substrate for controlling the driving of M and 6C and the like.
As shown in FIG. 9, the correction substrate 76 includes a CPU 65 that controls the driving unit 48 of each of the photosensitive drums 6K, 6Y, 6M, and 6C. Reference numeral 77 denotes an image processing board which collectively handles the memory and image processing.
Is a control board for managing the movement of all of these boards and the entire digital color copying machine.

In the digital color copying machine according to this embodiment having the above arrangement, as shown below, the position generated between the image carrier and the endless carrier such as the transfer material transport belt and the intermediate transfer belt. It is possible to reduce the color difference between different transfer materials due to the displacement, and it is possible to improve the stability of image quality.

That is, in the digital color copying machine according to this embodiment, as shown in FIG. 11, when the power of the apparatus is turned on and the image forming operation is disclosed, the CPU 65
Paper transport belt 24 and photosensitive drums 6K, 6Y, 6
It is determined whether or not M and 6C are rotating (step 10).
1). Then, the sheet transport belt 24 and the photosensitive drum 6
If K, 6Y, 6M, and 6C are not rotating, it waits until they are rotationally driven. When the paper transport belt 24 and the photosensitive drums 6K, 6Y, 6M, 6C are rotating, as shown in FIG. 10, the belt mark 70 for detecting the belt home provided on the paper transport belt 24 is
It is detected by the belt home detection sensor 71, and it is determined whether or not the belt home signal output from the belt home detection sensor 71 is detected (step 102). If the belt home signal has not been detected, the process waits until the belt home signal is detected.

Next, when the belt home signal is detected, the CPU 65 determines whether or not the belt home signal has been detected twice or more (step 103), and the belt home signal has been detected twice or more. If not, the process returns to step 102, and the detection of the belt home signal is repeated until the belt home signal is detected twice or more.

When the belt home signal is detected two or more times, the CPU 65 performs a process of detecting a difference between an integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the sheet conveying belt 24 (step 104). ).

Here, the difference between the integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the sheet conveying belt 24 is determined, for example, by the first reference position detecting means for detecting the reference position of the endless carrier. The output interval of the output first reference position detection signal and the output interval of the second reference position detection signal output from the second reference position detection means for detecting the reference position of the image carrier, or the output interval of the image carrier. It is calculated from the set rotation cycle.

More specifically, the difference between the integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the paper transport belt 24 is, as shown in FIG. 70 is detected by the belt home detection sensor 71, from the rising of the belt home detection pulse output from the belt home detection sensor 71 to the rising of the belt encoder clock output from the belt encoder 68. Is measured using a time counting reference clock. Here, the belt encoder is provided in a driving unit 48 that rotationally drives the photosensitive drum 6, and outputs a pulse synchronized with the rotation of the photosensitive drum 6.

Next, immediately after the rotation of the paper transport belt 24 and the rise of the belt home detection pulse output from the belt home detection sensor 71, the integrated value A of the number of times the clock of the belt encoder 68 rises, Thereafter, counting is performed until the belt home detection pulse rises. Here, the design value of the integrated value A of the number of times the clock of the belt encoder 68 rises is, for example, 72
Set to 00.

Thereafter, the paper transport belt 24 makes one rotation, and the belt mark 70 for detecting the belt home of the paper transport belt 24 is used as a sensor 71 for detecting the belt home.
The time Tb from the rise of the belt home detection pulse output from the belt home detection sensor 71 to the rising of the next belt encoder clock output from the belt encoder 68
Is measured by a reference clock for time counting.

Then, the CPU 65 calculates a difference C between an integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the sheet conveying belt 24 based on the following equation. C = [(A−7200) × 1.111 + Ta + 1.111−Tb] msec Here, the time from the rise of the belt encoder clock output from the belt encoder 68 to the next rise is set to 1.111 msec. .

Next, the CPU 65 calculates the average rotation of the photosensitive drum 6 based on the difference C between the integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the sheet conveying belt 24 calculated as described above. A process for calculating the speed is performed (step 10).
5).

The CPU 65 determines the rotation cycle of the photosensitive drum 6 based on the difference C between the rotation cycle of the sheet conveying belt 24 and the integral multiple of the rotation cycle of the photosensitive drum 6 in order to make the two rotation cycles coincide with each other. The difference C between the two rotation periods is divided into eight equal parts so that the integral period (8 in this example) is equal to the rotation period of the paper transport belt 24, and D = [C ÷ 8]
Control is performed to increase or decrease the average rotation speed of the photosensitive drum 6 (step 106). As shown in FIG. 9, when the average clock speed of the photosensitive drum 6 is changed by dividing the reference clock pulse output from the crystal oscillator 67 by the timer IC 66 and applying the divided clock pulse to the drive motor 58 as shown in FIG. This is performed by changing the number of reference clock pulses divided by the IC 66 by the CPU 65.

The average rotation speed of the photosensitive drum 6 is changed so that the same image is formed at the same position of the image formed by each of the image forming units 5K, 5Y, 5M, and 5C. , Each image forming unit 5K, 5
Each of the photosensitive drums 6K, Y, 5M, and 5C
Even when changing the average rotation speed of 6Y, 6M, 6C, the timing of changing the average rotation speed of each photoconductor drum 6K, 6Y, 6M, 6C is different for each image forming unit for the same image. Each of the image forming units 5K, 5Y, 5M, and 5C is located at the same position of an image to be formed.
The formation positions of images of different colors formed by K, 5Y, 5M, and 5C do not individually change, and it is possible to prevent a color shift or the like from occurring in the same image.

The image forming units 5K, 5Y, 5Y
M, 5C, the respective photosensitive drums 6K, 6Y,
When the average rotation speed of the photosensitive drums 6K and 6C is changed, the images of the respective photosensitive drums 6K, 6Y, 6M and 6C are distorted. In the case of 10 microns, color shift can be found by human eyes, but image distortion cannot be recognized. Therefore, even if the average rotation speed of each photosensitive drum 6K, 6Y, 6M, 6C is changed during image formation, there is no problem. Does not occur.

That is, due to an environmental change such as an increase in the temperature inside the apparatus, a manufacturing error of parts, or the like, the circumference of the paper transport belt 24 is longer than the designed value, and the rotation cycle of the paper transport belt 24 is changed to the rotation cycle of the photosensitive drum 6. When the length of the photosensitive drum 6 is longer than an integral multiple of the photosensitive drum 6, the rotation speed of the photosensitive drum 6 is controlled to decrease by D = [C ÷ 8]. Also, the paper transport belt 24
Is smaller than the design value, and the rotation period of the paper transport belt 24 is shorter than an integral multiple of the rotation period of the photosensitive drum 6, the amount of the photosensitive drum 6 is D = [C ÷ 8]. Is controlled so as to increase the rotation speed.

Thereafter, the CPU 65 performs a process of changing the average rotation speed of the photosensitive drum 6 (step 10).
6), a process of correcting the image forming position on the photosensitive drum 6 is performed (Step 107), and the process returns to Step 101.

The image forming position on the photosensitive drum 6 is corrected by changing the average rotation speed of the photosensitive drum 6 so that the image formed on the photosensitive drum 6 The position transferred to the held transfer paper 14 changes. Therefore, in this embodiment, a process of correcting an image forming position on the photosensitive drum 6 is performed according to a change in the average rotation speed of the photosensitive drum 6.

That is, when the average rotation speed of the photosensitive drum 6 is changed to a high speed, the ROS 8K is changed so that the image forming position on the photosensitive drum 6 is changed to the upstream side in the rotation direction of the photosensitive drum 6. , 8Y, 8M, and 8C, the image writing timing is changed quickly.

When the average rotation speed of the photosensitive drum 6 is changed to a low value, the ROS 8K is changed so that the image forming position on the photosensitive drum 6 is changed to the downstream side in the rotation direction of the photosensitive drum 6. , 8Y, 8M, 8C, the image writing timing is changed later.

In this manner, when the average rotation speed of the photosensitive drum 6 is changed to be faster or slower, the image forming position is changed to the upstream or downstream in the rotation direction of the photosensitive drum 6 to change the image forming position. The image on the photosensitive drum 6 can be always transferred to a predetermined position on the transfer paper 14 held on the paper transport belt 24.

The transfer timing of the transfer material is adjusted so that the image is formed at the same position on the transfer material on which the image is finally formed in accordance with the change amount of the average rotation speed of the photosensitive drum 6. You may comprise so that it may change.

As described above, in the digital color copying machine according to the above embodiment, the difference between the integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the paper transport belt 24 is detected, and based on the detection result, The rotation period of the photosensitive drum 6 is controlled by the CPU 65 so that the rotation period of the paper transport belt 24 coincides with the integral multiple of the rotation period of the photosensitive drum 6. Therefore, the circumferential length of the sheet conveying belt 24, as shown in FIG. 13 (a), by an ideal from the length L _B is a design value, a manufacturing error or the like of the environmental changes and parts such as increase of the internal temperature, As shown in FIG. 13B or 13C, the length is reduced to L _B -L _X or L
Even when stretched or the _B + L _Y, and detects the difference between the integer multiple and the rotation period of the sheet conveying belt 24 of the rotation period of the photosensitive drum 6, on the basis of the detection result, the rotation period of the photosensitive drum 6 The CPU 65 controls the photosensitive drum 6 so that the integral multiple matches the rotation cycle of the paper transport belt 24.
By controlling the average rotation speed of the two, as shown in FIG.
It is possible to prevent the image forming position from shifting between the photosensitive drum 6 and the sheet conveying belt 24, and to perform different transfer due to the position shift between the photosensitive drum 6 and the sheet conveying belt 24. A color difference between the papers 14 can be reduced, and a digital color copier excellent in image quality stability can be provided.

FIG. 15 shows another embodiment of a rotation cycle difference detecting means for detecting a difference between an integral multiple of the rotation cycle of the photosensitive drum 6 and the rotation cycle of the sheet conveying belt 24.

Here, the difference between the integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the sheet conveying belt 24 is output from the first reference position detecting means for detecting the reference position of the endless carrier. The output timing of the first reference position detection signal and the second reference position detection means for detecting the reference position of the image carrier detected immediately after or immediately before the output timing of the first reference position detection signal. It is configured to be calculated from the difference between the output timings of the second reference position detection signal.

That is, in this embodiment, the difference between the integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the paper transport belt 24 is, as shown in FIG.
When the belt home detection pulse output from the belt home detection sensor 71 rises when the belt home detection belt mark 70 is detected by the belt home detection sensor 71, the photosensitive drum 6 The time Tc until the rise of the Z clock (one output per rotation of the photosensitive drum 6) output from the drum encoder that detects the rotation of the photosensitive drum 6 is measured by the reference clock of the counter.

Next, the paper transport belt 24 makes one rotation,
When the belt mark 70 for detecting the belt home of the paper transport belt 24 is detected again by the sensor 71 for detecting the belt home, after the belt home detection pulse output from the sensor 71 for detecting the belt home rises, The time Td until the rise of the Z clock (one output per one rotation of the photosensitive drum 6) output from the drum encoder that detects the rotation of the photosensitive drum 6 is also measured by the reference clock of the counter.

Then, the CPU 65 calculates a difference E between an integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the sheet conveying belt 24 based on the following equation. E = [Tc-Td] msec

The CPU 65 adjusts the rotation period of the photosensitive drum 6 based on the difference E between the rotation period of the sheet conveying belt 24 and the integral multiple of the rotation period of the photosensitive drum 6 to make the rotation periods of the photosensitive drum 6 coincide with each other. Integer of rotation period (8 in this example)
The difference E between the two rotation periods is divided into eight so that F = [E ÷
8], control for changing the average rotation speed of the photosensitive drum 6 is performed.

In this embodiment, from the rising of the belt home detection pulse output from the belt home detecting sensor 71 to the rising of the Z clock output from the drum encoder for detecting the rotation of the photosensitive drum 6. Since the time Tc may be measured by the reference clock of the counter, the configuration of the rotation cycle difference detecting means can be simplified, which is desirable.

In the first embodiment, the rotation cycle of the image carrier or the endless carrier is controlled so that the integral multiple of the rotation cycle of the image carrier is equal to the rotation cycle of the endless carrier. Although the case has been described, when controlling the rotation cycle of the endless carrier to be equal to an integral multiple of the rotation cycle of the image carrier, depending on the image forming apparatus, an image on the When transferring onto the transfer material or the endless carrier, which is carried on the endless carrier, a speed difference is set between the image carrier and the endless carrier, so-called slip transfer is performed consciously. There is an apparatus that improves the transfer efficiency, etc.

The method of setting the speed difference between the image carrier and the endless carrier is the same as the method of setting the relationship “surface speed of image carrier> surface speed of endless carrier” in reverse. "Surface velocity of image carrier <Surface velocity of endless carrier"
In some cases, the relationship may be set to:

By the way, in order to perform the so-called slip transfer as described above, even in an image forming apparatus in which a speed difference is set between the image carrier and the endless carrier, it is an integral multiple of the rotation period of the image carrier. When the rotation cycle of the endless carrier is shifted from that of the endless carrier, a color difference appears between different transfer materials as described in the related art.

In the image forming apparatus for performing the slip transfer, a difference is set in advance in the circumferential length between the image carrier and the endless carrier in order to set a speed difference between the image carrier and the endless carrier. May be. As described above, when a difference is previously set in the peripheral length between the image carrier and the endless carrier, the rotation period of the endless carrier is equal to the integral multiple of the rotation period of the image carrier as in the present invention. In addition, when the rotation period of the image carrier or the endless carrier is controlled, if the peripheral length of the endless carrier is maximally fluctuated due to environmental fluctuation or the like, the above-described speed relationship may not be satisfied. There is.

Therefore, in the image forming apparatus employing the so-called slip transfer, even if the peripheral length of the endless carrier has a maximum fluctuation, "surface speed of image carrier> surface speed of endless carrier". The difference between the speed of the image carrier and the surface of the endless carrier is set so that the relationship, or the surface speed of the image carrier <the surface speed of the endless carrier, is always satisfied. In the case of “speed> surface velocity of endless carrier”, the set value of the peripheral length of the endless carrier is the same as that of the image even if the peripheral length of the endless carrier has the largest fluctuation. The speed difference between the image carrier and the endless carrier is set so as to be equal to or less than an integral multiple of the peripheral length of the carrier, and the relation of “surface speed of the image carrier <surface speed of the endless carrier” is satisfied. In this case, the set value of the circumference of the endless carrier is the largest change in the circumference of the endless carrier. Even if occurs, it is desirable to set such that the peripheral length of the integer times of the image bearing member.

Second Embodiment FIGS. 16 and 17 show a second embodiment of the present invention. In the second embodiment, a plurality of image forming means having a rotatable image carrier are used to form a color image. An apparatus that forms different images and directly forms images having different colors formed by the plurality of image forming units onto a rotatably driven endless carrier, thereby forming images.
In an image forming apparatus that determines the image forming timing on the image carrier based on the position of the endless carrier, a difference between an integral multiple of the rotation cycle of the image carrier and the rotation cycle of the endless carrier is detected. And controlling the rotation cycle of the image carrier or the endless carrier based on the detection result so that the integral multiple of the rotation cycle of the image carrier substantially coincides with the rotation cycle of the endless carrier. Means are provided.

FIG. 16 is an overall configuration diagram showing a tandem type digital color copying machine as an image forming apparatus according to Embodiment 2 of the present invention.

In FIG. 16, reference numeral 101 denotes a main body of a tandem-type digital color copying machine, and a document reading device 104 for reading an image of a document 102 is provided on an upper portion of one end of the digital color copying machine main body 101. It is arranged. The image forming unit 113 of each color of black (K), yellow (Y), magenta (M), and cyan (C) is provided inside the digital color copying machine main body 101.
K, 113Y, 113M, and 113C are arranged at regular intervals in the horizontal direction. Furthermore, the above 4
Image forming units 113K, 113Y, 113M,
Below the 113C, an intermediate transfer belt 125 for transferring the toner images of each color sequentially formed by these image forming units in a state of being superimposed on each other is arranged rotatably in the direction of the arrow. . Then, the toner images of the respective colors multiplexly transferred onto the intermediate transfer belt 125 are collectively transferred onto transfer paper 134 as a transfer material fed from a paper feed cassette 139 or the like, and then the fixing device 137. Is fixed on the transfer paper 134 and discharged to the outside.

FIG. 17 shows the configuration of a tandem-type color electrophotographic copying machine as an image forming apparatus according to Embodiment 2 of the present invention in further detail.

Although the configuration of the present invention will be described here using a tandem type color electrophotographic copying machine, the present invention is also effective in a color printer / facsimile.

In FIG. 16, reference numeral 101 denotes a main body of a tandem-type digital color copying machine, and a platen for pressing an original 102 onto a platen glass 105 is provided on one end of the digital color copying machine main body 101. A cover 103 and a document reading device 104 that reads an image of the document 102 placed on the platen glass 105 are provided. The original reading device 104 illuminates an original 102 placed on a platen glass 105 with a light source 106, and reflects a reflected light image from the original 102 from a full-rate mirror 107, half-rate mirrors 108 and 109, and an imaging lens 110. Scanning exposure is performed on an image reading element 111 such as a CCD through a reduction optical system, and the image reading element 111 converts a color material reflected light image of the document 102 at a predetermined dot density (for example, 16 dots / mm). It is configured to read.

The color material reflected light image of the document 102 read by the document reading device 104 is, for example, red (R),
IPS 112 (Image Processes) is used as document reflectance data of three colors of green (G) and blue (B) (each 8 bits).
Sing System) and the IPS 112
Now, with respect to the reflectance data of the original 2, shading correction, positional deviation correction, lightness / color space conversion, gamma correction,
Predetermined image processing such as frame erasure and color / movement editing is performed.

The image data subjected to the predetermined image processing by the IPS 112 as described above includes yellow (Y), magenta (M), cyan (C), and black (K) (each of 8 bits).
Are converted into four-color original color material gradation data, and as described below, image forming units 113K and 113K of black (K), yellow (Y), magenta (M), and cyan (C), respectively.
ROS 114K, 114Y of Y, 113M, 113C,
114M, 114C (Raster Output S)
ROS114K, 1
In 14Y, 114M, and 114C, image exposure with laser light is performed in accordance with original color material gradation data of a predetermined color.

As described above, four image forming units of black (K), yellow (Y), magenta (M), and cyan (C) are provided inside the tandem-type digital color copying machine main body 1. 113K, 113Y,
113M and 113C are arranged in parallel at a constant interval in the horizontal direction.

The four image forming units 113
K, 113Y, 113M, and 113C have the same configuration, and are roughly divided into a photosensitive drum 115 that rotates at a predetermined rotation speed in the direction of an arrow, and the surface of the photosensitive drum 115 is uniformly charged. And a ROS 11 for exposing an image corresponding to each color to the surface of the photosensitive drum 115 to form an electrostatic latent image.
4, a developing unit 117 for developing the electrostatic latent image formed on the photosensitive drum 115, and a cleaning device 118.

As shown in FIG. 17, the ROS 114 modulates the semiconductor laser 119 according to the original color material gradation data, and emits a laser beam LB from the semiconductor laser 119 according to the gradation data. The laser beam LB emitted from the semiconductor laser 119 is deflected and scanned by the rotating polygon mirror 122 via the reflection mirrors 120 and 121, and is again image-bearing via the reflection mirrors 120 and 121 and the plurality of reflection mirrors 123 and 124. The photosensitive drum 115 as a body is scanned and exposed.

From the IPS 112, the image forming units 113K, 113Y, 113M, 113 of the respective colors of black (K), yellow (Y), magenta (M), and cyan (C) are provided.
C, the image data of each color is sequentially output to the ROSs 114K, 114Y, 114M, and 114C.
Laser beams LB emitted from 4K, 114Y, 114M, and 114C according to image data are scanned and exposed on the surfaces of respective photosensitive drums 115K, 115Y, 115M, and 115C to form electrostatic latent images. The electrostatic latent images formed on the respective photosensitive drums 115K, 115Y, 115M, and 115C are developed by the developing devices 117K, 117Y, and 117C.
The toner images are developed as black (K), yellow (Y), magenta (M), and cyan (C) toner images by 17M and 117C, respectively.

Each of the above image forming units 113K, 113
Y, 113M, 113C photoconductor drums 115K, 11
The toner images of black (K), yellow (Y), magenta (M), and cyan (C) sequentially formed on 5Y, 115M, and 115C are image-forming units 113.
The primary transfer rolls 126K, 126Y, 126M, and 126C transfer the image onto the intermediate transfer belt 125 as an intermediate transfer member disposed below K, 113Y, 113M, and 113C. This intermediate transfer belt 125
Drive roll 127 and stripping roll 128
, Steering roll 129 and idle roll 13
0, backup roll 131, and idle roll 1
32, and is circulated at a predetermined speed in a direction indicated by an arrow by a drive roll 127 rotated by a dedicated drive motor having excellent constant speed (not shown). Has become. As the transfer belt 125, for example, an endless belt is formed by forming a synthetic resin film such as polyimide having flexibility in a belt shape and connecting both ends of the synthetic resin film formed in the belt shape by means such as welding. What was formed in the shape is used. Therefore, the intermediate transfer belt 125 necessarily has a seam portion 125a which is a connection portion of the synthetic resin film.

The toner images of each color of black (K), yellow (Y), magenta (M), and cyan (C) transferred on the intermediate transfer belt 125 in a multiplexed manner are
The transfer paper 134, which is secondarily transferred onto the transfer paper 134 by the pressing force and the electrostatic force by the secondary transfer roll 133 pressed against the base 31 and the toner image of each color is transferred, by the two conveyor belts 135 and 136. The sheet is transported to the fixing device 137. Then, the transfer paper 134 onto which the toner images of the respective colors have been transferred undergoes a fixing process by heat and pressure by a fixing device 137, and is discharged onto a discharge tray 138 provided outside the copying machine main body 101.

As shown in FIG. 17, the transfer paper 134 has a predetermined size from one of the plurality of paper feed cassettes 139, 140 and 141 and is supplied to the paper feed roller 142.
And a registration roller 14 via a paper transport path 146 including a pair of paper transport rollers 143, 144, and 145.
7 once. The paper cassettes 139 and 14
Transfer paper 13 supplied from any one of 0 and 141
4 is fed onto the intermediate transfer belt 125 by a registration roll 147 that is driven to rotate at a predetermined timing.

Then, the four image forming units 113K, 113K, 1K of black, yellow, magenta and cyan colors are used.
In 13Y, 113M, and 113C, as described above, black, yellow, magenta, and cyan toner images are sequentially formed at predetermined timings.

Incidentally, the photosensitive drums 115K, 115
After the toner image transfer step is completed, the cleaning devices 118K, 118Y and 118C
M and 118C remove residual toner, paper dust, and the like, and prepare for the next image forming process. Further, residual toner is removed from the intermediate transfer belt 125 by the belt cleaner 148.

In the second embodiment, a difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is detected, and based on the detection result, the rotation period of the image carrier is determined. A control means is provided for controlling the rotation cycle of the image carrier or the endless carrier so that the integral multiple substantially matches the rotation cycle of the endless carrier.

In the second embodiment, the control means comprises means for controlling the rotation period of the endless carrier, and the rotation of the endless carrier is controlled in accordance with the detected difference in the rotation period. It is configured to be performed by changing the average rotation speed of the endless carrier.

FIG. 18 is a block diagram showing a drive system for driving the intermediate transfer belt of the tandem type digital color copying machine.

Driving means 15 for this intermediate transfer belt 124
Reference numeral 0 denotes a frame 151 located on the front side of the intermediate transfer belt unit, as shown in FIG.
0 and a frame 152 arranged in parallel with the drive roller 127 of the intermediate transfer belt 124 so as to be rotatable, and the rotation shaft 1 of the drive roll 127
The gear 154 is provided with a gear 154. The drive roll 127 is driven by a plurality of gears 156 by a drive motor 155 composed of a pulse motor.
It is designed to be rotationally driven through .about.160. An encoder 161 is attached to the rotation shaft 153 of the drive roll 127. The encoder 161 detects the rotation state of the drive roll 127, and outputs a detection signal via the CPU 65 as control means as described below. The rotation of the drive roll 127 is controlled so as to be a predetermined speed by feeding back to the drive motor 155.

In the digital color copying machine according to the second embodiment having the above-described configuration, as described below, the image is generated between the image carrier and the endless carrier such as the transfer material conveying belt and the intermediate transfer belt. It is possible to reduce the color difference between different transfer materials due to the displacement, and to improve the stability of image quality.

That is, in the digital color copying machine according to the second embodiment, as shown in FIG. 19, when the power of the apparatus is turned on and the image forming operation is disclosed, the CPU 65
Are the intermediate transfer belt 127 and the photosensitive drum 115K,
It is determined whether or not 115Y, 115M, and 115C are rotating (step 201). Then, the intermediate transfer belt 127
And photosensitive drums 115K, 115Y, 115M, 11
If 5C is not rotating, it waits until these are driven to rotate. When the intermediate transfer belt 127 and the photosensitive drums 115K, 115Y, 115M, 115C are rotating, the belt mark 70 for detecting the belt home provided on the intermediate transfer belt 127 is detected by the sensor 71 for detecting the belt home. It is determined whether or not a belt home signal output from the belt home detection sensor 71 is detected (step 202). If the belt home signal has not been detected, the process waits until the belt home signal is detected.

Next, when the belt home signal is detected, the CPU 65 determines whether or not the belt home signal has been detected twice or more (step 203), and the belt home signal has been detected twice or more. If not, the process returns to step 202, and the detection of the belt home signal is repeated until the belt home signal is detected twice or more.

When the belt home signal is detected twice or more, the CPU 65 performs a process of detecting a difference between an integral multiple of the rotation period of the photosensitive drum 115 and the rotation period of the intermediate transfer belt 127 (step 204). ).

Here, the difference between the integral multiple of the rotation period of the photosensitive drum 115 and the rotation period of the intermediate transfer belt 127 is output from the first reference position detecting means for detecting the reference position of the endless carrier. The output timing of the first reference position detection signal and the second reference position detection means for detecting the reference position of the image carrier detected immediately after or immediately before the output timing of the first reference position detection signal. It is configured to be calculated from the difference between the output timings of the second reference position detection signal.

To further explain, the photosensitive drum 11
The difference between the rotation cycle of the intermediate transfer belt 127 and the integral multiple of the rotation cycle of the intermediate transfer belt 127 is, as shown in FIG.
7, when the belt mark 70 for detecting the belt home is detected by the sensor 71 for detecting the belt home, after the belt home detection pulse output from the sensor 71 for detecting the belt home rises, the photosensitive drum is exposed immediately before the pulse. The time Tc 'until the rising of the Z clock (one output per one rotation of the photosensitive drum 6) output from the drum encoder that detects the rotation of the body drum 6 is measured by the reference clock of the counter.

In this case, unlike FIG. 15, the Z clock output from the drum encoder rises earlier than the belt home detection pulse, so that the Z clock output from the drum encoder rises before If the rising of the belt home detection pulse is not detected next, the count value of the counter is reset, and after the Z clock output from the drum encoder rises, the counting of the belt home detection pulse is started. When the rising edge is detected, the count value of the counter at that time is set to Tc ′.

Next, when the intermediate transfer belt 127 rotates once and the belt mark 70 for detecting the belt home of the intermediate transfer belt 127 is detected again by the sensor 71 for detecting the belt home, the belt home detection is performed. The time Td 'from the rise of the belt home detection pulse output from the sensor 71 to the rise of the Z clock output from the drum encoder that detects the rotation of the photosensitive drum 6 immediately before that is determined by the reference clock of the counter. measure. The measurement of the time Td ′ is performed in the same manner as the measurement of the time Tc ′ described above.

Then, the CPU 65 calculates a difference E 'between an integral multiple of the rotation period of the photosensitive drum 6 and the rotation period of the intermediate transfer belt 127 based on the following equation. E ′ = [Tc′−Td ′] msec

In this embodiment, from the rising of the belt home detecting pulse output from the belt home detecting sensor 71 to the rising of the Z clock output from the drum encoder for detecting the rotation of the photosensitive drum 115. Since the time Tc may be measured by the reference clock of the counter, the configuration of the rotation cycle difference detecting means can be simplified, which is desirable.

Next, the CPU 65 sets the photosensitive drum 115
The average rotation speed of the intermediate transfer belt 127 is calculated based on a difference E between the integral multiple of the rotation period of the intermediate transfer belt 127 and the rotation period of the intermediate transfer belt 127 (step 205).

The CPU 65 determines the rotation period of the photosensitive drum 115 based on the difference E between the rotation period of the intermediate transfer belt 127 and the integral multiple of the rotation period of the photosensitive drum 115 so as to make the two rotation periods coincide with each other. Is controlled so as to increase or decrease the average rotation speed of the intermediate transfer belt 127 by the difference E 'between the rotation periods of the intermediate transfer belt 127 so that the integral period (8 in this example) becomes equal to the rotation period of the intermediate transfer belt 127. Perform (step 106). As shown in FIG. 9, when the average clock speed of the intermediate transfer belt 127 is changed and the reference clock pulse output from the crystal oscillator 67 is frequency-divided by the timer IC 66 and applied to the drive motor 58, This is performed by changing the number of reference clock pulses divided by the IC 66 by the CPU 65.

That is, the circumferential length of the intermediate transfer belt 125 is longer than the designed value due to environmental changes such as an increase in the temperature inside the apparatus, manufacturing errors of parts, and the like. If the length of the intermediate transfer belt 125 is longer than an integral multiple of
Is controlled so as to increase the rotation speed. Further, when the circumference of the intermediate transfer belt 125 is smaller than the design value and the rotation cycle of the intermediate transfer belt 125 is shorter than an integral multiple of the rotation cycle of the photosensitive drum 115, the amount corresponding to E is obtained. The rotation speed of the intermediate transfer belt 125 is controlled so as to decrease.

Thereafter, the CPU 65 operates the intermediate transfer belt 1
After performing the process of changing the average rotation speed of step S25 (step 106), the process of correcting the writing speed of the image writing unit for writing the image on the photosensitive drum 115 is also performed (step 107). Return to

The processing for correcting the writing speed of the image writing means for writing an image on the photosensitive drum 115 is performed by changing the average rotation speed of the intermediate transfer belt 125 so that the image formed on the photosensitive drum 116 is changed. , Intermediate transfer belt 125
When transferred to the top, the magnification of the image changes. Therefore, in the second embodiment, a process of correcting the writing speed of the ROS 114 as an image writing unit that writes an image on the photosensitive drum 115 is performed according to the change in the average rotation speed of the intermediate transfer belt 125. The magnification of the image transferred onto the intermediate transfer belt 125 is always equal to a predetermined magnification.

As described above, in the digital color copying machine according to the above embodiment, the difference between the integral multiple of the rotation period of the photosensitive drum 115 and the rotation period of the intermediate transfer belt 125 is detected, and based on the detection result. The rotation cycle of the intermediate transfer belt 125 is set to C such that the integer multiple of the rotation cycle of the photosensitive drum 115 matches the rotation cycle of the intermediate transfer belt 125.
It is configured to be controlled by PU65. Therefore, even if the circumference of the intermediate transfer belt 125 contracts or expands due to an environmental change such as an increase in the temperature inside the apparatus or a manufacturing error of a part, the intermediate transfer belt 125 has an integral multiple of the rotation period of the photosensitive drum 115 and an intermediate transfer belt. 125 is detected, and based on the detection result, the photosensitive drum 115 is detected.
By controlling the average rotation speed of the intermediate transfer belt 125 by the CPU 65 so that the rotation period of the intermediate transfer belt 125 matches the integral multiple of the rotation period of the intermediate transfer belt 125, both rotation periods can be matched with each other. It is possible to prevent the image forming position from being shifted between the photosensitive drum 115 and the intermediate transfer belt 125, and to perform different transfer due to the positional shift between the photosensitive drum 115 and the intermediate transfer belt 125. A color difference between the papers 134 can be reduced, and a digital color copying machine excellent in image quality stability can be provided.

The other configuration and operation are the same as those of the first embodiment, and the description is omitted.

Third Embodiment FIG. 21 shows a third embodiment of the present invention. In the third embodiment, images of different colors are formed by a single image forming means having a rotatably driven image carrier. Forming, images of different colors formed by the image forming means,
By transferring onto an endless carrier that is driven to rotate,
In an image forming apparatus for forming an image, a difference between an integral multiple of the rotation cycle of the image carrier and the rotation cycle of the endless carrier is detected, and based on the detection result, image formation on the endless carrier is performed. It is configured to include a control unit that instantaneously controls the rotation drive of the endless carrier in the non-image portion so that the positions match.

FIG. 21 shows a color electrophotographic copying machine as an image forming apparatus according to Embodiment 3 of the present invention.

In FIG. 21, reference numeral 201 denotes a main body of the color electrophotographic copying machine, and an original 202 is automatically conveyed to the upper portion of the main body 201 of the color electrophotographic copying machine in a state where the originals 202 are separated one by one. Automatic document feeder 203
And a document reading device 204 that reads an image of the document 202 conveyed by the automatic document conveying device 203. The document reading device 204 illuminates a document 202 placed on a platen glass 205 with a light source 206, and reflects a reflected light image from the document 202 from a full-rate mirror 207, half-rate mirrors 208 and 209, and an imaging lens 210. A scanning exposure is performed on an image reading element 211 such as a CCD through a reduction optical system, and the image reading element 211 converts a color material reflected light image of the original 202 at a predetermined dot density (for example, 16 dots / mm). It is designed to read.

The color material reflected light image of the document 202 read by the document reading device 204 is, for example, red (R),
Document reflectance data of three colors of green (G) and blue (B) (each 8 bits) are sent to the image processing device 212, and the image processing device 212 performs shading correction on the reflectance data of the document 2 , Position shift correction, brightness / color space conversion,
Predetermined image processing such as gamma correction, frame erasure, and color / movement editing is performed.

The image data subjected to the predetermined image processing by the image processing device 212 as described above includes yellow (Y), magenta (M), cyan (C), black (B
K) ROS213 (Raster Output Scan) as four-color original color material gradation data (8 bits each)
The ROS 213 performs image exposure using laser light in accordance with the original color material gradation data.

An image forming means A capable of forming a plurality of toner images of different colors is provided inside the main body 201 of the color electrophotographic copying machine. The image forming unit A mainly includes a photosensitive drum 217 as an image carrier on which an electrostatic latent image is formed, and a plurality of images having different colors by developing the electrostatic latent image formed on the photosensitive drum 217. Developing device 21 as a developing means capable of forming a toner image
9.

As shown in FIG. 21, the ROS 213 modulates a semiconductor laser (not shown) according to the original reproduction color material gradation data, and emits laser light LB from the semiconductor laser according to the gradation data. The laser light LB emitted from the semiconductor laser is applied to a rotating polygon mirror 214.
Drum 21 serving as an image carrier through the f · θ lens 215 and the reflection mirror 216
7 is scanned and exposed.

The ROS 213 causes the laser beam LB
The photosensitive drum 217 to be scanned and exposed is driven to rotate at a predetermined speed along a direction indicated by an arrow by a driving unit (not shown). The surface of the photosensitive drum 217 is charged to a predetermined polarity (for example, a negative polarity) and a potential by a scorotron 218 for primary charging in advance, and then the laser light LB according to the document reproduction color material gradation data.
Are scanned and exposed to form an electrostatic latent image.
The electrostatic latent image formed on the photoconductor drum 217 includes four color developing units 219Y, 219M, and 219 of yellow (Y), magenta (M), cyan (C), and black (BK).
C, rotary developing device 21 equipped with 219BK
As a result, for example, the toner 9 is reversely developed with a toner (charged color material) charged to a negative polarity having the same polarity as the charged polarity of the photoconductor drum 217 to form a toner image of a predetermined color. still,
The toner image formed on the photosensitive drum 217 is charged with a negative polarity by the pre-transfer charger 220 as necessary, and the charge amount is adjusted.

The toner images of each color formed on the photosensitive drum 217 are transferred onto an intermediate transfer belt 221 as an intermediate transfer member disposed below the photosensitive drum 217.
Multiple transfer is performed by a primary transfer roll 222 as a first transfer unit. The intermediate transfer belt 221 is moved at the same moving speed as the peripheral speed of the photosensitive drum 217 by a driving roll 223, a driven roll 224a, a tension roll 224b, and a backup roll 225 as an opposing roll constituting a part of the secondary transfer unit. , So as to be rotatable along the arrow direction.

On the intermediate transfer belt 221, yellow (Y), magenta (M), cyan (C), and black (BK) are formed on the photosensitive drum 217 according to the color of the image to be formed. All or some of the toner images of the four colors are transferred by the primary transfer roll 222 in a state of being sequentially superimposed. The toner image transferred onto the intermediate transfer belt 221 is transferred onto a transfer sheet 226 as a transfer material conveyed to a secondary transfer position at a predetermined timing, on a backup roll 225 supporting the intermediate transfer belt 221.
Is transferred by the pressing force and the electrostatic attraction force of the secondary transfer roll 227 which constitutes a part of the second transfer means which is pressed against the backup roll 225. Transfer paper 22
Reference numeral 6 denotes a predetermined size from one of a plurality of paper feed cassettes 228, 229, 230, and 231 as a plurality of recording medium housing members disposed in the lower part of the color electrophotographic copying machine main body 201 as shown in FIG. Is the feed roll 22
8a, 229a, 230a, and 231a. The fed transfer paper 226 is transported by a plurality of transport rolls 2.
The intermediate transfer belt 221 is conveyed to the secondary transfer position of the intermediate transfer belt 221 at a predetermined timing by the registration roller 32 and the registration roll 233. Then, as described above, the intermediate transfer belt 22 is transferred onto the transfer paper 226 by the backup roll 225 and the secondary transfer roll 227 as secondary transfer means.
1, a toner image of a predetermined color is collectively transferred from above.

The transfer paper 226 onto which the toner image of a predetermined color has been transferred from the intermediate transfer belt 221 is separated from the intermediate transfer belt 221 and then transferred to the transport belt 234.
Is transported to the fixing device 235 by the fixing device 2.
The toner image is fixed on the transfer paper 226 by heat and pressure by 35, and in the case of single-sided copying, the toner image is discharged onto the paper discharge tray 236 as it is to complete the color image copying process.

On the other hand, in the case of double-sided copying, the transfer sheet 226 having the color image formed on the first side (front side) is not discharged onto the discharge tray 236 as it is, but is transported downward by a reversing gate (not shown). The tri-roll 237 and the reversing roll 23 whose directions are changed and three rolls are pressed against each other
8, the sheet is once conveyed to the reversing path 239. Then, the transfer sheet 226 is conveyed to the two-sided passage 240 by the reversing roll 238 which is reversed this time, and once conveyed to the registration roll 233 by the conveying rolls 241 provided in the two-sided passage 240 and stopped. The transfer paper 226 is again conveyed by the registration roll 233 in synchronization with the toner image on the intermediate transfer belt 221, and the transfer / fixing process of the toner image on the second surface (back surface) of the transfer paper 226 is performed. After the discharge tray 2
36.

In FIG. 21, reference numeral 242 denotes a cleaning device for removing residual toner, paper dust and the like from the surface of the photosensitive drum 217 after the completion of the transfer step, and 243 a device for cleaning the intermediate transfer belt 221. Reference numeral 244 denotes a manual transfer tray.

In the third embodiment, the difference between the integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is detected, and the image on the endless carrier is detected based on the detection result. The image forming apparatus is provided with control means for instantaneously controlling the rotational driving of the endless carrier in the non-image portion so that the forming positions coincide with each other.

FIG. 22 is a block diagram showing a drive system for driving the photosensitive drum and the intermediate transfer belt of the tandem type digital color copying machine.

Driving means 250 for this photosensitive drum 217
As shown in FIG. 22, the photosensitive drum 217 is rotatable between a first frame 251 located on the front side of the copying machine main body and a second frame 252 arranged in parallel with the first frame 251. And the rotation shaft 253 of the photosensitive drum 217 is rotatably supported between the second frame 252 and the third frame 254. And
The photosensitive drum 217 includes a drive motor 255 composed of a pulse motor, a motor shaft gear 256 provided on a rotation shaft of the drive motor 255, a first intermediate gear 257 meshing with the motor shaft gear 256, Second intermediate gear 25 fixed to the same shaft as one intermediate gear 257
8 and a photoconductor drive gear 25 fixed to a drive shaft 253 of the photoconductor drum 217 meshing with the second intermediate gear 258.
9 to rotate. Also,
An encoder 260 is attached to the drive shaft 253 of the photosensitive drum 217.
The rotation state of the photosensitive drum 217 is detected by 60,
The detection signal is sent to the CPU 6 as control means as described below.
5 to the drive motor 255 via
The rotation speed of the photosensitive drum 217 is controlled to be a predetermined speed.

The driving means 2 for the intermediate transfer belt 221
A drive roller 223 for the intermediate transfer belt 221 is rotatably supported between a frame 261 located on the front side of the intermediate transfer belt unit and a frame 262 arranged in parallel with the frame 261. The gear 263 is provided on the rotation shaft of the drive roll 223. Then, the drive roll 22
Numeral 3 is driven to rotate by a driving motor 255 composed of a pulse motor via a plurality of gears 264 to 267.

In the digital color copying machine according to the third embodiment having the above-described configuration, as described below, the image is generated between the image carrier and the endless carrier such as the transfer material conveying belt and the intermediate transfer belt. It is possible to reduce the color difference between different transfer materials due to the displacement, and to improve the stability of image quality.

That is, in the digital color copying machine according to the third embodiment, as shown in FIG. 21, the difference between the rotation period of the intermediate transfer belt 221 and the integral multiple of the rotation period of the photosensitive drum 217 is detected. Based on the detection result, the image forming position on the intermediate transfer belt 221 is matched so that
In the non-image portion, a CPU 65 is provided as control means for instantaneously controlling the rotational drive of the intermediate transfer belt 221.

In the third embodiment, in the case of an image forming apparatus in which images having different colors are formed by a single image forming unit having the photosensitive drum 217 driven to rotate, only one image forming unit is provided. Therefore, the image forming positions on the intermediate transfer belt 221 coincide with each other by instantaneously controlling the rotation drive of the intermediate transfer belt 221 in the non-image portion without the plural image forming units simultaneously forming an image. And the configuration of the control means can be simplified.

The other structure and operation are the same as those of the first embodiment, and the description is omitted.

[0184]

As described above, according to the present invention, the transfer between different transfer materials caused by the positional shift between the image carrier and the endless carrier such as the transfer material transport belt and the intermediate transfer belt. It is possible to provide a drive control method of an image forming apparatus, an apparatus thereof, and an image forming apparatus, which can reduce color difference and have excellent image quality stability.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a case where the belt length of the image forming apparatus according to the embodiment of the present invention changes.

FIG. 4 is a configuration diagram showing a digital color copying machine as an image forming apparatus to which the drive control device according to the first embodiment of the present invention is applied;

FIG. 5 is a configuration diagram showing a digital color copying machine as an image forming apparatus to which the drive control device according to the first embodiment of the present invention is applied.

FIG. 6 is an explanatory diagram showing a state in which an image is formed on an intermediate transfer belt.

FIG. 7 is a configuration diagram illustrating a driving unit of a photosensitive drum.

FIG. 8 is a configuration diagram more specifically showing driving means of the photosensitive drum.

FIG. 9 is a block diagram showing a photosensitive drum driving unit.

FIG. 10 is a perspective configuration diagram illustrating an image forming unit and a control unit of the image forming apparatus according to Embodiment 1 of the present invention;

FIG. 11 is a flowchart showing an operation of the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 12 is a timing chart showing a detection operation for detecting a difference between the rotation cycles of the intermediate transfer belt and the photosensitive drum.

FIG. 13 is an explanatory diagram showing a case where the intermediate transfer belt length of the image forming apparatus according to Embodiment 1 of the present invention has changed.

FIG. 14 is an explanatory diagram illustrating a correction process when the intermediate transfer belt length of the image forming apparatus according to the first embodiment of the present invention changes.

FIG. 15 is a timing chart showing another detection operation for detecting the difference between the rotation periods of the intermediate transfer belt and the photosensitive drum.

FIG. 16 is a configuration diagram showing a digital color copying machine as an image forming apparatus to which the drive control device according to the second embodiment of the present invention is applied.

FIG. 17 is a configuration diagram showing a digital color copying machine as an image forming apparatus to which the drive control device according to Embodiment 2 of the present invention is applied.

FIG. 18 is a configuration diagram illustrating a drive system of the intermediate transfer belt.

FIG. 19 is a flowchart showing an operation of the image forming apparatus according to Embodiment 2 of the present invention.

FIG. 20 is a timing chart showing a detection operation for detecting a difference between the rotation periods of the intermediate transfer belt and the photosensitive drum.

FIG. 21 is a configuration diagram showing a digital color copying machine as an image forming apparatus to which a drive control device according to Embodiment 3 of the present invention is applied.

FIG. 22 is a configuration diagram showing a drive system of an image forming apparatus to which a drive control device according to Embodiment 3 of the present invention is applied.

FIG. 23 is a configuration diagram showing a conventional image forming apparatus.

FIG. 24 is a perspective view showing an intermediate transfer belt.

FIG. 25 is a schematic diagram showing image forming timings of the intermediate transfer belt and the photosensitive drum.

FIG. 26 is an explanatory diagram showing an image forming position on the intermediate transfer belt.

FIG. 27 is an explanatory diagram showing an image forming position on the intermediate transfer belt.

FIG. 28 is an explanatory diagram showing an image forming position on the intermediate transfer belt.

FIG. 29 is an explanatory diagram showing a relationship between a photosensitive drum and an image forming position on an intermediate transfer belt.

FIG. 30 is an explanatory diagram showing a relationship between a photosensitive drum and an image forming position on an intermediate transfer belt.

FIG. 31 is an explanatory diagram showing a relationship between a photosensitive drum and an image forming position on an intermediate transfer belt.

FIG. 32 is an explanatory diagram showing development characteristics in one rotation of the photosensitive drum.

[Explanation of symbols]

01K, 01Y, 01M, 01C: image carrier, 02K,
02Y, 02M, 02C: image forming means, 03: endless carrier, 04: transfer material, 05K, 05Y, 05M, 05
C: drive means, 06: control means.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shingo Yano 2274 Hongo, Ebina-shi, Kanagawa Prefecture F-Xerox Co., Ltd. F-term (reference) 2H027 DA16 DA17 DA41 DE02 EB04 EC06 ED02 ED06 ED16 ED24 EE03 EE04 EE06 ZA07 2H030 AA01 AB02 AD16 BB02 BB21 BB42 BB56 BB71

Claims (17)

[Claims] 1. A drive control of an image forming apparatus, comprising: at least one rotatably driven image carrier; and a rotatably driven endless carrier; and controlling the rotational driving of the image carrier and the endless carrier. In the method, a difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is detected, and based on the detection result, an integer multiple of the rotation period of the image carrier and the endless carrier are detected. A drive control method for an image forming apparatus, comprising: controlling a rotation cycle of the image carrier or the endless carrier so that the rotation cycle substantially coincides with the rotation cycle. 2. A drive control of an image forming apparatus, comprising: at least one image carrier that is rotationally driven; and an endless carrier that is rotationally driven, wherein the image forming apparatus controls the rotational drive of the image carrier and the endless carrier. In the apparatus, a difference between an integral multiple of the rotation period of the image carrier and the rotation period of the endless carrier is detected, and based on the detection result, an integral multiple of the rotation period of the image carrier and the endless carrier are detected. A drive control device for an image forming apparatus, comprising: control means for controlling a rotation period of the image carrier or the endless carrier so that the rotation period substantially coincides with the rotation period. 3. An endless carrier, which forms images of different colors by at least one image forming means having an image carrier which is rotationally driven, and which rotationally drives the images of different colors formed by said image forming means. The image is formed by transferring the image onto the transfer material carried on the body or the endless carrier and determining the image forming timing on the image carrier based on the position of the endless carrier. In the image forming apparatus, a difference between an integer multiple of the rotation period of the image carrier and the rotation period of the endless carrier is detected, and based on the detection result, an integer multiple of the rotation period of the image carrier and the endless carrier are detected. An image forming apparatus comprising: a control unit that controls a rotation cycle of the image carrier or the endless carrier so that a rotation cycle of the body substantially coincides with the rotation cycle of the body. 4. A difference between an integral multiple of a rotation cycle of the image carrier and a rotation cycle of the endless carrier is output from a first reference position detecting means for detecting a reference position of the endless carrier. 1
And the second reference position detection means for detecting the reference position of the image carrier.
4. The image forming apparatus according to claim 3, wherein the calculation is performed based on the output interval of the reference position detection signal or the set rotation period of the image carrier. 5. The method according to claim 5, wherein a difference between an integral multiple of a rotation cycle of the image carrier and a rotation cycle of the endless carrier is output from a first reference position detection unit that detects a reference position of the endless carrier. 1
The output timing of the reference position detection signal and the second reference position detection means for detecting the reference position of the image carrier detected immediately before or immediately before the output timing of the first reference position detection signal. 4. The image forming apparatus according to claim 3, wherein the calculation is performed based on a difference between output timings of the reference position detection signal. 6. The control means comprises means for controlling a rotation cycle of the image carrier, wherein the rotation control of the image carrier changes an average rotation speed of the image carrier according to a difference between the detected rotation cycles. The image forming apparatus according to claim 3, wherein the image formation is performed by performing the following. 7. An image is formed on a transfer material carried on a rotatably driven endless carrier or on a predetermined position on the endless carrier in accordance with a change amount of an average rotation speed of the image carrier. 7. The image forming apparatus according to claim 6, wherein the image writing timing in the rotation direction on the image carrier is changed. 8. The transfer timing of the transfer material such that an image is formed at a predetermined position on the transfer material on which an image is finally formed in accordance with the amount of change in the average rotation speed of the image carrier. The image forming apparatus according to claim 6, wherein the image forming apparatus is changed. 9. An image forming apparatus having a plurality of image forming means having image carriers which are driven to rotate, wherein the timing for changing the average rotation speed of each image carrier is different for each of the same images. 7. The image forming apparatus according to claim 6, wherein the image is formed at the same position on an image formed by the image forming unit. 10. An image forming apparatus comprising a plurality of image forming means having an image carrier which is driven to rotate, wherein the average rotation speed of each image carrier is set for each image carrier or in the same drive control system. 7. The image forming apparatus according to claim 6, wherein the setting is performed for each image carrier to be driven and controlled. 11. The image writing timing of each of the image carriers in the rotation direction is individually changed according to a change amount of the average rotation speed of each of the image carriers. Image forming device. 12. The control means comprises means for controlling a rotation cycle of the endless carrier, and the rotation control of the endless carrier is performed based on a difference between the detected rotation cycles. The image forming apparatus according to claim 3, wherein the image forming is performed by changing a speed. 13. A writing speed of an image writing means for writing an image on an image carrier according to a change amount of an average rotation speed of the endless carrier. An image forming apparatus according to claim 1. 14. An image forming apparatus comprising a plurality of image forming means having an image carrier driven to rotate, wherein the timing at which the average rotation speed of the endless carrier is changed is such that all the image forming means are capable of forming an image. 14. The image forming apparatus according to claim 12, wherein the setting is performed when the image is not being transferred. 15. When the image on the image carrier is transferred onto a transfer material carried on the endless carrier or onto the endless carrier, a transfer between the image carrier and the endless carrier is performed. Is set as the speed difference, and the speed difference between the image carrier and the endless carrier is expressed as “surface speed of image carrier> surface speed of endless carrier”.
In the image forming apparatus having the following relationship, the set value of the peripheral length of the endless carrier is an integer multiple of the peripheral length of the image carrier even when a maximum fluctuation occurs in the peripheral length of the endless carrier. The image forming apparatus according to claim 3, wherein the setting is made as follows. 16. When transferring an image on the image carrier to a transfer material carried on the endless carrier or onto the endless carrier, a transfer between the image carrier and the endless carrier is performed. The speed difference between the image carrier and the endless carrier is defined as “the surface speed of the image carrier <the surface speed of the endless carrier”.
In the image forming apparatus having the following relationship, the set value of the peripheral length of the endless carrier is an integral multiple of the peripheral length of the image carrier, even when the peripheral length of the endless carrier has a maximum variation. 4. The image forming apparatus according to claim 3, wherein the setting is made as described above. 17. An endless carrier rotatably driven by forming images of different colors by a single image forming means having an image carrier rotatably driven by said image forming means. In the image forming apparatus that forms an image by transferring the image onto the image carrier and determining the image forming timing on the image carrier based on the position of the endless carrier, an integer of the rotation period of the image carrier is used. The difference between the magnification and the rotation period of the endless carrier is detected, and based on the detection result, the non-image is displayed so that the integral period of the rotation period of the image carrier substantially coincides with the rotation period of the endless carrier. An image forming apparatus comprising: a control unit that instantaneously controls the rotation drive of an endless carrier in a unit.