JP2004252295A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately suppress the positional deviation of an image, in spite of a change in the thickness of, the elongation and vibration of a belt used for the superposition of images, and to form an image of high image quality at a low cost. <P>SOLUTION: The velocity of the belt is directly measured at a transfer position, and the moving velocity of the belt is controlled based on the measurement result. In a tandem type color printer, a velocity detector 35 is arranged on the rotating shaft of a transfer roller 5K corresponding to a photoreceptor drum 1K. The velocity of the transport belt 7 is calculated based on a distance between marks written on the transport belt 7 and a time between the marks, and the rotational velocity of the transfer roller 5K is converted to the velocity of the transfer material transport belt 7. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, a plotter, and the like. More specifically, images formed by a plurality of image forming units are sequentially superimposed and transferred via an endless belt to form one image. To an image forming apparatus.
[0002]
[Prior art]
A plurality of photoconductor drums are arranged on a conveyance path that holds and conveys a transfer material (sheet-shaped recording medium) on a conveyance belt, and a toner image formed on each photoconductor drum is sequentially transferred to the transfer material to form a color image. A tandem image forming apparatus to be created is known.
In a color image forming apparatus that sequentially transfers toner images of different colors formed on a plurality of photosensitive drums to a transfer material, a transfer position shift of the transfer material becomes a problem.
In the transfer belt for transferring the transfer material, the transfer surface speed of the transfer material changes due to a change in thickness, and a transfer position shift occurs. A method for eliminating the rotation fluctuation due to the thickness of the transport belt has been proposed in, for example, JP-A-3-3841 and JP-A-2001-228777.
In these techniques, a distance sensor for detecting the thickness of the belt is provided on the belt conveyance path, and the speed of the belt drive motor is controlled based on the detection result to reduce the speed fluctuation of the transfer material.
[0003]
Further, a method of detecting the speed by a transport roller that supports the rotation of the transport belt has been proposed in, for example, Japanese Patent Application Laid-Open No. H11-126004. This method detects the rotation speed of the conveyor roller at a position distant from the belt drive roller among the support rollers that support the conveyor belt, and uses the roller rotation speed at a position different from the belt drive roller position as the speed of the entire belt. Catch and control.
[0004]
[Patent Document 1]
JP-A-3-3841 [Patent Document 2]
JP 2001-228777 A [Patent Document 3]
Japanese Patent Application Laid-Open No. H11-126004
[Problems to be solved by the invention]
In the technology described in JP-A-3-3841 or JP-A-2001-228777, the speed of the outer periphery of the belt is reduced by detecting the thickness of the transport belt at the position of the drive roller and controlling the speed of the drive motor. be able to. However, a high-precision sensor is required to detect a belt thickness difference with a small change, for example, a change of 1% (0.01 mm) of the belt thickness of 1 mm described in JP-A-2001-228777. Also, since the mounting accuracy of the sensor is required, it is difficult to reduce the cost.
Further, since the thickness of the transfer belt of the transfer material is detected by a high-precision sensor, it is necessary to cope with a change in the detection unit due to scattering of toner and paper dust.
[0006]
According to the technology described in Japanese Patent Application Laid-Open No. H11-126004, a speed error due to a change in the belt thickness at the driving roller position can be reduced by detecting the speed with a roller at a position distant from the roller position for driving the belt. In order to correspond to the belt thickness at the roller position, a high-precision thickness processing technique for the belt circumference is required in which the belt driving position and the belt thickness at the speed detection position are inversely proportional.
Further, since the conveying roller for detecting the speed is located at a position distant from the belt driving roller, there is a problem that the speed fluctuation of the transfer position cannot be accurately detected due to the belt elongation or runout due to the load fluctuation or the speed fluctuation.
[0007]
ADVANTAGE OF THE INVENTION This invention can highly accurately suppress the displacement of an image even if there is a change in the thickness, elongation, runout, etc. of a belt for superimposing images, and can perform high-quality image formation at low cost. It is an object of the present invention to provide an image forming apparatus.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a driving roller, an endless belt wrapped around a plurality of supporting members including the driving roller, and transmitting a rotational force to the driving roller. A driving source for rotating the belt, a plurality of image forming units arranged on the surface side of the belt along the moving direction of the belt, and a drive source provided on an inner surface side of the belt facing each image forming unit. An image forming apparatus having a transfer unit for transferring an image formed by the image forming unit and forming one image by sequentially superimposing images formed by the image forming units while rotating the belt. The speed of the belt is directly measured at the transfer position by the transfer unit, and the moving speed of the belt is controlled based on the measurement result.
[0009]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a belt speed detecting unit that detects a speed of the belt at a transfer position by the transfer unit, and the belt speed detecting unit detects the belt speed based on information detected by the belt speed detecting unit. The configuration has a control means for controlling the drive source.
[0010]
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the transfer unit is a transfer roller, and the belt speed detection unit is provided so as to detect a rotation speed of the transfer roller. Has been adopted.
[0011]
According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the belt speed detecting means is provided so as to be able to detect a rotation speed of the transfer roller close to the drive roller. I have.
[0012]
According to a fifth aspect of the present invention, in the image forming apparatus according to the third aspect, the rotation speed of the driving source by the control unit is set based on the movement speed of the belt and the rotation speed of the transfer roller. It has a configuration.
[0013]
According to a sixth aspect of the present invention, in the image forming apparatus of the third aspect, the rotation speed of the transfer roller is set periodically in accordance with the moving speed of the belt.
[0014]
According to a seventh aspect of the present invention, in the image forming apparatus according to the third aspect, the belt speed detecting means is provided on a side opposite to the transfer roller in a contact direction of the transfer roller with respect to the belt via a rotation shaft of the transfer roller. Has been adopted.
[0015]
According to an eighth aspect of the present invention, in the image forming apparatus of the third aspect, the belt speed detecting means moves integrally with the rotation shaft of the transfer roller.
[0016]
According to a ninth aspect of the present invention, in the image forming apparatus according to the first aspect, a configuration is adopted in which a rotation speed of the driving source can be changed according to a moving speed of the belt.
[0017]
According to a tenth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the image forming means has a photosensitive drum, and a rotation speed of the photosensitive drum is based on detection information of the belt speed detecting means. Is set.
[0018]
According to an eleventh aspect of the present invention, in the image forming apparatus according to the second or third aspect, a plurality of the belt speed detecting units are provided, and based on an average speed obtained from each detection information of the belt speed detecting units. The rotation speed of the drive source is set.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, an outline of the configuration and functions of a tandem-type color printer using a transfer material transport system as an image forming apparatus according to the present embodiment will be described with reference to FIG.
The color printer has a transfer unit 13 at a substantially central portion of an apparatus main body 50. A paper feed cassette 51 is provided below the transfer unit 13, and four image forming units (process units) are provided above. Have been.
The transfer unit 13 includes a drive roller 17, which is rotationally driven by a motor as a drive source (not shown), support rollers (transport rollers) 18, 19, a tension roller 20, and an endless transport looped between these support members. The image forming apparatus includes a belt 7 and transfer rollers 5Y, 5M, 5C, and 5K as transfer units provided on the inner surface side of the belt 7 corresponding to the respective image forming units.
The four image forming units form an image forming unit that forms a yellow (Y) toner image and a magenta (M) toner image in order from the upstream side along the moving direction of the conveyor belt 7 (the direction of the arrow 21). Image forming means for forming a cyan (C) toner image, and an image forming means for forming a black (K) toner image, which are arranged at a predetermined pitch.
[0020]
The configuration of an image forming unit that forms a black toner image will be described. Around the photosensitive drum 1K, a charging roller 2K that contacts the photosensitive drum 1K and charges the drum surface to a predetermined polarity in a clockwise order, and irradiates a laser beam based on write data to the photosensitive drum 1K. An optical writing device 3K for forming an electrostatic latent image on the surface of the photoconductor drum, a developing device 4K for visualizing the electrostatic latent image formed on the photosensitive drum 1K, and a toner image visualized by the developing device 4K. A transfer roller 5K for transferring to a sheet 8 as a transfer material conveyed by a conveyance belt 7, a drum cleaning device 6K for cleaning the toner remaining on the photosensitive drum 1K after the transfer with a blade, and a drum cleaning device 6K for remaining on the photosensitive drum 1K. An unillustrated static eliminator or the like for eliminating static electricity is disposed. Since other image forming units have the same configuration, the corresponding color-coded alphabets are added and description thereof is omitted.
Above each of the developing devices 4Y, 4M, 4C, and 4K, toner supply units 9Y, 9M, 9C, and 9K that supply toner to the developing devices 4Y, 4M, 4C, and 4K are arranged.
[0021]
The paper 8 loaded and stored in the paper feed cassette 51 is separated and fed one by one from the uppermost one by a paper feed roller 10 and a separating member (not shown), and fed to a registration roller pair 12 while being guided by a transport guide 11. It is conveyed toward. After the paper 8 is temporarily stopped by the pair of registration rollers 12 and the skew is corrected, the transfer timing with the toner image formed on each of the photosensitive drums 1Y, 1M, 1C, and 1K is set, and the sheet 8 is pressed by the pair of registration rollers 12. It is sent onto the conveyor belt 7 via the rollers 52.
The paper 8 held and transported by the transport belt 7 is a photosensitive drum 1Y for yellow image formation, a photosensitive drum 1M for magenta image formation, a photosensitive drum 1C for cyan image formation, and a photosensitive drum 1C for black image formation. When passing through the body drum 1K, the toner images of the respective colors are sequentially superimposed and transferred.
[0022]
The sheet 8 onto which the toner image is superimposed and transferred is sent from the process unit of the photosensitive drum 1K for black image formation to the fixing device 14, where the toner image is fixed by heat and pressure. The sheet 8 on which the toner image has been fixed is discharged by a discharge roller pair 15 to a discharge tray 16 formed on the upper surface of the apparatus main body 50.
As described above, the transport belt 7 is stretched between the drive roller 17, the support rollers 18, 19, and the tension roller 20. The tension roller 20 is urged by a belt tension mechanism (not shown), so that the transport belt 7 is constantly tensioned so as to rotate with tension.
The conveyance belt 7 rotates in the direction of the arrow 21 by the rotation of the driving roller 17. Therefore, by detecting the speed of the conveyor belt 7 at the position of the transfer roller 5K, that is, at the transfer position, the influence of the elongation and runout of the conveyor belt 7 can be reduced.
[0023]
Next, the drive configuration of the photosensitive drum 1K and the transfer roller 5K will be described with reference to FIG.
The photoconductor drum 1K is rotatably supported on both frames 1a and 1b by frames 25 and 26 of the apparatus main body 50 via belling 23 and 24. A gear 27 is fixed to one shaft 1a of the photosensitive drum 1K. A stud 28 is fixed to the frame 25, and idler gears 29a and 29b are rotatably inserted into the stud 28. A gear 30a is fixed to the output shaft of the drive motor 30 of the photosensitive drum 1K, and the gear 30a meshes with the idler gear 29b. The idler gear 29a meshes with the gear 27. When the gear 30a of the drive motor 30 rotates, the idler gears 29a and 29b rotate, and the photosensitive drum 1K is rotationally driven.
[0024]
The transport belt 7 is rotated by rotation of a drive roller 17 that is driven to rotate by a drive motor (not shown). Belt guides 7a and 7b are fixed along the entire circumference on the inner surfaces on both side ends in the width direction orthogonal to the moving direction (conveying direction) of the conveying belt 7. The belt guides 7a and 7b are guided to the end surfaces of the drive roller 17, the transport rollers 18 and 19, and the tension roller 20, thereby preventing the transport belt 7 from meandering.
Bearings 31 and 32 are respectively inserted into both shafts 5a and 5b of the transfer roller 5K. The bearings 31 and 32 are inserted into grooves of the frames 25 and 26, and are pressed by the compression springs 33 and 34 in the direction of the photosensitive drum 1K. ing. When the bearings 31 and 32 are pressed by the compression springs 33 and 34, the transfer roller 5 </ b> K is pressed against the photosensitive drum 1 </ b> K with a constant force via the conveyor belt 7.
[0025]
At the end of the shaft 5b of the transfer roller 5K, a speed detecting device 35 is provided as belt speed detecting means for detecting the rotation speed of the transfer roller 5K. On the other hand, a pressing plate 36 is pressed against the end surface of the shaft 5a of the transfer roller 5K.
When the paper 8 passes through the pressure contact portion (transfer portion) between the photosensitive drum 1K and the transfer roller 5K, the charging of the toner image formed on the photosensitive drum 1K to the transfer roller 5K via the pressure contact plate 36 by an application device (not shown). A transfer bias having a polarity opposite to that of the electrodes is applied, and the toner image formed on the photosensitive drum 1 </ b> K is transferred to the paper 8.
[0026]
FIG. 3 is a cross-sectional view of the speed detecting device 35 for detecting the rotation speed of the transfer roller 5K, and FIG. 4 is a diagram excluding the speed detecting device 35 viewed from the rotation shaft end side of the transfer roller 5K. As shown in FIG. 5, grooves 31a and 31b are formed on both sides of the bearing 31 inserted into the shaft 5a of the transfer roller 5K. The grooves 31a and 31b are inserted into the guide holes 25a of the frame 25 and compressed. It is pressed in the direction of the conveyor belt 7 by the spring 32. The same pressing configuration is adopted on the bearing 32 side. In FIG. 5, reference numeral 31d denotes an insertion hole of the shaft 5a.
As shown in FIG. 4, the compression spring 32 is positioned between a spring receiving groove 31 c formed at the lower end of the bearing 31 and the projection 25 b of the frame 25.
[0027]
As shown in FIG. 3, the speed detection device 35 has a disk 37 fixed to the shaft 5 a with a pin 38 and a light reflection type speed detection sensor 39 fixed to the frame 25. The rotational speed of the disk 37 is calculated by speed calculation means (not shown) based on the reflected light of the disk 37 output from the speed detection sensor 39. The speed calculating means constitutes a part of a control means (not shown) (which can also serve as the main controller of the color printer) for controlling the moving speed of the conveyor belt 7 based on the detection information of the speed detecting device 35.
The speed calculation value is corrected by the mark written on the conveyor belt 7. That is, the speed of the transport belt 7 is calculated from the distance between marks, which are written on the transport belt 7 for one round or at equal intervals, and the time between marks, and the rotational speed of the transfer roller 5K is converted into the speed of the transfer material transport belt 7.
This conversion work may be performed when the power of the image forming apparatus is turned on. However, by performing the conversion work before printing, it is possible to perform highly accurate settings corresponding to environmental changes.
[0028]
As described above, in the present embodiment, since the speed detection sensor 39 is fixed to the opposite side of the transfer roller 5K with respect to the conveying belt 7 in the contact (pressing) direction via the shaft 5a, the rotation diameter of the transfer roller 5K is reduced. Even if it changes, the speed corresponding to the speed of the conveyor belt 7 can be detected.
For example, in the initial setting in which the contact distance L1 from the rotation shaft center position of the transfer roller 5K to the conveyor belt 7 and the distance L2 from the rotation shaft center position of the transfer roller 5K to the detection position of the speed detection sensor 39 are the same distance, When the distance L1 decreases due to the pressure deformation of the roller 5K, the rotation speed of the transfer roller 5K decreases, but the distance L2 increases by the shortened distance L1, so that the rotation speed detected by the speed detection sensor 39 increases. .
Therefore, even when the transfer roller 5K is deformed and rotated, the speed detection deviation of the transport belt 7 does not occur.
[0029]
A second embodiment will be described with reference to FIGS. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and the description of the already-described configuration and function will be omitted unless necessary, and only the main part will be described.
The speed detection device 46 according to the present embodiment includes a disk 41 fixed to the shaft 5a of the transfer roller 5K with a pin 42, and a light transmission type speed detection sensor 45 fixed to the bearing 40 of the shaft 5a.
The bearing 40 has a bracket 43 integrally extending downward along the frame 25, and a speed detection sensor 45 is fixed to the bracket 43. The passing time between the slits of the disk 41 is detected, and the rotational speed of the transfer roller 5K is calculated by the speed calculating means.
[0030]
Since the speed detection sensor 45 is integrally fixed to the bearing 40 inserted into the shaft 5a of the transfer roller 5K, the distance between the axis of the transfer roller 5K and the speed detection sensor 45 even if the position of the transfer roller 5K changes. Lx always maintains a constant distance.
The calculated rotation speed of the transfer roller 5K is replaced with the speed of the conveyor belt 7 calculated from the distance between the marks written on the conveyor belt 7 for one round or at equal intervals and the time between the marks. Is controlled to a predetermined speed (a motor for driving the drive roller 17).
[0031]
In each of the above embodiments, the photosensitive drum 1K and the transfer roller 5K are described. Similarly, the transport speed (moving speed) of the transport belt 7 for the paper 8 is calculated from the rotational speeds detected by the transfer roller 5Y and all the transfer rollers. And averaged.
In this case, the detection accuracy of the transport speed of the sheet 8 (moving speed of the transport belt 7) is improved, and the speed of the transport belt 7 can be controlled with high accuracy. A quality image can be formed.
In addition, the rotation speed of the photosensitive drums 1Y, 1M, 1C, and 1K is set to the transport speed of the transport belt 7 so that the transport speed of the transport belt 7 and the peripheral speeds of the photosensitive drums 1Y, 1M, 1C, and 1K become the same. By controlling the driving together, a high-quality image without color shift can be formed.
[0032]
Further, in each of the above embodiments, the tandem-type image forming apparatus in which the toner images are sequentially transferred while the sheet 8 is conveyed by the conveyance belt 7 is described. After that, a similar belt position shift suppressing function can be obtained in a tandem type image forming apparatus of a system in which batch transfer is performed on a transfer material by a secondary transfer unit.
[0033]
【The invention's effect】
According to the first aspect of the present invention, the driving roller, the endless belt wrapped around the plurality of supporting members including the driving roller, and the rotational force transmitted to the driving roller to rotate the belt. A drive source, a plurality of image forming units disposed on the front side of the belt along the moving direction of the belt, and a plurality of image forming units provided on the inner surface side of the belt facing each image forming unit and formed by the image forming units. An image forming apparatus having a transfer unit for transferring the transferred image, and forming one image by sequentially superimposing the images formed by the image forming units while rotating the belt. The speed of the belt is measured directly at the position, and the movement speed of the belt is controlled based on the measurement result. Out can be, can be aligned with high accuracy.
[0034]
According to the second aspect of the present invention, in the image forming apparatus according to the first aspect, a belt speed detecting unit that detects a speed of the belt at a transfer position by the transfer unit, and the information based on the detection information by the belt speed detecting unit. And the control means for controlling the driving source, the speed can be detected with high accuracy without being affected by the change in the belt thickness, and the positioning can be performed with high accuracy.
[0035]
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the transfer unit is a transfer roller, and the belt speed detection unit is provided to detect a rotation speed of the transfer roller. Therefore, a high-precision distance sensor or control device for measuring a change in the thickness of the belt is not required, and an image forming apparatus which is inexpensive and has excellent maintainability can be provided.
[0036]
According to the fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the belt speed detecting means is provided so as to be able to detect the rotational speed of the transfer roller close to the drive roller. In addition, since there is no influence from the elongation or bending of the belt, highly accurate speed control can be performed.
[0037]
According to a fifth aspect of the present invention, in the image forming apparatus according to the third aspect, the rotation speed of the driving source by the control unit is based on a moving speed (surface speed) of the belt and a rotation speed of the transfer roller. By setting the motor drive speed of the drive roller with the belt surface speed, there is no influence of speed fluctuations due to the contact radius of the transfer roller with the belt, and the accuracy corresponding to the actual belt speed is set. High speed control.
[0038]
According to the sixth aspect of the present invention, in the image forming apparatus according to the third aspect, the rotation speed of the transfer roller is set periodically according to the moving speed of the belt. It is possible to cope with the change of the transfer roller due to the change, and it is possible to always control the belt speed stably.
[0039]
According to a seventh aspect of the present invention, in the image forming apparatus according to the third aspect, the belt speed detecting means is provided on a side opposite to the transfer roller in a contact direction of the transfer roller with respect to the belt via a rotation shaft of the transfer roller. With this configuration, the belt speed can always be kept constant even if the transfer roller axis changes due to the pressure contact deformation of the transfer roller.
[0040]
According to an eighth aspect of the present invention, in the image forming apparatus according to the third aspect, the belt speed detecting means is configured to move integrally with the rotation shaft of the transfer roller. However, since the position of the speed detecting means and the transfer roller shaft always maintain a constant distance, the speed can be detected with high accuracy without a detected position deviation from the rotation center position.
[0041]
According to the ninth aspect of the present invention, in the image forming apparatus according to the first aspect, the rotation speed of the driving source is configured to be changeable according to the moving speed of the belt. Even if the rotation speed of the roller changes, the rotation speed of the drive source can be adjusted according to the speed of the belt, so that the belt speed can be maintained at a predetermined speed.
[0042]
According to a tenth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the image forming means has a photosensitive drum, and the rotation speed of the photosensitive drum is the detection information of the belt speed detecting means. , The relative speed between the photosensitive drum and the belt can be kept constant, and the transfer position can be adjusted with high accuracy. In particular, in the tandem type, if the transfer positions of the respective photoconductors do not match on the belt, color misregistration occurs. Therefore, a color image without color misregistration can be obtained by adjusting the rotation speed of the photoconductor drum to the belt speed. .
[0043]
According to an eleventh aspect of the present invention, in the image forming apparatus according to the second or third aspect, a plurality of the belt speed detecting means are provided, and the average speed obtained by each detection information of the belt speed detecting means is provided. Since the rotation speed of the drive source is set based on the above, it is possible to reduce the speed detection error due to the slippage of the transfer roller, and to perform the speed control with high accuracy.
[Brief description of the drawings]
FIG. 1 is a schematic front view of a color printer as an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic side view showing a drive mechanism of a photosensitive drum and a transfer roller in a black image forming unit.
FIG. 3 is a diagram illustrating a support configuration at one end side of a transfer roller and a mounting state of a speed detection device.
FIG. 4 is a schematic front view of the configuration shown in FIG.
FIG. 5 is a perspective view of a bearing of the transfer roller.
FIG. 6 is a diagram illustrating a support configuration on one end side of a transfer roller and an attached state of a speed detecting device according to a second embodiment.
7 is a schematic front view of the configuration shown in FIG.
[Explanation of symbols]
1Y, 1M, 1C, 1K Photoconductor drums 5Y, 5M, 5C, 5K Transfer roller 5a as transfer means Rotary shaft 7 of transfer roller Belt 17 Drive rollers 35, 46 Speed detecting device as belt speed detecting means

Claims (11)

A drive roller, an endless belt stretched between a plurality of support members including the drive roller, a drive source that transmits a rotational force to the drive roller to rotate the belt, and a surface side of the belt. A plurality of image forming means arranged along a moving direction of the belt; and a transfer means provided on an inner surface side of the belt opposite to each image forming means for transferring an image formed by the image forming means. And an image forming apparatus that forms one image by sequentially superimposing images formed by the respective image forming means while rotating the belt,
An image forming apparatus, wherein the speed of the belt is directly measured at a transfer position by the transfer means, and the moving speed of the belt is controlled based on the measurement result. The image forming apparatus according to claim 1,
An image comprising: belt speed detecting means for detecting a speed of the belt at a transfer position by the transfer means; and control means for controlling the drive source based on detection information from the belt speed detecting means. Forming equipment. The image forming apparatus according to claim 2,
An image forming apparatus, wherein the transfer unit is a transfer roller, and the belt speed detection unit is provided to detect a rotation speed of the transfer roller. The image forming apparatus according to claim 3,
An image forming apparatus, comprising: the belt speed detection means for detecting a rotation speed of the transfer roller close to the drive roller. The image forming apparatus according to claim 3,
The rotation speed of the drive source by the control means is set based on the movement speed of the belt and the rotation speed of the transfer roller. The image forming apparatus according to claim 3,
An image forming apparatus, wherein a rotation speed of the transfer roller is set periodically in accordance with a movement speed of the belt. The image forming apparatus according to claim 3,
The image forming apparatus according to claim 1, wherein the belt speed detecting means is provided on an opposite side of the transfer roller in a contact direction of the transfer roller with respect to the belt via a rotation shaft of the transfer roller. The image forming apparatus according to claim 3,
An image forming apparatus, wherein the belt speed detecting means moves integrally with a rotation shaft of the transfer roller. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein a rotation speed of the driving source can be changed according to a moving speed of the belt. The image forming apparatus according to claim 2, wherein
An image forming apparatus, wherein the image forming means has a photosensitive drum, and a rotation speed of the photosensitive drum is set based on detection information of the belt speed detecting means. The image forming apparatus according to claim 2, wherein
An image forming apparatus comprising: a plurality of the belt speed detecting means; and a rotation speed of the driving source is set based on an average speed obtained from each detection information of the belt speed detecting means.

Images