JP2000132047A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-quality image while prolonging the life of an intermediate transfer belt even in the case of using the intermediate transfer belt having a joint. SOLUTION: Four detection holes 16A and 16B are formed at equal intervals on the intermediate transfer belt 5, and further the hole 16a at a position where an image area does not come to the part of the joint S has different size from the other holes 16B. The holes 16A and 16B are discriminated by an optical sensor 17, and whether to use all the holes 16a and 16B and whether to use only the hole 16A having the different size are changed over in accordance with a printing condition. Since all the detection holes are used on a condition that the joint S does not cause image defect, all the periphery of the belt is used. Therefore, the life of the belt is prolonged, while image forming timing is controlled so as to avoid the image defect on a condition that the joint causes the image defect, whereby the high-quality image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type image forming apparatus such as a copying machine or a laser beam printer.

[0002]

2. Description of the Related Art FIG. 10 shows an example of a conventional color image forming apparatus. Hereinafter, description will be given with reference to the drawings.

A photosensitive drum 1 serving as an image carrier is driven in a direction indicated by an arrow by driving means (not shown), and is uniformly charged by a primary charger 2. Next, the exposure device 3 irradiates the photosensitive drum 1 with laser light L according to a yellow image pattern, and a latent image is formed on the photosensitive drum 1. Furthermore,
When the photosensitive drum 1 advances in the direction of the arrow, among the developing devices 4a, 4b, 4c, and 4d supported by the rotary support 11,
The image is visualized by the developing device 4a containing the yellow toner.

An intermediate transfer belt 5 serving as an intermediate transfer member rotates in the direction of the arrow at substantially the same speed as the photosensitive drum 1, and transfers a toner image formed and carried on the photosensitive drum 1 to a primary transfer roller 8.
The primary transfer is performed on the outer peripheral surface of the intermediate transfer belt 5 by the primary transfer bias applied to the intermediate transfer belt 5. By performing the above steps for yellow, magenta, cyan, and black, a plurality of color toner images are formed on the intermediate transfer belt 5.

[0005] Next, the transfer material P is picked up from the transfer material cassette 12 by the pickup roller 13 at a predetermined timing.
Paper is fed through guide members 7a and 7b. At the same time, a secondary transfer bias is applied to the secondary transfer roller 8b, and the toner image is transferred from the intermediate transfer belt 5 to the transfer material P.

Further, the transfer material P is conveyed to the fixing device 6 by the conveyance belt 14 to be fused and fixed to obtain a color image, and is discharged to an external tray 20 via a discharge roller 19.

The transfer residual toner on the intermediate transfer belt 5 is charged by an intermediate transfer cleaning roller 15 and is reversely transferred onto the photosensitive drum 1 at the next primary transfer. On the other hand, the transfer residual toner on the photosensitive drum 1 is cleaned by a cleaning device 9 of a known blade means.

The intermediate transfer belt 5 is provided with a detection mark for obtaining a signal synchronized with the rotation of the intermediate transfer belt 5 in order to transfer the toner images of the respective colors in a superimposed manner. The signal of the detection mark is detected by an optical sensor, and an image of the next color is formed according to the signal.

Conventionally, as shown in FIG. 11, a detection hole 16 is formed at the end of the intermediate transfer belt 5 as a detection mark. An optical sensor 17 is provided at a position where the hole 16 can be detected. FIG. 12 shows the output of the sensor 17 when the detection hole 16 is detected. here,
A state without transmission (portion other than a hole) is defined as Lo, and a state with transmission (portion of a hole) is defined as Hi.

The CPU 18 controls image formation by synchronizing with the intermediate transfer belt 5 based on the Lo and Hi signals.

Further, four detection marks 16 are provided at equal intervals on one circumference of the intermediate transfer belt, and by using each of them sequentially, an image can be formed on the entire circumference of the intermediate transfer belt 5.

[0012]

However, if an intermediate transfer belt having a seam is used, the seam may appear as an image defect depending on the type of paper or environment. This is due to the difference in electrical resistance between the seam part and the other part and the presence of mechanical irregularities,
This is due to the change in transferability.

In this case, the image forming timing may be controlled so that the image area does not come to the seam portion. However, if the same image forming timing is always used, the same portion on the intermediate transfer belt is always used. Therefore, the life of the intermediate transfer belt is shortened.

The same applies to a color image forming apparatus in which an image formed on an image carrier is sequentially transferred from a first color to a plurality of colors onto a transfer material carried on a transfer material carrier. Can be said.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of obtaining a high-quality image while achieving a long life of the belt body even when a belt body having a seam is used.

[0016]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
In an image forming apparatus for transferring a toner image formed on an image carrier onto an intermediate transfer member and transferring the toner image on the intermediate transfer member onto a transfer material, a plurality of image forming devices provided on the intermediate transfer member are provided. An image forming apparatus comprising: a detection mark; and detection means for detecting the detection mark, wherein at least one of the plurality of detection marks has a characteristic different from the other.

According to another aspect of the present invention, an image forming apparatus for transferring an image formed on an image carrier to a transfer material carried on a transfer material carrier is provided on the transfer material carrier. A plurality of detection marks, and detection means for detecting the detection marks, wherein at least one of the plurality of detection marks provided on the transfer material carrier has characteristics different from others. An image forming apparatus is provided.

According to another aspect of the present invention, an image is formed on an intermediate transfer member by sequentially primary transferring a plurality of colors from a first color to a toner image formed on an image carrier. A color image forming apparatus that performs a secondary transfer from the intermediate transfer member onto a transfer material at one time, comprising: a plurality of detection marks provided on the intermediate transfer member; and detection means for detecting the detection marks. A color image forming apparatus is provided, wherein at least one of the plurality of detection marks has a characteristic different from the others.

Further, according to another aspect of the present invention, there is provided a color image in which an image formed on an image carrier is sequentially transferred from a first color to a plurality of colors on a transfer material carried on a transfer material carrier. The forming apparatus includes a plurality of detection marks provided on the transfer material carrier, and detection means for detecting the detection marks, and at least one of the plurality of detection marks provided on the transfer material carrier is provided. A color image forming apparatus characterized in that one has different characteristics from the other.

In the above invention, the different characteristics are:
Different sizes, different transmittances, different reflectances, or different detection mark intervals.

Further, it is preferable to have a control means for controlling the leading end of the image by detecting the detection mark, and to change the detection mark to be used according to the type of the transfer material. According to another aspect, it is preferable to have a control unit for controlling the leading end of the image by detecting the detection mark, and to change the detection mark to be used according to the environment. According to still another aspect, it is preferable that a control unit for controlling the leading edge of the image by detecting the detection mark is provided, and the detection mark to be used is changed according to the printing speed. or,
According to another aspect, it is preferable that the apparatus further includes control means for controlling the leading edge of the image by detecting the detection mark, and the detection mark to be used is changed between the mono color mode and the full color mode.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention will be described as being embodied in the color image forming apparatus shown in FIG. Therefore, description of the overall configuration and functions of the color image forming apparatus will be omitted, and only the features of the present invention will be described.

The feature of this embodiment is that the position of the seam of the intermediate transfer belt is changed by changing the size of one of the plurality of detection marks provided on the intermediate transfer belt to another. It is characterized by switching between using all detection marks and using only specific detection marks so as to avoid seams according to print conditions.

More specifically, when an intermediate transfer belt having a seam is used, an image defect may occur at the seam. The inventors of the present invention have examined the occurrence of image defects. As a result, plain paper does not occur in a low-temperature and low-humidity environment but does occur in a high-temperature and high-humidity environment. Further, even in a situation that does not occur with plain paper, it occurs with OHT. Further, image defects also occur in a mode in which the transfer / fixing speed is reduced to improve the fixability and printing is performed. or,
It has been found that even in a situation where an image defect occurs in the full color mode, it does not occur in the mono color mode.

Here, in order to prevent an image defect occurring at the seam portion, only one detection mark for specifying the seam is provided on the intermediate transfer belt, and the image formation timing is determined only by this one detection mark. What is necessary is to control.
However, in this case, although the image defect does not occur in every situation as described above, the image is always formed only on a specific portion of the intermediate transfer belt, so that the intermediate transfer belt deteriorates quickly, Life will be shortened.

Therefore, in the present embodiment, among the plurality of detection marks provided on the intermediate transfer belt, the size of the detection mark at a position where the image area does not come to the seam is provided so as to be different from the size of the other marks. The detection mark can be distinguished from other detection marks, and printing conditions (for example,
Environment, paper type, print speed, mono color or full color)
Switching between using all the detection marks or using only the detection marks located at positions where the image area does not come to the joint.

Thus, under the condition that the seam does not cause an image defect, all the detection marks are used, so that the entire circumference of the belt can be used, and the service life of the belt can be extended. Since the image forming timing is controlled so that the seam does not enter the image area, an image defect can be prevented.

In this embodiment, an intermediate transfer belt 5 having a surface layer made of urethane rubber and a fluororesin such as PTFE dispersed on a base layer of EPDM rubber having a circumference of 400 mm and a thickness of 1 mm was used.

More specifically, in this embodiment, as shown in FIG. 1, the size of the detection hole 16A at a position where the joint S does not enter the image area and the size of the other detection holes 16B are changed. Therefore, during the pre-print operation, the intermediate transfer belt 5
Is rotated at a cycle of 4000 msec, the optical sensor 17 detects each intermediate transfer belt 5 as shown in FIG.
A signal as shown in FIG. In other words, the Hi signal at time t _A is detected at the detection hole 16A, and the H signal at time t _B is detected at the detection hole 16B.
An i signal is output, and a Lo signal is output in a portion having no hole.

At this time, the CPU 18 changes the signal from Lo to Hi.
, And then the time from Hi to Lo is measured, and as a result, the detection holes 16 from the times t _A and t _B are measured.
A, 16B identifies type A or type B. Then, the CPU 18 detects the types A and B of the detection holes 16A and 16B.
It is determined whether to start the image formation or to suspend the image formation up to the next detection hole, based on the paper type information from the controller (not shown) and the like.

That is, when the paper type is plain paper, image formation starts irrespective of whether the detection hole is type A or type B. However, when the paper type is OHT, the image formation starts when the detection hole is type B. Image formation is suspended, and image formation is started only when the detection hole is of type A.

As described above, in this embodiment, the entire circumference of the belt can be used because all the detection holes are used under conditions where the seam does not cause an image defect, and the life of the belt can be prolonged. Under conditions that cause image failure, image formation timing is controlled so that the seam does not enter the image area, so that image failure can be prevented.

In this embodiment, the detection holes to be used are changed according to the type of paper. However, if the type of the detection holes to be used is changed according to environmental information, printing speed, and whether the color is mono-color or full-color. Good.

In this embodiment, a hole is used as a detection mark and a transmission type optical sensor is used as a sensor.
A reflection plate may be used as the detection mark, and a reflection type optical sensor may be used as the sensor.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention will be described as being embodied in the color image forming apparatus shown in FIG. Therefore, description of the overall configuration and functions of the color image forming apparatus will be omitted, and only the features of the present invention will be described.

In the present embodiment, the position of the seam of the intermediate transfer belt is specified by changing the transmittance of one of the plurality of detection marks provided on the intermediate transfer belt to the other, and according to the printing conditions. Switching between using all detection marks or using only specific detection marks so as to avoid seams.

In this embodiment, as shown in FIG.
Detection hole 16A at a position where seam S does not enter the image area
Is covered with a film with low transmittance, and the other detection holes 1
6B and the transmittance is changed. Therefore, the print before operation when rotating the intermediate transfer belt in a cycle of 4000Msec, each optical sensor 17 intermediate transfer belt 5, the signal I _A, as shown in FIG. 4, and outputs the I _B. At this time, the CPU 18 measures the intensity of the Hi portion of the signal, and from the result, the type A of the detection holes 16A and 16B,
Identify B. Then, the CPU 18 detects the detection holes 16A, 1
Based on the types A and B of 6B and the paper type information from the controller or the like, it is determined whether to start image formation or to suspend image formation until the next detection hole.

That is, when the paper type is plain paper, image formation starts regardless of the type of the detection hole, A or B, but when the paper type is OHT, the image is formed when the detection hole is the B type. The formation is suspended, and the image formation is started only when the detection hole is of type A.

As described above, also in the present embodiment, under the condition that the seam does not cause an image defect, all the detection holes are used, so that the entire circumference of the belt can be used, the life of the belt can be extended, and the seam can be improved. Under conditions that cause image failure, image formation timing is controlled so that the seam does not enter the image area, so that image failure can be prevented.

In this embodiment, the detection holes to be used are changed according to the type of paper. However, if the type of the detection holes to be used is changed according to environmental information, printing speed, mono color or full color, etc. Even better.

In this embodiment, a hole is used as a detection mark and a transmission type optical sensor is used as a sensor.
A reflection plate may be used as the detection mark, and a reflection type optical sensor may be used as the sensor.

Embodiment 3 Next, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention will be described as being embodied in the color image forming apparatus shown in FIG. Therefore, description of the overall configuration and functions of the color image forming apparatus will be omitted, and only the features of the present invention will be described.

In the present embodiment, the position of the seam of the intermediate transfer belt is specified by changing the interval between one of the plurality of detection marks provided on the intermediate transfer belt to the other, so that the printing conditions can be determined. The position of the joint of the intermediate transfer belt is measured by changing all the detection marks according to others, and all the detection marks are used according to the printing conditions, or only specific detection marks are used to avoid the seam It is characterized in that switching is performed.

In this embodiment, as shown in FIG. 5, the distance between the detection hole 16A and the detection hole 16B at the position where the seam S does not enter the image area is changed. Therefore, during the pre-print operation, the intermediate transfer belt is set to 4000 ms.
When rotated at a cycle of ec, the optical sensor 17 outputs signals T _A and T _B as shown in FIG. 6 for each of the intermediate transfer belts 5.

At this time, the CPU 18 measures the time from when the signal changes from Hi to Lo to the next change from Lo to Hi. As a result, the detection hole 1 changes from T _A and T _B to the detection hole 1.
Identify types A and B of 6A and 16B. And CP
U determines whether to start image formation or suspend image formation until the next detection hole based on the types A and B of the detection holes 16A and 16B and paper type information from a controller or the like.

That is, when the paper type is plain paper, image formation starts regardless of whether the detection hole is of type A or B. When the paper type is OHT, image formation is started when the detection hole is of type B. Suspended and image formation starts only when the detection hole is of type A.

As described above, also in the present embodiment, the entire circumference of the belt can be used because all the detection holes are used under conditions where the seam does not cause an image defect, and the life of the belt can be prolonged. Under conditions that cause image failure, image formation timing is controlled so that the seam does not enter the image area, so that image failure can be prevented.

In this embodiment, the type of the detection hole used is changed according to the type of paper.
It is even better to change the type of detection hole used depending on the printing speed and whether the printing is mono-color or full-color.

In this embodiment, the case where three or more detection holes are arranged at unequal intervals has been described with reference to FIG. 5, but the same applies to the case where only two detection holes are provided. Needless to say, the seam can be identified with one hole.

In this embodiment, a hole is used as a detection mark and a transmission type optical sensor is used as a sensor.
A reflection plate may be used as the detection mark, and a reflection type optical sensor may be used as the sensor.

Embodiment 4 Next, a fourth embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 7, the color image forming apparatus of this embodiment has a plurality of image forming units M, C, Y, and Bk.
And a transport belt 50 as a transfer material carrier is provided so as to cross each image forming unit.

In each of the image forming units M, C, Y, and Bk, cylindrical photosensitive members (photosensitive drums) 60M, 60C, 60Y, and 60Bk as image carriers are rotatably supported in the direction of arrow a. ing. Around each photosensitive drum, a primary charger 22M arranged at a predetermined interval,
22C, 22Y, 22Bk, primary chargers 22M, 22
C, 22Y, and 22Bk, the photosensitive drums 60M, 60
The laser exposure devices 23M, 23C, 23Y, and 23Bk, which expose the downstream side in the rotation direction of C, 60Y, and 60Bk, contain magenta, yellow, cyan, and black toners. Developing devices 24M, 24C, 24Y, 24Bk, which are arranged further downstream and in contact with the photosensitive drum, and
Cleaners 26M, 26C, 26Y, 26 for cleaning residual toner on the photosensitive drums 60M, 60C, 60Y, 60Bk
Bk is provided.

The transport belt 50 is stretched by a driving roller 51 and a tension roller 52, and the photosensitive belt 60M,
60C, 60Y, and 60Bk are disposed so as to face each other and are driven in the direction of arrow b.

Further, the transfer chargers 54M, 54C, 54Y, 54Y, 54C, and 54Y are placed at respective transfer positions so as to sandwich the conveyor belt 50 with respect to each photosensitive drum in order from the upstream side in the moving direction of the conveyor belt 50.
54Bk are arranged.

Further, the driving roller 5 is sandwiched by the transport belt 50.
1, a belt cleaner 33 for cleaning the transport belt 50 and an attraction roller 53 for attracting the transfer material P to the transport belt 50 are provided.

The operation of the image forming apparatus configured as described above will be described by taking the image forming unit M as an example.

The photosensitive drum 60M has a photoconductive layer on the surface of a conductive substrate such as aluminum, and rotates in the direction of arrow a. Then, after the surface is uniformly negatively charged by the primary charger 22M, exposure is performed by the laser exposure device 23M, and an electrostatic latent image is formed. The developing device 24M performs development using negatively charged toner, and forms a toner image corresponding to the electrostatic latent image on the surface of the photosensitive drum 60M.

On the other hand, the transfer material P is transported to the transport belt 50 by the paper feed roller 56 at a predetermined timing, and is electrostatically attracted to the transport belt 50 by the attraction roller 53. Then, the toner image formed on the surface of the photosensitive drum 60M is
The image is transferred onto the transfer material P electrostatically attracted to the transport belt 50 by the transfer charger 54M.

On the other hand, the residual toner adhering to the surface of the photosensitive drum 60M after the transfer is removed by the cleaner 26M, and is used for the next image formation.

The above operation is performed at a predetermined timing,
The operation is performed in each image forming unit, and the toner image formed on each photosensitive drum is sequentially transferred to the transfer material P. In the case of the full-color mode, the transfer is performed in the order of M, C, Y, and Bk. In the case of the single-color mode or the two- or three-color mode, similarly, the toner of the required color is transferred in the order described above. Is transcribed multiple times.

The transfer material P on which the toner image has been transferred in this manner
Is supplied to a fixing device 40, and is fixed by receiving heat and pressure to obtain a full-color image.

The surface of the conveyor belt 50 from which the transfer material P has been separated is cleaned by the belt cleaner 33.

Here, it is necessary to transfer the toner images of the respective colors onto the conveying belt 50 in a superimposed manner on the recording material P adsorbed thereon, and as shown in FIG. 8, a signal synchronized with the rotation of the conveying belt 50 is provided. Detection marks 36A and 36B are provided for obtaining the following. The signals of the detection marks 36A and 36B are detected by the optical sensor 37, and the next color image is formed according to the signals. Further, four detection marks 36A and 36B are provided at equal intervals with respect to one circumference of the transport belt, and by using each of them sequentially, an image can be formed on the entire circumference of the belt.

In this embodiment, the size of one of the plurality of detection marks 36A and 36B provided on the conveyor belt 50 is changed to the size of the other detection mark 36B so that the seam S of the conveyor belt 50 is changed. It is characterized in that the position is specified, and whether to use all the detection marks or only specific detection marks so as to avoid the seam S is switched according to the printing conditions.

More specifically, if a transport belt having a seam is used, an image defect may occur at the seam depending on the printing conditions, as described in the above embodiment.

Therefore, in the present embodiment, a plurality of detection marks 36A provided on the transport belt 50 as the transfer material carrier are provided.
36B, the size of the detection mark 36A at a position where the image area does not come to the seam S portion is changed to another detection mark 36B.
The detection mark 36A and the other detection marks 36B can be distinguished from each other, and all the detection marks can be detected according to the printing conditions (for example, environment, paper type, printing speed, mono color or full color). Switching between using a mark or using only a detection mark at a position where an image area does not come to a joint portion.

As a result, similarly to the above embodiment, under the condition that the seam does not cause an image defect, all the detection marks are used, so that the entire circumference of the belt can be used, and the life of the belt can be extended, and the image of the seam can be extended. Under conditions that cause a defect, the image forming timing is controlled so that the joint does not enter the image area, so that the image defect can be prevented.

In this embodiment, a polyimide resin having a circumference of 400 mm and a thickness of 100 μm is used as the transport belt 50, and a detection hole 36 A is formed at the end of the transport belt 50 as a detection mark as shown in FIG. , 36B are provided. An optical sensor 37 is provided at a position where the detection holes 36A and 36B can be detected.

FIG. 9 shows the output of the sensor 37 when the detection holes 36A and 36B are detected. Here, the state without transmission (portion other than the hole) is Lo, and the state with transmission (portion) is Hi. In the present embodiment, the size of the detection hole 36A at a position where the seam S does not enter the image area and the size of the other detection holes 36B are changed.

Therefore, during the pre-printing operation, the transport belt 5
When 0 is rotated at a cycle of 400 msec, the sensor 37 outputs a signal as shown in FIG. At this time, the CPU 38 measures the time during which the signal changes from Lo to Hi, and then changes from Hi to Lo.
6B identifies type A or B.

Then, the CPU 38 detects the detection holes 36A, 36A.
Based on the types A and B of B and the paper type information from the controller or the like, it is determined whether to start image formation or suspend image formation until the next detection hole. That is, when the paper type is plain paper, image formation starts regardless of whether the detection hole is type A or B. However, when the paper type is OHT, image formation is suspended when the detection hole is type B. When the detection hole is of type B, the image formation is suspended, and the image formation is started only when the detection hole is of type A.

In the present embodiment, the detection holes to be used are changed according to the type of paper. However, the type of the detection holes to be used may be further changed according to environmental information, printing speed, and whether the color is mono-color or full-color. .

In this embodiment, a hole is used as a detection mark and a transmission type optical sensor is used as a sensor.
A reflection plate may be used as the detection mark, and a reflection type optical sensor may be used as the sensor.

Further, in this embodiment, the size of the detection mark for specifying the joint portion is set to be different from the size of the detection mark. However, the transmittance, the reflectance, or the interval between the detection marks may be changed. Similar effects can be obtained.

[0077]

As is apparent from the above description, according to the image forming apparatus of the present invention, the image forming apparatus has a plurality of detection marks provided on the intermediate transfer member, and detection means for detecting the detection marks. By having at least one of the detection marks having different characteristics from the other, or having a plurality of detection marks provided on the transfer material carrier and a detection means for detecting the detection marks, Since at least one of the plurality of detection marks provided has a characteristic different from that of the other, a long life of the belt body with a seam, that is, the intermediate transfer body or the transfer material carrier can be obtained even when the belt body is used. High quality images can be obtained while achieving.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a main part of a first embodiment according to the present invention.

FIG. 2 is a waveform diagram showing an output signal of the optical sensor according to the first embodiment.

FIG. 3 is an explanatory view showing a main part of a second embodiment according to the present invention.

FIG. 4 is a waveform diagram showing an output signal of an optical sensor according to a second embodiment.

FIG. 5 is an explanatory view showing a main part of a third embodiment according to the present invention.

FIG. 6 is a waveform diagram showing an output signal of an optical sensor according to a third embodiment.

FIG. 7 is a schematic configuration diagram illustrating a color image forming apparatus according to a fourth embodiment of the present invention.

FIG. 8 is an explanatory view showing a main part of a fourth embodiment according to the present invention.

FIG. 9 is a waveform chart showing an output signal of an optical sensor according to a fourth embodiment.

FIG. 10 is a schematic configuration diagram illustrating an example of a conventional color image forming apparatus to which the first to third embodiments are applied.

FIG. 11 is an explanatory view showing a conventional detection mark and an optical sensor.

FIG. 12 is a waveform diagram showing an output signal of the optical sensor of FIG.

[Explanation of symbols]

1, 60M, 60C, 60Y, 60Bk Photosensitive drum (image carrier) 5 Intermediate transfer belt (intermediate transfer member) 16A, 16B Detection hole (detection mark) 17, 37 Optical sensor (detection means) 36A, 36B Detection hole ( Detection mark) 50 Conveyor belt (transfer material carrier) P Transfer material

Continued on the front page F-term (reference) 2C058 AB07 AC08 AC17 AE02 AE09 AF27 GB04 GB05 GB11 GB29 GB47 2H027 DA11 DA14 DA38 DE02 EB04 EC06 EC20 ED02 ED06 EE02 EE07 EF09 FA28 2H030 AA01 AB02 AD05 AD07 AD12 BB02 BB24 BB02 BB02 BB02 BB02 BB02 BB02 BB16 BB16 BB16 BB16 BB16 BB16 BB24 BB16 BB16 BB16 BB16 BB24 BB16 BB16 BB16 BB16 BB16 BB16 BB16 BB16 BB16 BB16 BB16 BB16 BA09 BA18 9A001 BB06 HH34 KK42 LL09

Claims (20)

[Claims] 1. A toner image formed on an image carrier,
An image forming apparatus for transferring an image on an intermediate transfer member and transferring a toner image on the intermediate transfer member onto a transfer material, comprising: a plurality of detection marks provided on the intermediate transfer member; and detection means for detecting the detection marks And wherein at least one of the plurality of detection marks has a characteristic different from the others. 2. An image forming apparatus for transferring an image formed on an image carrier to a transfer material carried on a transfer material carrier, comprising: a plurality of detection marks provided on the transfer material carrier; An image forming apparatus comprising: a detection unit configured to detect the detection mark, wherein at least one of the plurality of detection marks provided on the transfer material carrier has a characteristic different from the others. 3. The image forming apparatus according to claim 1, wherein the different characteristic is a difference in size. 4. The image forming apparatus according to claim 1, wherein the different characteristic is a difference in transmittance. 5. The image forming apparatus according to claim 1, wherein the different characteristic is that the reflectance is different. 6. The image forming apparatus according to claim 1, wherein the distance between the detection marks differs from the characteristic. 7. The image forming apparatus according to claim 1, further comprising control means for controlling the leading edge of the image by detecting the detection mark, and changing a detection mark to be used in accordance with a type of the transfer material. . 8. The image forming apparatus according to claim 1, further comprising control means for controlling the leading edge of the image by detecting the detection mark, and changing a detection mark to be used according to an environment. 9. The image forming apparatus according to claim 1, further comprising control means for controlling the leading edge of the image by detecting the detection mark, and changing a detection mark to be used according to a printing speed. 10. The image forming apparatus according to claim 1, further comprising control means for controlling the leading edge of the image by detecting the detection mark, and changing a detection mark to be used in a mono color mode or a full color mode. . 11. An image is formed on an intermediate transfer member by primary-transferring a toner image formed on an image bearing member from a first color to a plurality of colors sequentially, and is transferred from the intermediate transfer member onto a transfer material. A plurality of detection marks provided on the intermediate transfer body, and detection means for detecting the detection marks, wherein at least one of the plurality of detection marks is another A color image forming apparatus having characteristics different from those of the above. 12. A color image forming apparatus for sequentially transferring an image formed on an image carrier to a transfer material carried on a transfer material carrier from a first color to a plurality of colors. It has a plurality of detection marks provided, and a detection means for detecting the detection marks, wherein at least one of the plurality of detection marks provided on the transfer material carrier has characteristics different from others. Color image forming apparatus. 13. The color image forming apparatus according to claim 11, wherein the different characteristic is a difference in size. 14. The color image forming apparatus according to claim 11, wherein the different characteristic is a difference in transmittance. 15. The color image forming apparatus according to claim 11, wherein the different characteristic is that the reflectance is different. 16. The color image forming apparatus according to claim 11, wherein the distance between the detection marks differs from the characteristic. 17. The image forming apparatus according to claim 11, further comprising control means for controlling the leading edge of the image by detecting the detection mark, and changing a detection mark to be used in accordance with the type of the transfer material.
Any of the color image forming apparatuses. 18. The color image forming apparatus according to claim 11, further comprising control means for controlling the leading edge of the image by detecting the detection mark, and changing a detection mark to be used in accordance with an environment. 19. The apparatus according to claim 11, further comprising control means for controlling the leading edge of the image by detecting the detection mark, and changing a detection mark to be used according to a printing speed.
Any of the color image forming apparatuses. 20. A color image forming apparatus according to claim 11, further comprising control means for controlling the leading edge of the image by detecting the detection mark, and changing a detection mark to be used in a mono color mode or a full color mode. apparatus.