JPH1115290A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately judge the deterioration of an intermediate transfer belt and to highly precisely detect the end of its life by detecting a mechanical characteristic such as a change in the length of its periphery or a change in its tensile force, which is the factor of the deterioration of the intermediate transfer belt. SOLUTION: A spring 70 is suspended from a tension roller 64, and a position sensor 11 of an optical system, magnetic system, or the like is provided at one end of it in its axial direction. The position sensor 11 is provided with a flag which moves synchronizing with the movement of the tension roller 64, and it measures the movement of the flag optically. To the position sensor 11 a judging circuit 21 is connected for comparing an amount of measured change with a reference value, and to the judging circuit 21 a display unit 22 is connected. In the case the length of the periphery of the intermediate transfer belt 61 changes due to the slack in the belt, the position of the tension roller 64 changes and therefore the amount of change is measured by the position sensor 11. Further, the value of the measurement is compared with the specific value by the judging circuit 21. When the amount of change is above the reference value, it judges that the end of life has reached, and causes the display unit 22 to display the information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic image forming apparatus, and more particularly, to an image forming apparatus using an intermediate transfer belt for collectively transferring toner images.

[0002]

2. Description of the Related Art A conventional image forming apparatus has a structure as shown in FIG.

In FIG. 1, a drum type electrophotographic photosensitive member (hereinafter, referred to as a "photosensitive drum") 1 as a first image carrier is shown.
Is an organic photoreceptor (OP
C), a photoconductor such as A-Si, CdS, or Se is applied.

The photosensitive drum 1 is driven in a direction indicated by an arrow R1 by driving means (not shown). Around the photosensitive drum 1, a roller charger 2 for uniformly charging the photosensitive drum 1 to a predetermined potential, a light source 31 such as a laser, a polygon mirror 32 for performing scanning, and the like are provided. An exposure device 3 for forming an image on the photosensitive drum 1; and developing devices 4a, 4b, 4c, which contain yellow, magenta, cyan, black, and other toners for visualizing the electrostatic latent image formed on the photosensitive drum 1. A developing device 4 in which a support 4d is supported by a support 5, an intermediate transfer member 6 as a second image carrier on which a toner image formed on the photosensitive drum 1 is visualized, and an intermediate transfer member 6 to the photosensitive drum 1 after transfer
And a cleaning device 7 for removing the toner remaining in the cleaning device.

[0005] The intermediate transfer member 6 includes an intermediate transfer belt 61 formed of ethylene propylene rubber (EPDM), nitrile rubber (NBR), urethane, silicone rubber, or the like, which is driven by a driving roller 62, a driven roller 63, and a spring (not shown). The photosensitive drum 1 is stretched on a tension roller 64 that is pressurized, and the intermediate transfer belt 61 is interposed therebetween.
Transfer Roller 65 and Intermediate Transfer Belt 6 Contacting
The secondary transfer roller 66 is in contact with the driven roller 63 with 1 interposed therebetween. A primary transfer bias is applied to the primary transfer roller 65 from a high-voltage power supply, and the toner image on the photosensitive drum 1 is transferred onto the intermediate transfer belt 61.

The primary transfer roller 65 and the secondary transfer roller 66 have a structure in which a conductive sponge layer is provided on a shaft.
A bias is applied from a high-voltage power supply (not shown) to transfer the toner image on the photosensitive drum 1 onto the intermediate transfer belt 61 or transfer the toner image on the intermediate transfer belt 61 onto transfer paper P as a recording material. Or In this case, the intermediate transfer belt 61 is driven in the illustrated arrow R6 direction by rotating the drive roller 62 by a motor (not shown). Further, since it is necessary to superimpose and transfer the toner images of the respective colors on the intermediate transfer belt 61, a timing flag 68 for obtaining a signal synchronized with the rotation of the intermediate transfer belt 61 is used.
Is attached, a signal of the timing flag 68 is detected by the timing sensor 69, and an image of the next color is formed in accordance with the signal.

A fixing device 8 for fixing the toner image transferred from the intermediate transfer member 6 to the transfer paper P is disposed downstream of the transfer paper P in the illustrated transport direction Kp. The intermediate transfer belt 61 has a cleaning device 67 such as a fur brush or web for removing toner remaining on the intermediate transfer belt 61.
Are provided so as to be able to contact and separate from the intermediate transfer belt 61.

The photosensitive drum 1 is driven in a direction indicated by an arrow R1 by driving means, and is uniformly charged to a predetermined potential by the rotation of the roller charger 2 in a direction indicated by an arrow R2. Next, the photosensitive drum 1 is scanned with the exposure light L according to the yellow image information from the exposure device 3 to form an electrostatic latent image. Next, the support 5 is rotated to make the developing device 4a.
Is selected to face the photosensitive drum 1 to visualize the electrostatic latent image, and then the yellow toner image is transferred to the intermediate transfer belt 61 by the primary transfer roller 65.

Similarly, the above steps are repeated to obtain magenta,
The cyan and black toner images are multiplex-transferred onto the intermediate transfer belt 61 to form a color toner image on the intermediate transfer belt 61. When the color toner image is formed on the intermediate transfer belt 61, when the transfer paper P conveyed in synchronization with the movement of the intermediate transfer belt 61 reaches the transfer portion between the intermediate transfer belt 61 and the secondary transfer roller 66 Then, the color toner image is collectively transferred to the transfer paper P.

The color toner image transferred to the transfer paper P is heated and pressurized by the fixing device 8 so as to be fused and fixed to the transfer paper P. Further, the transfer residual toner on the photosensitive drum 1 is removed by the cleaning device 7, and the transfer residual toner on the intermediate transfer belt 61 is also removed by the cleaning device 67.

In the above-described color image forming apparatus, image quality is deteriorated due to deterioration of the intermediate transfer belt 61 due to durability. Conventionally, as a means for detecting deterioration of the intermediate transfer belt 61 and notifying the user of the life, a method of multiplying the number of printed sheets using, for example, a complicated mechanical mechanism or a large-capacity nonvolatile memory circuit has been widely used.

Therefore, when the number of printed sheets reaches the predetermined number, the user can operate the intermediate transfer belt 61 regardless of the state thereof.
The life of the intermediate transfer belt 61 or the unit including the intermediate transfer belt 61 has been replaced.

[0013]

However, the use state of the intermediate transfer belt 61, such as the use environment, the use frequency,
The number of prints and the intermediate transfer belt 61 depend on the material of the transfer material.
When the number of printed sheets reaches a predetermined number even when the intermediate transfer belt 61 is in a state where it can be used satisfactorily, it is necessary to replace it. There is a problem that deterioration occurs.

[0014] Further, those having a complicated mechanical mechanism for accumulating the number of printed sheets and a configuration having a large-capacity nonvolatile memory circuit,
There is a problem that the cost increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides an image forming apparatus capable of accurately determining the deterioration state of an intermediate transfer belt and detecting the life thereof with high accuracy. The purpose is to do.

[0016]

In order to achieve the above object, an image forming apparatus according to the present invention forms an electrostatic latent image by irradiating a charged image carrier with scanning light. After the toner image obtained by visualizing the electrostatic latent image is primarily transferred to an intermediate transfer belt that rotates in synchronization with the image carrier, the toner image is transferred from the intermediate transfer belt to a recording material. And a detecting means for detecting a state of the intermediate transfer belt, and a determining means for determining a deterioration state based on a signal from the detecting means. It is characterized by.

According to a second aspect of the present invention, the electrostatic latent image is formed by irradiating the charged image carrier with scanning light, and the electrostatic latent image is visualized to form a toner image. After the primary transfer to an intermediate transfer belt that rotates in synchronization with the image carrier, the toner image is collectively transferred from the intermediate transfer belt to a recording material by two times.
A detecting means for detecting a change in the circumference of the intermediate transfer belt, and comparing a deterioration state of the intermediate transfer belt with a reference value based on a signal from the detecting means. Determining means for determining.

According to the third aspect of the present invention, the detecting means includes a tension roller that constantly maintains the intermediate transfer belt in an adjusted state, and a position sensor that detects a position of the tension roller.

According to a fourth aspect of the present invention, an electrostatic latent image is formed by irradiating the charged image carrier with scanning light, and the electrostatic latent image is visualized to obtain a toner image. After the primary transfer to an intermediate transfer belt that rotates in synchronization with the image carrier, the toner image is collectively transferred from the intermediate transfer belt to a recording material by two times.
Detecting the change in the tension of the intermediate transfer belt, and comparing the deterioration state of the intermediate transfer belt with a reference value based on a signal from the detection unit. And determining means for performing the determination.

According to the fifth aspect of the present invention, the detecting means has a tension roller for always maintaining the intermediate transfer belt in an adjusted state, and a pressure sensor for measuring a pressure applied to the tension roller.

According to a sixth aspect of the present invention, the electrostatic latent image is formed by irradiating the charged image carrier with scanning light, and the electrostatic latent image is visualized to obtain a toner image. After the primary transfer to an intermediate transfer belt that rotates in synchronization with the image carrier, the toner image is collectively transferred from the intermediate transfer belt to a recording material by two times.
Measuring means for measuring the rotation cycle of the intermediate transfer belt, and determining whether the deterioration state of the intermediate transfer belt is compared with a reference value based on the rotation cycle measured by the measurement means. Means.

According to the seventh aspect of the present invention, the measuring means has a timing flag attached to the intermediate transfer belt and a timing sensor for detecting the movement of the timing flag.

According to the present invention, the electrostatic latent image is formed by irradiating a scanning light to the charged image carrier, and the electrostatic latent image is visualized to obtain a toner image. After the primary transfer to an intermediate transfer belt that rotates in synchronization with the image carrier, the toner image is collectively transferred from the intermediate transfer belt to a recording material by two times.
Current transfer means for detecting current flowing when the image carrier or the intermediate transfer belt is charged, and whether the current detected by the current detection circuit is within a predetermined level. A transfer bias control unit for determining whether or not the transfer bias is applied and controlling a transfer bias; and a determination unit for determining a deterioration state of the intermediate transfer belt based on a determination result of the transfer bias control unit.

[Operation] Based on the above configuration, according to the present invention, the intermediate transfer is performed by detecting mechanical characteristics such as a change in circumference or a change in tension, which is a cause of deterioration of the intermediate transfer belt, by detecting means. Determine the state of belt degradation.

Further, according to another aspect of the present invention, the electric bias characteristic, which is a factor of the deterioration of the intermediate transfer belt, is detected by the transfer bias control means to determine the deterioration state of the intermediate transfer belt.

Further, according to another aspect of the present invention, the deterioration state of the intermediate transfer belt is determined by detecting the rotation cycle of the intermediate transfer belt by using the detecting means for detecting the print timing of the intermediate transfer belt.

[0027]

Embodiments of the present invention will be described below in detail with reference to the drawings. <First Embodiment> FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to a first embodiment of the present invention, and FIG. 2 is a perspective view showing an essential part of FIG. 1 and 2, the same or equivalent components as those in FIG. 7 are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 1, the intermediate transfer belt 61 is driven by a driving roller 62 such that the respective axes of a driving roller 62, a driven roller 63, and a tension roller 64 are movable so that the belt tension is constant. , Driven roller 6
3 and the tension roller 64. A tension roller 64, which is a movable roller, is suspended with a spring 70 of 5 kg on one side. Further, a known position sensor 11 such as an optical type or a magnetic type as a detecting means for detecting the position of the tension roller 64 is used. 2, it is provided at one end in the axial direction.

FIG. 2 shows the position sensor 11 of the present embodiment.
As shown in (1), a flag 111 is provided in conjunction with the movement of the tension roller 64, and the movement of the flag 111 is optically measured. The position sensor 11 is connected to a determination circuit 21 as a determination unit for comparing the measured change amount with a reference value, and the determination circuit 21 is connected to a display 22 for displaying a comparison result. .

A detailed examination of the state of deterioration of the intermediate transfer belt 61 made of a rubber belt due to durability revealed the following.

The deterioration of the intermediate transfer belt 61 due to the durability is caused by a change in the circumference due to the relaxation. Although the relaxation is mainly caused by the durability, the change with time in the stationary state depends on the number of printed sheets and the life of the intermediate transfer belt 61. Has been found to cause a discrepancy between For this reason, the service limit of the intermediate transfer belt 61, that is, the service life, can be defined as follows.

Problems caused by the loosening of the intermediate transfer belt 61 differ depending on how the intermediate transfer belt 61 is stretched and the type of material used, and the like. Phenomena are different due to differences.

First, for example, the tension roller 64 can be moved, and a constant load can be applied to the intermediate transfer belt 61 by a spring 70, and the center can be moved, and the tension of the belt is always kept constant. In such a case, when the change in the circumferential length due to the relaxation becomes about 5% or more, the printing accuracy becomes unusable.

Therefore, when the circumferential length changes due to the relaxation of the intermediate transfer belt 61, the position of the tension roller 64 changes. The change amount is measured by the position sensor 11, and the measured value is determined by the determination circuit 21. To the value of. As a result, when the amount of change exceeds the reference value, it is determined that the life has expired, and the information may be displayed on the display 22.

In this embodiment, a rubber belt having a circumference of 440 mm is used as the intermediate transfer belt 61. <Second Embodiment> Next, a second embodiment will be described with reference to FIG.

In the above-described embodiment, the use mode in which the spring 70 can move between the axes for applying a constant weight to the intermediate transfer belt 61 and keep the tension of the belt constant has been described. A usage mode in which the total distance between the drive roller 62, the driven roller 63, and the tension roller 64 is fixed at a value greater than the circumference of the roller 61, and tension is generated in the intermediate transfer belt 61 by using the elasticity of rubber. Even if used, the durability of the intermediate transfer belt 61 can be accurately determined.

FIG. 3 is a schematic configuration diagram showing an image forming apparatus according to a second embodiment of the present invention. In FIG. 3, the same or equivalent components as those in FIG. Description is omitted. In the figure, the intermediate transfer belt 61
Is fixed between the respective axes of the drive roller 62, the driven roller 63, and the tension roller 64, and is stretched around the drive roller 62, the driven roller 63, and the tension roller 64 by using elasticity of rubber. Further, the bearing of the tension roller 64 as a support shaft is provided with a pressure sensor 12 as a detecting means for measuring a pressure applied to the tension roller 64. As the pressure sensor 12, a known piezo sensor is used.

Therefore, when the intermediate transfer belt 61 is relaxed and the tension changes, the pressure sensor 12 detects a change in the pressure applied to the tension roller 64, and the amount of the change is detected by the determination circuit 21. Is greater than the reference value, it is determined that the life is reached, and the life may be displayed on the display 22.

That is, when the tension of the intermediate transfer belt 61 is reduced to about 70% or less of the initial value due to relaxation, slip between the intermediate transfer belt 61 and the driving roller 62 cannot be ignored, and uniform image formation cannot be performed. . Therefore, the pressure fluctuation of the tension roller 64 is detected by the pressure sensor 12, the change amount is determined by the determination circuit 21, and when the detection result exceeds the reference value, the life is determined and the life is displayed on the display 22. .

In this embodiment, a change in the circumference of the intermediate transfer belt 61 can be detected by measuring the rotation period of the intermediate transfer belt 61. That is, when the tension of the intermediate transfer belt 61 is used constant, the driving roller 6
No slippage occurs between the intermediate transfer belt 61 and the intermediate transfer belt 61, and the peripheral speed of the intermediate transfer belt 61 is constant. Therefore, when the circumference of the intermediate transfer belt 61 changes due to relaxation, the rotation period of the intermediate transfer belt 61 is detected by the timing flag 68 and a signal synchronized with the rotation is measured by the timing sensor 69. The change of the circumference of 61 can be measured.

Further, a driving roller 62 and a driven roller 63
When the intermediate transfer belt 61 is used while fixing the respective axes of the intermediate transfer belt 61 and the tension roller 64, the tension of the intermediate transfer belt 61 is relaxed moderately. Until slippage cannot be ignored, the peripheral speed of the intermediate transfer belt 61 gradually changes without changing the peripheral length of the intermediate transfer belt 61. That is, the rotation cycle of the intermediate transfer belt 61 changes. Therefore, if the rotation cycle of the intermediate transfer belt 61 is measured,
The life can be detected irrespective of the usage of the intermediate transfer belt 61.

Therefore, if a use mode in which the belt can be moved between the shafts and the belt tension is kept constant is used, a change in the circumferential length can be detected. It will be good. <Third Embodiment> Next, a third embodiment will be described with reference to FIG.

FIG. 4 is a schematic configuration diagram showing an image forming apparatus according to a third embodiment of the present invention. In FIG. 4, the same or equivalent components as in FIG. Is omitted. In the figure, the signal from the timing sensor 69 is sent not only to the image forming circuit 24 but also to the timer circuit 23 as a measuring means.
Then, the timing sensor 69 sets the timing flag 6
When the timer circuit 23 measures the time from the detection of the time 8 to the next detection, the rotation cycle of the intermediate transfer belt 61 is always measured, and the determination circuit 21 determines the measured value and the reference value. The life can be detected by comparing.

By using this mode of use, the rotation cycle of the intermediate transfer belt 61 can be measured without newly providing a sensor, and the same effect as that of the above-described embodiment can be obtained by a cheaper method. There are advantages. <Fourth Embodiment> Next, a fourth embodiment will be described with reference to FIG.

FIG. 5 is a schematic configuration diagram showing an image forming apparatus according to a fourth embodiment of the present invention.
The same or equivalent components as those described above are denoted by the same reference numerals, and redundant description will be omitted.

In the second embodiment, the intermediate transfer belt 6
Although the case where the elastic rubber belt is used is described as 1, when the flexible sheet is used as the intermediate transfer belt 61, the amount of relaxation is smaller than that of the rubber belt. It was difficult to detect the deterioration of the belt 61. Further, the mechanical deterioration of the belt is not so slow as that of the rubber belt, and the elongation of the belt immediately leads to breakage. Therefore, when a flexible sheet is used for the intermediate transfer belt 61, if the life of the flexible sheet is not detected early, there is a problem that the broken belt is wound around rollers and the apparatus is damaged.

Further, the thickness of the flexible sheet used for the intermediate transfer belt 61 must be a thin film of 100 to 200 μm. There is also a problem peculiar to the flexible sheet that the image of the portion that has been deteriorated is deteriorated.

As a result of examining the state of deterioration of the intermediate transfer belt 61 using the flexible sheet having such a problem,
The following became clear.

Intermediate transfer belt 6 using a flexible sheet
The rupture of No. 1 occurs from a portion of the flexible sheet where the sheet thickness of the sheet having low mechanical strength is small or a point where a scratch or a pinhole exists. Further, the electrical resistance value of such a flexible sheet at a point of low mechanical strength is different from the electrical resistance value of a normal portion. For this reason, it has been found that by measuring the electrical resistance value between the point where the mechanical strength is weak and the normal part, the two can be distinguished.

Therefore, if the resistance value of the intermediate transfer belt 61 can be measured in the movable image forming apparatus main body, the deterioration state of the flexible sheet can be grasped, and the deterioration of the intermediate transfer belt 61 can be determined before the sheet breaks. It is possible to notify.

Therefore, the fourth embodiment is configured as shown in FIG.

In the figure, a primary transfer bias power supply 25 for supplying a transfer voltage to a primary transfer roller 65 includes a primary transfer current detection circuit 26 as current detection means for appropriately controlling a current at the time of transfer. Grounded. This one
A signal from the next transfer current detecting circuit 26 is sent to an image forming circuit 24 as transfer bias control means for controlling the operation in the image forming apparatus main body, and the image forming circuit 24
The primary transfer bias of the secondary transfer roller 65 is controlled so as to be appropriate.

In this embodiment, the resistance value of the intermediate transfer belt 61 is measured using the image forming circuit 24. That is, first, the surface of the photosensitive drum 1, which is in contact with the opposite electrode of the intermediate transfer belt 61, is charged to a predetermined potential, and a primary transfer bias having an approximate voltage is applied while rotating the intermediate transfer belt 61. FIG. 6 shows the difference between the normal current change profile and the abnormal current change profile obtained at this time. FIG.
In the above, scratches and pinholes on the flexible sheet appear as spike-like signals, and a change in the thickness of the flexible sheet appears as a gradual change on the photosensitive drum 1. Therefore, when the resistance value of the intermediate transfer belt 61 is measured, the image forming circuit 24 compares whether or not the current signal exceeds the level indicated by the dotted line in the figure, and the comparison result is displayed via the determination circuit 21 on the display unit. By displaying the information 22, the deterioration state of the intermediate transfer belt 61 can be grasped.

In the above embodiment, the method in which the primary transfer bias is controlled at a constant voltage has been described. However, the method is not limited to this as long as the sheet resistance can be measured. The voltage may be monitored.

In the above-described embodiment, the counter electrode of the intermediate transfer belt 61 is described as the photosensitive drum 1.
The secondary transfer roller 66 may be used.

Further, in the above-described embodiment, the resistance measurement of the sheet may be performed at any time as long as it is not during the printing sequence. Is effective.

[0057]

As is apparent from the above description, according to the present invention, mechanical characteristics such as a change in circumference or a change in tension, which is a cause of deterioration of the intermediate transfer belt, are detected by the detection means. Therefore, the deterioration state of the intermediate transfer belt can be accurately determined, and the life can be detected with high accuracy.

According to another aspect of the present invention, the electric resistance characteristic, which is a cause of deterioration of the intermediate transfer belt, is detected by the transfer bias control means, so that the deterioration state of the intermediate transfer belt can be accurately determined. The life can be detected with high accuracy.

Further, according to another aspect of the present invention, since the rotation period of the intermediate transfer belt is detected by using the detection means for detecting the print timing of the intermediate transfer belt, a complicated mechanical mechanism and a large-capacity nonvolatile memory are used. The memory circuit can be omitted, and cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a perspective view extracting and showing main parts of FIG.

FIG. 3 is a schematic configuration diagram illustrating an image forming apparatus according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an image forming apparatus according to a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram illustrating an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a characteristic diagram illustrating the principle of reversing the deterioration of the intermediate transfer belt according to the fourth embodiment.

FIG. 7 is a schematic configuration diagram illustrating an example of a conventional image forming apparatus.

[Explanation of symbols]

 Reference Signs List 1 image carrier (photosensitive drum) 6 intermediate transfer belt 11 detecting means (position sensor) 12 detecting means (pressure sensor) 21 determining means (determining circuit) 23 measuring means (timer circuit) 24 transfer bias controlling means (image forming circuit) 26 Current Detector (Primary Transfer Current Detector) 61 Intermediate Transfer Belt 64 Detector (Tension Roller) 68 Detector (Timing Flag) 69 Detector (Timing Sensor)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuya Kobayashi Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo

Claims (8)

[Claims] 1. A charged image carrier is irradiated with scanning light to form an electrostatic latent image, and a toner image obtained by visualizing the electrostatic latent image is synchronized with the image carrier. In the image forming apparatus, after the primary transfer to the intermediate transfer belt that rotates around, the toner image is secondarily transferred collectively from the intermediate transfer belt to the recording material, the state of the intermediate transfer belt is detected. An image forming apparatus, comprising: means for determining a deterioration state based on a signal from the detecting means. 2. A charged image carrier is irradiated with scanning light to form an electrostatic latent image, and a toner image obtained by visualizing the electrostatic latent image is synchronized with the image carrier. An image forming apparatus configured to transfer the toner image from the intermediate transfer belt to a recording material in a batch after the primary transfer to the intermediate transfer belt that rotates around the intermediate transfer belt. An image forming apparatus, comprising: a detecting unit for detecting; and a determining unit for determining a state of deterioration of the intermediate transfer belt by comparing with a reference value based on a signal from the detecting unit. 3. The apparatus according to claim 2, wherein the detection unit includes a tension roller that constantly maintains the intermediate transfer belt in a stretched state, and a position sensor that detects a position of the tension roller. Image forming device. 4. A charged image carrier is irradiated with scanning light to form an electrostatic latent image, and a toner image obtained by visualizing the electrostatic latent image is synchronized with the image carrier. An image forming apparatus configured to transfer the toner image from the intermediate transfer belt to the recording material in a batch after the primary transfer to the intermediate transfer belt that rotates around, and to detect a change in the tension of the intermediate transfer belt. An image forming apparatus, comprising: a detecting unit that performs a determination based on a signal from the detecting unit to compare a deterioration state of the intermediate transfer belt with a reference value. 5. The apparatus according to claim 4, wherein the detection unit includes a tension roller that constantly maintains the intermediate transfer belt in a stretched state, and a pressure sensor that measures a pressure applied to the tension roller. Image forming apparatus. 6. A charged image carrier is irradiated with scanning light to form an electrostatic latent image, and a toner image obtained by visualizing the electrostatic latent image is synchronized with the image carrier. In the image forming apparatus configured to transfer the toner image from the intermediate transfer belt to the recording material in a batch after the primary transfer to the intermediate transfer belt that rotates around, the rotation cycle of the intermediate transfer belt is measured. An image forming apparatus comprising: a measuring unit; and a determining unit that compares a deterioration state of the intermediate transfer belt with a reference value based on a rotation cycle measured by the measuring unit. 7. The image forming apparatus according to claim 6, wherein the measuring unit has a timing flag attached to the intermediate transfer belt, and a timing sensor for detecting a movement of the timing flag. 8. A charged image carrier is irradiated with scanning light to form an electrostatic latent image, and a toner image obtained by visualizing the electrostatic latent image is synchronized with the image carrier. An image forming apparatus configured to transfer the toner image from the intermediate transfer belt to a recording material in a batch after the primary transfer to an intermediate transfer belt that rotates around the image carrier. Current detection means for detecting a current flowing when charging; transfer bias control means for controlling whether or not the current detected by the current detection circuit is within a predetermined level to control a transfer bias; Determining means for determining a deterioration state of the intermediate transfer belt based on a determination result of the image forming apparatus.