JPH0427977A - Sensitivity compensating device for photosensitive body - Google Patents

Abstract

PURPOSE:To prolong the life of a photosensitive body by providing a storage means which integrates and stores the rotating time of the photosensitive body and an exposure voltage control means which increases the input voltage of the exposing lamp for the photosensitive body in accordance with the increase of the rotating time which is stored in the storage means. CONSTITUTION:When an image forming device is actuated and the photosensitive body is rotated, a CPU 28 fetches the on-time of a driving circuit 32 for rotating the photosensitive body through an I/O 29 and integrates and stores the on-time in the memory 26a of a RAM 26. The CPU 28 reads out data from a ROM 27 and the RAM 26 and outputs exposure voltage in accordance with the stored rotating time to a control part 22 through the I/O 29. Then, the relation of the rotating time and the appropriate exposure voltage of the exposing lamp 21 is set, and the exposure voltage is increased according to the increase of the rotating time which is integrated and stored based on the set relation. Thus, the time till the exchange of the photosensitive body 30 is put off.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field This invention forms an image by irradiating and exposing a photoreceptor comprising a charge generation layer and a charge transport layer to light reflected from a light source. The present invention relates to a sensitivity compensation device for a photoreceptor in an image forming apparatus.

(b) Conventional technology In an image forming apparatus such as a copying machine, a charged cylindrical photoreceptor is rotated and exposed to slit light reflected from an original to form a latent image, and a latent image is formed in a developing device. Generally, images are formed by attaching toner to the image and transferring it to paper.

Since there were many problems with the above-mentioned image forming apparatuses, organic photoreceptors (○PC) are now widely used, especially in the charge generation layer! Most are of the functionally separated type with laminated cargo transport layers.

(C) Problems to be Solved by the Invention However, when the above-mentioned functionally separated type is attached to an image forming apparatus using a photoreceptor, the photoreceptor is charged using, for example, a scorotron mirror, and the image forming apparatus is formed. When repeating the process, as the number of images formed increases, C.

The thickness of the charge transport layer decreases. The film thickness of the transport layer C affects the photoreceptor's poor performance, and as the film thickness δ decreases, the real-world performance decreases. Therefore, if the image becomes dark or problems such as background fog occur and the film thickness falls below a certain level, the photoreceptor must be replaced, and the lifespan of the photoreceptor is shortened. be.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sensitivity compensation device for a photoreceptor that can extend the life of the photoreceptor.

(d) Means for Solving Problem R In the photoconductor sensitivity compensation device of the first invention according to this application, in an image forming apparatus that exposes the photoconductor with imaging light such as reflected light of an original, rotation of the photoconductor is provided. a storage means for accumulating and storing time;
The present invention is characterized by further comprising an exposure voltage control means for increasing the input voltage of the exposure lamp of the photoreceptor in accordance with an increase in the rotation time stored in the storage means.

The sensitivity compensation device for a photoconductor according to the second invention of this application includes a cleaning device that exposes the photoconductor to image forming light such as light reflected from an original and has a cleaning blade that presses against the photoconductor only when forming an image. An image forming apparatus comprising: a storage means for accumulating and storing the time period in which the cleaning blade is in pressure contact with the photoreceptor; and an input voltage to an exposure lamp of the photoreceptor is increased in accordance with an increase in the time period in which the cleaning blade is in pressure contact with the photoreceptor. An exposure voltage control means is provided.

+e) Effect In the photoreceptor sensitivity compensation device of the first invention related to this application, in an image forming apparatus to which this sensitivity compensation device is applied,
A storage means is provided to accumulate and store the rotation time of the photoreceptor,
The exposure voltage control means increases the input voltage (exposure voltage) of the exposure lamp in accordance with the increase in the stored rotation time.

As mentioned above, the film thickness of the photoreceptor is almost inversely proportional to the number of images formed, but in reality there is a warm-up time, etc., so in order to obtain an accurate relationship, the rotation time of the photoreceptor and the film thickness are Measure and explore relationships. This result is expressed in a graph as shown in FIG. Further, the relationship between the number of images formed and the standard exposure voltage as the number increases is as shown in the graph of FIG. Based on these relationships, determine the exposure voltage that should be increased as the rotation time of the photoreceptor increases, set the relationship of exposure voltage according to the increase in rotation time, for example as shown in Figure 1, and apply this to the image In FIG. 1, the exposure voltage is set to 0 every 5 hours, which is stored in the CPU of the forming device.
．． The upper line that increases by 4V is exposure scale 1, which will be described later.
When , the lower line is exposure scale 5, and all the scales between ] and 5 change in the same way as the upper and lower lines, and the rotation time of the photoreceptor is accumulated and memorized. The exposure voltage is increased according to the stored rotation time according to the relationship shown in FIG. As a result, the apparent sensitivity of the photoreceptor can be maintained for a longer period of time, so that the time for replacing the photoreceptor can be extended.

In the photoreceptor sensitivity compensation device of the second invention according to this application, in an image forming apparatus using this sensitivity compensation device,
Means for detecting and storing the time during which the cleaning blade is in contact with the photoreceptor is provided, and the exposure voltage control means increases the exposure voltage in accordance with an increase in the stored time during which the cleaning blade is in contact with the photoreceptor.

That is, in order to know whether the film thickness of the photoreceptor has decreased, the time during which the cleaning blade is in pressure contact with the photoreceptor is detected. The pressure contact time of the cleaning blade includes blade release time such as warm-up, but it is normal based on empirical research]
Pressure contact was applied for approximately 5 hours during image formation using the cross-section. The relationship between the pressure contact time of the cleaning blade and the film thickness of the photoreceptor is as shown in Figure 5, and from this Figure 5 and the above-mentioned Figure 4, the exposure voltage to be increased as the cleaning blade pressure contact time increases is determined. The relationship between the exposure voltage and the increase in the pressure contact time of the cleaning blade is set, for example, as shown in FIG. 2, and this is stored in the CPU of the image forming apparatus. In Figure 2, the first
The voltage is varied in the same way as shown in the figure, and the pressure contact time of the cleaning blade is accumulated and stored, and according to the relationship shown in FIG. 2, the exposure voltage is increased to the value suitable for opening when the cleaning blade is pressed. In this way, the apparent sensitivity of the photoreceptor can be maintained for a longer period of time, and the time for replacement of the photoreceptor can be extended.

(f) Embodiment FIG. 7 is a schematic diagram of the main parts of an image forming apparatus to which a photoreceptor sensitivity compensating device, which is an embodiment of the first invention according to this application, is applied.

A document table 10 is provided on the upper surface of the main body 1, and a document is placed on the document table 10. An optical device 2 including an exposure lamp 21, a mirror, a lens, etc. is arranged below the document table 10. The light reflected from the original travels through the optical path formed by the mirror of the optical device 2, and irradiates the photoreceptor 30 at an exposure point P. The photoreceptor 30 of this embodiment is of a functionally separated type (two layers), and its surface A photoresist film 30a is formed on and rotates in the direction of arrow A. Around it, downstream from the exposure point P, there is a developing device 4, a transfer charger 34, a peeling charger 35, a cleaning device 36, a static elimination lamp 37, and a charging charger 38.
is installed. The cleaning device 36 is provided with a cleaning blade 36a that can come into contact with the photoreceptor. A paper feed section 7 including a cassette for storing paper 71, a paper feed roller, a timing roller, etc. is disposed at the lower right side of the main body 1, and the paper is conveyed to the transfer section in the direction of arrow B.

A fixing device 5 is provided on the left side of the photoreceptor 30, and a paper discharge section 6 is provided on the left side thereof.

The operation of the image forming apparatus configured as above will be explained. First, the exposure lamp 21 or the like of the optical device 2 scans the document on the document table 10, and the reflected light of the document strikes the photoreceptor 30 at an exposure point P.
Irradiate at As a result, a static latent image is formed on the surface of the photoreceptor. Toner is attached to the formed latent image in the developing device 4 to form a toner image, and the toner image is transferred by the transfer charger 34 onto the paper 71 fed from the paper feed section 7 at the same timing. Ru. After the development and transfer, the photoreceptor 30 has residual toner removed by a cleaning device 36, and the charge is removed by a charge removal lamp 37. On the other hand, the sheet 71 on which the image has been transferred is peeled off from the photoreceptor 30 by the peeling charger 35 and conveyed, subjected to heat treatment by the fixing device 5 to fix the image, and then discharged to the sheet discharge section 6. By repeating image formation, the thickness of the photoreceptor film 30a of the photoreceptor 30 decreases, and the sensitivity of the photoreceptor decreases. The rotation time is integrated and stored, and the exposure voltage of the light source 21 is increased according to the rotation time.

FIG. 6 is a block diagram of the same anger compensation device application section of the control section of the same plane image forming apparatus.

The CPU 28 that controls the entire image forming apparatus has l102.
9 to the operation panel 25 and the control section 2 of the exposure lamp 21.
2. Drive circuit 32 for the motor 31, control circuit 3 for the solenoid 36b that turns on and off the cleaning blade 36a
3 is connected. The photoreceptor is rotationally driven by this motor 31, and the operation panel 25 has a print switch 2.
5a and other keys are arranged, and 25b is an exposure scale, which specifies the input voltage (1 to 5) to the exposure lamp 21 according to the density of the original, and when the cleaning blade comes into contact with the photoreceptor.・Cancellation is performed by turning on and off the solenoid 36a.
6 is connected to the ROM 27, a program is written in advance, and the RAM 2C is assigned to a working area such as the memory 26a1 timer.
6a is a non-volatile memory having a backup ifS.

When the image forming apparatus operates and the photoreceptor 30 rotates, the drive circuit 320 that rotates the photoreceptor 30 has an on-time of I/'0.
29, the CPU 28 integrates the on-time and stores it in the memory 25a of the RAM 26. C
PU2B reads data from ROM27 and FAM26, and stores the exposure voltage according to the stored large rotation time.
It is output to the control unit 22 via l1029. The relationship between rotation time and exposure voltage is as shown in FIG. 3 above. As a result, the exposure scale described later is set to normal (3 in this example) (Z
The sensitivity of the photoreceptor can be maintained appropriately. However, if the exposure voltage is changed according to Fig. 1 during continuous image forming operation,
Since the image quality changes before and after that, changes in the exposure voltage are prohibited during continuous operations on the same document, and the exposure voltage is changed from the image forming operation on the next document.

In addition, depending on the density of the original, the operator can set the exposure scale 25.
When one of b 1 to 5 is selected, the signal is l1
The signal of the exposure voltage of the selected scale is input to the CPU 2B via 1029 and output to the control unit 22 via 11029. This exposure scale 25b is shifted in accordance with the density of the original, and also when the number of sheets on which images are formed increases and the time to replace the photoreceptor approaches and the sensitivity decreases, the scale is shifted to a brighter side as the number of sheets increases. By doing so,
It can be used to maintain sensitivity to some extent. However, if the sensitivity decreases to a level greater than the negative value, there will no longer be an appropriate exposure scale for various originals, and it will be necessary to replace the exposure scale. Note that FIG. 8 is a graph showing the relationship between the exposure scale and the exposure voltage. The closer the scale is to 1, the more appropriate the voltage is for originals with dark background, and the closer to 5, the appropriate voltage is for originals with thin lines and light texture. It takes about 5 hours to form 10,000 images due to the warm amplifier at the beginning of use, preliminary rotation at the start and end of copying, etc. Then, by increasing the input voltage of the exposure lamp as the rotation time of the photoreceptor increases using the photoreceptor sensitivity compensator, which is an embodiment of the present invention, the exposure scale (described later) is maintained at the normal (3). It is possible to form images up to 1000m, and after that, by using the conventional method of compensating for the decrease in sensitivity, that is, by shifting the exposure scale towards the brighter side.
It was possible to form images on up to 10,000 sheets without replacing the photoreceptor.

Furthermore, the detection and integration of the rotation time of the photoconductor is not limited to the means of this embodiment; for example, a detection protrusion is provided on the rotation axis of the photoconductor, and the number of rotations is detected by a photosensor, integrated, and stored. Schematic configuration of main parts of an image forming apparatus to which a photoreceptor sensitivity compensating device is applied, which is an embodiment of the second invention according to the second application, in which the exposure voltage may be controlled according to the rotation speed of the photoreceptor. is the same as FIG. 9, and the explanation of the configuration and operation will be omitted.

In the photoreceptor sensitivity compensator of this embodiment, the input voltage of the exposure lamp is increased by integrating the time during which the cleaning blade 36a is in pressure contact with the photoreceptor.

The block diagram of a part of the control section of the same sensitivity compensation device application part of the image forming apparatus is the same as that shown in FIG. 6 Only the different parts will be explained below.

The ON time of the control circuit 33 that controls the pressing/release of the cleaning blade is taken in by the CPU 2B via 11029 and stored in the memory 26a of the RAM 26. CPU
2o reads data from the RO:vi 27 and RAM 26, and outputs the exposure voltage corresponding to the stored pressure contact time to the control circuit 33 via the I/O 29.

The relationship between the pressure contact time and the exposure voltage is as shown in FIG. 2 above. As a result, the sensitivity of the photoreceptor can be maintained appropriately with the exposure scale (described later) being normal (3 in this embodiment). However, during continuous image forming operations, changing the exposure voltage is prohibited, similar to the first invention.

In this example, the image forming speed for A4 size is 40 sheets/min (A3 and B4 size are considered as 2 sheets), as in the above example, and there is a warm amplifier and a blade release time at the end of copying. Normally, pressure is applied for 5 hours to form 10,000 images. Then, by increasing the exposure voltage of the light source as the pressure contact time of the cleaning blade increases using the photoreceptor sensitivity compensator, which is an embodiment of the present invention, the exposure scale is kept at the normal (3) until about 100,000 sheets are printed. The structure of the image forming apparatus was able to form images, and by shifting the conventional exposure scale to the brighter side, it was possible to form images up to 160,000 sheets without replacing the photoreceptor.
The rate of increase in the input voltage of the exposure lamp is not limited to the above two embodiments.

(g) Effect of the invention As described above, the photoreceptor sensitivity compensating devices of the first and second inventions of this application can reduce the sensitivity of the photoreceptor by adjusting the film thickness and rotation time of the photoreceptor. Search for the relationship between the photoconductor film thickness and the cleaning blade's pressure contact time, and set the relationship between the rotation time and the appropriate exposure lamp input voltage (exposure voltage), and the relationship between the pressure contact time and the appropriate exposure voltage. Based on this, the exposure voltage is increased in accordance with the increase in rotation time and pressure contact time which are accumulated and stored. Therefore, it was possible to compensate for the decrease in sensitivity due to a decrease in the thickness of the photosensitive film by increasing the exposure voltage, maintain the apparent sensitivity at an appropriate level, and extend the time until the photoreceptor was replaced.

[Brief explanation of the drawing]

FIG. 1 shows the rotation time of a photoreceptor in an image forming apparatus, and
3 is a graph showing the relationship between the exposure voltage and the sensitivity compensation device for the photoreceptor according to the first embodiment of the invention; FIG. 2 is a graph showing the relationship between the pressure contact time of the cleaning blade in the image forming apparatus and the exposure voltage at which the sensitivity compensation device for the photoreceptor according to the second embodiment of the invention changes. FIG. 3 is a graph showing the relationship between the rotation time of the photoreceptor and the film thickness. FIG. 4 is a graph showing the relationship between the number of images formed and the standard exposure voltage as the number increases. FIG. 5 is a graph showing the relationship between the pressure contact time of the cleaning blade and the film thickness of the photoreceptor. FIG. 6 is a block diagram of a sensitivity compensation device application section of a control section of an image forming apparatus that uses the photoreceptor sensitivity compensation devices of the first and second inventions. FIG. 7 is a schematic diagram of the main parts of the image forming apparatus. FIG. 8 is a graph showing the relationship between exposure scale and exposure voltage. O-photoreceptor, 1-exposure lamp, a cleaning blade.

Claims (2)

[Claims] (1) In an image forming apparatus that exposes a photoreceptor to image-forming light such as reflected light from a document, a storage means for accumulating and storing the rotation time of the photoreceptor;
A sensitivity compensation device for a photoreceptor, comprising: exposure voltage control means for increasing an input voltage to an exposure lamp of the photoreceptor in accordance with an increase in the rotation time stored in the storage means. (2) In an image forming apparatus including a cleaning device that exposes a photoreceptor to imaging light such as reflected light from a document and has a cleaning blade that presses against the photoreceptor only during image formation, the cleaning blade is in pressure contact with the photoreceptor. A photoreceptor characterized in that it is provided with a storage means for accumulating and storing it, and an exposure voltage control means for increasing an input voltage to an exposure lamp of the photoreceptor in accordance with an increase in the pressure contact time stored in the storage means. Sensitivity compensation device.