JP2001154429A - Device and method for forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device and an image forming method by which the fatigue and the secular change of the respective parts of the device can be precisely grasped. SOLUTION: A fatigue evaluation value is obtained by integrating the rotating amount of an intermediate transfer belt 41 (counted value of rotation). Based on it, the fatigue and the secular change of the respective parts of the device are presumed. Therefore, the fatigue and the secular change of the respective parts of the device can be precisely presumed. Even when the printing processing of one sheet is performed, the rotating amount of the belt 4 is one round in the case of monochromatic printing. However, it becomes 4 rounds in the case of color printing and corresponds to the degree of the fatigue and the secular change of a photoreceptor 21, a developing part 23 and the like. Therefore, even when the color printing and the monochromatic printing coexist, the fatigue and the secular change of the respective parts of the device can be precisely presumed by using the fatigue evaluation value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for charging a surface of a photoreceptor by charging means, forming an electrostatic latent image on the surface of the photoreceptor, and further developing the electrostatic latent image with toner by a developing means. The present invention relates to an image forming apparatus and an image forming method that form a toner image by being exposed.

[0002]

2. Description of the Related Art In an image forming apparatus of this type, the image density may change due to fatigue and time-dependent changes of each part of the apparatus such as a photoconductor and a developing device, and changes in temperature and humidity around the apparatus. . Therefore, conventionally, there have been proposed many techniques for stabilizing the image density by adjusting the density control factors affecting the image density of the toner image, for example, the charging bias, the developing bias, and the exposure amount at an appropriate timing.
For example, in a conventional image forming apparatus, the number of printed sheets is cumulatively counted, and the execution timing of the density adjustment processing for adjusting the image density is determined based on the cumulative count value (total number of printed sheets).

[0003]

Here, when the printing process is continuously performed in the same size and in the same image forming mode, the photosensitive member and the developing device are changed based on the number of printed sheets as in the above-mentioned conventional example. It is possible to estimate the fatigue and the change with time and perform the density adjustment processing at an appropriate timing. However, since the operation of each unit of the apparatus such as the photoconductor and the developing device is different between the color printing and the monochrome printing, the density adjustment processing cannot be performed at an appropriate timing by setting the timing based on the number of printed sheets. For example, even when printing one sheet, in the color print mode, it is necessary to form yellow, cyan, magenta, and black toner images on the photoconductor, and to superimpose the toner images on the intermediate transfer medium. There is. On the other hand, in the monochrome print mode, the toner image formed on the photoconductor is only one type of black toner image. Therefore, the rotation amount of the photoconductor and the intermediate transfer medium in the color print mode is about four times that in the monochrome print mode. Therefore, even if the number of printed sheets is the same, the fatigue and the change over time of the photosensitive member in color printing are inevitably greater than those in monochrome printing.

Therefore, in an image forming apparatus that prints in various image forming modes, if the density adjustment processing is determined based on the number of printed sheets, it is not possible to perform an appropriate density adjustment processing.

In some cases, the photoreceptor and the intermediate transfer medium idle during the image forming process. During the idle process, each part of the apparatus is operating.
Changes with time progress. Furthermore, in this type of image forming apparatus, an initial operation that is not directly involved in image forming processing such as initialization is executed immediately after the power is turned on. During this initial operation, the photoconductor and the intermediate transfer medium, etc.
A predetermined initial operation is performed. At this time, the respective parts of the apparatus are operating, and the fatigue and the change with time due to the operation progress. Therefore, it is necessary to consider this effect in order to determine an accurate density adjustment timing.

However, in the prior art, such a point was not considered at all, and it could not be said that the density adjustment processing was performed at an appropriate timing.

As described above, in the conventional image forming apparatus,
Fatigue and time-dependent changes in each part of the device, such as the photoconductor and developing unit, were estimated based on the number of printed sheets, so it was not possible to accurately capture the fatigue and time-dependent changes in each part of the device. There is a problem in that the throughput is lowered by executing the process, and conversely, the execution timing of the density adjustment process is delayed and the image quality is lowered.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its first object to provide an image forming apparatus and an image forming method capable of accurately detecting fatigue and changes over time of each part of the apparatus.

It is a second object of the present invention to provide an image forming apparatus and an image forming method capable of executing a density adjusting process at an appropriate timing.

A third object of the present invention is to provide an image forming apparatus and an image forming method which can make the fatigue and time-dependent change of each part of the apparatus known.

[0011]

Means for Solving the Problems One aspect of the present invention is as follows.
An image forming apparatus and an image forming method, wherein an electrostatic latent image is formed on a surface of a photoreceptor, and the electrostatic latent image is made visible by toner by a developing unit to form a toner image.
In order to achieve the above object, the fatigue evaluation value is obtained by integrating the rotation amount of the photoconductor, and the fatigue / time-dependent change of each part of the apparatus is estimated based on the fatigue evaluation value.

In another aspect of the present invention, an electrostatic latent image is formed on a surface of a photoreceptor, and the electrostatic latent image is made visible by a developing means to form a toner image. An image forming apparatus and an image forming method for transferring an image onto a transfer medium that rotates in synchronization with the photoconductor, wherein at least one of the photoconductor and the transfer medium is used to achieve the first object. The amount of rotation is integrated to obtain a fatigue evaluation value, and based on the fatigue evaluation value, the fatigue / time-dependent change of each part of the device is estimated.

In these inventions, the fatigue evaluation value is obtained by integrating the rotation amount of the photosensitive member or the transfer medium. For example, even when performing printing processing of one sheet, a relatively small amount of rotation is added to the fatigue evaluation value in monochrome printing, while a relatively large amount of rotation is fatigued in color printing. It is added to the evaluation value. Therefore, even if color printing and monochrome printing are mixed, the fatigue / time-dependent change of each part of the apparatus can be accurately estimated by using the fatigue evaluation value.

Further, the respective parts of the apparatus operate even while the respective parts of the apparatus are not actually executing the printing process, which leads to the fatigue of the respective parts of the apparatus and changes over time. During this operation, the photoconductor and the transfer medium may be rotating. In these inventions, the rotation amount at this time is also integrated into the fatigue evaluation value. Therefore, it is possible to accurately estimate the fatigue and the change over time of each unit of the apparatus based on the operation of the apparatus other than the printing process based on the fatigue evaluation value.

The warm-up is started immediately after the power supply of the apparatus is turned on, and each section of the apparatus operates to set a printing start state. Therefore, by starting the integration of the amount of rotation immediately after turning on the power to the apparatus, it is possible to obtain a fatigue evaluation value reflecting the fatigue and the change over time of each part of the apparatus due to the warm-up.

The rotation amount may be integrated only while the toner image is being formed. in this case,
Image forming means for forming a toner image in each part of the apparatus (a process unit including a photoconductor and a developing device)
The fatigue evaluation value corresponding to the fatigue / time-dependent change of the image forming means is obtained, and the fatigue / time-dependent change of the image forming means can be accurately estimated.

Incidentally, when the fatigue evaluation value exceeds a predetermined value,
That is, when each part of the apparatus is greatly fatigued and changes with time, it is desirable to adjust the image density of the toner image to the target density or to notify the effect. That is, a predetermined fatigue threshold value is stored, and when the fatigue evaluation value exceeds the fatigue threshold value, (1) the second object is achieved by adjusting the image density of the toner image to the target density. (2) The third object can be achieved by reporting the progress of fatigue.

[0018]

FIG. 1 is a diagram showing an example of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. This image forming apparatus forms a full-color image by superimposing four color toners of yellow (Y), cyan (C), magenta (M), and black (K), or uses only black (K) toner. To form a monochrome image. In this image forming apparatus, when an image signal (image forming command) is provided to the main controller 11 of the control unit 1 from an external device such as a host computer, the engine controller 12 responds to an instruction from the main controller 11 to cause the engine controller 12 to operate. Are formed on the sheet S to form an image corresponding to the image signal (image forming command).

In the engine section E functioning as an image forming means, a toner image can be formed on the photosensitive member 21 of the image carrier unit 2. That is, the image carrier unit 2 includes a photoconductor 21 rotatable in the direction of the arrow in FIG. 1, and further includes a charging roller 22 as a charging unit, a developing unit around the photoconductor 21 along the rotation direction. Developing units 23Y, 23C, 23M, and 23K, and a cleaning unit 24 are disposed. A high voltage is applied to the charging roller 22 from the charging bias generator 121, and the charging roller 22 contacts the outer peripheral surface of the photoconductor 21 to uniformly charge the outer peripheral surface.

Then, a laser beam L is emitted from the exposure unit 3 toward the outer peripheral surface of the photoconductor 21 charged by the charging roller 22. The exposure unit 3 is configured as shown in FIG.
Is electrically connected to the image signal switching section 122, and scans and exposes the laser beam L onto the photoconductor 21 in accordance with the image signal given through the image signal switching section 122, An electrostatic latent image corresponding to an image signal (image formation command) is formed on the image signal 21. For example, based on a command from the CPU 123 of the engine controller 12, when the image signal switching unit 122 is conducting with the patch creation module 124, the patch image signal output from the patch creation module 124 is given to the exposure unit 3. Thus, a patch latent image is formed. On the other hand, when the image signal switching unit 122 is electrically connected to the CPU 111 of the main controller 11, the laser beam L is output in accordance with an image signal (image forming command) given via an interface 112 from an external device such as a host computer. Is scanned and exposed on the photoconductor 21 to form an electrostatic latent image corresponding to the image signal on the photoconductor 21.

The electrostatic latent image thus formed is developed
Is developed with toner. That is, in this embodiment, as the developing unit 23, a developing unit 23Y for yellow, a developing unit 23C for cyan, a developing unit 23M for magenta, and a developing unit 23K for black are arranged along the photoconductor 21 in this order. Have been. These developing units 23Y and 23
Each of C, 23M, and 23K is configured to be able to freely contact and separate from the photoconductor 21, and in response to a command from the engine controller 12, the four developing units 23Y, 23M,
One of the developing units 23C and 23B selectively
1 and a high voltage is applied by the developing bias generator 125 to apply the toner of the selected color to the surface of the photoconductor 21 to make the electrostatic latent image on the photoconductor 21 visible.

The toner image developed by the developing unit 23 is primarily transferred onto the intermediate transfer belt 41 of the transfer unit 4 in a primary transfer region R1 located between the black developing unit 23K and the cleaning unit 24. The transfer unit 4
Will be described later in detail.

Also, from the primary transfer region R1 in the circumferential direction (FIG. 1)
(In the direction of the arrow in FIG. 3), a cleaning unit 24 is disposed, and scrapes off toner remaining on the outer peripheral surface of the photoconductor 21 after the primary transfer.

Next, the configuration of the transfer unit 4 will be described. In this embodiment, the transfer unit 4 includes a roller 4
2 to 47; an intermediate transfer belt 41 stretched over the rollers 42 to 47; and a secondary transfer roller 48 for secondary transferring the intermediate toner image transferred to the intermediate transfer belt 41 to the sheet S. ing. A primary transfer voltage is applied to the intermediate transfer belt 41 from a transfer bias generator 126. When the color image is to be transferred to the sheet S, the color image is formed by superimposing the toner images of each color formed on the photoreceptor 21 on the intermediate transfer belt 41, and The sheet S is taken out from the cassette 61, the manual feed tray 62 or an additional cassette (not shown) by the paper section 63, and the secondary transfer area R2
Transport to Then, a color image is secondarily transferred to the sheet S to obtain a full-color image. When a monochrome image is to be transferred to the sheet S, only a black toner image is formed on the photoreceptor 21 on the intermediate transfer belt 41, and is conveyed to the secondary transfer region R2 in the same manner as in the case of a color image. Is transferred to the sheet S to obtain a monochrome image.

After the secondary transfer, the toner remaining on the outer peripheral surface of the intermediate transfer belt 41 is removed by the belt cleaner 49. This belt cleaner 4
Reference numeral 9 denotes an intermediate transfer belt which is disposed opposite to the roller 46 with the intermediate transfer belt 41 interposed therebetween. At an appropriate timing, the cleaner blade comes into contact with the intermediate transfer belt 41 to scrape the toner remaining on the outer peripheral surface thereof. Drop.

In the vicinity of the roller 43, a patch sensor PS and a synchronization reading sensor RS are arranged. The patch sensor PS is a sensor for detecting the density of a patch image formed on the outer peripheral surface of the intermediate transfer belt 41. On the other hand, the reading sensor RS for synchronization is
A sensor for detecting one reference position, and functions as a vertical synchronization reading sensor for obtaining a synchronization signal in a sub-scanning direction substantially orthogonal to the main scanning direction, that is, a vertical synchronization signal VSYNC. Then, each time the intermediate transfer belt 41 makes one rotation, it outputs a signal of one pulse.

Returning to FIG. 1, the description of the configuration of the engine unit E will be continued. The sheet S to which the toner image has been transferred by the transfer unit 4 is disposed downstream of the secondary transfer area R2 along a predetermined paper feed path (two-dot chain line) by the paper feed unit 63 of the paper feed / discharge unit 6. The toner image on the sheet S conveyed to the fixing unit 5 is fixed to the sheet S. Then, the sheet S is further conveyed to the sheet discharging unit 64 along the sheet feeding path 630.

The paper discharge section 64 has two paper discharge paths 641
a, 641b, one of the paper discharge paths 641a extends from the fixing unit 5 to the standard paper discharge tray,
The other paper discharge path 641b extends between the re-feed unit 66 and the multi-bin unit substantially in parallel with the paper discharge path 641a. Along these discharge paths 641a and 641b, 3
A pair of rollers 642 to 644 are provided, and a sheet re-feeding unit for discharging the fixed sheet S toward the standard sheet discharge tray or the multi-bin unit or forming an image on the other side. To the 66 side.

As shown in FIG. 1, the re-feeding section 66
The sheet S reversely conveyed from the sheet discharge section 64 as described above is fed along the re-feed path 664 (two-dot chain line).
And the three re-feeding roller pairs 6 arranged along the re-feeding path 664.
61 to 663. As described above, the paper discharge unit 6
4 is returned to the gate roller pair 637 along the re-feed path 664 so that the sheet S
3, the non-image forming surface of the sheet S is the intermediate transfer belt 4
1 and the image can be secondarily transferred to the surface.

In FIG. 2, reference numeral 113 denotes an interface 11 from an external device such as a host computer.
2 is an image memory provided in the main controller 11 for storing an image given through
Reference numeral 7 denotes control data and CPU for controlling the engine unit E.
Reference numeral 128 denotes a RAM for temporarily storing a calculation result and the like in the 123, and reference numeral 128 denotes a ROM for storing a calculation program and the like performed by the CPU 123.

Next, a description will be given of a density adjusting operation in the image forming apparatus configured as described above. In the embodiment described below, the engine controller 12 adjusts the density of an image formed by the image forming apparatus while controlling the engine unit E as described below. It functions as a means.

<First Embodiment> FIG. 3 is a flowchart showing a first embodiment of the image forming apparatus according to the present invention. In the first embodiment, as shown in FIG.
When the apparatus power is turned on (step S1), the process waits until a pulse-shaped vertical synchronization signal VSYNC is output from the vertical synchronization reading sensor RS (step S2). Here, the vertical synchronization reading sensor RS is connected to the intermediate transfer belt 41 as described above.
1 pulse is output each time the circuit makes one round.

Therefore, in this embodiment, the rotation count value is set to an appropriate value, for example, "1", and when the pulse-like vertical synchronization signal VSYNC is output, the rotation count value is incremented to obtain the fatigue evaluation value. (Step S
3). Therefore, while the total number of rotations of the intermediate transfer belt 41 is relatively small and the fatigue and aging of each part of the apparatus are small,
Although the fatigue evaluation value is small, when the printing process is repeatedly executed,
The total number of rotations of the intermediate transfer belt 41 increases, and the fatigue evaluation value becomes a large value. That is, the fatigue evaluation value functions as an index value indicating the fatigue / time-dependent change of each part of the device.

In the next step S4, the fatigue evaluation value is compared with a fatigue threshold value previously set and stored in the ROM 128. Then, while the fatigue evaluation value is less than the fatigue threshold, that is, while determining “NO” in step S4, the process returns to step S2, and steps S2 to S4 are repeated.

On the other hand, if it is determined in step S4 that the fatigue evaluation value is equal to or greater than the fatigue threshold value, that is, if it is determined that the various parts of the apparatus are undergoing fatigue and aging, concentration adjustment processing is executed. However, the density adjustment processing cannot be performed at an arbitrary timing. For example, when performing color printing, four colors (yellow, cyan, magenta,
Since it is necessary to transfer while superimposing the toner image on the intermediate transfer belt 41 while sequentially forming the toner image of (black), it is not possible to shift to the density adjustment processing at the stage of forming the toner image in the middle.

Therefore, in this embodiment, step S5
Then, it is determined whether or not the density adjustment processing can be executed. When the execution becomes possible, the process proceeds to step S6 to execute the density adjustment processing. In this embodiment, the density adjustment is performed by executing the following two steps, but the content of the density adjustment is not limited to this.

(1) While fixing the charging bias applied from the charging bias generator 121 to the charging roller 22, while changing the developing bias applied from the developing bias generator 125 to the developing unit 23, a plurality of patch images (solid images) are ) Is formed, the density of the patch images is detected by the patch sensor PS, and the optimum developing bias necessary for obtaining the target density is determined based on the detected values (image density of the patch image).

(2) A plurality of patch images (halftone images) are sequentially formed while changing the charging bias while the developing bias is fixed to the optimum developing bias previously obtained, and the image density of the patch images is changed. Patch sensor P
Detected by S and their detected values (image density of patch image)
The optimum charging bias required to obtain the target density is determined based on the above.

When the density adjustment process is completed, the fatigue evaluation value is cleared, the process returns to step S2, and the above series of processes (steps S2 to S6) are repeated.

As described above, according to the first embodiment, the fatigue evaluation value is obtained by integrating the rotation amount (rotation count value) of the intermediate transfer belt 41, and based on this, the fatigue / time-dependent change of each part of the apparatus is determined. Since the estimation is made, it is possible to accurately estimate the fatigue and the change with time of each part of the device. What happens
Even when one sheet of print processing is performed, the rotation amount of the intermediate transfer belt 41 is one rotation in the case of monochrome printing, whereas the rotation amount of the intermediate transfer belt 41 is four in the case of color printing. Around the photoconductor 21, the developing unit 23, etc.
It depends on the degree of change over time. Therefore, even if color printing and monochrome printing are mixed, the fatigue / time-dependent change of each part of the apparatus can be accurately estimated by using the fatigue evaluation value.

In this embodiment, since the integration of the rotation amount is started immediately after the power supply to the apparatus is turned on, the following operation and effect can be obtained. When the power supply to the apparatus is turned on, the warm-up is started, and each section of the apparatus operates irrespective of the actual printing. This is one of the causes of fatigue and aging of each section of the apparatus. In this embodiment, since the rotation amount (rotation count value) of the intermediate transfer belt 41 during the warming-up is integrated into the fatigue evaluation value, the fatigue evaluation value reflecting the fatigue / time-dependent change of each part of the apparatus due to the warming-up is calculated. It is possible to obtain
The change with time can be accurately estimated.

Also, other than during the warm-up, and while the printing process is not being executed, each part of the apparatus may be operating while the intermediate transfer belt 41 and the photosensitive member 21 run idle. Also in this case, fatigue and time-dependent changes of respective parts of the apparatus progress during the idling. On the other hand, according to the first embodiment, even during the idling, the rotation amount (rotation count value) of the intermediate transfer belt 41 is integrated into the fatigue evaluation value. It is possible to obtain a fatigue evaluation value reflecting the fatigue / temporal change of the apparatus, and to accurately estimate the fatigue / temporal change of each part of the apparatus.

<Second Embodiment> FIG. 4 is a flowchart showing a second embodiment of the image forming apparatus according to the present invention. The second embodiment differs greatly from the first embodiment in that a detection sensor (not shown) for detecting the temperature and humidity inside the device is provided in the engine unit E, and an output signal from this detection sensor is provided. CPU 12
3 is that the rotation count value is corrected according to the temperature and humidity inside the apparatus. The other configurations are the same.

In this embodiment, when the apparatus power is turned on (step S1), the apparatus waits for a pulse-shaped vertical synchronization signal VSYNC to be output from the vertical synchronization reading sensor RS (step S2), and then proceeds to the next step. Proceed to S11.

In this step S11, the vertical synchronizing signal V
The temperature and humidity inside the device at the time when SYNC is output are measured by the detection sensor. Then, the rotation count value is corrected based on the measurement result (step S12). For example, the relationship between the temperature / humidity and the correction coefficient may be checked in advance, the relation table may be stored in the ROM 128, and the correction coefficient A2 corresponding to the measurement result may be read from the ROM 128 to correct the rotation count value. . Also,
Instead of the relation table, a relational expression between the temperature / humidity and the correction coefficient may be used.

Then, the thus corrected value (= “rotation count value” × A 2) is integrated to obtain a fatigue evaluation value (step S13). The major reason why the rotation count value is corrected based on the temperature and the humidity is that the degree of fatigue progress of each unit such as the photoconductor 21 and the developing unit 23 varies depending on the surrounding temperature and the surrounding humidity. As in this embodiment, by correcting the rotation count value based on the temperature and the humidity, it is possible to more accurately estimate the fatigue and the change with time.

After the fatigue evaluation value is obtained in this way, the density adjustment processing is executed at an appropriate timing as in the first embodiment. That is, the fatigue evaluation value is stored in the ROM 128 in advance.
(Step S4), it is determined that the fatigue evaluation value is equal to or greater than the fatigue threshold, and it is confirmed that the density adjustment processing can be performed (step S5). ) Later, the density adjustment processing is executed (step S6).

When the concentration adjustment processing is completed, the fatigue evaluation value is cleared, the flow returns to step S2, and the above-described series of processing (steps S2, S11 to S13, and S4 to S6) is repeated.

<Third Embodiment> FIG. 5 is a flowchart showing a third embodiment of the image forming apparatus according to the present invention. The third embodiment is largely different from the first embodiment in that a detection sensor (not shown) for detecting the temperature and humidity inside the device is provided in the engine unit E, and an output signal from the detection sensor is provided. CPU 12
3 is that the fatigue evaluation value is corrected according to the temperature and humidity inside the apparatus. The other configurations are the same.

In this embodiment, when the apparatus power is turned on (step S1), a pulse-shaped vertical synchronization signal VSYNC is output from the vertical synchronization reading sensor RS (step S1).
2) Every time, the rotation count value is incremented to obtain a fatigue evaluation value (step S3).

Next, before comparing the fatigue evaluation value with the fatigue threshold value (step S4), the fatigue evaluation value is corrected according to the temperature and humidity inside the apparatus. That is, step S2
In 1, the temperature and humidity inside the device are measured by a detection sensor. Then, the fatigue evaluation value is corrected based on the measurement result (step S22). For example, the relationship between the temperature and humidity and the correction coefficient is checked in advance, and the relationship table is stored in the ROM
128, the correction coefficient A3 corresponding to the measurement result may be read from the ROM 128 to correct the fatigue evaluation value. Also, instead of a relation table,
A relational expression between the temperature / humidity and the correction coefficient may be used.

A major reason for correcting the fatigue evaluation value based on the temperature and humidity in this way is that the temperature and humidity are constant in the first embodiment despite the fact that the image density changes depending on the ambient temperature and the ambient humidity. This is because the density adjustment processing may not be properly performed because the fatigue evaluation value is obtained based on the premise. For example, when the fatigue evaluation value is less than the fatigue threshold value at a specific temperature and humidity, a toner image can be formed at a predetermined density. May not be able to form a toner image at a predetermined density even if is less than the fatigue threshold.

The value thus corrected (= “fatigue evaluation value before correction” × A 3) is compared with a fatigue threshold value previously set and stored in the ROM 128 (step S 4).
After determining that the fatigue evaluation value is equal to or greater than the fatigue threshold value and further confirming that the density adjustment processing can be executed (step S5), the density adjustment processing is executed (step S5).
6). As described above, by correcting the fatigue evaluation value based on the temperature and the humidity, the above-mentioned problem caused by the temperature and the humidity is solved.

When the density adjustment process is completed, the fatigue evaluation value is cleared and the process returns to step S2 to return to the above-described series of processes (steps S2, S3, S21, S22, S4 to S4).
Repeat 6).

In this embodiment, the fatigue evaluation value is corrected according to the temperature and humidity inside the apparatus. However, the same operation and effect can be obtained by correcting the fatigue threshold value instead of the fatigue evaluation value. Is obtained.

<Fourth Embodiment> FIG. 6 is a flowchart showing a fourth embodiment of the image forming apparatus according to the present invention. The fourth embodiment is significantly different from the first embodiment in that the rotation count value is corrected based on the image forming mode. The other configurations are the same.

In this embodiment, when the apparatus power is turned on (step S1), the apparatus waits for a pulse-shaped vertical synchronizing signal VSYNC to be output from the vertical synchronizing read sensor RS (step S2). Proceed to S31.

In step S31, the rotation count value is corrected based on the image forming mode. Here, the image forming mode includes a print mode, a print sheet type, and the like. For example, in the case of color printing, since the necessity of density adjustment processing is higher than in the case of monochrome printing, the rotation count value is corrected to be higher than that in the case of monochrome printing, and the interval is relatively short. It is desirable to execute a density adjustment process. In contrast, in the case of monochrome printing, the necessity of the density adjustment processing is lower than in the case of color printing, and it is desirable to increase the interval of the density adjustment processing or to improve the throughput by not performing the density adjustment processing. In order to satisfy such a demand, the rotation count value is set relatively high when color printing is selected as the printing mode, while the rotation count value is set relatively low or zero for monochrome printing. The rotation count value is corrected according to the image forming mode.

As for the type of sheet to be printed, similarly to the print mode, there are different demands when printing on ordinary plain paper and when printing on special paper such as postcards or color-only paper. In other words, special paper is more expensive than plain paper, and when printing on special paper, we want to perform density adjustment processing at relatively short intervals to prevent printing failure due to poor density etc. When printing on plain paper, there is a demand to increase the interval of the density adjustment processing to improve the throughput. Therefore, in order to satisfy such a demand, when the special paper is selected as the print sheet type, the rotation count value is set relatively high, while the rotation count value is set relatively low or zero for plain paper. The rotation count value is corrected according to the image forming mode.

Then, the fatigue correction value is obtained by integrating the corrected values (= “rotation count value” × A4) (step S32), and then the density is adjusted at an appropriate timing as in the first embodiment. Execute the process. That is, the fatigue evaluation value is compared with a fatigue threshold value previously set and stored in the ROM 128 (step S4), and it is determined that the fatigue evaluation value is equal to or greater than the fatigue threshold value. After confirming that (step S5), a density adjustment process is executed (step S6).

When the concentration adjustment processing is completed, the fatigue evaluation value is cleared, the flow returns to step S2, and the above series of processing (steps S2, S31, S32, S4 to S6) is repeated.

<Fifth Embodiment> FIG. 7 is a flowchart showing a fifth embodiment of the image forming apparatus according to the present invention. The fifth embodiment is significantly different from the first embodiment in that the fatigue evaluation value is corrected based on the image forming mode. The other configurations are the same.

In this embodiment, when the apparatus power is turned on (step S1), a pulse-like vertical synchronization signal VSYNC is output from the vertical synchronization reading sensor RS (step S1).
2) Every time, the rotation count value is incremented to obtain a fatigue evaluation value (step S3).

Next, before comparing the fatigue evaluation value with the fatigue threshold value (step S4), the fatigue evaluation value is corrected based on an image forming mode such as a print mode or a print sheet type. Here, the reason for performing such correction is the same as in the fourth embodiment. That is, when color printing is selected as the printing mode (image forming mode), the fatigue evaluation value is set to a relatively high value to prompt the density adjustment processing, while for monochrome printing, the fatigue evaluation value is corrected to a relatively low value or to zero. Then, the interval of the density adjustment processing is widened to improve the throughput.

Also, regarding the type of sheet to be printed, when special paper is selected as the type of printing sheet, the fatigue evaluation value is set relatively high to prompt the density adjustment processing, while when the plain paper is selected. In order to improve throughput, the fatigue evaluation value is corrected to a relatively low value or zero, thereby increasing the interval of the density adjustment processing.

Then, the corrected value (= “fatigue evaluation value before correction” × A5) is compared with a fatigue threshold value previously set and stored in the ROM 128 (step S4).
After determining that the fatigue evaluation value is equal to or greater than the fatigue threshold value and further confirming that the density adjustment processing can be executed (step S5), the density adjustment processing is executed (step S5).
6). As described above, by correcting the fatigue evaluation value based on the temperature and the humidity, the above-mentioned problem caused by the temperature and the humidity is solved.

When the concentration adjustment process is completed, the fatigue evaluation value is cleared, the process returns to step S2, and the above-described series of processes (steps S2, S3, S41, S4 to S6) are repeated.

In this embodiment, the fatigue evaluation value is corrected in accordance with the image forming mode. However, similar effects can be obtained by correcting the fatigue threshold value instead of the fatigue evaluation value. .

<Sixth Embodiment> FIG. 8 is a flowchart showing a sixth embodiment of the image forming apparatus according to the present invention. The sixth embodiment differs from the first embodiment in that the rotation count value is integrated only immediately after the apparatus power is turned on, in that the rotation count value is integrated only while the toner image is being created. ing. The other configurations are the same.

In this type of image forming apparatus, when a job is given from the main controller 11 to the engine controller 12, the engine unit E creates a toner image corresponding to the job and transfers it to the sheet S. Thus, in this embodiment, after the job is received in step S51, until the completion of the job is confirmed in step 52, the amount of rotation (rotation count value) of the intermediate transfer belt 41 is the same as in the first embodiment. ) Is integrated to obtain a fatigue evaluation value to estimate the fatigue and changes over time of each part of the device.
When the fatigue evaluation value is equal to or more than a predetermined fatigue threshold value and it is confirmed that the density adjustment processing can be performed,
The density adjustment process is being performed.

As described above, in the sixth embodiment, the image forming means for forming a toner image, that is, the process unit including the image carrier unit 2 and the exposure unit 3 in the various parts of the apparatus can cope with fatigue and changes over time. The fatigue evaluation value can be obtained, and the fatigue / time-dependent change of the image forming means can be accurately estimated.

In the sixth embodiment, whether or not the toner image is being formed is determined based on the reception and completion of the job.
May be determined based on the rotation / stop of the scanner motor that scans in the main scanning direction, or based on whether an image signal is given to the exposure unit 3.

The rotation count value is corrected as in the second and fourth embodiments, or the fatigue evaluation value (or the fatigue threshold value) as in the third and fifth embodiments. ) May be corrected. In these cases, the same operation and effect as described in each embodiment can be obtained.

The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, in the above embodiment, the fatigue evaluation value is calculated based on the rotation amount (rotation count value) of the intermediate transfer belt 41. However, the fatigue evaluation value may be calculated based on only the rotation amount of the photoconductor 21 or both rotation amounts. It may be.

In the above embodiment, both the temperature and the humidity inside the apparatus are measured by the detection sensor, and the rotation count value (rotation amount), the fatigue evaluation value, or the fatigue threshold is corrected based on the measurement result. However, even if the correction is made based only on the temperature inside the apparatus or only on the humidity inside the measure, the same effect as that obtained when the correction is made based on the temperature and humidity can be obtained. However, in order to more accurately obtain the fatigue and the change over time, it is desirable to make correction based on both the temperature and the humidity inside the apparatus.

In the above embodiment, the concentration adjustment processing is performed when the fatigue evaluation value is equal to or greater than the fatigue threshold value. You may.

The image forming apparatus according to the above embodiment forms an image given from an external device such as a host computer via the interface 112 on sheets such as copy paper, transfer paper, paper, and a transparent sheet for OHP. Although the present invention is a printer, the present invention can be applied to all electrophotographic image forming apparatuses such as copying machines and facsimile machines. In the above embodiment, after the toner image on the photoconductor 21 is transferred to the intermediate transfer belt 41, the sheet S
However, the present invention can also be applied to an image forming apparatus that directly transfers a toner image on the photoconductor 21 to a sheet.

Further, in the above embodiment, the toner image on the photosensitive member 21 is transferred to the intermediate transfer belt 41. However, transfer media other than the intermediate transfer belt (transfer drum, transfer belt, transfer sheet, intermediate transfer drum, The present invention can also be applied to an image forming apparatus that transfers a toner image to an intermediate transfer sheet, a reflective recording sheet, a transparent storage sheet, or the like.

[0079]

As described above, according to the present invention, the fatigue evaluation value is obtained by integrating the rotation amount of the photosensitive member or the transfer medium, and the fatigue / time-dependent change of each part of the apparatus is estimated based on the fatigue evaluation value. Therefore, the fatigue and time-dependent changes of each part of the apparatus can be accurately grasped.

According to the ninth aspect of the present invention, since the integration of the rotation amount is started immediately after the power supply to the apparatus is turned on, the fatigue evaluation value reflecting the fatigue and the change over time of each part of the apparatus due to the warm-up is obtained. You can ask.

According to the tenth aspect of the present invention, the amount of rotation is integrated only while the toner image is being formed. The fatigue evaluation value corresponding to the fatigue / time-dependent change of the process unit (e.g., a process unit including a body and a developing device) is obtained, and the fatigue / time-dependent change of the image forming unit can be accurately estimated.

According to the third and thirteenth aspects of the present invention, when the fatigue evaluation value exceeds a predetermined value, that is, when each part of the apparatus is greatly fatigued and changes with time, the image density of the toner image is set to the target density. Since the adjustment is performed, the density adjustment processing can be executed at an appropriate timing.

Further, according to the fourth and fourteenth aspects of the present invention, when the fatigue evaluation value exceeds a predetermined value, that is, when the respective parts of the apparatus are largely fatigued and changed with time, the progress of fatigue is reported. Fatigue and changes over time of each part of the device can be made known.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating an electrical configuration of the image forming apparatus of FIG. 1;

FIG. 3 is a flowchart illustrating a first embodiment of the image forming apparatus according to the present invention.

FIG. 4 is a flowchart illustrating a second embodiment of the image forming apparatus according to the present invention.

FIG. 5 is a flowchart illustrating a third embodiment of the image forming apparatus according to the present invention;

FIG. 6 is a flowchart illustrating a fourth embodiment of the image forming apparatus according to the present invention.

FIG. 7 is a flowchart illustrating a fifth embodiment of the image forming apparatus according to the present invention;

FIG. 8 is a flowchart illustrating a sixth embodiment of the image forming apparatus according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control unit (control means) 2 image carrier unit (image forming means) 3 exposure unit (image forming means) 12 engine controller (control means) 21 photoconductor 23 developing sections 23Y, 23C, 23M, 23K: Developing device 41: Intermediate transfer belt (transfer medium) 123: CPU (control means) RS: Read sensor for vertical synchronization VSYNC: Vertical synchronization signal

Claims (14)

[Claims] 1. An image forming apparatus for forming an electrostatic latent image on a surface of a photoreceptor and developing the electrostatic latent image with toner by a developing unit to form a toner image, comprising: An image forming apparatus comprising: a control unit that obtains a fatigue evaluation value by integrating the values, and estimates a fatigue / time-dependent change of each unit of the apparatus based on the fatigue evaluation value. 2. An electrostatic latent image is formed on a surface of a photoreceptor, and the electrostatic latent image is made visible by toner by a developing unit to form a toner image, and the toner image is synchronized with the photoreceptor. In an image forming apparatus for transferring images onto a transfer medium that rotates by rotation, the amount of rotation of at least one of the photoconductor and the transfer medium is integrated to obtain a fatigue evaluation value, and the fatigue / time of each part of the apparatus is determined based on the fatigue evaluation value. An image forming apparatus comprising control means for estimating a change. 3. The control unit according to claim 1, wherein a predetermined fatigue threshold value is stored, and when the fatigue evaluation value exceeds the fatigue threshold value, the image density of the toner image is adjusted to a target density.
Or the image forming apparatus according to 2. 4. The image forming apparatus according to claim 1, wherein said control means stores a predetermined fatigue threshold value, and notifies the progress of fatigue when a fatigue evaluation value exceeds said fatigue threshold value. apparatus. 5. The apparatus according to claim 1, further comprising detecting means for detecting at least one of temperature and humidity inside the apparatus, wherein said control means corrects a rotation amount based on a detection result by said detecting means, and calculates the corrected rotation amount. The image forming apparatus according to claim 3, wherein the image is integrated with the fatigue evaluation value. 6. The apparatus according to claim 1, further comprising detection means for detecting at least one of temperature and humidity inside the apparatus, wherein said control means corrects said fatigue evaluation value or said fatigue threshold value based on a detection result by said detection means. Item 5. The image forming apparatus according to item 3 or 4. 7. The image forming apparatus according to claim 3, wherein the control unit corrects a rotation amount based on an image forming mode, and integrates the corrected rotation amount into the fatigue evaluation value. 8. The image forming apparatus according to claim 3, wherein the control unit corrects the fatigue evaluation value or the fatigue threshold based on an image forming mode. 9. The image forming apparatus according to claim 1, wherein the control unit starts the integration of the rotation amount immediately after the power supply of the apparatus is turned on. 10. The image forming apparatus according to claim 1, wherein the control unit performs the integration of the rotation amount only while forming the toner image. 11. An image forming method for forming an electrostatic latent image on a surface of a photoreceptor and developing the electrostatic latent image with toner by a developing unit to form a toner image. An image forming method comprising: obtaining a fatigue evaluation value by integrating the values; and estimating a fatigue / time-dependent change of each part of the apparatus based on the fatigue evaluation value. 12. An electrostatic latent image is formed on the surface of a photoreceptor, and the electrostatic latent image is made visible by toner by a developing means to form a toner image. The toner image is synchronized with the photoreceptor. In the image forming method of transferring onto a rotating transfer medium, the rotation amount of at least one of the photosensitive member and the transfer medium is integrated to obtain a fatigue evaluation value, and the fatigue / time of each part of the apparatus is determined based on the fatigue evaluation value. An image forming method characterized by estimating a change. 13. The image forming method according to claim 11, wherein when the fatigue evaluation value exceeds a predetermined fatigue threshold value, a density adjustment process for adjusting an image density of the toner image to a target density is executed. 14. The image forming method according to claim 11, wherein when the fatigue evaluation value exceeds a predetermined fatigue threshold value, the progress of fatigue is notified.