JP2001154428A - 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 density adjustment processing can be performed in proper timing. SOLUTION: While a printing mode is not changed, the density adjustment processing is not started as usual unless a density adjustment start condition (fatigue evaluation value is equal to or over a fatigue threshold) is not satisfied. When the printing mode is changed, the density adjustment processing is immediately started. Due to that, since the density is adjusted before a toner image is formed in the printing mode after being changed, the toner image can be always formed on an excellent image forming condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a plurality of printing modes different from each other, and forms a toner image in a printing mode corresponding to an image forming command given from outside the apparatus among the plurality of printing modes. And an image forming method.

[0002]

2. Description of the Related Art In this type of image forming apparatus, the image density may change due to fatigue and changes over time of the photosensitive member and the developing unit, and changes in temperature and humidity around the apparatus. Therefore, conventionally, density control factors that affect the image density of a toner image, such as a charging bias, a developing bias,
Many techniques for stabilizing the image density by adjusting the exposure amount or the like at an appropriate timing have been proposed. For example, in a conventional image forming apparatus, the number of printed sheets is cumulatively counted to obtain a fatigue evaluation value indicating the degree of progress of fatigue and time-dependent change of each part of the apparatus, and the fatigue evaluation value is equal to or greater than a predetermined fatigue threshold. At times, image density is adjusted by executing density adjustment processing.

[0003]

Incidentally, an image forming apparatus usually has a plurality of print modes. Then, image formation is performed while appropriately changing the print mode according to an image formation command given from outside the apparatus. Here, when the print mode is changed, there is a case where it is desired to change the execution timing of the density adjustment processing in accordance with the mode change.

[0004] For example, government-made postcards include mailing costs, which are extremely expensive compared to ordinary plain paper. For this reason, when printing a postcard, it is desired to print under the best possible image forming conditions. Therefore, it is necessary to control the image forming conditions more closely than other paper types, and the fatigue evaluation value at the time of mode change is smaller than the fatigue threshold value, that is, the fatigue / time-dependent change of each part of the apparatus is less. Even if it has not progressed, it is desirable to execute the density adjustment processing prior to postcard printing. Further, even during postcard printing, it is desirable to execute the density adjustment processing at shorter execution intervals than when printing plain paper.

[0005] Such a situation is the same in the case of color-only paper. That is, color-only paper is not as expensive as postcards, but is more expensive than ordinary plain paper. Moreover, it is clear that users expect high-quality output from the usage purpose. Therefore, as in the case of postcards, the image forming conditions must be strictly managed, and the density adjustment processing is executed prior to color printing on the color paper, or the density adjustment processing is performed during the printing of the color paper. It is desirable to shorten the execution interval of.

Further, there is a case where the user explicitly specifies the high image quality mode. In this case, too, high-quality output is expected, so strict control of image forming conditions must be performed as in the case of postcards and color-only paper, and density adjustment prior to high-quality printing It is desirable to execute the processing or shorten the execution interval of the density adjustment processing during high-quality printing.

However, in the prior art, even when the mode is changed, the execution timing of the density adjustment processing is always performed under a fixed density adjustment start condition (the fatigue evaluation value is equal to or higher than a predetermined fatigue threshold). Was decided.
Therefore, there is a problem that density adjustment processing suitable for each print mode cannot be performed.

The present invention has been made in view of the above problems, and has as its object to provide an image forming apparatus and an image forming method that can execute density adjustment processing at appropriate timing.

[0009]

An image forming apparatus according to the present invention has a plurality of print modes different from each other, and a print mode corresponding to an image forming command given from outside the apparatus among the plurality of print modes. Forming an electrostatic latent image on the surface of the photoreceptor, developing the electrostatic latent image with toner by developing means to form a toner image, and further forming the toner image on a sheet directly or via a transfer medium. In the image forming apparatus to which the image is to be transferred, the density adjustment process is started when the density adjustment start condition, which is the start condition of the density adjustment process, is satisfied while the toner image is being formed and the transfer process is being performed in each print mode. Control means for adjusting the image density of the toner image to the target density. Then, in order to achieve the above object, when the print mode is changed to another print mode, the control means changes the density adjustment start condition in accordance with the change of the print mode.

Further, the image forming method according to the present invention comprises:
It has a plurality of print modes different from each other, and in the print mode corresponding to an image forming command given from outside the apparatus among the plurality of print modes, forms a toner image,
In the meantime, when a predetermined density adjustment start condition is satisfied, the image forming method starts the density adjustment process to adjust the image density of the toner image to the target density. When the print mode is changed to another print mode, the density adjustment start condition is changed in accordance with the mode change.

In these inventions, the density adjustment start condition is changed in accordance with the change of the print mode, and the density adjustment processing is executed at a timing suitable for the changed print mode.

[0012]

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 prints a full-color image on a sheet by superimposing toners of four colors of yellow (Y), cyan (C), magenta (M), and black (K), or only a black (K) toner. Is a device that prints a monochrome image on a sheet by using. In this image forming apparatus, an image signal (image forming command) is sent from an external device such as a host computer.
Is given to the main controller 11 of the control unit 1, the main controller 11 converts the job data into a format suitable for the operation instruction of the engine unit E. Then, the engine controller 12 controls each part of the engine unit E according to the job data from the main controller 11, and forms an image corresponding to the image signal (image forming command) on the sheet S.

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 forming command) is formed on the image forming device 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 light L is output in accordance with an image signal (image formation 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.

In this embodiment, a maximum A
A three-size toner image can be formed.
It is possible to simultaneously image two sheets of size or four sheets of postcard size.

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 structure of the transfer unit 4 will be described later in detail.

Also, the circumferential direction from the primary transfer region R1 (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, toner remaining on the outer peripheral surface of the intermediate transfer belt 41 is removed by a 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 all of the embodiments described below, the main controller 11
Converts an image forming command from an external device into one or a plurality of job data and sequentially gives the job data to the engine controller 12. For example, when an image forming command to print five A4 size documents is transmitted to the main controller 11 from an external device, in the image forming apparatus according to the present embodiment, the main controller 11 transmits the image forming command to the engine unit E. The job data is converted into the following three job data in order to make the format suitable for the operation instruction.

(1) A job for printing two A4 size documents; (2) A job for printing two A4 size documents; (3) A job for printing one A4 size document; The job includes various print mode information indicating the print mode, and job data indicating each job is sequentially provided to the engine controller 12.

Here, the print mode information includes color / monochrome print information indicating whether color printing or monochrome printing is performed, and whether printing is performed on plain paper or special paper that is more expensive than plain paper such as color dedicated paper or postcard. Sheet type information indicating whether printing is performed with high quality, print quality information indicating whether printing is performed with high image quality or normal image quality, and the like.

Then, the engine controller 12 having received the job data including these print mode information controls the density of the image printed by the image forming apparatus at an appropriate timing while controlling the engine unit E as follows. I do.

<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 job data is sent from the main controller 11 (step S1), it is determined whether the print mode of the received job has been changed from the previous print mode (step S2). Specifically, when the color / monochrome print information, the sheet type information, or the print quality information among the print mode information of the job has changed, it is determined that the print mode has been changed.

If it is determined in step S2 that there is no change in the print mode, the fatigue evaluation value is obtained by integrating the number of prints in the same manner as in the conventional example (step S3), and this fatigue evaluation value is previously set and stored in the ROM 128. It is compared with the set fatigue threshold (step S4). While the fatigue evaluation value is less than the fatigue threshold, that is, “N” in step S4.
While determining "O", the process returns to step S1 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, that is, if each part of the apparatus determines that the fatigue / time-dependent change is progressing,
A density adjustment process is performed (Step S5). This embodiment (and second to eleventh embodiments described later)
In the example, 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 image ) 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 at the optimum developing bias previously obtained, and the image density of the patch images is changed. Is detected by the patch sensor PS, and the optimum charging bias necessary for obtaining the target density is determined based on the detected values (image density of the patch image).

When the density adjustment processing is completed, the fatigue evaluation value is cleared, the flow returns to step S1, and the above-described series of processing (steps S2 to S5) is repeated.

On the other hand, if it is determined in step S2 that the print mode has been changed, the process immediately proceeds to step S5 to execute density adjustment processing prior to actual job execution, regardless of the fatigue evaluation value. . After clearing the fatigue evaluation value, the process returns to step S1 to wait for the next job to be sent.

As described above, according to the first embodiment, the density adjustment start condition (the fatigue evaluation value is equal to or higher than the fatigue threshold value) as usual while the print mode is not changed.
If the print mode is changed, the density adjustment process is immediately executed if the print mode is changed. Therefore, before the toner image is formed in the print mode after the change, The toner image can always be formed under good image forming conditions. That is, in this embodiment, the density adjustment start condition is changed to a condition that "the print mode has been changed" in accordance with the mode change. Also, after the first density adjustment process is performed after the mode change, the density adjustment start condition is returned to the state before the change, and the density is adjusted based on the normal density adjustment start condition (the fatigue evaluation value is equal to or more than the fatigue threshold). The execution timing of the adjustment process is controlled.

<Second Embodiment> In the first embodiment, the density adjustment processing is always performed when the print mode is changed. Therefore, even if the density adjustment processing is not necessary, if the print mode change occurs, the density adjustment processing is performed. Is executed. For example, this corresponds to a case where the mode is changed from the color print mode to the monochrome print mode. In such a case, the execution of the density adjustment processing causes a decrease in throughput.

Therefore, in the second embodiment, the above problem is solved by configuring as follows. Less than,
The second embodiment will be described in detail with reference to FIGS.

FIG. 4 is a flowchart showing a second embodiment of the image forming apparatus according to the present invention. A major difference between the second embodiment and the first embodiment is that when the print mode is changed, the density adjustment process is executed only when it is confirmed that the mode change requires the density adjustment process. The other configuration is the same as that of the first embodiment.

More specifically, as shown in FIG. 4, if it is determined in step S2 that the print mode has been changed, the flow advances to step S6 to determine the current mode based on the combination of the previous print mode and the current print mode. It is determined whether or not the change is a mode change requiring density adjustment processing. Here, “mode change requiring density adjustment processing” means that the print mode after the change needs to form a toner image with higher image quality than the print mode before the change. Various combinations are as shown in Table 1.

[0041]

[Table 1]

In the table, the "user-specified high image quality mode" is a print mode set when the user explicitly specifies the high image quality mode as the image quality. The “special paper mode” is a print mode in which printing is performed on a sheet that is more expensive than plain paper such as color-only paper or postcard.

If these print modes are arranged in the order in which high image quality is required, (user-specified high image quality mode)> (special paper mode)>
(Color mode)> (monochrome mode). Therefore, the combination indicated by a circle in each column corresponds to “mode change requiring density adjustment processing”. Also, when schematically showing these combinations,
The correspondence shown in FIG.

Returning to FIG. 4, the description will be continued.
If it is determined in step 6 that the current mode change is not a mode change requiring density adjustment processing, the process directly returns to step S1 and waits for the next job to be sent without executing density adjustment processing. Conversely, if it is determined that the current mode change is a mode change requiring density adjustment processing, the process proceeds to step S5, and regardless of the fatigue evaluation value, the density adjustment is performed prior to the actual job execution. Execute the process. After clearing the fatigue evaluation value, the process returns to step S1 to wait for the next job to be sent.

As described above, according to the second embodiment, it is determined that "the print mode after the change needs to form a toner image with higher image quality than the print mode before the change". As the adjustment start condition, it is determined whether or not the changed density adjustment start condition is satisfied based on a combination of the print modes before and after the mode change, and the density adjustment process is executed only when it is determined that the density adjustment start condition is satisfied. Therefore, it is possible to prevent unnecessary density adjustment processing from being executed and effectively prevent a decrease in throughput. Of course, if there is a “mode change requiring density adjustment processing”, no matter what the fatigue evaluation value is, the density adjustment processing is executed prior to the actual job execution, and good image forming conditions Can form a toner image.

As described above, according to the second embodiment, it is possible to control the activation of the density adjustment processing in accordance with the mode change, thereby ensuring the two effects (maintaining high image quality and high throughput) in a well-balanced manner.

After determining whether or not the density adjustment start condition is satisfied after the mode change, the density adjustment start condition is returned to the state before the change, and the normal density adjustment start condition (the fatigue evaluation value is changed to the fatigue threshold value). Based on the above, the execution timing of the density adjustment processing is controlled. This is the same in the third to eighth embodiments described later.

<Third Embodiment> In the second embodiment,
It is determined whether or not the density adjustment processing is necessary based on a combination of the print modes before and after the mode change, and the density adjustment processing is executed only when it is determined that the density adjustment processing is necessary. However, even when changing to a print mode requiring higher image quality,
Density adjustment processing may not be necessary. As an example of such a case, a case where the mode is changed from the monochrome mode to the color mode can be considered. For example, if a color print job is received immediately after executing the density adjustment processing in the monochrome mode, according to the second embodiment, the density adjustment processing is immediately executed. In this case, after the previous density adjustment processing, The accumulated fatigue and changes over time are slight, and the concentration adjustment processing is substantially unnecessary. As described above, if the density adjustment processing is performed even when unnecessary, the throughput is reduced.

Therefore, in the third embodiment, the following problem is solved by executing the density adjustment processing at a more appropriate timing by configuring as follows. Hereinafter, the third embodiment will be described in detail with reference to FIG.

FIG. 6 is a flowchart showing a third embodiment of the image forming apparatus according to the present invention. The difference between the third embodiment and the second embodiment is that, when the print mode is changed, it is confirmed that the mode change requires the density adjustment processing, and further, at the time of the mode change. The point is that the density adjustment processing is executed only when it is confirmed that the fatigue evaluation value is equal to or more than a certain value, and the other configuration is the same as that of the second embodiment.

More specifically, as shown in FIG. 6, when it is determined in step S2 that the print mode has been changed, the flow advances to step S6 to determine the current mode based on the combination of the previous print mode and the current print mode. It is determined whether or not the change is a mode change requiring density adjustment processing. If it is determined in step S6 that the current mode change is a mode change requiring density adjustment processing, the process further proceeds to step S7.

In this step S7, it is determined whether or not the fatigue evaluation value is equal to or greater than a mode change threshold value stored in the ROM 128 in advance. If it is determined as “NO” in step S7, that is, if it is determined that the fatigue evaluation value at the time of the mode change is less than the mode change threshold value and that the fatigue and the change with time have not progressed, the density adjustment processing is executed. Without returning to step S1, the process waits for the next job to be sent. Conversely, if "YES" is determined, that is, if the fatigue evaluation value at the time of the mode change is equal to or greater than the mode change threshold value and it is determined that the fatigue / time-dependent change has progressed to some extent, the process proceeds to step S5, and The density adjustment processing is executed prior to the execution of the job. After clearing the fatigue evaluation value, the process returns to step S1 to wait for the next job to be sent.

As described above, according to the third embodiment, the density adjustment start condition after the mode change is the following two conditions: condition (a): the print mode after the change is higher than the print mode before the change. (B): the fatigue evaluation value at the time of mode change must be equal to or greater than the mode change threshold value, and these conditions must be satisfied.
Since the density adjustment processing is executed only when both (a) and (b) are satisfied, it is necessary to prevent unnecessary density adjustment processing from being executed and to more effectively prevent a decrease in throughput. Can be. Of course, if there is a “mode change requiring density adjustment processing”, the density adjustment processing is executed prior to the actual job execution, and a toner image can be formed under good image forming conditions.

<Fourth Embodiment> FIG. 7 is a flowchart showing a fourth embodiment of the image forming apparatus according to the present invention. The fourth embodiment is similar to the third embodiment in that the density adjustment process is executed only when the density adjustment start condition including the two conditions (a) and (b) is satisfied. The third embodiment is common to the third embodiment in that the mode change threshold is changed according to the combination of the print modes before and after the mode change, and is largely different from the third embodiment having only a single mode change threshold. Different. The other configuration is the same as that of the third embodiment. Therefore, the features of the fourth embodiment will be described below focusing on the differences.

In the fourth embodiment, as shown in FIG. 7, when it is determined in step S2 that the print mode has been changed, the process proceeds to step S6, where the current print mode is determined based on the combination of the previous print mode and the current print mode. It is determined whether the mode change is a mode change requiring density adjustment processing. If it is determined in step S6 that the current mode change is a mode change requiring density adjustment processing, the process further proceeds to step S8.

In step S8, a value corresponding to the current mode change is read from Table 2 based on the combination of the print modes before and after the mode change, and set as a mode change threshold.

[0057]

[Table 2]

The values VA to VF in the table are independent numerical values, and correspond to a mode change threshold value corresponding to a combination of print modes before and after the mode change.

When the mode change threshold value corresponding to the mode change is thus set, it is determined whether or not the fatigue evaluation value at the time of the mode change is equal to or greater than the mode change threshold value (step S7). If it is determined as “NO” in step S7, that is, if it is determined that the fatigue evaluation value at the time of the mode change is less than the mode change threshold value and that the fatigue and the change with time have not progressed, the density adjustment processing is executed. Without returning to step S1, the process waits for the next job to be sent. Conversely, if "YES" is determined, that is, if the fatigue evaluation value at the time of the mode change is equal to or greater than the mode change threshold value and it is determined that the fatigue / time-dependent change has progressed to some extent, the process proceeds to step S5, and The density adjustment processing is executed prior to the execution of the job. After clearing the fatigue evaluation value, the process returns to step S1 to wait for the next job to be sent.

As described above, in this embodiment, since the mode change threshold is changed and set in accordance with the combination of the print modes before and after the mode change, the following operation and effect can be obtained. That is, even if the fatigue evaluation values at the time of the mode change are the same, depending on the combination of the printing modes before and after the mode change, it may be desirable to execute the density adjustment processing, or may not be desirable. . For example, when changing from the monochrome mode to the color mode, even though the fatigue evaluation value is relatively high, the density adjustment processing is not required to give priority to the throughput,
When changing from the color mode to the special paper mode, there is a case where it is desired to execute the density adjustment processing in order to give priority to image quality even if the fatigue evaluation value is relatively low. In order to satisfy such a request, the value V in the table of Table 2 is required in advance.
F (corresponding to the mode change threshold when changing from the monochrome mode to the color mode) is larger than the value VC (corresponding to the mode change threshold when changing from the color mode to the special paper mode). By setting it to a numerical value, the above requirement can be satisfied. The numerical values and the magnitude relationships of the values VA to VF in the table are arbitrary.

As described above, according to the fourth embodiment, the density adjustment start condition (b), that is, “mode change” is set by independently setting the mode change thresholds according to the combination of the print modes before and after the mode change. The condition that the fatigue evaluation value at the time is equal to or greater than the mode change threshold value "can be flexibly changed, and the density adjustment processing can be executed at a timing suitable for actual use.

<Fifth Embodiment> In the above-described first embodiment, since the density adjustment processing is always performed when the print mode is changed, the image quality after the mode change can be made high. However, even when the density adjustment processing is not necessary, if the print mode is changed, the density adjustment processing is executed. For example, this corresponds to a case where the mode is changed from the color print mode to the monochrome print mode. In such a case, the execution of the density adjustment processing causes a decrease in throughput.

Therefore, in the fifth embodiment, the above problem is solved by configuring as follows. Less than,
The fifth embodiment will be described in detail with reference to FIG.

FIG. 8 is a flowchart showing a fifth embodiment of the image forming apparatus according to the present invention. In the fifth embodiment, as shown in FIG.
1 sends job data (step S1).
Then, as in the conventional example, the number of printed sheets is integrated to obtain a fatigue evaluation value (step S3).

Subsequently, it is determined whether or not the print mode of the received job has been changed from the previous print mode (step S2). Specifically, when the color / monochrome print information, the sheet type information, or the print quality information among the print mode information of the job has changed, it is determined that the print mode has been changed. If it is determined that there is a mode change, the fatigue evaluation value is corrected (step S9), and the process proceeds to step S4. On the other hand, if it is determined in step S2 that there is no mode change, the process directly proceeds to step S4 without correcting the fatigue evaluation value.

In the next step S4, it is determined whether or not the fatigue evaluation value is equal to or greater than a fatigue threshold value previously set and stored in the ROM 128. If it is determined that the fatigue evaluation value is less than the fatigue threshold, the process returns to step S1 and waits for the next job. On the other hand, if it is determined that the fatigue evaluation value is equal to or greater than the fatigue threshold value, the density adjustment process is executed to clear the fatigue evaluation value (step S5), and then return to step S1 to send the next job. Wait for it to come.

As described above, in the fifth embodiment, when the mode is changed, the condition for starting the density adjustment is corrected by correcting the fatigue evaluation value so that the corrected fatigue evaluation value is equal to or higher than the fatigue threshold value. Has been changed. " Here, the correction method in step S9 is arbitrary. For example, when the fatigue evaluation value is doubled and the correction value is reset as the fatigue evaluation value, the fatigue evaluation value at the time of mode change is equal to the fatigue threshold value. If it is half or more, the density adjustment processing is started.
Therefore, when the print mode is changed to a print mode requiring higher-quality printing, the density adjustment processing is executed relatively frequently, and high-quality printing can be performed in the changed print mode.

Further, the fatigue evaluation value at the time of the mode change is relatively small, that is, the fatigue evaluation value in the print mode before the change.
When the degree of progress of the change with time is low, it is possible to prevent a problem that the density adjustment processing is performed unnecessarily, thereby improving the throughput.

As described above, according to the fifth embodiment, by appropriately setting the correction method in step S9, the activation of the density adjustment processing accompanying the mode change is controlled, and two effects (high image quality maintenance and high image quality are maintained). Throughput) in a well-balanced manner.

<Sixth Embodiment> FIG. 9 is a flowchart showing a sixth embodiment of the image forming apparatus according to the present invention. The sixth embodiment is common to the fifth embodiment described above in that the fatigue evaluation value is corrected when the mode is changed. However, the correction method according to the combination of the print modes before and after the mode change. Is greatly different from the fifth embodiment in which the correction method is fixed.
The other configuration is the same as that of the fifth embodiment. Therefore, the features of the sixth embodiment will be described below focusing on the differences.

In the sixth embodiment, as shown in FIG. 9, if it is determined in step S2 that the print mode has been changed, the flow advances to step S10 to perform correction based on the combination of the previous print mode and the current print mode. The coefficients are determined from Table 3.

[0072]

[Table 3]

The values KA to KF in the table are each "1" or more, and are independent numerical values, and correspond to correction coefficients corresponding to combinations of print modes before and after the mode change. Further, when the print mode requiring high image quality is changed to the print mode with lower image quality, there is no need to perform the density adjustment processing, and thus “1.0” is set as the correction coefficient.

When the correction coefficient corresponding to the mode change is set in this way, an operation of multiplying the fatigue evaluation value at the time of the mode change by the correction coefficient is performed, and the calculation result is reset as a new fatigue evaluation value. (Step S11)
Thereafter, the process proceeds to step S4.

After that, as in the fifth embodiment, only when it is determined that the fatigue evaluation value is equal to or greater than the fatigue threshold, the density adjustment processing is executed (step S).
5).

As described above, in this embodiment, the correction coefficient is obtained in accordance with the combination of the printing modes before and after the mode change, and the fatigue evaluation value is corrected based on the correction coefficient. An effect can be obtained. That is,
Even if the fatigue evaluation values at the time of the mode change are the same, depending on the combination of the printing modes before and after the mode change, it may be desirable to execute the density adjustment processing, or conversely, may not be desirable. For example, when changing from monochrome mode to color mode, even though the fatigue evaluation value is relatively high, we want to eliminate the need for density adjustment processing in order to give priority to throughput. Is relatively low, there is a case where it is desired to execute the density adjustment processing in order to give priority to image quality. In order to satisfy such a request, a value KF (corresponding to a correction coefficient when the mode is changed from the monochrome mode to the color mode) in the table of Table 3 is previously determined.
By setting the value larger than the value KC (corresponding to a correction coefficient when the mode is changed from the color mode to the special paper mode), the above requirement can be satisfied. Note that the values and the magnitude relationships of the values KA to KF in the table are arbitrary.

As described above, according to the sixth embodiment, the density adjustment processing is executed at a timing suitable for actual use by independently setting the correction coefficients in accordance with the combination of the print modes before and after the mode change. Can be.

In this embodiment, the correction coefficient when the print mode requiring high image quality is changed to the print mode with lower image quality is set to "1.0". You may. In this case, even if a relatively large amount of fatigue / temporal change is accumulated in the print mode before the change and the fatigue evaluation value approaches the fatigue threshold, it is reset to a small value by the correction process after the mode change (step S11). Will be set. As a result, the start timing of the density adjustment processing in the changed print mode, that is, the print mode of low image quality is delayed, thereby contributing to the improvement of the throughput.

<Seventh Embodiment> In the above-described first embodiment, since the density adjustment processing is always performed when the print mode is changed, the image quality after the mode change can be made high. However, even when the density adjustment processing is not necessary, if the print mode is changed, the density adjustment processing is executed. For example, this corresponds to a case where the mode is changed from the color print mode to the monochrome print mode. In such a case, the execution of the density adjustment processing causes a decrease in throughput.

Therefore, in the seventh embodiment, the above problem is solved by configuring as follows. Less than,
The seventh embodiment will be described in detail with reference to FIG.

FIG. 10 is a flowchart showing a seventh embodiment of the image forming apparatus according to the present invention. This seventh
In the embodiment, as shown in the figure, job data is sent from the main controller 11 (step S1).
Then, as in the conventional example, the number of printed sheets is integrated to obtain a fatigue evaluation value (step S3).

Subsequently, it is determined whether or not the print mode of the received job has been changed from the previous print mode (step S2). Specifically, when the color / monochrome print information, the sheet type information, or the print quality information among the print mode information of the job has changed, it is determined that the print mode has been changed. If it is determined that there is no mode change, it is confirmed that the fatigue evaluation value is equal to or greater than the fatigue threshold (step S4).
A density adjustment process is performed (Step S5).

On the other hand, if it is determined in step S2 that there is a mode change, step S7 is executed instead of step S4. That is, in this step S7, it is determined whether or not the fatigue evaluation value is equal to or more than the mode change threshold value stored in the ROM 128 in advance. If it is determined as “NO” in step S7, that is, if it is determined that the fatigue evaluation value at the time of the mode change is less than the mode change threshold value and that the fatigue and the change with time have not progressed, the density adjustment processing is executed. Step S1 without any change
Return to and wait for the next job to be sent. vice versa,
If "YES" is determined, that is, if the fatigue evaluation value at the time of the mode change is equal to or more than the mode change threshold value and it is determined that the fatigue / time-dependent change has progressed to some extent, step S5
The density adjustment process is executed prior to the actual job execution. After clearing the fatigue evaluation value, the process returns to step S1 to wait for the next job to be sent.

As described above, in the seventh embodiment, when the mode is changed, the condition for starting the density adjustment is changed from the condition that the fatigue evaluation value is equal to or more than the fatigue threshold value to the condition that the fatigue evaluation value is It must be greater than or equal to the mode change threshold ", and it is determined whether or not the density adjustment start condition after the change is satisfied. Such effects can be obtained. For example, if the mode change threshold is set to half of the fatigue threshold, it is assumed that the fatigue / time change has progressed only to the extent that the fatigue evaluation value at the time of mode change exceeds half of the fatigue threshold. Also, in the present embodiment, the density adjustment processing is started by the mode change. Therefore, when the print mode is changed to a print mode requiring higher-quality printing, the density adjustment processing is executed relatively frequently, and high-quality printing can be performed in the changed print mode.

<Eighth Embodiment> FIG. 11 is a flowchart showing an eighth embodiment of the image forming apparatus according to the present invention. In the eighth embodiment, similarly to the above-described seventh embodiment, there is a mode change, and the density adjustment start condition of “the fatigue evaluation value is equal to or more than the mode change threshold” is satisfied. In this case, the fourth embodiment is similar to the seventh embodiment in that the density adjustment processing is executed prior to the first image forming processing in the print mode after the mode change, but the mode is changed according to the combination of the print modes before and after the mode change. The point that the threshold value is changed is significantly different from the seventh embodiment having only a single mode change threshold value. The other configuration is the same as that of the seventh embodiment. Therefore, the features of the eighth embodiment will be described below focusing on the differences.

In the eighth embodiment, as shown in FIG. 11, if it is determined in step S2 that the print mode has been changed, the flow advances to step S12 to execute the current print mode based on the combination of the previous print mode and the current print mode. Is read from Table 4 and set as a mode change threshold.

[0087]

[Table 4]

The values TA to TF in the table are independent numerical values, and correspond to a mode change threshold value corresponding to a combination of print modes before and after the mode change.

When the mode change threshold value corresponding to the mode change is thus set, it is determined whether or not the fatigue evaluation value at the time of the mode change is equal to or more than the mode change threshold value (step S7). If it is determined as “NO” in step S7, that is, if it is determined that the fatigue evaluation value at the time of the mode change is less than the mode change threshold value and that the fatigue and the change with time have not progressed, the density adjustment processing is executed. Without returning to step S1, the process waits for the next job to be sent. Conversely, if "YES" is determined, that is, if the fatigue evaluation value at the time of the mode change is equal to or greater than the mode change threshold value and it is determined that the fatigue / time-dependent change has progressed to some extent, the process proceeds to step S5, and The density adjustment processing is executed prior to the execution of the job. After clearing the fatigue evaluation value, the process returns to step S1 to wait for the next job to be sent.

As described above, in this embodiment, since the mode change threshold is changed and set in accordance with the combination of the print modes before and after the mode change, the following operation and effect can be obtained. That is, even if the fatigue evaluation values at the time of the mode change are the same, depending on the combination of the printing modes before and after the mode change, it may be desirable to execute the density adjustment processing, or may not be desirable. . For example, when changing from the monochrome mode to the color mode, even though the fatigue evaluation value is relatively high, the density adjustment processing is not required to give priority to the throughput,
When changing from the color mode to the special paper mode, there is a case where it is desired to execute the density adjustment processing in order to give priority to image quality even if the fatigue evaluation value is relatively low. In order to satisfy such a request, the value T in the table of Table 4 must be set in advance.
F (corresponding to the mode change threshold value when changing from the monochrome mode to the color mode) is larger than the value TC (corresponding to the mode change threshold value when changing from the color mode to the special paper mode). By setting it to a numerical value, the above requirement can be satisfied. Note that the values TA to TF in the table and the magnitude relation are arbitrary.

As described above, according to the eighth embodiment, the density adjustment start condition (b), that is, the “mode change” is set by independently setting the mode change thresholds according to the combination of the print modes before and after the mode change. The condition that the fatigue evaluation value at the time is equal to or greater than the mode change threshold value "can be flexibly changed, and the density adjustment processing can be executed at a timing suitable for actual use.

<Ninth Embodiment> The above-described first to eighth embodiments
In the embodiment, after determining whether or not the changed density adjustment start condition is satisfied at the time of the mode change, the density adjustment start condition is returned to the state before the change, but as described in the ninth and tenth embodiments. After the print mode is changed to the print mode, the execution timing of the density adjustment processing may be controlled based on the density adjustment start condition after the change until the print mode is changed next. Hereinafter, the image forming apparatuses according to the ninth and tenth embodiments will be sequentially described.

FIG. 12 is a flowchart showing a ninth embodiment of the image forming apparatus according to the present invention. This ninth
In the embodiment, as shown in the figure, job data is sent from the main controller 11 (step S1).
Then, as in the conventional example, the number of printed sheets is integrated to obtain a fatigue evaluation value (step S3).

Subsequently, it is determined whether the print mode of the received job has been changed from the previous print mode (step S2). Specifically, when the color / monochrome print information, the sheet type information, or the print quality information among the print mode information of the job has changed, it is determined that the print mode has been changed. If it is determined that there is a mode change, the fatigue threshold is changed to a value corresponding to the changed print mode (step S13).
Thereafter, the process proceeds to step S4. On the other hand, if it is determined in step S2 that there is no mode change, the process directly proceeds to step S4 without changing the fatigue threshold.

In the next step S4, it is determined whether or not the fatigue evaluation value is equal to or greater than the fatigue threshold. If it is determined that the fatigue evaluation value is less than the fatigue threshold, the process returns to step S1 and waits for the next job. On the other hand, if it is determined that the fatigue evaluation value is equal to or greater than the fatigue threshold value, the density adjustment process is executed to clear the fatigue evaluation value (step S5), and then return to step S1 to send the next job. Wait for it to come.

As described above, in the ninth embodiment, when the mode is changed, the condition for starting the density adjustment is changed by changing the fatigue threshold value according to the changed print mode. Until the print mode is changed, the execution timing of the density adjustment processing is controlled based on the density adjustment start condition (the fatigue evaluation value is equal to or more than the fatigue threshold value corresponding to the changed print mode). Therefore, in each print mode, the density adjustment processing can be executed at a timing suitable for the print mode. For example, in a monochrome mode in which strict density adjustment is not required, by setting a relatively large fatigue threshold, the frequency of execution of density adjustment processing can be suppressed, and throughput can be improved. On the other hand, in the special paper mode and the high image quality mode, the image quality is prioritized. Therefore, by setting the fatigue threshold to a relatively small value, the frequency of the density adjustment processing is increased and the high quality print output is obtained. Obtainable.

<Tenth Embodiment> FIG. 13 is a flowchart showing a tenth embodiment of the image forming apparatus according to the present invention. The tenth embodiment is significantly different from the ninth embodiment in that the density adjustment start condition is changed by changing the fatigue threshold value according to the print mode in the ninth embodiment. In the present embodiment, however, the condition for starting the density adjustment is changed by correcting the fatigue evaluation value according to the print mode. The other configuration is the same as that of the ninth embodiment. Therefore, the following description focuses on the differences.

In this embodiment, after obtaining the fatigue evaluation value in step S3, it is determined whether or not the print mode of the accepted job has been changed from the previous print mode (step S2). If it is determined that there is no mode change, the process proceeds to step S14 with the correction coefficient corresponding to the print mode, and an operation of multiplying the fatigue evaluation value obtained in step S3 by the correction coefficient is performed. The calculation result is reset as a new fatigue evaluation value (step S
14). Subsequently, it is determined whether or not the fatigue evaluation value is equal to or greater than the fatigue threshold (step S4). Here, when it is determined that the fatigue evaluation value is less than the fatigue threshold,
The process directly returns to step S1 and waits for the next job to be sent. On the other hand, if it is determined that the fatigue evaluation value is equal to or greater than the fatigue threshold value, the density adjustment process is executed to clear the fatigue evaluation value (step S5), and then return to step S1 to send the next job. Wait for it to come.

On the other hand, if it is determined in step S2 that there is a mode change, step S15 is executed prior to step S14 to change the correction coefficient to a value corresponding to the changed print mode. Thereafter, the process proceeds to step S14, in which the fatigue evaluation value is corrected in the same manner as in the case where there is no mode change, and the density adjustment process is executed only when the corrected fatigue evaluation value is equal to or greater than the fatigue threshold value (step S14). S
5).

As described above, in the tenth embodiment,
When the mode is changed, the density adjustment start condition is changed by changing the correction coefficient according to the changed print mode, and the density adjustment start condition (after correction) is changed until the next print mode is changed. (The fatigue evaluation value is equal to or greater than the fatigue threshold value), the execution timing of the density adjustment processing is controlled. Therefore, in each print mode, the density adjustment processing can be executed at a timing suitable for the print mode. For example, in a monochrome mode in which strict density adjustment is not required, by setting the correction coefficient to a relatively small value, the frequency of execution of the density adjustment processing can be suppressed and the throughput can be improved. On the other hand, in the special paper mode and the high image quality mode, since the image quality is prioritized, setting the correction coefficient to a relatively large value increases the execution frequency of the density adjustment processing, thereby achieving high quality print output. Obtainable.

<Eleventh Embodiment> FIG. 14 is a flowchart showing an eleventh embodiment of the image forming apparatus according to the present invention. The eleventh embodiment differs greatly from the tenth 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 the detection sensor The point is that the CPU 123 receives the output signal and corrects the fatigue threshold value according to the temperature and humidity inside the apparatus. The other configurations are the same.

In the ninth embodiment, as shown in the figure, when job data is sent from the main controller 11 (step S1), the number of printed sheets is integrated to obtain a fatigue evaluation value as in the conventional example. (Step S3). Then, in the subsequent step S16, the temperature and humidity inside the apparatus at the time when the job data is received are measured by the detection sensor. Then, the fatigue threshold is corrected based on the measurement result. For example, the relationship between the temperature / humidity and the correction coefficient is checked in advance, the relation table is stored in the ROM 128, and the temperature correction coefficient corresponding to the measurement result is stored in the RO 128.
M128 may be read to correct the fatigue threshold. Further, instead of the relation table, a relational expression between the temperature / humidity and the correction coefficient may be used. A major reason for correcting the fatigue threshold based on the temperature and humidity in this way is that the photoreceptor 2 depends on its surrounding temperature and surrounding humidity.
This is because the degree of progress of fatigue of each unit of the apparatus such as the developing unit 1 and the developing unit 23 is different. As in this embodiment, by correcting the fatigue threshold value based on the temperature and humidity, the density adjustment start condition is adjusted corresponding to the temperature and humidity, and the density adjustment process is executed at a more accurate timing. It becomes possible.

When the optimization of the density adjustment start condition is completed, the execution timing of the density adjustment process is controlled by determining whether or not the density adjustment start condition is satisfied, as in the tenth embodiment. . Step S2
Subsequent operations are the same as in the tenth embodiment, and a description thereof will not be repeated.

In this embodiment, the fatigue threshold value is corrected based on the temperature and humidity in order to adapt the concentration adjustment start condition to the temperature and humidity. However, the fatigue evaluation value is corrected. Is also good. In addition, the temperature inside the device
The fact that the fatigue threshold value or the fatigue evaluation value is corrected according to the humidity and the concentration adjustment start condition is adapted to the temperature and the humidity is also applicable to the first to ninth embodiments described above.

Further, 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 when the correction is made based on the temperature and humidity can be obtained.
However, in order to more accurately determine fatigue and changes over time,
It is desirable to make correction based on both temperature and humidity inside the device.

<Others> The present invention is not limited to the above-described embodiments, and various changes other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, a value obtained by integrating the number of printed sheets as in the conventional example is used as the fatigue evaluation value indicating the degree of progress of the fatigue and the change with time of each part of the apparatus, but the fatigue evaluation value is not limited to this. Instead, the operation time of the apparatus may be used as the fatigue evaluation value. In addition, a photoconductor or a transfer medium (intermediate transfer belt 41 in this embodiment) described below.
The fatigue evaluation value may be obtained based on the rotation amount of the developing device, the number of contact / disengagement of the developing device, and the job count value.
In this case, an advantageous effect can be obtained as compared with the case where the fatigue evaluation value is obtained based on the number of printed sheets. Hereinafter, each will be described separately.

<< Rotation Amount of Photoconductor >> When calculating a fatigue evaluation value based on the number of printed sheets, the operation of each unit such as a photoconductor and a developing device differs between color printing and monochrome printing. Is calculated based on the number of printed sheets, it may not be possible to accurately indicate the fatigue and the change over time of each part of the apparatus. For example, even when printing one sheet, in the color print mode, yellow, cyan,
It is necessary to form magenta and black toner images on the photoreceptor, respectively, and to overlay the respective toner images on the intermediate transfer medium. On the other hand, in the monochrome print mode, the toner image formed on the photoconductor is only one type of black toner image. For this reason, 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. For this reason, even if the number of printed sheets is the same, the fatigue and changes over time of the photoreceptor and the like in color printing are inevitably greater than those in monochrome printing.

In the double-sided printing mode, the photoconductor 21 and the intermediate transfer belt 41 may be idle. However, each part of the apparatus is operating even during the idle processing, and the fatigue and temporal change due to the operation 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, a predetermined initial operation is performed while the photoconductor, the intermediate transfer belt 41, and the like run idle. 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, in order to accurately obtain the degree of progress of fatigue and change with time, it is necessary to consider this effect.

However, in the calculation of the fatigue evaluation value based on the number of prints, such points are not taken into account at all, so that it is not possible to accurately show the fatigue and the change over time of each part of the apparatus.

On the other hand, for example, immediately after the apparatus power is turned on, the pulse-shaped vertical synchronizing signal VSYNC is counted from the vertical synchronizing reading sensor RS, and the rotation count value of the intermediate transfer belt 41 is integrated. As an evaluation value,
The above problem can be solved. In other words, even if one sheet of print processing is performed, the rotation amount of the intermediate transfer belt 41 is one revolution in monochrome printing, whereas the rotation amount of the intermediate transfer belt 41 is one rotation in color printing. The amount of rotation is four revolutions, and it depends on the degree of fatigue and the change with time of the photoconductor 21 and the developing unit 23. Therefore, even if color printing and monochrome printing are mixed, the degree of progress of the fatigue and time-dependent change of each part of the apparatus can be accurately indicated by the fatigue evaluation value.

In this case, since the integration of the amount of rotation is started immediately after the power supply to the apparatus is turned on, the following operation and effect can be obtained. When the power of the apparatus is turned on, the warm-up is started, and each section of the apparatus operates independently of the actual printing. This is one of the causes of fatigue and aging of each section of the apparatus. In this embodiment, the rotation amount (rotation count value) of the intermediate transfer belt 41 during the warming-up is added to the fatigue evaluation value. It is possible to accurately estimate the fatigue and the change over time of each part of the apparatus.

Also, during periods other than warm-up and when 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, even during the idling, the rotation amount (rotation count value) of the intermediate transfer belt 41 is integrated into the fatigue evaluation value. The evaluation value can be obtained, and the fatigue / time-dependent change of each part of the apparatus can be accurately estimated.

Here, the fatigue evaluation value is obtained based on the rotation amount (rotation count value) of the intermediate transfer belt 41. However, the fatigue evaluation value is obtained based on only the rotation amount of the photoconductor 21 or both rotation amounts. You may do so.

Further, the fatigue evaluation value may be obtained by integrating the rotation count value only while the toner image is being created. In this case, image forming means for forming a toner image in each part of the apparatus, that is, fatigue of a process unit including the image carrier unit 2 and the exposure unit 3 is reduced.
The fatigue evaluation value corresponding to the temporal change can be obtained, and the fatigue / temporal change of the image forming means can be accurately estimated.

<< Number of Separation and Contact of Developing Unit >> The number of separation and contact of the developing unit (separation contact count value) may be integrated to obtain the fatigue evaluation value. The reason will be described in detail below. When the developing process is performed, the four developing devices 23Y and 23
Any one of 3C, 23M, and 23K contacts the photoconductor 21, but in the case of color printing, four developing units 23Y, 23K
Since C, 23M, and 23K are sequentially switched, each time the developing device is switched, the contact / contact count value is incremented by "1" and the fatigue evaluation value is counted up. On the other hand, in monochrome printing, only the black developing device 23K comes into contact with and separates from each other, and the other developing devices 23Y, 23C, and 23M are in a stopped state. This is 1/4 that of color printing.
Therefore, the contact / contact count value of the developing device reflects the color / monochrome print information.

Therefore, when integrating the number of printed sheets, the four developing units 23Y, 23C, 23M, 2
Although 3K is activated and the photoconductor 21 is activated correspondingly, it is determined that the same fatigue and change over time occurs as in the case of monochrome printing in which only one developing device is activated. Had a lack of validity. In contrast, when the fatigue evaluation value obtained by integrating the contact and contact count values is used, even if such a problem is solved and color printing and monochrome printing are mixed,
The fatigue evaluation value can accurately indicate the degree of progress of the fatigue / time-dependent change of each part of the apparatus.

<< Job Count >> In this type of image forming apparatus, an image forming process, a transfer process, and the like are executed based on job data given from the main controller 11, and the job data includes a print size (paper size). Print mode information such as (size), color / monochrome, single-sided / double-sided, and the like. For this reason, even in the case of performing one printing, if the printing mode is different, the ratio of the fatigue and the change over time of the photoconductor and the developing unit due to the printing process is different.

This will be specifically described. For example, consider the case of printing four postcard sizes simultaneously. Here, when the fatigue evaluation value is obtained by accumulating the number of printed sheets, even though the image forming operation is performed once, four images are counted. It was decided that it was obviously invalid.

When monochrome printing is performed, the photosensitive member 2
In contrast to forming only a black toner image on the photoconductor 1 and operating only the black developing device 23K, when performing color printing, yellow, cyan, magenta and black toner images are sequentially formed on the photoconductor 21. Therefore, the number of operations of the photoconductor 21 is four times that of monochrome printing, and the yellow, cyan, and magenta developing units 23Y, 23C, and 23M also operate in addition to the black developing unit 23K. Therefore, the degree of progress of the fatigue and the change over time of the photoconductor 21 and the developing units 23Y, 23C, 23M, and 23K changes depending on whether the printing mode is the color / monochrome printing mode.

Further, in the case of double-sided printing, the final number of sheets is one, but since an image is formed on both sides, the image forming operation is doubled as compared with the single-sided printing, and the fatigue and time-dependent change of each part of the apparatus. Advances more greatly than in the case of single-sided printing. In addition, double-sided printing does not mean simply performing single-sided printing twice, but may perform idling processing as necessary for reversal conveyance of a sheet. In such an idling process, a part of the engine unit E (the photoreceptor 21 and the like) is driven, causing friction and the like, which causes fatigue and changes over time.

Therefore, by calculating the fatigue evaluation value by integrating the weighted count values weighted based on the print mode information included in the job, the degree of progress of the fatigue and the change over time of each part of the apparatus is accurately reflected. Fatigue evaluation value can be obtained. Specifically, a weighting table as shown in Table 5 is stored in the ROM 128 in advance,
When each job is received, a weighted count value is obtained by referring to the table, and a fatigue evaluation value can be obtained by integrating the weighted count value.

[0122]

[Table 5]

In the table, "image forming unit" means the number of output media that can be subjected to collective image forming processing in the image forming apparatus when printing at a designated size.

Further, "development C", "development M", "development Y", and "development K" correspond to developing units 23C, 23M, 2 respectively.
The values correspond to the operations of 3Y and 23K. In the case of color printing, all “development C”, “development M”, “development Y”, and “development K” are “1”. In the case of monochrome printing, “development K” becomes “1” and the remaining developing units 2
3C, 23M, and 23Y are set to “0”. “OPC” is a value corresponding to the operation of the photoconductor 21, and the number of operations of the photoconductor 21 in color printing is four times that in monochrome printing as described above. On the other hand, in monochrome printing, “1” is set. As described above, in the second embodiment, “development C”, “development M”,
The values of “development Y”, “development K” and “OPC” are set.

Further, the values shown in “double-sided coefficient” and “double-sided blanking” in the table are set in consideration of the influence of the difference between the single-sided / double-sided printing modes on the fatigue and the change over time. That is, in one-sided printing, the “double-sided coefficient” is set to “1” to print on only one side, and the idling process is essentially unnecessary.
Is set to In contrast, double-sided printing requires printing on both sides of the sheet and requires idle processing.
“2” for “double-sided coefficient” and “2”
It is set to “1”.

Then, the "image forming unit", "development C", "development M", "development Y", "development K", "OP"
C ”,“ double-sided coefficient ”and“ double-sided blank ”are calculated by the following equation (weighted count value) = (total value of all developing devices + OP)
C) × (double-sided coefficient) × (image formation unit) + (double-sided blanking), and the calculation result is used as a weighted count value. For reference, the number of sheets when each job is executed is also shown in the table.

The values shown in the respective columns are merely examples, and it goes without saying that the present invention is not limited to these values. Also, of the print mode information included in the job, “image forming unit”, “color / monochrome print information (values of“ development C ”,“ development M ”,“ development Y ”,“ development K ”,“ OPC ”) "And" one side /
The weight count value may be set based on one or more of the two-sided printing information (“two-sided coefficient”, “two-sided blank”).

Incidentally, 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. In all of the above-described embodiments, the concentration adjustment processing is performed when the fatigue evaluation value is equal to or greater than the fatigue threshold value. However, the progress of fatigue may be notified by a display, a lamp, or the like to notify an operator or the like. Good.

Further, the image forming apparatus according to the above embodiment prints 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.

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.

[0131]

As described above, according to the present invention, the density adjustment start condition is changed in accordance with the change of the print mode. Therefore, the density adjustment is performed at a timing suitable for the changed print mode. Processing can be performed.

Here, if it is determined whether or not the density adjustment start condition after the change is satisfied at the time of mode change, the density adjustment start condition is returned to the state before the change. The density adjustment process is performed prior to forming a toner image on the photoreceptor in the print mode, and a toner image can be formed under favorable image forming conditions after the mode is changed.

After the print mode is changed to another print mode, the execution timing of the density adjustment processing is controlled based on the density adjustment start condition after the change until the next print mode is changed. In each print mode, the density adjustment processing can be executed at a timing suitable for the print mode.

[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 diagram schematically illustrating a mode change pattern in which it is desirable to execute a density adjustment process at the time of mode change.

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

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

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

FIG. 9 is a flowchart illustrating a sixth embodiment of the image forming apparatus according to the present invention;

FIG. 10 is a flowchart illustrating a seventh embodiment of the image forming apparatus according to the present invention;

FIG. 11 is a flowchart illustrating an eighth embodiment of the image forming apparatus according to the present invention.

FIG. 12 is a flowchart illustrating a ninth embodiment of the image forming apparatus according to the present invention;

FIG. 13 is a flowchart illustrating a tenth embodiment of the image forming apparatus according to the present invention.

FIG. 14 is a flowchart illustrating an eleventh 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 (20)

[Claims] A plurality of print modes different from each other, wherein an electrostatic latent image is formed on the surface of a photosensitive member in a print mode corresponding to an image forming command given from outside the apparatus, among the plurality of print modes; An image forming apparatus that develops the electrostatic latent image with toner by a developing unit to form a toner image, and further transfers the toner image directly or via a transfer medium to a sheet; If the density adjustment start condition, which is the start condition of the density adjustment process, is satisfied during the execution of the image forming and transfer processes, the density adjustment process is started to adjust the image density of the toner image to the target density. An image forming apparatus, wherein when the print mode is changed to another print mode, the control unit changes the density adjustment start condition in accordance with the mode change. 2. The image forming apparatus according to claim 1, wherein the control unit determines whether or not the changed density adjustment start condition is satisfied at the time of the mode change, and then returns the density adjustment start condition to the state before the change. . 3. A density adjustment process is executed prior to a first image forming process in another print mode, wherein a change in a print mode is set as a density adjustment start condition after the mode change. Image forming apparatus. 4. The density adjustment start condition after the mode change is that the image quality required for the print mode after the change is higher than the image quality required for the print mode before the change. Image forming apparatus. 5. The control means stores a predetermined mode change threshold value in advance, and a fatigue evaluation value indicating a degree of progress of fatigue and time-dependent change of each part of the apparatus is equal to or greater than the mode change threshold value. 5. The condition for starting the density adjustment after the mode is changed.
The image forming apparatus as described in the above. 6. The image forming apparatus according to claim 5, wherein the control unit changes the mode change threshold according to a combination of a print mode before the change and a print mode after the change. 7. The control means stores a predetermined fatigue threshold value in advance, and corrects a fatigue evaluation value indicating a degree of progress of fatigue / time-dependent change of each part of the apparatus in accordance with a mode change, and after the correction, 3. The image forming apparatus according to claim 2, wherein the condition that the fatigue evaluation value becomes equal to or more than the fatigue threshold value is set as the density adjustment start condition after the mode change. 8. The image forming apparatus according to claim 7, wherein the control unit changes the correction amount of the fatigue evaluation value according to a combination of the print mode before the change and the print mode after the change. 9. The control means, after being changed to the another print mode, changes the execution timing of the density adjustment processing based on the density adjustment start condition after the change until the next print mode is changed. The image forming apparatus according to claim 1, wherein the control is performed. 10. The control means stores a predetermined fatigue threshold value in advance, and corrects a fatigue evaluation value indicating a degree of progress of fatigue and time-dependent change of each part of the apparatus in accordance with a mode change. The image forming apparatus according to claim 9, wherein the condition that the fatigue evaluation value of the image is equal to or more than the fatigue threshold value is set as the density adjustment start condition after the mode change. 11. The control unit obtains a fatigue threshold value corresponding to the changed print mode, wherein a fatigue evaluation value indicating a degree of progress of fatigue and time-dependent change of each part of the apparatus is equal to or greater than the fatigue threshold value. The image forming apparatus according to claim 9, wherein the condition is that the density adjustment is started after the mode change. 12. The image forming apparatus according to claim 5, wherein the control unit sets a value obtained by integrating the number of printed sheets as the fatigue evaluation value. 13. The control unit converts the image forming command into one or a plurality of jobs suitable for the operation of each unit of the apparatus, and sequentially controls the operation of each unit of the apparatus according to each job. 12. The image forming apparatus according to claim 5, wherein a value obtained by integrating weighted count values weighted based on included print mode information is used as the fatigue evaluation value. 14. The developing means comprises a plurality of developing devices,
Each developing device can form a toner image of a different color on the photoconductor, and the control means counts the number of separation / contact between the developing device and the photoconductor, and calculates the integrated value as the fatigue value. Claims 5 and 7, which are evaluation values.
12. The image forming apparatus according to 8, 10, or 11. 15. The developing means comprises a plurality of developing devices,
A black toner image is formed on the photoconductor by one of the plurality of developing devices, and a chromatic toner image can be formed on the photoconductor by the remaining developing devices. 12. The image forming apparatus according to claim 5, wherein the control unit counts the number of contact and contact of the remaining developing units with the photoconductor, and uses an integrated value thereof as the fatigue evaluation value. 16. The transfer medium is configured to rotate in synchronization with the photoconductor, and the control unit calculates a value obtained by integrating a rotation amount of at least one of the photoconductor and the transfer medium. 12. The image forming apparatus according to claim 5, wherein the evaluation value is a fatigue evaluation value. 17. The apparatus further comprising detection means for detecting at least one of temperature and humidity inside the apparatus, wherein the control means corrects the fatigue evaluation value or the fatigue threshold based on a detection result by the detection means. 17. The image forming apparatus according to claim 1, wherein the condition for starting the density adjustment is adapted to the environment inside the apparatus. 18. A printing apparatus according to claim 1, wherein a plurality of printing modes different from each other are provided, and a toner image is formed in a printing mode corresponding to an image forming command given from outside the apparatus, among said plurality of printing modes. When the predetermined density adjustment start condition is satisfied, the density adjustment process is started, and in the image forming method for adjusting the image density of the toner image to the target density, when the print mode is changed to another print mode, An image forming method, wherein the density adjustment start condition is changed according to a mode change. 19. The image forming method according to claim 18, wherein after determining whether or not the changed density adjustment start condition is satisfied at the time of mode change, the density adjustment start condition is returned to the value before the change. 20. After the print mode is changed to another print mode, the execution timing of the density adjustment processing is controlled based on the density adjustment start condition after the change until the next print mode is changed. The image forming method as described in the above.