JP2002082578A - Image forming method and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method and image forming device, in which the life of a photoreceptor, which matches individual's use condition, can accurately be predicted. SOLUTION: The image forming device forms a latent image by exposing the electrified photoreceptor 51 and forms an image while making corrections by means of a CPU 10 so that a difference between electrification potential and exposure potential of the surface of the photoreceptor is constant. In the image forming device, the CPU 10 composes a correction quantity computing means for computing correction quantity of electrification potential and correction quantity of exposure potential, and a replacement time predictive means for predicting the replacement time of the photoreceptor from the quantities of the corrections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and an image forming apparatus for forming an image using a photoreceptor, and more particularly, to an image forming method and an image forming apparatus capable of accurately predicting the life of a photoreceptor. .

[0002]

2. Description of the Related Art An original is read by an optical system, image data obtained by reading is formed on a photosensitive member by an electrophotographic method, and then transferred to a recording medium. The image-formed recording medium is fixed to the outside of the machine. There is an image forming apparatus (copier) for discharging.

Further, image data from an external image processing apparatus is received, the image data is transferred to a recording medium by an electrophotographic method to form an image, and the recording medium on which the image is formed is fixed and discharged outside the apparatus. Image forming apparatuses (printers) exist.

[0004]

In this type of image forming apparatus, the life of the photoreceptor exists, and it is necessary to periodically replace the photoreceptor. In this case, the life of the photoconductor is caused by abrasion of the photosensitive layer due to friction with the cleaning blade, rubbing of the developer in the nip, and fatigue of the photosensitive layer due to repeated charging and discharging. The rotation speed of the photoreceptor also changes depending on the number of prints for which image formation is performed at a time, so that the life differs depending on the method of use.

For example, assuming that the photosensitive layer of a certain model has an initial thickness of 23.5 ± 1.5 μm,
μm is an allowable range, and a life of less than 15 μm can be determined. In order to satisfy this under all use conditions, the exchange cycle needs to be 100,000 prints. But,
Under conditions where the environment is stable in a general office, 100,000 prints may be replaced in half the actual life.

[0006] Further, when one image is repeatedly formed, the photoreceptor is preliminarily rotated every time, and the photoreceptor drum wears more than the actual number of prints as compared with the case of forming a large number of images. It becomes intense. As described above, the life due to the wear of the photoreceptor varies depending on the individual use conditions.

However, until now, no method has been established for measuring or estimating the accurate life of the photoreceptor in accordance with individual use conditions. Therefore, in general, the photoconductor is set to be exchanged according to the number of prints according to the worst condition. Therefore, the replacement may be performed even though the life is actually left.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an image forming method and an image forming apparatus capable of predicting an accurate life of a photoconductor in accordance with each use situation. The purpose is to:

[0009]

That is, the present invention for solving the above-mentioned problems is as follows. (1) According to the first aspect of the present invention, a latent image is formed by exposing a charged photoreceptor, and correction is performed so that a difference between a charged potential on the photoreceptor surface and an exposed potential after exposure is constant. A correction amount of a charging potential and a correction amount of an exposure potential, and predicting a photoconductor replacement time from the correction amount. .

According to a ninth aspect of the present invention, a latent image is formed by exposing a charged photoreceptor, and the difference between the charged potential of the photoreceptor surface and the exposed exposure potential becomes constant. An image forming apparatus for forming an image while correcting an amount of charge, a correction amount calculating means for obtaining a correction amount of a charging potential and a correction amount of an exposure potential, and a replacement time prediction for predicting a replacement time of a photoconductor from the correction amount. And an image forming apparatus.

According to these inventions, when forming an image while correcting the difference between the charged potential of the photoreceptor surface and the exposed potential after exposure, the correction amount of the charged potential and the correction of the exposure potential The characteristic of the amount is obtained, and the replacement time of the photoconductor is predicted from the characteristic of the correction amount.

For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation. (2) The invention according to claim 2 is an image forming method for forming an image by exposing a charged photoconductor to form a latent image, wherein a driving distance or a driving time of the photoconductor is obtained.
An image forming method is characterized in that a photoconductor replacement time is predicted from the driving distance or the driving time.

According to a tenth aspect of the present invention, there is provided an image forming apparatus for forming an image by exposing a charged photoreceptor to form a latent image, wherein a driving distance or a driving time of the photoreceptor is obtained. An image forming apparatus comprising: a measuring unit; and a replacement time predicting unit that predicts a replacement time of a photoconductor from the driving distance or the driving time.

In these inventions, the drive distance or drive time of the photoconductor is determined, and the replacement time of the photoconductor is predicted from the drive distance or drive time. For this reason,
It is possible to predict an accurate life from the deterioration characteristics of the photoconductor in accordance with each use situation.

(3) The invention according to claim 3 is an image forming method for forming an image by exposing a charged photoreceptor to form a latent image, wherein the charging time for the photoreceptor by the charging means is reduced. And determining a replacement time of the photosensitive member from the charging time.

An eleventh aspect of the present invention is an image forming apparatus for forming an image by exposing a charged photoreceptor to form a latent image, wherein a charging time for the photoreceptor by a charging unit is obtained. An image forming apparatus comprising: a measuring unit; and a replacement time predicting unit that predicts a replacement time of a photoconductor from the charging time.

In these inventions, the charging time of the photoconductor is determined, and the replacement time of the photoconductor is predicted from the charging time. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(4) The invention according to claim 4 is an image forming method for forming an image by exposing a charged photoreceptor to form a latent image, wherein a driving distance of a developing roller in a developing means is provided. Alternatively, an image forming method is characterized in that a drive time is obtained, and a photoconductor replacement time is predicted from the drive distance or the drive time.

According to a twelfth aspect of the present invention, there is provided an image forming apparatus for forming an image by exposing a charged photoreceptor to form a latent image. An image forming apparatus comprising: a measuring unit that calculates a driving time; and a replacement time prediction unit that predicts a replacement time of a photoconductor from the driving distance or the driving time.

In these inventions, the drive time or drive distance of the developing roller is obtained to predict the time for replacing the photosensitive member. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

According to a fifth aspect of the present invention, there is provided an image forming method for forming an image by exposing a charged photoreceptor to form a latent image. The image forming method is characterized in that a replacement time of the photosensitive member is estimated from the charge elimination time.

According to a thirteenth aspect of the present invention, there is provided an image forming apparatus for forming an image by exposing a charged photoreceptor to form a latent image, wherein a charge elimination time for the photoreceptor by the charge eliminating means is obtained. An image forming apparatus comprising: a measuring unit; and a replacement time predicting unit configured to predict a replacement time of a photoconductor from the charge elimination time.

In these inventions, the time for exchanging the photosensitive member is predicted by calculating the charge elimination time. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(6) The image according to any one of claims 1 to 5, wherein the prediction of the replacement time of the photoconductor is periodically and repeatedly executed. It is a forming method.

According to a fourteenth aspect of the present invention, the image forming apparatus according to any one of the ninth to thirteenth aspects of the present invention, wherein the prediction of the replacement time of the photoconductor is periodically and repeatedly executed. Device.

In these inventions, the estimation of the photoconductor replacement time in (1) to (5) is repeatedly executed periodically. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(7) The invention according to claim 7 is that, when the replacement time based on the prediction approaches, the replacement time is automatically displayed, and the replacement time can be displayed by manual operation. An image forming method according to any one of claims 1 to 6.

The invention according to claim 15 is characterized in that the replacement time is displayed automatically when the replacement time based on the prediction approaches, and the replacement time can be displayed by manual operation. Claims 9 to 14
An image forming apparatus according to any one of the above.

In these inventions, the results of the (1) to (6) estimation of the photoconductor replacement time are displayed automatically or manually. For this reason, it is possible to predict and display an accurate life from the deterioration characteristics of the photoconductor in accordance with each use situation.

(8) The invention according to claim 8 is characterized in that the prediction of the replacement time of the photoreceptor according to any one of claims 1 to 5 is combined. It is an image forming method as described above.

According to a sixteenth aspect of the present invention, there is provided a method according to any of the ninth to thirteenth aspects, wherein the prediction of the replacement time of the photosensitive member is combined.
An image forming apparatus according to any one of the above.

In these inventions, any or all of the predictions of the photoconductor replacement time in (1) to (5) are executed in combination. For this reason, it is possible to accurately determine the deterioration characteristics of the photoconductor in accordance with each use situation, and it is possible to predict an accurate life.

[0033]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram illustrating an example of an electrical configuration of a portion related to an image forming apparatus according to an embodiment of the present invention. Here, reference numeral 10 denotes a CPU as control means for controlling the entire apparatus, and the measured values and the deterioration characteristics according to the present embodiment are stored in the memory 11.
Reference numeral 40 denotes an image writing unit that generates a laser beam for exposure in accordance with image data; 51M, a drum motor that drives a photoconductor; 52, a charging unit that applies a charging potential to the photoconductor surface;
Is a potential sensor for measuring the charged potential and the exposure potential of the photoconductor surface, 54 is a developing unit that uses a latent image formed on the photoconductor surface by exposure as a toner image, and 58 is a photoconductor surface in preparation for the next image formation. This is a static eliminator for erasing the potential of. Reference numeral 60 denotes a transport unit that transports the transfer paper, and 70 denotes a fixing unit that fixes the toner image on the transfer paper.

The CPU 10 calculates a correction amount for obtaining a correction amount of the charging potential and a correction amount for the exposure potential, a measuring unit for obtaining a charging time for the photosensitive member by the charging unit, and obtains a driving distance or a driving time of the developing roller. Measuring means, measuring means for determining the charge elimination time for the photoconductor by the charge eliminating section,
Further, it constitutes a replacement time predicting means for predicting a replacement time of the photoconductor from the measured value or the like.

FIG. 2 is a configuration diagram showing a mechanical configuration of the image forming apparatus according to the embodiment of the present invention. Where 3
0 is a paper feed cassette for sending out transfer paper, 40 is an image writing unit that generates a laser beam for exposure according to image data,
Reference numeral 50 denotes an image forming unit for forming an image, 51 denotes a photoconductor as an image carrier on which an image is formed, 52 denotes a charging unit that applies a charging potential to the surface of the photoconductor 51, and 53 denotes a charging potential and an exposure potential of the surface of the photoconductor. Is a potential sensor that measures
A developing unit that uses a latent image formed on one surface by exposure as a toner image; 55, a transfer unit for transferring the toner image to transfer paper; 56, a separation unit for separating the transfer paper from the photoconductor 51; Reference numeral 58 denotes a cleaning unit for scraping off excess toner on the surface of the photoreceptor 51 by a blade, and reference numeral 58 denotes a charge removing unit for erasing the potential on the surface of the photoreceptor in preparation for the next image formation. 60
Is a transport unit for transporting the transfer paper, 61 is a feed roller for feeding the transfer paper from the paper supply cassette 30, 62 is a registration roller for sending the transfer paper to the photoconductor 51 at a predetermined timing, and 63 is a guide for the transfer paper to the fixing unit. It is a transport unit. Reference numeral 70 denotes a fixing unit for fixing the toner image on the transfer paper by heat and pressure, and reference numeral 80 denotes a discharge roller for sending the transfer paper out of the apparatus.

In such an image forming apparatus, the transfer paper is fed out from the paper feed cassette 30 on which the transfer paper is loaded, and is fed to the image forming section 50. The transfer paper fed to the image forming unit 50 is synchronized by a registration roller 57 at the entrance thereof, and then comes closer to the photosensitive drum 51 as an image carrier. Image data from the image processing unit and the like is input to the image writing unit 40, and a laser diode in the image writing unit 40 irradiates the photosensitive drum 51 with laser light corresponding to the image data to form an electrostatic latent image. . The electrostatic latent image is developed by the developing unit 54 to form a toner image on the photosensitive drum 51. This toner image is transferred to the photosensitive drum 5
1 is transferred to a transfer sheet by a transfer section 55 below. Then, the transfer paper pressed to the photosensitive drum 51 is separated by the separation unit 56. The transfer paper separated from the photosensitive drum 51 enters the fixing unit 70 via the transport unit 63, and the toner image is fixed by heat and pressure. In this way,
An image is formed on the transfer paper. And the transfer paper is guide 6
1 and is discharged outside the apparatus by a discharge roller 80.

In the image forming section 50 where the image formation for one transfer sheet has been completed, the toner adhered to the photosensitive drum 51 is removed by the cleaning section 57, the charge is removed by the subsequent charge removing section 58, and the charging section 52 is further charged. To prepare for the next image formation.

When an image is formed, a charging potential and an exposure potential are detected by a potential sensor 53, and in accordance with the detection result, the CPU 10 determines a charging potential on the surface of the photosensitive member 51 and an exposure potential after the exposure. Is corrected so that the difference between the two is constant.

FIG. 3 shows the charging potential Vh due to charging, the exposure potential VL due to exposure, and the development potential VBias due to development on the surface of the photoreceptor 51. Actually, the ability of the photosensitive layer on the surface of the photosensitive member 51 gradually increases due to fatigue of the photosensitive layer due to repeated charging and discharging, or abrasion of the photosensitive layer due to friction with the cleaning blade or rubbing of the developer in the nip. Is changing. 3A (charging potential Vh to development potential VBias) and FIG. 3B (development potential VBias to exposure potential VL) tend to be narrowed due to deterioration of the photosensitive layer of photoconductor 51.

Therefore, even in such a case, the charging unit 5 is controlled so that a constant C (charging potential Vh to exposure potential VL) is obtained.
The CPU 10 performs correction for controlling the charging potential of No. 2 and the laser power of the image writing unit 40 (see FIG. 4).

In this case, the correction data a to a for each fixed number of prints (for example, several thousands) in FIG.
And the correction data bb of B are stored in the memory 1 by the CPU 10.
1 is stored. This makes it possible for the CPU 10 to calculate the prediction of the correction characteristic of A (broken line in FIG. 3) and the prediction of the correction characteristic of B (broken line in FIG. 3) from the measured characteristics (solid line). The sum of the correction characteristic of A and the correction characteristic of B means the deterioration characteristic. Instead of storing the data every fixed number of prints, the data may be stored for a certain period (every time when the power is turned on, every certain number of days).

Then, the correction value (lifetime correction value) of the photosensitive member 51 whose life has expired is separately measured, and the number of prints until the life correction value is reached is obtained from the characteristics predicted by the CPU 10. Then, the number of prints up to the life is automatically displayed on the display unit of the image forming apparatus or displayed in response to a predetermined command input.
Or, when the replacement time is approaching due to the life of the drum, CP
When U10 determines, it is automatically displayed.

In this way, it is possible to predict an accurate life of the photosensitive member according to each use condition. That is, when the deterioration of the photoconductor 51 progresses more slowly than the number of prints in a stable environment or using method, the photoconductor can be used longer than before, and waste is eliminated.

On the other hand, in a severe environment or a usage method,
Even when the deterioration of the photoconductor progresses earlier than the number of prints, the life of the photosensitive member can be reliably determined. When the deterioration is progressing early, a display for calling a service person is performed, thereby preventing a situation in which the image quality suddenly decreases due to the life of the photoconductor.

In order to determine the life of the photoconductor by measuring and predicting the deterioration of the photoconductor, the following method is possible. (1) As described above, when performing image formation while correcting so that the difference between the charged potential of the photoreceptor surface and the exposed potential after exposure is constant, the correction amount of the charged potential and the correction of the exposure potential The replacement amount is obtained, and the replacement time of the photoconductor is predicted from the correction amount.

(2) The drive distance or drive time of the photosensitive member 51 is obtained from the drive time of the drum motor 51M controlled by the CPU 10, and the replacement time of the photosensitive member is predicted from the drive distance or drive time. The wear of the photosensitive layer due to friction with the cleaning blade and the rubbing of the developer in the nip, and the fatigue of the photosensitive layer due to repeated charging and static elimination progress according to the photoconductor driving time, and the deterioration of the photoconductor proceeds. It is.

(3) Charging section 5 controlled by CPU 10
The charging time for the photoreceptor is obtained by the method 2 and the replacement time of the photoreceptor is predicted from the charging time. This is because the deterioration of the photoconductor proceeds in accordance with the charging time.

(4) Developing unit 5 controlled by CPU 10
4. Calculate the driving distance or driving time of the developing roller in 4,
The replacement time of the photoconductor is predicted from the driving distance or the driving time. This is because the deterioration of the photoconductor proceeds due to the friction between the photoconductor and the developing roller.

(5) Static eliminator 5 controlled by CPU 10
The static elimination time for the photoreceptor 51 is determined by 8 and the replacement time of the photoreceptor is predicted from the static elimination time. This is because the charge elimination time is substantially equal to the charging time, and the deterioration of the photoconductor also progresses.

(6) The prediction is performed by combining any of the above (1) to (5) or a method for predicting the replacement time of all the photoconductors. In this way, more accurate determination of deterioration can be made.

It is desirable that the above-described (1) to (6) prediction of the photoconductor replacement time is periodically repeated. By doing so, it is possible to appropriately predict the life of the photoconductor even if the usage pattern changes on the way.

The replacement time is displayed automatically when the replacement time based on the predictions (1) to (5) approaches, and the replacement time can be displayed by manual operation. It is desirable.

In order to predict the life of the photosensitive member 51,
The CPU 10 can also determine the number of usable days by judging not only the number of prints but also the usage status of the image forming apparatus up to now. Therefore, it is desirable to display the number of prints and the number of days that can be used until the replacement time.

[0054]

As described above, according to the present invention, the following effects can be obtained.

(1) According to the first and ninth aspects of the present invention, when forming an image while correcting the difference between the charged potential on the surface of the photoreceptor and the exposure potential after the exposure, the correction is made constant. In addition, the characteristics of the correction amount of the charging potential and the correction amount of the exposure potential are obtained, and the replacement time of the photoconductor is predicted from the characteristics of the correction amount. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(2) According to the second and tenth aspects of the present invention, the drive distance or drive time of the photosensitive member is obtained, and the replacement time of the photosensitive member is predicted from the drive distance or drive time. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(3) According to the third and eleventh aspects of the present invention, the charging time of the photosensitive member is obtained, and the replacement time of the photosensitive member is predicted from the charging time. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(4) According to the fourth and twelfth aspects of the invention, the replacement time of the photosensitive member is predicted by calculating the drive time or drive distance of the developing roller. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(5) According to the fifth and thirteenth aspects of the present invention, the charge removal time is obtained to predict the time for replacing the photosensitive member. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(6) According to the inventions described in (6) and (14), the prediction of the replacement time of the photoconductor in (1) to (5) is repeatedly executed periodically. For this reason, it is possible to accurately predict the lifetime from the deterioration characteristics of the photoconductor in accordance with each use situation.

(7) According to the seventh and fifteenth aspects of the present invention, the results of the (1) to (6) photoconductor replacement time prediction are automatically or manually displayed.
For this reason, it is possible to predict and display an accurate life from the deterioration characteristics of the photoconductor in accordance with each use situation.

(8) According to the eighth and sixteenth aspects of the present invention, any one or all of the (1) to (5) predictions of the photoconductor replacement time are executed in combination. For this reason, it is possible to accurately determine the deterioration characteristics of the photoconductor in accordance with each use situation, and it is possible to predict an accurate life.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating an electrical configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a mechanical configuration of the image forming apparatus according to the embodiment of the present invention;

FIG. 3 is an explanatory diagram illustrating correction characteristics of a photosensitive member of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating correction characteristics of a photosensitive member of the image forming apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 CPU 11 Memory 40 Image writing unit 51M Drum motor 52 Charging unit 53 Potential sensor 54 Developing unit 58 Static elimination unit 60 Transport unit 70 Fixing unit

Claims (16)

[Claims] A latent image is formed by exposing a charged photoreceptor, and image formation is performed while correcting the difference between the charged potential on the photoreceptor surface and the exposed potential after exposure to be constant. An image forming method, comprising: obtaining a correction amount of a charging potential and a correction amount of an exposure potential; and predicting a replacement time of a photoconductor from the correction amount. 2. An image forming method for forming an image by exposing a charged photoreceptor to form a latent image, wherein a driving distance or a driving time of the photoreceptor is obtained, and the driving distance or the driving time is calculated from the driving distance or the driving time. An image forming method for predicting a time for replacing a photoconductor. 3. An image forming method for forming an image by exposing a charged photoreceptor to form a latent image, wherein a charging time for the photoreceptor by a charging unit is obtained, and the charging time of the photoreceptor is determined from the charging time. An image forming method for predicting a replacement time. 4. An image forming method for forming an image by exposing a charged photoreceptor to form a latent image, wherein a driving distance or a driving time of a developing roller in a developing unit is obtained. Alternatively, an image forming method is characterized in that a photoconductor replacement time is predicted from a driving time. 5. An image forming method for forming an image by exposing a charged photoreceptor to form a latent image, wherein a charge elimination time for the photoreceptor by a charge elimination unit is determined, and the photoreceptor is charged based on the charge elimination time. An image forming method for predicting a replacement time. 6. The image forming method according to claim 1, wherein the estimation of the replacement time of the photoconductor is periodically and repeatedly executed. 7. The replacement time is displayed automatically when the replacement time based on the prediction approaches, and the replacement time can be displayed by a manual operation. 7. The image forming method according to any one of 6. 8. The image forming method according to claim 1, wherein the prediction of the replacement time of the photoreceptor according to claim 1 is combined. 9. A method for exposing a charged photoreceptor to form a latent image, and forming an image while correcting the difference between the charged potential on the photoreceptor surface and the exposure potential after exposure to light. An image forming apparatus, comprising: a correction amount calculation unit that calculates a correction amount of a charging potential and a correction amount of an exposure potential; and a replacement time prediction unit that predicts a replacement time of a photoconductor from the correction amount. Characteristic image forming apparatus. 10. An image forming apparatus for forming an image by exposing a charged photoreceptor to form a latent image, comprising: a measuring unit for determining a driving distance or a driving time of the photoreceptor; An image forming apparatus comprising: a replacement time prediction unit configured to predict a replacement time of a photoconductor from a driving time. 11. An image forming apparatus for forming an image by exposing a charged photoreceptor to form a latent image, comprising: a measuring unit for obtaining a charging time for the photoreceptor by a charging unit; An image forming apparatus comprising: a replacement time predicting unit that predicts a replacement time of a photoconductor. 12. An image forming apparatus for forming an image by exposing a charged photoreceptor to form a latent image, comprising: a measuring unit for determining a driving distance or a driving time of a developing roller in a developing unit; An image forming apparatus comprising: a replacement time prediction unit configured to predict a replacement time of the photoconductor from the driving distance or the driving time. 13. An image forming apparatus for forming an image by exposing a charged photoreceptor to form a latent image, comprising: a measuring unit for obtaining a static elimination time for the photoconductor by the static elimination unit; An image forming apparatus comprising: a replacement time predicting unit that predicts a replacement time of a photoconductor. 14. The image forming apparatus according to claim 9, wherein the prediction of the replacement time of the photoconductor is repeatedly executed periodically. 15. The replacement time is automatically displayed when the replacement time based on the prediction approaches, and the replacement time can be displayed by a manual operation. 15. The image forming apparatus according to any one of 14. 16. The image forming apparatus according to claim 8, wherein prediction of replacement time of the photosensitive member according to any one of claims 9 to 13 is combined.