JP2003263079A - Image forming device and method for estimating life of photoreceptor used in the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device which can accurately estimate and detect the life of a photoreceptor without hindering its saving of space and reduction of cost for a photoreceptor unit. <P>SOLUTION: The image forming device having an electrifying means which electrifies the surface of a photoreceptor is constituted, for solving the problem, so that it is provided with a bias-on time detection means which integrates each bias-on time during which a bias is applied to the electrifying means, and a life estimation detection means which estimates and detects the life of the photoreceptor based upon the bias-on time detected by the bias-on time detection means. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital copying machine or a printer adopting an electrophotographic system, and more particularly to a life prediction detecting means for predicting and detecting the life of an image carrier such as a photosensitive drum. The present invention relates to a provided image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a digital copying machine or a printer adopting the electrophotographic method, the surface of a photosensitive drum is uniformly charged by a charging means, and then the surface of the photosensitive drum is charged. Image exposure is performed to form an electrostatic latent image according to image information, and the electrostatic latent image is developed by a developing device to form a toner image. In the image forming apparatus, the toner image formed on the photoconductor drum is transferred onto the recording paper fed from the paper feeding device, and then the recording paper on which the toner image is transferred is fixed to the fixing device. The image is formed by fixing with heat and pressure.

By the way, in the above image forming apparatus,
Improves maintainability by integrating the photoconductor drum and its neighboring parts into an integrated unit so that the user can easily replace the photoconductor drum unit with a new one when the photoconductor drum reaches the end of its life. I am letting you.

In this case, in the photoconductor drum unit of the image forming apparatus, which saves space and costs, the life of the photoconductor is generally determined by the rotation time and the number of rotations of the photoconductor drum, or the number of printed sheets. It is detecting.

In the above-mentioned image forming apparatus, as a charging means for uniformly charging the surface of the photosensitive drum, instead of the conventional scorotron, the generation of ozone and the like is small, and the charging of the high voltage power source is possible. Rollers are often used. A DC bias voltage on which an AC bias voltage is superimposed is applied to the charging roller in consideration of the uniformity of charging and the adhesion of toner to the surface of the charging roller.

However, in the above-mentioned photosensitive drum, the charge transport layer (C) on the surface of the photosensitive drum (OPC photosensitive member) is discharged by the discharge due to the application of the AC bias voltage of the charging roller.
TL) is deteriorated by discharge, and the charge transport layer (CTL) on the surface of the photosensitive drum, which has been deteriorated by discharge, is scraped by rubbing of a cleaning blade, a transfer roller, or the like, and the surface of the photosensitive drum cannot be charged. Becomes

Therefore, in order to extend the life of the photoconductor drum as much as possible, it is effective to suppress the deterioration of the photoconductor surface due to the discharge by turning off the voltage applied to the charging roller when the image is not formed. is there.

However, the total bias-on time of the charging roller is the number of sheets to be printed in one operation, the sheet size, and when the image forming apparatus has a single drive motor, the image forming apparatus sleeps. It depends on the idle rotation time of the fixing roller that operates to return from the mode. Especially, in the image forming apparatus etc. in which the power consumption in the sleep mode is greatly reduced,
As shown in the figure, the idling time of the fixing roller changes according to the sleep time when the machine is not operating. It rotates idly, and at this time, the bias to the charging roller is turned off.

As described above, since the ratio of the bias-on time of the charging roller to the rotation time of the photosensitive drum varies depending on the usage condition of the image forming apparatus, the life of the photosensitive member is also the ratio of the bias-on time of the charging roller. It depends on the device.

Therefore, in the image forming apparatus in which the life of the photoconductor is predicted and detected by the rotation time and the number of rotations of the photoconductor drum or the number of prints on the paper, the life of the photoconductor can be accurately detected. If it becomes shorter than the set life, trouble may occur on the image,
On the contrary, there is a problem in that the photoconductor unit is replaced and the running cost is undesirably increased even though it has a long life and is still usable.

Therefore, as a technique capable of solving such a problem, for example, a photoconductor life detecting means disclosed in Japanese Patent Application Laid-Open Nos. 9-190144 and 9-237018 has been proposed. Has been done.

The image forming apparatus according to Japanese Unexamined Patent Publication No. 9-190144 includes an electrophotographic photosensitive member and a contact charging member that comes into contact with the electrophotographic photosensitive member to uniformly charge the surface layer of the electrophotographic photosensitive member. In the provided electrophotographic image forming apparatus, means for detecting or controlling the discharge current flowing in the contact charging member, and means for calculating the amount of wear of the electrophotographic photosensitive member based on the detected or controlled discharge current value, And means for storing the calculated integrated value of the amount of consumption.

Further, in the image forming apparatus according to the above-mentioned Japanese Patent Laid-Open No. 9-237018, a member to be charged having a photosensitive member on its surface, a charging member arranged in contact with the photosensitive member, and a voltage is applied to the charging member. In the image forming apparatus, which includes a voltage applying unit for charging or discharging the photoconductor through the charging member, detects a current output when the photoconductor is charged or discharged through the charging member. First means for updating and storing an integrated value of the current detected by the current detecting means
Storage means, and control means for predicting the life of the photoconductor by comparing the integrated value of the current updated and stored in the first storage means with the integrated value of the current corresponding to the life of the photoconductor. It is configured to include.

[0014]

However, the above-mentioned prior art has the following problems. That is, the above-mentioned JP-A-9-190144 and JP-A-9-2
In the case of the image forming apparatus according to Japanese Unexamined Patent Publication No. 37018, a means for detecting or controlling the discharge current flowing through the contact charging member, or a current output when the photosensitive member is charged or discharged through the charging member is detected. Since current detection means must be provided, there is a problem that space saving and cost reduction of the photoconductor unit are hindered.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and the object thereof is to prevent the space saving and cost reduction of the photoconductor unit without hindering the photosensitization. An object is to provide an image forming apparatus capable of accurately predicting and detecting the life of a body.

[0016]

In order to achieve the above object, the invention described in claim 1 is an image forming apparatus having a charging means for charging the surface of a photoreceptor, and a bias is applied to the charging means. Bias-on-time detecting means for integrating and detecting bias-on-time, and life prediction detecting means for predicting and detecting the life of the photoconductor based on the bias-on time detected by the bias-on-time detecting means. An image forming apparatus comprising:

According to a second aspect of the present invention, in an image forming apparatus that includes a charging unit that charges the surface of the photoconductor, and does not apply a bias to the charging unit when an image is not formed, the rotating state of the photoconductor. Rotation detecting means for accumulating and detecting, bias on time detecting means for accumulating and detecting bias on time for applying a bias to the charging means, rotation time detected by the rotation detecting means and the bias on time An image forming apparatus comprising: a life prediction detecting unit that predicts and detects the life of the photoconductor based on the bias-on time detected by the detecting unit.

Further, in the invention described in claim 3, the life time prediction detecting means detects the rotation time detected by the rotation detecting means every time the rotation time detected by the rotation detecting means reaches a predetermined time. 3. The image forming apparatus according to claim 2, wherein the life of the photoconductor is predicted and detected based on the bias on time detected by the bias on time detecting unit.

Furthermore, the invention described in claim 4 is
Based on the life expectancy of the life expectancy detection means,
The image forming apparatus according to any one of claims 1 to 3, further comprising: a unit that warns or displays a replacement time of the photoconductor.

The invention according to claim 5 further comprises means for controlling the amount of exposure light for exposing an image on the photoconductor based on the life predicted and detected by the life prediction detecting means. The image forming apparatus according to any one of 1.

Further, in the invention described in claim 6, the developing bias for developing the electrostatic latent image formed on the surface of the photoconductor is controlled based on the life predicted and detected by the life prediction detecting means. The image forming apparatus according to claim 1, further comprising a unit.

The invention according to claim 7 further comprises means for controlling a bias applied to the charging means based on the life predicted and detected by the life prediction detecting means. The image forming apparatus described in 1.

Further, in the invention described in claim 8, in a method of predicting the life of a photoconductor used in an image forming apparatus equipped with a charging means for charging the surface of the photoconductor, a bias on for applying a bias to the charging means. A method for predicting the life of a photoconductor, characterized by integrating and detecting time, and predicting and detecting the life of the photoconductor on the basis of the bias on time detected by the bias on time detecting means.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 2 shows a digital printer as an image forming apparatus according to Embodiment 1 of the present invention.

This digital printer is configured to form an image on the basis of image information sent from a personal computer, an image reading device or the like (not shown). Inside the digital printer body 1, a process cartridge 2 in which an image forming member such as a photosensitive drum is integrally unitized is arranged. The process cartridge 2 is configured to be attachable / detachable to / from the printer body 1, and provided on the upper portion of the printer body 1 or the like when the photoconductor drum or the like provided in the process cartridge 2 reaches the end of its life. The cover can be opened and replaced with a new cartridge 2.

As shown in FIGS. 2 and 3, the process cartridge 2 has a photosensitive drum 3 as an image carrier.
A charging roller 4 as a charging means, a developing device 5 as a developing means, and a cleaning device 6.

As the photosensitive drum 3, for example, a cylindrical metal cored bar made of aluminum or the like is coated on its surface with a charge generation layer (CGL), a charge transport layer (CTL), and the like in this order. A photoconductor (OPC) is used, and the photoconductor drum 3 is driven at a predetermined rotational speed by a driving unit (not shown) along the arrow direction. The surface of the photosensitive drum 3 is
As shown in FIG. 3, after being uniformly charged to a predetermined potential by the charging roller 4, the ROS (Ras as the exposing means is used.
Image exposure is performed by a ter Output Scanner (see FIG. 2) to form an electrostatic latent image according to image information. As shown in FIG. 2, the ROS 7 modulates a semiconductor laser on the basis of image information that has been subjected to predetermined image processing by the image processing device 8, and outputs a laser beam LB emitted from the semiconductor laser to a collimator lens, An electrostatic latent image is formed on the surface of the photoconductor drum 3 by scanning and exposing the photoconductor drum 3 through an imaging optical system including a reflection mirror, a polygon mirror, an f-θ lens, and the like. Has been done. Then, the electrostatic latent image formed on the photoconductor drum 3 is developed by the developing device 5 containing the one-component developer (toner) to form a toner image. The developing device 5 may of course use a two-component developer.

As shown in FIG. 2, the toner image formed on the photosensitive drum 3 is transferred onto a recording sheet 10 as a recording medium by a transfer roll 9 as a transfer means. The recording paper 10 is fed from the paper feed cassette 12 by the feed roll 11, is separated by the separation roll 13 and the retard roll 14 one by one, is conveyed to the registration roll 15, and is temporarily stopped. Then, the recording paper 10 is conveyed to the surface of the photosensitive drum 3 by the registration roll 15 in synchronization with the toner image formed on the photosensitive drum 3, and the recording paper 1 is conveyed.
0, the toner image is transferred from the photosensitive drum 3 onto the transfer roll 9
Transcribed by

Recording sheet 10 on which this toner image is transferred
After being separated from the photoconductor drum 3, the toner is conveyed to the fixing device 16, fixed by heat and pressure by the heating roll 17 and the pressure roll 18 of the fixing device 16, and then discharged by the discharge roll 19 to the printer body 1. The sheet is discharged onto the sheet discharge tray 20 provided on the upper part of the sheet, and a series of image forming steps is completed.

The cleaning device 6 removes the residual toner from the surface of the photosensitive drum 3 after the toner image transfer step is completed, and prepares for the next image forming step.

FIG. 3 shows a process cartridge of the above digital printer.

As shown in FIGS. 5 and 6, the process cartridge 2 is composed of an upper cartridge 21 and a lower cartridge 22. The upper cartridge 21 and the lower cartridge 22 are connected so as to be tiltable about the engaging pin 25 by engaging portions 23 and 24 and an engaging pin 25 provided at both ends in the width direction thereof. In addition, as shown in FIG. 5, it is biased by a spring 26 provided on the upper surface of the lower cartridge 22, and as shown in FIGS. 7 and 8, the photosensitive drum 3 and the developing roller of the developing device 5 are urged. The tracking rolls 28 provided at both ends of 27 are configured to come into pressure contact with each other at a predetermined pressure (for example, 2 kg on one side).

Further, on the upper surface of the lower cartridge 22, as shown in FIG. 8, an irradiation space 29 for exposing the surface of the photosensitive drum 3 with the laser beam LB emitted from the ROS 7 is substantially fan-shaped. It is provided in.

At one end of the upper cartridge 21,
As shown in FIG. 4, a photosensitive drum 3 is rotatably mounted, a charging roll 4 is provided on a side of the photosensitive drum 3, and a cleaning device 6 is provided on an upper portion thereof. A cleaning blade 31 is provided. The cleaning device 6 also occupies most of the collected toner conveying member 32 that conveys the collected toner removed by the cleaning blade 31 and the upper cartridge 21 that stores the collected toner conveyed by the collected toner conveying member 21. And a toner storage chamber 33. Further, in the upper cartridge 21,
A cover 34 that covers the surface of the photosensitive drum 3 is provided to be openable and closable. As shown in FIG. 4, the cover 34 normally covers the surface of the photoconductor drum 3 to prevent the photoconductor drum 3 from being exposed and deteriorated. In the state of being mounted at a predetermined position, as shown in FIG. 3, it automatically opens with the mounting operation and comes into contact with the transfer roll 9.

On the other hand, the lower cartridge 22 constitutes the developing device 5 itself. A developing roll 27 is rotatably disposed at one end of the housing 35 of the developing device 5, and the surface of the developing roll 27 is triboelectrically charged with toner and regulates the layer thickness of the toner. The restricting member 36 is in contact with. A toner supply member 37 that supplies toner to the surface of the developing roll 27 is rotatably provided on the back side of the developing roll 27. On the back side of the toner supply member 37, a toner accommodating portion 39 that occupies most of the developing device 5 is integrally provided via a toner supply opening 38. A bottom surface 40 of the toner containing portion 39 is formed by connecting two portions 41 and 42 each having a substantially arcuate cross section.
Inside the toner container 40, the toner is agitated and conveyed, in which the contained toner is agitated and sequentially conveyed from the second toner container 42 on the back side to the first toner container 41 on the developing roller 27 side. The members 43 and 44 are rotatably arranged.

A toner sensor 45 for detecting the presence / absence of toner is provided on the bottom surface of the first toner container 41, as shown in FIG.

By the way, in this embodiment, in the image forming apparatus having the charging means for charging the surface of the photosensitive member, the bias-on-time detecting means for integrating and detecting the bias-on time for applying the bias to the charging means. And a life expectancy detecting means for estimating and detecting the life of the photoconductor based on the bias on time detected by the bias on time detecting means.

Further, in this embodiment, in the image forming apparatus which is provided with the charging means for charging the surface of the photoconductor and does not apply the bias to the charging means when the image is not formed, the rotation state of the photoconductor is integrated. Rotation detecting means for detecting, bias on time detecting means for detecting by integrating bias on time for applying bias to the charging means, rotation time detected by the rotation detecting means and detection by the bias on time detecting means And a life expectancy detecting means for predicting and detecting the life of the photoconductor based on the bias on time.

Further, in this embodiment, the life prediction detecting means detects the rotation time detected by the rotation detecting means and the bias-on every time the rotation time detected by the rotation detecting means reaches a predetermined time. Based on the bias on time detected by the time detection means,
It is configured to predict and detect the life of the photoconductor.

Furthermore, in this embodiment, it is configured to have a means for warning or displaying the replacement time of the photoconductor based on the life predicted and detected by the life prediction detecting means.

Further, in this embodiment, the amount of exposure light for exposing an image on the photoconductor and the electrostatic latent image formed on the surface of the photoconductor are determined based on the life predicted and detected by the life prediction detection means. It is configured to have a means for controlling at least one of a developing bias for developing and a bias applied to the charging means.

FIG. 1 is a block diagram showing a control circuit of a digital printer as the image forming apparatus.

In FIG. 1, reference numeral 50 denotes a control device composed of a CPU, MPU, etc. This control device 50 performs an image forming operation of a digital printer as an image forming device based on a program stored in a ROM (not shown). In addition to being controlled, it also functions as a life prediction detecting means for predicting and detecting the life of the photoconductor. Further, the control device 50 includes a storage device 5 including a RAM or the like for storing the lifespan Q of the photoconductor predicted and detected by the control device 50.
1 is connected.

Further, reference numeral 52 is a main motor for driving the photosensitive drum 3 to rotate.
In addition to the photoconductor drum 3, the fixing device 16 and the like are simultaneously driven to rotate. Reference numeral 53 is a main motor on-time integration timer as a rotation detection means for calculating the on-time T1 of the main motor 52.

Furthermore, 54 is a high voltage power supply device for the charging roller which applies a DC bias voltage obtained by superimposing an AC bias voltage to the charging roller 4. Reference numeral 55 is a high-voltage power-on time integration timer as a bias-on-time detecting means which is obtained by integrating the on-time T2 of the high-voltage power supply device 54 for the charging roller.

Then, the control device 50 controls the life of the photosensitive member based on the rotation time T1 detected by the main motor on-time integration timer 53 and the bias on time T2 detected by the high-voltage power-on time integration timer 55. Is configured to be predicted and detected.

Further, in this embodiment, the control device 50
Is provided with a display device 56 that warns or displays the replacement time of the photoconductor based on the predicted and detected life. As the display device 56, for example, a display unit of a user interface of a printer is used. Of course, other display devices may be used.

With the above configuration, the digital printer as the image forming apparatus according to the embodiment of the present invention is
In the following manner, it is possible to accurately predict and detect the life of the photoconductor without hindering space saving and cost reduction of the photoconductor unit.

That is, in the digital printer according to this embodiment, as shown in FIG. 2, by repeatedly performing the printing operation, the photosensitive drum 3 is discharged by applying the AC bias voltage to the charging roller 4. ,
The charge transport layer (CTL) on the surface of the photoconductor (OPC photoconductor) drum 3 is deteriorated due to discharge, and the charge transport layer (CTL) on the surface of the photoconductor drum 3 which is deteriorated due to discharge is used as the cleaning blade 31 or the transfer roller 9. It is gradually scraped and worn by rubbing.

Therefore, when the image is not formed on the surface of the photosensitive drum 3, the bias voltage is not applied to the charging roller 4 to reduce the damage due to the deterioration of the charge transport layer due to the discharge. It can prolong the life of the body. Therefore, when the bias-on time of the charging roller 4 with respect to the rotation time of the photosensitive drum 3 is relatively constant with respect to the usage conditions of each device, that is, the rotation time of the photosensitive drum 3 and the bias of the charging roller 4 If the devices have substantially the same on-time, the controller 5
For 0, the bias-on time of the charging roller 4 is measured by the high-voltage power-on time integration timer 55, and the life of the photoconductor is predicted and detected by the total bias-on time of the charging roller 4 used in the photoconductor unit 2. . Then, the control device 50 determines that the total bias-on time of the charging roller 4 is
When a certain charging time which is the life of the photoconductor is reached, the fact that the photoconductor has reached the end of life is displayed on the display device 65, and a warning is issued to replace the photoconductor unit 2 with a new one.

Further, when the digital printer is a device in which the power consumption in the sleep mode is greatly reduced, and when returning from the sleep mode, as shown in FIG. Accordingly, in a single apparatus in which the idling time of the fixing roller 17 changes and the drive motor is only the main motor 52, the idling of the fixing roller 17 causes the photoconductor drum 3 to idle at the same time. At this time, since the bias to the charging roller 4 is turned off, even if the photosensitive drum 3 rotates, it is not affected by the discharge deterioration by the charging roller 4.

As described above, in the case where the digital printer is a device in which the bias-on time of the charging roller 4 with respect to the photoconductor rotation time varies greatly depending on the usage conditions of the device, such as when the photoconductor drum 3 is idle. That is, in order to obtain a device in which the number of times of idle rotation and the idle rotation time greatly differ depending on the frequency of use by the user, the life of the photosensitive drum 3 is controlled by executing the control shown in FIG. It is possible to accurately predict.

The effect of extending the life of the photoconductor drum 3 has a relationship as shown in FIG. 10, depending on the ratio of the bias-on time of the charging roller 4 to the photoconductor rotation time.
It has been confirmed by the experiments of the present inventors.

More specifically, the control device 50 measures the photoconductor rotation time or the number of rotations and the bias on time of the charging roller 4 by the main motor on-time integration timer 53 and the high-voltage power-on time integration timer 55. In the case of a device that measures the number of rotations of the photoconductor drum 3, the rotation speed of the photoconductor drum 3 is converted into a rotation time.

Next, as shown in FIG. 9, the control device 50, when the photoconductor rotation time of the photoconductor drum 3 reaches the rotation time (T1) set for life estimation (step 101), The bias-on time ratio (M = T2 / T1) of the charging roller 4 is calculated from the photosensitive member rotation time and the charging roller bias-on time (T2) at that time (step 10).
2) The photoconductor life extension effect (N) is derived from the relational expression of the extension effect shown in FIG. 10 (step 103), and the photoconductor rotation time or rotation when the bias-on time ratio of the charging roller 4 is 100%. The photoconductor life time Q, which is the photoconductor rotation time or the number of rotations with the extension effect added from the set number of times
Is stored in the storage device 51 of the apparatus main body or the storage device of the photoconductor unit 2 (step 104).

When the photoconductor rotation time reaches or is near the predicted photoconductor life, the photoconductor life is displayed and a warning is given (step 105). The life estimation of the photoconductor may be performed only once, but since it changes while the photoconductor is in use, the above-mentioned operation is performed for each fixed interval of the photoconductor rotation time or the number of rotations. By doing so, it is desirable to correct the photoconductor life prediction so that it actually matches.

Further, since the wear amount of the film thickness of the charge transport layer can be predicted from the prediction of the total bias-on time of the charging roller 4 or the rotation time when the photosensitive member reaches the end of its life, the exposure apparatus can be calculated according to the wear amount. By changing one of the eight light amounts, the developing bias, and the bias of the charging roller 4 or a combination thereof, it becomes possible to set the optimum image quality parameter according to the photoconductor film thickness.

As described above, in the above-described embodiment, the life of the photoconductor can be predicted only by measuring the photoconductor rotation time and the bias on time of the charging roller 4. Therefore, the bias on time of the charging roller 4 varies depending on the device. Even in this case, it is possible to properly estimate the life of the photoconductor according to each device.

Further, in the above embodiment, since the life of the photoconductor can be predicted only by measuring the photoconductor rotation time and the charging roller bias on time, no special detection sensor or complicated control is required, and the image forming apparatus Space saving / cost reduction is possible.

Further, in the above-described embodiment, by predicting the life of the photoconductor, the life is short with respect to the set photoconductor time, and troubles may occur on an image or the life is long and the photoconductor is still usable. It is possible to replace the unit that is almost in use without notifying the replacement of the photoconductor unit, it is possible to reduce the running cost, and it is possible to prevent troubles due to defective charging of the photoconductor.

Furthermore, in the above-described embodiment, by changing any one or a combination of the light amount of the exposure device, the developing bias, and the charging roller in accordance with the predicted photoreceptor life and the film thickness reduction of the charge transport layer. Therefore, it is possible to easily control the image control parameter according to the variation in the sensitivity of the photoconductor due to the decrease in the film thickness of the photoconductor.

[0063]

As described above, according to the present invention, it is possible to accurately predict and detect the life of the photoconductor without hindering space saving and cost reduction of the photoconductor unit. A forming device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control circuit of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a digital printer as an image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional configuration diagram showing an image forming unit.

FIG. 4 is an exploded perspective view showing an image forming unit.

FIG. 5 is an external perspective view showing an image forming unit.

FIG. 6 is an exploded plan view showing an image forming unit.

FIG. 7 is an exploded perspective view showing an image forming unit.

FIG. 8 is an exploded side view showing the image forming unit.

FIG. 9 is a flowchart showing an operation of the digital printer as the image forming apparatus according to the first embodiment of the present invention.

FIG. 10 is a graph used for controlling the digital printer as the image forming apparatus according to the first embodiment of the present invention.

FIG. 11 is a graph showing the relationship between sleep time and idle rotation time.

[Explanation of symbols]

3: photoconductor drum, 4: charging roller, 50: control device,
51: storage device, 52: main motor, 53: main motor ON time integration timer, 54: high voltage power supply device for charging roller, 55: high voltage power ON time integration timer.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Hashino             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. (72) Inventor Hideaki Ozawa             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. F-term (reference) 2H027 DA06 DA39 DE07 EA01 EA02                       EA05 EC06 EE07 EF09 GA30                       HB02 HB14                 2H073 AA01 BA01 BA13 BA22 CA02                 2H076 AB02 AB12 DA06 DA11                 2H200 FA02 GA23 GA34 GA46 GA56                       GB12 GB22 GB33 GB44 HA02                       HA29 HB12 HB22 JA02 JB10                       PA03 PA22 PA27 PB35

Claims (8)

[Claims] 1. An image forming apparatus provided with a charging unit for charging the surface of a photoconductor, a bias-on-time detecting unit for integrating and detecting a bias-on time for applying a bias to the charging unit, and the bias-on time. An image forming apparatus, comprising: a life prediction detecting unit that predicts and detects the life of the photoconductor based on the bias-on time detected by the detecting unit. 2. An image forming apparatus comprising a charging unit for charging the surface of a photosensitive member, wherein a bias is not applied to the charging unit when an image is not formed, and a rotation detecting unit for integrating and detecting a rotating state of the photosensitive member. A bias-on-time detecting means for integrating and detecting a bias-on-time for applying a bias to the charging means, a rotation time detected by the rotation detecting means, and a bias-on time detected by the bias-on-time detecting means. An image forming apparatus comprising: a life prediction detecting unit that predicts and detects the life of the photoconductor based on the above. 3. The life prediction detection means detects the rotation time detected by the rotation detection means and the bias-on-time detection means each time the rotation time detected by the rotation detection means reaches a predetermined time. The image forming apparatus according to claim 2, wherein the life of the photoconductor is predicted and detected based on the bias-on time. 4. The image forming apparatus according to claim 1, further comprising a unit that warns or displays the replacement time of the photoconductor based on the lifespan predicted and detected by the lifespan prediction detection unit. 5. The image forming apparatus according to claim 1, further comprising a unit that controls an exposure light amount for exposing an image on the photoconductor, based on a life that the life prediction detection unit predictively detects. 6. The method according to claim 1, further comprising a means for controlling a developing bias for developing the electrostatic latent image formed on the surface of the photoconductor, on the basis of the life predicted and detected by the life prediction detecting means. An image forming apparatus according to claim 2. 7. The image forming apparatus according to claim 1, further comprising: a unit that controls a bias applied to the charging unit based on the life estimated and detected by the life expectancy detecting unit. 8. A method for predicting the life of a photoconductor used in an image forming apparatus equipped with a charging unit for charging the surface of the photoconductor, wherein the bias on time for applying a bias to the charging unit is integrated and detected to detect the bias. A method for predicting the life of a photoconductor, wherein the life of the photoconductor is predicted and detected based on the bias on time detected by the on-time detection means.