JP2002072778A - Image forming apparatus and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of fogging or toner scattering resulting from the life of a photoreceptor drum by accurately detecting the life of the photoreceptor drum. SOLUTION: When no image is formed, a specific AC component is applied to an electrostatic charging roller 2 and the ratio (x) of a current Iac and a voltage Vpp detected by a load value detecting means 22 at this time is compared with a reference value X previously stored in a memory 20 of a process cartridge A to automatically determine whether or not image forming operation is carried out or quit according to the comparison result; when the image forming operation is quit, warning information is displayed on a display device 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an image forming apparatus using an electrophotographic method, and a process cartridge detachably mountable to the main body of the image forming apparatus.

Here, as an electrophotographic image forming apparatus,
For example, an electrophotographic copying machine, an electrophotographic printer (for example, L
ED printers, laser beam printers, etc.), and electrophotographic facsimile machines.

A process cartridge detachably mountable to the main body of the electrophotographic image forming apparatus is a cartridge in which at least a charging means and an electrophotographic photosensitive member are integrally formed, and this cartridge is detachably mountable to the main body of the electrophotographic image forming apparatus. To say.

[0004]

2. Description of the Related Art FIG. 10 shows an example of a conventional image forming apparatus.

This image forming apparatus is an electrophotographic laser beam printer, and has an electrophotographic photosensitive member (hereinafter, referred to as a "photosensitive drum") 101 as an image bearing member generally of a rotary drum type. The surface of the photosensitive drum 101 is uniformly charged by a charging roller 102 serving as a charging unit, and is exposed by a laser according to image information by an exposing unit 103 to form an electrostatic latent image on the surface of the photosensitive drum 101. . Next, the electrostatic latent image is visualized as a toner image by the developing device 104.

On the other hand, a transfer material, which is a recording medium, stored in a paper feed cassette 113 is fed one by one by a feed roller 114, and is further synchronized with a toner image on the photosensitive drum 101 by a registration roller 105. To a transfer section formed by the photosensitive drum 101 and a transfer roller 108 serving as a transfer unit via transfer guide pairs 106 and 107.
Here, the transfer roller 108 transfers the toner image on the photosensitive drum 101 onto a transfer material.

The transfer material onto which the toner image has been transferred is supplied to a fixing device 11.
And the toner image is fixed as a permanently fixed image by pressure and heat, and is discharged to a discharge tray 115.

After the toner image on the photosensitive drum 101 is transferred to the transfer material, the photosensitive drum 101 is cleaned by a cleaner 112 which is a cleaning means by removing residual contaminants such as transfer residual toner and paper powder remaining on the surface. And used repeatedly in the image forming process.

In the above laser beam printer, for example, a photosensitive drum 101, a charging roller 102,
In recent years, the process cartridge system in which the developing device 104 including the toner container 104a and the cleaner 112 are integrated as a process cartridge and are detachably mounted on the printer main body to realize maintenance-free operation has recently been applied to a high-speed, high-durability image forming apparatus. Are also becoming more commonly used.

[0010] In contact charging, a charging member to which a voltage is applied is brought into contact with a photoreceptor to directly transfer charges to the photoreceptor, thereby charging the surface of the photoreceptor to a required potential.
The contact charging device using this contact charging can reduce the applied voltage required to charge the photoreceptor surface to a desired potential, as compared with a corona charging device that has been widely used as a charging device. That the amount of ozone generated during the charging process is very small, eliminating the need for an ozone removal filter, etc., which simplifies the configuration of the exhaust system of the device, is maintenance-free, and has a simple configuration. It has many advantages, such as being there.

As a contact charging member, a roller-shaped charging roller in which a conductive elastic layer and a resistance adjusting layer are sequentially formed on a core metal is widely used. In this contact charging device, a uniform charging process is performed on the surface of the photoconductor by applying an oscillating voltage obtained by superimposing a DC voltage on an AC voltage to the contact charging member.

Means for extending the life of the photosensitive drum used in the process cartridge include a method of hardening the photosensitive layer, increasing the film thickness, and reducing the number of idle rotations of the photosensitive member. The method of increasing the film thickness is in the direction of image quality deterioration, and as a method of hardening the photosensitive layer, there is a method of dispersing fluororesin particles and increasing the slipperiness of the surface layer, but this also scatters exposure. This is the direction of image quality deterioration.

As a method for hardening the photosensitive layer without deteriorating the image quality, there is a method in which the surface layer is made of a high molecular weight resin. Conventionally, a commonly used ordinary resin has a molecular weight of 2,000.
Although it was a polycarbonate resin having a molecular weight of about 0,
Recently, even resins having a high molecular weight of 000 or more can be made of polycarbonate, polyarylate, or the like.

[0014]

However, the above-mentioned prior art has the following problems.

A high-speed, high-durability, long-life image forming apparatus includes:
There are various uses in the market. Therefore, the number of sheets passed through the process cartridge when the toner life is reached varies greatly. For example, if printing is performed at an A4 size and a printing rate of 4%, a process cartridge having a toner life of 15,000 sheets can be printed at a low printing rate of 2% to obtain 300.
00 sheets will be passed. Also, if there is paper of B5 size, legal, or A3 size instead of A4 size, performing a double-sided printing function or the like with a long idle rotation time is also a factor that causes a large variation in the number of sheets passed during the life of the toner.

In particular, when used at a low printing rate, the life of the photosensitive drum has expired even though the toner has not run out, and fogging may occur due to poor charging. In addition, by performing a print job or copying several hundred sheets immediately before the end of the life of the photosensitive drum, the photosensitive drum reaches the end of its life during printing, and a great amount of toner is scattered in the apparatus body. There is also a possibility.

Accordingly, it is an object of the present invention to provide an image forming apparatus and a process cartridge capable of accurately detecting the life of an image carrier.

Another object of the present invention is to provide an image forming apparatus and a process cartridge which can prevent fogging or scattering of the developer due to the life of the image carrier.

[0019]

The above object is achieved by an image forming apparatus and a process cartridge according to the present invention. In summary, the present invention provides an image forming apparatus including a process cartridge including an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member to a predetermined potential, and cartridge information storage means for storing cartridge information. The apparatus further includes a load value detecting unit that detects a ratio of a current and a voltage of an AC component of a bias applied to the charging unit, and applies a predetermined AC component to the charging unit during non-image formation. Comparing the ratio of the current and the voltage detected by the load value detection means with the cartridge information in the cartridge information storage means, and according to the comparison result,
An image forming apparatus is characterized by automatically determining whether to perform or stop the image forming operation.

According to an embodiment of the present invention, there is provided a high-voltage power supply unit including a power supply for applying a bias in which an AC component and a DC component are superimposed on the charging unit, and the load value detection unit.

According to another embodiment of the present invention, cartridge information reading means for reading the cartridge information from the cartridge information storage means, load value signal reading means for reading a signal from the load value detecting means, and charging means And switching means for switching the magnitude of the bias applied to the power supply.

According to another embodiment of the present invention, there is provided a temperature detecting means for detecting an ambient temperature of the apparatus,
A value obtained by correcting the value of the cartridge information read from the cartridge information storage means in accordance with the temperature detected by the temperature detection means, and a predetermined AC component are applied during non-image formation. The ratio between the current and the voltage detected by the means is compared, and it is automatically determined whether to perform or stop the image forming operation according to the comparison result.

Further, according to another embodiment of the present invention, the control means can read and write information stored in the cartridge information storage means, and the information written by the control means is such that the process cartridge reaches the end of its life. Is information that means that

According to another embodiment of the present invention, when the image forming operation is stopped, warning information is displayed on the display means. A signal for displaying the warning information is transmitted to the display means and displayed. Alternatively, it can communicate with a device having the display means, and transmits a signal for displaying the warning information to the device having the display means. The cartridge information is a reference value indicating that the image carrier has reached the end of its life.

According to another aspect of the present invention, there is provided an image carrier, and charging means for charging the image carrier to a predetermined potential;
A process cartridge having cartridge information storage means for storing cartridge information, wherein the cartridge information is a reference value indicating that the image carrier has reached the end of its life. Is provided.

In each of the above inventions, the reference value is a value unique to each process cartridge. The reference value is a value related to the thickness of the image carrier and the capacitance of the charging unit.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus and a process cartridge according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 A first embodiment of the present invention will be described with reference to FIGS.

First, the configuration and operation of the image forming apparatus of this embodiment will be described with reference to FIGS.

[Overall Configuration of Image Forming Apparatus] As shown in FIG. 1, an electrophotographic photosensitive member (hereinafter, referred to as "photosensitive drum") 1 as an image carrier is provided, and a photosensitive drum 1 is uniformly formed around the photosensitive member. The developing device 4 is a developing unit for developing the electrostatic latent image on the photosensitive drum 1 as a visible image with a developer (toner), and the transferring the visible image as a storage medium. The image forming apparatus includes a transfer roller 8 as a transfer unit for transferring to a material, a cleaner 12 as a cleaning unit for removing and cleaning residual toner on the photosensitive drum 1 and the like.

Further, an exposure device 3 for exposing the photosensitive drum 1 to light, a discharging needle 9 for discharging the transfer material, a pair of registration rollers 5 for feeding and transporting the transfer material, and introducing the transfer material to the transfer portion. A pair of transfer guides 6 and 7, a transport guide 1 for transporting a transfer material on which a visible image is transferred by a developer to the fixing device 11
0, a paper cassette 13 for storing the transfer material, a paper feed roller group 14 for feeding and transporting the transfer material in a timely manner, and the like.

In this embodiment, the photosensitive drum 1,
The charging roller 2, the developing device 4, and the cleaner 12 are integrally formed as a unit as a process cartridge A, and are detachably attached to the image forming apparatus main body by the attaching means 60. The process cartridge A has a memory 20 as cartridge information storage means.

[Image Forming Process] The photosensitive drum 1 is driven to rotate at a predetermined peripheral speed (process speed) in the direction of the arrow. The charging roller 2 is charged with a voltage obtained by superimposing an AC bias on a DC bias, and charges the photosensitive drum 1 to be uniformly charged to a predetermined polarity and potential (primary charging). The exposure device 3 is a laser beam scanner, outputs laser light on / off modulated in accordance with image information input from an external device such as an image scanner or a computer (not shown), and performs a charging process on the photosensitive drum 1. The surface is scanned and exposed. This scanning exposure forms an electrostatic latent image on the surface of the photosensitive drum 1.

In the developing device 4, a developer (toner) is supplied from the developer carrier 41 to the surface of the photosensitive drum 1, and the electrostatic latent image is visualized as a toner image. In an electrophotographic image forming apparatus such as a laser beam printer, a reversal developing method in which toner is adhered to an exposed portion and developed is generally used.

A transfer material is stored in the paper feed cassette 13, and a paper feed roller group 14 is provided based on a paper feed start signal.
Is driven, the transfer material in the paper feed cassette 13 is fed one by one, and is introduced at a predetermined timing into a transfer portion which is a contact nip between the photosensitive drum 1 and the transfer roller 8 through the registration roller pair 5. Is done. That is, the transfer of the transfer material is controlled by the registration roller pair 5 in synchronization with the timing at which the leading end of the toner image on the photosensitive drum 1 reaches the transfer portion.

The transfer material introduced into the transfer portion is conveyed while nipping the transfer portion. At this time, a constant voltage bias (transfer bias) controlled to a predetermined value is applied to the transfer roller 8 from a transfer bias application power source (not shown). . When a transfer bias having a polarity opposite to that of the toner is applied to the transfer roller 8, the toner image on the surface of the photosensitive drum 1 is electrostatically transferred to the transfer material at the transfer portion.

The transfer material on which the toner image has been transferred at the transfer site is separated and conveyed from the photosensitive drum 1 and conveyed to the fixing device 11 to undergo a fixing step involving heating and pressing of the toner image.

On the other hand, the surface of the photosensitive drum 1 after the transfer and separation is cleaned by a cleaner 12 with toner remaining after transfer and paper dust, and is repeatedly subjected to an image forming process. The transfer material that has passed through the fixing device 11 is directly discharged to the paper discharge tray 15 when single-sided printing is designated.

Next, the control system of this embodiment will be described with reference to the block diagram of FIG.

As described above, the process cartridge A includes the photosensitive drum 1, the charging roller 2, the developing device 4, the cleaner 1,
2 and a cartridge information storage means (hereinafter referred to as “cartridge memory”) 20, but only the photosensitive drum 1, the charging roller 2 and the cartridge memory 20 related to the present invention are shown in the figure.

The high voltage power supply B has a power supply 21 for applying a bias to the charging roller 2 and a load value detecting means 22.

The control section C as control means includes a process cartridge A, a high-voltage power supply B, a CPU 23 for controlling various parts (not shown) of the image forming apparatus, and cartridge information reading means for reading cartridge information from the cartridge memory 20. 24, a load value signal reading means 25 for reading a signal from the load value detecting means 22, and a switching means 26 for switching the magnitude of a bias applied to the charging roller 2.

[Load Detection] A method of detecting a load value by the load value detecting means 22 will be described. FIG. 3 shows the relationship between the voltage Vpp and the current Iac when an AC bias is applied to the contact charging member, that is, the charging roller 2.

A curve 201 shows the characteristics of the photosensitive drum 1 when not in use. When the voltage is lower than the point 226 corresponding to Vpp = V4, the characteristic is linear, and when the voltage is higher than the point 226, the characteristic moves upward from the straight line (broken line portion) in the figure. This indicates that discharge has occurred between the surface of the charging roller 2 and the surface of the photosensitive drum 1 and charging has started. On the other hand, as the number of prints increases, this characteristic becomes
The slope gradually becomes steep, such as 03. This is because the thickness of the charge transfer layer of the photosensitive drum 1 gradually decreases, and the capacitance increases. Therefore,
When a bias is applied at a constant voltage, the discharge increases due to abrasion of the drum. Therefore, a constant current controlled bias is generally applied during image formation.

In the present invention, the ratio between the current Iac and the voltage Vpp at the linear portion of this characteristic is used for judging the drum life.
That is, a load value x defined by x = Iac / Vpp is used. The reason for using x in the linear portion is that the linear portion accurately reflects the thickness of the charge transfer layer of the photosensitive drum as a value inversely proportional to the capacitance at which no discharge occurs.

In this embodiment, as a method for obtaining x, a constant current value I1 lower than that during image formation is applied during non-image formation, the voltage at that time is detected, and x is calculated. Curve 20
The voltages Vpp corresponding to 1, 202 and 203 are V
1, V2 and V3. The value of x is I1 /
V1, I1 / V2, and I1 / V3, and the value of x increases as the film thickness decreases.

[Drum Life Judgment] In this embodiment, a photosensitive drum in which the charge conductive layer is formed of an organic photosensitive member is used. It is experimentally known that fogging occurs when the film thickness is about 5 μm. . Therefore, the value of x when the film thickness is 5 μm is represented by X as a reference value. FIG. 4 shows the relationship between X and X as the number of prints increases. In the test of the present embodiment, as indicated by the curve 227, an image defect occurred at the number of prints N. Therefore, in this embodiment, the load value x is compared with the reference value X, and when the load value x exceeds the reference value X, the life is determined.

The reference value X will be further described. The capacitance is related not only to the film thickness of the drum but also to the capacitance of the charging roller. Although the electrostatic capacity of the charging roller hardly changes due to printing, the initial electrostatic capacity varies. Therefore,
The reference value X differs for each process cartridge. Therefore, in the present invention, the cartridge memory 20 capable of storing the reference value X is provided in the process cartridge A, and the control unit C detects the reference value X stored in the cartridge memory 20 of the process cartridge A and the load value of the high-voltage power supply B. A method of comparing the load value x detected by the means 22 is adopted.

[Control Operation] Referring mainly to FIGS. 2 and 5,
The control operation of this embodiment will be described sequentially.

First, the contents of the cartridge memory 20 provided in the process cartridge A, that is, the reference value X is
The signal line 101 is output by the cartridge information reading means 24.
Is read by the control unit C via the controller (S1). Next, the rotation of the photosensitive drum 1 is started (S2). In response to an instruction from the switching unit 26, an AC bias current Iac lower than normal is applied from the power supply 21 to the charging roller 2 (S
3). At this time, the load value x (=
Iac / Vpp). The load value signal reading means 25 reads the load value x via the signal line 103 (S4). The control unit C compares the read reference value X with the load value x (S5), and if x is smaller, performs normal printing (S7). If x is larger, "warning operation" and "print prohibition operation" as described below are performed (S6).

[Warning Operation / Print Prohibition Operation] In this embodiment, as the warning operation, the display device 50 as a display means provided in the image forming apparatus displays, for example, “Drum life has been detected”, please Exchange"
Is displayed, or a warning operation is performed by, for example, providing an LED to the image forming apparatus and blinking the image forming apparatus. Further, the display means is not limited to the display device 50, but may be a display means such as a screen of a device such as a host computer communicably connected to the image forming apparatus main body.

As the print prohibiting operation, a method is adopted in which the image forming operation is not performed even if a print command is issued.

As described above, according to this embodiment, the drum life could be accurately detected. Further, by performing the print prohibition operation, it was possible to prevent the toner from scattering in the apparatus. Further, by performing the warning operation, it was possible to appropriately inform the user that the drum life has expired.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS. The image forming apparatus according to the present embodiment has substantially the same configuration as that of the first embodiment, and therefore, different portions will be described. The same members as those described above are denoted by the same reference numerals, and description thereof will be omitted.

As described in the section of “Prior Art”,
As a contact charging member, a roller-shaped charging roller in which a conductive elastic layer and a resistance adjusting layer are sequentially formed on a core metal is widely used, but depending on the type of conductive material used as a component of the resistance adjusting layer, FIG. As shown in FIG. 2, some of the sensors have extremely temperature dependence and change in capacitance. In this embodiment,
The purpose is to correct this temperature fluctuation.

As shown in FIG. 7, the image forming apparatus of this embodiment is provided with a temperature sensor 30 as temperature detecting means for measuring the temperature of the atmosphere in which the apparatus is installed. At C, the detection value of the temperature sensor 30 is read via the signal line 105.

FIG. 8 shows a correction coefficient T used for correcting the reference value X, which is corrected by the control unit C using the following equation.

X = T × X A curve 234 is a correction curve representing the relationship between the ambient temperature and the correction coefficient T. The higher the temperature, the larger the value of X, and the lower the temperature, the smaller the value of X. Means that. The correction curve was determined by experimentally determining the temperature dependence in FIG.

When the load value x is compared with the reference value X, the same effect as in the first embodiment can be obtained in this embodiment by using the reference value X corrected for the temperature fluctuation. In addition to the above, the accuracy of detecting the life of the photosensitive drum could be further improved particularly when a charging roller having a temperature fluctuation is used.

Embodiment 3 Next, a third embodiment of the present invention will be described with reference to FIG. The same members as those described above are denoted by the same reference numerals, and description thereof will be omitted.

In the present embodiment, the control unit C of the image forming apparatus, in particular, the CPU 43 can read and write the stored information from / to the memory 40 as the cartridge information storage means via the signal line 104, and the information written by the CPU 43 Is information indicating that the process cartridge A has reached the end of its life.

The method of detecting the life of the photosensitive drum in the present embodiment is the same as in the first and second embodiments, and a description thereof will be omitted.

In this embodiment, when the life of the photosensitive drum 1 is detected, X = 0 is written in the memory 40.

Next, the process cartridge A
If you try to use, for example, (1) When the power is turned on,
(2) When a print command is issued, and (3) when a door is opened or closed, a warning operation and a print prohibition operation are performed directly without performing operations such as idle rotation of the photosensitive drum that is normally performed.

As described above, in the present embodiment, it is not necessary to perform idle rotation of the photosensitive drum for load detection, and it is possible to further prevent toner scattering.

[0066]

As is apparent from the above description, the image forming apparatus of the present invention has the load value detecting means for detecting the ratio of the current to the voltage of the AC component of the bias applied to the charging means. At the time of image formation, a predetermined AC component is applied to the charging unit, and the ratio of the current and the voltage detected by the load value detecting unit at that time is compared with the cartridge information in the cartridge information storage unit. By automatically determining whether to perform or stop the image forming operation according to the image forming operation, the life of the image carrier can be accurately detected, and the fog or the developer caused by the life of the image carrier can be detected. Scattering can be prevented.

According to the present invention, there is provided an image carrier, charging means for charging the image carrier to a predetermined potential, and cartridge information storage means for storing cartridge information. In a possible process cartridge, the cartridge information is a reference value indicating that the life of the image carrier is long, so that the life of the image carrier can be accurately detected. Can prevent fogging or scattering of the developer caused by the above.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram illustrating a control system in the image forming apparatus of FIG. 1;

FIG. 3 is a graph showing the relationship between voltage and current when an AC bias is applied to a charging roller.

FIG. 4 is a graph showing a relationship between the number of prints and a load value x.

FIG. 5 is a flowchart relating to life determination of a photosensitive drum.

FIG. 6 is a graph showing a relationship between a voltage and a current when an AC bias is applied to a charging roller according to a change in an ambient temperature.

FIG. 7 is a block diagram showing another embodiment of the control system in the image forming apparatus of FIG. 1;

FIG. 8 is a graph showing a relationship between a read value of a temperature sensor and a correction coefficient T of a reference value X.

FIG. 9 is a block diagram showing another embodiment of the control system in the image forming apparatus of FIG. 1;

FIG. 10 is a schematic sectional view showing one embodiment of a conventional image forming apparatus.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photosensitive drum (image carrier / electrophotographic photosensitive member) 2 charging roller (charging means) 20, 40 cartridge memory (cartridge information storage means) 21 power supply 22 load value detection means 24 cartridge information reading means 25 load value signal reading means 26 Switching means 30 Temperature sensor (temperature detecting means) A Process cartridge B High-voltage power supply means C Control unit (control means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/02 102 G03G 15/00 556 F term (Reference) 2H003 AA01 AA11 BB11 CC04 DD03 DD06 2H027 DA01 DA13 DA27 DD09 DE07 EA01 EJ08 EJ15 EK03 GB07 HA01 HB01 HB05 HB15 HB17 2H071 BA03 BA33 BA34 DA06 DA15 DA31 DA32

Claims (14)

[Claims] 1. An image forming apparatus in which a process cartridge including an image carrier, charging means for charging the image carrier to a predetermined potential, and cartridge information storage means for storing cartridge information is detachable. A load value detecting means for detecting a ratio of a current and a voltage of an AC component of a bias applied to the means, and applying a predetermined AC component to the charging means during non-image formation; Comparing the ratio of the current and the voltage detected by the means with the cartridge information of the cartridge information storage means, and according to the comparison result,
An image forming apparatus for automatically determining whether to perform or stop an image forming operation. 2. The image forming apparatus according to claim 1, further comprising a high-voltage power supply including a power supply for applying a bias in which an AC component and a DC component are superimposed on the charging unit, and the load value detection unit. . 3. A cartridge information reading means for reading the cartridge information from the cartridge information storage means, a load value signal reading means for reading a signal from the load value detecting means, and a magnitude of a bias applied to the charging means. 3. The image forming apparatus according to claim 1, further comprising a control unit including a switching unit. 4. A temperature detecting means for detecting an ambient temperature of the apparatus, wherein the temperature detecting means detects
A value obtained by correcting the value of the cartridge information read from the cartridge information storage unit and a ratio of current and voltage detected by the load value detection unit at the time of applying a predetermined AC component during non-image formation, 4. The image forming apparatus according to claim 1, wherein the image forming apparatus automatically determines whether to perform or stop the image forming operation in accordance with a result of the comparison. 5. The control means can read and write information stored in the cartridge information storage means, and the information written by the control means is information indicating that the process cartridge has reached the end of its life. 5. The image forming apparatus according to claim 3, wherein: 6. When stopping the image forming operation,
6. The image forming apparatus according to claim 1, wherein warning information is displayed on a display unit. 7. The image forming apparatus according to claim 6, wherein a signal for displaying said warning information is transmitted to said display means and displayed. 8. A communication device capable of communicating with a device having the display means, and transmitting a signal for displaying the warning information to the device having the display means.
Image forming apparatus. 9. The image forming apparatus according to claim 1, wherein the cartridge information is a reference value indicating that the image carrier has reached the end of its life. 10. The image forming apparatus according to claim 9, wherein the reference value is a value unique to each process cartridge. 11. The image forming apparatus according to claim 9, wherein the reference value is a value related to a film thickness of the image carrier and a capacitance of the charging unit. 12. A process cartridge which has an image carrier, charging means for charging the image carrier to a predetermined potential, and cartridge information storage means for storing cartridge information, wherein the process cartridge is detachable from the image forming apparatus main body. The cartridge information is a reference value indicating that the image carrier has reached the end of its life. 13. The process cartridge according to claim 12, wherein the reference value is a value unique to each process cartridge. 14. The process cartridge according to claim 12, wherein the reference value is a value related to a thickness of the image carrier and a capacitance of the charging unit.