JP2003287986A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of applying optimum transfer bias by appropriately calculating the film thickness of a photoreceptor drum and detecting the life of a process cartridge in accordance with the calculated result. <P>SOLUTION: The image forming apparatus has image carriers 11 to 14, electrifying means 21 to 24 electrifying the image carriers 11 to 14, transfer means 51 to 54 transferring developer on the image carriers 11 to 14 to transfer material P, and a transfer material P detection means 80. In the apparatus, the information of the detection means 80 is stored and the thickness of photoreceptive layers on the image carriers 11 to 14 is decided based on the information of the detection means 80, the driving time of the image carriers 11 to 14 and the bias applying time of the electrifying means 21 to 24. <P>COPYRIGHT: (C)2004,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 an electrophotographic copying machine and a laser beam printer.

[0002]

2. Description of the Related Art As a known image forming apparatus using an electrophotographic recording system, for example, a laser beam printer is a photosensitive drum as an image carrier to be rotationally driven, and a charging means for uniformly charging the surface of the photosensitive drum. As a charging roller, a laser for exposing the surface of the photosensitive drum to form an electrostatic latent image corresponding to an image signal, a developing unit for developing the electrostatic latent image with toner to form a visible image, a visible image (developer) image)
Transfer roller for transferring the sheet onto a recording sheet as a sheet,
It is provided with a fixing unit for fixing the visible image transferred on the recording sheet, a cleaning unit, and the like.

In this image forming apparatus, the photosensitive drum and the charging roller are integrally formed as a cartridge with the cleaning means and the developing means, and the cartridge (hereinafter referred to as a process cartridge) is made detachable. , Which realizes a maintenance-free image forming apparatus are known.

In such an image forming apparatus, the entire process cartridge is replaced when the functions of the components incorporated in the process cartridge deteriorate due to, for example, long-term use.

This replacement work is a very simple operation in which the main body of the image forming apparatus is opened with one touch, the old process cartridge is taken out from the inside of the main body of the image forming apparatus, and a new unused process cartridge is mounted in the main body of the image forming apparatus. Therefore, it can be easily implemented by the operator himself.

The life of this process cartridge is mainly
It is determined by the wear of the photosensitive drum and the consumption of toner.

As a technique for managing the life of the photosensitive drum, for example, as disclosed in Japanese Patent Application Laid-Open No. 09-179460, there is a technique in which the application time of the charging bias is integrated to make a determination.

Since the user can arbitrarily replace the process cartridge, it is desirable that the life information of the photosensitive drum is stored in the process cartridge.

For example, a method of storing life information in a memory mounted on a process cartridge is known.

On the other hand, it is known that the resistance value of a transfer roller for transferring an image on a recording sheet changes according to changes in the environment.

When the resistance value of the transfer roller becomes high, it becomes difficult to draw the toner on the photosensitive drum to the paper, so that the transfer bias must be increased.

A technique for optimizing the transfer by controlling the transfer bias against the change of the resistance value is disclosed in Japanese Patent No. 26.
14309.

In this technique, when the photosensitive drum and the transfer roller are in contact with each other, the resistance value of the transfer roller is calculated by applying a reference current and measuring the voltage.

[0014]

However, the photosensitive drum wears due to the unevenness of the transfer material.

Therefore, when the life of the photosensitive drum is detected, the detection may be deviated only by integrating the application time of the charging bias.

Further, when the resistance value of the transfer roller is calculated, as described above, the voltage value at the reference current applied to the transfer roller is measured, so that the film thickness of the photosensitive drum is worn. As a result, the voltage applied to the surface of the photosensitive drum and the transfer roller varies.

For example, when the film thickness is thin, the capacity increases and a current easily flows, so that a transfer roller having a high resistance may detect a low voltage and be determined as a transfer roller having a low resistance.

Therefore, when the film thickness of the photosensitive drum is thin,
It is necessary to calculate the resistance value of the transfer roller by adding the amount of decrease in the voltage applied to the photosensitive drum.

However, the provision of a new detecting means for measuring the film thickness of the photosensitive drum leads to an increase in the size of the apparatus, and therefore a simple method is desired.

The present invention has been made in view of the above problems, and an object of the present invention is to accurately detect the life of a process cartridge and to make the transfer of a transfer roller always good. Another object of the present invention is to provide an image forming apparatus capable of appropriately calculating the film thickness of the photosensitive drum, detecting the life of the process cartridge accordingly, and applying an optimum transfer bias.

[0021]

Therefore, in the present invention, the above object is achieved by providing an image forming apparatus shown in any one of the following items (1) to (5). Is.

(1) In an image forming apparatus having an image carrier, a charging unit for charging the image carrier, a transfer unit for transferring the developer of the image carrier to a transfer material, and a detection unit for the transfer material. The information of the transfer material detecting means is stored, and the thickness of the photosensitive layer of the image bearing material is determined from the information of the transfer material detecting means, the driving time of the image carrier, and the bias application time of the charging means. An image forming apparatus characterized by the above.

(2) An image forming apparatus in which a process cartridge having at least an image carrier and a charging means for charging the image carrier is detachable, wherein the process cartridge has a non-volatile memory and a photosensitive layer. The image forming apparatus according to (1) above, wherein thickness information is stored in the non-volatile memory.

(3) The image forming apparatus described in the item (1), wherein the transfer material detecting means detects the roughness of the surface of the transfer material.

(4) The above-mentioned item (1) is characterized in that it further comprises a judging means for judging the thickness of the photosensitive layer of the image carrier by the judging means to detect the life of the image carrier. Image forming apparatus.

(5) Further, a determining means is provided, and the thickness of the photosensitive layer of the image carrier is determined by the determining means, and the charging condition, the exposure condition, the developing condition and the transfer condition are controlled according to the result. The image forming apparatus described in the item (1).

The details will be described below.

To achieve the above object, in the present invention, an image carrier, a charging means for charging the image carrier, and a transfer means for transferring the developer of the image carrier to a transfer material by controlling a transfer bias. And an image forming device having a transfer material detecting means, storing information of the transfer material detecting means, and using the information of the transfer material, the drive time of the image carrier, and the bias application time of the charging means, the image carrier An image forming apparatus is provided which determines the thickness of the photosensitive layer.

Also provided is an image forming apparatus for correcting the transfer bias from the information on the thickness of the photosensitive layer and the information on the detecting means of the transfer material.

Further, there is provided an image forming apparatus in which a process cartridge having at least an image carrier and a charging means for charging the image carrier is detachable, the process cartridge having a non-volatile memory, and information relating to the thickness of a photosensitive layer. There is provided an image forming apparatus which stores the data in a non-volatile memory.

In such an image forming apparatus, since the film thickness of the photosensitive drum can be calculated corresponding to the history of the durable transfer material, the optimum transfer bias can be controlled and applied, and each photosensitive drum can be applied. Thus, the transfer to the transfer material can always be kept in a good state.

Similarly, it is possible to adjust the image density which changes depending on the film thickness of the photosensitive drum.

Moreover, the life of the photosensitive drum can be detected corresponding to the transfer material.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail and specifically with reference to the drawings using an embodiment of an in-line type color printer.

The present invention is not limited to the form of the apparatus, but can be implemented in the form of a method supported by the description of the embodiments.

(Embodiment 1) FIG. 1 is a sectional view showing a schematic structure of an image forming portion of a color image forming apparatus utilizing an electrophotographic process according to Embodiment 1 of the present invention.

Reference numerals 11 to 14 designate rotating drum type electrophotographic photosensitive members (hereinafter referred to as photosensitive drums) 21 which are image bearing members.
-24 are primary charging rollers 31-34 which are charging means.
Is a cleaning means, 41 to 44 are cleaning containers,
51 to 54 are transfer rollers, which are transfer means, and 61 to 64.
Is a developing device, 71 to 74 are cartridge memories which are non-volatile memories, 80 is a paper detecting means which is a detecting means of a transfer material, 84, 85 and 86 are paper guides, 100 is an image forming section, 101 to 104 are Color station, 121-1
Reference numeral 24 denotes the photosensitive drums 11 to 14 and the primary charging roller 21.
To 24, cleaning means 31 to 34, cleaning containers 41 to 44, developing devices 61 to 64, and cartridge memories 71 to 74,
P is a transfer material.

In FIG. 1, the image forming unit 100 is a color station as Y (yellow), M (magenta), C (cyan), and K (black) image forming units arranged in a line in a vertical direction. 101 to 104 and transfer rollers 51 to 54 as transfer members, the transfer material P is conveyed to the color stations 101 to 104, and the toner images formed in the color stations 101 to 104 are transferred by the transfer rollers 51 to 54. By transferring, a full color image is formed on the transfer material P.

Here, the color stations 101 to 10
4 are process cartridges 121 to 124, respectively.
And the transfer rollers 51 to 54, which are repeatedly used as an image carrier, and which are driven to rotate counterclockwise at a predetermined peripheral speed (process speed), and the photosensitive drum 11. Primary charging rollers 21 to 24 for uniformly charging the surfaces of
And developing devices 61 to 64, which are developing devices for developing the electrostatic latent images formed on the photosensitive drums 11 to 14, and exposing the photosensitive drums 11 to 14 to form electrostatic latent images. It is provided with a non-exposed image exposure means and cleaning means 31 to 34 for removing the toner on the photosensitive drums 11 to 14.

In this embodiment, the photosensitive drums 11 to 14 are negatively charged OPC photoconductors having a diameter of 30 mm, and the peripheral speed thereof is 100 mm / sec.

Further, the primary charging rollers 21 to 24 constitute a DC contact charging type charging device which is driven and contacted by the photosensitive drums 11 to 14 to perform charging, and the primary charging roller applies a DC voltage of -1.2 Kv. The photosensitive drum 1 by the charging rollers 21 to 24
Surfaces 1-14 are charged to -600v.

As shown in FIG. 1, the developing devices 61 to 64 contain a so-called non-toner toner storage portion that does not include magnetic materials of Y, M, C, and BK therein, and a rotation drive (not shown). A developing roller that rotates in a forward direction with respect to the photosensitive drums 11 to 14 by an apparatus, and a variable voltage is applied to the developing roller according to a signal from a controller (not shown). The electrostatic latent image thus formed is developed, and is disposed so as to face the photosensitive drums 11 to 14.

The image exposure means (not shown) is composed of a laser diode, a polygon scanner, a lens group and the like. By receiving image exposure from this image exposure means, the photosensitive drums 11-14 are exposed. Form electrostatic latent images corresponding to the first to fourth color component images (for example, yellow, magenta, cyan, and black component images) of the target color image.

In this embodiment, the image exposure means is a polygon scanner using a laser diode.

Further, the writing of the laser exposure is carried out by BD for each scanning line in the main scanning direction (direction orthogonal to the progress of the transfer material).
Each of the color stations 101 to 104 is delayed by a predetermined time from a position signal in the polygon scanner called a TOP signal in the sub-scanning direction (moving direction of the transfer material) starting from a switch in the conveyance path. In the configuration, the photosensitive drums 11 to 14 can be exposed at the same timing so that they can be transferred to the same position on the transfer material P at all times.

In the present embodiment, the image forming apparatus has been described above in order to minimize the ground contact area and to achieve the desired purpose by opening and closing only the front door for cartridge replacement and jam processing. To color station 1
01 to 104 are arranged vertically, and the main body is divided between the transfer rollers 51 to 54 and the color stations 101 to 104.

The transfer rollers 51 to 54 are
It is in contact with the photosensitive drums 11 to 14 via the transfer material P.

In this embodiment, the transfer rollers 51 to 54 are urethane foam rubber rollers having a volume resistivity of 105 to 106 Ωcm.

This resistance value has a temperature of 23.5.
C., relative humidity is 60%, and applied voltage is 100V.

The transfer rollers 51 to 54 are in contact with the photosensitive drums 11 to 14 at a total pressure of 9.8 N.

Next, the path of the transfer material P thus constructed will be described.

The thickness and surface roughness of the fed transfer material P are detected by the paper detecting means 80.

After that, the color stations 101 to 10
The transfer material P moves upward at the timing of 4.

The first color station 1
01, the color station 101 of the first color (Y)
The toner image formed on the photosensitive drum 11 is transferred by the transfer roller 51.

Similarly, each color station 102-1
At 04, the toner images on the photosensitive drums 12 to 14 are transferred while being sequentially overlapped.

The transfer material P passes between the photosensitive drum 12 and the transfer roller 52, between the photosensitive drum 13 and the transfer roller 53, and between the photosensitive drum 14 and the transfer roller 54.

Finally, the color image is printed by being guided to a fixing unit (not shown).

It is known that the photosensitive drum wears in proportion to the number of rotations, but deterioration of discharge due to charging and paper with a rough surface also promote wear.

The discharge chemically weakens the molecular structure of the surface of the photosensitive drum to promote abrasion.

On the other hand, the paper whose surface is rough promotes abrasion of the photosensitive drum by directly rubbing and abutting the photosensitive drum.

Further, the paper dust released from the paper having a rough surface promotes the abrasion of the photosensitive drum due to the polishing effect and the like.

Next, the main body control section of the image forming apparatus and the cartridge memory will be described with reference to FIG.

FIG. 2 is a block diagram of the non-volatile cartridge memory which is the storage element of the process cartridge and the main body control section.

1 is a transfer control means, 2 is a drum film thickness correction means which is a judgment means, 3 is a drum total rotation time storage means,
Reference numeral 4 is a charging bias total application time storage means, 5 is a motor control means, 6 is a charging control means, 7 is a paper roughness calculation means, 8 is a paper roughness total storage means, 9 is a main body control section, and 15 is a printed sheet number storage. Means, 16 is a paper roughness average value calculating means, and 50 is a high voltage power source.

The cartridge memories 71 to 74 are
Since all have the same structure, only the cartridge memory 71 is shown here.

The motor control means 5 stores the drum rotation time in the drum total rotation time storage means 3 of the cartridge memory 71, and the charging control means 6 stores the charging bias application time in the charging bias total application time storage means 4. .

In the present embodiment, the paper roughness calculating means 7 is
Information on the roughness of the passed paper is stored in the paper roughness total storage means 8.

The number of printed sheets is stored in the printed sheet number storage means 15 by the paper detection means or the like.

The average value of the roughness of the passed paper is calculated by the paper roughness average value calculating means 16 from the information of the paper roughness and the number of printed sheets.

In addition to the information on the average value of the roughness of the passed paper,
The drum film thickness correction unit 2 calculates the drum film thickness based on the information in the drum total rotation storage unit 3 and the charging bias total application time storage unit 4.

Hereinafter, the film thickness of the photosensitive drum (the thickness of the photosensitive layer)
The calculation will be described.

In this embodiment, the average value of the roughness of the passed paper, the rotation time of the photosensitive drum, and the application time of the charging voltage are used as the factors related to the film thickness of the drum, and their influence on the film thickness of each drum. Considering the degree.

Based on the above concept, it is determined that the following expression (1) is related to the decrease L in the film thickness of the drum.

L = β (D + αH) + Dγ (R−R0) (1) In the above equation, L: film thickness reduction D: drum total rotation time (drum total drive time) H: charging bias total application time R: average value of the roughness of the passed paper R0: roughness of the reference paper Also, α represents the ratio of the degree of influence on the drum film thickness per unit time when the charging voltage is ON and when the charging voltage is OFF. It is a coefficient.

Further, β is a coefficient indicating the ratio of the total drum rotation time to the drum film thickness reduction.

Further, γ is a coefficient showing the degree of contribution of the film thickness reduction due to the roughness of the passed paper.

With this formula (1), the number of revolutions of the photosensitive drum and the film thickness due to the charge deterioration are measured, and then the contribution degree of the paper is adjusted to the experimental value of γ and substituted into the formula (1). it can.

D is the total drum rotation time storage means 3,
H is stored and managed in the charging bias total application time storage means 4.

The values of R, R0, α, and β are the values obtained by experiments,
And a value that is statistically obtained in advance can be set.

For example, in the reference paper R = R0, when only the DC bias is applied as the charging, the charging voltage ON is largely 20% of the photosensitive drum in the same rotation time as the charging voltage OFF.

In this case, by setting α = 0.2 in the equation (1), the degree of influence of the charging voltage on the photosensitive drum can be reflected in the equation.

Β is determined by the relationship between the total drum rotation time and the film thickness, and in this embodiment, 0.4 μm per 20 seconds.
Since it was scraped, β = 0.4 (μm) ÷ 20 (sec) =
It becomes 0.02 (μm / sec).

That is, the equation (1) in this case is as follows: when R = R0, L = β (D + αH) + Dγ (R−R0) = 0.02 (D + 0.2H) [μm / sec].

Next, as the paper rougher than the reference paper, the roughness R1 is used.
When the paper of (μm) is used, the formula (1) is L = β (D + αH) + Dγ (R−R0) = 0.02 (D + 0.2H) + Dγ (R1-R0) [μm / sec] .

If the amount L of decrease in the thickness of the photosensitive drum can be calculated in this way, the thickness of the photosensitive drum can also be calculated.

The information on the paper and the information on the storage element of each process cartridge are collected by the transfer control means 1 and used to control the transfer bias after calculating the film thickness reduction L of the photosensitive drum according to the equation (1). It

An apparatus for measuring the surface roughness of a transfer material such as paper will be described with reference to FIG.

FIG. 3 is an explanatory view of the paper detecting means in the first embodiment.

Reference numeral 81 is a light source, 82 is a lens, and 83 is a CCD.
Image sensor (charge transfer device Charge Coupled Devic
e).

As shown in FIG. 3, the paper detection means 80 has paper guides 84, 8 for conveying the transfer material P to a fixed detection position.
5, 86, a light source 81 for irradiating the surface of the transfer material P with a constant light amount, a lens 82 for collecting an image of the irradiation light from the light source 81 reflected on the surface of the transfer material P, and a light collection. It is composed of a CCD image sensor 83 for measuring an image.

The unevenness image (information of the transfer material detecting means) measured by the CCD image sensor 83 is detected by the paper roughness calculating means 7 as shown in FIG.

By selecting an optimum threshold value according to the depth of the unevenness of the transfer material, it is possible to associate the surface roughness of the transfer material with the number exceeding the threshold value.

In other words, a rough transfer material has a large value, and a slippery transfer material has a small value.

The paper roughness calculating means 7 using this method can accurately determine the surface roughness of transfer materials of different qualities without contact.

The surface roughness of the transfer material measured here is used for calculating the average value and calculating the film thickness reduction L of the drum film thickness as described above.

Next, the bias control for the transfer rollers 51 to 54 will be described.

During pre-multi-rotation before image formation, the surfaces of the photosensitive drums 11 to 14 are first uniformly charged to a predetermined polarity and potential by the charging rollers 21 to 24 during the rotation process of the photosensitive drums 11 to 14. .

Next, a predetermined transfer bias, for example, +2.
By applying a reference current of 0 μA, each transfer roller 51-54
The voltage value V0 is measured.

At this time, since no paper is used as a transfer material, the voltage applied in series to the photosensitive drums 11-14 and the transfer rollers 51-54 is measured.

This voltage value V0 is stored in the transfer control means 1.

Assuming that the bias applied with optimum control during sheet passing transfer is V, V = kV0-V1 (2) V0: voltage with respect to reference current V1: correction voltage depending on thickness of photosensitive drum.

In the equation (2), the voltage V0 is multiplied by the ratio k of the transfer bias required to transfer the toner under the conditions of the reference paper and the initial photosensitive drum.

Further, the transfer control means 1 obtains the correction voltage V1 depending on the thickness of the photosensitive drum, which is the voltage decrease due to each photosensitive drum, from the look-up table in which the reduction L of the thickness of the photosensitive drum is taken into consideration, and the expression ( According to 2), the optimum transfer bias V is calculated.

The decrease L in the thickness of the photosensitive drum is utilized in the surface of the photosensitive drums 11-14 and the transfer rollers 51-54.
This is because the voltage applied to V fluctuates depending on the film thickness of the photosensitive drums 11-14.

For example, as the film thickness becomes thinner, the capacity increases and the current easily flows, so that the transfer rollers 51 to 5 having high resistance.
Even in No. 4, a low voltage is detected, and it may be determined as a transfer roller having a low resistance.

Therefore, when the film thickness of the photosensitive drums 11 to 14 is thin, the resistance values of the transfer rollers 51 to 54 are calculated in consideration of the amount of decrease in the voltage applied to the photosensitive drums 11 to 14.

In the image forming apparatus of this embodiment, 110 μm paper is used as the reference paper, and the initial drum film thickness is 20 μm.
When m, the voltage V0 corresponding to the reference current of 2.0 μA at 23 ° C. and 60% was V0 = 1500V, and the optimum bias V for transfer was 2250V.

From equation (2), k was 1.5.

The reference voltage of 15 ° C. and 10% is the transfer roller 5
Since the resistance values of 1 to 54 increased, V0 increased to 2000V.

As a part of the concrete example, the following table shows the numerical values for correction by the thickness of the paper and the photosensitive drum.

[0111]

[Table 1] As described above, by controlling the transfer bias, it is possible to always obtain good transferability even when a paper having an arbitrary thickness is passed when the photosensitive drum wears and becomes thin due to durability.

Information regarding the film thickness of the photosensitive drum is as follows:
Information is stored in the memories 71 to 74 fixed to the process cartridges 121 to 124.

Therefore, even if the user replaces the process cartridge with another process cartridge, the optimum transfer bias can always be corrected by the information relating to the film thickness stored in the memories 71 to 74.

(Embodiment 2) This embodiment 2 is based on the equation (1) for calculating the film thickness reduction L of the photosensitive drum of the embodiment 1.
An image forming apparatus that calculates the film thickness of the photosensitive drum, sets charging conditions, exposure conditions, developing conditions, transfer conditions, controls the density, and detects the life according to the film thickness of the photosensitive drum. Will be described.

A block diagram of this image forming apparatus is shown in FIG.

Reference numeral 10 is a life determining circuit, 19 is an image density control means, and 20 is a laser control means.

Since the other structures are the same as those shown in the first embodiment, the same structures are designated by the same reference numerals and detailed description thereof will be omitted.

The image density control means 19 controls at least one of the high voltage power source 50 for charging, developing and transferring, and the laser control so that the developing contrast is reduced even when the photoconductor film thickness is reduced and the potential of the electrostatic latent image portion is lowered. Control to maintain.

For example, increase the DC voltage component of charging (-
For example, 600 V is set to -550 V, the DC voltage component of the developing bias is lowered (-400 V is set to -450 V), and the laser light amount is increased.

When the film thickness of the photosensitive drums 11 to 14 becomes thin and falls below a predetermined value, the life determining circuit 10 sends a signal to the display unit, which indicates that the photoconductor has reached the end of its life.

As described above, since the film thickness of the photosensitive drum can be accurately calculated in accordance with the sheet passing history of the transfer material as in the first embodiment, appropriate charging conditions, exposure conditions, It is possible to set developing conditions and transfer conditions, and to improve the accuracy of density control and life detection.

Next, the characteristic operation of the second embodiment will be described with reference to FIG.

FIG. 6 is a flow chart schematically showing the operation of the second embodiment.

First, in steps S1 to S3, the roughness of the paper is detected using the paper detection means 80, and the detected paper roughness information is stored in the paper roughness total storage means 8 via the paper roughness calculation means 7. The average value R of the paper roughness is calculated by using all the information stored in the paper roughness total storage means 8 and the number of printed sheets stored in the printed sheet number storing means.

Next, in S4, the photosensitive drum rotational speed is read from the drum total rotational speed time storage means 3.

Then, in step S5, the charging voltage application time is read from the charging bias total application time storage means 4.

Note that S1 to S3, S4, and S5 may be performed in any order.

Next, in S6, based on these information,
The drum film thickness correction means 2 calculates the film thickness reduction L of the photosensitive layer.

Then, in S7, the thickness of the photosensitive layer is calculated from the initial thickness of the photosensitive layer and the decrease L in the photosensitive layer thickness obtained in S5.

Then, in step S8, appropriate charging conditions, exposure conditions, developing conditions, transfer conditions are set, and the density is controlled by using the image density control means 19 and the life determining circuit 10 according to the thickness of the photosensitive layer. , Lifespan detection, etc.

By accurately calculating the thickness of the photosensitive layer in this manner, it becomes possible to appropriately set transfer conditions, control density, and detect life.

[0132]

As described above, according to the present invention, since the film thickness of the photosensitive drum can be calculated corresponding to the history of the durable transfer material, the optimum transfer bias can be controlled and applied. Thus, it is possible to provide an image forming apparatus capable of always maintaining a good transfer state on a transfer material with each photosensitive drum.

Similarly, it is possible to adjust the image density which changes depending on the film thickness of the photosensitive drum.

Moreover, the life of the photosensitive drum can be detected corresponding to the transfer material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming unit of an image forming apparatus according to a first exemplary embodiment.

FIG. 2 is a block diagram of a storage element and a main body control unit of the process cartridge according to the first embodiment.

FIG. 3 is an explanatory diagram of a paper detection unit according to the first embodiment.

FIG. 4 is an explanatory diagram of roughness calculation according to the first embodiment.

FIG. 5 is a block diagram of an image forming apparatus according to a second embodiment.

FIG. 6 is a flowchart schematically showing the operation of the second embodiment.

[Explanation of symbols]

1 Transfer Control Means 2 Drum Thickness Correcting Means 3 Drum Total Rotation Time Storage Means 4 Charging Bias Total Application Time Storage Means 5 Motor Control Means 6 Charge Control Means 7 Paper Roughness Calculation Means 8 Paper Roughness Total Means Storage 9 Body Control Part 10 Life judgment circuit 11-14 Photosensitive drum 15 Number of printed sheets storage means 16 Paper roughness average value calculation means 19 Image density control means 20 Laser control means 21-24 Primary charging rollers 31-34 Cleaning means 41-44 Cleaning container 50 High-voltage power sources 51 to 54 Transfer rollers 61 to 64 Developing devices 71 to 74 Cartridge memory 80 Paper detecting means 81 Light source 82 Light collecting lens 83 CCD image sensor (Charge transfer device Charge Cou
pled Device) 84-86 Paper guide 100 Image forming section 101-104 Color station 121-124 Process cartridge P Transfer material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazushi Inou             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Toru Saito             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Kazunari Murayama             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 2H027 DA39 DA45 DC02 DE02 EA02                       EA03 EA05 EC06 EC07 EC20                       GB07 HB02 HB14 ZA07                 2H171 FA02 FA09 FA11 FA22 FA24                       GA01 GA25 JA23 JA27 JA29                       JA31 JA50 QA03 QA04 QA08                       QA15 QA16 QA17 QB03 QB09                       QB15 QB22 QB41 QB49 QC03                       QC11 QC14 SA09 SA14 SA22                       SA26 TA02 TA07 TA08 TA15                       TA17 TB02 TB13 UA03 UA08                       WA21                 2H200 FA02 FA18 GA09 GA10 GA12                       GA14 GA23 GA30 GA34 GA46                       GA47 GA52 GA56 HA02 HA29                       HA30 HB12 HB22 HB48 JA02                       JA25 JA26 LA18 LA19 LA23                       LA38 MA03 MA08 MB06 MC06                       NA02 NA09 PA02 PA24 PA27                       PB24 PB33 PB35 PB39

Claims (5)

[Claims] 1. An image forming apparatus comprising an image carrier, a charging unit for charging the image carrier, a transfer unit for transferring a developer of the image carrier to a transfer material, and a transfer material detecting unit. Information of the transfer material detecting means is stored, and the thickness of the photosensitive layer of the image carrying material is determined from the information of the transfer material detecting means, the image carrier driving time, and the charging means bias applying time. An image forming apparatus characterized by. 2. An image forming apparatus in which a process cartridge having at least an image carrier and charging means for charging the image carrier is detachable, wherein the process cartridge has a non-volatile memory and a thickness of a photosensitive layer. The image forming apparatus according to claim 1, wherein information is stored in the non-volatile memory. 3. The image forming apparatus according to claim 1, wherein the transfer material detection unit detects surface roughness of the transfer material. 4. The image forming apparatus according to claim 1, further comprising a determining unit, wherein the determining unit determines the thickness of the photosensitive layer of the image carrier to detect the life of the image carrier. . 5. A determination means is further provided, wherein the thickness of the photosensitive layer of the image carrier is determined by the determination means, and charging conditions, exposure conditions, development conditions and transfer conditions are controlled according to the results. The image forming apparatus according to claim 1.