JP2001147620A - Electrophotographic image forming device and cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic image forming device, which can always optimize an image forming condition for each of cartridges regardless of cartridge replacement or a difference of conditions for use, and a cartridge. SOLUTION: A CPU 20 reads present environmental condition (temperature and humidity) and absolute time from a temperature and humidity sensor 33 and a clock 24 and reads out an environmental condition, an absolute time, and gradation characteristics (difference data) at the time of preceding control from a non-volatile RAM 30a of a control object, for example, a development cartridge 4a for yellow. These information are compared to perform process control like halftone control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electrophotographic image forming apparatus such as a printer or a copying machine, and a cartridge detachably mountable to the image forming apparatus.

[0002]

2. Description of the Related Art FIG. 8 shows an example of a conventional electrophotographic image forming apparatus. In FIG. 1, an image forming apparatus includes an organic photoconductor (OPC) or an A-
A photosensitive drum 101, which is an electrophotographic photosensitive member formed by applying a photoconductor made of Si, CdS, Se, or the like, is provided. The photosensitive drum 101 is driven in a direction indicated by an arrow by driving means (not shown). It is driven and uniformly charged to a predetermined potential by a roller charger 102 as a charging means.

A laser diode 111 constituting an exposure device as an electrostatic latent image forming means, a polygon mirror 109 rotated and driven by a high-speed motor 108,
The lens 110 and the folding mirror 107 are arranged.

When an image signal is input to the laser driver 112, the laser driver 112 causes the laser diode 111 to emit light. Then, light having optical information corresponding to the image signal passes through the optical path 113 to the photosensitive drum 10.
1 to form an electrostatic latent image. When the photosensitive drum 101 further moves in the direction of the arrow, this electrostatic latent image is developed by a developing device (developing means) 104 to become a toner visible image. The developed toner visible image is transferred onto a transfer paper P as a recording medium by a transfer roller 103 as a transfer unit to which a predetermined bias is applied. The transfer paper P is conveyed to the fixing device 105 by the conveying device, and the toner visible image is fused and fixed by the fixing device 105 to be a permanent image.

On the other hand, the toner remaining on the photosensitive drum 101 is cleaned by a cleaning device 106 such as a fur brush or blade means.

In an electrophotographic image forming apparatus that outputs a gradation image, the relationship between an input image signal and an output image, ie, gradation characteristics, is generally as shown in FIG. Normally, with this default gradation characteristic,
Since high image quality cannot be obtained, the input image signal actually has a gradation characteristic by a look-up table (hereinafter, referred to as “LUT”) formed in a RAM in the memory 121 before entering the laser driver 112. Adjustment is made so as to obtain an appropriate relationship such as a linear relationship. Therefore,
A density detection toner image (hereinafter, referred to as a “patch”) is formed on the photosensitive drum 1 based on all image signals that can be handled.
01, and the density of those toner images is detected by an optical density sensor 122 or the like, and the gradation characteristics of the image forming apparatus at that time are obtained from the detection result.
By performing halftone control for creating an LUT based on this, an accurate desired gradation characteristic can be obtained.

More specifically, in FIG.
, A signal for forming a patch pattern is input to the laser driver 112 to form a visible image on the photosensitive drum 101, which is detected by the optical density sensor 122, and a LUT is stored in the RAM in the memory 121 based on the result. Is created.

However, in this method, for example, when the image signal is 8 bits, 256 types of image data can be handled, so that 256 types of patches are created.
A large amount of toner and time will be spent to find the LUT. Therefore, as shown in a1 to a10 in FIG. 9, several representative image signals whose density changes at appropriate intervals are selected in advance, and a patch is created using these image signals. The density of the image signal versus the density of the patch is measured by measuring the density of the patch, and the tone characteristic is obtained by interpolating the data to obtain the tone characteristic, and further, the halftone control method of forming the LUT is adopted. By this method, an image having desired gradation characteristics is obtained while toner consumption is minimized.

However, the gradation characteristics shown in FIG. 9 are obtained when the image forming apparatus is in a normal temperature and normal humidity environment (about 23 ° C., about 60%). Depending on the environment around the image forming apparatus, the gradation characteristics shown in FIG. This may not be the case, and may be as shown in the graph of FIG. 10 or FIG. FIG. 10 shows gradation characteristics under a high temperature and high humidity environment (about 30 ° C., about 80%).
Represents the gradation characteristics under a low-temperature and low-humidity environment (15 ° C., 10%).

Therefore, when the image forming apparatus is in a high-temperature and high-humidity environment and the actual tone characteristics are as shown in FIG. 10, if a patch is created with an image signal similar to that of FIG. Since only patches are created and patches of intermediate density portions are missing, there is a possibility that corrections may not be performed correctly.

On the other hand, when the actual tone characteristics are as shown in FIG. 11, when a patch is created with an image signal similar to that of FIG. 9, only a low-density patch is created. Correction may not be performed correctly because a patch is missing.

[0012]

As a method for preventing the above-mentioned inconvenience, the result of the previous halftone control is stored, and in the next control, the steps of the image density are equally spaced. A method for adjusting the values of a1 to a10 (see Japanese Patent Application Laid-Open No. H11-167320) and an atmosphere of the apparatus main body at the time of control, that is, parameters including values of a1 to a10 at the time of halftone control using temperature and humidity are used. A method of correcting is conceivable.

However, for example, when the atmosphere of the apparatus main body changes abruptly, the toner in the photosensitive drum, the toner in the developing apparatus, or the process cartridge including the toner cannot follow the change in the surrounding environment, and the halftone control is not performed. There is a possibility that erroneous correction (for example, when the atmosphere in the apparatus main body is changing in the low humidity direction, but the toner in the developing apparatus keeps absorbing moisture under high humidity).

In an image forming apparatus such as a full-color printer which has been rapidly developing in recent years, developers of four colors such as yellow (Y), magenta (M), cyan (C) and black (BK) are used, respectively. In most cases, a method of forming an image on one or four photosensitive drums using a stored developing cartridge is used. In this case, for example, printing using only BK and printing using four colors are performed. Are performed, and the final use time and use history of each developing cartridge or photosensitive drum differ.

In such a case, the halftone control method is corrected for each developing cartridge (developing device) and photosensitive drum using the previous control result and the current environment (atmosphere) information. For example, in a case where one developing cartridge has not been used for a long time and another has been printed immediately before, it is difficult to perform appropriate correction in halftone control. . That is, it is difficult to optimize the image forming conditions.

Accordingly, it is an object of the present invention to provide an electrophotographic image forming apparatus and a cartridge which can always optimize the image forming conditions for each cartridge regardless of whether or not the cartridges are replaced or the usage conditions are different. .

[0017]

The above object is achieved by an electrophotographic image forming apparatus and a cartridge according to the present invention. In summary, the present invention relates to an electrophotographic image forming apparatus for forming an image on a recording medium in which a cartridge is detachable, wherein a first time of an electrophotographic image forming apparatus main body; Holding means for holding a first environmental condition corresponding to the first condition, a second time of the electrophotographic image forming apparatus main body, and a second environment condition corresponding to the second time. A first time and a first environment information held by the first holding means, and a second holding means held by the second holding means. An electrophotographic image forming apparatus characterized in that third environmental information is obtained from the time and second environmental information, and image forming conditions are controlled based on the third environmental information.

According to one embodiment of the present invention, the image forming condition is defined as a gradation characteristic in a gradation correcting means for forming a halftone image, or a density detection pattern for creating the gradation characteristic. Is the creation condition. The second holding unit in the cartridge holds information on the halftone density.

According to another embodiment of the present invention, the image forming condition is a condition for forming a latent image on the electrophotographic photosensitive member of the cartridge.

According to another embodiment of the present invention, the image forming condition is a developing condition of a developing unit of the cartridge.

According to another embodiment of the present invention, the cartridge has an electrophotographic photosensitive member, and the main body of the electrophotographic image forming apparatus is an image carrier on which a developed image formed on the electrophotographic photosensitive member is transferred. And the image forming conditions are transfer conditions of a transfer unit for transferring the developed image to the image carrier.

According to another embodiment of the present invention, the image forming condition is a condition for forming a density detection pattern when controlling the maximum density.

According to another embodiment of the present invention, the cartridge is a developing cartridge as developing means, and the electrophotographic image forming apparatus is a color image forming apparatus having a plurality of the developing cartridges.

According to another embodiment of the present invention, the cartridge is a process cartridge in which an electrophotographic photosensitive member and at least one of a developing unit, a charging unit, and a cleaning unit are integrally formed. The electrophotographic image forming apparatus is a color image forming apparatus having a plurality of the process cartridges.

According to another aspect of the present invention, there is provided a cartridge detachably mountable to an electrophotographic image forming apparatus main body.
It has at least an electrophotographic photosensitive member or a developing unit, and further stores at least predetermined time information of the electrophotographic image forming apparatus main body and information on environmental conditions of the electrophotographic image forming apparatus main body at the predetermined time. A cartridge is provided having storage means.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electrophotographic image forming apparatus and a 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. FIG. 1 schematically shows a color printer which is an electrophotographic image forming apparatus of the present embodiment.

Hereinafter, description will be made with reference to the drawings. A photosensitive drum 1 as an electrophotographic photosensitive member is driven in a direction indicated by an arrow by a driving unit (not shown), and a primary charger 2 as a charging unit.
Is charged uniformly. FIG. 2 shows the photosensitive drum 1
More specifically, a photoconductor layer 1b made of a normal organic photoconductor layer (OPC) is formed and applied to the outer peripheral surface of a grounded drum base 1a made of a conductive material such as aluminum. The photoreceptor layer 1b further includes an undercoat layer (C
PL), 1b-1, injection blocking layer (UCL) 1b-2, charge generation layer (CGL) 1b-3, and charge transport layer (CT
L) It consists of four layers 1b-4.

Next, returning to FIG. 1, the photosensitive drum 1 is irradiated with a laser beam L according to a yellow image pattern from an exposure device 3 as an electrostatic latent image forming means.
An electrostatic latent image is formed thereon. When the photosensitive drum 1 further moves in the direction of the arrow, the developing devices 4a, 4b, 4c, and 4 containing yellow toner, magenta toner, cyan toner, and black toner supported by the rotary support 11 respectively.
The developing device 4a containing the yellow toner is selected and rotated in the direction of the arrow so as to face the photosensitive drum 1, and the electrostatic latent image is visualized as a toner image by the developing device 4a.

An intermediate transfer belt 5 serving as an image carrier rotates in the direction of the arrow at substantially the same speed as the photosensitive belt 1, and a primary transfer roller serving as a transfer means transfers a toner image formed and carried on the photosensitive drum 1. The primary transfer is performed on the outer peripheral surface of the intermediate transfer belt 5 by the primary transfer bias applied to the intermediate transfer belt 8a.
The above steps are further performed for magenta, cyan, and black to form toner images of a plurality of colors on the intermediate transfer belt 5.

Next, a transfer material P as a recording medium is fed from the transfer material cassette 12 by a pickup roller 13 at a predetermined timing. At the same time, the secondary transfer roller 8
b, a secondary transfer bias is applied, and the toner image is transferred from the intermediate transfer belt 5 to the transfer material P.

Further, the transfer material P is transported to the fixing device 6 by the transport belt 14 and is fused and fixed to obtain a color image. Further, the transfer residual toner on the intermediate transfer belt 5 is cleaned by the intermediate transfer belt cleaner 15. On the other hand, the transfer residual toner on the photosensitive drum 1 is cleaned by a cleaning device 7 of a known blade means.

A density sensor 9 as density detecting means is provided in the printer body. In an electrophotographic color image forming apparatus, if the image density fluctuates due to changes in the environment in which the apparatus is used, the number of prints, and the like, the original correct color tone cannot be obtained. Therefore, in a color printer or the like, a toner image for density detection, that is, a patch is formed on the photosensitive drum 1 with each color toner on a trial basis in the same manner as described in the conventional example, and the densities thereof are determined. A stable image can be obtained by performing image density control in which the density is detected by the density sensor 9 and the result of the detection is fed back to the LUT for halftone correction.

The density sensor 9 is, as shown in FIG.
A light emitting element 91 such as D, a light receiving element 92 such as a photodiode, and a holder 93;
The density of the patch T is measured by irradiating the patch T on the photosensitive drum 1 with the infrared light from No. 1 and measuring the reflected light therefrom with the light receiving element 92. The light reflected from the patch T includes a specular reflection component and an irregular reflection component, and the specular reflection component is a variation in the state of the surface of the photosensitive drum 1 serving as a base of the patch T and the distance between the density sensor 9 and the patch T. Accordingly, if the specular reflection component from the patch T to be measured is included because the light amount fluctuates greatly, the detection accuracy is significantly reduced. Therefore, the density sensor 9 measures only the irregularly reflected light with the irradiation angle to the patch T being 45 ° and the light receiving angle of the reflected light from the patch T being 0 ° with respect to the normal I.

The patch T is formed on the photosensitive drum 1 by inputting a patch pattern signal to a laser driver 21 by a computer (hereinafter, also referred to as "CPU") 20 in the same manner as described in the conventional example. The photosensitive drum 1 is formed by exposing the photosensitive drum 1 via a laser diode 22, a polygon mirror 23, etc. In the printer of the present embodiment, the photosensitive drum 1 of the intermediate transfer belt 5 is used for patch formation.
Is released so that the intermediate transfer belt 5 does not touch the patch T.

Each of the developing devices 4a to 4d constitutes a developing cartridge which can be independently attached to and detached from the rotary support 11, and is a nonvolatile RAM which is a readable and writable storage means.
30a, 30b, 30c and 30d are mounted. Similarly, the photosensitive drum 1, the primary charger 2, the cleaning device 7, and the removed toner container 25 constitute a process cartridge A which can be integrally attached to and detached from the printer main body. It has.

Since the developing cartridges 4a to 4d are supported in a rotating body, the RAMs 30a to 30d cannot be connected to the printer main body, and use a non-contact type memory there. The non-contact type memory is a well-known type having a receiving means such as an antenna therein.
Need to go through 1. Therefore, when each of the developing cartridges 4a to 4d faces the photosensitive drum 1 by the rotation of the rotating support 11, the RAM 30a
30d are arranged so as to approach and face the R / W means 31. The RAM 32 of the process cartridge A is normally connected to the main body by a connector (not shown), but a non-contact type RAM similar to that used for the developing cartridge may be used instead.

The atmosphere of the printer body is measured by a temperature / humidity sensor 33 which is an environment detecting means.
The values of the temperature (° C.) and the relative humidity (% RH), which are the measurement results, are sent to the controller. The absolute time (information such as year, month, day, hour, minute, etc.) is measured by a clock 24 which is a clock means provided in the printer body, and the value is transmitted to the computer 20 in the same manner.

As described in the conventional example, generally, the initial gradation characteristics of an image forming apparatus which outputs a gradation image are, for example, in a normal temperature and normal humidity environment, a high temperature and high humidity environment, and a low temperature and low humidity environment, respectively, as shown in FIGS. 10, as shown in the graph of FIG.

The data of the gradation characteristics for each environment is stored in the main memory 1 serving as the main storage means as initial values.
6 is stored in the ROM. The data of this gradation characteristic may be prepared for each more detailed environment as needed.

On the other hand, in the non-volatile RAMs 30a to 30d mounted on the developing cartridges 4a to 4d, the data of the gradation characteristics obtained by the half-tone control and the data of the gradation characteristics are stored in the non-volatile RAMs 30a to 30d. The obtained environment data is stored. These data stored in the nonvolatile RAMs 30a to 30d are stored in the form of a difference from the initial value of the gradation characteristic. However, the non-volatile R
All 0s are written as differential data in the AMs 30a to 30d. When parts such as the photosensitive drum 1 and the developing cartridges 4a to 4d are replaced, all 0s are written as difference data as in the case of shipping. The handling of environment and time data in such a case will be described later.

Next, the halftone control in this embodiment will be described with reference to FIGS.

When the CPU 20 detects an appropriate timing such as turning on the power to the printer body, the elapsed time from the turning on of the power, or the number of prints, the halftone control is started (S30). First, the CPU 20 reads the current environmental conditions (temperature / humidity / first environmental information) and the absolute time (first time) using the temperature / humidity sensor 33 and the clock 24 as the first holding unit. Further, from the nonvolatile RAM 30a as the second holding unit of the control target, for example, the yellow developing cartridge 4a, the environmental condition at the time of the previous control (second environmental information), the absolute time (second time) ), And read out the gradation characteristics (difference data) (S31).

Next, the current absolute time T1 and R
Absolute time T at the time of previous control written in AM 30a
Then, the elapsed time ΔT = T1−T2 is obtained from the equation (2). Then, an estimated environment condition (third environment information) which seems to be familiar to the developing cartridge 4a to be controlled is estimated from the environment at the time of the previous control, the current environment, and the parameter of ΔT (S3).
2). Examples of the environmental conditions include a temperature t (° C.),
From the relative humidity ψ (% RH), the moisture content in the air x (1 kg
Per unit of water in the air, g / kg).

Incidentally, the value of x is 21.5 g at 30 ° C. and 80% RH under the atmospheric pressure of 760 mmHg;
1.1 g at 5 ° C., 10% RH; 1 g at 25 ° C., 60% RH
It becomes 1.8 g.

The larger the value of ΔT, the smaller the influence of the previous environmental conditions.
Current moisture content x2, estimated moisture content x = Ax1 + Bx2
As (A + B = 1), x can be obtained by preparing a corresponding set of ΔT and weighting coefficients A and B.
As an example, A = 1 when ΔT = 0, A = 0 when ΔT ≧ 8 hours, and a method such as linear interpolation between them is used as x.
Can be requested.

Next, difference data of gradation characteristics corresponding to the estimated environment (moisture content) is read from the nonvolatile RAM 30a of the developing cartridge 4a (S33). Next, the initial value of the gradation characteristic corresponding to this environment is read out from the ROM of the printer main body memory 16 (S34). By subtracting the difference data of the gradation characteristic from the initial value of the gradation characteristic, the gradation characteristic when the previous halftone control is performed is calculated (S35). A data set of a patch created by halftone control is calculated based on the data of the gradation characteristics (S36), and the data is sent to the laser driver 21 to form a latent image of the density detection patch on the photosensitive drum 1. Then, a patch is created by developing with the developing cartridge 4a (S3).
7).

Then, the densities of these patches are measured at appropriate timing by the density sensor 9 (S38).
Further, the relationship between the image signal used for creating each patch and the measured density of each patch is interpolated by another term to obtain a gradation characteristic (S39). An LUT is created based on the gradation characteristics and written into the RAM in the CPU 20 (S40).
At the same time, the difference from the initial value of the gradation characteristic stored in the ROM of the memory 16 is calculated. This difference data is stored in the nonvolatile RAM 30a together with the current environment information,
It is used at the next halftone control (S41).

Next, a method of calculating the data set of the patch in the above-mentioned control step S36 will be described.

When the gradation characteristics of the printer are as shown in the graph of FIG. 5 by the previous halftone control, the upper and lower 5% of the image density are set as the upper limit L1 and the lower limit L2, and the necessary number of patch data during this period is When n is set, it is divided into n-1 equal parts. Here, since n = 10 pieces of data are required, FIG.
Then, as shown by the dotted line in FIG. Then, image signals a1 to a10 necessary for obtaining these image densities are used as data for creating a patch. According to this method, a patch without bias in density can always be created.

As described above, the developing cartridge 4a for yellow
I explained the method of correcting the gradation characteristics related to
Similarly, control can be sequentially performed for each of the developing cartridges 4b, 4c, and 4d for magenta, cyan, and black. At this time, for example, when only black printing is performed for a while and the developing cartridges 4b to 4d for yellow, magenta, and cyan are not used, the above-described ΔT is obtained for each developing cartridge. Therefore, optimal correction can be performed for each developing cartridge.

When the printer, the developing cartridge, or the process cartridge is shipped, the non-volatile RAMs 30a to 30d, 32, and the like do not have environmental data or absolute time data under the use environment. Is normal temperature and normal humidity (25 ° C, 60%),
If the absolute time is set to the time at the time of manufacturing each cartridge or a minimum value (for example, zero), the current environmental condition can be used as it is with "weight 100%" at the time of environment estimation.

In the present embodiment, the RAMs 30a to 30a
As the data of the environment and the absolute time to be written in d, 32, etc., the data of the timing at the time of the density control is used. You may.

The difference data of the gradation characteristics of each color is stored in the RAM 16 provided in the main body memory 16 without being stored in the RAM of each color.
M may be stored.

Further, the present invention is also effective in a case where an inexpensive printer without a density sensor stabilizes the halftone density against environmental changes. In other words, the present invention makes it possible to detect a substantial temperature and humidity, which are considered to be familiar to each cartridge, with high accuracy according to the present invention. By selecting (or calculating) the corresponding LUT based on the corrected environmental information such as temperature and humidity or the amount of moisture obtained using the above, appropriate halftone correction can be performed.

Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIGS.

In the first embodiment, the case where the gradation control is mainly performed has been described. However, in addition to the halftone γ characteristic, the light portion of the photosensitive drum 1, There are the potential of the dark portion, the developing ability of the solid density of the developing devices 4a to 4d, the transfer efficiency of the transfer means, and the like.

Conventionally, these parameters are also based on the measurement result of the solid density (or dark halftone density) by the density sensor 9, the exposure amount of the laser beam, the developing bias, and the charging amount by the charging means of the photosensitive drum. In some cases, the image is stabilized by giving feedback to the user. In some cases, the bias value of the transfer unit (such as the primary transfer roller 8a) is changed according to the environment.

Even in such a case, the nonvolatile RAM
30a-30d, 32 etc. each cartridge 4a-4
By storing the environmental state and the absolute time at the time of the last control of d and A or at the time of printing, and comparing with the current environmental state and the absolute time at the time of performing the next density control or printing, better. Control or printing can be performed.

First, the case of density control will be described.

Among the parameters affected by environmental changes, the sensitivity of the photosensitive drum 1 decreases, for example, at low humidity (low temperature) and increases at high humidity (high temperature).
As such, sensitivity is often affected by humidity (or temperature).

In this case, in the same manner as described in the first embodiment, the amount of water is determined based on the past environmental state (and time) and the current environmental state (and time) written in the RAM 32 of the process cartridge A. May be obtained and fed back to the laser exposure amount, the charge amount, and the like.

FIG. 6 shows, as an example, a method in which the charge amount is fed back by the high voltage power supply 34. That is, when the sensitivity is lowered under low humidity, the bright potential increases, so that the amount of charge can be reduced to mitigate the increase. Conversely, the charge amount may be increased under high humidity.
If the amount of adjustment is prepared in advance in the ROM of the memory 16 of the printer in association with the amount of moisture, optimal potential correction can be performed by using the above-mentioned predicted amount of moisture in consideration of the passage of time. it can.

In the developing device 4a, the solid density often changes mainly due to the influence of the amount of water on the charge amount of the toner. Therefore, the output value of the developing bias power supply 35 may be corrected by controlling the output value according to the amount of moisture.

In the case where a solid density control system for correcting the change in density according to the environmental change by measuring a dark patch with the density sensor 9 described above is used, the following method is used. be able to.

First, a typical method of such control will be described. When measuring patch densities, a plurality of predetermined developing bias values are prepared, and the patches are switched to provide a plurality of patches having different densities. 1, and a developing bias value close to a predetermined density value is selected (or calculated by interpolation) from among them, whereby the developing bias can be determined. However, the number of patches that can be used is limited (for example, 3 to 6, and 5 patches are used in this embodiment). In some cases, the developing bias value may not be present in the prepared set of patches. On the other hand, by preparing a plurality of development bias sets used for patch formation and changing them according to the amount of water,
Good solid density control can always be performed without increasing the number of patches or increasing the change width of the developing bias to lower the accuracy.

Specifically, as shown in FIG. 7, V5 and V1, which are the maximum and minimum values of the developing bias to be used, are set to RA
M30a to 30d, it is increased or decreased according to the predicted moisture content according to the above-described method, and at the same time, other biases V2 to V
By increasing or decreasing the number 4, the developing bias values (V1 to V5) for forming the patch including the maximum and minimum values can be changed to an appropriate area including the target density.

Next, a method for correcting a change in the transfer efficiency of the primary transfer means 8a will be described.

In general, the charge amount of the toner decreases under high humidity, and increases under low humidity. Therefore, the output value of the bias power supply 36 applied to the primary transfer means 8a is changed accordingly. Specifically, the output may be reduced under high humidity and increased under low humidity. Also in this case, by using the predicted water amount obtained by the above-described method using the RAMs 30a to 30d of the developing cartridges 4a to 4d, an optimum transfer bias value previously associated with the water amount is selected and used. Good transfer performance can always be obtained.

Embodiment 3 Next, a third embodiment of the present invention will be described.

In the first and second embodiments described above, the case where the temperature and humidity sensor 33 is used has been described. However, regarding the humidity, the relationship between the current and the voltage of various charging means used in the printer is described. By looking at the changes, you can get an alternative.

For example, the primary transfer means 8a shown in FIG.
Alternatively, the above object can be achieved by measuring the current or voltage value of the secondary transfer means 8d (the latter is the case of a constant current power supply).

In this case, the amount of water in the air corresponding to the measured current or voltage value is stored in the ROM in the memory 16 in advance, and the above current or voltage value is referred to by the computer 20 with reference to the value of the ROM. After the conversion into the water content, the value is stored in the RAM 30a to
What is necessary is just to store in 30d, 32, etc. suitably.

While the first to third embodiments have been described above, the RAMs 30a to 30d, 32
The timing of writing the environment and clock data to each cartridge is preferably performed at the time of the last density control or printing execution for each cartridge.The previous data is compared with the current data, and after a series of operations are completed The current data may be overwritten on the previous data in the RAM of the operated cartridge.

Further, the present invention is not limited to the form of the printer of the above-described embodiment, but can be similarly applied to a tandem type color printer having four photosensitive drums. In particular, when each of the four photosensitive drums integrally has a cleaning device and a developing device and forms an independently detachable process cartridge, the use of the photosensitive drum and the developing device is required for each of the four cartridges. Since the history is the same, a non-volatile RAM is provided for each cartridge, and the environmental data and the time at the time of environmental measurement are stored in the RAM. Since it can be treated as an integrated effect, the development, latent image, halftone characteristics, and the like can be controlled more appropriately. For example, the correction of the charging and the developing bias can be performed not independently but with a certain relationship.

Also, as in the present invention, the environment data and the absolute time when the environment data is measured are written in the nonvolatile RAM provided in each cartridge, so that the used cartridge alone can be used in the environment at the time of use. It is possible to know the status, and it is also possible to obtain an effect that it can be effectively used for estimating a cause when a trouble occurs and grasping market information.

[0077]

As is apparent from the above description, according to the electrophotographic image forming apparatus and the cartridge of the present invention,
A first holding unit for holding a first time of the electrophotographic image forming apparatus main body and a first environmental condition corresponding to the first time; and a second time of the electrophotographic image forming apparatus main body. ,
Holding the second environmental condition corresponding to the second time;
A second holding unit in the cartridge, wherein a first time and first environmental information held by the first holding unit and a second time information held by the second holding unit are stored. The third environment information is obtained from the time and the second environment information, and the image forming conditions are controlled based on the third environment information. The image forming conditions can be always optimized for each cartridge, so that a good image can always be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a color printer that is an electrophotographic image forming apparatus according to the present invention.

FIG. 2 is a partial cross-sectional view showing one embodiment of a photosensitive drum.

FIG. 3 is an explanatory diagram showing one embodiment of a density sensor.

FIG. 4 is a flowchart of halftone control in the first embodiment.

FIG. 5 is a graph showing a relationship between an image density and an image signal in the first embodiment.

FIG. 6 is a schematic configuration diagram showing a color printer of another embodiment according to the present invention.

FIG. 7 is a graph showing a relationship between a water content and a developing bias in a second embodiment.

FIG. 8 is a configuration diagram illustrating an example of a conventional electrophotographic image forming apparatus.

FIG. 9 is a graph showing the relationship between image density and image signal in a conventional example.

FIG. 10 is a graph showing the relationship between image density and image signal under high temperature and high humidity.

FIG. 11 is a graph showing the relationship between image density and image signal under low temperature and low humidity.

[Explanation of symbols]

Reference Signs List 1 photoconductor drum (electrophotographic photoconductor) 4a, 4b, 4c, 4d developing device (developing cartridge) 5 intermediate transfer belt (image carrier) 8a primary transfer roller (transfer unit) 9 density sensor (density detection unit) 16 memory Reference Signs List 20 CPU (first holding unit) 30a, 30b, 30c, 30d RAM (second holding unit) 32 RAM (second holding unit) A Process cartridge

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04N 1/407 H04N 1/40 101E 9A001 F term (reference) 2H027 DA10 DA11 DA14 DA38 DE02 EA03 EA04 EB04 EC03 EC06 EE08 HB05 HB13 HB14 2H071 BA04 BA32.

Claims (10)

[Claims] 1. An electrophotographic image forming apparatus in which a cartridge is detachable and for forming an image on a recording medium, wherein the first time corresponds to the first time of the main body of the electrophotographic image forming apparatus and the first time corresponds to the first time. First holding means for holding a first environmental condition, a second time of the electrophotographic image forming apparatus main body,
Holding a second environmental condition corresponding to the second time;
A second holding unit in the cartridge, a first time and first environmental information held by the first holding unit, and a second time information held by the second holding unit. An electrophotographic image forming apparatus comprising: obtaining third environment information from a time and second environment information; and controlling an image forming condition based on the third environment information. 2. The image forming condition is a tone characteristic in a tone correcting unit for forming a halftone image, or a condition for forming a density detection pattern when creating the tone characteristic. The electrophotographic image forming apparatus according to claim 1. 3. An electrophotographic image forming apparatus according to claim 2, wherein said second holding means in said cartridge holds information on halftone density. 4. An electrophotographic image forming apparatus according to claim 1, wherein said image forming condition is a condition for forming a latent image on an electrophotographic photosensitive member of said cartridge. 5. The electrophotographic image forming apparatus according to claim 1, wherein the image forming condition is a developing condition of a developing unit of the cartridge. 6. The cartridge has an electrophotographic photosensitive member, and the main body of the electrophotographic image forming apparatus has an image carrier on which a developed image formed on the electrophotographic photosensitive member is transferred. 2. The electrophotographic image forming apparatus according to claim 1, wherein the condition is a transfer condition of a transfer unit for transferring the developed image to the image carrier. 7. The electrophotographic image forming apparatus according to claim 1, wherein the image forming condition is a condition for forming a density detection pattern when controlling a maximum density. 8. The image forming apparatus according to claim 2, wherein the cartridge is a developing cartridge as a developing unit, and the electrophotographic image forming apparatus is a color image forming apparatus having a plurality of the developing cartridges. Such an electrophotographic image forming apparatus. 9. The process cartridge wherein the electrophotographic photosensitive member and at least one of a developing unit, a charging unit, and a cleaning unit are integrally formed, and the electrophotographic image forming apparatus comprises a plurality of cartridges. 9. An electrophotographic image forming apparatus according to claim 2, wherein said electrophotographic image forming apparatus is a color image forming apparatus having said process cartridge. 10. A cartridge detachable from an electrophotographic image forming apparatus main body, comprising at least an electrophotographic photosensitive member or a developing means, further comprising at least predetermined time information of the electrophotographic image forming apparatus main body, and A cartridge having holding means for holding information on environmental conditions of the electrophotographic image forming apparatus main body at a time.