JP2006138989A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute setup without lowering productivity of image formation. <P>SOLUTION: A control unit 10 of an image forming apparatus 1 selects and executes any one of first setup seriously considering image quality and second setup seriously considering productivity. In the first setup, the control unit 10 regulates both of an electrification amount in an electrification device 12 and an exposure amount in an exposure device 13. In the second setup, the control part 10 regulates the exposure amount in the exposure device 13. Since the second setup regulates contrast potential without changing electrification potential, the control part 10 can execute the setup at a high speed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for controlling image density in an electrophotographic image forming apparatus.

  An image forming apparatus such as an electrophotographic copying machine or a printer has a problem that the image density tends to fluctuate due to the surrounding environment, use conditions, changes with time, etc. due to the characteristics of the image forming system. For example, in an image forming apparatus using a general two-component developer, the image density tends to decrease under a low humidity environment, and the image density tends to increase under a high humidity environment. Also, due to factors such as deterioration of the photoconductor and developer, or fluctuations in the toner amount in the developing unit, the image density input as an image signal (hereinafter referred to as “input image density”) and the actual paper or image carrier In some cases, the relative ratio to the image density (hereinafter referred to as “output image density”) of the image formed at the same time is different between the low density area and the high density area. Therefore, in order to stably maintain the image density, the image forming apparatus generally performs “setup” for adjusting the image density. The execution timing of the setup is arbitrary, and is normally executed as appropriate when the image forming apparatus is activated or idle, or during continuous image forming jobs or during continuous image formation (so-called inter-image). From the viewpoint of stably maintaining the image density, it is desirable that the setup is performed frequently.

  There are several ways to set up. One is to predict the usage conditions of the image forming apparatus based on the degree of deterioration of the photoreceptor and developer, the toner amount in the developing unit, or the environmental conditions such as temperature and humidity, and the charging potential corresponding to the predicted usage conditions. This is a method of controlling the charger and the exposure device so that the exposure potential is obtained. Alternatively, a patch image having a predetermined image density (hereinafter referred to as “reference patch”) is formed on an image carrier such as a photoconductor, and the output image density of the reference patch is optically measured by a sensor or the like to obtain an input image. There is also a method in which image forming conditions such as a charging potential, an exposure potential, or a supplied toner amount are changed according to the difference from the density. Patent Document 1 shows an example of the latter. After a predetermined time has elapsed, a toner image (reference patch) is formed and measured on a photosensitive member charged to a plurality of charged potentials, and a desired toner amount is determined based on the measurement result. Is determined, and the exposure amount corresponding to the charged potential is determined.

Japanese Patent No. 2585354

  By the way, it generally takes time to change the charging potential. For example, in a roll type charger such as a general BCR (Bias Charge Roller), a considerable time is required until the photosensitive member is charged after the desired charging potential is calculated and the charging potential of the entire photosensitive member is stabilized. Is required. In addition, for example, a charger such as a corotron that charges a photoconductor with a surface requires more time depending on the area to be charged, that is, the opening width.

  However, since setup can be executed at various timings, sufficient time is not always ensured. For example, when the setup is executed during the inter-image, if the setup time is longer than the normal inter-image time, the setup must be executed at the expense of image formation productivity. However, if setup is executed only when the image forming apparatus with sufficient time is started or idle, and setup is not executed for inter-images with no time, for example, a large amount of images can be created in the same image forming job. When the images are continuously formed, a significant density difference may occur between the first image and the last image of the image forming job.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for executing setup without reducing the productivity of image formation.

In order to achieve the above object, the present invention provides an image carrier, charging means for charging the image carrier to a predetermined charging potential, and irradiating the charged image carrier with light. An exposure means for forming an electrostatic latent image having an exposure potential determined in the selected area, and a toner charged to a reverse polarity of the electrostatic latent image to the electrostatic latent image formed on the image carrier. A first setup for adjusting a developing unit for forming a toner image, a charge amount for the charging unit to charge the image carrier, and an exposure amount for the exposure unit to expose the image carrier. Means, a second setup means for adjusting an exposure amount for the exposure means to expose the image carrier, and as a setup means to be executed, the first setup means and the second setup means Choose one To provide an image forming apparatus and selecting means.
According to such an image forming apparatus, it is possible to switch and execute the first setup focusing on image quality and the second setup focusing on productivity. That is, it is possible to execute setup without reducing the productivity of image formation.

In a more preferred aspect of the image forming apparatus of the present invention, the selecting unit may charge the image carrier to a desired charging potential before the next scheduled image forming process is started. If possible, if the first set-up means is selected and the image carrier cannot be charged to the desired charging potential before the next scheduled image forming process is started, , Selecting the second setup means.
More specifically, for example, the selection unit selects the first setup unit during non-image formation or between successive image formation jobs.
Alternatively, the selection unit selects the second setup unit during successive image forming processes in the same image forming job.
In this way, the first setup that emphasizes image quality is executed when there is a relatively large amount of time, and the second setup that emphasizes productivity is performed when there is a relatively small amount of time. It is possible to more reliably prevent a decrease in productivity.

The image forming apparatus according to the present invention further includes an input unit for inputting a selection criterion of the selection unit as a more preferable aspect.
In this way, the user can input a desired selection criterion, and setup can be executed based on the selection criterion. Therefore, the setup according to the user's request can be set.

In a more preferred aspect of the image forming apparatus of the present invention, a density storage unit that stores a target value of a density of a reference image that serves as a reference for the adjustment, and a density detection unit that detects the density of the developed toner image. The first set-up means stores the density of the toner image based on the reference image formed by the developing means and detected by the density detection means in the density storage means. Compared with the target value, at least one of the charge amount and the exposure amount is adjusted according to the comparison result.
Alternatively, the image forming apparatus includes a density storage unit that stores a density of a reference image serving as a reference for the adjustment, and a density detection unit that detects a density of the developed toner image. The second setup unit is formed by the development unit. The density of the toner image based on the reference image obtained by the detection by the density detection unit is compared with the density of the reference image stored in the density storage unit, and the exposure amount is determined according to the comparison result. Adjust.
In this way, the density of the toner image based on the reference image can be directly detected, and the charge amount and exposure amount can be adjusted based on the detection result. Therefore, it is possible to further improve the accuracy of density adjustment by setup.

In the image forming apparatus of the present invention, as a more preferable aspect, the charging unit charges the image carrier by a surface charging method.
The surface charging type charging means requires time to reach a desired charging potential. Therefore, the present invention has a more remarkable effect in an image forming apparatus using such a charging unit.

In a more preferred aspect of the image forming apparatus of the present invention, the first setup unit adjusts the exposure amount so that the exposure potential of the image carrier does not change before and after the adjustment of the charge amount. The second setup means adjusts the exposure amount so that the image carrier has a predetermined exposure potential.
In this way, since the exposure potential of the image carrier does not change in the first setup, the gradation reproducibility does not deteriorate after the execution of setup.

In a more preferred aspect of the image forming apparatus of the present invention, the first set-up unit includes an adjusting unit that adjusts a developing bias potential for charging the toner in the developing unit, and the charging potential of the charging unit. At least one of the charge amount and the exposure amount is corrected while the ratio between the difference between the developing bias potential of the developing means and the difference between the developing bias potential and the exposure potential of the exposing means is made constant.
Alternatively, the second setup means includes an adjusting means for adjusting a developing bias potential for charging the toner in the developing means, and the difference between the charging potential of the charging means and the developing bias potential of the developing means, The exposure amount is corrected while the ratio between the developing bias potential and the difference between the exposure potential of the exposure means is kept constant.
In this way, it is possible to prevent the gradation of the image density from changing greatly before and after the setup.

(1) Configuration FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 1 according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 1 includes a photoconductor 11, a charging device 12, an exposure device 13, a developing device 14, a paper transport belt 15, a transfer roll 16, and a fixing device 17. A cleaning device 18 and a charge removal device 19.

For example, a photoconductive layer made of OPC (Organic Photo Conductor) as a charge acceptor is formed on the surface of the photoconductor 11 and is rotated in the direction of arrow R in the figure. The charging device 12 is a corotron, for example, and uniformly charges the surface of the photoconductor 11 by corona discharge. The surface potential of the photoconductor 11 at this time is hereinafter referred to as a charging potential V _H. The exposure device 13 includes a laser diode and the like, and exposes the surface of the photoconductor 11 by irradiating light based on image data, thereby forming an electrostatic latent image by losing the charge in the irradiated area. The potential of the area on the surface of the photoconductor 11 where the electrostatic latent image is formed is hereinafter referred to as an exposure potential _VL .

The developing device 14 supplies toner to the surface of the photoreceptor 11. At this time, the toner is charged so as to have a reverse polarity with respect to the electrostatic latent image, and is attached to the electrostatic latent image due to a potential difference from the surface of the photoreceptor 11 and developed (visualized). This potential difference is hereinafter referred to as a developing bias potential V _Bias .

  The paper transport belt 14 is driven in the direction of arrow P in the drawing to transport the paper. The transfer roll 16 is charged to a predetermined potential and faces the photoconductor 11 with the paper transport belt 14 interposed therebetween. The transfer roll 16 transfers the toner image developed on the surface of the photoconductor 11 to a sheet by electrostatic force at a position facing the photoconductor 11. The fixing device 17 includes a pair of rollers facing each other with the paper transport belt 14 interposed therebetween, and the toner image on the paper is fixed by heating and pressurizing the paper using the rollers. In this way, the image forming apparatus 1 forms an image on a sheet.

  The cleaning device 18 removes toner remaining on the surface of the photoconductor 11 without being transferred to the paper. The static eliminator 19 irradiates the surface of the photoconductor 11 with light to remove residual charges. After these two processes, the photoconductor 11 is prepared for the next image forming process.

In addition, the image forming apparatus 1 is provided with various means for detecting the use conditions of the apparatus itself and the surrounding environment. These means will be described below.
The environmental sensor 21 detects the temperature and humidity inside or outside the machine. The magnetic sensor 22 detects the toner density (toner density) inside the developing device 14. The toner sensor 23 detects the density of the toner image developed on the surface of the photoreceptor 11 (toner image density). The detection results by these sensors are supplied to the control unit 10.

The control unit 10 includes an arithmetic device such as a CPU (Central Processing Unit) and various memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and executes various programs stored in the memory. By doing so, the above-described units are controlled. That is, the control unit 10 controls the charge amount in the charging device 12, the exposure amount in the exposure device 30, the developing bias potential in the developing device 14, and the like. The memory of the control unit 10 stores patch image data D _P for forming a reference patch used for setup described later.
Further, the image forming apparatus 1 of the present embodiment includes an input unit 30. The input unit 30 is, for example, a touch panel type liquid crystal display, and displays various types of information and receives instructions from the user. When the user wants to execute setup described later, an instruction is input to the image forming apparatus 1 via the input unit 30.

(2) Operation With the above configuration, the image forming apparatus 1 forms a toner image based on the image data, and transfers and fixes the toner image on a sheet to form an image. When such an operation is repeatedly performed, the image forming apparatus 1 performs setup in order to stably maintain the image density.
The image forming apparatus 1 according to the present embodiment is characterized in that one of two different types of setups is performed according to the selection of the control unit 10. These two types of setups are simply “setup focusing on image quality (first setup)” and “setup focusing on productivity (second setup)”. Therefore, before describing a series of operations of the image forming apparatus 1, the setup operation in the present embodiment, and the first setup and the second setup described above will be specifically described.

The setup in the present embodiment refers to correction so that the image density of the formed image matches the target value by changing at least one of the charge amount in the charger 12 and the exposure amount in the exposure device 13. It is. Since the image density depends on the difference between the charging potential V _H and the exposure potential V _L , that is, V _H −V _L , the image density can be changed by adjusting the charge amount or the exposure amount. In the following, the difference between the above-described charging potential V _H and exposure potential V _L , that is, “V _H −V _L ” is referred to as “contrast potential V _Cont ”. Output image density as the contrast potential V _Cont is increased higher, related that the contrast potential V _Cont output image density as smaller decreases.

FIG. 2 is a diagram showing the relationship between the exposure amount and the surface potential in a general photoreceptor. As shown in the figure, the surface potential of the photoconductor attenuates substantially linearly when the exposure amount is small. However, when the exposure amount increases to some extent, the attenuation of the surface potential becomes saturated and becomes nonlinear. Since the toner image density changes according to the surface potential of the photoconductor, if the photoconductor is exposed with an exposure amount such that the surface potential attenuates non-linearly, the density change of the toner image density also becomes non-linear. That is, when the exposure potential V _L is equal to or higher than the threshold value V _th shown in FIG. 2, the toner image density shows good gradation reproducibility, and when the exposure potential V _L is lower than the threshold value V _th shown in FIG. The tone reproducibility of the toner image density decreases.
This is shown in FIG. Figure 3 is a diagram illustrating input-output characteristics of the image density of the two types of exposure potential line L shows the case where the exposure potential V _L is the threshold V _th or more, the curve C is the exposure potential V _L is the threshold The case where it becomes less than _Vth is shown. As described above, when exposure is performed with an exposure amount in which the surface potential is attenuated nonlinearly, gradation reproducibility is lowered in a density region where the exposure amount is large, that is, a high density region.

That is, in order to perform setup that emphasizes gradation reproducibility, in other words, image quality, it is desirable that the exposure potential V _L is always equal to or higher than the threshold value V _th , for example, charging while maintaining the exposure potential V _L at a constant value. Ideally, the contrast potential V _Cont is adjusted by changing only the potential V _H. At this time, if the charge amount is increased or decreased to change the charge potential V _H , the exposure potential V _L naturally changes if the exposure amount remains the same. Therefore, in order to change only the charging potential V _H while maintaining the exposure potential V _L at a constant value, it is necessary to adjust the charge amount and the exposure amount. This is the “first setup” in the present embodiment.

However, as described above, a charger such as a general BCR or corotron has a problem in responsiveness, and it takes a considerable time to change the charging potential V _H. For this reason, in a situation where setup execution in a short time is required, a setup for changing the charging potential V _H as in the first setup described above is inappropriate.
Therefore, in such a case, a setup for changing only the exposure potential V _L without changing the charging potential V _H is executed. This is the “second setup” in the present embodiment. Such a setup includes a possibility that the exposure potential V _L is lowered and becomes less than the threshold value V _th . However, from the viewpoint of execution speed, that is, productivity of image formation, the second setup is superior to the first setup. In addition, since the second setup can be executed at high speed, it can be executed in a small free time such as an interimage. That is, since the second setup can be executed frequently, correction can be performed while the fluctuation of the image density is small. As a result, it can be said that the second setup has an effect of stably maintaining the image density as compared with the first setup.

  The image forming apparatus 1 of the present embodiment selectively executes the first setup and the second setup described above according to the situation. In the present embodiment, the timing at which the image forming apparatus 1 performs setup includes (a) when the image forming apparatus 1 is started up, (b) immediately before the start of the image forming job, (c) an inter image, and (d) an image forming job. (E) There are five types of selection criteria at idle. These timings will be briefly described below.

First, (a) when the image forming apparatus 1 is started is a state in which an image immediately after the image forming apparatus 1 is turned on is not formed, and when the image forming apparatus 1 is in a so-called standby state. It is.
Next, (b) immediately before the start of the image forming job and (d) immediately after the end of the image forming job are immediately before the start and immediately after the end of the command (image forming job) processed in one unit in the image forming apparatus 1. That's it. In this embodiment, for example, a command “output one copy of a 10-page document” or “output five copies of an image for one page” corresponds to one image forming job. Of course, there is an image forming job in which only one image is formed, such as “output one copy of an image for one page”.
The (c) inter-image is an image forming process in which a plurality of images are formed, during a continuous image forming process. That is, for example, in an image forming job of “outputting a document of 10 pages”, between the image forming process of the first page and the second page or between the image forming process of the third page and the fourth page. It means that.
Finally, (e) “idle time” refers to a state in which the next image forming job is not started even after a predetermined waiting time (for example, 5 minutes) has elapsed since the last image forming job. That is, an image is not formed during the period from the elapse of the above-described waiting time until the next image forming job is started, and this period is called idle time. The specific value of the waiting time is arbitrary, and this value is stored in the control unit 10.
In this embodiment, the state (a) or (e) in which the image forming apparatus 1 is not performing image formation is defined as a “standby state”.

  The image forming apparatus 1 executes either the first setup or the second setup for each of the above-described (a) to (e). In any of (a) to (e), either the first setup or the second setup may be executed. However, if there is time, the first setup and time If not, a second setup is preferably performed. For this reason, the correspondence relationship shown in FIG. 4 is suitable, for example. That is, in the case of (a), (b), (d) and (e), the first setup is executed, and in the case of (c), the second setup is executed. is there. This correspondence may be stored in the image forming apparatus 1 in advance, or a screen similar to that shown in FIG. 4 may be displayed on the input unit 30, and the user may select each of the selection criteria (a) to (e). Either of the first setup and the second setup may be instructed.

Next, an operation when the image forming apparatus 1 performs setup in a state where the above correspondence is set will be described.
FIG. 5 is a flowchart showing a setup operation in the image forming apparatus 1 of the present embodiment. Describing along the drawing, first, the control unit 10 of the image forming apparatus 1 is in a timing at which the current image forming apparatus 1 should execute setup, that is, in any one of the above-described (a) to (e). It is determined whether or not the conditions match (step S1). If none of (a) to (e) is met (step S1; NO), this means that it is not time for the image forming apparatus 1 to execute setup, so the control unit 10 does not perform any processing. This operation is terminated without performing the operation.
On the other hand, when any of (a) to (e) is met (step S1; YES), the control unit 10 refers to the correspondence shown in FIG. It is determined whether the setup is the first setup or the second setup (step S2).

When executing the first setup (step S2; YES), the control unit 10 first forms two reference patches having different toner image densities on the photoconductor 11 (step S3). That is, at this time, the two reference patches are formed at different contrast potentials V _Cont . The reference patch is formed based on the patch image data D _P stored in the memory of the control unit 10.
Subsequently, the control unit 10 causes the toner sensor 23 to detect the toner image densities of the two reference patches (step S4). The control unit 10 compares the toner image density is detected result of the toner sensor 23 and the patch image data D _P, it calculates a contrast potential V _Cont for correcting the respective density difference (step S5). Then, the control unit 10 calculates a charge amount and an exposure amount for obtaining the contrast potential V _Cont without changing the exposure potential _VL, and sends the charge amount and the exposure amount to the charging device 12 and the exposure device 13. The respective settings are made and the setup is completed (step S6). The charging device 12 charges the photoconductor 10 with the charge amount calculated in step S6, and the exposure device 13 exposes the photoconductor 10 with the exposure amount calculated in step S6. The image density to be obtained can be obtained.

When executing the second setup (step S2; NO), the control unit 10 first forms a reference patch on the photoconductor 11 with the charging potential V _H and the exposure potential V _L at that time (see FIG. Step S7). Subsequently, the control unit 10 causes the toner sensor 23 to detect the toner image density of the reference patch (step S8). The control unit 10 compares the toner image density is detected result of the toner sensor 23 and the patch image data D _P, it calculates a contrast potential V _Cont for correcting the density difference (step S9). Then, the control unit 10 calculates an exposure amount for obtaining the contrast potential V _Cont , sets the exposure amount in the exposure apparatus 13 and ends the setup (step S10). When the exposure device 13 exposes the photosensitive member 10 with the exposure amount calculated in step S10, the image forming apparatus 1 can obtain a desired image density.

  By performing such processing, the image forming apparatus 1 of the present embodiment can selectively execute the first setup and the second setup according to the situation. As a result, the first setup that emphasizes image quality is executed when sufficient time can be secured, and the second setup that emphasizes productivity is executed when sufficient time cannot be secured. It is possible to execute the setup without degrading the performance.

(3) Modifications The present invention is not limited to the above-described embodiments, and can be realized in various other modes. Some examples are shown below.
In the above-described embodiment, a single-color image forming apparatus has been described. However, the present invention is naturally applicable to a multi-color image forming apparatus including a plurality of photoconductors. At this time, the reference patch may be formed on the photosensitive member, but may be formed on the sheet conveying belt or the intermediate transfer belt. In this case, only one sensor is required for detecting the toner image density, and it is not necessary to provide a sensor for each photoconductor.

  In the above-described embodiments, the charger is described as a surface charging type corotron. However, other chargers, for example, a roll type charger such as a BCR may be used. As described above, the effect of the present invention is remarkably exhibited in the surface charging type charger. Therefore, in the above-described embodiment, the charger is used.

  In the above-described embodiment, the setup is performed based on the detection result by detecting the toner image density of the reference patch formed on the surface of the photoreceptor. This is because the accuracy of density adjustment by setup is improved by directly detecting the toner image density. However, the physical quantity measured in the setup is not limited to the toner image density. For example, in the case of the above-described image forming apparatus 1, the temperature / humidity inside or outside the apparatus may be measured by the environmental sensor 21, and the toner density inside the developing apparatus 14 may be measured by the magnetic sensor 22. In addition, the degree of use of the image forming apparatus 1 is estimated by measuring the rotational speed of the photoconductor 10 and the rotational speed of the developing roll inside the developing device 14, and the charge amount and the like are determined based on the estimated change over time. The exposure amount may be adjusted. Furthermore, a setup using a plurality of the above-described physical quantities may be performed.

In the above-described embodiment, the control amount in the setup is only the exposure amount, or only the charge amount and the exposure amount. However, in addition to these control amounts, the development bias potential V _Bias of the developing device 14 may be adjusted simultaneously. Before and after the setup, the ratio of the difference “V _H −V _Bias ” between the charging potential V _H and the development bias potential V _Bias and the difference “V _Bias −V _L ” between the exposure potential V _L and the development bias potential V _Bias does not change. By adjusting the developing bias potential V _Bias as described above, it becomes possible to maintain the gradation of the image density even better. For example, before the setup, the charging potential V _H is “−700 (V)”, the exposure potential V _L is “−200 (V)”, and the development bias potential V _Bias is “−450 (V)”. When the charging potential V _H becomes “−600 (V)” and the exposure potential V _L becomes “−200 (V)” after execution, the control unit sets the developing bias potential V _Bias to “−400 (V)”. It is to adjust so that. In this way, the ratio of “V _H −V _Bias ” and “V _Bias −V _L ” remains “1: 1” before and after the setup, and therefore there is a large change in the gradation of the image density. It can be prevented from occurring.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure showing the relationship between the exposure amount and surface potential in a general photoconductor. It is the figure which illustrated the input / output characteristic of image density about two types of exposure potential. It is the figure which illustrated the selection criteria of the 1st setup and the 2nd setup in the embodiment. 5 is a flowchart showing a setup operation in the image forming apparatus of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Control part, 11 ... Photoconductor, 12 ... Charging device, 13 ... Exposure device, 14 ... Developing device, 15 ... Paper conveyance belt, 16 ... Transfer roll, 17 ... Fixing device, 18 ... Cleaning Device: 19 ... neutralizing device, 21 ... environmental sensor, 22 ... magnetic sensor, 23 ... toner sensor, 30 ... input unit.

Claims (11)

An image carrier;
Charging means for charging the image carrier to a predetermined charging potential;
Exposure means for irradiating the charged image carrier with light and forming an electrostatic latent image with an exposure potential determined in the irradiated area;
Developing means for forming a toner image by attaching a toner charged to a reverse polarity of the electrostatic latent image to the electrostatic latent image formed on the image carrier;
A first set-up means for adjusting a charge amount for the charging means to charge the image carrier and an exposure amount for the exposure means to expose the image carrier;
A second set-up means for adjusting an exposure amount for the exposure means to expose the image carrier;
An image forming apparatus comprising: a selection unit that selects one of the first setup unit and the second setup unit as a setup unit to be executed. The selection means includes
If it is possible to charge the image carrier to a desired charging potential before the next scheduled image forming process is started, the first setup means is selected,
2. The image formation according to claim 1, wherein when the image carrier cannot be charged to a desired charging potential until the next scheduled image formation process is started, the second setup unit is selected. apparatus. The image forming apparatus according to claim 1, wherein the selection unit selects the first setup unit in a standby state or between successive image formation jobs. The image forming apparatus according to claim 1, wherein the selection unit selects the second setup unit between successive image forming processes in the same image forming job. The image forming apparatus according to claim 1, further comprising an input unit configured to input a selection criterion of the selection unit. Density storage means for storing a target value of the density of a reference image serving as a reference for the adjustment;
Density detecting means for detecting the density of the developed toner image,
The first setup means includes
The density of the toner image formed by the developing unit and obtained based on the detection by the density detection unit is compared with the target value stored in the density storage unit, and the comparison result is determined. The image forming apparatus according to claim 1, wherein at least one of the charge amount and the exposure amount is adjusted. Density storage means for storing the density of a reference image serving as a reference for the adjustment;
Density detecting means for detecting the density of the developed toner image,
The second setup means includes
The density of the toner image based on the reference image formed by the developing unit and obtained by the density detection unit is compared with the density of the reference image stored in the density storage unit, and the comparison result is The image forming apparatus according to claim 1, wherein the exposure amount is adjusted accordingly. The image forming apparatus according to claim 1, wherein the charging unit charges the image carrier by a surface charging method. The first setup means adjusts the exposure amount so that the exposure potential of the image carrier does not change before and after the adjustment of the charge amount,
The image forming apparatus according to claim 1, wherein the second setup unit adjusts an exposure amount so that the image carrier has a predetermined exposure potential. The first setup means includes
An adjusting means for adjusting a developing bias potential for charging the toner in the developing means;
At least one of the charge amount and the exposure amount while maintaining a constant ratio between the difference between the charging potential of the charging unit and the developing bias potential of the developing unit and the difference between the developing bias potential and the exposure potential of the exposing unit. The image forming apparatus according to claim 1. The second setup means includes
An adjusting means for adjusting a developing bias potential for charging the toner in the developing means;
The exposure amount is corrected while a ratio between the difference between the charging potential of the charging unit and the developing bias potential of the developing unit and the difference between the developing bias potential and the exposure potential of the exposing unit is made constant. Image forming apparatus.

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