JP2005010584A - Image forming apparatus and control method for apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep image quality satisfactory by executing an adjustment operation if necessary, and to prevent toner and a processing time from being wasted by inhibiting the adjustment operation if unnecessary. <P>SOLUTION: Whether image forming condition adjustment is necessary or not is determined for each of all the toner colors (step S1 to S4). The toner color determined to need the adjustment, a patch image is formed and, based upon the detection of its density, the image forming conditions are adjusted. On the other hand, the toner color determined not to need the adjustment, the adjustment operation is not performed. This operation prevents waste of toner and waste of processing time from increasing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus configured to be able to mount a plurality of developing devices and to execute a condition control process for controlling image forming conditions based on a density detection result of a toner image as a patch image, and a control method thereof. It is.
[0002]
[Prior art]
In an electrophotographic image forming apparatus such as a printer, a copying machine, and a facsimile machine, a small test image (patch image) having a predetermined image pattern is formed as needed, and the image density is adjusted by a density sensor. A predetermined image density can be stably obtained by detecting and adjusting various image forming conditions based on the detection result.
[0003]
For example, in the image forming apparatus described in Patent Document 1 according to the application of the present applicant, the developing bias that affects the image density is adjusted to an optimum value as follows. That is, a patch image is formed while changing the development bias within the variable range, and the optimum value of the development bias at which the image density becomes the target density is found from the density detection results of those patch images. In order to obtain the optimum value with high accuracy, two processing modes having different development bias variable ranges are prepared, and one of them is selected and executed according to the operation status of the apparatus.
[0004]
[Patent Document 1]
JP 2001-75319 A (FIG. 5)
[0005]
[Problems to be solved by the invention]
By the way, in an apparatus configured to be equipped with a plurality of developing units such as a color image forming apparatus that forms a color image with a plurality of toner colors, a sequence of adjustment of image forming conditions for the plurality of developing units is performed. Configured as an action. That is, once the adjustment process is executed, the image forming conditions are adjusted for all the developing devices. The object is to prevent the quality of the formed image from being different for each developing device and maintain the image quality well.
[0006]
However, since such an image forming condition adjustment operation involves patch image formation, if it is executed too frequently, a large amount of toner is wasted, which increases the running cost of the apparatus. Further, since it takes a long processing time to perform the adjustment operation for all the developing devices, there is a problem that the throughput of image formation is lowered.
[0007]
In this type of image forming apparatus, the developer is generally configured as a cartridge that is detachable from the apparatus main body in order to facilitate repair of the apparatus and replacement of consumables. For such a developer cartridge, the image quality may be different before and after replacement due to variations in characteristics of each cartridge. Therefore, in order to suppress such fluctuations in image quality, it is conceivable to adjust the image forming conditions as described above, for example, when the developer cartridge is replaced.
[0008]
In such a case, it is not always necessary to adjust the image forming conditions for the developing device that has not been replaced. However, in the case of the image forming apparatus of the prior art, the adjustment operation for all the developing devices is executed even in such a case, so that the problem of an increase in running cost and a decrease in throughput still occurs.
[0009]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and while maintaining the image quality satisfactorily by executing the adjustment operation as necessary, the toner and processing time are prevented by not performing the unnecessary adjustment operation. The purpose is to prevent waste.
[0010]
[Means for Solving the Problems]
An image forming apparatus and a control method therefor according to the first invention of the present application are the image forming apparatus configured to be able to mount a plurality of developing devices on the apparatus main body, and the control method thereof. A condition for controlling image forming conditions when forming a toner image as a patch image using a developing device mounted on the toner image and forming the toner image using the developing device based on the density detection result of the patch image Control processing is executed, and for each of the developing devices mounted on the apparatus main body, it is determined whether or not it is necessary to execute the condition control processing for the developing device based on information on the usage status of the developing device. When it is determined that the condition control process needs to be executed for at least one developing device, the condition control process is performed for the developer determined to be necessary. While the row for the other developing devices are characterized not to execute the condition controlling process.
[0011]
In the invention configured as described above, the timing for executing the condition control process is determined according to the usage state of the developing device, so that the condition control process is surely executed when necessary, and as a result, good image quality is achieved. Can be maintained. In addition, since the condition control process is executed only for the developer that is determined to be necessary, unnecessary unnecessary processing operations are not executed, and waste of toner and processing time can be effectively prevented.
[0012]
The image forming apparatus configured as described above may further include a storage unit for storing the information. In this way, it is possible to determine whether or not the condition control process is necessary based on the information regarding the usage status of each developing device stored in the storage unit. Further, this information can be used for managing the usage status of each developing device. For example, when these pieces of information indicate that the life of any of the developing devices has expired, it is possible to notify the user of the fact and prompt replacement.
[0013]
Further, each of the developing devices may be provided with a storage unit for storing information on the usage status of the developing device among the information. This makes it easy to manage the usage status of the developing device. Further, if this storage unit is constituted by a non-volatile memory, for example, it is possible to store the usage status of the developing device even when it is removed from the apparatus body, which is more convenient in terms of developing device management. is there.
[0014]
Here, whether or not condition control processing is necessary for one developing device can be determined as follows, for example. That is, when at least one of the developing devices mounted on the apparatus main body reaches the predetermined control start condition set in advance corresponding to the developing device, the developing device It is determined that the condition control process needs to be executed for the device.
[0015]
In other words, the state of the developing device changes with use, but when the developing device enters a predetermined state in the process, that is, information indicating the usage status of the developing device is a predetermined control start condition. When the condition is satisfied, the condition control process is executed. By doing so, the condition control process is executed at an appropriate timing according to the change in the state of the developing device, so that the image quality is kept good.
[0016]
As part of the “information relating to the use state of the developing device” according to the present invention, for example, toner state information relating to the state of the toner stored in the developing device attached to the apparatus main body can be used. There are various indicators indicating the usage status of the developing device, but according to the knowledge of the present inventor, among them, the one representing the toner state in the developing device has a great influence on the quality of the formed image. Is known to affect. Therefore, by determining whether or not the condition control processing is necessary based on the toner state information indicating the toner state, waste of toner and processing time due to performing unnecessary processing operations while maintaining good image quality is achieved. Can be suppressed.
[0017]
An image forming apparatus and a control method thereof according to the second invention of the present application are the image forming apparatus configured to be capable of mounting a plurality of developing units on the apparatus main body and the control method thereof, in order to achieve the above object, A toner image as a patch image is formed using a developing device attached to the apparatus main body, and image forming conditions for forming the toner image using the developing device are controlled based on the density detection result of the patch image. In addition, when at least one developing device is removed from the apparatus main body and a new developing device is mounted on the apparatus main body, the condition control processing is executed on the mounted developing device. On the other hand, the condition control process is not executed for the other developing devices attached to the apparatus main body before the take-out.
[0018]
In the invention configured as described above, when a new developing device is mounted on the apparatus main body, the condition control process for the developing device is executed, so that there is little fluctuation in image quality before and after the developing device is replaced. . Further, since the condition control processing is not performed for the developing device that is originally mounted on the apparatus main body and has not been replaced, waste of toner and processing time can be effectively suppressed.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a view showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. This apparatus 1 forms a full color image by superposing four color toners (developers) of yellow (Y), cyan (C), magenta (M), and black (K), or black (K) toner. This is an image forming apparatus that forms a monochrome image using only the image forming apparatus. In the image forming apparatus 1, when an image signal is given to the main controller 11 from an external device such as a host computer, the engine controller 10 controls each part of the engine unit EG in accordance with a command from the main controller 11 to obtain a predetermined image. The forming operation is executed, and an image corresponding to the image signal is formed on the sheet S.
[0020]
In the engine unit EG, the photosensitive member 22 is provided so as to be rotatable in an arrow direction D1 in FIG. Further, a charging unit 23, a rotary developing unit 4 and a cleaning unit 25 are arranged around the photosensitive member 22 along the rotation direction D1. The charging unit 23 is applied with a predetermined charging bias, and uniformly charges the outer peripheral surface of the photoconductor 22 to a predetermined surface potential. The cleaning unit 25 removes the toner remaining on the surface of the photosensitive member 22 after the primary transfer, and collects it in a waste toner tank provided inside. The photosensitive member 22, the charging unit 23, and the cleaning unit 25 integrally constitute the photosensitive member cartridge 2, and this photosensitive member cartridge 2 is detachably attached to the main body of the apparatus 1 as a whole.
[0021]
Then, the light beam L is irradiated from the exposure unit 6 toward the outer peripheral surface of the photosensitive member 22 charged by the charging unit 23. The exposure unit 6 exposes the light beam L onto the photosensitive member 22 in accordance with an image signal given from an external device, and forms an electrostatic latent image corresponding to the image signal.
[0022]
The electrostatic latent image thus formed is developed with toner by the developing unit 4. That is, in this embodiment, the developing unit 4 is configured as a support frame 40 that is rotatably provided about a rotation axis center orthogonal to the paper surface of FIG. A yellow developing device 4Y, a cyan developing device 4C, a magenta developing device 4M, and a black developing device 4K are provided. The developing unit 4 is controlled by the engine controller 10. Based on the control command from the engine controller 10, the developing unit 4 is driven to rotate, and the developing units 4Y, 4C, 4M, and 4K are selectively brought into contact with the photoreceptor 22 or have a predetermined gap. When positioned at a predetermined development position opposed to each other, the toner is provided on the surface of the photoconductor 22 from the developing roller 44 provided in the developing unit and carrying the selected color toner and applied with a predetermined development bias. Is granted. As a result, the electrostatic latent image on the photosensitive member 22 is visualized with the selected toner color.
[0023]
Each of the developing devices 4Y, 4C, 4M, and 4K is provided with non-volatile memories 91 to 94 for storing information related to the developing devices. Then, one of the connectors 49Y, 49C, 49M, 49K provided in each developing device is selected as necessary, and the connector 109 provided on the main body side is connected to each other, and the CPU 101 of the engine controller 10 and the memory Communication is performed with 91-94. In this way, information about each developing device is transmitted to the CPU 101, and information in each of the memories 91 to 94 is updated and stored.
[0024]
More specifically, when the developing device is attached to the apparatus main body, the communication is performed between the memory provided in the attached developing device and the CPU 101, and the development stored in advance in the memory. Information regarding the device is read by the CPU 101. This information is stored in the RAM 107 (described later) of the engine controller 10. Among the information, information that changes as the developing device is used is updated and stored as needed by the writing operation from the CPU 101 to the RAM 107.
[0025]
When any of the developing devices is taken out, information about the developing device at that time is written in a memory provided in the developing device before the taking out. As a result, information indicating the use status up to that point is stored in the developing device taken out from the apparatus main body, and the life management of the developing device is facilitated.
[0026]
A more detailed description of the apparatus configuration and operation for realizing such functions is described in, for example, Japanese Patent Application Laid-Open No. 2002-333756 previously disclosed by the applicant of the present application.
[0027]
Returning to FIG. 1, the description of the image forming operation will be continued. The toner image developed by the developing unit 4 as described above is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer region TR1. The transfer unit 7 includes an intermediate transfer belt 71 stretched over a plurality of rollers 72 to 75, and a drive unit (not shown) that rotates the intermediate transfer belt 71 in a predetermined rotation direction D2 by rotationally driving the roller 73. It has. When a color image is transferred to the sheet S, each color toner image formed on the photosensitive member 22 is superimposed on the intermediate transfer belt 71 to form a color image and taken out from the cassette 8 one by one. Then, the color image is secondarily transferred onto the sheet S conveyed along the conveyance path F to the secondary transfer region TR2.
[0028]
At this time, in order to correctly transfer the image on the intermediate transfer belt 71 to a predetermined position on the sheet S, the timing of feeding the sheet S to the secondary transfer region TR2 is managed. Specifically, a gate roller 81 is provided on the transport path F on the front side of the secondary transfer region TR2, and the gate roller 81 rotates in accordance with the timing of the circumferential movement of the intermediate transfer belt 71. S is sent to the secondary transfer region TR2 at a predetermined timing.
[0029]
Further, the sheet S on which the color image is thus formed is conveyed to the discharge tray portion 89 provided on the upper surface portion of the apparatus main body via the fixing unit 9, the pre-discharge roller 82 and the discharge roller 83. Further, when images are formed on both sides of the sheet S, when the rear end portion of the sheet S on which the image is formed on one side as described above is conveyed to the reversal position PR behind the pre-discharge roller 82. The rotation direction of the discharge roller 83 is reversed, whereby the sheet S is conveyed in the direction of the arrow D3 along the reverse conveyance path FR. Then, the sheet is again placed on the transport path F before the gate roller 81. At this time, the image is transferred first on the surface of the sheet S on which the image is transferred by contacting the intermediate transfer belt 71 in the secondary transfer region TR2. It is the opposite surface. In this way, images can be formed on both sides of the sheet S.
[0030]
Further, a density sensor 60 and a cleaner 76 are provided in the vicinity of the roller 75. The density sensor 60 optically detects the density of a toner image as a patch image formed on the intermediate transfer belt 71 as will be described later, as necessary. That is, the density sensor 60 irradiates light toward the patch image, receives reflected light from the patch image, and outputs a signal corresponding to the reflected light amount.
[0031]
The cleaner 76 is configured to be freely separated from and abutted on the intermediate transfer belt 71, and scrapes off residual toner on the belt 71 and toner constituting the patch image by contacting the intermediate transfer belt 71 as necessary.
[0032]
In addition, the apparatus 1 includes a display unit 12 controlled by the CPU 111 of the main controller 11 as shown in FIG. The display unit 12 is constituted by, for example, a liquid crystal display, and in accordance with a control command from the CPU 111, the operation guidance to the user, the progress of the image forming operation, the occurrence of an abnormality in the apparatus, the replacement timing of any unit, etc. A predetermined message for notification is displayed.
[0033]
In FIG. 2, reference numeral 113 denotes an image memory provided in the main controller 11 for storing an image given from an external device such as a host computer via the interface 112. Reference numeral 106 is a ROM for storing a calculation program executed by the CPU 101, control data for controlling the engine unit EG, and the like. Reference numeral 107 is a RAM for temporarily storing calculation results in the CPU 101 and other data. is there.
[0034]
Next, an image forming condition adjusting operation executed in the image forming apparatus will be described. In this image forming apparatus, the CPU 101 executes the image quality management operation shown in FIG. 3 as needed to determine whether or not it is necessary to perform condition control processing for each toner color with the toner color, and determines that it is necessary. For the toner color, a condition control process (FIG. 6) for adjusting the image forming condition is subsequently performed. Thereby, the image forming conditions are adjusted so that predetermined image quality can be stably obtained.
[0035]
FIG. 3 is a flowchart showing the image quality management operation in this embodiment. In this process, first, one of yellow, magenta, cyan, and black toner colors is selected (step S1), and it is determined whether an adjustment operation with the selected toner color is necessary (step S2). . How to determine whether or not it is necessary will be described in detail later. For the toner color determined to be necessary, the toner color is set as “necessary color” (step S3). On the other hand, this setting is not performed for the toner color determined to be unnecessary.
[0036]
When the above steps S1 to S3 are repeated for all the toner colors (step S4), among the four toner colors of yellow, magenta, cyan, and black, only the toner color that requires condition control processing is changed to the necessary color. Is set. Then, the condition control process shown in step S5 is subsequently executed only for the toner color set as the necessary color. The details of the condition control process will be described later.
[0037]
FIG. 4 is a flowchart showing the necessity determination process for the adjustment operation performed in step S2 of FIG. In this necessity determination process, as shown in FIG. 4, the determination process is roughly divided into two stages, that is, necessity determination 1 (steps S21 to S23) and necessity determination 2 (steps S24 to S26) for each toner color. It is determined whether or not it is necessary to adjust the image forming condition with the toner color.
[0038]
Necessity determination 1 is determination processing corresponding to the second invention of the present application. That is, whether or not the image forming conditions need to be adjusted is determined based on whether or not the toner color developer has been replaced. Specifically, first, it is checked whether or not the user has performed an operation of mounting the developing device on the apparatus main body (step S21).
[0039]
The presence / absence of the mounting operation can be determined, for example, by whether or not an opening / closing operation of a cover (not shown) that is provided in the apparatus main body so as to be freely opened and closed and covers the developing unit 4 is performed. That is, for example, a cover sensor using a limit switch for detecting the opening / closing of the cover is provided, and it is determined whether the opening / closing of the cover has been performed based on an output signal of the cover sensor. When the opening / closing operation is performed, it can be estimated that the developer has been taken out or mounted. Further, whether or not the developing device is attached can be determined by whether or not communication from the CPU 101 to the memory provided in the developing device is established after the cover is closed. Here, the cover is opened and closed, and if the communication between the CPU 101 and the memory provided in the developing device is established after the cover is closed, “YES” is determined. In other cases, that is, the cover is opened and closed. If the cover is opened or closed but the subsequent communication is not established (that is, the developing device is not attached), the determination is “NO”.
[0040]
If the result of determination in step S21 is NO, that is, if the developing device mounting operation has not been performed, the process proceeds to step S24, and necessity determination 2 described later is executed. On the other hand, when the determination result here is YES, that is, when the developing device is mounted, the information stored in the memory provided in the developing device is subsequently read and stored in the RAM 107 of the engine controller 10. Verification with the information is performed (step S22). This is a step for determining whether or not the installed developing device is the same as the developing device previously taken out from the apparatus main body.
[0041]
As described above, in this apparatus, prior to removal of the developing device, information regarding the usage status of the developing device is written in the memory of the developing device. Accordingly, when the developer once taken out is remounted, the content of the information read from the memory should match the content written earlier. The same applies to the case where the cover is simply opened and closed and the developer is not attached or detached. On the other hand, if the installed developer is an individual different from the one previously taken out, or even if it is the same individual, the usage status has changed due to use in other devices, etc. The contents of these information do not match.
[0042]
In this embodiment, the installed developer is the same as the previously removed developer, and there has been no change in usage due to, for example, being used in another device or being replenished with toner. At this time, it is assumed that the taken-out developing device and the mounted developing device are “the same individual”.
[0043]
As described above, the engine controller 10 stores the information written in the memory at the time of the previous extraction, collates this information with the information read from the memory of the next installed developing device, and based on the result. Then, it is determined whether or not the mounted developing device is the same as the developing device previously taken out (step S23).
[0044]
If the result of this determination is NO, that is, if both developing devices are not the same individual, it is necessary to readjust the image forming conditions. Therefore, the process proceeds to step S28 without determining necessity / unnecessity determination 2, and determines that the image forming conditions need to be adjusted for the developing device.
[0045]
On the other hand, when the result of determination in step S23 is YES, that is, when both developing devices are the same unit, the developing device is simply removed from the apparatus main body and remounted as it is. In this case, since there is no change in the usage status of the developing device, it is not always necessary to readjust the image forming conditions. Rather, adjusting the image forming conditions in this case is a waste of toner and processing time. Therefore, if the installed developing device and the taken-out developing device are the same, the process proceeds to step S24, and further necessity determination 2 is performed to determine whether adjustment of image forming conditions is necessary.
[0046]
Necessity determination 2 is determination processing corresponding to the first invention of the present application. That is, it is processing for determining whether or not adjustment of image forming conditions is necessary in view of the usage status of the developing device. Here, in view of the fact that the variation in the characteristics of the built-in toner greatly affects the image quality among the usage conditions of the developing device, information on the use status of the built-in toner, more specifically, exposure corresponding to the toner color. An integrated count value of the number of dots formed on the photosensitive member 22 by the unit 6 (hereinafter referred to as “dot count value”) and an integrated value of the rotation time of the developing roller 44 of the developing device (hereinafter referred to as “developing roller rotation time”). To determine whether it is necessary.
[0047]
Here, the “dot count value” is information indicating the amount of toner consumed in the developing device. The easiest way to estimate the toner consumption or remaining amount is to calculate from the integrated value of the number of images formed. However, the amount of toner consumed by forming one image is not constant. It is difficult to know the exact amount of toner by this method. On the other hand, the number of dots formed on the photoconductor 22 by the exposure unit 6 represents the number of dots visualized by the toner on the photoconductor 22, and thus more accurately reflects the amount of toner consumption. Become. Therefore, in this embodiment, the number of dots when the exposure unit 6 forms the electrostatic latent image on the photoreceptor 22 to be developed by the developing unit is counted and stored in the RAM 107, and this dot count value is stored. Is a parameter indicating the toner consumption of the developing device.
[0048]
The “developing roller rotation time” is a numerical value indicating the approximate number of images to be formed, but is information indicating the characteristics of the toner remaining in the developing device at the same time. That is, not all of the toner carried on the surface of the developing roller 44 is used for image formation, but at least a part of the toner is returned to the developing device without contributing to image formation and reused for subsequent image formation. The By being repeatedly used in this manner, the toner gradually deteriorates in fatigue, and the characteristics of the toner change accordingly. That is, even if the toner is not consumed at all, the toner characteristics in the developing device gradually change as the rotation time of the developing roller 44 increases.
[0049]
That is, these pieces of information are information indicating the usage status of the developing unit mounted on the apparatus main body, and are also “toner status information” indicating the status of the toner in the developing unit. Then, the state of the toner in the developing device is estimated by a combination of these two types of information, that is, the dot count value that indicates the toner consumption amount and the developing roller rotation time that indicates the number of formed images. From this state, it is determined whether or not the image forming conditions need to be adjusted. These pieces of information are stored in the RAM 107 of the engine controller 10 and updated whenever the image forming operation is executed and the value thereof is changed.
[0050]
FIG. 5 is a principle diagram for explaining necessity determination 2. In the necessity determination 2, the toner state represented by the combination of the dot count value and the developing roller rotation time is classified into four stages, and the time when the toner state shifts from one stage to the next stage is determined as the image forming condition. It is determined that it is time to make adjustments. That is, a virtual coordinate plane represented by a combination of a dot count value and a developing roller rotation time is divided into four areas (A) to (D) shown in FIG. A point P (development roller rotation time, dot count value) represented by a combination of rotation times shifts from one area to another area is a time when adjustment of image forming conditions is necessary.
[0051]
Among these, the area (A) is an area corresponding to a toner consumption amount of 15 g or less and an image forming number of 1000 sheets (A4 size conversion) or less. When the point P belongs to this region (A), it can be said that the toner is relatively new at that time and the remaining amount is sufficient. The area (B) is an area excluding the above-described area (A) in the area where the toner consumption is 60 g or less and the number of images formed is 5000 or less, and is slightly more toner than the area (A). It corresponds to the state where the deterioration of has progressed. Similarly, the area (C) is an area in which the toner consumption is 100 g or less and the number of formed images is 7000 or less, and the area until the developer reaches the end of its life (toner end) is the area ( D).
[0052]
While the point P is within one area, the image forming conditions are maintained assuming that there is little fluctuation in image quality. On the other hand, when the point P shifts from one area to another, the fluctuation in image quality is large. Therefore, readjustment of the image forming conditions is performed at that time.
[0053]
Returning to FIG. 4, the processing content of necessity determination 2 will be described. The CPU 101 reads out the dot count value and the developing roller rotation time for the toner color developing device stored in the RAM 107 of the engine controller 10 (step S24). Then, from these values, it is determined to which region the point P currently belongs (step S25). The determination result is stored in the RAM 107.
[0054]
Then, the determination result in the necessity determination 2 executed previously is compared with the current determination result to determine whether there is a change (step S26). If both determination results are different, that is, if there is a change in the area to which the point P belongs (YES in step S26), the process proceeds to step S28, and it is determined that the image forming conditions need to be adjusted for the toner color. On the other hand, if both determination results are the same, that is, if there is no change in the area (NO in step S26), it is determined that adjustment of the image forming conditions is unnecessary (step S27). As a result, when the point P reaches a point corresponding to the boundary between two adjacent areas (FIG. 5), it is determined that adjustment of the image forming conditions is necessary.
[0055]
As described above, in the necessity determination process, when a developing device different from the previously extracted developing device is mounted for one toner color (necessity determination 1), and the toner incorporated in the developing device. When the dot count value representing the state of the above and the developing roller rotation time are in a predetermined combination (necessity determination 2), it is determined that the image forming conditions need to be adjusted. The above is the content of the determination shown in step S2 of FIG.
[0056]
Next, the contents of the condition control process (step S5 in FIG. 3) will be described. Many proposals have been made for this type of condition control processing, and these techniques can also be applied to this embodiment. Since the processing content shown here is also one of these known technologies, the outline thereof will be briefly described here.
[0057]
FIG. 6 is a flowchart showing the condition control process in this embodiment. In this condition control process, the development bias given to each developer and the intensity of the exposure beam L (hereinafter referred to as “exposure power”) are variable as control factors that affect the image quality, and these are controlled for each toner color. Is adjusted to an optimum condition for obtaining a predetermined image density.
[0058]
Specifically, first, one of the toner colors determined as the necessary color in the previous necessity determination is selected (step S51). Then, a toner image of a predetermined pattern (for example, a solid image) is formed as a patch image using the toner color developing device while changing and setting the developing bias in multiple stages (step S52), and is formed on the intermediate transfer belt 71. The density of these transferred patch images is sequentially detected by the density sensor 60 (step S53). Thereby, since the relationship between the developing bias and the image density as a control factor is obtained, the optimum value of the developing bias that obtains the target density is obtained based on the relationship (step S54).
[0059]
Subsequently, similarly for the exposure power, a patch image (for example, a fine line image) is formed while being changed and set in multiple stages, and its density is detected (steps S55 and S56). Based on the result, the optimum exposure power is determined. A value is obtained (step S57).
[0060]
When the processing for one toner color is completed in this manner, if there is another toner color that requires the same processing (step S58), the processing returns to step S51 to select another toner color and the above processing is repeated.
[0061]
As described above, the toner color to be subjected to the condition control process is determined according to the status of the apparatus, and the condition control process for all the necessary toner colors is sequentially performed, so that the optimum development bias and the toner color for each toner color can be determined. An optimum exposure power value can be determined for each. For toner colors that have not been subjected to the condition control process, the values obtained in the previous condition control process can continue to be used.
[0062]
The optimum development bias and optimum exposure power values thus obtained are stored in the RAM 107 of the engine controller 10, and when image formation is performed, these values are read from the RAM 107 to set the development bias and exposure power values, respectively. By doing so, it is possible to perform image formation at a predetermined target density.
[0063]
As described above, in this embodiment, for one toner color, when a developing device different from the previously extracted developing device is mounted, and a dot count value indicating the state of toner built in the developing device. When the rotation time of the developing roller becomes a predetermined combination, it is determined that adjustment of the image forming condition for the toner color is necessary, and the image forming condition is continuously adjusted for the toner color. For this reason, it is possible to stably form an image with good image quality by suppressing fluctuations in image quality due to replacement of the developing device and change in toner characteristics.
[0064]
Further, the adjustment of the image forming conditions is performed only for the toner color determined to be necessary, and is not performed for the other toner colors. In this way, condition control processing is executed only for the necessary toner colors when necessary, so that toner and processing time are not wasted, effectively suppressing an increase in running costs and a decrease in throughput. can do.
[0065]
When there is a change that may affect the image quality for all toner colors, for example, when the photosensitive cartridge 2 is replaced, all of the toner colors are not affected by the above determination. It is desirable to perform a condition control process for the toner color.
[0066]
As described above, in this embodiment, the CPU 101 of the engine controller 10 functions as the “control unit” of the present invention. The RAM 107 functions as the “storage unit” of the present invention, while the memories 91 to 94 provided in the developing devices 4Y, 4M, 4C, and 4K function as the “storage unit” of the present invention.
[0067]
Further, the boundary of each region shown in FIG. 5 provided for the combination of the dot count value indicating the usage status of the developing device and toner and the developing roller rotation time corresponds to the “control start condition” in the present invention. When these combinations reach the boundary between the regions, the control start condition is satisfied and the condition control process is executed.
[0068]
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, necessity determination 1 corresponding to the second invention of the present application and necessity determination 2 corresponding to the first invention of the present application are executed one after another, but these are executed individually. Is possible. That is, whether or not to adjust the image forming conditions may be determined based on the result of only necessity determination 1 or only necessity determination 2.
[0069]
Further, for example, in the above-described embodiment, a combination of a dot count value and a developing roller rotation time is used as information indicating the usage status of the developing device, more specifically, the toner status. It is not limited to this and is arbitrary. For example, in an apparatus including a toner counter that counts the remaining amount of toner in the developing device, the count value may be used, or a toner consumption amount calculated by analyzing an image signal given from a host computer may be used. Moreover, it is also possible to use what combined these information suitably.
[0070]
In the above embodiment, as shown in FIG. 5, the toner state is divided into four stages, and the condition control process is executed when there is a change in the stage. The location of the boundary is not limited to the above, but is arbitrary. Furthermore, in view of the difference in toner characteristics for each toner color, it goes without saying that these sections and their boundaries may be different for each toner color.
[0071]
In the above-described embodiment, each developing device is provided with a memory and information related to the developing device is stored in the memory. However, the present invention is not limited to this. For example, the developing device is provided with a memory. In addition, the present invention can also be applied to an apparatus that manages the usage status of each developing device centrally on the apparatus main body side. Further, in the above embodiment, the memory of the developing device is read / written only when the developing device is attached / detached, but information on each developing device is held in the memory of each developing device, and this is stored as needed. The present invention can also be applied to an apparatus for updating and storing.
[0072]
In the above embodiment, the development bias and the exposure power are used as control factors related to the image forming conditions, and the image forming conditions are optimized by adjusting them. However, as described above, the condition control is performed. Various processing contents and control factors, including known techniques other than those described above, can be applied.
[0073]
In the above-described embodiment, the present invention is applied to an apparatus that forms an image using four color toners of yellow, magenta, cyan, and black. However, the types and number of toner colors are limited to those described above. It is not a thing but arbitrary. In addition to the rotary development type apparatus as in the present invention, the so-called tandem type image forming apparatus in which developing units corresponding to the respective toner colors are arranged in a line along the sheet conveying direction. The present invention is also applicable. Furthermore, the present invention is not limited to the electrophotographic apparatus as in the above embodiment, but can be applied to all image forming apparatuses.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention.
2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG.
FIG. 3 is a flowchart showing an image quality management operation in this embodiment.
4 is a flowchart showing an adjustment operation necessity determination process performed in step S2 of FIG. 3; FIG.
FIG. 5 is a principle diagram for explaining necessity determination 2;
FIG. 6 is a flowchart showing a condition control process in this embodiment.
[Explanation of symbols]
4 ... development unit, 4Y, 4M, 4C, 4K ... developer, 10 ... engine controller, 60 ... density sensor, 71 ... intermediate transfer belt, 91-94 ... memory (storage unit), 101 ... CPU (control means), 107: RAM (storage means), EG: engine unit

Claims (8)

In the image forming apparatus configured to be able to mount a plurality of developing units on the apparatus main body,
A toner image as a patch image is formed using a developing device attached to the apparatus main body, and image forming conditions for forming a toner image using the developing device are determined based on the density detection result of the patch image. A control means for executing a condition control process to control,
The control means determines, for each of the developing devices attached to the apparatus main body, whether or not it is necessary to execute the condition control processing for the developing device based on information on the usage status of the developing device, and at least 1 When it is determined that it is necessary to execute the condition control processing for one developing device, the condition control processing is executed for the developing device determined to be necessary, while the condition control processing is not executed for the other developing devices. An image forming apparatus. The image forming apparatus according to claim 1, further comprising storage means for storing the information. 3. The image forming apparatus according to claim 1, wherein each of the developing units is provided with a storage unit for storing information on a usage status of the developing unit among the information. The control means, when the information on the usage status of the developing device reaches a predetermined control start condition set in advance corresponding to the developing device for at least one of the developing devices mounted on the apparatus main body. The image forming apparatus according to claim 1, wherein it is determined that the condition control process needs to be executed for the developing unit. 5. The image forming apparatus according to claim 1, wherein the information includes toner state information relating to a state of toner stored in a developing unit attached to the apparatus main body. In the image forming apparatus configured to be able to mount a plurality of developing units on the apparatus main body,
A toner image as a patch image is formed using a developing device attached to the apparatus main body, and image forming conditions for forming a toner image using the developing device are determined based on the density detection result of the patch image. A control means for executing a condition control process to control,
When the at least one developing device is taken out from the apparatus main body and a new developing device is attached to the apparatus main body, the control means executes the condition control process for the attached developing device, while An image forming apparatus characterized in that the condition control process is not executed for other developing devices that have been attached to the apparatus main body from the front. In the control method of the image forming apparatus configured to be able to mount a plurality of developing units on the apparatus main body,
A toner image as a patch image is formed using a developing device attached to the apparatus main body, and image forming conditions for forming a toner image using the developing device are determined based on the density detection result of the patch image. Execute the condition control process to control,
For each of the developing units mounted on the apparatus main body, it is determined whether or not the condition control process needs to be executed for the developing unit based on information on the usage status of the developing unit, and the at least one developing unit When it is determined that the condition control process needs to be executed, the condition control process is executed for the developing device determined to be necessary, while the condition control process is not executed for the other developing devices. A method for controlling an image forming apparatus. In the control method of the image forming apparatus configured to be able to mount a plurality of developing units on the apparatus main body,
A toner image as a patch image is formed using a developing device attached to the apparatus main body, and image forming conditions for forming a toner image using the developing device are determined based on the density detection result of the patch image. Execute the condition control process to control,
When at least one developing device is taken out from the apparatus main body and a new developing device is attached to the apparatus main body, the condition control processing is executed for the attached developing device, while the apparatus main body is before being taken out. The control method for an image forming apparatus, wherein the condition control process is not executed for the other developing devices mounted on the printer.

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