JPH09211910A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute simple density control to shorten a density control time and to obtain a stable image with the same density before/after exchange by detecting a characteristic mark with a mark detecting means and providing a density setting control means for controlling set conditions for changing the image density. SOLUTION: The characteristic mark of an intermediate transfer body after exchange is detected by a mark detecting element and a signal on the detection value is transmitted to the mark detection value storage part 5a of the density setting control part 5 and stored. In a comparing part 5c, the mark detection value of the characteristic mark of the intermediate transfer body before exchange is taken out from a precious mark detection value storage part 5b and compared with the after being exchanged. Consequently, when a difference exists, it is judged that the intermediate transfer body after exchange is not the one before exchanged and the information is transmitted to a correction value predicting part 5d. This predicting part 5d predicts a correction value with respect to the set conditions and in a correction value setting part 5e, the correction value is set. Further, the correction value is outputted to a fixed place by a correction value output part 5f.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine,
The present invention relates to an image forming apparatus such as a printer and a fax, and more particularly to a color image forming apparatus including a detachable photoconductor or an intermediate transfer body.

[0002]

2. Description of the Related Art In a conventional color image forming apparatus having a photosensitive member or an intermediate transfer member which can be attached to and detached from an apparatus main body, deterioration of a developer due to image formation, transfer due to environmental change or replacement work. The density balance of the colors of the formed image may be lost due to changes in efficiency and the surface potential of the photoreceptor. In this case, adjustment of the color density balance is troublesome, so a toner patch of standard density is formed on the photoconductor or intermediate transfer member, the density of the formed toner patch is measured with a photo sensor, and the measured value of the photo sensor is measured. Is compared with a specified value as a reference, and if there is a difference between the two, the development bias or charging bias is adjusted, and the density of the reformed toner patch is measured with a photo sensor and controlled. The above cycle is repeated until the reference value stored in the copy is reached. When there is no difference between the two, the same process is performed for another color, and when all the colors are finished, the preparation for image formation is completed.

[0003]

In the above prior art,
A toner patch of standard density is formed on the photoconductor or intermediate transfer body, the density of the formed toner patch is measured with a photo sensor, and the measured density is compared with a standard density value, and there is a difference between the two. The toner patch is formed many times while repeatedly adjusting the developing bias or the charging bias until the charge disappears. Therefore, when the surface potential of the photosensitive member or the transfer efficiency of the intermediate transfer member changes due to the replacement of the photosensitive member or the intermediate transfer member, the toner cannot be changed under the conventional setting conditions without knowing the changed state. The only option was to form a patch. Therefore, there is a problem that it takes a lot of time to adjust the density and it is difficult to obtain a stable image having the same density before and after the replacement of the photoconductor and the like. Therefore, an object of the present invention is to add a characteristic mark indicating the characteristics to the outside of the image forming area of the photoconductor or the intermediate transfer member at the time of manufacturing, and to replace the characteristic mark when the photoconductor or the intermediate transfer member is replaced. Is detected first, the correction value of the developing bias or charging bias according to the difference from the detection value used so far is predicted, and the toner patch is formed after the correction is corrected to the set value. Accordingly, it is an object of the present invention to provide an image forming apparatus capable of easily performing density adjustment, shortening the density adjustment time, and obtaining stable images of the same density before and after replacement.

[0004]

In order to achieve the above-mentioned object, the first means is to develop a photoreceptor which can be attached to and detached from an apparatus main body and an electrostatic latent image formed on the photoreceptor with toner. A developing device, a removable intermediate transfer member that sequentially transfers the toner images of a plurality of colors formed on the photoconductor, and carries the toner images in an overlapping manner, and an image forming area of the photoconductor or the intermediate transfer member. And an image forming apparatus having a mark detecting means for detecting a characteristic mark representing the characteristic of the photoconductor or the intermediate transfer member, wherein the mark detecting means detects the characteristic mark to form an image. It is characterized in that a density setting control means for controlling setting conditions for changing the density is provided. A second means is characterized in that the photosensitive member and the intermediate transfer member are detachably integrated. A third means is characterized in that, in the first or second means, the density setting control means controls the image density by controlling the setting condition of the developing bias or the charging bias. The fourth means is the first and the second.
Alternatively, in the third means, the mark detecting means also detects the position mark indicating the image forming area of the photoconductor or the intermediate transfer body in combination.
A fifth means is the fourth means, wherein when the density detection control means detects different detection values of the characteristic mark by the mark detection means, it is the photoconductor or the intermediate transfer body, or It is characterized in that it is judged that the integral type photoconductor and the intermediate transfer body have been exchanged.

[0005]

In the image forming apparatus constructed as the first means, if the characteristic mark corresponding to the characteristic is added at the manufacturing stage of the photosensitive member or the intermediate transfer member, the photosensitive member or the intermediate transfer member is exchanged. At this time, since the characteristic mark is detected by the mark detecting means and the setting condition for determining the image density according to the value detected by the density setting control means can be controlled, the density can be easily adjusted, and the density adjustment time can be adjusted. Thus, it is possible to provide an image forming apparatus capable of obtaining an image with stable density even when the photosensitive member or the intermediate transfer member is changed. In the image forming apparatus configured as the second means, since the photosensitive member and the intermediate transfer member of the first means have a detachable integral structure, the surface potential of the photosensitive member or the intermediate potential is lowered. Even if the transfer efficiency of the transfer body changes, since it is an integrated type, it is possible to reliably predict the setting conditions that should be corrected by adjusting both changes, and the density adjustment can be performed more easily. Thus, it is possible to provide an image forming apparatus capable of obtaining an image with stable density even when the photosensitive member or the intermediate transfer member is changed.

In the image forming apparatus configured as the third means, the characteristic mark is detected by the mark detecting means, and the setting condition of the developing bias or the charging bias is controlled according to the value detected by the density setting control means. Therefore, the bias voltage suitable for the photoconductor or the intermediate transfer member being used allows the density to be adjusted quickly, which shortens the time for adjusting the density and prevents the photoconductor or the intermediate transfer member from changing. An image forming apparatus that can obtain an image with stable density can be provided. In the image forming apparatus configured as the fourth means, the mark detecting means can also detect the position mark indicating the image forming area of the photoconductor or the intermediate transfer body, so that the mark detecting element can be shared. It is also cheap in terms of cost,
Moreover, it is possible to solve the trouble of space.
In the image forming apparatus configured as the fifth means, when the value of the characteristic mark detected by the mark detecting means is different from that before the replacement, the photosensitive member or the intermediate transfer member or the integrated type Since it is determined that the photosensitive member and the intermediate transfer member have been replaced, the replacement timing can be accurately grasped by resetting the counter or the like for counting the number of sheets used for image formation.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a side view showing a main part of a color printer. Since the detailed structure and function of the color printer are known, only the outline related to the present invention will be described. In FIG. 1, the photosensitive belt 1a of the photosensitive member 1 is uniformly charged by coming into contact with the charging roller 6 biased by the variable power source 7. Further, the light of the laser optical device 8 which emits light based on image information exposes and scans the surface of the photosensitive belt 1a to form an electrostatic latent image. Here, for the image information to be exposed, a desired color image is selected from yellow, magenta, cyan, and
This is monochromatic image information decomposed into black color information. The electrostatic latent image formed on the surface of the photoconductor belt 1a is subjected to predetermined yellow, magenta, cyan, and
The image of each color is developed with the black toner, and the image of each color is formed on the photosensitive belt 1a.
Form on the surface. The image of each color formed on the surface of the photosensitive belt 1a is an intermediate transfer of the intermediate transfer body 3 which rotates together with the photosensitive belt 1a in the arrow A direction in the figure and rotates in the arrow B direction in synchronization with the photosensitive belt 1a. The yellow, magenta, cyan, and black single colors are sequentially transferred and superposed on the body belt 3a.

On the other hand, the printing paper in the paper feed cassette 9 is conveyed by the paper feed roller 10 and the conveyance roller 11,
At the position of the registration roller 12, the timing is matched with the image on the intermediate transfer body belt 3a. After that, the images of the respective colors, which are transferred and superposed on the intermediate transfer belt 3a, are collectively transferred onto the printing paper by the function of the transfer roller 13. The transferred printing paper is conveyed to the fixing device 14,
After being thermally fixed by the heating roller 14a and the pressure roller 14b, it is discharged to the outside by the discharge roller 15 and stored in a storage stacker (not shown). Here, the photoconductor 1
Alternatively, considering the case where the intermediate transfer member 3 is replaced, the surface potential of the photosensitive member 1, the transfer efficiency of the intermediate transfer member 3, and the like change depending on the manufacturing conditions. Therefore, before replacement, the toner density during image formation is optimal. Even if the state is maintained, a state that deviates from the optimum state occurs after replacement. For example, when the intermediate transfer body 3 is replaced in FIG. 1, a characteristic mark 17 (see FIG. 4) corresponding to the characteristics of the intermediate transfer body 3 is added at a proper position outside the image transfer area on the intermediate transfer body belt 3a at the time of factory shipment. The characteristic mark 17 is detected by the mark detecting element 4a as the mark detecting means 4.

This detection result is sent to the density setting control means 5 for controlling the setting conditions for changing the image density, and the characteristic mark of the intermediate transfer member 3 before replacement stored in the memory of the control means 5 is detected. Compared to the result. As a result of comparing the detection results of both characteristic marks, if the two characteristics are different,
The setting conditions suitable for the characteristics of the intermediate transfer body 3 after replacement are set. The density setting control means 5 operates the variable power source 7 so as to change the charging bias of the charging roller 6 to an optimum value as shown in the figure, and sets the developing bias (not shown) of the developing device 2 to an optimum value. The above adjustment is performed by changing the operation.

The procedure for detecting the characteristic mark 17 will be described in detail below with reference to FIGS. 2 to 6. First, as shown in FIG. 2, the surface of the photoconductor belt 1a of the photoconductor 1 is uniformly charged by the charging roller 6. Next, the light quantity corresponding to the toner patch 18 having the reference density in FIG.
(See FIG. 1) to expose the surface of the photoconductor belt 1a to form an electrostatic latent image corresponding to the density of the toner patch.
FIG. 2 shows the developing unit 2a of the developing device 2 when developing one monochromatic color corresponding to one of yellow, magenta, cyan, and black.
A cross-sectional view of is shown. The toner in the developing unit 2a is supplied in a constant amount from the outside (not shown) by the rotation of the toner conveying screw 2b. The toner developing roller 2e rotates while contacting with the photosensitive belt 1a by adhering toner to the surface by the action of the toner supplying roller 2c and the thin layer blade 2d. The toner remaining in the developing section 2a is discharged to the outside of the developing device 2 by the toner recovery screw 2f.

Therefore, the electrostatic latent image of the toner patch 18 formed on the surface of the photoconductor belt 1a is subjected to reversal development by the developing section 2a, so that it becomes a visible toner image.
Further, the toner image formed on the surface of the photoconductor belt 1a is transferred onto the intermediate transfer body belt 3a which rotates in contact with each other in a synchronous manner to form a toner patch 18 as shown in FIG.
Toner patch 18 on the formed intermediate transfer belt 3a
The density is detected by the density detection sensor 19 that detects the density, and the deviation of the density of the toner patch 18 from the reference value is calculated based on the density value detected by the density detection sensor 19 to calculate a correction value to be corrected. Then, the setting conditions such as the developing bias and the charging bias are changed, the toner patch 18 is formed again, and the density is detected. The above cycle is repeated until the optimum concentration is reached.

If the intermediate transfer body 3 is replaced while the optimum density state is obtained by the above process, the characteristic mark 17 of the intermediate transfer body 3 as shown in FIG. Since it is added at the time of factory shipment,
Before forming the toner patch 18, the mark detecting element 4a
Then, the characteristic mark 17 is detected, and the set value of the instructed developing bias or charging bias is detected. After the detection, the data is sent to the density setting control means 5 so as to match the setting conditions suitable for the characteristics, but the details of the density setting control means 5 will be described with reference to FIG.

In FIG. 5, the characteristic mark 17 of the intermediate transfer body 3 after replacement is detected by the mark detecting element 4a,
A signal related to the detected value is sent to and stored in the mark detected value storage section 5a of the density setting control means 5. In the comparison unit 5c,
The mark detection value of the characteristic mark 17 of the intermediate transfer member 3 before replacement is taken out from the previous mark detection value storage unit 5b and compared with the mark detection value after replacement. If there is no difference between the two values as a result of the comparison, it is assumed that the intermediate transfer body 3 after replacement is the one before replacement, and the set values such as the developing bias and the charging bias are not changed and are left as they are. If there is a difference as a result of the comparison, it is determined that the intermediate transfer body 3 after the exchange is not the one before the exchange, and at the same time the information is passed to the correction value prediction unit 5d.
The contents of the mark detection value storage unit 5a are moved to the previous mark detection value storage unit 5b, and the contents of the previous mark detection value storage unit 5b are rewritten. The correction value prediction unit 5d predicts the correction value for the setting condition from the mark detection values of both, and passes it to the correction value setting unit 5e. The correction value setting unit 5e sets the correction value, and the correction value output unit 5f outputs the correction value to a predetermined location.

FIG. 3 shows that the characteristic mark 17 on the surface of the photosensitive belt 1a can be detected by the mark detecting element 4a when the characteristic mark 17 is added on the surface of the photosensitive belt 1a. Although not shown, the density detection sensor 19 and the mark detection element 4a in FIG.
May be replaced, or the density detection sensor 19 and the mark detection element 4a may detect the surface of the photoconductor belt 1a, respectively. Which configuration is optimum? , The degree of variation in the characteristics of the photoconductor 1 or the intermediate transfer body 3, the replacement frequency, and the like.
FIG. 4 further shows the position detection mark 16 used for timing control of the image area range. If the characteristic mark 17 is added on the same scanning line between both position detection marks 16, the mark detection means 4 for detecting the characteristic mark 17 by the detection means of the position detection mark 16 can be used together.
The mark detection element 4a detects the characteristic mark 17 at the time of power-on, when the cover for replacing the photoconductor 1 or the intermediate transfer body 3 is opened, or at the photoconductor 1
Alternatively, if a replacement detection unit for the intermediate transfer member 3 is provided, the operation is performed when the operation of the replacement detection unit is confirmed. During the normal printing process, the characteristic mark 17 is detected after the first position detection mark 16 of FIG. 4 is detected so that the characteristic mark 17 is not mistakenly detected as the position detection mark 16.
The output of the characteristic mark 17 is controlled so as not to be detected for a certain period of time so that 7 is not detected.

FIG. 6 shows the photosensitive member 1 or the intermediate transfer member 3,
Or, it is a block diagram showing an example of an embodiment (density setting control means) in the case of detecting that the integrated photoconductor 1 and the intermediate transfer member 3 have been exchanged and applying this data to a maintenance cycle or the like. Since the basic operation is the same as that described with reference to FIG. 5, only the main part will be described. In the comparison unit 5c, the mark detection value of the characteristic mark 17 of the intermediate transfer member 3 before replacement is set to the previous mark. It is taken out from the detection value storage unit 5b and compared with the detection value of the characteristic mark of the intermediate transfer body 3 after replacement. If, as a result of comparison, a difference between the two characteristic marks is detected, the mark detection values of the two characteristic marks are transmitted to the correction value prediction unit 5d, and it is determined that the intermediate transfer body 3 after replacement is not the one before replacement. A counting counter provided outside the density setting control means 5 for counting the number of printed sheets is reset. Therefore, when the count value of the counting counter reaches a predetermined value, it is possible to determine the replacement time. In the above description, the photoconductor 1 or the intermediate transfer member 3 before replacement is used.
The mark detection value of the characteristic mark 17 and the mark detection value after replacement are compared, and if there is a difference, a correction value is predicted from both mark detection values, and the development bias or charging bias for the correction value is set. It is designed to change the value, but as a result of comparison, if there is a difference, the correction value is not predicted,
It is considered the same operation to directly set a new mark detection value after replacement.

FIG. 7 is a flowchart showing the main operation when the photosensitive member or the intermediate transfer member or the integrated photosensitive member and the intermediate transfer member are exchanged. Mark detection element 4
The characteristic mark 17 added on the photosensitive member or the intermediate transfer member is detected by a (step S1). The mark detection values before and after the exchange are compared, and it is determined whether the mark detection value before the exchange and the mark detection value after the exchange are the same value (S2). If the same mark detection value is shown (S2 Yes), it is determined that the photoconductor or the intermediate transfer member has not been replaced, and the process exits this flow. If the mark detection values before and after the exchange are not the same in step S2 (No in S2), it is determined that the photoconductor or the intermediate transfer member has been exchanged, and the appropriate development bias or A correction value to be set conditions such as charging bias is predicted (S3), and the setting conditions are changed by the correction value to obtain an appropriate set value (S4). Also,
Assuming that the photoconductor or the intermediate transfer member has been exchanged, the counting counter for counting the number of printed sheets is reset (S
5) Exit this flow. If the characteristics of the photoconductor or the intermediate transfer member vary greatly depending on the manufacturing lot, and there is a possibility that many of the same characteristics will appear in the same manufacturing lot,
Occasionally, the replacement timing of the photosensitive member or the intermediate transfer member described above may be incorrect. In that case, the serial number of the photosensitive member or the intermediate transfer member may be written in the characteristic mark 17 so that all the products have the characteristic mark 17 of different information.

[0017]

As described above, according to the first aspect of the present invention, when the photosensitive member or the intermediate transfer member is replaced, the characteristic mark described in advance is detected and the density setting control means detects the characteristic mark. Since it is now possible to control the setting conditions such as development bias or charging bias according to the value, it is possible to immediately adjust to the optimum value that takes into account the variations in the manufacturing stage of the photoconductor or the intermediate transfer member, and to adjust the density adjustment time. It has become possible to provide an image forming apparatus having a stable image density even before and after the replacement of the photosensitive member or the intermediate transfer member.

According to the second aspect of the present invention, since the photosensitive member and the intermediate transfer member are integrally formed, it is possible to reliably predict the setting conditions for correcting the variations between the photosensitive member and the intermediate transfer member.
It has become possible to easily perform the density adjustment, which has been troublesome until now, and it has become possible to shorten the density adjustment time and provide an image forming apparatus with stable image density before and after replacement.

According to the invention of claim 3, it is possible to easily control the setting condition of the developing bias or the charging bias according to the added characteristic mark, so that it is suitable for the characteristic of the photosensitive member or the intermediate transfer member. Since the bias can be applied and the density can be easily adjusted, the time for adjusting the density can be shortened, and an image forming apparatus having a stable image density before and after replacement can be provided.

According to the fourth aspect of the present invention, the mark detecting element for detecting the characteristic mark and the mark detecting element for detecting the position detecting mark can be used in common, and the cost is low, and the space is troublesome. As a result, the cost of the device can be reduced, the reliability of the device life can be improved, and the size of the device can be reduced.

According to the invention of claim 5, it is possible to accurately grasp that the photoconductor or the intermediate transfer body or the integrated photoconductor and the intermediate transfer body are exchanged. By resetting the counter that counts the number of sheets used at the time of replacement, it is possible to accurately grasp the maintenance cycle of important parts related to image formation in advance, without providing a special detection part for detecting replacement. It was

[Brief description of drawings]

FIG. 1 is a side view of a main part of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a manner of detecting a characteristic mark added on the photoconductor or the intermediate transfer member according to the embodiment of the present invention.

FIG. 3 is another explanatory diagram for explaining how to detect the characteristic mark added on the photosensitive member or the intermediate transfer member according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating the appearance of characteristic marks and toner patches according to the embodiment of the present invention.

FIG. 5 is a block diagram showing a function of a density setting control unit of the image forming apparatus according to the embodiment of the present invention.

FIG. 6 is a block diagram showing another function of the density setting control means of the image forming apparatus according to the embodiment of the present invention.

FIG. 7 is a flowchart showing main operations of the image forming apparatus according to the embodiment of the present invention.

[Explanation of symbols]

1 photoconductor, 1a photoconductor belt, 2 developing device, 2a
Developing unit, 2b toner conveying screw, 2c toner supplying roller, 2d thin layer blade, 2e toner developing roller, 2f toner collecting screw, 3 intermediate transfer member, 3
a intermediate transfer belt, 4 mark detection means, 4a mark detection element, 5 density setting control means, 5a mark detection value storage section, 5b previous mark detection value storage section, 5c comparison section, 5d correction value prediction section, 5e correction value Setting part, 5f
Correction value output unit, 6 charging roller, 7 power supply, 8 laser optical device, 9 paper feeding cassette, 10 paper feeding roller, 11
Conveyor roller, 12 Registration roller, 13 Transfer roller, 14 Fixing device, 15 Discharge roller, 16 Position detection mark, 17 Characteristic mark, 18 Toner patch, 1
9 Concentration detection sensor.

Claims (5)

[Claims] 1. A photoconductor that is attachable to and detachable from the apparatus body,
A developing device that develops the electrostatic latent image formed on the photoconductor with toner, and a removable intermediate transfer that sequentially transfers the toner images of a plurality of colors formed on the photoconductor and superposes them. An image forming apparatus having a body and mark detection means for detecting a characteristic mark which is written outside the image forming area of the photoconductor or the intermediate transfer body and represents the characteristic of the photoconductor or the intermediate transfer body. Then, by detecting the characteristic mark by the mark detecting means,
An image forming apparatus comprising a density setting control means for controlling a setting condition for changing an image density. 2. The image forming apparatus according to claim 1, wherein
The image forming apparatus is characterized in that the photosensitive member and the intermediate transfer member have a detachable integral structure. 3. The image forming apparatus according to claim 1 or 2, wherein the density setting control means controls the image density by controlling a setting condition of a developing bias or a charging bias. Image forming apparatus. 4. The claim 1, claim 2, or claim 3.
In the image forming apparatus described above, the mark detecting means is
An image forming apparatus characterized in that it also detects a position mark indicating an image forming area of the photosensitive member or the intermediate transfer member. 5. The image forming apparatus according to claim 4, wherein
When the detected value of the characteristic mark is detected differently by the mark detecting means, the density setting control means determines whether the photoconductor or the intermediate transfer body, or the integral type photoconductor and the intermediate transfer body. An image forming apparatus, characterized in that it is judged that it has been exchanged.