JPH03170957A - Image forming operation controller for electronic image forming device - Google Patents

Abstract

PURPOSE:To detect the extent of variation of a photosensitive drum with simple constitution and to control image forming operation properly by controlling the image forming operation according to the detection result of the grid current of an electrostatic charging device. CONSTITUTION:The image forming operation controller 30 detects a current flowing to a grid by a grid current detecting means 36. This grid current varies linearly as the use of the photosensitive drum is advanced, so the grid current is used as a control parameter to control the image forming operation of the image forming device properly without measuring the state of the photosensitive drum directly. Consequently, the extent of variation of the photosensitive drum is detected with the simple constitution and an image forming operation control means 1 controls the image forming operation properly.

Description

[Detailed description of the invention] [Industry] Second usage branch] Kiwamon is an image forming operation control device, '! 'i, ・:i
}A photoconductor charged by an electric device)
This invention relates to an image forming operation control device for an image forming apparatus that forms images. [Prior art and its problems] Image forming devices, such as copying machines and laser printers, generally form an electrostatic latent image on a rotating photoreceptor drum, develop the latent image with toner, and create a toner image. is transferred onto transfer paper. The toner remaining on the photosensitive drum after the transfer process is removed by a cleaning device. As the photoreceptor drum, a photoreceptor drum using an organic photoreceptor has recently been adopted. However, since this type of photoreceptor drum has a relatively low surface strength, a problem arises in that the photoreceptor layer is quickly scraped away by the blade of the cleaning device. When the photoreceptor layer is scraped and becomes thinner, this leads to problems such as a decrease in surface potential or a change in sensitivity, which shortens the life of the photoreceptor drum. Therefore, in order to solve this problem, if the pressing force of the blade against the photoreceptor drum is set weakly, the oxidized surface layer will not be removed, and the charging property of the photoreceptor drum will be reduced based on the oxidation of the n-type photoreceptor. to degrade.

On the other hand, in the image forming apparatus disclosed in Special Question No. 64-91160, deterioration of the characteristics of the photoreceptor drum is detected every time the grid current of the Scorjtron is detected, and the necessity of maintenance of the photoreceptor drum is indicated. It looks like this.
However, in this case, the change in grid current is:
It only performs binary processing at °C using a single inverter, and can simply determine whether the photoreceptor drum is good or bad.

SUMMARY OF THE INVENTION An object of the present invention is to detect the degree of change in a photoreceptor drum of an electronic image forming apparatus using a simple configuration, and to provide an image forming system that can appropriately control image forming operations.
The objective is to provide a l device.

[Means for Solving the Problems] An image forming control device according to the present invention is an image forming apparatus that forms both images using a photosensitive drum charged by an electric device. It is a forming operation control i■ device. This control device includes a grid disposed on the side of the photoreceptor 1 and 1 of the charging device, a grid current detection means for detecting the current flowing through the grid, and amphoteric formation based on the detection result by the grid current detection means. and an image forming operation control means for controlling the image forming operation of the apparatus.

[Effect]

The image forming apparatus forms images using a photoreceptor drum that is powered by an IF electric device. At this time, in the image type motion control device, the grid current detection means detects the current flowing through the grid. According to the inventor's study, this grid current changes linearly as the use of the photoreceptor]'ram progresses.

Therefore, by using the grid current as a control parameter, it is possible to appropriately control the image forming operation of the image forming apparatus without directly measuring the condition of the photoreceptor drum. Therefore, the image forming operation control means controls the image forming operation of the image forming apparatus based on the result from the grid current detecting means. As a result, the degree of change in the photoreceptor drum can be detected using the atr=- structure, and the image forming operation can be appropriately controlled.

〔Example〕

FIG. 1 shows an example of a copying machine employing an embodiment of the present invention.

In Figure 1, ゜C, A↓ original striped stand 2
is fixed, and a document holder 3 that can be opened and closed is disposed on the document table 21. On the right side of the multi-VA main unit 10,
A bypass tray 4 and a pair of paper feed cassettes 5.6 are removably attached. On the figure k side of the copying machine main body 1,
A haiku paper tray 7 from which the copied paper is outputted is installed.

Inside the copying machine I, an exposure device 8 for reading the original V4 is provided at the top.

This exposure device 8 is composed of a light source, a mirror, and the like. Further, a photosensitive drum 9 on which an electrostatic latent image is formed is arranged in the center of the copying machine body 1. Here, the photoreceptor drum 9 is constituted by, for example, an IT machine photoreceptor. Around the photoreceptor drum 9, there is a photoreceptor drum 9.
A main electronic device 10 that charges 4JF to a predetermined charge, a developing device 11 that develops the electrostatic latent image, a transfer device 12 that transfers the toner image onto the paper, and a device that separates the paper from the photosensitive drum 9. River paper separator i13 and photosensitive drum 9-I:.
A cleaning device W14 is arranged to remove the remaining toner.

Between the bypass tray 4, the paper feed cassette 5.6, and the image forming section constituted by the photosensitive drum 9, etc., and on the downstream side of the image forming section, there are provided a paper feed conveyance path 17 and a paper conveyance path 17 for conveying paper, respectively. UF. A paper conveyance path l8 is provided. At the end of the paper feed cassette 5.6 on the paper feed conveyance path 17 side,
Paper feed rollers 16a and 16b are provided for feeding the sheets in the paper feed cassette 5.6 one by one to the paper feed conveyance path l7 side.

Further, between the paper discharge conveyance path I8 and the paper discharge tray 7, there is a fixing device 2 for fixing the transferred image on the paper that has been conveyed.
0 and an ejection port 19 for ejecting the paper after fixing are arranged.

The cleaning device l4 includes a cleaning section 14a, a screw conveyor 14b for discharging toner scraped off by the cleaning section 14a, and a housing 14c for housing them.

As shown in FIG. 2, the cleaning section 14a has a blade 21 that comes into pressure contact with the photoreceptor drum 9. As shown in FIG. The blade 2I is an elastic member made of, for example, urethane rubber, and extends in a direction parallel to the center line of the photoreceptor drum 9. The base (upper end) of the blade 21 is connected to the blade holder 22.
Fixed. The upper end of the blade holder 22 is connected to a support shaft 2 rotatably supported by the housing I4c (Figure 1).
It is fixed at 3. Note that the rotation center of the support shaft 23 is parallel to the center line of the photoreceptor drum 9.

A base portion of a cam follower 24 is fixed to the support shaft 23 . The cam follower 24 extends in a direction away from the photoreceptor drum 9 so as to protrude from the support shaft 23 . A cam 25 is in pressure contact with the upper surface of the protrusion 24a of the cam follower 24. An output shaft of a stepping motor 26 is fixed to the rotation center of the cam 25. In addition, the protrusion 24
A is connected to the lower end of a spring 27 whose upper end is engaged with a pin provided in the housing 14c (FIG. 1). The spring 27 is arranged in a stretched state, so that the protrusion 24a is always attached upwardly. As shown in FIG. In addition, the cam surface 25a (outer circumferential surface) of the force 1, 25 is in contact with the notch surface 2B starting from the part closest to the rotation center 0.

Then, the cam surface 25a of the cam 25 is set to gradually move away from the center of rotation 01 from one end of the notch surface 28 in the direction of the arrow X. The force l1 in Figure 2 is the protrusion 24a of the lower back 24.
is in contact with "ζ". Note that even if the force J is the part a closest to the center 01 of the surface 25a, the cleaning device 114
The force l and the shape of the surface 25a are set so that the basic cleaning operation of the surface 25a can be maintained.

As shown in FIG. 4, the main electric device 10 has an electric IE applying wire extending parallel to the center line of the photoreceptor drum 9.
I' 1 0 a, a shield gauge i0b that covers the wire IOa from the outside, a photosensitive drum 9 and a wire lOa.
The main IF electrical equipment n10 is a so-called scorotron. A constant current power supply 40 is connected.
A grid current sensor 36 is arranged on the grid 10c to measure the current flowing through the grid loc. Between the grid 10c and the power supply 41, there is a grid l.
(A constant voltage power supply 41 for maintaining lc at a predetermined potential is connected.

Furthermore, this copying machine has a control unit 3 shown in FIG.
It has 0. The control unit 30 includes a CPU 3 1, RO
M3 2, RAM33 and I/0 baud 1-: I/
It includes a microcomputer with I. The above-mentioned grid current sensor 36 is connected to the I/O boat 34 of the control unit 30 via the 8D converter 35.

Also, L. The stepping motor 26 described above is connected to the I/O boat 34 via a ]' lever 37. Further, the I/O boat 34 is connected to a key panel 38 and other input/output units provided on the main body of the multifunction device l.

2C O, R O M 3 2 D is the control program
In addition to x, etc., information regarding grid current is stored.

According to the study results of the present inventors, if the surface potential of the photosensitive drum 9 decreases as the surface potential of the photosensitive drum 9 progresses, the grid current also changes accordingly. Further, this change in grid current can be expressed by the following function.

Therefore, under various conditions regarding the supply current to the wire IOa of the main electric device 10 and the grid voltage, how should the ζ grid current ideally change as the number of copies increases? , r?OM3 2
is stored as a linear equation with the number of copies as a parameter. Some examples of data based on actual experiments are shown in Table I. In addition, in Table I, IOOK is the number of copies 1
00,000 sheets, and SP means the surface potential of the photoreceptor drum l1.

Table 1 From such data, the relationship between grid current and surface potential can be expressed by a linear equation as shown in Figure 7. On the other hand, R.A.
M3 3 contains non-volatile memory. This R
The non-volatile memory of AM33 includes a total counter TT that records and stores the number of times the photosensitive drum 9 is used, converts it into the number of copies, a counter C'F that is used to calculate the blade adjustment timing, and a stepping motor. Record the setting position of cam 25 according to 26? ．． A storage area is provided for the IPN of the cam to be used. This copier has a total counter TT and a counter CT when it is not in use.
is set to 0, and the cam position PN is set to the C position of the cam surface 25a in FIG. Next, the operation of the above embodiment will be explained according to the control flowcharts shown in FIGS. 6A to 6C. When a main switch (not shown) is turned on, initial settings such as setting the number of copies to 1 and setting the fixing device i120 to a predetermined temperature are performed in step Sl in FIG. 6A. Next, in step S2, the key panel 38
Determine whether the print key has been pressed. If the print key is not pressed, the process moves to step S3, and it is determined whether it is time to replace the photosensitive drum 9. Here, it is determined whether the total counter TT has reached a predetermined number of sheets (usually about 10,000 sheets) as the lifespan of the drum 9. If the determination is No, the process moves to step S4. In step S4, it is determined whether or not a shift to reset mode has been instructed by a service person or the like during maintenance. If the transition to reset mode is not instructed, the process moves to step S5. In step S5, other processes such as resetting the number of copies are performed as necessary. When the process in step S5 is completed, the process returns to step S2. Here, if the print key on the key panel 38 is pressed to start the copying operation, the program moves from step S2 to step S6. In step S6, the copy operation subroutine shown in FIG. 6B is executed. In step S7 of FIG. 6B, the counter CT is incremented. In step S8, the total counter TT is incremented. Next, in step S9, it is determined whether it is time to adjust the pressure contact force of the blade 21.
This judgment is made by converting the number of copies, and the counter CT
This is determined based on whether the O value has reached, for example, 2000. If the blade tA alignment time has not been reached, the process moves to step 510. In step SIO, a copying operation is started. Next, in step Sll, cam 2
5 at the specified position PN using the stepping motor 2G. In the initial state, as a result, the C portion of the cam surface 25a of the cam 25 comes into contact with the protrusion 24a. As a result, the blade 2l is pressed against the photoreceptor drum 9 with a pressing force corresponding to the distance from the rotation center Ol to the cam surface 25a. Subsequently, the remaining copying operations are performed in step S12. In a series of copying operations, first, the paper feed cassette 5.6
A sheet of paper designated by the above is fed to the photosensitive drum 9 side, and image information of the document placed on the document table 2 is read by the exposure device 8. Further, the obtained image information is transferred onto paper using the photosensitive drum 9. moreover,
After the paper onto which the image has been transferred is subjected to a fixing process in the fixing device 20, it is discharged to the paper discharge tray 7. On the other hand, the surface of the photosensitive drum 9 after the transfer process is cleaned in a cleaning device l4. In this case, the blade 2l of the cleaning device 14 comes into pressure contact with the surface of the photoreceptor drum 9, thereby removing residual 1/toner adhering to the surface of the photoreceptor drum 9. The removed residual toner is discharged to the outside by the screw conveyor 14b. Note that as the photoreceptor drum 9 rotates simultaneously with the blade 21 in pressure contact, the blade 21 not only removes the toner but also removes the toner from the photoreceptor. Slightly scrape off the surface of drum 9.

As a result, the oxidized layer on the surface of the photoreceptor drum 9 is removed, and a fresh organic photoreceptor is always exposed on the surface of the photoreceptor drum 9. This ensures a good copying operation.

In step S13, it is determined whether the copying operation for the specified desired number of sheets has been completed. If the determination is NO, the processing from step S7 onwards is performed again. Step 313
If the determination is Yes, the process moves to step S14. In step Sl4, the cam 25 is rotated by the stepping motor 26 to arrange the notch surface 28 on the protrusion 24a side. As a result, the protruding portion 24a is connected to the spring 2
7, the support shaft 23 rotates,
The blade 21 is separated from the photoreceptor drum 9. As a result, not only is deterioration of the photoreceptor drum 9 caused by the blade 2l being in pressure contact with the photoreceptor drum 9 for a long period of time prevented, but also permanent deformation of the blade itself is also prevented. When the process in step S14 is completed, the process returns to the main routine shown in FIG. 6A. By repeating the above-mentioned copying operation, the blade 2
1, the surface of the photoreceptor drum 90 is gradually scraped away, and its charging ability is gradually reduced. As a result, as already explained, the grid current changes as the charging capacity changes. Here, an example of the relationship between the grid current obtained by the charging operation by the main charging device 20 and the number of copies is shown in the eighth example.
As shown in the figure. In FIG. 8, a broken line A indicates a value corresponding to the usable limit of the photosensitive drum 9, and normal copying operations cannot be performed below the broken line A. A single-point chain AliB shows an example of a change in grid current that occurs when the C portion of the cam surface 25a is used. A two-dot chain line C shows a change in the imaginary grid current of the photosensitive drum 9 in this copying machine. Referring to FIG. 7, the change in grid current (solid line D) follows the dashed-dotted line B until the initial number of copies is 2000 sheets. When the number of copies reaches 2000, the determination at step S9 in FIG. 6B becomes YcS. As a result, the program moves to step S15, and the blade adjustment subroutine of FIG. 6C is executed.

In FIG. 6C, in step S16, the grid current of the charging device 10 is measured using the grid current sensor 36. Next, in step 517, a comparison is made between the measured grid current and the change in the ideal grid current stored in the preliminary ROM 32 (corresponding to the two-dot M line C in FIG. 8). Here, based on the set values of the supply current and grid voltage, a corresponding change in the grid current is selected from information stored corresponding to various set values of the supply current and grid current.

Next, in step 31B, it is determined whether the pressing force of the blade 2l is too high based on the comparison result in step S17. If the pressing force of the blade 2l is too high, the process moves to step 319, and the cam position PN is changed by one step in the direction of lowering the pressing force of the blade 2l. For example, if the cam position PN is set to the C position, it is changed to the b position. When the process in step S19 is finished, the process moves to step S20. If the determination in step 318 is No, the process moves directly to step S20. In step S20, it is determined whether the pressing force of the blade 2l is too low.

If the determination is Yes, the process moves to step 521, and the cam position PN is changed by one step in the direction of increasing the pressure contact force of the blade 21. For example, when the cam position PN is at the C position, it is changed to the d position. When the process in step S21 is finished, the process moves to step S22. If the determination in step S20 is NO, the process directly proceeds to step S22. In the example of FIG. 8, as a result of the comparison in step 317, it is determined that the grid current decreases (ie, the surface potential decreases) too quickly and the pressure contact force of the blade 21 is too high.
Therefore, the program moves from step 31B to step S19, and the cam position IPN is changed in a direction that reduces the pressure contact force of the blade 2l. In step S22,
The counter CT is reset to count the next blade adjustment special. When the process at step 322 is completed, the process returns to the main routine shown in FIG. 6B. In the case of the example in Figure 8, the first blade adjustment
The cam position PN is changed by one step in the direction in which the pressing force of the blade 21 becomes smaller. As a result, the rate of decrease in surface potential decreases. However, in the example of FIG. 8, even at the next blade adjustment time N, I1 (4000th copy), it is determined that the pressing force of the blade 21 is still too high, so the pressing force of the blade 21 is further reduced. The cam position HpN is changed in the direction. Furthermore, at the next blade adjustment period (the 6000th copy), the actual grid current value is higher than the ideal grid current change value (double-dashed line C in Figure 8). blade 21
The cam position WPN is changed in the direction of increasing the contact force.
In this manner, in the above-described embodiment, the blade adjustment is performed every predetermined number of copies based on the change in the grid current, so that the pressing force of the blade 2l against the photoreceptor drum 9 is maintained in a nearly ideal state. Therefore, the amount of scraping of the photoreceptor drum 9 by the blade 2l is prevented from becoming excessive or insufficient, and the condition of the photoreceptor drum 9 can be maintained in good condition for a long period of time. As the use of the copying machine progresses and the photosensitive drum 9 reaches its usage limit, the program moves from step S3 in FIG. 6A to step 323, and the drum life display on the key panel 38 is lit. When the drum life indicator lights up, the user knows that it is time to replace the photosensitive drum 9. When the photosensitive drum 9 is replaced by a new one by a service person, the reset mode is designated and the program moves from step S4 to step S24.

In step S24, the total counter 'FT and counter CT are each set to 0, and the cam position IPN
is set to position C. When the process in step S24 is completed, the process returns to the main routine again.

[Other Embodiments] (a) The means for changing the pressing force of the blade 2l is not limited to the above-mentioned cam 25. For example, the pressing force of the blade 2l may be changed by using a polygonal cam. Further, the pressure force of the blade 21 can be changed by moving a weight for applying a load to the blade 2l. (t)) The blade pressure may be controlled by measuring and comparing the grid current for each copy operation, instead of adjusting the blade at regular intervals every 2000 copies.

(C) In the above embodiment, the grid current measurement results were used as a parameter for adjusting the pressure contact force of the blade. However, the present invention is not limited to this, and uses the measurement result of the grid current as a parameter to control the exposure amount of the exposure device 8, control the applied voltage of the wire 10a, and control the voltage applied to the developing device Rll.
It can also be used for developing bias control, etc.

〔Effect of the invention〕

In the image forming operation control device according to the present invention, the grid current of Teidenso Otsu is detected by the grid current detection means, and the image forming operation of the image forming apparatus is controlled by the image forming operation control means based on the detection result. Therefore, the degree of change in the photoreceptor drum can be detected with a simple configuration, and the image forming operation can be appropriately controlled.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of a copying machine in which an embodiment of the present invention is adopted, FIG. 2 is a partial vertical cross-sectional view of its cleaning section, FIG. The main IF
A schematic block diagram of the electrical device, FIG. 5 is a schematic block diagram of its control section, and FIG. 6A. Single GTJ diagram. FIG. 6C is a control flowchart, FIG. 7 is a graph showing an example of the relationship between grid current and surface potential, and FIG. 8 is a graph showing the relationship between the number of copies and grid current. 9... Photosensitive drum, IO... Main charging device, 10c
...Grid, 14...Cleaning device, 25.
...Cam, 26...Stepping mode, 30...
Control unit, 36...grid current sensor. Patent source Sanda Kogyo Co., Ltd.

Claims (1)

[Claims] (1) An image forming operation control device for an image forming apparatus that forms an image using a photoreceptor drum charged by a charging device, comprising: a grid disposed on a side of the photoreceptor drum of the charging device; and the grid. a grid current detection means for detecting the current flowing through the grid; and based on the detection result by the grid current detection means,
An image forming operation control device for an electronic image forming apparatus, comprising: an image forming operation control means for controlling an image forming operation of the image forming apparatus.