JPH04134371A - Image forming device - Google Patents

Abstract

PURPOSE:To finely control the surface potential of an image carrier by generating a voltage corresponding to outputted data with a generating means and impressing it on a grid. CONSTITUTION:A D/A converter 73 outputs a reference voltage corresponding to data from memory 77 to a grid voltage generating circuit 80. I generates a grid voltage VG from the reference voltage VGS from the D/A converter 73 and impresses it on the grid 13. Therefore, the grid voltage VG impressed o the grid 13a corresponds to the setting position of a setting key 61d in a later mode. Consequently, the surface potential of a photosensitive drum 12 corresponds to the setting position. Thus, a change inthe grid voltage VG of the electrifying means electrifying the image carrier before an exposure is carried out, is consecutively carried out, and the surface potential of the image carrier is finely controlled.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) This invention provides an image processing system for copying machines and the like that can continuously change the grid voltage of a charger that charges a photoreceptor drum before exposure. The present invention relates to a forming device.

(Prior art) Generally, in a copying machine, a uniform electrostatic charge is applied to the surface of a photoreceptor drum by corona charging, and the surface charge of the exposed area is released by image exposure to form an electrostatic latent image, which is opposite to the latent image. By applying polarized toner to the latent image and making it visible (development) L7, the toner image is transferred to paper and passed through a fixing device.
The toner is heat-fixed.

As the photosensitive drum, OPC (organic
A photoconductor drum is used, and a negative polarity discharge is applied to the photoreceptor drum by a charger. A grid is used to stabilize the discharge characteristics of this charger.

This kind of copying machine has the disadvantage that it is not possible to continuously change the grid voltage of the charger that charges the photoreceptor drum before exposure, and the surface potential of the photoreceptor drum cannot be precisely controlled. .

(Problems to be Solved by the Invention) As described above, this invention solves the problem that the grid voltage of the charging means for charging the image bearing member before exposure cannot be changed continuously, and the surface potential of the image bearing member is This eliminates the disadvantage of not being able to precisely control the image carrier, and allows the grid voltage of the charging means that charges the image carrier before exposure to be continuously changed, allowing fine control of the surface potential of the image carrier. An object of the present invention is to provide an image forming apparatus that can perform the following functions.

[Structure of the Invention] (Means for Solving the Problems) The image forming apparatus of the present invention charges an image carrier with a charging means having a grid that stabilizes discharge characteristics, and charges the image carrier with a charge on the charged image carrier. is exposed by an exposure means to form an electrostatic latent image, this electrostatic latent image on the image carrier is visualized as a developer image by a developing means, and this visualized developer image is transferred to a transfer means. A designation means capable of continuously designating changes in the surface potential on the image carrier, an output means outputting data corresponding to the designation specified by the designation means; It is comprised of a generation means for generating a voltage corresponding to the data outputted by the output means, and an application means for applying the voltage generated by the generation means to the grid.

(Function) The present invention charges an image bearing member with a charging means having a grid that stabilizes discharge characteristics, and forms an electrostatic latent image by exposing the charged image bearing member to light using an exposure means. , in which the electrostatic latent image on the image carrier is visualized as a developer image by a developing means, and the developed developer image is transferred to an image forming medium by a transfer means, wherein the image carrier is A change in the above surface potential is specified by a specifying means that can be specified continuously, data corresponding to this specified specification is outputted by an outputting means, and a voltage corresponding to this output data is generated by a generating means. This generated voltage is then applied to the grid.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 shows the internal structure of a copying machine 1 as an image forming apparatus of the present invention, in which a photosensitive drum (image carrier) 12 is rotatably provided approximately at the center of the main body 11. . Around the photosensitive drum 12, a charging charger 13, an exposure section 14, a developing device 15, 16, a transfer charger 17, and a peeling charger 18 are arranged in order along the rotation direction of the photosensitive drum 12.
, a cleaner 19 and a static eliminator 20 are provided. The charger 13 has a grid 13a that stabilizes the discharge characteristics to the photoreceptor drum 12. The cleaner 19 is provided with a leaning blade 19a that can approach and separate from the photoreceptor drum 12. The static eliminator 20 is constituted by a static eliminator lamp that removes static electricity from the photoreceptor drum 12.

Further, an exposure system 21 is provided in the upper part of the main body 11. The exposure system 21 is composed of an exposure lamp 22, first to third reflecting mirrors 23, 24, 25, a variable magnification lens block 26, and fourth to sixth reflecting mirrors 27, 28, 29.

The main body 11 is placed separably on a desk 51, and paper feed cassettes 30, 31 are provided inside the desk 51 so as to be freely accessible from the front side.

Further, a large capacity paper feeder (LCF) 52'' that can hold 1,000 sheets or more is provided on one side of the main body 11, and a manual paper feeder 53 is provided on the upper surface of this large capacity paper feeder 52. By setting the most frequently used paper (for example, A4 size) P in the large capacity paper feeder (LCF) 52, the number of times paper runs out can be reduced.

The large-capacity paper feeding device 52 includes an upper cover 52a, and this upper cover 52a also serves as a guide for the manual paper feeding section 53. Furthermore, the large-capacity paper feeder 52 includes a paper feed roller 52b and a separation roller 52c, and these paper feed rollers 52b and separation roller 52c are also included in the manual paper feed section 5.
It is also used as the paper feed roller and separation roller of No. 3.

Above paper feed cassette 30.31, large capacity paper feed device (LC)
F) Paper P fed from 52 or manual paper feed section 53
is conveyed along a paper conveyance path 32 provided within the main body 11.

The paper conveyance path 32 includes a registration roller 33 and the transfer/peel charger 17 in sequence along the conveyance direction of the paper P.
．． 18, conveyor belt 34, fixing device 35, paper ejection roller pair 3
6 are arranged.

Further, a document placing table 38 is provided on the upper surface of the main body 11, and a document feeding section 39 is provided on the document placing table 38. This document feeding section 39 includes a take-out section 41 that takes out documents one by one from a document tray 40;
The transport section 43 transports the original document from the document tray 38 and places it on the document placing table 38, and also discharges the original placed on the document placing table 38 onto the ejection tray 42. A detector 44 is provided within the take-out section 41 to detect whether or not a document is set on the document tray 40 .

On the other hand, a sorter device 45 is integrally incorporated in the paper discharge section of the main body 11. This sorter device 45 includes a plurality of bins 46 arranged at predetermined intervals in the vertical direction,
It is constituted by a gate means 47 provided between these bins 46 and the pair of paper discharge rollers 36.

The gate means 47 includes a telescopic and rotatable guide body 48, and a pair of discharge rollers 49 is provided at the rotary end of the guide body 48.

Further, the gate means 4 is provided at the bottom of the bin 46...
7 and a reversing tray 54 that constitutes a continuous reversing means 53.
is provided. On this reversing tray 54, a reversing roller 55 that can move up and down and rotate forward and backward, and a rotatable switching gate 56 are provided.
An idle roller 57 as a feed roller is provided at the lower part of the roller.

When the gate means 47 is moved to the lowest stage, a pair of ejection rollers 49 are disposed on the idle roller 57 and are also used as ejection rollers of the stacker 58, so that the paper P is directly fed into the stacker 58. It has become.

During normal copying, the exposure system 21 scans the original placed on the original placing table 38 with light, and the reflected light forms an image on the photosensitive drum 12 whose surface is charged by the charger 13. to form an electrostatic latent image. This electrostatic latent image is visualized by supplying developer from the developing device 15 or 16. At this time, the paper P is supplied from the paper feed cassette 30.31, the large-capacity paper feed device 52, or the manual paper feed section 53, so that the paper P is transferred to the image transfer section 12g between the photoreceptor drum 12 and the transfer charger 17. The paper P is fed and the developed image on the photosensitive drum 12 is transferred onto the paper P. The paper P to which this image has been transferred is peeled off from the photosensitive drum 12 by the action of the peeling charger 18, and is sent to the fixing device 35 by the conveyor belt 34, where the image is fixed. The paper P on which this image has been fixed is discharged via the paper feed roller 36, and the gate means 4 of the sorter device 45
7 and is discharged onto the top bin 46.

Further, when copying and sorting multiple copies of a document, the gate means 47 is rotated in the vertical direction, and the ejection roller pair 4
9 to each bin 46 and sorted.

In addition, in the case of double-sided copying, the gate means 47 is rotated to the lowest end so that the lower side of the ejection roller pair 49 comes into contact with the idle roller 57, and the reversing roller 55 and the switching gate 56 are moved upward. The paper P on which the image has been fixed and sent from the fixing device 35 is delivered to a pair of ejection rollers 4.
9 and onto the reversing tray 54. Next, the reversing roller 55 is lowered while being reversely rotated and comes into contact with the paper P, and when the rear end of the paper P comes off the paper ejection roller pair 36, the reversing roller 55 is stopped and the gate 56 is rotated downward. Then, at the end of the rotation, the paper P is shot down. Then, the reversing roller 55 is rotated in the reverse direction, and the paper P is sent between the ejection roller pair 49 and the idle roller 57 and is conveyed while being nipped. In this way, when paper P is pinched and conveyed,
The switching gate 56 and the reversing roller 55 are raised.

At this time, the next sheet P is sent to the ejection roller pair 49, and is sent onto the reversing tray 54 in a state overlapping with the previous sheet P. The previous paper P is pinched and conveyed by a pair of discharge rollers 49 and an idle roller 57, and is directly transferred to the stacker 5.
8 will be introduced.

Further, an operation panel 60 is provided at the top of the copying machine 1, and is configured as shown in FIG. That is,
Numeric keypad 60a for setting the number of sheets etc., automatic exposure key 60b for setting automatic exposure, preheating key 6 for selecting preheating state
0c1 Interrupt key 60d1 for selecting an interrupt during continuous copying 60e1 Copy key for instructing the start of copying
Clear stop key 60f for correcting the number of copies or stopping copying midway; all clear key 60g for returning all copy mode to standard mode; density setting key 60h for density setting; paper size for selecting paper size. Key 6011 Original size key 6 to select the original size
0j1 cassette selection key 60 for selecting the cassette; operation guide key 6011 for selecting the guidance display for one operation procedure; zoom key 60m, 160m for changing the magnification;
1x key 6001 to insert when returning the magnification to 1x copy
A magnification display 60o that displays the selected magnification, a document orientation display 60p1 that displays the orientation of the document, an operation status display section 60q that displays the operating status, and a message display section that displays operating procedures and machine status in text. 60r1 Copy number display 60s that displays the number of copies set with the numeric keypad 60a, photo key 61a1 that is set to photo mode when the original is a photo, etc. Setting that sets the degree of photo mode in multiple stages when set to photo mode Key 61b1 Letter key 61c1 is set to letter mode when the original is a letter etc. consisting of letters, and setting key 61d is used to set the degree in multiple stages when set to letter mode.
It is composed of Nyoto.

Next, the main parts of the control circuit of the copying machine 1 will be explained with reference to FIG.

That is, the copying machine 1 is provided with a main control section 71 that controls the entire copying machine 1. This main control section 71 includes
an operation panel 60 for inputting various copying conditions; a high-voltage power supply 72 for applying high voltage to the charger 13, etc.;
A D/A converter 73 as a reference voltage generation circuit that generates a reference voltage for grid setting corresponding to data from the main control section 71, a driver 75 that rotationally drives the main motor 74 that rotates each part, and the static eliminator 20. A driver 76 that drives the lighting, a nonvolatile memory 77 that stores control programs and setting data, and an A/D converter 78 are connected.

A detector 79 composed of a resistor R5 that detects the current value of the photoreceptor drum 12 is connected to the A/D converter 78, and converts the current value detected by the detector 79 into a digital value. It is designed to be output to the main control section 71.

The D/A converter 73 includes the charger 1.
A grid voltage generation circuit 80 that applies a voltage to the grid 13a of No. 3 is connected.

The setting data stored in the memory 77 includes data corresponding to the degree of photo mode set by the setting key 61b in the photo mode, and data corresponding to the degree of letter mode set by the setting key 61d in the letter mode. data and reference data for photo mode and letter mode in serviceman mode are stored.

The main control unit 71 also includes a serviceman key 81 provided on an operation panel (not shown) for servicemen.
The signal is supplied from

The main control unit 71 controls the photo' key 6 on the operation panel 60.
1g, data corresponding to the settings of the setting key 61b is stored in the memory 77.
is read from the D/A converter 7 as reference voltage data.
When the letter mode is set by the letter key 61C of the operation panel 60, the data corresponding to the setting of the setting key 61d is read from the memory 77 and is output to the D/A Konno Kuichi Tough 3 as reference voltage data. Output to.

The main control section 71 controls when the serviceman mode is set by the serviceman key 81, the developing device 79 is pulled out, and the cleaning blade 19a is connected to the photoreceptor drum 12.
Detection results from a detector 79 of leakage current of the photoreceptor drum 12 obtained by charging and eliminating electricity on the photoreceptor drum 12 while being separated from the photoreceptor drum 12 are supplied.

The grid voltage generation circuit 80 generates a grid voltage vG from the reference voltage vGS for grid setting from the D/A converter 73, and for example, as shown in FIG. A differential amplifier 5 constituted by a gain operational amplifier is constituted by a 5SPNP type transistor T1 and Zener diodes D1 to D5.

As a result, for example, when the grid voltage VC falls below a predetermined voltage, that voltage is divided by the resistors R2 and R3 and fed back to the differential amplifier S as a reference value. Then, the output of the differential amplifier S decreases by an amount corresponding to the decrease in the reference value.

As a result, the potential difference at the base of the transistor T becomes smaller, the amplification factor of the transistor T also becomes smaller, and as a result, the grid voltage VG is pulled from the - side toward O by that amount, and the voltage value increases. .

Reference voltage VGS in the grid voltage generation circuit 79
The relationship between and grid voltage vG is as shown in the following equation.

VGs-(VCC ten (R2/(R3 in R2)) x VG
) x O,752+(R2/(R3 in R2))
X V 0 Next, in such a configuration, FIG. 5 (a
) The operation performed by the service person will be explained with reference to the flowchart shown in (b). For example, the serviceman now inputs the serviceman key 81 of the operation panel for the serviceman (not shown).

Then, the main control unit 71 determines the serviceman mode,
Check whether the developing units 15 and 16 are removed and the cleaning blade 19a is removed from the photoreceptor drum 12. If the automatic adjustment is not correct, it is determined that automatic adjustment is prohibited, and the service person is notified to that effect.

If the above conditions are satisfied, the main control unit 71 lights up the static eliminator 20, rotates the main motor 74, turns on the charger 13, and turns on the D/A converter 7.
Set r128J to 3.

As a result, the photosensitive drum 12 is rotated by the rotation of the main motor 74, the surface of the photosensitive drum 12 is charged by the charger 13, and then the electricity is removed by the defroster 20. At this time, r1 is input to the D/A converter 73.
By setting r128J, the reference voltage corresponding to r128J is output to the grid voltage generation circuit 80.

As a result, the grid voltage generation circuit 80
A grid voltage VG is generated from the reference voltage vGS from the converter 73 and is applied to the grid 13a.

Further, the potential on the surface of the photoreceptor drum 12 is discharged via a resistor R8 as a detector 79, and the current value by the resistor R8 is sent to the main control unit via the A/D converter 78 as a detection result. 71. Main control section 71
determines whether the surface potential of the photoreceptor drum is within a predetermined range according to the current value supplied from the A/D converter 78, and transmits the data value to the D/A converter 73 according to the result of this determination. change. That is, if it is smaller than a predetermined range, the main control unit 71 determines that the surface potential of the photoreceptor drum 12 is insufficient, and increases the data value sent to the D/A converter 73. As a result, the grid voltage VG applied to the grid 13a increases (becomes thicker) and the photoreceptor drum 1
The surface potential of 2 increases. After that, the photoreceptor drum 1 is again
Detect the discharge potential of 2. If it is smaller than the predetermined range, the main controller 71 determines that the surface potential of the photoreceptor drum is too high, and reduces the data value sent to the D/A converter 73. As a result, the grid voltage vG applied to the grid 13a decreases, and the surface potential of the photoreceptor drum 12 decreases. Thereafter, the discharge potential of the photoreceptor drum 12 is detected again.

Further, when the surface potential of the photoreceptor drum 12 is within a predetermined range, the main control section 71 controls the D/A converter 7 at this time.
The data value for 3 is stored in the memory 77 as a proper value. Next, the main control unit 71 turns off the electrification charger 13, stops the rotation of the main motor 74, turns off the static eliminator 20, and ends the process.

The storage of data values in the memory 77 by the service person is performed for each of the photo mode and letter mode.

Further, it is determined whether or not the surface potential of the photoreceptor drum 12 has deviated from a predetermined range due to changes in the environment such as temperature and humidity, based on the detection result from the detector 79, and according to the determination result. By changing the data value to the D/A converter 73, the surface potential of the photoreceptor drum 12 is changed due to changes in the environment such as temperature and humidity.

In addition, when the photo mode is set by the photo key 61a of the operation panel 60, the setting key 61b
When the settings are changed, the main control section 71 reads data corresponding to the settings from the memory 77 and sets it in the D/A converter 73. As a result, the D/A converter 73 outputs the reference voltage corresponding to the data from the memory 77 to the grid voltage generation circuit 80. The grid voltage generation circuit 80 generates a grid voltage VG from the reference voltage VGS from the D/A converter 73, and
3a is applied. Therefore, the grid voltage VG applied to the grid 13a corresponds to the setting position of the setting key 61b in the photo mode, and as a result, the surface potential of the photoreceptor drum 12 corresponds to the setting position.

In addition, when the letter mode is set by the letter key 61c of the operation panel 60, the setting key 61d
When the settings are changed, the main control section 71 reads data corresponding to the settings from the memory 77 and sets it in the D/A converter 73. As a result, the D/A converter 73 outputs the reference voltage corresponding to the data from the memory 77 to the grid voltage generation circuit 80. The grid voltage generation circuit 80 generates a grid voltage VG from the reference voltage VGS from the D/A converter 73, and
3a is applied. Therefore, the grid voltage VG applied to the grid 13a corresponds to the setting position of the setting key 61d in the letter mode, and as a result, the surface potential of the photosensitive drum 12 corresponds to the setting position.

As mentioned above, when a serviceman attempts to set (adjust) the grid voltage of the charger to an appropriate value for photo mode and letter mode, it is difficult to set (adjust) the grid voltage of the charger to an appropriate value. By varying the volume of the reference voltage generation circuit, there is no need to change or change the value output from the grid voltage generation circuit, service personnel do not have to deal with high voltage, and it can be adjusted automatically.

In addition, when the surface potential of the photoconductor drum no longer reaches the appropriate value due to changes in the environment such as temperature and humidity, the surface potential of the photoconductor drum is changed by changing the grid voltage of the charger, and the surface potential of the photoconductor drum is automatically changed. It can be returned to the appropriate value.

Furthermore, photo mode and letter mode can be further divided, and different grid voltages can be applied to each mode, and by changing the surface potential of the photoreceptor drum, copies can be made with desired image quality.

Therefore, the grid voltage can be optimized by controlling the CPU in various situations, the grid voltage can be changed continuously, the surface potential of the photoreceptor drum can be changed according to the image quality control ability, and a stable Image formation is possible.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to continuously change the grid voltage of the charging means that charges the image carrier before exposure, and to finely adjust the surface potential of the image carrier. An image forming apparatus that can be controlled can be provided.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a block diagram showing the general structure of a copying machine, FIG. 2 is a sectional view showing the internal structure, and FIG. 3 is a plan view showing the structure of the operation panel. , FIG. 4 is a circuit diagram showing the schematic configuration of the grid voltage generation circuit,
FIG. 5 is a flowchart for explaining the operation. 1... Copying machine, 12... Photosensitive drum, 60...
Operation panel, 61a...photo key '61b. 61d...Setting key 61c...Letter key 71
...Main control unit, 72...High voltage power supply, 73...D/
A converter, 74... Main motor, 75.76.
...Driver, 77...Memory, 78...A/D converter, 79...Detector, 80...Grid voltage generation circuit, 8U...Servicemankey Applicant's representative Patent attorney Takehiko Suzue

Claims (1)

[Scope of Claims] An electrostatic latent image is formed by charging an image carrier with a charging means having a grid that stabilizes discharge characteristics, and exposing the charged image carrier with light by an exposure means, In an image forming apparatus, the electrostatic latent image on the image carrier is visualized as a developer image by a developing means, and the developed developer image is transferred to an image forming medium by a transfer means. a specifying means that can continuously specify changes in the surface potential on the body; an output means that outputs data corresponding to the specification specified by the specifying means; and a voltage corresponding to the data output by the output means. An image forming apparatus comprising: a generating means for generating a voltage; and an applying means for applying a voltage generated by the generating means to the grid.