JPS59206852A - Controlling system of electrostatic stripping - Google Patents

Abstract

PURPOSE:To enable always stable and sure control of stripping without decreasing stripping performance of paper for an original having any density by controlling the voltage to be impressed on a corona charger for stripping according to the data corresponding to the density of the original. CONSTITUTION:A part of the reflected light from an original corresponding to the density thereof is made incident to a photodetecting element 29 and is converted to an electrical signal equivalent to the quantity of the incident light in an exposing process. The output signal from the detector 29 is converted to a digital signal by an A/D converter 32 is inputted to a microcomputer 31. The microcomputer 31 stores preliminarily the quantity of the reflected light when, for example, the original is white as a reference value into the ROM provided therein and calculates the ratio L(%) between said reference value and the quantity of the reflected light now detected actually. Output ports P0, P1, P2 are controlled according to the results thereof, by which the output voltage of a high voltage generating circuit 36 is variably controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to, for example, a process for transferring a toner image formed on a photoreceptor to paper in an electronic copying machine.
The present invention relates to an electrostatic peeling control method when a corona charger electrostatically peels paper that is attached to a photoreceptor from the photoreceptor.

[Technical background of the invention and its problems]

Generally, in an electronic copying machine, for example, charging, exposure, development, transfer, peeling, and fixing processes are performed. That is, the surface of the rotating photoreceptor drum is charged by a charging corona charger, the original is scanned with light by an exposure lamp, and the reflected light is guided to the photoreceptor drum for exposure, and the original is deposited on the photoreceptor drum. A static latent image corresponding to the image is formed. The electrostatic latent image formed on the photoreceptor drum is made into a visible image by applying toner with a developer, and this visible image is transferred to the paper fed from the paper feed cassette by a transfer corona charger. Transfer silently.

During this transfer, the paper comes into close contact with the photoreceptor drum, so the paper after the transfer is peeled off from the photoreceptor drum and sent to the fixing device.

By the way, as a means of peeling the paper from the photoreceptor drum in the above transfer process, there is a method of electrostatic peeling using an AC corona charger, or a mechanical peeling method using a peeling nail, a peeling tape, etc. , and even a method that combines them. The present invention relates to a method of electrostatic stripping, but in this case, conventionally the voltage applied to the corona charger was always fixed at a constant value.
A problem arose in that the toner could not be peeled off due to the thickness of the toner layer on the photoreceptor drum.

In other words, as shown in Fig. 1, which shows the relationship between the voltage applied to the stripping corona charger and the stripping performance, it is necessary to increase the applied voltage when the document has a thin a degree and there is little toner adhering to the photoreceptor drum. On the other hand, if the density of the original is high and there is a lot of toner adhesion, it is necessary to lower the value. In addition, in Fig. 1, the curve A is the blank paper copying time (reflected light number ratio L-
100%), curve B is halftone copy temporary (L=50%)
%) and curve C are the characteristics of solid black copying (L=0chi).

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide a stable and effective peeling control that does not deteriorate the paper peeling performance for originals of any density and that enables stable and effective peeling control at all times. An object of the present invention is to provide an electro-stripping control method.

[Summary of the invention]

The present invention automatically adjusts the amount of corona by the peeling corona charger by obtaining data corresponding to the cost concentration and controlling the voltage applied to the peeling corona charger according to the data. This is what I did to get it.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 schematically shows an electronic copying machine according to the present invention. That is, 1 is a main body of a copying machine, and a document table (transparent glass plate) 2 is provided on the top surface of this main body 1 to support a document. It is provided. On the lower surface side of the document table 2, there is an exposure lamp 4 that reciprocates in the direction of the arrow shown in the figure, and a mirror 5°6.7.
An exposure optical system consisting of a fixed lens block 8 and a mirror 9 is provided, and by optically scanning the document surface with these exposure optical systems, an image of the document is focused on the surface of the photoreceptor drum 10. image (slit exposure). The photosensitive drum 10 rotates in the direction of the arrow shown in the figure, and its surface is first charged by a charging corona charger 11, and then an electrostatic latent image is formed on the surface by slit exposure of the image. The latent image is made visible by applying toner to the latent image using a developer 12.

On the other hand, the paper P is taken out one by one from the selected upper paper feed cassette 13 or lower paper feed cassette I4 by the feed roller X5 or 16, and is taken out from the paper guide path 17 or 18
It is guided through the registration roller pair 19 and sent to the transfer section by the roller pair 19. The paper P sent to the transfer section comes into close contact with the surface of the photoreceptor drum 10 at the transfer corona charger 20, so that the toner image on the photoreceptor drum 10 is transferred by the action of the corona charger 20. The transferred paper P is electrostatically peeled off from the photoreceptor drum 10 by the action of the peeling AC corona charger 2I and conveyed through the paper conveyance path 22, and a heat roller serving as a fixing device is provided at the end of the sheet conveyance path 22. 23, and by passing through there, one transferred image is fixed. Then, the paper P after fixing is transferred to the main body I by a pair of paper ejection rollers 24.
It is designed to be discharged onto an outside tray 25. Also,
After the transfer, the photoreceptor drum 1O is charged with electricity by a charge-eliminating corona charger 26, residual toner on the next surface is removed by a cleaner 27, and afterimages are erased by a fluorescent lamp 28 so that it returns to its initial state. ing.

Further, a light detection element 29 is provided in the optical path between the mirrors 5 and 6 to detect a portion of the reflected light from the original.

This photodetecting element 29 is located slightly away from the optical axis so as not to affect the image formation on the photosensitive drum IO.

FIG. 3 shows a control circuit for controlling the voltage applied to the peeling corona charger 2I. That is, 31
is a microcomputer (hereinafter abbreviated as microcomputer) that controls the entire copying machine, and includes output ports Po and PL for peeling control.

It is equipped with P2. The output of the photodetecting element 29 is supplied to the microcomputer 31 via an A//D converter 32. It is still the output port P of the microcomputer 31 mentioned above. is resistance 3
3o to the base of an NPN transistor 34o, and its base is grounded via a resistor 35o. Furthermore, the output port Pl of the microcomputer 31 is connected to a resistor 33.
is connected to the base of an NPN transistor 341 via a resistor 35. grounded through. Furthermore, the output port P of the microcomputer 3I is a resistor 33□
It is connected to the base of an NPN transistor 342 via a resistor 35□, and its base is grounded via a resistor 35□. On the other hand, 36 is a high voltage generation circuit that applies an AC high voltage to the peeling corona charger 21, and an output control terminal 36. ，
36□, and these terminals 36, . There is an output control resistor 37o between 36□.

37. 372 and 373 are directly connected. and,
The resistor 37o and the terminal 36. The connection point between resistors 370 and 371 is at the emitter of transistor 34o, and the connection point between resistors 370 and 371 is at transistor 34. At the emitter of resistor 37. and 37
The connection points with □ are connected to the emitters of the transistors 342, respectively. In addition, the resistors 372 and 37. The connection points with transistors 34o, 34. ．． 34. are connected to each collector.

FIG. 4 shows the high voltage generation circuit 36 in detail.
DC power supply 41, a stabilizing circuit that is connected to this power supply 4Z and outputs a stabilized voltage, and also varies the output voltage according to the voltage applied to the output control terminal 362 (feedback from the step-up transformer 46, which will be described later). 42, this stabilization circuit 4
2, an oscillation circuit 44 consisting of an unstable multivibrator connected to the power supply 41 and operating at a predetermined frequency, and A push-pull circuit 45 consisting of a pair of transistors that are mutually turned on and off depending on the output, a primary coil 46I connected to the output of the stabilizing circuit 42 via this push-pull circuit 45, and a stripping corona charger 2I. A step-up transformer 46 has a high-voltage secondary coil 462 connected to the feedback secondary coil 463, and the output voltage of the feedback secondary coil 468 of the transformer 46 is rectified. It is constituted by a rectifier circuit 47 that outputs to.

Next, the operation of the above configuration will be explained with reference to the flowchart shown in FIG.

Now, when the copy key (not shown) is turned on, the microcomputer 3
1 starts the copying operation and performs the banding, exposure, and
The processes of transfer, peeling, and fixing are executed sequentially, but in the exposure process, a portion of the reflected light from the original in accordance with the density enters the photodetector element 29, and the amount of incident light (that is, the original is converted into an electrical signal according to the a degree). The output signal of the photodetecting element 29 is converted into a digital value by an A//D converter 32 and inputted to a microcomputer 31 . The microcomputer 31 stores in advance in the internal FtOM the reflection light meter measured when the document is blank, for example, as a reference value, and uses that reference value and the reflected light 11 (A/
The ratio L (%) to the output value of the D converter 32 is calculated.

Then, it is compared and determined which of the conditions shown in the table below is satisfied by the obtained photometer ratio, and the output is determined according to the result. , pm, and p2.

That is, for example, if the light amount ratio is [O≦L('25), the output capo-)P. Transistor 3 with 11 lebel
Turn on 4o. When transistor 34° turns on,
Since both ends of the series circuit of the resistor J 7 oT J 7 H+372 are short-circuited, the output control terminal 36. ．． Only the resistor 373 is connected between the resistors 362 and 362. Then,
The amount of feedback from the step-up transformer 46 to the stabilizing circuit 42 increases, and the stabilizing circuit 42 operates to lower the output voltage by the increased amount.

As a result, the output voltage of the high voltage secondary coil 462 of the step-up transformer 46 is set to, for example, 4.3 kilovolts (KV). Similarly, the output voltage increases by 0.2 kilovolts each time the light intensity ratio increases by 25 inches.

In this way, the amount of light reflected from the original (that is, the density of the original)
is detected by the photodetection element 29 and inputted to the microcomputer 31, and the microcomputer 31 variably controls the output voltage of the high voltage generation circuit 36 according to the detected amount of light. If the amount of corona acid is high, the voltage applied to the corona charger 21 is lowered, and if the density of the document is low and there is little toner adhesion, the voltage applied is increased to automatically adjust the amount of corona acid. Therefore, there is no deterioration in paper peeling performance for documents of any density, from white paper to solid black, and stable and reliable peeling control is always possible.

In the above embodiment, a case has been described in which data corresponding to the density of the original is obtained by detecting the time when light is reflected from the original, but the present invention is not limited to this. Data corresponding to the density of the document may be obtained by detecting the amount of adhesion. In this case, as shown in FIG. 6, for example, a detector 30 consisting of a light source that irradiates light onto the surface of the photoreceptor drum 10 and a light receiving element that receives the reflected light is provided after the developing device 12, and the output signal thereof is may be input to the microcomputer 31 via the A/D converter 32.

Further, data corresponding to the density of the document may be obtained by detecting a developing current corresponding to the amount of toner adhering to the photoreceptor drum.

In this case, for example, as shown in FIG. 7, there is a developing chamber between the developing roller 12a of the developing device 12 and the output terminal of the developing bias voltage generating circuit 51 that applies the developing bias voltage to the developing roller 12th. Connect the resistor 52 for
The voltage across the terminals of the resistor 52 is input to the microcomputer 31 via the A/D converter 32. That is, the photosensitive drum 10
When developing the upper electrostatic latent image, if the potential on the photosensitive drum 10 is higher than the developing device 12, a developing current 1 flows from the photosensitive drum 12 side to the developing device 12 side. The amount of current at this time is approximately proportional to the amount of toner deposited on the photoreceptor drum 1o. Therefore, by detecting the voltage change between the terminals of the resistor 52 and inputting it manually to the microcomputer 3I via the A/D converter 32, the same control as in the previous embodiment is possible. In this case, the standard value stored in the ROM of the microcomputer 3I in advance is, for example, the voltage between the terminals of the resistor 52 when the original is solid black, and the voltage between the terminals of the resistor 52 that is actually detected is the same as the standard value. Calculate the ratio v@). Then, it is compared and determined which of the conditions shown in the table below is satisfied by the obtained voltage ratio V, and the output is determined according to the result. +P1yP2 is controlled. Incidentally, an operational flowchart in this embodiment is shown in FIG.

In addition, although the said Example demonstrated the case where an AC corona charger was used as a corona charger for peeling, it is not limited to this and can be similarly applied to the case where a DC corona charger is used.

Further, in the above embodiment, a case has been described in which the present invention is applied to paper peeling control in an electronic copying machine, but the present invention is not limited to this, and can also be applied to paper peeling control in a facsimile machine, for example.

〔Effect of the invention〕

As detailed above, according to the present invention, by obtaining data corresponding to the density of the original and controlling the voltage applied to the peeling corona charger according to the data, it is possible to obtain data corresponding to the density of the original. Therefore, it is possible to provide an electrostatic peeling control method that does not deteriorate paper peeling performance even when the paper is peeled off, and allows stable and reliable peeling control at all times.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the relationship between the voltage applied to the peeling corona charger and peeling performance when peeling paper from the photoreceptor, and Figures 2 to 5 are for explaining an embodiment of the present invention. Fig. 2 is a side view showing the schematic configuration of the electronic copying machine, Fig. 3 is a configuration diagram of the control@1 circuit, and Fig. 4 is a circuit diagram showing details of the high voltage generation circuit in Fig. 3. FIG. 5 is a flowchart for explaining the operation, FIG. 6 is a diagram for explaining the toner adhesion amount detection means in another embodiment of the invention, and FIG. 7 is a diagram for explaining the toner adhesion amount detection means in another embodiment of the invention. current i
#A diagram for explaining the current detection means, FIG. 8 is a flowchart for explaining the operation of the embodiment of FIG. 7. 2... Original table, 4... Exposure lamp, 10... Photosensitive main drum, 11... Charging corona charger, 121
5-...Current 1'a device, 20...Corona charger for transfer, 21...Corona charger for peeling, 23...Heat roller, 29...Photodetection element, P...Paper, 31
...Microcomputer, 32...A/D converter, 33°~3
3! ...Transistor, 36...High voltage generation circuit,
370 to 373... Resistor for output control, 30... Toner adhesion amount detector, I2 property... Developing roller, 51...
Development via voltage generation circuit, 52...Resistor for development current detection. Applicant's agent Patent attorney Takehiko Suzue 16- No. 1 Figure 59 Sword O Turtle 1 Ko (Ni V) 7th cause 10

Claims (4)

[Claims] (1) By irradiating a document with light and guiding the light from the document to a photoconductor, an electrostatic latent image is formed on the photoconductor, and toner is applied to this electrostatic latent image using a developing device. , the OT visual mound is electrostatically transferred to paper, and the paper that is in close contact with the photoreceptor at the time of transfer is electrostatically removed from the photoreceptor by a corona charger,
Electrostatic peeling characterized by comprising: a detection means for obtaining data corresponding to the density of the original; and a side tilting means for controlling the ball pressure applied to the corona charger according to the output of the detection means. control method. (2) The electrostatic @chick control method according to claim 1, wherein the data obtained by the detection means is the amount of light from the document according to its density. (3) The data obtained by the detection means is the toner adhesion edge on the photoreceptor.
Electrostatic peeling control method described. (4) The electrostatic peeling control method according to claim 1, wherein the data obtained by the detection means is a developing current of a developing device corresponding to a toner adhesion number on the photoreceptor.