JPS60220371A - Control method of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To shorten the down time of a machine to improve the operability by making a developing device, whose toner end is detected by a toner end detecting means, unoperated and using another developing device to perform the copying operation. CONSTITUTION:A primary electrifier 8, a secondary electrifier 9, an exposure device 10, an erasing device 11, a developing device 12, a cleaning device, and a dielectric belt unit 13 are arranged around the first photosensitive drum 6. An electrostatic latent image of only a red picture part is formed and is developed with a red developer of the developing device 12 and is transferred to a transfer paper, which is carried by the dielectric belt 13, by a transfer charger 14. Meanwhile, an electrostatic charging device 16, an exposure device 17, an erasing device 18, a developing device 19, a transfer charger 20, a separating charger 21, and a cleaning device 22 are arranged around the second photosensitive drum 7. An electrostatic latent image of only a black picture part is formed and is developed with a black developer of the developing device 19 and is transferred to the transfer paper, which is carried by the dielectric belt 13, by the transfer charger 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method of controlling a color copying machine when toner runs out.

(Prior Art) Conventionally, in a copying machine having a plurality of developing devices, such as a two-color copying machine, when one of the developing devices reaches a toner end state, the subsequent copying operation is usually prohibited. , the copy operation is allowed to resume only after toner is replenished. For example, when the red developing device runs out of toner, the copying operation is prohibited even though it is possible to perform a copying operation using only the black developing device. In this way, in the conventional case, when you do not have replenishment toner on hand and you need to make an urgent copy,
There was a problem that the machine could not be used at all.

(Purpose) The present invention has been made in view of the drawbacks of the conventional examples, and an object of the present invention is to provide a control method for an electronic copying machine that can reduce downtime of the machine. be.

(Structure) The structure of the present invention will be described below based on illustrated embodiments. FIG. 1 is a schematic diagram of an electrophotographic copying machine according to the present invention.

The original placed on the original table is exposed by an exposure lamp, and the light image passes through the lens J and reaches the half mirror 2. The light beam is transmitted to the first photoreceptor drum 6 by the half mirror 2.
The light beam is divided into a first light beam directed toward the photoreceptor drum 7 and a second light beam directed toward the second photoreceptor drum 7. The first light beam transmitted by the half mirror 2 passes through the mirror 5 and is focused on the first photoreceptor drum 6, for example, a red photoreceptor drum. On the other hand, the second light beam reflected by the half mirror 2 forms an image on the second photoreceptor drum 7, for example, a black photoreceptor drum, by the mirrors 3 and 4 at i. Each mirror is arranged so that the optical path lengths of the first beam and the second beam are substantially the same.

Around the first photoreceptor drum 6, there are a primary charger 8, a secondary charger 9, an exposure device 10, an erase device 11, and a development device 1.
2. A cleaning device 15 and a dielectric belt unit 13 are arranged, and utilize the difference in spectral sensitivity of the photoconductive layer of the photoreceptor drum to form an electrostatic latent image of only a red image. The image is visualized by the transfer charger 14 and transferred to a transfer paper conveyed by the dielectric belt 13. After the transfer, the photosensitive drum is cleaned by the cleaning device 15 in preparation for the next copying operation.

On the other hand, a charging device i16 is provided around the second photoreceptor drum 7.
, exposure device 17. An erase device 18, a developing device @ 19, a transfer charger 20, a separation charger 21, and a cleaning device 22 are arranged to form an electrostatic latent image of only a black image. The transfer charger 20 transfers the image onto the transfer paper conveyed by the body belt 13 (although two colors, black and red, have been described, the present invention is not limited to these two colors).

As mentioned above, the system of this example is a two-color copying machine consisting of a first photoreceptor drum (Se-OPC composite photoreceptor) and a second photoreceptor (Se photoreceptor). These include an all-black mode that copies the original in black and white and reproduces it like a conventional copier, a red-black mode that reproduces the original by making two-color copies of red and black, an all-red mode that reproduces the original as an all-red copy, and an all-black mode that reproduces the original as a black and white copy. A total of five modes are available: a red erase mode that erases the red information in the document, and a black erase mode that erases the black color information in the document. Also, this system.

In the case of the first all-black mode, the first photosensitive drum 6 and the surrounding process elements are put in a non-operating state 1, and the sheet is transported along a completely different route. The main reason for doing this is that the first photoreceptor drum 6 and the second
This is the difference in sensitivity of the photoreceptor drum 7, and the second photoreceptor drum 7
This is so as not to impair the amount of copies produced in all-black mode, which can be achieved by using only the black mode. This means that there are at least two process speeds in all black mode and other modes. In the system according to this embodiment, the process speed (also referred to as photosensitive drum circumferential speed) at high speed in full black mode is approximately 180 wn/see, and the process speed at other low speeds in red mode is approximately 90 pages/see.

Next, the transport path of the transfer paper will be explained.

First, in all copy modes, copy paper is stored in the main paper feed cassette 45 (
Or from the unfeed paper cassette 46) to the overprint paper roller 47. Upper separate roller 48. Upper reverse roller 49. (In the case of non-feeding, the paper is sent out from the non-feeding roller 58°, the lower separate roller 59, and the downward bar roller 60), and the relay roller pair 5
Reach 3. At this time, the switching claw 50 is positioned below (indicated by a broken line) and guides the copy paper (transfer paper). After that, the leading edge of the copy paper is detected by the paper detection sensor 54, further passes through the relay roller pair 55, the leading edge of the copy paper is detected by the paper detection sensor 57 before registration, and then reaches the lower registration roller pair 56. In the case of C unfeeding, the leading edge of the copy paper reaches the relay roller pair 61 and is detected by the paper detection sensor 62 (hereinafter the same as upper paper feeding). Here, the one-sheet detection sensor 54, 57, 62 is configured to detect the behavior of the sheet at a predetermined sheet feeding timing and feed back a signal to the control system. Also, unfeeding roller 4
7 (unfeeding roller 58) detects the paper position by the paper detection sensor 57, and then stops after a predetermined time required to reach the lower pair of registration rollers 56.

The timing is determined so that the operations of the paper feeding system and the developed image on the second photosensitive drum 7 are synchronized at the leading edge of the paper, and the lower registration roller pair 56 is operated to transfer the developed image on the drum to the paper. .

In other modes, copy paper is 11 = paper cassette 4.
5, the paper is sent out from the unfeed roller 47, the false separation roller 48, and the upper reverse roller 49, and arrives at the upper registration roller pair 51. At this time, the paper detection sensor 52 detects the leading edge of the paper, and after the detection, the upper paper feeding roller 47 stops after a predetermined time required for the paper to reach the upper registration roller pair 51. At this time, the switching claw 50 is positioned upward (indicated by a solid line) and guides the copy paper.

After a predetermined amount of paper feeding is completed, timing is determined so that the developed image on the first photosensitive drum 6 and the paper are synchronized, and the resist roller pair 51 is operated to transfer the developed image on the drum to the paper. Thereafter, the transfer paper conveyed by the dielectric belt 13 is transferred to the second
It reaches the photosensitive drum 7, and a predetermined developed image is transferred thereto.

FIG. 2 is a cross-sectional view of the developing device, showing the first photoreceptor 6, the second
The photoreceptor 7 also has a similar developing device. Developing device 1
2 or 19 are a developing roller 70, a paddle wheel 72 which is a developer pumping member that also serves as stirring, and a doctor member 7.
3, a toner replenishing member 76, and a developer concentration sensor 75.

The configuration of the developer concentration sensor 75 is shown in FIG.

This is mylar 758. Sensor 75b, holder 75c
Consisting of This developer concentration sensor detects a change in the magnetic permeability of the developer due to a change in the developer concentration as a change in the inductance of a coil.

FIG. 4 shows an embodiment of the developer concentration detection circuit.

Part A is an unstable multivibrator circuit with resistor R25.
, R26 and capacitor C7. The B part and the 0 part are a detection oscillation circuit and a reference oscillation circuit, respectively, and the detection oscillation and the reference oscillation are caused to be performed at the alternating voltage by the output of the unstable multivibrator. A coil Ls in section B is a density detection sensor provided in the developing device. The detection oscillation frequency fr and the reference oscillation frequency IO are ! = 1/2π τ1 , f = I/2π τ1 −ε:. Part D is a resonant circuit using transistors as a differential amplifier, and the resonant frequency is f=1/2.
πJ mouth? ] When the output of the circuit has a frequency above the resonance point, the amplitude 11 decreases, and the higher the frequency, the smaller the amplitude 111. Therefore, changes in frequency are output as changes in voltage. The E section performs AM detection on the voltage change obtained in the previous stage resonant circuit and extracts it as a low frequency. The F section is a DC amplification circuit that increases only the difference between the detected oscillation frequency and the reference oscillation frequency of the low-frequency signal obtained by detection.
They are integrated together and extracted as a complete DC. Section G is a comparator circuit, and the frequency difference between the detection and the reference is made into a DC voltage difference in the amplification circuit 111, and this comparator circuit outputs a toner replenishment signal. When the output of the DC amplifier 11 circuit that enters one terminal of the operational amplifier Ic6 becomes lower than the voltage of the + terminal, the output terminal of the operational amplifier Ic6 becomes HIGH. The output of the operational amplifier Ic6 is sent to the main body control section, and also drives the transistor Q2 to light up the light emitting diodes L and E D1 for toner replenishment indication, and turns on the electromagnetic clutch CL for driving the toner replenishment roller to turn on the toner. replenish into the developing device.

On the other hand, although the main body control section 1 is not shown, it includes CP and U.

Consists of ROM, RAM, I10 interface, etc.
The toner replenishment signal sent from the developer concentration detection circuit is monitored, and if the toner supplementary signal is detected for 10 consecutive seconds, it is determined that the toner has run out, and a message to that effect is displayed. This is the same for both the red image device and the black image device. FIG. 5 is a flowchart showing the above operation.

Next, depending on the 1-ner end status of the red image device and black image device, if both are at the toner end, copying is not possible for all modes, and when only the door side is at the 1-ner end, all black mode and red The erasing mode allows copying, and when only the black side is 1-naen 1-, the all-red mode and black erasing mode are controlled so that copying is possible. FIG. 6 is a flowchart showing the above operation. By controlling in this manner, even if one of the developing devices reaches the toner end and becomes unusable, the copying mode that can be achieved using the other developing device is still enabled, reducing machine downtime. This can improve operability.

In the example, a two-color copying machine using two photoreceptor drums was explained, but it can also be implemented for a two-color or multicolor copying machine in which a plurality of developing devices are arranged around one photoreceptor drum. It is.

(Effects) As described above, according to the control method according to the present invention, downtime of the machine can be reduced and operability can be improved.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the internal machine MII of a copying machine according to the present invention, Fig. 2 is an enlarged configuration diagram of the developing section, Fig. 3 is an exploded perspective view of the concentration sensor, and Fig. 4 is a developer concentration detection device. The circuit diagram of the embodiment, FIGS. 5 and 6, are flowcharts showing the operation of the control method according to the present invention.

Claims (1)

[Claims] A copying machine having a plurality of developing devices is characterized in that a toner end detection means in each developing device deactivates the developing device that detects toner end, and enables copying operations using other developing devices. A method for controlling electronic copying.