JPS624712B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying machine that repeatedly uses the same photoreceptor, and more particularly to a photoreceptor fatigue correction device.

In general, the characteristics of a photoreceptor in a transfer-type electrophotographic copying machine (hereinafter simply referred to as a copying machine) change as the number of times it is used increases due to the effects of exposure, charging, and neutralization. This phenomenon is called fatigue of the photoconductor, and when characteristics change, that is, fatigue occurs, the potential of the photoconductor part corresponding to the background part of the image increases, and the background part is also developed, causing background stains, and charging due to charging. In some cases, the potential becomes lower and the copy density decreases.

In this way, fatigue of the photoreceptor is related to the number of repetitions of the copying cycle, that is, the total number of copies, so it is possible to correct the fatigue by controlling the developing bias voltage, etc. according to the total number of copies, and prevent deterioration in the quality of copied images. However, because the exposure time varies depending on the document size during copying, and the charging state changes depending on the ambient temperature and humidity, the degree of fatigue progress differs each time, so simply controlling based on the number of copies does not provide sufficient compensation. I can't wait.

For this reason, it is conceivable to detect various data such as exposure, charging, static elimination, temperature and humidity during copying, and correct the fatigue of the photoreceptor according to the cumulative value of these detected data. For example, as shown in FIG. 1, a document size detection device 1, an exposure amount detection device 2, a charge amount detection device 3, a temperature/humidity detection device 4, a copy number detection device 5, etc. are provided to detect the amount of exposure that causes fatigue. Detects the amount of charge, temperature and humidity, number of copies, etc. each time a copy is made,
The detected data is sent to the storage device 6, cumulatively added, and stored. The control signal generating device 7 determines the degree of fatigue at that point by integrating the contents stored in the storage device 6, and generates a control signal based on correction data set in advance in comparison with the degree of fatigue, and controls the exposure. This is intended to correct fatigue of the photoreceptor by controlling the control circuit 8, the charging voltage control circuit 9, the developing bias voltage control circuit 10, etc.

However, since copying machines are used intermittently, the fatigue of the photoreceptor recovers to a certain extent during the period when the photoreceptor is not in use.However, since the conventional method of making corrections ignores this stoppage time, it becomes over-compensated and the photoreceptor is not accurately corrected. I was unable to compensate for my fatigue.

The present invention has been made in view of the above points, and the electrophotographic copying machine according to the present invention includes a fatigue information detection device that detects information that causes fatigue of the photoreceptor during copying, and a fatigue information detection device that detects information that causes fatigue of the photoreceptor during copying. a storage device that cumulatively stores information about the copying process; a stop time detection device that detects the copy stop time when the copy machine starts to be used; and a fatigue recovery coefficient that is set in comparison with the copy stop time detected by the device. Therefore, a correction device that subtracts and corrects the storage contents accumulated in the storage device, a control signal generation device that generates a control signal based on the storage contents modified by the device, and a control signal generating device that generates a control signal based on the storage contents modified by the device. The present invention is characterized in that a photoconductor fatigue correction device is provided, which includes a control device that controls at least one of charging conditions, exposure conditions, and development bias voltage of the photoconductor.

According to the electrophotographic copying machine configured in this way,
The memory content, which is cumulative storage of information that causes fatigue of the photoreceptor during copying, is subtracted and corrected by the fatigue recovery coefficient for the copying stop time, and the charging conditions, exposure conditions, or development of the photoreceptor are adjusted based on the corrected memory content. Since at least one of the bias voltages is controlled, it is possible to always accurately correct fatigue of the photoreceptor and obtain good copy image quality without overcorrecting.

The present invention will be explained below with reference to FIGS. 2 to 5. FIG. 2 is a block diagram showing an embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals. Reference numeral 11 denotes a stop time detection device that detects the time when the copying machine is turned off and stopped in use.

A document size detection device 1, an exposure amount detection device 2, and a charge amount detection device 3, which are fatigue information detection devices for detecting information that causes fatigue of the photoreceptor during copying.
Detection information is sent from the temperature/humidity detection device 4 and copy number detection device 5 to the storage device 6, respectively. In the storage device 6, the number of sheets for each size or the number of sheets converted to a specific size based on the area ratio of the original or copy sheet is accumulated and stored in the storage device 6 based on the size information and the number of sheets, and the amount of exposure is also calculated based on the area. Since it is proportional, the cumulative exposure amount is stored by calculating the exposure amount based on the exposure amount information based on the lamp voltage, irradiation intensity, etc., and the size information and adding it. The charge amount information is detected by extracting a part of the voltage or current of a charging charger, a static elimination charger, etc., and the cumulative charge amount is stored by multiplying the voltage or current by a coefficient depending on the charging time and adding the result. The temperature and humidity information detected by the temperature sensor or humidity sensor is updated in the memory each time, and is used as information on the progress of fatigue of the photoreceptor due to temperature and humidity, or information on fatigue correction, or when it exceeds a set value. The number of times is accumulated and stored as comprehensive fatigue information.

The stop time detection device 11 is designed to enable detection without using a power source in the event of a power outage.The stop time detection device 11 is designed to detect power outages without using a power source. Detect copy stop time when starting to use.

The correction device 12 subtracts and corrects the storage contents that cause fatigue in the storage device 6 using the fatigue recovery coefficient set in comparison with the copy stop time detected by the stop time detection device 11. As described above, the control signal generating device 7 generates a control signal based on the modified storage contents, and the control signal is generated by the exposure control circuit 8, the charging voltage control circuit 9, and the developing bias voltage control circuit 10, which are control devices. , exposure conditions, charging conditions, and development bias voltage to correct fatigue of the photoreceptor. Therefore, not only fatigue correction is made based on usage conditions such as charge amount and exposure amount, and number of uses, but also correction is made based on fatigue recovery during the stop time, so that fatigue of the photoreceptor can be accurately corrected.

FIG. 3 shows this invention in which a microcomputer is used to control each of the detection devices 1 to 11 in FIG. 2, process various information, judge, calculate, etc., and generate a control signal for fatigue correction. This is an example of the following. Components that are the same as those in FIG. 2 are given the same reference numerals, and their description will be omitted.

A block portion 20 surrounded by a two-dot chain line corresponds to a central processing unit (hereinafter referred to as CPU) 21, a fixed storage device (hereinafter referred to as ROM) 22 in which a control program is set, and the storage device 6 in FIG. non-volatile constant-speed recall storage (hereinafter referred to as
(abbreviated as RAM) 23, etc., and for convenience of explanation, input ports 24 to 29 that are connected to each detection device 1 to 5 and 11 to input their information, an exposure control circuit 8, and a charging voltage control circuit. Circuit 9 and developing bias voltage control circuit 1
0 are provided with output ports 30-32 for transmitting control signals. In addition, CPU21 and ROM22,
The RAM 23 and each input/output port 24 to 32 are connected to each other by an address bus 33, a data 34, and a control bus (not shown).

The CPU 21 operates according to a program set in the ROM 22 during copying. By the detection information of the document size detection device 1 input from the input port 24 at the start of exposure, the document sizes A3, A4, B are detected.
4, B5 is determined and RAM is determined based on the determination result.
The data is cumulatively added to each of the 23 size storage addresses. If necessary, the cumulative exposure amount may be stored at the same address in the RAM 23 together with the detection information of the exposure amount detector 2 inputted from the input port 25. Next, upon the start of charging, the detection information of the charge amount detection device 3 inputted from the input port 26 is checked, for example, the charging time, and the address for storing the charge amount in the RAM 23 is set with a constant of +2 for the longer charging time and +1 for the shorter charging time. Add to and accumulate. The temperature and humidity detection device 4 also compares the output of the temperature sensor or humidity sensor with a set value, converts it into a "1" or "0" signal, and inputs it to the input port 27, which is used to store the temperature and humidity in the RAM 23. Add each to the address.

Copy counter data is input from the sheet number detection device 5 to the input port 28, and is added to the address for storing the number of sheets in the RAM 23. Further, when the use of the copying machine is stopped, when the use of the copying machine is started again, the stop time detection information is inputted from the stop time detection device 11 to the input port 29, and the information is set in advance in the ROM 22 in accordance with this. Each memory content of the RAM 23 is subtracted and corrected based on the fatigue recovery coefficient. In this way, all information such as exposure amount, charge amount, number of copies, etc., which are factors that cause fatigue of the photoreceptor, are stored in the RAM 23 as cumulative values, and the cumulative values are each corrected depending on the stop time.

Next, the CPU 21 also operates as the control signal generator 7 in FIG.
The memory contents stored in RAM23 are collectively stored in ROM
22 to determine the fatigue of the photoreceptor,
A control signal for performing fatigue correction corresponding to this is issued to the output ports 30 to 32, and is transmitted to the exposure control circuit 8, charging voltage control circuit 9, or development bias voltage control circuit 10 to determine the exposure conditions, charging conditions, or development bias voltage. At least one of these is controlled to correct fatigue of the photoreceptor.

FIG. 4 is a circuit diagram showing an example of the stop time detection device 11 that utilizes a voltage drop due to discharge of a storage battery, and the same parts as in FIG. 3 are given the same reference numerals and their explanation will be omitted. . 35 is a transformer connected to the power supply of the copying machine, 36 is a rectifier connected to the secondary side of the transformer 35 and converts AC voltage into DC voltage, and 39 is a resistor 3 connected to the DC output of the rectifier 36.
7 and a storage battery that is charged via a charging controller 38 and discharged with a substantially constant discharge current by a resistor 40 connected in parallel; 41 is an A/D converter that converts the terminal voltage of the storage battery 39 into a digital signal; be.

When the power is turned on to use the copying machine, AC voltage is supplied to the primary side of the transformer 35, and the AC voltage induced on the secondary side is rectified by the rectifier 36 and converted to DC voltage. 37, the storage battery 39 is charged. This charging continues while the copying machine is in use, and the terminal voltage of the storage battery 39 is kept constant. However, when the power to the copying machine is cut off, current does not flow in the reverse direction to the rectifier 36, so the storage battery 39 has a resistance. A substantially constant current is discharged through 40, and the terminal voltage thereof gradually drops. Figure 5 shows the discharge characteristics of a nickel cadmium storage battery.
B shows the relationship between discharge time and terminal voltage in the case of 300mA. For example, when discharging at a discharge current of 150 mA for about 10 hours, the terminal voltage decreases by about 0.1 V from 1.34 V in the charged state. Therefore, by using such a storage battery as the storage battery 39 in FIG. 4 and detecting its terminal voltage at the time of starting use, it is possible to detect the time when use is stopped.

The signal converted into a digital signal by the A/D converter 41 is input to the input port 29 of the microcomputer 20. When the copying machine is restarted, the CPU 21 compares the digital signal from the input port 29 with the voltage value corresponding to the discharge time preset in the ROM 22 to determine the discharge time, that is, the stop time, and determines the exposure amount in the RAM 23 accordingly. , the cumulative values of the amount of charge, temperature and humidity, number of copies, etc. are corrected by subtraction. During this detection by the CPU 21, the charge controller 38 temporarily stops charging the storage battery 39. Of course, by selecting the resistance value R of the resistor 40 and changing the discharge current, it is possible to freely set the maximum detectable time, and since the battery voltage E at the initial stage of discharge is constant, it can be detected for a long time and with high accuracy. It is possible to detect outage time.

As explained above, according to the present invention, by detecting the copying stop time which is a factor for recovery from photoreceptor fatigue, and correcting by subtracting the accumulated storage content of information which is a factor for fatigue, the photoreceptor is accurately The effect is great because fatigue correction is performed and good copy image quality can always be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional example of a photoreceptor fatigue correction device, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing an embodiment using a microcomputer of the present invention. FIG. 4 is a circuit diagram showing an example of the stop time detection device in the embodiment shown in FIGS. 2 and 3;
FIG. 5 is a curve diagram showing the discharge characteristics of a nickel cadmium storage battery. DESCRIPTION OF SYMBOLS 1... Original size detection device, 2... Exposure amount detection device, 3... Charge amount detection device, 4... Temperature/humidity detection device, 5... Copy number detection device, 6... Storage device, 7... Control Signal generator, 8... Exposure control circuit, 9... Charging voltage control circuit, 10... Development bias voltage control circuit, 11... Stop time detection device,
12... Correction device, 20... Microcomputer, 21... Central processing unit (CPU), 22... Fixed memory (ROM), 23... Constant speed access memory (RAM), 24 to 29... Input port, 30
to 32...output port, 39...storage battery.

Claims (1)

[Claims] 1. In an electrophotographic copying machine that uses the same photoreceptor repeatedly, a fatigue information detection device that detects information that causes fatigue of the photoreceptor during copying, and a storage device that cumulatively stores information detected by the device. , a stop time detection device that detects a copy stop time when the copying machine starts to be used, and a fatigue recovery coefficient that is set in comparison with the copy stop time detected by the device, and cumulatively stored in the storage device. a control signal generating device that generates a control signal based on the memory content corrected by the device; and a control signal generating device that generates a control signal based on the memory content corrected by the device; or a control device for controlling at least one of the developing bias voltages.