JPS58132247A - Copying device - Google Patents

Abstract

PURPOSE:To obtain stable copies of high quality having less influences occuring in secular changes and environmental changes by measuring the surface potential of a photoreceptor corresponding to the bright and dark parts of an original upon each lapse of a specified time, and controlling the outputs of required electric power sources automatically. CONSTITUTION:When the output upon each lapse of a specified time by a calendar clock IC 84 backed up by a battery 83 is applied to a microcomputer 41, the measured value of the surface potential of a photoreceptor corresponding to the bright and dark parts of an original by a surface electrometer 87 is updated and written into an RAM 82 through an A/D converter 86, etc. by the interruption processing by the microcomputer. In accordance with said value, a high voltage electric power source for electrostatic charging of the photoreceptor and an electric power source for biasing for development are controlled with the computer 41, and the power source outputs thereof are automatically controlled, whereby the image densities are regulated. As a result, the stable copying of high quality with less influences occuring in secular changes and environmental changes is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying apparatus, and more particularly to a copying apparatus that measures the surface potential of a photoreceptor and controls the amount of charge, developing bias voltage, etc. based on the measurement results.

In a copying machine, the image quality of a copy is determined by +HC charging,
It depends on the surface potential of the photoconductor, where a latent image corresponding to the original image is formed in the exposure process, and the developing bias voltage applied to the developing roller in the developing process, and by keeping these at appropriate values, copies with good image quality can be achieved. can be obtained.

Conventionally, copying machines use a constant voltage/constant current circuit in the high voltage power supply for charging to keep the output constant.
Furthermore, the output of the developing bias power source is fixed or can be set manually to maintain the amount of charge and the phenomenon bias voltage at appropriate values.

However, as the photoreceptor deteriorates over time, its residual potential increases, and the surface potential changes depending on the ambient temperature and humidity. However, due to aging and changes in ambient temperature and humidity, problems such as the image density of copies becoming inappropriate and the background becoming smudged occur.

Therefore, when copying all originals with dirty backgrounds or poor originals with small density differences between image and non-image areas,
There was also the inconvenience of having to manually adjust the density by making several trial runs while looking at the copy.

This invention has been made in view of the above points, and the copying machine is designed to prevent damage caused by changes over time, ambient temperature, and humidity.
The purpose is to reduce the influence on images and to stably obtain high-quality copies.

Therefore, the copying apparatus according to the present invention periodically measures the surface potential of the photoreceptor corresponding to the bright and dark areas of the original, and automatically controls the charging high-voltage power supply and the developing bias power supply based on the measurement results. The output is adjusted and controlled.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a copying apparatus of a static exposure type using a belt-shaped photoreceptor according to the present invention.

In the figure, a halogen lamp for exposure 1. Exposure fiber laser using a condensing light transmitter 2. Double type scorotron charger for charging 6, high voltage power supply for charging 4. A linear optical sensor 5 for detecting document turns is integrally mounted on the carrier sensor 6.

Then, when a print key (not shown) is pressed, the halogen lamp 1 is turned on, a high voltage of approximately 5.6 K VO is applied by the scorotron charger 3, and the carriage 6 is scanned by the scanning device 7 as shown by arrow A. 2 with two segments.
A belt photoreceptor 8 made of an organic optical semiconductor (OPC) capable of forming electrostatic latent images is charged and exposed.

This exposure is slit exposure, and the light reflected by the original 10 on the contact glass 9 from the laser beam 1 passes through the fiber lens 2 to the charged belt photoreceptor 8.
The electrostatic latent image corresponding to the image on the original document 10 is formed on the belt photoreceptor 8.

At the same time, the linear optical sensor 5 scans the original 10 and detects its A' turn.

When charging and exposure are completed, the application of high voltage to the scorotron charger 3 is stopped, the halogen lamp 1 is turned off, and the carriage 6 returns to the home position at twice the speed of the forward movement. Return with .

On the other hand, the belt photoreceptor 8 rotates in the direction of arrow B, and first, the eraser/blade 12 erases charges unnecessary for copying according to the size of the original 10 or the transfer paper.

Thereby, toner is prevented from adhering to unnecessary areas of the belt photoreceptor 8, and fatigue of the belt photoreceptor 8 is kept at a constant level.

Thereafter, toner 14 is applied by the developing roller 13, and the electrostatic latent image on the belt photoreceptor 8 is visualized.

On the other hand, the upper paper feed cassette 15 or the lower paper feed cassette 16
The transfer paper inside is fed by the paper feed roller 17 or 18,
The registration roller 19 contacts the belt photoreceptor 8 at precise timing, and the toner image on the belt photoreceptor 8 is transferred to the transfer paper.

At this time, a high voltage of approximately 6 KV is applied to the transfer charger 20 at precise timing to attract the toner image on the belt photoreceptor 8 toward the transfer paper, and a high voltage of approximately 5 KV is applied to the separation charger 21. This acts to remove static electricity from the transfer paper so that the transfer paper can be easily separated from the belt photoreceptor 8.

Then, the toner image is flash-fixed on the transfer paper separated at the corner of the belt photoreceptor 8 (separated by curvature) by emitting light from the xenon lamp 23 of the fixing device 22 several times.

Thereafter, the transfer paper is stocked in a double-sided buffer tray 25 by a guide plate 24 when the front side copy of double-sided copying is completed, and is stocked in a discharge paper stocker 26 by the guide plate 24 when one side copying is finished or the back side copy of double-sided copying is completed.

Further, the segments of the belt photoreceptor 8 on which one transfer separation has been completed have their residual charges erased by light irradiation from the static eliminating lamp 27, and residual toner is removed by the cleaner Farbrar/28, in preparation for the next copying process.

Furthermore, when a predetermined number of copy cycles have been executed, the in-slump 12. The static elimination lamp 27 is fully lit, and a high voltage is applied to the separation charger 21.
A cycle is performed in which the belt photoreceptor 8 is rotated several times to remove residual charges and image memory on the belt photoreceptor 8 and to clean its surface.

The top of this copying apparatus is opened as shown by the phantom line to allow the user to replace the belt photoreceptor 8 which has become a magazine.

Further, in the figure, 30 is a fan motor, 31 is a paper feed roller for the double-sided buffer tray 25, 32 is a drive motor, and 33 is an electrical unit.

FIGS. 2 and 3 are block circuit diagrams of the control section of this copying apparatus.

In these figures, this copying apparatus has two microcomputers (hereinafter abbreviated as "microcomputers") 41 and 42.
controlled by

The microcomputer 41H is a master microcomputer, and is in charge of sequence control of the a-photography process, output control of various high-voltage power supplies and current bias power supplies, dimming control, time measurement, audio notification, and other controls.

The microcomputer 42U is a slave microcomputer, and controls display control, manual key control, voice recognition control, and drive control of a pulse motor for registration (paper feed, paper feeding section) control.

These microcomputers 41 and 42 are each 8-bit one-chip microcomputers, including a CPU (central processing unit), 4 bytes of program memo! J (RO
M), 128 bytes of data memory (RAM), three 8-bit parallel I10 ports (H)Pa, P1*P
2> + Two 16-pin counters (To terminal + Ti
terminal) and two interrupt terminals INTo, INT
+ and using a 12 MHz crystal, the execution time t/'i is 1 μ per instruction/yon.
sec.

The microcomputers 41 and 42 serially transfer data via open collector inverter buffers 43 to 46 by an asynchronous transfer/transmink (hereinafter referred to as rUARTJ).

Here, the functions of the UART of the microcontrollers 41 and 42 will be briefly explained. As shown in FIG. 4, the internal registers of the UART include a transmit buffer 401, a receive buffer 402, and so on.
Irukapatufa 403. control word register 40
4, has all the functions necessary for data communication, and interfaces with modems and terminal equipment.

The transmission buffer 401 receives data from the accumulator/? Converts the /1 parallel data sent via the spuffer into serial data consisting of the required number of characters and bits, and sends it out from the TxD terminal according to the control signal.

Furthermore, the reception buffer 402 converts serial data sent from the RXD terminal via the input amplifier 403 into parallel data, and converts it into parallel data.
The bits and characters are checked according to the communication format specified in the mode set by the initial setting of 04, and the assembled characters are sent to the accumulator.

Note that FIG. 5 shows the transmission data "toughness" in this system. In the figure, the first stage is address data, and the second stage is information data.

In this way, 256 pieces of data can be sent to 256 terminals.

In this way, the microcontrollers 41 and 42 are connected to the UART RX
When serial data is input to the D terminal, an internal interrupt is generated, and the input data is read by jumping to a specific register. Data communication is performed according to the protocol between the multiprocessors and information is exchanged.

Referring to FIG. 2, a Schmitt trigger inverter 50 and a CMOS inverter 5 are connected to the To terminal of the microcomputer 41.
A timing pulse from an encoder 52 is inputted via 1.

The encoder 52 is constructed by disposing a light emitting diode 54 and a phototransistor 55 facing each other, sandwiching a slint disk 53 that rotates in synchronization with the rotation of the belt photoreceptor 8.

The timing pulses input to the To terminal of the microcomputer 41 are counted by an event counter, and the microcomputer 41 performs sequence control of the copying process based on the count value.

This counter is capable of counting up to 64,000 numbers, and counts by hardware regardless of program execution.

By counting timing pulses with the event counter in this way, the problem that occurs when timing pulses are input to the interrupt terminal and counted by software is that an interrupt occurs every time a timing pulse is input. For example, the Luss period is 50μ
sec, an interrupt occurs every 50 μsec, which solves the problem of delayed program execution time and malfunction.

The T1 terminal of the microcomputer 41 detects the start position mark 56 on the belt photoreceptor 8 with a reflective photoelectric sensor 59 consisting of a light emitting diode 57 and a phototransistor 58, and outputs InnoPataro 0 and Schmitt Trigger Input. A timing start pulse signal obtained through 61 is input.

The microcomputer 41 starts sequence control when this timing start pulse is input.

A zero-cross pulse of the AC power supply voltage is input to the interrupt terminal INTo of the microcomputer 41.

That is, the AC voltage of the IOV, which is obtained by stepping down the AC power supply voltage by a transformer (not shown), is full-wave rectified by the full-wave rectifier 62 and applied to the light-emitting diode 63 . Then, the light emitting diodes 6 and 3 are turned off near the AC zero cross point, and turned on and emit light at other times, so the phototransistor 64, which forms a photocoupler together with the light emitting diode 63, is turned off every time around the AC zero cross point.

As a result, the input side of the Innopartaro 5 becomes a high level 5H" at every zero cross point, and a zero cross pulse that becomes a high level 1H" at every AC zero cross point is generated on the output side of the gain converter 66. A pulse is input to the interrupt terminal INToK.

The edge of this interrupt from the microcomputer 41 can be detected by setting a flag in the register, using a falling pulse.

The microcomputer 41 detects the edge of the zero-cross pulse, starts an internal counter, and controls the power phase of the halogen lamp 1 and the xenon lamp 23 based on the result.

The signals input to the port P1 via the inverter group 67 are input to the interrupt terminal lNT1 of the microcomputer 41 via the open collector inverter group 68, respectively.

This includes a copying machine, sorter, collator, automatic document feeder (ADF), charge counter, and document reader (OCR).
This is because when an external device such as ) is attached, the interface with the external device such as this is connected to the UART of the microcomputer 41 using a digit chain method.

That is, when the external device outputs an acknowledge signal requesting permission to use the line to port P1 of the microcomputer 41, an interrupt is generated at the interrupt terminal INTt of the microcomputer 41, and the microcomputer 41 polls the port P1 to determine which external device Determine whether permission to use the line has been requested.

Then, when the microcomputer 41 permits the use of the line, the UA
An address code is sent from RT and data transfer is performed.

In this embodiment, when the port P1Vc acknowledge signal of the microcomputer 41 is input from the ports P1 and P2 of the microcomputer 42, and the microcomputer 41 permits the use of the line, data transfer between the microcomputers 41 and 42, that is, the microcomputer 41 is performed. 42 is the key human power information data, and the microcomputer 41 is the sequence status.

The commands of the pulse motor and each data of display information are transferred.

A voice synthesis chip 70 controlled by a control signal from a microcomputer 741 is connected to a port P21C1'j of the microcomputer 41.

This speech synthesis chip 70 has an internal speech memory of 32 bits and is capable of speech of 26 seconds, but since this alone is insufficient for guidance, an external speech memory of 32 bits is provided.
Connect bit speech ROM 71 to 28, and 100
sec speech is possible.

This voice synthesis chip 70 reads operation commands from the microcomputer 41 via a bidirectional path line, reads data from the internal speech memory or data from the speech ROM 71, synthesizes the voice necessary for information transmission, and synthesizes the voice. The sound is sent to the speaker 7 via a filter 72 and an amplifier 73.
Output to 4.

Then, each time one phrase of audio is output, the terminal lN
(from TR to microcontroller 41 port via Impertaph 5)
A completion signal is output to P2.

The microcomputer 41 is connected to an A/D converter 78 to which a detection signal from the linear optical sensor 5 composed of a fiber lens 76 and a photodiode array 77 for detecting the image density and size of the original 10 is input in parallel. It is.

The microcomputer 41 controls the A/D converter 78 to execute A/D conversion of the A parallel input, and determines the image density and size of the original 10 based on the conversion result input from the A/D converter 78. do.

Then, based on this determination result, dimming and outputs of various high-voltage power supplies and development bias power supplies are controlled.

Since the microcomputer 41 does not have enough capacity with just the internal ROM and RAM, a 2K''-item CMO8 is used, which is punctured with a 2-item IO/ROM 80 and a battery 81.
RAM 82 is connected.

The microcomputer 41 is connected to a calendar/clock IC 84t which is powered by a battery 83 and serves as a time measuring means for continuously measuring time.

This calendar/clock IC 84 has a reference frequency of 32
,768 KHz, 1.05MHz, 4.19
You can select any one of MHz, hour 9 minutes 9 seconds 1
1st of the month.

It contains day of the week data, and the data format is input and output by the microcomputer 41.

The microcomputer 41 reads out the data from the calendar/clock IC 84 and displays a liquid crystal display which is arranged opposite to the blank area of the copy of the Wurth photoreceptor 8 and can display the displayed characters in reverse, as shown in FIG. 6, for example. The data is displayed on the device 85, and the date and time are recorded on the copy.

In addition, when placing the liquid crystal display 85 on the contact glass 9 as shown in FIG. 7 and inserting the date and time on the copy, the liquid crystal display 85Fi, for example, as shown in FIG. Configure to display.

It is also possible to display the date and time on an operation panel (not shown) of the copying machine.

The microcomputer 41 receives fixing temperature detection signals from various sensors (not shown), an ACC effective value detection signal indicating the effective value of the AC power supply voltage, and a surface potential detection signal vH from a surface electrometer 87, which is a body surface potential detection means. An A/D converter 86 that performs A/D conversion based on a control signal from the microcomputer 41 is connected thereto.

As shown in FIG.
0 and an amplifier circuit 91.

As shown in FIG. 11, the electrostatic field chopper 88 detects the white part (background part) of a general document placed on the contact glass 9.
As shown in FIG. 10, the standard white plate 92 corresponding to the standard white plate 92 is arranged near the belt photoreceptor 8.

As shown in FIG. 12, this electrostatic field chopper 88 includes a case 88 for electrostatic shielding in which an aperture 880a is formed.
A detection electrode 881 is arranged inside the aperture 880a facing the aperture 880a, and between the aperture 880a and the detection electrode 881, a tuning fork 884 is supported by a mounting base 882 and vibrated by an oscillation element 883. A printed circuit board 886 is disposed with the formed short electrode 885 interposed therebetween, on which a circuit for converting the electric flux Δ induced in the sensing electrode 881 from current to voltage and outputting a voltage signal Sv is formed. In addition, in the figure, 887 is a connector.

Returning to FIG. 9, the oscillation circuit 89 includes resistors R1 and R2.
+ Consists of a capacitor C1 and an operational amplifier 890, and outputs a signal that causes the oscillation element 886 of the electrostatic field chopper 88 to oscillate.

The rectifier/filter circuit 90 consists of resistors R3 to R6m, capacitors C2 and C5, and an auxiliary pair 900.

The voltage signal Sv from the electrostatic field chopper 88 is rectified and waveform shaped.

The amplifier circuit 91 includes resistors R7 to R11 and capacitors C4 to
C6+ diodes D1 and D2, operational amplifier 910
and 911, and outputs a surface potential detection signal vH which is an amplified signal obtained by waveform shaping the voltage signal SV from the electrostatic field chopper 88.

The operation of the surface electrometer 87 configured in this way will be explained.

First, since the aperture 880a of the electrostatic field chopper 88 is disposed to face the belt photoreceptor 8, lines of electric force due to surface charges on the belt photoreceptor 8 enter the detection electrode 881 via the aperture 880a.

In this state, a DC voltage is applied to the oscillation circuit 89 to cause it to oscillate, and its output is transmitted through the electrostatic field and the oscillation element β83 of 88.
, the tuning fork 884 self-excited to vibrate at the resonant frequency, and the chopper electrode 885 vibrates to open and close the aperture 880a at a constant cycle, so that the belt photoreceptor 8. The electric field due to the surface potential does not fluctuate at a constant period.

Thereby, the sensing electrode 8 located in the varied electric field
81 shows the surface potential of the belt photoreceptor 80 and the chopper electrode 8.
A flux current corresponding to the difference in the potential of the capacitor 85 (same potential as that of the casing 880) is induced, and an AC voltage signal Sv corresponding to this flux current is output from the electrostatic field chopper 88.

This AC voltage signal Sv is rectified and waveform-shaped by a rectifier/filter circuit 90, then amplified by an amplifier circuit 91, and output as a surface potential detection signal vH corresponding to the surface potential of the belt photoreceptor 8. .

13, 14, and 15 show the surface of the belt photoreceptor 8 when the gaps between the belt photoreceptor 8 and the electrostatic field chopper 88 of the surface electrometer 87 are 2B, 3B, and 4B. An example of the relationship between the potential and the output voltage of the surface electrometer 87 is shown.

Returning to FIG. 2, the microcomputer 41 controls the light emission of the xenon lamp 23 for fixing shown in FIG. 1 based on the A/D conversion result of the AC effective value detection signal based on the A/D conversion result of the fixing temperature detection signal. Based on this, the power supply of the halogen lamp 1 is regulated (dimmer control) via the analog output control circuit 96.

Further, the microcomputer 41 controls the voice synthesis chip 70 based on the A/D conversion result of the human body detection signal to issue a voice notification only when there is an oiler in the vicinity of the copying machine.

Furthermore, the microcomputer 41 outputs A/A of the surface potential detection signal vH.
Based on the D conversion result, the outputs of the charging and transfer high voltage power supplies and the developing bias power supply are controlled via the analog output control circuit 93.

In other words, the microcomputer 41 also serves as an output control means.

As shown in FIG. 16, the analog output control circuit 93 includes four D/A converters 94, 95, 96, 97 that convert digital data sent from the microcomputer 41 into analog data, D/A converter 94
It consists of output circuits 98, 99, 100, and 101 consisting of operational amplifiers and the like that convert the current outputs from 97 to 97 into voltage.

The D/A converter 94 and the output circuit 98 output a high voltage output control signal HV+ to the high voltage power source 4 according to the output control data of the charging high voltage power source 4 from the microcomputer 41 .

As shown in FIG. 17, this high voltage power supply 4 includes a comparator 405 that compares the high voltage output control signal HVl with a feedback current, a switching circuit 406 that performs switching according to the output of this comparator 405, and a step-up transformer. 407 and a rectifier circuit 408, and applies a high voltage output to the scorotron charger 3 according to an analog high voltage output control signal HV1. This high voltage power supply 4 has a 600
The output can be varied within the range of -1200 μA.

The D/A converter 95 and output circuit 99 in FIG. 16 output a high voltage output control signal HV2 to the high voltage power source 102 according to the output control data of the high voltage power source 102 for transfer from the microcomputer 41. Note that the configuration of the high voltage power source 102 is similar to that of the high voltage power source 4, and the output can be varied within a range of 5.5 to 8 KV.

The D/A converter 96 and the output circuit 100 are connected to the microcomputer 41.
The developing bias voltage control signal BV corresponding to the output control data of the developing bias power source 103 from the developing bias power source 1
Output to 03. Note that the configuration of the developing bias power supply 103 is the same as that of the high voltage power supply 4, and the output can be changed in the range of 100 to 500V.

The D/A converter 97 and the output circuit 101 are connected to the microcomputer 41.
A dimming signal LV corresponding to the dimming data from the lamp control circuit 104 is output to the lamp control circuit 104.

As shown in FIG. 18, this lamp control circuit 104 includes a comparator 104a that compares the dimming signal LV and a detection signal from an effective value detection circuit 104c, and
The phase control circuit 104b controls the phase of the voltage applied to the halogen lamp 1 according to the output of the halogen lamp 1, and the effective value detection circuit 104c detects the effective value of the voltage applied to the halogen lamp 1. A voltage corresponding to the signal LV is output to the halogen lamp 1. This lamp control unit 104 can change the output in the range of AC 30 to 80V.

Next, returning to FIG. 3, port P1 of the microcomputer 42. P
2 via the display driver/controller 110.
Switch matrix circuit 1 for 7-segment displays 111 and 112, number of copies, print start key, etc.
13 are connected to each other.

A microphone 114 is connected to port Pa of the microcomputer 42.
A voice recognition unit 115 is connected to analyze the spectrum of the voice input via the voice recognition unit 115 and recognize whether it matches the already registered voice. We are making it possible to do this.

An example of the system configuration of this voice recognition unit 115 is shown in FIG. Note that illustration of a nonvolatile RAM that stores registered voice and data is omitted.

In the figure, the voice recognition chip VRC detects a state sequence of voiced sounds, unvoiced sounds, and parameters in an input word or phrase, and compares this sequence with a stored sequence of word spirit registered in advance. Recognize speech. Its state sequence and recognition parameters are stored in a one-chip ROM.

Further, another example of the system configuration of the voice recognition unit 115 is shown in FIG.

This system includes a preamplifier/equalizer 115a that inputs audio signals from a microphone, an automatic level adjustment circuit 115b, a speech preprocessor 115c, an A/
It is composed of a D converter 115d, a reference i4-turn RAM 115e, and a recognition/control circuit 115f.

The speech preprocessor 115c includes 16 bandpass filters each separated by a half-wave rectifier, a second-order low/mother filter that cants off 25Hz, and 80 operational amplifiers to achieve the necessary audio frequency spectrum analysis. , a 16-channel analog multiplexer, a decoder, etc., and contains audible frequencies exceeding the range in which speech can be easily recognized, i.e. '
It is equipped with a spectrum analysis function of 200 to 7000Hz.

In addition, the recognition/control circuit 115fld, word boundary detection,
Amplitude normalization, endpoint time reduction.

It contains an overall algorithm for recognition of separated utterances, including programmable language integration.

This recognition/control circuit 115f is connected to the parallel
0. Analog multiplexer for control.

Equipped with an A/D converter, it reads commands given through a parallel input port, and outputs recognition and command responses through a parallel output port.

This speech recognition system analyzes input speech with a 16-channel spectrum analyzer and converts it into constant-sized patterns that preserve information content while removing redundant features.

These seven words are used during word training to estimate the type corresponding to each word item, and are used in the recognition process to compare with the input speech.

In addition, this speech recognition system has two training modes: a normal training mode in which all or some of the specific word types are cleared and several selectable samples are registered, and a normal training mode in which specific word types are stored. The word pattern updating means is provided for increasing word patterns by additionally registering reference nos and turns.

Returning to FIG. 3, the T1 terminal of the microcomputer 42 has an i! for registration control. A pulse motor drive circuit 117 for driving and controlling the pulse motor 116 is connected thereto.

Next, the adjustment of the surface potential of the belt photoreceptor 8 in the embodiment configured as described above will be explained with reference to FIG. 21 and subsequent figures.

First, in each processing stage of the copying process, the bright area surface potential VHA of the belt photoreceptor 8 corresponding to the bright area (area where much light is reflected) of the document and the dark area (area where there is little light reflection) of the document are determined. The dark surface potential VHB changes as shown in FIG.

In the figure, primary charging means a state charged by the scorotron charger 3, static elimination means a state in which static electricity is removed by the erase lamp 12, and exposure means a state in which the location lamp 1 is turned on and exposed.

By the way, what is needed as the final electrostatic latent image is the 21st
The bright area surface potential VHA and the dark area surface potential VHB at point 0 in the figure are shown in FIG. 22, but as shown in FIG. decreases like VHB'.

Therefore, compensation control is performed so that the difference between the bright area surface potential vHA and the dark area surface potential VHB at the 0 point in FIG. 21 becomes constant.

Next, details of the surface potential compensation control executed by the microcomputer 41 will be described.

First, target values of the bright area surface potential VHA and the dark area surface potential VHB that provide appropriate image contrast are set in advance,
Its target value, for example, VHA=-50V.

VHB=-450V (7) Store f'-V in ROMK.

Then, based on the time measurement result by the calendar/clock IC 84 shown in FIG.
The bright area surface potential vHA and the dark area surface potential VHB at point 0 in the figure are measured.

This surface potential measurement is performed for each dimming blade of the halogen lamp 1, for example, in the case of digital dimming, for each step, using the standard white plate 92 (the standard white plate 92) with the standard light amount corresponding to each dimming blade by the halogen lamp 1. 11) and measure the bright area surface potential VHA, and the dark area surface potential VHB with the halogen lamp 1 turned off.

The data of the measurement results obtained in this way, for example, Table 1
Data as shown in is stored in the RAM 82.

Thereafter, based on this data, the bright area surface potential vHA and the dark area surface potential V correspond to the selected dimming blade.
In the above example, set the target value to VHA"-50V so that the difference from HB is constant.

Since VHB=-450V, 1yfi- in Table 1
The output of the charging high-voltage power supply 4 is controlled so that ZnI (n=1...8) is constant at 400V.

Note that the surface potential of the belt photoreceptor 8 depends on the current injected to the surface of the photoreceptor by the scorotron charger 3, so as shown in FIG.
By changing the high voltage output control signal HV· (control voltage) with respect to FIG. 16) and changing the output current IH of the high voltage power supply 4, the surface potential VH is also changed.

This surface potential VH increases the output current IH of the high voltage power supply 4 by 60
When it changes in the range of 0 to 1200 μA, it changes in the range of 400 to 900 V, although it depends on the structure of the scorotron charger 3.

In this way, by periodically measuring the surface potential of the belt photoreceptor 8 and controlling the output of the charging high-voltage power supply 4 so that the difference between the bright area surface potential vHA and the dark area surface potential VHB becomes constant. , copies with appropriate image contrast can be stably obtained.

Further, by measuring the surface potential of each light control blade and controlling the output of the charging high-voltage power supply 4 based on each measurement result, a constant image contrast can be obtained even if the light control blade is changed.

In parallel with such output control of the charging high-voltage power source 4, the transfer efficiency is improved by controlling the output of the transfer high-voltage power source 102 (FIG. 16) to be 300 to 400 V higher than the output of the charging high-voltage power source 4. Also, the developing bias power supply 103 (
By controlling the output of FIG. 16) to be slightly higher than the dark area surface potential VHB, copies without background stains can be obtained.

However, as shown in FIG. 24, the bright area surface potential VHA of the photoreceptor does not drop even as the photoreceptor deteriorates over time.

In addition, in Fig. 24, tc1 to tc5 indicate one hour of continuous copying;
ts1 to ts3 indicate pause times.

In this case, in order to increase the dark surface potential VHB,
Although it is necessary to increase the output current of the charging high-voltage power supply 4, there is a certain limit due to the capacity of the power supply, and the larger the output current, the more leakage inside the charger case, which is impractical.

Therefore, the bright area surface potential vA is a predetermined value (residual potential 30
If the voltage falls below (equivalent to 0 V), proper image contrast cannot be obtained, so it is desirable to instruct the operator to replace the photoconductor by display or voice notification.

As described above, according to the present invention, in a copying apparatus, the adverse effects of deterioration of the photoreceptor over time and the ambient temperature and humidity on copied images are reduced, and high-quality copies can be stably obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a copying apparatus of a static exposure type using a belt-shaped photoreceptor according to the present invention. 2 and 3 are block circuit diagrams of the control section of the copying apparatus. Figures 4 and 5 show the microphone o:+ in Figures 2 and 3.
FIG. 2 is a block diagram showing the configuration of an internal register of the asynchronous receiver/transmitter of the Z computer, and an explanatory diagram showing the transmission data formatter. FIG. 6 is an explanatory diagram showing the display surface of the display device 85 in FIG. 2, and FIGS. 7 and 8 are explanatory diagrams showing other arrangement examples of the display device 85 and the display surfaces in those cases. . 9 is a block diagram showing a configuration example of the surface electrometer 87 in FIG. 2; FIGS. 10 and 11 are explanatory diagrams for explaining the arrangement position of the electrostatic field chopper in FIG. 9; FIG. 2 is a schematic configuration diagram showing the structure of an electrostatic field. Figures 13, 14, and 15 are diagrams showing an example of the relationship between the surface potential and the output voltage when the gap between the belt photoreceptor and the electrostatic field of the surface electrometer is changed. be. Figure 16 shows the analog output control circuit 9 of Figure 2.
3. FIG. 17 is a block diagram showing the configuration of the high voltage power supply 4 in FIG. 16. FIG. 18 is a block diagram showing the configuration of the lamp control circuit 104 in FIG. 16. . 19 and 20 are block diagrams showing different examples of system configurations of the speech recognition unit 115 shown in FIG. 3, respectively. FIG. 21 is a diagram showing an example of the change in surface potential on the photoreceptor at each processing stage of the copying process. FIG. 22 is a diagram showing an example of the relationship between the surface potential of the photoreceptor and time and temperature. , Fig. 26 is a diagram showing an example of the relationship between the control voltage for the charging high-voltage power supply, the output current of the charging high-voltage power supply, and the surface potential of the photoreceptor, and Fig. 24 shows the residual potential of the photoreceptor and aging deterioration. FIG. 2 is a diagram showing an example of the relationship between 1...Halogen lamp 3...Scorotron charger 4...High voltage power supply for charging 6...Carriage 8...
・Belt photoreceptor 13...Developing roller 41.42
... One-chip microcomputer 84 ... Calendar/clock IC (time measurement means) 87 ... Surface electrometer 92 ... Standard white plate 93 ... Analog output control circuit 102 ... High voltage power supply for transfer 103...Development bias power supply 104...Run saw/trawl circuit 1''! From the accumulator in Figure 4 of 132247/1986 (l) Figure 5

Claims (1)

[Claims] 1. In a copying apparatus, a time measuring means for continuously measuring time, a surface potential detecting means for detecting a surface potential of a photoreceptor, and a measuring means for detecting the surface potential at regular intervals based on the measurement results of the time measuring means. The detection means is controlled to measure the bright area surface potential corresponding to the bright area of the original and the dark area surface potential corresponding to the dark area of the original on the photoreceptor, and based on the measurement results, the high voltage power source for charging and the developing bias power source are controlled. 1. A copying apparatus comprising output control means for controlling each output.