KR920004159Y1 - Charge apparatus for electrography - Google Patents

Abstract

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Description

Charging device of electronic copying machine

1 is a conventional block diagram.

2 is a circuit diagram according to the present invention.

* Explanation of symbols for main parts of the drawings

10: surface potential detection unit 20: amplification unit

30: A / D converter 40: CPU

50: D / A converter 50: high voltage power supply unit

TECHNICAL FIELD The present invention relates to a charging device for an electronic copying machine of the present invention, and more particularly, to a charging device for detecting a potential generated by a corona discharge and controlling the discharge to have a uniform and appropriate value.

In general, to uniformize the corona discharge, the secondary voltage of the high voltage power supply is fed back to detect and control the voltage caused by the load variation.

FIG. 1 is a block diagram of the related art. When a "low" signal, which is a control signal from a CPU, is output, an input unit including a diode D1-D2, a zener diode D3, a resistor R1-R2, and a transistor Q1 ( 1) is applied.

At this time, the diode D1 is turned on so that the DC voltage input through the input terminal P1 flows through the resistor R1 and the diode D1, and the zener diode D3 is turned off.

When the zener diode D3 is turned off, the transistor Q1 is also turned off.

At this time, the DC voltage input through the input terminal P1 is applied to the oscillation amplifier 2 composed of a resistor R3, a capacitor C6, a diode D10, and a transistor Q2, wherein the resistor R3 and the capacitor are Since the transistor Q2 is driven by being charged and discharged by the time constant by (C6), it is amplified and oscillated.

As the transistor Q2 is amplified and oscillated, the transformer 3 induces the voltage applied to the primary coil L1 to the secondary coils L2 and L3 to output the boosted voltage.

The rectifier 4 including the diodes D10-D12 and the capacitors C7-C9 for inputting the boosted voltage induced by the secondary coil L2 of the transformer 3 is rectified to output a stable DC high voltage.

The DC high pressure output from the rectifier 4 is applied to the corona wire W through the resistor R7.

At this time, the voltage of the primary side of the transformer 3 is induced to the secondary coil L3 and fed back to the capacitor C5, the diode D9, the zener diode D6, the transistor Q4, the resistor R5, It is applied to the first voltage detector 5 composed of the variable resistor VR2.

At this time, the voltage induced by the secondary coil L3 and fed back is rectified by the diode D9 and the capacitor C5.

The voltage rectified by the diode D9 and the capacitor C5 is divided by the resistor R5 and the variable resistor VR2.

The divided voltage is applied to the zener diode D6. At this time, the voltage induced by the secondary coil L3 of the transformer 3 is increased so that the divided voltage is equal to or greater than the zener voltage and the zener diode D6 is turned on.

When the zener diode D6 is turned on, a voltage is applied to the first voltage controller 6 including the transistor Q4, the capacitor C4, and the diode D7, and the transistor Q4 is turned on.

As a result, the current flowing through the base of the transistor Q2 flows from the collector of the transistor Q4 to the emitter through the diode D7, so that the transistor Q2 is turned off, so that a high voltage applied to the corona wire W is applied. Will be blocked.

In addition, the DC high voltage output from the rectifier 4 is fed back to the second voltage detector 7 including the capacitor C1, the resistor R4, and the variable resistor VR1 through the resistor R8.

The DC high voltage fed back to the second voltage detector 7 is divided by the resistor R4 and the variable resistor VR1. When the DC voltage fed back becomes higher than a predetermined constant voltage, the resistor R4 and the variable resistor VR1 are divided. ), The divided voltage is also increased to turn on the transistor Q3 in the second voltage control section 8 composed of the transistor Q3, the diode D5, and the capacitor C2.

When the transistor Q3 is turned on, current flowing in the base of the transistor Q2 flows from the collector of the transistor Q3 to the emitter through the diode D4.

As a result, since the transistor Q2 is turned off, the DC high voltage applied to the corona wire W is cut off to control the discharge to have an appropriate value.

In the conventional charging device as described above, only the secondary load of the transformer is controlled by electrical fluctuations and does not detect the surface potential charged on the actual photoconductor surface due to the contamination of the corona wire installed in the charging device and the change in humidity or altitude. There was a problem with the safety measures of the high-voltage power supply device could not be normal discharge.

Accordingly, an object of the present invention is to provide a charging device that uniformly charges an electronic copying machine, improves an image, and prevents electric shock and damage of a high voltage power supply that occur when spark discharge and corona wire breakage due to high voltage application.

Hereinafter, the present invention will be described in detail with reference to the drawings.

2 is a circuit diagram according to the present invention, a surface potential detection unit 10 for detecting the surface potential of the charger, an amplifier 20 for amplifying and outputting the detected potential of the surface potential detection unit 10, and The analog / digital transformer 30 converts and outputs the analog signal output from the amplifier 20 into a digital signal, and generates a power on / off control signal to generate the digital signal of the analog / digital transformer 30. CPU 40 for generating a high voltage control signal by determining whether the input data is an appropriate value and digital / analog for converting and outputting a digital high voltage control signal output from the CPU 40 to an analog signal. Supplying a constant DC high voltage power supply to a charger by inputting a log converter 50 and a power on / off control signal of the CPU 40 and a high voltage control signal digitally converted by the digital / analog converter 50.One consists of a high-voltage power supply unit 60.

In the above configuration, the high voltage power supply unit 60 includes the input unit 1 of FIG. 1, the oscillation amplifier 2, the transformer 3, the rectifier unit 4, and the first-second voltage detectors 5 and 6. It is the same as the structure of the voltage control part 7,8.

Based on the above-described configuration will be described the present invention in detail.

When a low signal, which is a power-on control signal, is output from the CPU 40 and applied to the input unit 65, the input unit 61 outputs a DC voltage input through the input terminal P1 to the oscillation amplifier 62. Done.

The oscillation amplifier 62 which inputs a DC voltage from the input unit 61 performs oscillation and amplification by the input DC voltage.

The voltage oscillated and amplified by the oscillation amplifier 62 is boosted by the transformer 63.

The voltage boosted by the transformer 63 outputs a stable DC high voltage power through the rectifying unit 64 to supply to the corona wire (W).

At this time, the surface potential detector 10 installed at a distance d2 equal to the distance d1 from the surface of the photoconductor D to the corona wire W detects and outputs the surface potential of the charger.

Here, the surface potential detection unit 10 is composed of a potential sensor, a pair of electrodes are subjected to electromagnetic vibration to detect the change in the soluble between the electrode and the surface of the photosensitive member (D) to convert to a voltage.

The operational amplifier OP1 for inputting the potential detected by the surface potential detection unit 10 to the non-inverting multiplier (+) is formed by the resistors R1-R2 and the variable resistor VR1.

Vo: Output voltage of the operational amplifier OP1 Vi: Input voltage of the operational amplifier OP1 Amplified and output as shown in Equation (1).

The A / D converter 30 for inputting the potential that is amplified by the operational amplifier OP1 converts the digital signal into an output digital signal. The CPU 40 that inputs the digital data value output from the A / D converter 30 compares the input data with the set value and outputs a high voltage control signal to the D / A converter 50.

The D / A converter 50 for inputting the high voltage control signal output from the CPU 40 converts and outputs the digital signal into an analog signal and applies it to the base of the transistor Q5.

At this time, the CPU 40 generates a low level signal when the detection target potential is input higher than the set value due to spark discharge or disconnection of the corona wire W, thereby lowering the output value of the D / A converter 50. do.

As a result, when the output signal of the D / A converter 50 becomes low, the base current of the transistor Q5 decreases, thereby increasing the collector voltage.

When the collector voltage of the transistor Q5 is increased, the voltage detected by the voltage detector 65 is increased.

The detection voltage is applied to the voltage controller 66, and the voltage controller 62 reduces the oscillation operation of the oscillation amplifier 62.

When the oscillation operation of the oscillation amplifier 62 is reduced, the voltage applied to the secondary side of the transformer 63 is lowered, so that the DC high voltage output from the rectifier 64 is lowered and applied to the corona wire (W). It is controlled to apply a constant voltage by lowering the voltage.

However, when the detected surface potential is input lower than the set value, the CPU 40 generates a high level signal to increase the output value of the D / A converter 50.

As a result, the base current of the transistor Q5 increases to decrease the collector voltage.

When the collector voltage of the transistor Q5 is reduced, the voltage detected by the voltage detector 65 is lowered.

The detection voltage is applied to the voltage controller 66, and the voltage controller 62 increases the oscillation operation of the oscillation amplifier 62.

When the oscillation operation of the oscillation amplifier 62 is increased, the voltage applied to the secondary side of the transformer 63 is increased to increase the DC high voltage output from the rectifier 64.

As a result, the voltage applied to the corona wire (W) is increased to control to apply a constant voltage.

As described above, the surface potential sensor is installed so as to attract the same distance as the drum surface in the charger, and by detecting and controlling the voltage charged on the actual drum surface due to contamination of the corona wire, disconnection, and change of altitude, the uniformity of electrical charge and electrical This has the advantage of protecting against shock or high voltage power supplies.

Claims (1)

In the charging apparatus of an electromagnetic copier, a surface potential detection unit (10) for detecting the surface potential of the charger, an amplifier (20) for amplifying and outputting the detected potential of the surface potential discharge unit (10), and the amplification unit An analog / digital converter 30 for converting and outputting the analog signal output from the digital signal to a digital signal, generating a power on / off control signal, and inputting the digital signal of the analog / digital converter 30; A digital / analog converter which determines whether the input data is an appropriate value and inputs a digital high voltage control signal output from the CPU 40 and converts the analog high voltage control signal into an analog signal. A high voltage for inputting a power on / off control signal of the CPU 40 and a digital high voltage control signal of the digital / analog converter 50 to supply a constant DC high voltage to the charger; Circuit, characterized by consisting of a ledger tooth 60. The