JP2002023468A - High voltage power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost by eliminating a photocoupler. SOLUTION: A bypass resistance 44 is connected between a photoreceptor 49 and ground, that is, between the output of DC bias and the ground so that electrifying current is allowed to flow, and a resistance value is made lower than (DC bias voltage)/(electrifying current), thus a photoisolation can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage power supply for supplying a potential to a photosensitive member of an electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, a high-voltage power supply of this type has been configured as shown in FIG. 2, reference numeral 1 denotes a transformer, which includes a primary winding 2, a secondary winding 3, and a tertiary winding 4. 5 is a control circuit for controlling and driving the transformer 1; 6 is a diode for rectifying the high AC voltage generated in the secondary winding 3;
Is a smoothing capacitor, 8 is a diode for rectifying the AC generated in the tertiary winding 4, 9 is a smoothing capacitor, 10 is a detection resistor for detecting an output current, 11 is a transistor for amplifying the current detected by the detection resistor 10, Reference numeral 12 denotes a photocoupler that feeds an output current back to the control circuit 5. The diode 8 is connected to the tertiary winding 4 and the transistor 11 is connected to the control circuit 5.

[0003] The above constitutes a first high-voltage power supply.

Reference numeral 13 denotes a transformer, which comprises a primary winding 14, a secondary winding 15, and a tertiary winding 16. 17 is a control circuit for controlling and driving the transformer 13, 18 is a diode for rectifying the high AC voltage generated in the secondary winding 15, 19 is a smoothing capacitor, 20 is a diode for smoothing the AC generated in the tertiary winding 16, 21 Is a smoothing capacitor, and 22 is a variable resistor for adjusting the voltage generated in the transformer 13.

[0005] The above constitutes the second high-voltage power supply.

Reference numeral 23 denotes a corotron to which a first high-voltage power supply is applied, and reference numeral 24 denotes a photoconductor to which a second high-voltage power supply is applied.

Here, the second high-voltage power supply is a constant-voltage power supply for causing the photoconductor 24 to have a potential difference from the ground, and the voltage is detected by the tertiary winding 16.

Since the first high-voltage power supply is superposed on the second high-voltage power supply and is a constant-current power supply, the output current is
3 and the stabilizer of the corotron 23 and the photoconductor 24
And flows through the detection resistor 10.

Here, the detection resistor 10 is connected to the output side of the second high-voltage power supply, and has a potential difference with the ground. Therefore, the detection resistor 10 is electrically separated by the photocoupler 12 to return to the control circuit 5. I have. Further, the photocoupler 12 is provided with a very small current (several tens μA to several hundreds
Since the operation is incomplete at about (μA), the transistor 11, the tertiary winding 4, the rectifier diode 8, and the smoothing capacitor 9 are provided for amplification.

[0010]

In the above arrangement, the photosensitive member 24 is biased by a DC power supply, and the output current needs to be a constant current. Therefore, the current is detected from the bias voltage level by the photocoupler 12 and grounded. It is necessary to perform photo-isolation with the potential level, and there is a problem that the cost is increased.

Therefore, an object of the present invention is to reduce the cost.

[0012]

According to the present invention, in order to solve the above-mentioned problems, a resistor for flowing a charging current is connected between the photosensitive member and the ground, that is, between the DC-biased output and the ground potential. By reducing the DC bias voltage by a resistance value obtained by dividing the DC bias voltage by the output current, photo-isolation can be eliminated to reduce the cost.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The invention of a high-voltage power supply for electrophotography according to claim 1 of the present invention comprises a photoconductor, a corona discharge coronatron arranged opposite to the photoconductor, and a corotron. A first high-voltage power supply that applies a DC voltage of a current, and a DC high voltage of a constant voltage is applied to the conductor of the photoconductor,
A second high-voltage power supply as a reference potential of the photoconductor,
The first high-voltage power supply and the low-potential side of the second high-voltage power supply are grounded, a resistor is connected between the output side of the second high-voltage power supply and ground, and the output current of the first high-voltage power supply is Photoisolation can be eliminated by making the product of the absolute value of the value and the resistance value of the resistor lower than the absolute value of the output voltage of the second high-voltage power supply.

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

In FIG. 1, reference numeral 30 denotes a transformer having a primary winding 31 and a secondary winding 32. 33, a control circuit for controlling and driving the transformer 30; 34, a diode for rectifying the AC high voltage generated in the secondary winding 32; 35, a smoothing capacitor;
Reference numeral 6 denotes a detection resistor for detecting an output current, and the above-mentioned components constitute a first high-voltage power supply.

Reference numeral 37 denotes a transformer, which comprises a primary winding 38, a secondary winding 39, and a tertiary winding 40. 41 is a control circuit for controlling and driving the transformer 37, 42 is the secondary winding 3
9, a diode for rectifying the AC high voltage generated at 9, a smoothing capacitor 43, a bypass resistor 44, and a tertiary winding 4
A diode for smoothing the alternating current generated at 0, a smoothing capacitor 46, and a variable resistor 47 adjust the voltage generated in the transformer 37. The above components constitute the second high-voltage power supply. 48 is a corotron to which a first high-voltage power supply is applied, and 49 is a photoconductor to which a second high-voltage power supply is applied.

Next, the operation will be described. The second high-voltage power supply is a constant-voltage power supply for causing the photoconductor 49 to have a potential difference from the ground, and performs voltage detection by the tertiary winding 40. Since the first high-voltage power supply is superimposed on the second high-voltage power supply and is a constant-current power supply, the output current flows from the wire of the corotron 48 to the stabilizer of the corotron 48 and the photoreceptor 49, flows to the bypass resistor 44, and is detected. It flows to the resistor 36.
Here, since the detection resistor 36 and the bypass resistor 44 are connected at the same ground, the voltage detected by the detection resistor 36 is fed back to the control circuit 33, and the constant current control of the first high-voltage power supply becomes possible.

[0018]

As described above, the present invention provides a corotron for corona discharge arranged opposite to the photoreceptor, a first high-voltage power supply for applying a constant high-voltage DC to the corotron, and a conductor portion of the photoreceptor. The constant current control without photo-isolation of the output current of the first high-voltage power supply in an electrophotographic apparatus composed of a second high-voltage power supply that applies a constant DC high voltage to This is advantageous in terms of cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a high-voltage power supply device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional high-voltage power supply device.

[Explanation of symbols]

 44 bypass resistor 48 corotron 49 photoreceptor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koji Nishioka 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 2H003 BB11 CC01 DD03 2H027 ZA01 5H730 AA00 AS00 AS01 AS02 AS04 BB43 BB82 BB85 EE02 EE07 EE56 FD24 FD31

Claims (1)

[Claims] 1. A photoconductor, a corona for corona discharge arranged opposite to the photoconductor, a first high-voltage power supply for applying a constant current DC voltage to the corotron, and a conductor of the photoconductor And a second high-voltage power supply that applies a constant high-voltage DC high voltage to the reference potential of the photoreceptor, and the first high-voltage power supply and the low-potential side of the second high-voltage power supply are grounded, A resistor is connected between the output side of the second high-voltage power supply and ground, and the product of the absolute value of the output current value of the first high-voltage power supply and the resistance value of the resistance is the output voltage of the second high-voltage power supply. A high-voltage power supply device characterized by being lower than an absolute value.