JPS6142283A - High voltage power source - Google Patents

Abstract

PURPOSE:To readily obtain bias voltages of positive and nagative polarities by connecting two series circuits of diodes and resistors in parallel with DC bias windings, and connecting a variable resistor between the both diodes. CONSTITUTION:A capacitor C is connected between the starting end (a) of the secondary side AC high voltage output winding N2 of a transformer T and a ground GND to form an AC high voltage output circuit. A series circuit of a diode D1 and a resistor R1 and a series circuit of a diode D2 having reverse polarity of the diode D1 and a resistor R2 are connected in parallel with a DC bias windings N3, and a variable resistor VR is connected between both diodes D1 and D2 to form a DC bias 2 output circuit.

Description

[Detailed description of the invention] [Industrial application field] The present invention applies to high voltage power supply devices such as copying machines.

[Prior Art] In conventional high-voltage power supply devices such as copying machines, in order to output AC high voltage and DC bias, in addition to an AC high-voltage output power supply, a DC power supply that outputs positive and negative DC bias voltages is used. Since a power supply section was provided separately and this DC bias voltage was superimposed on the AC high voltage and applied to the load, the DC bias power supply section became large, leading to an increase in cost.

[Structure of the Invention] The present invention provides a high-voltage power supply device in which the DC bias power supply unit that applies the positive and negative DC biases described above is configured in a small size and the cost is reduced.

The configuration will be explained below using the illustrated circuit.

In the figure, the king is the transformer of high-voltage power supply equipment such as copying machines,
N1 is its primary winding, and N2 is its secondary AC high voltage output winding. A capacitor C is connected between the winding start end a of the secondary-side AC high-voltage output winding N2 and the ground GND to form an AC high-voltage output circuit.

AC is an output terminal of the AC high voltage output winding N2, and a load such as a copying machine is connected to this terminal AC and the ground GNDIII.

N3 is a DC bias winding provided on the secondary side of the transformer T, and one end of this DC bias winding N3 is connected to the connection point between the AC high voltage output winding N2 and the capacitor C. A resistor R1 is connected to the other end of this DC bias winding N3.
A series circuit consisting of a resistor R2 and a diode D1 having a polarity opposite to that of the diode D1 is connected in parallel to this series circuit. A single variable resistor VR is connected between the diodes D1 and D2, and the output terminal of the variable resistor VR is connected between the capacitor C and the ground G. A DC bias output circuit is constituted by the DC bias winding N3, resistor R1, diode D1, resistor R2, diode D2, and variable resistor VR.

The output current of the DC bias winding N3 is
- When the flow passes through the diode D1 to the variable resistor VR, it flows through the resistor r1 on the back of the variable resistor VR to the output terminal, and at this time, the current flows between point a at one end of the DC bias winding N3 and the output terminal of the variable resistor VR. The DC output voltage outputted between the point and the point becomes a voltage value adjusted by the resistor r1 of the variable resistor VR. On the contrary, when the output current of the DC bias winding N3 flows to the variable resistor VR via the diode D2 and the resistor R2, the DC output voltage becomes a voltage value adjusted by the resistor r2 of the variable resistor VR.

The output of the DC bias output circuit is output between a point a at the winding start end of the AC high voltage output winding N2 and a point b at one end of the capacitor C, and is superimposed on the AC output of the AC high voltage output circuit. At this time, the capacitor C cuts the direct current flowing into ll1l between points a and b.

The present invention is constructed as described above, and the AC high voltage output voltage of the AC high voltage output winding N2 is applied to a load such as a copying machine connected between its output terminal ΔC and the ground GND, and the DC bias The DC output voltage of the output winding N3 becomes a positive and negative DC bias voltage by the diode D1 and the diode D2, and becomes the DC bias voltage selected by the resistance values r1 and r2 of the variable resistor VR, and is output to the AC high voltage output winding. The voltage is superimposed on the output of N2 and applied to the copying machine, and the copying machine uses this applied voltage to neutralize and charge the photosensitive drum.

[Effects of the Invention] As described above, the present invention provides a series circuit of a diode D1 and a resistor R1 with respect to the DC bias winding N3, and a diode D2 and a resistor R2 having a polarity opposite to that of the diode D1.
This series circuit is connected in parallel, and both diodes D1
．． Since a variable resistor VR is connected between D2 to configure a DC bias output circuit, bias voltages with different positive and negative polarities can be easily obtained, and the output of the DC bias output circuit is an AC high voltage output @ line. Since it is connected between point a at the winding start end of N2 and point b at one end of capacitor C, there is no need to separately provide a DC power supply unit that outputs a bias voltage as in the conventional case, and the DC power supply unit is small and compact. As a result, costs can be reduced.

[Brief explanation of drawings]

The drawings depict one embodiment of the invention. N2: AC output winding. N2: DC bias winding. R1, R2 + resistance. Dl, D2: Diode. ■R: Variable resistance.

Claims (1)

[Claims] an AC output winding, a DC bias winding connected to one end of the AC output winding, a resistor connected to the other end of the DC bias winding, and a diode connected to the resistor. a series circuit of a resistor and a diode of opposite polarity connected in parallel to the series circuit;
and a variable resistor connected between both of the diodes,
A high-voltage power supply device comprising a capacitor connected between a connection point between the AC output winding and the DC bias winding and an output terminal of the variable resistor.