JPH11168877A - High-voltage power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To share a piezoelectric transformer for generating a high voltage and hence make compact a high-voltage power supply device and reduce its weight, by providing a first rectification part at one electrode of the piezoelectric transducer with two insulation electrodes as an output terminal and a second rectification part at the other electrode. SOLUTION: A piezoelectric transducer control circuit 1 rectifies AC output from a polarized output terminal 1c of a piezoelectric transducer 1a by a rectification part 1b according to diodes D1 and D2 to obtain DC output and supplies it to an electrification high-voltage generation circuit 3. An afterimage high- voltage generation circuit 3 superposes an AC voltage to the supplied DC voltage and sends it to a developer 6. Further, the piezoelectric transducer control circuit 1 rectifies AC output from a polarized output terminal 1d by a rectification part 1e consisting of diodes D3 and D4 to obtain DC output and supplies it to the electrification high-voltage generation circuit 3. An AC voltage is superposed on the DC voltage that is supplied by the electrification high-voltage generation circuit 3 and is outputted and then is sent to electrification equipment 4, thus polarizing a piezoelectric transducer and use it in two systems without using a high-voltage transformer that is especially insulated.

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 suitable for an electrophotographic apparatus such as a copying machine or a printer using an electrophotographic method.

[0002]

2. Description of the Related Art Conventionally, in forming an image in an electrophotographic apparatus, various high voltages (hereinafter, referred to as high voltages) are used for charging, developing, transferring and separating.

The voltage supplied to each of the above devices is usually generated using a transformer.

[0004]

However, in the conventional high-voltage power supply device, when a voltage to be supplied to each high-voltage device such as charging, developing, and transferring is generated using a transformer, the voltage of each device is reduced. In order to stabilize the differential voltage with respect to one end of the transformer, one end of the output winding of the transformer is connected to the output of each device.

[0005] Transformers used in such applications require insulation against high voltage, so that expensive and expensive molded transformers must be used, and one transformer is mounted on each device, and a plurality of transformers are mounted. Since a transformer is required, the cost has been increased. Furthermore, it was wide in space.

The present invention has been made under such circumstances, and has as its object to provide a small, lightweight, and inexpensive high-voltage power supply device.

[0007]

According to the present invention, in order to achieve the above object, a high-voltage power supply is constituted as described in the following (1) and (2).

(1) A piezoelectric transformer having two electrodes insulated from each other at an output end, a first rectifier connected to one of the two electrodes, and a piezoelectric transformer connected to the other of the two electrodes. A high-voltage power supply device comprising: a second rectifier connected thereto.

(2) A piezoelectric transformer control circuit having a piezoelectric transformer, a charging high voltage generating circuit, and a developing high voltage generating circuit are provided, and the output terminal of the piezoelectric transformer is polarized so that the charging high voltage generating circuit and the developing high voltage High-voltage power supply unit connected to the generation circuit and sharing the transformer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples of an image forming apparatus.

[Embodiment] FIGS. 1 and 2 are block diagrams showing a configuration of a main part of an "image forming apparatus" according to an embodiment.

First, the configuration of the apparatus will be described. 1 and 2
In the figure, 1 is a piezoelectric transformer control circuit, and 1a is a piezoelectric transformer made of ceramic. Reference numeral 2 denotes a development high voltage generation circuit, and reference numeral 3 denotes a charging high voltage generation circuit. 4 is a charger, 5 is a photoconductor, and 6 is a developing device. 7 is a high-voltage power supply, 8 is a controller, 9 is a scanner, and 10 is a mirror.

The high-voltage power supply 7 generates various high voltages, and includes a piezoelectric transformer control circuit 1, a piezoelectric transformer 1a,
It comprises a developing high voltage generating circuit 2 and a charging high voltage generating circuit 3, and applies an output to a charger 4 and a developing device 6. A scanner 9 for forming an image forms an image on the photoconductor 5 via a mirror 10. The high-voltage power supply 7 and the scanner 9 are sequence-controlled by the controller 8.

More specifically, the high-voltage power supply 7
Is a charging high-voltage generating circuit 3 that supplies a high-voltage DC voltage with a high-voltage AC voltage superimposed on a charger 4 that contacts and charges the photoconductor 5, and visualizes an electrostatic latent image formed on the photoconductor 5. A developing high voltage generation circuit 2 for supplying an output obtained by superimposing a high voltage DC voltage and a high voltage AC voltage to a developing device 6 for forming an image, and a piezoelectric transformer control circuit 1 having a piezoelectric transformer 1a for generating a high voltage to be supplied to each device. Prepare.

Next, the basic operation will be described with reference to FIG.
First, the piezoelectric transformer control circuit 1 rectifies an AC output output from the polarized output terminal 1c of the piezoelectric transformer 1a by a rectifying portion 1b including diodes D1 and D2, and supplies the rectified DC output to the developing high voltage generation circuit 2. The high-voltage developing circuit 2 superimposes an AC voltage on the supplied DC voltage and sends the superposed voltage to the developing device 6 as an output of the high-voltage developing circuit 2. With this output voltage, the developing device 6 performs an operation of turning the electrostatic latent image formed on the photoconductor 5 into a visible image.

Further, the piezoelectric transformer control circuit 1 rectifies the AC output output from the polarized output terminal 1d of the piezoelectric transformer 1a by a rectifying portion 1e composed of diodes D3 and D4 to produce a DC output. Supply. The charging high voltage generation circuit 3 superimposes an AC voltage on the supplied DC voltage and sends the superimposed voltage to the charger 4 as an output of the charging high voltage generation circuit 3. With this output voltage, the charger 4 causes the photoconductor 5
The charging operation is performed by abutting the.

The output voltage of each device is generated by the above basic operation.

Next, a method of polarizing the piezoelectric transformer 1a is shown in FIG.
I will explain using. The conventional piezoelectric transformer (a) usually has a conductor printed on an electrode portion. Normally, the conductor is printed as shown in FIG. 3A, but in this embodiment, the conductor is printed by dividing the output electrode into two parts as shown in FIG. 3B. Polarize.

As described above, according to the present embodiment, an expensive molded transformer can be obtained by using a piezoelectric transformer as a transformer for generating a high voltage without using a transformer having a special insulation treatment against a high voltage. , The high-pressure generator is smaller, lighter, and less expensive.
Further, by polarizing the piezoelectric transformer and using it in two systems, it is possible to share the transformer for each of the high-voltage power supply devices for charging and developing, thereby reducing costs and saving space.

[0020]

As described above, according to the present invention,
A small, lightweight, and inexpensive high-voltage power supply can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a detailed view of a high-voltage power supply device.

FIG. 3 is an explanatory diagram of polarization of a piezoelectric transformer.

[Explanation of symbols]

 1a Piezoelectric transformer 1c, 1d Output terminal 1b, 1e Rectifying part

Claims (2)

[Claims] 1. A piezoelectric transformer having two electrodes insulated from each other at an output end, a first rectifier connected to one of the two electrodes, and connected to the other of the two electrodes. A high-voltage power supply device comprising: a second rectifying unit. A piezoelectric transformer control circuit having a piezoelectric transformer, a charging high voltage generating circuit, and a developing high voltage generating circuit, wherein an output terminal of the piezoelectric transformer is polarized to generate the charging high voltage generating circuit and the developing high voltage generating circuit. A high-voltage power supply unit connected to a circuit to share a transformer.