KR100438730B1 - Apparatus for providing high voltage and electrophotographic processor employing the same - Google Patents

Abstract

A high pressure supply device and an electrophotographic processor using the same are disclosed. The high pressure supply device according to the present invention, which generates the first high pressure applied to the first load and the second high pressure applied to the second load, may apply the common high voltage switching signal to determine the high pressure generation interval, and the first high pressure. A controller configured to generate a first switching signal for determining timing and a second switching signal for determining timing for applying the second high voltage; A high pressure generator configured to generate the first high pressure in response to the common high voltage switching signal; A voltage limiter configured to generate the second high pressure from the first high pressure supplied from the high pressure generator; And a switching unit configured to apply the first and second high voltages to the first and second loads in response to the first and second switching signals. Therefore, since a necessary voltage can be applied to a plurality of loads requiring different voltage levels and different voltage application timings only by the number of high-voltage output circuits smaller than the number of loads, there is an effect of reducing cost and improving design margin. .

Description

High voltage supply and electrophotographic processor using the same {Apparatus for providing high voltage and electrophotographic processor employing the same}

The present invention relates to a high pressure supply device for supplying a high pressure required in the developing unit and the charging unit of the electrophotographic processor.

In general, electrophotographic methods are widely used in copiers, plain paper fax machines, laser beam printers, and the like. This electrophotographic method consists of a charging → exposure → development → transfer → fixing process as is known. Briefly, in the charging process, the photosensitive drum is charged by the charging unit to form a uniform charge in the photosensitive drum, and in the exposure process, an electrostatic latent image is formed on the photosensitive drum by exposing the photosensitive drum corresponding to the original or image data. In the developing process, the developer transfers and attaches the developer to the electrostatic latent image formed on the photosensitive drum. In the transferring process, the developer formed on the photosensitive drum is transferred to the recording paper by the transfer unit. The transferred developer is fixed to the recording paper by the heat and pressure of the fixing unit.

At this time, a high voltage negative voltage is required for charging and developing. Typically, the voltage required for charging is-thousands of V or more, and the bias voltage required for developing is-several hundred V, and requires the highest negative voltage of the charging unit among the charging unit and developing unit. As such, as the voltage levels required for charging and developing are different, the electrophotographic processor has used a separate high voltage supply device as shown in FIG. 1.

Referring to FIG. 1, an electrophotographic processor includes a unit (not shown) that requires a charging unit, a developing unit, and other additional high-voltage power supplies, each of which requires a high pressure of a different size, as well as a control unit. The timing at which the high pressure is applied at (10) is also different.

As described above, in the conventional electrophotographic processor, a plurality of high pressure switch units 20 and 22 and high pressure generators 30 and 32 are provided to supply high pressure to a plurality of units 40 and 42 requiring high pressure. The cost increases and there is a problem that the space occupied when designing the circuit increases.

The technical problem to be achieved by the present invention is a high voltage supply device capable of applying a required voltage to a plurality of loads requiring different voltage levels and different voltage application timings only by the number of high voltage supply circuits smaller than the number of loads. To provide.

Another object of the present invention is to provide an electrophotographic processor using the high pressure supply device.

1 is a view for explaining the configuration of a high-pressure generating device used in a conventional electrophotographic processor.

2 is a view for explaining the configuration of an embodiment of a high pressure supply device according to the present invention.

3 is an embodiment of a high pressure application timing diagram used in the high pressure supply device shown in FIG.

4 is a high pressure application table according to the high pressure application timing diagram shown in FIG. 3.

In order to achieve the above technical problem, the high pressure supply device according to the present invention for generating the first high pressure applied to the first load and the second high pressure applied to the second load, the common high pressure switching to determine the high pressure generation interval A controller configured to generate a signal, a first switching signal for determining a timing for applying the first high pressure, and a second switching signal for determining a timing for applying the second high pressure; A high pressure generator configured to generate the first high pressure in response to the common high voltage switching signal; A voltage limiter configured to generate the second high pressure from the first high pressure supplied from the high pressure generator; And a switching unit configured to apply the first and second high voltages to the first and second loads in response to the first and second switching signals.

In addition, the electrophotographic processor according to the present invention in order to achieve the above technical problem, the charging unit for charging the photosensitive member to a predetermined voltage; A developing unit for supplying a developer to the electrostatic latent image formed on the photosensitive member; Generate a first high pressure for supplying the charging unit in response to a common high pressure switching signal for determining a high pressure generation interval, generate a second high pressure for supplying the developing unit from the first high pressure, and And a high pressure supply device for applying the first and second high pressures to the charging unit and the developing unit, respectively, in response to the first and second switching signals for determining the timing at which the second high pressure is to be applied, respectively.

Hereinafter, with reference to the accompanying drawings the configuration and operation of the high pressure supply device according to the present invention will be described as follows.

2 is a view for explaining the configuration of an embodiment of a high pressure supply device according to the present invention.

The electrophotographic processor according to the present invention has a first load 140 that requires a maximum load voltage and a second load 150 that has at least one or more loads that require a smaller voltage.

In the electrophotographic processor, a charging unit implemented by a charging wire or a charging roller or the like requires a maximum load voltage of about -1500 V to charge the photosensitive drum to about -800V. Therefore, the first load 140 may be a charging unit.

The developing unit performs a developing process of attaching toner to an electrostatic latent image formed by the potential difference between the exposed portion and the non-exposed portion on the charged photosensitive drum surface to form a visible image. The developing unit can adjust the density of the toner visible image by adjusting the developing bias voltage between -400 V and -500 V. In the electrophotographic processor, the second load 150 may be implemented as a developing unit.

In the electrophotographic processor according to the present invention, the high pressure supply device for supplying high pressure to the charging unit and the developing unit includes a control unit 100, a high pressure generating unit 110, a switching unit 120, and a voltage limiting unit 130. It is provided. Here, the switching unit 120 includes a first relay unit 122 and a second relay unit 124. Unlike the conventional high pressure supply device having the charging high pressure generating unit 30 and the developing high pressure generating unit 32 shown in FIG. 1, only one high pressure generating unit 110 is provided.

The control unit 100 may apply the common high voltage switching signal 102 to determine the high voltage generation period, the first switching signal 104 to determine the timing of applying the voltage to the first load 140, and the second load 150. A second switching signal 106 that determines the timing of applying the voltage is output. The control unit 100 is generally implemented as a ROM (not shown) storing a microcomputer (not shown) installed on the main board of the electrophotographic processor using the high pressure supply device according to the present invention and a control program connected to the microcomputer to control the microcomputer. Can be.

The high voltage generator 110 includes a transformer circuit, a rectifier circuit, a smoothing circuit, a high voltage stabilization circuit, and the like, and a commercial AC power source, for example, 110V, during a section corresponding to the common high voltage switching signal 102 supplied from the controller 100. Alternatively, 220V AC power (not shown) is converted into a DC high voltage suitable for use in the first load 140 requiring the maximum load voltage.

The switching unit 120 applies the first and second high voltages to the first and second loads in response to the first switching signal 104 and the second switching signal 104. The first relay unit 122 and the second relay unit 124 provided in the switching unit 120 to apply or cut a high voltage to the first load and the second load may be implemented as a relay.

The voltage limiter 130 is connected to an output terminal of the high voltage generator 110 that outputs the maximum load voltage, and loads at least one or more different second voltages smaller than the maximum load voltage required by the first load 140 to the second load. Output to 150. At this time, in consideration of the voltage level required by the second voltage, if a zener diode is provided, a desired voltage output can be obtained.

3 is an embodiment of a high pressure application timing used in the electrophotographic processor according to the present invention, and FIG. 4 is a high pressure application table according to the high pressure application timing diagram shown in FIG. 3.

In the electrophotographic processor, the charging unit first charges the photosensitive drum, and then the developing unit performs a developing process in which toner adheres to the electrostatic latent image. Therefore, referring to FIG. 3, the first switching signal 104, which is an active low that determines the timing of applying high voltage to the first load 140 corresponding to the charging unit, is at a low level at the first time T1. (Low Level) Signal period starts. That is, the contact of the first relay unit 122 is closed and energized at the time T1, and high pressure is applied to the first load 140. In addition, in the second control signal 106, which is an active low that determines the timing of applying the high voltage to the second load 150 corresponding to the developing unit, the low level at the time T2 later than the time T1 The signal section starts. That is, at the time T2, the second relay unit 124 is energized, and high voltage is applied to the second load 150. On the other hand, the first switching signal 104 becomes a high level at the time T3 after the time T2, and the high voltage applied to the first load 140 is blocked by the first relay unit 122 at the time T3. do. In addition, the second control signal becomes a high level at the time T4 after the time T3, and the high voltage applied to the second load 150 by the second relay unit 124 is cut off at the time T4. The common high voltage switching signal 102 that is active low is a signal that controls the high voltage generator 110 to generate a high voltage during a period in which the first high voltage and the second high voltage are applied, and maintains a low level for the period T1 to T4. .

An embodiment according to the present invention is modified, such as a component for supplying a high voltage to the second load 150, that is, an output terminal for outputting a new switching signal from the controller 100, a voltage limiter having a zener diode and If the relay unit is further provided, it is possible to supply high pressure to another unit requiring high pressure.

As described above, according to the high voltage supply device and the electrophotographic processor using the same, the plurality of loads requiring a different voltage level and different voltage application timing are smaller than the number of loads. The required voltage can be applied only by the output circuit, which reduces cost and improves design margin.

Claims (4)

In the high pressure supply device for generating a first high pressure applied to the first load, and a second high pressure applied to the second load, A controller configured to generate a common high voltage switching signal for determining a high voltage generation period, a first switching signal for determining a timing for applying the first high pressure, and a second switching signal for determining a timing for applying the second high pressure; A high pressure generator configured to generate the first high pressure in response to the common high voltage switching signal; A voltage limiter configured to generate the second high pressure from the first high pressure supplied from the high pressure generator; And And a switching unit configured to apply the first and second high voltages to the first and second loads in response to the first and second switching signals. The method of claim 1, wherein the switching unit A first relay unit applying the first high voltage supplied from the high pressure generator to the first load in response to the first switching signal; And And a second relay unit configured to apply the second high voltage supplied from the voltage limiting unit to the second load in response to the second switching signal. 3. The high pressure supply of claim 1 or 2, wherein the voltage limiting unit includes a zener diode. A charging unit for charging the photosensitive member to a predetermined voltage; A developing unit for supplying a developer to the electrostatic latent image formed on the photosensitive member; Generating a first high pressure for supplying the charging unit in response to a common high pressure switching signal for determining the high pressure generation period, generating a second high pressure for supplying the developing unit from the first high pressure, And a high pressure supply device configured to apply the first and second high pressures to the charging unit and the developing unit, respectively, in response to the first and second switching signals for determining a timing for applying the second high pressure, respectively. Photo processor.