JPH06317922A - High voltage power source for image forming device - Google Patents

Abstract

PURPOSE:To prevent the faulty separation of a transfer material from occurring by making the separation electrode of an image forming device always secure constant separation ability. CONSTITUTION:An AC high voltage generating circuit 21, an AC current detecting circuit 22 detecting an outputted AC current value, a DC high voltage generating circuit 23, and a DC current detecting circuit 24 detecting an outputted DC current value are provided inside the high voltage power source 20. The AC current value is controlled to be an outputted indicated value from a CPU by providing an AC current controlling circuit 21A between the AC high voltage generating circuit 21 and the AC current detecting circuit 22. The DC current value is controlled by providing a DC current controlling circuit 23A between the DC high voltage generating circuit 23 and the DC current detecting circuit 24 in the same way.

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 power to a separation electrode for separating a transfer material provided in an electrophotographic image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Generally, a copying material of an electrophotographic image forming apparatus is composed of a platen on which a document is placed, a document irradiation lamp reciprocating below the platen, a reflection mirror, and a fixed projection lens and a reflection mirror. For example, a scanning optical system, a photosensitive drum that is an image carrier that rotates by being charged with a predetermined potential by a band electrode, and a toner to an electrostatic latent image formed on the surface of the photosensitive drum by the scanning optical system. A developing device for applying and developing, a transfer pole for transferring a toner image onto a recording paper surface which is a transfer material conveyed below the surface of the photosensitive drum, a separation electrode and a removing electrode, and the recording paper. A fixing device for fixing the toner image transferred on the surface and a cleaning device for removing the toner and paper dust remaining on the surface of the photosensitive drum after the transfer.

Then, desired toner images are successively recorded on the surface of the recording paper conveyed along a predetermined conveying path. The cleaned photosensitive drum is recharged according to a predetermined sequence and enters the next image forming process.

Conventionally, the AC component of the AC high voltage generating circuit and D
In a high-voltage power supply that superimposes a DC component from the C high-voltage generation circuit and applies it to the separation pole, its output value is controlled by each constant voltage. In connection with the conventional technique, for example, Japanese Patent Laid-Open No.
89863, JP-A-3-155372 and JP-A-63-2845
No. 68 is disclosed.

[0005]

Normally, the AC current value, which is an AC component applied to the separation pole, is set to 0.7 to 1.3 mmA, and the DC component current value is set to 1 μA to −100 μA. Then, by keeping each of the determined current values constant, the separation performance of the separation electrode is ensured.

However, conventionally, when the high voltage output applied to the separation pole is controlled by a constant voltage, for example, AC high voltage has a drawback that the current values are not fixed because the load changes greatly. The separation performance of the transfer material is very difficult to adjust because the fluctuation of the current component has a great influence, and also causes the separation failure.

The present invention solves such a problem and reduces the fluctuation of each current component applied to the separation electrode to ensure the separation performance in which the separation electrode is always defined. For the purpose of providing.

[0008]

The object of the present invention is to superimpose an AC component and a DC component in a high-voltage power source in the apparatus for supplying a separating means of an electrophotographic image forming apparatus for separating a transfer material from an image carrier. This is achieved by a high voltage power supply for an image forming apparatus, characterized in that a constant current control current control circuit is provided in each of the AC high voltage generation circuit and the DC high voltage generation circuit in the output high voltage power supply.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the block diagram showing the configuration of a high voltage power source having the current control circuit of FIG. 1 and the side sectional view showing the configuration of the image forming apparatus of FIG.

However, the present invention is not limited to this embodiment.

As shown in FIG. 2, an electrophotographic image forming apparatus (hereinafter simply referred to as an image forming apparatus) 18 is provided with a platen glass P on which an original M is placed on the upper surface of the main body 1, and the platen glass P in the main body 1 is provided. A scanning optical device 2 is provided below. The scanning optical device 2 comprises a reciprocating document irradiation lamp 2a, a first mirror 2b, second and third mirrors 2c forming a V shape, a fixed projection lens 2d and a fourth mirror 2e. A photoconductor drum 3 is rotatably provided in the center of the inside of the main body 1 in the direction of the arrow, and in the periphery thereof, a belt electrode 4 for uniformly charging the photoconductor 3a along the rotation direction and a toner replenishing device. 5, the toner is replenished with toner, the developing device 6 including the developing sleeve 6a, the transfer electrode 7,
The separation electrode 8, the static elimination electrode 9, and the cleaning device 10 are sequentially arranged. Two kinds of recording papers of different sizes are housed in the paper feed cassettes 11 and 11 'and set in the main body 1. Reference numeral 12 denotes a first paper feed roller that feeds the recording paper stored in the paper feed cassette 11 to a standby position before the second paper feed roller 13, and a belt is provided to prevent double feeding of the recording paper. It is composed of rotating rollers 12a, 12a and a stop roller (also referred to as a separating roller) 12b. 13 is an appropriate timing so that the recording paper fed by the first paper feed roller 12 is temporarily stopped at the standby position, and then the leading edge of the visible image on the photoconductor 3a and the leading edge of the recording paper are aligned at the transfer position. The second paper feed roller 14 for re-feeding the paper toward the transfer position is a guide plate for guiding the recording paper fed by the first paper feed roller 12 to the position of the second paper feed roller 13. Reference numeral 15 denotes a conveying device that conveys the recording sheet after transfer to the fixing position, and the fixing device 16 includes a heating roller 16a and a pressure roller 16b. Reference numeral 17 denotes a paper discharge roller that discharges the recording paper after fixing to the outside of the main body.

When the copy button is operated in the above apparatus, the original M on the platen glass P is exposed and scanned by the scanning optical device 2, and an electrostatic latent image of the original M is formed on the photoconductor 3a of the photoconductor drum 3. It This electrostatic latent image is developed by the developing device 6.
Is converted into a visible image by the transfer electrode 7 and transferred to the recording paper fed from one of the paper feed cassettes 11 and 11 'of the main body 1. After the transfer, the recording sheet is separated from the photoconductor 3a by the separation electrode 8 and is fixed by the transport device 15.
The sheet is conveyed to 16, is fixed there, and is ejected by the ejection roller 17. In this way, desired toner images are successively recorded on the recording paper surface.

Next, a high voltage power supply for an image forming apparatus equipped with the current control circuit of the present invention will be described.

As shown in FIG. 1, in the high voltage power supply 20, an AC high voltage generating circuit 21, an AC current detecting circuit 22 for detecting the output AC current value, a DC high voltage generating circuit 23, and an output DC
The DC current detection circuit 24 for detecting the current value is connected between the AC high voltage generation circuit 21 and the AC current detection circuit 22,
It is connected between the AC current control circuit 21A for controlling the current value, the DC high voltage generation circuit 23 and the DC current detection circuit 24, and D
And a current control circuit 23A for controlling the C current value.

The AC high-voltage component output from the AC high-voltage generating circuit 21 and the DC high-voltage generating circuit 23 DC output from the DC
The high voltage component is superimposed and applied to the discharge wire 8a of the separation electrode 8.

When the CPU of the image forming apparatus 18 instructs the high-voltage power source 20 to output high-voltage AC and DC high-voltage output values, the high-voltage AC generation circuit 21 based on the output instruction values.
And an AC voltage determined by the DC high voltage generation circuit 23,
The AC current, the DC voltage, and the DC current are superimposed and applied to the discharge wire 8a of the separation electrode 8.

Simultaneously with the application to the separation electrode 8, the AC current output by the AC high voltage generation circuit 21 is input to the AC current detection circuit 22 shown by the arrow, confirmed by the AC current detection circuit 22, and then shown by the arrow. It is fed back to the AC current control circuit 21A.

Then, the AC current control circuit 21A controls the fed back AC current value, and the output value actually output from the AC high voltage generation circuit 21 is compared with the output instruction value from the CPU to separate the transfer machine. If there is a high or low value that affects the output voltage, the output value to the AC high voltage generation circuit 21 is corrected and controlled so that it becomes the output instruction value of the CPU.

Similarly, the output value output from the DC high voltage generation circuit 23 is also confirmed via the DC current detection circuit 24 and then fed back to the DC current control circuit 23A so that the DC current becomes the output instruction value of the CPU. Value is controlled D
The C high voltage generating circuit 23 always outputs a predetermined DC current value.

As described above, the AC and DC current control circuits 21A and 23A are provided in the high-voltage power source 20 for constant current control, so that the separation electrode 8 always maintains a constant separation performance under any load condition. Became possible. Note that the present invention has been described by taking a mono-black image forming apparatus as an example, but it goes without saying that the present invention is also applied to a color image forming apparatus.

[0021]

With the high voltage power supply provided with the current control circuit of the present invention, the separation electrode of the image forming apparatus is always applied with a constant current controlled current value to ensure the predetermined separation performance, and to secure the transfer material. It has become possible to prevent poor separation.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a high-voltage power supply including a current control circuit according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing the configuration of the image forming apparatus.

[Explanation of symbols]

 8 Separation Electrode 8a Discharge Wire 18 Image Forming Device 20 High Voltage Power Supply 21 AC High Voltage Generation Circuit 21A AC Current Control Circuit 22 AC Current Detection Circuit 23 DC High Voltage Generation Circuit 23A DC Current Control Circuit 24 DC Current Detection Circuit

Front Page Continuation (72) Inventor Seiji Takaba Seiji Kagawa Co., Ltd. 2970 Ishikawacho, Hachioji City, Tokyo

Claims (1)

[Claims] 1. An alternating current in a high-voltage power supply for superposing an alternating-current component and a direct-current component in a high-voltage power supply in the device for supplying power to a separating means of an electrophotographic image forming apparatus for separating a transfer material from an image carrier. A high voltage power supply for an image forming apparatus, characterized in that a current control circuit capable of constant current control is provided in each of the high voltage generation circuit and the DC high voltage generation circuit.