JP4639437B2 - High voltage power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-voltage power supply device that supplies a potential to a photoreceptor of an electrophotographic apparatus.
[0002]
[Prior art]
Conventionally, this type of high-voltage power supply has been constructed as shown in FIG. 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 AC high voltage generated in the secondary winding 3, 7 is a smoothing capacitor, 8 is a diode for rectifying the AC generated in the tertiary winding 4, and 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, 12 is a photocoupler that feeds back the output current to the control circuit 5, and the diode 8 side has a tertiary winding. 4, the transistor 11 side is connected to the control circuit 5.
[0003]
Thus, the first high-voltage power supply is configured.
[0004]
A transformer 13 includes 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 AC high 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, 22 is a variable resistor, and adjusts the voltage generated in the transformer 13.
[0005]
The second high-voltage power supply is configured as described above.
[0006]
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.
[0007]
Here, the second high-voltage power source is a constant voltage power source for causing the photosensitive member 24 to have a potential difference from the ground, and the voltage is detected by the tertiary winding 16.
[0008]
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 23 to the stabilizing plate of the corotron 23 and the photosensitive member 24, and flows through the detection resistor 10.
[0009]
Here, the detection resistor 10 is connected to the output side of the second high-voltage power supply, and has a potential difference with respect to the ground, so that it is electrically separated by the photocoupler 12 in order to return to the control circuit 5. Further, since the operation of the photocoupler 12 is incomplete with a very small current (several tens of μA to several hundred μA) of a high-voltage power source used in electrophotography, the transistor 11, the tertiary winding 4, the rectifier diode 8, and the smoothing capacitor for amplification. 9 is provided.
[0010]
[Problems to be solved by the invention]
In the above configuration, the photosensitive member 24 is biased by a DC power source, and the output current needs to be a constant current. Therefore, the current detection needs to be photoisolated from the bias voltage level to the ground potential level by the photocoupler 12. There is a problem of increasing the cost.
[0011]
Accordingly, the present invention aims to reduce the cost.
[0012]
In order to solve the above problem, the present invention connects a bias resistor for flowing a charging current between the photosensitive member and the ground, that is, between the DC biased output and the ground potential, and this resistance value is obtained by converting the DC bias voltage by the output current. By making the voltage lower than the divided resistance value , the voltage generated by the resistance and the power supply that supplies the output voltage are superposed to obtain a constant voltage output, and this superposition operation and the detection of the charging current are grounded to the bottom potential. By carrying out on the side, it is possible to reduce the cost by eliminating photoisolation for insulation .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, there is provided a high-voltage power supply device for electrophotography, wherein a photoconductor, a corona for corona discharge disposed opposite to the photoconductor, and a DC voltage having a constant current are applied to the corotron. A first high-voltage power supply; and a second high-voltage power supply that applies a constant DC high voltage to the conductor portion of the photoconductor to obtain a reference potential of the photoconductor. Grounding the low-potential side of the second high-voltage power supply, connecting a resistor between the output side of the second high-voltage power supply and the ground, and the absolute value of the output current value of the first high-voltage power supply and the resistance value of the resistor Is made lower than the absolute value of the output voltage of the second high-voltage power supply, so that photoisolation can be eliminated.
[0014]
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
[0015]
1 is a transformer, which includes a primary winding 31 and a secondary winding 32. 33 is a control circuit for controlling and driving the transformer 30, 34 is a diode for rectifying the AC high voltage generated in the secondary winding 32, 35 is a smoothing capacitor, and 36 is a detection resistor for detecting an output current. The high-voltage power supply is configured.
[0016]
Reference numeral 37 denotes a transformer, which includes 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 a diode for rectifying the AC high voltage generated in the secondary winding 39, 43 is a smoothing capacitor, 44 is a bypass resistor, 45 is smoothing the AC generated in the tertiary winding 40. , A smoothing capacitor, 47 is a variable resistor, and adjusts the voltage generated in the transformer 37. The second high-voltage power source is configured with the above-described items. 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.
[0017]
Next, the operation will be described. The second high-voltage power supply is a constant voltage power supply for causing the photosensitive member 49 to have a potential difference from the ground, and the voltage is detected 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 stabilizing plate of the corotron 48 and the photosensitive member 49, 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 by the same ground, the voltage detected by the detection resistor 36 is fed back to the control circuit 33, and constant current control of the first high-voltage power supply becomes possible.
[0018]
【The invention's effect】
As described above, the present invention relates to a corona for corona discharge disposed opposite to a photoconductor, a first high-voltage power source for applying a constant-current DC high-voltage to the corotron, and a constant-voltage DC to a conductor portion of the photoconductor. In an electrophotographic apparatus composed of a second high-voltage power source that applies a high voltage and uses it as a reference potential of the photoreceptor, constant current control is performed without photoisolating the output current of the first high-voltage power source. 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.
44 Bypass resistor 48 Corotron 49 Photoconductor

Claims (1)

A photoconductor, a corotron for corona discharge disposed opposite to the photoconductor, a first high-voltage power source for applying a constant-current DC voltage to the corotron, and a constant-voltage direct current on a conductor portion of the photoconductor A detection resistor connected to a low-potential side output of the first high-voltage power supply, and a low-potential side output of the second high-voltage power supply. Is connected to the high potential side output of the first high voltage power source and the high potential side output of the second high voltage power source is connected to the conductor portion of the photosensitive member. By connecting a bypass resistor between the output and the low-potential side output of the second high-voltage power supply, the absolute value of the output current value flowing through the photoconductor, the corotron, and the bypass resistor by the first high-voltage power supply and the The product of the resistance value of the bypass resistor That the bypass voltage value said second high voltage power supply so as to be lower than the absolute value of the DC high constant voltage, wherein the constant voltage output winding voltage in the DC high voltage the second high voltage power supply It is obtained by superimposing a bypass voltage value, and the output side winding is detected in accordance with the detection of the output voltage while detecting the output voltage of the second high voltage power supply by the detection circuit in the second high voltage power supply . A high voltage power supply apparatus characterized in that the second high voltage power supply output voltage is made constant by superimposing the output side winding voltage and the bypass voltage value after adjusting the line voltage .

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