Power supply unit and image forming apparatus

Abstract

To minimize an increase in cost to reduce a detection error in a power supply device that detects DC current at a position where inflow of AC voltage occurs.SOLUTION: A power supply device α applies a voltage obtained by superimposing DC voltage and AC voltage to an electrifying member 18 that electrifies an image carrier, and the power supply device comprises: an AC voltage generation unit 810 that generates AC voltage; a DC voltage generation unit 820 that generates DC voltage; a DC current detection unit 840 that is provided on a side of an output end of the DC voltage generation unit 820, and detects output DC current flowing into the image carrier 40; and inflow reduction means 850 that reduces inflow of AC current into the DC current detection unit.SELECTED DRAWING: Figure 4

Claims

1. A power supply device that applies a voltage consisting of a DC voltage and an AC voltage superimposed on a charging member that charges an image carrier, An AC voltage generation unit that generates the aforementioned AC voltage, A DC voltage generation unit that generates the aforementioned DC voltage, A DC current detection unit is provided on the output terminal side of the DC voltage generation unit to detect the output DC current flowing into the image carrier, The DC current detection unit includes an inverse waveform application unit that applies an inverse waveform of the ripple voltage assumed by the DC current detection unit to the DC current detection unit. power supply.

2. The DC current detection unit is A detection AD converter for detecting the output DC current flowing into the image carrier, The aforementioned detection AD converter includes a current detection element that acts as a resistor, The inverse waveform application unit applies the inverse phase waveform of the ripple voltage to the DC current detection line between the detection AD converter and the current detection element. The power supply device according to claim 1.

3. The inverse waveform application unit outputs a control signal to the AC voltage generation unit to generate the specified AC voltage. The inverse waveform application unit is, A ripple voltage storage unit that stores in advance the ripple waveform generated for each specified AC voltage of the control signal, A calculation unit that, based on the current control signal, anticipates the resulting ripple waveform and calculates the inverse waveform of the anticipated ripple waveform, The system includes a DA converter that generates an inverse waveform of the calculated ripple waveform and outputs it to the DC current detection line. The power supply device according to claim 2.

4. The DC current detection line includes a phase detection unit that detects the phase of the ripple voltage of the output DC current, The inverse waveform application unit outputs the inverse waveform of the calculated ripple waveform to the DC current detection line downstream of the position to which the phase detection unit is connected, in accordance with the phase of the detected ripple voltage. The power supply device according to claim 3.

5. The inverse waveform application unit is, The system further includes a deviation amount storage unit that pre-stores the relationship between the amount of deviation between the detected value and the actual detected value at the measurement point of the ripple voltage generated for each specified AC frequency. The calculation unit, based on the control signal and the stored amount of deviation at the measurement point, assumes a ripple waveform that takes the deviation amount into account and calculates the inverse waveform of the ripple waveform that takes the assumed deviation amount into account. The power supply device according to claim 4.

6. A power supply device that applies a voltage consisting of a DC voltage and an AC voltage superimposed on a charging member that charges an image carrier, An AC voltage generation unit that generates the aforementioned AC voltage, A DC voltage generation unit that generates the aforementioned DC voltage, The system includes a control device that outputs a control signal to the AC voltage generation unit to generate the specified AC voltage, and is connected to the output terminal side of the DC voltage generation unit to calculate the output DC current that flows into the image carrier, The control device is An AD converter is connected to the output terminal side of the DC voltage generation unit and detects the DC current, A ripple voltage storage unit that stores in advance the ripple waveform generated for each specified AC voltage of the control signal, The system includes a calculation unit that, based on the current control signal, anticipates the ripple waveform that will be generated, calculates the inverse waveform of the anticipated ripple waveform, and adds the calculated inverse waveform to the detected DC current including the ripple to obtain the output DC current. power supply.

7. A power supply device according to any one of claims 1 to 6, Image carrier and, A charging member for charging the image carrier, The system includes a control device that calculates the surface potential of the image carrier based on the output DC current. Image forming apparatus.

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