JPS6013432A - Power source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply device, and particularly to a power supply device effective for application to electronic image forming apparatuses that require a low-voltage power source and a high-voltage power source, such as electronic copying machines and electronic printers. It is.

Conventionally, in this type of electronic image forming apparatus, the low-voltage power supply for sequence control first converts a commercial AC power supply into low-voltage DC through a low-voltage transformer and rectifier circuit, and then supplies the sequence control circuit, lamp, and solenoid. At the same time, the direct current output is supplied to the primary side of a high voltage transformer of a high voltage power source for power supplying a charger via an inverter circuit. For this reason, the high voltage output is multiplied by the conversion efficiency of the low voltage power source and the high voltage power source, resulting in a significant drop in energy efficiency.Also, the drive circuits for the low voltage and high voltage transformers are doubled, which increases the number of parts. This, in turn, led to an increase in the size of the equipment and an increase in costs.

The present invention has been proposed in view of the above, and aims to improve the power conversion efficiency and obtain a highly reliable power supply device with a small number of parts.

The drawing is a circuit diagram showing an embodiment of the present invention, in which 1 is a commercial AC power supply connected to the input side of a rectifier circuit 2, and 3 is a circuit diagram for driving and controlling a low voltage inverter transformer 4 connected to the output side of the rectifier circuit 2. Control circuits W1 to W3 are secondary windings of the low voltage inverter transformer 4.

The control circuit 3 is a switching transistor oscillation circuit,
Including PWM, (pulse width modulation) circuit, error amplifier, etc.
The rectified output of the rectifier circuit 7 which inputs the output of the secondary winding W3 is compared with a reference value, and the energization time of the low voltage inverter transformer 4 is controlled so that the rectified output becomes constant.

The rectifier output of the rectifier circuit 6 which inputs the output of the secondary winding vAW2 is outputted to the terminal 12.13, and the voltage of approximately 24V is applied to the low voltage of the sequence control circuit (not shown), lamp, solenoid, etc. connected to the terminal. supply to the circuit.

"-The secondary winding W1 is an electrical or mechanical switch 5
It is connected to the primary winding of the high voltage inverter transformer 8 via. The rectified output of the rectifier circuit 9 connected to the secondary side of the high voltage inverter transformer 8 is maintained at a constant voltage by the constant voltage characteristics of the control circuit 3 and the high voltage inverter transformer 8 itself, and this constant voltage is transferred to the terminal 10. .11 is connected to a high voltage circuit such as a charger (not shown).

In the unembodied example, a relay is used as the switch 5, and the switch 5 is opened and closed in response to a sequence control signal.

”-As stated above, the present invention is a low voltage inverter transformer.
Since the secondary winding and the primary winding of the high-voltage inverter transformer are connected, there is no need to turn off the primary side drive circuit of the high-voltage inverter transformer, eliminating switching and other losses in the drive circuit and improving power conversion. Can be made highly efficient. Further, there is no noise caused by switching, heat generation due to switching loss, etc., and the number of parts is reduced, so reliability can be significantly improved, and miniaturization and cost reduction can be achieved.

Note that the high-voltage inverter transformer 8 may have a plurality of secondary windings to supply power to a plurality of chargers having different charging voltages.

In the above embodiment, the control circuit 3 is composed of a switching transistor oscillation circuit, a PWM circuit, and an error amplifier, which implicitly indicates that it is a passive inverter.
By adding a feedback winding input to the base of the switching transistor to the inverter transformer, it is possible to simplify the automatic inverter by removing the oscillation circuit.

The stabilized output of the low voltage inverter transformer 4 is connected to the secondary winding W.
It is also possible to use the rectified output of the secondary winding W2 instead of the rectified output of the secondary winding W2. Therefore, it is possible to easily stabilize the output of the secondary winding ill or the output of the high voltage inverter transformer 8 itself.

[Brief explanation of drawings]

The drawing is a circuit diagram showing one embodiment of the present invention. 1 is a commercial AC power supply, 2 is a rectifier circuit, 3 is a control circuit, 4 is a low voltage inverter transformer, 5 is a switch, 6.7 is a rectifier circuit, 8 is a high voltage inverter/transformer, 9 is a high voltage rectifier circuit, 10 - 13 is an output terminal. 9-

Claims (1)

[Claims] (1) A first transformer having a plurality of secondary windings and supplying low voltage output to a low voltage circuit; one of the secondary windings of the first transformer and the primary winding are connected to supply a high voltage to the high voltage circuit; and a second transformer that supplies an output.