JPS6013433A - 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 the commercial AC power supply into low-voltage DC power through a low-voltage transformer and rectifier circuit, and then supplies the sequence control circuits, lamps, and solenoids. At the same time, the DC output was 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 depends on the changes in the low voltage power supply and high voltage power supply.
Since the output is multiplied by the conversion efficiency, there is a significant drop in energy efficiency, and the drive circuits for the low-voltage and high-voltage transformers are duplicated, which increases the number of parts, resulting in larger equipment and higher costs. did.

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

FIG. 1 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 the rectifier circuit 2, and 3 is a low voltage inverter transformer 4 connected to the output side of the rectifier circuit 2. A control circuit Wl-W3 is a secondary winding 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 rectified output of the rectifier circuit 6, which receives the output of the secondary winding W2 as input, is output to a terminal 12.13, and a voltage of approximately 24 V is applied to a sequence control circuit (not shown), a lamp, a solenoid, etc. connected to the terminal. Supplies low voltage 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 kept at a constant voltage by the constant voltage characteristics of the control circuit 3 and the high-voltage inverter transformer itself, and this constant voltage is applied to the terminals 10.11. Supplied to a high voltage circuit such as a charger (not shown) connected to the

In the non-embodiment, a relay is used as the switch 5, and the switch 5 is opened and closed by a sequence control signal.

FIG. 2 is an external perspective view of an embodiment of the present invention, and FIG. 3 is a longitudinal sectional view thereof. In FIG. 2.3, a bobbin 18 around which a primary coil 17 of a low-voltage inverter transformer 4 is wound is fitted into one of insulating cylinders 15 and 16 erected on the surface of a substrate 14. A bobbin 20 on which secondary coils W1, W2, and W3 are wound is fitted on the outside of the bobbin. Moreover, a bobbin around which the primary coil 21 of the high voltage inverter transformer 8 is wound around the other cylindrical body 16? A bobbin 24 having a secondary coil 23 wound thereon is fitted on the outside of the bobbin. Lead terminals 4a and 8a of the transformer 4.8 are provided protruding from the back surface of the substrate 14. Secondary coil 2 of the above high voltage inverter transformer
3 are connected to rectifiers 9a to 9d constituting the high voltage rectifier circuit 9.

19 partitions a hole 25.26 into which the cylindrical body 15.16 fits, and a bobbin 18.20 of the low-voltage inverter transformer 4 and a bobbin 22.24 of the high-voltage inverter transformer 8 to increase insulation against social gatherings. Partition recess 27 for
As shown in FIG. 3, each bobbin and rectifier are covered, and an epoxy-based highly insulating resin 28 is vacuum injected and dried and integrated. Reference numeral 29.30 denotes an iron core inserted into the cylindrical body 15.16.

As detailed above, the present invention connects the secondary winding of the low-voltage inverter transformer and the primary winding of the high-voltage inverter transformer, so there is no need for any drive circuit on the primary side of the high-voltage inverter transformer. Therefore, switching and other losses in the drive circuit can be eliminated and power conversion can be made highly efficient.

Further, since there is no noise caused by switching, heat generation due to switching loss, etc., and the number of parts is reduced, reliability can be significantly increased, and miniaturization and cost reduction can be achieved.

In addition, the low-voltage inverter transformer and the high-voltage inverter transformer are housed in the same case, and the interior of the case is injected and filled with highly insulating resin to integrate the whole, so each component is compliant with safety regulations. This has the effect of making the power supply device much smaller by reducing the insulation distance and allowing it to be mounted closely.

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 easily possible to stabilize the output of the secondary winding W1 or the output of the high voltage inverter transformer 8 itself.

In addition to the rectifiers 9a to 9d that constitute the high voltage rectifier circuit 9, circuit components that share a common ground with the input commercial power supply, which is called a primary circuit due to safety standards, are housed in the case 19, and are filled with high insulation. By integrating the parts with a material, the insulation distance can be shortened and the device can be made more compact.

The illustrated example shows the primary coil and 2 of the low voltage inverter transformer 4.
Although the subsequent coils are wound on separate bobbins 18, 20, they may be on the same bobbin.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the power supply system of the present invention, FIG. 2 is an external perspective view of the power supply device of the present invention, and FIG. 3 is a longitudinal sectional view thereof. 4 is a low voltage inverter transformer, 8 is a high voltage inverter transformer, 19 is a case, and 28 is a high insulation material.

Claims (1)

[Claims] (1) A first transformer that has a plurality of secondary windings and supplies low-voltage output to a low-voltage circuit, and one of the secondary @ wires and the primary @ wire of the first transformer is connected to supply a high voltage to the high-voltage circuit. 1. A power supply device comprising: a giS2 transformer that supplies an output; and a case housing both transformers is filled with an insulating resin to integrate the whole.