JPH04125064A - Power source device - Google Patents

Abstract

PURPOSE:To drive a primary side of one transformer by a constant voltage, to control the voltage of the primary side of the other transformer, and to reduce in size by connecting a first converter for outputting a positive or negative polarity and a second converter for outputting the other polarity in series at the secondary sides of the transistors. CONSTITUTION:A PWM circuit 1 of control driving means is so controlled that, if a voltage to be supplied to a load is set to zero, (output voltage V+ of a converter transformer T1 = output voltage V- of a second converter transformer T2 is obtained. The circuit 1 is so controlled that, if the voltage to the load is set to positive, the V+>V- is obtained, while if it is set to negative, the V+<V- is obtained, the negative voltage is varied to control the output from the positive voltage to the negative voltage by a control signal S1. Thus, the output can be controlled merely by controlling one converter transformer to reduce in size an apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply device for obtaining high voltages of both positive and negative polarities in a high voltage power supply for an electrophotographic copying machine or printer.

(Prior Art) Conventionally, a power supply device for obtaining high voltage with both positive and negative polarities is configured as shown in FIG.

In the figure, T1 is a converter transformer, D3 is a diode, C3 is a capacitor, Tri is a transistor, and IA
, IB is a PWM (pulse width modulation) circuit.

The first converter circuit A is a first converter transformer T
1. Transistor Tri, diode D3. The second converter circuit B is also composed of a converter transformer T2゜transistor Tr2. Diode D4. It consists of a capacitor C4.

The conventional power supply device includes the first converter circuit A, a transistor Tri for driving the first converter circuit A, and a PWM circuit IA for controlling and driving the transistor Tri.
It is composed of a second converter circuit B having a similar configuration and a PWM circuit IB that controls and drives the second converter circuit B.

Next, the operation of this device will be explained.

The output of converter transformer T1 is connected to diode D3. It is rectified and smoothed by capacitor C3 to generate a positive high voltage. Note that the transistor Tri is switched by the output of the PWM circuit IA, and drives the converter transformer T1. Similarly, the output of converter transformer T2 outputs a negative high voltage through diode D4° and capacitor C4.

Note that the transistor Tr2 drives the converter transformer T2 with the output of the PWM circuit IB.

Also, resistor R4 detects the current flowing to the load, and resistor R5
, R6, the voltages shifted to positive polarities are input to each PWM circuit IA, IB, respectively.

Sl and S2 are control signals from a controller (not shown), Sl is a positive output control signal, and the positive output voltage is determined by the voltage of the control signal S1. In addition, the control signal S
Similarly, 2 is a negative output control signal, and a negative output voltage is determined. When outputting a positive voltage, the control signal S2 is
Further, when outputting a negative voltage, the control signal S1 is input as a signal to turn off the output of each PWM circuit IA, IB.

As described above, it operates to output high voltages of both positive and negative polarities depending on the signal voltages of the control signals Sl and S2.

[Problem to be solved by the invention]

However, the conventional example described above requires a circuit for controlling each of the positive and negative high-voltage power supplies, which has the drawback of complicating the circuit and increasing cost.

The present invention has been made to solve the problems of the conventional example as described above, and aims to provide a power supply device that is downsized by omission.

(Means for Solving the Problems) Therefore, in the present invention, in a power supply device that generates an output of both positive and negative polarities, a first converter circuit that generates an output of one of the positive and negative polarities, and a first converter circuit that generates an output of one of the positive and negative polarities, and a second converter circuit that generates a pole output; a control drive means that voltage-controls and drives the primary side of a transformer included in the first converter circuit; and drive means for driving the primary side with a constant voltage, the secondary sides of the transformers of each of the converter circuits are connected in series with each other, and a desired output is supplied from both ends by the control drive means. Use as a power supply device.

Further, by further providing another secondary winding in the transformer of the second converter circuit, and controlling the primary side of the transformer of the second converter circuit according to the output of this secondary winding, the second The above object is achieved by providing a power supply device characterized by constant voltage control of the output of the converter circuit.

[Effect]

With the above configuration, the power supply device according to the present invention includes a first converter circuit that controls and drives the primary side by the control drive means and generates a positive or negative output, and a first converter circuit that controls and drives the primary side by the control drive means, and By using the second converter circuit which generates a constant output from the other rod without changing the output from the other rod, it is possible to generate desired outputs of both positive and negative polarities with one control circuit, that is, the control drive means.

Further, another constant voltage controlled low voltage output can be supplied from a secondary winding that is separately provided in the transformer of the second converter circuit that supplies a constant voltage.

〔Example) Hereinafter, the present invention will be explained based on examples according to the drawings.

(First Embodiment) FIG. 1 shows a circuit diagram of a power supply device according to a first embodiment of the present invention. Components that are the same (equivalent) to those of the conventional example shown in FIG. 3 are denoted by the same reference numerals, and redundant explanation will be omitted.

In the figure, 1 is a PWM circuit which is a control drive means of the first converter circuit A, and 3 is an OSC (oscillation) circuit which is a drive means of the second converter circuit B.

The power supply device of this embodiment includes a first converter circuit A that generates a positive voltage, a PWM circuit 1 that drives the next side of a transformer T1 of this converter circuit under voltage control, and a second converter circuit B that generates a negative voltage. The secondary side of the transformer TI, T2 of each converter circuit is connected to a resistor R2.
to supply the desired positive or negative polarity output from both ends. Conventionally, the first and second converter circuits A and B are PWM circuits IA.

The voltage was controlled by each IB, but in this example, the second
Converter circuit B is configured to perform constant voltage control using an O3C circuit 3 having a simple configuration, and only the first converter circuit A is voltage controlled using a PWM circuit 1 to supply outputs of both positive and negative polarities.

Next, the operation will be explained.

The voltage generated by the first converter transformer T1 is controlled by the PWM circuit 1 as in the conventional example shown in FIG. The voltage at this time is assumed to be V+.

Since the transistor Tr2 is driven by the O3C circuit 3, the second converter transformer T2 always generates a constant output while the power is on. Assuming that the voltage at this time is ■-, if you want to make the voltage supplied to the load zero, control the PWM circuit 1, which is the control drive means, so that the voltage of both types is equal to V, = V-, and make it positive. If V, >V
- and V, the voltage is controlled to be greater than the V- voltage,
When setting the negative polarity, the output is controlled by the control signal S1 from the positive voltage to the negative voltage by controlling the PWM circuit 1 and changing the negative voltage so that V<V- and the V+ voltage are smaller than the V- voltage. It becomes possible to do so.

As explained above, the output can be controlled by simply controlling one of the two sets of converter transformers that generate outputs of both positive and negative polarities, so that the size of the device can be reduced accordingly.

(Second Embodiment) FIG. 2 shows a circuit diagram of a power supply device according to a second embodiment of the present invention. Note that the same (equivalent) components as in the conventional example shown in FIG. 3 and the first embodiment shown in FIG.

In the figure, the first converter circuit A and its control drive means 1 have the same structure as in the first embodiment, and the explanation thereof will be omitted. D6 is a bridge diode, and C6 is a capacitor, which rectify and smooth the line input and input it to the converter transformer T3 of the second converter circuit B. The converter transformer T3 is provided with three windings: a winding nl for supplying power, a high voltage output winding n2, and a low voltage output @line n3.

The output of the winding n3 is rectified and smoothed by a diode D5 and a capacitor C5 to provide a low voltage output. Further, the low voltage output is inputted to a driving means 6 consisting of a voltage detection circuit 4, a photocoupler 5, and a PWM circuit 2.

The PWM circuit 2 drives the converter transformer T3 by switching the transistor Tr2, and performs constant voltage control so that the low voltage output becomes 24V.

As explained above, by adding the secondary winding n3 to the converter transformer T3 on the constant voltage control side, it is possible to perform constant voltage control of other low voltage outputs and the converter circuit.

〔Effect of the invention〕

As explained above, according to the present invention, the first converter circuit that outputs one of the positive or negative poles and the second converter circuit that outputs the other pole are connected on the secondary side of each transformer. By connecting the transformers in series, using a drive means that drives the primary side of one transformer with a constant voltage, and using a control drive means that controls the voltage on the primary side of the other transformer, we are able to obtain control outputs of both positive and negative polarities. The control drive means of one converter circuit is reduced to a drive means, and both positive and negative outputs can be controlled with only one control drive means of the other converter circuit, and operability is also improved.

In addition, when multiple outputs are required such as in electrophotographic equipment, another secondary winding can be added to the transformer of the constant voltage control converter circuit to increase other low voltage outputs and reduce the size of the circuit. can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a power supply device according to a first embodiment of the present invention, FIG. 2 is a circuit diagram of a power supply device according to a second embodiment of the present invention, and FIG. 3 is a circuit diagram of a power supply device of a conventional example. It is a circuit diagram. In addition, in the figures, the same reference numerals indicate the same (equivalent) components. 1------PWM circuit (control driving means) 3------
- OSC circuit (driving means) 6----- Drive means TI, T2. T3 axis...Converter transformer A...
...First converter circuit B----Second converter circuit n11 n2.
n3++e++e winding

Claims (2)

[Claims] (1) In a power supply device that generates an output of both positive and negative polarities, a first converter circuit that generates an output of one of the positive and negative polarities, and a second converter circuit that generates an output of the other polarity; comprising control driving means for voltage-controlled and driving the primary side of the transformer provided in the first converter circuit, and driving means for driving the primary side of the transformer provided in the second converter circuit at a constant voltage, A power supply device characterized in that the secondary sides of the transformers of each of the converter circuits are connected in series with each other, and a desired output is supplied from both ends thereof by the control drive means. (2) Further providing another secondary winding in the transformer of the second converter circuit described in paragraph 1, and controlling the primary side of the transformer of the second converter circuit according to the output of this secondary winding. A power supply device characterized in that the output of the second converter circuit is controlled at a constant voltage.