JPH0650016Y2 - High voltage stabilized power supply circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-voltage stabilized power supply circuit, and more particularly to a high-voltage stabilized power supply circuit for supplying a constant high voltage to a load energized by a DC high voltage. Power supply circuit.

Referring to FIG. 1, a prior art high voltage stabilized power supply circuit has a primary winding 2 connected to an AC power supply 1 and a plurality of (three shown) secondary windings 3, 4, and 5. A power transformer 6 is provided. The secondary winding 3 is a high voltage winding for applying a constant high voltage to the load 7 with a direct current. One terminal of the load 7 is grounded. In order to convert AC high voltage to DC high voltage,
A rectifying / smoothing circuit 10 including a diode 8 and a capacitor 9 is connected to the secondary winding 3. A transistor for controlling the current provided between the positive high voltage lines 11 and 12 on the side opposite to the ground side in order to stabilize the high DC voltage converted by the rectifying and smoothing circuit 10. A comparator circuit 14 is provided for detecting the voltage applied to the load 7 and the reference voltage and applying an output to the transistor 13 so as to eliminate the fluctuation voltage according to the fluctuation of the voltage applied to the load 7. A low voltage is applied to the comparison circuit 14 from the secondary winding 4 and the rectifying / smoothing circuit 15 via lines 16 and 17, respectively. The midpoint 18 of the rectifying / smoothing circuit 15 is connected to the line 12. That is, the secondary winding 4 and the rectifying / smoothing circuit 15
The power supply 19 configured by means of is a floating power supply biased by the high voltage on line 12. With such a configuration, a constant high DC voltage is applied to the load 7. However, since the power supply 19 is a floating power supply biased by the high voltage of the line 12, the power supply 19 is supplied to another load such as a resistor or an active element (not shown) to be powered by the low voltage near the ground. It cannot be used as a power source. Therefore, the power supply to the other load must be constructed using the secondary winding 5 or another power transformer. Moreover, the power supply to other loads cannot be used as the power supply to the comparison circuit 14. Therefore, the circuit becomes complicated and the configuration becomes large.

An object of the present invention is to solve the above technical problem and to provide a high voltage stabilized power supply circuit that can share a power supply for a comparison circuit and a power supply for another load.

The present invention is a power supply transformer 22 having an AC power supply 21, a primary winding 23 connected to the AC power supply 21, a high voltage secondary winding 24, and a low voltage secondary winding 25, and a high voltage High-voltage rectifying / smoothing circuit 28 for rectifying and smoothing the output of the secondary winding 24 for low voltage, and rectifying and smoothing the output of the low-voltage secondary winding 25 for low voltage in which the low potential side terminal is grounded. The rectifying / smoothing circuit 35, the first resistor 52 whose one end is grounded, the high-potential-side terminal 37 of the low-voltage rectifying / smoothing circuit 35, and the other end of the first resistor 52 are coupled in the reverse direction. Zener diode 51, terminal 29 on the high potential side of rectifying / smoothing circuit 28 for high voltage, first resistor 52, and connection point of zener diode 51
It is connected in series between the transistor 50 interposed between the high voltage side rectifying and smoothing circuit 35 and the high potential side terminal 37 of the low voltage rectifying and smoothing circuit 35 and the low potential side terminal 30 of the high voltage rectifying and smoothing circuit 28. A plurality of second resistors 55, 56 for voltage division, a high potential side terminal 37 of the low-voltage rectifying and smoothing circuit 35, and the ground are connected to be energized and connected to the first node of the connection point 53. One voltage and a second voltage divided by the second resistors 55 and 56 are applied, and the voltage difference between the first voltage and the second voltage is applied to the control terminal of the transistor 50. 50 is a high voltage regulated power supply circuit characterized in that it includes such a comparison circuit 54 which increases the current when the second voltage drops.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is an electric circuit diagram showing a basic structure of the present invention. The AC power supply 21 is connected to and removed from the primary winding 23 of the power supply transformer 22. The power transformer 22 includes a secondary winding 24 for high voltage and a secondary winding 25 for low voltage. The secondary winding 24 has a diode 26 for rectification and a capacitor for smoothing.
A rectifying / smoothing circuit 28 composed of 27 is connected in parallel. Line 29 is connected to the connection point between diode 26 and capacitor 27, and line 30 is connected to the connection point between capacitor 27 and secondary winding 24.
Are connected. Therefore, a high DC voltage is derived between the lines 29 and 30. The potential of line 29 is higher than that of line 30. A constant high voltage, for example 300V, is grounded at one terminal.
Are connected. A capacitor 41 is connected in parallel to the load 31.

A rectifying / smoothing stabilizing circuit 35 is connected to the secondary winding 25.
The secondary winding 25 and the rectifying / smoothing stabilizing circuit 35 constitute a low voltage stabilizing power supply circuit 36. One terminal of the output of the rectifying and smoothing / stabilizing circuit 35 is grounded, and the other terminal is a line.
37 is connected. Between the line 37 and the ground, a constant low voltage having a small absolute value, for example, 32 V, is derived as a direct current. Therefore, the potential of the line 37 is + 32V.

In order to make the voltage applied to the load 31 a constant high voltage,
In order to apply the voltage from the low voltage regulated power supply circuit 36 to other loads such as resistors and active elements (not shown) to which a constant low voltage is applied, the collector of the transistor 32 as a current control element is provided in the line 30. Are connected. The emitter of the transistor 32 is grounded via a zener diode 33, which is reverse-directionally coupled. Therefore, rectifying and smoothing circuit
A series circuit including a load 31 and a transistor 32 is connected to 28. The breakdown voltage of the Zener diode 33 is a constant voltage of, for example, 16V. Transistor 3
The output of the comparison circuit 34 having an amplifying function is given to the base which is the second control terminal. Comparator circuit 34 is implemented, for example, by an operational amplifier, and is powered with a voltage between line 37 and ground. A resistor 38 is connected between the line 37 and the Zener diode 33. A common connection point 42 between the resistor 38, the Zener diode 33 and the emitter of the transistor 32 is connected to the inverting input of the comparison circuit 34. Connection point 42
The potential of is a constant + 16V. Therefore, the comparison circuit 34
A constant reference voltage of 16V is applied to the inverting input of.

A series circuit including a variable resistor 39 and a resistor 40 is connected between the line 29 and the ground. A connection point 43 between the variable resistor 39 and the resistor 40 is connected to the non-inverting input of the comparison circuit 34. Therefore, a voltage obtained by dividing the voltage corresponding to the voltage applied to the load 31 is applied to the non-inverting input. Variable resistor 39
By adjusting the resistance value of the
300V, that is, the voltage applied to the load 31 is 300V, and the potential of the connection point 43 is set near the reference voltage.

The comparator circuit 34 amplifies the differential voltage between the inverting input and the non-inverting input, and outputs it to the base of the transistor 32 with a voltage obtained by adding + 16V which is an intermediate value of the voltage between the line 37 and the ground. Therefore, the transistor 32 controls the current near the ground potential.

When the potential of the + 300V line 29 approaches OV from the positive to the negative direction, that is, when the absolute value of the voltage applied to the load 31 tends to decrease, the potential of the connection point 43 changes from the positive to the negative reference voltage. Get away from. The potential at node 42 remains constant at + 16V. Therefore, the output from the comparison circuit 34 increases the current flowing from the emitter of the transistor 32 to the collector, and the potential of the line 29, that is, the load 31.
The voltage applied to is kept constant.

When the potential of the + 300V line 29 tends to move further away from OV in the negative to positive direction, that is, when the absolute value of the voltage applied to the load 31 tends to increase, the potential of the connection point 43 changes from the negative to the positive direction. Close to the reference voltage. The potential at node 42 remains constant at + 16V. Therefore, the comparison circuit 34
Due to the output from, the current flowing from the emitter of the transistor 32 to the collector is reduced, and the potential of the line 29, that is, the voltage applied to the load 31 is kept constant. Therefore, a constant high voltage is always applied to the load 31. Note that the other loads are energized from the low voltage regulated power supply circuit 36 at a constant low voltage between the line 37 and ground.

FIG. 3 is a specific electric circuit diagram of an embodiment of the present invention, in which parts corresponding to those of the structure shown in FIG. 2 are designated by the same reference numerals. It should be noted in this embodiment that the line 30 having a lower potential than the line 29 is connected to the other terminal of the load 31 to which a constant high voltage, for example, 300 V, to which one terminal is grounded, should be applied. is there. The collector of the transistor 50 as a current control element is connected to the line 29. Between line 37, which has a constant voltage, for example 32V, and ground, a series circuit consisting of a backward-coupled Zener diode 51 and a resistor 52 is connected. The breakdown voltage of the Zener diode 51 is a constant voltage of 16V, for example.
The emitter of the transistor 50 is connected to the connection point 53 between the Zener diode 51 and the resistor 52. The potential of the connection point 53 is
It becomes a constant + 16V. This connection point 53 is connected to the inverting input of a comparison circuit 54 which has an amplifying function and is powered by the voltage between line 37 and ground. Therefore, a constant reference voltage of 16V is applied to the inverting input of the comparison circuit 54.

Between line 37 and line 30, resistor 55 and variable resistor
A series circuit consisting of 56 is connected. Resistor 55 and variable resistor 56
A connection point 57 with is connected to the non-inverting input of the comparison circuit 54. Therefore, a voltage obtained by dividing the voltage corresponding to the voltage applied to the load 31 is applied to the non-inverting input. By adjusting the resistance value of the variable resistor 56, the potential of the line 30 is set to −300V, that is, the voltage applied to the load 31 is set to 300V, and the potential of the connection point 57 is set near the reference voltage.

The comparator circuit 54 amplifies the differential voltage between the inverting input and the non-inverting input, and outputs it to the base of the transistor 50 at a potential obtained by adding + 16V which is an intermediate value between the line 37 and the ground. Therefore, the transistor 50 controls the current near the ground potential.

When the potential of the −300V line 30 is going to be further away from OV in the positive to negative direction, that is, when the absolute value of the voltage applied to the load 31 is about to increase, the potential of the connection point 57 is changed from the positive to the negative direction. Approach the reference voltage. The potential at node 53 remains constant at + 16V. Therefore, the comparison circuit 54
Due to the output from, the current flowing from the collector of the transistor 50 to the emitter is reduced, and the potential of the line 30, that is, the voltage applied to the load 31 is kept constant.

When the potential of the −300V line 30 approaches OV from the negative direction to the positive direction, that is, when the absolute value of the voltage applied to the load 31 tends to decrease, the potential of the connection point 57 is referenced from the negative direction to the positive direction. Get away from voltage. The potential at node 53 remains constant at + 16V. Therefore, the output from the comparison circuit 54 increases the current flowing from the collector of the transistor 50 to the emitter, and the potential of the line 30, that is, the load 31.
The voltage applied to is kept constant. Therefore load 31
A constant high voltage is always applied to.

Further, the transistor 50 may be a field effect transistor. Further, the rectifying / smoothing circuits 28 and 35 may include a full-wave rectifying circuit, a full-wave voltage doubler rectifying circuit, and the like.

As described above, according to the present invention, the low-voltage rectifying and smoothing circuit 35
The low potential side terminal of is connected to the ground, and the high potential side terminal 37 of this low voltage rectifying and smoothing circuit 35 is connected to a zener diode.
51 is connected, the transistor 50 is connected to a connection point 53 between the Zener diode 51 and the first resistor 52 which is grounded, and the comparison circuit 54 uses the low voltage rectifying and smoothing circuit 35 to energize the power. The comparison circuit 54 includes the connection point 53
Of the low voltage rectifying / smoothing circuit 35 and the low potential side terminal 30 of the high voltage rectifying / smoothing circuit 28 for voltage division. The divided voltage is given by the second resistors 55, 56 of the low resistance rectifying / smoothing circuit 35, so that the low voltage rectifying / smoothing circuit 35 can be used as a power source for other loads. A power supply can be used to power the comparison circuit 54. The power transformer 22 is composed of a high voltage secondary winding 24 and a low voltage secondary winding.
25, and other secondary windings are not required, and the high voltage secondary winding 24 and the low voltage secondary winding 25 allow high voltage and low voltage DC voltage. Therefore, the size is reduced and the cost is reduced, the circuit configuration is simplified, and the space is small.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a prior art, FIG. 2 is an electric circuit diagram showing a basic structure of the present invention, and FIG. 3 is an electric circuit diagram of an embodiment of the present invention. 21 …… AC power supply, 22 …… Power transformer, 23 …… Primary winding, 24,25 …… Secondary winding, 28 …… Rectifying and smoothing circuit, 29,30…
… Line, 31 …… Load, 32,50 …… Transistor, 33,51
...... Zener diode, 34,54 …… Comparison circuit, 36 ……
Low voltage stabilized power supply circuit

Claims (1)

[Scope of utility model registration request] 1. An AC power supply 21 and a device 1 connected to the AC power supply 21.
Secondary winding 23, secondary winding 24 for high voltage, secondary winding for low voltage
A high-voltage rectifying / smoothing circuit 28 for rectifying and smoothing the output of the high-voltage secondary winding 24, and a low-voltage secondary winding 25 for rectifying and smoothing the output of the low-voltage secondary winding 25. A low-voltage rectifying / smoothing circuit 35 whose potential-side terminal is grounded, a first resistor 52 whose one end is grounded, a high-potential-side terminal 37 of the low-voltage rectifying / smoothing circuit 35, and a first resistor 52. A Zener diode 51 that is reverse-directionally coupled to the other end, a terminal 29 on the high potential side of the high-voltage rectifying and smoothing circuit 28, a connection point between the first resistor 52 and the Zener diode 51.
It is connected in series between the transistor 50 interposed between the high voltage side rectifying and smoothing circuit 35 and the high potential side terminal 37 of the low voltage rectifying and smoothing circuit 35 and the low potential side terminal 30 of the high voltage rectifying and smoothing circuit 28. A plurality of second resistors 55, 56 for voltage division, a high potential side terminal 37 of the low-voltage rectifying and smoothing circuit 35, and the ground are connected to be energized and connected to the first node of the connection point 53. One voltage and a second voltage divided by the second resistors 55 and 56 are applied, and the voltage difference between the first voltage and the second voltage is applied to the control terminal of the transistor 50. A high voltage regulated power supply circuit 50, characterized in that it includes such a comparison circuit 54 which increases the current when the second voltage drops.