JPH1080158A - Power-supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power-supply apparatus by which a change in an output voltage due to a load change or a power-supply change is prevented effectively by a method in which the peak value of a pulse-shaped signal by a high voltage from a power supply for drive is detected and the voltage of the power supply for drive is changed in such a way that the peak value becomes a constant value. SOLUTION: An impulse power supply 20 generates various power supplies which are required to operate the impulse power supply 20 by a primary power- supply part 21. A drive part 22 drives a high-voltage circuit 23 at a prescribed timing, and an output stabilization part 24 detects the peak value of impulses which are output from the high-voltage circuit 23. In addition, the output stabilization part 24 makes a control voltage CT variable on the basis of the detection result of the peak value, and the voltage of a power supply B1, for drive, which is output from the primary power-supply part 21 is made variable. Thereby, the peak value of the impulses is held by a constant value with reference to a load change and a power-supply change. Thereby, it is possible to effectively prevent a change in an output voltage due to the load change and the power- supply change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a power supply device,
For example, the present invention can be applied to an impulse power supply device used for a knocking test of a cathode ray tube. The present invention detects the peak value of the output voltage and varies the power supply voltage based on the peak value detection result, thereby effectively avoiding the output voltage fluctuation due to the load fluctuation and the power supply fluctuation.

[0002]

2. Description of the Related Art Conventionally, in a cathode ray tube, a knocking test is carried out at the time of shipment from a factory, so that a failure in a market is effectively avoided. That is, this knocking test is a test in which a plurality of cathode ray tubes are connected in parallel, and a high voltage impulse is applied between the electrodes of the cathode ray tubes, thereby scattering dust and burrs on the electrodes. If the dust and the like of the electrodes are scattered by the knocking test, it is possible to effectively avoid the discharge in the tube between the cathode rays in the market.

Therefore, in such a knocking test, a high-voltage impulse is generated by an impulse power supply as shown in FIG. That is, the impulse power supply 1 connects the charge-up capacitor 3 to the primary terminal of the step-up transformer 4 in parallel via the SCR 2. The charge-up capacitor 3 is charged up by the commercial power supply via the diode 7, while the SCR 2 is triggered by the commercial power supply via the resistors 5 and 6, and the power transformer T. Thus, the impulse power supply 1 charges the charge-up capacitor 3 in the negative half cycle of the commercial power supply, and then discharges the charge-up capacitor 3 in the positive half cycle of the commercial power supply. To induce a high voltage.

The secondary terminal of the step-up transformer 4 is connected to a hot side by a coupling capacitor 8 formed by connecting a high-voltage capacitor in series / parallel, and by a plurality of diodes 10 each having a damping resistor 9 connected in parallel. A series circuit is configured to clamp the output voltage of the coupling capacitor 8.

As a result, as shown in FIG. 6, the impulse power supply 1 has a cycle TS of the commercial power supply VS (FIG. 6A).
A high voltage impulse VP of about -80 [kV] (FIG. 6
(B)).

[0006]

However, this type of impulse power supply has a problem in that the output voltage fluctuates due to fluctuations in the power supply of the commercial power supply by rectifying and directly using the commercial power supply. There is also a problem that the output voltage fluctuates greatly due to load fluctuation.

In particular, in the knocking test, when a discharge is caused in one of a plurality of cathode ray tubes to be tested at the same time, a load current sharply increases, so that a prescribed test voltage is not applied to another cathode ray tube, and the other cathode ray tubes are not applied. The knocking test was not substantially performed for the cathode ray tube.

The present invention has been made in view of the above points, and a power supply device for generating this kind of impulse includes:
An object of the present invention is to propose a power supply device that can effectively avoid output voltage fluctuations due to load fluctuations and power supply fluctuations.

[0009]

According to the present invention, a pulse signal having a higher voltage than a driving power supply is generated, a peak value of the pulse signal is detected, and the peak value of the pulse signal is detected. The voltage of the driving power supply is varied so that the value becomes constant.

[0010] The peak value of the pulse signal changes due to load fluctuation and power supply fluctuation. Therefore, by varying the voltage of the driving power supply so that the peak value becomes a constant value based on the peak value detection result, it is possible to effectively avoid fluctuations in output voltage due to load fluctuations and power supply fluctuations.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an impulse power supply according to an embodiment of the present invention. The impulse power supply 20 is provided by the primary power supply unit 21.
Generates various power supplies required for the operation of. The driving unit 22 drives the high voltage circuit 23 at a predetermined timing, and the output stabilizing unit 24 detects the peak value of the impulse output from the high voltage circuit 23. Further, the output stabilizing section 24 varies the control voltage CT based on the peak value detection result to vary the voltage of the driving power supply B1 output from the primary power supply section 21, thereby controlling the load fluctuation and the power supply fluctuation. To keep the peak value of the impulse constant.

The high-voltage circuit 23 has a turns ratio of 1: 100.
A high voltage is generated using the step-up transformer 25 of 0. That is, one end of the primary winding of the step-up transformer 25 is grounded by the capacitor 26, and the driving power supply B1 is input from the primary power supply unit 21 to this one end. Further, in the high-voltage circuit 23, the other end of the primary winding is intermittently grounded by the drive unit 22, so that the driving current intermittently flows into the primary winding.

Further, in the high voltage circuit 23, a coupling capacitor 27 formed by connecting a high withstand voltage capacitor in series / parallel is connected to the secondary winding and the hot side end of the step-up transformer 25, and a damping resistor 29 is connected in parallel. A series circuit of a plurality of diodes 28
It is like clamping the output voltage. As a result, the impulse power supply 20 is driven by the driving unit 2 as shown in FIG.
2 generates a high-voltage impulse output -OUT of about -80 [kV] in a driving cycle T.

The high-voltage circuit 23 includes a step-up transformer 2
5 secondary winding, cold side is connected to one end of the detection winding,
The other end of this detection winding is grounded. Thereby, the high voltage circuit 2
No. 3 is such that even if the discharge noise is superimposed on the impulse or the output waveform is deformed, the peak value of the impulse can be reliably detected through this detection winding.

That is, when the discharge noise is superimposed on the impulse and the output waveform is deformed, it is difficult to stably detect a correct peak value by simply dividing the impulse waveform by resistance. . On the other hand, in this type of step-up transformer 25, the cross-sectional area of the core is S, the length of the magnetic circuit is L, the magnetic permeability is μ, and the number of primary windings is N1.
In other words, the inductance L1 of the primary winding is expressed by the following equation.

(Equation 1)

When a sine wave AC voltage V1 having an angular frequency ω is applied to this primary winding, the phase is delayed by 90 ° and the exciting current I0
Flows to form an alternating magnetic flux φ in the magnetic circuit. This alternating magnetic flux φ is expressed by the following equation.

(Equation 2)

Assuming that the number of turns of the secondary winding wound on the same core is N2 with respect to this primary winding, the electromotive force V2 of this secondary winding is expressed by the following equation.

(Equation 3)

By substituting equation (2) into the equation, the following equation can be obtained.

(Equation 4)

That is, it can be seen that the terminal voltage of the secondary winding changes following the fluctuation of the terminal voltage of the primary winding according to the proportional relationship in which the turns ratio of the step-up transformer 25 is made a proportional constant. As a result, when the secondary winding side terminal voltage changes due to power supply fluctuation and the impulse peak value changes,
Corresponding to this, the peak value detected via the detection winding also changes, indicating that a change in the peak value due to power supply fluctuation can be detected via the detection winding.

On the other hand, the impedance Z
When a load of 2 is connected, a current of I2 = V2 / Z2 flows through the secondary winding, and this current forms a magnetic flux φ2 represented by the following equation in the core.

(Equation 5)

Even if the magnetic flux φ2 is generated as described above, the back electromotive force generated in the primary winding is balanced with the externally applied primary voltage, so that a magnetic flux −φ2 canceling the magnetic flux φ2 is formed. As a result, the current I1 flows through the primary winding. That is, ignoring the exciting current I0,
The relationship of N1I1 = N2I2 is obtained, whereby the relational expression of the following expression can be obtained by setting the impedance on the primary side to Z1.

(Equation 6)

That is, the secondary load fluctuation appears on the primary side using the square value of the turns ratio as a proportional constant, and it can be seen that the change in the impulse waveform due to the load fluctuation can be detected via the detection winding.

Since the step-up transformer 25 is formed so that a high-voltage output can be detected through the detection winding, a magnetic circuit is formed by a farite core having high magnetic permeability and good frequency characteristics. That is, as the number of windings increases, the stray capacitor increases accordingly, and the charge / discharge current of the stray capacitor cannot be ignored. For this reason, the step-up transformer 25 uses a ferrite core having a high magnetic permeability to secure a desired high-voltage output with a small number of turns. Further, the impulse waveform can be correctly detected from the detection winding by effectively avoiding waveform deterioration due to the frequency characteristics of the core.

The high-voltage circuit 23 outputs the detection winding output S2 to the output stabilizing section 24 via a shielded cable so as to effectively avoid mixing of discharge noise and the like. The high voltage circuit 23 divides the impulse output −OUT by resistance and outputs a monitor signal S1 for waveform monitoring.

FIG. 3 is a block diagram showing the driving unit 22. The drive unit 22 sets a repetition cycle T of the impulse output −OUT, and drives the high-voltage circuit 23 according to the repetition cycle T. That is, in the driving unit 22, the reference signal generation circuit 30 generates a reference signal having a frequency of 1.024 [MHz] in the crystal oscillation circuit 31. Further, the reference signal generation circuit 30 converts the reference signal into a frequency divider 3
2 to generate an operation reference signal S3 having a frequency of 2 [kHz].

The repetition cycle setting circuit 33 has a digital switch (S) on the operation panel of the impulse power supply 20.
W) 34 is arranged so that a repetition period T can be set in the digital switch 34. The counter 36 is configured by a programmable counter,
The set value set in the digital switch 34 is set by the set signal ST, and the set value is reset by the reset signal RT. The counter 36 counts the operation reference signal S3 based on the set value and outputs a frequency-divided signal S4. Driving unit 2
2 drives the high-voltage circuit 23 in synchronization with the frequency-divided signal S4, whereby the repetition period T can be set via the digital switch 34.

That is, in the repetition period setting circuit 33, the flip-flop (FF) 37 outputs the frequency-divided signal S
4 is corrected to a duty ratio of 50 [%] and output. The mono-multivibrator (MO) 38 then drives the drive signal S5 in which the signal level rises in a pulse shape in synchronization with the timing at which the signal level of the flip-flop output rises.
Generate

The drive circuit 40 connects the power MOS FET 42 having the source resistor 43 grounded to the primary winding of the step-up transformer 25, and controls the power MOS FET 42 on and off by the drive signal S5 via the resistor 44.
Thus, the drive circuit 40 forms a switching circuit, switches the boosting transformer 25 at the timing of the drive signal S5, and drives the high-voltage circuit 23 according to the repetition cycle T set by the repetition cycle setting circuit 33.

The frequency display circuit 45 is constituted by a frequency counter for counting and displaying the frequency of the drive signal S5, and displays the repetition cycle T set by the repetition cycle setting circuit 33 by the repetition frequency.

FIG. 4 is a block diagram showing the primary power supply section 21 and the output stabilization section 24. Primary power supply 21
Generates various power supplies necessary for driving the impulse power supply 20 from a commercial power supply. At this time, the primary power supply unit 21 inputs commercial power to the power supply circuit 51 through the filter 50,
The filter 50 prevents discharge noise and the like from leaking to the power supply line.

The stabilizing circuit 52 is composed of a voltage stabilizing circuit having a series regulator circuit configuration. A transistor 53 having a resistor 54 connected between a base and a collector is connected to a driving power supply B1 line output from the power supply circuit 51. Insert. The transistor 53 is connected to a base-emitter type transistor 55, and varies the base voltage of the transistor 55 with a control voltage CT via a resistor 56 so that the voltage of the driving power supply B1 can be varied. It has been done. Thus, the stabilizing circuit 52 variably outputs the voltage of the driving power supply B1 such that the control voltage CT is controlled by the output stabilizing unit 24 and the peak value of the impulse output becomes constant.

The output stabilizing section 24 is provided with a digital switch (S) disposed on the operation panel of the impulse power supply 20.
W) 57 allows the peak voltage value of the impulse output -OUT to be set. The digital switch 57 outputs the set value as a 12-bit BCD output, and the digital / analog conversion circuit (D / A) 58 converts the BCD output into an analog value and outputs it. At this time, the digital-to-analog conversion circuit (D / A) 58 converts the BCD output to an analog value so as to output an analog signal with a voltage of 1/100000 of the value set by the digital switch 57. The display circuit 59 is constituted by a digital voltmeter, and detects and displays the output voltage value of the digital / analog conversion circuit 58.

The peak hold circuit 60 receives the output S2 of the detection winding via the coupling capacitor 61 and inputs the output to the parallel circuit of the diode 62 and the resistor 63 whose anodes are grounded. The peak hold circuit 60 inputs the detection winding output S2 to the hold capacitor 65 via the diode 64, and outputs the detection winding output S2 to the hold capacitor 65.
Hold the peak voltage of 2. As a result, the peak hold circuit 60 outputs the impulse output -O via the detection winding.
Detect peak voltage of UT.

In the peak hold circuit 60, an FET 66 is arranged in parallel with the hold capacitor 65, and a reset signal R is supplied to the gate of the FET 66 via a resistor 67.
ST is input. Here, the reset signal RST is
Immediately before the impulse output -OUT falls based on the drive signal S5, the signal is generated in the drive unit 22 so that the signal level rises for a predetermined period. As a result, the peak hold circuit 60 sets the terminal voltage of the hold capacitor 65 to 0 immediately before the impulse output −OUT falls.
The voltage falls to [V], and the peak voltages of successive impulses are sequentially detected.

The operational amplifier circuit 69 is constituted by a voltage follower circuit having input resistors 70 and 71 connected to an inverting input terminal and a non-inverting input terminal.
Is output to the following comparison circuit 74. Note that the operational amplifier circuit 69 is configured to connect the inverting input terminal and the non-inverting input terminal with diodes 72 and 73 to effectively avoid damage due to high voltage input.

In the comparison circuit 74, the operational amplifier circuit 75
Inputs the output signal of the peak hold circuit 60 to the inverting input terminal via the input resistor 76. The operational amplifier circuit 75
Inputs the output signal of the digital-to-analog conversion circuit 58 to the non-inverting input terminal via the input resistor 77. Here, the operational amplifier circuit 75 is constituted by an integrating circuit having an inverting input terminal and an output terminal connected by an integrating capacitor 78, whereby the peak hold circuit 60 is set based on a target voltage value set via the digital switch 57. , An error voltage of the impulse peak voltage detected is detected, and this error voltage is integrated and output as a control voltage CT. Accordingly, the output stabilizing unit 24 varies the control voltage CT such that the detected impulse peak voltage matches the target voltage value set via the digital switch 57.

This integration process is executed in order to secure an appropriate response speed for intermittently output impulse outputs. The operational amplifying circuit 75 is connected between the inverting input terminal and the non-inverting input terminal by diodes 79 and 80 so as to effectively avoid damage due to high voltage input.

In the above configuration, the impulse power supply 20
In FIG. 4 (FIG. 4), commercial power is input to the power supply circuit 51 via the filter 50, and various power supplies required for the operation are generated. The driving power supply B1 is stabilized at a voltage determined by the control voltage CT in the subsequent stabilizing circuit 52, and is then input to one end of the primary winding of the step-up transformer 25 (FIG. 1). The primary winding current is intermittently supplied to the step-up transformer 25 in response to the switching operation of the drive circuit 40 (FIG. 3) in the drive unit 22 connected to the other end.

As a result, a high voltage corresponding to the ratio of the number of turns of the step-up transformer 25 is intermittently induced in the secondary winding of the step-up transformer 25 (FIG. 1).
To generate an impulse output -OUT.

This impulse output -OUT is detected by a detection winding connected to the cold side of the secondary winding.
That is, the detection winding output S2 of this detection winding is prevented from being mixed with external noise and discharge noise by a shielded cable, and the peak hold circuit 6 of the output stabilizing unit 24 (FIG. 4) is used.
Input to 0. Here, the detection winding output S2 of the detection winding
Is peak-held by a hold capacitor 65 discharged prior to switching, and the peak-held voltage is input to a comparison circuit 74 via an operational amplifier circuit 69 having a voltage follower circuit configuration.

Here, the peak-held voltage is
An error voltage is generated between the target voltage and the target voltage set via the digital switch 57, and the error voltage is integrated by the operational amplifier circuit 75 and converted into a control voltage CT. As a result, the driving power supply B1 is varied by the control voltage CT so that the error voltage becomes 0 [V], that is, the peak voltage of the impulse output −OUT becomes a voltage corresponding to the target voltage. Even when a load fluctuation occurs due to discharge in the cathode ray tube or when a power fluctuation occurs in a commercial power supply, the impulse output −
The peak voltage of OUT is maintained at a constant voltage.

On the other hand, in the drive section 22 (FIG. 3), the operation reference signal S3 generated in the reference signal generation circuit 30 is counted by the counter 36 with the set value set by the digital switch 34, and the counting result is obtained. Is a duty ratio of 50 by the flip-flop 37.
[%], And then converted to a drive signal S5 by the mono-multi vibrator 38. This drive signal S
5, the frequency is detected and displayed by the frequency display circuit 45, whereby the repetition period of the impulse output-OUT is set via the digital switch 34, and the repetition frequency corresponding to the period T can be confirmed.

The drive signal S5 is supplied to the step-up transformer 2
The on / off control of the MOS FET 42 connected to the other end of the primary winding 5 controls the on / off of the step-up transformer 25. As a result, a repetition impulse is generated according to the repetition cycle T set via the digital switch 34, and the repetition cycle can be varied.

According to the above configuration, the peak voltage of the impulse output -OUT is detected via the detection winding, and the voltage of the driving power supply B1 is controlled based on the detection result, whereby power supply fluctuation and load fluctuation And the fluctuation of the output voltage can be effectively avoided. Therefore, a knock test can be performed simultaneously on a plurality of cathode ray tubes, and even if an internal discharge occurs in any one of the cathode ray tubes, the knock test can be performed with a preset test voltage, and the reliability of the knock test can be reduced accordingly. Can be improved.

Since the reference signal is counted by the counter 36 to generate the switching drive signal S5, the counter 36 can be set and the repetition period can be set freely. This makes it possible to apply a larger number of impulses to the cathode ray tube in a shorter time than in the case of a conventional impulse power supply triggered by a commercial power supply, thereby shortening the knock test time and improving the efficiency of the knock test. Can be improved.

In the above-described embodiment, the case where the negative impulse is generated by the impulse power supply has been described. However, the present invention is not limited to this. For example, the polarity of the diode 28 on the secondary winding side is reversed. , Can be widely applied to the case of generating a positive impulse.

Further, in the above-described embodiment, the case where the present invention is applied to the impulse power supply for knocking test has been described. , Can be widely applied to various impulse power supplies.

[0049]

As described above, according to the present invention, the peak value of the output voltage is detected, and the power supply voltage is varied based on the peak value detection result. Can be avoided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an impulse power supply according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram showing an impulse output in the impulse power supply of FIG.

FIG. 3 is a block diagram illustrating a driving unit of the impulse power supply of FIG. 1;

FIG. 4 is a block diagram illustrating a primary power supply unit and an output stabilization unit of the impulse power supply of FIG. 1;

FIG. 5 is a block diagram showing a conventional impulse power supply.

6 is a signal waveform diagram showing an impulse output in the impulse power supply of FIG.

[Explanation of symbols]

1 ... Impulse power supply, 4, 25 ... Step-up transformer, 2
1 primary power supply section, 22 drive section, 24 output stabilization section, 30 reference signal generation circuit, 33 repetition cycle setting circuit, 40 drive circuit, 52 stabilization circuit,
60: peak hold circuit, 74: comparison circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H02M 3/00 H02M 3/00 H

Claims (3)

[Claims] 1. A power supply device for outputting a high-voltage pulse-like signal, a primary power supply circuit for generating and outputting a drive power supply, a pulse generation circuit for generating the pulse-like signal from the drive power supply, A power supply device comprising: a stabilizing circuit that detects a peak value of a pulse signal and changes a voltage of the driving power supply so that the peak value becomes a constant value. 2. The step-up generator according to claim 1, wherein the driving power source is input to one end of a primary winding of a boosting transformer, and the other end of the primary winding is intermittently grounded. The stabilization circuit detects a peak value of the pulse-like signal from a detection winding wound on the boosting transformer. The power supply device according to claim 1. 3. The step-up transformer according to claim 1, wherein the driving power source is inputted to one end of a primary winding of a step-up transformer, and the other end of the primary winding is intermittently grounded at a predetermined repetition cycle. The power supply device according to claim 1, further comprising: a repetition period setting circuit that generates the pulse-like signal from a secondary output induced in the secondary winding of (i) and varies the repetition period.