JPH07322084A - Power supply circuit for tv equipment - Google Patents

Abstract

PURPOSE:To provide a power supply circuit for TV equipment with a simplified circuit to stabilize the output voltage and with less power loss. CONSTITUTION:The voltage on which the parabolar wave generated across the S-like correction capacitor 20 is superposed and passed to a capacitor 41. A diode 42 clamps the low level side of the waveform to provide the parabolar wave Vpb with the low level fixed to the zero. This voltage is compared with the reference voltage Erf by a comparator 39. With the obtained exciting waveform Vsw, the DC voltage Ebo is stabilized. Further, the parabolar Vpb rectifies the summit by a diode 43 and a capacitor 45 through a resistance 44. Thus, the DC voltage Eb1 corresponding to the p-p value of the Vpb is obtained. The Eb1 becomes the value as low as a part of the Ebo. One end of which is connected to a pseudo ground point A and it becomes suitable for the power supply of the comparator 39 and the arithmetic amplifier 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for a television device having a simplified circuit configuration and a low power loss.

[0002]

2. Description of the Related Art Since a chopper type regulator can control a load voltage with high power efficiency by a relatively simple circuit, it has been conventionally used as a main power supply circuit in a television receiver.

FIG. 8 is a circuit diagram showing a power supply circuit of a conventional television device using the chopper type regulator. In FIG. 8, 1 is a first diode bridge type rectifier circuit that receives an AC power supply Eac and generates a DC power supply voltage Eb, 2 is a first smoothing capacitor, 3 is a switch element, 4 is a flywheel diode, and 5 is a choke. A coil, 7 is a second smoothing capacitor, 8 is a power source excitation circuit, and the elements between the switch element 3 and the power source excitation circuit 8 constitute a so-called chopper regulator 9 whose output is controlled by direct current. A voltage Ebo is produced.

This DC voltage Ebo is supplied as a power supply voltage for operation to each circuit 10 in the television equipment. The power supply excitation circuit 8 normally operates by using the first low-voltage DC voltage Eb1 that is lower than the DC voltage Ebo as a power supply. The first low-voltage DC voltage Eb1 is the dropper resistor 11 and the capacitor 12 here. , And is generated by lowering the DC voltage Ebo.

In this way, the power source excitation circuit 8 generates the excitation waveform Vsw that matches the period of the pulse Vh of the horizontal deflection period that is applied at the same time. Then, this excitation waveform V
The switch element 3 is turned on / off according to sw, and a square wave Vo is generated at the output. This square wave Vo cooperates with the operation of the flywheel diode 4 to flow a triangular wave current through the choke coil 5, and a DC voltage Ebo is generated across the second smoothing capacitor 7. And this DC voltage Ebo is
It is proportional to the duty cycle of the ON side of the switch element 3. Therefore, if this DC voltage Ebo is applied to the power supply excitation circuit 8 and if this rises, the excitation waveform Vsw changes, forming a feedback loop such that the duty cycle of the square wave Vo on the side decreases. The DC voltage Ebo is stabilized. By doing this, even if the AC power input E
Even if ac changes, the DC voltage Ebo applied to each circuit 10 in the device becomes constant, and stable operation of the device can be guaranteed.

Next, FIG. 9 is a circuit diagram showing another example of the power supply circuit of the conventional television equipment, in which the parts which operate in the same way as the circuit shown in FIG. Detailed explanation is omitted. Here, the configuration of the chopper regulator 9 including the switch element 3 to the power supply excitation circuit 8 is basically the same as that of FIG. 8, but the DC voltage Ebo of the output is the same as that of the horizontal deflection output circuit 13. Only supplied as a power source.

Here, 14 is a horizontal excitation circuit, 15 is a horizontal excitation transformer, 16 is a horizontal output transistor, 17 is a damper diode, 18 is a return resonance capacitor, 19 is a horizontal deflection coil, 20 is an S-shaped correction capacitor, 21 Is a flyback transformer, and these are combined to form a horizontal deflection output circuit 13. Further, 22 connected to one end of the secondary winding 21b of the flyback transformer 21 is a high voltage rectifying diode, and generates a high voltage HV to be supplied to the anode of a picture tube not shown. Reference numeral 23 connected to one end of the tertiary winding 21c is a low-voltage rectifier diode, and reference numeral 24 is a smoothing capacitor, which supplies the second low-voltage DC voltage Eb2 as a power source to other circuits of the receiver.

Further, 25 is a power transformer, 26 is a second diode bridge rectifier circuit, 27 is a smoothing capacitor,
A smoothing choke coil 55 and a smoothing capacitor 56 generate a first low-voltage DC voltage Eb1 for operating the power supply excitation circuit 8. 28 is a high frequency coupling capacitor.

As shown in FIG. 9, an oscillating waveform Vosc having a horizontal period is added to the horizontal excitation circuit 14 from the preceding stage (not shown), and a third winding is provided at one end of the primary winding 15a of the horizontal excitation transformer 15.
When the low-voltage DC voltage Eb3 is applied, the horizontal excitation waveform Vcd is generated by the horizontal excitation circuit 14 at the other end of 15a. This horizontal excitation waveform Vcd is transformed into the secondary winding 15b and applied between the base and emitter of the horizontal output transistor 16, and as a result, a switching operation is repeated between the collector and emitter thereof, which is repeatedly turned on and off in a horizontal cycle.

In this way, the flyback transformer 2
1 of the primary winding 21a and the horizontal output transistor 1
When the DC voltage Ebo obtained by the chopper regulator 9 described above is applied between the emitter and the emitter of the transistor 6, the damper diode 17 turns on and off in the horizontal cycle together with the horizontal output transistor 16, and the horizontal deflection coil 19 is operated according to the well-known principle. A sawtooth wave current Iy having a horizontal cycle is passed through a series circuit of the S-shaped correction capacitor 20 and the S-shaped correction capacitor 20. by this,
The electron beam of a picture tube not shown is deflected in the horizontal direction.

In this circuit, the primary winding 2 of the horizontal deflection coil 19 and the flyback transformer 21 is mainly used.
A pulse Vc for a half cycle of a sine wave determined by the resonance cycle of the inductance of 1a and the return resonance capacitor 18.
Occurs at the collector of the horizontal output transistor 16. This pulse Vc is boosted by the secondary winding 21b of the flyback transformer 21 to become Vhv and is applied to the anode of a picture tube not shown. Further, the flyback transformer 21 is also provided with a tertiary winding 21c. The pulse V3 obtained from this is rectified by a rectifying diode 23 and further smoothed by a smoothing capacitor 24 to obtain a second low-voltage DC voltage Eb2. .
This DC voltage Eb2 is supplied to the circuits of the respective parts in the circuit as a power supply for operation.

Reference numeral 25 is a power supply transformer, which applies an AC power supply voltage Eac to its primary winding 25a and adds a secondary winding 25b.
A small AC voltage Eac1 is obtained from the
1 is rectified by the second diode bridge 26, and further passed through a filter formed by the smoothing capacitor 27, the smoothing choke coil 55, and the smoothing capacitor 56 to obtain the first low-voltage DC voltage Eb1 for operating the power supply excitation circuit 8. And power.

The characteristic of the circuit shown in FIG. 9 is that of FIG.
The portion of the line A drawn with a thick line, that is, the common connection portion drawn as the ground in FIG. 8 is not directly connected to the housing of the device but is grounded only through high frequencies through the high frequency coupling capacitor 28. That is. The portion A will be referred to as a pseudo ground point hereinafter.

In this way, the DC voltage Ebo generated across the smoothing capacitor 7 is correctly supplied to the horizontal output circuit 13, so that the sawtooth wave current Iy is passed through the horizontal deflection coil 19 and the collector pulse Vc is applied. In addition to the primary winding 21a of the flyback transformer 21, there is no problem in the operation of generating high voltage and the like. On the other hand, since the output of the diode bridge 1 directly connected to the AC power source Eac is not directly connected to the housing of the device, there is no danger of electric shock. As a power source for the circuit portion that must be grounded in the housing in relation to the external connection, a second low-voltage DC voltage Eb2 that is separated from the pseudo ground point A portion and whose negative side is grounded in the housing is supplied. Just do it.

Since this DC voltage Eb2 does not occur unless the horizontal deflection operation is performed normally, it cannot be used as it is as the power supply of the horizontal excitation circuit 14. As a power supply for the horizontal excitation circuit 14, a third low-voltage DC power supply Eb3, which is grounded on one side of the casing and is formed by another means, is used, though not particularly described here. Further, if the portion of the pseudo ground point A is completely disconnected from the ground, the potential of this portion becomes unstable and the operation is hindered. Therefore, the high frequency coupling capacitor 28 grounds at a high frequency. Of course, this high frequency coupling capacitor 2
The value of 8 is set to a value having a sufficiently high impedance with respect to 50 to 60 Hz of the AC power supply Eac so that there is no risk of electric shock even when the housing is touched.

FIG. 10 is a diagram showing a specific configuration of the power supply excitation circuit 8 in FIG. 8 or FIG. Here, 29 and 30 are resistors for dividing a DC voltage, 31 is a Zener diode, 32 is its bias resistor, 33 is an operational amplifier, 34 and 36 are resistors, 35 is a potentiometer,
37 is an oscillation prevention resistor, 38 is an oscillation prevention capacitor,
39 is a comparator. Reference numeral 57 is a waveform shaping transistor, 58 and 59 are base bias resistors thereof, 60 is a collector resistor, and 61 is a charging / discharging capacitor, which form the sawtooth wave voltage generator 40.

In this way, the DC voltage Ebo is first divided by the resistors 29 and 30 and applied to the non-inverting terminal of the operational amplifier 33, and at the same time, the constant voltage generated by the Zener diode 31 and the resistor 32 becomes The voltage is divided by the resistors 34 and 36 and the potentiometer 35 to become the reference voltage Es, which is applied to the inverting terminal. Then, the output reference voltage Erf is applied to the non-inverting terminal of the next comparator 39.

On the other hand, a pulse corresponding to the above-mentioned pulse Vh of the horizontal deflection period is obtained as follows. A pulse V4 is applied to the base of the transistor 57 from the winding 21d newly provided on the flyback transformer 21 to turn on its collector-emitter during this pulse period. Then, at this time, the charge of the capacitor 61 is once discharged and its terminal voltage becomes zero, but when the collector-emitter is turned off after the end of the pulse period, the potential of the capacitor 61 rises through the resistor 60, and eventually the capacitor 61 As the voltage across 61, a sawtooth wave voltage Vst that rises during the horizontal scanning period and bottoms during the blanking period is obtained.

This sawtooth wave voltage Vst is applied to the inverting terminal of the comparator 39 and compared with the above-mentioned reference voltage Erf applied to the non-inverting terminal. Then, the output of the comparator 39 is at the high level only during the period when the sawtooth wave voltage Vst is below the reference voltage Erf, and the excitation waveform V is bottomed during the subsequent period.
You get sw. If the switch element 3 is an element that is turned on during the low level period of the excitation waveform Vsw and turned off during the high level period, for example, a p-type MOSFET, the DC voltage Ebo will rise for some reason. Then, the low-level period of the excitation waveform Vsw, that is, the ON duty cycle of the switch element 3 is automatically reduced to work to lower the DC voltage Ebo. Therefore,
Even if the AC voltage Eac fluctuates and other circuit elements drift, the output DC voltage Ebo is maintained at a constant value.

[0020]

However, in the conventional circuit shown in FIG. 8, as can be seen from the above description, the AC power supply Eac is used.
Since one end of the output of the diode bridge 1 for rectifying is grounded to the housing, there is an unavoidable risk of electric shock. Further, the first low-voltage DC voltage Eb1 as the power supply for operating the power supply excitation circuit 8
Is generated by the voltage drop across the resistor 11 from the higher DC power supply voltage Ebo, the power loss in this resistor is a serious problem.

Further, in the conventional circuit shown in FIG. 9, since the AC power supply is disconnected from the ground, the problem of electric shock has been solved, and the power loss for making the DC voltage Eb1 is far higher than that in FIG. It can be small. However, in the conventional circuit shown in FIG. 9, since the power supply transformer 25, the second diode bridge 26, the smoothing capacitors 27 and 56, and the choke coil 55 are newly required, the cost and volume of this portion become large, which is a problem. The convenience of the chopper regulator cannot be used. Therefore, there is a need for a method of easily obtaining a low-voltage DC power supply for operating the power supply excitation circuit 8 with the pseudo ground point A as a reference with low loss.

Further, in the specific example of the power supply excitation circuit 8 in FIG. 8 or 9 shown in FIG. 10, the flyback transformer 21 newly requires a dedicated winding 21d, and the pulse obtained from this is required. Sawtooth wave voltage V from V4
The need for the sawtooth wave generation circuit 40 for generating st has a drawback that the circuit is also complicated.

[0023]

In order to solve the above-mentioned problems of the prior art, the present invention provides (1) when a DC power supply voltage is input and a DC voltage controlled through a switch element is output, this output voltage Is fed back to the power supply excitation circuit and compared with the reference voltage, and an excitation waveform of the horizontal deflection cycle is output. From this excitation waveform, the on / off operation of the switch element is controlled, and the output voltage is kept constant from the chopper regulator. In the power supply circuit of the television apparatus, a rectifier circuit is provided, which generates a low-voltage DC voltage by rectifying the parabolic wave voltage generated across the S-shaped correction capacitor of the horizontal deflection output circuit and supplies the low-voltage DC voltage to the power supply excitation circuit as the power supply voltage. The power supply excitation circuit compares the output voltage with the reference voltage,
An operational amplifier that outputs a reference voltage and a parabolic wave voltage that is generated across the S-shaped correction capacitor of the horizontal output circuit are input and compared with the reference voltage to generate an excitation that controls the on / off operation of the switch element. A power supply circuit of a television device having a comparator that outputs a waveform, and (2) the rectification circuit is a double-wave rectification circuit, a rectification diode circuit that rectifies the positive side of the waveform, and a negative side. A difference is provided in the circuit impedance between the rectifying diode circuit for rectification and the power supply circuit of the television device according to (1), and (3) the differentiation that differentiates the parabolic wave voltage supplied to the power supply excitation circuit. Characterized by having a circuit
(1) The present invention provides a power supply circuit for the television device described above.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply circuit for a television device according to the present invention will be described below with reference to the accompanying drawings. 1 is a circuit diagram showing a first embodiment of a power supply circuit of a television device of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the circuit shown in FIG. 1, and FIG. FIG. 4 shows a second screen of the power supply circuit of the television device of the present invention.
FIG. 5 is a waveform diagram for explaining the operation of the circuit shown in FIG. 4, FIG. 6 is a diagram showing a circuit for differentiating the parabolic wave voltage Vpb, and FIG. 7 is a television of the present invention. It is a circuit diagram which shows the 3rd Example of the power supply circuit of a John equipment.
In addition, in FIG. 1, FIG. 4, and FIG.
The same parts as those in FIGS. 9 and 10 are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, the portion from the horizontal excitation circuit 14 to the smoothing capacitor 24 functions as a horizontal deflection output and high voltage output circuit as in the case of FIG. 9, and the horizontal deflection coil 1
There is no change in the operation of causing the sawtooth wave current Iy of the horizontal cycle to flow in 9 and simultaneously generating the high voltage HV on the secondary side of the flyback transformer. In addition, the first diode bridge 1 to the second smoothing capacitor 7 and the high frequency coupling capacitor 2
The part from 8 to the comparator 39 rectifies the AC input voltage Eac, controls the voltage and converts it to the DC voltage Ebo, and adds this to one end of the primary winding 21a of the flyback transformer 21 and the horizontal output circuit 13 The same applies to the operating power supply of. In FIG. 1, newly provided are a DC blocking capacitor 41, a first parabolic-wave rectifying diode 42, a second parabolic-wave rectifying diode 43, a resistor 44, and a smoothing capacitor 45.

In FIG. 1, as is well known, a voltage in which a parabolic wave having a horizontal deflection period is superimposed on the DC voltage Ebo is generated across the S-shaped correction capacitor 20.
Therefore, this is passed through the capacitor 41 and the diode 42
When the low level side of the waveform is clamped at, the parabolic wave voltage Vpb with the low level side fixed to zero is obtained as shown by the solid line in FIG. 2 (A). Then, when the parabolic wave voltage Vpb is compared with the reference voltage Erf indicated by the alternate long and short dash line in the figure by the comparator 39, the excitation waveform Vsw as shown in FIG. 2B is obtained.

As can be seen from FIG. 2, if the DC voltage Ebo rises for some reason and the reference voltage Erf rises as a result, the excitation waveform V as shown by the broken line.
The time length toff of the high level side of sw, that is, the portion where the switch element 3 is turned off becomes long. Therefore, this works to lower the output DC voltage Ebo, and eventually the DC voltage Ebo does not move stably at a constant value. As described above, the power supply circuit of the television device of the present invention shown in FIG.
The first feature is that the waveform applied to the inverting terminal of the parabolic wave voltage Vpb is not the sawtooth wave Vst but the parabolic wave voltage Vpb. This is performed, and the circuit is greatly simplified as compared with the case where the sawtooth wave Vst is generated by the circuit shown in FIG.

Further, when the top of the parabolic wave voltage Vpb is rectified by the diode 43 and the capacitor 45 through the resistor 44, a DC voltage Eb1 corresponding to the peak-peak (pp) value of Vpb is obtained, which is zenered. It is used as a power supply for operating the parts from the diode 31 to the comparator 39. That is, between the DC blocking capacitor 41 and the smoothing capacitor 45, a rectifying circuit 70 that rectifies the pp value of the parabolic wave generated at both ends of the S-shaped correction capacitor 20 is formed. The low-voltage DC voltage Eb1 thus obtained is generally a fraction of the value of the DC voltage Ebo, and one end of the low-voltage DC voltage Eb1 is connected to the pseudo ground point A. Therefore, the comparator 39 and the operational amplifier 33 are connected. It is suitable as a power source.

Therefore, unlike the conventional circuit shown in FIG. 9, in which the DC voltage Eb1 is obtained by using the power transformer 25, the diode bridge 26, the smoothing capacitors 27 and 56, and the choke coil 55, FIG. A simple circuit is sufficient, and at the same time, the parabolic wave voltage Vpb as a comparison waveform to be applied to the comparator 39 is also generated, so that the circuit is greatly simplified. The value of the smoothing capacitor 45 for the DC voltage Eb1 shown in FIG. 1 is smaller than that of the smoothing capacitor for the same purpose shown in FIG. 9 because the horizontal deflection frequency to be handled is much higher than the frequency of the AC Eac of the power source. The value is sufficient, and it is not necessary to use a choke coil to form a pie-type filter. Also in this respect, the present invention is advantageous for downsizing and cost reduction.

Further, as in the circuit shown in FIG. 1, the method of rectifying the parabolic wave voltage across the S-shaped correction capacitor 20 to obtain the DC voltage has another advantage. That is, when the S-shaped correction capacitor 20 is simply connected in series with the horizontal deflection coil 19 as in the conventional circuit shown in FIG. 9, image distortion may occur. For example, as shown in FIG. 3, when a lattice-stripe signal is received, the load current Ia of the high-voltage HV abruptly increases in the white horizontal line portion, so that the deflection current thereafter is affected and the vertical line oscillates left and right. It is a phenomenon.

In order to reduce this distortion, it is known to add a diode clamp circuit so that the potential of the S-shaped correction capacitor 20 does not move even if the high voltage load current Ia changes. The capacitor 41 and the diode 42 of the circuit shown in FIG. 1 have a voltage clamping effect in combination with the action of the load current drawn from the low-voltage DC voltage Eb1, and have the advantage of simultaneously reducing the distortion as shown in FIG. However, if the low-voltage DC voltage Eb1 is created by performing full-wave rectification without the resistor 44, it will try to clamp both the upper and lower ends of the parabola wave of the S-shaped correction capacitor 20, The potential is not stable. In order to prevent this, there is no problem if the diode 43 is replaced with a choke coil or the like for half-wave rectification. However, in that case, the value of the DC voltage Eb1 is reduced to about half.

If the voltage value of Eb1 is insufficient and it is absolutely necessary to perform double-wave rectification, a resistor 44 is added to the rectifying diode 43 on one side to half-clamp this, as shown in FIG. It should be done. Then, the clamping action is performed mainly only by the diode 42, and the potential of the lower tip portion of the parabola wave is fixed, so that the above-described distortion correction action is performed without any trouble. The voltage value of Eb1 resulting from the rectification can also be set sufficiently higher than in the case of half-wave rectification.

In the chopper regulator shown in FIG. 1, the square wave Vo obtained through the switch element 3 is converted into a DC voltage Ebo by the choke coil 5 and the smoothing capacitor 7,
It is added to one end of the primary winding 21a of the flyback transformer 21. However, if the load of the chopper regulator is limited to the horizontal output circuit, the choke coil 5 and the smoothing capacitor 7 can be omitted.

FIG. 4 shows an example thereof, in which the output Vo of the switch element 3 is directly connected to one end of the primary winding 21a of the flyback transformer. The operation in this case will be described with reference to FIG. 5. First, the parabolic wave voltage Vpb in FIG. 5A is compared with the reference voltage Erf, and the excitation waveform Vsw used in the switch operation of the chopper as shown in FIG. Obtaining is the same as the circuit shown in FIG. At this time, the horizontal output collector pulse Vc has a phase relationship as shown in FIG. 5 (C), and is located substantially at the center of the excitation waveform Vsw.

The switch element 3 turns from on to off at the rising time t1 of the excitation waveform Vsw. However, at the time t2 at the center of the retrace time tr, which is the width of the collector pulse, the energy recovery diode 6 newly added in FIG. 4 is automatically turned on by the return current from the flyback transformer winding 21a. Therefore, the square wave Vo output from the switch element 3 becomes equal to the input DC voltage Eb at time t2 as shown in FIG. 5 (D), and its pulse width is different from Vsw in FIG. 5 (B). It does not match. However, since the position of the rising time t1 of the excitation waveform Vsw moves back and forth depending on the reference voltage Vrf, the bottoming width of the square wave Vo also changes accordingly.

FIG. 5E shows the current It flowing through the flyback transformer primary winding 21a at this time. During the horizontal scanning period ts, the gradient current flows as usual, but at time t1
After that, since the switch element 3 is turned off, the current becomes flat, becomes an oscillating current when the flyback time tr is entered, and leads to the start of the gradient current It from the horizontal scanning period ts. As can be seen from FIG. 5 (E), when the reference voltage Erf changes and the time t1 position moves, the maximum value (flat portion) of the current It changes, and the maximum energy stored in this horizontal output circuit also changes. The coil current and high voltage output can also be controlled.

Thus, in the circuit format as shown in FIG.
There is no DC voltage Ebo which is the result of the control as in the circuit shown in FIG. Therefore, instead, a filter 48 newly composed of a resistor 46 and a capacitor 47 is newly provided, and the DC voltage Eb4 is taken out from this, and this voltage Eb4 is obtained.
May be appropriately divided and then applied to the non-inverting terminal of the operational amplifier 33. Since both the deflection current Iy and the high voltage value HV are proportional to this DC voltage Eb4, if the DC voltage Eb4 is made constant in this way, it is similarly stabilized.

In the case of FIG. 1 described above, there is no particular condition except that the timing at which the switch element 3 is turned off is synchronized with the horizontal deflection in terms of countermeasures against interference, that is, in short, the switch element 3 is turned off. It only needs to be able to control the duty cycle. For example, the inversion / non-inversion of the input terminals of the operational amplifier 33 and the comparator 39 of FIG.
Even if f enters the scanning period ts, it operates without any problem. However, in the circuit format shown in FIG. 4, as can be seen from the description of FIG.
The high level period of the excitation waveform Vsw corresponding to the period needs to extend before and after the retrace time tr. In this respect, it is convenient to create the excitation waveform Vsw based on the parabola voltage Vpb in this way. However, the polarities of the operational amplifier 33 and the comparator 39 are limited as shown in FIG.

When the parabolic wave voltage Vpb is used in place of the conventional sawtooth wave Vst as in the circuit shown in FIG. 4, the excitation waveform Vsw can be seen from the waveform diagram shown in FIG.
The moving range of the rising time t1 is from the center of the scanning period ts to the start time of the blanking period tr. Therefore, as described with reference to the waveform diagram shown in FIG. 2, the control range is about half that of the circuit shown in FIG. If the control range is insufficient, the modification shown in FIG. 6 is applied. This is not a parabolic wave but a waveform obtained by slightly differentiating the parabolic wave is added to the non-inverting terminal input of the comparator 39. That is, in FIG. 6, the parabolic wave voltage Vpb is differentiated by the resistors 49, 50 and 51 and the capacitor 52 (differential circuit), and then appropriately divided and applied to the comparator 39. By doing so, the apex of the waveform applied to the comparator moves forward, as indicated by the broken line in FIG. 5 (A), so that time t1 can be moved further forward accordingly. And the control range of voltage is expanded.

Next, another embodiment of the present invention will be described with reference to FIG. As shown in FIGS. 1 and 4, when the parabolic wave voltage Vpb across the S-shaped correction capacitor 20 is rectified to obtain the DC voltage Eb1, the voltage value of this Eb1 is also the average of the DC voltage Ebo and the square wave Vo. It is proportional to the value Eb4, in other words, the deflection current Iy and the high voltage value HV. Therefore, even if a voltage proportional to the DC voltage Eb1 is added to the operational amplifier 33 and made constant by comparison with the reference voltage Es, the deflection current Iy and the high voltage HV are still stabilized.

In FIG. 7, resistors 53 and 54 are for dividing the DC voltage Eb1 and applying it to the non-inverting terminal of the operational amplifier 33. By doing so, the divided value is naturally made constant so as to coincide with the reference voltage Es, so that the parabola voltage Vpb and the deflection current Iy are stabilized. The circuit configuration is simpler than that of FIG. In addition,
In the case of the circuit shown in FIG. 7, the form without the choke coil and the second smoothing capacitor similar to that in FIG. 4 has been described, but this is of course the choke coil 5 and the second smoothing capacitor 7 as shown in FIG. It is also possible to use the format with.

[0042]

As described in detail above, in the power supply circuit of the television apparatus of the present invention, the circuit for stabilizing the output voltage is greatly simplified, and the power loss is small.
At the same time, it has an extremely excellent practical effect of reducing image distortion.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a power supply circuit of a television device of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the circuit shown in FIG.

FIG. 3 is a diagram showing a screen when a lattice fringe signal is received.

FIG. 4 is a circuit diagram showing a second embodiment of the power supply circuit of the television device of the present invention.

5 is a waveform chart for explaining the operation of the circuit shown in FIG.

FIG. 6 is a diagram showing a circuit for differentiating the parabolic wave Vpb.

FIG. 7 is a circuit diagram showing a third embodiment of the power supply circuit of the television device of the present invention.

FIG. 8 is a circuit diagram showing a power supply circuit of a conventional television device using a chopper type regulator.

FIG. 9 is a circuit diagram showing another example of a power supply circuit of a conventional television device.

10 is a circuit diagram showing a specific configuration of the power supply excitation circuit 8 in FIG. 8 or FIG.

[Explanation of symbols]

1 First diode bridge type rectifier circuit 2 First smoothing capacitor 3 Switch element (chopper regulator) 4 Flywheel diode (chopper regulator) 5 Choke coil (chopper regulator) 6 Energy recovery diode 7 Second smoothing capacitor (chopper regulator) ) 8 power supply excitation circuit (chopper regulator) 9 chopper regulator 13 horizontal deflection output circuit 20 S-shaped correction capacitor 33 operational amplifier (power supply excitation circuit) 39 comparator (power supply excitation circuit) 41 DC blocking capacitor (rectifier circuit) 42 first Parabolic wave rectifier diode (rectifier circuit) 43 Second parabolic wave rectifier diode (rectifier circuit) 44 Resistance (rectifier circuit) 45 Smoothing capacitor (rectifier circuit) 49-51 Resistor (differential circuit) 52 Condenser Sa (differentiating circuit) 70 rectifier circuit Eb DC power supply voltage Ebo output voltage Eb1 low DC voltage Erf reference voltage Es reference voltage Vsw excitation waveform Vpb parabolic wave voltage

Claims (3)

[Claims] 1. When inputting a DC power supply voltage and outputting a DC voltage controlled through a switch element, this output voltage is fed back to a power supply excitation circuit and compared with a reference voltage to output an excitation waveform of a horizontal deflection cycle. In a power supply circuit of a television device including a chopper regulator for controlling the on / off operation of the switch element by this excitation waveform to keep the output voltage constant, the voltage is generated across the S-shaped correction capacitor of the horizontal deflection output circuit. A rectifier circuit that generates a low-voltage DC voltage that rectifies the parabolic wave voltage and supplies the low-voltage DC voltage to the power supply excitation circuit as a power supply voltage is provided, and the power supply excitation circuit compares the output voltage with the reference voltage and outputs a reference voltage. An operational amplifier and a parabolic wave voltage generated across the S-shaped correction capacitor of the horizontal output circuit are input and compared with the reference voltage.
A power supply circuit for television equipment, comprising: a comparator that outputs an excitation waveform for controlling the on / off operation of the switch element. 2. The rectifier circuit is a double-wave rectifier circuit, and a circuit impedance is provided between a rectifier diode circuit that rectifies the positive side of a waveform and a rectifier diode circuit that rectifies the negative side of the waveform. Item 1. A power supply circuit for a television device according to Item 1. 3. A power supply circuit for television equipment according to claim 1, further comprising a differentiating circuit for differentiating the parabolic wave voltage supplied to the power supply exciting circuit.