JP2002320104A - High-voltage correction circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-voltage correction circuit which can restrain high voltage fluctuations in a television picture tube. SOLUTION: The high-voltage correction circuit 5 consists of a diode modulator circuit 6, connected between the collector and the emitter of a horizontal transistor Tr1, and a high-voltage control circuit 7 which produces a feedback signal corresponding to a high-voltage output of a flyback transformer FBT and feeds back the signal to the circuit 6. A voltage, divided by a resistor R1 and a resistor R2, is inputted in an inverting input terminal of an operational amplifier 7a, and a specified DC voltage is inputted in a non-inversion input terminal. The output of the operational amplifier 7a is applied to a connection point B of the diode modulator circuit 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correction circuit for a high voltage circuit that generates a high voltage using a flyback pulse.

[0002]

2. Description of the Related Art FIG. 5 shows a flyback transformer FBT and a horizontal output circuit 1 constituting a high-voltage circuit of a television receiver. A diode modulator circuit 2 and a deflection correction circuit 3 are connected between the collector and the emitter of the horizontal transistor Tr1 in the horizontal output circuit 1. The diode modulator circuit 2 includes two series-connected diodes D1 and D2 and two series-connected resonance capacitors C1 and C2, and connects a diode connection point and a capacitor connection point to each other (hereinafter, referred to as a diode connection circuit).
This connection point is denoted by the symbol A). The deflection correction circuit 3 is formed by connecting a series connection of a horizontal deflection coil L1 and an S-shaped correction capacitor C3, and a series connection of a pincushion correction coil L2 and a capacitor C4. The connection point is connected to the connection point A of the diode modulator circuit 2. A pin cushion correction voltage (PCC correction) is applied to a connection point between the pin cushion correction coil L2 and the capacitor C4. The pincushion correction voltage is supplied from a collector of a transistor (not shown) to which a parabola voltage is applied to a base. The horizontal output circuit 1 includes a horizontal transistor Tr
1 horizontal pulse signal (H-DRIV)
E) generates a sawtooth waveform current and supplies it to the horizontal deflection coil L1. At this time, the deflection current of the horizontal deflection coil L1 is controlled according to the horizontal scanning line position, and pincushion distortion correction is performed. The flyback transformer FBT supplies a high voltage (anode voltage HV, focus voltage Fo, screen voltage s) to the picture tube using a flyback pulse generated in the horizontal output circuit 1, and
Supply power to other circuits.

[0003]

By the way, when the picture of the picture tube is dark, the anode current is reduced to cause an increase in the high voltage, and the electron beam is more likely to be drawn to the tube surface side, so that the picture size is reduced. In addition, the deflection power by the horizontal deflection coil L1 is relatively small, the scanning width is narrowed, and a distortion occurs in which the horizontal width of the screen is reduced due to a synergistic effect of these. Conversely, when the picture tube of the picture tube is bright, the anode current increases to cause a decrease in high voltage, and a distortion occurs in which the picture width increases. As a result, FIG.
As shown in FIG.

In the circuit shown in FIG. 5, since the high voltage circuit and the deflection circuit are constituted by one system, they mutually affect each other and the distortion is increased. Then, as shown in FIG.
Five systems of circuits are used, or two systems of circuits shown in FIG.

However, the above-described 1.5-system circuit and 2
In the system circuit, the mutual influence between the high voltage fluctuation and the deflection can be reduced, but the screen distortion due to the anode current fluctuation in the single high voltage circuit has occurred, and it is an issue to solve such a problem. In particular, there is a demand for displaying high-definition broadcasting by BS digital broadcasting with high image quality, and not causing screen distortion even with an increase in screen luminance difference in data broadcasting.

In view of the above circumstances, an object of the present invention is to provide a high-voltage correction circuit capable of suppressing a high-voltage fluctuation in a television picture tube.

[0007]

In order to solve the above-mentioned problems, a high-voltage correction circuit according to the present invention corrects a high voltage in a high-voltage circuit having a horizontal output transistor connected to a horizontal deflection coil and a flyback transformer. In the circuit, a diode modulator connected between the collector and the emitter of the horizontal transistor and at least one of a feedback signal corresponding to a high voltage output of a flyback transformer and a feedback signal corresponding to a beam current flowing through the flyback transformer are generated. Means for feeding back to the diode modulator.

With the above configuration, when the high-voltage output of the flyback transformer decreases or the beam current increases,
This is reflected in the feedback signal to control the diode modulator so that the high voltage output is kept constant. High voltage fluctuations are suppressed, and vertical line bending and image distortion are reduced.

A feedback signal may be generated in consideration of a video signal or a luminance signal in the video signal. If the luminance signal value, etc. is high, the screen becomes brighter as a result, and the high voltage tends to decrease.Therefore, it is possible to more accurately maintain the high voltage constant by performing correction in consideration of the luminance corresponding signal. Become. In particular, since a video signal and a luminance signal that cause high-voltage output and beam current fluctuation are added in advance, a time delay of correction is reduced.

The power supply current to the high-voltage generating circuit may be converted into a voltage, and a feedback signal may be generated in consideration of a signal based on the voltage. If the screen (CRT) becomes brighter, the power supply current of the high-voltage generation circuit increases, and if the screen becomes darker, the power supply current of the high-voltage generation circuit decreases. Therefore, this power supply current change is combined with high-voltage fluctuation information and beam current information. Thereby, more accurate high-pressure correction can be performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to FIG.
4 through FIG. For convenience of description, the same components as those described in the conventional example are denoted by the same reference numerals.

FIG. 1 shows a flyback transformer FBT, a horizontal output circuit 1, and a high-voltage correction circuit 5 of this embodiment, which constitute a high-voltage circuit of a television receiver. The circuit configuration of this example is an example applied to the 1.5-system circuit shown in FIG. A diode modulator circuit 2 and a deflection correction circuit 3 are connected between the collector and the emitter of the horizontal transistor Tr1 in the horizontal output circuit 1. The diode modulator circuit 2 includes two series-connected diodes D1 and D2 and two series-connected resonance capacitors C1 and C2, and connects a diode connection point and a capacitor connection point to each other (hereinafter, referred to as a diode connection circuit). This connection point is denoted by the symbol A). The deflection correction circuit 3 is formed by connecting a series connection of a horizontal deflection coil L1 and an S-shaped correction capacitor C3, and a series connection of a pincushion correction coil L2 and a capacitor C4. The connection point is connected to the connection point A of the diode modulator circuit 2. Pincushion correction coil L2 and capacitor C4
Pincushion correction voltage (PCC correction) at the connection point with
Is applied. The pincushion correction voltage is supplied from a collector of a transistor (not shown) to which a parabola voltage is applied to a base. The horizontal output circuit 1 outputs a horizontal pulse signal (H−H) input to the base of the horizontal transistor Tr1.
DRIVE) to generate a sawtooth-shaped current, which is supplied to the horizontal deflection coil L1. At this time, the deflection current of the horizontal deflection coil L1 is controlled according to the horizontal scanning line position, and pincushion distortion correction is performed. The flyback transformer FBT uses a flyback pulse generated in the horizontal output circuit 1 to apply a high voltage (anode voltage H) to the picture tube.
V, the focus voltage Fo, and the screen voltage s), and also supplies power to other circuits and the like.

The high-voltage correction circuit 5 generates a feedback signal corresponding to the high-voltage output of the flyback transformer FBT by connecting the diode modulator circuit 6 connected between the collector and the emitter of the horizontal transistor Tr1 to the diode modulator circuit 6. And a high-voltage control circuit 7 for feeding back.

The diode modulator circuit 6 includes two series-connected diodes D3 and D4 and two series-connected resonance capacitors C5 and C6, and connects a diode connection point and a capacitor connection point to each other. (Hereinafter, this connection point is denoted by reference numeral B). The connection point A is connected to the primary winding of the flyback transformer FBT via the capacitor C7.

The high voltage control circuit 7 includes resistors R1 and R2 for dividing the high voltage output of the flyback transformer FBT, and an operational amplifier 7a. The voltage divided by the resistors R1 and R2 is input to the inverting input terminal of the operational amplifier 7a, and a predetermined DC voltage is input to the non-inverting input terminal. And
The output of the operational amplifier 7a is applied to the connection point B of the diode modulator circuit 6.

With the above configuration, when the high-voltage output of the flyback transformer FBT decreases, the output potential of the operational amplifier increases, and the horizontal potential of the horizontal transistor Tr1 is increased by the diode modulator 6 receiving this output potential at the connection point B.
, The voltage between the collector and the emitter increases, the primary voltage of the flyback transformer FBT rises, and the high-voltage output rises. On the other hand, when the high-voltage output of the flyback transformer FBT rises, the output potential of the operational amplifier decreases, and the voltage between the collector and the emitter of the horizontal transistor Tr1 decreases due to the diode modulator 6 receiving this output potential at the connection point B, thereby reducing the fly potential. The primary voltage of the back transformer FBT decreases, and the high-voltage output decreases. As a result, screen distortion due to high-voltage fluctuation is prevented, and high-definition broadcasting can be displayed with high image quality.

FIG. 2 shows another example of the high voltage correction circuit. This high-voltage correction circuit further includes an adding means 8 and a luminance signal value corresponding output section 9. The video signal value corresponding output unit 9 is a voltage value corresponding to a luminance signal output from a video signal output unit (not shown), specifically, a signal for increasing the high voltage when the luminance signal value is high (a luminance signal inversion voltage value or the like). Is given to the adding means 8, and when the luminance signal value is low, a signal for lowering the high voltage is given to the adding means 8. If the luminance signal value is high, the screen will be bright and the high voltage will tend to decrease.Therefore, by correcting both the luminance signal and the high voltage output, it is possible to more accurately maintain the high voltage constant. Become. In particular, in addition to the high-voltage output fluctuation, by adding in advance the luminance signal that causes this fluctuation, there is an effect that the time delay of the correction is reduced.

It should be noted that a chrominance signal (C signal) may be further added as correction information in addition to the luminance signal value. According to this, it is possible to cope with a delicate change in luminance in which colors are combined.

FIG. 3 shows another example of the high voltage correction circuit. This high voltage correction circuit includes an adding means 8 and a beam current corresponding output section 10. The beam current corresponding output unit 10 is a circuit for providing a voltage value corresponding to the beam current in the flyback transformer FBT to the adding means 8. Screen (CR
Since the change in the brightness of T) means that the beam current changes, more accurate high-voltage correction can be performed by converting the beam current into a voltage and combining the voltage with the high-voltage fluctuation information.

It is also possible to perform high voltage correction by controlling the diode modulator circuit 6 only by the beam current without detecting the high voltage fluctuation.

FIG. 4 shows another example of the high voltage correction circuit. This circuit is provided with a power supply current information output circuit 11 for giving a change (signal) of a power supply current (+ B) to the high voltage generation circuit, and supplies the power supply current information to the adding means 8. When the screen (CRT) becomes bright, the power supply current to the high-voltage generation circuit increases, and when it becomes dark, the power supply current to the high-voltage generation circuit decreases. Therefore, by combining the power supply current change with the high voltage fluctuation information, more accurate high voltage correction can be performed.

Although the configuration applied to the 1.5-system circuit has been exemplified, the present invention can be applied to the one-system circuit shown in FIG. 5 or the two-system circuit shown in FIG. In the above example, the feedback signal is generated mainly based on the high voltage fluctuation. However, the feedback signal is generated mainly based on the beam current by adding the luminance signal / video signal or the power supply current (+ B). You may.

[0023]

As described above, according to the present invention, high-voltage fluctuations can be suppressed and vertical line bending and image distortion can be reduced. This is effective for improving the image quality of images having black bands on the left and right sides of the screen, such as three broadcasts.
In addition, in the text broadcasting, even if a part of the screen undergoes an extreme change in luminance, other screen parts are hardly affected, and an effect of providing an easy-to-view screen can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a high-voltage correction circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another example of the high-voltage correction circuit according to the embodiment of the present invention.

FIG. 3 is a circuit diagram showing another example of the high voltage correction circuit according to the embodiment of the present invention.

FIG. 4 is a circuit diagram showing another example of the high voltage correction circuit according to the embodiment of the present invention.

FIG. 5 is a circuit diagram showing a conventional high voltage correction circuit (one system).

FIG. 6 is an explanatory diagram showing screen distortion.

FIG. 7A is a circuit diagram showing a conventional high voltage correction circuit (1.5 systems), and FIG. 7B is a circuit diagram showing a conventional high voltage correction circuit (2 systems). is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Horizontal output circuit 2 Diode modulator circuit 3 Deflection correction circuit 5 High voltage correction circuit 6 Diode modulator circuit 7 High voltage control circuit 7 7a Operational amplifier 8 Addition means 9 Luminance signal value corresponding output unit 10 Beam current corresponding output unit 11 Power supply current information output circuit Tr1 Horizontal transistor FBT flyback transformer

Claims (3)

[Claims] 1. A correction circuit for correcting a high voltage of a high voltage circuit comprising a horizontal deflection transistor and a flyback transformer connected to a horizontal output transistor, a diode modulator connected between a collector and an emitter of the horizontal transistor, and a flyback. Means for generating at least one of a feedback signal corresponding to the high voltage output of the transformer and a feedback signal corresponding to the beam current flowing through the flyback transformer and feeding back the feedback signal to the diode modulator. 2. The high voltage correction circuit according to claim 1, wherein the high voltage correction circuit is configured to generate a feedback signal in consideration of a video signal or a luminance signal in the video signal. 3. The high-voltage correction circuit according to claim 1, wherein a power supply current to the high-voltage generation circuit is converted into a voltage, and a feedback signal is generated by adding a signal based on the voltage. A high-voltage correction circuit characterized by: