JPH0750763A - Horizontal deflection circuit - Google Patents

Abstract

PURPOSE:To simply and easily adjust the fluctuation of horizontal amplitude due to the luminance change of a display screen, the change of a horizontal deflection frequency and the characteristic change of an FBT. CONSTITUTION:This circuit is equipped with a polarity inversion circuit 20 which polarity-inverts a DC voltage IV detected and smoothed by a beam current detecting resistor 14, an analog/digital converter 21 which outputs the output of the polarity inversion circuit 20 as digital data, an arithmetic unit 22 which performs arithmetic processing by inputting the digital data of the converter 21, a digital/analog converter 23 which outputs by converting the output of the arithmetic unit 22 to analog quantity, an amplifier circuit 24 which amplifies the output of the converter 23, a horizontal deflection amplitude controller 10 which inputs the output of the amplifier circuit 24 and supplies it to the common connecting point of a modulation coil 8 and an S shape-correction capacitor 9, and a power supply voltage control circuit 11 which controls a power supply voltage VCC by a voltage detected by a high voltage detector 17, and a high voltage HV is kept constant by controlling the output voltage VCC of the control circuit 11, and the fluctuation of the horizontal amplitude generated by the luminance change of the display screen can be corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal deflection circuit for a cathode ray tube display device, and more particularly, it is suitable for a multi-scan type cathode ray tube display device and is capable of correcting a variation in horizontal amplitude caused by a change in luminance of a display screen. It relates to a horizontal deflection circuit.

[0002]

2. Description of the Related Art It is desirable that the amplitude of a display screen of a cathode ray tube display device is ideally constant regardless of the brightness of the display screen. However, in practical use, when the brightness of the display screen changes, the beam current also increases and decreases, and the anode voltage changes, so the display amplitude fluctuates. For this reason, conventionally, this amplitude variation has been corrected by the horizontal deflection circuit having the configuration shown in FIG.

In FIG. 6, reference numeral 1 denotes a horizontal deflection output transistor whose emitter is grounded. A series circuit composed of a horizontal deflection coil 6 and a first S-shaped correction capacitor 7 and a parallel circuit composed of a first damper diode 2 and a first resonance capacitor 4 are provided between the collector and the emitter of the transistor 1. A series circuit composed of the modulation coil 8 and the second S-shaped correction capacitor 9 and a parallel circuit composed of the second damper diode 3 and the second resonance capacitor 5 are connected in series.

Reference numeral 12 is a flyback transformer, one end of the primary winding of which is connected to a power source + B via a power source voltage control circuit 11.
The other end is connected to the collector of the transistor 1. In addition, one end of the secondary winding is a high voltage rectifier diode 13
Is connected to the anode of the cathode ray tube via, and the other end is grounded via the beam current detection resistor 14.

Reference numeral 10 denotes a horizontal deflection amplitude controller composed of a known circuit, which is an output obtained by inverting and amplifying a DC voltage IV detected by a beam current detection resistor 14 and smoothed by a smoothing capacitor 15 by a polarity inverting / amplifying circuit 19. Is input and the output thereof is connected to control the voltage V9 across the second S-shaped correction capacitor 9.

Reference numerals 16 and 17 denote high-voltage detectors. One end of the high-voltage detector 16 is connected to the cathode of the high-voltage rectifying diode 13, and the other end is connected in series to the high-voltage detector 17 whose one end is grounded. The high voltage LV detected at the common connection point of the high voltage detectors 16 and 17 is the power supply voltage control circuit 1
The power supply voltage control circuit 11 is controlled so as to cancel the change in the high voltage LV detected by being fed back to 1.
The power supply voltage control circuit 11 is composed of a known circuit and supplies the controlled power supply voltage VCC to the horizontal deflection circuit.

In the horizontal deflection circuit configured as described above, when the brightness of the display screen is increased while the power supply voltage VCC is kept constant, the high voltage HV becomes the curve a in FIG. 2 as the beam current increases. The characteristic curve as shown decreases and the horizontal and vertical amplitudes increase. Therefore, when the voltage LV detected by the high voltage detector 17 is fed back to the power supply voltage control circuit 11, the power supply voltage VCC is controlled so as to cancel the change in the detected voltage LV, and the high voltage is irrespective of the brightness of the display screen. The voltage HV becomes constant. In this way, the high voltage HV is controlled to be constant, so that the vertical amplitude is also constant.

However, since the horizontal deflection current flowing through the horizontal deflection coil 6 increases as the power supply voltage VCC increases,
The horizontal amplitude fluctuated. Therefore, when the power supply voltage VCC is controlled so that the high voltage HV is constant with respect to the brightness change of the display screen, there is a problem that the horizontal amplitude fluctuates.

Therefore, in the conventional circuit, the negative polarity DC voltage IV detected by the beam current detecting resistor 14 and smoothed by the smoothing capacitor 15 is inverted and amplified by the polarity inverting / amplifying circuit 19 so as to be an appropriate correction voltage, The voltage is input to the horizontal deflection amplitude controller 10 and the voltage across the second S-shaped correction capacitor 9 is controlled by its output so that the horizontal amplitude is constant regardless of the brightness of the display screen.

That is, the voltage V9 across the second S-shaped correction capacitor 9 is lowered, the deflection current flowing through the horizontal deflection coil 6 is increased to increase the horizontal amplitude, and the voltage across the voltage V
9 was increased to reduce the horizontal amplitude.

[0011]

In the conventional horizontal deflection circuit described above, the high voltage H regardless of the beam current IA.
When the V is controlled to be constant, the horizontal amplitude changes in a curved shape as shown by the curve b in FIG. 3 with respect to the beam current IA. On the other hand, the DC voltage IV with respect to the change in the beam current IA detected by the beam current detection resistor 14 changes linearly as shown in FIG. Therefore, the polarity of the detected voltage IV is inverted, the amplified voltage is amplified to an appropriate correction voltage, and the voltage V9 across the S-shaped correction capacitor 9 is controlled via the horizontal deflection amplitude controller 10 to obtain the curve a in FIG. As shown in
It was corrected so that the fluctuation of the horizontal amplitude was reduced.

However, since the fluctuation of the horizontal amplitude remains, the output of the polarity reversing / amplifying circuit 19 needs to have a curve characteristic as shown in FIG. 5 in order to obtain a display device with higher image quality. The polarity reversing / amplifying circuit 19 having such characteristics has a complicated circuit configuration and is expensive. In particular, in a multi-scan type cathode ray tube display device, it is desired that the amplitude be constant regardless of the brightness of the display screen even if the horizontal deflection frequency changes. Had to change. In addition, there is a drawback that the circuit configuration of the polarity reversing / amplifying circuit 19 becomes more complicated and expensive in order to eliminate the excess or deficiency of the control amount of the horizontal amplitude caused by the frequency. In addition, when the characteristics of the high voltage HV with respect to the change of the beam current of the flyback transformer 12 change due to design changes or the like, the components and circuit constants of the polarity reversing / amplifying circuit 19 are reviewed each time to obtain the optimum characteristics. However, there was a drawback that it required complicated adjustment work.

An object of the present invention is to correct horizontal amplitude fluctuations caused by changes in the brightness of the display screen, changes in the horizontal deflection frequency, or changes in the characteristics of the flyback transformer. (EN) Provided is a horizontal deflection circuit which has a simple circuit configuration and can be easily adjusted for correction.

[0014]

A series circuit including at least a horizontal deflection coil 6 and a first S-shaped correction capacitor 7, a first damper diode 2 and a first resonance capacitor 4 are provided.
And a parallel circuit composed of a modulation coil 8 and a second S-shaped correction capacitor 9 and a parallel circuit composed of a second damper diode 3 and a second resonance capacitor 5 are connected in series to form a collector-emitter. A horizontal deflection output transistor 1 having a grounded emitter, which is connected in between, is connected to a power source + B through the power supply voltage control circuit 11 at one end of the primary winding, and is connected to the collector of the contact transistor 1 at the other end thereof. A flyback transformer 12 in which one end of the wire is connected to the anode of the cathode ray tube through a high voltage rectifying diode 13 and the other end is grounded through a beam current detection resistor 14, and a high voltage HV output to the anode of the cathode ray tube. Alternatively, a high voltage detector 17 for detecting a voltage proportional to HV, a smoothing capacitor 15 for smoothing the voltage detected by the resistor 14, and a smoothed DC power source. Is input to invert the polarity, an analog / digital converter 21 that inputs the output of the polarity inversion circuit 20 and outputs it as digital data, and digital data of the converter 21 is input to perform arithmetic processing. Arithmetic unit 22 and the arithmetic unit 22
Digital / analog converter 23 which inputs the output of the converter and outputs it as an analog voltage, an amplifier circuit 24 which inputs the output of the converter 23 and amplifies it, and the output of the amplifier circuit 24 A horizontal deflection amplitude controller 1 for controlling the voltage V9 across the S-shaped correction capacitor 9 by supplying the output to the common connection point of the modulation coil 8 and the S-shaped correction capacitor 9.
0, the voltage detected by the high voltage detection resistor 17 is input to the power supply voltage control circuit 11 to control the output voltage VCC thereof to be constant so that the high voltage HV is constant and the display screen The horizontal deflection circuit is configured to correct the fluctuation of the horizontal amplitude due to the fluctuation of the output voltage VCC caused by the change of the luminance. Also, the arithmetic unit 2
Information on the horizontal deflection frequency is input to 2 and the correction amount of the horizontal amplitude may be changed according to the horizontal deflection frequency.

[0015]

In the horizontal deflection circuit of the present invention, the analog voltage detected by the beam current detection resistor is converted into digital data. The digital data is arithmetically processed by the arithmetic unit to be output as digital data, and the analog data is again generated. Since it is configured to be input to the horizontal deflection amplitude controller after being converted to, the optimum characteristics for correction are set to the voltage across the S-shaped correction capacitor by processing the digital data output from the analog / digital converter. Can be given. Further, even when the characteristics of the flyback transformer are changed, it is possible to easily obtain the optimum characteristics for correction simply by changing the coefficient of the arithmetic expression of the arithmetic unit.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG. The same components as those of the conventional horizontal deflection circuit are represented by the same symbols. In the figure, the circuit components that characterize the present invention are a polarity inverting circuit indicated by 20, an analog / digital converter 21; an arithmetic unit 22; a digital / analog converter 23; and an amplifier 24. . still,
The high voltage detector 17 is not limited to the circuit example shown in FIGS. 1 and 6, and may detect the output of the tertiary winding of the FBT 12 by rectifying it, or may detect it from the middle of the bleeder resistance inside the FBT 12. You may.

The negative DC voltage IV detected and smoothed by the beam current detecting resistor 14 is converted into a positive voltage by the polarity inverting circuit 20 and output from the analog / digital converter 21 as digital data. This digital data is output in the arithmetic unit 22 as digital data that has been arithmetically processed so as to obtain the characteristics (see FIG. 5) required by the preset arithmetic expression. Then, after being converted again into an analog voltage by the digital / analog converter 23, it is amplified by the amplifier circuit 24 so as to obtain an appropriate correction voltage, and the horizontal deflection amplitude controller
It is connected to be input to 0.

In the horizontal deflection circuit configured as described above, the high voltage HV can be controlled to be constant with respect to the luminance change of the display screen as in the conventional horizontal deflection circuit, and the horizontal amplitude caused by the luminance change of the display screen can be controlled. The variation can be easily corrected as follows.

Now, when a horizontal deflection current flows through the horizontal deflection coil 6 of the horizontal deflection circuit, a negative voltage IV proportional to the beam current IA is detected by the beam current detection resistor 14 and smoothed by the smoothing capacitor 15. Then, the DC voltage IV smoothed by the capacitor 15 is input to the polarity inversion circuit 20, converted into the positive voltage IV, and input to the analog / digital converter 21. From the analog / digital converter 21 to which the positive voltage IV is input, 8-bit digital data corresponding to the input analog voltage positive voltage IV is output. And
This 8-bit digital data is input to the arithmetic unit 22, and the arithmetic expression DOUT = √ ((DIN-M) · N /
P (however, DOUT is the output data of the arithmetic unit 22,
DIN indicates input data of the arithmetic unit 22, and M,
N and P are coefficients that can be adjusted in accordance with variations in horizontal amplitude of the display screen. Is converted into digital data suitable for horizontal amplitude correction and input to the digital / analog converter 23. Then, the voltage is again converted into an analog voltage, amplified by the amplifier circuit 24 so as to obtain an appropriate correction voltage, and then input to the horizontal deflection amplitude controller 10, where the second S-shaped signal is input to the horizontal deflection amplitude controller 10. The voltage V9 across the correction capacitor 9 is controlled to be the correction voltage having the characteristic shown in FIG. In this way, it is possible to easily obtain the correction voltage having the optimum characteristic for the change in the luminance of the display screen, correct the fluctuation of the horizontal amplitude, and improve the image quality.

By inputting horizontal deflection frequency information to the arithmetic unit 22 such as through a frequency / voltage converter, it becomes possible to change the horizontal amplitude correction amount according to the horizontal deflection frequency, and a multi-scan type cathode ray tube display A horizontal deflection circuit suitable for the device can be obtained.

[0021]

As described above, according to the horizontal deflection circuit of the present invention, it is possible to easily correct the fluctuation of the horizontal amplitude due to the brightness change of the display screen with a simple circuit configuration. Further, even if variations occur in each cathode ray tube display device or changes in the characteristics of the flyback transformer, these variations can be easily corrected simply by changing the coefficient of the arithmetic expression in the arithmetic unit. As a result, it is possible to obtain an inexpensive cathode ray tube display device having uniform characteristics, excellent image quality.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a horizontal deflection circuit of the present invention.

FIG. 2 is a characteristic diagram of high voltage with respect to changes in beam current.

FIG. 3 is a characteristic diagram of horizontal amplitude with respect to changes in beam current.

FIG. 4 is a characteristic diagram of a voltage across a beam current detection resistor with respect to a change in beam current.

FIG. 5 is a characteristic diagram of the output voltage of the polarity inversion / amplification circuit with respect to changes in beam current.

FIG. 6 is a circuit diagram showing a conventional example.

[Explanation of symbols]

 1 horizontal deflection output transistor 2,3 damper diode 4,5 resonance capacitor 6 horizontal deflection coil 7,9 S-shaped correction capacitor 8 modulation coil 10 horizontal deflection amplitude adjuster 11 power supply voltage control circuit 12 flyback transformer 13 high voltage rectifier diode 14 beam Current detection resistor 15 Smoothing capacitor 16, 17 High voltage detector 19 Polarity inversion / amplification circuit 20 Polarity inversion circuit 21 Analog / digital converter 22 Operation unit 23 Digital / analog converter 24 Amplification circuit + B power supply VCC Power supply voltage IA of horizontal deflection circuit Beam current IV Beam current Detection voltage across detection resistor HV High voltage V9 Voltage across second S-shaped correction capacitor

Claims (2)

[Claims] 1. At least a horizontal deflection coil 6 and a first S
A series circuit composed of a letter correction capacitor 7, a parallel circuit composed of a first damper diode 2 and a first resonance capacitor 4, a series circuit composed of a modulation coil 8 and a second S-shaped correction capacitor 9, and a second damper. A horizontal deflection output transistor 1 having a grounded emitter, which is connected in series with a parallel circuit composed of a diode 3 and a second resonance capacitor 5 and is connected between a collector and an emitter, and one end of a primary winding is connected to a power supply voltage control circuit 11 Via the power supply + B, the other end is connected to the collector of the transistor 1, one end of the secondary winding is connected to the anode of the cathode ray tube via the high voltage rectifier diode 13, and the other end is connected to the beam current detection resistor 14. And a grounded flyback transformer 12, and a high voltage detector 17 for detecting a high voltage HV output to the anode of the cathode ray tube or a voltage proportional to HV. A smoothing capacitor 15 that smoothes the voltage detected by the resistor 14, a polarity inverting circuit 20 that inputs the smoothed DC voltage to invert the polarity, and an output of the polarity inverting circuit 20 that is input and output as digital data. Analog / digital converter 21, an arithmetic unit 22 for inputting digital data of the converter 21 to perform arithmetic processing, and a digital / analog converter for inputting the output of the arithmetic unit 22 and outputting it as an analog voltage. 23, an amplifier circuit 24 that inputs and amplifies the output of the converter 23, and an output of the amplifier circuit 24, and supplies the output to the common connection point of the modulation coil 8 and the S-shaped correction capacitor 9. The voltage detected by the high-voltage detector 17 comprises a horizontal deflection amplitude controller 10 for controlling the voltage V9 across the S-correction capacitor 9 at least. It is input to the power supply voltage control circuit 11 to control the output voltage VCC thereof to make the high voltage HV constant and to correct the fluctuation of the horizontal amplitude due to the fluctuation of the output voltage VCC caused by the brightness change of the display screen. A horizontal deflection circuit characterized by being configured. 2. The horizontal deflection circuit according to claim 1, wherein information on a horizontal deflection frequency is input to the arithmetic unit 22, and a correction amount of the horizontal amplitude is changed according to the horizontal deflection frequency.