JPH11341299A - Bidirectional deflection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the linearity of a scanning line by a simple circuit without using an auxiliary coil by superimposing the current of a polarity opposite to a horizontal deflection current on a vertical deflection current. SOLUTION: The fluctuation value of peak-to-peak over several hundreds V of the voltage waveform VH of a horizontal deflection drive circuit 4 is converted to about 5 V by a voltage adjustment circuit 15, inverted output (m) is supplied to a drive circuit 16 and an output drive voltage (n) is supplied to a transformer 17 for correction current superimposing. Since a phase is delayed for 90 deg. by a voltage for a current flowing to a coil, a correction current component ILV flowing to a vertical deflection yoke LV becomes the opposite phase of a horizontal deflection current component indicated by a broken line (p) on the vertical deflection current. Thus, a cancellation current ILV is superimposed on the vertical deflection current ILV, horizontal deflection components are cancelled and excellent linearity characteristics are obtained. Thus, the linearity is improved without providing the auxiliary coil requiring the drive circuit of large output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the linearity of scanning lines of a video display device for displaying bidirectional reciprocating scanning lines on a computer display or a television receiver.

[0002]

2. Description of the Related Art A conventional bidirectional deflection system is disclosed in
The configuration found in JP-A-203238 is common. The basic configuration and operation at this time will be described with reference to FIGS. In FIG. 3, reference numeral 1 denotes a double-speed processing of a video signal to display a normal video signal in a reciprocating manner to convert the video signal into a double-speed luminance signal Y and color difference signals Pb and Pr, and to drive a horizontal deflection circuit of a reciprocating deflection system. A signal processing circuit that outputs the control signal of the above, a circuit 2 that converts the Y, Pb, and Pr signals into RGB and amplifies and outputs the same, and 3 a CRT,
4 is a horizontal deflection drive circuit of a reciprocating deflection system that outputs pulses for alternately driving the switch elements 5 and 6;
Reference numerals 5 and 6 denote switch elements for horizontal deflection output, reference numerals 7 and 8 denote diodes, reference numeral 9 denotes a deflection distortion correction circuit, reference numeral 10 denotes an S-shaped correction capacitor Cs, reference numeral 11 denotes a horizontal deflection yoke LH, and reference numeral 12 denotes a current ILH flowing through the horizontal deflection yoke. A correction circuit for detecting and correcting horizontal linearity, 13 is a vertical deflection output circuit, and 14 is a vertical deflection yoke LV.

FIG. 4 shows waveforms at various points in FIG.
Waveforms (a) to (f) correspond to points a to f in FIG. (A) is a normal video signal V1fH, (b) is a video signal V2fH after double-speed processing, and (c) is a control signal VHdri for driving a horizontal deflection circuit of a reciprocating deflection system.
ve, (d) is the feedback signal VFB, (e) is the horizontal deflection current ILH flowing through the horizontal deflection yoke LH, (f)
Is a terminal voltage VH generated at both ends of the S-shaped capacitor Cs.

In FIG. 5, (g) is a vertical deflection voltage VV which is an output voltage of the vertical deflection output circuit 13, (h) is a current ILV flowing through the vertical deflection yoke 14 (LV), and (g)
And (h) show the vertical time rate, that is, the time axis in a form corresponding to the period of the vertical synchronization signal. (I) is (g)
The waveform in the dotted line is enlarged in the horizontal time rate, that is, the time axis is enlarged and displayed according to the cycle of the horizontal synchronization signal.
(J) is the horizontal deflection current ILH.

[0005] When a video signal is input, the signal processing circuit 1 double-processes the video signal, and outputs the signal in reverse during retrace. It also outputs necessary control signals to the horizontal deflection drive circuit 4. The horizontal deflection drive circuit 4 outputs a pulse for driving the switch elements 5 and 6 alternately. When the switch element 5 is turned on, a voltage is applied to the S-shaped correction capacitor 10 and the horizontal deflection yoke 11. The capacitance Cs of the S-shaped capacitor 10 and the horizontal deflection yoke 1
The following relationship is established between the inductances LH.

Fh = 1 / 2π√Cs · LH (Equation 1) Since Cs and LH are set so that the resonance frequency fh and the frequency of the input video signal are substantially equal to each other, The current and voltage flowing through the deflection yoke 11 resonate in a sine wave shape as shown in (e) and (f).

The broken line shown in FIG. 5 (i) shows the vertical deflection current ILVideal having ideal linearity. At this time, the locus of the scanning line displayed on the screen of the CRT 3 is shown in FIG. Looks like However, the horizontal deflection yoke and the vertical deflection yoke have a crosstalk component of a horizontal deflection current of about 2 mA peak-to-peak with a one-cycle variation as shown by the solid line in FIG. As described above, the linearity of the scanning lines displayed on the screen of the CRT cannot be maintained, and in particular, the reciprocating scanning lines are overlapped at both left and right ends of the screen.

As a method for improving the linearity of the scanning lines and the parallelism of the scanning lines, as disclosed in JP-A-6-14211, an auxiliary coil separate from the conventional deflection coil is provided, There was a method of improving linearity and parallelism.

[0009]

However, a tendency of recent television receivers is to further enhance contrast on a bright screen in order to reproduce a high-definition image. Therefore, as a characteristic required for a cathode ray tube, the beam current increases, and the method of providing the auxiliary coil disclosed in the above publication has a problem that a drive circuit of the auxiliary coil requires a large output and is complicated.

The present invention solves the above problem by improving the linearity of a scanning line, and provides a simple circuit that does not use an auxiliary coil for improving linearity.

[0011]

In order to solve the above-mentioned problems, the present invention provides: (1) a bidirectional deflection of an image display device which displays an image by reciprocation of a scanning line by forming a horizontal deflection current into a sine wave shape; A bidirectional deflection system characterized by improving the linearity of scanning lines by superimposing a current having a polarity opposite to that of a horizontal deflection current on a vertical deflection current.

(2) an S-shaped correction capacitor, a horizontal deflection yoke connected in series to the capacitor, a horizontal deflection output circuit for controlling a current flowing through the capacitor and the deflection yoke, and a vertical deflection output circuit. A correction means for superimposing the reverse polarity component of the horizontal deflection current on the vertical deflection current, a drive circuit for the correction means, and a vertical deflection yoke, wherein a sine wave current caused by a resonance phenomenon of the S-shaped capacitor and the horizontal deflection yoke As a horizontal deflection current, wherein a horizontal deflection voltage generated in the horizontal deflection yoke is input to a drive circuit of the correcting means.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a bidirectional deflection system of an image display device for displaying an image by reciprocating scanning lines by making a horizontal deflection current into a sine wave shape.
A bidirectional deflection system characterized by improving the linearity of the scanning line by superimposing a current of the opposite polarity to the horizontal deflection current on the vertical deflection current. Since the component is corrected, no new auxiliary coil is required to improve the linearity of the scanning line,
In addition, since the sine wave deflection system is used, the circuit is simplified by using a sine wave generated in the deflection circuit.

According to a second aspect of the present invention, there is provided an S-shaped correction capacitor, a horizontal deflection yoke connected in series to the capacitor, a horizontal deflection output circuit for controlling a current flowing through the capacitor and the deflection yoke, A vertical deflection output circuit, a correction unit that superimposes the reverse polarity component of the horizontal deflection current on the vertical deflection current, a drive circuit of the correction unit, and a vertical deflection yoke, wherein the S-shaped capacitor and the horizontal deflection yoke are provided. A bidirectional deflection system using a sinusoidal current due to a resonance phenomenon as a horizontal deflection current, wherein a horizontal deflection voltage generated in the horizontal deflection yoke is input to a drive circuit of the correction means. The circuit corrects the horizontal deflection component superimposed on the vertical deflection current, so a new auxiliary coil is used to improve the linearity of the scanning line. It has a feature that the circuit is simplified by using a sine wave generated in the deflection circuit for not required and is a sine wave deflection system.

An embodiment of the present invention will be described below with reference to FIGS. The bidirectional deflection system of the present invention will be described with reference to an example of a deflection circuit constituting a television receiver.

FIG. 1 is a block diagram of the deflection system of the present invention. In FIG. 1, reference numerals 1 to 14 are the same as those in FIG. Reference numeral 15 denotes a voltage adjustment circuit, 16 denotes a drive circuit, and 17 denotes a transformer for superimposing a correction current on a vertical deflection current. FIG. 2 shows waveforms at points k to p in FIG.
(K) is the horizontal deflection current ILH, (l) is the horizontal deflection voltage V
H and (m) indicate the output voltage Vcance of the voltage adjustment circuit 15.
1 and (n) indicate the output voltage Vcance of the drive circuit 16
Lout, (o) is the correction current component ILVcancel flowing through the vertical deflection yoke, and the solid line of (p) is the vertical deflection current ILVideal after correction, and the broken line is the vertical deflection current ILV before correction.

The operation of the horizontal deflection circuit is the same as that of the conventional example described with reference to FIGS. The phase of the horizontal deflection voltage waveform VH shown in (l) is 90 degrees ahead of the phase of the horizontal deflection current waveform ILH shown in (k). Since the fluctuation of the horizontal deflection voltage waveform VH is several hundred volts peak-to-peak, the voltage adjusting circuit 15 converts and inverts this voltage to about 5 volts and outputs it as shown in (m).

The drive circuit 16 outputs a drive voltage as shown in FIG.
Since the current flowing through the coil has a phase delay of 90 degrees from the voltage, a current ILVcancel as shown in (o) flows through the vertical deflection yoke as a correction current component. The phase of the horizontal deflection current component on the deflection current ILV is opposite to that of the horizontal deflection current component.
By superimposing the LVcancel, the vertical deflection current ILVideal has a good linearity characteristic in which the horizontal deflection component is canceled as shown by the solid line in (p).

[0019]

As described above, according to the power supply device of the present invention, the linearity of the vertical deflection current can be improved with a simple circuit without using an auxiliary coil.

[Brief description of the drawings]

FIG. 1 is a block diagram of a deflection circuit according to an embodiment of the present invention.

FIG. 2 is a waveform chart of each part of the deflection circuit according to the embodiment of the present invention.

FIG. 3 is a block diagram of a conventional deflection circuit.

FIG. 4 is a waveform diagram of each part of a conventional deflection circuit.

FIG. 5 is a waveform diagram of each part of a conventional deflection circuit.

FIG. 6 is a diagram showing a trajectory of a scanning line having ideal linearity on a screen surface;

FIG. 7 is a diagram showing a trajectory of a scanning line on a screen by a conventional deflection circuit.

[Description of Signs] 1 signal processing circuit 2 RGB output circuit 3 CRT 4 horizontal deflection drive circuit 5, 6 switch element 7, 8 diode 9 distortion correction circuit 10 S-shaped capacitor 11 horizontal deflection yoke 12 linearity correction circuit 13 vertical deflection output circuit 14 Vertical deflection yoke 15 Voltage adjustment circuit 16 Drive circuit 17 Correction current superposition circuit

Claims (2)

[Claims] 1. A bidirectional deflection system of an image display device for displaying an image in a reciprocating manner of a scanning line by making a horizontal deflection current a sine wave shape, wherein a current having a polarity opposite to the horizontal deflection current is superimposed on a vertical deflection current. A bi-directional deflection system having improved scan line linearity. 2. An S-shaped correction capacitor, a horizontal deflection yoke connected in series to the capacitor, a horizontal deflection output circuit for controlling a current flowing through the capacitor and the deflection yoke, a vertical deflection output circuit, A correcting means for superposing a reverse polarity component of the deflection current on the vertical deflection current, a drive circuit of the correction means, and a vertical deflection yoke;
A bidirectional deflection system using a sinusoidal current due to the resonance phenomenon of the horizontal deflection yoke as a horizontal deflection current, wherein a horizontal deflection voltage generated in the horizontal deflection yoke is input to a drive circuit of the correction means. A two-way deflection system.