JPH05336389A - Deflection circuit - Google Patents

Abstract

PURPOSE:To obtain a deflection circuit capable of forming a scanning line uniformly and in parallel as the whole display image plane by varying correction quantity following up the variation of a vertical deflecting current varying by S-shape correction. CONSTITUTION:A driving power source VP is supplied to a transistor 14 via the secondary coil of a transformer 6, and a correction current ITR1 changing to a sawtooth wave shape synchronizing with a horizontal synchronizing signal HD, and whose amplitude being changed in parabolic shape following a vertical synchronizing signal can be generated. The correction current ITR1 is superimposed on the primary current ITR2 of the transformer 6 via the transformer 6. Thereby, the amplitude of the correction current ITR1 is reduced on the upper and lower terminal sides of a display image plane, and it is superimposed on the primary current ITR2 of the transformer 6, therefore, the correction quantity at the upper and lower terminal sides of the display image plane is decreased by adjusting a semi-fixed resistor VR1. Therefore, the correction quantity becomes variable following up the variation of the vertical deflecting current varying by the S-shape correction in the deflection circuit 20.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Industrial Application Conventional Technology (FIGS. 5 and 6) Problem to be Solved by the Invention (FIGS. 7 and 8) Means for Solving the Problem (FIG. 1) Action (FIG. 1) Embodiment (1) Configuration of Embodiment (FIGS. 1 to 4) (2) Effect of Embodiment (3) Other Embodiment Effect of Invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection circuit, and is particularly suitable for application to a bidirectional vertical deflection circuit.

[0003]

2. Description of the Related Art Conventionally, in a deflection circuit of this type, a deflection circuit for driving a horizontal deflection yoke (hereinafter referred to as a bidirectional deflection circuit) so that a current value changes symmetrically before and after a predetermined time point. A deflection circuit) has been proposed (US Pat. No. 4,672,449).

This bidirectional deflection deflecting circuit has been proposed in which the deflection yoke is driven by a sine wave signal to reduce the power required for deflection with a simple structure (Japanese Patent Laid-Open No. 3-30083). 70369).

In this bidirectional deflection, the vertical deflection coil is driven by a mere sawtooth wave signal by forming a display image by scanning the forward path and the backward path, as shown in FIG. The return scan lines are not arranged in parallel on the display screen M but are displayed so as to overlap each other at both ends of the display screen M (that is, by pairing). Therefore, as shown in FIG. 6, the deflection circuit is configured to prevent the occurrence of pairing by modulating the current value of the vertical deflection current into a sawtooth wave in synchronization with the horizontal synchronizing signal. 1 has been proposed (Japanese Patent Laid-Open No. 3-145378).

That is, the deflection circuit 1 uses the vertical synchronizing signal VD.
To a sawtooth wave signal generation circuit 2 to generate a sawtooth wave signal S _TR whose signal level changes in a sawtooth wave shape in synchronization with the vertical synchronizing signal. The amplifier circuit 4 is formed by a low impedance output power amplifier circuit of a differential amplifier circuit type, inputs the sawtooth wave signal S _TR to the non-inverting input end side, and outputs the output signal to the primary coil of the transformer 6, the vertical coil. Deflection coil L,
It is grounded via the S-shaped correction capacitor 8 and the resistor 10.

The feedback circuit 12 includes an S-shaped correction capacitor 8
Is detected and the detection result is fed back to the inverting input terminal of the amplifier circuit 4, whereby the deflection circuit 1 vertically changes so that the current value changes in accordance with the signal level of the sawtooth wave signal S _TR. The deflection coil 8 is driven.

Further, at this time, the deflection circuit 1 connects the S-correction capacitor 8 in series with the vertical deflection coil 8 and detects the terminal voltage thereof to form a feedback loop, thereby forming an S-shape on the display screen. It is designed to correct distortion.

Further, the deflection circuit 1 generates a horizontal synchronizing signal H _D whose signal level rises at the timing of starting the forward scanning and the backward scanning, and supplies this horizontal synchronizing signal H _D to the grounded-emitter transistor 14. Transistor 14
Connects the collector output to the secondary coil of the transformer 6, and the resonance capacitor 16 and the damper diode 18
Ground with. Further, the deflection circuit 1 connects the power source voltage V _CC to the secondary coil of the transformer 6 via a series regulator circuit formed by the reference power source 20 and the transistor 22, and thereby the predetermined voltage is passed via the transformer 6. A voltage driving power supply is supplied to the transistor 14.

As a result, the transistor 14 raises the voltage V _P between the secondary coil terminals of the transformer 6 in pulse form in synchronization with the horizontal synchronizing signal, and synchronizes the secondary coil side current of the transformer 6 with the horizontal synchronizing signal. And change it into a sawtooth wave. As a result, the deflection circuit 1 corrects the current value of the vertical deflection current I _DY so as to change stepwise, and drives the vertical deflection coil L with this vertical deflection current I _DY to prevent pairing from occurring. It is designed to get you.

[0011]

However, in the deflection circuit 1, the scanning lines cannot be formed uniformly and in parallel on the entire display screen, and there is still a problem in practical use.

That is, as shown in FIG. 7, when the vertical deflection coil L and the S-th order capacitor 8 are connected in series to perform the S-th order correction, in the vertical deflection current I _L (FIG. 7A), the scanning start end And the current value changes slowly on the end side.

When the current value of the vertical deflection current I _L is corrected by the sawtooth wave signal S1 (FIG. 7B) synchronized with the horizontal synchronization signal (FIG. 7C), the deflection current I _DY after correction is corrected. Causes the current value to be overcorrected on the upper and lower ends of the display screen. Therefore, as shown in FIG. 8, in the display screen M, the scanning lines are formed to be inclined at the upper and lower ends of the screen, so that the scanning lines cannot be formed uniformly and the resolution is lowered.

The present invention has been made in consideration of the above points, and is intended to propose a deflection circuit which can be applied to a vertical deflection circuit of bidirectional deflection to uniformly form a scanning line.

[0015]

In order to solve such a problem, in the first invention, a deflection circuit 20 for correcting an S-shaped characteristic of a display screen by connecting an S-shaped correction capacitor 8 in series with a vertical deflection coil L is provided. in generates a raster correction signal I _TR1 whose signal level changes in sawtooth wave in synchronism with the horizontal synchronizing signal H _D, and the amplitude of the whole in synchronization with the vertical synchronizing signal V _D varies parabolically, raster Correction signal I _TR1 ,
And the vertical deflection coil L is driven based on the first sawtooth wave signal I _TR2 whose signal level changes in a sawtooth wave shape in synchronization with the vertical synchronization signal V _D.

Further, in the second invention, the horizontal synchronizing signal H is generated by the predetermined sawtooth wave signal generating circuits 14, 16 and 18.
After generating the second sawtooth signal whose signal level changes in a sawtooth waveform in synchronization with _D , the parabolic signal generation circuit 22
Then, a parabolic signal SP whose signal level changes in a parabolic shape in synchronization with the vertical synchronizing signal V _D is generated, and the parabolic signal SP modulates the second sawtooth wave signal to generate the raster correction signal I.
Generate _TR1 .

Further, in the third invention, the parabolic signal generation circuit 22 generates the parabolic signal SP based on the voltage across the terminals of the S-shaped correction capacitor 8.

Further, in the fourth invention, the parabolic signal generating circuit integrates the vertical synchronizing signal V _D to generate a parabolic signal SP.

Further, in the fifth invention, the vertical deflection coil L is formed by connecting the primary windings of a predetermined transformer 6 in series.
Inputs the deflection current I _TR2 of the current value changes following through the following winding of the signal level of the first sawtooth signal I _TR2, raster correction signals I _TR1 secondary winding of the transformer 6
To input the raster correction signal I _TR1 and the first
Driven based on the sawtooth wave signal I _TR2 .

[0020]

[Action] in synchronization with the horizontal synchronizing signal H _D signal level changes in sawtooth wave, and the amplitude of the whole in synchronization with the vertical synchronizing signal V _D generates a raster correction signal I _TR1 which changes parabolically, Raster correction signal I _TR1 and vertical sync signal V _D
If the vertical deflection coil L is driven based on the first sawtooth wave signal I _TR2 whose signal level changes in a sawtooth wave shape in synchronization with, the correction amount follows the change in the vertical deflection current due to the S-shaped correction. Can be varied so that uniform and parallel scan lines can be formed across the screen.

At this time, after the second sawtooth wave signal whose signal level changes in a sawtooth wave shape in synchronization with the horizontal sync signal H _D , the signal level is changed in a parabola shape in synchronization with the vertical sync signal V _D. The raster correction signal I _TR1 can be easily generated by generating the changing parabolic signal SP and modulating the second sawtooth wave signal with the parabolic signal SP.

Further, if the parabolic signal SP is generated based on the voltage between the terminals of the S-shaped correction capacitor 8, the parabolic signal SP can be easily generated.

Also, the parabolic signal SP can be easily generated by integrating the vertical synchronizing signal.

Further, the vertical deflection coil L is connected to the transformer 6
Series connected to the next winding, by correcting the first sawtooth signal I _TR2 in the transformer 6 in a raster correction signal I _TR1, a first sawtooth signal I _TR2 raster correction signals I _TR1 easily Can be corrected.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of the embodiment In FIG. 1 in which parts corresponding to those in FIG. 6 are assigned the same reference numerals, 20 denotes a deflection circuit as a whole, and a terminal of the S-order correction capacitor 8 is provided via a feedback circuit 22. By detecting the voltage and feeding back the detection result to the amplifier circuit 4, the S-order distortion of the display screen is corrected and the vertical deflection coil L is driven.

Further, as shown in FIG. 2, the feedback circuit 22 detects the potential difference between both ends of the S-order correction capacitor 8 and thereby the parabolic signal SP (FIG. 2 (A )) Is generated (in FIG. 2, the symbol V represents one vertical scanning period).

The power supply modulation circuit 23 is a predetermined power supply circuit 24.
Modulating the DC power supply V _CC output by the parabolic signal SP from, thereby generating a modulated power VP of the voltage changes parabolically from a predetermined DC level (FIG. 2 (B)),
This modulation power supply VP is output to the transformer 6.

That is, as shown in FIG. 3, in the power supply modulation circuit 23, the parabolic signal SP is input to the buffer circuit composed of the resistor R1 and the transistor Q1, and the emitter output of this transistor Q1 is transferred to the transistor Q2 via the coupling capacitor C1. Output to. The transistor Q2 is
The resistors R2 to R4 and the semi-fixed resistor VR1 form an emitter-grounded amplifier circuit having a predetermined gain, and the semi-fixed resistor VR1 can be adjusted to adjust the gain.

As a result, the power supply modulation circuit 23 amplifies the parabolic signal SP by the transistor Q2 and then removes the noise component mixed in from the horizontal deflection coil or the like by the low-pass filter circuit of the resistor R5 and the capacitor C2.

Further, the power supply modulation circuit 23 gives the output signal of the low-pass filter circuit to the transistor Q3, where the transistor Q3 forms a buffer circuit together with the resistor R3. As a result, the power supply modulation circuit 23 removes the noise component from the parabolic signal SP, and then the transistor Q3,
Output to the transistor Q5 via the coupling capacitor C3.

The transistor Q5 is a transistor Q6,
Together with the resistors R8 and R9, a direct current buffer circuit having an emitter follower circuit configuration is formed, and its base potential is the resistor R7,
The voltage is determined by the semi-fixed resistor VR2 and the transistor Q4. As a result, the power supply modulation circuit 23 forms a DC clamp circuit with the transistors Q4 to Q6, the resistors R7 to R9, and the semi-fixed resistor VR2, and has a DC level determined by the semi-fixed resistor VR2 and the parabolic signal SP.
To generate a driving power supply VP whose AC level changes.

Thus, the deflection circuit 20 uses this driving power source.
VP through the secondary coil of the transformer 6 to the transistor 1
4 and the horizontal synchronizing signal H_DIn a sawtooth wave in synchronization with
Change and the overall amplitude follows the vertical sync signal and
Correction current I changing in a volatile shape _TR1(Figure 2 (C)) is generated
To do. As a result, the deflection circuit 20 passes through the transformer 6.
This correction current I_TR1Is the primary current I of the transformer 6_TR2
(FIGS. 2D and 2E).

As a result, in the deflection circuit 20, the amplitude of the correction current I _TR1 can be reduced on the upper and lower ends of the display screen,
When superposed on the primary current I _TR2 of the transformer 6, the semi-fixed resistor VR1 can be adjusted to reduce the correction amount at the upper and lower ends of the display screen. As a result, in the deflection circuit 20, the correction amount can be changed by following the change in the vertical deflection current that changes due to the Sth-order correction, and the deflection of the vertical deflection coil L is performed so that the current value changes stepwise on the entire screen. Current I _DY
Can be corrected.

As a result, as shown in FIG. 4, the deflection circuit 2
At 0, overcorrection of the vertical deflection current can be prevented even at the upper and lower ends of the screen, and the scanning lines can be formed uniformly and in parallel on the entire display screen.

(2) Effects of the Embodiments With the above configuration, the amplitude of the sawtooth wave signal synchronized with the horizontal synchronizing signal is modulated with the parabolic signal synchronized with the vertical synchronizing signal to generate the correction signal. By superimposing the correction signal on the vertical deflection current and correcting the vertical deflection current so that the current value changes stepwise, the correction amount can be changed according to the change in the vertical deflection current that changes due to the S-th order correction. As a result, scanning lines can be formed uniformly and in parallel on the entire display screen.

(3) Other Embodiments In the above-described embodiments, the case where the parabolic signal is generated by the potential difference between the S-shaped correction capacitors has been described. The parabolic signal may be generated by multiple integration.

Further, in the above-mentioned embodiment, the case where the correction signals are current-added by using the transformer 6 has been described, but the present invention is not limited to this, and voltage addition may be made at the input side of the amplifier circuit 4, for example. good.

[0039]

As described above, according to the present invention, the sawtooth wave signal synchronized with the horizontal synchronizing signal is modulated by the parabolic signal synchronized with the vertical synchronizing signal, and the vertical deflection current is obtained by the resulting raster correction signal. The correction amount can be varied by following the change in the vertical deflection current that changes due to the S-shaped correction, and thus a deflection circuit that can form scanning lines uniformly and in parallel on the entire display screen can be obtained. it can.

[Brief description of drawings]

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

FIG. 2 is a signal waveform diagram for explaining the operation.

FIG. 3 is a connection diagram showing a power supply modulation circuit.

FIG. 4 is a schematic diagram showing a distribution of scanning lines.

FIG. 5 is a schematic diagram for explaining pairing.

FIG. 6 is a block diagram showing a conventional vertical deflection circuit.

FIG. 7 is a signal waveform diagram for explaining the operation.

FIG. 8 is a schematic diagram used to describe a disorder of a scanning line.

[Explanation of symbols]

1, 20 ... Deflection circuit, 4 ... Amplification circuit, 6 ... Transformer, 8 ... S-correction capacitor, 14 ... Transistor, 16 ... Capacitor, 18 ... Diode, 22 ...
... Feedback circuit, 23 ... Power supply modulation circuit.

Claims (5)

[Claims] 1. A deflection circuit for connecting an S-shaped correction capacitor in series with a vertical deflection coil to correct the S-shaped characteristic of a display screen, wherein the signal level changes in a sawtooth wave shape in synchronization with a horizontal synchronizing signal, and A first sawtooth-shaped signal whose level changes in a sawtooth waveform in synchronization with the raster correction signal and the vertical synchronization signal is generated in synchronization with the vertical synchronization signal. A deflection circuit for driving the vertical deflection coil based on a wave signal. 2. A second sawtooth wave signal generating circuit, wherein the signal level is changed to a sawtooth wave shape in synchronization with a horizontal synchronizing signal.
After generating the sawtooth wave signal of, the parabolic signal generation circuit generates a parabolic signal whose signal level changes in a parabolic shape in synchronization with the vertical synchronization signal, and the parabolic signal generates the second sawtooth wave signal. The deflection circuit according to claim 1, wherein the deflection circuit is modulated to generate the raster correction signal. 3. The deflection circuit according to claim 2, wherein the parabolic signal generation circuit generates the parabolic signal based on a voltage between terminals of the S-shaped correction capacitor. 4. The deflection circuit according to claim 2, wherein the parabolic signal generation circuit integrates the vertical synchronization signal to generate the parabolic signal. 5. The vertical deflection coil is configured such that primary windings of a predetermined transformer are connected in series, and the first winding is provided through the primary windings.
By inputting the deflection current whose current value changes in accordance with the signal level of the sawtooth wave signal of (1) and inputting the raster correction signal to the secondary winding of the transformer, the raster correction signal and the first The deflection circuit according to claim 1, 2, 3, or 4, wherein the deflection circuit is driven based on the sawtooth wave signal.