JPH08163389A - Horizontal pincushion distortion correction circuit - Google Patents

Abstract

PURPOSE: To provide the horizontal pincushion distortion correction circuit which satisfactorily corrects the raster distortion, which has a low distortion rate in both ends of the x-axis and has higher distortion rate in the middle part throughout the screen. CONSTITUTION: A horizontal output circuit is provided with the horizontal pincushion distortion correction circuit in the saturable reactor system which is provided with two saturable reactor transformers 10 and 11 different in characteristics. The horizontal pincushion distortion correction circuit in the saturable reactor system is inserted to the part where the horizontal deflection current of the horizontal output circuit flows. At this time, two saturable reactor transformers 10 and 11 different in characteristics have the same DC superposition characteristics as a linearity coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a left and right pincushion distortion correction circuit used for a television and a CRT display for a computer, and more particularly to a left and right pincushion distortion correction circuit for correcting a distortion in an intermediate portion between both ends of the x-axis and the center of the screen.

[0002]

2. Description of the Related Art As is well known, left and right pincushion distortion correction circuits have been proposed in various circuits such as (1) power supply modulation system, (2) diode modulator system, and (3) saturable reactor system.

Of these, the power source modulation method (1) has a large fluctuation in high voltage and is therefore widely used when a circuit system of deflection / high voltage separation is used. The diode modulator method of (2) has an advantage that there is little fluctuation in high voltage, and is therefore widely used in the recent 110 ° -deflection large color cathode ray tube. On the other hand, the saturable reactor method (3) has a drawback that the amount of pincushion distortion is different between the central portion and the peripheral portion of the screen due to the correction due to the superposition characteristics of the reactor transformer.

In recent years, flattening of the face plate panel of the color CRT has been popular, but the flattening tends to have an aspherical structure in consideration of the doming characteristics of the color CRT.

FIG. 5 is a diagram for explaining correction of a non-linear left and right pincushion distortion state of a color cathode-ray tube using a conventional aspherical structure panel, (a) showing a distortion state before correction, and (b). And (c) show raster correction states when the left and right pincushion distortions of (a) are corrected by the power supply modulation method.

As shown in FIG. 5A, the distortion state of the color cathode-ray tube using such an aspherical structure panel before correction of the left and right pincushion distortion is as shown in FIG. It does not change so much, and decreases sharply near the center of the screen. In other words, the ratio of the length from the center of the screen to the distortion is not constant, and there is a non-linear tendency that the distortion rate increases near the middle of the x-axis ends and the center of the screen (hereinafter referred to as the middle). .

When the left and right pincushion distortion shown in FIG. 5A is corrected by the power source modulation method, if the correction amount is determined by paying attention to the intermediate portion, as shown in FIG. Then, when the correction amount is determined by paying attention to both ends of the x-axis,
As shown in FIG. 5 (c), there is a defect that the correction remains in the middle portion, and so-called Inner-Kissen distortion remains. That is, the non-linear left and right pincushion distortion remains even after correction.

[0008]

As described above,
Non-linear left and right pincushion distortion correction circuits such as those that occur in a color cathode ray tube using an aspherical structure panel cannot be satisfactorily corrected by these left and right pincushion distortion correction circuits.

An object of the present invention is to solve the above-mentioned problems, and to satisfactorily correct the raster distortion such that the distortion rate is small at both ends of the x-axis and the distortion rate is increased in the middle part on the entire screen. It is to provide a left and right pincushion distortion correction circuit.

[0010]

In order to achieve the above object, a left and right pincushion distortion correction circuit of the present invention is a horizontal output circuit including a left and right pincushion distortion correction circuit, and the horizontal output circuit has different characteristics. It has a saturable reactor type left and right pincushion distortion correction circuit with two saturable reactor transformers.

The left and right pincushion distortion correction circuit of the present invention is
The saturable reactor type left and right pincushion distortion correction circuit,
It is inserted in a portion of the horizontal output circuit where a horizontal deflection current flows.

The left and right pincushion distortion correction circuit of the present invention is
The two saturable reactor transformers having different characteristics can have the same DC superposition characteristics as the linearity coil.

[0013]

The present invention having the above-mentioned structure has the following functions. (1) The horizontal deflection current flowing part of the horizontal output circuit including the left and right pincushion distortion correction circuits other than the saturable reactor system is
It has a saturable reactor type left and right pincushion distortion correction circuit including two saturable reactor transformers having different characteristics, and the saturable reactor type left and right pincushion distortion correction circuit is inserted in a portion of a horizontal output circuit where a horizontal deflection current flows. Therefore, it is possible to correct non-linear left and right pincushion distortions such as inner kissen, inner barrel, etc., good correction on all screens for raster distortion such that the distortion rate is small at both ends of the x-axis and the distortion rate increases at the middle part. It is possible to dramatically improve the raster distortion quality. (2) Since the two saturable reactor transformers having different characteristics have the same DC superposition characteristics as the linearity coil normally used in the horizontal deflection circuit, the characteristics are set to an appropriate value and also have the role of the linearity coil. This makes it possible to configure the circuit at a low cost because a dedicated linearity coil is unnecessary.

[0014]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a left and right pincushion distortion correction circuit according to an embodiment of the present invention. Figure 2
FIG. 3 is a characteristic diagram showing a DC superposition characteristic of the saturable reactor transformer in the configuration of FIG. 1, (a) showing a DC superposition characteristic of the first saturable reactor transformer, and (b) showing a second saturable reactor. The DC superposition characteristic of a transformer is shown. FIG.
FIG. 2 is a diagram showing a parabola-shaped current waveform obtained by converting the output voltage of the correction voltage generation circuit into a current by the voltage / current conversion circuit in the configuration of FIG. 1. FIG. 4 is a diagram for explaining the correction of the left and right pincushion distortion state using the configuration of FIG. 1, and FIG. 4A shows the left and right pincushion distortion after correction by the saturable reactor transformer according to an embodiment of the present invention, (B) shows a raster correction state when the left and right pincushion distortion of (a) is corrected by the power supply modulation method.

The configuration of this embodiment will be described with reference to FIG.
The correction voltage generating circuit 1 is a voltage wave required for distortion correction in the middle part.
The first voltage-current conversion circuit 2 and the second voltage-current
Output to the current conversion circuit 3. First voltage / current conversion circuit
The output of 2 is the primary winding of the first saturable reactor transformer 10.
Second voltage-current conversion circuit connected to one terminal of the line
The output of 3 is the primary of the second saturable reactor transformer 11
It is connected to one terminal of the winding. Also, the first
The other terminal of the primary winding of the sum reactor transformer 10 and
The other side of the primary winding of the second saturable reactor transformer 11
The terminal is the power supply V _B (V_B ≈ 10-20V_DC) Is connected to
ing. First voltage-current conversion circuit 2 and second voltage
The current output from the current conversion circuit 3 is the first
Of the saturable reactor transformer 10 and the second saturable
Flows to the primary winding of the sum reactor transformer 11.

The modulation circuit 4 has a power source V _A (V _A ≈40-2)
A parabolic wave for correcting left and right pincushion distortion is superimposed on the power supply voltage of 00V _DC ), and the superimposed output is input to one terminal of the flyback transformer 5. The output of a horizontal oscillation circuit (not shown) is input to the base of the horizontal output transistor 6, the emitter is grounded, and the collector is connected to the other terminal of the flyback transformer 5. The damper diode 7 and the resonance capacitor 8 are connected in parallel between the collector and the emitter of the horizontal output transistor 6.

One terminal of the horizontal deflection coil 9 is connected to the collector of the horizontal output transistor 6, and the other terminal is connected to one terminal of the secondary winding of the first saturable reactor transformer 10. The other terminal of the secondary winding of the first saturable reactor transformer 10 is connected to one terminal of the secondary winding of the second saturable reactor transformer 11, and the secondary terminal of the second saturable reactor transformer 11 is connected. The other terminal of the winding is connected to the S-shaped correction capacitor 12, and the other terminal of the S-shaped correction capacitor 12 is grounded. That is, the horizontal deflection coil 9, the secondary winding of the first saturable reactor transformer 10, the secondary winding of the second saturable reactor transformer 11, and the S-correction capacitor 12 are connected in series, and the deflection current I flows.

The operation of FIG. 1 will be described with reference to FIG. First
The DC superposition characteristics of the secondary windings of the saturable reactor transformer 10 and the second saturable reactor transformer 11 are used in a normal horizontal deflection circuit as shown in FIGS. 2 (a) and 2 (b), respectively. In the same manner as the linearity coil described above, the value of the inductance L greatly differs depending on the direction of the deflection current I. The value of the inductance L is the currents i1 and i1 ^* (i1 ≠ i1 ^* ) flowing in the primary winding of the first saturable reactor transformer 10 and the current i2 flowing in the primary winding of the second saturable reactor transformer 11.
And i2 ^* (i2 ≠ i2 ^* ). Further, the DC superposition characteristics determined by the directions of the deflection current I of the first saturable reactor transformer 10 and the second saturable reactor transformer 11 are set in the opposite directions. Furthermore, when the current value of the primary winding is the same, the value of the inductance L of the first saturable reactor transformer 10 is set to be larger than the value of the inductance L of the second saturable reactor transformer 11.

A parabolic current i as shown in FIG.
Through the primary windings of the two saturable reactor transformers having the DC superposition characteristics shown in FIG. The current i is a current obtained by converting the voltage output from the correction voltage generation circuit 1 by the first voltage / current conversion circuit 2 and the second voltage / current conversion circuit 3. By passing this current i through the primary windings of the first saturable reactor transformer 10 and the second saturable reactor transformer 11, the modulation circuit is focused on both ends of the x axis as shown by the solid line in FIG. When the modulation amount of 4 is determined, that is, when the correction amount of the left and right pincushion distortion is determined, when the horizontal linearity is compared in the vertical cycle as shown by the dotted line in FIG. ) And the end point (bottom end), the left and right ends are contracted (the center is closer to the center of the screen on the x axis). Further, the amount of movement of the central portion due to the contraction at the left and right ends is larger at both end portions of the x-axis than at the intermediate portion.

As shown in FIG. 3, this is because the current increases (i1 ^* , i2 ^* ) at the beginning and end of the vertical cycle, and becomes the minimum current (i1, i2) at approximately the midpoint of the vertical cycle. Such a parabolic current is transmitted to the first saturable reactor transformer 10
And the first saturable reactor transformer 10 by flowing through the primary winding of the second saturable reactor transformer 11.
This is because the inductance of the secondary winding of the second saturable reactor transformer 11 becomes smaller at the beginning and end of the vertical cycle and changes so as to become maximum at approximately the midpoint of the vertical cycle. Moreover, as shown in FIG.
This is because the larger the deflection current I, the larger the increase in the inductance L, and thus the larger the change in the inductance L near both ends of the x-axis.

In this way, the pincushion distortion at both ends of the x-axis greatly increases, and the pincushion distortion from the center of the screen to the intermediate part slightly increases. From this state, however, the pincushion distortion correction amount of the modulation circuit 4 should be increased. By Fig. 4 (b)
As shown in, the pincushion distortion correction is uniformly performed on the entire screen without excess or deficiency.

In the present embodiment, the method of correcting the Inner Kissen distortion has been described, but the left and right pincushion distortion determined by the system of the color cathode ray tube and the deflection yoke does not always become the Inner Kissen distortion, and the inner barrel distortion (pins at both ends of the x-axis is not shown). The strain amount may be larger than the pin strain amount in the middle portion).

In this case, the first saturable reactor transformer 10 and the second saturable reactor transformer 1
By setting the parabola current flowing through the primary winding 1 in the opposite direction, that is, the maximum current value at approximately the midpoint of the vertical cycle and decreasing the current value at the beginning and end of the vertical cycle, It can be similarly corrected.

[0025]

As described above, the left and right pincushion distortion correction circuit of the present invention has the following effects. (1) The horizontal deflection current flowing part of the horizontal output circuit including the left and right pincushion distortion correction circuits other than the saturable reactor system is
It has a saturable reactor type left and right pincushion distortion correction circuit including two saturable reactor transformers having different characteristics, and the saturable reactor type left and right pincushion distortion correction circuit is inserted in a portion of a horizontal output circuit where a horizontal deflection current flows. By doing so, it is possible to correct non-linear left and right pincushion distortions such as inner kissen, inner barrel, etc., and satisfactorily correct the raster distortion such that the distortion rate is small at both ends of the x-axis and the distortion rate increases in the middle part on the entire screen. This has the effect that the raster distortion quality of can be dramatically improved. (2) Since two saturable reactor transformers having different characteristics have the same DC superposition characteristics as the linearity coil normally used in the horizontal deflection circuit, the characteristics are set to appropriate values and the role of the linearity coil is also adjusted. This has the effect that a dedicated linearity coil is not required and a circuit can be constructed at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a left and right pincushion distortion correction circuit according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a DC superposition characteristic of a secondary winding of the saturable reactor transformer in the configuration of FIG. 1, (a) showing a DC superposition characteristic of a first saturable reactor transformer,
(B) shows the DC superimposition characteristic of the second saturable reactor transformer.

FIG. 3 is a diagram showing a parabola-shaped current waveform obtained by converting the output voltage of the correction voltage generation circuit into a current by the voltage / current conversion circuit in the configuration of FIG. 1.

FIG. 4 is a diagram for explaining correction of a left and right pincushion distortion state using the configuration of FIG. 1, and FIG. 4 (a) shows a left and right pincushion distortion after being corrected by a saturable reactor transformer according to an embodiment of the present invention, (B) shows a raster correction state when the left and right pincushion distortion of (a) is corrected by the power supply modulation method.

FIG. 5 is a diagram illustrating correction of a non-linear left and right pincushion distortion state of a color CRT using a conventional aspherical structure panel, in which (a) shows a distortion state before correction;
(B) and (c) respectively show the raster correction state when the left and right pincushion distortion of (a) is corrected by the power supply modulation method.

[Explanation of symbols]

1 Correction voltage generation circuit 2 1st voltage / current conversion circuit 3 2nd voltage / current conversion circuit 4 Modulation circuit 5 Flyback transformer 6 Horizontal output transistor 7 Damper diode 8 Resonant capacitor 9 Horizontal deflection coil 10 First saturable Reactor transformer 11 Second saturable reactor transformer 12 S-correction capacitors V _A , V _B power supply

Claims (3)

[Claims] 1. A horizontal output circuit including a left and right pincushion distortion correction circuit, wherein the horizontal output circuit includes a saturable reactor type left and right pincushion distortion correction circuit including two saturable reactor transformers having different characteristics. Left and right pincushion distortion correction circuit. 2. The left and right pincushion correction circuit according to claim 1, wherein the saturable reactor type left and right pincushion distortion correction circuit is inserted in a portion of the horizontal output circuit where a horizontal deflection current flows. 3. The left and right pincushion correction circuit according to claim 2, wherein the two saturable reactor transformers having different characteristics have the same DC superposition characteristics as the linearity coil.