JPH1198520A - Convergence correction circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct an X axis longitudinal mis-convergence independently right and left in a horizontal direction of the seven. SOLUTION: A bias magnetic field is given to coils L1, L2 in the same direction and a bias magnetic field is given to coils L7, L8 in an opposite direction to the direction given to coils L1, L2. Inductances of coils L3, L4 and coils L5, L6 are respectively changed differentially. A correction coil L9 is connected so that the coils L1-L9 configure a bridge circuit 1 as a whole. The coil L9 is divided into two and they are connected to both sides of an electron gun. The bridge 1 becomes unbalanced by changing differentially the inductance of the coils L3, L4 or the coils L5, L6 and a current flows to the coil L9. An X axis longitudinal mis-convergence is corrected independently on the left/right sides of the screen by respectively adjusting the coils L3, L4 and the coils L5, L6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a convergence correction circuit suitable for a color CRT or the like, which can correct X-axis vertical misconvergence independently of left and right without generating image distortion.

[0002]

2. Description of the Related Art It is known that a color CRT generates symmetrical vertical misconvergence near the left and right ends on the X axis (horizontal scanning axis) as shown in FIG. Hereinafter, the vertical misconvergence that occurs on the X axis is referred to as X axis vertical misconvergence. Conventionally, a saturable reactor has been used to correct the X-axis vertical misconvergence.

FIG. 7 shows an example of the configuration of the saturable reactor 120. The saturable reactor 120 includes an I-shaped core 122, a U-shaped core 124, and a U-shaped core 12 as shown in FIG.
4, and a pair of permanent magnets 126, 128 inserted between the two legs 124a, 124b and the I-shaped core 122.
Coil L11, L12 is wound around both legs 124a, 124b. The magnets 126 and 128 are connected to both cores 122 and 12.
4 to generate a fixed bias magnetic field in one direction (for example, a magnetic field indicated by a solid arrow).

A pair of coils L11 and L12 wound around both legs 124a and 124b are connected to a horizontal deflection coil (HDY) 112 shown in FIG. Of the horizontal deflection coils 112 mounted near the funnel portion of the cathode ray tube, the coil portion mounted above the X axis when viewed from the panel side is an upper horizontal deflection coil (hereinafter referred to as an upper coil).
And H _U, the coil portion attached to the underside of the X-axis (referred to as lower coil) lower horizontal deflection coil and H _D.

FIG. 9 shows how the horizontal deflection coil 112 is mounted. The upper separator 114 has an upper coil H
A pair of coils 112a and 112b constituting _U are toroidally wound, and the lower coil
A pair of coils 112c and 112d forming _D are toroidally wound. 106 is an electron beam R, G, B
Is a generic term for

The above-mentioned pair of coils L11 and L12 are respectively composed of an upper coil H _U and a lower coil H _D as shown in FIG.
Are connected in series and connected in parallel.

[0007] Then, by passing a horizontal deflection current I _H of the sawtooth horizontal period to the terminal 108, the pair of coils L11, L12, and parabolic wave convergence correction current flows, X Jikutate shown in FIG. 6 Misconvergence is corrected. 130 is a capacitor for S-shaped correction.

[0008] By developing the structure shown in FIG.
In the configuration shown in FIG. 1, X-axis misconvergence can be variably corrected. That is, the above-mentioned pair of coils H _U and H _D are connected in parallel, and the two coils H _U and H _D are magnetically biased saturable reactors, and the coils L 13 and L D
14, a set of coils XBV and coils L15 and L
16 is connected to the balance coil XCV.

As shown in FIG. 11, the coils L13 and L14 are respectively formed by
0, 131 and are connected so that a magnetic field is generated in the same direction. A circular magnet Mg is placed between the drum cores 130 and 131, and a magnetic bias is applied. By rotating the magnet Mg, the magnetic bias applied to the coils L13 and L14 changes, and the convergence correction amount can be changed.

The coils L15 and L16 are
2 is wound around the bobbin. Core 13 in bobbin
2, the inductance of the coils L15 and L16 can be changed differentially. Thereby, the convergence correction amount can be changed.

[0011]

As described above, the magnet M having the structure as shown in FIGS.
By adjusting g and the coils L15 and L16, the X-axis vertical misconvergence can be variably corrected.

However, in this correction, since the correction is made symmetrically in the left-right direction of the screen, the movement in the left-right direction of the screen is the same, and the movement also occurs in the center of the screen. Therefore, in the method according to the related art, there is a problem that it takes a considerable amount of time to simultaneously correct the X-axis end of the screen and the center of the screen, and a long time is required for correcting the misconvergence.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a convergence correction circuit that can correct X-axis vertical misconvergence independently in the horizontal direction of the screen.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to provide a color CRT equipped with an in-line type electron gun in which an X-axis vertical misconvergence which occurs vertically at both ends of a screen is reduced. In the convergence correction circuit for correction, a horizontal deflection current is supplied in parallel, and a bias magnetic field is applied in the same direction. The first and second coils are connected to the first and second coils, respectively. A third coil and a fourth coil, the inductances of which are changed, and fifth and sixth coils respectively connected to the third and the fourth coils and having a differentially changed inductance. , Fifth and sixth coils, respectively, and a seventh and eighth coil to which a bias magnetic field is applied in a direction opposite to the first and second coils, , A fifth and seventh coil, a second and fourth coil, and a convergence correction coil for correcting convergence, which is connected to form a bridge with the sixth and eighth coils. By adjusting the third and fourth coils and the fifth and sixth coil sets, respectively, X
A convergence correction circuit for correcting axial-vertical misconvergence.

As described above, according to the present invention, the bias magnetic field in the opposite direction to the bias magnetic field applied to the first and second coils is applied to the seventh and eighth coils, and the third and fourth coils are provided. And the fifth and sixth coils have their inductances changed differentially, respectively, and the convergence correcting coils are the first and third coils, the fifth and seventh coils, the second and fourth coils. And the sixth and eighth coils are connected to form a bridge, so that the third and fourth coils and the fifth and sixth coils are respectively adjusted to balance the bridge. The current is caused to flow through the convergence correction coil, so that the X-axis vertical misconvergence correction can be performed independently on the left and right sides of the screen.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the configuration of a circuit for performing convergence correction according to the present invention. And the upper coil H _U and lower coil H _D is a set of coils constituting the horizontal deflection coil is connected in parallel. The horizontal deflection current is supplied to one of the connection portion of the upper coil H _U and lower coil H _D. The other connection portion is connected to one end of the bridge circuit 1 including the coils L1 to L9.

The coils L1, L3, L5 and L7 are connected in series, and similarly the coils L2, L4 and L4 connected in series.
L6 and L8 are connected in parallel. Also, the coil L
The midpoints of L3 and L5 and the midpoints of coils L4 and L6 are connected via correction coil L9. Coil L1, L
When the coils L3, L5, and L7 and the coils L2, L4, L6, and L8 maintain a predetermined balance, no current flows through the correction coil L9. The other end of the bridge circuit 1 is grounded via a capacitor 10.

A set of coils L3 and L4 and a coil L
Each of the pairs of L5 and L6 has, for example, the configuration shown in FIG. 2 and functions as a balance coil having a variable inductance. That is, the coils L3 and L4
Are wound around a common bobbin, and the respective inductances are changed differentially by moving the screw core 11. Similarly, the coils L5 and L6 are wound around a common bobbin, and the respective inductances are changed differentially by moving the screw core 12.

FIG. 3 shows coils L1 and L2 and coil L
7 shows an example of the structure of L8. These coils L1, L2
And coils L7 and L8 form a saturable reactor,
The U-shaped core 24 includes a pair of permanent magnets 26 and 28 attached to both legs 24a and 24b.
4b, coils L1 and L2 and coils L7 and L8
Is wound. The magnets 26 and 28 are for generating a fixed bias magnetic field in one direction with respect to the core 24. Although not shown, the I-shaped core is replaced with the permanent magnets 26, 2
8 may be further provided at the other end.

As shown in FIG. 3A, the coils L1, L
2 are the legs 24a of the core 24 so that the magnetic field due to the horizontal deflection current is in the same direction as the fixed bias magnetic field during right deflection.
It is wound against. On the other hand, the coils L7 and L8 are wound around the legs 24b of the core 24 so that the magnetic field is in the opposite direction to the fixed bias magnetic field during right deflection. In the case of left deflection, the relationship between the two is reversed, the magnetic field generated by the coils L7 and L8 is in the same direction as the fixed bias magnetic field, and the magnetic field generated by the coils L1 and L2 is in the opposite direction to the fixed bias magnetic field. Become.

The coils L1 and L2 and the coils L
3B, the same effect can be obtained by winding the cores 24a and 24b attached to both poles of the permanent magnet 27 so as to obtain the magnetic field as described above, as shown in FIG. 3B. Can be obtained.

FIG. 4 shows an example of the arrangement of the correction coil L9 with respect to the electron gun 32 from the rear side. As shown in the drawing, the correction coil L9 is divided into a coil L9 ′ and a coil L9 ″ so that a magnetic field is generated in a symmetrical direction by the same current, and the correction coil L9 is respectively applied to the cores 30 and 31 independent of each other. The cores 30 and 31 are arranged so as to sandwich the electron guns 32 in an in-line arrangement, and the directions of the generated magnetic fields are red (R), green (G), and blue (B). And to be in line.

As described above, according to the present invention, the correction coil L9 is provided separately from the saturable reactor for generating the correction current. For this reason, it is possible to avoid deterioration in image quality such as image distortion during convergence correction.

Next, misconvergence correction by this configuration will be described. FIG. 5 schematically illustrates horizontal deflection current and convergence correction for the screen. When the electron beam is deflected rightward from the center of the screen shown in FIG. 5A. In the case of right deflection, as shown in II of FIG. 5B, the horizontal deflection current increases in the positive direction with the deflection. Then, since the magnetic fluxes on the coils L1 and L2 side are combined, the inductance is reduced. On the other hand, since the coils L7 and L8 are reverse-biased, there is no change in inductance.

When the inductance of the coils L1 and L2 is reduced, the screw core 11 is adjusted to
When the balance of the inductance of L4 is changed differentially,
The balance of the entire bridge circuit 1 is lost, and a current similar to the deflection current flows through the correction coil L9. As described above, the correction coil L9 is arranged with respect to the electron gun 32 as shown in FIG. Therefore, FIG.
As shown by an example in C, the blue electron beam and the red electron beam are shifted from each other in the up and down directions. By appropriately adjusting the coils L3 and L4, the amount of deviation and the forward and reverse directions can be controlled.

On the other hand, in the case of left deflection, the horizontal deflection current is negative, which is the reverse of the right deflection, and as shown by I in FIG. Increase. Therefore, the operation is also opposite to that at the time of the right deflection, and the magnetic fluxes on the coils L7 and L8 side are synthesized, and the inductance is reduced. On the side of the coils L1 and L2, the fixed bias magnetic field becomes reverse bias, so that there is no change in inductance. Therefore, the screw core 12 is adjusted and the coils L5 and L5 are adjusted.
By changing the balance of L6 differentially, the overall balance of the bridge circuit 1 is lost, and a current similar to the deflection current flows through the correction coil L9. Thereby, FIG. 5C
As shown in FIG. 2, as in the case of right deflection, the blue electron beam and the red electron beam are shifted from each other in the upper and lower directions, and by appropriately adjusting the coils L5 and L6, The amount of deviation and the forward and reverse directions can be controlled.

As described above, according to the present invention, the coil L
The correction of the vertical misconvergence at the X-axis end on the right side can be performed independently by adjusting the balance coils of L3 and L4, and the adjustment of the balance coils of the coils L5 and L6 can be performed independently.

For example, at the time of rightward deflection, the coils L5, L
Even if the balance of the inductance 6 is changed, the overall balance of the bridge circuit 1 will be lost. However, the inductance of the coils L7 and L8 is
If the value is set to be sufficiently larger than the inductance of L6, this effect can be ignored. The same applies to the relationship between the coils L1 and L2 and the coils L3 and L4.

[0029]

As described above, according to the present invention, according to the present invention, the coil L having a variable inductance is provided.
By adjusting 3, L4 and L5, L6 respectively,
Since the vertical misconvergence on the left and right sides of the screen can be corrected independently, there is an effect that the X-axis vertical convergence can be adjusted very easily.

Further, according to the present invention, since the misconvergence correction coil is provided separately from the saturable reactor, there is an effect that image quality such as image distortion is not deteriorated.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of a configuration of a convergence correction circuit according to the present invention.

FIG. 2 is a circuit diagram more specifically showing an example of the configuration of a convergence correction circuit according to the present invention.

FIG. 3 is a schematic diagram illustrating an example of the structure of a saturable reactor.

FIG. 4 is a schematic diagram illustrating an example of an arrangement of a correction coil with respect to an electron gun.

FIG. 5 is a diagram for explaining X-axis misconvergence correction according to the present invention.

FIG. 6 is a diagram for explaining X-axis vertical misconvergence.

FIG. 7 is a schematic diagram illustrating an example of a configuration of a saturable reactor conventionally used.

FIG. 8 is a circuit diagram showing an example of a convergence correction circuit according to the related art.

FIG. 9 is a sectional view seen from the panel side.

FIG. 10 is a circuit diagram illustrating an example of a convergence correction circuit according to the related art.

FIG. 11 is a circuit diagram more specifically showing an example of a convergence correction circuit according to the related art.

[Explanation of symbols]

H _U · · · upper horizontal deflection coil, H _D · · · lower horizontal deflection coils, L1, L2, L7, L8 ··· coil, L
3, L4, L5, L6 ... balance coil, L9 ...
.Correction coils, 1... Bridge circuits, 11, 12.
..Screw cores to be adjusted for convergence correction, 3
2 ... Electron gun

Claims (2)

[Claims] 1. A color C having an in-line type electron gun
In a convergence correction circuit for correcting an X-axis vertical misconvergence generated in both ends of a screen in a vertical direction on a RT, a first and a second horizontal deflection currents are supplied in parallel and a bias magnetic field is applied in the same direction. And third and fourth coils respectively connected to the first and second coils, the inductances of which are changed differentially; and connected to the third and fourth coils, respectively. Fifth and sixth coils whose inductances are changed differentially, and bias magnetic fields connected to the fifth and sixth coils, respectively, in a direction opposite to the first and second coils. And the seventh and eighth coils, the first and third coils, the fifth and seventh coils, the second and fourth coils, and the 6 and 8 are connected in so as to form a coil and a bridge, and a convergence correction coils for correcting convergence, the third and fourth coil pairs, and the fifth
And the sixth set of coils are adjusted to obtain X
A convergence correction circuit for correcting axial vertical misconvergence. 2. The convergence correction circuit according to claim 1, wherein the convergence correction coil is divided into two and arranged from both sides in the inline arrangement direction of the electron gun.