JPH0588036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a convergence correction device, and more particularly to a convergence correction device for an in-line electron gun and a color picture tube having a self-convergence type deflection yoke.

2. Description of the Related Art Generally, in a color picture tube used in a color television receiver, electron beams emitted individually from three electron guns are not only focused on a fluorescent surface, but also concentrated on the same hole in a shadow mask (convergence). )It is necessary to.

For this reason, in the conventional three-electron gun in-line color picture tube, in order to obtain good concentration of the three electron beams on the fluorescent surface,
A deflection device is used that includes a self-convergence type deflection yoke that has a vertical deflection magnetic field as a barrel type and a horizontal deflection magnetic field as a pincushion type magnetic field distribution.

However, it is well known that in the self-convergence type deflection yoke, a convergence deviation (hereinafter referred to as coma error) d between the center beam G and the side beams R and B due to coma aberration occurs as shown in FIG. In order to correct the vertical coma error among these coma errors, magnetic pieces 22a and 22b are used to shield or enhance the three beams R, G, and B in the electron gun as necessary, as shown in FIG. , 23a, 23b, or
A set of coils for generating a six-pole magnetic field as shown in FIG. 8A or a four-pole magnetic field as shown in FIG. 8B is arranged near the electron gun. As shown in FIG. 8, the current flowing through the coil that generates the magnetic field is supplied in the form of a sawtooth waveform with a vertical deflection period.

Problems to be Solved by the Invention However, when vertical coma error correction is performed optimally on the upper and lower sides of the screen using a conventional correction device as shown in FIGS. 7 and 8, as shown in FIG. As shown in the figure, the correction becomes excessive in the middle part 26 of the screen between the center part 25 and the upper side part 24 of the screen.

When this is viewed in terms of the relationship between the vertical deflection distance and the amount of overcorrection of the coma error, it becomes a curve as shown in FIG. 10, which causes problems such as deterioration of convergence quality.

The present invention has been made in view of the above points, and an object of the present invention is to provide a convergence correction device that can perform optimal coma error correction over the entire screen.

Means for Solving the Problems The present invention provides a convergence correction device for correcting the coma error of an electron beam caused by a self-convergence type deflection yoke attached to a color picture tube having an in-line type electron gun. a first coma error correction coil that is driven by a sawtooth waveform current and generates a sawtooth waveform magnetic field that corrects a coma error of the electron beam according to the sawtooth waveform current; and the first coma error correction coil. a second coma error correction coil that generates a magnetic field that cancels a magnetic field corresponding to an overcorrection of the sawtooth waveform magnetic field generated by the coil; drive current generating means for generating a drive current for driving the second coma error correction coil; and a drive current generating means for generating a drive current for driving the second coma error correction coil; and a correction magnetic field applying means for correcting the coma error caused by the deflection yoke of the electron beam.

Operation The magnetic field generated by the first coma error correction coil is driven by the sawtooth waveform current that drives the vertical deflection coil, producing a sawtooth waveform magnetic field that corrects the coma error of the electron beam. The magnetic field generated by the first coma error correction coil has a simple sawtooth waveform and includes over-correction.

Further, the second coma error correction coil generates a magnetic field that cancels the overcorrection of the magnetic field generated by the first coma error correction coil.

Therefore, by superimposing the magnetic fields generated by the first and second coma error correction coils around the electron gun by a correction magnetic field applying means, the overcorrection of the coma error can be extracted from the magnetic field generated by the first coma error correction coil. It is possible to apply an optimal correction magnetic field around the electron gun in which the correction magnetic field is canceled.

Therefore, coma errors caused by the electron beam deflection yoke can be reliably corrected.

Embodiment FIG. 1 shows a schematic diagram of one embodiment of the invention. In the figure, 1 and 2 are cores, and 3a, 3b, 4a, and 4b are coils.

Coils 3a and 4a are wound around the core 2, and the coil 3a generates a magnetic field having lines of magnetic force as shown by a solid arrow 5a, and the coil 4a generates a magnetic field having lines of magnetic force as shown by a broken arrow 6a. Further, coils 3b and 4b are wound around the core 1, and the coil 3b generates a magnetic field having lines of magnetic force as shown by a solid arrow 5b, and the coil 4b generates a magnetic field having lines of magnetic force as shown by a broken arrow 6b. Cores 1 and 2 are arranged to sandwich the electron gun of a television picture tube to form a six-pole magnetic field.

The coils 3a, 3b, 4a, 4b are wired as shown in FIG. In the figure, 7 and 8 indicate vertical deflection coils. A sawtooth waveform current is passed between terminals 9 and 10. Therefore, the magnetic flux generated by the coils 4a and 4b becomes as shown in FIG. 4A. Further, at both ends of the coils 3a and 3b, there are at least one pair of diodes D ₁ and D ₂ connected in parallel with each other with opposite polarities, or at least one pair of Zener diodes D 3 and ₂ connected in series with each other with opposite polarities. D ₄ are connected in parallel.

At this time, the turn-on voltage of the diodes D ₁ and D ₂ or the Zener diodes D ₃ and D ₄ is set so that it matches the voltage across the coils 3a and 3b when the electron beam is deflected to approximately the middle in the vertical deflection direction. Set.

In addition, the coils 4a and 4b are wired so that a current flows with a polarity that reduces the coma error, and a sawtooth waveform current synchronized with the vertical deflection period flows.
A magnetic field having a sawtooth waveform as shown in FIG. 4AA is generated in the coils 4a and 4b. On the other hand, the coil 3a,
3b is wired so that a current flows through it with magnetism that generates a magnetic field that increases the coma error,
A current having a sawtooth waveform synchronized with the vertical deflection period is waveform-shaped by the diodes D ₁ and D ₂ or the Zener diodes D ₃ and D ₄ as described above, and the current flows through the coils 3a and 3b. This causes a change in the rate of change in the waveform of the magnetic flux generated during the scanning period, and a magnetic field whose rate of change changes during the scanning period as shown in FIG. 4B is generated.

Therefore, the magnetic flux caused by the coils 3a, 3b and the magnetic flux caused by the coils 4a, 4b are superimposed, and the coils 3a, 3b, 4a, 4b surround the electron gun.
A magnetic flux as shown in FIG. 4C will be generated.

In this embodiment, the change in the amount of coma error correction with respect to the vertical deflection distance is shown by a solid line 21 in FIG. 5A when the coma error correction is set to be optimal on the upper and lower sides of the screen. Further, a broken line 20 in FIG. 5A shows the change in the amount of coma error correction with respect to the vertical deflection distance by the sawtooth wave current, which is set so that the coma error correction is optimal at the top and bottom sides of the screen.

Next, FIG. 5B shows a change in the amount of coma error correction in this embodiment with respect to the amount of coma error correction using the conventional sawtooth wave current.

In the conventional coma error correction using only the sawtooth wave current, the coma error correction exceeds the area near the middle part 26 of the screen, as shown in FIG. However, in the correction according to this embodiment, the amount of correction is less in the middle part 26 of the screen than in the conventional coma error correction using sawtooth wave current, as shown in FIG. 5B.

Therefore, over-correction of the coma error as shown in FIG. 10 can be canceled, and misconvergence patterns can be favorably corrected.

FIG. 3 shows a schematic diagram of another embodiment. As shown in FIG. 3, a coil 14a is wound around the core 13,
A coil 14b is wound around the core 12, and a current with a sawtooth waveform synchronized with the vertical deflection period is applied to the arrow 1, for example.
The configuration is such that a magnetic field having lines of magnetic force as shown in 5a and 15b is generated to correct the convergence shift at the top and bottom sides of the screen, and a coil 18a is wound around the core 17, a coil 18b is wound around the core 16, and the coils 14a,
Arrows 19a, 19 of opposite polarity to the magnetic field caused by 14b
By generating a magnetic field having lines of magnetic force as shown in FIG. 1B, it is possible to effectively correct the coma error in the same manner as in the first diagram.

In addition, although the coma error correction device using a 6-pole coil was explained in the above two embodiments, even when using a 4-pole coil as shown in FIG. 8B or a magnetic piece as shown in FIG. Convergence patterns can be effectively corrected.

Further, since the correction device of this embodiment does not need to obtain a complicated correction waveform and does not require an electric circuit therefor, optimal coma error correction can be performed at low cost.

Furthermore, although the above two embodiments have been described in which one set each of the first coma error correction coil and the second coma error correction coil are provided, it is also possible to provide a plurality of sets of each for correction.

Effects of the Invention As described above, according to the present invention, at least two sets of coma error correction coils are provided, and the over-correction caused by one correction coil is canceled by the other correction coil, thereby achieving optimal coma error correction over the entire screen. can be done,
It has features such as being able to improve the screen quality of television picture tubes.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a wiring diagram of an embodiment of the invention, Fig. 3 is a diagram for explaining another embodiment of the invention, and Fig. 4 is a diagram for explaining another embodiment of the invention. A corrected magnetic flux waveform diagram obtained by a correction device according to an embodiment of the present invention, FIG. 5 is a diagram showing an over amount of coma error correction with respect to a vertical deflection distance according to an embodiment of the present invention, and FIG. 6 is a diagram showing convergence deviation due to coma aberration. Figures 7 and 8 are diagrams showing an example of a convergence correction device, Figure 9 is a diagram showing a convergence shift pattern caused by correction of only a sawtooth wave current, and Figure 10 is a diagram showing a convergence shift pattern caused by correction of only a sawtooth wave current. FIG. 6 is a diagram showing the amount of overcorrection of the coma error due to the correction of only the image. 1, 2...core, 3a, 3b...coil, 4a, 4
b...Coil, 6a, 6b...Magnetic field lines, 7...Vertical deflection coil, 8...Vertical deflection coil, _D1 , _D2 ...Diode, _D3 , _D4 ...Zena diode.

Claims (1)

[Scope of Claims] 1. A convergence correction device for correcting a coma error of an electron beam caused by a self-convergence type deflection yoke attached to a color picture tube having an in-line type electron gun, comprising: a sawtooth shape that drives a vertical deflection coil of the deflection yoke; a first coma error correction coil that is driven by a waveform current and generates a sawtooth waveform magnetic field that corrects the coma error of the electron beam according to the sawtooth waveform current; a second coma error correction coil that generates a magnetic field that cancels a magnetic field corresponding to an overcorrection of the sawtooth waveform magnetic field; a drive current generating means for generating a drive current for driving the coma error correction coil; and a drive current generating means for generating a drive current for driving the coma error correction coil, and superimposing the magnetic fields generated by the first coma error correction coil and the second coma error correction coil and applying the superimposed magnetic fields around the electron gun. A convergence correction device comprising a correction magnetic field applying means for correcting an elacomer of the beam due to the deflection yoke.