JPH08138572A - Coma error correcting device - Google Patents

Abstract

PURPOSE: To provide a coma error correcting device which make correction of a coma error with high precision. CONSTITUTION: The coils of a pair of electromagnets 4a, 4b pinching the neck part 5 between color cathode rays having an in-line electron gun are composed of main correction coils 3a, 3b and aux. correction coils 3e, 3f. The L/R value of the aux. correction coils 3e, 3f is made larger than the L/R value of the main correction coils 3a, 3b, and a series circuit of a groupe of diodes 15 in parallel connection with the aux. coils in opposite polarities is connected parallel with the main correction coils 3a, 3b, and a vertical deflecting current is fed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection yoke coma error correction device used in a color cathode ray tube having an in-line type electron gun.

[0002]

2. Description of the Related Art A self-convergence type deflection yoke used for a color cathode ray tube having an in-line type electron gun is generally shown in FIG. 8 by forming a horizontal deflection magnetic field into a pincushion shape as shown in FIG. Focus the horizontal axis vertical line on the screen and the horizontal displacement (XH) between the side beams red (RED) and blue (BLUE).
Further, by making the vertical deflection magnetic field into a barrel shape as shown in FIG. 9, as shown in FIG. 10, vertical axis vertical lines, side beams red (RED) and blue (BL) are displayed on the screen.
Self-convergence is achieved by focusing the horizontal shift (YH) between UEs).

In this case, in the central beam G with respect to the side beams R and B, a vertical line shift (VCR) called a coma error as shown in FIG. 11 occurs.

As a device for correcting such a frame error, for example, there is a frame error correction device shown in FIG. This coma error correction device 1 has U-shaped magnetic poles 2a and 2b.
A pair of electromagnets 4a and 4b, around which correction coils 3a and 3b are respectively wound, are arranged at a rear portion of a deflection yoke attached to a color cathode ray tube in such a manner that a neck portion 5 is sandwiched from above and below, as shown in FIG. As shown in FIG. 12, the vertical deflection coil 6 is connected in series and a vertical deflection current is supplied to the neck 5 as shown in FIG.
A pincushion-type vertical deflection magnetic field as shown in the drawing is formed, and a coma error is corrected by applying a larger vertical deflection force to the central beam G than the side beams R and B.

FIG. 14 shows another conventional frame error correction device 7
The auxiliary coil 9 is attached to the Y-shaped magnetic poles 8a and 8b.
A pair of electromagnets 10a and 10b around which a and 9b are wound are arranged so as to be sandwiched from the left and right sides of the neck portion 5. By applying a vertical deflection current to the auxiliary coils 9a and 9b, the electromagnets 10a and 10b are placed in the neck portion as shown in FIG. The coma error is corrected by forming a deflection magnetic field as shown and applying vertical deflection forces in different directions to the central beam G and the side beams R and B.

In the above conventional coma error correction device, a sawtooth-shaped vertical deflection current shown in FIG. 15A is applied to the auxiliary coil. At this time, however, a counter electromotive force is generated in the correction coil, so that the vertical flow current actually flows. The deflection current waveform is shown in Fig. 15 (b).
And the sawtooth shape has a dull top. Therefore, as shown in FIG. 16, there is a problem in that the correction amount is insufficient at the upper and lower edges of the screen and the coma error is not sufficiently corrected.

FIG. 17 is a diagram showing a coma error correction device disclosed in Japanese Patent Laid-Open No. 1-207789, which is made to solve such a problem, and FIG. 18 is a circuit diagram thereof, which is the same as FIG. The reference numerals indicate the same or corresponding portions. In the figure, 11 is a pair of bar-shaped electromagnets 12a, 12 arranged at positions sandwiching the neck portion 5 from the left and right.
In the auxiliary coma error correction device constituted by b, the rod-shaped electromagnets 12a, 12b are constituted by rod-shaped magnetic poles 13a, 13b and auxiliary coils 14a, 14b.
4b and a series body of a diode group 15 composed of diodes connected in parallel with opposite polarities and a series body 16 of R and L are connected in parallel and are connected in series to the vertical deflection coil 6.

According to this prior art, the coma error compensating device 1 forms the pincushion magnetic field shown in FIG. 17 in the neck portion 5 and the auxiliary coma error compensating device 11 forms the barrel magnetic field to the central beam G. By applying a vertical deflection force stronger than the side beams R and B, and by generating a barrel magnetic field in the deflection period in which the diode group 15 is turned on, that is, in the vertical deflection period at the upper and lower ends of the screen, The coma error at the edge is corrected.

[0009]

However, according to this prior art, an auxiliary coma error correction device is required, and the energization start point of the diode group 15 is the voltage of the diode −.
Since it is determined by the current characteristics, there is a problem that it is difficult to improve the correction accuracy of coma error.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a coma error correction device having a small number of constituent parts and capable of performing an accurate coma error correction. To do.

[0011]

In the coma error correction device according to the present invention, a main correction coil is provided in a pair of electromagnets sandwiching a neck portion, and an L / R ratio larger than the L / R ratio of the main correction coil.
A sub-correction coil having an R ratio is wound, and a group of diodes inversely connected in parallel to the sub-correction coil are connected in series. Further, the main correction coil and the sub correction coil are connected in parallel.

The diode group is formed by connecting a plurality of diodes connected in series in anti-parallel or connecting a plurality of diodes connected in anti-parallel in series. Is configured to adjust. Further, a series resistor is connected to the main correction coil to adjust the ratio of the impedance of the main correction coil circuit and the impedance of the sub correction coil circuit.

[0013]

In the sub-correction coil, current flows only while the diode group is conducting, and the L / R ratio of the sub-correction coil is larger than the L / R ratio of the main correction coil. Since the vertical deflection magnetic field of the sub-correction coil is larger than the amount of decrease of, the vertical deflection of the central beam G at the upper and lower ends of the screen becomes large, and the coma error is corrected.

Further, since the conduction period of the diode group and the current ratio between the main correction coil and the sub correction coil can be adjusted, the coma error can be corrected with high accuracy.

[0015]

【Example】

Example 1. FIG. 1 is a diagram showing a configuration of an embodiment of the present invention,
FIG. 2 is a diagram showing the connection circuit. In the figure,
The same reference numerals as those in FIG. 2, FIG. 13 or FIG. 17 respectively denote the same or corresponding portions, and 3a and 3b denote magnetic poles 2a and 2b.
The main correction coils 3e and 3f wound around the same are magnetic poles 2
The main correction coil circuit 18a is a sub-correction coil wound around a and 2b, and is composed of a series body of the main correction coils 3a and 3b, as shown in FIG. 2, the sub-correction coils 3e and 3f, and the diode group 15. A parallel connection body with the sub-correction coil circuit 18b formed of a serial body is connected in series to the vertical deflection coil 6 so that the vertical deflection current Ia shown in FIG.

FIG. 3B is a diagram showing the waveform of the main correction current Ib flowing through the main correction coil circuit 18a, and FIG. 3C is a diagram showing the waveform of the sub-correction current Ic flowing through the sub-correction coil circuit 18b. In the figure, T ₁ shows the timing when the sub-correction current Ic is turned off, and T ₂ shows the timing when it is turned on.

According to the first embodiment, the vertical deflection current Ia
3 of FIG. 3 only during the period when the diode group 15 is conducting.
The sub-correction current Ic shown in (c) flows, and the main correction current Ib
Is reduced accordingly. The current ratio between Ib and Ic is
It is determined by the ratio of the impedance of the main correction coil circuit 18a and the impedance of the sub correction coil circuit 18b. Also,
The strength of the deflection magnetic field generated by the main correction coils 3a and 3b and the strength of the deflection magnetic field generated by the sub-correction coils 3e and 3f are given by the value of L / R (inductance / resistance) × Ib of the main correction coils 3a and 3b. And the sub-correction coils 3e, 3
It is determined by the value of (L / R) × Ic of f.

Therefore, the vertical deflection magnetic field generated by the auxiliary correction coils 3e and 3f (shown by the broken line in FIG. 1) so that the impedance ratio of the main correction coil circuit 18a and the auxiliary correction coil circuit 18b becomes a predetermined shunt ratio. L) is increased by a predetermined amount so as to be larger than the reduction amount of the vertical deflection magnetic field generated by the main correction coils 3a and 3b.
By setting the values, that is, the number of turns of the main correction coils 3a and 3b and the sub-correction coils 3e and 3f and the wire diameter of each coil, it is possible to accurately correct the coma error that occurs at the upper and lower ends of the screen.

Example 2. FIG. 4 is a circuit diagram of a second embodiment of the present invention. The same reference numerals as those in FIG. 2 denote the same or corresponding portions, and the diode group 15a is formed by connecting a series body of three diodes in parallel. A resistor R is inserted in series in the main frame error correction circuit 18a. FIG. 5 is a diagram showing a current waveform of each part of the second embodiment.

According to this embodiment, the rising voltage of the diode string is 3 times the rising voltage of one diode.
As shown in FIG. 5C, the timing T ₃ at which the sub-correction current Ic is turned off and the timing T _{4 at which it} is turned on are as shown in FIG. 5C, as compared with the case of the first embodiment. , The period during which the sub-correction current Ic flows becomes shorter.

Further, the main correction coil circuit 1 is adjusted by adjusting the resistance R inserted in the main correction coil circuit 18a.
The impedance of 8a is adjusted to adjust the diversion ratio of the main correction current Ib and the sub correction current Ic.

According to the second embodiment, the diode group 15
By adjusting the number of a in series and the resistance value of the resistor R, the strength of the deflection magnetic field generated by the main correction coils 3a and 3b, the strength of the deflection magnetic field generated by the sub correction coils 3e and 3f, and the period thereof Since and can be adjusted, more accurate frame error correction can be performed.

Example 3. FIG. 6 is a circuit diagram of Embodiment 3 of the present invention, in which the same reference numerals as those in FIG. 4 denote the same or corresponding portions, and 15b is a series connection of three diode groups connected in parallel with opposite polarities. The same effects as those of the second embodiment can be obtained.

In each of the above embodiments, the U-shaped magnetic pole 2
The coma error correction device in which the main correction coils 3a and 3b and the sub correction coils 3e and 3f are wound around a and 2b is shown.
It can be applied to the coma error correction device shown in FIG. 14 as well, and the same effect can be obtained.

[0025]

According to the present invention, the coil of the electromagnet for generating the coma error correction magnetic field, the main correction coil and the sub correction coil are used, and the L / R value of the sub correction coil is set to L / R of the main correction coil. The auxiliary correction coil is configured to have a value larger than the R value, and a group of diodes inversely connected in parallel to the sub-correction coil is connected in series to the main correction coil. By adjusting the L / R value and the rising voltage of the diode group, the magnitude and pattern of the coma error correcting magnetic field generated by the coma error compensating apparatus can be adjusted, so that a coma error compensating apparatus capable of highly accurate correction can be obtained. effective.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a circuit diagram of the first embodiment.

FIG. 3 is a current waveform diagram of each part of the first embodiment.

FIG. 4 is a circuit diagram of a second embodiment of the present invention.

FIG. 5 is a current waveform chart of each part of the second embodiment.

FIG. 6 is a circuit diagram of Embodiment 3 of the present invention.

FIG. 7 is a diagram showing a pin cushion type horizontal deflection magnetic field of a self-convergence type deflection yoke.

FIG. 8 is a diagram showing a horizontal convergence blur (XH) corrected by a pincushion type horizontal deflection magnetic field.

FIG. 9 is a view showing a barrel type vertical deflection magnetic field of a conventional self-convergence type deflection yoke.

FIG. 10 is a diagram showing a horizontal shift (YH) corrected by a barrel-type vertical deflection magnetic field.

FIG. 11 is a diagram showing a coma error of a self-convergence type deflection yoke.

FIG. 12 is a diagram showing a conventional coma error correction device.

FIG. 13 is a circuit diagram of a conventional coma error correction device.

FIG. 14 is a diagram showing another conventional frame error correction device.

FIG. 15 is a current waveform chart of each part of a conventional example.

FIG. 16 is a diagram showing a coma error correction state according to a conventional example.

FIG. 17 is a diagram showing a coma error correction device according to the prior art.

FIG. 18 is a prior art circuit diagram.

[Explanation of symbols]

1 frame error correction device, 2a, 2b U-shaped magnetic pole,
3a, 3b main correction coil, 3e, 3f sub correction coil,
4a, 4b electromagnets, 5 neck parts, 6 vertical deflection coils, 15 diode groups, 18a main auxiliary coil circuit,
18b Sub auxiliary coil circuit.

Claims (4)

[Claims] 1. A deflection yoke attached to a color cathode ray tube, which comprises a pair of electromagnets arranged so as to sandwich a neck portion of a color cathode ray tube having an in-line type electron gun and which is supplied with a vertical deflection current. In a coma error correction device that generates a deflection magnetic field that corrects a coma error that occurs, a coil that constitutes the pair of electromagnets includes a main correction coil and an L / R value larger than the L / R value of the main correction coil.
A sub-correction coil having a value and configured with a sub-correction coil in which anti-parallel connected diode groups are connected in series. 2. The coma error correction device according to claim 1, wherein the main correction coil and the sub correction coil are connected in parallel. 3. The diode group is formed by connecting a plurality of diodes connected in series in anti-parallel or connecting a plurality of diodes connected in anti-parallel in series. The coma error correction device according to claim 1, wherein the coma error correction device is configured to adjust a conduction voltage. 4. The main correction coil is connected to a resistor in series to adjust the impedance ratio of the main correction coil circuit and the sub correction coil circuit. Coma error correction device.