JPH06133325A - Convergence device - Google Patents

Abstract

PURPOSE:To reduce mis-convergence due to deterioration in an electron beam and the earth magnetism without revision of a basic structure of the convergence device. CONSTITUTION:The convergence device is provided with a couple of left/right pole pieces 2, 2 arranged in the inside of a neck 1A of a cathode ray tube 1, convergence yokes 3, 3 whose front shape is of a channel shape and arranged in the outside of the neck 1A corresponding to the pole pieces 2, 2 respectively and correction coils 4, 4 wound respectively on the convergence yokes 3, 3 and a magnetic shield frame 11 surrounding the convergence yokes 3, 3 and the cathode ray tube 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a convergence device suitably used for a cathode ray tube composed of a plurality of electron guns.

[0002]

2. Description of the Related Art As a conventional device of this type, for example, one shown in FIG. 4 is known. Therefore, a conventional convergence device will be described with reference to FIG. In the figure, 1 is a cathode ray tube, 2 is a neck portion 1A of the cathode ray tube 1.
(See FIG. 1) Pole piece 3 provided inside is arranged on the outer side of the neck portion 1A corresponding to the pole piece 2, and a convergence yoke 4 formed in a U-shape on the front is provided. The correction coil is wound around the convergence yoke 3 and generates a magnetic field in the convergence yoke 3 by energizing a drive circuit (not shown) to apply a current. Then, when the drive circuit (not shown) is energized, the convergence device causes both sides of the center beam 6 passing through the electron gun cup 5 arranged in the cathode ray tube 1 from the convergence yoke 3 and the correction coil 4 to pass. Convergence correction magnetic field 8 on the side beams 7 and 7
Is applied to match the beams 6 and 7 on a fluorescent screen (not shown).

Next, the operation will be described. When the drive circuit of the convergence device is energized, a convergence correction magnetic field 8 (shown by a broken line in FIG. 4) is generated in the convergence yoke 3 and the correction coil 4. This convergence correction magnetic field 8 is applied to the pole pieces 2 and 2 inside the cathode ray tube 1.
Center beam 6 passing through the electron gun cup 5 via
A uniform magnetic field in the vertical direction is formed with respect to the side beams 7, 7 on both sides, and this magnetic field corrects the misconvergence between the side beams 7, 7 to move the side beams 7, 7 laterally. Perform convergence correction.

[0004]

However, in the case of the conventional convergence device, an external magnetic field 9 (solid line in FIG. 4) such as magnetic field leakage in the deflection yoke (see FIG. 1) or terrestrial magnetism other than the convergence yoke 3 (solid line in FIG. 4). There is a problem that the original spot shape of the electron beam after the convergence correction is deteriorated due to the influence of () and the misconvergence occurs due to the geomagnetism.

The present invention has been made to solve the above problems, and an object thereof is to provide a convergence device capable of reducing the misconvergence due to deterioration of the electron beam and geomagnetism without changing the basic structure of the convergence device. There is.

[0006]

The convergence device of the present invention comprises a convergence yoke and a magnetic shield frame surrounding the cathode ray tube.

[0007]

According to the present invention, when the convergence correction magnetic field is applied to the side beam generated from the electron gun in the cathode ray tube from the convergence yoke and the correction coil to match the center beam and the side beam on the phosphor screen, Even if a magnetic field acts, the magnetic shielding frame does not shield the external magnetic field to magnetically affect the convergence yoke, and the original convergence correction can be performed without degrading the side beam spot by the convergence correction magnetic field.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Based on the embodiment shown in FIG. 1, the same or corresponding parts as in the prior art will be designated by the same reference numerals, and the characteristics of the present invention will be mainly described. 1 is a side view showing a state in which the convergence device is attached to the electron gun, FIG. 2 is a perspective view showing the convergence device shown in FIG. 1 taken out, and FIG. 3 is a sectional view taken along the line CC of FIG. is there.

As shown in FIG. 1, the convergence device of this embodiment is mounted on a neck portion 1A of a cathode ray tube 1 arranged at the rear end of a deflection yoke 10 for deflecting an electron beam on a fluorescent screen. As shown in FIGS. 1 to 3, the convergence device includes a pair of left and right pole pieces 2 and 2 as a magnetic path forming ferromagnetic body disposed inside the neck portion 1A of the cathode ray tube 1. , These pole pieces 2, 2
Corresponding to each of the above, the convergence yokes 3 and 3 having a U-shaped front shape are provided outside the neck portion 1A.
And correction coils 4 and 4 respectively wound around the convergence yokes 3 and 3, and the electrons arranged in the cathode ray tube 1 by the convergence yokes 3 and 3 and the correction coils 4 and 4. A convergence correction magnetic field 8 is applied to the center beam 6 and the side beams 7 and 7 passing through the gun cup 5 so that the beams 6 and 7 are aligned on a fluorescent screen (not shown).

Further, the pair of convergence yokes 3 and 3 and the cathode ray tube 1 are both surrounded by a magnetic shield frame 11, and the magnetic shield frame 11 leaks from the deflection yoke 10 and an external magnetic field 9 such as geomagnetism. Is formed so that the external magnetic field 9 does not pass through the magnetic shield frame 11. And this magnetic shielding frame 11
Is formed of a magnetic substance. As the magnetic substance, for example, permalloy, carbon steel, etc. are preferable, and the magnetic substance is preferably formed as an amorphous alloy. Reference numeral 12 is a convergence yoke outer frame that surrounds the magnetic shielding frame 11.

Next, the operation will be described. In the case of the convergence device of this embodiment, when the drive circuit is energized, a convergence correction magnetic field 8 is generated in the convergence yoke 3 and the correction coil 4. The convergence correction magnetic field 8 forms a uniform magnetic field in the vertical direction with respect to the side beams 7, 7 on both sides of the center beam 6 passing through the electron gun cup 5 via the pole pieces 2, 2 inside the cathode ray tube 1, This magnetic field corrects the misconvergence between the side beams 7, 7 and moves the side beams 7, 7 laterally to perform the convergence correction.

At this time, when an external magnetic field 9 such as a leakage magnetic field from the deflection yoke 10 or a geomagnetism is applied to the convergence device, the external magnetic field 9 passes through the magnetic shield frame 11 as shown in FIG. Without disturbing the convergence correction magnetic field 8 of the convergence yokes 3 and 3 and the correction coils 4 and 4 inside the magnetic shield frame body 11, the original magnetic field of the convergence correction magnetic field 8 is applied to the side beams 7 and 7 on both sides of the center beam 6. It is possible to accurately match the two beams 6 and 7 on the phosphor screen without causing the beam spots to be deteriorated in shape by applying evenly to each other or causing misconvergence due to geomagnetism.

As described above, according to the present embodiment, the external magnetic field 9 can be shielded by the magnetic shield frame 11 attached to the outer periphery of the conventional convergence device, so that the magnetic shield frame 11 can correct the convergence. Convergence correction without disturbing the magnetic field 8, the original function of the magnetic field 8 can be exerted to reduce misconvergence due to deterioration of the side beams 7 and 7 and geomagnetism to perform accurate convergence correction. Since it suffices to attach the magnetic shielding frame 11 to the outer periphery of the device, the convergence device can be manufactured at low cost without changing the basic structure of the conventional convergence device.

The present invention is not limited to the above-mentioned embodiments, and any convergence device constructed by providing a magnetic shielding frame surrounding the convergence yoke and the cathode ray tube is included in the present invention. It

[0015]

As described above, according to the present invention, since the convergence yoke and the cathode ray tube are surrounded by the magnetic shield frame body, the deterioration of the electron beam and the terrestrial magnetism are caused without changing the basic structure of the convergence device. A convergence device that can reduce misconvergence can be provided.

[Brief description of drawings]

FIG. 1 is a side view showing a state in which a convergence device of the present invention is mounted.

FIG. 2 is a perspective view showing a convergence device taken out.

3 is a cross-sectional view taken along the line CC of FIG.

FIG. 4 is a diagram showing an example of a conventional convergence device,
It is a figure equivalent to FIG.

[Explanation of symbols]

 1 cathode ray tube 2 pole piece (ferromagnetic material) 3 convergence yoke 4 correction coil 6 center beam 7 side beam 8 convergence correction magnetic field 11 magnetic shielding frame

Claims (1)

[Claims] 1. A ferromagnetic material for forming a magnetic path, which is disposed inside a neck portion of a cathode ray tube, and a convergence yoke which is disposed outside the neck portion so as to correspond to the ferromagnetic material.
A correction coil wound around the convergence yoke is provided, and a convergence correction magnetic field is applied to the center beam and the side beam from the electron gun in the cathode ray tube by the convergence yoke and the correction coil to apply each of the beams to the fluorescent screen. A convergence device in which the above-mentioned convergence device is provided with a magnetic shielding frame surrounding the convergence yoke and the cathode ray tube.