JPH02146890A - Cathode ray tube display - Google Patents

Abstract

PURPOSE:To decrease a required exciting ampere-turn, to make the size of a degauss coil small and to reduce the cost by fitting a magnetic cover made of a ferromagnetic substance to the inside of the case forming part of a return path for a degauss coil magnetic flux. CONSTITUTION:A magnetic cover 8 is fitted to a case 3. Since the magnetic cover 8 has a small magnetic reluctance, the cover 8 forms a magnetic circuit with a small magnetic reluctance surrounding a degauss coil 4 together with an inner shadow mask 5 and an inner magnetic shield 6.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cathode ray tube display device, and in particular,
This invention relates to a cathode ray tube display device in which a degauss coil is wound around a panel of a cathode ray tube installed in the device.

[Prior art] Figures 3 and 4 show a conventional cathode ray tube (hereinafter abbreviated as CRT).
This shows a display device, and inside a casing (3) made of a non-magnetic material, a CRT (]) with a deflection yoke (2) attached around its neck is arranged, and its screen f
A degauss coil (4) is wound around the f11 rema, and it functions as a degauss by passing an attenuating alternating current through it.The shadow mouse (5) and internal magnetic silt (6) is also made of ferromagnetic material, and the fourth
When a degauss current flows in the direction shown by O20 in the figure, a degauss magnetic flux (7) shown by a broken line is generated.

In the above configuration, since the shadow mouse (5) and the internal magnetic shield (6) are made of ferromagnetic material, the magnetic resistance is very small, but the degauss magnetic flux emitted from the internal magnetic shield (6) has a large magnetic resistance. air and housing (3
) as a return bus (return trip). For this purpose, it is necessary to increase the excitation a/bear turn, which is the product of the number of turns and the current (ampere).

[Problems to be Solved by the Invention] As described above, in conventional cathode ray tube display devices, the magnetic resistance of the return path is large, so in order to obtain the required degauss magnetic flux, it is necessary to use a degauss coil. First, there was a problem in that the device also became large.

This invention was made to solve the above problems, and by reducing the return path magnetic resistance of the degauss coil, the excitation ampere turns can be reduced, thereby achieving miniaturization and cost reduction of the degauss coil. The purpose is to obtain a cathode ray tube display device that can be used.

[Means for Solving the Problems] The cathode ray tube display device according to the present invention includes a casing that forms part of the return path of the degauss coil magnetic flux.
A magnetic cover made of ferromagnetic material is attached.

[Function] In the present invention, the magnetic cover reduces the magnetic resistance of the degauss coil magnetic flux transfer path.

[Embodiment] FIG. 1 shows an embodiment of the present invention, in which a magnetic cover (8) is attached to the casing (3) in contrast to the one shown in FIG.

With the above configuration, since the magnetic material cover (8) has a small magnetic resistance, it works together with the inner shadow mask (5) and the inner magnetic shield (6) to reduce the magnetic resistance surrounding the degauss coil (4). It forms a small magnetic circuit.

FIG. 2 shows an example of the shape of the magnetic cover. For the purpose of explanation, the magnetic material cover (8) is classified according to the direction in which the magnetic flux passes.There is a tube shaft plate (8a) through which the magnetic flux passes in the four axial directions of the CRT tube, and a radius plate (8b) through which the magnetic flux passes in the radial direction.
). FIG. 2(A) shows a shape in which both the tube shaft plate (8a) and the radius plate (8b) exist over the entire circumference,
The radius plate (8b) in FIG. 2(B) does not exist over the entire circumference, but is attached locally.

In addition, in the above embodiment, the magnetic material cover is in close contact with the inner side of the casing. good.

Further, although the case where the magnetic shield is placed inside the CRT has been described, the same effect can be obtained even if an external magnetic shield method is used outside the CRT.

[Effect of the invention] As described above, according to the present invention, the degauss coil can be
Since a magnetic loop is formed with a ferromagnetic magnetic shield plate and a magnetic cover, a large degauss magnetic flux can be obtained with a small excitation ampere turn, which has the effect of making it compact and low cost. .

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a perspective view showing an example of the shape of the magnetic cover, FIG. 3 is a schematic side sectional view of a conventional cathode ray tube display device, and FIG. Third
FIG. 2 is a cross-sectional view taken along the line IV-IV in the figure. (1)...Cathode ray tube, (4)...Degauss coil,
(5) Shadow mask, (6) Internal magnetic shield, (8) Magnetic cover. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A magnetic material provided on the outside of a degauss coil wound in a headband shape around the outer periphery of a screen side panel of a cathode ray tube having a magnetic shield made of a ferromagnetic material, and magnetically surrounding the degauss coil together with the internal magnetic shield. A cathode ray tube display device comprising a cover.