JP3023678B1 - Degaussing device for cathode ray tube - Google Patents

Abstract

An object of the present invention is to provide a degaussing device that enables sufficient degaussing of a large cathode ray tube with a simple configuration and a small alternating decay current. SOLUTION: The coil includes a degaussing coil having an air core portion wider than a face plate of a cathode ray tube, and a power supply circuit for generating an alternating decay current flowing through the coil, wherein a magnetic field generated by the alternating decay current flowing through the coil is provided. In a cathode ray tube degaussing apparatus in which a face plate is provided at a position opposed to the air core of the cathode ray tube to degauss the cathode ray tube, an air core coil 12 for degaussing is formed such that one side 12a has an upper surface 12a of the face plate 6 of the cathode ray tube 6. The coil 1 is bent in a substantially L-shape so as to be located at
The direction of the magnetic field at the center position of the air core where 2 occurs is inclined with respect to the face plate 6a of the cathode ray tube 6, and a magnetic field component in the direction along the face plate 6a is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degaussing device for a cathode ray tube.

[0002]

2. Description of the Related Art For example, a cathode ray tube (CRT) used as a picture tube of a color television is subjected to color inspection at the final stage of the manufacturing process. In this case, if the electrodes and auxiliary metal fittings in the cathode ray tube are magnetized and the magnetism remains, the electron beam bends and color unevenness occurs, so that precise inspection cannot be performed. Therefore, before the inspection, the magnetization of the cathode ray tube is removed, that is, degaussing is performed.

FIG. 3 shows a schematic configuration of a degaussing apparatus for performing such degaussing. The degaussing apparatus mainly generates an alternating attenuation voltage (a voltage that gradually reduces the amplitude of an AC voltage and finally reduces it to 0). And a demagnetizing air-core coil 2 that receives an alternating attenuation voltage from the power supply circuit 1 and generates an alternating attenuation magnetic field. The power supply circuit 1
A thyristor connected to a commercial AC power supply 3 of 00 V or 200 V, 50 Hz or 60 Hz; and a gate control circuit 1 a for generating a gate control signal for transmitting a conduction angle of the thyristor to an AC voltage in a time series manner. An alternating decay voltage (alternate decay current) is generated by attenuating the AC voltage input by the signal in a time-series manner and finally reducing the voltage to 0 voltage. The degaussing air core coil 2 has a rectangular shape, and the air core portion is formed wider than the face plate of the cathode ray tube.

As shown in FIG. 4, the degaussing by the degaussing apparatus constructed as described above is performed by placing an air core parallel to the transport conveyor 4 at a predetermined position on a transport line that goes through each manufacturing process of the cathode ray tube comprising the transport conveyor 4. The coil 2 is arranged, and a face plate (face plate) 6a of a cathode ray tube 6 placed on a pallet 5 for moving each manufacturing process by a conveyor 4 is positioned so as to face the air-core coil 2, and an alternating decay current is supplied to the air-core coil 2. To generate an alternating attenuating magnetic field, and applying the magnetic field to the cathode ray tube 6.

In this case, as shown in FIG. 5, the magnetic field generated by the air-core coil 2 is such that the magnetic field Φ at the center position of the air-core portion of the air-core coil 2 is a cathode wire positioned at a position facing the air-core portion of the air-core coil 2. It is formed in a direction penetrating substantially at right angles to a shadow plate 6b which is a main metal part of the cathode ray tube 6 attached to the face plate 6a of the tube 6, more specifically, the cathode ray tube 6 mounted close to the face plate 6a, and alternates the shadow mask 6b in its thickness direction. It is magnetized and its magnetization is attenuated over time, eventually to zero, thereby extinguishing the remanence.

[0006]

By the way, recently, the cathode ray tube 6 has been increased in size and width.
When the size becomes large like a 34.36 inch wide flat tube, the degaussing using the commercial AC power supply 3 as described above
As shown in FIG. 6, the metal portion located in the band-shaped region 6c at the center of the face plate 6a of the cathode ray tube 6 cannot be sufficiently demagnetized, and color unevenness occurs in this region 6c. In order to eliminate this, there is a problem that an AC power supply equipment for flowing a large alternating decay current to the air core coil 2, for example, a large capacity transformer must be prepared.

The present invention has been made in view of such a problem, and does not require a large-scale AC power supply facility, and enables sufficient demagnetization of a large cathode ray tube with a simple configuration and a small alternating decay current. An object is to provide a degaussing device.

[0008]

According to a first aspect of the present invention, there is provided a coil having an air core portion wider than a face plate of a cathode ray tube, and a power supply circuit for generating an alternating attenuation current flowing through the coil. In a cathode ray tube degaussing device for applying a magnetic field generated by an alternating current to flow to a cathode ray tube having a face plate disposed at a position facing the air core portion of the coil and degaussing the cathode ray tube, the center of the air core portion where the coil is generated The direction of the magnetic field at the position is inclined with respect to the face plate of the cathode ray tube.

According to a second aspect of the present invention, there is provided a coil having an air core wider than a face plate of a cathode ray tube, and a power supply circuit for generating an alternating decay current flowing through the coil. In a cathode ray tube degaussing device for applying a magnetic field to a cathode ray tube having a face plate disposed at a position facing an air core portion of the coil to degauss the cathode ray tube, the coil is disposed along the outer periphery of the face plate portion of the cathode ray tube. It is characterized by being formed in an L-shape.

In the present invention, since the magnetic field at the center of the air core generated by the air core coil penetrates obliquely to the face plate of the cathode ray tube, the magnetic field component is perpendicular to the face plate of the cathode ray tube and in a direction parallel to the face plate. Is formed, and the metal component located at the center of the face plate of the cathode ray tube can be effectively demagnetized by the magnetic field component. Further, when the air-core coil is formed to be bent in a substantially L shape along the outer periphery of the face plate portion of the cathode ray tube, it can be arranged at a predetermined position of the transport line of the cathode ray tube without obstructing the movement of the cathode ray tube, and the face plate of the cathode ray tube can be arranged. Can be applied to the magnetic field in an oblique direction.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a degaussing device according to an embodiment of the present invention. Parts corresponding to those of the conventional degaussing device shown in FIG. 3 are denoted by the same reference numerals. In FIG. 1, reference numeral 12 denotes a degaussing air core coil.

The degaussing air core coil 12 is, for example, 2t ×
An air core part wider than the face plate (face plate) 6a of the cathode ray tube 6 for demagnetizing a 4t soft copper wire, for example, a cathode ray tube of 33 inches is wound squarely, for example, 94 times as an air core part of 750 mm in width and 610 mm in length. The upper part of the vertically extending sides (one side of the short side) 12b opposed to each other is bent so that one side (one side of the long side) 12a extending in the lateral direction of the wound coil is located on the upper surface of the cathode ray tube 6. About L
It is bent in a letter shape. Note that this bending does not prevent the parallel movement of the cathode ray tube 6, and the bending angle may be set appropriately, and the winding may be performed while forming a bent state.

The degaussing by the air-core coil 12 is performed in the same manner as in the prior art shown in FIG. An air-core coil 12 is arranged in parallel with the conveyor 4, and the face plate (face plate) 6a of the cathode ray tube 6 placed on a pallet 5 for moving each manufacturing process by the conveyor 4 is positioned so as to face the air-core coil 12. This is performed by supplying an alternating attenuating current from the power supply circuit 1 to the air core coil 12 to generate an alternating attenuating magnetic field, and applying the magnetic field to the cathode ray tube 6.

In this case, as shown in FIG. 2, the magnetic field generated by the air-core coil 12 is such that the magnetic field Φ at the center position of the air-core portion of the air-core coil 12 is a cathode wire positioned at a position facing the air-core portion of the air-core coil 12. It is inclined by θ degrees (θ is set to approximately 72 degrees in this embodiment) with respect to the face plate 6 a of the tube 6, more specifically, the shadow mask 6 b attached in close proximity to the face plate 6 a. Face plate 6
a, the shadow mask 6b is alternately magnetized in its thickness direction (horizontal direction) Φx and width direction (vertical direction) Φy, and its magnetization is attenuated to eliminate the residual magnetization of the metal part. Let it.

In this alternating magnetic field, the total amount of the magnetic field .PHI.x in the direction perpendicular to the face plate is large, but the magnetic flux density is small because the positive area of the shadow mask 6b is large. However, although the total amount of the magnetic field φy in the direction parallel to the face plate is small, the shadow mask 6
b, the magnetic flux density increases because of the small cross-sectional area, and the shadow mask 6
b is strongly magnetized, and the small alternating decay current can sufficiently demagnetize the portion located in the band-like region at the center of the face plate of the large cathode ray tube.

In the above embodiment, the air-core coil is formed in a substantially L-shape so as not to hinder the parallel movement of the cathode ray tube, and the cathode ray tube on the transport line is demagnetized without providing a special moving mechanism. Simple and convenient
You.

Incidentally, a rectangular air-core coil in which a copper wire was wound 90 times was prepared, and this air-core coil was previously magnetized.
Parallel to the 5 inch color cathode ray tube face plate as before,
In other words, the magnetic field at the center of the air core of the air core coil is
The cathode-ray tube is disposed in a direction penetrating at right angles (90 degrees) to the face plate of the cathode-ray tube positioned at a position facing the air-core portion of the air-core coil. The maximum current required when it was possible to eliminate was 31 Ap.

Subsequently, the air-core coil is inclined with the center position as a fulcrum, and the magnetic field at the center position of the air-core portion of the air-core coil is inclined with respect to the face plate of the cathode ray tube positioned at a position facing the air-core portion of the air-core coil. In the direction that penetrates the
When the inclination angle with respect to the face plate is set to 80 degrees, the maximum current required when the color unevenness can be eliminated is 16 Ap,
15 Ap at 70 degrees, 13 A at 60 degrees
p was 45 Ap and it was 12 Ap.

From this result, it is possible to obtain a high efficiency of about two times or more by tilting in the range of 70 to 80 degrees, and to avoid mechanical interference with the movement of the cathode ray tube in a small space even with a rectangular air core coil. It can be understood that the air-core coil can be arranged.

[0020]

As described above, according to the present invention,
Since the magnetic field at the center position of the air core generated by the air core coil penetrates obliquely to the face plate of the cathode ray tube, the metal part located at the center of the face plate of the cathode ray tube can also be effectively demagnetized, and Even in the case of a cathode ray tube, degaussing is enabled by the same power supply equipment as in the past, and the power required for degaussing can be reduced regardless of the size of the cathode ray tube.

When the air-core coil is formed in a substantially L-shape along the outer periphery of the face plate portion of the cathode-ray tube, the air-core coil can be disposed on the face plate of the cathode-ray tube with a simple structure in which the air-core coil is arranged along the transport line of the cathode ray tube. In contrast, a magnetic field in an oblique direction can be applied, and a low-cost degaussing device that does not require a mechanical driving device or the like for degaussing can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a degaussing device according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the degaussing device of FIG. 1;

FIG. 3 is a configuration diagram of a conventional degaussing device.

FIG. 4 is an explanatory view of an arrangement of a degaussing device.

FIG. 5 is a diagram illustrating the operation of a conventional degaussing device.

FIG. 6 is a diagram illustrating the operation of a conventional degaussing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply circuit 1a Gate control circuit 3 Commercial AC power supply 4 Conveyor 5 Pallet 6 Cathode ray tube 6a Face plate of cathode ray tube 6b Shadow mask 12 Air-core coil for degaussing

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuharu Morishima 18 Kochishin Electric Co., Ltd. 18 Shichijo-Goshinonai Nishimachi, Shimogyo-ku, Kyoto-shi, Kyoto (56) References JP-A-9-9281 (JP, A) 60-43084 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 9/29 H01F 13/00

Claims (1)

(57) [Claims] A coil having an air core wider than a face plate of a cathode ray tube and a magnetic field for generating an alternating attenuation current flowing through the coil are applied to a cathode ray tube having a face plate disposed at a position facing the air core of the coil. In a cathode ray tube degaussing apparatus for degaussing a cathode ray tube, the coil is formed by bending an upper portion extending in a vertical direction along an outer periphery of a face plate portion of the cathode ray tube so as to be bent substantially in an L-shape, and the bent coil portion is formed.
A degaussing device for a cathode ray tube, which is located on an upper surface of the cathode ray tube.