JPH0687397B2 - Magnetic transfer method of cathode ray tube - Google Patents

Description

The present invention relates to a magnetic transfer method for correcting the inclination of a beam landing pattern in a zero magnetic field of a cathode ray tube, that is, a so-called landing twist component.

[Outline of Invention]

The present invention is a magnetic transfer method for a cathode ray tube, in which a bias magnetic field is applied using a ring coil arranged in the vicinity of the color selection electrode, and in this state, an alternating damping magnetic field is applied by a degauss coil to apply a magnetic field to the color selection electrode. By transferring, it is possible to correct the landing twist component in the zero magnetic field.

[Conventional technology]

In the color cathode ray tube, the color selection electrode is mounted in the panel via a support spring so as to face the fluorescent surface.However, for example, mechanical displacement of the color selection electrode based on the spring pressure causes a zero magnetic field. The landing pattern of the electron beam changes depending on the state. This change in the landing pattern results in a state of being tilted with respect to the Y axis of the screen as shown by the broken line (1) in FIGS. 4A and 4B, and this is usually called a landing twist. Conventionally,
For example, in the case of a large tube type, a cathode ray tube is placed in a magnetic field generated by a mini Helmholtz coil, and a strong AC damping magnetic field is applied to shape the landing pattern.

[Problems to be solved by the invention]

When using the above-mentioned Mini Helmholtz coil, the amount of landing correction that can be corrected is very small,
There is a limit to the correction by this. Further, since the coil for generating magnetic flux in the tube axis direction of the cathode ray tube is not incorporated, the twist component of the landing pattern in the completed tube cannot be corrected. Conventionally, a method of correcting an average twist tendency by using a lens at the time of manufacturing the fluorescent surface has been adopted, but it is considerably large until the introduction of a new correcting lens according to a new tube type. It takes a long time, and the cost for doing so is quite high. Also, in the set assembly factory, one or two magnets are attached to the funnel to correct the landing of the screen corners, but this may cause image distortion when correcting the twist component near the so-called Y axis in the center. In addition, since the correction effect cannot be obtained sufficiently, the magnet correction is not performed in principle. Therefore, a finished tube having a large twist component is regarded as defective.

In view of the above points, the present invention provides a method for magnetic transfer of a cathode ray tube that enables correction of twist components in a zero magnetic field.

[Means for solving problems]

In the present invention, a bias magnetic field is generated in the tube axis direction using a ring coil (11) arranged so as to surround the vicinity of the color selection electrode of the cathode ray tube (12), and the decaus coil is applied with this bias magnetic field. An alternating magnetic field is applied by (17) to perform magnetic transfer to the color selection electrode.

[Action]

A magnetic flux can be generated in the tube axis direction of the cathode ray tube (12) by using the ring coil (11) arranged so as to surround the cathode ray tube (12) in the vicinity of the color selection electrode. When a strong bias magnetic field in this direction is applied and an alternating damping magnetic field is applied to demagnetize, the ring coil (1
The magnetic field generated in 1) is transferred to the color selection electrode, which makes it possible to correct the twist component of the landing pattern at zero magnetic field.

The amount of twist correction is changed by changing the value of the current flowing through the ring coil (11), and if the polarity of the current is reversed, the correction can be performed in the opposite direction.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

The twist correction ring coil (TRC) (11) for applying the bias magnetic field used in this embodiment has a diameter of 0.8 mm.
The copper wire is wound 300 turns to a size slightly larger than the circumference of the tension band attached to the cathode ray tube (12). The panel of the cathode ray tube (12) is provided near the color selection electrode (for example, the aperture grille) of the cathode ray tube (12) in which the twist correction ring oil (TRC) (11) is arranged with the panel surface (15) facing downward. It is arranged so as to surround (13). (18) is the funnel, (19) is the neck,
(20) is an anode button, and (21) is a spacer. When a current of 2 A is applied to the twist correction ring coil (11) from the DC power supply (14), a magnetic flux is generated in the Z-axis direction (16), that is, the tube axis direction with respect to the panel surface (15). The required number of turns of the coil (11) may vary depending on the capacity of the DC power supply (14), but from several experiments, 600 AT (current x number of turns) is suitable. Further, in the present embodiment, the degauss coil for giving an AC damping magnetic field is arranged at a predetermined interval so as to surround the twist correction ring coil (11) around the cathode ray tube (12) as shown in the figure. Uses a triac degauss coil (TA) (17). (2
2) is a power supply for this coil (17), and (23) is a fitting. Then, with a bias magnetic field applied by the twist correction ring coil (11), this triac degauss
When a strong alternating magnetic field is applied by the coil (17),
Magnetism having a shape that cancels the twist component of the landing pattern is transferred to the color selection electrode. After this, the DC power supply (14) is turned off. Then, by changing the value of the current flowing in the twist correction ring coil (11), the correction amount of the twist component changes accordingly, and by reversing the polarity of the current, the twist component can be corrected in the opposite direction. is there.

FIGS. 3A to 3C show the values of the currents flowing in the twist correction ring coil (11) in the 14-inch high-definition tube of 1A, 2A, and
It shows the change in the correction amount of the twist component when changed to 2.8A. According to this, the correction amount increases as the current value increases. Twist correction ring coil (11)
From various experiments, it has been clarified that the closer to the color selection electrode the location is, the greater the effect is, and when the location is located on the panel surface (15) side, the correction effect is reduced. In this example, the grill height (distance between the panel inner surface and the color selection electrode) in the central portion of the panel surface (15) was 6.34 mm, which was as small as 14 inches. It can be estimated that the correction effect of the twist component is further increased. This is because the larger the grill height is, the more the influence of the rod-shaped degauss used by the assembly shop and the service person can be avoided. In the present invention, magnetic transfer having a strength not erased by the rod-shaped degauss and the automatic degaussing circuit of the receiver can be performed on the cathode ray tube. As an example of generating a magnetic field in the tube axis direction of the cathode ray tube, when the size of the tube becomes large, the twist correction ring coil may be divided into a plurality of ring coils and provided on the tube surface.

〔The invention's effect〕

According to the present invention, a magnetic flux stronger than that of the conventional Mini Helmholtz coil is generated in the tube axis direction of the cathode ray tube to perform degaussing, so that the twist component having a large landing pattern can be corrected. Therefore, no correction lens is required, and a device simpler than the mini Helmholtz coil is required.

[Brief description of drawings]

FIG. 1 is a front view of the embodiment, FIG. 2 is a plan view of the embodiment, and FIGS. 3A to 3C are measurement diagrams showing changes in the twist correction amount when the current value flowing in the twist correction ring coil is changed. ,
FIGS. 4A and 4B are diagrams showing twist components used for explaining the present invention. (11) is a twist correction ring coil, (12) is a cathode ray tube, (13) is a panel, (15) is a panel surface, and (17) is a triac degauss coil.

Claims (1)

[Claims] 1. A cathode ray tube, wherein a bias magnetic field is applied by a ring coil surrounding a color selection electrode of a cathode ray tube, and an alternating damping magnetic field is applied by a degauss coil to magnetically transfer the color selection electrode. Tube magnetic transfer method.