JP3041891B2 - Cathode ray tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube, and more particularly to a cathode ray tube in which a deflection yoke having a horizontal deflection coil and a vertical deflection coil is attached from a neck portion to a funnel portion. . In the present application, the cathode ray tube is appropriately replaced with a CRT (Cathode R
ay Tube).

[Summary of the Invention]

By pre-deflecting the electron beam before entering the deflection yoke in the reverse direction according to the vertical deflection, it cancels out the pre-deflection due to the leakage magnetic field, and increases the neck shadow margin,
Thus, the deflection efficiency is improved by lowering the deflection yoke later.

[Conventional technology]

In the CRT, an electron beam emitted from an electron gun is swung right and left and up and down on a front screen surface so as to illuminate phosphors on the entire screen. In order to oscillate the electron beam horizontally and vertically in this way, a CRT
A deflection yoke is attached from the neck to the funnel. The deflection yoke has a horizontal deflection coil and a vertical deflection coil, and a saw-tooth current is applied to each of these coils so that the electron beam scans on the screen surface. Deflection coils are classified into saddle type and toroidal type depending on the winding system.
From the viewpoint of power consumption and mass productivity, a saddle type coil is used for the horizontal deflection coil, and a toroidal type coil is used for the vertical deflection coil.

[Problems to be solved by the invention]

The toroidal coil used for the vertical deflection coil has a larger leakage magnetic field in the front-rear direction than the saddle-type horizontal deflection coil. Therefore, due to such a leakage magnetic field,
Before the electron beam enters the deflection yoke, it is already deflected and pre-deflected. That is, the electron beam is vertically decentered in the main magnetic field of the deflection yoke according to the vertical magnetic field.

Since the electron beam is pre-deflected by the leakage magnetic field before entering the deflection yoke in this way, the deflection center is set to reduce the margin of the neck shadow due to the deflection, that is, the shadow generated on the screen by the beam hitting the funnel. It must be close to the panel side, which inevitably results in a large deflection yoke and poor efficiency.

The present invention has been made in view of such a problem, and it is an object of the present invention to provide a CRT that improves deflection efficiency by suppressing deflection until an electron beam enters a deflection yoke. Things.

[Means for solving the problem]

The present invention relates to a cathode ray tube in which a deflection yoke having a horizontal deflection coil and a vertical deflection coil is attached from a neck portion to a funnel portion, wherein the deflection yoke is located on the rear side of the deflection yoke and forward of the front end of the electron gun. An auxiliary coil is provided at the position, and the auxiliary coil generates a magnetic field that causes a deflection in a direction opposite to the pre-deflection of the electron beam due to a leakage magnetic field by the vertical deflection coil of the deflection yoke, so as to increase a vertical neck shadow margin. The present invention relates to a cathode ray tube characterized by the following.

[Action]

Accordingly, the auxiliary coil generates a magnetic field that causes the electron beam to be deflected in the direction opposite to the pre-deflection of the electron beam due to the leakage magnetic field by the vertical deflection coil of the deflection yoke, thereby correcting the pre-deflection of the electron beam. As the neck shadow margin increases in the direction, the deflection yoke can be shifted backward and toward the electron gun as the neck shadow margin increases, thereby improving the deflection efficiency of the deflection yoke.

〔Example〕

FIG. 1 shows a CRT 10 according to an embodiment of the present invention. The CRT 10 has a deflection yoke 11 from its funnel to its neck. The deflection yoke 11 includes a horizontal deflection coil 12 and a vertical deflection coil 13. The horizontal deflection coil 12 is composed of a saddle type coil.
On the other hand, the vertical deflection coil 13 is formed of a toroidal type coil, and is attached to the core 14 on the horizontal deflection coil 12 in a dried state. An electron gun 15 is arranged inside the neck of the CRT 10, and this electron gun 15
As shown in FIG. 2, a beam of three colors of R, G and B is emitted in-line by means of 15. That is, the CRT 10 constitutes an in-line type trinitron tube.

An auxiliary coil 18 is mounted on the electron gun 15 side behind the deflection yoke 11. The auxiliary coil 18 has a pair of upper and lower cores 19 as shown in FIG. 2, and is composed of a coil 18 wound around these cores 19. A magnetic field 20 is formed by such a coil 18. This magnetic field 20 is a magnetic field in the opposite direction to the vertical deflection magnetic field 21. The auxiliary coil 18 is connected in series with the vertical deflection coil 13 as shown in FIG. 3, and is driven by a current from the vertical deflection circuit 22.

As described above, in the CRT 10 according to the present embodiment, the auxiliary coil 18 is attached to the electron gun 15 side behind the deflection yoke 11, and a vertical deflection current is supplied to the auxiliary coil 18 as shown in FIG. I have to. As shown in FIG. 2, the direction of the magnetic field generated by the auxiliary coil 18 is opposite to the direction of the vertical main deflection magnetic field 21 generated by the vertical deflection coil. Leakage magnetic field of deflection yoke 11, especially vertical deflection coil 13
The beam is pre-deflected in the same direction as the vertical deflection direction as shown by the dotted line in FIG. However, when the magnetic field 20 is generated by the auxiliary coil 18 as described above, this magnetic field 20 deflects the electron beam in the opposite direction, and the beam advances as shown by the solid line in FIG. Therefore, the amount of beam deflection when the beam enters the main magnetic field of the deflection yoke 11 is reduced, and the neck shadow margin shown in FIG. 1 can be increased. By increasing the margin of the neck shadow in this way, the deflection yoke 11 is moved
It can be lowered to the 15 side, which can improve the deflection efficiency.

〔The invention's effect〕

As described above, the present invention is directed to a cathode ray tube in which a deflection yoke having a horizontal deflection coil and a vertical deflection coil is attached from a neck portion to a funnel portion, at the rear side of the deflection yoke and at the front end of the electron gun. An auxiliary coil is provided at a position forward of the auxiliary yoke to generate a magnetic field in the auxiliary yoke that causes a deflection in a direction opposite to the pre-deflection of the electron beam due to a leakage magnetic field by the vertical deflection coil of the deflection yoke, so as to increase a vertical neck shadow margin. It was made.

Therefore, according to the present invention, it is possible to increase the vertical neck shadow margin of the electron beam in the vertical direction by predeflecting the electron beam and deflecting the electron beam in the opposite direction by the leakage magnetic field by the vertical deflection coil of the deflection yoke. become. Accordingly, this eliminates the occurrence of shadows in the images in the upper and lower portions of the screen. In addition, since the neck shadow margin increases, the deflection yoke can be moved rearward, that is, moved toward the electron gun, and can be mounted. As a result, the deflection efficiency of the deflection yoke is improved. Therefore, the power consumption of the deflection yoke can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a CRT according to one embodiment of the present invention,
FIG. 2 is a front view showing a magnetic field generated by the auxiliary coil, and FIG. 3 is a drive circuit diagram of the deflection coil. The names of the main parts in the drawings are as follows. 10 CRT 11 Deflection yoke 12 Horizontal deflection coil 13 Vertical deflection coil 15 Electron gun 18 Auxiliary coil 19 Core 20 Magnetic field 21 Vertical deflection magnetic field 22 Vertical deflection circuit

Claims (1)

(57) [Claims] 1. A cathode ray tube in which a deflection yoke having a horizontal deflection coil and a vertical deflection coil is attached from a neck portion to a funnel portion, the cathode ray tube being located on the rear side of the deflection yoke and more than the front end of the electron gun. An auxiliary coil is provided at a front position, and a magnetic field that causes a deflection in a direction opposite to the pre-deflection of the electron beam due to a leakage magnetic field by the vertical deflection coil of the deflection yoke is generated by the auxiliary coil so as to increase a vertical neck shadow margin. A cathode ray tube characterized in that: