JPS62296345A - Inline type color picture tube - Google Patents

Abstract

PURPOSE:To get rid of the axial separation of an electron beam at a main lens as well as to make a halo in and around a faceplate reducible, by connecting a coil of a compensator to a vertical deflecting coil electrically in series or parallel. CONSTITUTION:When an electron beam 5 is deflected to the upside of a faceplate by a deflecting yoke, electric current flows into a coil 22 in such a direction as shown by an arrow in illustration. With this current flow, it comes to generate a corrective magnetic field 24 in the right direction in consequence, so that a vertical deflecting leakage field 25 can be offset. And, axial separation of the electron beam 5 at a main lens area attributable to this field 25 is reducible to the minimum. Therefore, since the electron beam 5 is able to minimize distortion of the beam received from spherical aberration of the main lens, a halo to be produced inward at an upper part of the faceplate is thus reducible.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an in-line color picture tube, and particularly to a deflection magnetic field generated by a deflection yoke for deflecting an electron beam toward the electron gun side. This invention relates to a correction device that reduces deterioration of the spot shape of an electron beam caused by leakage magnetic fields.

[Conventional technology]

In general, an in-line color picture tube, as shown in FIG. 2, includes an envelope 1 whose inside is evacuated to a high vacuum, and red and blue lights arranged on the inner face of the envelope 1.

Green multiple phosphor stripes or phosphor dora I
・A fluorescent film 2 consisting of a fluorescent film 2, a shadow mask 3 having an X-selective transmission function for causing any phosphor on the fluorescent film 2 to emit light, and a shadow mask 3 arranged side by side in the same horizontal plane.
The in-line electron gun 4, the deflection yoke 6 for deflecting the three electron beams 5 emitted from the in-line electron gun 4, and the color shift and static convergence caused by variations in assembly of the electron gun are corrected. Two poles for
It has a utility convergence device 7 that can generate four-pole and six-pole magnetic fields. In an in-line color picture tube, the electron guns 4 are arranged side by side in the same horizontal plane as described above, and the horizontal deflection magnetic field distribution created by the deflection yoke 6 is shown in FIG.
By setting the pincushion distortion as shown in a) and the barrel distortion for the vertical deflection magnetic field distribution as shown in Fig. 3(b), it is possible to generate the output from three electron guns 4 without using any special convergence correction. Since it uses a so-called self-convergence system in which the three emitted electron beams 5 can be concentrated over the entire surface of the screen, high-quality images can be obtained at low cost.

[Problems to be Solved by the Invention] Generally, the resolution of a color picture tube largely depends on the beam diameter of the electron beam, and the smaller the beam diameter, the higher the resolution and the higher the quality of the image. . The conventional in-line color picture tube described above uses a self-convergence system, which makes it possible to concentrate three electron beams over the entire image, but the horizontal deflection magnetic field distribution is pincushion distorted, and the vertical one flattened magnetic field distribution. Since this is barrel distortion, the electron beam that passes through the deflection magnetic field and reaches the screen is distorted. FIG. 4 shows the beam shape of the electron beam on the screen. It is circular at the center of the screen, but a hollow 10 is formed around the beam core 9 at the periphery of the screen. The halo 10 at the top and bottom of the screen in FIG. This is noticeable because it affects the inside.

FIG. 5 is a diagram explaining that the halo tends to extend toward the inside of the screen, and the electron beam emitted from the cathode 11 is transmitted to the G1 electrode 12. G2 electrode 13°G3 electrode 14. The electron beam passes through the G4 electrode 15 and reaches a fluorescent film (not shown).When the electron beam is not deflected, that is, when the electron beam reaches the center of the screen, there is no magnetic field generated by the vertical image yoke, and therefore there is no leakage magnetic field. The trajectory of the electron beam is as shown by beam trajectory 17 between the G3 electrode 111 and the G3 electrode 111.
It passes through the center of the main lens 16 formed between the four electrodes 15. On the other hand, when the electron beam is deflected toward the top of the screen, for example, there is a leakage magnetic field toward the electron gun due to the vertical deflection yoke, so the trajectory of the electron beam changes as shown by beam trajectory 18 before passing through the main lens 16. The first direction begins at , and passes through the upper part of the main lens 16 . In an electric field lens such as a main lens, lens aberration generally increases in proportion to the cube of the distance from the center of the lens. Therefore, when an electron beam passes through the upper part of the lens as described above, the aberration of the lens is larger than when there is no deflection, so a halo extending toward the bottom of the screen is generated.

When the light is deflected toward the bottom of the screen, the opposite is true, so the halo ends up extending to 1jl within the screen, as shown in FIG. This halo is a collar receiver ('A tube solution ('A degree 1
('IA quality deteriorates significantly.

[Means for solving problems]

The in-line color picture tube according to the present invention is provided with a pair of correction devices for canceling the leakage magnetic field from the linear deflection magnetic field on the outer periphery of the envelope closer to the cathode than the main lens area of the electron gun, By electrically connecting the coil of this correction device and the vertical deflection coil in series or parallel, the off-axis of the electron beam at the main lens is eliminated and the halo around the screen is reduced.

〔Example" Next, the present invention will be explained using the drawings.

FIG. 1 shows an embodiment of an in-line color picture tube according to the present invention, and shows a sectional view seen from the screen side. The position of this correction device in the tube axis direction is closer to the cathode than the main lens region in FIG.

In FIG. 1, there are three in-line electron beams 5 arranged in the same horizontal plane inside the envelope 1.
A pair of upper and lower correction devices 23 each consisting of a core 21 and a coil 22 wound around the core 21 are attached to the outside of the envelope 1 . The coil 22 is connected to a pair of vertical deflection coils 26, and the current flowing through the coil 22 is connected to a variable resistor 2.
7, it can be increased or decreased.

Next, the operation of this embodiment will be explained. The electron beam is I
When the Q-direction yoke causes the screen to be deflected by one angle towards the top of the screen, current flows through the coil 22 in the direction shown by the arrow in the figure, which generates a correction magnetic field 24 in the right direction, resulting in vertical deflection. The leakage magnetic field can be offset by 25 minutes, and the off-axis of the electron beam in the main lens region caused by the vertical deflection leakage magnetic field 25 can be minimized. Therefore, the distortion of the electron beam caused by the spherical aberration of the main lens can be minimized, so that the barlow that occurs inward above the screen can be reduced. Furthermore, when the electron beam is deflected downward, the polarity is reversed and the halo generated inward at the bottom of the screen can be reduced, just as in the above case. In FIG. 1, the variable resistor 27 is provided with an adjustment function to optimize the amount of halo correction, and is not necessarily necessary.

(Effects of the Invention) As explained above, the present invention reduces the separation of the electron beam at the main lens due to the leakage magnetic field of the deflection magnetic field generated by the vertical deflection yoke toward the electron gun side, which is a cause of deterioration of resolution 2 display quality. By reducing the halo caused by the shaft,
It has the effect of being able to obtain high-resolution ('A), high-quality images over the entire screen.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of an in-line color picture tube according to the present invention, FIG. 2 is an explanatory diagram of a conventional in-line color picture tube, and FIG. 3(a). (b) is a diagram showing the magnetic field distribution of the self-convergence method, and FIG. 4 is a diagram showing the beam shape on the screen. FIG. 5 is a diagram for explaining the deterioration of the beam shape. ■... Envelope, 2... Fluorescent film, 3... Shadow mask. 4... In-line electron gun, 6... Deflection yoke, 9...
... Beam core, 10... Halo, 22... Coil, 23... Correction device, 24... Correction magnetic field, 25...
・Vertical deflection leakage magnetic field, 27...variable resistance. / ,7・,＼ Agent Patent Attorney Susumu Uchihara ) 1,7・″ 81 Zuman'2 Ward 3rd Ward

Claims (1)

[Claims] Three electron guns are arranged side by side in the same horizontal plane,
In a self-convergence type in-line color picture tube with pincushion distortion in the horizontal deflection magnetic field distribution and barrel distortion in the vertical deflection magnetic field distribution, the vertical deflection magnetic field is applied to the outer periphery of the envelope on the cathode side of the main lens area of the electron gun. 1. An in-line color picture tube, comprising: a pair of correction devices for canceling leakage magnetic fields; and a coil of the correction device and a vertical deflection coil are electrically connected.