JPS6056338A - Manufacture of small size cathode ray tube - Google Patents

Abstract

PURPOSE:To obtain a highly efficient, high grade and small size cathode ray tube which does not result in ion spot by magnetizing, after exhausting the inside of tube, the magnetic ring which is disposed between the cathode and deflection yoke of electron gun and generates electron beam focusing magnetic field. CONSTITUTION:Since the electron gun constituting members which are disposed between the cathode 4 and deflection yoke 13 of electron gun and includes a magnetic ring 9 which generates electron beam focusing magnetic field is heated for exhausting gas during the exhausting process and does not always show the uniform distribution of heating temperature, magnetization of ferro magnetic ring 9 is carried out after exhausting the inside of tube. This magnetization apparatus 18 is composed of a U-shaped iron piece 9 and a coil 20 would thereto and the magnetic field of magnetization 23 is generated between a pair of magnetic poles 21, 22 by allowing a DC current to flow into the coil 20. The ring of cathode ray tube 24 to be processed after the exhaustion and disposed so that the tube axis becomes parallel to the magnetic field 23 is magnetized to have the specified coersive force.

Description

DETAILED DESCRIPTION OF THE INVENTION 'Industrial Field of Application The present invention relates to a method for manufacturing a miniature cathode ray tube, particularly a microcathode ray tube having a function of electrostatically and magnetically focusing an electron beam.

Conventional Structure and Problems Therein, a micro-sized cathode ray tube with a screen diagonal length of about 1.5 inches, 1 inch, or 0.5 inches is used as a view finder of a video camera. Since such cathode ray tubes are often driven by batteries, it is especially desirable that they operate with low power consumption and high efficiency.

Since the deflection power in the above-mentioned ultra-small cathode ray tube occupies a considerable proportion of the total power consumption, reducing the deflection power greatly contributes to power saving.

Since the deflection power is proportional to the anode voltage, lowering the anode voltage can reduce the deflection power, but lowering the anode voltage too much makes it difficult to obtain the necessary brightness at the phosphor screen surface. In cathode ray tubes that do not have a metal back on the phosphor screen surface, the necessary screen surface brightness can be obtained with a relatively low anode voltage, but so-called ion burn occurs on the phosphor screen surface. In addition, the LJ can also lower the anode voltage by reducing the thickness of the aluminum vapor-deposited film that constitutes the metal back, but by reducing this film thickness by half, for example, 0°031
The screen surface brightness (anode voltage 2KV) when set at 1 m is approximately half of the screen surface brightness (anode voltage 2KV) without Notarbac.
I can't say it's enough.

Furthermore, when the film thickness is reduced, wrinkles are formed on the film surface in a pattern. When viewing the phosphor screen surface through an optical lens such as in a viewfinder, the wrinkles become very unsightly.

OBJECTS OF THE INVENTION An object of the present invention is to provide a manufacturing method suitable for obtaining a high-efficiency, high-quality compact cathode ray tube that does not include a metal back and hardly causes ion burnout.

Structure of the Invention According to the manufacturing method of the present invention, the magnetic ring that is disposed between the cathode and the deflection yoke of an electrostatic focusing electron gun and generates an electron beam focusing magnetic field is magnetized after the tube is evacuated. This will be explained in detail below along with embodiments shown in the drawings.

In FIG. 1, an electrostatic focusing electron gun 3; 7, a cathode 4, a control electrode 5, an accelerating electrode 6, a focusing electrode 7j, . In addition, a ferromagnetic ring 9 is provided on the inner peripheral surface of the focusing electrode 7.
It has been attached. The ferromagnetic rod 9 is arranged coaxially with the gun axis, and is magnetized so that S and N poles are generated in the direction of the gun axis, thereby creating a magnetic field for electron beam focusing coaxial with the gun axis. generate.

On the other hand, the phosphor screen 11 attached to the inner surface of the face pile part 10 of the crow bulb 1 ((I) does not have a metal back, and the electron gun 3 and t) do not have a metal back. 12 is an internal conductive film held at the same potential as the anode 8, and 13 is a deflection yoke.

The modulated electron beam emitted from the electron gun 3 is deflected by the horizontal and vertical deflection magnetic fields produced by the deflection yoke 13, and a monochrome image is projected on the surface of the phosphor screen 11. After being prefocused by the focusing magnetic field of the modulated electron beam incident on the focusing electrode 7 or the magnetized ferromagnetic ring 9, it is finally focused by the main electron ring generated between the focusing electrode 7 and the anode 8. subject to a focusing effect. That is, the modulated electron beam incident on the focusing electrode 7 is focused by two films by the focusing magnetic field and the main electron lens.

On the other hand, the negative ions generated near the crossover between the control electrode 5 and the accelerating electrode 6 are focused by the main lens in the same way as the electron beam, but because they have a larger mass than the electrons, they are more intense. It is hardly affected by the focusing magnetic field 2 produced by the magnetic ring 9 and the deflection magnetic field produced by the deflection yoke 13. Therefore, the negative ions that are incompletely focused by the main lens impinge on a relatively wide area centered on the center of the phosphor screen 11, thereby preventing ion burn from occurring only in the center of the phosphor screen. do not have.

To explain this in more detail with reference to FIG. 2, the electron beam 14 shown by the solid line in the same figure is focused by the magnetic field lens 16f formed by the ferromagnetic ring 9 and the main electron lens 16 onto the surface of the phosphor screen 11. In contrast, the negative ion beam 17 shown by the broken line is mainly focused only by the main electron lens 16, so that the phosphor screen 110
It does not converge to one point on the surface, but is dispersed over a relatively wide area. For this reason, even though Eiji does not have Notarbanoku, the occurrence of ion burn is considerably alleviated.

In the above embodiment, the ferromagnetic ring 9 is used as the focusing electrode 7.
The ferromagnetic ring 9 may be provided coaxially (, , it suffices if the cathode 4 and the deflection yoke 13 are coaxially installed near the midpoint.

By the way, the electron gun component including the ferromagnetic ring 9 is
During the tube evacuation process, it is heated to a temperature of approximately 4000 °C for degassing. Furthermore, since the temperature distribution of this heating is not necessarily uniform, the coercive force of the ferromagnetic ring 9, which has been magnetized in advance, may change irregularly before and after the pipe evacuation process.

If this happens, it becomes difficult to obtain the desired ion content, scattering effect, and electron beam focusing effect satisfactorily.

Therefore, in the present invention, the magnetization process for the ferromagnetic ring 9 is performed after the tube is evacuated. Magnetization processing device 18 shown in FIG.
consists of a U-shaped iron piece 19 and a coil 2o wound around it, and by passing a direct current through the coil 20, the
A magnetizing magnetic field 23 is generated between the pair of magnetic pole parts 21 and 22. The ferromagnetic ring of the evacuated cathode ray tube 24 to be processed, which is arranged so that the tT axis is parallel to the magnetic field 23, is magnetized to a predetermined coercive force by the magnetic field 23.

When the completed/ζ cathode ray tube is operated, if the focused state of the electron beam is not optimal, the device 18 may be used to re-magnetize or demagnetize it.

Effects of the Invention Since the method for manufacturing a small cathode ray tube of the present invention is configured as described above, it is possible to obtain a high efficiency small cathode ray tube that can obtain sufficient brightness with a relatively low anode voltage and has almost no fear of ion burnout. Not only this, but also the uniformity of the magnetization and coercive force of the ferromagnetic ring can be obtained, and the reduction in resolution due to variations and changes in the electron beam focusing magnetic field can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a small-sized camellia wire tube that is the object of the present invention;
FIG. 2 is an explanatory diagram of the operation of the magnetic field lens and the main electron lens formed by the ferromagnetic ring of the cathode ray tube, and FIG. 3 is a perspective view showing an example of the magnetization processing device applied in the manufacturing method of the present invention. be. 3- Electron gun, 4... steep, 7... focusing electrode,
9 ・Ferromagnetic ring, 11 Fluorescent screen, 13
... Deflection yoke. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 0 /

Claims (1)

[Claims] an electrostatic focusing electron gun; a phosphor screen that faces the electron gun without intervening a metal back; and a magnetic field disposed between the cathode and the deflection yoke of the electron gun to generate a magnetic field for focusing the electron beam. 1. A method of manufacturing a small cathode ray tube, comprising: magnetizing the ferromagnetic ring after the tube is evacuated.