JP2001325901A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation of brightness caused by excessively using evaporative getter for being longer lasting. SOLUTION: Using a cathode-ray tube with a non-evaporative getter and a little evaporative getter mounted on it, an adverse effect on brightness function resulting from degradation of transmittance of electron beam by the evaporative getter is eliminated, and long life of the cathode-ray tube is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube which outputs an image by scanning an electron beam.

[0002]

2. Description of the Related Art In a conventional cathode ray tube, an electron tube is provided in a neck of an envelope including a panel having a fluorescent screen formed on an inner surface thereof and a shadow mask mounted thereon and a neck connected to the panel via a funnel. A gun is mounted, and a valve spacer provided on the electron gun is connected to an anode terminal through an internal conductive film formed on an inner surface from a neck to a funnel. A getter support is provided from the electron gun so as to be in elastic contact with a predetermined portion of the internal conductive film in the funnel, and a getter made of a metal container filled with getter material powder is provided at this end. The getter is induction-heated from the outside by a high-frequency heating coil so that barium is flushed in a predetermined direction of the envelope, and the inside of the envelope is made to have a high vacuum. Such a conventional CRT is described in JP-A-59-46735.

Generally, a getter captures and restrains gas molecules on a special surface or inside a solid in a vacuum space,
It has an exhaust function of removing gas molecules from the vacuum space. Such getters are used in a wide range of fields related to vacuum, and various getter materials have been developed to meet various applications. They are classified into evaporable getters and non-evaporable getters according to the properties of getter materials. Evaporable getter materials include alloys mainly composed of elements such as barium (Ba) and magnesium (Mg). Include alloys mainly composed of elements such as zirconium (Zr) and titanium (Ti).

As described above, the conventional cathode ray tube is Ba
It is equipped with an evaporable getter whose main component is.

[0005] The cathode ray tube needs to maintain a high vacuum inside the tube (in the envelope) in order to stably emit electrons.
However, due to gas release from the surface irradiated with electrons,
When a high vacuum cannot be maintained, the electron emission characteristics deteriorate,
Eventually it will reach the end of its life. Therefore, the gas emitted in the tube at the time of electron emission is adsorbed to the getter, and the pressure in the tube is maintained at a high vacuum for a long time, thereby extending the life of the cathode ray tube.

[0006]

There is a limit to the number of gas molecules (gas molecules) that can be adsorbed by the getter. When the number of gas molecules reaches the limit, the exhaust function is lost. In the case of an evaporable getter, the larger the amount of evaporation of the getter material, the greater the adsorption capacity. Therefore, each type of cathode ray tube is filled with the getter material so as to evaporate an appropriate amount. However, if the amount of evaporation of the getter is too large, the evaporated getter not only forms a getter film on the inner wall of the tube but also floats in the tube. Since electrons collide with the floating getter molecules, there is a problem that the transmission of the electron beam is hindered and the brightness is reduced.

An object of the present invention is to solve the above-mentioned problems by reducing the amount of the evaporable getter, and to extend the life of the CRT.

[0008]

In order to achieve the above-mentioned object, a non-evaporable getter and a small amount of an evaporable getter are mounted on a cathode ray tube, and an initial release gas is adsorbed on the evaporable getter.
The above object is achieved by adsorbing the released gas by a non-evaporable getter until the end of its life.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view showing the structure of a cathode ray tube according to the present embodiment, and FIG. 2 is a graph showing a change in the released gas in the tube.

In FIG. 1, the CRT has a structure in which a panel 1, a funnel, and a neck 3 are integrally joined. A fluorescent film 4 is formed on the inner surface of the panel 1, and a shadow mask 5 is arranged inside the panel 1 so as to face the fluorescent film 4. The shadow mask 5 has a number of holes through which the electron beam 6 passes, and its periphery is fixed to the frame 7.
A non-evaporable getter material (Zr getter 9) made of a Zr-V-Fe alloy is provided in a getter holder 8 made of a stainless steel plate, which is located at an upper end and a lower end inside the shadow mask 5 and is attached to a frame 7. ) Is installed. The Zr getter 9 and the getter holder 8 form a non-evaporable getter device 10, and the Zr getter 9 is attached to the getter holder 8 on the shadow mask 5 side. Further, a magnetic shield 11 is attached to the frame 7, and is supported on the inner surface of the panel 1 by support means 12 provided on the frame 7.

On the inner surface of the funnel 2, a conductive film 13 containing carbon as a main component is formed. An electron gun 14 that emits the electron beam 6 is sealed in the neck 3, and the tip of a getter support 15 that protrudes from the electron gun 14 to the funnel 2 is provided at the tip of an evaporative getter material (Ba getter) containing Ba as a main component. 17) Stainless steel container 16 filled with
Is installed. The filling amount of the Ba getter 17 is small. Specifically, for a cathode ray tube with a lifetime of 10,000 hours,
The stainless steel container 16 is filled with a Ba getter 17 of about 10% of a filling amount necessary for maintaining a high vacuum for 10,000 hours.

At the joint between the funnel 2 and the neck 3,
A deflection coil 18 is mounted from outside.

As described above, the cathode ray tube of the present invention uses both the Ba getter 17 as the evaporable getter material and the Zr getter 9 as the non-evaporable getter material. These getters are activated in the manufacturing process, and first, the Ba getter 17 is heated and evaporated to form a Ba getter film on the inner wall of the tube. Next, the non-evaporable getter device 10 is heated to about 400 to 450 ° C. to activate the Zr getter 9. These getters are heated from outside the cathode ray tube by a high frequency induction heating method. When the Ba getter 17 is activated, the inside of the tube becomes a high vacuum, and the gas released by heating the Zr getter 9 is adsorbed on the Ba getter film, thereby activating the Zr getter 9 while maintaining the high vacuum. Zr
The getter 9 does not heat and evaporate, but has an exhaust function of adsorbing gas only by being activated and left in the tube.

When the adsorption capacity of the surface is reduced, the Zr getter 9 diffuses the molecules adsorbed on the surface into the getter,
It has the property of restoring the surface to allow gas adsorption again. At room temperature, there is an exhaust function, but at room temperature, diffusion into the interior is not so remarkable. It is known that when the temperature is increased, the diffusion into the inside becomes active, the activity of the surface is increased, and the adsorptivity is maintained. However, if the temperature is raised too high, gas molecules taken into the inside are discharged, so care must be taken not to raise the activation temperature to 450 ° C. or more.

The electron beam 6 emitted from the electron gun 14 is applied to the shadow mask 5, and the electron beam 6 passing through the hole of the shadow mask 5 is applied to the fluorescent film 4.
To emit light. The electron beam 6 is controlled by a deflection coil 18 so as to sequentially irradiate the entire surface of the fluorescent film 4, and scans a range indicated by a broken line in FIG. 1 to output an image. At this time, the getter holder 8 of the non-evaporable getter device 10 has the scan frequency period 3
The electron beam 6 is repeatedly irradiated at 0 Hz, and the non-evaporable getter device 10 operates at 80 to 1 with the irradiation energy of the electron beam 6.
Heat to 50 ° C.

FIG. 2 shows the change in the gas emitted when the electron beam 6 is irradiated on the inner wall of the tube, the film, and the like, normalized by the amount of gas emitted per unit time at 10,000 hours. The amount of gas emission decreases rapidly with the passage of time,
It turns out that it is extremely small after 0 hour. Almost 100
After 0 hour, the gas adsorption speed and the amount of adsorbed Ba are large.
There is no need to use the getter 17, and the non-evaporable getter such as the Zr getter 9 can sufficiently maintain a high vacuum with the adsorbing ability.

The Ba getter 17 mainly adsorbs the initially released gas for up to about 1000 hours, and its adsorbing ability decreases with time, and eventually loses its adsorbing ability. On the other hand, Zr
The getter 9 adsorbs gas by 1000 hours,
While the adsorbability of the Ba getter 17 gradually decreases, the exhaust action of the Zr getter 9 gradually becomes dominant. While scanning the electron beam and outputting an image, the Zr getter 9 is heated to 80 to 150 ° C. by the electron beam 6 repeatedly applied to the non-evaporable getter device 10, and the released gas is Zr. It is adsorbed on the surface of the getter 9 and is taken in by diffusion, and the surface is always in an activated state, so that the initial adsorption ability is maintained. By such an exhausting action, the pressure in the tube can be maintained at a high vacuum for a long time, so that the life of the cathode ray tube can be extended. In addition, since the amount of evaporation of the Ba getter 17 is small, the amount of floating getter molecules is extremely small, and there is no adverse effect on the luminance characteristics.

By mounting the non-evaporable getter device 10 having the Zr getter 9 and the evaporable getter device 19 having a small amount of Ba getter 17 on the cathode ray tube, the floating performance of the getter molecules does not adversely affect the luminance performance. The type getter device 10 is heated by irradiating it with the electron beam 6, and the gas in the tube is captured and confined by the Zr getter 9, which has the effect of extending the life of the cathode ray tube.

In this embodiment, Z is used as the non-evaporable getter material.
Although the case of the r-V-Fe alloy has been described, the Zr-A
Even if another non-evaporable getter material such as 1 alloy is used, the same effect as that of the present embodiment can be obtained.

[0020]

According to the present invention, since the electron beam scanning is not hindered, there is an effect that the brightness is not reduced and the life of the CRT is prolonged.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a cathode ray tube showing one embodiment of the present invention.

FIG. 2 is a graph showing a time change of gas emission by an electron beam of a cathode ray tube.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Panel, 2 ... Funnel, 3 ... Neck, 4 ... Fluorescent film, 5 ... Shadow mask, 6 ... Electron beam, 7 ... Frame, 8 ... Getter holder, 9 ... Zr getter, 10 ... Non-evaporable getter device.

Claims (1)

[Claims] 1. A cathode ray tube having a fluorescent film that emits light by an electron beam, wherein the cathode ray tube is equipped with an evaporable getter device and a non-evaporable getter device.