JPH08167379A - Manufacture of cathode-ray tube - Google Patents

Abstract

PURPOSE: To provide a cathode-ray tube of high in-tube vacuum and excellent quality by ionizing the inert gas in the tube by means of the thermoion emitted from a cathode, and irreversibly adsorbing the ionized gas by a focusing elec trode. CONSTITUTION: The residual gas in a tube is ionized to the positive electrode by the thermoion emitted from a cathode 2, and the ionized gas is adsorbed by a focusing lens 5 for generating the main lens kept at the negative potential. The inert gas such as Ar which is the main composition of the in-tube residual gas is reduced in volume during the manufacturing process of a cathode ray tube. Because a final acceleration electrode 6 during this treatment is kept at the voltage higher than that of the focusing electrode 5, the ionized inert gas is adsorbed mainly by the focusing electrode 5, and little adsorbed by the final acceleration electrode, a shadow mask, a magnetic shield and a fluorescent screen, etc. Thus, the final acceleration electrode 6, etc., is kept at the high positive voltage in the normal operation of the tube, and no gas is emitted even when the electron beam hits.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a cathode ray tube in which an inert gas remaining in the tube is adsorbed on a specific electrode to increase the vacuum degree in the tube.

[0002]

2. Description of the Related Art Generally, in manufacturing a cathode ray tube such as a color picture tube, a getter flash step and an aging step are set subsequent to each step of exhausting and sealing the tube. In the pipe exhaust step, not only the gas inside the pipe is discharged, but also the electrode inside the pipe is heated by high frequency to discharge the gas sucked in the electrode material. In the getter flash process, a Ba getter previously provided in the tube is heated by high frequency to form a Ba getter film on the inner surface of the tube by vapor deposition. Since this Ba getter film chemically adsorbs the residual gas in the tube for a long period of time, it is possible to maintain a high degree of vacuum in the tube during the aging process and throughout the life period.

The electron gun of the color picture tube shown in FIG. 3 is for producing a cathode 2 having a heater 1 built therein, a control electrode 3 serving as a first grid, an accelerating electrode 4 serving as a second grid, and a main lens serving as a third grid. It is composed of a focusing electrode 5 and a final accelerating electrode 6 which is a fourth grid. The tongue-shaped conductive piece 7 extending from the final accelerating electrode 6 is in contact with the conductive film 8, and the conductive film 8 is electrically connected to an anode button terminal, a shadow mask, a magnetic shield, a phosphor screen surface and the like (not shown). There is.

In the aging process, a heating voltage of 6.0 V is applied to the heater 1, the control electrode 3 is grounded, and the cathode 2 is supplied with 105 to 120 as in the normal tube operation.
A positive electric potential of V, and 400 to 700 V to the acceleration electrode 4.
The positive potential of is applied. The thermoelectrons 9 emitted from the cathode 2 in the front triode part are focused to form an electron beam 1
It becomes 0. Then, the electron beam 10 that has been accelerated and focused by the focusing electrode 5 held at a positive potential of 6 to 7 KV and the final acceleration electrode 6 held at a positive potential of about 25 KV,
It impinges on the phosphor screen surface through a deflection magnetic field and a shadow mask (not shown).

Although the degree of vacuum in the tube of the color picture tube after the aging process is lowered, the Ba getter film adsorbs the residual gas in the tube for a long period of time, so that the inside of the tube is maintained in a vacuum state. However, the residual gas in the tube adsorbed by the Ba getter film is limited to the active gas, and the inert gas such as Ar is not adsorbed. The Ar atoms 11 remaining in the tube are ionized by colliding with the thermoelectrons 9 to become Ar ions 11a. Some of the Ar ions 11a collide with the control electrode 3 at the ground potential and are adsorbed, but the adsorption amount is very small because the pore size of the acceleration electrode 4 is small. Ar ion 11a
Most of is neutralized with the thermoelectrons 9 and returns to Ar gas again, collides with the thermoelectrons 9 again and returns to Ar ions,
The so-called ion process is repeated.

[0006]

As described above, among the gases remaining in the tube, the inert gas such as Ar is not adsorbed by the Ba getter film and is hardly adsorbed by the electrode, so that this is the vacuum in the tube. It was a factor that reduced the degree. In particular, since Ar ions have a large mass number, they are likely to damage the cathode and phosphor screen surfaces by ion bombardment.

Referring to FIG. 4, it can be seen that the gas pressure (total pressure) in the pipe after 10,000 hours of life is reduced to about 1/10 of the gas pressure in the pipe immediately after the aging process (immediately after the pipe is manufactured). . This is because the residual gas components H ₂ , CO,
This is because an active gas such as N ₂ or CH ₄ is chemically adsorbed on the Ba getter film. On the other hand, it can be seen that the partial pressure of an inert gas such as Ar or He decreases with time due to ion implantation and electric adsorption, but shows a high value immediately after the aging step.

Therefore, an object of the present invention is to provide a method of manufacturing a cathode ray tube capable of minimizing the inert gas component in the residual gas in the tube during the manufacturing process of the cathode ray tube.

[0009]

According to the present invention, in order to achieve the above-mentioned object, a control electrode and an accelerating electrode adjacent thereto are set to a positive potential, a focusing electrode for generating a main lens is set to a negative potential, and The final accelerating electrode is held at a potential higher than that of the focusing electrode, and the residual gas in the tube is positively ionized by thermoelectrons emitted from the cathode, and the ionized gas is adsorbed to the focusing electrode. A method of manufacturing a cathode ray tube is provided.

Further, the control electrode, the acceleration electrode and the auxiliary electrode system adjacent thereto are set to a positive potential, the focusing electrode for generating the main lens is set to a negative potential, and the final acceleration electrode is set to a potential higher than the potential of the focusing electrode. Provided is a method for manufacturing a cathode ray tube, characterized in that the residual gas in the tube is positively ionized by thermoelectrons held respectively and emitted from the cathode, and the ionized gas is adsorbed to the focusing electrode.

[0011]

In the present invention, the residual gas in the tube is positively ionized by thermionic electrons emitted from the cathode, and the ionized gas is electrically adsorbed by the focusing electrode for generating the main lens held at the negative potential. An inert gas such as Ar, which is the main component of the residual gas, can be reduced during the manufacturing process of the cathode ray tube. Further, since the final accelerating electrode during this treatment period is held at a potential higher than that of the focusing electrode, the ionized inert gas is mainly adsorbed on the focusing electrode, and the final accelerating electrode, the shadow mask, the magnetic shield and the fluorescence. It is hardly adsorbed on the body screen surface. Therefore, even if the final accelerating electrode, shadow mask, magnetic shield, and phosphor screen surface are held at a positive high potential during the normal operation of the tube and are hit by an electron beam, almost no inert gas is emitted. Absent.

When the adsorbed gas ions are neutralized by the thermoelectrons reaching the surface of the focusing electrode, the adsorbed gas ions return to the inert gas atoms again. However, since a thin oxide layer exists on the surface of the metal electrode, the migration of thermoelectrons is blocked by this oxide layer. Therefore, most of the gas ions are not neutralized and remain electrically adsorbed on the surface of the oxide layer. Since the focusing electrode and the final accelerating electrode generate the main lens electric field, as long as the potential distribution of both electrodes is set to a predetermined value and a strong main lens electric field is generated between both electrodes, the accelerated electron beam Rarely strikes the surface of the focusing electrode to neutralize the adsorbed gas ions.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In the embodiment shown in FIG. 1, a heating voltage of 6.5 V, which is slightly higher than that during normal operation, is applied to the heater 1, the cathode 2 is grounded, and the control electrode 3 and the accelerating electrode 4 are set to 400 V.
A positive potential of 1000 V is applied to cause the cathode 2 to emit thermions 9. A potential of -9 KV is applied to the focusing electrode 5,
The electrodes after the final acceleration electrode 6 (including the shadow mask, the magnetic shield, and the phosphor screen surface) are kept at the ground potential. In this case, the Ar atom 11 which is the inert gas remaining in the tube collides with the thermoelectron 9 and is ionized to become the Ar ion 11b having a positive polarity. The Ar ions 11b are fed to the focusing electrode 5 held at a negative potential more than that by the fan.
It is driven in and absorbed by the Del Waals force and Coulomb force. Since a thin oxide layer exists on the surface of the focusing electrode 5,
The movement of electrons is blocked, and most of the gas ions are not neutralized and remain electrically adsorbed on the surface of the focusing electrode 5.

Since the electrodes after the final accelerating electrode 6 are held at the ground potential, the amount of Ar ions 11b implanted in these electrodes is small. Then, the Ar ions 11b that have been implanted into the electrodes after the final accelerating electrode 6 are gasified and released into the tube when the electron beam raster-sweeps during normal operation of the tube.

The characteristic curve a shown in FIG. 2 shows that the control electrode 3, the acceleration electrode 4 and the focusing electrode 5 are held at a positive potential of 440 V, the electrodes after the final acceleration electrode 6 are held at the ground potential, and the phosphor screen surface is shown. An example of accelerating and implanting Ar ions to the side is shown. When the tube is operated under normal operating conditions (raster sweep) after such treatment, most of the adsorbed Ar ions are returned to Ar gas and released into the space inside the tube. In this example, the electrodes after the final accelerating electrode 6 were held at the ground potential, but the same results as above can be obtained even if they are held at the negative potential.

The characteristic curve b shown in FIG. 2 shows that the control electrode 3 and the acceleration electrode 4 are at a positive potential of 440 V, the focusing electrode 5 is at the ground potential, and the electrodes after the final acceleration electrode 6 are at 440 V.
In this example, the positive potential of V is maintained and Ar ions are mainly implanted into the focusing electrode 5. In this case, the amount of Ar ions adsorbed is larger than that of the characteristic curve a, and the amount of Ar gas released in the raster sweep is relatively small.

The characteristic curve c shows that the control electrode 3 and the accelerating electrode 4 are kept at a positive potential of 440 V, the focusing electrode 5 and the electrodes after the final accelerating electrode 6 are kept at the ground potential, respectively, and the focusing electrode 4 moves to the phosphor screen surface. In this example, all the electrodes up to this point are used as adsorption surfaces for Ar ions. In this case, since the adsorption area of Ar ions is increased, the adsorption amount is increased, but the amount of Ar gas released by the raster sweep is also increased.

The characteristic curve d is according to the present invention. The control electrode 3 and the accelerating electrode 4 are set to a positive potential of 440 V, the focusing electrode 5 is set to a negative high potential of -9 KV, and the final accelerating electrode 6 is formed.
This is a case where the following electrodes are held at the ground potential.
In this case, Ar ions are not accelerated toward the phosphor screen surface side, and most of them are adsorbed to the focusing electrode 5. Also, the amount of Ar gas released by the raster sweep is very small. In this example, the electrodes after the final accelerating electrode 6 are held at the ground potential, but even if they are held at a negative potential (0 to -3 KV) higher by several KV or more than the potential of the focusing electrode 5, almost the same gas adsorption is achieved. The action can be obtained.

In the above-mentioned cases, the potential applied to the control electrode 3 and the acceleration electrode 4 is set to 440V, but it is preferably selected from the range of 400V to 1KV. Further, the potential applied to the focusing electrode 5, the potential applied to the electrodes after the final accelerating electrode 6, and the heating voltage applied to the heater 1 can also be appropriately selected according to the tube type of the cathode ray tube to be manufactured. it can. Further, although the cathode ray tube in the above-described embodiment is of the bipotential type, the acceleration electrode 4 and the main lens are generated like a cathode ray tube equipped with a multi-stage focusing electron gun (MPF (multi-prefocus)). The present invention can also be applied to a cathode ray tube in which one or more auxiliary electrodes (auxiliary electrode system) are arranged between the focusing electrode 5 and the focusing electrode 5. In that case, a positive potential similar to that of the accelerating electrode 4 is applied to all the auxiliary electrode systems, a potential that is negative with respect to the potential is applied to the main-lens generating focusing electrode, and the final accelerating electrode is grounded or focused. Give a higher potential than.

By performing such a treatment after the aging step, the Ar gas remaining in the tube can be greatly reduced and the vacuum degree in the tube can be increased. When the focusing electrode 5 is applied with a positive potential of 6 to 7 KV and the electrodes after the final acceleration electrode 6 are applied with a positive high potential of about 25 KV during normal operation of the tube, a strong main voltage is applied between the electrodes 5 and 6. Since the lens electric field is generated, the accelerated electron beam passes through the main lens electric field without hitting the focusing electrode 5.
Therefore, the inert gas ions once adsorbed on the focusing electrode 5 hardly neutralize the thermoelectrons and return to the gas atoms.

The potential applied to the electrodes after the final acceleration electrode 6 may be a positive potential of 500 V to 1 KV only for the purpose of preventing adsorption of gas ions to these electrodes. Fixing this potential to the ground potential not only simplifies the equipment but also improves the manufacturing efficiency. The ion process described above works for all gas compositions of the residual gas in the tube, but since the active gas is mainly adsorbed by the getter film, the gas that is irreversibly adsorbed on the focusing electrode is mainly the inert gas. Is.

With the increase in size, definition and brightness of cathode ray tubes, the number of cases in which impregnated cathodes are used as cathodes is increasing. Among the gas in the tube, if ionized inert gas scatters the Ba monoatomic layer on the surface of the impregnated cathode by ion bombardment, there is a risk of causing emission slump. Therefore, when the cathode ray tube having the impregnated cathode is manufactured by the method of the present invention, the generation of emission slump can be suppressed.

[0024]

As described above, according to the present invention, since the inert gas in the tube is ionized by the thermoelectrons emitted from the cathode and the ionized gas is irreversibly adsorbed to the focusing electrode, the vacuum degree in the tube is reduced. It is possible to obtain a high quality cathode ray tube.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship of electric potential with respect to each electrode of a cathode ray tube in one embodiment of the present invention.

FIG. 2 shows Ar gas pressure of one embodiment of the present invention as Ar gas pressure of a comparative example.
Characteristic diagram showing with gas pressure

FIG. 3 is a diagram showing a relationship of potentials to respective electrodes of a cathode ray tube during normal operation.

FIG. 4 is a view showing a pressure change with time of residual gas in a cathode ray tube.

[Explanation of symbols]

 2 cathode 3 control electrode 4 acceleration electrode 5 focusing electrode for main lens generation 6 final acceleration electrode

Claims (4)

[Claims] 1. A control electrode and an accelerating electrode adjacent to the control electrode are set to a positive potential, and a focusing electrode for generating a main lens is set to a negative potential.
Then, the final accelerating electrode is held at a potential higher than that of the focusing electrode, and the residual gas in the tube is positively ionized by thermoelectrons emitted from the cathode, and the ionized gas is adsorbed to the focusing electrode. A method for manufacturing a characteristic cathode ray tube. 2. The control electrode, the accelerating electrode and the auxiliary electrode system adjacent thereto are set to a positive potential, the focusing electrode for generating the main lens is set to a negative potential, and the final accelerating electrode is set to a potential higher than the potential of the focusing electrode. A method for manufacturing a cathode ray tube, characterized in that the residual gas in the tube is positively ionized by thermions emitted from the cathode and held, and the ionized gas is adsorbed to the focusing electrode. 3. The method of manufacturing a cathode ray tube according to claim 1, wherein the cathode and the final accelerating electrode are held at the same potential or the ground potential. 4. The method of manufacturing a cathode ray tube according to claim 1, wherein the cathode is an impregnated cathode.