JPH08148081A - Manufacture of cathode-ray tube - Google Patents

Abstract

PURPOSE: To provide a cathode-ray tube having a stable emission characteristic by activating an impregnated cathode in a short time. CONSTITUTION: An impregnated cathode K is activated by selectively applying prescribed voltage to the impregnated cathode K and to the first/second/third electrodes G1, G2, G3 successively adjacent to this impregnated cathode K. Voltage of 120% or more rated value is applied to a heater H, to apply to this second electrode G2 voltage equal to the voltage at actual operation time, to on/off turn by ration of 1:2 to 1:5 the voltage applied to this second electrode G2, further to repeat this on/off turning. By a method, including a condition of applying to the third electrode G3 voltage lower than the voltage applied to this second electrode G2, the impregnated cathode K is activated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a cathode ray tube in which the cathode of an electron gun is an impregnated cathode, and in particular, a cathode ray tube which can stably activate the impregnated cathode in a short time. Regarding the method.

[0002]

2. Description of the Related Art Generally, a cathode ray tube is formed in a structure for displaying an image by deflecting an electron beam emitted from an electron gun by a magnetic field generated by a deflecting device and horizontally and vertically scanning a phosphor screen. There is. The electron gun is
It has a cathode and a plurality of electrodes sequentially arranged in the phosphor screen direction from the cathode, and an oxide cathode is usually used as the cathode. However, recently, impregnated cathodes have been used in some cathode ray tubes. That is, the impregnated cathode is
It is capable of drawing a larger current than an oxide cathode and has excellent life characteristics. Therefore, a large direct-view type cathode ray tube or projection cathode ray tube that requires a large current, or a cathode for high resolution can be obtained. It is used for a display tube or the like in which a large load is applied to the cathode because the electron beam passage hole of the first electrode adjacent to is extremely small.

Generally, in a cathode ray tube, various in-tube members are arranged in the tube in the manufacturing process, the electron gun is further sealed and then exhausted, and the cathode is activated after the latter stage of the exhaust. Regarding the activation of the impregnated cathode, based on the activation of the oxide cathode, first, the cathode is preheated, and then a predetermined voltage is applied to the first electrode while the heater is higher than the rated voltage, and the A tubular cathode aging is performed, and then a predetermined voltage is applied to the second electrode to perform triode crossover aging.

However, activation of this impregnated cathode is
Since the impregnated cathode is easily poisoned by the gas in the tube, it is necessary to process the gas in the tube while gradually applying an electric current to activate it for a long time.In addition, it is released from each electrode of the electron gun in a working state. In order to stabilize the initial cathode against gas, it is necessary to raise the heater above the rating and activate it for a long time under the working anode condition, which requires a long time for activation.

That is, activation of a conventional impregnated cathode is
As compared with the activation of the oxide cathode shown in Table 1, the procedure is performed as shown in Table 2. The time required for activation of the oxide cathode is 46 minutes, whereas the time required is 249 minutes.

[Table 1]

[Table 2]

[0006]

As described above, the impregnated cathode is a large direct-view cathode ray tube or projection cathode ray tube that requires a large current, and the first cathode adjacent to the cathode so that high resolution can be obtained. It is used in a display tube or the like in which a large load is applied to the cathode because the electron beam passage hole of the electrode is extremely small. Conventionally, activation in the manufacturing process of a cathode ray tube having these impregnated cathodes is based on the activation of oxide cathodes, preheating the cathodes, and then heating the heaters above the rated value to the first electrode. A voltage is applied to cause aging of the cathode in the manner of a bipolar tube, and then a predetermined voltage is applied to the second electrode to perform aging of the triode crossover.

However, in the activation of the impregnated cathode, since the impregnated cathode is easily poisoned by the gas in the tube, it is necessary to process the gas in the tube while gradually applying an electric current to carry out the activation for a long time. In order to stabilize the initial cathode against the gas emitted from each electrode of the electron gun in the working state, it is necessary to raise the heater above the rated value and activate it for a long time under the working anode condition. There is a problem that it takes time.

The present invention has been made in view of the above problems, and in a method of manufacturing a cathode ray tube having an impregnated cathode, the impregnated cathode is activated in a short time and has a stable emission characteristic. The purpose is to be able to supply.

[0009]

A cathode ray tube equipped with an impregnated cathode, a heater for heating the impregnated cathode, and an electron gun having a plurality of electrodes arranged in order adjacent to the impregnated cathode. In the method of manufacturing a cathode ray tube in which a predetermined voltage is selectively applied to the impregnated cathode and the first, second, and third electrodes sequentially adjacent to the impregnated cathode to activate the impregnated cathode, a heater is used. 120% of rating
The above voltage is applied, the same voltage as the voltage during actual operation is applied to the second electrode, and the voltage applied to this second electrode is 1: 2
It is turned on / off at a ratio of 1: 5 and this on / off is repeated to activate the impregnated cathode by a method including a condition of applying a voltage lower than the voltage applied to the second electrode to the third electrode. I chose

[0010]

In order to solve the activation problem of the conventional impregnated cathode, it is necessary to extract as much current as possible during activation and to sufficiently discharge gas from each electrode. is there. Moreover, it is necessary to properly adjust the balance between the gas discharge and the activation of the cathode.

In the conventional activation of the cathode, the first electrode is sufficiently outgassed by high-frequency heating during exhaust gas, but the second electrode is not sufficiently outgassed. Outgassing of the electrode was an obstacle to the initial stabilization of the cathode and reduction of the aging time.
Therefore, when a voltage lower than the voltage applied to the second electrode is applied to the third electrode during the aging of the second electrode as described above, a part of the electron beam emitted from the cathode collides with the second electrode. The collision of the electron beam can sufficiently discharge the gas from the second electrode.
However, in this case, if the electron beam is continuously extracted from the cathode, the second electrode is considerably heated, and abnormal emission of gas occurs. Further, barium from the cathode adheres to the second electrode, which makes it easier for abnormal light emission (stray emission) to occur.
By repeatedly turning on / off the voltage applied to the second electrode, it is possible to prevent the abnormal discharge of the gas and the adhesion of barium from the cathode. As a result, the time required for activation can be reduced to half that of the conventional method. Further, it is possible to obtain a cathode ray tube having stable emission characteristics without generation of stray emission.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

After arranging a phosphor screen and other various in-tube members in the cathode ray tube bulb, the electron gun whose cathode is an impregnated cathode is sealed in the neck of the bulb. A typical structure of this electron gun is shown in FIGS.
Shown in

The electron gun shown in FIG. 2A is a unipotential type electron gun used in a general cathode ray tube.
An impregnated cathode K, a heater H for heating the impregnated cathode K, and first to fifth electrodes G1 to G5 arranged in the direction of the phosphor screen in the order of being adjacent to the impregnated cathode K. An electron beam generator GEA for generating an electron beam is formed by the first and second electrodes G1 and G2.
Further, the anode voltage Eb is applied to the third and fifth electrodes G3 to G5, and the focusing voltage Ec4 is applied to the fourth electrode G4, and the electron beam from the electron beam generator GEA is converted into a phosphor by the third to fifth electrodes G3 to G5. The main lens portion MLA that focuses on the screen is formed.

The electron gun shown in FIG. 2 (b) is a bipotential type electron gun which is also used for a general cathode ray tube, and includes an impregnated cathode K, a heater H for heating the impregnated cathode K, and an impregnated cathode. The first to fourth electrodes G1 to G4 are arranged adjacent to the cathode K in order in the phosphor screen direction, and the impregnated cathode K and the first and second electrodes G1 and G2 form an electron beam generator GEA. . Further, by applying the focusing voltage Ec3 to the third G3 and the anode voltage Eb to the fourth electrode G4, the main lens portion MLA is formed by these third and fourth electrodes G3 and G4.

The electron gun shown in FIG. 2 (c) is an electromagnetic focusing electron gun used in a projection cathode ray tube, and includes an impregnated cathode K, a heater H for heating the impregnated cathode K, and an impregnated cathode K. Of the first to third electrodes G1 to G3 which are sequentially arranged adjacent to each other in the direction of the phosphor screen, and the impregnated cathode K and the first and second electrodes G1 and G2 form an electron beam generator GEA. Further, the anode voltage Eb is applied to the third electrode G3, and the main lens portion MLA is formed by the third electrode G3 and the focusing coil mounted on the outside of the neck.

In each electron gun, the impregnated cathode K and the first and second electrodes G1 and G2 are used to generate an electron beam generator GEA.
Is formed, and the main lens portion MLA is formed by one or a plurality of electrodes arranged closer to the phosphor screen than the second electrode G2.

In such a cathode ray tube valve with a sealed electron gun, the entire cathode ray tube valve is then heated by the exhaust device to exhaust gas while sufficiently exhausting gas from the valve and the tube inner member. Then, after the exhaustion, activation of the impregnated cathode, getter flash, withstand voltage treatment, etc. are performed.

Activation of the impregnated cathode in the cathode ray tube manufacturing method of this example is carried out under the conditions shown in Table 3.

[Table 3]

That is, first, after activation under the same conditions as the conventional activation shown in Table 2, the heater is replaced by the heater instead of the conventional raster aging in which the third electrode and the second electrode are made to have the same potential. Applying a voltage of 120% or more of the rating, 550V to the third electrode, 600 to the second electrode
Aging is performed by a method of applying V and a voltage lower than that of the second electrode to the third electrode and turning on / off the voltage applied to the second electrode.

When the impregnated cathode is activated under such conditions, the aging effect more than the activation of the conventional impregnated cathode can be obtained in a short time. In addition, the gas is sufficiently discharged from the second electrode due to the collision of the electron beam, and
By repeatedly turning the voltage applied to the electrodes on and off, overheating of the second electrode due to the collision of the electron beam is prevented, and abnormal light emission does not occur due to the adhesion of barium from the impregnated cathode to the second electrode. Therefore, a highly reliable cathode ray tube having stable emission characteristics can be manufactured.

In Table 4, as an evaluation method of the cathode ray tube aged under the conditions of Table 3, the anode voltage was 30 kV, the first electrode was grounded, and the second cut-off voltage was 70 V.
Table 4 and FIG. 1 show changes in the cathode current for the first 30 seconds when the voltage of the electrodes was adjusted and the cathode was set to 0 V to take out the maximum current.

[Table 4]

In FIG. 1, A is a cathode current when a cathode ray tube whose cathode is an oxide cathode is activated under the conditions shown in Table 1, and B is a cathode ray tube whose cathode is an impregnated cathode. Cathode current before raster aging when activated under the conventional conditions shown in Table 1, C is a comparative example of the cathode current when aged under the conventional conditions shown in Table 2 (180 minutes of raster aging). Yes, D is the cathode current when the cathode ray tube whose cathode is the impregnated cathode is activated under the conditions shown in Table 3.

As shown in Table 4 and FIG. 1, when activated under the conditions of Table 3, an aging effect more than the activation of the conventional impregnated cathode is obtained, and moreover, the time required for activation is conventionally increased. The activation time of the impregnated-type cathode was 249 minutes, which was significantly reduced to 114 minutes.

In the above embodiment, the duty for the impregnated cathode by turning on / off the voltage applied to the second electrode is set to 1: 2, but this may be changed depending on the cathode current and the shape of the second electrode. Need, generally 1: 2-
Good results are obtained in the range of 1: 5.

[0026]

INDUSTRIAL APPLICABILITY After the evacuation process of the cathode ray tube equipped with the impregnated cathode, the heater for heating the impregnated cathode and the electron gun having a plurality of electrodes arranged in order adjacent to the impregnated cathode, the impregnated cathode is used. In a method of manufacturing a cathode ray tube in which a predetermined voltage is selectively applied to a cathode and first, second, and third electrodes that are sequentially adjacent to the impregnated cathode to activate the impregnated cathode, a heater with a rated voltage of 120% is used. The above voltage is applied, the same voltage as the voltage at the time of actual operation is applied to the second electrode, the voltage applied to this second electrode is turned on / off at a ratio of 1: 2 to 1: 5, and this on / off When the impregnated cathode is activated by a method including a condition of applying a voltage lower than the voltage applied to the second electrode to the third electrode, part of the electron beam emitted from the cathode is applied to the second electrode. Can be collided, The degassing of the second electrode can be sufficiently performed by. Further, by repeatedly turning on / off the voltage applied to the second electrode, it is possible to prevent abnormal emission of gas and adhesion of barium from the impregnated cathode. As a result, the time required for activation is 1/2
Can be shortened to In addition, a cathode ray tube having stable emission characteristics that does not generate stray emission can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an effect of activating an impregnated-type cathode according to an embodiment of the present invention.

2 (a) to 2 (c) are diagrams each showing a configuration of an electron gun in which a cathode is an impregnated cathode.

[Explanation of symbols]

 G1 ... 1st electrode G2 ... 2nd electrode G3 ... 3rd electrode G4 ... 4th electrode G5 ... 5th electrode GEA ... Electron beam generation part H ... Heater K ... Cathode MLA ... Main lens part

Claims (1)

[Claims] 1. A cathode ray tube equipped with an impregnated cathode, a heater for heating the impregnated cathode, and an electron gun having a plurality of electrodes sequentially arranged adjacent to the impregnated cathode, after the subsequent stage of the exhaust step, In a method of manufacturing a cathode ray tube in which a predetermined voltage is applied to an impregnated cathode and first, second, and third electrodes sequentially adjacent to the impregnated cathode to activate the impregnated cathode, the heater is rated at 120%. % Or more, the same voltage as the voltage at the time of actual operation is applied to the second electrode, and the voltage applied to the second electrode is turned on / off at a ratio of 1: 2 to 1: 5 and The method for producing a cathode ray tube is characterized in that the impregnated cathode is activated by a method including a condition in which a voltage lower than a voltage applied to the second electrode is applied to the third electrode repeatedly.