JPH06162949A - Cathode body structure for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To provide a cathode body ensuring white balance over a long term and stable color tone by whitening the gradation of the blackened film of a heater inserted in an intermediate cathode among three cathodes to such an extent as larger than the case of heaters at both sides. CONSTITUTION:Three cathodes are laid and fixed along a straight line, while being supported on respective cathodes supports. Regarding heaters 5a, 5b and 5c inserted in respective cathode sleeves 1a, 1b and 1c, the gradation of the blackened film of the heater 5c is whitened for reducing heat radiation therefrom. As a result, all of the three cathodes for blue, green and red can stably emit electrons over a long term, and a color cathode-ray tube of high quality can be provided, ensuring freedom from the change of color tone called 'collapse of while color balance'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode assembly for a color picture tube, and more particularly to a cathode assembly for an in-line type color picture tube.

[0002]

2. Description of the Related Art Conventionally, in the cathode assembly of this type of in-line type color picture tube, three cathodes of blue, green and red are supported by respective cathode supports and arranged and fixed in a straight line. The center cathode receives heat conduction and heat radiation from the cathodes located on both sides, and the temperature of the cathode base metal is generally higher than the temperature of the base metal of the cathodes located on both sides, resulting in deterioration of electron emission characteristics. There was a problem that a change in color tone called "white balance collapse" occurred quickly during long-term use.

FIG. 3 is a sectional view showing an example of the structure of a conventional cathode assembly.

Each of the cathodes for blue, green and red contains a reducing agent on the upper part of the cathode sleeves 11a, 11b and 11c as shown in the figure, and the base metal 12 shaped like a cap is formed.
a, 12b, 12c are welded, and the alkaline earth metal oxides 13a, 13b, 13c are coated thereon.
Inside the cathode sleeves 11a, 11b, 11c, heaters 15 are formed with blackened films 14a, 14b, 14c of the same gradation.
a, 15b, 15c are inserted, heater auxiliary supports 16a, 16b, 16c, heater supports 17a, 17
b and 17c are supported and fixed, an electric current is supplied through them, and the base metal 12a, 12b, 12c is 700
Heat to ~ 800 ° C.

At this operating temperature, the base metals 12a, 12b,
Reducing agents such as Mg and Si contained in 12c are diffused on the surface and coated with the alkaline earth metal oxides 13a and 13b.
Electron emission is carried out for a long period of time by the reaction with 13c (JP-A-1-220393).

[0006]

As described above, in the cathode structure of the conventional color picture tube, the three cathodes for blue, green and red contain the reducing agent on the upper portions of the cathode sleeves 11a, 11b and 11c. , Base metal 12a formed in a cap shape,
12b and 12c are welded together to form the cathode sleeves 11a and 11
b and 11c, the blackened films 14a and 14 having the same gradation
Heaters 15a, 15b, 15c having b, 14c are inserted and arranged on a straight line.

For this reason, in the center cathode of the three cathodes, the temperature of the base metal 12b of the cathode is 1 due to the heat conduction and heat radiation of the cathodes located on both sides.
The temperature is higher than the temperatures of 2a and 12c by about 10 ° C., the diffusion rate of the reducing agent such as Mg and Si contained in the base metal 12b is increased, and the consumption is increased. There was a problem that it started to deteriorate at an early stage and a change in color tone called white balance collapse occurred during long-term use.

It is an object of the present invention to provide a cathode assembly of a color picture tube which has a stable white color balance for a long period of time.

[0009]

A cathode assembly for a color picture tube according to the present invention comprises a base metal which is shaped like a cap and which contains a reducing agent in the upper part of the cathode sleeve and is fixed on the base metal. The cathode assembly of the color picture tube in which three cathodes for blue, green, and red, which are covered with an object and in which a heater is inserted inside the cathode sleeve, are arranged and fixed in a straight line.
Among the individual cathodes, the gradation of the heater blackening film inserted in the cathode sleeve of the cathode located in the center is made whiter than the gradation of the heaters located on both sides, and the heat radiation from the heater is reduced. .

Further, of the three cathodes, the gradation of the blackening treatment of the cathode sleeve located at the center is made whiter than the gradation of the cathode sleeves located on both sides, or only the cathode sleeves located on both sides are blackened. It has been blackened.

[0011]

According to the above construction, the temperature of the base metal of the cathode located at the center is lowered, and stable electron emission characteristics can be obtained for all three cathodes for blue, green and red over a long period of time.
It is possible to obtain a reliable and high-quality color picture tube in which a change in color tone called white balance loss does not occur.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a cathode assembly of a color picture tube showing an embodiment of the present invention.

In this type of in-line type cathode ray tube cathode structure, three cathodes for blue, green and red are supported by respective cathode supports and arranged and fixed in a straight line.

Referring to the drawings, each cathode has a base metal 2a, 2b, 2c which is shaped like a cap and includes a reducing agent on the top of the cathode sleeve 1a, 1b, 1c.
Are welded on top of which the alkaline earth metal oxides 3a, 3
b and 3c are covered. Each cathode sleeve 1
In the insides of a, 1b, and 1c, the gradation of the blackening film 40b of the heater 5b located in the center, the heaters 5a, 5 located on both sides
heaters 5a, 5b, 5c which are whiter than the blackened films 4a, 4b, 4c of b, 5c are inserted, and heater auxiliary supports 6a, 6b, 6c, heater supports 7a, 7b, 7c,
Supported and fixed by the heater connecting bodies 8a, 8b, 8c,
An electric current is supplied through these, and the base metal 2a, 2b,
2c is heated so that it may become 700-800 degreeC.

At this operating temperature, the base metal 2a, 2b, 2
The alkaline earth metal oxides 3a, 3b, 3 coated with reducing agents such as Mg and Si contained in c are diffused on the surface.
The reaction of c causes electron emission for a long period.

At this time, the cathode sleeves 1a, 1b, and
Among the heaters 5a, 5b, 5c inserted in 1c, the gradation of the blackening film 40b of the heater 5b is made white, and the heat radiation from the heater 5b is reduced, so that three heaters for blue, green and red are obtained. Stable electron emission is obtained for a long time with both the cathode and
It is possible to obtain a high-quality color picture tube without a change in color tone called white balance loss.

In the above embodiment, the gradation of the heater located in the center is white, but it can be realized by making the gradation of the heaters on both sides black compared with the heater located in the center.

[0019]

[Embodiment 2] FIG. 2 is a sectional view of a cathode assembly of a color picture tube showing another embodiment of the present invention.

In the figure, the same parts as those in FIG. 1 of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The difference from the first embodiment lies in the blackened cathode sleeves 10a, 10b and 10c, and the gradation of the blackening treatment of the cathode sleeve 10b at the center of the cathode is located on both sides of the cathode sleeve. As compared with the gradations of the sleeves 10a and 10c, it is characterized in that it is white. By lowering the temperature of the base metal 2b of the central cathode as in the first embodiment,
This has the effect of making the temperatures of the three base metals 2a, 2b, 2c uniform.

In this embodiment, three heaters 5a,
Although no gradation is provided on the blackened films 4a, 4b and 4c of 5b and 5c, the blackened film 4b of the central heater 5b may be whitened as described in FIG.

Further, as another specific example, the cathode sleeve 10b does not necessarily need to be blackened, and therefore only the cathode sleeves 10a and 10c on both sides of the cathode can be blackened.

By combining the configurations of the first and second embodiments, the gradation of the blackening film of the heater located in the center of the cathode is the gradation of the blackening film of the heaters located on both sides. Similar effects can be obtained by making the cathode sleeve whiter than that of the above, and additionally by making only the cathode sleeve located at the center whiter than the cathode sleeves on both sides.

[0025]

As described above, according to the present invention,
In the cathode assembly of a color picture tube in which three cathodes for green and red are arranged and fixed in a straight line, of the three cathodes, a blackened film of the heater inserted in the cathode sleeve located in the center or the cathode By making the gradation of the sleeve whiter than the gradation of the heaters or cathode sleeves located on both sides, stable electron emission characteristics can be obtained for a long time for all three cathodes for blue, green, and red. It is possible to obtain a reliable and high-quality color picture tube in which a change in color tone called white balance loss does not occur.

[Brief description of drawings]

FIG. 1 is a sectional view of a cathode assembly of a color picture tube showing an embodiment of the present invention.

FIG. 2 is a sectional view of a cathode assembly of a color picture tube showing another embodiment of the present invention.

FIG. 3 is a sectional view showing an example of a cathode assembly of a conventional color picture tube.

[Explanation of symbols]

 1a, 1b, 1c Cathode sleeve 2a, 2b, 2c Base metal 3a, 3b, 3c Alkaline earth metal oxide 4a, 4b, 4c, 40b Blackening film 5a, 5b, 5c Heater 6a, 6b, 6c Heater auxiliary support 7a, 7b, 7c Heater support 8a, 8b, 8c Heater connecting body 10a, 10b, 10c Blackened cathode sleeve

Claims (5)

[Claims] 1. A base metal, which contains a reducing agent and is formed into a cap shape, is fixedly provided on an upper portion of the cathode sleeve, an alkaline earth metal oxide is coated on the base metal, and a heat resistant metal resistance wire is provided inside the cathode sleeve. As a coil, the surface of which is covered with an insulator, and the surface of which is coated with a heater with a blackening film formed to increase the efficiency of heat radiation is inserted into three cathodes for blue, green, and red. In the cathode assembly of the color picture tube fixedly aligned in a straight line, the gradation of the blackening film of the heater inserted in the central cathode of the three cathodes is the blackening film of the heaters located on both sides. The cathode assembly of the color picture tube is characterized in that it is whiter than the gradation of. 2. A blue metal having a base metal formed in a cap shape containing a reducing agent, fixed on the cathode sleeve, coated with an alkaline earth metal oxide, and having a heater inserted inside the cathode sleeve. In the cathode structure of a color picture tube in which three cathodes for green and red are linearly fixed, the gradation of the blackening treatment of the cathode sleeve of the cathode located at the center among the three cathodes is set on both sides. The cathode assembly of the color picture tube, which is whiter than the gradation of the cathode sleeve located at. 3. The cathode assembly of a color picture tube according to claim 2, wherein only the cathode sleeves located on both sides of the cathode are blackened. 4. The gradation of the blackening treatment of the cathode sleeve located in the center is compared with the gradation of the cathode sleeves located on both sides.
The cathode assembly of the color picture tube according to claim 1, which is whitened. 5. The cathode assembly of a color picture tube according to claim 1, wherein only the cathode sleeves located on both sides of the cathode are blackened.