JP2699840B2 - Cathode structure of color cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode structure of an in-line type color cathode ray tube in which red, green, and blue cathodes are linearly arranged and arranged. The present invention relates to a cathode structure in which the temperatures of three cathodes are made uniform.

[0002]

2. Description of the Related Art As shown in FIG. 2A, a cathode structure (A) of an in-line type color cathode ray tube has red, green, and blue cathodes (Kr) (Kg) (Kb ) And a first grid electrode (Ga). The cathodes (Kr), (Kg) and (Kb) are coated with an emitter material for emitting an electron beam on the upper end surfaces (1a), (2a) and (3a) of three cap-shaped cathode sleeves (1), (2) and (3). Each of the sleeves (1) (1) and (2) is formed such that the emitter material is linearly arranged as shown in FIGS. 2 (a) and 2 (b). 2) (3) is aligned, and three cathodes (Kr) (Kg) (Kb) are linearly arranged. The first grid electrode (Ga) is a metal plate (for example, stainless steel or permalloy plate) formed into a predetermined shape.
Three electron beam transmission holes (Er) (Eg) (Eb) corresponding to the cathodes (Kr) (Kg) (Kb) are formed on the cathode (Kr) (Kg) (Kb). Predetermined interval (Lg = about 70 ~
100 μm) and fixedly arranged.

In the above configuration, when the red, green, and blue cathodes (Kr), (Kg), and (Kb) are heated, an electron beam is emitted from the emitter material, and further, the fluorescent screen (Ga) passes through the first grid electrode (Ga). (Not shown).

[0004]

The problem to be solved is a cathode structure (A) of an in-line type color cathode ray tube.
Are three cathodes of the same dimensions, red, green and blue (K
r) (Kg) (Kb)
When heating the heater, the cathodes (Kr) and (Kb) on both sides thermally shield the cathode (Kg) located at the center to lower the heat dissipation, and also reduce the heat dissipation from the cathodes (Kr) and (Kb) on both sides. Dissipated heat is transmitted, and heat is accumulated in the centrally located cathode (Kg) and easily rises to a high temperature. Three cathodes (Kr) (K
g) The point at which the temperature of (Kb) becomes non-uniform. Then, as shown in FIG. 3 (a), in the temporal characteristic of luminance (emission), the gradient at the time of rising at the center cathode (Kg) and the cathodes (Kr) (Kb) at both sides and the stable state thereafter. Each operating characteristic is different, and
As shown in FIG. 3B, the luminance characteristic with respect to the first grid voltage (Vga) is also the same for the central cathode (Kg).
And the cathodes (Kr) and (Kb) on both sides have different gradients, resulting in different cutoff voltages (Vcg) and (Vcbr). As a result, the white balance is broken and the color tone is disturbed.
Also, when the temperatures of the three cathodes (Kr) (Kg) (Kb) become uneven, the electron emission characteristic of the cathode (Kg) located at the center becomes earlier than the cathodes (Kr) (Kb) on both sides. It starts to deteriorate, and the white balance is similarly distorted and the color tone is disturbed during long-term use.

[0005]

According to the present invention, an emitter material for emitting an electron beam is formed on each of the upper end surfaces of three cap-shaped cathode sleeves, and a heater is inserted into each of the sleeves. Red, arranged and arranged in a shape
Green and blue cathodes, and three electron beam transmitting holes corresponding to the cathodes are formed in a metal plate formed in a predetermined shape, and are fixedly arranged at predetermined intervals with respect to the cathodes. And a first grid electrode having a heat absorption region formed at least in a surface layer portion near a central electron beam transmission hole.

[0006]

According to the above technical means, when at least the surface layer near the electron beam transmitting hole located in the center of the first grid electrode is heat-resistant blackened to form a heat absorbing region, the center of the electron beam is emitted when the electron beam is emitted. When the temperature of the cathode is particularly high, the distance between the first grid electrode and the cathode is very small,
The heat of the central cathode is absorbed by the radiation from the back surface of the first grid electrode into the heat absorbing region, and the absorbed heat is radiated from the surface of the grid electrode, so that the heat dissipation of the central cathode is improved and its temperature is reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cathode structure of a color cathode ray tube according to the present invention will be described below with reference to FIGS. The same parts as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. The difference is that the three electron beam transmission holes (Er) (Eg) (Eb) of the first grid electrode (Gb)
Among them, the heat absorption region (4) is formed at least in the surface layer near the transmission hole (Eg) located at the center.
The heat absorbing region (4) is formed by, for example, a blackening process using a heat-resistant black material.
As shown in FIG. 3B, black tungsten oxide (W ₂ O ₃ ) is simultaneously formed with the metal plate press forming of the first grid electrode (Gb).
Are temporarily and tightly adhered to the front and back surfaces of a predetermined region of the metal plate without gaps, and then embedded by press. Then, since the metal plate has plasticity, it is easily embedded in the surface layer portion of the metal plate simultaneously with press molding.

Next, the operation of the present invention based on the above configuration will be described. First, as before, three cathodes (Kr) (Kg)
When the cathode (Kg) located at the center becomes higher in temperature than the cathodes (Kr) and (Kb) on both sides when heating (Kb) and emitting an electron beam, the first grid electrode (Gb) and the cathode (Kb) are heated.
r) Since the interval (Lg) between (Kg) and (Kb) is very narrow, the heat of the cathode (Kg) is efficiently absorbed by radiation from the back surface of the first grid electrode (Gb) into the heat absorbing region (4). You. At the same time, when the temperature of the first grid electrode (Gb) rises due to the absorbed heat, the heat absorption region (4) is a black body, so that the temperature tends to be uniform and the absorbed heat is efficiently radiated from the surface. . Therefore, the heat radiation of the cathode (Kg) located in the center is improved, and the temperature is increased from high temperature to the cathodes (Kr) on both sides.
3 cathodes (Kr) (Kg) lowered to the temperature of (Kb)
The temperature of (Kb) becomes uniform.

In the above blackening treatment, the amount of heat absorption can be appropriately controlled by changing the density of the embedded particles.

[0010]

According to the present invention, in the cathode structure of the in-line type color cathode ray tube, the heat absorption region is formed at least in the surface layer near the electron beam transmission hole at the center of the first grid electrode. Of the three cathodes arranged and arranged in a straight line, the heat of the central cathode, which has become hot, is absorbed by the heat absorption region and dissipated from the surface, thereby improving the heat dissipation of the central cathode and lowering the temperature. . Therefore, the temperature of the three cathodes becomes uniform, and the brightness characteristics of each cathode are particularly kept uniform over a long period of time.
The white balance is stable, and the disturbance of color tone can be prevented.

[Brief description of the drawings]

FIG. 1A is a partially sectional side view showing an embodiment of a cathode structure of a color cathode ray tube according to the present invention. FIG. 2B is an enlarged sectional side view showing a main part of an embodiment of the cathode structure of the color cathode ray tube according to the present invention.

FIG. 2A is a partially sectional side view showing an example of a cathode structure of a conventional color cathode ray tube. FIG. 1B is a plan view of a cathode showing an example of a cathode structure of a conventional color cathode ray tube.

FIG. 3 (a) is a graph showing the temporal characteristics of luminance of three cathodes showing a conventional problem. (B) is a graph of luminance characteristics of three cathodes with respect to a first grid voltage showing a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cathode sleeve 2 Cathode sleeve 3 Cathode sleeve 4 Heat absorption area Kr Red cathode (cathodes on both sides) Kg Green cathode (center cathode) Kb Blue cathode (cathodes on both sides) Gb First grid electrode Er Electron beam transmission hole Eg Transmission hole for electron beam Eb Transmission hole for electron beam

Claims (3)

(57) [Claims] 1. An emitter material for emitting an electron beam is formed on each of upper end surfaces of three cap-shaped cathode sleeves, and a heater is inserted into each of the sleeves, and the sleeves are linearly aligned and arranged. A red, green, and blue cathode and three electron beam transmission holes corresponding to the above-mentioned cathode are formed in a metal plate formed in a predetermined shape, and are fixedly arranged at a predetermined interval with respect to the above-mentioned cathode. And a first grid electrode having a heat absorption region formed at least in a surface layer near a central electron beam transmission hole. 2. The cathode structure of a color cathode ray tube according to claim 1, wherein a heat absorbing region is formed by blackening with a heat-resistant black material. 3. The cathode structure of a color cathode ray tube according to claim 2, wherein the heat-resistant black material is tungsten oxide.