JPS601734A - Projection type cathode-ray tube - Google Patents

Abstract

PURPOSE:To effectively prevent the destruction of a sealing section resulting from thermal expansion and the leak of coolant and the generation of a bubble following the coolant leak by providing a notched section that performs external air ventilation on a bracket arranged on the external surface of a face section and arranging a bellows assembly body that is airtightly connected to the coolant space in this notched section. CONSTITUTION:Coolant 9 is injected from an injection port 10 and the space between both panels and the inner part of a bellows assembly body 16 are filled and sealed. When the temperature of a face section increases, inner pressure is generated in the sealed coolant 9 by the thermal expansion and carburetion of the coolant 9. This pressure presses and expands a soft bellows 18 and volume expansion components are absorbed in the bellows. The volume of the pressed and expanded components pushed out the air of a notched section 14 into atmospheric pressure through a ventilating hole 19 and as a result the internal volume is kept in stationary status. Besides, even if a bubble is generated in the sealed coolant 9, the bubble is smaller in specific gravity than liquid, the bubble floats and is collected to the bellows assembly body 16.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a projection type cathode ray tube, in particular, a projection type cathode ray tube, in which a second panel is disposed parallel to the outer surface of the face portion of the panel, and a liquid refrigerant is sealed in between. This relates to a cooled projection type cathode helmet tube.

[Background of the invention]

Projection type cathode ray tubes generally require high output because of the need to obtain high brightness, and as a result, the temperature of the panel face portion where the electron beam strikes increases significantly. The luminescent properties of the phosphor surface deteriorate as the temperature of the phosphor increases, and if the temperature increases significantly, cracks may occur in the panel itself.

In order to prevent such a situation, in the case of a projection type shaded gauze tube, it is customary to provide cooling by disposing a refrigerant on the outer surface of the 7th section.

FIG. 1 shows an example of a conventionally used liquid-cooled projection cathode ray tube with this glaze. In the figure, 1 is a projection type cathode ray tube, 2 is an electron gun disposed in the neck, 3 is an electron beam, and 4 is a fluorescent surface formed on the inner surface of the 7th part of the panel 5. In order to arrange the refrigerant on the outer surface 6 of the 7-space part of this panel 5, a frame-shaped bracket 7 made of M gold and having good thermal conductivity is arranged around the outer periphery, and this bracket 7 is further sandwiched between the frame-shaped brackets 7 and parallel to the panel 5. Place the transparent outer second panel 8 flat on the
A refrigerant 9 is sealed in the space formed between them. As the refrigerant 9, one made by mixing ethylene glycol and pure water is generally used, and this liquid refrigerant 9 is used in the bracket 7.
The refrigerant is poured into the space from one of the injection ports 10 provided in the face, air is removed from the other side, and the space is filled with refrigerant so that no air bubbles remain on the face surface, and then the injection ports 10 are sealed. The panel 5.8 and the bracket 7 are airtightly fixed using a silicon adhesive 11 having excellent temperature characteristics.

Such a projection cathode ray tube is mounted so that the bracket 7 comes into contact with a housing (not shown) inside the receiver. Therefore, the heat generated in the face portion during operation is transmitted from the bracket 7 to the supporting body and is radiated.

In the above configuration, the temperature distribution of the face portion is as shown in Figure 2 (
(Equivalent to a side view of part A-A') As shown in the figure, the center part A is highest, where it is constantly heated by the electron beam and where the most heat escapes by thermal conduction, and the upper part where the warmed refrigerant rises. The temperature is the second highest at B, decreases at the side C due to heat radiation through the bracket 7, and is the lowest at the bottom.

Therefore, the refrigerant 9 causes a convection phenomenon in the direction of the arrow 12 centering on the part A, releases heat through the bracket 7, and tries to maintain a constant temperature.

However, while such convection is taking place, the refrigerant near the upper part B is at a high temperature and therefore undergoes thermal expansion compared to the refrigerant near the lower part D. As mentioned above, this space is in a sealed state, and the refrigerant that has increased due to thermal expansion has no place to escape, so the internal pressure increases. In addition, the cold part itself becomes vaporized, and eventually the inlet l
As a result of the O evaporating through the sealed portion, air bubbles 13 are generated in the sealed refrigerant 9, and at the same time, the airtightness of the adhesive 11 is broken, causing liquid turbidity. Once a liquid leak occurs, more bubbles are generated corresponding to the reduced amount of refrigerant, and as these bubbles grow, they eventually appear as shadows on the image, making it impossible to fulfill the role of a projection cathode ray tube.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to eliminate sealing caused by thermal expansion in a projection cathode ray tube in which a space provided on the outer surface of the panel face is sealed with a liquid refrigerant. The object of the present invention is to provide a structure that can effectively prevent damage to the cooling medium, leakage of the cooling medium, and the generation of bubbles associated with this.

[Summary of the invention]

In order to achieve such an object, the present invention provides a notch part that has ventilation with the outside in a bracket placed on the outer periphery of the face part, and a bellows assembly that is airtightly connected to the space in this notch part. This is what was placed. Hereinafter, the present invention will be explained in detail using Examples.

[Embodiments of the invention]

FIG. 3 is a sectional view showing an embodiment of the present invention.

In the figure, the bracket 7 is different from the simple frame-shaped one shown in FIG. 2, and has a notch 14 in the upper part. The inner periphery of the bracket 7 forms a slope 15 on both sides of the dowel. Furthermore, the refrigerant 9 in this notch 14
A bellows assembly 16 is disposed on the side filled with water. As shown in FIG. 4, this bellows assembly 16 consists of a metal frame 17 and a bellows 18, is welded to the bracket 7 at the metal frame 17, and is formed by both panels 5 and 8. It is airtightly connected to the space. The bellows 18 is a thin, flexible rubber-like material having a bag-like shape, and is welded to the bottom center of the rectangular box-shaped metal frame 17 with the surface in contact with the refrigerant 9 enlarged, and is shown by the arrow. It is shown so that no gas or liquid will leak from the direction. Furthermore, this bellows 1
8 shall have corrosion resistance against refrigerant liquid.

Further, the cutout portion 14 maintains ventilation with the outside by a ventilation hole 19 provided in the center.

In the above configuration, the refrigerant 9 is injected from the conventional energizing inlet IO to fill and seal the space between both panels and the inside of the bellows assembly 1-6. When the temperature of the face portion increases, internal pressure is generated in the sealed refrigerant 9 due to thermal expansion and vaporization of the refrigerant 9. This pressure is a flexible bellows! 8 is expanded, and the volumetric expansion due to thermal expansion and vaporization of the refrigerant 9 is absorbed therein. In particular, these effects occur very effectively because the thermally expanded liquid and gas collect in the upper portion where the bellows assembly 16 is located. The volume of the expanded part is
The air in the notch 14 is vented! 9 to the outside (atmospheric pressure), and as a result the internal pressure is maintained at a steady state. Therefore, there is no possibility that the sealing part will be destroyed by internal pressure and leakage will occur. Of course, the notch 14 and the bellows assembly 16 are located on the effective surface of the face, so they do not interfere with the image.

Furthermore, even if bubbles occur in the sealed refrigerant 9,
Since the air bubbles have a lower specific gravity than the liquid, they float to the surface and collect in the bellows assembly 16, so they do not cast shadows on the image.

In particular, since the upper inner periphery of the bracket 7 forms the slope 15, air bubbles generated and floated up enter the inside of the metal frame 17 and hide without staying on the face portion.

〔Effect of the invention〕

As explained above, according to the present invention, by providing the bellows assembly in the upper part, the internal pressure caused by thermal expansion and vaporization is absorbed by the increase in volume while remaining in a sealed state, thereby preventing the destruction of the sealing part and the refrigerant. It is possible to effectively prevent leakage and the generation of air bubbles associated therewith, and it has a great effect on improving the quality and reliability of liquid-cooled projection cathode ray tubes.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view in the tube axis direction showing an example of a conventional liquid-cooled projection cathode ray tube, FIG. FIG. 4 is a cross-sectional view in a direction perpendicular to the tube axis showing one embodiment, and FIG. 4 is a perspective view showing a bellows assembly. ! ...Projection cathode ray tube, 5...Panel, 7...
...Bracket, 8...Second panel, 9...
Refrigerant! 4...notch part! 6... Bellows assembly, 17... Metal frame, 18... Bellows, 1
9...Vent hole.

Claims (1)

[Claims] A projection type in which a frame-shaped bracket is arranged around the outer periphery of the face of the panel, a second panel is arranged parallel to the outer surface of the face, sandwiching this bracket, and a liquid refrigerant is filled in the space formed in between. In the cathode ray tube, a part of the bracket is provided with a notch having ventilation with the outside,
A projection cathode ray tube characterized in that a bellows assembly airtightly connected to the space is disposed in the notch.