JPH04249849A - Display tube for light source - Google Patents

Abstract

PURPOSE:To improve fluorescent screen brightness with the heat ray of a tungsten evaporation source effectively absorbed and filming film damage reduced by providing an infrared ray absorbing film on a part of a glass bulb inner wall, and forming a metal-backed film on a part of the infrared ray absorbing film. CONSTITUTION:Carbon paste is applied in a peripheral direction on a part of the inner wall surface of a glass bulb 1, and baked and fixed to form an infrared ray absorbing film 7. A phosphor film 2 for a high-speed electron beam is formed on a head part inner wall surface in the bulb 1, and a lacquer liquid is injected on the film 2, applied, and dried to form a filming film 3. A metal mask 6 is inserted in the bulb 1, a tungsten evaporation source 5 in which an evaporation Al wire is mounted is inserted in the metal mask 6, and an Al metal film 4 is formed by an evaporation method. After that, baking is made to burn and decompose the film 3, and the film 4 is sticked on the film 2 to complete a fluorescent screen. This can reduce the temperature rise of the filming film 3 and film 3 damage, improving fluorescent screen brightness.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display tube for a light source, and more particularly to a display tube for a light source in which a filming film and a metal back film are formed on a phosphor film.

0002

2. Description of the Related Art FIG. 2 is a sectional view of a main part of a glass bulb structure showing the structure of a conventional display tube for a light source. In the same figure,
1 is a cylindrical glass bulb with one end sealed, 2 is a phosphor film formed on the inner wall surface of the head of the glass bulb 1, 3 is a filming film formed on the phosphor film 2, and 4 is a filter. This is an Al metal back film formed on the metal layer 3. Note that the filming film 3 is formed to temporarily support the Al metal back film 4 formed thereon, and will disappear after the phosphor screen is formed and will not remain for convenience of explanation. Above, illustrated. Therefore, after the phosphor screen is formed, the Al metal back film 4 is placed directly on the phosphor film 2.

0003

[Problems to be Solved by the Invention] However, the Al metal back film 4 in the conventional light source display tube is produced by depositing a phosphor film 2 for high-speed electron beams inside a cylindrical glass bulb 1 sealed at one end. After forming a filming film 3 by injecting and applying a lacquer liquid onto this phosphor film 2 and drying it, a tungsten evaporation source 5 is inserted into the glass bulb 1 as shown in FIG. A through the metal mask 6
Since the metal back film 4 was formed by vapor deposition, there were problems as described below. ■Tungsten evaporation source 5 and filming film 3 during formation of Al metal back film 4
Since the distance between the tungsten evaporation source 5 and the tungsten evaporation source 5 is very close, ie, 10 to 40 mm, the filming film 3 is heated by the heat of the tungsten evaporation source 5 and is susceptible to damage such as burnout, peeling, and expansion. (2) When the filming film 3 is damaged, the phosphor film 2 formed under it is also damaged, and even if light is emitted after being made into a tube, uneven light emission occurs, degrading the display quality. ■When the filming film 3 is heated, a large amount of gas is released, and this gas turns the Al metal back film 4 black.
The function of the Al film as a reflective film is significantly reduced, causing a reduction in the brightness of the phosphor screen.

0004

[Means for Solving the Problems] In order to solve the above problems, a display tube for a light source according to the present invention is provided with an infrared absorbing film on a part of the inner wall of a glass bulb.

[0005]

In the present invention, by providing the infrared absorbing film, the heat rays of the tungsten evaporation source are effectively absorbed, and damage to the filming film and the phosphor film is reduced.

[0006]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of a glass bulb assembly showing the structure of an embodiment of a display tube for a light source according to the present invention, and the same parts as those in the previous figures are given the same reference numerals. In the figure, a part of the inner wall surface of a cylindrical glass bulb (diameter 20 mm, length 60 mm) 1 with one end sealed is coated with carbon paste in the circumferential direction, and is baked and solidified to form an infrared absorbing film 7. It is formed. In addition, a phosphor film 2 for high-speed electron beams with a film thickness of about 12 to 16 μm is formed on the inner wall surface of the head inside the glass bulb 1 by a precipitation method, and a lacquer liquid is further injected onto this phosphor film 2. After coating and drying, the film thickness is approximately 0.
．． A filming film 3 of 8 μm is formed. Also,
A metal mask 6 is inserted into the glass bulb 1, a tungsten evaporation source 5 equipped with 4 mg of Al wire for evaporation is inserted into the metal mask 6, and a thickness of approximately 0.12 mm is formed by a known vacuum evaporation method.
An Al metal back film 4 with a thickness of μm is formed. In this case, the distance between the filming film 3 and the tungsten evaporation source 5 is about 20 mm. After that, baking is performed at about 460°C for about 10 minutes to burn and decompose the filming film 3 to form A.
A metal back film 4 is deposited on the phosphor film 2 to complete a phosphor screen for a display tube. Next, although not shown, by known means, the stem structure including the cathode and anode ring is inserted into the opening of the glass bulb 1, and the stem glass is heated with a gas burner to melt the glass and connect the glass bulb 1 and the stem. The tube is completed by joining it with the structure. Next, air is exhausted from the exhaust pipe of this tube to create a vacuum inside the tube, and then tip-off is performed to complete the display tube.

When the temperature rise curve of the filming film 3 was measured in the light source display tube constructed as described above, it was found that the display tube provided with the infrared absorbing film 7 had a higher temperature than the display tube without the infrared absorbing film 7. It was found that there was a temperature difference of about 130° C. (measured 1 minute after heating the tungsten evaporation source 5). Furthermore, regarding the state of the filming film 3, in the display tube provided with the infrared absorbing film 7, the Al metal back film 4 exhibited a normal Al color (silver color), and no abnormality was observed in the filming film 3. . On the other hand, in a display tube without the infrared absorbing film 7 as a comparative example, the color of the Al metal back film 4 was darkened, and peeling of the filming film 3 was observed in a part of the periphery of the phosphor screen.

The lacquer liquid used to form the filming film 3 is generally called a metal back paint used for cathode ray tubes, and is a toluene solution or methyl isobutyl methacrylate butyl ester polymer as a main component. It is a ketone solution. This paint holds approximately 4
It is commonly used because it completely thermally decomposes at around 00°C and does not cause any damage to the phosphor, but since it starts to decompose at relatively low temperatures (below 120°C), Drying or heating conditions must be tightly controlled. Glass bulb 1 during formation of Al metal back film 4
A part of the inner wall of is heated by the tungsten evaporation source 5, but at this time, the filming film 3 is also heated,
If the temperature rise is too rapid, the filming film 3 will be thermally decomposed. When the filming film 3 is damaged, the phosphor film 2 is also damaged, causing burnout, peeling, expansion, etc. Therefore, the temperature of the tungsten evaporation source 5 instantaneously rises to 1000° C. or more, and therefore, decomposition of the filming film 3 cannot be prevented unless some measure is taken to prevent temperature rise. Therefore, an infrared absorbing film 7 is formed on the inner wall surface of the glass bulb 1, and an Al metal back film 4 is formed thereon. In other words, since the blackbody radiation spectrum at a temperature of several hundred to 1000 degrees Celsius is in the infrared region of 2 to 20 μm, a layer that effectively absorbs infrared rays in this range is provided on the inner wall surface of the glass bulb 1 around the tungsten evaporation source 5. As a result, a temperature rise in the filming film 3 is small and a film with almost no damage can be obtained.

[0009] In the above-described embodiment, the infrared absorbing film 7 is made of carbon paste, but Si (infrared absorbing range: 1.1 to 10 μm),
Ge (infrared absorption range: 1.7 to 100 μm), PbTe
(Infrared absorption range: 3.4 to 30 μm), graphite, etc. are also suitable as the material, and it goes without saying that they may be used as part of the anode electrode as long as they have electrical conductivity.

0010

[Effects of the Invention] As explained above, according to the present invention,
By providing an infrared absorbing film on a part of the inner wall of the glass bulb, there is less thermal damage to the filming film when forming the metal back film, so there is no damage to the phosphor screen and a phosphor screen with good display quality can be obtained. It will be done. Moreover, since the metal back film does not darken and the mirror state of the metal back film can be maintained, extremely excellent effects such as improving the brightness of the phosphor screen can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a glass bulb structure showing the structure of an embodiment of a display tube for a light source according to the present invention.

FIG. 2 is a sectional view of a main part of a glass bulb structure showing the structure of a conventional display tube for a light source.

[Explanation of symbols]

1 Glass bulb 2. Phosphor film 3 Filming film 4 Al metal back film 5 Tungsten evaporation source 6 Metal mask 7 Infrared absorption film

Claims (1)

[Claims] 1. A light source display tube in which at least a phosphor film and a metal back film are laminated on the inner wall of a cylindrical glass bulb with one end sealed, wherein an infrared absorbing film is provided on a part of the inner wall of the glass bulb. . A display tube for a light source, characterized in that the metal back film is formed on a part of the infrared absorbing film.