JPH04249848A - Display vacuum tube - Google Patents

Abstract

PURPOSE:To make low cost with a manufacture process simplified by laminating metal-backed films, composed of a laminated film of a phosphor film and metal powder, in order on a glass substrate. CONSTITUTION:Phosphor for a high-speed electron beam is precipitated on a glass substrate to form a phosphor film 2 having a prescribed film thickness. After drying, precipitated liquid, in which Al fine powder, etc., is melted, is injected on the film 2 and left stationary for a fixed time, and a supernatant liquid is removed and dried to form an Al powder layer 5 as a metal-backed film. This method eliminates processes of wetting, filming, trimming, and Al evaporation compared with a case where an Al metal-backed film is formed by a vacuum evaporation method, enabling low cost.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display vacuum tube having a metal back film on a phosphor screen.

0002

2. Description of the Related Art FIG. 2 is a sectional view of a main part showing the structure of a phosphor screen of a display tube for a light source, for example, which is used as a conventional display vacuum tube. In the figure, 1 is a glass substrate, 2 is a phosphor film, 3 is a filming film, and 4 is an Al metal back film. 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 fired 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

However, in the conventional light source display tube, the Al metal back film 4 is formed by forming the filming film 3 on the phosphor film 2 formed on the glass substrate 1, and Since the Al metal back film 4 was formed by forming an Al thin film using a vacuum evaporation method, there were the following problems. (1) A wetting process and a filming process are absolutely necessary in order to adhere the Al metal back film 4 in a uniform thin film form, and the concentration control and coating process of the lacquer liquid that forms the filming liquid used therein , a drying process, a trimming process, a firing process, etc., which required a large amount of man-hours. (2) In particular, the Al thin film formation process requires a vacuum evaporation process, which requires an extremely high cost process of vacuuming the inside of the glass tube and performing Al evaporation, and also requires temperature control of the evaporation source. There were many technical difficulties in controlling the film thickness.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the display vacuum tube according to the present invention, the metal back film formed on the phosphor film is composed of a laminated film of metal powder.

[0005]

[Function] In the present invention, since the metal back film is composed of a laminated film of metal powder, wetting steps, filming steps, trimming steps, and Al vapor deposition steps are not necessary.

[0006]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. FIG. 1 is a sectional view of essential parts of a phosphor screen showing a structure according to an embodiment of the present invention applied to a display tube for a light source as a display vacuum tube, and the same parts as those in the previous figures are given the same reference numerals. In the figure, a phosphor for high-speed electron beams is precipitated on a glass substrate 1 by a precipitation method to form a phosphor film 2 having a predetermined thickness. After drying, a precipitate containing, for example, fine Al powder dissolved therein is injected onto the phosphor film 2, left to stand for a certain period of time, the supernatant liquid is removed, and then dried to form an Al powder layer 5 as a metal back film. Form. This Al powder layer 5
is deposited on the phosphor film 2 to form a phosphor screen of a light source display tube.

In such a configuration, when accelerated electrons from a cathode (not shown) strike the phosphor screen, the accelerated electrons pass through the Al powder layer 5 and collide with the phosphor film 2, emitting light. let The generated light is transmitted through the glass substrate 1 and emitted, and the light directed toward the Al powder layer 5 is
The light is reflected by the Al powder surface and is emitted from the glass substrate 1 through the phosphor film 2.

In such a configuration, when accelerating electrons emitted from the cathode to the phosphor screen, the Al powder layer 5
It is necessary to allow the Al powder layer 5 to pass through and excite the phosphor film 2 formed under it, but if the thickness of the Al powder layer 5 is too thick, electrons cannot pass therethrough and therefore the phosphor is not excited. The maximum thickness of this Al powder layer 5 is the penetration depth Xe from the Thomson-Weddington formula: Xe=2.5×1
It can be calculated from 0-12 ・δ-1・V02 (cm),
For example, when the metal powder layer is Al powder and the accelerating voltage is 10 Kv, the penetration depth Xe is 0.93 μm. This makes it suitable for the metal powder to have a scaly and thin film shape. Note that metal powder has various shapes; for example, in addition to the aforementioned flake shape, there are also spherical, flattened, and
There are rod-shaped, foil-shaped, ultrafine powder, etc., and the Al powder layer 5 can be formed by selecting a suitable one among these.

Next, explanation will be given using a specific example. First, a diameter of 20 mm and a length of 60 mm was formed with an anode electrode formed on a part of the inner surface.
A phosphor for high-speed electron beams is formed on the head of a glass tube with one end sealed by a precipitation coating method to form a phosphor film 2 with a thickness of approximately 15 μm.
get. Next, 2 ml of an aqueous solution containing potassium silicate was injected into the glass tube, and then a precipitation solution containing a mixture of Al fine powder (scaly Al powder, thickness 0.1 μm) and barium acetate was injected, and the mixture was allowed to stand for about 15 minutes. place After a predetermined period of time has elapsed, the supernatant liquid is removed by a decanting method and dried to form an Al powder layer 5 made of fine Al powder. As described above, the phosphor film 2
, and after forming the Al powder layer 5, a light source display tube is formed by a normal vacuum tube manufacturing process.

[0010] In the above-mentioned embodiment, a case was explained in which the Al powder layer 5 was formed using Al powder to form the metal powder layer, but the present invention is not limited to this. Examples of metal powder include Au, Ag, In
, Sn, Pd, etc., the same effect as described above can be obtained. In addition, in the above-mentioned embodiment, the case where this metal back film was applied to the fluorescent screen of a display tube for a light source was explained, but the present invention
The present invention is not limited to this, and the same effects as described above can be obtained even when applied to cathode ray tubes, cathode ray tubes, and similar vacuum tubes that have fluorescent screens that emit light when electron beams strike them.

[0011]

[Effects of the Invention] As explained above, according to the present invention,
Since the metal back film formed on the phosphor film is composed of a laminate of metal powder, the conventionally necessary wetting process, filming process, trimming process, and Al vapor deposition process are all unnecessary, resulting in significant labor savings. In addition, it is possible to completely eliminate the occurrence of defects in these steps. Furthermore, since the metal back film can be formed by an extremely simple precipitation method, extremely excellent effects such as the ability to significantly reduce the occurrence of defective products can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a phosphor screen of a display tube for a light source, showing the structure of an embodiment of a display vacuum tube according to the present invention.

FIG. 2 is a sectional view of a main part of a fluorescent screen showing the configuration of a conventional light source display tube.

[Explanation of symbols]

1 Glass substrate 2. Phosphor film 5 Al powder layer

Claims (1)

[Claims] 1. A display vacuum tube characterized in that a phosphor film and a metal back film are sequentially laminated on a glass substrate, and the metal back film is composed of a laminated film of metal powder.