Coating processes – Coating by vapor – gas – or smoke – Metal coating
Reexamination Certificate
2001-06-14
2003-09-23
Meeks, Timothy (Department: 1762)
Coating processes
Coating by vapor, gas, or smoke
Metal coating
C427S255230, C427S255700, C427S064000, C427S124000
Reexamination Certificate
active
06623800
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for forming a composite vapor-deposited film having a varied film composition at initial and final stages of vapor deposition by means of continuous vacuum vapor deposition and to a composite vapor-deposition material suitable for use in vacuum vapor-deposition therefor. In particular, the present invention relates to a method for forming a composite vapor-deposited film which has a highly varied film composition as in a reflection film and a light-absorption film attached on fluorescent material of a cathode ray tube like a color television picture tube and to a composite vapor-deposition material suitable for use in vacuum deposition therefor.
DESCRIPTION OF THE RELATED ARTS
There is a need for obtaining a vapor-deposited film having plural laminated layers with different properties by means of a continuous vacuum vapor deposition process. In a cathode ray tube like a color television picture tube, for example, the inner surface of its face plate is coated with three-color fluorescent materials in the shape of dots or stripes, and a thin film layer having a high light-reflectance like aluminum is formed on this fluorescent material at the side opposite to the face plate, so that the aluminum thin film layer reflects light running inside the CRT of the visible light emitted from the fluorescent material and plays a role of increasing the amount of the light running through the face plate. In addition, on the backside of the fluorescent screen, a shadow mask or aperture grille is positioned which is a color selecting electrode to control the landing position of the electron beam on the fluorescent screen. This electrode transmits about 20% of the electron beam from the electron gun to the side of the fluorescent screen, and shields the remaining, about 80% of the electron beam. This about 80% of the electron beam will contribute to an increase in the temperature of the color selecting electrode. As the temperature increases, heat radiation from the color selecting electrode takes place, and this heat radiation converges on the closest fluorescent screen, so that most of the heat radiation is reflected by the aluminum thin film layer on the fluorescent screen. The reflected heat reaches the color selecting electrode again, and thus raises the electrode temperature to a greater extent. As the temperature rises, the color selecting electrode will undergo thermal expansion, causing its deformation. Consequently, it will be likely to result in mismatching the electron beam.
As described in U.S. Pat. No. 3,703,401, the surface of the aluminum thin film layer attached on the fluorescent screen is coated with a carbon coating, such that radiant heat from the color selecting electrode is absorbed by the heat absorption effect of the carbon coating. However, such a carbon coating must be dissolved in a solvent such as an organic solvent and the like to spray it for coating, and furthermore, it is necessary to carry out this coating step separately from a vapor deposition process of aluminum onto the fluorescent screen. Accordingly, these make not only the step troublesome, but also its continuous operation impossible.
When carbon or nickel with a property of absorbing heat rays and aluminum with a high light-reflectance are vaporized simultaneously in vacuum, it is possible to obtain a composite vapor-deposited film having an aluminum-rich composition at the initial stage of the vapor deposition and a carbon- or nickel-rich composition at the final stage of the vapor deposition, since the vapor pressure of aluminum is different from that of carbon and nickel. The aluminum-rich composition formed at the initial stage of the vapor deposition, however, contains large amounts of carbon or nickel, causing a decreased reflectance. Also, the carbon- or nickel-rich composition formed at the final stage contains large amounts of aluminum, and thus the property of absorbing heat rays cannot be satisfactory.
On the other hand, it is possible to form a vapor-deposited film of a two-layer structure having a fully different composition by loading the initial vapor-deposition material, aluminum, on a vacuum depositing tray to form a vapor-deposited film, followed by loading a vapor-deposition material different from the initial vapor-deposition material, such as carbon or nickel, on the vacuum depositing tray to carry out vapor deposition. However, this process requires two vapor deposition operations.
Deposition of chromium or iron having a property of absorbing heat rays is also carried out after the vacuum vapor depositing of aluminum having a high light-reflectance. In the composite vapor-deposited film having a layer of chromium or iron deposited on the aluminum layer, when heated to several hundred degrees centigrade after the vapor deposition, the chromium or iron may be diffused within the composite vapor-deposited film, resulting in mixing of the chromium or iron into the aluminum and a reduced light-reflectance of the aluminum layer. This leads to decreasing the brightness of a CRT.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a method for forming a composite vapor-deposited film capable of obtaining a CRT with superior brightness by means of continuous vacuum vapor deposition.
Another object of the present invention is to provide a composite vapor-deposition material and a method for producing the same which allows vapor deposition of an aluminum layer having high light-reflectance at an initial stage of the vapor deposition and subsequent, continuous vacuum vapor deposition of a layer having a property of absorbing heat rays, and at the same time, is suitable for forming a composite vapor-deposited film whose composition is not varied, even if receiving a heat history thereafter.
A further other object of the present invention is to provide a composite vapor-deposition material and a method for producing the same which is capable of enhancing brightness of a CRT by vapor depositing a layer of aluminum having high light-reflectance at an initial stage of the vapor deposition, and then continuously vacuum vapor depositing over the layer a layer having a tendency of transmitting a electron beam and a property of absorbing heat rays.
Therefore, a method for forming a composite vapor-deposited film according to the present invention which is capable of making a CRT with superior brightness by continuous vacuum vapor deposition comprises heating under reduced pressure a composite vapor-deposition material having an aluminum body and powder of a low vapor-pressure metal/metalloid compound retained in a core region of the aluminum body, vaporizing aluminum and low vapor-pressure metal/metalloid compound in series, and vapor depositing them on a substrate to be deposited.
In the specification, when materials of different types are heated under the same vacuum, a material which vaporizes at a low temperature is defined as a high vapor-pressure material, and a material which vaporizes at an elevated temperature is defined as a low vapor-pressure material. In the present invention, aluminum is utilized as a high vapor-pressure material. A metal/metalloid compound, for example, an oxide, carbide, and nitride, vaporizes at higher temperatures than aluminum, and are sometimes referred to as a low vapor-pressure material or low vapor-pressure metal/metalloid compound.
The above-mentioned low vapor-pressure metal/metalloid compound is of powder, and a composite vapor-deposition material having a structure in which such powder is dispersed and retained with aluminum in the core region of the aluminum body can be utilized to form a composite vapor-deposited film by continuous vacuum vapor deposition. As low vapor-pressure metal/metalloid compound powder can be employed an oxide, nitride, carbide, silicide, nitro-oxide, carbo-nitride, carbo-oxide, silico-oxide, silico-nitride, or boride of a metal/metalloid element. As a metal/metalloid element, at least one element can be selected from the group consisti
Hitachi Metals Ltd.
Meeks Timothy
LandOfFree
METHOD FOR FORMING COMPOSITE VAPOR-DEPOSITED FILM HAVING... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with METHOD FOR FORMING COMPOSITE VAPOR-DEPOSITED FILM HAVING..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and METHOD FOR FORMING COMPOSITE VAPOR-DEPOSITED FILM HAVING... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3016650