Cathode-ray tube panel having thin conductive film

Details Cathode-ray tube panel having thin conductive film Cathode-ray tube panel having thin conductive film

1990-02-26

1992-03-24

O'Shea, Sandra

Electric lamp and discharge devices

Cathode ray tube

Envelope

313478, 220 21A, 445 14, H01J 920, H01J 2988

Patent

active

050991710

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a cathode-ray tube panel or face plate, and more particularly it relates to a cathode-ray tube panel having both antistatic and antireflective properties imparted to its outer surface and also to a method for producing the same.


BACKGROUND ART

Generally, a cathode-ray tube operates with a high voltage applied thereto, with the result that static electricity is generated on the outer surface of the panel upon switching or at other times, such static electricity causing dust to stick to the outer surface of the panel to degrade visibility or giving shock to a person when his hands touch the outer surface of the panel. There is another problem that incident light is reflected by the outer surface of a cathode-ray tube panel, also degrading visibility. Therefore, in cathode-ray tubes, particularly those for display purposes, it is desired to impart antistatic and antireflective properties to the outer surface of the panel.
For example, provision of a transparent electrically conductive metal film of tin oxide SnO.sub.2 on the back surface of a panel to prevent buildup of static electricity is disclosed in Japanese Utility Model Publication No. 8515/1969 and Japanese Patent Application Disclosure No. 94337/1984. Such SnO.sub.2 film, however, can be a cause of reflection of light on the front surface of the panel. Although various suggestions intended to prevent either buildup of static electricity or reflection of light have heretofore been made, there has no cathode-ray tube panel which achieves prevention of both buildup of static electricity and reflection of light.


DISCLOSURE OF THE INVENTION

This invention is intended to provide a cathode-ray tube panel having both antistatic and antireflective properties, characterized in that the outer surface of the glass panel is made in the form of a roughened surface having microscopic irregularities, said roughened surface being formed with a thin electrically conductive film made mainly of tin oxide SnO.sub.2 while retaining the shape of the irregularities of the roughened surface.
These and other features of the invention will become more apparent from the following description when taken in conjunction with the accompanying drawings.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view, partly broken away, of a cathode-ray tube panel;
FIG. 2 is an enlarged sectional view of the principal portion of an embodiment of the invention;
FIG. 3 is a microphotograph showing a roughened outer surface of a panel before it is formed with an electrically conductive film, and
FIG. 4 is a graph showing the relation between the thickness of an Sn.sub.2 film on the outer surface of a panel and reflectivity.


BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a cathode-ray tube in its entirety, wherein a glass panel 10 and a funnel 11 are fused together or fritted-glass-sealed together. The panel 10 has an outer surface 12 and an inner surface 13. FIG. 2 is an enlarged principal sectional view showing an embodiment of the invention, wherein the outer surface 12 of the panel 10 is made in the form of a roughened surface 14 having microscopic irregularities, said roughened surface being coated with a thin electrically conductive film 15 made mainly of tin oxide SnO.sub.2 while retaining the shape of the irregularities of the roughened surface 14. The material of the film 15 consists mainly of tin oxide SnO.sub.2, with a slight amount of antimony oxide Sb.sub.2 O.sub.3 added thereto. This is for the purpose of reducing the electric resistance of the film 15, the amount of Sb.sub.2 O.sub.3 added ranging from 0.1% to 4%, preferably from 0.2% to 2% with respect to SnO.sub.2.
From the standpoint of antireflective effect, the irregularities of the roughened surface 14 (FIGS. 2 and 3) forming the outer surface of the panel 10 would have no have an average diameter of not less than 3.mu. and an average roughness R of not more than 2.mu.; however, it is preferable that the average diameter be not more than 40.mu. (desirably not more

REFERENCES:
patent: 2820166 (1958-01-01), Pinotti
patent: 4731558 (1988-03-01), Haisma et al.

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