Cathode ray tube panel

Details Cathode ray tube panel Cathode ray tube panel

1999-12-07

2002-09-10

Patel, Nimeshkumar D. (Department: 2879)

Electric lamp and discharge devices

Cathode ray tube

Envelope

C313S47700R, C501S064000, C501S069000, C501S070000

Reexamination Certificate

active

06448707

ABSTRACT:

FIELD OF THE INTENTION
The present invention relates to a glass panel for a cathode ray tube, and more particularly, to a light-weight cathode ray tube panel having a reduced glass thickness and a high X-ray absorption coefficient.
BACKGROUND OF THE INVENTION
A cathode ray tube(CRT) such as a computer monitor and television picture tube comprises three principal parts: a glass panel through which video displays may be made; a funnel which has a yoke determining the course of electron beam generated from an electron gun and is attached to the panel; and a neck equipped with the electron gun. The glass panel is required to have, among others, the strength to withstand a static stress resulting from a pressure difference between the outside atmosphere and the internal vacuum as well as the ability to shield harmful X-ray radiation below a safety regulation level.
For this reason, conventional CRT panels have remained relatively thick, entailing such disadvantages as low productivity and high material costs. Therefore, there have been attempts to develop a light-weight glass panel having a high mechanical strength and a reduced glass thickness.
For example, U.S. Pat. No. 2,991,591 suggests that the thickness of a glass panel may be reduced by imparting residual compressive stress on the face of the glass panel, e.g., by prestressing the plate in order to compensate for the static stress; and Japanese Patent Laid-Open Publication Nos. 8-138579 and 7-21944 disclose that the thickness of the face area of a glass panel may be reduced by using a similar physical strengthening method. However, the extent of thickness reduction achievable by the above methods is limited because of their inability to meet the X-ray emission specification.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a light-weight, thin panel for a cathode ray tube having a high X-ray absorption coefficient and mechanical strength.
It is another object of the present invention to provide a cathode ray tube comprising the inventive glass panel.
In accordance with the present invention, there is provided a substantially rectangular glass panel for a cathode ray tube, characterized in that the panel is made of a glass having a linear X-ray absorption coefficient of at least 34 cm
−1
at a wavelength of 0.6 Å; the dimensions of the panel satisfy the condition of 0.07≦T/sqrt(D)≦0.09; and the panel is prestressed so that the surface of the face of the panel has a residual compressive stress ranging from 5 to 25 MPa, wherein T is the central thickness of the face of the panel in inches and D is the maximum diagonal line length of the face of the panel in inches.


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patent: 8-138579 (1996-05-01), None

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