Television – Video display – Cathode-ray tube
Utility Patent
1998-07-06
2001-01-02
Britton, Howard (Department: 2713)
Television
Video display
Cathode-ray tube
C348S818000, C348S832000
Utility Patent
active
06169588
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a glass panel (panel) used for a color cathode ray tube.
Discussion of Background
Glass parts used for a color cathode ray tube are mainly a panel
1
for displaying picture images, a funnel-shaped funnel
2
and a neck
3
as shown in FIG.
5
. The panel
1
is sealingly attached to the funnel
2
by interposing a flit glass
5
between opposing seal edge surfaces
4
. The flit glass
5
is previously mixed with an organic binder to be in a slurry state, and the flit glass
5
is coated on the seal edge surface of the funnel
2
. After drying the flit glass
5
, the panel
1
is put on the funnel
2
by mutually opposing the seal edge surfaces. Then, the sealing is conducted by heat-melting the flit glass
5
.
The sealing operation to the panel
1
is carried out after a fluorescent layer and an electronically controlling screen which are necessary for displaying a colored picture image are attached to the inside of the hollow portion of the panel. Accordingly, the seal edge surface
4
of the panel is apt to suffer flaws or stains with material having electric conductivity such as carbon powder, iron particles and so on during manufacturing steps, transportation and so on. If the sealing is conducted with the flit glass to the edge seal surface having flaws and/or stains, there may result an electric conductive portion in the sealed portion. In this case, when a high voltage is applied to an inner or outer portion of the cathode ray tube, a predetermined strength or performance may not be assured. Heretofore, a special attention has been paid to the seal edge surface
4
of the panel
1
for a cathode ray tube in order to eliminate the above-mentioned problem.
For example, a seal edge surface in a completely mirror-like state reduces a possibility of attaching thereon stains including material having electric conductivity. Even if the stains are deposited, they can be removed by simply washing. However, there is still a problem that flaws or scratches are easily produced in the seal edge surface.
On the other hand, it is effective to prevent occurrence of flaws by simply forming a roughened surface in the seal edge surface. However, it is difficult to remove stains when they have fallen into recessed portions in the roughened surface. Japanese Examined Patent Publication JP-B-7-95431 proposes a roughened surface formed in a seal edge surface of a funnel. However, the roughened surface is to stably hold the flit glass when the funnel is sealingly attached to the panel. Since the proposed roughened surface has a minute convex/concave portion wherein a period (pitch) of adjacent concave portions (or adjacent convex portions) is small, simple application of the proposed roughened surface to the panel for a cathode ray tube is improper from the viewpoint of removing the stains.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a panel for a color cathode ray tube which eliminates simultaneously problems of difficulty in removing stains and preventing flaws adversely influencing the performance of the cathode ray tube and which had a seal edge surface capable of constituting a cathode ray tube having stable performance and strength.
The present invention has been attained by finding the facts that: (1) of flaws produced in a seal edge surface of the panel, any flaw which does not traverse the seal edge surface to bridge outer and inner sides of the panel even though it is in a point shape or a linear shape having a certain length, does not substantially influence the strength and performance of the cathode ray tube, and (2) when a toughened surface having a relatively large period between adjacent concave portions (or convex portions) is formed in order to prevent occurrence of a flaw, such roughened surface is effective to prevent stains.
Namely, in accordance with the present invention, there is provided a panel for a color cathode ray tube characterized in that an at least 10% portion in a width direction of a seal edge surface of the panel is a roughened surface which satisfies:
5 &mgr;m≦
R
z
≦30 &mgr;m,
150 &mgr;m≦
S
m
≦500 &mgr;m, and
0.015
≦R
z
/S
m
≦0.2
where R
z
represents an average depth of a concave/convex portion formed in the seal edge surface and S
m
represents an average period of adjacent concave or convex portions.
Further, in accordance with the present invention, there is provided a panel for a color cathode ray tube characterized in that a recessed portion having a roughened surface is formed in the entire circumference of a seal edge surface of the panel, wherein 10 &mgr;m≦d≦200 &mgr;m and d/D≦0.06 where D represents an open-end width in a width direction of the recessed portion and d represents the maximum depth of the recessed portion.
REFERENCES:
patent: 4054913 (1977-10-01), Lerner
patent: 4913817 (1990-04-01), Tsushima et al.
patent: 5280374 (1994-01-01), Nakai et al.
patent: 5300942 (1994-04-01), Dolgoff
patent: 5380318 (1995-01-01), Daikuzono
patent: 5592840 (1997-01-01), Miyasaka
Mizukami Masaki
Wakatsuki Hiroshi
Asahi Glass Company Ltd.
Britton Howard
Diep Nhon T
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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