Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Reexamination Certificate
1999-06-15
2001-08-28
Koslow, C. Melissa (Department: 1755)
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
C501S017000, C501S021000, C313S117000, C427S165000, C427S162000, C427S376200, C427S397700, C106S287340
Reexamination Certificate
active
06281152
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a paint of a shielding coat membrane and a lamp with the shielding coat membrane used for a high luminance discharge lamp of automobiles.
2. Description of the Related Art
Used for a high luminance discharge lamp for headlights of automobiles, it is necessary to form a black shielding coat membrane with an arbitrary shape on a glass surface of the lamp for contrasting light and shade in the projecting area.
FIG. 1
shows a structure of the discharge lamp of the D
2
R type automobiles. Numeral
1
of
FIG. 1
denotes a shielding coat membrane of which position and size are determined by the international standard. Numerals
2
a
,
2
b
denote electrodes made of tungsten in which the discharging emission is generated when the electrodes
2
a
,
2
b
are applied with an external voltage so that the lamp glows. Numeral
4
denotes an outer tube made of quartz glass. The shielding coat membrane
1
is formed on the surface of the outer tube
4
. Numeral
5
denotes an emission tube melted and fixed with the emission tube
5
at a portion
6
.
According to the conventional manufacturing process, first the outer tube
4
is melted and fixed with the emission tube
5
with a heating treatment by a gas burner. And the paint for the shielding coat membrane which is made of a black colorant of transition metal elements such as ferric oxide, copper oxide, and cobalt oxide, and also made of a binder of granulated glass is painted on the surface of the lamp. Then the lamp is sintered in the electric furnace at the temperature that the granulated glass is melted so that the desired shielding coat membrane is provided.
As the temperature at the glass surface of the lamp increases when the discharge lamp glows, the temperature of the shielding coat membrane formed on the glass also increases. Especially as for the discharge lamp of the D
2
R type automobiles, the temperature at the glass surface of the lamp increases up to 700° C., therefore the shielding coat on the glass surface is also exposed under the temperature of 700° C.
For the above reason, it is necessary to sinter the conventional lamp at the temperature more than 700° C.
While the granulated glass is conventionally used for the binder as described, the melting granulated glass does not have a good wettability with the above mentioned black oxide colorant. Thus the granulated glass does not perform as the binder to bind the black oxide colorants one another so that the robust membrane is difficult to be obtained and the cracks sometimes occur thereon.
Therefore it is desired for the shielding coat material which has good membrane strength and no crack.
SUMMARY OF THE INVENTION
To solve the problem, the paint of the shielding coat membrane for the discharge lamp according to the present invention comprises polycrystalline silica, Mn-doped ferric oxide, and granulated glass mostly made of silica.
And the above mentioned paint is painted on the surface of the lamp and sintered so that the lamp with the shielding coat membrane according to the present invention is provided.
Further a process for manufacturing the lamp with the shielding coat membrane according to the present invention comprises steps of painting a paint for the shielding coat which includes polycrystalline silica, Mn-doped ferric oxide, and granulated glass mostly made of silica, on the lamp surface, and sintering so as to form the shielding coat membrane.
The shielding coat membrane according to the present invention is provided such that the membrane has good membrane strength thereby suppressing pealing off, cracking, and discoloration thereon even when exposed in the temperature higher than 700° C. for 2000 hours.
REFERENCES:
patent: 5421877 (1995-06-01), Hayakawa et al.
patent: 6015592 (2000-01-01), Mifune et al.
patent: 797238 (1997-09-01), None
patent: 0797238 (1997-09-01), None
patent: 96/15548 (1996-05-01), None
Ikeda Masaru
Mifune Tatsuo
Koslow C. Melissa
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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