Electric lamp and discharge devices – Cathode ray tube – Screen
Reexamination Certificate
2000-05-04
2003-05-06
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Screen
C313S479000
Reexamination Certificate
active
06559590
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a paint for a heat absorbing film provided on a conductive reflecting film formed on a fluorescent surface on the inner surface of a panel of a color cathode ray-tube (CRT), a heat absorbing film obtained from the paint and a color CRT provided with the heat absorbing film.
2. Description of the Related Art
A color CRT of panel structure shown in, for example,
FIG. 2
has been hitherto known.
In
FIG. 2
, a reference symbol
21
denotes a transparent panel of a color CRT. A fluorescent surface
22
, consisting of red, green and blue fluorescent stripes and carbon stripes embedded therebetween, is formed on the inner surface of this transparent panel
21
. The fluorescent surface
22
is designed such that an electron beam emitted from an electron gun is selectively landed through a color selection electrode (not shown) on the respective colors of fluorescent stripes and scanned horizontally and vertically, to thereby display a color image. As the color selection electrode, an aperture grill having many slits formed at predetermined intervals or a shadow mask having many transparent holes formed in a predetermined arrangement is used.
In addition, to smooth an irregular surface formed by the fluorescent stripes, an organic intermediate film (not shown) is formed on the fluorescent surface
22
. A conductive reflecting film
23
made of aluminum referred to as a metal back is formed on the organic intermediate film in a state in which the film
23
covers the fluorescent surface
22
as well as the outer periphery of the surface
22
. The conductive reflecting film
23
is formed by aluminum having high light reflectance and high electron transmittance. Due to this, the film
23
functions to reflect light emitted toward the electron gun (not shown) to the transparent panel
21
side to increase display brightness and to stabilize the potential of the fluorescent surface
22
when the fluorescent surface
22
emits light.
Meanwhile, when the color selection electrode consisting of the aperture grill or the shadow mask is applied with an electron beam, the temperature of the electrode increases and the electrode is thermally expanded.
Further, aluminum which is a material for the conductive reflecting film
23
has also high heat reflectance. Due to this, when the film
23
is exposed, radiation heat from the color selection electrode which has been heated as a result of collision against the electron beam is reflected by the conductive reflecting film
23
and radiated again on the color selection electrode, with the result that the color selection electrode is further heated and further thermally expanded.
As can be seen, when the color selection electrode is heated and thermally expanded, the positions of the slits of the aperture grill or those of the transparent holes of the shadow mask are shifted and the correspondence between the color selection electrode including these slits or holes and the fluorescent stripes on the fluorescent surface
22
varies. As a result, the electron beam is erroneously landed on the fluorescent surface
22
and color slippage and the degradation of brightness and color purity disadvantageously occur.
To avoid these disadvantages, the following technique is conventionally, though partly, adopted. A heat absorbing film
24
is formed on the conductive reflecting film
23
to allow the heat absorbing film
24
to absorb heat radiated from the color selection electrode, the reflection and radiation of the heat from the conductive reflecting film
23
to the color selection electrode is suppressed to thereby prevent the thermal expansion of the color selection electrode.
As an example of such a heat absorbing film
24
, there is proposed a color CRT described in the Japanese Patent Examined Application Publication No. 62-47341. In the color CRT, aluminum is deposited in a vacuum of about 0.2 to 0.3 Torr and a heat absorbing film
24
formed out of a black aluminum film is thereby formed.
Further, in a cathode ray-tube described in the Japanese Patent Unexamined Application Publication No. 51-52782, a solution obtained by dissolving carbon in a solvent essentially consisting of an alcohol group is sprayed and a carbon film which becomes a heat absorbing film
24
is formed on the conductive reflecting film
23
.
In the case of the above-stated color CRT, however, the heat absorbing film
24
is formed by means of a deposition method in a vacuum of as low as 0.2 to 0.3 Torr. Due to this, the interior of a deposition unit is easily contaminated, a desired vacuum is difficult to attain and the film thickness of the heat absorbing film
24
becomes irregular and the heat absorbing effect thereof become unstable.
For these reasons, the reflection and radiation of the heat from the conductive reflecting film
23
to the color selection electrode cannot be efficiently suppressed, thus making it difficult to ensure preventing the electron beam from erroneously landing onto the fluorescent surface
22
and to manufacture a color CRT with sufficiently reduced color slippage. Furthermore, the irregular thickness of the heat absorbing film
24
causes irregularity in color purity resulting from scattered electrons.
Moreover, in the case of the above-stated CRT, the binding property for binding the carbon film serving as the heat absorbing film
24
and the conductive reflecting film is weak and the carbon film easily comes off due to external vibration. Thus, it is difficult to ensure high reliability against color slippage.
Besides, if the heat absorbing film
24
normally differs greatly in the coefficient of thermal expansion from the conductive reflecting film
23
made of aluminum and positioned under the heat absorbing film
24
and blocks the evaporation holes of the organic intermediate film formed on the conductive reflecting film
23
, then the film may disadvantageously crack in the heat treatment process or float from the conductive reflecting film
23
.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-stated circumstances. It is, therefore, an object of the present invention to provide a paint for forming a heat absorbing film which exhibits a good binding property for binding with a conductive reflecting film, suppresses color slippage and irregularity in color purity and is prevented from cracking and floating from a to-be-coated surface, a heat absorbing film obtained form the paint and a color CRT provided with the heat absorbing film.
To obtain the above object, a paint for a heat absorbing film provided on a conductive reflecting film formed on a fluorescent surface on an inner surface of a panel of a color CRT as claimed in claim 1 of the present invention, comprises:
a black pigment having a grain diameter of not less than 10 nm and not more than 2000 nm; and a compound represented by Si(OR1)nR2m, where n+m=4, n=1 to 4, m=0 to 3, each of R
1
and R
2
is one of an alkyl group, an alkenyl group and an aryl group, or a hydrolyzate of the compound.
Further, to obtain the object, a heat absorbing film for a heat absorbing film provided on a conductive reflecting film formed on a fluorescent surface on an inner surface of a panel of a color CRT as claimed in claim 5, comprises:
a black pigment; and a compound represented by Si(OR1) nR2m, where n+m=4, n=1 to 4, m=0 to 3, each of R
1
and R
2
is one of an alkyl group, an alkenyl group and an aryl group, the carbon number of R
2
falling within a range of 1 to 10, or a hydrolyzate of the compound.
Moreover, to obtain the object, a heat absorbing film as claimed in claim 8 of the present invention is formed by being coated with the paint for a heat absorbing film as claimed in claim 1 stated above.
To obtain the object, a heat absorbing film as claimed in the thirteenth aspect is formed by being coated with the paint for a heat absorbing film as claimed in the fifth aspect stated above.
Additionally, to obtain the object, a hea
Abe Shun-ichi
Ibaraki Kimiyo
Kimata Hitoshi
Metsugi Yasunori
Mori Masatoshi
Kananen Ronald P.
Patel Vip
Rader & Fishman & Grauer, PLLC
Sony Corporation
Williams Joseph
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