Coating processes – Electrical product produced – Fluorescent or phosphorescent base coating
Reexamination Certificate
1999-09-24
2001-05-08
Bareford, Katherine A. (Department: 1762)
Coating processes
Electrical product produced
Fluorescent or phosphorescent base coating
C427S068000, C427S232000, C427S235000, C427S238000, C118S500000, C034S440000, C034S441000
Reexamination Certificate
active
06228421
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing a cathode ray tube, such as is used for a television receiver or a computer display.
2. Description of the Prior Art
In the step for forming a phosphor screen on a glass panel in conventional methods for manufacturing a cathode ray tube, the inside surface
2
of a glass panel
1
having a wall portion
3
is coated with a coating fluid
5
for forming a phosphor screen, and then the glass panel
1
is lowered in the arrow direction “B”, with the inside surface
2
of the glass panel
1
facing downward as shown in FIG.
6
. After placing an end surface
3
a
of the wall portion
3
on a flat portion
4
a
of a panel support stand
4
, the coating fluid
5
that has been applied to the inside panel surface
2
is dried with a heater
6
.
However, in such conventional methods for manufacturing a cathode ray tube, if the glass panel
1
is lowered too fast in the arrow direction “B” onto the panel support stand
4
, and the wall portion end surface
3
a
is placed too fast onto the flat portion
4
a
of the panel support stand
4
, the coating fluid
5
adhering to the wall portion end surface
3
a
and drooping down from it is sandwiched between the wall portion end surface
3
a
and the flat portion
4
a
of the panel supporting stand. The pressure resulting from this sandwiching scatters the coating fluid
5
in the arrow direction “C”, so that it adheres to the inside panel surface
2
, which leads to irregularities of the phosphor formed on the inside panel surface
2
. As a result, the thickness of the phosphor layer formed on the inside panel surface
2
becomes uneven, which causes brightness irregularities in the cathode ray tube using this glass panel
1
.
Slowing down the speed with which the glass panel
1
is placed reduces the scattering of the coating fluid
5
over the inside panel surface
2
, but this prolongs the time for placing the glass panel
1
, and more time is required for forming the phosphor layer on the glass panel
1
. In other words, this approach leads to a decreased productivity for making a glass panel
1
on which a phosphor layer has been formed.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the problems of the prior art and to provide a method for manufacturing a cathode ray tube that decreases the scattering of the coating fluid adhering to the end surface of the wall portion when placing the glass panel on the panel support stand, so that a uniform phosphor layer can be formed on the inside surface of the panel without decreasing the productivity for making such a glass panel on which a phosphor layer is formed.
A method for manufacturing a cathode ray tube according to the present invention comprises a coating step, in which a coating fluid for forming a phosphor screen is coated to an inside surface of a glass panel having a wall portion provided with a wall portion edge at an outside surface of the glass panel; and a drying step, in which the coating fluid coated on the inside surface of the glass panel is dried after facing the inside surface of the glass panel downward and placing the wall portion edge onto a panel support stand in a manner that the panel is supported on the support stand primarily by the wall portion edge.
Because in this method the coating fluid adhering to the end surface of the wall portion is not easily sandwiched between the end surface of the wall portion and the panel support stand when placing the glass panel on the panel support stand, the scattering of the coating fluid caused by the pressure resulting from the sandwiching can be reduced. As a result, a uniform phosphor layer can be formed on the inside surface of the panel without decreasing the productivity for making such a glass panel on which a phosphor layer is formed. Thus, brightness irregularities in the cathode ray tube using this glass panel can be reduced.
In the method for manufacturing a cathode ray tube according to the present invention, it is preferable that the panel support stand is provided with a suction device for removing by suction unnecessary coating fluid adhering to the wall portion.
With this method, the unnecessary coating fluid adhering to the wall portion is removed by suction. Thus, when the glass panel is placed on the panel support stand, the scattering of the coating fluid adhering to the end surface of the wall portion can be reduced even further.
REFERENCES:
patent: 3652323 (1972-03-01), Smith
patent: 3791846 (1974-02-01), Nuehring
patent: 4513024 (1985-04-01), Morita et al.
patent: 6-156709 (1994-06-01), None
patent: 9/180632 (1997-07-01), None
Bareford Katherine A.
Cleveland Michael
Matsushita Electronics Corporation
Merchant & Gould P.C.
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