Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
2001-02-06
2003-02-18
Pendegrass, Joan (Department: 2852)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C315S169300, C345S075100
Reexamination Certificate
active
06522062
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a fluorescent display device, and more particularly to a graphic-type vacuum fluorescent display (VFD) and a method for driving the same.
A conventional fluorescent display device will be described with reference to FIGS.
22
(
a
) and
22
(
b
) each showing a conventional anode substrate. The anode substrate shown in FIG.
22
(
a
) and that shown in FIG.
22
(
b
) are different in structure of openings from each other. In each of FIGS.
22
(
a
) and
22
(
b
), reference character S
1
designates an anode-side glass substrate which has a plurality of anode electrodes A
1
formed thereon. The anode electrodes A
1
have an insulating layer D deposited all thereover. The insulating layer D is formed thereon with grids G
2
to G
3
. The anode electrodes A
1
and grids G
2
to G
3
are arranged in a manner to be laminated on each other. The grids G
2
to G
3
and insulating layer D are formed with openings of either a rectangular or square shape or a circular shape. The openings have phosphors H
1
to H
2
arranged therein in a manner to be positioned on portions of the anode electrodes exposed through the openings, respectively. The grids G
2
and G
3
, phosphors H
1
and H
2
and insulating layer D are made by thick film screen printing.
In the structure shown in FIG.
22
(
a
), the phosphor H
1
and insulating layer D are formed into the same height. Whereas, in FIG.
22
(
b
), the phosphor H
1
is formed into a height smaller than the insulating layer D. Above the grids G
2
and G
3
are arranged filaments (not shown) in a manner to be positioned on a side opposite to the anode electrodes. Such arrangement is disclosed in Japanese Utility Model Application Laid-Open Publication No. 69354/1988.
The grids function to draw out electrons emitted from the filaments toward the anode electrodes, so that it is required to arrange the grids in proximity to the filaments rather than the anode electrodes. In each of the structures shown in FIGS.
22
(
a
) and
22
(
b
), the grids G
2
and G
3
are formed into a height larger than the phosphors H
1
and H
2
, to thereby be positioned in proximity to the filaments. Thus, in the structure of FIG.
22
(
a
), a part of electrons emitted from the filaments toward the anode electrodes A
1
is struck against an exposed surface Ds
1
of the insulating layer D, leading to accumulation of electrons or charges. Also, in FIG.
22
(
b
), the electrons are partially struck against an exposed surface Ds
2
of the insulating layer D, leading to the accumulation.
In the structure shown in each of FIGS.
22
(
a
) and
22
(
b
), the charges thus accumulated on the insulating layer cause a so-called electron eclipsing or shading phenomenon of repelling electrons traveling toward an end of the phosphor H
1
, so that the electrons fail to reach the end. This results in the end of the phosphor H
1
having a portion which fails to emit light. This is true of the phosphor H
2
as well. Affection of such an electron shading phenomenon is increased as a width of the anode electrodes and/or grids is reduced and an interval therebetween is reduced. More specifically, the affection is increased as definition is increased, resulting in a deterioration in quality of display.
Also, in the conventional fluorescent display device, the grids G
2
and G
3
and insulating layer D each are made of a thick film. In this regard, a thickness of the insulating layer D is generally restricted to a level as large as about 0.2 mm or more. Thus, formation of such a thick film into the insulating layer D leads to a failure in an increase in definition.
Further, in the conventional fluorescent display device, the filaments are stretchedly arranged so as to be spaced from each other at predetermined intervals, to thereby cause the anode electrodes positioned in proximity to the filaments and those away therefrom to be different in the amount of electrons traveling thereto, leading to a difference in luminescence between the anode electrodes or non-uniformity in luminance.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a fluorescent display device which is capable of minimizing non-uniformity in luminance, to thereby exhibit increased definition.
It is another object of the present invention to provide a fluorescent display device which is capable of reducing accumulation of charges on an insulating layer.
It is a further object of the present invention to provide a fluorescent display device which is capable of permitting electrons emitted from filaments to be uniformly spread or diffused in a plane-like manner.
In accordance with one aspect of the present invention, a fluorescent display device is provided. The fluorescent display device includes a first substrate, on which stripe-like phosphor-deposited anode electrodes and stripe-like grids are arranged in a matrix-like manner through an insulating layer. The anode electrodes, grids and insulating layer each are made of a thin film. The fluorescent display device also includes a second substrate, back electrodes each made of a thin film and arranged on the second substrate, and filaments stretchedly arranged between the first substrate and the second substrate.
In accordance with this aspect of the present invention, a fluorescent display device is provided. The fluorescent display device includes a first substrate, stripe-like anode electrodes and stripe-like grids arranged in a matrix-like manner on the first substrate through an insulating layer. The anode electrodes each have a phosphor deposited thereon. The anode electrodes, grids and insulating layer each are made of a thin film. The fluorescent display device also includes a second substrate, back electrodes each made of a thin film and arranged on the second substrate, and filaments stretchedly arranged between the first substrate and the second substrate. The grids and insulating layer are formed at portions thereof positioned at intersections between the anode electrodes and the grids with openings, and the phosphor is deposited on a portion of the anode electrodes exposed through each of the openings.
Also, in accordance with this aspect of the present invention, a fluorescent display device is provided. The fluorescent display device includes a first substrate, stripe-like phosphor-deposited anode electrodes and stripe-like grids arranged in a matrix-like manner on the first substrate through an insulating layer, a second substrate, stripe-like back electrodes each arranged on the second substrate, and filaments stretchedly arranged between the first substrate and the second substrate so as to extend in a longitudinal direction of the back electrodes.
Further, in accordance with this aspect of the present invention, a fluorescent display device is provided. The fluorescent display device includes a first substrate and stripe-like anode electrodes and stripe-like grids arranged in a matrix-like manner on the first substrate through an insulating layer. The anode electrodes each have a phosphor deposited thereon. The fluorescent display device also includes a second substrate, stripe-like back electrodes arranged on the second substrate, and filaments stretchedly arranged between the first substrate and the second substrate so as to extend in a longitudinal direction of the back electrodes. The grids and insulating layer are formed at portions thereof positioned at intersections between the anode electrodes and the grids with openings. The phosphors each are deposited on a portion of the anode electrodes exposed through each of the openings.
In a preferred embodiment of the present invention, the fluorescent display device further includes a means for giving a potential gradient to filament selection voltages applied to the back electrodes.
In a preferred embodiment of the present invention, the phosphors each have a surface arranged in proximity to the filaments as compared with a surfac
Ishikawa Kazuyoshi
Kawasaki Hiroaki
Kougo Katsutoshi
Ogawa Yukio
Futaba Corporation
Pendegrass Joan
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