Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
1999-10-28
2001-06-26
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C313S503000, C313S506000, C313S510000
Reexamination Certificate
active
06252356
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of dispersed multicolor electroluminescent (EL) lamps employed as backlights of liquid crystal displays and switch keys in a variety of small mobile equipment, and more particularly to dispersed multicolor EL lamps and EL lamp units employing thereof which not only satisfy practical functions such as visibility but also are aesthetically appealing.
BACKGROUND OF THE INVENTION
A conventional dispersed multicolor EL lamp is described using its sectional view in FIG.
9
. In
FIG. 9
, the thickness dimension is magnified for illustrative purposes.
In
FIG. 9
, indium tin oxide, for example, is deposited on a transparent resin film
1
using a deposition method such as vacuum sputtering to form a transparent electrode
2
. Then a phosphor layer
3
is formed by dispersing phosphor particles such as zinc sulfide doped with copper in a resin with high dielectric constant such as cyanic resin or fluororubber resin. A dielectric layer
4
is made of the same synthetic resin system as the phosphor layer
3
in which ferroelectric powder such as barium titanate is dispersed. A back electrode layer
5
is made of silver resin system or carbon resin system paste. An insulative cover resist
6
, followed by external electrodes
7
A and
7
B are then formed.
When multicolor text or graphics are displayed using the above conventional EL lamp, the text or graphics are directly drawn onto the surface of the transparent insulative film
1
using optically transmissive color paint; or a sheet on which text or graphics are drawn with optically transmissive color paint is attached to the transparent insulative film
1
. Alternatively, the luminescent color of the phosphor layer
3
is partially changed to match the text or graphics.
In the above conventional dispersed multicolor EL lamps, however, only one type of text or graphics can be displayed.
SUMMARY OF THE INVENTION
In the dispersed multicolor EL lamp in accordance with an exemplary embodiment of the present invention, a first transparent electrode layer is formed on a transparent resin film, and then a first luminescent layer at least containing a phosphor layer in which phosphor powder is dispersed is formed. Then, a transparent electrode layer and luminescent layer are formed layer by layer as a set to form N (N is an integer of N≧2) transparent electrode layers and N luminescent layers. One or more layers in the first to Nth luminescent layers are divided into multiple luminescent color regions for the required text or graphics in the same luminescent layer. A back electrode layer is then formed on the Nth luminescent layer.
The above configuration enables the display of multiple text and graphics in multiple luminescent colors using a single dispersed EL lamp.
In the dispersed multicolor EL lamp in accordance with an exemplary embodiment of the present invention, one or more layers in the first to Nth luminescent layers which are divided into multiple luminescent color regions show an almost colorless monocolor in the same luminescent layer when they are not illuminated, but emit multiple luminescent colors when they are illuminated. When the first to Nth luminescent layers are illuminated independently, multiple divided regions are illuminated in multiple luminescent colors without mutually affecting the coloring of each luminescent layer.
Also in the dispersed multicolor EL lamp in accordance with an exemplary embodiment of the present invention, one or more layers in the first to Nth transparent electrode layers or back electrode layer are electrically separated into two or more regions in the same transparent electrode layer or back electrode layer. This makes it possible to illuminate each divided region of the first to Nth luminescent layers in more than one luminescent color.
Also in the dispersed multicolor EL lamp in accordance with an exemplary embodiment of the present invention, each of the first to (N−1)th luminescent layers is formed of two layers. The first layer is a phosphor layer in which phosphor particles are dispersed. The second layer is formed of a light transmissive insulation layer with higher dielectric constant than that of the first layer. This enables even higher luminance to be achieved when any of the first to (N−1)th luminescent layers are illuminated.
In the dispersed multicolor El lamp in accordance with an exemplary embodiment of the present invention, the Nth luminescent layer is practically formed of two layers. The first layer is a phosphor layer in which phosphor particles are dispersed. The second layer is formed of a white insulation layer with higher dielectric constant than that of the first layer. This makes it possible to achieve even higher luminance when the Nth luminescent layer is illuminated.
Furthermore, in the dispersed multicolor EL lamp in accordance with an exemplary embodiment of the present invention, transparent electrode layers at least other than the first transparent electrode layer are formed of light-transmissive conductive paste with sheet resistance of 50 k or less by printing and drying transparent synthetic resin in which conductive indium tin oxide powder is dispersed. This facilitates the manufacture of the transparent electrode layer, such as by screen printing, at low cost.
Still furthermore, in the dispersed multicolor EL lamp in accordance with an exemplary embodiment of the present invention, the light-transmissive conductive paste for transparent electrode layers may be colored. This allows the overall luminescent color of each of the first to Nth luminescent layers to be changed.
In an EL lamp unit in accordance with an exemplary embodiment of the present invention, a microcomputer is employed to control the turning on and off and flashing of the first to Nth luminescent layers of the dispersed multicolor EL lamp separately or in combination. This makes it possible to automatically turn on, turn off, or flash each of the first to Nth luminescent layers independently or in combination in accordance with predetermined conditions.
Furthermore, in the EL lamp unit in accordance with an exemplary embodiment of the present invention, the microcomputer controls each of the electrically separated electrodes in the first to Nth transparent electrode layers and back electrode layer to automatically apply, shut, or intermittently apply voltage to each of the electrode layers electrically separated into multiple regions independently or in combination. This makes it possible to automatically turn on, turn off, or flash each of divided regions in the first to Nth luminescent layers corresponding to electrically separated electrode layers in the first to Nth transparent electrode layers and back electrode layer independently or in combination, in accordance with predetermined conditions.
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European Search Report, application No. EP 99 12 1080, dated Jan. 22, 2001.
Chikahisa Yosuke
Nishioka Naohiro
Tanabe Koji
Matsushita Electric - Industrial Co., Ltd.
Philogene Haissa
Ratner & Prestia
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