JPS5923358Y2 - electroluminescent device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electroluminescence device whose main purpose is to be used as a backlight for a liquid crystal display device.
A transparent protective layer containing a fluorescent material is bonded to the light-emitting surface of the electroluminescent device, and in bright daylight, external light stimulates the fluorescent material to produce illumination light, and a voltage is applied in the dark to produce luminescent light. When a surface emits light, the fluorescent material is stimulated to emit fluorescence at the same time that the emitted light is transmitted, and even though the fluorescent material is dispersed inside, the amount of electroluminescence emitted is substantially reduced. This is to prevent it from decreasing.

Liquid crystal display devices such as digital watches are often used in which the liquid crystal layer in the area where characters are displayed is made opaque, and the opaque color is often black.

Conventionally, liquid crystal display devices have a white reflective plate installed behind them to improve display quality by creating a clear contrast between external light and the opaque display characters on the liquid crystal layer. If Ellen I. Luminescence is placed in place of the reflector, not only will the reflective performance deteriorate, but the background color of the luminescent will appear, resulting in poor contrast. Since it cannot be transmitted, the effect of the backlight is almost ineffective.

In a place where there is external light, this device functions similar to a conventional reflector due to the fluorescent material scattered inside, and when a voltage is applied in a dark place to emit surface light, the fluorescent material is excited by the light emitted. This device generates fluorescent light and does not substantially impair the amount of the emitted light.

An embodiment of the present invention will be described with reference to the accompanying drawings.

Reference numeral 1 in the figure shows an example of electroluminescence, in which a fluorescent layer 4 is provided on an inductive layer 3 overlaid on a back electrode 2, and a transparent electrode 5 is overlaid thereon.

The above-mentioned dielectric layer 3 is made of titanate barium ceramic, and a mixture of fluorescent material powder such as ZnS and glass powder is baked on the dielectric layer 3 to form a fluorescent layer 4. The back is baked with silver.

The transparent electrode 5 is formed by baking SnO2 onto the fluorescent layer 4.

This electroluminescence 1 emits light with a brightness of, for example, about 3 fL when a voltage of about 50 V and 200 Hz is applied to the back electrode 2 and the transparent electrode 5.

Reference numeral 6 denotes a transparent protective layer bonded onto the above-described transparent electrode 5, which is made of a transparent epoxy resin, polyester resin, acrylic resin, etc., and contains diaminostilbendisulfone, a fluorescent white dye, in these resins. A material obtained by mixing and dispersing 5 to 20 wt % of an acid derivative, an imidazole derivative, etc. and spreading the mixture to a thickness of 1 mm or less is used.

Although an organic fluorescent white dye is used in the above method, the color of the dye may be changed depending on the purpose of use, or an inorganic fluorescent pigment may be used.

7 is a liquid crystal display device, and a transparent protective layer 6 is bonded to the back surface thereof.

As illustrated in the drawings, the present invention, when mounted behind the time display liquid crystal display device 7 of a digital wristwatch, allows external light such as during the daytime to pass through the portion excluding the opaque display characters.
The fluorescent material mixed and dispersed in the transparent protective layer 6 is stimulated to produce fluorescent light emission, and the background color of the electroluminescence 1 is completely hidden, so that the color of the opaque display characters and the above-mentioned fluorescent light emission are different. Displays the time in good quality with contrast.

When electroluminescence is surface-emitted in a dark place, the amount of light transmitted through the transparent protective layer 6 is reduced due to the fluorescent substance dispersed inside, but the fluorescent substance that blocks the transmission of light is stimulated and becomes fluorescent. The light illuminates the liquid crystal display device 7 from the back.

According to experiments, the brightness as an electroluminescent backlight was completely equal when the transparent protective layer was made colorless and when a fluorescent substance was mixed.

The present invention has the effect described in detail above, and the fluorescent substance dispersed inside the transparent protective layer 6 is stimulated by external light to glow in a fluorescent color, and when it emits electroluminescence in a dark place, the luminescence The material is stimulated by the electroluminescent material to emit light, hardly reducing the total amount of light emitted, and has the property of hiding the background color of electroluminescence, so it has the effect of being suitable for backlighting of liquid crystal display devices and the like.

[Brief explanation of the drawing]

The accompanying drawing is a longitudinal sectional front view showing an embodiment of the present invention. 1 → Electroluminescence, 6 → Transparent protective layer.

Claims (1)

[Scope of utility model registration request] An electroluminescent device in which a light-transmitting protective layer containing a fluorescent substance is bonded to the light-emitting surface of the electroluminescent device.