JPS63216294A - Electroluminescence display - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a thin film EL display device that emits all EL light in response to the application of an electric field, and particularly relates to a thin film EL display device that emits all EL light in response to the application of an electric field, and in particular to a light transmission type EL display device that uses ZnS:Mn as a light emitting layer material. This invention relates to a yellow-orange light emitting EL display device.

<Prior art> The emitted light color of a thin film EL device varies depending on the type of luminescent center added to the light emitting layer base material, and by adding rare earth elements such as manganese (Mn) or terbium (Tb), various colors can be produced in the visible range. A luminescent color is obtained. Thin film EL devices that have already been put into practical use are those in which Mn is added as a luminescent center in a ZnS film, but the luminescent color is limited to yellow-orange.

For this reason, the red, green, and
High-brightness thin film E that emits three primary colors of blue and white light
The development of L elements is desired.

<Problems to be Solved by the Invention> White light emission exhibits a uniform energy distribution in the visible range, or even if it has a linear spectrum.

It is obtained by mixing multiple complementary colors of light, such as red and blue-green, and orange and blue. The former is extremely difficult to achieve in light-emitting devices that utilize localized luminescent centers, such as thin-film EL devices, and the emission spectrum of the latter also depends on the type of luminescent center added. There are problems such as difficulty in obtaining

Praseodylam (Pr) and dysprosium (Dy
) has an emission spectrum I that satisfies the relationship of complementary colors even when added singly.
Since it shows -/y, light emission close to white can be obtained, but the brightness is insufficient.

The present invention has been made in view of the above problems, and is
The purpose of this invention is to obtain high-intensity white light emission in a light transmission type yellow-orange light emitting EL display device using nS:Mn as a light emitting layer and using a transparent conductive film as an electrode material.

<Means for solving the problem> The light reflectance or light transmittance of the light at a wavelength of 460~
A blue plate having a maximum wavelength around 495 nm is arranged.

<Example> FIG. 2 shows the light emission spectra of a thin film EL device using a ZnS:Mn film as a light emitting layer. Mn in ZnS has wavelength 5
It emits yellow-orange light with a peak at 85 nm and a half-width of about 5 Q nm. The chromaticity coordinates of the emitted light colors are shown on the chromaticity diagram in FIG. From the above-mentioned complementary color relationship, white light emission can be obtained by mixing the light emission having the chromaticity coordinates within the diagonal lines in the figure, that is, the blue light emission with a wavelength of around 460 to 495 nm, with the yellow-orange light emission of ZnS:Mn. It will be done. However, at present, high-intensity blue light emission that satisfies the above conditions cannot be obtained from thin-film EL elements. Therefore, behind the EL element,
A blue plate with high reflectance or transmittance in the above wavelength range is installed. Since the EL element is transparent, the blue light reflected or transmitted from the external light is mixed with the total EL light emission to obtain white light emission. As a result, in a dark room with no external light, it is possible to display yellow-orange light on a black background as before, and under external light, it is possible to display white on a blue background.

As an example, FIG. 1 shows a configuration diagram in which the above-mentioned blue plate is used as a protective backing glass plate of a special EEL screen. In the figure, 1 is a blue glass plate, 2 is a transmission type yellow-orange light emitting E
L element 3 is a glass substrate.

<Effects of the Invention> As described above in detail, according to the present invention, high-intensity white light emission can be obtained using a transmission type EL element that emits yellow-orange light.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention in which a blue plate is used as a protective backing glass plate for an EL element. Figure 2 is Z
FIG. 2 is an emission spectrum diagram of a thin film EL device using nS:Mn in a light emitting layer. Figure 3 is a chromaticity diagram, and Zn
S: Shows the emission color and white region of the MnEL element. Explanation of symbols 1: Blue glass plate, 2: Transmissive yellow-orange light emitting EL element, 3
Niglass substrate. Agent Patent Attorney Takeshi Sugiyama (and 1 other person) 1! , Figure 7 Depletion length (nm) True 2 Figure

Claims (1)

[Scope of Claims] 1) A light-transmissive electroluminescent device having a light-emitting layer in which Mn is added as a light-emitting center in a ZnS film, and a transparent front electrode and a transparent back electrode for applying voltage to the light-emitting layer. An electroluminescence display device characterized in that a blue plate having a high light reflectance or light transmittance at a wavelength of 460 to 495 nm is disposed behind the transparent back electrode.