Electroluminescent display device

A color electroluminescent (EL) display device comprises a transparent substrate, and a transparent electrode arranged on the transparent substrate. The EL display also includes an electroluminescent layer arranged on the transparent electrode that comprises a plurality of pixel units. Each pixel unit comprises at least two regions comprising electroluminescent materials capable of emitting light of different colors. The EL display further comprises a plurality of opposing electrodes arranged on the electroluminescent layer. Each of the opposing electrodes cooperates with the transparent electrode to apply a voltage to one of the at least two regions of each pixel unit.

BACKGROUND

1. Technical Field

The present disclosure relates to electroluminescent display devices and, more particularly, to a color electroluminescent display device.

2. Description of Related Art

Flat panel displays such as liquid crystal displays (LCD) are well known. LCD display devices can display colorful images. An LCD display generally includes a backlight module, which causes difficulties in reducing the total thickness of the LCD display. Therefore, it is desirable to provide a thinner flat panel display, such as an electroluminescent (EL) display device that can display colorful images.

DETAILED DESCRIPTION

Referring toFIG. 1, an electroluminescent (EL) display10includes a substrate20, a transparent electrode30, a plurality of opposing electrodes40, and an electroluminescent layer50. In the embodiment, the substrate20is made of glass. In an alternative embodiment, the substrate20may be made of other suitable material. The substrate20is transparent to provide a viewing surface through which a user can view images formed by the electroluminescent layer50.

The transparent electrode30is arranged on the substrate20. In the exemplary embodiment, the transparent electrode30is a thin sheet made of indium tin oxide (ITO). The transparent electrode30is shaped to match the substrate20.

Referring toFIG. 1andFIG. 2, the electroluminescent layer50is arranged on the transparent electrode30and can be made of any suitable transparent material. The electroluminescent layer50includes a base body54and a plurality of cavities52defined in the base body54to accommodate electroluminescent materials. The plurality of cavities52are arranged in a matrix pattern. Each of the cavities52is shaped in cylinder and has a circular opening in the electroluminescent layer50.

Moreover, the electroluminescent layer50includes a plurality of pixel units51. Each pixel unit51includes three adjacent cavities52which accommodate electroluminescent materials. The electroluminescent materials can be activated to emit lights of primary colors, that is, red, green, and blue light (RGB). Each pixel unit51includes three color regions53. The three color regions53can be controlled to display RGB colors, respectively, which can be combined to form a desirable color. The pixel unit51thus displays the desirable color.

The opposing electrodes40are arranged on the electroluminescent layer50. In the exemplary embodiment, each electrode40is aligned with one cavity52, which cooperates with the transparent electrode30to apply a voltage to the electroluminescent material in the cavity52, to cause the electroluminescent material to emit light.

In the exemplary embodiment, to prevent a short circuit, a first protective layer60is arranged between the opposing electrodes40and the electroluminescent layer50. Similarly, a second protective layer70is arranged between the transparent electrode30and the electroluminescent layer50. In the exemplary embodiment, the first protective layer60and the second protective layer70can be made of Ta2O5.

To form a desirable colorful image, certain pixel units51each need to display a predetermined color. For example, if a pixel unit51needs to display a yellow color, the red and green regions53in the pixel unit51need to display red and green colors, which combine to form a yellow color according to color mixing theory. One of the three opposing electrodes40corresponding to the pixel unit51is controlled to have a potential identical to the transparent electrode30, such that the corresponding electroluminescent material will not be activated to emit blue light. While, the other two opposing electrodes40are controlled to cooperate with the transparent electrode30to apply voltages to cause the corresponding electroluminescent materials to emit red and green light, respectively. The pixel unit51thus displays a yellow color.

Each pixel unit51can display different colors by applying different magnitude of voltages to the electroluminescent materials in the three cavities52of each pixel unit51. Specifically, by applying different magnitude of voltages, the electroluminescent materials in each cavity52can be caused to display colors of different levels. The pixel unit51can thus display different colors by mixing the lights of different colors emitting by the electroluminescent materials in the three cavities52.