Multicolor Electroluminescent Displays

The development of a multicolor electro-luminescent (EL) display for instrument cluster which emits red, green and their mixed colors is presented in this paper. We constructed the EL display with a stacked panel configuration, which is composed of a lower panel of the green ZnS:Tb luminescent layer and an upper one of the red ZnS:Mn + filter luminescent layer. The display is based on three technologies. First, green luminance of the ZnS:Tb was improved by appropriately arranging the crystal environment around the Tb luminescent center. Second, a suitable red filter was developed to obtain red light by filtering ZnS:Mn. Last, a process to fabricate transparent EL panels was established. This technology allows the green panel to be located on the lower side of the red panel. As a result of these developments, the luminance of the display has been increased to a comfortable level.