Red-emitting CaS:Eu, Ce, Cu, reddish orange-emitting SrS:Eu, Ce, Cu and blue-emitting SrS:Ce, Cu phosphors were prepared by baking the mixed powders of corresponding host and dopant materials. The luminance, luminous efficiency, transported charge, and EL spectra have been measured in order to study optimal content of dopants and firing temperatures.
There are such problems as low luminance and slow buildup in light output when fabricating red-color CaS:Eu phosphors by using the rf-sputtering tequnique. The effects of Cu codopant in a sputtering target and H_2S in a sputtering gas were studied to improve the performance of the red-color EL devices. It was found from this experiment that the Cu co-dopant increases the amount of transported charge through the active layer and the H_2S incorporation in the sputtering gas provides quick response of light output.
The green-emitting ZnS:TbOF phosphors were fabricated by sputtering a novel doubly-layered pressed target. This newly proposed target was found to be capable of avoiding the particle contamination. A systematic study on phosphor film preparation conditions was also made to improve the performance of green-emitting ZnS:TbOF TFEL devices. A developed device in this work typically shows the luminance exceeding 120 cd/m^2 at V_<th> +30 V with a frequency of 60 Hz.
An 8-inch diagonal gas-discharge panel with resistors has been fabricated and TV pictures have been displayed on it by means of a pulse memory drive scheme. The panel with resistors is the panel promising long life time and high luminous efficiency. To decrease the deviation of resistance in the whole panel area, a new structure of resistor has been introduced into the panel. This structure is characterized by striped resistive material and comb-shaped terminator, both fabricated by thick-film printing.
White light emitting thin-films electroluminescent (TFEL) devices with (SrS:Ce/ZnS:Mn)_n multilayered phosphor thin-films have been investigated. The luminance and efficiency of the ZnS:Mn/SrS:Ce/ZnS:Mn TFEL device are 50 cd/m^2 and 0.4 lm/W at 50 Hz. The color tone dose not vary with the driving voltage. The electrical properties of the multilayered TFEL device such as an transferred charge density and a threshold voltage are dominated by the characteristics of the SrS:Ce layer.
An eye contact display system of 100 in, display size is studied. It is mainly composed of both a 100 in. PDLC screen and four video projectors. The 100 in. PDLC screen works at video field frequency. Display brightness and its distribution are compared for two different types of projection method. Proposed display system has some disadvantages of low brightness and image seam, but it is confirmed that large screen eye contact display is useful for visual telecommunication with reality.