|Budget Amount *help
¥14,300,000 (Direct Cost: ¥14,300,000)
Fiscal Year 1990: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1988: ¥9,000,000 (Direct Cost: ¥9,000,000)
In view of the recently growing large potential needs for multi-coloring in flat panel display systems, tunable color EL (TCEL) device which varies emission color by controlling applied voltage, has been developed by color mixing of dual or triple monochrome EL cells.
For color mixing methods for the dual color TCEL, for example, two kinds of primary color cells are stacked vertically on a glass substrate. In this case, ZnS : TbF_3 and ZnS : SmF_3 are used as emission layers, and two sources of driving voltage are applied across the top and bottom electrorodes to the middle ITO as the common electrode. To drive this control system, We have studied three kinds of color control methods : (a) applying two sources of sinusoidal wave voltage with their amplitude moderation, (b) applying square wave pulse voltage with their pulse width modulation and (C) applying a number of constant pulse voltage with their pulse code moderation.
Most of the significant results obtained in this work are summe
rlized as following ;
1. We have succeeded to realize R, G, B primary color emission with the TFEL (thin film electro luminescent) devices, with active layer materials of ZnS : TbF_3 and ZnS : SmF_3 and ZnS : TmF_3, respectively.
2. Low threshold voltage project has also been accomplished by new kinds of thin film dielectrics PbTiO_3, Nb_2O_5/Y_2O_3 as an insulating layer.
3. The dual color TCEL and the triple color TCEL devices are developed.
4. As the emission color control system, pulse code modulation has best availability for practical operations in view of stability, constant visual emission intensity with color regulation.
5. The emitted color in the full color TCEL device are comparable with those of the CRT of a conventional color TV set
The TCEL devices developed in this work have a wide variety of potential applications such as multi-indication systems in the aviation electronics, car electronics and traffic signal control systems. The obtained results in full-color TCEL show a realistic evidence of possibility for a flat panel color television. Less