Title :
Optical Properties of a-SiGe:H Thin Film Transistor for Infrared Image Sensors in Touch Sensing Display
Author :
Sang Youn Han ; Kyung Tea Park ; Ho Sik Jeon ; Yang Wook Heo ; Byung Seong Bae
Author_Institution :
LCD R&D Center, Samsung Display, Yongin, South Korea
Abstract :
We report the effects of monochromatic illumination on the electrical performance of a-SiGe:H thin-film transistor (TFT) and the use of this device as infrared (IR) image-sensing touch displays. In order to reduce the inevitable incidence of visible light into device, the visible cutting layer was designed, which played a critical role in reducing the optical noise from visible light. When the photo response was observed in real liquid crystal display (LCD) operation environment, it showed the display contents dependence, meaning that the supply of external IR light source for the touch sensing would be effective independent of any ambient light condition. Additionally, the optical noise from the display operation was eliminated using the block operation as well as the backlight IR light-emitting diode (LED) light modulation. From these, the clear touch images were successfully obtained in the a-SiGe:H photosensor embedded LCD panel.
Keywords :
Ge-Si alloys; LED displays; amorphous semiconductors; hydrogen; image denoising; image sensors; infrared detectors; infrared sources; liquid crystal displays; optical sensors; photodetectors; tactile sensors; thin film sensors; thin film transistors; IR image sensor; LCD operation environment; LCD panel; SiGe:H; TFT; ambient light condition; backlight IR LED light modulation; backlight IR light-emitting diode light modulation; electrical performance; external IR light source supply; infrared image sensor; liquid crystal display operation environment; monochromatic illumination; optical noise reduction; optical property; photo response; photosensor; thin film transistor; touch sensing display; visible cutting layer design; Band pass filters; Glass; Light emitting diodes; Optical noise; Optical sensors; Thin film transistors; Amorphous SiGe; infrared (IR) detector; photosensor; thin-film transistor (TFT);
Journal_Title :
Display Technology, Journal of
DOI :
10.1109/JDT.2012.2209171
