Browse Prior Art Database

Active Matrix Liquid Crystal Display

IP.com Disclosure Number: IPCOM000035298D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Kaida, Y: AUTHOR

Abstract

Disclosed is a device which has one thin oxide layer on a Black Matrix of Active Matrix Liquid Crystal Display (LCD) which has an amorphous silicon Thin Film Transistor (a-Si TFT) array. The thin oxide layer on the Black Matrix improves the performance of a-Si TFT, for example, drain current versus gate voltage characteristic, by decreasing reflection light emitted from a back light unit and injected into the a-Si TFT.

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Active Matrix Liquid Crystal Display

Disclosed is a device which has one thin oxide layer on a Black Matrix of Active Matrix Liquid Crystal Display (LCD) which has an amorphous silicon Thin Film Transistor (a-Si TFT) array. The thin oxide layer on the Black Matrix improves the performance of a-Si TFT, for example, drain current versus gate voltage characteristic, by decreasing reflection light emitted from a back light unit and injected into the a-Si TFT.

The LCD structure is shown in the figure. Black Matrix is generally made of a certain metal. The Black Matrix made of Ta and the thin oxide layer on the Black Matrix made of Ta2O5 are shown in the figure. Ta2O5 layer is a surface of Black Matrix oxidized by anodic oxidation.

Reflectivity is changed because light from the back light unit is interfered at the Ta2O5 layer on the Black Matrix. The control of reflectivity is done by adjusting a thickness of Ta2O5 layer. The thickness is accurately controlled by anodic oxidation voltage .

Amorphous silicon is sensitive to light with a wavelength between 400 nm and 650 nm. The thickness of the oxide layer (Ta205) in the figure is adjusted suitably in order to get reflectivity as low as possible. As reflectivity decreases, the light injected into a-Si TFT decreases. Consequently, TFT off current decreases, and on/off current ratio is improved in this LCD.

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