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Stepwise Voltage Compensated Driving for A Vertical Aligned LCD

IP.com Disclosure Number: IPCOM000013606D
Original Publication Date: 2000-Mar-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 2 page(s) / 261K

Publishing Venue

IBM

Abstract

Disclosed herein is a stepwise-voltage compensated driving method for vertical aligned LCD, where applied voltage for Blue (B), Green (G), Red (R) color is set to different amplitude and slicing step of gray level. This driving method is optimized for a normally black (NB) vertical aligned color LCD, which has different T-V (transmittance-voltage) curve for each B, G, R color. Steep-ness of each color is different and Blue is the steepest, Green is next, and Red is the slowest.

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Stepwise Voltage Compensated Driving for A Vertical Aligned LCD

  Disclosed herein is a stepwise-voltage compensated driving method for vertical aligned LCD, where applied voltage for Blue (B),

   Green (G), Red (R) color is set to different amplitude and slicing step of gray level. This driving method is optimized for a

   normally black (NB) vertical aligned color LCD, which has different T-V (transmittance-voltage) curve for each B, G, R color.

Steep-ness of each color is different and Blue is the steepest, Green is next, and Red is the slowest.

The driving voltage level of "off and on" switching is set to 1-2.5 V for Blue (B), 1-3.5 V for Green (G), and 1-4.5 V for Red (R), respectively. The upper voltage will have the +/- 0.5 voltage range such as 2.0 to 3.0 V for Blue (B), 3.0 to 4.0 V for Green (G),
and 4.0 tp 5.0 V for Red (R) color. This range depends on d·n value, where threshold voltage Vth decreases as d·n increases. The gray-level slicing for each color is optimized to be almost the same transmittance for each color, depending on gamma (·) correction. Driving voltage for each color will be set to the above value by electrical circuit (driver IC) or resistance adjustment on the glass substrate by thin film layer structure. For this use, normal vertical-stripe color-filter arrangement will be very effective. The range of d·n is set to 350 nm to 450 nm for this invention.

Figure shows the typical T-V curve of normally black (NB) vertical aligned mode, where...