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Transflective type LCD device having excellent image quality

  • US 9,093,035 B2
  • Filed: 05/17/2013
  • Issued: 07/28/2015
  • Est. Priority Date: 01/10/2007
  • Status: Active Grant
First Claim
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1. A transflective liquid crystal display (LCD) device comprising an LCD panel including an array of pixels each having a reflective area and a transmissive area in a liquid crystal (LC) layer, and a drive circuit for driving said reflective area and said transmissive area of said LC layer by using an inverting drive scheme, whereinthe drive circuit generates a first common electrode signal periodically inverted in a polarity thereof at a predetermined amplitude, and generates a second common electrode signal having a phase opposite to a phase of the first common electrode signal,the drive circuit drives an LC of one of the reflective area and the transmissive area based on a common pixel signal that is common to the reflective area and the transmissive area, and based on the first common electrode signal,a voltage characteristic, Vr(K)−

  • Vr, of the reflective area is substantially equivalent to a second voltage characteristic, Vt−

    Vt(K), of the transmissive area when a first drive voltage Vr and a second drive voltage Vt change by a voltage Δ

    V, the Vr and Vt are drive voltages of the LC in the reflective area and the transmissive area, respectively,Vr(K) is a dark-state setup voltage in the reflective area, Vt(K) is a dark-state setup voltage in the transmissive area, R is a reflectance, and T is a transmittance,The dark-state setup voltage is selected according to a comb teeth clearance,a first common electrode and a first pixel electrode in said reflective area are comb teeth electrodes and are disposed in such a manner that teeth of said first common electrode and teeth of said first pixel electrode are alternately aligned with a clearance Lr in an alignment direction,a second common electrode and a second pixel electrode in said transmissive area are comb teeth electrodes and are disposed in such a manner that teeth of the second common electrode and teeth of the second pixel electrode are alternately aligned with a clearance Lt in an alignment direction thereof, andLt is greater than Lr,wherein α

    (R) is 25°

    where α

    (R) is an angle formed between a direction in which said teeth of said first common electrode and said first pixel electrode in said reflective area extend and a rubbing direction for said LC,wherein α

    (T) ranges from 15°

    to 25°

    where α

    (T) is an angle formed between a direction in which said teeth of said second common electrode and said second pixel electrode in said transmissive area extend and said rubbing direction for said LC.

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