Vertical alignment type liquid crystal display apparatus having improved display uniformity

Abstract

A mono domain vertical alignment type liquid crystal display apparatus to be multiplex driven is provided whose display uniformity at a large pretilt angle (near 90°) is improved. Waveform A is applied to a liquid crystal cell of a mono domain vertical alignment type, the waveform A having a duty not lower than 4 and a frame frequency of f. The frame frequency f is determined from a pretilt angle θp, and is a frequency not lower than 60 Hz at a pretilt angle of 88.5°≦θp<89.6° or a frequency not lower than [120×(θp−89.6)+60] Hz at a pretilt angle of 89.6°≦θp≦89.9°.

What are claimed are: 
     
       1. A liquid crystal display apparatus comprising:
 a liquid crystal cell of a mono domain vertical alignment type; and 
 a driver apparatus which applies a multiplex driving waveform to said liquid crystal cell, 
 wherein said liquid crystal cell of the mono domain vertical alignment type comprises:
 first and second substrates disposed facing each other; 
 a liquid crystal layer sandwiched between said first and second substrates; and 
 a first vertical alignment film formed above said first substrate on a side of said liquid crystal layer, and a second vertical alignment film formed below said second substrate on a side of said liquid crystal layer, wherein at least one of said first and second vertical alignment films has an aligning texture which gives liquid crystal molecules in said liquid crystal layer a pretilt angle θp in a range between 88.5° and 89.9° and mono domain alignment during no voltage application; 
 
 wherein said driver apparatus applies, to said liquid crystal cell, a multiplex driving waveform having a frame frequency f, as a function of a duty number and said pretilt angle θp, said duty number being an inverse of a duty ratio; and 
 wherein:
 said frame frequency f is not lower than F Hz at a pretilt angle of 88.5° ≦θp <Θ° and not lower than [A 1 ×(θp−Θ)+F] Hz at a pretilt angle of Θ°≦θp≦89.9°, when said duty number is not lower than 4 and not higher than 31, 
 said frame frequency f is not lower than F Hz at a pretilt angle of 88.5°≦θp<Θ° and not lower than [A 2  ×(θp−Θ)+F] Hz at a pretilt angle of Θ°≦θp≦89.9°, when said duty number is not lower than 32 and not higher than D, and 
 said frame frequency f is not lower than F Hz at a pretilt angle of 88.5°≦θp≦89.9°, when said duty number is not lower than (D+1); and 
 
 wherein said frequency F is not lower than 60 Hz, said angle Θ is not higher than 89.6°, said gradient A 1  is not lower than 120, said gradient A 2  is not lower than 60, and said number D is not lower than 63. 
 
     
     
       2. The liquid crystal display apparatus according to  claim 1 , wherein said driving waveform is a multiplex driving waveform with polarity reversal. 
     
     
       3. The liquid crystal display apparatus according to  claim 1 , wherein said driving waveform is a waveform A, said frequency F is 60 Hz, said angle Θ is 89.6°, said gradient A 1  is 120, said gradient A 2  is 60, and said number D is 119. 
     
     
       4. The liquid crystal display apparatus according to  claim 1 , wherein said driving waveform is a waveform B, said frequency F is 100 Hz, said angle Θ is 89.0°, said gradient A 1  is 312, said gradient A 2  is 160, and said number D is 119. 
     
     
       5. The liquid crystal display apparatus according to  claim 1 , wherein said driving waveform is a waveform C having a polarity reversal line number M that is not smaller than 1 and not larger than half of said duty number of said waveform C, and
 wherein said frequency F is 60 Hz, said angle Θ is 89.2°, said gradient A 1  is 216, said gradient A 2  is 110, and said number D is 119. 
 
     
     
       6. The liquid crystal display apparatus according to  claim 1 , wherein said driving waveform is a waveform MLS, said frequency F is 60 Hz, said angle Θ is 89.3°, said gradient A 1  is 150, said gradient A 2  is 75, said number D is 63, a simultaneous line select number N of said waveform MLS is not smaller than 2 and not larger than 4 when said duty number is not higher than 63, and said simultaneous line select number N is 4 when said duty number is not lower than 64. 
     
     
       7. The liquid crystal display apparatus according to  claim 1 , wherein said first and second vertical alignment films have aligning textures formed by antiparallel rubbing. 
     
     
       8. The liquid crystal display apparatus according to claim 1, wherein the liquid crystal display apparatus is a segment display type liquid crystal display apparatus.