液晶响应速度_1306

1、Fast Response Liquid CrystalsLCD TV :video rate (rise+ decay16ms)Color-sequential display (rise+ decayK11K22 for most nematicsElastic Constant Effectd2,but d n=constant 1/( n)2i.e. larger n for thinner cellBirefringent Effect n1.Bias Voltage effect:Vb VbVth: LC molecules are already tilted to a cert

2、ain degree by Vb. Thus, they quickly follow the incoming activation pulses.The higher the Vb, the faster the response time.2.Overdrive voltage rise pulse3.Undershoot driving scheme Shorten decay Voltage EffectVTimeV2V1V31 21 3V2OverdriveVoltage effectEx : 12 1 3 2 In PSNLC & PSCT displayPolymer

3、network alignment force due to the surface effectshorten decay Surface Stabilization d2Ex. d=4m, response time =30ms and how to achieve 16ms by using cell gap reduction? Cell Gap EffectOptical comparisonTNTN+SWVTN+NHMVAPVAAS-IPSAFFSViewing angle15/45/45/45 75/60/75/7530/85/85/85/8585/85/85/8585/85/8

4、5/85 85/85/85/8545/135 viewing60605085858585Transmittance-90%TN-80%TN85%TNColor shift0.020.020.02Response time (on+off)16ms5ms16ms1525ms2030msLC modes0.02 MVAIPS Ferroelectric LCD, e.g. Surface-Stabilized Ferroelectric LC (SSFLC)1.100s range2.BistableIdeal Candidate1. DC voltage effect: Accumulation

5、 of ions, and causes serious image sticking after prolonged operation.2. Thin cell:Limit manufaturing yieldSSFLC ProblemsResponse time of the IPS response time 需需d ,但但d 時時driving voltage會會 Response timedriving voltage 兩者兩者trade offResponse time and driving voltage can be optimized at the same timeRe

6、sponse time of Ultra FFS -Cell (OCB cell) OCB (Optically Compensated Bend) Self-compensation: Wide viewing angleFast switching: Eliminates backflowV=0 V=Vbias2V Von 5 VBend 1 stateThe director at the cell center aligns along the electric field, perpendicular to the cell surface (refer to last pape).

7、Thus, during switching, the applied voltage causes director distortion only in the vicinity of the cell surfaces, with the center remaining permanently along the filed.It means that, during switch, the two surface regions of an OCB cell are thus decoupled, it is this feature, together with the Elimination of backflow which utim