Liquid crystal display device

Abstract

A liquid crystal (LC) display device includes a LC panel and a driving circuit. The LC panel exhibits, in its voltage-transmittance characteristics, an extreme transmittance at a voltage equal to or lower than a lowest gray-level voltage. The driving circuit supplies to the LC panel a predetermined driving voltage overshooting a gray-level voltage corresponding to an input image signal of a current vertical period, according to a combination of an input image signal of an immediately preceding vertical period and the input image signal of the current vertical period.

What is claimed is:  
     
         1 . A liquid crystal display device, comprising: 
 a liquid crystal panel including a liquid crystal layer and an electrode for applying a voltage to the liquid crystal layer; and    a driving circuit for supplying a driving voltage to the liquid crystal panel, wherein    the liquid crystal panel exhibits, in its voltage-transmittance characteristics, an extreme transmittance at a voltage equal to or lower than a lowest gray-level voltage, and    the driving circuit supplies to the liquid crystal panel a predetermined driving voltage overshooting a gray-level voltage corresponding to an input image signal of a current vertical period, according to a combination of an input image signal of an immediately preceding vertical period and the input image signal of the current vertical period.    
     
     
         2 . The liquid crystal display device according to    claim 1   , wherein a difference in retardation of the liquid crystal panel between a state where a voltage is not applied and a state where a highest gray-level voltage is applied is 300 nm or more.  
     
     
         3 . The liquid crystal display device according to claim  1 , wherein the liquid crystal panel is a transmission-type liquid crystal panel, and the extreme transmittance provides a maximum transmittance.  
     
     
         4 . The liquid crystal display device according to    claim 1   , wherein a single vertical period of the input image signal corresponds to a single frame, at least two fields of the driving voltage correspond to a single frame of the input image signal, and the driving circuit supplies, at least in a first field of the driving voltage, a driving voltage overshooting a gray-level voltage corresponding to an input image signal of a current field to the liquid crystal panel.  
     
     
         5 . The liquid crystal display device according to    claim 1   , wherein the liquid crystal layer is a homogeneous-orientation liquid crystal layer.  
     
     
         6 . The liquid crystal display device according to    claim 1   , wherein the liquid crystal panel further includes a phase compensator, three principal refractive indices na, nb and nc of an index ellipsoid of the phase compensator have a relation of na=nb>nc, and the phase compensator is arranged so as to cancel at least a part of retardation of the liquid crystal layer.  
     
     
         7 . A liquid crystal display device, comprising: 
 a liquid crystal panel including a plurality of picture-element capacitors arranged in a matrix, and thin film transistors respectively electrically connected to the plurality of picture-element capacitors; and    a driving circuit for supplying a driving voltage to the liquid crystal panel, wherein    the liquid crystal display device updates display every vertical period by rendering the plurality of picture-element capacitors in a charged state corresponding to the input image signal,    each of the plurality of picture-element capacitors includes a liquid crystal capacitor formed from a corresponding picture-element electrode, a counter electrode and a liquid crystal layer provided between the picture-element electrode and the counter electrode, and a storage capacitor electrically connected in parallel with the liquid crystal capacitor, a capacitance ratio of the storage capacitor to the liquid crystal capacitor being 1 or more, and    the picture-element capacitor retains 90% or more of a charging voltage over a single vertical period, when at least a highest gray-level voltage is applied.    
     
     
         8 . The liquid crystal display device according to claim  7 , wherein the driving circuit supplies to the liquid crystal panel a predetermined driving voltage overshooting a gray-level voltage corresponding to an input image signal of a current vertical period, according to a combination of an input image signal of an immediately preceding vertical period and the input image signal of the current vertical period.  
     
     
         9 . The liquid crystal display device according to    claim 8   , wherein, for the input image signal of every gray level, the driving circuit supplies to the liquid crystal panel the driving voltage overshooting the gray-level voltage corresponding to the input image signal of the current vertical period.  
     
     
         10 . The liquid crystal display device according to    claim 7   , wherein the liquid crystal layer of the liquid crystal panel includes a nematic liquid crystal material having a positive dielectric anisotropy, the liquid crystal layer included in each of the plurality of picture-element capacitors includes first and second regions having different orientation directions, and 
 the liquid crystal panel further includes a pair of polarizers arranged so as to orthogonally cross each other with the liquid crystal layer interposed therebetween, and a phase compensator for compensating for a refractive index anisotropy of the liquid crystal layer in a black display state.    
     
     
         11 . The liquid crystal display device according to    claim 7   , wherein the liquid crystal layer is a homogeneous-orientation liquid crystal layer.  
     
     
         12 . The liquid crystal display device according to    claim 11   , wherein the liquid crystal panel further includes a phase compensator, three principal refractive indices na, nb and nc of an index ellipsoid of the phase compensator have a relation of na=nb>nc, and the phase compensator is arranged so as to cancel at least a part of retardation of the liquid crystal layer.