Liquid crystal display using liquid crystal with bend alignment and driving method thereof

Abstract

When a transition voltage, which is higher than a display voltage for image display, is applied to liquid crystal, the liquid crystal can transition to a bend alignment. Therefore, by applying a transition voltage to liquid crystal prior to image display period only for a transition time which depends on a transition voltage so as to cause a bend transition in the liquid crystal, an OCB mode LCD with a high speed response can be obtained. An interval d between pixel regions is set to be less than, for example, a transition distance of 5 μm, so that a bend transition expands over inter-pixel regions to thereby achieve a bend transition all over the display region. In an active matrix type LCD, a electrical field is caused to be generated between a common electrode and data lines or gate lines disposed between pixel electrodes due to application of a transition voltage to the common electrode, thereby obtaining a bent transition over the entire surface of the display screen. Further, a pretilt angle set by an alignment film is determined to be 1.2° or more, such that a great number of transition sources for causing a bend transition are generated to thereby secure a high speed bend transition. Also, the pretilt angle is set to be 3° or less for accelerating a response time in a bend alignment.

1 - 35 . (canceled)  
   
   
       36 . A liquid crystal display device including liquid crystal between first and second substrates, comprising: 
 a plurality of first electrodes formed on a side of the first substrate facing the second substrate,    wherein    the liquid crystal has a splay alignment state and a bend alignment state,    a transition factor which triggers a bend transition from the splay alignment state to the bend alignment state is provided to the first electrodes, and the bend transition occurs with the transition factor as a starting point, and    the interval between adjacent electrodes among the plurality of first electrodes, or the width of a region where a conductive layer is not present between adjacent electrodes among the plurality of first electrodes, is 5 μm or less.    
   
   
       37 . The liquid crystal display according to  claim 36 , wherein 
 the interval is 2 μm or less.    
   
   
       38 . The liquid crystal display device according to  claim 36 , wherein 
 an alignment film is provided on a side of the first substrate facing the liquid crystal,    an alignment film is provided on a side of the second substrate facing the liquid crystal, and    rubbing treatment is performed on the alignment films in substantially the same direction.    
   
   
       39 . The liquid crystal display device according to  claim 36 , wherein 
 a second electrode is formed on a side of the second substrate facing the first substrate, and    the bend transition starts with the transition factor as a starting point by applying a transition voltage higher than a threshold voltage between the first and second electrodes.    
   
   
       40 . The liquid crystal display device according to  claim 39 , wherein 
 the transition voltage is a voltage for causing an alignment state of the liquid crystal to transit from the splay alignment state to the bend alignment state and is higher than a display voltage.    
   
   
       41 . The liquid crystal display device according to  claim 39 , wherein 
 the transition voltage is a voltage for causing an alignment state of the liquid crystal to transit from the splay alignment state to the bend alignment state, and    the state energy level of the liquid crystal in the bend alignment state is lower than that of the liquid crystal in the splay alignment state in a state wherein the transition voltage is applied to the liquid crystal.    
   
   
       42 . The liquid crystal display device according to  claim 36 , wherein 
 a display voltage is higher than a threshold voltage.    
   
   
       43 . The liquid crystal display device according to  claim 36 , further comprising an inter-pixel electrode disposed at the interval between adjacent electrodes among said plurality of pixel electrodes, wherein the distance between said inter-pixel electrode and the corresponding electrode among said plurality of pixel electrodes is 2 μm or less.  
   
   
       44 . The liquid crystal display device according to  claim 43 , wherein said plurality of pixel electrodes are insulated from said inter-pixel electrode.  
   
   
       45 . The liquid crystal display device according to  claim 36 , further comprising an inter-pixel electrode disposed at the interval between adjacent electrodes of said plurality of pixel electrodes, wherein said inter-pixel electrode and the corresponding electrode among said plurality of pixel electrodes have an overlapping region with an insulating layer interposed therebetween.  
   
   
       46 . The liquid crystal display device according to  claim 36 , wherein 
 a switching element is connected to each of said plurality of pixel electrodes, and    a selection line for selecting said switching element or a signal line for supplying a prescribed signal to each of said plurality of pixel electrodes is provided as an inter-pixel electrode at the interval between adjacent electrodes among said plurality of pixel electrodes.    
   
   
       47 . The liquid crystal display device according to  claim 46 , wherein said selection line or said signal line and the corresponding electrode among said plurality of pixel electrodes have an overlapping region with an insulating layer interposed therebetween.  
   
   
       48 . A liquid crystal display device including liquid crystal between first and second substrates, comprising: 
 a plurality of first electrodes formed on a side of the first substrate facing the second substrate; and    a second electrode formed on a side of the second substrate facing the first substrate,    wherein    the liquid crystal has a splay alignment state and a bend alignment state,    a transition factor which triggers a bend transition from the splay alignment state to the bend alignment state is provided to the first electrodes, and the bend transition occurs with the transition factor as a starting point,    the interval between adjacent electrodes among the plurality of first electrodes, or the width of a region where a conductive layer is not present between adjacent electrodes among the plurality of first electrodes, is 5 μm or less, and    a transition voltage for causing an alignment state of the liquid crystal to transit from the splay alignment state to the bend alignment state is applied between the first and second electrodes, the transition voltage being higher than a display voltage.    
   
   
       49 . The liquid crystal display device according to  claim 48 , wherein 
 the interval is 2 μm or less.    
   
   
       50 . The liquid crystal display device according to  claim 48 , wherein 
 an alignment film is provided on a side of the first substrate facing the liquid crystal,    an alignment film is provided on a side of the second substrate facing the liquid crystal, and    rubbing treatment is performed on the alignment films in substantially the same direction.    
   
   
       51 . The liquid crystal display device according to  claim 48 , wherein 
 the transition voltage is higher than a threshold voltage, and the bend transition starts with the transition factor as a starting point by applying the transition voltage between the first and second electrodes.    
   
   
       52 . The liquid crystal display device according to  claim 48 , wherein 
 the display voltage is higher than a threshold voltage.    
   
   
       53 . The liquid crystal display device according to  claim 48 , further comprising an inter-pixel electrode disposed at the interval between adjacent electrodes among said plurality of pixel electrodes, wherein the distance between said inter-pixel electrode and the corresponding electrode among said plurality of pixel electrodes is 2 μm or less.  
   
   
       54 . The liquid crystal display device according to  claim 53 , wherein said plurality of pixel electrodes are insulated from said inter-pixel electrode.  
   
   
       55 . The liquid crystal display device according to  claim 48 , further comprising an inter-pixel electrode disposed at the interval between adjacent electrodes of said plurality of pixel electrodes, wherein said inter-pixel electrode and the corresponding electrode among said plurality of pixel electrodes have an overlapping region with an insulating layer interposed therebetween.  
   
   
       56 . The liquid crystal display device according to  claim 48 , wherein 
 a switching element is connected to each of said plurality of pixel electrodes, and    a selection line for selecting said switching element or a signal line for supplying a prescribed signal to each of said plurality of pixel electrodes is provided as an inter-pixel electrode at the interval between adjacent electrodes among said plurality of pixel electrodes.    
   
   
       57 . The liquid crystal display device according to  claim 56 , wherein said selection line or said signal line and the corresponding electrode among said plurality of pixel electrodes have an overlapping region with an insulating layer interposed therebetween.  
   
   
       58 . A liquid crystal display device including liquid crystal between first and second substrates, comprising: 
 a plurality of first electrodes formed on a side of the first substrate facing the second substrate,    wherein    the liquid crystal has a splay alignment state and a bend alignment state,    each of the first electrodes is formed in an individual pattern for each pixel and is connected to a switching element provided for each pixel, and a transition factor which triggers a bend transition from the splay alignment state to the bend alignment state is provided to the first electrodes, and the bend transition occurs with the transition factor as a starting point, and    the interval between adjacent electrodes among the plurality of first electrodes, or the width of a region where a conductive layer is not present between adjacent electrodes among the plurality of first electrodes, is 5 μm or less.    
   
   
       59 . The liquid crystal display device according to  claim 58 , wherein 
 the interval is 2 μm or less.    
   
   
       60 . The liquid crystal display device according to  claim 58 , wherein 
 an alignment film is provided on a side of the first substrate facing the liquid crystal,    an alignment film is provided on a side of the second substrate facing the liquid crystal, and    rubbing treatment is performed on the alignment films in substantially the same direction.    
   
   
       61 . The liquid crystal display device according to  claim 58 , wherein 
 a second electrode is formed on a side of the second substrate facing the first substrate,    the bend transition starts with the transition factor as a starting point by applying a transition voltage higher than a threshold voltage between the first and second electrodes.    
   
   
       62 . The liquid crystal display device according to  claim 58 , wherein 
 a transition voltage for causing an alignment state of the liquid crystal to transit from the splay alignment state to the bend alignment state is higher than a display voltage.    
   
   
       63 . The liquid crystal display device according to  claim 58 , wherein 
 the state energy level of the liquid crystal in the bend alignment state is lower than that of the liquid crystal in the splay alignment state in a state wherein a transition voltage for causing an alignment state of the liquid crystal to transit from the splay alignment state to the bend alignment state is applied to the liquid crystal.    
   
   
       64 . The liquid crystal display device according to  claim 58 , wherein 
 a display voltage is higher than a threshold voltage.    
   
   
       65 . The liquid crystal display device according to  claim 58 , further comprising an inter-pixel electrode disposed at the interval between adjacent electrodes among said plurality of pixel electrodes, wherein the distance between said inter-pixel electrode and the corresponding electrode among said plurality of pixel electrodes is 2 μm or less.  
   
   
       66 . The liquid crystal display device according to  claim 65 , wherein said plurality of pixel electrodes are insulated from said inter-pixel electrode.  
   
   
       67 . The liquid crystal display device according to  claim 58 , further comprising an inter-pixel electrode disposed at the interval between adjacent electrodes of said plurality of pixel electrodes, wherein said inter-pixel electrode and the corresponding electrode among said plurality of pixel electrodes have an overlapping region with an insulating layer interposed therebetween.  
   
   
       68 . The liquid crystal display device according to  claim 58 , wherein 
 a switching element is connected to each of said plurality of pixel electrodes, and    a selection line for selecting said switching element or a signal line for supplying a prescribed signal to each of said plurality of pixel electrodes is provided as an inter-pixel electrode at the interval between adjacent electrodes among said plurality of pixel electrodes.    
   
   
       69 . The liquid crystal display device according to  claim 68 , wherein said selection line or said signal line and the corresponding electrode among said plurality of pixel electrodes have an overlapping region with an insulating layer interposed therebetween.