Liquid crystal driver and liquid crystal display device using the same

Abstract

A liquid crystal driver includes a voltage generator for generating gray scale voltages on the basis of reference voltages, and an output device for selecting one gray scale voltage from the generated gray scale voltages in accordance with display data, for applying inversion/non-inversion control to the selected gray scale voltage with respect to an inversion reference voltage on the basis of the selected gray scale voltage, an AC switching signal and the inversion reference voltage, and for outputting different liquid crystal supply voltages for one and the same display data to a liquid crystal panel.

1. A liquid crystal driver comprising:
 a plurality of output terminals for outputting display voltages to be applied to a liquid crystal display device;  
 an input terminal for receiving display data corresponding to said plurality of output terminals; and  
 output means for converting said input display data into said output display voltages;  
 wherein said output means selects a display voltage level corresponding to one input display data and simultaneously generates two different display voltages from the selected display voltage level so that either one of said two different display voltages can be selected as an output display voltage for each of said output terminals.  
 
     
     
       2. A liquid crystal driver according to  claim 1 , wherein said two different display voltages are a display voltage higher than a reference voltage and a display voltage lower than the reference voltage. 
     
     
       3. A liquid crystal driver according to  claim 1 , wherein a display voltage to be selected from said two different display voltages is determined on the basis of a signal received from outside the liquid crystal driver. 
     
     
       4. A liquid crystal driver according to  claim 1 , wherein a display voltage to be selected from said two different display voltages is determined on the basis of input information received together with the display data. 
     
     
       5. A liquid crystal driver according to  claim 2 , wherein said two different display voltages are inverted relative to each other so as to be symmetric relative to each other with respect to said reference voltage. 
     
     
       6. A liquid crystal driver according to  claim 2 , wherein one of said two different display voltages is shifted by an amount corresponding to said reference voltage compared with another one of said two different display voltages. 
     
     
       7. A liquid crystal driver according to  claim 1 , wherein said output means includes level-shift means for shifting said output display voltages with respect to said output terminals. 
     
     
       8. A liquid crystal driver according to  claim 1 , wherein a signal obtained by periodically switching between said two different display voltages is outputted at each of said output terminals. 
     
     
       9. A liquid crystal driver according to  claim 2 , wherein during a certain period, a display voltage higher than said reference voltage and a display voltage lower than said reference voltage are respectively supplied to two arbitrary adjacent output terminals. 
     
     
       10. A liquid crystal driver according to  claim 1 , wherein the liquid crystal driver is constituted by one LSI. 
     
     
       11. A liquid crystal display device comprising:
 a liquid crystal panel including pixel portions which are arranged at positions of intersections of a plurality of data lines and a plurality of scanning lines in the form of a matrix;  
 a scanning driver for successively supplying voltages to said plurality of scanning lines; and  
 a liquid crystal driver as defined in  claim 1  for receiving display data and supplying display voltages to said plurality of data lines in correspondence to said display data.  
 
     
     
       12. A liquid crystal display device according to  claim 11 , wherein said scanning driver includes a level-shift circuit for receiving an input signal of a same level as a level of a signal received by said liquid crystal driver, and shifting the level of said input signal to a level allowed to be used in said scanning driver. 
     
     
       13. A liquid crystal driver according to  claim 1 , wherein said output means includes two different-characteristic output amplification circuits for two adjacent output terminals so that said two different display voltages can be selected and outputted by switching connections between two gray scale voltage data generated on the basis of input display data corresponding to said two output terminals and input terminals of said two output amplification circuits, and connections between output terminals of said two output amplification circuits and said two output terminals on the basis of an external signal. 
     
     
       14. A liquid crystal driver according to  claim 1 , wherein said output means includes a combination of a non-inversion output amplification circuit and an inversion output amplification circuit for two adjacent output terminals so that said two different display voltages can be alternately outputted by alternately switching connections between two gray scale voltage data generated on the basis of input display data corresponding to said two output terminals and input terminals of said combination of output amplification circuits, and connections between output terminals of said combination of output amplification circuits and said two output terminals on the basis of an external signal. 
     
     
       15. A liquid crystal driver according to  claim 9 , wherein said output means includes connection means which connects together two adjacent output terminals outputting a display voltage higher than said reference voltage and a display voltage lower than said reference voltage so that said two adjacent output terminals are connected together during a predetermined period before output display voltages of the two adjacent output terminals are switched. 
     
     
       16. A method of applying display voltages to a liquid crystal display device, the method comprising the steps of:
 receiving display data corresponding to output terminals which output display voltages;  
 generating gray scale display voltage levels on the basis of reference voltages;  
 selecting one of the gray scale display voltage levels for each output terminal in accordance with said display data, the selected gray scale display voltage level being a first display voltage for the output terminal;  
 supplying an AC switching signal and an inversion reference voltage, said AC switching signal having a polarity which is periodically inverted;  
 inverting said selected gray scale voltage level with respect to said inversion reference voltage to generate an inverted selected gray scale display voltage level, the inverted selected gray scale display voltage level being a second display voltage for the output terminal, the second display voltage being different from the first display voltage, the first display voltage and the second display voltage being available simultaneously;  
 selecting one of the first display voltage and the second display voltage in accordance with the AC switching signal as an output display voltage for the output terminal; and  
 outputting the output display voltage from the output terminal.  
 
     
     
       17. A display device comprising:
   a display panel having a plurality of columns and a plurality of rows for displaying an image in accordance with display data; and        a data driver coupled to said display panel, said data driver being arranged on a single side of said display panel, said data driver having an input terminal and a plurality of output terminals, each of said output terminals corresponding to each of at least a part of said columns of said display panel, said data driver including:      a generator for simultaneously generating a plurality of display voltages, said display voltages including a set of positive and negative polarity gray scale voltages corresponding to each of gray scales,        a selector for selecting one of said plurality of display voltages according to each of said display data, and        an output circuit for outputting said selected one of said display voltages to said each of said output terminals;          wherein selected display voltages which correspond to adjacent two of said output terminals have different polarity from each other.     
     
     
       18. A display device according to  claim 17 , wherein the data driver is constituted by at least one integrated circuit. 
     
     
       19. A display device according to  claim 17 , wherein the gray scales are  64  gray scales. 
     
     
       20. A display device according to  claim 17 , wherein the generator includes:
   a plurality of reference voltage terminals for receiving a plurality of reference voltages; and        a converter coupled to the plurality of reference voltage terminals for outputting the plurality of display voltages;        wherein a number of the display voltages is larger than a number of the reference voltages.     
     
     
       21. A data driver for coupling to a display panel, said display panel having a plurality of columns and a plurality of rows for displaying an image in accordance with display data, said data driver being arranged on a single side of said display panel, said data driver having an input terminal and a plurality of output terminals, each of said output terminals corresponding to each of at least a part of said columns of said display panel, said data driver comprising:
   a generator for simultaneously generating a plurality of display voltages, said display voltages including a set of positive and negative polarity gray scale voltages corresponding to each of gray scales;        a selector for selecting one of said plurality of display voltages according to each of said display data; and        an output circuit for outputting said selected one of said display voltages to said each of said output terminals;        wherein selected display voltages which correspond to adjacent two of said output terminals have different polarity from each other.     
     
     
       22. A data driver according to  claim 21 , wherein the data driver is constituted by at least one integrated circuit. 
     
     
       23. A data driver according to  claim 21 , wherein the gray scales are  64  gray scales. 
     
     
       24. A data driver according to  claim 21 , wherein the generator includes:
   a plurality of reference voltage terminals for receiving a plurality of reference voltages; and        a converter coupled to the plurality of reference voltage terminals for outputting the plurality of display voltages;        wherein a number of the display voltages is larger than a number of the reference voltages.     
     
     
       25. A method of applying display voltages to a display panel, said display panel having a plurality of columns and a plurality of rows for displaying an image in accordance with display data, said method comprising the steps of:
   providing an input terminal and a plurality of output terminals, said output terminals being coupled to said display panel, said output terminals being arranged on a single side of said display panel, each of said output terminals corresponding to each of at least a part of said columns of said display panel;        simultaneously generating a plurality of display voltages, said display voltages including a set of positive and negative polarity gray scale voltages corresponding to each of gray scales;        selecting one of said plurality of display voltages according to each of said display data; and        outputting said selected one of said display voltages to said each of said output terminals, thereby applying said selected one of said display voltages to said display panel;        wherein selected display voltages which correspond to adjacent two of said output terminals have different polarity from each other.     
     
     
       26. A method according to  claim 25 , further comprising the step of providing at least one integrated circuit which includes the input terminal and the output terminal, and which performs the generating, selecting, and outputting steps. 
     
     
       27. A method according to  claim 25 , wherein the gray scales are  64  gray scales. 
     
     
       28. A method according to  claim 25 , wherein the generating step includes the steps of:
   providing a plurality of reference voltage terminals for receiving a plurality of reference voltages; and        converting the plurality of reference voltages received by the plurality of reference voltage terminals to the plurality of display voltages;        wherein a number of the display voltages is larger than a number of the reference voltages.