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 is 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 pixels arranged corresponding to crossing points of a plurality of data lines and a plurality of scan lines; and   a driver being connected with the data lines for outputting gray scale voltages corresponding to display data consisting of a plurality of bits to the pixels via the data lines;   wherein the driver outputs the gray scale voltages having polarity different from each other to an adjacent two data lines;   wherein an adjacent two pixels on the display panel connected to the adjacent two data lines have polarity different from each other; and   wherein the driver makes outputs from the driver to the data lines to be in a high impedance state before the gray scale voltages are output to the pixels.   
     
     
       18. The display device according to claim 17,
 wherein the driver includes a switch, provided for each data line and arranged between the driver and each data line; and   wherein the driver makes the outputs from the driver to the data lines to be in the high impedance state by turning the outputs OFF by the switch.   
     
     
       19. The display device according to claim 17,
 wherein, when the driver make the outputs from the driver to the data lines to be in the high impedance state, the outputs from the driver to the data lines are connected to each other.   
     
     
       20. The display device according to claim 19,
 wherein the driver includes a switch for connecting and disconnecting the outputs from the driver to the data lines with each other.   
     
     
       21. The display device according to claim 17,
 wherein the driver comprises:   a first amplifier for outputting the gray scale voltage having a positive polarity corresponding to the display data to one of the adjacent two data lines;   a second amplifier for outputting the gray scale voltage having a negative polarity corresponding to the display data to an other of the adjacent two data lines; and   a selector for switching an output destination of the positive polarity gray scale voltage output from the first amplifier between the one of the adjacent two data lines and the other of the adjacent two data lines while switching an output destination of the negative polarity gray scale voltage output from the second amplifier between the other of the adjacent two data lines and the one of the adjacent two data lines.   
     
     
       22. The display device according to claim 17,
 wherein the driver precharges the outputs from the driver to the data lines to a predetermined voltage level after making the outputs from the driver to the data lines to be in the high impedance state and before the gray scale voltages are output to the pixel.   
     
     
       23. The display device according to claim 17,
 wherein the adjacent two pixels on the display panel connected to an adjacent two scan lines have polarity different from each other.   
     
     
       24. A display device comprising:
 a display panel having a plurality of pixels; and   a driver, having output terminals (Y1, Y2) provided for data lines connected to the pixels, for outputting gray scale voltages corresponding to display data for each pixel consisting of a plurality of bits to the pixel from the output terminal via the data line;   wherein a polarity of the gray scale voltage output from the output terminal (Y1) at an odd-numbered position is different from a polarity of the gray scale voltage output from the output terminal (Y2) at an even-numbered position,   wherein the polarity of the voltage at the pixel connected to the odd-numbered output terminal (Y1) via the data line is different from the polarity of the voltage at the pixel connected to the even-numbered output terminal (Y2) via the data line; and   wherein the driver makes the outputs from the output terminals to be in the high impedance state before the gray scale voltages are output to the pixels.   
     
     
       25. The display device according to claim 24,
 wherein the driver includes a switch at each output terminal, provided for each output terminal; and   wherein the driver makes the outputs from the output terminals to be in the high impedance state by turning the output OFF by the switch.   
     
     
       26. The display device according to claim 24,
 wherein, when the driver makes the outputs from the output terminals to be in the high impedance state, the outputs from the output terminals are connected to each other.   
     
     
       27. The display device according to claim 26,
 wherein the driver includes a switch for connecting and disconnecting the outputs from the driver to the data lines with each other.   
     
     
       28. The display device according to claim 24,
 wherein the driver further comprises:   a first amplifier for outputting the gray scale voltage having a positive polarity corresponding to the display data to the odd-numbered output terminal;   a second amplifier for outputting the gray scale voltage having a negative polarity corresponding to the display data to the even-numbered output terminal; and   a selector for switching an output destination of the positive polarity gray scale voltage output from the first amplifier between the odd-numbered output terminal and the even-numbered output terminal while switching output an destination of the negative polarity gray scale voltage output from the second amplifier between the even-numbered output terminal and the odd-numbered output terminal.   
     
     
       29. The display device according to claim 24,
 wherein the driver precharges the outputs from the output terminals to a predetermined voltage level after making the outputs from the output terminals to be in the high impedance state and before the gray scale voltages are output to the pixels.   
     
     
       30. A display device comprising:
 a display panel having a plurality of pixels; and   a driver, having output terminals (Y1, Y2) provided for data lines connected to the pixels, for outputting gray scale voltage corresponding to display data consisting of a plurality of bits to the pixel from the output terminal via the data line;   wherein the driver makes the outputs from the output terminals to be in a high impedance state before the gray scale voltages are output to the pixels.   
     
     
       31. The display device according to claim 30,
 wherein the driver includes a switch at each output terminal, provided for each output terminal, for making the output from the output terminal ON or OFF, and   the driver makes the outputs from the output terminals to be in a high impedance state by turning the outputs OFF by the switch.   
     
     
       32. The display device according to claim 30,
 wherein, when the driver makes the outputs from the output terminals to be in the high impedance state, the outputs from the output terminals are connected to each other.   
     
     
       33. The display device according to claim 32,
 wherein the driver includes a switch for connecting and disconnecting the outputs from the driver to the data lines with each other.   
     
     
       34. The display device according to claim 30,
 wherein the driver precharges the outputs from the output terminals to a predetermined voltage level after making the outputs from the output terminals to be in the high impedance state and before the gray scale voltages are output to the pixels.   
     
     
       35. A display device comprising:
 a display panel having a plurality of pixels arranged corresponding to crossing points of a plurality of data lines and a plurality of scan lines; and   a driver, connected with the data lines, for outputting gray scale voltages corresponding to display data consisting of a plurality bits to the pixels via the data lines;   wherein the driver outputs the gray scale voltages having a polarity different from each other to an adjacent two data lines;   wherein the voltages at an adjacent two pixels on the display panel connected to the adjacent two data lines have a polarity different from each other; and   wherein the driver connects the outputs from the driver to the data lines with each other before the gray scale voltages are output to the pixels.   
     
     
       36. The display device according to claim 35,
 wherein the driver includes a switch for connecting and disconnecting the outputs from the driver to the data lines with each other.   
     
     
       37. The display device according to claim 35,
 wherein the driver comprises:   a first amplifier for outputting the gray scale voltage having a positive polarity corresponding to the display data to one of the adjacent two data lines;   a second amplifier for outputting the gray scale voltage having a negative polarity corresponding to the display data to an other of the adjacent two data lines; and   a selector for switching an output destination of the positive polarity gray scale voltage output from the first amplifier between the one of the adjacent two data lines and the other of the adjacent two data lines while switching an output destination of the negative polarity gray scale voltage output from the second amplifier between the other of the adjacent two data lines and the one of the adjacent two data lines.   
     
     
       38. The display device according to claim 35,
 wherein the driver precharges the outputs from the driver to the data lines to a predetermined voltage level after connecting the outputs from the driver to the data lines to each other and before the gray scale voltages are output to the pixels.   
     
     
       39. A display device comprising:
 a display panel having a plurality of pixels arranged corresponding to crossing points of a plurality of data lines and a plurality of scan lines; and   a driver, connected with the data lines, for outputting gray scale voltages corresponding to display data consisting of a plurality bits to the pixels via the data lines;   wherein the driver outputs the gray scale voltages having a polarity different from each other to an adjacent two data lines;   wherein the voltages at an adjacent two pixels on the display panel connected to the adjacent two data lines have a polarity different from each other, and   wherein the driver provides an equalizing period during which the gray scale voltages are not output to the pixels just before the gray scale voltages are output to the pixels.   
     
     
       40. The display device according to claim 39,
 wherein the driver makes the outputs from the driver to the pixels to be in a high impedance state during the equalizing period.   
     
     
       41. The display device according to claim 40,
 wherein the driver includes a switch, provided for each output from the driver to the data line, for making the outputs from the driver to the data line ON or OFF, and   wherein the driver makes the outputs from the driver to the data lines to be in a high impedance state by turning the outputs OFF by the switch.   
     
     
       42. The display device according to claim 40,
 wherein, when the driver makes the outputs from the driver to the data lines to be in the high impedance state, the outputs from the driver to the data lines are connected to each other.   
     
     
       43. The display device according to claim 42,
 wherein the driver includes a switch for connecting and disconnecting the outputs from the driver to the data lines with each other.   
     
     
       44. The display device according to claim 39,
 wherein the driver further comprises:   a first amplifier for outputting the gray scale voltage having a positive polarity corresponding to the display data to one of the adjacent two data lines;   a second amplifier for outputting the gray scale voltage having a negative polarity corresponding to the display data to an other of the adjacent two data lines; and   a selector for switching an output destination of the positive polarity gray scale voltage output from the first amplifier between the one of the adjacent two data lines and the other of the adjacent two data lines while switching an output destination of the negative polarity gray scale voltage output from the second amplifier between the other of the adjacent two data lines and the one of the adjacent two data lines.   
     
     
       45. The display device according to claim 39,
 wherein the driver precharges the outputs from the driver to the data lines to a predetermined voltage level after the equalizing period and before the gray scale voltages are output to the pixels.