Display device with multiple row addressing

Abstract

A device for multiple row addressing is driven with pulse patterns based on sets of 8 (or more) orthogonal functions which have a less varying frequency content than pulse patterns based on a set of 8 Walsh functions.

1 . A display device comprising a liquid crystal between a first substrate provided with row or selection electrodes and a second substrate provided with column or data electrodes, in which overlapping parts of row and column electrodes define pixels, drive means for driving the column electrodes in conformity with an image to be displayed, and drive means for driving the row electrodes which, in the operating condition, sequentially supply groups of p row electrodes with p mutually orthogonal signals, characterized in that the mutually orthogonal signals are obtained from at least two types of orthogonal functions having four elementary units of time, within which four elementary units of time one pulse time each time has a polarity which is different from that of the other pulses.  
     
     
         2 . A display device as claimed in  claim 1 , characterized in that the orthogonal signals are obtained from orthogonal functions having four elementary units of time, within which four elementary units of time the pulse having a polarity which differs from that of the other pulses each time shifts by one elementary unit of time.  
     
     
         3 . A display device as claimed in  claim 1  or  2 , characterized in that the orthogonal signals are obtained from orthogonal functions having four elementary units of time which, viewed in a time sequence, are situated one after the other.  
     
     
         4 . A display device as claimed in  claim 3 , characterized in that at least two orthogonal signals have opposed DC contents.  
     
     
         5 . A display device as claimed in  claim 1  or  2 , characterized in that the orthogonal signals are obtained from orthogonal functions having four elementary units of time, in which the elementary units of the orthogonal functions are interwoven.  
     
     
         6 . A display device as claimed in  claim 1  or  2 , characterized in that p=4, and in that four orthogonal signals have identical DC contents and four are free from a DC voltage.  
     
     
         7 . A display device as claimed in  claim 6 , characterized in that the DC content of 2 orthogonal signals of the orthogonal signals having an identical DC content is opposed to that of the two other orthogonal signals.  
     
     
         8 . A display device as claimed in  claim 1  or  2 , characterized in that the drive means invert the orthogonal signals after each frame period.