公开(公告)号：JPH04194896A

公开(公告)日：1992-07-14

申请号：JP32343290

申请日：1990-11-28

Applicant: IBM

Inventor： TERASAWA YOSHIHIRO ,  YAMAGUCHI HIDEFUMI

IPC: G02F1/133 ,  G09G3/20 ,  G09G3/36

Abstract: PURPOSE: To reduce the number of analog switches, the number of liquid crystal driving power supplies and the number of inputs of a driver by simultaneously impressing two levels of voltage through two analog switches capable of simultaneously turning on liquid crystal driving voltage. CONSTITUTION: Since D0=0 is set up when input data are (D0=0, D1=1 and D2=1), a selector 11 turns on only an analog switch SW3 and impresses driving voltage V3 to a data line. Since D1=1 and D2=1 are set up when input data are (C0=0, D1=0 and D2=1), the selector 11 turns on a switch SW of a succeeding level simultaneously with the ON of the switch SW2 and impresses R3.V2+ R2.V3/R2+R3 to the data line. In the case of 8-gradation level display, the number of power supplies and the number of analog switches can be respectively reduced from conventional eight units to five units, and in the case of K gradation level display, the number of power supplies and the number of analog switches are respectively reduced to (K/2+1) units.