from external are respectively inputted to the digital analog converter dac in the u03b3 voltage generator 50 switching circuits 51 and 52 has either of power source voltage vdd or the ground voltage vss complementarily connected to and n 1 resistors r 0 u02dc rn are serially connected in between n resistively divided u03b3 voltage values are extracted from intermediate connecting nodes between the serially connected resistors the u03b3 voltage values are provided to the digital analog converter dac in a bus and are digitized by the dac according to the selecting data from the data latch and then are provided to the source lines the two switching circuits 51 and 52 can invert the polarity of the voltages applied to the resistor row by switch to the respective opposite sides of the switching circuits 51 and 52 which causes the inversion of the driving polarity of the liquid crystals the u03b3 voltage generator 50 is constituted by the serially connected resistors and the intermediate connecting nodes between the serially connected resistors the u03b3 voltage value obtained therefrom is fixed fig3 is a circuit diagram of the digital analog converter circuit of the present invention in which the structures providing the applied voltages to the liquid crystal elements in fig2 are mostly replaced a modulating device such as a modulator 110 supplied with control signals ctrl generated from a control unit 100 outputs two frequency signals fa and fb referring to a storage device such as a u03b3 look up table lut 120 which stores the u03b3 value of the desired u03b3 curve according to the value of the control signal ctrl these frequency signals fa and fb are provided to the two switch capacitors.