Display apparatus and driving device for displaying

Abstract

A display driver having a first mode where a number of colors to be displayed is smaller than a predetermined number and a second mode where a number of colors to be displayed is equal to or larger than the predetermined number. A generation circuit generates gray scale voltages having a plurality of levels for positive polarity and negative polarity. In the first mode, the generation circuit decreases a current flowing into an internal circuit which generates a gray scale voltage of an intermediate level other than two gray scale voltages of a lowest and a highest level, in comparison to a current flowing in the second mode. In the first mode, the selection circuit selects a gray scale voltage in accordance with the display data, from the two gray scale voltages of the lowest and the highest level gray scale voltage which are generated from the generation circuit.

1 . A display driver comprising:
 a generation circuit that generates gray scale voltages of a plurality of levels; and   a selection circuit that selects a gray scale voltage in accordance with a display data among the gray scale voltages generated by said generation circuit,   wherein said display driver has a first mode in which a number of colors to be displayed on a display panel is smaller than a predetermined number, and a second mode in which the number of colors to be displayed on the display panel is equal to or larger than the predetermined number,   wherein said generation circuit generates gray scale voltages having a plurality of levels for positive polarity and gray scale voltages having a plurality of levels for negative polarity,   wherein, in the first mode, said generation circuit decreases a current flowing into an internal circuit which generates a gray scale voltage of an intermediate level other than two gray scale voltages of a gray scale voltage of a lowest level and a gray scale voltage of a highest level among the gray scale voltages of the plurality of levels, in comparison to a current flowing in the second mode, and   wherein, in the first mode, said selection circuit selects a gray scale voltage in accordance with the display data, from the two gray scale voltages of the lowest level gray scale voltage and the highest level gray scale voltage which are generated from said generation circuit.   
     
     
         2 . The display driver according to  claim 1 , further comprising:
 a switching circuit that controls a resistance of a first resistor to divide a voltage between the lowest level gray scale voltage and the intermediate level gray scale voltage, and controls a resistance of a second resistor to divide a voltage between the highest level gray scale voltage and the intermediate level gray scale voltage with each other,   wherein, in the first mode, said switching circuit increases the resistance of the first resistor and the resistance of the second resistor.   
     
     
         3 . The display driver according to  claim 2 ,
 wherein said first resistor includes a third resistor and a fourth resistor having a lower resistance than a resistance of said third resistor, said third and fourth resistors being connected in parallel with each other,   wherein said second resistor includes a fifth resistor and a sixth resistor having a lower resistance than a resistance of said fifth resistor, said fifth and sixth resistors being connected in parallel with each other, and   wherein, in the first mode, said switching circuit selects the third resistor and the fifth.   
     
     
         4 . The display driver according to  claim 2 ,
 wherein both said first and second resistors are configured to be variable resistors, and   wherein, in the first mode, said switching circuit varies the resistance of said first and second resistors so as to increase the resistance of both said first and second resistors.   
     
     
         5 . The display driver according to  claim 1 ,
 wherein said generation circuit decreases the current flowing into said internal circuit using a resistor.   
     
     
         6 . The display driver according to  claim 1 ,
 wherein said generation circuit decreases the current flowing into said internal circuit by controlling the resistance of at least one of said first and second resistors in accordance with a selected mode between said first and second modes.   
     
     
         7 . The display driver according to  claim 6 ,
 wherein, in the second mode, said selection circuit selects a gray scale voltage in accordance with the display data from gray scale voltages of a plurality of levels including the lowest level gray scale voltage, the highest level gray scale voltage, and the intermediate level gray scale voltage, which are generated from said generation circuit, and   wherein said display driver includes a circuit to switch the current flowing into said internal circuit in accordance with the selected mode.   
     
     
         8 . The display driver according to  claim 1 ,
 wherein said internal circuit includes a dividing circuit, and   wherein said dividing circuit generates gray scale voltages of a plurality of levels including the highest level gray scale voltage, the lowest level gray scale voltage, and the intermediate level gay scale voltage, by dividing a reference voltage.   
     
     
         9 . The display driver according to  claim 1 ,
 wherein said dividing circuit is formed of a plurality of resistors.   
     
     
         10 . The display driver according to  claim 1 ,
 wherein information representing either of the first and second modes is inputted from an external device of said display driver.