US 7,030,865 B2 · Operational amplifier circuit, driving circuit and driving method

Abstract

In a period T1 (positive polarity) in which a voltage level of a counter electrode VCOM becomes VC1, a data line is driven using P-type operational amplifier OP1 having P-type driving transistor, while in a period T2 (negative polarity) in which VCOM becomes VC2, the data line is driven using N-type operational amplifier OP2 having N-type driving transistor. An output of a selection circuit for the operational amplifiers OP1, OP2 is set to the high impedance state when VCOM is changed over. At the time of driving the operational amplifier OP1, a current which flows in current sources of the operational amplifier OP2 is cut off, while at the time of driving the operational amplifier OP2, a current which flows in current sources of the operational amplifier OP1 is cut off. In the period before the operational amplifiers OP1, OP2 are driven, the driving transistors of the operational amplifiers OP1, OP2 are turned off. The voltage level of the data line can be changed before driving by positively utilizing the parasitic capacitance between the counter electrode and data line.

Claims18

Dependent claims

An operational amplifier circuit which drives each of data lines of an electro-optical device having scan lines, the data lines and pixel electrodes which are specified by the scan lines and the data lines, the operational amplifier circuit comprising:

a first operational amplifier which drives a data line in a first period in which a voltage level of a counter electrode facing a pixel electrode with an electro-optical material interposed therebetween becomes a first voltage level;
a second operational amplifier which drives the data line in a second period in which the voltage level of the counter electrode becomes a second voltage level;
and
a selection circuit which selects an output of the first operational amplifier and connects the output to the data line in the first period in which the voltage level of the counter electrode becomes the first voltage level, and selects an output of the second operational amplifier and connects the output to the data line in the second period in which the voltage level of the counter electrode becomes the second voltage level,
wherein an output of the selection circuit is set to a high impedance state in a given period including a transition timing between the first and second periods.

2 more elements

Dependencies are inferred from the claim text.

Operational amplifier circuit, driving circuit and driving method

Life of this patent

Operational amplifier circuit, driving circuit and driving method

Life of this patent

Abstract

Claims18