Patent ID: 6697060
Filing Date: 2004-02-24
Classification: G09G

Abstract:
A power supply circuit for generating potentials used to drive a liquid crystal, the power supply circuit comprising:a first to fourth switches connected in series between a high potential line and a low potential line; a switch drive circuit which drives the first to fourth switches so that the period of time in which the first and third switches are on and the period of time in which the second and fourth switches are on alternate; and a plurality of capacitors of which connection state is switched alternately between series and parallel connections by a switching operation of the switch drive circuit, wherein a potential between the second and third switches converges to a middle potential between potentials of the high and low potential lines by a switching operation of the switch drive circuit, when first to third midpoints are midpoints of switch-intervals formed by being divided by the first to fourth switches, the power supply circuit includes: a first capacitor connected between the high potential line and the second midpoint; a second capacitor connected between the second midpoint and the low potential line; and a third capacitor connected between the first midpoint and the third midpoint, and the first and second capacitors are replaced by capacitors of a liquid crystal layer formed by supplying potentials of the high and low potential lines and the second midpoint to the liquid crystal layer.