Patent ID: 7764257
Filing Date: 2010-07-27
Classification: G09G

Abstract:
1. A gate voltage controlling apparatus for a liquid crystal display, comprising: a power supply that generates at least two gate voltages having different voltage levels; a gate driver that generates a scanning pulse that selects a display line using the at least two gate voltages having different voltage levels; and a gate voltage control means that supplies the gate voltages to the gate driver in a sequence of a lower voltage followed by a higher voltage, wherein the gate voltages include a gate low voltage corresponding to a low logical voltage of the scanning pulse, a gate high voltage corresponding to a high logical voltage of the scanning pulse, and a gate modulated voltage between the gate low voltage and the gate high voltage, wherein the gate voltage control means includes a first power wire that supplies the gate low voltage, a second power wire that supplies the gate high voltage, a third power wire that supplies the gate modulated voltage, wherein the gate voltage control means further includes a first transistor connected between the first power wire and the third power wire to control a voltage at a first node between the first power wire and the third power wire in response to a voltage on the first power wire, a second transistor controlled by different voltage of between the voltage of the first node and a voltage of the third power wire, a third transistor connected between the second power wire and the third power wire to control a voltage at a second node between the second power wire and the third power wire in response to a voltage on the third power wire and a fourth transistor controlled by different voltage of between the voltage of the second node and a voltage of the second power wire, wherein the gate voltage control means first supplies the gate low voltage as a low-level voltage to the gate driver and then supplies the gate modulated voltage as a middle-level voltage to the gate driver and last supplies the gate high voltage as a high-level voltage to the gate driver, wherein the first transistor turned on to form a voltage at the first node according to a different voltage of between a base electrode and a emitter electrode of the first transistor and then a different voltage of between a base electrode and a emitter electrode of the second transistor turn on the second transistor so that the gate modulated voltage is supplied to the gate driver, wherein the third transistor turned on to form a voltage at the second node according to a different voltage of between a base electrode and a emitter electrode of the third transistor, while the gate modulated voltage is supplied, and then a different voltage of between a base electrode and emitter electrode of the fourth transistor turn on the fourth transistor so that the gate high voltage is supplied to the gate driver.