Patent ID: 7916107
Filing Date: 2011-03-29
Classification: G09G

Abstract:
1. A gamma voltage output circuit for a liquid crystal display, the gamma voltage output circuit comprising: an internal resistor string, comprising a plurality of resistors and a plurality of nodes; at least one external resistor string, comprising a plurality of resistors and a plurality of nodes; a plurality of switching circuits, each switching circuit comprising at least one input end and at least one output end; wherein the internal and the at least one external resistor strings connect in series between a power source AVDD and ground, respectively, each node outputting a gamma voltage, the nodes of internal and the at least one external resistor strings respectively being connected to the at least one output end and the at least one input end, the resistors of the internal resistor string parallel connecting to corresponding resistors of the at least one external resistor string through the corresponding switching circuit, wherein the at least one external resistor string comprises three external resistor strings, which are a first external resistor string, a second external resistor string and a third external resistor string, and each switching circuit comprises three input ends, which are a first input end, a second input end, and a third input end, in which the plurality of nodes of the first external resistor string respectively connects with the first input ends of the plurality of switching circuits, and the plurality of nodes of the second external resistor string respectively connects with the second input ends of the plurality of switching circuits, and the plurality of nodes of the third external resistor string respectively connects with the third input ends of the plurality of switching circuits, wherein each switching circuit comprises an enabling signal input end, a first controlling signal input end, and a second controlling signal input end, when the enabling signal input end receives a high level signal, and the first and the second controlling signal input ends of the switching circuit respectively receive a low level signal, the first input end electrically connects with the output end.