Reference voltage generating circuit and liquid display device using the same
AssigneeLG Display Co., Ltd.
InventorBu Yeol Lee
Life of this patent
Estimating the term…
Abstract
A reference voltage generating circuit for an LCD device includes a main pumping section, a sub-pumping section, an input section inputting a level designating signal periodically and alternately designating a first reference level and a second reference level, and a control section alternately comparing an output voltage with the first and second reference levels in response to the level designating signal, wherein the control section outputs a first logic level and the main pumping section selectively lowers the output voltage in a fast negative pumping and the sub-pumping section selectively raises the output voltage in a slower positive pumping.
Claims18
A reference voltage generating circuit for an LCD device, comprising:
- a main pumping section;
- a sub-pumping section;
- an input section inputting a level designating signal periodically and alternately designating a first reference level and a second reference level;
- and
- a control section alternately comparing an output voltage with the first and second reference levels in response to the level designating signal,
- wherein the control section outputs a first logic level and the main pumping section selectively lowers the output voltage in a fast negative pumping and the sub-pumping section selectively raises the output voltage in a slower positive pumping,
- wherein the control section outputs a second logic level and the main pumping section selectively raises the output voltage in a fast positive pumping and the sub-pumping section selectively lowers the output voltage in a slower negative pumping,
- wherein one of the fast positive pumping and fast negative pumping is selectively performed when the output voltage has a level in a range between the first reference level and the second reference level.
A liquid crystal display device, comprising:
- a liquid crystal panel with liquid crystal cells in a matrix arrangement are commonly connected to a common electrode;
- a driver part driving the liquid crystal panel by alternately supplying pixel data voltages having a negative polarity and a positive polarity with reference to a voltage level on the common electrode to the liquid crystal cells;
- and
- a common voltage generator periodically and alternately having a first reference level and a second reference level lower than the first reference level in response to a polarity inverting signal from the driver part representing the output periods of the pixel data of the negative polarity and the positive polarity, the common voltage generator supplying a common voltage having rapid divergence characteristics and slow convergence characteristics to the common electrodes,
- wherein the common voltage generator includes a main pumping section selectively raising and lowering the common voltage on the common electrode in a fast positive pumping and a fast negative pumping, a sub-pumping section selectively raising and lowering the common voltage on the common electrode in a slower positive pumping and a slower negative pumping and a switching control section alternately comparing the common voltage with the first and second reference levels in response to the polarity inverting signal, and switching the main pumping section between one of the fast positive pumping and fast negative pumping, and the sub-pumping between one of the slower positive and slower negative pumping;
- and
- wherein the fast positive pumping and the fast negative pumping are selectively performed when the common voltage has a level in a range between the first reference level and the second reference level.
Dependencies are inferred from the claim text.