Liquid crystal display device for preventing and afterimage
View Patent ↗The liquid crystal display device includes pixel electrodes; a common electrode; a plurality of data lines and a plurality of gate lines intersecting each other; a plurality of switchers for the pixel electrodes for supplying signals from the data lines to the pixel electrodes; a gate line driver for scanning the gate lines; a data line driver for driving the data lines in accordance with the gradation to be displayed; and a controller for controlling the gate line driver and the data line driver. The controller includes a signal absence detector for detecting that no signal has been input to the liquid crystal display device. The controller outputs a signal to the gate line driver to make all the gate lines active for a predetermined time after the signal absence detector detects that no signal has been input. The controller outputs a signal to the data line driver to supply an electric potential, applied to the common electrode, to all the data lines for the predetermined time.
1. A liquid crystal display device comprising:
pixel electrodes;
a common electrode;
a plurality of data lines and a plurality of gate lines intersecting each other;
a plurality of switchers, provided for the pixel electrodes, for supplying signals from the data lines to the pixel electrodes;
a gate line driver for scanning the gate lines;
a data line driver for driving the data lines, in accordance with the gradation to be displayed; and
a controller for controlling the gate line driver and the data line driver, wherein
the controller comprises a signal absence detector for detecting that at least one of a video signal, a horizontal synchronization signal, and a vertical synchronization signal is no longer being input to the liquid crystal display device,
wherein in response to a detection by the signal absence detector that one of the signals is no longer being input while power is being supplied to the liquid crystal display, the controller outputs a signal to the gate line driver to make all the gate lines active for a predetermined time and the controller outputs a signal to the data line driver to supply the same electric potential as applied to the common electrode to all the data lines for the predetermined time,
wherein, after discharging of the liquid crystal display, the controller outputs signals to the gate line driver and the data line driver for making the gate line driver and the data line driver return to a state before the discharging was performed, and
wherein the predetermined time, during which time all the gate lines are active and during which time the same electric potential as applied to the common electrode is applied to all the data lines, is determined based on time constants of a resistor and a capacitor.
2. A liquid crystal display device according to claim 1 , wherein the predetermined time is a time required to discharge all the charge from the liquid crystal by supplying the common electric potential to all the pixel electrodes.
3. A liquid crystal display device according to claim 1 , further comprising a power supply maintaining circuit for maintaining power after a power supply to the liquid crystal display device is turned off.
4. A liquid crystal display device according to claim 1 , wherein the data line driver connects all the data lines to the ground after a power supply to the liquid crystal display device is turned off.
5. The device of claim 1 , wherein said signal absence detector detects that at least one of a video signal and a vertical synchronization signal is no longer being input to the liquid crystal display device.
6. The device of claim 1 , wherein said signal absence detector detects that a video signal is no longer being input to the liquid crystal display device.
7. The device of claim 1 , wherein said signal absence detector detects that a vertical synchronization signal is no longer being input to the liquid crystal display device.
8. A method for controlling a liquid crystal display device comprising: pixel electrodes; a common electrode; a plurality of data lines and a plurality of gate lines intersecting each other; a plurality of switchers, provided for the pixel electrodes, for supplying signals from the data lines to the pixel electrodes; a gate line driver for scanning the gate lines; a data line driver for driving the data lines, in accordance with the gradation to be displayed; and a controller for controlling the gate line driver and the data line driver, the method comprising the steps of:
detecting that at least one of a video signal, a horizontal synchronization signal, and a vertical synchronization signal is no longer being input to the liquid crystal display device;
in response to detection that one of the signals is no longer being input to the liquid crystal display device while power is being supplied to the liquid crystal display, making all the gate lines active for a predetermined time and supplying the same electric potential as applied to the common electrode to all the data lines for the predetermined time, wherein the predetermined time, during which time all the gate lines are active and during which time the same electric potential as applied to the common electrode is applied to all the data lines, is determined based on time constants of a resistor and a capacitor, and
after discharging of the liquid crystal display, outputting signals to the gate line driver and the data line driver for making the gate line driver and the data line driver return to a state before the discharging is performed.
9. The method of claim 8 , wherein the detecting step detects that at least one of a video signal and a vertical synchronization signal is no longer being input to the liquid crystal display device.
10. The method of claim 8 , wherein the detecting step detects that a video signal is no longer being input to the liquid crystal display device.
11. The method of claim 8 , wherein the detecting step detects that a vertical synchronization signal is no longer being input to the liquid crystal display device.