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US 12,682,864 B2Granted
Liquid crystal display device capable of reducing power consumption without degrading display quality and method of driving the same
AssigneeSharp Display Technology Corporation
InventorsKaoru Yamamoto, Kohhei Tanaka, Keiichi Yamamoto
Life of this patent
Estimating the term…
Abstract
In a first transition period during which an operation mode transitions from a normal mode to a low power consumption mode, a VCOM generation unit in a power source IC changes a potential of a common electrode drive voltage VCOM from a potential of a first level (for example, 5 V) to a potential of a second level (for example, 12 V) so that a leakage current flowing through a pixel transistor is not generated during a pause period, a gate driver changes a potential of each gate bus line to 0 V, and a source driver changes a potential of each source bus line to 0 V.
Claims16
A liquid crystal display device capable of switching an operation mode between a normal mode and a low power consumption mode, the liquid crystal display device comprising:
- a plurality of scanning signal lines;
- a plurality of video signal lines intersecting the plurality of scanning signal lines;
- a plurality of pixel forming portions, each connected to one of the plurality of scanning signal lines and one of the plurality of video signal lines;
- a scanning signal line drive circuit configured to drive the plurality of scanning signal lines;
- a video signal line drive circuit configured to drive the plurality of video signal lines;
- a common electrode provided in common to the plurality of pixel forming portions;
- and
- a power source circuit configured to generate a first power source voltage to be supplied to the common electrode,
- wherein each of the plurality of pixel forming portions includes:
- a pixel electrode,
- a pixel transistor including a control terminal connected to one of the plurality of scanning signal lines, a first conduction terminal connected to one of the plurality of video signal lines, and a second conduction terminal connected to the pixel electrode,
- the common electrode, and
- a liquid crystal capacitance formed by the pixel electrode and the common electrode,
- a period during which the operation mode is set to be the low power consumption mode includes a rewrite period, during which a video signal is written to the liquid crystal capacitance, and a pause period, during which a video signal is not written to the liquid crystal capacitance,
- in a first transition period during which the operation mode transitions from the normal mode to the low power consumption mode:
- the video signal line drive circuit changes potentials of the plurality of video signal lines to 0 V in a state in which each of potentials of the plurality of scanning signal lines is at a predetermined off level,
- the power source circuit changes a potential of the first power source voltage from first level to a second level so that a leakage current flowing through the pixel transistor is not generated during the pause period, and
- the scanning signal line drive circuit changes the potentials of the plurality of scanning signal lines from the predetermined off level to 0 V,
- in a second transition period during which the operation mode transitions from the low power consumption mode to the normal mode:
- the scanning signal line drive circuit changes the potentials of the plurality of scanning signal lines from 0 V to the predetermined off level, and
- the power source circuit changes the potential of the first power source voltage from the second level to the first level,
- a start point of the first transition period is an end point of a period, during which the operation mode is set to be the normal mode,
- an end point of the first transition period is a start point of the period, during which the operation mode is set to be the low power consumption mode,
- a start point of the second transition period is an end point of the period, during which the operation mode is set to be the low power consumption mode, and
- an end point of the second transition period is a start point of the period, during which the operation mode is set to be the normal mode.
22 more elements
A method of driving a liquid crystal display device capable of switching an operation mode between a normal mode and a low power consumption mode,
- the liquid crystal display device including:
- a plurality of scanning signal lines,
- a plurality of video signal lines intersecting the plurality of scanning signal lines,
- a plurality of pixel forming portions, each connected to one of the plurality of scanning signal lines and one of the plurality of video signal lines,
- a scanning signal line drive circuit configured to drive the plurality of scanning signal lines,
- a video signal line drive circuit configured to drive the plurality of video signal lines,
- a common electrode provided in common to the plurality of pixel forming portions, and
- a power source circuit configured to generate a first power source voltage to be supplied to the common electrode,
- wherein:
- each of the plurality of pixel forming portions includes:
- a pixel electrode,
- a pixel transistor including a control terminal connected to one of the plurality of scanning signal lines, a first conduction terminal connected to one of the plurality of video signal lines, and a second conduction terminal connected to the pixel electrode,
- the common electrode, and
- a liquid crystal capacitance formed by the pixel electrode and the common electrode,
- a period during which the operation mode is set to be the low power consumption mode includes a rewrite period, during which a video signal is written to the liquid crystal capacitance, and a pause period, during which a video signal is not written to the liquid crystal capacitance,
- the driving method comprising:
- causing the operation mode to transition from the normal mode to the low power consumption mode;
- and
- causing the operation mode to transition from the low power consumption mode to the normal mode,
- wherein causing the operation mode to transition from the normal mode to the low power consumption mode includes:
- causing the video signal line drive circuit to change potentials of the plurality of video signal lines to 0 V in a state in which each of potentials of the plurality of scanning signal lines is at a predetermined off level,
- causing the power source circuit to change the potential of the first power source voltage from a first level to a second level so that a leakage current flowing through the pixel transistor is not generated during the pause period, and
- causing the scanning signal line drive circuit to change the potentials of the plurality of scanning signal lines from the predetermined off level to 0 V, and
- causing the operation mode to transition from the low power consumption mode to the normal mode includes:
- causing the power source circuit to change the potential of the first power source voltage from the second level to the first level, and
- causing the scanning signal line drive circuit to change the potentials of the plurality of scanning signal lines from 0 V to the predetermined off level, and
- wherein a start point of a first period, during which causing the operation mode to transition from the normal mode to the low power consumption mode is performed, is an end point of a period, during which the operation mode is set to be the normal mode,
- an end point of the first period is a start point of the period, during which the operation mode is set to be the low power consumption mode,
- a start point of a second period, during which causing the operation mode to transition from the low power consumption mode to the normal mode is performed, is an end point of the period, during which the operation mode is set to be the low power consumption mode, and
- an end point of the second period is a start point of the period, during which the operation mode is set to be the normal mode.
27 more elements
Dependencies are inferred from the claim text.