Image display apparatus and driving method thereof
AssigneeLG Display Co., Ltd.
InventorsKaoru Kusafuka, Shinji Takasugi, Taro Hasumi
Life of this patent
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Abstract
An image display apparatus includes a light emitting unit that emits light by current flowing through the light emitting unit; and a driver unit that includes a first terminal and a second terminal. The driver unit has a characteristic that an absolute value of a current flowing through the second terminal increases with a potential of the first terminal to the second terminal, and controls light emission of the light emitting unit based on a potential difference between the first terminal and the second terminal. The image display apparatus also includes a control unit that controls the potential of the first terminal to the second terminal of the driver unit to a value lower than a threshold voltage of the driver unit.
Claims2
An image display apparatus, comprising:
- a light emitting unit configured to emit light by current flowing through the light emitting unit;
- a driving transistor including a gate electrode, a drain electrode, and a source electrode, the driving transistor being configured to control light emission of the light emitting unit based on a potential difference between the gate electrode and the source electrode;
- a threshold-voltage detecting transistor;
- and
- a control unit configured to:
- control a difference of a potential of the gate electrode and a potential of the source electrode to be a threshold voltage of the driving transistor by increasing a potential of a merge line electrically connected, via a switching transistor, to the gate electrode during a threshold-voltage detection period and passing, by short-circuiting of the gate electrode and the drain electrode, a current from the gate electrode to the drain electrode,
- control the potential of the gate electrode and the potential of the drain electrode to be a same potential during a write period by decreasing the potential of the merge line and connecting together the gate electrode and the drain electrode, and
- control the potential difference between the gate electrode and the source electrode to be a value lower than the threshold voltage of the driving transistor by decreasing a potential of a control line electrically connected to the gate electrode below a potential of the control line during a preparation period and increasing the potential of the merge line during a light emission period of the light emitting unit, and to have a variation width that is in inverse proportion to a gradation level of light emission brightness, by varying the potential difference between the gate electrode and the source electrode when the driving transistor has a characteristic that an absolute value of a current flowing through the source electrode increases with the potential difference between the gate electrode and the source electrode,
- wherein the image display apparatus is a multi-color image display apparatus, and
- wherein a value of an image signal voltage corresponding to a maximum gradation level is arranged to a maximum value of the image signal voltage and a variation width of the potential difference between the gate electrode and the source electrode is varied for different colors of the emitted light.
A method of driving an image display apparatus that includes a light emitting unit, a driving transistor, and a threshold-voltage detecting transistor, the driving transistor including a gate electrode, a drain electrode and a source electrode, and the driving transistor being electrically connected to a light emitting element, the method comprising:
- controlling a difference of a potential of the gate electrode and a potential of the source electrode to be a threshold voltage of the driving transistor by increasing a potential of a merge line electrically connected, via a switching transistor, to the gate electrode during a threshold-voltage detection period and passing, by short-circuiting of the gate electrode and the drain electrode, a current from the gate electrode to the drain electrode,
- controlling the potential of the gate electrode and the potential of the drain electrode to be a same potential during a write period by decreasing the potential of the merge line and connecting together the gate electrode and the drain electrode, and
- controlling the potential difference between the gate electrode and the source electrode to be a value lower than the threshold voltage of the driving transistor by decreasing a potential of a control line electrically connected to the gate electrode below a potential of the control line during a preparation period and increasing the potential of the merge line during a light emission period of the light emitting unit, and to have a variation width that is in inverse proportion to a gradation level of light emission brightness, by varying the potential difference between the gate electrode and the source electrode when the driving transistor has a characteristic that an absolute value of a current flowing through the source electrode increases with the potential difference between the gate electrode and the source electrode,
- wherein the image display apparatus is a multi-color image display apparatus, and
- wherein a value of an image signal voltage corresponding to a maximum gradation level is arranged to a maximum value of the image signal voltage and a variation width of a potential difference between the gate electrode and the source electrode is varied for different colors of the emitted light.
Dependencies are inferred from the claim text.