US 7,405,712 B2Granted

Method for driving electro-optical device, electro-optical device and electronic equipment

AssigneeSeiko Epson Corporation

InventorsMutsumi Kimura, Hiroyuki Hara

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Abstract

Aspects of the invention can provide a method for driving an electro-optical device, an electro-optical device and electronic equipment that can solve the insufficient supply of the data current and current fluctuation. In the driving method, a data current can be applied to a plurality of pixels provided to a display panel unit with same value through the data line regardless of grayscale data. Upon supply of the data current, in the pixel, a transistor selected in reproduction can be turned on such that a drive current corresponding to the data current output from a driving transistor is supplied to an organic EL element, thereby emitting light. A light-off signal can be supplied to the pixel at predetermined timing such that the organic EL element emits light only in the light-emitting period computed based on the grayscale data. The pixel to which a constant data current can be supplied emits light at a luminance corresponding to the grayscale data by changing the light-emitting period corresponding to the grayscale data.

Claims12

Dependent claims

An electro-optical device that includes a plurality of data lines, a plurality of first scanning lines, a plurality of second scanning lines, and a plurality of pixels, each of the plurality of pixels comprising:

a first transistor Tsig;
a second transistor Tprg;
a third transistor Tdr;
a fourth transistor Trep;
a storage capacitor Csig;
and
an organic EL element, a first electrode of the first transistor Tsig being electrically connected to one of the plurality of data lines, a gate electrode of the first transistor Tsig being electrically connected to one of the plurality of first scanning lines, a first electrode of the second transistor Tprg being electrically connected to a first electrode of the storage capacitor Csig and a gate electrode of the third transistor Tdr, a gate electrode of the second transistor Tprg being electrically connected to the one of the plurality of first scanning lines and the gate electrode of the first transistor Tsig, a first electrode of the third transistor Tdr being electrically connected to a second electrode of the storage capacitor Csig and a Vdd line, a first electrode of the fourth transistor Trep being electrically connected to a second electrode of the first transistor Tsig, a second electrode of the second transistor Tprg, and a second electrode of the third transistor Tdr, a second electrode of the fourth transistor Trep being electrically connected to an electrode of the organic EL element, a gate electrode of the fourth transistor Trep being electrically connected to one of the plurality of second scanning lines,
wherein the organic EL element is configured to be turned off such that:
the one of the plurality of second scanning lines provides a signal at low level to turn off the fourth transistor Trep;
the one of the plurality of data lines provides a light-off signal Vsig to the first electrode of the storage capacitor Csig while the fourth transistor Trep is turned off, a voltage of the light-off signal Vsig being equal to that of a signal provided from the Vdd line;
the one of the plurality of first scanning lines provides a signal at high level to turn on the first transistor Tsig and the second transistor Tprg while the fourth transistor Trep is turned off so that the third transistor Tdr is turned off by the light-off signal Vsig and the organic EL element is turned off;
the one of the plurality of first scanning lines provides a signal at low level to turn off the first transistor Tsig and the second transistor Tprg so that the light-off signal Vsig keeps the third transistor Tdr turned off;
and
the one of the plurality of second scanning lines provides a signal at high level to turn on the fourth transistor Trep after the first transistor Tsig, the second transistor Tprg, and the third transistor Tdr are turned off.

11 more elements

A method of driving an electro-optical device, the electro-optical device including a plurality of data lines, a plurality of first scanning lines, a plurality of second scanning lines, and a plurality of pixels, each of the plurality of pixels having a first transistor Tsig, a second transistor Tprg, a third transistor Tdr, a fourth transistor Trep, a storage capacitor Csig, and an organic EL element, a first electrode of the first transistor Tsig being electrically connected to one of the plurality of data lines, a gate electrode of the first transistor Tsig being electrically connected to one of the plurality of first scanning lines, a first electrode of the second transistor Tprg being electrically connected to a first electrode of the storage capacitor Csig and a gate electrode of the third Tdr, a gate electrode of the second transistor Tprg being electrically connected to the one of the plurality of first scanning lines and the gate electrode of the first transistor Tsig, a first electrode of the third Tdr being electrically connected to a second electrode of the storage capacitor Csig and a Vdd line, a first electrode of the fourth transistor Trep being electrically connected to a second electrode of the first transistor Tsig, a second electrode of the second transistor Tprg, and a second electrode of the third transistor Tdr, a second electrode of the fourth transistor Trep being electrically connected to an electrode of the organic EL element, a gate electrode of the fourth transistor Trep being electrically connected to one of the plurality of second scanning lines, the method comprising the following steps:

a first step of providing a signal from the one of the plurality of second scanning lines at low level to turn off the fourth transistor Trep and turn off the organic EL element at a beginning of a clear period;
a second step of providing a light-off signal Vsig from the one of the plurality of data lines, a voltage of the light-off signal Vsig being equal to that of a signal provided from the Vdd line after the first step;
a third step of providing a signal from the one of the plurality of first scanning lines at high level to turn on the first transistor Tsig and the second transistor Tprg after the second step so that the light-off signal Vsig is provided to the first electrode of the storage capacitor Csig and the third transistor Tdr is turned off by the light-off signal Vsig;
a fourth step of providing a signal from the one of the plurality of first scanning lines at low level to turn off the first transistor Tsig and the second transistor Tprg so that the light-off signal Vsig keeps the third transistor Tdr turned off after the third step;
a fifth step of providing a signal from the one of the plurality of second scanning lines at high level to turn on the fourth transistor Trep during the light-off period after the fourth step.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/959,999Filed 8 Oct 2004
Priority: JP 2003-36750128 Oct 2003
Published: US 2005/0104816 A119 May 2005
Granted: 29 Jul 2008
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G09G 3/2022
By time modulation using two or more time intervals: using sub-frames
G09G 3/325
The current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor…
G09G 3/3258
Using an active matrix: with pixel circuitry controlling the voltage across the light-emitting element
G09G 3/3275
Organic, e.g. using organic light-emitting diodes [OLED]: details of drivers for data electrodes