Drive method for an electrophoretic display device and an electrophoretic display device
View Patent ↗A drive method for an electrophoretic display device that has an electrophoretic device composed of a suspension fluid containing electrophoretic particles disposed between a common electrode and a plurality of pixel electrodes, a driver that drives the electrophoretic device by applying voltage between the common electrode and the plural pixel electrodes, and a controller that controls the driver. The control method has a display redrawing process that changes the displayed image by applying a common electrode drive pulse that repeats two different potentials to the common electrode, and applying either of the two different potentials to the pixel electrodes according to the updated display content. The display redrawing process includes a first pulse application step that applies a first pulse train to the common electrode as the common electrode drive pulse train, and a second pulse application step that executes after the first pulse application step to apply a second pulse train to the common electrode as the common electrode drive pulse train, the pulses of the second pulse train being wider than the pulses of the first pulse train.
1. A drive method for an electrophoretic display device that has an electrophoretic device composed of a suspension fluid containing electrophoretic particles disposed between a common electrode and a plurality of pixel electrodes,
driving the electrophoretic device by applying voltage between the common electrode and the plural pixel electrodes; and
redrawing the display to change the displayed image, the redrawing including
applying a first pulse train that repeats first potential and a second potential, to the common electrode until a reflectance of the displayed image reaches a threshold value set to at least 80% and less than 100% of a targeted maximum reflectance,
applying one of the first potential, and the second potential to a first pixel electrode while applying the first pulse train according to the updated display content,
applying a second pulse train that repeats the first potential and the second potential, after the threshold value is reached, to the common electrode, each pulse of the second pulse train having a longer width than that of each pulse of the first pulse train, and
applying the one of the first potential and the second potential to the first pixel electrode while applying the first pulse train;
wherein the electrophoretic display device has no holding electrode.
2. The drive method for an electrophoretic display device described in claim 1 , wherein the pulse width of each of the second pulse train pulses is about 2 to about 30 times the pulse width of each of the first pulse train pulses.
3. The drive method for an electrophoretic display device described in claim 1 , wherein:
the electrophoretic particles comprise electrophoretic particles of a first color for displaying a first color and electrophoretic particles of a second color for displaying a second color, the first color electrophoretic particles each being within a first size range and the second color electrophoretic particles being within a second size range that is different from the first size range,
the common electrode drive pulse repeatedly alternates between a first-color writing voltage that changes the displayed image to the first color and a second-color writing voltage that changes the image to the second color; and
the last pulse in the common electrode drive pulse train is (i) the first-color writing voltage when the first size range is larger than the second size range, and (ii) the second-color writing voltage when the second size range is larger than the first size range.
4. The drive method for an electrophoretic display device described in claim 3 , wherein:
the first pulse train in the common electrode drive pulse train in the display redrawing process is the first-color writing voltage when the electrophoretic particles of the first color are larger than the electrophoretic particles of the second color, and
the first pulse in the common electrode drive pulse stream in the display redrawing process is the second-color writing voltage when the electrophoretic particles of the second color are larger than the electrophoretic particles of the first color.