1. Field of the Invention
The present invention relates generally to an electrophoretic display device and more particularly to an electrophoretic display device in which sub-pixels exhibiting four different colors are used to improve reflective luminance.
2. Description of the Related Art
An electrophoretic display (EPD) device is a type of flat display device that is commonly used in electronic books. The EPD device includes two substrates with electric field formation electrodes formed therein and charged particles disposed between the two substrates. A voltage is applied to the two electrodes so that the charged particles move between the electrodes having opposite polarities, thereby displaying an image.
An EPD device has a high reflectivity and contrast. In addition, unlike liquid crystal display devices, the image quality on EPD devices do not vary according to the viewing angle, thus providing advantageously displaying images as on a sheet of paper. EPD devices have bistable characteristics, and thus, the image can remain in displayed state without continuous application of voltage. This bistable characteristic allows EPD devices to operate at reduced power consumption. Another difference between EPDs and liquid crystal devices is that EPD devices do not necessitate a polarization plate, an alignment film, liquid crystal, or other components, and are thus generally less expensive than liquid crystal display devices.
However, liquid crystal display devices have the advantage of being able to display color. A conventional EPD device can only display a black-and-white image, and a separate color filter is needed to display a color image. In addition, the EPD device is not a light-emitting device in itself, so it uses external light. Due to the reliance on external light, EPD devices sometime experience the problem of low reflective luminance.