Color display device

Abstract

The present invention provides a reflective color display device which can display multiple color states, without the disadvantages associated with previously known color display devices. The display fluid of the present invention comprises (a) black and white electrophoretic particles which are oppositely charged and (b) charged color-generating particles having photonic crystal characteristics, all of which are dispersed in a solvent or solvent mixture.

Description

[0001]This application claims the benefit of U.S. Provisional Application 61 / 955,129, filed Mar. 18, 2014, which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention is directed to a color display device which can display high quality color states, and a display fluid for such a color display device.BACKGROUND OF THE INVENTION[0003]In order to achieve a color display, color filters are often used. The most common approach is to add color filters on top of black / white sub-pixels of a pixellated display to display the red, green and blue colors. When a red color is desired, the green and blue sub-pixels are turned to the black state so that the only color displayed is red. When the black state is desired, all three-sub-pixels are turned to the black state. When the white state is desired, the three sub-pixels are turned to red, green and blue, respectively, and as a result, a white state is seen by the viewer.[0004]The biggest disadvant...

AI Technical Summary

Benefits of technology

The present invention is directed to a display fluid that includes particles which can produce different colors when charged. These particles can be made of various materials, such as silicon, titanium, barium, strontium, iron, nickel, cobalt, lead, aluminum, copper, silver, gold, tungsten, molybdenum, or a compound thereof. The particles can be coated or formed by using a material having electric charges. The color-generating particles can be activated by an electric field to control their inter-particle distances, which in turn affects the intensity of the displayed colors. This allows for controlled adjustment of the colors displayed. The solvent or solvent mixture used in the display fluid can also have electrical polarization characteristics.

Problems solved by technology

The biggest disadvantage of such a technique is that since each of the sub-pixels has a reflectance of about one third (⅓) of the desired white state, the white state is fairly dim.

Brighter colors can be achieved by adding light from the white pixel, but this is achieved at the expense of color gamut to cause the colors to be very light and unsaturated.

Even with this approach, the white level is normally substantially less than half of that of a black and white display, rendering it an unacceptable choice for display devices, such as e-readers or displays that need well readable black-white brightness and contrast.

However, the number of the color states displayed is limited by how many types of different colored particles are in the display fluid and how well their movement can be controlled.

Images