Viewing-angle-switching device based on array of optical micro-rods incorporated with electrophoretic material systems

We have successfully demonstrated a control device for a viewing angle that enables switching between two states, a wide-viewing angle, and a narrow-viewing angle. It is composed of a light-transmitting portion formed with an array of optical micro-rods and a shielding/transmitting changeable portion of cross stripes designed with electrophoretic material systems consisting of black particles and an optically transparent medium. When the black particles are fully dispersed in the optically transparent medium, the cross stripe portion plays the role of a non-transmitting material as the shielding portion in a similar manner to a conventional viewing angle control film. When the black particles are completely gathered electronically to one side in the optically transparent medium, in contrast, the cross stripe portion filled by the optically transparent medium can transmit incident light. These functions allow us to select electrically either of two modes between a limited viewing angle and a non-limited viewing angle. The optical properties for the limited viewing angle mode were +/−30° of the visible angle and 50% of the transmittance, and the one for the non-limited viewing mode was 58% of the transmittance. The response time from the narrow-viewing angle to wide-viewing angle was 1 s at 20 V of applied voltage.