Patent ID: 6398368
Filing Date: 2002-06-04
Classification: G03B,Y10S

Abstract:
A light pipe for a projection system, the projection system comprising a light source to generate light and to guide the light to the light pipe, and an image device to generate an image using the light gathered by the light pipe, the light pipe being a hollow tapering pipe set between the light source and the image device, the light pipe comprising:four trapezoidal flat plates, each of the trapezoidal flat plates having a top end, a bottom end and two sides, the sides of the trapezoidal flat plates being joined together to form the light pipe; an entrance pupil located at one end of the light pipe, the entrance pupil formed by the four bottom ends of the four trapezoidal flat plates, the light generated by the light source being guided to the light pipe through the entrance pupil; and an exit pupil located at another end of the light pipe, the exit pupil formed by the four top ends of the four trapezoidal flat plates, the light gathered by the light pipe being guided to the image device through the exit pupil; wherein the area of the exit pupil is smaller than that of the entrance pupil, and the shape of the exit pupil is scaled from that of the entrance pupil so as to increase the light gathering efficiency of the light pipe.