Patent ID: 8830582

Claim:
A pair of viewing glasses, comprising: a polarizer; a polarization conversion unit, disposed between a display screen and the polarizer, controlled by an operating signal to adjust a polarization direction of an image beam from the display screen before passing through the polarizer; a first light sensing unit detecting a first light intensity of the image beam after passing through the polarization conversion unit and the polarizer; and a control unit coupled to the first light sensing unit and the polarization conversion unit, the control unit obtaining brightness or transmittance of the image beam according to the first light intensity, and generating an operating signal according to an operating period of the viewing glasses, a corresponding value corresponding to the operating period of the viewing glasses, and the brightness or the transmittance of the image beam, so the transmittance is equal to the corresponding value corresponding to the operating period of the viewing glasses, and maintaining the operating signal during the operating period of the viewing glasses, wherein the operating period of the viewing glasses is a non-viewing period or a viewing period, wherein the control unit further determines whether the transmittance of the image beam is the corresponding value, when the transmittance of the image beam is not the corresponding value, the control unit controls the polarization conversion unit to rotate the polarization direction of the image beam towards a first direction, and when the transmittance of the image beam is the corresponding value corresponding to the one of the non-viewing period and the viewing period other than the operating period of the viewing glasses, the control unit controls the polarization conversion unit to rotate the polarization direction of the image beam by a specific angle.