Patent ID: 8648911

Claim:
A communication system comprising: a control device that divides one frame into plural sub-frames, distributes image signals of a first image to the plural sub-frames such that a sum of signal levels in the one frame is zero, superimposes the image signals on an image signal of a second image, and outputs the image signals; a display device that displays, for each of the sub-frames, an image based on the image signals output from the control device; and a reception device that shoots an image displayed on the display device in each period same as a period of the sub-frames and calculates the difference between two image signals obtained in each period which is the same as the period of the sub-frames to acquire and display the image signals of the first image, wherein the reception device adds up image signals obtained in each period which is the same as the period of the sub-frames to acquire and display the image signal of the second image, and wherein, when a number of sub-frames in the one frame is represented as n, where n is an integer number equal to or greater than 3, the reception device includes: a sub-frame memory that stores an integrated signal obtained by adding up a first image signal obtained in each period that is the same as the period of the sub-frame in the one frame and the n−1th image signal; an amplifier that multiplies a signal level of the nth image signal in the one frame by n−1; and a subtracter that calculates the difference between the integrated signal stored in the sub-frame memory and an image signal output from the amplifier and outputs the image signals of the first image.