Patent ID: 8446601

Claim:
A control device comprising: a first control unit configured to generate image data of a plurality of images to be superposed one on the other to form a single image and transmit the image data; and a second control unit configured to receive the image data and superpose the images so as to form the single image; wherein the second control unit transmits to the first control unit a horizontal sync reference signal for achieving synchronization of the images in a horizontal direction, based on the horizontal sync reference signal, the first control unit transmits to the second control unit a transfer clock signal that indicates transmission timing of the image data and an effective area signal that indicates an effective area of the image data, and the first control unit asserts the effective area signal for an effective-area-signal assertion period that occurs between two consecutive reference-signal assertion periods during which the horizontal sync reference signal is asserted; wherein the first control unit stops the transmission of the transfer clock signal during an effective-area-signal negation period, during which the effective area signal is negated, prior to the effective-area-signal assertion period; the first control unit then transmits the transfer clock signal during the effective-area-signal assertion period; and when the effective area signal is negated again after the effective-area-signal assertion period, the first control unit keeps the transmission of the transfer clock signal for a period corresponding to a predetermined number of pulses of the transfer clock signal, before stopping the transmission of the transfer clock signal.