Patent ID: 8035847

Claim:
A handheld display device for overlaying a printed substrate and for revealing hidden content associated with the printed substrate, said device comprising: an optical sensor for imaging an area of the printed substrate and for generating image data, said imaged area of the printed substrate contained printed content but no hidden content; a processor for determining interaction data using the image data, said interaction data identifying a page description corresponding to the printed substrate; a transceiver for: sending the interaction data to a computer system, thereby causing the computer system to identify the page description and retrieve display data comprising first data corresponding to said printed content and second data corresponding to the hidden content; and receiving the display data from the computer system; and an opaque touch-sensitive display screen for displaying display information based on said display data, said display information including first content matching with the printed content underlying said opaque display screen and second content corresponding to the hidden content, such that the opaque display screen has real-time virtual transparency through the screen to the printed content underlying said screen from a user's perspective to provide a virtual window to the printed content underlying said screen and wherein the opaque display screen additionally reveals the hidden content in real-time as if it were printed on the underlying printed substrate.