We could soon see a new kind of display screen from computer maker Apple (patent) - one that simultaneously takes pictures while showing images.  The clever idea is to insert thousands of microscopic image sensors in-between the liquid crystal display cells in the screen. Each sensor captures its own small image, but software stitches these together to create a single, larger picture. A large LCD screen filled with image sensors would be ideal for videoconferencing, Apple suggests, as participants would always appear to look straight into the "camera". The technique could also add a camera function to a cellphone or PDA without wasting space, and light from the screen should help illuminate a subject. The more sensors there are, the wider and clearer the image. Sketches accompanying the company's patent show as many sensors as liquid crystal cells in a screen. If some of the sensors have different focal lengths, switching between them would make the screen behave like a zoom lens.