An image display system comprises a first liquid crystal projector which projects a counterclockwise-rotating, circularly polarized light beam to form an image containing specific visual information on a screen and a second liquid crystal projector which projects a clockwise-rotating, circularly polarized light beam to form a white image on the same screen. The continuously variable drive may function in increments as well as allow the supercharger to free-wheel. The token is adapted to receive, through at least one USB communication channel, a command for requesting the token to specify at least one capability of the token, and send, through at least one USB communication channel, as a reply to the received command, a response for specifying that the token supports a USB device class for HID.