The patent goes back all the way to the original iMac in 1998 to describe a technology that enables a light source to be coordinated with certain computing events. The hardware foundation uses a light controller that is connected to the main CPU of the computer as well as a light source. In Apple's words, we are talking about: "computing device includes a housing having an illuminable portion. The computing device also includes a light device disposed inside the housing. The light device is configured to illuminate the illuminable portion."
Apple expands on this idea a bit further and notes that "the light source [is] configured to illuminate the reduced thickness portion in order to form an indicator image at an outer surface of the inner bezel" and that the "shape of the recess [produces] an indicator image of similar shape on the outer surface of the inner bezel."
Apple's idea comes down to the thought that the illumination of a computer housing can serve as an additional information source next to the display screen itself. For example, it would provide a different illumination when playing a DVD than when you are playing a video game. While it would be common to assume that Apple would be discussing different color ranges, the patent focuses on intensity and the brightness of the Illumination, which is controller via a light driver: "The light driver is configured to convert the light control signals into a stable continuous current for driving the light emitting diode. The magnitude of the current is based at least in part on the light control signal. The magnitude of the current affects the light intensity of the light emitting diode."
Apple patented the idea for any computing device, including "laptop computers, and handheld computing devices include personal digital assistants (PDAs) and mobile phones." There are 20 separate claims on 65 pages, which exhaustively describes and illustrates Apple's active case illumination idea.