In the primary filing, the electronics maker notes that with most HMDs the displays and optics are typically embedded in the helmet, glasses, or a visor, which is worn by the user. However, this arrangement has several drawbacks, the company explains:
"For one, the displays and optics take up a lot of space. Thus, the HMD may be quite large and therefore unwieldy to use. The weight of these components may further exacerbate this problem. For another, the displays may generate a lot of heat and have large power needs, which again make the HMD difficult to construct and use."
Though there exist several different architectures for producing HMDs -- including transmissive, emissive, and reflective -- Apple's design calls for the use of a micro-electro-mechanical/laser-based architecture. Still, there are concerns associated with laser HMD designs, mainly that the devices can generate a lot of heat and require a large amount of power to operate. Furthermore, some laser technologies also have safety concerns, and thus need to be housed in special enclosures in order to prevent laser leakage.
"As should be appreciated, designing around these constraints and limitations add complexity and cost to the HMD," Apple said. "Moreover, they can make the HMD aesthetically unpleasing, which reduces sales of the HMD."
As such, the company suggests a HMD apparatus that separates the laser engine from the image generator via a fiber optic cable so that the laser engine can be physically decoupled from a headgear.
"By separating the laser engine, a more lightweight compact smaller head mounted display apparatus can be created," Apple said. "Furthermore, concerns over heat, power requirement and safety at the head mounted display apparatus are greatly diminished. Another aspect of the invention relates to utilizing wedge optics to display the video images. Wedge optics are very thin and therefore a low profile head mounted display apparatus can be created. Wedge optics also provide a very large picture."
The decoupled laser engine would be a portable unit that can be carried by the user, or "may include a strap, clip or other attachment means for coupling to the user or an article of clothing thereby making it easily transportable." In such a case, Apple notes that the "user simply wears the head mounted display apparatus that includes the imaging device and displays elements on their head, and attaches the laser engine to their person thereby keeping their hands free to do other tasks."
In the case where the display elements of the HMD are formed from transparent optical materials, the user would also be free to be mobile when images aren't being displayed. For example, the user would be able see through the display unit similar to traditional eye glasses. The decoupled laser engine would not be particularly power hungry and thus could be powered by a small battery rather than a power cable, allowing the user to be free to move anywhere they like.
"In one example of this embodiment, a user simply plugs their handheld video player such as the iPod manufactured by Apple Computer of Cupertino, Calif., into the compact laser engine attached to their belt, and places the headset on their head," Apple said. "The user then selects a video to be played at the handheld video player (viewing through transparent display elements). Once selected, the handheld video player generates a video signal which is processed into synchronized light control signals and image control signals for use by the laser engine and imaging device."
"In essence," the company continued, "the laser engine and imaging device work together to create dual video images in accordance with the video signal being outputted by the handheld video player. Furthermore, the display unit receives the dual video images from the imaging device and presents them for viewing. When video is not being played, no images are being created and thus the display unit act just like glasses. In fact, the head set may further include optical components that are based on the user' eyesight so they can see normally when the system is not operating. Thus, the user is able to select other video for playing without taking off the head gear. If the laser engine further includes a battery, the user can be very mobile while utilizing and wearing the system 50 (e.g., not limited to the length of a power cord)."
Additionally, the fiber optic cable coupling the detached laser engine to the headgear could also be configured to include an audio line that provides audio signals in parallel with the video images. As such, the head mounted display apparatus may include integrated earphones capable of transmitting audio signals to the user's ears. The audio line could be an electrical line or an optical line, Apple said. "In some cases, the optical line used to transmit the RGB laser light is also used to send audio signals (e.g., multifunctionality)."
The iPod maker goes on to note that various enhancements may be applied to further improve its HMD concept. For example, the HMD may provide methods and apparatus for providing a wider field of view and creating a more natural viewing situation for a user of a head mounted display, which results in improved comfort and usability for head mounted displays.
The Apple HMD may also provide methods and apparatus for treating the peripheral area of a user's field of view in a head mounted display, and thereby creating improved comfort and usability for head mounted displays.
All three of the related filings are credited to Apple employee John Tang, with Apple iPod chief Anthony Fadell providing some input on the peripheral treatment filing.