As lenses and flashes gain more and more functions, camera manufacturers are running out of room for the electrical contacts required to transmit signals between components. Some of the latest compact clip-on flash units draw their power through the hotshoe, needing two contacts for this current, taking up space that could be used to transmit other signals such as synchronisation, TTL metering, wake-up from sleep mode etc.
Canon have filed a patent that could solve this problem. Using an extremely short-range wireless system between the camera and the flashgun, signals can be sent via radio instead of by wire. The invention also means that dirt, mechanical wear and corrosion will be less likely to affect correct function of a flash unit.
These diagrams, published in Canon patent application 2012-2984 on Japan’s Industrial Property Digital Library, show modules in the camera (3a) and flash (3d) for communicating settings wirelessly between the two. A wireless system faces its own challenges, such as signal interference and backwards compatibility.
… Then, it is possible to build a wireless communication function in a camera body, and to communicate by an external instrument and radio as the technique of communicating without passing electric contact 25. There are what communicates with partner equipment using the electric wave and magnetic field which are emitted from an antenna section, and a thing which communicates with partner equipment using beams of light, such as infrared rays, in radio.
The patent itself is for a method to prevent other devices from interfering or communicating in such a system without pairing first. For more information, please consult the document on the IPDL web site.