Apple wins a patent for Smart Rings or Finger-Clips that use Self-Mixing Interferometry to determine finger movement accuracy & speed
Today the U.S. Patent and Trademark Office officially granted Apple a patent that relates to input devices such as a future smart ring or Apple Pencil that use self-mixing interferometry to determine movement within an enclosure.
Apple's granted patent relates to an input device including an enclosure defining a three-dimensional input space and one or more self-mixing interferometry sensors coupled to the enclosure and configured to produce a self-mixing interferometry signal resulting from reflection of backscatter of emitted light by a body part in the three-dimensional input space.
In various examples, movement of the body part may be determined using the self-mixing interferometry signal, which may in turn be used to determine an input.
In some examples, a body part displacement or a body part speed and an absolute distance to the body part may be determined using the self-mixing interferometry signal and used to determine an input.
In various embodiments, an input device includes an enclosure defining a three-dimensional input space; a self-mixing interferometry sensor coupled to the enclosure and configured to emit a beam of coherent light from an optical resonant cavity to illuminate a body part in the three-dimensional input space, receive a reflection or backscatter of the beam into the optical resonant cavity, and produce a self-mixing interferometry signal resulting from self-mixing of the coherent light within the optical resonant cavity; and a processor.
The processor is configured to determine a body part displacement or a body part speed and an absolute distance to the body part using the self-mixing interferometry signal, and determine an input using the body part displacement or the body part speed and the absolute distance.
In some examples, the input corresponds to a touch of the body part to an object. In various implementations of such examples, the processor estimates an amount of force exerted on the object by the body part.
The 'body part' discussed is primarily presented in a series of patent figures below wherein the device appears to be a smart ring surrounding a user's finger. Apple is quite secretive and refers to these smart ring configurations as simply an enclosure around a finger or "an input device." That could be interpreted as either a ring and/or a finger-clip device that they've presented in a few previous patents.
Specifically in Apple's patent FIG. 3 below we see the depiction of an example of an input device #300 that uses self-mixing interferometry to determine movement within an enclosure #301.
The input device may include one or more self-mixing interferometry sensor assemblies 303A, 303B, 303C that may each be configured to emit a beam of coherent light 304A, 304B, 303C to illuminate a finger (body part #302) in a three-dimensional input space and produce a self-mixing interferometry signal resulting from self-mixing of the coherent light.
Further similarly, the input device may determine movement of the finger using the self-mixing interferometry signal and determine an input using the movement.
Apple's patent FIG. 1D above depicts an example block diagram illustrating example functional relationships between example components that may be used in the input device; FIGS. 1A and 2A represent rings with different SMI sensor configurations; FIG. 6 depicts a direct current bias procedure (#600) for determining speed of an object using self-mixing interferometry. This procedure may be used by one or more of the input devices.
The patent also touches on SMI sensors being used to detect movement in an Apple Pencil and more interestingly, a virtual keyboard associated with a heads-up display. Use of the sensors in such an implementation could involve the use of VR gloves, which Apple notes could be cumbersome. That's why the ring or finger-clip enclosures are preferred.
For more details, review Apple's granted patent 11,422,638.
Yesterday, Patently Apple posted another granted patent about a ring using SMI sensors in context with health features.