Self-Mixing Interferometry Sensors Used to Sense Vibration of a Structural or Housing Component Defining an Exterior Surface of a Device

Abstract

A device includes an electronic display, a cover through which the electronic display projects an image, and an array of SMI sensors. The array of SMI sensors is positioned on a same side of the cover as the electronic display. Each SMI sensor is configured to emit electromagnetic radiation toward a respective portion of: an interior surface of the cover, or a surface of a component of the device attached to the cover; and generate a respective SMI output including information indicative of vibration of the respective portion of the cover or the component. The device also includes circuitry configured to characterize a vibratory waveform impinging on the device. The vibratory waveform is characterized using at least two of the SMI outputs.

What is claimed is: 
     
         1 . A device, comprising:
 a structural component defining an exterior surface of the device;   at least one self-mixing interferometry (SMI) sensor positioned behind the structural component; wherein each SMI sensor is configured to:
 emit electromagnetic radiation toward: a respective interior portion of the structural component, or a surface of an internal component of the device attached to the structural component; and 
 generate an SMI output including information indicative of vibration of the structural component or the internal component; and 
   circuitry configured to:
 identify a user command contained within the information indicative of the vibration of the structural component or the internal component; and 
 execute or transmit the user command. 
   
     
     
         2 . The device of  claim 1 , wherein:
 the at least one SMI sensor comprises an array of SMI sensors disposed behind the structural component; wherein each SMI sensor in the array is configured to:
 emit electromagnetic radiation toward: a respective interior portion of the structural component, or a respective portion of the internal component; and 
 generate a respective SMI output including information indicative of the vibration of the structural component or the internal component. 
   
     
     
         3 . The device of  claim 2 ; wherein the circuitry is further configured to:
 sum at least two of the SMI outputs in the time domain; and   identify the user command using the summed SMI outputs.   
     
     
         4 . The device of  claim 2 , further comprising:
 a substrate positioned behind the structural component; wherein:   the array of SMI sensors is disposed on the substrate.   
     
     
         5 . The device of  claim 2 , wherein the circuitry is further configured to:
 determine at least one phase difference between at least two of the SMI outputs; and   determine, using the at least one phase difference and known positions of the SMI sensors, a direction to a source of the user command.   
     
     
         6 . The device of  claim 5 , wherein the circuitry is configured to execute or transmit the user command after determining the user command was received from a predetermined direction or a range of directions. 
     
     
         7 . The device of  claim 2 , wherein the SMI sensors of the array are discrete SMI sensors disposed at different positions behind the structural component. 
     
     
         8 . The device of  claim 1 , wherein the user command is a wakeup command, and the circuitry is further configured to:
 transition the device from a low power state or a no power state to an operating power state in response to identifying the wakeup command.