Methodology and application of acoustic touch detection

Abstract

Acoustic touch detection (touch sensing) system architectures and methods can be used to detect an object touching a surface. Position of an object touching a surface can be determined using time-of-flight (TOF) bounding box techniques, or acoustic image reconstruction techniques. Acoustic touch sensing can utilize transducers, such as piezoelectric transducers, to transmit ultrasonic waves along a surface and/or through the thickness of an electronic device. Location of the object can be determined, for example, based on the amount of time elapsing between the transmission of the wave and the detection of the reflected wave. An object in contact with the surface can interact with the transmitted wave causing attenuation, redirection and/or reflection of at least a portion of the transmitted wave. Portions of the transmitted wave energy after interaction with the object can be measured to determine the touch location of the object on the surface of the device.

1 - 35 . (canceled) 
     
     
         36 . An acoustic touch sensing system, comprising:
 an acoustic touch sensing circuit configured to perform a first detection scan of a surface and configured to perform a second detection scan of the surface; and   one or more processors coupled to the acoustic touch sensing circuit;   wherein at least one of the acoustic touch sensing circuit or the one or more processors is configured to process results of the first detection scan or results of the second detection scan;   wherein, when an object is touching the surface, the results of the first detection scan indicate a presence of the object touching the surface; and   wherein, when the object is touching the surface, the results of the second detection scan indicate a location of the object touching the surface.   
     
     
         37 . The acoustic touch sensing system of  claim 36 , wherein the one or more processors comprises a host processor and an auxiliary processor. 
     
     
         38 . The acoustic touch sensing system of  claim 37 , wherein the auxiliary processor is configured to receive the results of the first detection scan and the results of the second detection scan; and
 wherein the auxiliary processor is configured to:
 process the results of the first detection scan to determine the presence of the object touching the surface; and 
 process the results of the second detection scan to determine the location of the object touching the surface. 
   
     
     
         39 . (canceled) 
     
     
         40 . (canceled) 
     
     
         41 . The acoustic touch sensing system of  claim 37 , wherein the auxiliary processor is configured to receive the results of the first detection scan and the host processor is configured to receive the results of the second detection scan;
 wherein the auxiliary processor is configured to process the results of the first detection scan to determine the presence of the object touching the surface; and   wherein the host processor is configured to process the results of the second detection scan to determine the location of the object touching the surface.   
     
     
         42 . The acoustic touch sensing system of  claim 41 , wherein the results of the first detection scan are transferred to the auxiliary processor by a first communication channel and the results of the second detection scan are transferred to the host processor by a second communication channel, wherein the second communication channel has a bandwidth greater than the first communication channel. 
     
     
         43 . The acoustic touch sensing system of  claim 36 , further comprising:
 an acoustic touch sensing digital signal processor configured to receive the results of the second detection scan;   wherein the acoustic touch sensing digital signal processor is configured to process the results of the second detection scan to determine the location of the object touching the surface.   
     
     
         44 . The acoustic touch sensing system of  claim 36 , wherein the acoustic touch sensing circuit is configured to process the results of the first detection scan and the results of the second detection scan to determine the presence and the location of the object touching the surface. 
     
     
         45 . The acoustic touch sensing system of  claim 36 , further comprising:
 a plurality of transducers coupled to the surface; and   routing deposited along a side of the surface adjacent to the plurality of transducers;   wherein the acoustic touch sensing circuit is coupled to the plurality of transducers via coupling of the acoustic touch sensing circuit to the routing on the routing deposited along the side of the surface.   
     
     
         46 . The acoustic touch sensing system of  claim 36 , further comprising:
 a plurality of transducers coupled to the surface;   wherein the acoustic touch sensing circuit is coupled to the plurality of transducers via direct bonding between the plurality of transducers and the acoustic touch sensing circuit, via bonding between the plurality of transducers and a flexible circuit board coupled to the acoustic touch sensing circuit, or via bonding between the plurality of transducers and a rigid circuit board coupled to the acoustic touch sensing circuit.   
     
     
         47 . The acoustic touch sensing system of  claim 36 , wherein the acoustic touch sensing circuit comprises an acoustic transmit circuit and an acoustic receive circuit; wherein the acoustic transmit circuit is implemented on a first integrated circuit and the acoustic receive circuit is implemented on a second integrated circuit, separate from the first integrated circuit. 
     
     
         48 . The acoustic touch sensing system of  claim 36 , further comprising a plurality of transmit transducers and a plurality of receive transducers; wherein the acoustic touch sensing circuit is configured to generate an acoustic stimulation signal to apply to the plurality of transmit transducers; and wherein the acoustic touch sensing circuit is configured to receive an acoustic receive signal from the plurality of receive transducers generated in response to the acoustic stimulation signal. 
     
     
         49 . A method comprising:
 performing a first acoustic detection scan of a surface;   processing results of the first acoustic detection scan to determine whether an object is contacting the surface;   in accordance with a determination that the object is contacting the surface, performing a second acoustic detection scan of the surface; and   processing results of the second acoustic detection scan to determine a location of the object contacting the surface.   
     
     
         50 . The method of  claim 49 ,
 wherein performing the first acoustic detection scan comprises:
 transmitting an acoustic wave into the surface from a first transducer; and 
 receiving an acoustic reflection corresponding to an edge of the surface opposite the first transducer at the first transducer; and 
   wherein processing the results of the first acoustic detection scan to determine whether the object is contacting the surface comprises:
 determining that the object is contacting the surface when the received acoustic reflection corresponding to the edge of the surface is attenuated more than a threshold amount below a baseline received acoustic reflection corresponding to the edge of the surface. 
   
     
     
         51 . The method of  claim 49 ,
 wherein performing the first acoustic detection scan comprises:
 transmitting an acoustic wave into the surface from a first transducer; and 
 receiving the acoustic wave at a second transducer opposite the first transducer; and 
   processing the results of the first acoustic detection scan to determine whether the object is contacting the surface comprises:
 determining that the object is contacting the surface when the received acoustic wave is attenuated more than a threshold amount below a baseline received acoustic wave. 
   
     
     
         52 . The method of  claim 49 , wherein performing the second acoustic detection scan comprises:
 transmitting, by a first transducer of a plurality of transducers, a first acoustic wave in the surface;   receiving, by the first transducer of the plurality of transducers, a first acoustic reflection in the surface;   transmitting, by a second transducer of the plurality of transducers, a second acoustic wave in the surface;   receiving, by the second transducer of the plurality of transducers, a second acoustic reflection in the surface;   transmitting, by a third transducer of the plurality of transducers, a third acoustic wave in the surface;   receiving, by the third transducer of the plurality of transducers, a third acoustic reflection in the surface;   transmitting, by a fourth transducer of the plurality of transducers, a fourth acoustic wave in the surface; and   receiving, by the fourth transducer of the plurality of transducers, a fourth acoustic reflection in the surface.   
     
     
         53 . The method of  claim 52 , wherein processing the results of the second acoustic detection scan to determine the location of the object contacting the surface further comprises:
 determining a first time of flight between the transmitted first acoustic wave and the received first acoustic reflection;   determining a second time of flight between the transmitted second acoustic wave and the received second acoustic reflection;   determining a third time of flight between the transmitted third acoustic wave and the received third acoustic reflection;   determining a fourth time of flight between the transmitted fourth acoustic wave and the received fourth acoustic reflection; and   determining the location of the object based on the first time of flight, the second time of flight, the third time of flight, and the fourth time of flight.   
     
     
         54 . The method of  claim 49 ,
 wherein performing the first acoustic detection scan comprises:
 transmitting an acoustic wave into the surface from a first transducer on a first side of the surface; and 
 receiving an acoustic reflection corresponding to an edge of the surface opposite the first transducer at a second transducer on the first side of the surface; and 
   wherein processing the results of the first acoustic detection scan to determine whether to object is contacting the surface comprises:
 determining that the object is contacting the surface when the received acoustic reflection corresponding to the edge of the surface is attenuated more than a threshold amount below a baseline received acoustic reflection corresponding to the edge of the surface. 
   
     
     
         55 . (canceled) 
     
     
         56 . (canceled) 
     
     
         57 . A non-transitory computer readable storage medium storing instructions, which when executed by a device comprising a surface, a plurality of acoustic transducers coupled to edges of the surface, an acoustic touch sensing circuit, and one or more processors, cause the acoustic touch sensing circuit and the one or more processors to:
 in a first state:
 perform a first acoustic detection scan of the surface; and 
 process results of the first acoustic detection scan to determine whether an object is contacting the surface; and 
   in a second state:
 perform a second acoustic detection scan of the surface; and 
 process results of the second acoustic detection scan to determine a location of the object contacting the surface. 
   
     
     
         58 . The non-transitory computer readable storage medium of  claim 57 , further comprising instructions, which executed by the device, cause the acoustic touch sensing circuit to transition from the first state to the second state when the object is determined to be contacting the surface based on processing the results of the first acoustic detection scan. 
     
     
         59 . The non-transitory computer readable storage medium of  claim 57 , further comprising instructions, which executed by the device, cause the acoustic touch sensing circuit to transition from the second state to the first state when no object is determined to be contacting the surface based on processing the results of the second acoustic detection scan for a threshold period of time or in response to receiving user input to power down a display of the device. 
     
     
         60 - 89 . (canceled)