Operating a two-dimensional array of ultrasonic transducers

Abstract

In a method of operating a two-dimensional array of ultrasonic transducers, a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers is defined, the plurality of array positions each comprising a portion of ultrasonic transducers of the two dimensional array of ultrasonic transducers. For each array position of the plurality of array positions, a plurality of ultrasonic transducers associated with the respective array position are activated. The activation includes transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam. The activation also includes receiving reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers.

What is claimed is: 
     
         1 . A method of operating a two-dimensional array of ultrasonic transducers, the method comprising:
 defining a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, the plurality of array positions each comprising a portion of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, wherein the plurality of array positions are for capturing an image over the two-dimensional array of ultrasonic transducers;   defining an activation sequence of the plurality of array positions, wherein the activation sequence defines movement of the plurality of array positions over the two-dimensional array of ultrasonic transducers for forming a focused ultrasonic beam at different locations over the two-dimensional array of ultrasonic transducers;   for each array position of the plurality of array positions, activating a plurality of ultrasonic transducers associated with the respective array position for capturing a pixel of the image, the activating comprising:
 transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam focused for reflecting off an object in contact with a contact surface of a platen overlying the two-dimensional array of ultrasonic transducers; and 
 receiving reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers; and 
   performing the activating a plurality of ultrasonic transducers associated with the respective array position according to the activation sequence for each array position of the plurality of array positions.   
     
     
         2 . The method of  claim 1 , wherein the ultrasonic transducers are Piezoelectric Micromachined Ultrasonic Transducer (PMUT) devices. 
     
     
         3 . The method of  claim 1 , wherein a phase delay pattern of the first group of ultrasonic transducers is symmetric about two axes of the first group of ultrasonic transducers, wherein the two axes are orthogonal to each other. 
     
     
         4 . The method of  claim 1 , wherein a phase delay pattern of the first group of ultrasonic transducers is asymmetric about two axes of the first group of ultrasonic transducers, wherein the two axes are orthogonal to each other. 
     
     
         5 . The method of  claim 1 , wherein a phase delay pattern of the first group of ultrasonic transducers is symmetric about an axis of the first group of ultrasonic transducers. 
     
     
         6 . The method of  claim 5 , wherein the axis is orthogonal to an edge of the two-dimensional array of ultrasonic transducers. 
     
     
         7 . The method of  claim 5 , wherein the phase delay pattern of the first group of ultrasonic transducers is symmetric about the axis of the first group of ultrasonic transducers for an array position adjacent an edge of the two-dimensional array of ultrasonic transducers. 
     
     
         8 . The method of  claim 1 , wherein a phase delay pattern of the first group of ultrasonic transducers comprises at least three distinct timing phases. 
     
     
         9 . The method of  claim 1 , wherein the plurality of array positions comprise a same amount of ultrasonic transducers having a uniform arrangement. 
     
     
         10 . The method of  claim 1 , wherein the activating a plurality of ultrasonic transducers associated with the respective array position is performed concurrently for at least two non-overlapping array positions of the plurality of array positions. 
     
     
         11 . The method of  claim 1 , wherein the activating a plurality of ultrasonic transducers associated with the respective array position is performed consecutively for at least two overlapping array positions of the plurality of array positions offset by one row of ultrasonic transducers. 
     
     
         12 . The method of  claim 1 , wherein the activating a plurality of ultrasonic transducers associated with the respective array position is performed consecutively for at least two overlapping array positions of the plurality of array positions offset by one column of ultrasonic transducers. 
     
     
         13 . The method of  claim 1 , wherein the object is a finger. 
     
     
         14 . The method of  claim 1 , wherein at least one array position of the plurality of array positions comprises ultrasonic transducers that are not activated. 
     
     
         15 . The method of  claim 1 , wherein the first group of ultrasonic transducers and the second group of ultrasonic transducers comprise different ultrasonic transducers of each respective array position of the plurality of ultrasonic transducers. 
     
     
         16 . The method of  claim 1 , wherein at least one ultrasonic transducer is comprised within both the first group of ultrasonic transducers and the second group of ultrasonic transducers. 
     
     
         17 . The method of  claim 1 , wherein the activating comprises:
 transmitting second ultrasonic signals from the first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, wherein a phase delay pattern of the second ultrasonic signals is different than a phase delay pattern of the ultrasonic signals such that the second ultrasonic signals forms the focused ultrasonic beam over a different location of the array position than the ultrasonic signals; and   receiving second reflected ultrasonic signals at the second group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein the reflected ultrasonic signals are for sensing a first pixel of an image and the second reflected ultrasonic signals are for sensing a second pixel of the image.   
     
     
         18 . The method of  claim 1 , wherein the transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers comprises:
 provided an array position of the plurality of array positions extends over an edge of the two-dimensional array, truncating ultrasonic transducers of the first group of ultrasonic transducers from the array position that extend over the edge of the two-dimensional array.   
     
     
         19 . A fingerprint sensor device comprising:
 a two-dimensional array of ultrasonic transducers;   a platen overlying the two-dimensional array of ultrasonic transducers; and   a processor, wherein the processor is configured to:
 define a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, the plurality of array positions each comprising a portion of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, wherein the plurality of array positions are for capturing an image over the two-dimensional array of ultrasonic transducers; 
 define an activation sequence of the plurality of array positions, wherein the activation sequence defines movement of the plurality of array positions over the two-dimensional array of ultrasonic transducers for forming a focused ultrasonic beam at different locations over the two-dimensional array of ultrasonic transducers; 
 for each array position of the plurality of array positions, activate a plurality of ultrasonic transducers associated with the respective array position for capturing a pixel of the image, wherein activating the plurality of ultrasonic transducers comprises:
 transmit ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam for focusing on a fingerprint pattern of a finger in contact with a contact surface of the platen; and 
 receive reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers; and 
 
   perform the activating a plurality of ultrasonic transducers associated with the respective array position according to the activation sequence for each array position of the plurality of array positions.   
     
     
         20 . A non-transitory computer readable storage medium having computer readable program code stored thereon for causing a computer system to perform method of operating a fingerprint sensor comprising a two-dimensional array of ultrasonic transducers, the method comprising:
 defining a plurality of array positions comprising pluralities of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, the plurality of array positions each comprising a portion of ultrasonic transducers of the two-dimensional array of ultrasonic transducers, wherein the plurality of array positions are for capturing an image over the two-dimensional array of ultrasonic transducers;   defining an activation sequence of the plurality of array positions, wherein the activation sequence defines movement of the plurality of array positions over the two-dimensional array of ultrasonic transducers for forming a focused ultrasonic beam at different locations over the two-dimensional array of ultrasonic transducers;   for each array position of the plurality of array positions, activating a plurality of ultrasonic transducers associated with the respective array position for capturing a pixel of the image, the activating comprising:
 transmitting ultrasonic signals from a first group of ultrasonic transducers of the plurality of ultrasonic transducers, wherein at least some ultrasonic transducers of the first group of ultrasonic transducers are phase delayed with respect to other ultrasonic transducers of the first group of ultrasonic transducers, the first group of ultrasonic transducers for forming a focused ultrasonic beam for focusing on a fingerprint pattern of a finger in contact with a contact surface of a platen overlying the two-dimensional array of ultrasonic transducers; and 
 receiving reflected ultrasonic signals at a second group of ultrasonic transducers of the plurality of ultrasonic transducers; and 
   performing the activating a plurality of ultrasonic transducers associated with the respective array position according to the activation sequence for each array position of the plurality of array positions.