Direct digital speaker apparatus having a desired directivity pattern

Abstract

Direct digital speaker apparatus receiving a digital input signal and generating sound accordingly, the apparatus including: (a) an array of pressure-producing elements; and (b) a controller operative to compute a timing pattern determining if and when each pressure-producing element is actuated so as to achieve a desired directivity pattern; wherein said pressure-producing elements have the same amplitude.

What is claimed is: 
     
         1 . Direct digital speaker apparatus receiving a digital input signal and generating sound accordingly, the apparatus comprising:
 an array of pressure-producing elements; and   a controller operative to compute a timing pattern determining if and when each pressure-producing element is actuated so as to achieve a desired directivity pattern;   wherein said pressure-producing elements have the same amplitude.   
     
     
         2 . The direct digital speaker apparatus according to  claim 1 , wherein the apparatus also comprises at least one latch operative to selectively latch at least one subset of said pressure producing elements in at least one latching position thereby; wherein said controller comprises a latch controller operative to receive said digital input signal and to control said at least one latch accordingly. 
     
     
         3 . The direct digital speaker apparatus according to  claim 1 , configured to generate a plurality of directivity patterns, wherein the controller is configured to compute the timing pattern so as to achieve the desired directivity pattern which is selected out of the plurality of directivity patterns which comprises at least omnidirectional and uni-directional directivity patterns. 
     
     
         4 . The direct digital speaker apparatus according to  claim 1 , configured to generate a plurality of directivity patterns, wherein the controller is configured to compute the timing pattern so as to achieve the desired directivity pattern which is selected out of the plurality of directivity patterns which comprises at least omnidirectional, uni-directional and multidirectional directivity patterns. 
     
     
         5 . The direct digital speaker apparatus according to  claim 1 , wherein the controller is operative to compute the timing pattern so as to achieve the desired directivity pattern which corresponds to propagation of sound outward from a given focal point. 
     
     
         6 . The direct digital speaker apparatus according to  claim 1 , wherein is sound produced by the pressure producing elements in front of a surface of the pressure producing elements, wherein the focal point is located at a distance d behind the surface of pressure-producing elements. 
     
     
         7 . The direct digital speaker apparatus according to  claim 1 , wherein the controller is operative to compute the timing pattern determining if and when each pressure-producing element is actuated so as to achieve the desired directivity pattern in which different propagation angles are used for the directivity pattern in different planes. 
     
     
         8 . The direct digital speaker apparatus according to  claim 1 , wherein different subsets of one or more of the pressure-producing elements have different propagation angles, wherein in a per-clock operation of the controller the controller is operative to determine how many moving elements should move during a current clock based on the digital input signal and to determine which moving elements should move during the current clock by selecting a subset of pressure-producing element based on its matching to the desired propagation angle. 
     
     
         9 . The direct digital speaker apparatus according to  claim 1 , wherein the desired directivity pattern is a cylindrical pattern. 
     
     
         10 . The direct digital speaker apparatus according to  claim 1 , wherein the controller is operative to define at least one attribute of the sound to correspond to at least one characteristic of the digital input signal, thereby defining a highest frequency for the sound, wherein each of the pressure-producing elements defines a cross section which is perpendicular to a respective axis along which the pressure-producing element is constrained to travel alternately back and forth, wherein the largest dimension of each of the cross-sections of the pressure-producing elements is smaller than the wavelength of the highest frequency. 
     
     
         11 . The direct digital speaker apparatus according to  claim 1 , wherein the direct digital speaker is a Microelectromechanical system (MEMS) speaker which is fabricated using MEMS manufacturing techniques. 
     
     
         12 . The direct digital speaker apparatus according to  claim 1 , wherein the controller is operative to compute the timing pattern so as to achieve the desired directivity pattern which comprises unidirectional sound in at least two different directions so as to serve listeners located at different positions. 
     
     
         13 . The direct digital speaker apparatus according to  claim 12 , configured to generate different sound streams be simultaneously perceived by the listeners positioned at the different positions, wherein the controller is operative to compute the timing pattern so as to achieve a desired directivity pattern in which the different sound streams are produced in the different directions. 
     
     
         14 . The direct digital speaker apparatus according to  claim 1 , comprising a plurality of arrays of pressure-producing elements; wherein the controller is operative to compute different timing patterns for the different arrays, and to operate the plurality of arrays simultaneously in accordance with the different timing patterns, thereby to obtain the single desired directivity pattern. 
     
     
         15 . The direct digital speaker apparatus according to  claim 14 , wherein each of the plurality of arrays is of the same order of magnitude of the sound wave's length. 
     
     
         16 . The direct digital speaker apparatus according to  claim 1 , wherein each of the pressure-producing elements is operative to produce both positive pressure pulses and negative pressure pulses. 
     
     
         17 . Direct digital speaker apparatus receiving a digital input signal and generating sound accordingly, the apparatus comprising:
 A plurality of arrays of pressure-producing elements; and   a controller operative to compute a timing pattern determining if and when each pressure-producing element in the plurality of arrays is actuated so as to achieve a desired directivity pattern;   wherein in each of the arrays the pressure-producing elements have the same amplitude;   wherein different arrays of the plurality of arrays have different characteristics which includes at least one of different clock frequencies, different pressure-producing element sizes and different amplitudes.   
     
     
         18 . The direct digital speaker apparatus according to  claim 17 , wherein a size of each of the arrays is of the same order of magnitude of the sound wave's length. 
     
     
         19 . The direct digital speaker apparatus according to  claim 17 , configured to generate a plurality of directivity patterns, wherein the controller is configured to compute the timing pattern so as to achieve the desired directivity pattern which is selected out of the plurality of directivity patterns which comprises at least omnidirectional, uni-directional and multidirectional directivity patterns.