Acoustic surface wave transmission device

Claim 2

A signal transmission device comprising: a medium propagative of acoustic surface waves; means including an input transducer responsive to input signals for launching acoustic surface waves along a predetermined path on said medium, the fronts of said waves having a width which changes during propagation; an acoustic lens, including a material on said medium exhibiting an acoustical refractive index greater than one, disposed in said path for modifying the width change of said fronts; and means including an output transducer responsive to said acoustic surface waves transmitted through said lens for developing an output signal.

Claim 3

A device as defined in claim 1 in which said material decreases the velocity of propagation of said waves so that said lens is convergent.

Claim 4

A device as defined in claim 1 in which said lens converges said acoustic waves to a focal point further along said path than said output transducer, and including an element attenuative of said surfaces waves disposed on said medium in the vicinity of said focal point.

Claim 5

A device as defined in claim 1 in which said output transducer includes a series of interleaved electrodes disposed across the path of said waves, and in which the distance of said output transducer along said path beyond said lens as well as the length of said electrodes are selected to obtain a predetermined impedance for said output transducer while optimizing the interaction of said output transducer with said surface waves.

Claim 6

A device as defined in claim 1 in which at least one of said input and output transducers is coupled to a plane of reference potential, and in which said acoustic lens also is coupled to said plane of reference potential.

Claim 7

A device as defined in claim 1 in which said lens is convergent and in which said output transducer has a width across the path less than that of said input transducer.

Claim 8

A device as defined in claim 1 in which said lens is divergent and in which said output transducer has a width across the path of said waves greater than that of said input transducer.

Claim 9

A device as defined in claim 4 which includes a second output transducer similar to the first output transducer but spaced on said medium on the other side of said input transducer than said first output transducer, which further includes a second acoustic lens disposed in the propagation path between said input transducer and said second output transducer, and in which the electrodes of said second output transducer have a different length from those of said first output transducer so that said second output transducer presents an impedance substantially different from that of said first output transducer.

Claim 10

A device as defined in claim 8 in which said second acoustic lens exhibits a refractive power substantially different from that of the first acoustic lens.

Claim 11

A device as defined in claim 1 in which said acoustic lens curves the fronts of said acoustic waves and in which interactive portions of said output transducer are correspondingly curved.

Claim 12

A signal transmission device comprising: a medium capable of propagating acoustic surface waves; means including an electro-acoustic input transducer responsive to electrical input signals for launching acoustic surface waves along a predetermined path on a surface of said medium; acoustic surface wave lens means for focusing acoustic surface waves on said medium, comprising a substantially two-dimensional lens pattern disposed on said surface in said path to intercept surface waves propagated therealong and being composed of a material which conducts surface waves at a velocity different from the velocity of propagation of surface waves on said medium; and means including an electro-acoustic output transducer on said surface of said medium responsive to said acoustic surface waves transmitted through said lens pattern for developing electrical output signals.

Claim 13

A signal transmission device comprising: a medium capable of propagating acoustic surface waves; means including an electro-acoustic input transducer responsive to electrical input signals for launching acoustic surface waves along a predetermined path on a surface of said medium; acoustic surface wave lens means for focusing acoustic surface waves on said medium, comprising a substantially two-dimensional lens pattern disposed on said surface in said path to intercept surface waves propagated therealong and being composed of a material which conducts surface waves at a velocity different from the velocity of propagation of surface waves on said medium; and means including an electro-acoustic output transducer on said surface of said medium responsive to said acoustic surface waves transmitted through said lens pattern for developing electrical output signals.