Stable acoustic delay surface wave motion transducer systems

Claim 2

Transducer means comprising; flexure means having first and second opposed flexible surface layer means for separately propagating respective first and second acoustic waves along first and second respective predetermined paths therein, first and second exciter means for exciting and propagating said respective first and second acoustic waves along said first and second respective predetermined paths in response to respective first and second exciter electric signals, first and second receiver means along said respective first and second predetermined paths for receiving and converting said respective first and second acoustic waves into respective first and second receiver electric signals, first and second respective driver circuit means for coupling said first receiver means to said first exciter means and for coupling said second receiver means to said second exciter means for forming, with said respective first and second opposed flexible surface layer means, first and second oscillatory driver circuit means oscillating at different respective first and second frequencies, at least said first oscillatory driver circuit means including: phase detector means responsive jointly to the phases of said first respective exciter and receiver electric signals, and tunable oscillation frequency dtermining means responsive to said phase detector means, and signal processor means jointly responsive to said first and second oscillatory driver circuit means for deriving a measure of the flexure of said flexure means from said first and second frequencies for supply to utilization means.

Claim 3

Apparatus as described in claim 1 wherein said tunable oscillation frequency determining means includes voltage controlled oscillator means responsive to said phase detector means.

Claim 4

Apparatus as described in claim 2 additionally including integrator means interposed in series relation between said phase detector means and said voltage controlled oscillator means.

Claim 5

Apparatus as described in claim 2 additionally including phase shifter means for imposing a relative 90* phase shift on said first exciter electric signal before application to said phase detector means.

Claim 6

Apparatus as described in claim 2 additionally including signal amplitude subtractor means having output means coupled to first input means of said phase detector means and having first and second input means, said first input means of said amplitude subtractor means being supplied with said receiver electric signal.

Claim 7

Apparatus as described in claim 5 additionally including signal amplitude divider means for coupling to said second input means of said signal subtractor means a version of said exciter electric signal.

Claim 8

Apparatus as described in claim 1 wherein said tunable oscillation frequency determining means includes voltage controlled filter means responsive to said phase detector means.

Claim 9

Apparatus as described in claim 7 additionally including phase shifter means for imposing a relative 90* phase shift on said first receiver electric signal before application to said phase detector means.

Claim 10

Apparatus as described in claim 1 wherein said second oscillatory driver circuit means includes: sEcond phase detector means responsive jointly to the phases of said second respective exciter and receiver electric signals, and second tunable oscillation frequency determining means responsive to said second phase detector means.

Claim 11

Apparatus as described in claim 9 wherein said first and second opposed flexible surface layer means are oriented with respect to the predetermined flexure direction of said flexure means so as to be stressed in opposite senses for a predetermined flexure of said flexure means.

Claim 12

Transducer means comprising: flexure means having first and second opposed flexible surface layer means for separately propagating respective first and second acoustic waves along first and second respective predetermined paths therein, first and second exciter means for exciting and propagating said respective first and second acoustic waves along said respective first and second predetermined paths in response to respective first and second exciter electric signals, first and second receiver means along said respective first and second predetermined paths for receiving and converting said respective first and second acoustic waves into respective first and second receiver electric signals, first and second respective driver circuit means for coupling said first receiver means to said first exciter means and said second receiver means to said second exciter means for forming, with said respective first and second opposed flexible surface layer means, first and second oscillatory driver circuit means oscillating at different respective first and second frequencies, at least said first oscillatory driver circuit means including: first mixer means responsive to said first receiver means and to voltage controlled oscillator means for controlling the frequency of said voltage controlled oscillator means, second mixer means responsive to said voltage controlled oscillator means for supplying said first exciter electric signal to said first exciter means, and pulse generator means for supplying an output from said second mixer means in a first discrete time interval and for enabling said first mixer means to control the frequency of said voltage controlled oscillator means in a second discrete time interval, and signal processor means jointly responsive to said first and second oscillatory driver circuit means for deriving a measure of the flexure of said flexure means from said first and second frequencies for supply to utilization means.

Claim 13

Transducer means comprising: flexure means having first and second opposed flexible surface layer means for separately propagating respective first and second acoustic waves along first and second respective predetermined paths therein, first and second exciter means for exciting and propagating said respective first and second acoustic waves along said respective first and second predetermined paths in response to respective first and second exciter electric signals, first and second receiver means along said respective first and second predetermined paths for receiving and converting said respective first and second acoustic waves into respective first and second receiver electric signals, first and second respective driver circuit means for coupling said first receiver means to said first exciter means and said second receiver means to said second exciter means for forming, with said respective first and second opposed flexible surface layer means, first and second oscillatory driver circuit means oscillating at different respective first and second frequencies, at least said first oscillatory driver circuit means including: first mixer means responsive to said first receiver means and to voltage controlled oscillator means for controlling the frequency of said voltage controlled oscillator means, second mixer means responsive to said voltage controlled oscillator means for supplying said first exciter electric signal to said first exciter means, and pulse generator means for supplying an output from said second mixer means in a first discrete time interval and for enabling said first mixer means to control the frequency of said voltage controlled oscillator means in a second discrete time interval, and signal processor means jointly responsive to said first and second oscillatory driver circuit means for deriving a measure of the flexure of said flexure means from said first and second frequencies for supply to utilization means.

Claim 14

Apparatus as described in claim 11 wherein said pulse generator means additionally prevents any output from said first mixer means occurring in a third discrete time interval between said first and second discrete time intervals from controlling said voltage controlled oscillator means.

Claim 15

Apparatus as described in claim 12 additionally including integrator means interposed in series relation between said first mixer means and said voltage controlled oscillator means.

Claim 16

Apparatus as described in claim 12 wherein said first and second opposed flexible surface layer means are oriented with respect to the predetermined flexure direction of said flexure means so as to be stressed in opposite senses for a predetermined flexure of said flexure means.