(19)
(11) EP 0 973 149 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
27.12.2000 Bulletin 2000/52

(43) Date of publication A2:
19.01.2000 Bulletin 2000/03

(21) Application number: 99305633.2

(22) Date of filing: 15.07.1999
(51) International Patent Classification (IPC)7: G10K 9/12, G01H 11/06, B06B 1/02
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 16.07.1998 US 116271
27.04.1999 US 300200

(71) Applicant: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
Cambridge, MA 02139 (US)

(72) Inventor:
  • Pompei, Frank Joseph
    Cambridge, MA 02139 (US)

(74) Representative: Carpenter, David 
MARKS & CLERK, Alpha Tower, Suffolk Street Queensway
Birmingham B1 1TT
Birmingham B1 1TT (GB)

   


(54) Ultrasonic transducers


(57) Sonic transducers utilize resonant cavities of varying depths to achieve wide operational bandwidth. The transducers (29) may include a conductive membrane (38) spaced apart from one or more backplate electrodes (32a,32b). In one approach, spacing is achieved using a dielectric spacer (34) having a series of depressions (36) arranged in a pattern, the depressions forming cavities each resonant at a predetermined frequency. In another approach, the conductive membrane (62) is piezoelectrically active, and the transducer is simultaneously driven in both piezoelectric and electrostatic modes.






Search report