WIDTH FLEXURAL RESONATOR AND COUPLED MODE FILTER

• US 3,614,483 A
• Filed: 06/24/1970
• Issued: 10/19/1971
• Est. Priority Date: 06/24/1970
• Status: Expired due to Term

• Current Assignee: Don A. Berlincourt
• Original Assignee: Don A. Berlincourt
• Inventors: Berlincourt, Don A.
• Primary Examiner(s): Hirshfield, Milton O.
• Assistant Examiner(s): Reynolds, B. A.
• Application Number:
  US05/049,497
• Time in Patent Office: 482 Days
• Field of Search: 310/8,1,8.2,8.3,8.5,8.6,9.5,9.7,9.8 333/72,30
• US Class Current: 310/321
• CPC Class Codes: H03H 9/176 consisting of ceramic material H03H9/177, H03H9/178 take precedence
• CPC Class Codes: H03H 9/562 comprising a ceramic piezoelectric layer
• CPC Class Codes: H03H 9/566 Electric coupling means therefor H03H9/0095 takes precedence

Abstract

Ceramic and crystal resonators and coupled mode filters are disclosed. They are platelike assemblies and operate in the width flexural mode. The operating frequency is determined primarily by the width and thickness of the assembly.

Claims

1. A piezoelectric resonator comprising:

a first elongated plate, at least a portion of which remote from the ends thereof, is piezoelectric and adapted to vibrate in extension parallel to the width of the plate then subjected to an alternating electric field;

a second elongated plate secured to said first plate in face-toface relation and adapted to restrain said width extensional vibrations and thereby induce width flexural vibrations;

electrode means secured to said first plate and adapted to apply an alternating electric field to a piezoelectric region of said first plate remote from the ends thereof in a direction which would induce said width extensional vibrations in the absence of the restraint imposed by said second plate;

said electrode means cooperating with the piezoelectric material adjacent thereto and with said second plate to establish a width flexural resonator.

2. A piezoelectric resonator as described in claim 1 further comprising damping means engaging the plates at end regions thereof to suppress length related vibrations.

3. A piezoelectric resonator as described in claim 1 in which the second plate is similar to the first plate and has electrode means secured thereto as on the first plate.

4. A piezoelectric resonator as described in claim 3 in which the electrode means are secured to the major faces of the two plates.

5. A piezoelectric resonator as described in claim 3 in which the electrode means are secured to the long edge faces of the two plates.

6. A Piezoelectric resonator as described in claim 4 further comprising a metal plate sandwiched between the said first and second plates.

7. A piezoelectric resonator as described in claim 6 in which said metal plate provides electrical connections to electrode means secured to the adjacent faces of the said first and second plates.

8. A piezoelectric resonator as described in claim 6 in which said metal plate functions as electrode means for the adjacent faces of the said first and second plates.

9. A piezoelectric resonator as described in claim 1 in which the electrode means are secured to the major faces of the first plate and said second plate is a metal plate.

10. A piezoelectric resonator as described in claim 9 in which said metal plate provides electrical connection to electrode means on the adjacent face of the first plate.

11. A piezoelectric resonator as described in claim 9 in which said metal plate functions as electrode means for the adjacent face of the first plate.

12. A piezoelectric resonator as described in claim 1 in which said first plate is comprised of lead zirconate-lead titanate.

13. A piezoelectric resonator as described in claim 1 in which said first plate is an X-cut quartz crystal plate with width parallel to the Y-axis.

14. A piezoelectric band-pass filter comprising:

a first elongated plate having substantially uniform width and thickness, at least a portion of said plate remote from the ends thereof being piezoelectric and adapted to vibrate in extension parallel to the width when subjected to an alternating electric field;

a second elongated plate having uniform width and thickness secured to said first plate in face-to-face relation and adapted to restrain said width extensional vibrations and thereby induce width flexural vibrations;

a plurality of electrode means secured to said first plate, each adapted to apply an alternating electric field through a piezoelectric region of said first plate remote from the ends thereof in a direction which would induce said width extensional vibrations in the absence of the restraint imposed by said second plate;

each of said electrode means cooperating with the piezoelectric material adjacent thereto and with said second plate to establish a width flexural resonator;

the spacing between adjacent resonators being sufficiently small so that elastic coupling exists between adjacent resonators, thereby establishing a band-pass characteristic.

15. A piezoelectric band-pass filter as described in claim 14 further comprising damping means engaging the plates at end regions thereof to suppress length related vibrations.

16. A piezoelectric band-pass filter as described in claim 14 in which the second plate is similar to the first plate and has electrode means secured thereto as in the first plate.

17. A piezoelectric band-pass filter as described in claim 16 in which the electrode means are secured to the major faces of the two plates.

18. A piezoelectric band-pass filter as described in claim 16 in which the electrode means are secured to the long edge faces of the two plates.

19. A piezoelectric band-pass filter as described in claim 17 further comprising a metal plate sandwiched between the said first and second plates.

20. A piezoelectric band-pass filter as described in claim 19 in which said metal plate provides electrical connections to electrode means secured to the adjacent faces of the said first and second plates.

21. A piezoelectric band-pass filter as described in claim 19 in which said metal plate functions as electrode means for the adjacent faces of the said first and second plates.

22. A piezoelectric band-pass filter as described in claim 14 in which the electrode means are secured to the major faces of the first plate and said second plate is a metal plate.

23. A piezoelectric band-pass filter as described in claim 22 in which said metal plate provides electrical connection to electrode means on the adjacent face of the firSt plate.

24. A piezoelectric band-pass filter as described in claim 22 in which said metal plate functions as electrode means for the adjacent face of the first plate.

25. A piezoelectric band-pass filter as described in claim 14 in which said first plate is comprised of lead zirconate-lead titanate.

26. A piezoelectric band-pass filter as described in claim 14 in which said first plate is an X-cut quartz crystal plate with width parallel to the Y-axis.