Acoustic device

• US 20020027999A1
• Filed: 10/18/2001
• Published: 03/07/2002
• Est. Priority Date: 09/02/1995
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: New Transducers Limited (Alphabet Inc.)
• Inventors: Harris, Neil, Colloms, Martin, Azima, Henry
• Granted Patent: US 6,904,154 B2
• Time in Patent Office: Days
• US Class Current: 381/431
• CPC Class Codes: B42D 15/022 combined with permanently fastened sound-producing or light-emitting means or carrying sound records
• CPC Class Codes: B60R 11/0217 for loud-speakers
• CPC Class Codes: G06F 1/1601 Constructional details related to the housing of computer displays, e.g. of CRT monitors, of flat displays constructional details related to flat displays integrated in a portable computer, e.g. laptop, handheld computer G06F1/1637; constructional details related to television receivers H04N5/64
• CPC Class Codes: G06F 1/1605 Multimedia displays, e.g. with integrated or attached speakers, cameras, microphones
• CPC Class Codes: G06F 1/1616 with folding flat displays, e.g. laptop computers or notebooks having a clamshell configuration, with body parts pivoting to an open position around an axis parallel to the plane they define in closed position
• CPC Class Codes: G06F 1/1624 with sliding enclosures, e.g. sliding keyboard or display
• CPC Class Codes: G06F 1/1688 the I/O peripheral being integrated loudspeakers
• CPC Class Codes: G06F 9/02 using wired connections, e.g. plugboards
• CPC Class Codes: G07F 9/02 Devices for alarm or indication, e.g. when empty; Advertising arrangements in coin-freed apparatus alarms or warning devices indicating the interruption of flow to be metered G07F15/10
• CPC Class Codes: G10H 1/32 Constructional details
• CPC Class Codes: H04N 5/642 Disposition of sound reproducers
• CPC Class Codes: H04R 1/021 incorporating only one transducer
• CPC Class Codes: H04R 1/025 Arrangements for fixing loudspeaker transducers, e.g. in a box, furniture
• CPC Class Codes: H04R 1/028 associated with devices performing functions other than acoustics, e.g. electric candles
• CPC Class Codes: H04R 1/24 Structural combinations of separate transducers or of two parts of the same transducer and responsive respectively to two or more frequency ranges
• CPC Class Codes: H04R 1/26 Spatial arrangements of separate transducers responsive to two or more frequency ranges
• CPC Class Codes: H04R 1/2811 for loudspeaker transducers
• CPC Class Codes: H04R 1/2834 for loudspeaker transducers
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00
• CPC Class Codes: H04R 2201/021 Transducers or their casings adapted for mounting in or to a wall or ceiling
• CPC Class Codes: H04R 2205/024 : Positioning of loudspeaker enclosures for spatial sound reproduction
• CPC Class Codes: H04R 2307/029 : Diaphragms comprising fibres
• CPC Class Codes: H04R 2307/201 : Damping aspects of the outer suspension of loudspeaker diaphragms by addition of additional damping means
• CPC Class Codes: H04R 2400/07 : Suspension between moving magnetic core and housing
• CPC Class Codes: H04R 2440/03 : Resonant bending wave transducer used as a microphone
• CPC Class Codes: H04R 2440/05 : Aspects relating to the positioning and way or means of mounting of exciters to resonant bending wave panels
• CPC Class Codes: H04R 2440/07 : Loudspeakers using bending wave resonance and pistonic motion to generate sound
• CPC Class Codes: H04R 2499/11 : Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 2499/13 : Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 2499/15 : Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops
• CPC Class Codes: H04R 3/04 : for correcting frequency response
• CPC Class Codes: H04R 3/14 : Cross-over networks
• CPC Class Codes: H04R 31/003 : for diaphragms or their outer suspension
• CPC Class Codes: H04R 5/02 : Spatial or constructional arrangements of loudspeakers
• CPC Class Codes: H04R 5/027 : Spatial or constructional arrangements of microphones, e.g. in dummy heads
• CPC Class Codes: H04R 7/045 : using the distributed mode principle, i.e. whereby the acoustic radiation is emanated from uniformly distributed free bending wave vibration induced in a stiff panel and not from pistonic motion
• CPC Class Codes: H04R 7/06 : comprising a plurality of sections or layers
• CPC Class Codes: H04R 7/08 : comprising superposed layers separated by air or other fluid
• CPC Class Codes: H04R 7/10 : comprising superposed layers in contact
• CPC Class Codes: H04R 7/12 : Non-planar diaphragms or cones
• CPC Class Codes: H04R 7/20 : Securing diaphragm or cone resiliently to support by flexible material, springs, cords, or strands
• CPC Class Codes: H04R 9/025 : Magnetic circuit
• CPC Class Codes: H04R 9/045 : Mounting H04R9/043 takes precedence
• CPC Class Codes: H04R 9/066 : using the principle of inertia
• CPC Class Codes: Y10T 29/49005 : Acoustic transducer

Abstract

Acoustic device including a member extending transversely of its thickness and capable of sustaining bending waves at least over an intendedly consequentially acoustically active area of the transverse extent of said member, the member having, by reason of orderly design methodology disclosed and claimed, a distribution of resonant modes of its natural bending wave vibration at least over said area that is dependent on values of particular parameters of said members, including geometrical configuration and directional bending stiffness(es), which values have been selected to predetermine said distribution of natural resonant modes being consonant with required achievable acoustic action of said member for operation of said device over a desired operative acoustic frequency range.

Claims

1. A method of making a resonant acoustic object adapted for operation over an operative frequency range, the object comprising a member extending transversely of its thickness and capable of sustaining bending waves over an active area of the transverse extent of the member, wherein the distribution of resonant modes of bending wave vibration over the active area of the member depends on the values of physical parameters of geometry, bending stiffness, areal mass distribution and damping of the member, the method comprising:

selecting, through analysis, values of said parameters to effect a desired distribution of the resonant bending wave modes in frequency over the active area of the member; and

making the member having said selected values of said parameters.

2. A method according to claim 1, wherein said parameters are associated with at least two different directions across the active area of the member, and the values of said parameters are selected such that the frequencies of the resonant bending wave modes along one of said different directions substantially do not overlap with the frequencies of the resonant bending wave modes along the other of said different directions.

3. A method according to claim 2, wherein said different directions are substantially perpendicular.

4. A method according to claim 2, wherein the values of said parameters are selected such that the frequencies of the resonant bending wave modes along said different directions are interleaved and spread so that there are substantially minimal clusterings and disparities of spacings of said frequencies.

5. A method according to claim 4, wherein said different directions are substantially perpendicular.

6. A method according to claim 1, wherein said parameters comprise the lengths of the major and minor axes of the member.

7. A method according to claim 6, wherein the lengths of said major and minor axes are selected such that the frequencies of the resonant bending wave modes along one of said axes substantially do not overlap with the frequencies of the resonant bending wave modes along the other of said axes.

8. A method according to claim 7, wherein the values of said parameters are selected such that the frequencies of the resonant bending wave modes along said axes are interleaved and spread so that there are substantially minimal clusterings and disparities of spacings of said frequencies.

9. A method of making a loudspeaker adapted for operation over an operative frequency range, the loudspeaker including a member extending transversely of its thickness and capable of sustaining bending waves over an active area of the transverse extent of the member, and a transducer coupled to the member to vibrate the member, wherein the member when vibrating has a desired frequency distribution of resonant bending wave modes over the active area of the member, the method comprising:

analysing the distribution of resonant bending wave vibration of the member, including determining at least one region of the active area of the member where a plurality of lower frequency resonant bending wave modes in the operative frequency range have vibrationally active anti-nodes; and

coupling a transducer to a said at least one region of the active area of the member so that the transducer will couple with the lower frequency resonant bending wave modes.

10. A method of making a loudspeaker adapted for operation over an operative frequency range, the loudspeaker including a member extending transversely of its thickness and capable of sustaining bending waves over an active area of the transverse extent of the member, and a transducer coupled to the member to vibrate the member, wherein the distribution of resonant modes of bending wave vibration over the active area of the member depends on the values of physical parameters of geometry, bending stiffness, areal mass distribution and damping of the member, the method comprising:

selecting, through analysis, values of said parameters to effect a desired frequency distribution of the resonant bending wave modes over the active area of the member;

making the member having said selected values of said parameters;

analysing the distribution of resonant bending wave vibration of the member, including determining at least one region of the active area of the member where a plurality of lower frequency resonant bending wave modes in the operative frequency range have vibrationally active anti-nodes; and

coupling a transducer to a said at least one region of the active area of the member so that the transducer will couple with the lower frequency resonant bending wave modes.

11. A method according to claim 10, wherein said parameters are associated with at least two different directions across the active area of the member, and the values of said parameters are selected such that the frequencies of the resonant bending wave modes along one of said different directions substantially do not overlap with the frequencies of the resonant bending wave modes along the other of said different directions.

12. A method according to claim 11, wherein said different directions are substantially perpendicular.

13. A method according to claim 11, wherein the values of said parameters are selected such that the frequencies of the resonant bending wave modes along said different directions are interleaved and spread so that there are substantially minimal clusterings and disparities of spacings of said frequencies.

14. A method according to claim 11, wherein said different directions are substantially perpendicular.

15. A method according to claim 10, wherein said parameters comprise the lengths of the major and minor axes of the member.

16. A method according to claim 15, wherein the lengths of said major and minor axes are selected such that the frequencies of the resonant bending wave modes along one of said axes substantially do not overlap with the frequencies of the resonant bending wave modes along the other of said axes.

17. A method according to claim 16, wherein the values of said parameters are selected such that the frequencies of the resonant bending wave modes along said axes are interleaved and spread so that there are substantially minimal clusterings and disparities of spacings of said frequencies.

19. A loudspeaker according to claim 18, wherein said parameters are associated with at least two different directions across the active area of the member, and the values of said parameters are selected such that the frequencies of the resonant bending wave modes along one of said different directions substantially do not overlap with the frequencies of the resonant bending wave modes along the other of said different directions.

20. A loudspeaker according to claim 19, wherein said different directions are substantially perpendicular.

21. A loudspeaker according to claim 19, wherein the values of said parameters are selected such that the frequencies of the resonant bending wave modes along said different directions are interleaved and spread so that there are substantially minimal clusterings and disparities of spacings of said frequencies.

22. A loudspeaker according to claim 19, wherein said different directions are substantially perpendicular.

23. A loudspeaker according to claim 18, wherein said parameters comprise the lengths of the major and minor axes of the member.

24. A loudspeaker according to claim 23, wherein the lengths of said major and minor axes are selected such that the frequencies of the resonant bending wave modes along one of said axes substantially do not overlap with the frequencies of the resonant bending wave modes along the other of said axes.

25. A loudspeaker according to claim 24, wherein the values of said parameters are selected such that the frequencies of the resonant bending wave modes along said axes are interleaved and spread so that there are substantially minimal clusterings and disparities of spacings of said frequencies.

26. A loudspeaker according to claim 23, wherein the member is substantially rectangular and has substantially equal bending stiffness along said axes, and the lengths of said axes are unequal by about 13.4% to about 37%.

27. A loudspeaker according to claim 26, wherein the transducer is located at a position corresponding to about {fraction (3/7)}, {fraction (4/9)} or {fraction (5/13)} of the lengths of said axes used as coordinates from a corner of the member.

28. A loudspeaker according to claim 23, wherein the member is of substantially true elliptical shape and has substantially equal bending stiffness along said axes, and the lengths of said axes are unequal by about 18.2% to about 34%.

29. A loudspeaker according to claim 28, wherein the ratio of the length of the major axis to the length of the minor axis is about 1.182:

1, and the transducer is located at a position from the center of the member corresponding to about 0.43 of the length of and along the major axis, and 0.20 of the length of and along the minor axis.

30. A loudspeaker according to claim 23, wherein the member is of substantially super-elliptical shape with its super-ellipse defining power factor determined for any particular relative dimensional values of said axes, the member has substantially equal bending stiffness along said axes, the lengths of said axes are unequal by about 13% to about 32%, and said defining power factor is about 3.5 to about 4.

31. A loudspeaker according to claim 30, wherein the transducer is located at a position from the edge of the member that is about 15% along a line from the edge to the center of the member.

32. A loudspeaker according to claim 23, wherein the member is substantially rectangular, and the transducer is located at a position corresponding to about {fraction (3/7)}, {fraction (4/9)} or b {fraction (5/13)} of the lengths of said axes used as coordinates from a corner of the member.

33. A loudspeaker according to claim 23, wherein the member is of substantially true elliptical shape, the ratio of the length of the major axis to the length of the minor axis is about 1.182:

1, and the transducer is located at a position from the center of the member corresponding to about 0.43 of the length of and along the major axis, and 0.20 of the length of and along the minor axis.

34. A loudspeaker according to claim 23, wherein the member is of substantially super-elliptical shape with its super-ellipse defining power factor determined for any particular relative dimensional values of said axes, and the transducer is located at a position from the edge of the member that is about 15% along a line from the edge to the center of the member.

35. A loudspeaker according to claim 18, wherein the member has an area smaller than about 0.1 square meter, a lowest bending wave frequency above about 100 Hz, and a bending stiffness less than about 10 Newtonmeters.

36. A loudspeaker according to claim 18, wherein the member has an area in the range of about 0.1 to about 0.3 square meter, and a bending stiffness in the range of about 5 to about 50 Newtonmeters.

37. A loudspeaker according to claim 18, wherein the member has an area in the range of about 0.3 to about 1 square meter, and a bending stiffness greater than about 20 Newtonmeters.

38. A loudspeaker according to claim 37, wherein the member has a bending stiffness in the range of about 50 to about 500 Newtonmeters.

39. A loudspeaker according to claim 18, wherein the member has an area greater than about 1 square meter, and a bending stiffness greater than about 25 Newtonmeters.

40. A loudspeaker according to claim 18, wherein the operative frequency range spans more than 4 kHz.

41. A loudspeaker according to claim 18, wherein the operative frequency range includes the coincidence frequency of the member.

42. A loudspeaker according to claim 41, wherein the operative frequency range extends below, through and above the coincidence frequency of the member.

18. A loudspeaker adapted for operation over an operative frequency range, comprising:

a member extending transversely of its thickness and capable of sustaining bending waves over an active area of the transverse extent of the member, the member having physical parameters of geometry, bending stiffness, areal mass distribution and damping, the values of which affect the distribution of resonant modes of bending wave vibration over the active area of the member, said parameters having selected values such that the resonant bending wave modes are beneficially distributed in frequency over the active area of the member, and

a transducer coupled to the member in a region of the active area of the member where a plurality of lower frequency resonant bending wave modes in the operative frequency range have vibrationally active anti-nodes so that the transducer will couple with the lower frequency bending wave modes.