WO1994001979A1 - Enceinte acoustique a commande hydraulique - Google Patents

Enceinte acoustique a commande hydraulique Download PDF

Info

Publication number
WO1994001979A1
WO1994001979A1 PCT/US1992/005771 US9205771W WO9401979A1 WO 1994001979 A1 WO1994001979 A1 WO 1994001979A1 US 9205771 W US9205771 W US 9205771W WO 9401979 A1 WO9401979 A1 WO 9401979A1
Authority
WO
WIPO (PCT)
Prior art keywords
cone
loudspeaker
hydraulic
hydraulic cylinder
enclosure
Prior art date
Application number
PCT/US1992/005771
Other languages
English (en)
Inventor
Michael J. Parrella
Scott Miller
Original Assignee
Noise Cancellation Technologies, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Noise Cancellation Technologies, Inc. filed Critical Noise Cancellation Technologies, Inc.
Priority to PCT/US1992/005771 priority Critical patent/WO1994001979A1/fr
Publication of WO1994001979A1 publication Critical patent/WO1994001979A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R23/00—Transducers other than those covered by groups H04R9/00 - H04R21/00

Definitions

  • This invention relates to a unique means of powering a loudspeaker, namely, by the use of a hydraulic drive system.
  • a loudspeaker powered by this type of actuator is not extremely efficient, but has properties which make it well-suited to the reproduction of audio signals.
  • Recent advances in the manufacture of hydraulic servovalves and pumps and in control systems make it possible to use a hydraulic actuator and an open-loop control system rather than an electromagnetic actuator to drive a loudspeaker cone such that high sound pressure levels are produced even at low frequencies.
  • 5,060,274 propose a hydraulically driven speaker which involves the use of a high frequency pressure control device and pressure and position feedback.
  • the pressure control device, feedback transducers and control electronics of such a device are not easily or inexpensively obtained.
  • the proposed invention circumvents these shortcomings by using commonly available components. Additionally, the device may be operated using pneumatic power rather than hydraulic power.
  • Another object of this invention is to provide a loudspeaker with a hydraulic actuator and servovalve. Another object of this invention is to provide a hydraulic power source to drive the cone in a loudspeaker.
  • a further object of this invention is to provide a loudspeaker actuator with essentially no damping characteristics.
  • Fig. 1 shows the plan and side view of a typical electromagnetic loudspeaker driver
  • Fig.2 shows a diagrammatic view of a conventional bandpass loudspeaker
  • Fig. 3 shows a graph of the plot of SPL versus frequency
  • Fig. 4 shows a diagrammatic view of a hydraulic powered driver
  • Fig. 5 shows a diagrammatic view of a hydraulic bandpass loudspeaker
  • Fig. 6 shows a graph of the plot of SPL versus frequency for the loudspeaker of
  • Fig. 7 shows a diagrammatic view of a complex hydraulic bandpass enclosure.
  • a typical loudspeaker driver 10 is shown in Figure 1.
  • the cone 11 which displaces air to make sound, is driven by a voice coil 12 which sits inside a magnetic structure 13.
  • the electromagnetic coupling between the voice coil and the magnet allows a current passed through the coil to result in a force on the voice coil.
  • This coupling also induces a back-EMF as a result of the voice coil's velocity which is essentially a dissipator of energy. This limits the efficiency of the device at certain frequencies.
  • Enclosure 20 has speaker 21 and tuned aperture 22.
  • a hydraulic actuator and servovalve is used in place of the electromagnetic device, the resulting arrangement is more like Figure 4, in which the hydraulic actuator 21 is coupled directly to the speaker cone 22.
  • a servovalve driven actuator is basically a velocity source since flow through the servovalve is proportional to the electrical input signal.
  • the driver of a conventional speaker is a source of force in general.
  • the above-mentioned cone may be any shape or material required to displace air and support the operating loads. Indeed, another advantage of the present invention is that low cone mass is no longer a necessary design condition. If this hydraulic loudspeaker is placed in the bandpass box of Figure 5, a bandpass characteristic similar to that shown in Figure 6 results. If this is too irregular, it is possible to build a more complex enclosure with more degrees of freedom.
  • This type of enclosure 30 like that in figure 7, results in a flatter bandpass characteristic, although some type of damping may need to be added to the system.
  • These enclosures are only used as examples.
  • the device can be used with virtually any enclosure geometry. These measures should not be necessary with the advent of digital devices or even analog circuits which can "equalize” the response of such a device.
  • the electrical signal driving the servovalve can be conditioned through an analog or digital circuit which would artificially "flatten" the response of the device. This circuit can easily be designed such that no feedback of parameters is required to maintain acceptable operation of the speaker.
  • Enclosure 30 has speaker 31, tuned aperture 32, and wall 33 with tuned aperture 34.
  • the loudspeaker cone can be a 12" diameter cone.
  • the maximum stroke of the device will be +/- 12mm.
  • the maximum force required from the actuator is approximately 200 Newtons.
  • a hydraulic supply of 10 MPa (1500 PSI) is required, so the piston area of the hydraulic piston will be at least 2E-5 square meters. If the cylinder is to displace +/- 12mm at 100 Hz, the minimum required flow rate is 5E-5 cubic meters per second (3 cubic inches per second). There will be some leakage which requires this flow rate to be higher since a hydraulic cylinder is generally designed with leakage and "dither" movement to improve its linearity.
  • This centering stiffness may be the stiffness of the speaker cone support or may be an additional stiffness added to the cone or the hydraulic actuator.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)

Abstract

Enceinte acoustique à commande hydraulique faiblement amortie dans laquelle un cylindre hydraulique (21) est fixé au cône (22) d'un haut-parleur qui peut être utilisé dans une enceinte acoustique passe-bande.
PCT/US1992/005771 1992-07-14 1992-07-14 Enceinte acoustique a commande hydraulique WO1994001979A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1992/005771 WO1994001979A1 (fr) 1992-07-14 1992-07-14 Enceinte acoustique a commande hydraulique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1992/005771 WO1994001979A1 (fr) 1992-07-14 1992-07-14 Enceinte acoustique a commande hydraulique

Publications (1)

Publication Number Publication Date
WO1994001979A1 true WO1994001979A1 (fr) 1994-01-20

Family

ID=22231232

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1992/005771 WO1994001979A1 (fr) 1992-07-14 1992-07-14 Enceinte acoustique a commande hydraulique

Country Status (1)

Country Link
WO (1) WO1994001979A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997050077A1 (fr) * 1996-06-22 1997-12-31 Er Fluid Developments Limited Transducteurs acoustiques utilisant un fluide de travail
US6166886A (en) * 1998-03-20 2000-12-26 Seagate Technology Llc Swageless head suspension and method of assembly therefor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4564727A (en) * 1983-01-28 1986-01-14 Intersonics Incorporated Subwoofer speaker system
US4607382A (en) * 1983-04-26 1986-08-19 U.S. Philips Corporation Electroacoustic transducer unit with reduced resonant frequency and mechanical spring with negative spring stiffness, preferably used in such a transducer unit
US5060274A (en) * 1988-06-10 1991-10-22 Ishikawajima-Harima Heavy Industries Co., Ltd. Hydrostatic speaker and speaker driver
JPH03239099A (ja) * 1990-02-16 1991-10-24 Mitsubishi Electric Corp スピーカシステムの冷却装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4564727A (en) * 1983-01-28 1986-01-14 Intersonics Incorporated Subwoofer speaker system
US4607382A (en) * 1983-04-26 1986-08-19 U.S. Philips Corporation Electroacoustic transducer unit with reduced resonant frequency and mechanical spring with negative spring stiffness, preferably used in such a transducer unit
US5060274A (en) * 1988-06-10 1991-10-22 Ishikawajima-Harima Heavy Industries Co., Ltd. Hydrostatic speaker and speaker driver
JPH03239099A (ja) * 1990-02-16 1991-10-24 Mitsubishi Electric Corp スピーカシステムの冷却装置

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997050077A1 (fr) * 1996-06-22 1997-12-31 Er Fluid Developments Limited Transducteurs acoustiques utilisant un fluide de travail
US6166886A (en) * 1998-03-20 2000-12-26 Seagate Technology Llc Swageless head suspension and method of assembly therefor

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