CN1195463A

CN1195463A - Panel-form microphones

Info

Publication number: CN1195463A
Application number: CN96196703.XA
Authority: CN
Inventors: 亨利·阿兹玛; 马丁·科洛姆斯; 尼尔·哈里斯
Original assignee: New Transducers Ltd
Current assignee: NVF Tech Ltd
Priority date: 1995-09-02
Filing date: 1996-09-02
Publication date: 1998-10-07
Also published as: WO1997009862A1; DK0847678T3; AU703058B2; EA000640B1; HK1008652A1; EA199800262A1; JPH11512254A; EP0847678A1; ATE179297T1; ES2132952T3; CA2230449A1; RO119057B1; AU6881296A; DE69602204T2; EP0847678B1; DE69602204D1

Abstract

A panel-form microphone characterised by a distributed mode acoustic member (12) and a transducer (63) coupled wholly and exclusively to the member to produce a signal in response to resonance of the member due to incident acoustic energy.

Description

Panel-form microphones

Technical field

The present invention relates to loudspeaker, relate in particular to the loudspeaker that comprises board-like acoustic element.

Background technology

Proposed a kind of panel-form loudspeakers among the British patent GB-A-2262861, this loud speaker comprises:

Multi-modal radiator element resonates, the monobasic sandwich plate that this is made up of two layers of skin material of the spacer core that accompanies horizontal honeycomb, wherein the bending stiffness (B) of this sandwich plate on all fix the position for the plate quality (μ) of per surface area cube ratio be at least 10;

Erecting device, this device supports described plate or attaches it on the support in undamped mode freely; And

Be connected to the electro-machanical drive unit of described plate, this device be used for responding in the speaker operation frequency band range electric input and in the multi-modal resonance of radiator plate excitation.

Disclosure of an invention

The intrinsic propesties of the employed member of various embodiments of the present invention, structure and configuration can with the guidance of on the same day pending trial PCT patent application No. of the present invention (we case number P.5711) under obtain comprehensively and/or particularly.Therefore this member has the ability of bearing and propagate the inputted vibration energy, and this is to realize by the bending wave that extends laterally to the element marginal portion in the working face of thickness direction, but bending wave neither leave no choice but to extend to the element edge can not; With or do not construct with the anisotropy of bending stiffness, go up all resonance mode oscillating components that help carrying out acoustical coupling that distribute to have in described service area (all service areas) with surrounding air; And have all predetermined preferential position or the place of in described service area, laying transducer apparatus, especially in operation, have effective transducer active of the acoustic vibration activity in described service area (all service areas) or moving component (all actives or moving component); And has a signal of the normally signal of telecommunication corresponding with the acoustic content of this vibration activity.With on the same day pending trial international application No. of the present invention (we case number P.5711) in looked forward to this member as or be used for not having the acoustic equipment of transducer apparatus, such as being used for reverberation or being used for sound filtering or being used to make sound " to pass to " (voicing) space or place; Reach " active " acoustic equipment that is used as or is used to have transducer apparatus, for example when receiving the input signal that need be converted into sound, use it in the sound source or loud speaker with utmost point wide frequency ranges.

The present invention be more particularly directed to the active acoustic equipment of loudspeaker form.

In this article as above member is called distribution mode acoustic radiator, and prepares to make it to have other features in the above-mentioned PCT application and/or that this paper provides specially.

The present invention is a kind of panel-form microphones, it is characterized by: acoustic member and transducer integral body with distribution mode combine uniquely, to produce and the member that is caused by the incident acoustic energy corresponding signal that resonates.Described member can be installed in by means of the elasticity holder that inserts and enclose in the frame.

Panel-form microphones can be at least two described transducers that have the position of certain intervals on member.The response that panel-form microphones can be included on the member is resonated and another transducer of generation signal by the member that incident acoustic energy causes, also can comprise compare facilities, be used for the signal of described another transducer generation and the signal of aforementioned transducer generation are compared.

Compare facilities can comprise signal receiver, adjuster and signal output apparatus.

Distribution mode acoustic member can be the rigidity light plate with the honeycomb fashion spacer core that is clipped between the covering.

Described transducer or each transducer can be piezoelectric devices.

Brief description of drawings

The present invention is illustrated by way of example in the accompanying drawings, wherein:

Fig. 1 is our international application No of pending trial simultaneously ... the figure of described in (we case number P.5711) and the distribution mode loud speaker institute prescription;

Fig. 2 a is the partial cross section figure along Fig. 1 line A-A;

Fig. 2 b is the amplification sectional view of the distribution mode radiator of Fig. 2 a shown type, and this illustrates two kinds of possible structures;

Fig. 3 is the figure according to the micropkonic embodiment of distribution mode of the present invention; And

Fig. 4 is the perspective view of vibration transducer.

Realize best mode of the present invention

With reference to the Fig. 1 in the accompanying drawing, the figure shows described in our the pending trial international application (we case number P.5711) that enters on the same day and the sort of panel-form loudspeakers 81 of institute's prescription, loud speaker 81 is included is loaded with the rectangular frame 1 of elastic mounting thing 3 around the periphery, and thing 3 supporting distribution mode acoustic radiation plates 2 suspend.As entering on the same day with the present invention, the transducer 9 that is described in detail in our the pending trial international application (we case number P.56831415), intactly and uniquely be contained on the plate 2 or in the plate 2 in pre-position by size x and y regulation, to the calculating of this position as described in (we case number P.5711) in our the pending trial international application that enters on the same day with the present invention, so that the bending fluctuation is projected in the plate, this plate resonance is exported with radiation one acoustics.Transducer 9 is by the signal amplifier 10 that is connected to this transducer with lead 28, audio frequency amplifier for example, drive.

The loading of amplifier and power requirement can be complete nominals, and be identical with the pyramid type loud speaker of routine, under indoor loading environment sensitivity be about the 86-88 decibel/watt.The impedance of amplifier load is ohmic basically, is 6 ohm, and power conversion capability is 20-80 watt.When plate core and/or covering were made with metal, they can play the work of transducer radiator in order to remove heat from the transducer moving-coil, have therefore improved power conversion capability.

Fig. 2 a and 2b are the part typical section figure of Fig. 1 loud speaker 81.Fig. 2 a representational framework 1, surround 3 and plate 2 usefulness bonding connection layer 20 separately link together.The suitable material of framework comprises the lightweight frame, for example the picture frame of being made by extrusion metal (as aluminium alloy) or plastics.Suitable surround material comprises elastomeric material, for example sponge rubber and foamed plastics.The proper adhesive of articulamentum 20 usefulness comprises adhesives such as epoxy resin, polypropylene and cyanoacrylate.

It is one to have the rigidity light plate of fuse 22 that Fig. 2 b illustrates plate 2 with the size of amplifying, this fuse 22 is made by for example rigid foamed plastics 97 (as crosslinked polyvinyl chloride) or cellular matrix 98 (i.e. the cellular matrix made from sheet metal, plastics or similar substance), each honeycomb structure laterally extends on the plane of plate, and is sealed by opposed covering 21 (as paper, ivory board, plastics or sheet metal or sheet metal).Under covering situation made of plastic, can come stiffened skin to increase its modulus as fiber in a known manner with carbon, glass, Kevlbar (registered trade mark) or similar material.

Therefore the covering layer material of expection and fortifier comprise carbon, glass, Kevlar (registered trade mark), the Nomex (registered trade mark) of various sth. made by twisting methods and weave, it is the fiber of aromatic polyamide etc., also have paper, pasted paper laminated sheet, melamine in addition, and the synthetic plastic film of various high modes such as Mylar (registered trade mark), Kaptan (registered trade mark), Merlon, phenolic aldehyde, polyester or relevant plastics, and fiber-reinforced plastic etc., and sheet metal or thin slice.Investigation to all liquid crystal polymer thermoplastics of Vectra board shows that these thermoplastic materialss can be used for the injection molded of ultra-thin covering or small size (for example up to about 30 cm diameters) ultra-thin covering or housing.This forms an oriented crystal structure this material on injection direction, promptly form a preferred orientation that can transmit the high pitch energy from drive point to the plate periphery well.

In addition, use this or other thermoplastic materials allow to make mould God just like groove, encircle the location feature of a class, be used to make as moving-coil, the transducer part of magnet one class is accurately located.For some softer core body spare material, also to replenish the covering thickness that calculates required increase in 150% the zone be preferably in transducer diameter nearly or the annular region, to strengthen this zone and to help vibrational energy is coupled in the plate.Take this measure can when using softer foamed material, improve high frequency response.

The core material of expection comprises with aluminium alloy sheet or film or with Kevlar (registered trade mark), Nomex (registered trade mark), common paper or pasted paper, reaches various synthetic plastic films, and expandable plastic or foamed plastics or raw material of wood pulp.Even the honeycomb or the corrugated structure of various aviation gelling metals manufacturings, if they have suitably low density.Some suitable core material presents available covering self-generating phenomenon and/or has enough self-stiffnesses in its manufacture process, thereby can directly use and not as the interlayer between the covering layer.The well-known cellular fuse material of high-performance is fit to do radiant panel with trade (brand) name " Rohacell ", and this material need not covering.In fact, purpose is to reach the slight and rigidity that is suitable for a special-purpose comprehensively, specifically, comprises sandwich layer and covering layer and the optimization of transition portion therebetween.

The some preferential assembled scheme of plate adopts the covering of metal and metal alloy, perhaps selects to adopt carbon fiber-reinforced thing as another.These two kinds of materials, and the design of using alloy aviation gum material or metal beehive fuse all have significant radio shielding characteristic, and these characteristics should be important in some EMC (Electro Magnetic Compatibility) use.Conventional board-like or circular cone type loud speaker does not then have inherent EMC screening ability.

In addition, the preferred form of the dynamic transducer of piezoelectricity has very little electromagnetic radiation or stray magnetic field.Conventional loud speaker then has big magnetic field, unless take special compensation countermeasure, magnetic field can reach 1 meter farthest.

In one uses, be important if keep shielding, then can be electrically connected or conductive foam plastic or similarly be connected the installation that material is used for the limit with the conductive component of suitable DML plate.

The thing 3 that suspends can play damping action in case plate produces excessive edge motion to each limit of plate.In addition, or the another kind of selection of conduct, on the position that for example some patches is adhered to plate, can apply further damping and be evenly distributed on the plate to stop excessive motion and to make to resonate through selection.Patch can be as material or elasticity or rigid polymer light sheet material based on pitch commonly used in conventional loud speaker outer cover.Some material, particularly paper and ivory board and some fuse can be self-dampings.When needed, solidify rather than the adhesive of rigid set, can increase damping in the configuration aspects of plate by using elasticity.

Effectively described optional damping comprises to the plate that comprises its light sheet material and applies permanent coupled device specially.Limit and angle are for the main and low low-frequency vibration mode particular importance of disperseing of plate of the present invention.Damping device is installed on the limit is helped making described light sheet material to be lived by frame institute frame fully, yet, for example in order to wish to expand to more low-frequency operation, usually can make each angle of plate free relatively.Can come bonding with adhesive or self adhesive material.The useful damping of other forms especially with regard to trickleer effect and/or intermediate frequency and higher frequency, can realize by on predetermined effective middle position in described zone suitable matter piece or all matter pieces being pasted on the light sheet material.

Above-mentioned plate is for being good receiver as the acoustic vibration sound that occurs onboard.Preferably the plate structure of lightweight helps the raising of sensitivity, vibration can be by one but preferably more a plurality of simple flexible transducer (the described piezoelectricity kind of for example following Fig. 4) detect.The use of a plurality of transducers and the riding position of these transducers have been optimized the quality from the panel vibration that distributes to the conversion of required electrical output signal.Riding position should be on the position of high modal density, and in the inside of plate, simultaneously, plate itself should have the reality or the equivalent geometrical shape of the best that produces good modal distribution.

Incident acoustic energy onboard is transformed into the Free Modal vibration.This vibration can be detected by all optics or electric vibrating transducer, consequently becomes a loudspeaker.For requiring not harsh application, the single detector that is placed in drive point place equivalence, that optimize is effectively.

In order to obtain good effect, must consider the characteristics of non-reciprocity of transduction principle.Relevant with it have two factors: the first, some equilibriums that depend on frequency be arranged obtaining the flat frequency response, the second, need catch the more extensive sample of the complex vibration of plate.At least need three transducers; They can be that output is the cheap flexural piezoelectric device of parallel form.Or the bigger polymer piezo film of usable floor area, and form that suitable geometry picks up pattern so that determine vibration integrated district for obtaining optimum sensitivity/frequency response.

Use for loudspeaker, the very light in weight of plate preferably is so that provide the radiation impedance of air and the optimum Match between the plate.The quality of plate is more little, and the sensitivity that obtains is high more.For single transducer, the calculating of theoretical model points out that the optimum position is the corner at plate, because can " excite " (voiced) all mode of oscillations with voice at each place, angle.

The preparation that Fig. 3 illustrates according to Fig. 1 and 2 type of the present invention is micropkonic distribution mode plate 2 as acoustic receiver.Though not shown, plate 2 is to be installed in to enclose in the frame 1 and be connected to this by elastic mounting thing 3 in the mode shown in Fig. 1 and 2 to enclose on the frame.This enclose frame for example be suspended in come from ceiling or on a pair of line 33 on the upright frame (not shown) in floor.

Be loaded with onboard the array of four vibration transducers 63 placing at certain intervals on the described plate, these transducers can be the PZT (piezoelectric transducer)s of following type shown in Figure 4, and they are connected in parallel and are connected to the signal receiver and the adjuster 65 of output 66 with driving.

Fig. 4 represent to distribute transducer 9 of mode plate 2 usefulness, it is shaped as the plate-like flexural piezoelectric device 27 of crystal, and bending apparatus 27 is installed on the dish 118 that for example brass is made, and transducer 9 for example is adhered on the face of plate 2 with adhesive 20.In operation, the audio signal that is added to transducer 9 by electric wire 28 can make piezoceramic disk 27 bendings, thereby local and flexiblely make plate 2 distortion, and the bending fluctuation is projected in the plate.

Claims

1. a panel-form microphones is characterized in that, has distribution mode acoustic member and have intactly and uniquely to be connected to this member produces signal to respond the member resonance that is caused by incident acoustic energy transducer.

2. according to the described panel-form microphones of claim 1, it is characterized in that described member is installed in by the elasticity holder that inserts and encloses in the frame.

3. according to claim 1 or 2 described panel-form microphones, it is characterized in that there are at least two described transducers all positions that have certain intervals on described member.

4. according to the described panel-form microphones of above arbitrary claim, it is characterized in that described member is the rigidity light plate with the honeycomb core that is clipped between the covering.

5. according to the described panel-form microphones of above arbitrary claim, it is characterized in that described transducer is a piezoelectric device.