Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers, loudspeakers or microphones
  • H04R3/12—Circuits for transducers, loudspeakers or microphones for distributing signals to two or more loudspeakers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
  • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
  • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
  • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
  • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
  • H04R1/403—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers loud-speakers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/005—Details of transducers, loudspeakers or microphones using digitally weighted transducing elements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R19/00—Electrostatic transducers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2430/00—Signal processing covered by H04R, not provided for in its groups
  • H04R2430/20—Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic

Definitions

• This invention relates to acoustic devices, particularly to devices for producing and radiating sound typically in response to electric signals from appropriate electronic audio signal processing means; and specifically to novel forms of loudspeakers .
• Conventional loudspeakers rely upon pistonic action to impart sound into ambient air using diaphragms driven basically reciprocally by electromagnetic means, typically cones intendedly operative on air in and forward thereof.
• Such conventional loudspeakers are variously characterised by box-like enclosures with often complex provision for rearward absorption of otherwise at least partially cancelling sound components that are opposite in phase to desired forwardly directed sound components; by direction- ality of desired forward sound in effective listening beam angles that are narrower the higher the frequency of reproduced sound concerned; and by fall -off of intensity of produced sound within such beam angles in a square-law manner with distance as though from a substantially point source close to which sound intensity can be very high for powerful loudspeakers.
• Multiple unit cone type loudspeakers are well known with different sizes of cones operative for low, mid and high bands of audio frequencies, with consequent requirement for electronic cross-over networks for signals to such units.
• acoustic devices including loudspeakers of radically new type, specifically as to acoustic action and resulting sound radiation, see PCT application no. GB96/02145) .
• the acoustic action concerned for such loudspeakers relies on bending waves excited at particular prescribed positions in suitably constructed and configured panels for which resulting surface vibrations couple acoustically to air in a fundamentally non-pistonic manner.
• Resulting sound radiation can be effectively from the whole panel surface and over a very wide angular range producing highly diffused effects far, removed from above-mentioned intrinsic prior proximity loudness and directionality features, and over remarkably wide frequency ranges for individual panel units.
• a sound radiator comprises an areally distributed array of plural acoustic transducer units having individually energisable drive or exciter means, and drive signals therefor are such as to result in sound radiations of differing respective phases, say directly related to imposed phasing of said drive signals, suited to such integration of individual unit outputs as to produce usefully diffuse and/or desiredly directional overall radiated sound from the area of said array rather or other than with prior narrowing beam angle with increasing frequency.
• Suitably disorderly or incoherent relation of said phases is envisaged for arrays of transducer units ranging from as low as 20 or less to as high as 750 or more.
• electrostatic loudspeakers representing, compared with cone-type loudspeakers, relatively large sound radiating areas that are effectively made up of individually pistonic-action sub-areas that operate with carefully orderly phase shifts so that such loudspeakers exhibit perceived coherence and point-source directionality of radiated sound, thus differ fundamentally from proposals hereof.
• desired phase incoherency of plural units producing diffuse perception of overall radiated sound that it proves upon directionality and proximity loudness of conventional loudspeakers is not essentially of similar nature to what happens in above-discussed distributed mode bending wave panels. Indeed, pursuit of such similar nature in terms of areal distribution of resonant frequency modes of such a panel might most naturally involve a matching unit distribution and operative frequency correlation of the transducer units.
• phase distributions hereof can be considered as being randomised.
• phase differences themselves individual and/or cumulative cancellation effects are readily avoided, e.g. readily achieved by such constraint as none being a whole number sub-multiple/divisor of 180°.
• any particular distribution of particular different phases that is deemed to be satisfactory for any particular array of transducer units can be, and usually will be for simplicity, made or treated as fixed or prescribed for the implementation concerned.
• the number of different phases may not need to be the same as the Number of transducer units, i.e. some could be the same so long as the number and distribution of different phases produces acceptable perceived diffuse overall sound, a situation the more likely the more units there are in the array concerned.
• Such low frequency in-phase drive mode is applicable to less than all of the transducer units of an array hereof, i.e. only to the units of sub-area (s) of the array, say a medial usually central sub-area that could be shrunk progressively, typically step-wise, with frequency rising through the low range below what is well handled by above randomised different phase mode of operation.
• array (s) of individual transducer units hereof it is preferred for array (s) of individual transducer units hereof to have common sheet- or panel-like carrier means, whether of flexible or stiff nature and presenting surface (s) that need not be flat planar, i.e. could be curved in one or more directions and/or faceted.
• preferred carrier means can further assist desired application of drive signals individually to such transducer units, conveniently as a substrate for related conductor patterns, say after the well-established manner of printed circuit boards. Indeed, such carrier means may also usefully serve in mounting of local drive signal circuitry such as of modular semiconductor integrated circuit type.
• Suitable units can be of the order of only about ten millimetres in diameter and have as low as 5% - 10% moving mass (compared with customary cone- loudspeaker design practice) , say about 50 milligrams per transducer unit, which have not hitherto been considered as viable for much beyond low quality sound reproduction, but actually have significant advantage for the purposes hereof by reason of already being so small as to have sound radiation patterns that are of more spherical multi- directional than axially directed nature.
• transducer units will be chosen or designed according to power handling, bandwidth and maximum pressure level characteristics and desiderata.
• line drive is feasible using semiconductor integrated circuits for modular amplifier sets, say of CMOS type, and digital- to-analogue converters for digitally processed signals. Resistive summation from a low bit-capacity decoder is feasible.
• CMOS complementary metal-oxide-semiconductor
• Resulting signal coding can readily incorporate audio content along with any and all of phase and/or amplitude functions desired for the transducer units of arrays hereof, and undesirable transitions, such as between all-zero and all- one sequences can be avoided.
• local driving provisions therefor and the carrier means of the array local drivers can be row-and-column addressable and time and line multiplex coded for response to digitally processed signals, and the carrier means can have printed circuit paths for addressing etc, if necessary or desired in plural layers of metallisation.
• the transducer units may also, be formed in or on the carrier means with benefit from technology developed and evolving for semiconductor integrated circuits, particularly highly sophisticated lithography techniques; and as first indicted above the units may be of electrostatic, thin or thick film piezoelectric type(s), or reliant on micro- engineered machine technology for the making of very small devices with moving parts, thus applicable to moving coil or lever assisted electrodynamic units typically as using high efficiency neodymium permanent magnets and operated in external polarising f ⁇ eld(s).
• Suitable piezoelectric materials include crystalline types, e.g. barium titanate, or high polymer electrets, and multi-layer transducer units are readily fabricated together using layer printing commonplace m semiconductor processing.
• transducer units are below 20 millimetres each.
• carrier means such as of flexible films that have acoustic transducing action in themselves and have multi cell drive positions suitably conductively connected in a matrix array.
• Figures 1A and IB are outline front plan and edge-on views of first matrix-like rectangular array of panel-mounted movmg-coil type transducer units;
• Figures 2A and 2B are similar views of second gene- rally circular array of panel-mounted movmg-coil type transducers;
• Figures 3A and 3B are similar views of a larger matrix-like rectangular array of panel-mounted movmg-coil type transducer units;
• Figures 4A and 4B are similar views of a 10 x 10 array of sheet- or membrane-mounted piezoelectric transducer units;
• Figures 5A and 5B similarly show transducer unit sites formed by selective metallisations of a piezoelectric sheet or membrane;
• Figures 6A - D show electro-mechanical film type embodiment
• Figure 7 is an outline block diagram of a multichannel audio system with implementation of this invention
• Figure 8 is an outline block circuit diagram for out-of-phase and low frequency in-phase operation of an array loudspeaker
• Figure 9 likewise shows further low frequency options
• Figure 10 is a schematic circuit diagram for implementation by digital signal processing in a program controlled computer system.
• generally rectangular arrays could have more or less rows and/or columns of equal or unequal numbers of transducer units, perhaps involving binary powers, and such units might be in adjacently staggered relation from row to row and/or column to column, say by half pitch and partially intercalated to increase the density of unit population of the panel; generally circular arrays could have different numbers of transducer units in first and second rings and/or more rings of transducer units with any practical relation of ring populations and/or partial intercalation of progressively outward transducer units; and other arrays are feasible, for example of simple or staggered successively triangular or polygonal nature, or of compound type involving combinations of such distribution shapes, or even of irregular nature that might satisfy even or varying unit density desiderata.
• FIGs 4 and 5 each show carrier sheets or membranes
• the transducer units 42 can be of individual piezoelectric type affixed to the sheet or membrane 41, and the transducer units 52 can also be of piezoelectric type but in this case formed and defined by registering metallisations 52A and 52B on opposite surfaces of intrinsically piezoelectric material of the membrane or sheet 51, say of high polymer type.
• row-and-column addressing is envisaged conforming to the labelling of the units, i.e. with a corresponding one of each of sets of row-following and column-following conductors (not shown) energised, see further below regarding digital signal processing.
• FIGS. 6A - D show implementation using dielectric film 63 as a moving acoustic diaphragm between front and back porous stator plates 64F, B.
• Such electromechanical film devices operative acoustically are well known in the art, including using inherently conductive or conductively coated stator plates and multilayer films having oppositely charged layers selectively metallised with, or to each side of a layer carrying, conductive electrode provisions. Cavities formed as registering depressions
• the depressions 65F, B are shown rounded or domed with dashed references in Figure 6C, but otherwise, specifically peaked pyramidal in Figures 6A, B.
• Localised plate-like electrode formations 62F, B are shown on opposite sides of common electret sheet 63 local to each cavity with individual conductive paths 66F, B for individual energisation for the purposes hereof.
• each transducer unit T also omitted from Figures 1 - 6 are envisaged drive amplifiers (see labelled A in later Figures) individual to each transducer unit T, and which may be of semiconductor integrated type, whether conveniently mounted on the carriers (11, 21, 31, 41, 51, 63) , say at undersides, or to an underlying printed circuit board, say with connector pins engaged with plated holes connected to the amplifiers them-selves supplied via conductive tracks in one or more layers of metallisation as appropriate.
• Figure 7 shows audio system implementation in a multi-channel environment comprising electronic source 100 serving to supply electric audio signals to channel outputs 101 - 105 as for such as home movie or other stereophonic surround-sound applications involving the now familiar left and right plus centre forward speakers and pair of rearward loudspeakers, in this case with all five loudspeakers 111 -115 each indicated as being of array type and embodying this invention, see particularly and typically array loudspeaker 113, by way of plural transducer units Tl - Tn as above and individually associated drive amplifiers Al - An. Audio signal supply lines SI - Sn for the amplifiers Al - An of each of the array loudspeakers 111 - 115 are shown supplied from phase and/or amplitude setting and routing means 121 - 125.
• array loudspeakers 111 - 115 need not be all of the same type, nor all have the same number of transducer units Tl - Tn, i.e. "n" may be different for each, though left and right forward stereo loudspeakers will normally be the same, as will the usual rearward loudspeakers; and that, in any applications of this invention where loudspeakers would receive essentially the same signals, array loudspeakers embodying this invention would be supplied from common phase and/or amplitude adjustment means.
• Figure 8 shows a simple implementation of suitable phase setting by way of branch 131 shown from channel audio signal line 103 delay line 132 having multiple taps
• this lines Dl - Dn could be less than the number of transducer units, thus drive lines SI - Sn, even some submultiple. If some of the transducer units do receive the same phase of audio signal, it is usually preferred that are not all adjacent, indeed distributed beneficially (or at least non- damagingly) to achieving acceptably diffuse sound results, though they might well be arranged symmetrically in the array.
• the number involved is preferably sufficient if applied to a sub-area or patch of the array to achieve acceptably diffuse sound results in its own right, and arrangement in a total array might well have symmetry of such sub-areas in appropriately adjacent relationships and/or transforms of the same patterns and/or different patterns each effective as aforesaid and further in actual combination.
• the channel audio signal line 103 is also shown going to a low pass filter 135 for producing such low frequency outputs as benefit from being applied to the whole array with an in-phase relationship simulating pistonic loudspeaker effects, as discussed above, see filter output
• Figure 9 differs from Figure 8 firstly in illustrating action for transducer units Tl - Tm of part 113a only of an array loudspeaker hereof, specifically a row or column of a rectangular matrix-like overall array, with corresponding indication of transducer unit drive lines SI - Sm and part 132a only of delay line provisions with corresponding tap output lines Dl - Dm. It may be convenient to consider completion of provisions for the whole array as further sub-arrays of transducer units above and/or below or in front and/or behind those (tl - Tm) in row or column part 113a, likewise with delay line part 132a (say as parts serially connected end-to-end) and with "randomising" routing means 133a.
• output 136 from low pass filter 135 is shown branched at 137 for connection to less than all of output lines Rl - Rm of the "randomising" routing part 133, specifically to a medial number at RX. If similarly applied to outputs of each of all other parts of the "randomising” routing means, the result would be for only a centralised band of the transducer units to receive in- phase low frequency signals on branch line 137, but such band could have its ends reduced to give an all-round “window” effect if outputs of outer ones of parts of the routing means do not have connections to the branch line 137.
• Line 136 is further shown going to another low pass filter 138 for providing lowest frequency signals on line 139 connected to all others of the outputs from the routing means, see at RY1 and RY2 of part 133a, thus increasing the number of the transducer units driven by such lowest frequencies to the full loudspeaker array. If desired, there could be more filter stages and more and/or other steps in increasing the numbers of array transducer units driven in-phase from a minimum band or window to a maximum that could be less than the full array.
• FIG. 9 further shows another multiple-tap delay line or delay line part 141a fed over branch 142 from the low pass filter output 136 and having its outputs connected in order to the outputs of the routing means, see at Ml - Mm and Rl - Rm for part 133a, usefully with such phase differences and driving of the array transducer units as to simulate sound output as though from a stretched string or membrane.
• Figure 9 shows another branch 145 taken from audio channel signal line 103 to each of plural filters 146, one per transducer unit of area(s) up to all of the array, see filter outputs labelled FI - Fm to corresponding routing means outputs Rl - Rm; these filters 146 preferably being of second order recursive all-pass type up to a predetermined frequency which may serve as a cross-over frequency to only-diffuse transducer unit operation and be different for each or sets thereof, and serving to produce desired resulting sound effects, say to simulate travelling wave vibration as follows :-
• Figure 9 further shows additional amplitude varying means 151 for signals on outputs from the routing means that will have no effect unless enabled into operation for which several modes are envisaged, see outputs 152 from node specification block 153 shown with specifications for outer or frame regions (153F) or corners (153C) or patches
• a digital data processor 161 that will include its own immediate working memory/ storage for data and in-use program material is shown in outline association via parallel bus provisions 162A, B with high-capacity memory 163 holding data and programs relating to useful modes of phase manipulation including for randomising (163R) , simulations of stretched membrane (163M) and travelling wave (163T) , and controlled according to Fourier transform (163F) ; and of amplitude manipulation including window and/or patch (163W/P) , frame and/or corner (163F/C) and Fourier transform (163F) modes; and for general and specific control purposes (163C) including by which said modes are selected and implemented automatically according to installed software, see schematic dashed extension of the data processor block 161 and bi-directionally arrowed dashed lines therethrough to and from referenced content blocks of the memory 163.
• Analogue multiplexor output 172 is shown branched at 173 for low pass filtering at 174 onto line 175 with both of lines 172 and 175 going to analogue-to-digital (ADC) conversion stage 176 feeding parallel input buses 177 and 178.
• Parallel digital channel outputs 101D - 10SD are assumed with parallel output effectively onto the input bus 177, though they could be serial and converted to parallel at output of multiplexing.
• illustrated multiplexing and ADC can be expected to be done within the input/output provisions 165, probably under control of a microprocessor subsidiary to the data processor 161, i.e. then with only a low pass filter (or more as above) connected up externally (and possibly even to use for the digital audio if conversion to analogue form within block 165 is preferred to equivalent digital signal manipulation) , even omitted if equivalent digital signal manipulation is preferred, i.e. after such conversion that is required in any event.
• DACm are further shown feeding said amplifiers Al - Am.
• parallel feed bus branches Bl - Bm are shown from digital system output 181 to each of digital-to-analogue converters DAC1 - DACm, serial supply can be made in fast enough digital data processing systems, say with shift plus latching registers for substantially continuous analogue drive signals for the acoustic transducer units from the latching register content conversion between shift register loadings. At least then, and given presence of local final drive signal conditioning amplifiers (Al -
• amplifiers Al - Am of Figure 10 are shown as being of gated (G) type, specifically of two-input AND-action type to facilitate individual row-and-column addressing to specify transducer units desired to be active at any one time, or even on a multiplexed basis for different mode signals if resulting duty cycles are good enough for satisfactory sound production.
• G gated
• R row
• C column
• Sets of row (R) and column (C) addressing lines are shown from the input/ output provision 165, including those specific to gating of the illustrated amplifiers Al and Am.
• economy of wiring would benefit from the data processing system and its input/output provision producing serial binary words specifying, say digit-by-digit, and periodically changing the rows and columns to be addressed by receiving circuitry at the carrier of the array loudspeaker.

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• Health & Medical Sciences (AREA)
• Otolaryngology (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• General Health & Medical Sciences (AREA)
• Circuit For Audible Band Transducer (AREA)
• Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
• Transducers For Ultrasonic Waves (AREA)
• Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
• Transmitters (AREA)
• Piezo-Electric Transducers For Audible Bands (AREA)

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• 1997
  • 1997-08-05 GB GBGB9716412.3A patent/GB9716412D0/en active Pending
• 1998
  • 1998-07-30 ID IDW20000059A patent/ID24975A/id unknown
  • 1998-07-30 IL IL13398598A patent/IL133985A0/xx unknown
  • 1998-07-30 AU AU85519/98A patent/AU741154B2/en not_active Ceased
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  • 1998-07-30 JP JP2000506798A patent/JP2001513619A/ja active Pending
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  • 1998-07-30 CN CN98807982A patent/CN1266604A/zh active Pending
  • 1998-07-30 CA CA002295724A patent/CA2295724A1/en not_active Abandoned
  • 1998-07-30 TR TR2000/00351T patent/TR200000351T2/xx unknown
  • 1998-07-30 WO PCT/GB1998/002288 patent/WO1999008479A1/en not_active Application Discontinuation
  • 1998-07-30 KR KR1020007001218A patent/KR20010022624A/ko not_active Application Discontinuation
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  • 1998-07-30 SK SK163-2000A patent/SK1632000A3/sk unknown
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  • 1998-07-30 HU HU0101998A patent/HUP0101998A2/hu unknown
  • 1998-07-30 EP EP98936555A patent/EP1002445A1/en not_active Withdrawn
  • 1998-07-31 TW TW087112629A patent/TW392415B/zh not_active IP Right Cessation
  • 1998-08-03 ZA ZA986927A patent/ZA986927B/xx unknown
  • 1998-08-04 AR ARP980103849A patent/AR013281A1/es unknown
• 2000
  • 2000-01-12 BG BG104072A patent/BG104072A/bg unknown
  • 2000-02-04 NO NO20000588A patent/NO20000588D0/no not_active Application Discontinuation

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