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WO2006030198A1 - Reseau de cadres - Google Patents

Reseau de cadres Download PDF

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Publication number
WO2006030198A1
WO2006030198A1 PCT/GB2005/003528 GB2005003528W WO2006030198A1 WO 2006030198 A1 WO2006030198 A1 WO 2006030198A1 GB 2005003528 W GB2005003528 W GB 2005003528W WO 2006030198 A1 WO2006030198 A1 WO 2006030198A1
Authority
WO
WIPO (PCT)
Prior art keywords
transducers
array
spiral
curve
display screen
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/GB2005/003528
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English (en)
Inventor
Anthony Hooley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
1 Ltd
Original Assignee
1 Ltd
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 1 Ltd filed Critical 1 Ltd
Priority to GB0704911A priority Critical patent/GB2432743B/en
Publication of WO2006030198A1 publication Critical patent/WO2006030198A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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
    • 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
    • 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
    • H04R2205/00—Details of stereophonic arrangements covered by H04R5/00 but not provided for in any of its subgroups
    • H04R2205/022—Plurality of transducers corresponding to a plurality of sound channels in each earpiece of headphones or in a single enclosure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
    • H04R2499/10—General applications
    • H04R2499/15—Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S3/00—Systems employing more than two channels, e.g. quadraphonic

Definitions

  • the present invention relates to an apparatus for creating a sound field and a method of designing such an apparatus. More particularly, the invention provides a novel arrangement of transducers in an array type loudspeaker which alleviates the problems associated with sidelobes that can occur when sound is beamed in one or more particular directions, especially when the array contains an area devoid of transducers, such as a rectangular area used to support a display screen.
  • Phased array (and digital-delay array) loudspeakers and microphones are known in the art (see e.g WO01/23104 and WO02/078388), and these include multi-beam arrangements useful for the production of surround sound.
  • the arrays comprise transducers arranged in a regular pattern, such as a square grid pattern or triangular grid pattern. Non-uniformly spaced transducer arrangements are also known, including logarithmic spiral arrays (see e.g.US 5,838,284).
  • the invention provides apparatus for creating a sound field, said apparatus comprising: an array of sonic output transducers, which array is capable of directing at least one sound beam in a selected direction; wherein said array surrounds a central region devoid of transducers and suitable for mounting a display screen; and wherein said transducers are disposed in an irregular pattern such that any sidelobes created are at least 3 dB less powerful than the sound beam to be directed.
  • the irregular pattern of transducers helps to ensure that the vector separating any two transducers is different in both magnitude and angle to a vector separating any other two transducers.
  • a regular pattern of transducers there are many repeated transducer pair spacings which contribute to the creation of a few quite strong sidelobes.
  • the irregular pattern helps to reduce the power of the sidelobes.
  • any sidelobes created are at least 5 dB less powerful than the sound beam to be directed and more preferably at least 10 dB less powerful than the sound beam to be directed.
  • the irregular pattern is created according to a mathematical relationship.
  • a mathematical relationship This assists in designing the apparatus and it helps when modelling the transducer positions.
  • Preferable mathematical relationships include spirals, such as logarithmic spirals. Such spirals are preferably "squarised” by including further mathematical functions that vary with theta such that there are four peaks as theta varies from 0 to 360°. For example, a function based on sin 2 (2theta) is suitable.
  • apparatus for creating a sound field comprising: an array of sonic output transducers, which array is capable of directing at least one sound beam in a selected direction; wherein said ' transducers are disposed in a rectangular spiral having horizontal and vertical perturbations in the transducer positions from an ideal rectangular spiral.
  • the use of a rectangular spiral allows the positions of the transducers to fall outside the area of a rectangular display screen.
  • the horizontal and vertical perturbations in the transducer positions from an ideal rectangular spiral creates a certain degree of irregularity in the pattern which helps to minimise the power of sidelobes which can be created in use of the device.
  • the use of a rectangular spiral with perturbation alleviates the creation of powerful sidelobes, even in arrays not having a central area devoid of transducers.
  • the invention is clearly also of use in the case that a substantially rectangular display screen needs to be surrounded by transducers.
  • a third aspect of the invention also provides apparatus for creating a sound field, said apparatus comprising: an array of sonic output transducers, which array is capable of directing at least one sound beam in a selected direction; wherein said array surrounds a central region devoid of transducers and suitable for mounting a display screen; and wherein said transducers are disposed in a spiral around said central region.
  • the invention provides in a fourth aspect a method of designing a sonic transducer array, said method comprising: determining a display screen area; defining a spiral curve around said display screen area upon which transducers may be placed such that said transducers do not mechanically interfere with each other or a display screen when the same is placed in said display screen area; determining the positions of each transducer along said spiral curve.
  • the use of a spiral curve in designing the transducer array allows the transducers to, on the one hand, be located in a fairly dense grouping around the periphery of the display screen (thereby ensuring that the overall apparatus size is not too large), and, on the other hand, helps to avoid a regular grid pattern being provided which can cause the creation of deleterious sidelobes.
  • the invention also includes a method of creating a sound field in which at least one sound beam is directed using an array of sonic output transducers, the output transducers being positioned such that any sidelobes created are at least 3 dB less powerful than the sound beam to be directed.
  • the apparatus comprises a central region devoid of transducers.
  • the irregular pattern is preferably a spiral and more preferably a squarised spiral.
  • Hoolix The term “Hoolix” is coined to refer to a family of curves that have some of the properties of squares (or more generally rectangles) and some of the properties of spirals.
  • a square or rectangular “curve” is a closed loop that has four straight-line segment sides in two parallel pairs (with each segment of a parallel pair having equal length, and the segments in each pair being orthogonal to the segments in the other pair, and for the square as opposed to rectangle case, the lengths of segments in each pair are also identical to each other). Also included within the definition of Hoolix such parallel pairs of line segments where the orthogonality constraint is dropped (in which case the forms of the loops are what are colloquially called "diamonds" and technically parallelograms).
  • a spiral curve is (except in the limiting case) here defined as a non-closed-loop curve which, with the increase of some parameter t, takes successively increasing or decreasing values of polar angular coordinate theta about some origin O and which takes successively increasing or decreasing values of radial coordinate r from that same origin O.
  • the particular nature of the functional relationship between r, theta and t determines the exact form of said spiral, hi Simple Spirals, the increase or decrease of r and theta with t are both monotonia.
  • Complex Spirals are defined as otherwise similarly defined curves, wherein the increase or decrease of r and theta with t are non-monotonic, but nonetheless where for each increase of theta by 2pi radians, the related increase or decrease of theta integrated over that 2pi range of theta is monotonia
  • Complex Spirals generally grow or shrink in radius with gross changes in theta but may also have "wiggles".
  • a general Hoolix is defined as any curve that meets the definition of Simple or Complex Spiral as given above, and which simultaneously has the property that certain contiguous sections of the curve opposite to each other with respect to the origin of the curve O, are approximately straight and approximately parallel, insofar as curves (rather than straight lines) may be said to be "parallel” at all.
  • curves may be said to be "parallel” at all.
  • a more specialised form of Hoolix, the Parallelogram Hoolix has just two pairs of such opposite approximately-parallel sections per (approximately) 2pi radian increase in theta.
  • Rectangular Hoolix is a form of Parallelogram Hoolix where adjacent (connected) approximately straight sections of the curve are approximately at right angles to each other.
  • Rectangular Hoolix has such adjacent approximately straight sections of the curve, also of approximately the same length as each other, giving the curve a squarish spiral shape.
  • the curve between A & B may be entirely contained within a rectangular boundary passing through A and B, where the aspect ratio of said rectangle is more than 3:1, or preferably more than 5:1, or more preferably still, more than 10:1. Ih general there will be just one smallest possible bounding rectangle completely enclosing the curve between A & B [smallest in area] and the angular position of the longer side of said smallest bounding rectangle is then said to be the "slope-direction" of the curve segment between A & B.
  • Fig. 1 shows an array of transducers that might be obtained if a standard regular pattern of prior art transducers is modified so as to provide a central area devoid of transducers for the mounting of the display screen;
  • Fig. 2 shows an array of transducers laid out along a Hoolix curve according to one aspect of the present invention
  • Fig. 3 shows some functions that can be used to create a Hoolix curve
  • Fig. 4 shows a plan view of the beam shape obtained when the array of Fig. 2 is used, at 10 IcHz;
  • Fig. 5 shows a 2 ⁇ radian beam plot for the same Hoolix array and frequency as Fig. 4;
  • Fig. 6 is similar to Fig. 4 but is for a uniform rectangular array with a hole in the middle, similar to that shown in Fig. 1;
  • Fig. 7 is similar to Fig. 5, but shows a 2 ⁇ radian beam plot for a uniform rectangular array having a hole in the centre.
  • LCD liquid crystal display
  • TV typically of about 61 cm (24 inches) diagonal size, and a few centimetres thick.
  • LCD liquid crystal display
  • the present invention proposes to reduce these problems by positioning the transducers forming the DDAA around the LCD screen, not in a regular grid pattern, but instead, laying them down in an irregular pattern. For example in a spiral pattern or at successive positions along a carefully designed Rectangular Hoolix curve (defined above). Said Hoolix curve is designed to have a starting point > ⁇ one transducer radius from a point on the outer edge of the LCD screen (and more usefully perhaps near a corner of said screen) and then proceeds in a clockwise or anticlockwise fashion around said screen such that its first Hoolix turn (by analogy with a first spiral turn) (i.e.
  • transducers may be positioned along said Hoolix trajectory without mechanically interfering with the LCD screen structure.
  • the Hoolix curve is designed to now be > ⁇ 1 transducer diameter greater in radial distance from the screen centre than at its starting point, so that successive transducers laid out along its trajectory now do not interfere with those laid out along the first turn.
  • the two predominantly straight and parallel pairs of "sides" of the Hoolix are designed to be approximately parallel to the two sets of parallel edges of the LCD screen. More and more Hoolix turns may then be "wrapped" around the screen, with gradually increasing polar radii, transducers being laid along the curve as before, such that none of the transducers mechanically interfere with any others, or with the LCD screen structure. Typically two to four Hoolix turns of transducers will. suffice to produce a useful DDAA.
  • a simple and useful strategy is to place a first transducer at the Hoolix starting point as described above, and thereafter to place successive transducers an approximately fixed distance from the previous one, as measured along the Hoolix curve/trajectory.
  • the value of this -fixed distance is a free parameter but again, typically, a useful value is one to two transducer diameters, although greater spacings also work usefully. Smaller spacings would necessarily produce mechanical interference between adjacent transducers.
  • non- fixed or irregular transducer-transducer spacings are also useful, particularly spacings that increase slowly with successive distance along the Hoolix trajectory from the inner starting point, so that the outer "ring" of transducers has greater inter-transducer spacing than the inner ring of transducers.
  • the Hoolix turns can also have successively greater turn-to-turn spacing (if for example the Hoolix is not of the simple linear Hoolix form) then the two successively increasing transducer spacing parameters (i.e. along the curve and between turns of the curve) allow for the use of larger transducers towards the outside of the Hoolix DDAA which are generally better for the reproduction of lower frequencies.
  • the transducers themselves are preferably chosen so that they have the desired audio bandwidth, and, are preferably of a diameter such that they are reasonably non- directional over the frequencies of interest for controlling by the DDAA. These requirements usually imply that the transducer diameters are smaller than an acoustic wavelength (in air or the DDAA working fluid) at, at least, half the maximum operating frequency of the transducers in the DDAA (NB not all said transducers necessarily operate over the whole DDAA bandwidth, and there are specific advantages to be had by giving greater emphasis to lower frequencies towards the outside transducers of the Hoolix and greater emphasis to the higher frequencies towards the inner transducers of the Hoolix). So, e.g.
  • the maximum frequency of interest would probably lie in the region from 16KHz to 20KHz, implying an acoustic wavelength of half these frequencies, i.e. 43mm to 17mm, and thus transducer diameters, (at least those transducers in the high-frequency region of the DDAA array which are preferably positioned closest to the LCD screen edge), within this range or smaller.
  • DDAA designed along these lines is shown in Fig. 2. It has 480 transducers of diameter 13mm distributed along such a Hoolix curve at centre to centre spacing distance of ⁇ 18mm. The positions of the points plotted correspond to the (x, y) coordinates given Table 1 below. The transducers are driven in adjacent pairs (adjacent along the Hoolix curve trajectory) for a total of 240 driver amplifiers (to reduce cost and complexity).
  • transducer centre coordinates used for this specific DDAA are shown in Table 1 annexed to the end of the description, where each triplet of columns represents; i) a transducer reference number, 1 to 480; ii) a transducer x-coordinate in mm (chosen to be a horizontal position, i.e. the direction parallel to the long edge of the LCD screen used); and iii) a transducer y- coordinate in mm.
  • the first three columns show the positions of the first 60 transducers, the next three columns the positions of the next 60 transducers, and so on for a total of 480 transducers.
  • gg is another scaling parameter relating to the amount of squareness produced
  • sqrtQ is the square root function
  • the principal feature of the above described irregular transducer layouts for DDAAs is that the resulting set of transducer positions does not result in many or any identical transducer-pair spacings and angular orientations.
  • this is meant that if one takes each transducer in turn, and pairs it with each and every other transducer in the array, the set of all spacing and relative angular directions of such pairs will form a smooth distribution with few if any peaks. Compare this with the situation if the transducers were laid out in a regular rectangular or triangular array with a hole in it (e.g. a hole large enough to place a plasma or LCD screen of say 24 inches or more).
  • the distribution of all pairings would have many distinct and strong peaks in it.
  • the effect of the smooth distribution in the irregular (e.g. Hoolix) case is to produce only (many) weak sidelobes; and in the case of the peaky distribution of the regular array, to produce a few very strong sidelobes. So use of the Hoolix layout produces a sharp main beam surrounded by a broad but low floor of weak sidelobes, with no strong sidelobes present, which is unattainable with a regular array surrounding a hole.
  • a regular rectangular spiral arrangement where the transducers are all equispaced along a set of orthogonal straight lines surrounding the hole in the array offers some improvement over a regular array but can still produce sidelobes which lower the usability of the arrangement as a DDAA array for some applications.
  • An improvement over the regular rectangular spiral can be achieved by using non- constant transducer spacing (along the square-spiral) and by using non-constant square-turn spacing - these measures flatten out somewhat the distribution of transducer pair spacings.
  • the fact that many transducers still share the same horizontal and/or vertical coordinates because of the rectangular layout
  • This effect is further reduced by applying horizontal and/or vertical perturbations to the "ideal" positions in the square spiral. By doing this, an arrangement similar to the Hoolix curve in Fig. 2 is achieved.
  • Fig. 3 shows the mathematical development of a particular Hoolix curve.
  • the basis form is the Circle.
  • Fig. 4 shows a plan view of the beam shape of a Hoolix array, at 10KHz, where the array is at bottom centre of the figure.
  • the Figure represents an 8m square area in front of the array, hi this plot the beam is focussed at a point 3m away directly in front of the array (above in the picture), so focussed nearly at the centre of the array.
  • the amplitude scale is shown on band at the RHS of the plot, the colour/shading at the top of the band representing OdB, that at the bottom -5OdB.
  • a strong well focussed beam is evident with sidelobes lower than 15dB to 2OdB down.
  • Fig. 5 shows a 2pi radian beam plot (akin to a Mercator Map projection), for the same Hoolix array and frequency as Fig. 4.
  • the beam is again focussed at 3m from the array.
  • the horizontal centre line of the plot represents longitudinal angles from - 90 to +90 degrees, at zero latitude.
  • the vertical centre line represents latitudinal angles from +90deg through Odeg at plot centre to -90deg, at zero longitude.
  • the N and S poles are spread right along the top and bottom of the plot respectively.
  • the amplitude scale is again shown by the band at the RHS with OdB at the top and - 2OdB at the bottom. Where the plot is white the amplitude is more than -2OdB down.
  • Fig. 7 is directly comparable with Fig. 5 but is again for the uniform rectangular array. What now becomes apparent is that the strong sidelobe pattern for this simple array extends in both vertical and horizontal directions.

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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)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)

Abstract

La présente invention a trait à des antennes acoustiques à réseaux à éléments à commande de phase et leur application à des haut-parleurs et microphones directionnels à faisceau simple ou multiple. Et plus particulièrement à des formes pratiques utiles de tels réseaux lorsqu'ils doivent être confinés à l'espace autour d'un écran d'affichage (tel que dans un écran de téléviseur ou d'ordinateur). L'invention a trait à un procédé permettant de résoudre les principaux problèmes inhérents aux formes de réseaux existantes lors qu'ils sont disposés autour d'un écran principalement rectangulaire. Les transducteurs sont disposés dans une formation irrégulière, telle qu'une formation spirale ou en formation spirale mise au carré.
PCT/GB2005/003528 2004-09-13 2005-09-13 Reseau de cadres Ceased WO2006030198A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0704911A GB2432743B (en) 2004-09-13 2005-09-13 Frame array

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0420240.4 2004-09-13
GBGB0420240.4A GB0420240D0 (en) 2004-09-13 2004-09-13 Quasi-rectangular frame array antennae

Publications (1)

Publication Number Publication Date
WO2006030198A1 true WO2006030198A1 (fr) 2006-03-23

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Application Number Title Priority Date Filing Date
PCT/GB2005/003528 Ceased WO2006030198A1 (fr) 2004-09-13 2005-09-13 Reseau de cadres

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GB (2) GB0420240D0 (fr)
WO (1) WO2006030198A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7515719B2 (en) 2001-03-27 2009-04-07 Cambridge Mechatronics Limited Method and apparatus to create a sound field
US7577260B1 (en) 1999-09-29 2009-08-18 Cambridge Mechatronics Limited Method and apparatus to direct sound
WO2012032335A1 (fr) 2010-09-06 2012-03-15 Cambridge Mechatronics Limited Système de réseau de haut-parleurs
US8594350B2 (en) 2003-01-17 2013-11-26 Yamaha Corporation Set-up method for array-type sound system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0323110A2 (fr) * 1987-12-21 1989-07-05 Matsushita Electric Industrial Co., Ltd. Dispositif d'écran de projection
EP0807990A1 (fr) * 1996-05-17 1997-11-19 The Boeing Company Antenne plane à réseau avec symétrie circulaire
WO2004075601A1 (fr) * 2003-02-24 2004-09-02 1...Limited Systeme de haut-parleur a faisceaux acoustiques

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0323110A2 (fr) * 1987-12-21 1989-07-05 Matsushita Electric Industrial Co., Ltd. Dispositif d'écran de projection
EP0807990A1 (fr) * 1996-05-17 1997-11-19 The Boeing Company Antenne plane à réseau avec symétrie circulaire
WO2004075601A1 (fr) * 2003-02-24 2004-09-02 1...Limited Systeme de haut-parleur a faisceaux acoustiques

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7577260B1 (en) 1999-09-29 2009-08-18 Cambridge Mechatronics Limited Method and apparatus to direct sound
US7515719B2 (en) 2001-03-27 2009-04-07 Cambridge Mechatronics Limited Method and apparatus to create a sound field
US8594350B2 (en) 2003-01-17 2013-11-26 Yamaha Corporation Set-up method for array-type sound system
WO2012032335A1 (fr) 2010-09-06 2012-03-15 Cambridge Mechatronics Limited Système de réseau de haut-parleurs

Also Published As

Publication number Publication date
GB0420240D0 (en) 2004-10-13
GB2432743A (en) 2007-05-30
GB0704911D0 (en) 2007-04-25
GB2432743B (en) 2008-01-02

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