PANEL-FORM LOUDSPEAKER

Abstract: A method of operating a resonant panel-form loudspeaker, comprising arranging the loudspeaker panel near to a boundary so as to be acoustically linked to the boundary and with the plane of the loudspeaker panel at an angle to the boundary. The method may comprise moving the panel between a rest position in which the panel is parallel to and adjacent the boundary and a position of use in which the panel is at an angle to the boundary. A resonant panel-form loudspeaker support comprising means engaging and retaining the loudspeaker panel to be supported, means adapted for engagement with, and fixing to, a boundary, e.g. a wall or ceilling, and means connecting the respective loudspeaker and boundary engagement means, whereby the loudspeaker is supported adjacent to the boundary and at an angle thereto and such that the loudspeaker is linked acoustically to the boundary. The combination of a resonant panel-form loudspeaker and a support as described above.

Description: TITLE: PANEL-FORM LOUDSPEAKER DESCRIPTION TECHNICAL FIELD The invention relates to panel-form loudspeakers, and more particularly, but not exclusively, to resonant panel- form loudspeakers, e.g. of the kind described in our International application WO 97/09842. BACKGROUND ART Generally loudspeakers are placed in a room coplanar or near coplanar to major adjacent walls or boundaries, and at a range of distances from that boundary. This range extends from close proximity to the boundary to an approximation of free space a metre or more from the boundary. When several loudspeakers are used in association, they are often placed such that the listener or audience to be served is on or near the geometric, median and/or designed radiating axes of the loudspeakers. This generalisation applies to both conventional near point source, i.e. pistonic, loudspeakers and to previously suggested usage for distributed mode resonant panel-form loudspeakers, the subject of WO 97/09842. Unlike a conventional pistonic loudspeaker, a distributed mode resonant panel-form loudspeaker has a largely bi-polar and naturally diffuse radiation. Interference problems can exist when such a panel-form loudspeaker is placed close to and co-planar with a boundary, leading to cancellation of the radiation from the panel surface facing the boundary. It is an object of the invention to remove or at least mitigate such boundary cancellation problems, without the need for mounting the panels in free space. DISCLOSURE OF INVENTION From one aspect the present invention is a method of operating a resonant panel-form loudspeaker, comprising arranging the loudspeaker panel near to a boundary so as to be acoustically linked to the boundary and with the plane of the loudspeaker panel at an angle to the boundary. The angle may be greater than about 10° to the boundary. The angle may be substantially normal to the boundary. If desired, the panel may be stored in a rest position parallel to and adjacent the boundary and moved to a use position at an angle thereto. From another aspect the invention is a resonant panel- form loudspeaker support comprising means engaging and retaining the loudspeaker panel to be supported, means adapted for engagement with, and securing to, a boundary e.g. a room wall or ceiling, and means connecting the respective loudspeaker and boundary engagement means, the connecting means being arranged for disposition adjacent to a side edge of the loudspeaker panel and adjacent to the boundary. Preferably, the connecting means is such that the loudspeaker panel can be moved from a storage position in which the loudspeaker panel is substantially flush with the boundary to a working position in which the loudspeaker panel extends at an angle to the boundary. The connecting means may be a hinge with a substantially vertical pivot axis. Means may be provided damping hinging movement to restrain unintended relative movement whereby the loudspeaker panel remains in a position in which it has been positioned. The respective engagement means may be such as enable fasteners, e.g. screws, to fix the engagement means to the panel and to the wall or the like. From another aspect the invention is a combination of a resonant panel-form loudspeaker and a boundary support adapted to fix the panel to the boundary such that a panel edge is adjacent to the boundary and such that the panel can be moved between a working position in which the panel is disposed at an angle to the boundary and as storage position in which the panel is flush with the boundary. The panel-form loudspeaker may be of the resonant distributed mode radiator kind as described in our co- pending International application WO 97/09842. BRIEF DESCRIPTION OF DRAWINGS The invention is diagrammatically illustrated, by way of example, in the accompanying drawings, in which :- Figure 1 is a plan view of a domestic room in which audio visual apparatus is installed; Figure 2 is a perspective view of part of the room of Figure 1 and showing a wall-mounted panel-form loudspeaker; Figure 2a is a perspective view, to an enlarged scale, of the loudspeaker shown in Figure 2; Figure 3 is a perspective view of part of a room having a ceiling mounted panel-form loudspeaker, and Figure 4 is a perspective view of a support by which a panel-form loudspeaker can be fixed to a wall or ceiling. BEST MODES FOR CARRYING OUT THE INVENTION In the drawings, and referring more particularly to Figures 1 and 2, a rectangular domestic room is bounded by a front wall 2, a rear wall 3 and an opposed pair of side walls 4,5 respectively. A listening/viewing position 6 is diagrammatically shown at the centre of the room. A visual display screen 7 is positioned centrally on the front wall 2 and may be in the form of a combined projection screen and resonant panel-form loudspeaker of the general kind described in WO97/09842, and known as a distributed mode loudspeaker. Respective front and rear pairs 8,9 and 10,11 of substantially rectangular resonant panel-form loudspeakers are mounted on the respective side walls 4,5 by supports 22 (see Figure 4) at positions which are respectively in front of and behind the listening position 6. These loudspeakers may be distributed mode loudspeakers as described in WO97/09842. Each of the loudspeakers 8,9,10,11 is arranged to be mounted on the wall such that one vertical edge of the panel is adjacent to the wall and such that the panel can be pivoted from a storage position 12, in which the panel is flush with the wall to a position of use 13, in which the panel is disposed at an angle to the wall. Alternative positions of use of the loudspeaker panels 8,9,10,11 are shown in dotted lines at reference 14. The arrangement is such that the respective loudspeaker panels are sufficiently close to the wall as to be acoustically linked to the wall so that, in use, the apparent size of each loudspeaker is effectively doubled by an acoustic mirror image reflection 15, see Figure 2. This implementation of distributed mode loudspeaker placement on side walls leaves the focal interest wall 2 in the room visually unobstructed or impaired. Edge on mounting of the loudspeaker panels 8,9,10,11 as proposed herein brings the desired operating axis of the speakers back in line for the listener (s). Test results indicate improved acoustic drive to the room and superior sound quality from smaller distributed mode loudspeaker panel designs. In Home Theatre use, distributed mode loudspeaker placement on the side walls at right angles provides a close approximation to the acoustic dipole recommended for generation of an optimum surround sound field. Figure 3 shows a generally rectangular room having adjacent walls 2,4 and a ceiling 16 on which is mounted a generally rectangular resonant panel-form loudspeaker 17, e.g. a distributed mode loudspeaker of the general kind described in WO97/09842. The loudspeaker 17 is hingedly mounted on the ceiling 16 by one edge such that the edge is adjacent to the ceiling and such that the loudspeaker can be pivoted from a use position 18, in which the panel extends generally normal to the ceiling to a storage position 19 in which the loudspeaker is flush with the ceiling. Alternative positions of use, intermediate positions 18 and 19 are shown in dotted lines at reference 20. The close mounting of the resonant panel-form loudspeaker on the ceiling means the loudspeaker is acoustically linked to the boundary represented by the ceiling so that, in use, the apparent size of the loudspeaker is effectively doubled by an acoustic mirror image reflection 21. In Figure 4 there is shown a loudspeaker support 22 by which a resonant panel-form loudspeaker of the kind shown in Figures 1 to 3 can be fixed to a boundary, e.g. a wall or ceiling of a room. The support comprises means 23 for fixing to a wall, ceiling or other boundary in the form of a plate-like wall bracket which may be secured in place by means of fasteners (not shown) such as screws or the like in conventional fashion. The wall bracket 22 carries a spaced pair of lugs 24 which carry a hinge pin 25 to which is fixed one edge of a resonant panel-form loudspeaker, e.g. that shown at 8,9,10 and 11 in Figures 1 to 3, in any convenient manner, e.g. by clamping, by fasteners, or by adhesive means as desired. In this way the loudspeaker panel may be pivoted between the position shown in full lines and the rest or storage position 12 flush against the boundary surface, as well as various positions in between, also shown in dotted lines. A thumb screw 26 at one end of the hinge pin 25 applies friction to the hinge so that the loudspeaker panel remains in whatever position is selected by the user. The present application thus proposes that a distributed mode loudspeaker is placed at or close to an appropriate boundary, in close contact via an edge at right angles or at a range or angles greater than about 10° to the boundary, the angle being set conveniently by the user, for example, enabled by a friction stabilised hinge, or other means of adjusting the azimuth angle, connecting a wall bracket and the panel speaker. The advantages of the present invention include: - (1) User adjustable boundary alignment and operating axis. (2) Boundary reinforcement of sound power, operating the wall as a mirror plane to increase loudness by 3dB. (3) Low frequency augmentation, effectively doubling panel area as a low frequency source. (4) Panel may be orientated to adjust tonal balance and directivity for optimum quality at the listening position. (5) Panel may be orientated to provide a moderate power null directed at the user/listener for beneficially reduced localisation and also improved diffuse sound field generation. This is important in Home Theatre applications . (6) Panel may be folded away for improved tidiness and room appearance when not in use. The invention thus provides a simple means of enhancing the effectiveness of a panel-form loudspeaker, particularly a distributed mode radiator, while facilitating its use and storage, e.g. in a domestic situation.

Claims: CLAIMS 1. A method of operating a resonant panel-form loudspeaker, comprising arranging the loudspeaker panel near to a boundary so as to be acoustically linked to the boundary and with the plane of the loudspeaker panel at an angle to the boundary. 2. A method according claim 1, wherein the angle is greater than about 10°. 3. A method according to claim 1 or claim 2, comprising moving the panel between a rest position in which the panel is parallel to and adjacent the boundary and a position of use in which the panel is at an angle to the boundary. 4. A resonant panel-form loudspeaker support comprising means engaging and retaining the loudspeaker panel to be supported, means adapted for engagement with, and fixing to, a boundary, e.g. a wall or ceiling, and means connecting the respective loudspeaker and boundary engagement means, whereby the loudspeaker is supported adjacent to the boundary and at an angle thereto and such that the loudspeaker is linked acoustically to the boundary. 5. A support according to claim 4, wherein the connecting means is such that the panel can be moved from a storage position in which the loudspeaker panel is substantially flush with the boundary to a working position in which the loudspeaker panel extends at an angle to the boundary. 6. A support according to claim 5, wherein the connecting means comprises a hinge. 7. A support according to claim 6, comprising means for damping hinging movement to restrain unintended relative movement . 8. A support according to any one of claims 4 to 7, 5 wherein the boundary engagement means comprises a wall bracket. 9. A support according to any one of claims 4 to 8, wherein the loudspeaker panel is a distributed mode radiator loudspeaker. 10 10. The combination of a resonant panel-form loudspeaker and a support as claimed in any one of claims 4 to 9.

Inventors: AZIMA HENRY, HARRIS NEIL, AZIMA, HENRY, HARRIS, NEIL
Applicants: AZIMA HENRY, HARRIS NEIL, NEW TRANSDUCERS LTD, AZIMA, HENRY, HARRIS, NEIL, NEW TRANSDUCERS LIMITED
Application year: 1999
Main classification: H04R7
IPC codes: H04R1, H04R5, H04R7