WO2007115373A1

WO2007115373A1 - A side baffle for a loudspeaker

Info

Publication number: WO2007115373A1
Application number: PCT/AU2007/000474
Authority: WO
Inventors: Charles Corneles Van Dongen; Craig Douglas Evans
Original assignee: Immersion Technology Property Limited
Priority date: 2006-04-11
Filing date: 2007-04-11
Publication date: 2007-10-18
Also published as: AU2007236555A1

Abstract

A side baffle (50) for a loudspeaker for enhancing the output response of the loudspeaker relative to a particular environment in which the loudspeaker is located. The side baffle is made up of preferably three baffle sections (52, 54, 56) which are pivotally (78-66) (86-72) or telescopically mounted together whereby the baffle sections are relatively adjustable to vary the width and/or angle and/or curvature of the side baffle. The baffle sections may be formed from extruded sections and the inner baffle section may be formed with a channel (58) for clipping onto a side edge of the loudspeaker. The baffle sections (52, 54, 56) may be adjusted for the side baffle (50) to control low frequency cut-off, the effect of backwave, room modes or dispersion of the acoustic output sound waves of a loudspeaker.

Description

A SIDE BAFFLE FOR A LOUDSPEAKER

Technical Field

The present invention relates to a side baffle for a loudspeaker, that is, to a device for extending laterally from a side edge of a loudspeaker.

Background of the Invention

A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was, in Australia, known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Dipole loudspeakers including electrostatic loudspeakers suffer with reduction in bass frequency output due to front to rear cancellation effects. Bass output can be enhanced by extending the width of a baffle upon which a dipole loudspeaker panel is mounted. Increasing the width of such a baffle will improve bass output, but some disadvantages occur with this approach.

Thus, loudspeakers with wide baffles, particularly electrostatic loudspeakers, can be difficult to optimally place in a listening environment due to the width of the loudspeaker. As rooms are rarely symmetrical in size and due to furnishings, wall and window treatments, an uneven response is often obtained from such loudspeakers. This may be dealt with by some form of electronic equalisation in the form of tone controls mounted on the loudspeaker or amplifier, or by the use of a graphic equaliser. Unfortunately, these additional components often degrade the sound quality forcing a compromise to be made.

Wide loudspeakers can also provide excessive bass response in smaller rooms, again leading to unsatisfactory performance.

Baffles also affect the sound level of monopole loudspeakers projected to a listening area. Disclosure of the Invention

According to the present invention there is provided a side baffle for a loudspeaker including a plurality of baffle sections, wherein one baffle section includes at least one attachment device for attaching the side baffle to an outer edge of a loudspeaker surround, and wherein the side baffle includes at least one other baffle section which is attached to said one baffle section such that it is adjustable relative to said one baffle section to vary a width of the side baffle and/or an angle between said one and said other baffle sections.

The terminology "a loudspeaker surround" as used herein means, for example, the cabinet containing an electromagnetically driven loudspeaker or the outer frame of an electrostatic loudspeaker panel. A side baffle according to the invention is preferably attachable to a respective one of opposite side edges of the surround (usually a front side edge), for the side baffle to extend laterally from the loudspeaker surround. The side baffle can then be adjusted to vary the width (that is, the lateral extension) and/or angle, and/or curvature thereof relative to the front face of the loudspeaker to enhance the output response of the loudspeaker relative to the particular environment in which the loudspeaker is located.

Preferably the attachment device of said one baffle section is such that it allows that baffle section to pivot relative to the loudspeaker surround.

Preferably the side baffle includes at least three baffle sections which are adjustable relative to each other.

Preferably the baffle sections are hingedly attached together and are foldable relative to each other to vary the width and/or curvature of the side baffle.

Alternatively the baffle sections may be telescopically or slideably mounted relative to each other whereby the width of the side baffle is variable.

Embodiments of the invention offer several advantages. For example they provide for enhancement of low frequency response and output. Also a variable width side baffle (which embodiments of the invention effectively provide) can be adjusted in width or angle to enhance or reduce low frequency response to suit the room requirements. A folding section side baffle additionally allows for adjustment of the side baffle to different shapes or curvatures which in certain circumstances may be effective in controlling the polar pattern of the loudspeaker, for example the sections of the side baffle may be adjusted to substantially describe a logarithmic curve. Embodiments of the invention may also allow the elimination of any need for additional equalization components, whether such components are provided within the loudspeaker, as an add-on component or as tone controls on a pre-amplifier. Furthermore, embodiments of the invention provide an ability to adjust low frequency response to suit a wide range of room sizes and shapes while maintaining tonal and phase accuracy of an original signal.

Where necessary, such as in asymmetric rooms, each loudspeaker side baffle may be adjusted individually to provide the performance required for that particular room position. As an example, a left-side loudspeaker not fitted with any side baffle may be placed close to a room corner, which will enhance bass output due to the interaction of the loudspeaker and the corner walls. A right- side loudspeaker not fitted with any side baffle may be placed away from a corner, causing the loudspeaker to present a completely different low frequency response leading to an uneven sonic presentation, poor imaging and sound staging. In this case the fitting of side baffles would allow the left loudspeaker to have the side baffle sections folded (or telescoped) in so as to minimise bass frequency enhancement whereas on the right loudspeaker the baffle sections would be folded (or telescoped) out to provide compensation for the corner gain achieved by the left loudspeaker. This cannot be done with conventional loudspeaker baffles.

Smaller listening rooms can be equally served by having the adjustable baffle sections retracted, which will minimise the front profile of a loudspeaker and reduce bass output to a level more acceptable for the listening environment. Also in embodiments of the invention the baffle section attachable to an electrostatic loudspeaker panel can act as a structural member of the electrostatic panel making the panel more efficient to manufacture. It is also possible for this baffle section to act as a cosmetic trim to the loudspeaker eliminating the need for additional trim components.

Preferably the baffles are formed of aluminium, for example by extrusion, and may have a central void. Such a central void may be filled with non-resonant foam material giving effective damping of the extrusion. This will prevent ringing and colouration of the sound wave.

For a better understanding of the invention and to show how it may be performed, embodiments of the invention will now be described, by way of non- limiting example only, with reference to the accompanying drawings.

Brief Description of Drawings Figure 1 A is a schematic perspective view of side baffles according to an embodiment of the invention attached to a loudspeaker panel.

Figure 1 B shows a detail of the Figure 1 A embodiment, that is, an arrangement for attaching the side baffle to a loudspeaker panel.

Figure 1 C shows an alternative arrangement for attaching a side baffle to a loudspeaker panel.

Figure 1 D shows a schematic perspective view of the side baffles according to the Figure 1A embodiment of the invention attached to loudspeaker panels of a flat screen (plasma/LCD) television.

Figure 2 is a partially exploded perspective view of a top portion of a side baffle according to another embodiment of the present invention.

Figure 3 shows a top view of the embodiment of Figure 2 in a folded condition.

Figures 4, 5 and 6 are cross-sections of extruded sections for forming a side baffle as illustrated in Figures 2 and 3. Figure 7 is a schematic cross-section of a side baffle according to another embodiment of the invention.

Figure 8 schematically illustrates an electric motor arrangement for adjusting a side baffle.

Detailed Description

With reference to Figure 1 A, a loudspeaker panel 20 (which may for example be an electrostatic loudspeaker) is shown which has a surround or outer frame 22 having opposite outer side edges 24. A side baffle 26 is attached to each outer edge 24 of the loudspeaker 20 surround 22 such that the side baffles extend laterally from the loudspeaker panel 20. Each side baffle includes at least two baffle sections 28, 30, which are attached together such that they are relatively adjustable, for example they may be hinged together as indicated by reference 32 such that section 30 can be folded against section 28 to reduce the width of the side baffle 26, or section 30 can be turned to vary the angle between it and section 28, for example from 180° to a lesser angle such that the baffle section 30 extends backwardly relative to section 28 and the front of loudspeaker panel 20.

Each side baffle 26 includes an attachment device, for example a hinge component indicated by reference 34 (to be described in detail below with reference to Figure 1 B), for attaching the side baffle 26 to an outer edge 24 of the loudspeaker 20 surround 22. The attachment device 34 allows the baffle section 28 to pivot relative to the loudspeaker panel 20.

The attachment device may be a hinge component 34 in the form of a bracket which, with reference to Figure 1 B, is attached to the end surface 36 of the baffle section 28 and having an aperture 38 for receiving a pin 40 carried by another bracket 41 which is attached, for example by screws 43, to the loudspeaker surround 22. Alternatively the bracket 34 could be attached to the loudspeaker surround 22 and the bracket 41 with its pin 40 attached to the baffle section 28. Alternatively the attachment device may include a channel section 42 along a side edge 44 of the baffle section 28 (see Figure 1 C) which fits over an outer side edge 24 of the loudspeaker surround 22 and which includes manually adjustable clamping devices, for example screws 46, for clamping the baffle section 28 onto the outer edge 24 of the loudspeaker surround 22. This attachment does not allow adjustment of the panel section 28 relative to the loudspeaker panel 20. Instead of providing clamping screws 46, the channel section 42 may be magnetically attached to the loudspeaker surround 22 by means of embedded magnets for example in the channel and a ferrous metal component in the loudspeaker side edge of surround 22 such that the panel section 28 is readily adjustable. In a further alternative, the channel section may be shaped and dimensioned relative to the loudspeaker side edge 24 of surround 22 such that it slides over or clips onto the surround 22 to be frictionally retained in place.

Figure 2 illustrates a side baffle 50 which includes three baffle sections 52, 54, 56. The first baffle section 52 is formed to include a channel 58 (that is, an attachment device) along one side which has opposite legs 60 having facing beads 62. The legs 60 with the beads 62 are for clipping onto the outer edge of a loudspeaker surround, such as the outer edge 24 of a surround 22 of a loudspeaker panel 20 as illustrated in Figure 1 A, whereby the outer edge 24 seats within the channel 58. The baffle section 52 has a curved front face 53 and an outer side edge 64 region which is formed to include a hole 66.

The second or middle baffle section 54 has a curved front face 55 and an inner side edge 68 which is shaped to conform with the shape of the side edge 64 of the first baffle section 52 such that when the two baffle sections 52, 54 are relatively pivoted, there is effectively a substantially continuous smooth outer or front surface provided by the curved front faces 53 and 55 of the two baffle sections 52, 54, that is, there is a minimal (for example a virtually imperceptible) gap at the transition from the curved front face 53 of the first baffle section 52 to the curved front face 55 of the second baffle section 54 at the facing surfaces of the side edges 64 and 68. The other side edge 70 region of the baffle section 54 is formed to include a hole 72. A bracket 74 is fixed to an end surface 76 (for example top end) of the baffle section 54 by, for example, screws 75 (only one of which is illustrated) and includes a pin 78 which snugly fits within the hole 66 of the baffle section 52. A similar bracket is attached to the opposite end surface (for example bottom end) of the baffle section 54. Thus the second baffle section 54 is hingedly attached to the first baffle section 52 whereby it is able to be pivoted relative to that baffle section 52 and thus to a loudspeaker panel when the baffle section 52 is attached to such a panel.

The third or end baffle section 56 has a curved front face 57 and an inner side edge 80 that is shaped to conform with the shape of the side edge 70 of the baffle section 54 such that the curved front faces 55 and 57 of the two baffle sections 54 and 56 effectively present, like the baffle sections 52 and 54, a substantially continuous smooth outer or front surface across the two baffle sections when the baffle sections are unfolded. A bracket 82 is fixed to an end surface 84 of the baffle section 56 by, for example, screws (not shown) and includes a pin 86 which snugly fits within the hole 72 of the baffle section 54. A similar bracket is attached to the opposite end surface of the baffle section 56. Thus the third baffle section 56 is hingedly attached to the second baffle section 54 whereby it is able to be pivoted relative to that baffle section 54.

The fit of the pins 78 and 86 into the holes 66 and 72 is somewhat like that of a stiff journal bearing whereby the baffle sections, respectively 52 and 54, and then 54 and 56, are firmly attached to each other yet able to be pivoted, for example manually, to adjust their relative positions and for those relative positions to be maintained during use of a loudspeaker to which the side baffle 50 is attached, particularly when loud bass acoustic sound waves are being generated by the loudspeaker. Thus when the baffle sections 54, 56 have been manually adjusted to their desired positions, they retain those positions during use of a loudspeaker due to the frictional force between the pins 78 and 86 in the respective holes 66 and 72 and the weight of the baffle sections. Figure 3 illustrates the side baffle 50 in a folded condition whereby the end or third baffle section 56 is located between the first baffle section 52 and the second baffle section 54.

Figures 4, 5 and 6 illustrate, in cross-section, extruded sections for forming, respectively, the baffle sections 52, 54 and 56. These sections may be formed of aluminium and may each have a central void or voids, respectively 88, 90, 92. To form the baffle sections 52, 54 56 the voids 88, 90, 92 may be filled with a foam material (indicated by reference 94 on baffle section 52 of Figure 2) for damping the baffle sections, that is, to prevent resonances and thereby ringing or colouration of the acoustic sound waves generated by a loudspeaker. The extrusions may be formed of suitable materials other than aluminium, for example a plastic or alloy. The use of such extruded sections for the baffle sections offers the additional advantage that the height of the baffle sections can be readily determined (by cutting off suitable lengths of the extruded sections) to suit loudspeakers of different heights.

Figure 7 illustrates in cross-section a side baffle 100 that includes three telescopically mounted baffle sections, that is, a first or inner (relative to a loudspeaker) baffle section 102, a second or middle baffle section 104 and a third or outer baffle section 106. Figure 7 (in which the dimensions of the various features have been arbitrarily expanded or reduced for clarity) illustrates the three baffle sections as telescoped together whereby the side baffle 100 presents its smallest width outer facing surface 107. Baffle section 102 includes a hole 108 for pivotal attachment of the side baffle 100 to a loudspeaker surround (for example via a bracket and pin 40-42 as in Figure 1 B). The baffle section 102 also includes an interior void 1 10 for slidingly accommodating the second baffle section 104 and having a step shoulder 1 12 adjacent and along its outer side which provides a stop for the second baffle section 104. The second baffle section 104 includes a stepped flange 1 14 along its inner end which contacts the step 1 12 of baffle section 102 to define the outer telescopic limit of baffle section 104 relative to baffle section 102. Similarly, baffle section 104 includes a void 1 16 for baffle section 106 having a stop shoulder 1 18 for limiting the outward telescopic movement of baffle section 106 relative to baffle section 104 via a stop 120 on the baffle section 106.

The baffle sections 102, 104 and 106 may be manufactured from any suitable material, for example a light metal such as an alloy or aluminium, or a plastics material. The chosen material, to be suitable should be such that it damps or prevents any resonances from an acoustic output of the loudspeaker to which the side baffle 100 is to be attached.

With the side baffle 100, the baffle sections 102, 104 and 106 can be adjusted relative to each other to vary the width of the side baffle 100.

It is to be understood that the side baffles of the present invention may also be used to extend above and/or below a loudspeaker, as well as sideways. Thus the term "side" as used in this specification is to be understood as including any peripheral side of a loudspeaker such as its top or bottom as well as its lateral sides.

Figure 8 illustrates in plan view portion of the side baffle 50 of Figure 2 comprising baffle sections 52 and 54 and additionally including an electric motor device 122 attached to the baffle section 52 which via a pinion 123 drives a gear 124 for meshing with a gear 125 attached to the pin 78 of bracket 74 of baffle section 54. Thus by operating the electric motor 122, which may be done remotely as indicated by remote controller 126, the gear 124 is driven which in turn drives the gear of pin 78 to thereby adjust the angle of baffle section 54 relative to baffle section 52. Similar motor driven arrangements may be provided for operating all of the baffle sections of the side baffles disclosed herein to vary the width of a side baffle and/or the angle between the baffle sections or the angle between a side baffle and a loudspeaker.

It is to be understood that other embodiments not specifically disclosed may incorporate any number of and any combination of the features of the above described embodiments. Thus, for example, a side baffle may be provided that combines pivotal and slidable or telescopic baffle sections. It is also envisaged that a side baffle may be arranged relative to a loudspeaker in which the baffle sections telescope into a cabinet of the loudspeaker.

Side baffles according to embodiments of the invention may also be used in conjunction with television screens containing a loudspeaker for example as indicated by Fig 1 D. Fig. 1 D shows a flat screen television 23 (for example plasma or LCD screen) with stereo loudspeaker panels 20 attached to left and right side edges as is typical for this style of television. Side baffles 26 as described in relation to Fig 1 A are attached to the free sides of the loudspeaker panels 20, that is to the left side edge of the left loudspeaker panel and to the right side of the right loudspeaker panel.

The side baffles as disclosed herein are adjustable to adapt a loudspeaker (or television screen containing loudspeakers) to a wide range of room layouts and loudspeaker placements. For example they may be adjustable in width to control low frequency cut off, or adjustable in angle and/or contour to control the effect of backwave for dipole loudspeakers, or to control room modes, or to control dispersion of the acoustic sound waves.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and illustrated and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the scope of the following claims.

Claims

1 . A side baffle for a loudspeaker including a plurality of baffle sections, wherein one baffle section includes at least one attachment device for attaching the side baffle to an outer edge of a loudspeaker surround, and wherein the side baffle includes at least one other baffle section which is attached to said one baffle section such that it is adjustable relative to said one baffle section to vary a width of the side baffle and/or an angle between said one and said other baffle sections.

2. A side baffle as claimed in claim 1 wherein the attachment device of said one baffle section is such that it allows that baffle section to pivot relative to the loudspeaker surround.

3. A side baffle as claimed in claim 1 or claim 2 which includes at least three baffle sections which are adjustable relative to each other.

4. A side baffle as claimed in any one of claims 1 to 3 wherein the baffle sections are hingedly attached together and are foldable relative to each other to vary the width of the side baffle.

5. A side baffle as claimed in any one of claims 1 to 4 wherein each baffle section has a curved front face.

6. A side baffle as claimed in claim 5 wherein the baffle sections are adjustable relative to each other to vary the curvature of the side baffle.

7. A side baffle as claimed in any one of claims 1 to 3 wherein the baffle sections are telescopically or slideably mounted relative to each other whereby the width of the side baffle is variable.

8. A side baffle as claimed in any one of claims 1 to 7 wherein the at least one attachment device includes a channel section for sliding over or clipping onto the outer edge of a loudspeaker surround.

9. A side baffle as claimed in any one of claims 1 to 7 wherein the at least one attachment device includes a manually adjustable clamp for clamping onto the outer edge of a loudspeaker surround.

10. A side baffle as claimed in any one of claims 1 to 7 wherein the at least one attachment device includes a hole for receiving a pin of a bracket which is attachable to a loudspeaker surround.

1 1 . A side baffle as claimed in any one of claims 1 to 7 wherein the at least one attachment device and said one baffle section are connected together by a hinge.

12. A side baffle as claimed in any one of claims 1 to 1 1 wherein the baffle sections are extruded sections.

13. A side baffle as claimed in claim 12 wherein the extruded sections of each baffle section have a void which is filled with a foam material for damping the baffle sections.

14. A loudspeaker having a surround with two opposite side edges, and a side baffle as claimed in any one of claims 1 to 13 attached to at least one of said side edges.

15. A loudspeaker as claimed in claim 14 wherein each side baffle includes motor driven devices for operating the baffle sections to vary the width of each side baffle and/or the angles of the baffle sections relative to the loudspeaker.

16. A loudspeaker as claimed in claim 15 wherein the motor driven devices are remotely operable.