GB2458689A - Loudspeaker chassis formed from segments - Google Patents

Abstract

The chassis is formed from a plurality of individual peripheral segments 1 which are joined by bolts passing through holes 30 in flanges 26, 28 on the segments. The individual segments are made from die-cast aluminium or injection moulded plastics, thereby avoiding large and expensive dies as would have been necessary to form the chassis in a single casting. Resilient gaskets between the segments reduce undesirable ringing.

Description

LOUDSPEAICER CHASSIS

This invention relates to loudspeaker chassis.

A known loudspeaker chassis consists of a front ring for supporting the periphery of a loudspeaker cone, a rear ring, coaxial with the front ring and spaced axially from the front ring, for supporting a drive means for the cone, and a plurality of circumferentially spaced legs extending between the front and rear rings. Chassis of this kind are very well known and are used in a wide variety of loudspeakers, including loudspeakers for use in public address systems and in connection with electric guitars.

The chassis may be constructed in a number of ways, including being formed from die cast aluminium alloy. Such a material is particularly desirable for use in guitar speakers, but suffers from the disadvantage that, particularly for large guitar speakers, for example greater than 450 mm in diameter, production tends to be very expensive because of the need to provide a correspondingly large die for the casting of the chassis. The cost of manufacture is thereby increased, a problem which is exacerbated by the fact that such large sizes of loudspeakers tend to be produced in small quantities, perhaps no more than 1000 per year, leading to even higher unit costs.

The present invention seeks to overcome this disadvantage.

The present invention provides a loudspeaker chassis comprising a front ring for supporting the periphery of a loudspeaker cone, a rear ring for supporting a drive means for the cone, and a plurality of peripherally spaced legs extending between the rings, the chassis being formed from two or more peripheral segments which are joined to each other by joining means.

The invention also provides a chassis segment for use in forming a loudspeaker chassis according to the invention, the chassis segment comprising a portion of a loudspeaker front ring, a portion of a loudspeaker rear ring, at least one leg extending between the front and rear ring portions and means for joining the segment to one or more further segments to form the loudspeaker chassis.

Each chassis segment can be produced using a single die which consequently can be much smaller, and therefore less expensive to produce, than a die for producing the complete chassis. The invention thus allows larger diameter chassis, up to 600 rum diameter for example, to be produced economically as a result of reduced tooling costs compared with those which would be incurred by use of a single die for the complete chassis.

Preferably, each segment forms front and rear ring portions which have the same peripheral extent.

Conveniently, the joining means comprise a respective flange at each end of each segment, and fastening means joining adjacent flanges together. The flanges may be inwardly-or outwardly-directed. Lugs may be employed instead of flanges.

The fastening means may comprise nuts and bolts.

Advantageously, the joining means are formed on respective legs which are each substantially one-half of the peripheral width of a further leg extending between the front and rear rings.

Preferably, the further leg is located substantially at the peripheral mid-point of the segment.

Conveniently, there are two, three or four segments forming the chassis the segments then extending through arcs of 180°, 120° and 90°, respectively.

Preferably, the segments are formed from die cast aluminium alloy. Injection-moulded plastics could however be used instead.

Advantageously, the loudspeaker includes resilient gasket means located between the segments. Such resilient means have been found to reduce, or avoid entirely, undesirable "ringing" which might otherwise occur, particularly in metal chassis, thus improving the acoustic properties of the loudspeaker.

The gasket means may be formed in situ, or may be shaped prior to assembly of the chassis.

It should be noted that loudspeakers to which this invention relates are not necessarily circular in plan, although this will very often be the case. All other shapes, including, for example, oval, elliptical, polygonal and race-track, in which the front and rear rings are correspondingly shaped, are also covered.

An embodiment of the invention will now be described by way of example, with reference to the drawings of the

specification, in which:

Figure 1 is a perspective view of a segment of a segmented circular loudspeaker chassis, Figure 2 is a perspective view of a loudspeaker chassis constructed from four segments as shown in Figure 1, Figure 3 is a perspective view of part of two segments shown in figure 1 ready for assembly, and Figure 4 is a transverse sectional view of a loudspeaker incorporating the chassis of figure 2.

Figure 1 shows a loudspeaker chassis segment 1. This particular segment extends through an arc of 90° of the circumference of the loudspeaker chassis. Accordingly, four such segments are required to make up a complete chassis as shown in figure 2. In other embodiments, different numbers of segments can be used, for example 2, 3, 5 or even more segments. Although it is preferable that each segment should extend through the same arc of the circumference of the chassis, this is not necessarily the case. When the circumferential extent of all segments is the same, the segments can be identical to one another, as is the case with the four segments which constitute the chassis shown in figure 2.

The chassis segment shown in Figure 1 of the drawings has a front ring portion 10 which extends through a circular arc of 900 of the front ring of the loudspeaker chassis. The front ring portion 10 is shaped in cross-section in known manner to receive the outer periphery of a loudspeaker diaphragm. The ring portion 10 is also provided with a central circular hole 14 and, spaced at 45° to each side, a semi-circular hole 15 which coincides with a respective end of the segment 1.

The chassis segment 1 shown also has a rear ring portion 16 which extends through a circular arc of 90° corresponding to the arc of the front ring portion 10. The rear ring portion 16 is shaped in cross-section in known manner in order to support a suitable loudspeaker drive unit (not shown). The rear ring portion 16 also has a circular hole (not shown) mid-way between its ends.

The front and rear ring portions 10, 16 are interconnected by a leg 20 which extends therebetween mid-way between the ends of the ring portions 10,16.

The chassis segment 1 also has first and second half-legs 22, 24 each of which is half the circumferential width of the leg 20. Each half-leg 22, 24 is formed with a respective internal flange 26, 28, each of which has three holes 30 passing therethrough. The outer surfaces of the flanges 26, 28 lie flush with the outer edges of the respective half-struts 22,24. A pre-forined resilient gasket 32 (see figure 3) made from a suitable lossy material, for example, silicone elastomer, is shaped to lie along the outer surface of each flange 26,28. The gaskets 32 have holes 34 which align with the holes 30 in the flanges. Figure 3 shows one gasket 32 Positioned between the flanges 26, 28 of two aligned chassis segments ready for assembly.

In a modified embodiment of the loudspeaker described, the gaskets are formed in situ from a suitable paste or gel material.

The chassis segment 1 can be produced in a single casting operation by forcing molten aluminium into a suitably-shaped die or mould, usually of steel. The segment 1 being relatively small, the die can be produced relatively economically, leading to economic benefits in the production of a number of the chassis segments.

The construction of the complete chassis shown in figure 2 from four segments 1 as shown in figure 1 will now be described. First, two chassis segments are placed together with the flange 26 of one segment facing the flange 28 of the other, a gasket 32 lying between and the holes 30 in the flanges aligned with each other and the holes in the gasket, as shown in figure 3. The two segments are now joined together by bolts passing through the holes into nuts behind one of the flanges. Rivets could be used instead. Two further segments and three further gaskets are then added and secured similarly by nuts and bolts, or rivets, thus completing the four-unit segmented chassis shown in figure 2, in which the gaskets are not shown. Gaskets formed in situ could be used instead. In the assembled chassis the semi-circular holes 15 combine to form circular holes which, together with the holes 14, serve for mounting of the loudspeaker in a cabinet. The holes in the rear ring serve for mounting of the loudspeaker driver. The completed loudspeaker, with chassis, diaphragm 50 and driver 60 is shown in figure 4.

It will be appreciated that the individual chassis segments shown in figure 1 of the drawings are much easier and less expensive to cast from die cast aluminium than a complete chassis such as shown in figure 2 but formed in a single casting. A substantial economy in manufacture is thereby obtained without any significant drawbacks in performance or substantial increase in construction or manufacturing costs.

Similar considerations also apply if, by way of modification, the chassis segments are injection moulded in plastics material.

It will also be appreciated that the gaskets, whether pre-fox-rned or formed in situ, improve the acoustic performance of the finished loudspeaker, in that any undesirable "ringing" which might occur in their absence is considerably reduced and may be avoided altogether.

Claims (26)

1. CLAIMS: 1. A loudspeaker chassis comprising a front ring for Supporting the periphery of a loudspeaker cone, a rear ring for supporting a drive means for the cone, and a plurality of Peripherally spaced legs extending between the rings, the chassis being formed from two or more peripheral segments which are joined to each other by joining means.
2. 2. A chassis according to claim 1, in which each segment forms front and rear ring portions which have the same peripheral extent.
3. 3. A chassis according to claims 1 or 2, in which the joining means comprise a respective flange at each end of each segment, and fastening means joining adjacent flanges together.
4. 4. A chassis according to claim 3, in which the flanges are inwardly-direc
5. 5. A chassis according to claim 3 or 4, in which the fastening means comprise nuts and bolts.
6. 6. A chassis according to any of claims 3 to 5, in which the flanges are formed on respective legs which are each substantially one-half of the peripheral width of a further leg extending between the front and rear rings.
7. 7. A chassis according to claim 6, in which the further leg is located substantially at the mid-point of the segment.
8. 8. A chassis according to any preceding claim, in which there are two, three or four segments forming the chassis.
9. 9. A chassis according to any preceding claim, in which the segments are formed from die cast aluminium alloy.
10. 10. A chassis according to any preceding claim, in which the segments are formed from injection moulded plastics.
11. 11. A chassis according to any preceding claim, including resilient gasket means located between the segments.
12. 12. A chassis according to claim 11, in which the gasket means comprise pre-formed gasket pieces.
13. 13. A chassis according to claim 11, in which gasket means are formed in situ.
14. 14. A chassis segment for use in forming a loudspeaker chassis according to claim 1, the chassis segment comprising a portion of a loudspeaker front ring, a portion of a loudspeaker rear ring, at least one leg extending between the front and rear ring portions and means for joining the segment to one or more further segments to form the loudspeaker chassis.
15. 15. A chassis segment according to claim 14, in which the portions of the front ring and the rear ring have the same peripheral extent.
16. 16. A chassis segment according to claim 14 or 15, in which the joining means comprise a respective flange at each end of the segment.
17. 17. A chassis segment according to claim 16, in which the flanges are inwardly directed.
18. 18. A chassis segment according to claim 16 or 17, in which the flanges are formed on respective legs which are each substantially one-half of the peripheral width of a further leg extending between the front and rear rings.
19. 19. A chassis segment according to claim 18, in which the further leg is located substantially at the mid-point of the segment.
20. 20. A chassis segment according to any of claims 14 to 19, extending through an arc of 1800, 120° or 90°
21. 21. A chassis segment according to any of claims 14 to 20, formed from die-cast aluminium alloy.
22. 22. A chassis segment according to any of claims 14 to 20, formed from injection moulded plastics.
23. 23. A method of manufacturing a loudspeaker chassis, in which a plurality of chassis segments according to any of claims 14 to 22 are joined together to form the chassis.
24. 24. A segment for use in forming a loudspeaker chassis, the segment being substantially as hereinbefore described with reference to the drawings.
25. 25. A loudspeaker chassis segment substantially as hereinbefore described with reference to the drawings.
26. 26. A method of manufacturing a loudspeaker chassis, the method being substantially as hereinbef ore described with reference to the drawings.