GB2099659A

GB2099659A - Ring radiator for loudspeakers

Info

Publication number: GB2099659A
Application number: GB8215365A
Authority: GB
Original assignee: CELESTION INT Ltd
Current assignee: CELESTION INT Ltd
Priority date: 1981-05-26
Filing date: 1982-05-26
Publication date: 1982-12-08
Also published as: EP0065883A2; EP0065883A3

Abstract

A ring radiator for a loudspeaker has an annular inner portion (24) and an annular outer portion (22) and a tubular former (24c) carrying a coil (28) and positioned at the junction of said portions. Instead of securing the former to the radiating element by a butt joint the former is here made with at least one of the portions (e.g. 24a, 24b) of the radiating element. If integral with just one portion of the radiating element, the wound component is then secured to the other portion (22), preferably by an adhesive lap joint. <IMAGE>

Description

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GB 2 099 659 A 1

SPECIFICATION

Ring radiator for loudspeakers

This invention relates to an improved construction of loudspeaker which incorporates 5 what is known as a ring radiator. Loudspeakers which incorporate a ring radiator have an annular diaphragm which is held clamped at both its inner and outer peripheries and which is vibrated by the movements of a coil which is coupled to the 10 diaphragm.

One conventional construction of ring radiator for a loudspeaker comprises a diaphragm element formed as an annulus having generally horizontal inner and outer webs and a substantially V-1 5 shaped valley zone between them. The inner and outer webs are rigidly clamped by support washers. A separate tubular former carries the coil windings. Conventional practice has been to secure the wound former to the apex of the valley 20 zone of the diaphragm by means of an adhesive using a butt joint. In order to improve the adhesion, the tubular former is sometimes provided with a tongue to provide an increased surface area for adhesive contact with the 25 diaphragm.

This conventional form of construction has a number of disadvantages. Firstly, it is a relatively fragile construction, relying as it does upon a butt joint to secure the wound former to the 30 diaphragm. Secondly, with this form of construction the former has to be wound first with the coil, and this delicate combination then has to be brought up to the diaphragm and secured thereto. This involves handling problems and the 35 possibility of damage to the components. It is also not easy to wind the coil on to the tubular former. Furthermore, it has also been found that with this form of construction the response characteristics often include undesirable resonances, primarily 40 due to poor coupling between the coil and the diaphragm through the butt joint.

It is an object of the present invention to provide an improved ring radiator for a loudspeaker, and also an improved method of 45 manufacture of such a radiator.

In accordance with the present invention there is provided a ring radiator for a loudspeaker, comprising a radiating element having annular inner and outer portions, and a former carrying a 50 coil and positioned radially substantially at the junction of said inner and outer portions, wherein said former is integral with at least one of said inner and outer portions.

In a preferred embodiment of the invention, the 55 coil former is formed integrally with one of said inner and outer portions and the other said portion is secured to said one portion, preferably by an adhesive lap joint.

Preferably, the element which constitutes the 60 coil former is provided with a circumferential lip or return at the end remote from the radiating element, in order to prevent the coil turns from becoming detached.

Also, in accordance with the present invention

65 there is provided a method of making a ring radiator for a loudspeaker which comprises the steps of producing a tubular former integrally with at least a portion of an annular radiating element, and thereafter winding a coil on said former. 70 In the preferred method in which the former is integral with just one portion of the annular radiating element, the coil is wound on the former and then the wound component is secured to a further portion of the radiating element, for 75 example by means of an adhesive lap joint.

The method of construction in accordance with the present invention, and the product produced thereby, has considerable advantages as compared with the conventional arrangement. 80 The ring radiator of the present invention is tough and robust, and is much less liable to damage than the conventional radiator. Additionally, because of the direct coupling of the coil to the radiating element one achieves a much smoother 85 response, without the undesirable resonances which characterise conventional ring radiators. Furthermore, the winding of the coil is greatly simplified with the form of construction of the present invention, resulting in more consistent 90 performance, less wastage, and ease of handling with automated assembly machinery.

The ring radiator of the present invention is particularly suitable for loudspeakers which operate within a frequency range of 2 KHz to 16 95 KHz, although these frequencies are not to be taken as being limiting frequencies.

In order that the invention may be fully understood, one preferred embodiment of ring radiator in accordance with the invention will now 100 be described in way of example and with reference to the accompanying drawings, in which:—

Fig. 1 is a schematic view, taken as a section through one side of the ring, of a known 105 construction of ring radiator; and

Fig. 2 is a view, similar to Fig. 1, of a ring radiator in accordance with the invention.

A conventional construction of a ring radiator is shown in Figure 1 of the drawings which is a 110 schematic sectional view through just one side of the ring radiator, the section through the diametrically opposite side being the same. In this construction, the diaphragm element 10 is formed as an annulus having generally horizontal 115 inner and outer webs 10a and 10b respectively and a substantially V-shaped valley zone. The inner and outer webs 10a and 10b are rigidly clamped by support washers 12. A separate tubular former 14 carries the coil windings 16. 120 Conventional practice has been to secure the wound former to the apex of the valley zone of the diaphragm 10 by means of an adhesive using a butt joint as indicated at 18. In order to improve the adhesion, the tubular former 14 is sometimes 125 provided with a tongue, indicated in broken lines at 20, to provide an increased surface area for adhesive contact with the diaphragm 10.

Referring now to Figure 2, it will be seen that the annular radiator here comprises an outer

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GB 2 099 659 A 2

annular portion 22, and an inner annular portion 24. Clamping washers 26 are shown for each radiator portion, but these are optional. The outer annular portion 22 comprises a horizontal web or 5 limb 22a, a sloping limb 22b and an upturned tongue 22c. The inner annular portion 24 comprises a horizontal limb 24a, a sloping limb 246, and, integrally therewith, a portion 24c which constitutes a tubular former for the 10 windings of a coil 28. The tubular portion 24c has a flange or return 2 4</which serves as a seat for one end of the coil windings to prevent turns of the coil from becoming detached.

In manufacture, the one annular radiator 15 portion 24 is first produced by a suitable shaping process. The coil 28 is then wound on that element 24, using the flange 24d as a stop. The other, outer annular portion 22 of the radiator is then presented to the wound element so that the 20 tongue 22c makes a lap joint with the face of the sloping limb 246 of the element 24. A suitable adhesive is used between the two parts to give a strong joint. It will be appreciated that because one has surface-to-surface contact here, as 25 compared with point contact in many of the conventional arrangements, one can achieve much better adhesion and a more reliable joint.

The material of the ring radiator of the present invention may be any suitable material, for 30 example bakelised cloth, aluminium, a plastics material, etc.

Although in the preferred embodiment described above the portion 24c which constitutes the former on which the coil is wound 35 is integral with the radially inner portion of the radiator, it could alternatively be made integral with the radially outer portion 22 of the radiator. Alternatively, it could be made integral with both portions 22 and 24 of the radiator, in which case 40 no separate jointing steps would be necessary.

Claims

1. A ring radiator for a loudspeaker, comprising a radiating element having annular inner and outer portions, and a former carrying a coil and

45 positioned radially substantially at the junction of said inner and outer portions, wherein said former is integral with at least one of said inner and outer portions.

2. A ring radiator as claimed in claim 1, in

50 which the former is integral with one of said inner and outer portions, and the other said portion is secured to said one portion by an adhesive joint.

3. A ring radiator as claimed in claim 2, in which the joint is a lap joint providing surface-to-

55 surface contact between an annular tongue on said other portion and an annular surface on said one portion.

4. A ring radiator as claimed in any preceding clairri, in which the former is tubular and is

60 provided with a circumferential lip at the end remote from the radiating element.

5. A ring radiator as claimed in any preceding claim, in which said inner and outer portions of the radiating element each comprise a flat web

65 portion and a sloping web portion with said sloping web portions defining a substantially V-shaped valley at the bottom of which the former is located.

6. A method of making a ring radiator for a

70 loudspeaker which comprises the steps of producing a tubular former integrally with at least a portion of an annular radiating element, and thereafter winding a coil on said former.

7. A method as claimed in claim 6, which

75 comprises making the former integrally with one annular portion of the radiating element, then winding the coil on the former, and thereafter securing the wound component to a further annular portion of the radiating element.

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8. A method as claimed in claim 7, in which the wound component is secured to said further portion by an adhesive lap joint.

9. A ring radiator for a loudspeaker substantially as hereinbefore described with

85 reference to Fig. 2 of the accompanying drawings.

10. A method of making a ring radiator for a loudspeaker substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, J 982. Published by the Patent Office, 25 Southampton Buildings, London. WC2A 1 AY, from which copies may be obtained.