Loudspeakers and their production

(19)

(11)

EP 0 272 059 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	21.03.1990 Bulletin 1990/12

(43)	Date of publication A2:
	22.06.1988 Bulletin 1988/25

(21)	Application number: 87310904.5

(22)	Date of filing: 11.12.1987

(51)	International Patent Classification (IPC)⁴: H04R 9/00, H04R 7/02

(84)	Designated Contracting States:
	AT BE CH DE ES FR GB GR IT LI LU NL SE

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Priority:

17.12.1986 GB 8630092

(71)	Applicant: Acoustic Energy Limited
	London W13 0NP (GB)

(72)	Inventor:
	Jones, Philip Keith Glen Mitcham Surrey, CR4 1DA (GB)

(74)	Representative: Walter, Douglas Ernest et al
	HASELTINE LAKE & CO. 28, Southampton Buildings London WC2A 1AT London WC2A 1AT (GB)

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References cited: :

(54)	Loudspeakers and their production

(57) The straight-sided cone or diaphragm (2) of a moving coil loudspeaker is formed wholly or principally from aluminium which is spun substantially to double its tensile strength, the spinning process being conventional and preferably being effected manually (Fig. 1). Most advantageously, the formed cone (2) is hard anodised on both sides to increase rigidity and heat radiation. A loudspeaker in accordance with the invention has approximately two and one third times the sound volume capacity of a conventional loudspeaker of comparable size without producing any detectable sound distortion.

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