Acoustic diaphragm and method for producing same

• US 5,274,199 A
• Filed: 04/20/1993
• Issued: 12/28/1993
• Est. Priority Date: 05/18/1990
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kurihara, Noboru, Uryu, Masaru
• Primary Examiner(s): Gellner, Michael L.
• Assistant Examiner(s): Dang, Khanh
• Application Number:
  US08/049,970
• Time in Patent Office: 252 Days
• Field of Search: 181/167, 181/169, 181/170, 428/260, 428/245, 428/265, 428/272, 428/252, 106/163.1
• US Class Current: 181/169
• CPC Class Codes: H04R 2231/001 Moulding aspects of diaphragm or surround
• CPC Class Codes: H04R 2307/021 Diaphragms comprising cellulose-like materials, e.g. wood, paper, linen
• CPC Class Codes: H04R 2307/025 Diaphragms comprising polymeric materials
• CPC Class Codes: H04R 2307/029 Diaphragms comprising fibres
• CPC Class Codes: H04R 31/003 for diaphragms or their outer suspension
• CPC Class Codes: H04R 7/02 characterised by the construction
• CPC Class Codes: H04R 7/12 Non-planar diaphragms or cones

Abstract

An acoustic diaphragm is obtained by forming micro-fibrillated cellulose into a web by a process similar to a paper-making process. The micro-fibrillated cellulose is the cellulose obtained by beating to the Canadian standard freeness of not more than 300 ml, or bacterial cellulose. Since the micro-fibrillated cellulose is poor in wet strength, it is reinforced by a reinforcement element and, in this state, is formed into the web on a wire screen. The reinforcement element may be detached after forming the web, or may be left laminated with the cellulose web so that the resulting composite product is used as the acoustic diaphragm.

Claims

1. A loudspeaker diaphragm comprising:

a micro-fibrillated cellulose element formed by a paper making process of a micro-filbrillated cellulose having a Canadian standard freeness value of not more than 300 ml and said cellulose element having an outer convex surface and a recess molded therein; and

a reinforcement element laminated to an outer, convex surface of said cellulose element opposite said recess, wherein said reinforcement comprises a cloth made from the group consisting of carbon fibers, glass fibers, polyester fibers, aramide fibers and silk.

2. A loudspeaker diaphragm according to claim 1, wherein said cloth is woven.

3. A loudspeaker diaphragm according to claim 1, wherein said cloth is non-woven.

4. A loudspeaker diaphragm according to claim 1, wherein said cellulose element has a Young'"'"'s modulus of elasticity in the range of 6.7 to 8.5 Gpa.

5. A loudspeaker diaphragm according to claim 1, wherein said cellulose element has a thickness on the order of 10 μ

m.

6. A loudspeaker diaphragm according to claim 1, wherein said recess molded in said cellulose element is hemispherical.

7. A loudspeaker diaphragm according to claim 1, wherein said recess molded in said cellulose element is conical.