# US 4,395,814 A · Acoustic vibrating element of graphite and method of manufacturing same

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- Number: US 4,395,814 A
- Document ID: US4395814A
- Status: Granted
- Kind: A
- Application number: 06/315,564
- Filed: 1981-10-27
- Granted: 1983-08-02
- Earliest claimed: 1977-02-28
- Assignees: Pioneer Electronic Corporation
- Inventors: Tsunehiro Tsukagoshi; Teruo Tohma; Shinichi Yokozeki
- Web page: https://patentgrep.com/patent/US4395814A

## CPC

- H04R 1/18: Holders for styli; Mounting holders on transducers
- H04R 7/02: characterised by the construction
- H04R 7/127: {dome-shaped}
- H04R 2307/023: Diaphragms comprising ceramic-like materials, e.g. pure ceramic, glass, boride, nitride, carbide, mica and carbon materials
- Y10T 29/49005: Acoustic transducer
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An acoustic vibrating element, such a domed speaker diaphragm A or a phonographic pickup cantilever B, is formed by vapor deposition on an easily separable mold member 5 of tantalum or tantalum alloy when a mixture of a hydrocarbon gas and an inert gas is passed through a furnace heated to a temperature of 1150.degree. C.-1250.degree. C. at a flow rate in excess of 200 cm/min. The c-axis crystalline orientation of the resulting graphite element is substantially perpendicular to its surface, which provides a Young's modulus above 16,000 Kg/cm.sup.2.

## Claims

### Claim 1

In a method for producing an electro-acoustic transducer comprising a vibrating member and means for vibrating the vibrating member, the improvement comprising the step of: introducing a mixture of a gaseous carbon compound and an inert gas and/or hydrogen into a furnace; subjecting said mixture to thermal decomposition to thereby deposit a layer of carbon on a surface of a mold former having a desired configuration, wherein the flow rate of said gaseous carbon compound is sufficiently high that the crystallographic c-axis of said layer of carbon is substantially perpendicular to the surface of said layer of carbon; separating said layer of carbon from said mold former to thus obtain said vibrating member; and mounting said vibrating member in a position to be vibrated by said vibrating means.

### Claim 2 (depends on 1)

The method of claim 1 wherein said carbon layer has a Young's Modulus above 16,000 kg/cm.sup.2.

### Claim 3 (depends on 1)

The method of claim 1 wherein, in said step of subjecting said mixture to thermal decomposition, a temperature in a range of 1,150.degree. C. to 1,250.degree. C. is utilized.

### Claim 4 (depends on 3)

The method of claim 3 wherein, in said step of introducing said mixture into said furnace, said mixture has a continuous flow rate above 200 cc/min.

### Claim 5 (depends on 1)

The method of claim 1 further comprising the step of, following said step of subjecting said mixture to thermal decomposition, subjecting said layer to a heat treatment in an inert gas atmosphere at a temperature in a range of 2400.degree. C. to 2700.degree. C. for a time in a range of 3 to 60 minutes.