AU525975B2 - Structural material for acoustic machines - Google Patents

Description

1EGULATLON 11(l) FORMA 4 259?51 r COMONWEALTH OF AUSTRALIA PATENTS, ACT 1952-1976 CONVENTION APPLICATION FOR A PATENT

4867319 Here Insert (in fu lame of Company. We, .AIKOH CO. LTD. a corporation organised

tnder the laws of Japan, of No. 1-39, 2-chome, Ikenohata, 3) Here Insert Title ivention. Taito-kv., Tokyo, Japan, hereby apply for the a Patent for an invent2 ,on entitled:- A At

3039A "STRUCTURAL MATERIAL FOR COUSTC Mj J79t :and Here insei a ut*ame an~d Addre *4* P Ampany Officli ithorised mal WA eciaration. A 0 a 40*9 which is deacribed in the accompanyi-ng Complete Specification. a. A, A *1 *0 This Application is a Convention Application and is I. OcO p A ASO based on the Application numbered 8-1685/78 *9I~* r.-Here Insert iBash aunt-Ty or Countrie: for a Patent or similar protection made in Japan. liowed by date or date Basic Application(s)

on 20h July, 1978. Here isert Ful ame(s) of Applicant(s &Go Basic Country. Our address for service is:- 7HeTe Insert (in full~ 361q, and Address 01 tuai Inventor a0 velora. SHELSTON WATERS,

4 AND AME4NS 55 Clarence Street, APPUC2Afl2-NACCPIED QA

Sydney. N-SW. 2000. DATET' this 5th day of JUJLY, 1979 *3 C

AIK')H CG. LTD. 0 A 0

Fellow Institute of Patent Attorneys of Australia of SH ELSTON' P ersonal Signature To: The Commissioner of Patents, Dciamo~t (n~o seal, itnass or 'Agalisatlon), WODEN. A.C.T. Fee: $40-00 File: D.B. 152 gm

sue] This invention relates to anIIprovmeYnt in or relating to a structural nmterial for acou"&,c machilnes

(CONVENTION Compony) FORM 8 REGULATION 12 (2)

COMMONWEALTH OF AUSTRALIA PATENTS ACT, 1952-1973 f- DECLARATION IN SUPPORT OF A CON VENT fON APPLICATION FOR A PATENT

48 67 tI /7 In support of the Convention Application No made 1) Here Insert (In full) by(a) IAP,.T lame of Company.

(hereinafter -referred to as "Applicant") for a pamnt for an invention entitled Here Insert Title of "STRUCTURAL MATERIAL FOR ACOUS TIC MACHINES AND iventlon. INSTRUMENTS"

MASKRU TAKASHIMA ~and HeeInsert uaeand Address I- ;.tmpany Official ithorise* eclaration. t. make of(d) No. I-9 -coe Ikn2aa, -u

do solemnly and sincerely declare as follows: 1 I am authorised by Applicant to make this declaration on its behalf. 2. The basic Application(.4 as defined by section 141 of the Act was/wm made SHere Insert Basic ountiy or Countries *llowed by date or dates in on tha 1 .day 19 7A~ Basic Application(s). on the day of 19 I Here isert Full aine(s) of Applica nt(s) Mf AIKOH CO LTD Basic Country. SHe~ Insert (in full) 3. (g .TMOTUHY n ~~nd Add-.ess of tual Inventor or vdt~ors.

of 26. -16, Ko q~t

the actual ln~entor,() of the itivention and the facts upon which Applicant is entitled to make the Application are as follows: Applicant isthe Assignee of the said lnventor(x4.

4. The basic Application(o- referred to in paragraph 2 of th~s Declaration was/were the first Application{W made in a Convention country iri respect of the invefltion, the subject of the Application. DECLARED at .kyo,Ja.pa. e~raTy19 82. AIKO- CO., LTD. prsonal Signature Declaqtnt no seal, itness or !agallsatlon). (Sige~sture of Declarant) TMasaru TAICASHIMA,, Pres ident T4 thE -COMMISSIONER OF PATENTS.

1Y3iii*hC'F ii i i i

S(12) A1~ALIAN PATENT A1IDMENT (19) M (11) AU-8-48 673/79

-I

(54) STRUCTURAL MATERIAL FOR ACOUSTIC MACHINES (71) AIKOH CO., LTD (21) 48 673/79 525 975 (22) 5.7.79 (24) 20.7.78 (31) 53-87685 (32) 20.7.7 (33) JP (43) 24.1.80 (44) 9.1 (51)2 C04B 43/00 G11B 1/00 C04B 21/06 (72) TOMIO TSUCHIYA (74) SW (56) 13 524/62 270 036 19.2 (57) Claim 1. A structural material for acoustic machines and instruments, which consists of a sintered ceramic body wherein porosity is more than 20% and the diameter of pores is less than 300 microns on an average and at least part of the open pores are impregnated with rubber and/or resin.

ND 46* 3

*11/70/16

525 975 FORM COMONWEALTFI, OF AUSTRALA PATENTS ACT 1952-69

COMPLETE SPECIFICATION 486 7 39 FOR OFFICE USE: Class Int. Class

Lodged:

SCbimplete Specific?'ition Lodged: Accepted: Published: Priority:

Related Art:

4 jqme of Applicant: AIKOH CO., LTD.

Address of Applicant: N~o. 1-39. 2-cliome, Ikenobhata, Taito-ku, Tokyo, Japan

Actual -inventor: Tomia Tsuchiya

Address for Service: Shelston Waters, 1" Clarence Street, Sydney

Complete Specification for the Invention entitled: 1t STRUCTLTRATJ MATERIAL FOR ACOUSTIC MYACHINES AND INSTRUENTS1

The following statement is a -full description tO this invention, including the best iethod of performinig it L Irnown to ne/us-

This invention relates to an iprovment in or relating to a structural material for acou.tic machines and ijatruments. As the materials for turntable, turntable sheet,

stabilizer, speaker enclosure, floor system enclosure,

head shell and tone arm of acoustic machines and

instruments, particularly of record player there were

hitherto employed mainly metals such as aluminium die

casting and press worked steel plate and wood in view

of easy workability, rigidity and appearance to some

extent, and moderate cost, in the hope that said

materials may have a great equivalent mass and a

high rigidity so as to hardly vibrate, and that (2)

they may have a great damping ratio to vibration

thereby attenuating vibration quickly, said two

features and being of properties of making

o acoustic effects good.

-ong said products, however, the metallic

ones have a very small damping ratio to vibration but

2C a high resonance sharpness fh so that they have demerits

in likelihood of resonance to specific frequency.

They are liable to receive the vibration of motor,

the outside vibration transmitted through player

board and the vibration of speaker so as to deteriorate

the signal-to-noise ratio, thereby causing sometimes

howling. Wooden speaker enclosure is resonant even

with specific resonance. To prevent this unfavorable

effect there has been provided means that the upper

or lowar face of a turntable is coated or adhered with

a substance having a great damping ratio of vibration, n such as resin or rubber, or it is stuck together with composite plastics. However, in the former case it is impossible to completely control the properties innate to the metallic body because the resin or rubber is a complement to the metallic body. To answer the purpose, therefore, the resin or rubber must be greater in mass than the metallic body whereby the rigidity of metal can no longer be effectively used. In the latter case the main skeleton is of plastics so that it lacks in rigidity and the turntable causes damping action to swing the disc up and down, while cau6ing a fear of troubling the tracing operation of stylus chip. Further, being light in weight with regard to plastics, its mass is small when the content of filler is less to lack in the inertia mass of said turntable thereby causing wow and flutter as in a turntable of metal plate.

Furthermore, wooden articles have a great damping ratio

but they come short of rigidity.

The object of the invention is to provide materials

for acoustic machines and instruments of the kind described

at the beginning of the specification, said machines and

instruments excluding the conventional demerits and having

good performance.

The turntable according to the invention consists of

a sintered ceramic body wherein porosity is more than

and the diameter of the pores is less than 300 microns on an

average and at least part of the pores of said sintered body

is impregnated with elastic materials such as rubber and/or

resin. Porosity values were measured in accordance with

thb Japanese Industrial Standard, JIS R 2205-1974.

The great rigidity and mass possessed by ceramnic may serve for less sensitivity against vibration of the turn- table and for quickly attenuating the vibration thanks to the pores of ceramic. In the ceramic fit for the material

of the acoustic machines and instruments according to the invention, the greater in rigidity the better. However, the allowable lower limit of the rigidity will be a Knoop hardness of more than 5000 to fall under a range in which the strain by vibration does not badly affect the sound wl0 effects. This means that materials harder than ceramic

or glass can be used. Further, preferably the ratio of the pores which attenu te the damping ratio of vibration as quickly as possible is more than 20% porosity, ar.d the

porosity of less than 20% will have less effect because it cannot sufficiently form pores included between crystal particles of ceramic in order to promptly decrease the vibration added to the ceramic body. Accordingly, the less in the size of pores the wider they disperse so that the pores can be included more between the crystals and particles of ceramic to increase the attenuating properties of inside vibration, but ceramic having an average pore diameter of less than 300 microns can satisfy these requirements and it is effective for increasing the damping ratio of vibration to impregnate the interior of the pores of ceramic having said pores with elastic substances such as rubber and/or resin in place of air. That is, the rubber or resin is active for enclosing the vibration which was subject to the crystals or particles of ceramic to be a rigid body, into the crystals or 4 4- partieleg, theteby attenuating the vibration. The impregnation may not necessarily be carried out over the entire pores, and it may be restricted to the upper face and lower face of the material to be treated or non- uniformly dispersed in its entirety. Advantageously, the turntable which is impregnated with rubber or resin at its upper face will not require a turntable sheet made of rubber.

The invention will now be described more in detail,

by way of examples, with reference to a turntable.

Ceramic material is added with kaolin of more than

and then wet mixed with a small amount of combustible

material and water. The mixture is moulded by pressing

such as under hydraulic pressure, air pressure, oil pressure

or friction, and after drying it is sintered in a sintering

furnace. After cooling the sintered article, its surface

is faced thereby grinding and processing it to a desired

extent of preciseness of dimension and shape. The mixed

combustible materials are effective for forming pores, and

there are used wax, fine powder of wood, starch, wheat

powder .nd the like.

Impregnation of the elastic substances may be carried

out in a liquid state of said substances, such as latex of

natural or artificial rubber besides a carbon disulfide

solution of rubber, an alcohol solution of resin or the

like, by either coating it onto the surface of turntable

or dipping the turntable in it thereafter drying.

Mixing examples and the properties of the sintered

pieces of ceramic produced with said mixing are now

described hereunder.

Alumina (250 p 87% Kaolin 13%

Porosity 32%

Average pore diameter 150 u

Bulk specific gravity 2.47

Hardness 22000 Knoop

Silicon carbide (125i

Kaolin

Porosity 31%

Average pore diameter 45 v

Bulk specific gravity 2.04

Hardness 24000 Knoop

As a mode of working of the invention, a test

listening was carried out by acoustic specialists by

using a disc turntable in which a turntable sheet made

of baked ceramic impregnated with silicon rubber was

adhered onto a conventional curntable made of aluminium

die casting, with an adhesive. As a result, it was proved

that compared with conventional aluminium die casting disc

turntable with rubber sheet, there was scarcely resonance

caused by mechanical vibration, sound effects of high

damping effect were exerted, and acoustic properties thanks

to the rigidity and porosity of ceramic are very

prominent, said properties being a technical idea of the

invention.

6-

i~L1I~~S~I- I I-U~LIUY~r-YlilY 1~C~~I~I~L~C~ir~ULY liulr~r;a~i j

Claims (2)

THE CL4IMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1. A structural material for acoustic machines and

instruments, which consists of a sintered ceramic body

wherein porosity is more than 20% and the diameter of

pores is less than 300 microns on an average and at least

part of the open pores are impregnated with rubber and/or

resin.

2. A composite structural material for acoustic machines

and instruments wherein any structural material of claim 1 1 for is adhered with a conventional struztu 'al -materia

acoustic machines and instruments by means of an adhesive.

DATED -his 27th day of September 1982

AIKOH CO. LTD

Attorney: ROBERT G. SHELSTON Fellow Institute of Patent Attorneys of Australia" of SHELSTON WATERS

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