JP2005-204215,A
`
`Bibhiography
`{19} [PubHeation country/region] JP
`(19) [Rind of official gazette] A
`(1) [Publiestion number] 2005804215
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`{43} [Date of publication of application} 2O050TZA
`(a4) [Title of the mvention] ELECTRO-ACOUSTIC TRANSDUCER
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`(51) [International Patent Classification 7th Edition]
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`HO4R 722 HOSR 7/2 HoO4R 9/02 Hodk 31/00
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`[Fu
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`HOSR 7/22
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`HogR We
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`A
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`HG4R GO2
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`INA
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`HG4R GOG2 OLB
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`Ho4R Gos
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`10gA4
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`HOSR 31/66
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`B
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`{21} [Application maumber] 2004010427
`(29) [Piling date] 20040119
`(71) [Applicant!
`[Name] SDK KK
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`[Nsme! NIPPON TOKUSHU MIKE SEISARUSHO'RE
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`(72) Unventor}
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`[Full name] MATSUMOTO KAZUO
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`[Full name} TAKASHIMA KAORU
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`iTheme code (reference)!
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`spois
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`SDG1G
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`[F-term (reference) |
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`5DOLZBBG1
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`BDO TSBROS
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`SDOLSBROS
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`aDOISAAILS
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`SDOIGKANS
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`isT} (Overview!)
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`PROBLEMTO BE SOLVED: To provide a fiull-band type dynamvp-electric electra-acoustic transducer
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`

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`which can reduce cost, without complicating its structure or the manufacturing steps.
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`SOLUTHON: The electro-meaustic transducer inchides a frame 10, and an Inner marmetic circuit 20 is
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`housed ana recess 21 of the frame 10. An annular elastic member 25 is mounted in an elastic member
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`mounting portion 14 of the frame 10, and an edge portion a1 of an approximately dome-shaped
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`diaphraeni 30-is placed on the elastic meraber 25. An arnular elastic member 06 is plied on the
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`edge portion 31, and the edge portion S1 is held between the elastic members 25, 86. A protective
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`eover 40, which covers the diaphragm 30 and fines the elastic member.26, is mounted ta the frame 10.
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`FO bee
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`APOERH ORL EReR
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`

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`* NOTICE *
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`dPO and INPIT are not responsible for any damapes caused hy the use of this iranslation.
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`1, This document has been translated by computer, So the iranslation may not reflect the original
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`presisely.
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`2 **** shows a ward which cannot be translated.
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`3. in the drawings, any words are not translated.
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`
`[Patent Claims]
`
`[Claim 1
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`Afull hand electrodynamic electroacoustic transducer is provided.
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`A frame in which a pecessed part for housing a magnetic circuit is formed ats center part and an
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`annular elastic nrember mounting part is farmed around the recessed part |
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`A magnetic circuit of an inner magnetic type comprising a magnetic pile, a central pale, a gap
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`between the maonetic pale andthe central pole. anda permanent maenet, andis housed and fixed mm
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`the cancave portion ;
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`Adinphrarcn which has a dome shape and has an edge part on the peripheryof the dame;
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`Aveice coil mounted on the rear surface of the diaphragm and suspended in the gan:
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`An annular elastic member mounted on the elastic member mounting part and holding the edge
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`part ;
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`Aprotective cover attached to the frame and covering the diaphragm and fixing the elastic member }
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`The electroacaustic transducer characterized by preparation ***,
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`[Claim 2]
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`Afull band electrodynamic electroacaustic transducer is provided.
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`A frame m which a recessed part for housing a magnetic circuit is formed at a center part and an
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`annular elastic member mounting part is formed around the reressed part }
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`A magnetic circutt af an inner magnetic type comyprising a magnetic pole, a central pole, a gap
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`between the magnetic pole and the central pale, and a permanent magnet, and is housed and fixed m
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`the concave portion .
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`An annular i elastic rember menmied on the elastic member mounting part }
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`Adiaphragm which has a substantially dome shape and is mounted on the 1 elastic member ;
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`Aveis: coll mounted on the rear surface of the diaphrazm and suspended in the rap:
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`An annular 2 elastic member placed on the edge part and holding the edge part together with the 1
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`elastic mreamber;
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`A protective cover attached to the frarse and covering the diaphragm and fixime the 2 elastic
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`member:
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`The electroacoustic transducer characterized by preparation ***,
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`

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`[Claim 3]
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`An electroacoustic transducer according to claun Lor®?, wherem a detachable concavo-convex portion
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`is formed at an attachment partion ofthe frame and the protective caver.
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`[Claim 4]
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`The electraacoustic transducer according to claim 2, wherein the Land 2 elastic members are cach
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`formed of an elastic O-rme,
`[Gaim 5]
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`An electrazcastic transduter seocording to claim 2, wherein said elastic member mountine portion
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`comprises a concave groove for receiving said 1 elastic member.
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`[Detailed description of the invention!
`[Technical field]
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`fo001]
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`The present imvention relates ta a full-hand electradynamic electroacoustic transducer used in
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`headphones, microphones, and the like.
`[Background of the Invention}
`focog]
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`Conventimally, as a literature relating to a whole band type electradynamic electroacoustic
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`transducer which reproduces a sound over a wide hand ranging fram a low scund range to a high
`sound range fe.g.. a SHz~1G0KHz), for example, there are the following.
`fooe3]
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`[Patent document 1]U.S. Pat. No. 3005436 (FIG. 1).
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`foaos]
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`[Non-patent document 1]“NewVersion Speaker & Enclosure 100" edited by Saiki, Inc., "New Edition
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`Speaker & Enclosure", edited on Nov. 26, 5. p. 27, FIG. 1, FIG. 3, and FIG. 200
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`3
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`fooos]
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`Fic. 1 of Patent Document I and this descriptive text describe a technique of an electrodynamic
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`electroacoustic transducer of all band type. In this electromnwustic transducer, a magnetic circuit of
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`afi inner magnetic type comprisiig a frame m which 2 recessed part for housing a magnetic circuit is
`formed at a center part, a magnetic pole (yoke), a central pole {plate} and a permanent magnet
`imagnet} is housed im the recessed part :If is provided with a diaphragmwhich is adhered ta an outer
`edge of the frame. and a cylindrical voice coil (movable coil) which is mounted on a rear surface of the
`diaphrazm and is suspended im a gap (gap) of the magnetic circuit. A colunmar projection is formed
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`ai the center of the recess in the frame, and the colummar projection is fitted into a through-hale
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`formed im each of the magnetic pole, the central pole, and the permanent magnet, and the magnetic
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`circuit is fined ta the frame.
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`

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`fooos]
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`in this-tape of electroammuistio transducer, since the magnetic cireutt-can be fixed to the frame only by
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`itting the magnetic pole, the central pole, and the respective through holes of the permanant magnet
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`into the colummar projectian, there ia an effect that the assembly of the electroacoustic transducer
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`Peconies easy.
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`[Disclosure of invention!
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`[Problemte be solved by the invention!
`foo]
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`However, the conventional electroacoustic transducer has the following problems.
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`fooos!
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`FHS. 5 is a schematic partial structural viewshowing a loneitudmal section of a diaphragm im the
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`conventional electradynaniec electroacoustic transducer described im FIG. 1 of Patent Document 1
`and FIG. 3 of Non-Patent Document 1. FIG. 6 is a diaeram showing the fremuency response {output
`scund pressure frequency characteristic) of FIG. 4 described in FIG. 1 of Non-Patent Document 1.
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`fo009]
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`In FIG. 5, the diaphragm i has a substantially dome shape, and a cyHnerical voice nail 2 is bonded ta
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`the rear surface of the center portion side with an adhesive. The vaice cail 2 is suspended within 2
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`magnetic pole cap of the magnetic cireuit. An edge portion 1 a of an outer peripheryof the vibration
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`plate 1 is bonded ta an outer edge portion 3 a of the frame with an adhesive.
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`f0016]
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`In such an electroacoustic transducer, for exanmple, when an electric signal of an electric signal is
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`supphed to the voice coil 2, the veice call 2 drives up and down according tae the prmerple of
`electromagnetic action (Fleming's left-hand rule}. This driving force f is expressed by the following
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`equation.
`FSB L.I {dyne).
`: magnetic flux density of a magnetic pole gap (gauss)
`L:; length of voice coil 2 im maenetic field fem).
`IT. audio current (A)
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`ood
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`The driving force f increases or decreases linearly in proportion ta the sound current I. As a result,
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`the vibration plete 1, to which the voice coil 2 is mounted, moves up and dawn m proportion to the
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`change m current, and radiates sound.
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`fooig]
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`As deserthed in Non-Patent Document 1, the frequency response shown in FIG. 6 is obtaimed by
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`automahically measuring the sound pressure level at a point 1m on the reference axis so as ty be a
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`continuous curve corresponding to the frequency. In this frequency response, a frequency range to be
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`reproduced is referred to as an effective frequency hand FB, and 3 low frequency bard reproduction
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`limit Lin which an output sound pressure level is reduced by - 10 dB anda frequency range in which
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`

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`the output sound pressure level.is high are shown within a range of a low frequency resonance
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`frequency. fo indicating a limit afm low frequency band and a hich frequency. band resonance
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`frequency fh. indiwating a Hmit of a high frequency hand. The characteristic is divided inte a flat
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`characteristic of fhe piston vibration range PR and a divided vibration range DB consisting of a
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`comphoated vibration range of the diaphragm 1 2. In the full-band fype, the enhire effective
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`frequency band FB from the low band reproduction Gout L ta the high hand reproduction Hrsit His
`used.
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`foots)
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`The characteristic of the low sound frequency range is substantially dstermined by the valus of the
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`low sound resonance frequency fo and the value of the sharpness Qo of the resonance, and the mutput
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`sound preastre decreases in inverse proportion to the 2 power of the frequency, below the low scund
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`resonance frequencyfo. In the range from the low range te the middle range, because of the pisten
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`vibration range PB, the characteristic becomes substantially flat. In the middle sound range, an
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`influence of an edge portion I a around the diapbragnr] appears, amd vibration cecura in. an opposite
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`phase with respect to the diaphragm 1 due to resonance, and scamfrom the diaphraem 1 andthe
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`edge portion 1 a cancels out, resulting in a dip called a valley D of middle sound. In the high sound
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`range, the vibration plate 1 cannat vibrate, and the vibration plate 1 becoames.a divided whratien
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`range DB imwhich each portion of the vibration plate 1 vibrates miricately, so that many peak dips
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`eccur At a high frequency limit, a high Frequency resonance concurs mamlyat a frequency determined
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`by the stiffness and mass of the central portion of the diaphragm 1 and the mass of the voice onl 2,
`and a peak at this high frequency Hmit frequency (high frequency reproduction Hmit H) finally
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`decreases suddenly.
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`foci]
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`Conventionally, in a relatively large electroacnustic transducer such as a cone type speaker, an area
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`af an edge portion 1 a is reduced, a dumping agent is applied, or a hondimg structure is devised in
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`crder to suppress a valley D of a middie scund as much as possible.
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`fO015]
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`However, in a spill electraacoustic transducer such as a headphone, since a diameter of the
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`diaphragm 1 is small, a smele diaphragm structure is usually enrployed, and in such a single
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`diaphragm structure, when the area of the edge portion 1 a is reduced, the fixing strength hecomes
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`smal and there is a possibility that the diaphragm is peeled from the auter edge portion 3 a of the
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`frame. In order to prevent this, it is diffioult ta secure a necessary vaachining area because the
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`diameter of the vibration plate 1 is small, even if an attempt is made ta apply a dump agent or to
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`devise a bondimg structure or the like. Further, as ancther contrivance, a multicway system using 3
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`diaphragms for low sound, middle sound, and high sound or 2 vibration platesfor low sound, medium
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`scund, medium sound. and high sound is employed, and there is a problem that sound quality is
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`improved by suppressing the valley D of the middle sound as nnach as passible, but the structure and
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`the manufacturing process became complicated and the cost increases.
`foatél
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`itis an object af the present Invention to previde a syaall-sized electraacaustic transducer which can
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`he reducedin cost without complicating the struchiure and manufacturing process.
`[Means for solving the problem!
`foo17]
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`In order te salve the aboveproblem, an all-band clectrodynamic slectraacoustic transducer acommding
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`to the present invention inchides a frame m which & concave portion fir housing a mapmnetic circuit is
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`formed in a central portion and an annular elastic member mounting portion is formed around the
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`concave perio, and an internal magnetic type magnetic circuit. The mapmetic circuit mehides a
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`magnetic pole, a central pole, a gap between the magnetic pole and the central pole, and a permanent
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`magriet, and is hawsed and fixed im a recessed portion of the frame.
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`foais]
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`Further,
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`in the clectroacaustic transducer of the present mivention, a diaphragm having a
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`substantially dame-shaped shape and having an edge portion on the outer permphery of the dome,
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`and a voice coil mounted on the rear surface of the diaphragm amd suspended in the gap, are
`provided. The device inchides an anmular elastic member (or 1 and © elastic members) which is
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`mcunted om the elastic member mounting portion and holds the edge portion, and a protective cuver
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`which is attached to the frame and covers the vibrating plate and fixes the elastic member
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`[Effect of the Invention]
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`fooigl
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`Since the edge part of the diaphragm is pmehed with the elastic member according to Invention
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`concerning Clanns 1, 2, 4 and 5, it mthibits so that the valley of an inside sound may decrease, and
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`the tome quality in an effective frequency band buproves. Further, since the diaphragm has a
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`structure in which the edge portion is sandwiched bythe elastic member, the diaphragm carr be
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`easily attached, thereby facilitating the manufacture af the electroacoustic transducer and rechicing
`the cast.
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`foo2a]
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`According to the 3 aspect of the present invention, since the protective cover and the vibration plate
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`can be fixed only by engaeing the protective cover with the frame by the concave and convex portions
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`for angagement, the manufacture can be made easier and Tower costis obtained.
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`*4gation is attanied.
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`[Best mode for carrying out the invention!
`foazu]
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`In the etifire band type electrodynanic electroacoustic transducer according tothe present mvention,
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`adrame is provided in which a cencave portion for housine «a mernetic circuit isformed ata central
`peation, and aa anmalar clastic member waduntine portion te.2., w obficave oroove) is farmedarid
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`

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`the concave partion. Arsagnetic circuit of an internal magnetic type, which is coniposed of a magnetic
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`pele,.a central pele, a-gap betweenthe magnetic pole and the central pole, and a permanent magnet,
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`is housed and fixed in the concave portion. An annular elastic menther js mounted on the elastic
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`member niounting portion, and an edge partion of the elastic member mountings portion halds an
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`edge portion of an mater periphery of the substantially dame-shaped diaphraem., Theelastic member
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`is constituted by a single clastic menuner ara | and 2 elastic members. The 1 and 2 elastic members
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`are each constituted by, for exanmle, am elashi« O-ring or the hKe.
`Eoozg]
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`Avotce coulis mounted on the back of the diaphragm and is suspended im the gap. A protective cover
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`which covers the chaphragm and fixes the elastic memberis attached to the frame. The attachment
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`portion of each of the frame and the protective cover is provided with a detachable engaging portion.
`[Example 1]
`foazs]
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`(Elements of the Invention)
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`Fig.1 {A} and {B)
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`is a configuration diagram of the all
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`the zone type electrodynamie type
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`electroaonustic transducer m which Example 1 of the present mvention is shawn, and is the plan
`view in which the figure (A) removed drawing of longitudinal section, and the figure (B) removed the
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`protective cover and the diaphragm. FIG. 2 is a plan viewof the diaphragm in FG. 1:.
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`fooz]
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`This full-band electradynanuc electroacoustic transducer is a small electroacoustic transducer used
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`in hearhyhones and the like, and has a frame 10 made of resin or the ike which houses a transducer
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`body. The frame 10 has a circular plane, and a cencave portion 11 having a substantially circular
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`shape im plan viewis formed at the center of the cancave portion 11, and a cylindrical projection 12 is
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`provided at the center of the concave portion 11. The through hele of the projection 12 1s a seund
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`quality adjusting duct. A plurality of vent holes 13 are formed in the outer peripheryof the recessed
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`partion 1], and an annular elastic member mounting portion 4 is provided on the outer peripheryof
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`these vent holes 13. The elastic member mounting portion 14 is formed of a concave grove, and an
`annular outer wall portion 15 is provided on the outer periphery thereof]. An engaging receased
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`portion 16 is formed on an cuter surface side of the outer wall portion 15.
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`foazs]
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`Om the outer periphery of the concave portion 11 at the bottom surface side of the frame 10, another
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`concave portion LY is formed corresponding to the vent hole forming region. A phurahtyof vent holes
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`17 pass through the bottemof the concave portion 17, and a sound absorbing material 18 such as a
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`nonwoven fabric is adhered to the concave partion 13. A terminal 19 which is an electric terminal is
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`provided at a part of an outer periphery of the recess 11. The concave portion 11, the prmectien
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`partion 12, the vent hole 13, the elastic member miountine portion 14, the outer wall portion 15, the
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`angaeguig concave portion 16, and the cancave partion 17 of the frame 10 are mtegrally formed by
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`insert molding using resin, for example.
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`

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`foo26]
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`An inner magnetic maemetic circuit 2)is fitted inte the recess 1] of the frame 15. The magmetic
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`circuit 20 inchides a planar circular cap shaped magnetic pole 2] having a through hole 21 a formed
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`iis center. a disk-shaped permanent magnet 22 having a through-hele 22 a farmed in its canter, a
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`disk-shaped center pole 23 havine a.through-hole 23.aformed in its center. anda gap 24 hetween the
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`magnetic pale 21 and the center pole 23. In the cap type magnetic pole 21, a through hole 21 ais
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`fitted ta an outer periphery af the projection 12aman inverted state. The permanent magnet 25 is
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`micunted on the magnetic pole 21 in a state in which the throueh-hole 22 ais fitted inte the prijection
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`12. The center pole 23 is placed on the permanent magnet 22 in a state in which the through hole 23
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`# is fitted inte the projection 12. The top of the projection 1D is cmulked by ultrasonic welding or the
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`hike, and the center pole 23 is fixed by the caulking portion. A sap 24 1s formed between an outer
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`peripheral surface of the cenfer pole 23 and an inner peripheral surface of the magnetic pole 21.
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`foaz7]
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`Al elastic member (e.¢.. a O ring having an elastic section such as silicone rubber} 25 is inserted inte
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`the annular elastic member mounting portion 14. On an O-ring 25, an edge portion Si of an outer
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`edge of a substantially dome-shaped diaphragm 30 is placed, and an edge partion Si thereof is
`sandwiched by a 2 elastic member (ee, a 0 rine having an elastic section such as silicone rubber} 26
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`placed on the edge portion 31 and an O-rmg 25 thereof.
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`fo028]
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`The substantially dome-shaped diaphragm 30 has a sinele diaphragmstructure formed of a plastic
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`film or the hike, and has a circular plane, and the diameter of the flat edge portion Si of this outer
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`edge is substantially the same as the diameter of the annular elastic member mauntime portion 14.
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`An annular flat coi fixme portion 32 is formed at a gap corresponding portion of the vibration plate
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`30, and an inner side of the coil fixing partion 32 bulges mtc an are shape in cross section and cavers
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`the center pole 23. Between the coil fixine portion 32 and the edge portion 31, there is formed a
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`corrugation 35. The corrugation 55 is formed by radially projecting convex or concave rit-type pleats,
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`and is formed so as te reduce a crest and a valley of a response m a high sound resonance region
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`where the vibration plate 40 vibrates, tc obtain a frequency characteristic as flat as possible, and to
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`impart strength to the diaphraem 30.
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`fo029]
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`Acylindrical voice coll 34 is adhered to the rear surface of the onl fixing portion 32, amd this voice onl
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`34 is suspended in the gap 24. Acap shaped protective cover 4) having a circular plane is mounted on
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`an outer wall portion 15 of the frame 16 so as to cover the diaphragm 30. The protective cover 40 has
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`a finction such as a baffle plate which prevents the air pressure accompanying the vibration of the
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`vibration plate 30 from being sneaked and prevents a decrease im the sound pressure, and has a
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`fimetion of fixing the O-ring 26 and is formed of a ream or the like. An outer wall portion 41 which is
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`fitted te an outer wall portion 15 of the frame 16 side is erected on the outer edge of the protective
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`

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`cover 40, and an ehgagitig conves portion 42 which is detachably fitted into an engaging concave
`portion 16 ofthe frame 10 side is projecting!y previded onan anter surface. af the outer wall portion
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`41. A plurality of sound emitting holes 45 are formed on an upper surface of the protective cover 40.
`[0036]
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`‘Preparation Method Example)
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`FIGS. 3 a te 5 ¢ are manufacturing process diagrams showing an example of a manufacturing
`method of the electroacoustic transducer of FHG. 1.
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`loos)
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`The electroacoustic tranaducer of FIG. 1 is manufactured by, for example, the following steps (1) ta
`i}.
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`foo32]
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`(1) A process of FIG. 3 a;
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`Athrough hole 21 a of a magnetic pele 21, a through hole 22 a of a permanent magnet 22, and a
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`through hole 23 a of a center pole 23 are sequentially Fitted inte a projection 13 of a frame 10, anda
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`magnetic circuit 20 is formed by slacking the magnetic pole 21, the permanent magnet 22 and the
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`center pole 23. Then, when the top portion of the projection 12 is crimped by ultrascmic welding or
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`the ke, the magnetic cirewit 20 is fixed m the recess 11 of the frame 10, and a gap 24 having a
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`constant interval is formed between the masmetic pole 21 and the center pole 25.
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`[dos]
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`(2) The proceas of Fig.3 (B)
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`An O-ring 25 is inserted into an elastic member mounting part 14 of a frame 10. A voice coil 34 is
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`previcusiy adhered on the back surface of a coil fixing part 22 of a diaphragm 30, and an edge part 31
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`of a diaphragm 30 is placed an an O-ring 25 while the voice cail 34 is inserted inte a gap 24.
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`foasa]
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`ia) A process af FIG. 3c;
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`Aving 26 is placed on an edge part 31 of a diaphragm 30 surrounded by an auter wall part 15 ofa
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`frame 10. Next, when the outer wall portion 41 of the protective cover 40 side is placed on the outer
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`surface of the outer wall portion 15 of the frame 10 side and the protective caver 40) is pressed, the
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`engaging convex portion 42 of the outer wall portion 15 side is fitted mite the engaging concave
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`portion 16 af the outer wall portion 41 side. As a result, the pratective cover 4) is mounted om the
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`frame 1G, and the Crring 26 is fixed in a state of being slhehtly pressed hy the miner peripheral edge
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`of the protective cover 4).
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`Thereafter, when the saamd ahserhing material 18 is bended to the recess 17 on the battom sude of
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`the frame 16, and the lead of the voice cml 34 is soldered to the termimal 19. the manufachirimne of the
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`electroacoustic transducer shawn in FIG. 1 is completed.
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`[0035]
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`When, for example, a headphone is manufactured using such an electroacoustic transducer a desires
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`

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`headphone can be manufactured hy fixing an electroacoustic transducer in a headphone case thot
`shown) smd allaching an ear ped (ear pad) ip sax opening ofthe headphone ease.
`o0g5)poi
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`(Operation)
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`For example. when. ® voice current is supplied tothe terminal 19, this voice current flaws inte the
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`yeige coll 34. Then, asmice the voice coll 34 vibrates up and down acearding to an electromagnetic
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`action, the vibration plate Ht} moves up and down im propertion te a change m current to radiate a
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`gourd. This sound is radiated frony the sound enntting hele 43 of the protective cover 40 to the
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`outside.
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`[0037]
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`In the all-band electroacoustic transducer according to Embodiment 1, since the entire area of the
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`effective frequency band FB shown in FIG. 6 is used, since the vibration system vibrates almost
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`integrally with the middie sound range, the frequency characteristic becomes substantially flat. In a
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`conventional electroacoustic transducer, an influence of an edge portion arcund a diaphragm appears
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`in a middie sound range, vibration cecurs in a phase opposite fa that of a diaphragm due fo
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`resonance, noise from a diaphragm and an edge portion cancels, and a dip called a valley D of middle
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`sound is generated. In this embodiment 1, however, the edge portion 31 of the diaphragm 30 is
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`pinched from above and below by the O-ring 25,26 having 2 circular cross section havime an elastic
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`force. The contact ara of the edge part 31 and the O-ring 25,26 (1 «., the areaof the support point of
`the edge part 31} is small, and the left and right of the edge part 31 are not easily swung up and
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`down around the support pomt, and the edge part 30 vibrates in the same phase m conpinction with
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`vibration of the vibration plate 30. Therefore, vibration in the oppasite phase of the adge partion 31
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`due to resonance is suppressed, and the valley D of the middle sound is suppressed to be smal. At
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`this time, ois sufficient te set the elastic force of the O-ring 24,26 to a desired vahie in advance hy
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`expernnents or the hke so as to maximize the suppression effect.
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`[0038]
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`In the high scnmmd range, the vibration plate 30 becomes unable to perform the piston movement, and
`
`the vibration plate 30 tends to became a divided vibration range DB in which each partion of the
`
`vilmation plate 1 vibrates, but since the corrugation 33 1s formed, the crest and the valley of the
`
`response in the high sound resonance range im which the vibration is divided and vibrated are
`
`relaxed, so that a flatter frequency characteristic can be cbtaimed. At this time, m order ta obtain a
`
`more flat frequency characteristic, i is only necessary to set a predetermined value of the position,
`
`the size, the number, or the ke, of the projections 33 in advance by experiments or the hke.
`
`60380]
`
`{Effect ete}
`
`In Embodiment1, there are effects such as the following (BD to (HT).
`fo040)
`
`{I} Since the edge portion 31 of the vilmation plate 30 is held from above and belowby the 2 G-rines
`
`

`

`25,26, the valley D of the middle sound is reduced. Moreover, since the vibration 33 is formed on the
`
`diaphragm 30, the frequency characteristic in the hich sound range is flattened. Thus, the overall
`
`acund quality in the effective frequency band FR is remarkably improved.
`foo4u]
`
`dh Since the magnetic cireuit 20 is assembled by fitting the magnetic pole 21. the permanent
`
`magnet 22, and the central pole 23 to the prajection 12, the magnetic circuit 20 can be easily
`
`assembled. Further, since the diaphragm 30 has a struchure in which the edge porticom Si as
`
`sandwiched from above and below by 2 O-rings 25,26, the diaphragm 30 can be casily meoimted. Thus,
`
`itis possible to easily manufacture the electroacoustic transducer and to reduce cast.
`
`foo4g]
`
`UID The engaging projection 42 on the side of the protective cover 40 is fitted inte the engaging
`recess 16 on the side of the frame 10.
`
`Asa result, the protective cover 40 and the vihration plate 30 can be fixed, sa that the mamiufacturing
`
`pracess becomes easier and lower cost. In addition, an engaging convex portion may be provided on
`
`the frame 10 side, and an eneagme concave portion may be formed on the protective cover 40side.
`[Example 2]
`foo4s]
`
`FIGS. 4 (4} to (C} are cross-sectional views showing ancther configuration exaniple of an elastic
`
`member which holds an edge partion 31, showme a 2 embodiment of the present mvention.
`
`foo44]
`
`In FIG. 4 a, an annular elastic member 25 A, 26 A havme a substantially semicircular crass sectiem
`
`holds the edge partion 31. In FIG. 4b, an annular elastic member 25 B, 36 B having a triangular
`
`crass section holds the edee portion 31. The elastic member 25A,2GA25526B is formed of an elastic
`
`material such as slicane rubber, and even when such an elastic member 25426435B36GB is used.
`
`substantially the same action and effect as in Embodiment 1 can be chtamed. In addition, the croas
`
`section of the elastic member 254,264,258.268 may be chanzed to another shape such as a square.
`
`[0045]
`
`In FIG. 4 « an annular elastic member 25 C having a substantially U-shaped cross sectinn is
`
`provided, and an annular projection 25 €
`
`or a plurality of projectimms 26 €
`
`arranged at a
`
`predetermined miterval is formed on the upper and lower sides of the elastic member 26 €. Fhe
`
`elastic member 26 C and the projection 26 C are formed of an elastic material such as silicans rubber,
`
`for example. Then, the edge portion 31 mserted into the immer side of the clastic member 25 Cis
`
`pressed and held hy the upper and lower projections 26 C. Even when such an elastic member 25 Cis
`
`used, substantially the same efferts and effects as in Embodiment 1 oan be obtamed. Note that,
`
`instead of providing the projection 26 (, the edge portion S31 may be sandwiched by the upper and
`
`lower sides of the elastic member 25 (.
`
`fop46]
`
`

`

`In this way, in order to change the suppression ferce according to the size of the valley D of the
`
`middlesound, the elashx« memberthat holds the adge partion 31 can be deformed inte various shapes
`
`aul structures.
`
`[Example 3]
`i0047]
`
`The present Invention is net lnnited ta the above Enibodiments l and 2, and other variations are
`possible. As the 5 embodiment, there is, for example, the followime (1) and {i}.
`focs]
`
`iI) Although the elastic member mounting portion 14 of FIG. 1 is formed of a groove having a concave
`
`crass section, other confleurstions may be used. For example, the elastic member mounting portion
`
`14 has a flat shape, and the outer wall portion 15 of the outer edge is made higher than that of FIG. 1.
`
`At this tune, the outer diameter of the O-rmg 25,26 and the elastic member ZRA~25C3GA~26C is
`
`slishtly larger than the mmer diameter of the outer wall portion 15. Thus, due te the elastic force of
`
`the O-rmg 25,26 and the elastic member 25A~25C,2GA~26C,
`
`the Gyring 25.26 and the elastic
`
`member 25A~2hC,26A4~26Care held on the flat elastic member mamting portion 14 im the outer
`
`wall portion 15. Moreover, smee the elastic member mounting partion 14 has a flat shape, this
`
`formation becomes easy.
`
`foaa9]
`
`ii} The frame 10, the magnetic circuit 20, the diaphragm 30, the protective cover 40. and the Hke
`
`may be changed to other shapes, structures, and the hike than those shown mi the drawing.
`Undustrial applicability!
`[0050]
`
`The electroacnustic transducer of the present mvention can be used for various types of headphanes,
`
`such as headphones and microphones.
`[Brief Deseription of the Drawings!
`F005 1]
`
`[Fie. LIFEG. 1 is a configuration diagramof a full-band electrodynamic electreacoustic transducer
`
`according to a first embodiment of the present mveantion 5.
`
`[Fig. ZHFIG. 5 is a plan viewof a diaphragmin FIG. 1:
`[Fie. SIFIG. 4is a manufacturing process diagram showing an example of a manufacturing method of
`the electroaroustic transducer of FIG. 1 :.
`
`[Fie. 4IFEG. 16 is a cross-sectional view showing another configuration example of anelastic member
`
`showing Embodunent 3 of the present invention:.
`[Fig. SIFIG. 1 is a schematic partial configuration diagram showing « diaphrasamnof a conventional
`
`alectrodynanie electroacoustic transducer5.
`[Fie. GIFIG. 4 is a diagram showing a frequency response {output sound pressure frequency
`characteristic} of FIG. 53.
`
`

`

`[Explanation of lettars or mimerals]
`foas2]
`
`18
`
`li
`
`Frame
`
`Concave Part
`
`idelastic member mounting portion
`
`t&.41
`
`cuter wall part
`
`16 engaring recess
`
`26 Magnetic Cireunt
`
`21 Magnetic Pole
`
`22
`
`©6Permanent Maonet
`
`25 Central Pale
`
`24 Gap
`
`30 diaphragm
`
`31 Hage Part
`
`34=Voice Cou
`
`40
`
`Protective Cover
`
`42 engaging projection
`
`

`

`EP 2005-2042 75. A 2008. 7-28
`
`(19) ERRERGMF (IP)
`
`Gag Bo BF 4S HRCA)
`
`(LIRRaSBs
`$3RB2005~-204215
`(P2005-204215A)
`(43) RIE SERSI7SE7A28E] (2006,7. 28)
`
`1) Ent. Ch.
`HO4R 7/22
`HO4R 712
`HO4R 9/02
`HO4R 31/00
`
`FR
`
`TovafF BR
`5DO12
`5BDO1LS6
`
`HOAR 7/22
`A
`HO4AR 72
`TOTA
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`9/02
`TOIB
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`9/02
`102A
`HO4R 9/02
`
`BERK HK GRIMS OL i@il BR) FRR
`
`(21) EBRE
`
`(22) HERA
`
`$$ B2004-1 0427 (P2004- 10427)
`
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