EP0289264A1 - Elektromagnetischer Schallerzeuger - Google Patents

Elektromagnetischer Schallerzeuger Download PDF

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Publication number
EP0289264A1
EP0289264A1 EP88303750A EP88303750A EP0289264A1 EP 0289264 A1 EP0289264 A1 EP 0289264A1 EP 88303750 A EP88303750 A EP 88303750A EP 88303750 A EP88303750 A EP 88303750A EP 0289264 A1 EP0289264 A1 EP 0289264A1
Authority
EP
European Patent Office
Prior art keywords
casing
sounding device
base
pole
diaphragm
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP88303750A
Other languages
English (en)
French (fr)
Other versions
EP0289264B1 (de
Inventor
Saburo Kaido
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Publication of EP0289264A1 publication Critical patent/EP0289264A1/de
Application granted granted Critical
Publication of EP0289264B1 publication Critical patent/EP0289264B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R13/00—Transducers having an acoustic diaphragm of magnetisable material directly co-acting with electromagnet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/04—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism
    • B06B1/045—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism using vibrating magnet, armature or coil system
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K9/00—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers
    • G10K9/12—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated
    • G10K9/13—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated using electromagnetic driving means

Definitions

  • the present invention relates to a miniature electromagnetic sounding device applicable to, for example, a portable radio receiver for a radio paging system.
  • a paging receiver which is a typical example of portable radio apparatuses known in the art receives a signal of a predetermined format from a central station. If the signal received is identical with a code which is assigned to the paging receiver, the receiver produces sound to alert the user to the reception of a call. Since this kind of receiver is usually carried in the user's breast pocket or the like, its overall configuration should preferably be as miniature as a cigarette lighter or the like. Therefore, a sounding device installed in such a portable receiver has to be designed extremely small size.
  • an electromagnetic sounding device which comprises a magnetic force generator for generating a magnetic force, a vibrator which vibrates caused by the magnetic force, a support for supporting the magnetic force generator and the vibrator, and a casing which encloses the support and has an opening which is formed through a circumferential wall of the casing for radiating an acoustic output.
  • an electromagnetic sounding device which comprises a base constituting a base magnetic pole, a center magnetic pole provided in a central part of the base, a coil surrounding the center pole, a permanent magnet surrounding the coil, a support frame member located in a circumferential edge portion of the base pole and provided with a knife edge portion at the upper end of the support frame member, a diaphragm laid on and magnetically retained on the knife edge portion of the support frame member and having a magnetic plate which is rigidly mounted in a central part of the diaphragm, and a casing enclosing the support frame member and having an opening which is formed through a circumferential wall of the casing for radiating an acoustic output.
  • the prior art sounding device 10 includes a magnetic force generating section which is made up of a base 12 having a center pole 14, and an annular coil 16 and a permanent magnet 18 which are concentrically arranged around the center pole 14.
  • the sounding device 10 also includes a vibrating section defined above the magnetic force generating section and made up of a movable iron piece type vibrator 20 and a support frame 22 which supports the vibrator 20.
  • the vibrator 20 is caused to vibrate by a static magnetic force which is exerted by the permanent magnet 18.
  • the vibrator 20 is constituted by a flexible diaphragm 20a and a magnetic disk 20b fixed to the diaphragm 20a by spot welding.
  • a film 24 made of synthetic resin is disposed above the vibrator 20 and supported by the rim of a frame 22.
  • a first presser member 26 is located above the film 24 and also supported by the rim of the frame 22, the member 26 being notched to have windows 26a.
  • a second presser member 28 Disposed above the first presser member 26 is a second presser member 28 which is provided with openings 28a. All the structural elements mentioned so far are accommodated in a casing 30 which is formed with a window 30a.
  • a terminal plate 32 constitutes the bottom of the casing 30. Leads for feeding signal voltage to the coil 16 are connected to the terminal plate 32.
  • Fig. 2A shows a sound pressure characteristic particular to the prior art sounding device 10 as actually measured when the input signal supplied was a rectangular wave of 1.4 ⁇ and the distance from a microphone was 10 centimeters.
  • the ordinate and the abscissa indicate respectively the acoustic output P0 (dB) and the resonance frequency f0 (kHz) of the diaphragm 20a.
  • the prior art sounding device 10 use the two presser members 26 and 28 in addition to the magnetic force generating section and vibrating section.
  • the casing 30 has to be provided with a substantial thickness, or height, H although its width L is not questionable. This obstructs the miniaturization of the device 10.
  • a magnetic sounding device actually marketed with the above-described structure has a height H of 6 millimeters and a width L of 10 millimeters.
  • an electromagnetic sounding device in accordance with the present invention is shown and generally designated by the reference numeral 40.
  • the device 40 includes a base 42 which serves as a base pole.
  • a cylindrical center pole 44 is studded on a central part of the base 42.
  • An annular coil 46 is fit over the center pole 44 while a permanent ring magnet 48 is located to surround the annular coil 46.
  • the upper ends of the center pole 44 and ring magnet 48 are substantially coplanar with each other.
  • the base pole 42, center pole 44, coil 46, and ring magnet 48 constitute a magnetic force generating section.
  • a support frame 50 is composed of synthetic resin or like material and disposed at the circumferential edge portion of the base pole 42.
  • the upper end of the support frame 50 is provided with an annular knife edge configuration as indicated by 50a.
  • a thin flexible diaphragm 52 is supported on the knife edge 50a of the support frame 50.
  • a magnetic disk 54 is coaxially positioned on the upper surface of the diaphragm 52 and fixed at its central portion 56 to the latter by spot welding, whereby the diaphragm 52 is provided with permeability.
  • the diaphragm 52 and magnetic disk 54 in combination constitute a vibrating section.
  • the edge portion of the diaphragm 52 rests on and is magnetically retained on the knife edge 50a of the support frame 50 by the acctraction of the magnetic force generating section, while being regulated in deformation by that force.
  • a narrow air gap magnetic field 58 Defined between the underside of the diaphragm 52 and the coplanar upper ends of the center pole 44 and ring magnet 48 is a narrow air gap magnetic field 58.
  • a DC magnetic flux 0 ⁇ m created by the ring magnet 48 extends throughout the base pole 42 and center pole 44, as represented by a dash-and-dot line in Fig. 3. In this condition, the edge portion of the diaphragm 52 is retained on and pressed against the knife edge 50a.
  • a casing 60 made of synthetic resin or the like is engaged with and covers the support frame 50 while defining a narrow air gap 62 between its inner surface and the upper surface of the diaphragm 52. As shown in Figs.
  • a plurality of (usually four or so) short lugs 64 and a plurality of shoulders 66 each being contiguous with a respective one of the lugs 64 are provided on the inner surface of the casing 60 and arranged at equally spaced locations along the circumference of the the casing 60.
  • each lug 64 extends downward slightly beyond the general plane of the diaphragm 52 as viewed in Fig. 3.
  • An air gap 66a is defined between the lugs 64 and the periphery of the diaphragm 52 while an air gap 66b is defined between the lugs 64 and the circumferential wall of the casing 60, the air gaps 66a and 66b serving to minimize obstruction to the propagation of sound.
  • each shoulder 66 extends radially inwardly beyond the edge of the diaphragm 52 and is dimensioned short enough to define an adequate air gap 66c in cooperation with the diaphragm 52.
  • the shoulders 66 and the diaphragm 52 usually remain spaced from each other.
  • a rectangular elongate window 68 is formed through the circumferential wall of the casing 60 so that an acoustic output P0 may be propagated therethrough to the outside.
  • a piece of cloth 70 is attached to the casing 60 to cover the window 68, preventing dust and other impurities from entering the casing 60.
  • a terminal plate 74 is located on the bottom of the base 42 and frame 50.
  • Fig. 6 is an exploded perspective view of the sounding device as mentioned above.
  • signal voltage e is applied to the annular coil 46 to cause current i to flow, as shown in Fig. 3.
  • the DC magnetic flux ⁇ m from the ring magnet 48 (indicated by a dash-and-dot line in Fig. 3) and the magnetic flux ⁇ s which is developed by the voltage e (indicated by a dashed line in Fig. 3) are superposed to generate a vibromotive force in the diaphragm 52.
  • the diaphragm 52 vibrates to develop a sound pressure P1 in the air gap 62.
  • This sound pressure P1 is propagated radially into a space 72 which is defined around the diaphragm 52.
  • the sound pressure P1 is guided along the periphery of the diaphragm 52 to the window 68 of the casing 60, as indicated by arrows in Fig. 4. Consequently, an acoustic output P0 is intensely radiated to the outside via the window 68.
  • the device 40 has the window 68 which is formed through the circumferential wall of the casing 60.
  • the device 40 therefore can be provided with a miniature and thin configuration.
  • the width l of the device 40 is substantially the same as the width L of the prior art device 10, i.e., 10 centimeters
  • the thickness or height h of the device 40 is as small as 2 millimeters which is one-third of the thickness H of 6 millimeters of the device 10.
  • the sound pressure P1 developed in the air gap 62 is readily propagated to the window 68 by way of the circumferential space 72 as indicated by arrows in Fig. 4, the propagation loss of sound pressure P1 in the path defined within the casing 60 is small enough to allow the acoustic output P0 to be intensely radiated to the outside.
  • Fig. 2B shows a curve representative of a sound pressure characteristic of the device 40 which was measured under the same conditions as the prior art device 10. As shown, the device 10 achieves an acoustic output which is comparable with that of the prior art device 10, despite the miniature and thin configuration. Specifically, the acoustic output P0 attainable with the device 10 is higher than 80 dB or, rather, close to 90 dB.
  • the device 40 When an impact whose magnitude is greater than 5G is applied to the device 40 such as when it is let fall, lateral displacement and vertical displacement of the diaphragm are effectively eliminated by the lugs 64 and the shoulders 66, respectively. Hence, the device 40 is operable with stability overcoming such a magnitude of impact. It is to be noted that the lugs 66 are omissible if the air gap 62 is relatively narrow.
  • the present invention provides an electromagnetic sounding device which is miniature, thin, and operable efficiently and stably even when a substantial magnitude of impact is applied thereto from the outside.
EP88303750A 1987-05-01 1988-04-26 Elektromagnetischer Schallerzeuger Expired - Lifetime EP0289264B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP1987066944U JPH0452797Y2 (de) 1987-05-01 1987-05-01
JP66944/87 1987-05-01

Publications (2)

Publication Number Publication Date
EP0289264A1 true EP0289264A1 (de) 1988-11-02
EP0289264B1 EP0289264B1 (de) 1992-06-17

Family

ID=13330627

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88303750A Expired - Lifetime EP0289264B1 (de) 1987-05-01 1988-04-26 Elektromagnetischer Schallerzeuger

Country Status (3)

Country Link
EP (1) EP0289264B1 (de)
JP (1) JPH0452797Y2 (de)
KR (1) KR910007845B1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0497568A2 (de) * 1991-02-01 1992-08-05 Star Micronics Co., Ltd. Dünner Summer
EP0623913A2 (de) * 1993-05-04 1994-11-09 Star Micronics Co., Ltd. Elektroakustischer Wandler
CN112634849A (zh) * 2020-12-17 2021-04-09 新沂市承翔电子有限公司 一种新型防灰防水的电子蜂鸣器

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05209964A (ja) * 1992-01-30 1993-08-20 Shimadzu Corp エミッションｃｔ装置
JP2001125576A (ja) * 1999-10-22 2001-05-11 Citizen Electronics Co Ltd 発音体および発音体を搭載した電子機器
KR20030021288A (ko) * 2001-09-05 2003-03-15 혜성산업주식회사 단말기용 수신 유니트
KR20020024186A (ko) * 2002-01-31 2002-03-29 황상문 이동통신 단말기용 수신유니트

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2402288A1 (de) * 1974-01-18 1975-07-24 Fichter Kg Elektronisch gesteuerter summer, insbesondere fuer weckeruhren
US4251807A (en) * 1979-03-08 1981-02-17 Pickering & Company Miniature buzzer
US4413253A (en) * 1981-02-19 1983-11-01 Alan Hofer Miniature sounder with double tuned cavity

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55116399U (de) * 1979-02-13 1980-08-16
JPS56111893A (en) * 1980-02-12 1981-09-03 Seiko Instr & Electronics Vibration plate for electromagnetic buzzar
JPS55138698U (de) * 1980-03-26 1980-10-02
JPS59131797U (ja) * 1983-02-22 1984-09-04 株式会社三協精機製作所 電磁発音装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2402288A1 (de) * 1974-01-18 1975-07-24 Fichter Kg Elektronisch gesteuerter summer, insbesondere fuer weckeruhren
US4251807A (en) * 1979-03-08 1981-02-17 Pickering & Company Miniature buzzer
US4413253A (en) * 1981-02-19 1983-11-01 Alan Hofer Miniature sounder with double tuned cavity

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0497568A2 (de) * 1991-02-01 1992-08-05 Star Micronics Co., Ltd. Dünner Summer
EP0497568A3 (en) * 1991-02-01 1992-12-23 Star Micronics Co., Ltd. Thin buzzer
US5287084A (en) * 1991-02-01 1994-02-15 Star Micronics Co., Ltd. Thin buzzer
EP0623913A2 (de) * 1993-05-04 1994-11-09 Star Micronics Co., Ltd. Elektroakustischer Wandler
EP0623913A3 (de) * 1993-05-04 1995-11-02 Star Mfg Co Elektroakustischer Wandler.
US5467323A (en) * 1993-05-04 1995-11-14 Star Micronics Co., Ltd. Electroacoustic transducer
CN112634849A (zh) * 2020-12-17 2021-04-09 新沂市承翔电子有限公司 一种新型防灰防水的电子蜂鸣器
CN112634849B (zh) * 2020-12-17 2022-01-21 新沂市承翔电子有限公司 一种新型防灰防水的电子蜂鸣器

Also Published As

Publication number Publication date
KR880014833A (ko) 1988-12-24
EP0289264B1 (de) 1992-06-17
JPS63173293U (de) 1988-11-10
JPH0452797Y2 (de) 1992-12-11
KR910007845B1 (en) 1991-10-02

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