EP0083045A2 - Système magnétique à entrefer annulaire, en particulier pour haut-parleurs de basses fréquences - Google Patents

Système magnétique à entrefer annulaire, en particulier pour haut-parleurs de basses fréquences Download PDF

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Publication number
EP0083045A2
EP0083045A2 EP82111770A EP82111770A EP0083045A2 EP 0083045 A2 EP0083045 A2 EP 0083045A2 EP 82111770 A EP82111770 A EP 82111770A EP 82111770 A EP82111770 A EP 82111770A EP 0083045 A2 EP0083045 A2 EP 0083045A2
Authority
EP
European Patent Office
Prior art keywords
air gap
pole plate
working air
gap
brake air
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
EP82111770A
Other languages
German (de)
English (en)
Other versions
EP0083045B1 (fr
EP0083045A3 (en
Inventor
Eckehard Kort
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.)
Individual
Original Assignee
Individual
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
Priority claimed from DE19813151530 external-priority patent/DE3151530A1/de
Application filed by Individual filed Critical Individual
Publication of EP0083045A2 publication Critical patent/EP0083045A2/fr
Publication of EP0083045A3 publication Critical patent/EP0083045A3/de
Application granted granted Critical
Publication of EP0083045B1 publication Critical patent/EP0083045B1/fr
Expired 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
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/02—Details
    • H04R9/025—Magnetic circuit
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2209/00—Details of transducers of the moving-coil, moving-strip, or moving-wire type covered by H04R9/00 but not provided for in any of its subgroups
    • H04R2209/022—Aspects regarding the stray flux internal or external to the magnetic circuit, e.g. shielding, shape of magnetic circuit, flux compensation coils

Definitions

  • the invention relates to an annular gap magnet system, in particular for woofers, in which a voice coil with a large stroke moves in the working air gap, with a cylindrical pole core made of soft iron and an annular permanent magnet which is at a distance from the pole core between an upper pole plate delimiting the working air gap and a lower pole plate is arranged as well as woofers with such an annular gap magnet system.
  • the invention has for its object to provide an annular gap magnet system or a loudspeaker of the type mentioned in such a way that even with an extremely soft suspension of the membrane and the voice coil, even if the loudspeaker is overdriven, the voice coil on the lower pole plate is avoided with certainty .
  • This object is achieved in that in / on the lower pole plate at a distance from the upper pole plate, which corresponds at least to the thickness of the upper pole plate, a brake air gap surrounding the pole core in its lower region in an axial extension of the working air gap is provided, and in that In the area of the lower end of the brake air gap in the lower pole plate, a magnetic resistance of such a size is provided that the magnetic flux through the brake air gap and the leakage flux above the brake air gap are directed both to the magnetic flux in the working air gap and vice versa to the leakage flow below the working air gap are, in their sum, are at least equal to the opposite directional leakage flow below the working air gap.
  • the magnetic resistance can be caused by a cross-sectional reduction in the lower pole plate.
  • a connecting element with low magnetic conductivity can also be provided between the lower pole plate and the pole core.
  • a soft iron ring can be provided adjacent to the lower pole plate, which limits the outside brake air gap over at least part of the axial length and is magnetically conductive with the inner circumference of the permanent magnet ring in connection stands.
  • the depth and the distance of the brake air gap from the upper pole plate can then be varied by inserting soft iron rings of different heights.
  • the brake air gap can also be limited over part of its axial length by the ring-shaped permanent magnet, whereby the ring-shaped permanent magnet is expediently constructed from two permanent magnets lying in series, of which the magnet facing away from the working air gap has at least a part of the axial length with its inner circumference forms the outer boundary of the brake air gap.
  • a low-frequency speaker with an annular gap magnet system 1 a conical membrane 2 and a membrane basket 2a is shown schematically.
  • a cylindrical body 4b, on which a voice coil 4a is arranged, is firmly connected to the membrane.
  • a centering membrane 2b is arranged between the lower end of the membrane 2 and the membrane basket 2a.
  • the speaker basket 2a is firmly connected to the magnet system in the usual way.
  • the annular gap magnet system 1 has a cylindrical pole core 5 made of soft iron and an annular permanent magnet 6 with a thickness D, which is fixedly arranged concentrically to the pole core 5 between an annular upper pole plate 7 with a thickness d 2 and a lower pole plate 8.
  • a working air gap 3 is formed between the pole core 5 and the inner circumference of the upper pole plate 7, which is concentric with the pole core and into which the voice coil 4a is immersed.
  • pole core 5 and the lower pole plate 8 are shown in one piece.
  • the pole core 5 and the pole plate 8 are two separate bodies which are firmly connected to one another, for example by screws or rivets. This is symbolized in FIG. 1 by the dashed line 5a.
  • the voice coil 4a is designed such that it moves in the working air gap 3 of the magnet system with a corresponding stroke, for example the large stroke typical for a woofer.
  • the open end 9a of the brake air gap 9 is in all embodiments at a distance d 1 from the underside of the upper pole plate 7, which corresponds at least to the thickness d 2 of the upper pole plate 7, but is preferably greater.
  • the magnetic flux, as it results from the brake air gap 9 and the magnetic resistor 10e, is indicated in dashed lines.
  • the magnetic flux through the lower pole plate 8 to the pole core 5 runs due to the magnetic resistance 10e to a substantial extent 10a through the brake air gap 9 and the magnetic leakage flux 10d over the open end 9a of the brake air gap 9 runs from the edge and the top of the pole plate 8 to Pole core 5.
  • the magnetic flux 10a through the brake air gap and the leakage flux 10d form the brake magnetic flux and are at least equal in sum to the inner leakage flux 10c between the pole core 5 and the upper pole plate 7, which passes below the working air gap 3, preferably they are larger.
  • the voice coil 4a plunges inwards into the magnet system, it finally emerges completely from the field of the working air gap 3 if it is excited accordingly. It is driven further by the magnetic field of the stray flux 10c. The sum of the brake magnetic fluxes 10a and 10d acts in opposition to this drive by the leakage flux 10c. As a result, the voice coil 4a is actively braked, thus preventing it from striking the lower pole plate.
  • annular gap magnet system only the annular gap magnet system is shown, the same reference numerals being used for the same or equivalent parts, as in FIG Fig. 1. In the following, therefore, only those features are described in terms of which the magnet systems differ from the embodiment according to FIG. 1.
  • the lower pole plate 8 has a shoulder 8a on the underside of the center line radially outward of the brake air gap 9 in order to save material or to reduce weight.
  • An embodiment is shown to the right of the center line, in which the lower pole plate is composed of a ring 8b and a plate c.
  • the pole core 5 is fixed in the center on the plate 8c, the thickness of which determines the magnetic resistance.
  • a soft iron ring 12 is arranged on the upper side of the lower pole plate 8, the outer surface of which softly contacts the inner surface 6a of the permanent magnet ring 6, while its inner surface limits the brake air gap over part of its depth.
  • a soft iron ring 12a is provided in the embodiment according to FIG. 3b, but here has such a height that it limits the outside of the brake air gap over the entire depth d 3 with its inner surface.
  • the soft iron ring 12a is embedded in a corresponding recess 13 in the lower pole plate 8.
  • no soft iron bridge is provided between the lower pole plate 8, which is annular here, and the pole core 5.
  • 4 is between the inner surface of the lower Pole plate 8 and the outer surface of the pole core 5 arranged a ring 14 with a limited height, via which the two bodies are interconnected.
  • the ring 14 is made of a non-magnetic material, such as brass, aluminum, plastic or the like. 5, a similar effect is achieved in that the annular lower pole plate 8 and the pole core 5 are fixed on a plate 15 made of a non-magnetic material. Since there is no longer a soft iron bridge, in the embodiments according to FIGS. 4 and 5 the entire magnetic flux passes through the brake air gap.
  • the ring-shaped permanent magnet 6 is composed of two partial magnetic rings 6b and 6c, each with a thickness D 1 or D 2 , which overall corresponds approximately to the thickness D of the permanent magnet 6 according to FIG. 1.
  • the upper partial magnet 6b has an inner diameter which corresponds to the inner diameter of the magnet 6 according to FIG. 1.
  • the lower partial magnet 6c has an inner diameter which corresponds to the outer diameter of the brake air gap 9. It therefore forms with its inner surface 6d the outer surface of the brake air gap 9, which extends with an annular recess 9b into the lower pole plate 8, through which the cross-section reduction is determined, which in turn determines the magnetic resistance.
  • the thickness d 1 of the magnet 6b is selected so that the condition is again met that the distance of the open end 9a of the brake air gap 9 from the underside of the upper pole plate 7 corresponds at least to the height of the working air gap and thus the thickness d 2 of the upper pole plate .
  • the advantage of this embodiment is that, given a predetermined height of the brake air gap, the thickness of the lower pole plate can be kept smaller than in the embodiment 1 or 2. This reduces the weight of the magnet system.
  • FIG. 6 shows the magnetic stray flux to the left of the pole core, which in this embodiment flows essentially radially through the brake air gap 9 with its lower region 10d directed towards the pole core.
  • the magnetic flux density B was measured by means of a Hall probe over the total height d 1 + d 2 + d 3 , the measurement being limited to a total depth of 30 mm, since no usable measurement results could be obtained in the area of the bottom of the brake air gap.
  • the measurement results are shown in the diagram in FIG. 7.
  • the magnetic flux is directed away from the pole core above the abscissa and towards the pole core below the abscissa.
  • the magnetic flux density is essentially constant over the thickness d 2 of the upper pole plate 7, ie over the height of the working air gap 3. about the height d 1 , d. h . between the underside of the upper pole plate 7 and the open end 9a of the brake air gap 9, the density of the magnetic flux resulting from the stray field 10c drops quite steeply.
  • the magnetic flux density is then at point Y, ie at a distance of 9 mm from the lower edge of the upper pole plate 7 to 0. From point Y on, the stray field 10d takes effect.
  • the flux density rises again in the opposite direction of the magnetic flux and reaches its maximum approximately in the area of the open end 9a of the brake air gap 9, the size of which depends on the size of the magnetic resistance in the lower pole plate.
  • the flux density then remains essentially constant over the depth of the brake air gap in the measured area.
  • the flux density is plotted in the diagram in Teslar (T).
  • Annular gap magnet systems of the type described can be used not only in loudspeakers, but generally for electromagnetic drives in which a relatively large undamped stroke is required.
  • a writing element can be connected to the voice coil.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
EP82111770A 1981-12-24 1982-12-18 Système magnétique à entrefer annulaire, en particulier pour haut-parleurs de basses fréquences Expired EP0083045B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3151530 1981-12-24
DE19813151530 DE3151530A1 (de) 1981-12-24 1981-12-24 Ringspaltmagnetsystem, insbesondere fuer tiefton-lautsprecher
DE8226166U 1982-09-17
DE8226166 1982-09-17

Publications (3)

Publication Number Publication Date
EP0083045A2 true EP0083045A2 (fr) 1983-07-06
EP0083045A3 EP0083045A3 (en) 1983-09-28
EP0083045B1 EP0083045B1 (fr) 1985-11-21

Family

ID=25798319

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82111770A Expired EP0083045B1 (fr) 1981-12-24 1982-12-18 Système magnétique à entrefer annulaire, en particulier pour haut-parleurs de basses fréquences

Country Status (3)

Country Link
US (1) US4628154A (fr)
EP (1) EP0083045B1 (fr)
DE (1) DE3267630D1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5321762A (en) * 1991-08-05 1994-06-14 Aura Systems, Inc. Voice coil actuator

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5070530A (en) * 1987-04-01 1991-12-03 Grodinsky Robert M Electroacoustic transducers with increased magnetic stability for distortion reduction
US5142260A (en) * 1991-03-08 1992-08-25 Harman International Industries, Incorporated Transducer motor assembly
AU672953B2 (en) * 1991-08-05 1996-10-24 Speaker Acquisition Sub Voice coil actuator
US5390257A (en) * 1992-06-05 1995-02-14 Oslac; Michael J. Light-weight speaker system
US5883967A (en) * 1997-04-15 1999-03-16 Harman International Industries, Incorporated Slotted diaphragm loudspeaker
US6963652B1 (en) 2003-04-18 2005-11-08 James M Colombo Low frequency generator
US20080247582A1 (en) 2004-09-09 2008-10-09 Guenther Godehard A Loudspeaker and Systems
US8189840B2 (en) 2007-05-23 2012-05-29 Soundmatters International, Inc. Loudspeaker and electronic devices incorporating same
CN102378083A (zh) * 2010-08-12 2012-03-14 郭建文 动态阻尼中、低音扬声器
EP2737721A4 (fr) * 2011-07-25 2015-06-03 G Licensing Llc Dr Haut-parleurs ultraplats
DK180111B1 (en) * 2018-10-04 2020-05-06 Upper Level Aps A magnetic system for an electromechanical transducer

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE574429C (de) * 1929-06-25 1933-04-18 Heinrich Eberhard Einrichtung an elektrodynamischen Lautsprechern
GB858250A (en) * 1958-07-01 1961-01-11 Darwins Ltd Improvements in or relating to permanent magnet assemblies
DE1614164A1 (de) * 1967-06-01 1970-06-25 Magnetfab Bonn Gmbh Ringspalt-Magnetsystem
GB1321581A (en) * 1971-01-04 1973-06-27 Rola Celestion Ltd Magnet assemblies for moving coil electroacoustic transducers
DE2211818A1 (de) * 1970-10-01 1973-09-13 Stanley F White Magnetanordnung fuer dynamische lautsprecher
FR2304238A1 (fr) * 1975-03-14 1976-10-08 Licentia Gmbh Haut-parleur electrodynamique
FR2382822A1 (fr) * 1977-03-01 1978-09-29 Seas Fabrikker As Dispositif pour haut-parleur electrodynamique
JPS56146400A (en) * 1980-04-16 1981-11-13 Matsushita Electric Ind Co Ltd Speaker

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL257376A (fr) * 1959-10-29
DE2024258A1 (de) * 1970-05-19 1971-12-02 Neckarelz Mikrofonbau Magnetsystem für elektroakustische Wandler
JPS542647Y2 (fr) * 1971-03-10 1979-02-05
US3803522A (en) * 1973-05-11 1974-04-09 Arnold Eng Co Air gap extending the width of a permanent magnet assembly
JPS5244627A (en) * 1975-10-04 1977-04-07 Sony Corp Magnet core type speaker
SU587645A1 (ru) * 1976-07-21 1978-01-05 Предприятие П/Я А-3150 Магнитна цепь электродинамического громкоговорител
JPS5376824A (en) * 1976-12-20 1978-07-07 Hitachi Ltd Speaker
JPS5546645A (en) * 1978-09-29 1980-04-01 Sony Corp Head phone

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE574429C (de) * 1929-06-25 1933-04-18 Heinrich Eberhard Einrichtung an elektrodynamischen Lautsprechern
GB858250A (en) * 1958-07-01 1961-01-11 Darwins Ltd Improvements in or relating to permanent magnet assemblies
DE1614164A1 (de) * 1967-06-01 1970-06-25 Magnetfab Bonn Gmbh Ringspalt-Magnetsystem
DE2211818A1 (de) * 1970-10-01 1973-09-13 Stanley F White Magnetanordnung fuer dynamische lautsprecher
GB1321581A (en) * 1971-01-04 1973-06-27 Rola Celestion Ltd Magnet assemblies for moving coil electroacoustic transducers
FR2304238A1 (fr) * 1975-03-14 1976-10-08 Licentia Gmbh Haut-parleur electrodynamique
FR2382822A1 (fr) * 1977-03-01 1978-09-29 Seas Fabrikker As Dispositif pour haut-parleur electrodynamique
JPS56146400A (en) * 1980-04-16 1981-11-13 Matsushita Electric Ind Co Ltd Speaker

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENTS ABSTRACTS OF JAPAN, Band 6, Nr. 28, (E-95)[906], 19. Februar 1982 & JP - A - 56 146 400 (MATSUSHITA DENKI SANGYO K.K.) 13.11.1981 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5321762A (en) * 1991-08-05 1994-06-14 Aura Systems, Inc. Voice coil actuator

Also Published As

Publication number Publication date
EP0083045B1 (fr) 1985-11-21
US4628154A (en) 1986-12-09
EP0083045A3 (en) 1983-09-28
DE3267630D1 (en) 1986-01-02

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