EP0208907B1 - Système magnétique pour haut-parleur dynamique - Google Patents

Système magnétique pour haut-parleur dynamique Download PDF

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Publication number
EP0208907B1
EP0208907B1 EP86107808A EP86107808A EP0208907B1 EP 0208907 B1 EP0208907 B1 EP 0208907B1 EP 86107808 A EP86107808 A EP 86107808A EP 86107808 A EP86107808 A EP 86107808A EP 0208907 B1 EP0208907 B1 EP 0208907B1
Authority
EP
European Patent Office
Prior art keywords
magnetic
air gap
section
voice coil
saturation
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.)
Expired - Lifetime
Application number
EP86107808A
Other languages
German (de)
English (en)
Other versions
EP0208907A1 (fr
Inventor
Paul Zwicky
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.)
Harman International Industries Inc
Original Assignee
Willi Studer AG Fabrik fuer Elektronische Apparate
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 Willi Studer AG Fabrik fuer Elektronische Apparate filed Critical Willi Studer AG Fabrik fuer Elektronische Apparate
Priority to AT86107808T priority Critical patent/ATE51994T1/de
Publication of EP0208907A1 publication Critical patent/EP0208907A1/fr
Application granted granted Critical
Publication of EP0208907B1 publication Critical patent/EP0208907B1/fr
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
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/02—Details
    • H04R9/025—Magnetic circuit

Definitions

  • the invention relates to a magnet system for a dynamic loudspeaker with a magnetic circuit with an air gap in which conductors which are movable in one direction of movement and are connected to a power source are provided.
  • current-carrying conductors are usually arranged in a voice coil or moving coil. This is immersed in an annular magnetic field.
  • the voice coil or plunger coil is connected, for example, to an amplifier which emits electrical signals which are to be converted into acoustic signals. These electrical signals cause a deflection of the voice or moving coil in the magnetic field or in the air gap, whereby a diaphragm can be driven.
  • voice coil loudspeakers The emission of deep tones with sufficient volume is practically only possible with moving coil systems.
  • the fidelity of voice coil loudspeakers is limited by various circumstances, such as non-linear restoring force of the membrane suspension, non-linear restoring force caused by the air cushion in the loudspeaker housing (adiabatic), inhomogeneity of the magnetic field in the air gap, natural resonances of the diaphragm and housing and whirlpools Pole shoes of the diaphragm drive system etc.
  • the additional excitation in the magnetic circuit corresponds to the armature reaction in electrical drives.
  • This additional excitation in the magnetic circuit which is dependent on the direction in which the current flows through the voice coil, leads to an amplification or weakening of the magnetic field in the entire magnetic circuit and thus also in the air gap.
  • the center point of the vibrations of the voice coil moves inwards with respect to the magnet, which is generally referred to as mechanical rectification. This also reduces the possible vibration amplitude.
  • the change in the magnetic field in the air gap alone consists in the fact that the magnetic field strength can have a gradient seen across the depth of the air gap. This slope changes when the direction of the current or when the strength of the current in the voice coil changes.
  • a device which aims to compensate for the disadvantages of the above-mentioned change in the magnetic field in the air gap and to ensure that the current in the voice coil is not distorted. It is proposed to arrange means directly adjacent to the air gap in which the magnetic flux is partially saturated. This ensures that the current in the voice coil is not adversely affected by a changing magnetic field in the air gap.
  • German patent no. 594 490 It is also known from German patent no. 594 490 and also from the already mentioned US patent to keep the entire magnetic circuit associated with the air gap saturated. According to the US patent, this results in improvements in the movement of the voice coil. According to the German patent specification, an advantageous effect can be achieved with such a saturated magnetic circuit if this saturated magnetic circuit is connected in parallel with an unsaturated magnetic circuit.
  • the positive effect is that humming noises in the loudspeaker can be avoided with a pulsating excitation current of a magnetic circuit excited with direct current.
  • the magnet Field may then look for other ways than those through the air gap. Further measures must then be taken in order to avoid these disadvantages, which causes an increased outlay.
  • the invention as characterized in the claims solves the task of creating a simple, light and inexpensive magnet system for a low-distortion dynamic speaker.
  • the means according to the invention can be used for magnet systems of any size, in particular also of small sizes.
  • the high differential magnetic resistance in the vicinity of the operating point results in a low inductance in the voice coil. This results in a better frequency response at high frequencies and thus a better reproduction of high tones.
  • the solution according to the invention results in a uniform improvement over the entire range of the voice coil movement.
  • the solution according to the invention also offers few problems in the manufacture of the magnet systems by allowing large manufacturing tolerances, since changes in the magnetic flux have little or no effect on the operation of the loudspeaker. All speakers in a series can sound equally good.
  • FIG. 1 shows a characteristic curve 1 for a specific given magnet system.
  • This characteristic curve 1 has a linear area 2 and a saturation area 3 in a manner known per se.
  • This characteristic curve 1 lies between axes 4 and 5.
  • On the vertical axis 4 there are values for the magnetic flux Phi and on the horizontal axis 5 there are values for the product of current strength I and number of turns n for excitation of the magnet system or in short values for excitation in Magnet system applied.
  • This characteristic curve 1 expresses that in the linear region 2 an increase in the current in the coil must be followed by a proportional increase in the magnetic flux. It also expresses the fact that in the saturated area 3 an increase in excitation is almost followed by no increase in magnetic flux.
  • the excitation can be changed by the magnet system or by the coil or by both.
  • Lines 7 and 8 indicate possible limits for changes in the product of current strength and number of turns I n. Such changes result in changes in the magnetic flux Phi that lie within the limits indicated by lines 9 and 10.
  • FIG. 2 shows a magnet system 11 for a dynamic loudspeaker with a magnetic circuit, which essentially consists of a pole piece 12, a pole disc 13, a permanent magnet 14 as an exciter and an air gap 15.
  • the magnet system is designed to be rotationally symmetrical, which has the consequence that the air gap 15 is annular.
  • a voice coil 16, which is arranged on a coil former 17, is connected to a current source 18.
  • Known audio amplifiers can be used as the power source 18, for example.
  • the bobbin 17 is connected to a membrane, not shown.
  • the voice coil 16 consists of current-carrying and movable conductors which drive the coil body 17.
  • the pole piece 12 has a constriction 19 which defines a cross section 20 and forms a section 22.
  • This cross section 20 limits the magnetic flux that can flow in the magnet system 11 exactly. Magnetic saturation occurs in section 22. The strength of a magnetic field 21 in the magnetic circuit and thus also in the air gap 15 is thus limited.
  • sections 29 and 30 are connected, which are not magnetically saturated.
  • the air gap 15 is also not magnetically saturated.
  • FIG. 3 shows a magnet system 11 similar to that shown in FIG. 2.
  • the pole piece 12 has a section 22 which consists of a material which has a lower induction of saturation than the rest of the material used for the pole piece 12 and / or the pole disk 13.
  • FIG. 4 shows a magnet system 11 with a pole piece 12 of a constriction 19 for a precisely limited cross section, which has a length 24 and forms a section 22 in which magnetic saturation occurs.
  • This length 24 corresponds to the extension of the permanent magnet 14 or generally the extension 26 of the excitation in the direction of the axis 27 of the voice coil 16.
  • This constriction 19 is preferably filled with a short-circuit ring 25 made of copper, for example.
  • the mode of operation of the device according to the invention is that a section 22 is formed with a precisely determined cross-section 20 or with a precisely dimensioned saturation induction at one point in the magnet system 11, which causes the operating point 6 of the magnet system 11 to be set in such a way that a small one Changing the excitation leads to a negligible change in the magnetic flux.
  • the entire excitation of the magnet system 11, which results from the constant excitation by the per magnet magnets 14 and composed of the variable excitation by the voice coil 16 give a magnetic flux which lies in the saturated region 3 of the characteristic 1 of the magnet system 11.
  • changes in the current in the voice coil 16 cause practically no change in the magnetic flux and thus no change in the magnetic field 21.
  • the force for the deflection of the voice coil 16 depends practically only on the current which flows through the voice coil 16 in a proportional manner. This results in extremely low distortion for actuators for dynamic loudspeakers with appropriate magnet systems.
  • the inclination alfa of the linear region 2 of the characteristic curve 1 is given by the magnetic resistance of the magnetic circuit, all the materials involved working below their magnetic saturation.
  • the inclination beta of the saturated region 3 of the characteristic curve 1 is also determined by the magnetic resistance of the magnetic circuit. But provided that certain points in the magnetic circuit are used beyond their magnetic saturation. The larger the length 23, 24 of the constriction 19 or of the section 22, the lower the inclination beta of the saturation region 3. Remaining changes in the magnetic flux 28 (FIG. 1) in the magnetic circuit can be further reduced with the aid of a short-circuit ring 25 (FIG. 4). Its effect increases with increasing frequencies.
  • Means or sections 22 which limit the magnetic flux can be provided at many locations in the magnetic circuit. However, since the length of such sections 22 plays a decisive role, not all points in the magnetic circuit are equally suitable for this. The aim is to have the lowest possible inclination beta of the saturation region 3, since in this case the influence of the magnetic field which is generated by the voice coil 16 and which propagates in the magnet system 11 becomes as small as possible.
  • Means or sections 22 are preferably to be arranged in the pole piece 12. Sections 22 or parts of such sections in which the magnetic field is saturated should not, however, be arranged directly adjacent to the air gap 12 or even contain the air gap 12 itself.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)

Claims (6)

1. Système magnétique pour haut-parleur dynamique qui comprend un circuit magnétique (12, 13, 14) avec un entrefer (15) où plongent des conducteurs (16) movibles dans une direction prédéterminée qui sont raccordés à une source de courant (18) électrique, caractérisé en ce que le circuit magnétique a des moyens logés en dehors de l'entrefer qui limitent le flux magnétique dans le circuit magnétique et qui forment un secteur (22), logé en dehors de l'entrefer, où le flux magnétique est saturé et qui forment des sections (29, 30) qui touchent l'entrefer et où le flux magnétique n'est pas saturé.
2. Système selon la revendication 1, caractérisé en ce que les moyens dans le circuit magnétique consistent en une section (20) de dimension précise qui forme un secteur (22) où le flux magnétique est saturé.
3. Système selon la revendication 1, caractérisé en ce que le secteur (22) est réalisé en un matériau dont la limite de saturation magnétique est basse.
4. Système selon la revendication 1, caractérisé en ce que la longueur (23, 24) du secteur (22) correspond à la dimension (26) de l'excitation (14) dans le sens de l'axe (27) de la bobine (16).
5. Système selon la revendication 1, caractérisé en ce que le secteur (22) est prévu dans le pôle central (12) du circuit magnétique.
6. Système magnétique selon la revendication 5, caractérisé en ce que le pôle central (12) est entouré d'un anneau court-circuit (25) à l'endroit du secteur (22).
EP86107808A 1985-07-17 1986-06-07 Système magnétique pour haut-parleur dynamique Expired - Lifetime EP0208907B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86107808T ATE51994T1 (de) 1985-07-17 1986-06-07 Magnetsystem fuer einen dynamischen lautsprecher.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH3102/85 1985-07-17
CH310285 1985-07-17

Publications (2)

Publication Number Publication Date
EP0208907A1 EP0208907A1 (fr) 1987-01-21
EP0208907B1 true EP0208907B1 (fr) 1990-04-11

Family

ID=4248662

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86107808A Expired - Lifetime EP0208907B1 (fr) 1985-07-17 1986-06-07 Système magnétique pour haut-parleur dynamique

Country Status (4)

Country Link
US (1) US4980921A (fr)
EP (1) EP0208907B1 (fr)
AT (1) ATE51994T1 (fr)
DE (1) DE3670417D1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6774510B1 (en) * 2000-10-25 2004-08-10 Harman International Industries, Inc. Electromagnetic motor with flux stabilization ring, saturation tips, and radiator
US7039213B2 (en) * 2002-01-16 2006-05-02 Hyre David E Speaker driver
JP3946047B2 (ja) * 2002-01-21 2007-07-18 アルパイン株式会社 スピーカの磁気回路
GB201907610D0 (en) * 2019-05-29 2019-07-10 Pss Belgium Nv Loudspeaker

Family Cites Families (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE594490C (de) * 1934-03-17 Rca Corp Magnetsystem, insbesondere fuer dynamische Lautsprecher
US2026994A (en) * 1929-05-15 1936-01-07 Messick Charles Armature for magnetic movements
US2141595A (en) * 1937-01-13 1938-12-27 Cinaudagraph Corp Magnet structure
US2223496A (en) * 1937-11-12 1940-12-03 Osborne I Price Sound reproducer
GB721325A (en) * 1952-07-04 1955-01-05 Harry Claude Willson Improvements relating to electro-dynamic sound reproducers of the moving coil type
GB911411A (en) * 1959-03-05 1962-11-28 Telefunken Gmbh Improvements in or relating to moving coil loudspeakers and to radio receiving apparatus including such loudspeakers
US3134057A (en) * 1960-07-11 1964-05-19 Sumitomo Metal Ind Magnetic circuit for the deflection of flux leakage
US3079472A (en) * 1960-10-06 1963-02-26 Rca Corp Magnetic field structure for transducers and method of constructing same
NL274625A (fr) * 1961-02-10
US3240882A (en) * 1962-01-31 1966-03-15 Gen Electric Permanent magnet type loudspeakers
US3482062A (en) * 1967-04-18 1969-12-02 William Hecht Damped electro-acoustic high frequency transducer
US3783311A (en) * 1970-12-19 1974-01-01 Coral Audio Corp Magnetic device for use in acoustic apparatus
JPS542647Y2 (fr) * 1971-03-10 1979-02-05
DK142299B (da) * 1972-12-27 1980-10-06 Ragnar Lian Højttaler.
JPS51138431A (en) * 1975-05-26 1976-11-30 Mitsubishi Electric Corp Speaker
JPS5389728A (en) * 1977-01-19 1978-08-07 Sansui Electric Co Loudspeaker unit
US4289937A (en) * 1978-05-30 1981-09-15 Mitsubishi Denki Kabushiki Kaisha Speaker with fine grain ferromagnetic material on center pole or ring
US4293741A (en) * 1979-06-21 1981-10-06 Digre Clifford B Magnet assembly
US4295011A (en) * 1979-09-11 1981-10-13 Epicure Products Inc. Linear excursion-constant inductance loudspeaker
JPS5931111Y2 (ja) * 1980-07-19 1984-09-04 パイオニア株式会社 ダイナミツクマイクロホン
US4580015A (en) * 1981-09-29 1986-04-01 Peavey Electronics Corp. Loud speaker with minimized magnetic leakage
JPS59139794A (ja) * 1983-01-31 1984-08-10 Ibuki Kogyo Kk 漏洩磁場を打消したホ−ンスピ−カ−
US4661973A (en) * 1983-12-03 1987-04-28 Pioneer Electronic Corporation Minimization of distortion due to a voice coil displacement in a speaker unit
US4547632A (en) * 1984-04-04 1985-10-15 Electro-Voice, Incorporated Dynamic loudspeaker

Also Published As

Publication number Publication date
US4980921A (en) 1990-12-25
DE3670417D1 (de) 1990-05-17
EP0208907A1 (fr) 1987-01-21
ATE51994T1 (de) 1990-04-15

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