EP0537705A2 - A loudspeaker - Google Patents

A loudspeaker Download PDF

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Publication number
EP0537705A2
EP0537705A2 EP92117537A EP92117537A EP0537705A2 EP 0537705 A2 EP0537705 A2 EP 0537705A2 EP 92117537 A EP92117537 A EP 92117537A EP 92117537 A EP92117537 A EP 92117537A EP 0537705 A2 EP0537705 A2 EP 0537705A2
Authority
EP
European Patent Office
Prior art keywords
diaphragm
loudspeaker
voicecoil
accordance
woofer
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.)
Withdrawn
Application number
EP92117537A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0537705A3 (enrdf_load_stackoverflow
Inventor
Katsuhiko c/o Lux Corporation Iida
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.)
LUX Corp
Original Assignee
LUX 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 LUX Corp filed Critical LUX Corp
Publication of EP0537705A2 publication Critical patent/EP0537705A2/en
Publication of EP0537705A3 publication Critical patent/EP0537705A3/xx
Withdrawn legal-status Critical Current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
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/24—Structural combinations of separate transducers or of two parts of the same transducer and responsive respectively to two or more frequency ranges

Definitions

  • the present invention relates to a loudspeaker which consists of plural diaphragms and has wide frequency range.
  • Coaxial loudspeaker systems which consist of one loudspeaker referred to as a "tweeter” for higher frequencies and another loudspeaker referred to as a "woofer” for lower frequencies, are used in high fidelity audio systems.
  • a coaxial loudspeaker system is one in which a tweeter is arranged within a voicecoil of a woofer.
  • the above coaxial loudspeaker can reproduce a natural acoustic sound field because the tweeter and the woofer, which are arranged coaxially, can act like a single source of acoustic sound.
  • the above coaxial loudspeaker system has many limitations in design, because it is necessary to arrange the magnet, the voicecoil, and the diaphragm of the tweeter inside of the limited space of the woofer.
  • the voicecoil of the tweeter must function under the influence of the magnetic field which originates from the woofer, because the magnetic circuit of the woofer is much stronger than the magnetic circuit of the tweeter.
  • Figs. 12 to 14 show the structure of a new type of coaxial loudspeaker, which avoids the above influence of the woofer on the tweeter.
  • Numeral 10 indicates a resilient suspension which suspends the diaphragm 8 of the woofer; diaphragm 12 for a tweeter is made of conductive materials e.g. metal, and are arranged inside of the voicecoil 6 as shown in Figs. 13 and 14; diaphragm 12 for a tweeter consists of a half shell part 14 and a cylindrical part 16; diaphragm 12 is suspended by an axis 18, which is fixed on the central magnetic core 4 with a suspending piece 20.
  • a reflecting piece 22, which compensates for the acoustic waves emitted from the diaphragm 12, is fixed at the top of the axis 18.
  • the cylindrical part 16 acts as a coil, because the cylindrical part 16 has a round shape in cross sectional view so as to form a single turned coil.
  • the cylindrical part 16 can generate electrical current in the magnetic field which is generated by the voicecoil 6. Therefore, the voicecoil 6 acts as a first coil of a transformer together with the cylindrical part 16 which acts as a second coil of the transformer.
  • the diaphragm 8 for the woofer is easily driven by the current in the voicecoil 6.
  • the current through the voicecoil 6 is not sufficient to drive the tweeter's diaphragm 12 because the impedance of the voicecoil 6 is high below the upper limit of the woofer's oscillating frequency range.
  • the tweeter's diaphragm 12 is easily driven by the woofer's voicecoil 6 easily, because the impedance of the woofer's voicecoil 6 is lower than the impedance at the lower frequency range.
  • the coaxial loudspeaker system can reproduce acoustic sound within a wide frequency range because the diaphragm 6 can be driven easily only in the lower frequency range and because the diaphragm 12 can be driven easily only in the higher frequency range without a frequency dividing network which divides the driving current for the loudspeakers.
  • the above coaxial loudspeaker system has the following problems.
  • the present invention discloses a loudspeaker system comprising a first diaphragm which is driven by a driving signal which is supplied into a voicecoil which is connected with said first diaphragm, and a ferromagnetic second diaphragm which is supported relatively movable with respect to the first diaphragm.
  • the loudspeaker system reproduces a natural acoustic sound field as in conventional coaxial loudspeaker systems.
  • the first diaphragm can be driven easily by the driving current at lower frequencies according to its own mechanical oscillating mode. At the above frequency, the current through the voicecoil of the first diaphragm is not sufficient to drive the second diaphragm. The impedance of the voicecoil decreases and the current through the voicecoil increases enough to drive the second diaphragm above the upper limit of the oscillating mode of the first diaphragm. According to the increasing of the current, the second diaphragm begins to osculate in the magnetic field which originates from the voicecoil. Therefore, the first diaphragm can reproduce lower frequency acoustic sound and the second diaphragm can reproduce higher frequency acoustic sound without a frequency dividing circuit which divides the driving current for loudspeakers.
  • the second diaphragm can be made easily and cheaply because it can act as a tweeter through its own ferromagnetism and elastic deformation. It is easy to produce the second diaphragm, which is light in weight, because the design form and the selection of the materials for the diaphragm is flexible. Therefore, the second diaphragm obtains a sensitive compliance to the driving signal.
  • Fig.1 is a longitudinal sectional view of the loudspeaker system of the first embodiment.
  • Fig. 2 is a longitudinal sectional view of the diaphragm of the first embodiment.
  • Fig. 3 is a longitudinal sectional view of the diaphragm of the second embodiment.
  • Fig. 4 is an angled view of the diaphragm of the third embodiment.
  • Fig. 5 is a longitudinal sectional view of the loudspeaker system of the fourth embodiment.
  • Fig. 6 is a longitudinal sectional view of the diaphragm of the fifth embodiment.
  • Fig. 7 is an angled view of the diaphragm of the sixth embodiment.
  • Fig. 8 is a longitudinal sectional view of the diaphragm of the sixth embodiment.
  • Fig. 9 is an angled view of the diaphragm of the seventh embodiment.
  • Fig. 10 is an angled view of the diaphragm of the eighth embodiment.
  • Fig. 11 is a longitudinal sectional view of the ninth embodiment.
  • Fig. 12 is a longitudinal view of an example of a conventional loudspeaker system.
  • Fig. 13 is an angled view of a diaphragm of the loudspeaker system shown in Fig. 12.
  • Fig. 14 is a longitudinal sectional view of the diaphragm shown in Fig. 13.
  • Figs. 1 and 2 show a first embodiment of the invention.
  • the numeral 40 indicates a diaphragm which acts as a tweeter.
  • the diaphragm 40 is connected to one end of a suspending piece 42, the other end of which is connected to a central magnetic core 8.
  • the diaphragm 40 is made of ferromagnetic materials, e.g., steel, formed as a thin sheet.
  • the diaphragm 40 is magnetized as shown in Fig. 2.
  • One side of the diaphragm 40 which faces the top of the central magnetic core 4 which is magnetized as a north pole, is magnetized to reversed polarity with respect to the central magnetic core 4. Therefore, the other side of the diaphragm 40 is magnetized as a north pole.
  • the materials which are suitable for the diaphragm 40 are not limited to metals. Many kinds of ferromagnetic materials are suitable for the diaphragm 40. A plastic sheet or film, e.g., polyester, which is coated by a ferromagnetic layer, is also suitable for the diaphragm 40.
  • the suspending piece 42 is formed like a bellows having many corrugations for flexibility.
  • the suspending piece 42 can support diaphragm 40 resiliently.
  • a block, which is made of foamed rubber or plastic is also suitable for used in a resilient suspension.
  • the diaphragm 40 is suspended by the suspending piece 42 independently of the diaphragm 8.
  • the voicecoil is magnetized by the driving signal and the diaphragm 8 for the woofer is driven by the magnetically induced current between the voicecoil 6 and the magnet 2.
  • the diaphragm 8 for the woofer having a minimum diameter of 5-10 centimeters and a maximum diameter of 20-40 centimeters, can be driven easily by a driving current of a frequency of less than a few thousands Hz, because there is a limit in the reproduction frequency range for the diaphragm 8 of the woofer according to its own mechanical oscillating mode.
  • the diaphragm 8 for the woofer can be driven easily below the upper limit of the reproduction frequency range.
  • the current through the voicecoil 6 is not sufficient to drive the diaphragm 40 of the tweeter; this is because the impedance of the voicecoil 6 is high below the upper limit of the above frequency range.
  • the impedance of the voicecoil 6 decreases and the current through the voicecoil 6 increases enough to drive the diaphragm 40 of the tweeter, above the upper limit of the oscillating mode. According to the increasing of the current, the diaphragm 40 begins to oscillate in the magnetic field, which originates from the voicecoil 6.
  • the diaphragm 8 of the woofer can reproduce lower frequency acoustic sounds and the diaphragm 40 of the tweeter can reproduce higher frequency acoustic sound without a frequency dividing circuit which divides driving current for loudspeakers.
  • Fig. 3 shows a second embodiment of the invention.
  • a diaphragm 40 is not actively magnetized but is instead passively magnetized by a central magnetic pole 4.
  • One side of the diaphragm 40 which faces to the central magnetic pole 4 is magnetized into a south pole by the central magnetic pole 4 which has been magnetized into a north pole.
  • the above magnetized diaphragm 40 is driven by a magnetic field which originates by a voicecoil 3 as a manner similar to that of the first embodiment.
  • Fig. 4 shows a third embodiment of the present invention.
  • a plurality of slits 46 are provided in a ferromagnetic diaphragm 44.
  • the slits 46 are arranged to cut off eddy currents which are produced in the diaphragm 44 by a voicecoil (not shown in Fig. 4) when the diaphragm is electrically conductive.
  • a circular circuit, which would be formed in the diaphragm 44 in the magnetic field of the voicecoil, is interrupted by the slits 46, and therefore eddy currents cannot be generated in the diaphragm 44.
  • the efficiency of woofer in which the diaphragm 44 is thus arranged is not degraded by the eddy currents.
  • FIG. 5 ahows a fourth embodiment.
  • a diaphragm 48 which is formed in a convex shape so as to emit acoustic sound over a wide area, is arranged coaxially inside of a diaphragm 8 of a woofer.
  • Fig. 6 illustrates a fifth embodiment.
  • a diaphragm 50 which is formed in a concave shape so as to emit acoustic sound over a predetermined limited area, is arranged inside of a diaphragm 8 of a woofer coaxially.
  • FIG. 7 and Fig.8 illustrate a sixth embodiment.
  • a diaphragm 52 has a coaxial hole 54 in which a third diaphragm 56 is arranged.
  • the diaphragm 56 can be driven as a super tweeter to reproduce acoustic sound above a frequency range of the diaphragm 52 which acts as a tweeter.
  • the diaphragm 52 for a tweeter is connected with one end of a suspending piece 58, another end of which is connected with a central magnetic core 4.
  • the diaphragm 56 for a super tweeter is connected with one end of a suspending piece 60, another end of which is connected with a central magnetic core 4.
  • Each suspending piece 58 and 60 are arranged coaxially. It is possible to design the diaphragms 52 and 56 to alternate frequency ranges in which these diaphragms 52 and 56 can be driven easily, by changing the form, the materials, the weight of the diaphragms 52 and 56, or by suspending pieces 58 and 60.
  • a three way loudspeaker system of simple construction may be obtained without a frequency dividing circuit which divides the driving currents for a loudspeaker.
  • a construction to suspend the diaphragm 56 is not limited in those shown Figs. 7 and 8.
  • the diaphragm 56 can also be suspended by the diaphragm 52.
  • Fig. 9 illustrates a seventh embodiment.
  • Four diaphragms 61 each of which is formed as a quarter circle, are arranged on a suspending piece 62.
  • the suspending piece 62 is made of foam plastic or rubber and is formed as an cylindrical column.
  • the diaphragms 61 are arranged so as not to be in contact with one another so as to cut off any eddy currents.
  • Fig. 10 and Fig. 11 illustrate a eighth embodiment.
  • Two diaphragms 64 are arranged on a suspending piece 62.
  • the diaphragms 64 are arranged so as not to contact each other so as to cut off any eddy currents.
  • a diaphragm 56 is arranged in the hole 54 which is formed for the diaphragms 64.

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
EP92117537A 1991-10-16 1992-10-14 A loudspeaker Withdrawn EP0537705A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP3267951A JPH0761200B2 (ja) 1991-10-16 1991-10-16 スピーカ
JP267951/91 1991-10-16

Publications (2)

Publication Number Publication Date
EP0537705A2 true EP0537705A2 (en) 1993-04-21
EP0537705A3 EP0537705A3 (enrdf_load_stackoverflow) 1994-03-23

Family

ID=17451867

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92117537A Withdrawn EP0537705A2 (en) 1991-10-16 1992-10-14 A loudspeaker

Country Status (2)

Country Link
EP (1) EP0537705A2 (enrdf_load_stackoverflow)
JP (1) JPH0761200B2 (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2794604A1 (fr) * 1999-06-04 2000-12-08 Pierre Piccaluga Transformateur electro acoustique pour la reproduction du son
CN102685654A (zh) * 2012-05-04 2012-09-19 李植扬 同轴扬声器

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4662522B2 (ja) * 2000-09-28 2011-03-30 パナソニック株式会社 電磁形電気音響変換器および携帯端末装置

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4016376A (en) * 1975-01-06 1977-04-05 General Signal Corporation Concave diaphragm for electro-acoustic transducer
JPS56116398A (en) * 1980-02-20 1981-09-12 Pioneer Electronic Corp Multiway coaxial flat plane type speaker
JPS5957599A (ja) * 1982-09-27 1984-04-03 Katsuya Ishizaki ヘツドホン
JPS59164390U (ja) * 1983-04-15 1984-11-05 株式会社　双信音響製作所 同軸型複合スピ−カ
GB8809805D0 (en) * 1988-04-26 1988-06-02 Gabr S Electromagnetic transducer
DE68921924T3 (de) * 1988-06-02 2002-04-11 Boaz Elieli Elektroakustischer Wandler und Lautsprecher.
JPH10293U (ja) * 1997-12-08 1998-12-18 積水化学工業株式会社 排水桝の接続部材

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2794604A1 (fr) * 1999-06-04 2000-12-08 Pierre Piccaluga Transformateur electro acoustique pour la reproduction du son
WO2000076270A3 (fr) * 1999-06-04 2001-06-21 Claude Annie Perrichon Transducteurs haute definition
CN102685654A (zh) * 2012-05-04 2012-09-19 李植扬 同轴扬声器

Also Published As

Publication number Publication date
JPH0761200B2 (ja) 1995-06-28
JPH05344592A (ja) 1993-12-24
EP0537705A3 (enrdf_load_stackoverflow) 1994-03-23

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