US3334184A - Loudspeaker with feedback signal generator - Google Patents

Loudspeaker with feedback signal generator Download PDF

Info

Publication number
US3334184A
US3334184A US370262A US37026264A US3334184A US 3334184 A US3334184 A US 3334184A US 370262 A US370262 A US 370262A US 37026264 A US37026264 A US 37026264A US 3334184 A US3334184 A US 3334184A
Authority
US
United States
Prior art keywords
loudspeaker
cone
attached
transducer
apex
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
US370262A
Inventor
Koning Stephanus Hendrik De
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.)
US Philips Corp
North American Philips Co Inc
Original Assignee
US Philips 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 US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3334184A publication Critical patent/US3334184A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • H04R9/06—Loudspeakers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H03F1/36—Negative-feedback-circuit arrangements with or without positive feedback in discharge-tube amplifiers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/002—Damping circuit arrangements for transducers, e.g. motional feedback circuits

Definitions

  • the invention relates to a loudspeaker arrangement in which the movable portion of the loudspeaker is connected to a transducer for producing a voltage corresponding to the acceleration of the said movement.
  • the object of the present invention to provide a loudspeaker in which the said disadvantages are obviated.
  • the invention is characterized in that the transducer is secured to the apex of a conical member the base of which is attached to the device for driving the movable portion of the loudspeaker.
  • the loudspeaker in accordance with the invention comprises a movable portion in the form of a cone diaphragm 1 which is driven by a coil former 2 which is attached to the said diaphragm and on which a loudspeaker coil 3 is provided.
  • the coil former 2 together with the coil 3 are disposed within a magnet system shown diagrammatically, the arrangement being such that currents supplied to the loudspeaker coil 3 cause axial forces to be applied to the coil former so that the cone diaphragm is set into motion.
  • the said currents are produced by means of a loudspeaker amplifier 4 to which audio input signals from a source 5 are applied.
  • the transducer 6 is attached to the cone diaphragm a piezoelectric transducer 6 upon which an inertia proportional to the acceleration of the loudspeaker cone diaphragm is exerted.
  • the transducer is preferably made of a crystal material and hence is very hard. If the loudspeaker is accommodated in the wall 9 of an otherwise closed cabinet, for oscillations having a wavelength greater than one half of the circumference of the loudspeaker cone diaphragm the transducer pro- Patented Aug.
  • the joining means may provide difficulty in this respect. Due to the hardness of the crystal material from which is constructed transducer 6 it may unintentionally absorb mechanical forces and hence produce corresponding electric voltages.
  • the transducer 6 is secured to the apex of an axially rigid conical member 8, the base of which is attached to the loudspeaker diaphragm.
  • the conical member points in the direction in which the sound is radiated and consequently has acoustically satisfactory radiation properties.
  • it is so flexible radially as to prevent the transmission of radial forces from the conical diaphragm 1 to the solid cone apex to which the transducer 6 is secured.
  • the conical member is enclosed by a plate 10 to prevent pressure variations in the surrounding air from affecting the transducer.
  • the invention is based on the recognition that the axial movement of the cone 1 involves radial reaction forces exerted on the diaphragm 1 by the wall 9. These reaction forces reach the base of the conical member 8, attached to the coil former 3, along its entire circumference. Owing to the flexible conical construction chosen, however, they will be materially attenuated before reaching the apex of the conical member 8 so that no pressure corresponding to the said radial forces reaches the transducer 6 and hence the voltage delivered by the transducer 6 corresponds substantially to the axial accelerations only. Thus an important source of distortion in the production of a negative-feedback voltage is avoided.
  • the loudspeaker was provided with a conical diaphragm 1 having a diameter of 13 cm. and an apical angle of
  • the diameter of the coil former 3 was 2.6 cm. and its length 2.5 cm.
  • the conical member 8 was made of aluminium and had an apical angle of 40.
  • the diameter of the transducer 6 was 0.6 cm. and its length 1.6 cm. Its mass was of the same order of magnitude as that of the coil 3.
  • a loudspeaker for translating electrical signals into acoustic waves comprising, a radiating cone having its outer portion attached to a fixed support, first means attached to the inner portion of said cone for causing said cone to oscillate in response to electric signals when supplied to said means, a conical support means having its base attached to the said first means for movement thereby and its apex free standing, and a transducer mounted within the conical support means and attached to the support means at the apex for providing a voltage corresponding to the cone acceleration.
  • a loudspeaker for translating electrical signals into acoustic Waves comprising, a radiating cone having its outer portion attached to a fixed support, first means for establishing a positionally fixed magnetic field, second means located within the magnetic field and including a voice coil attached to the inner portion of said cone for causing said cone to oscillate in response to electric signals
  • a conical support 10 means having its base attached to said second means for movement thereby and its apex free standing, and a transducer mounted within the conical support means and References Cited UNITED STATES PATENTS 8/1960 Clements 179-1 11/1961 Bekey 179l KATHLEEN H. CLAFFY, Primary Examiner.

Landscapes

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

Description

1, 1967 's. H. DE KONING 3,334,184
LOUDSPEAKER WITH FEEDBACK SIGNAL GENERATOR Filed May 26, 1964 INVENTOR. STEPHANUS H.DE KONING BY m/ AGENT United States Patent 3,334,184 LOUDSPEAKER WITH FEEDBACK SIGNAL GENERATOR Stephanus Hendrik de Koning, Emmasingel, Eindhoven,
Netherlands, assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed May 26, 1964, Ser. No. 370,262 Claims priority, application Netherlands, June 21, 1963, 294,443; Sept. 26, 1963, 298,464 Claims. (Cl. 179-1) The invention relates to a loudspeaker arrangement in which the movable portion of the loudspeaker is connected to a transducer for producing a voltage corresponding to the acceleration of the said movement. It
is a particular object of the invention to provide a loudspeaker arrangement suitable for delivering a voltage which may be fed back degeneratively to an amplifier controlling the loudspeaker.
It has been suggested previously to couple the movable portion of the loudspeaker to an electromechanical transducer producing a voltage depending upon the loudspeaker movement. This arrangement always involved the difficulty that in such negative feedback undesirable oscillations are generated which indicate that undesirable phase shifts are produced between the electric current supplied to the loudspeaker and the voltage taken from the transducer. If the said phase shift should reach the value which is critical for the production of spurious oscillations only at the very high and very low frequencies, this disadvantage might be obviated by means of electric networks. It has been found, however, that phase shifts also occur within the reproducing band of the loudspeaker owing to resonance phenomena of the component parts joined to the loudspeaker. In practice elimination of the said phase shifts by means of electric networks proves to be highly complicated and sensitive to a variety of disturbances.
It is the object of the present invention to provide a loudspeaker in which the said disadvantages are obviated. The invention is characterized in that the transducer is secured to the apex of a conical member the base of which is attached to the device for driving the movable portion of the loudspeaker.
The invention will be described in detail with reference to the drawing which shows an embodiment of an arrangement in accordance with the invention and the associated circuit arrangement.
The loudspeaker in accordance with the invention comprises a movable portion in the form of a cone diaphragm 1 which is driven by a coil former 2 which is attached to the said diaphragm and on which a loudspeaker coil 3 is provided. The coil former 2 together with the coil 3 are disposed within a magnet system shown diagrammatically, the arrangement being such that currents supplied to the loudspeaker coil 3 cause axial forces to be applied to the coil former so that the cone diaphragm is set into motion. The said currents are produced by means of a loudspeaker amplifier 4 to which audio input signals from a source 5 are applied.
Since generally there is no purely linear relationship between the sound pressure produced by the moving cone diaphragm and the signal of the source 5 it is desirable to improve the said relationship by the provision of negative feedback. For this purpose there is attached to the cone diaphragm a piezoelectric transducer 6 upon which an inertia proportional to the acceleration of the loudspeaker cone diaphragm is exerted. The transducer is preferably made of a crystal material and hence is very hard. If the loudspeaker is accommodated in the wall 9 of an otherwise closed cabinet, for oscillations having a wavelength greater than one half of the circumference of the loudspeaker cone diaphragm the transducer pro- Patented Aug. 1, 1967 ice duces a voltage proportional to the square root of the radiated sound energy. At shorter wavelengths the voltage increases in proportion to the frequency in the case of constant sound energy. In order to allow for'the said effects, it is sufiicient to include a simple network 7 in the negative-feedback circuit, which network integrates the oscillations at shorter wavelengths in order that the negative-feedback voltage returned to the amplifier 4 depends substantially linearly on the square'root of the sound energy over the entire audio frequency range.
Hereinbefore it has been assumed that there are no parasitic phenomena which may cause the voltage of the transducer 6 to deviate from the said relationship. Since the transducer 6 must be joined to the diaphragm 1 in some way, the joining means may provide difficulty in this respect. Due to the hardness of the crystal material from which is constructed transducer 6 it may unintentionally absorb mechanical forces and hence produce corresponding electric voltages.
According to the invention the transducer 6 is secured to the apex of an axially rigid conical member 8, the base of which is attached to the loudspeaker diaphragm. The conical member points in the direction in which the sound is radiated and consequently has acoustically satisfactory radiation properties. Preferably it is so flexible radially as to prevent the transmission of radial forces from the conical diaphragm 1 to the solid cone apex to which the transducer 6 is secured. At its lower end the conical member is enclosed by a plate 10 to prevent pressure variations in the surrounding air from affecting the transducer.
The invention is based on the recognition that the axial movement of the cone 1 involves radial reaction forces exerted on the diaphragm 1 by the wall 9. These reaction forces reach the base of the conical member 8, attached to the coil former 3, along its entire circumference. Owing to the flexible conical construction chosen, however, they will be materially attenuated before reaching the apex of the conical member 8 so that no pressure corresponding to the said radial forces reaches the transducer 6 and hence the voltage delivered by the transducer 6 corresponds substantially to the axial accelerations only. Thus an important source of distortion in the production of a negative-feedback voltage is avoided.
In a practical embodiment, the loudspeaker was provided with a conical diaphragm 1 having a diameter of 13 cm. and an apical angle of The diameter of the coil former 3 was 2.6 cm. and its length 2.5 cm. The conical member 8 was made of aluminium and had an apical angle of 40. The diameter of the transducer 6 was 0.6 cm. and its length 1.6 cm. Its mass was of the same order of magnitude as that of the coil 3. By connecting the conical member 8 to earth the induction of ripple voltages in the transducer 6 was also avoided.
What is claimed is:
1. A loudspeaker for translating electrical signals into acoustic waves comprising, a radiating cone having its outer portion attached to a fixed support, first means attached to the inner portion of said cone for causing said cone to oscillate in response to electric signals when supplied to said means, a conical support means having its base attached to the said first means for movement thereby and its apex free standing, and a transducer mounted within the conical support means and attached to the support means at the apex for providing a voltage corresponding to the cone acceleration.
2. A loudspeaker as set forth in claim 1 in which the apex of the conical support means points substantially in the direction of propagation of the acoustic waves.
3. A loudspeaker as set forth in claim 1 in which the conical support means is constructed of metal which is at the base flexible in the radial direction and is provided with an electrically conductive path to ground.
4. A loudspeaker for translating electrical signals into acoustic Waves comprising, a radiating cone having its outer portion attached to a fixed support, first means for establishing a positionally fixed magnetic field, second means located within the magnetic field and including a voice coil attached to the inner portion of said cone for causing said cone to oscillate in response to electric signals When applied to said voice coil, a conical support 10 means having its base attached to said second means for movement thereby and its apex free standing, and a transducer mounted within the conical support means and References Cited UNITED STATES PATENTS 8/1960 Clements 179-1 11/1961 Bekey 179l KATHLEEN H. CLAFFY, Primary Examiner.
R. P. TAYLOR, Assistant Examiner.

Claims (1)

1. A LOUDSPEAKER FOR TRANSLATING ELECTRICAL SIGNALS INTO ACOUSTIC WAVES COMPRISING, A RADIATING CONE HAVING ITS OUTER PORTION ATTACHED TO A FIXED SUPPORT, FIRST MEANS ATTACHED TO THE INNER PORTION OF SAID CONE FOR CAUSING SAID CONE TO OSCILLATE IN RESPONSE TO ELECTRIC SIGNALS WHEN SUPPLIED TO SAID MEANS, A CONICAL SUPPORT MEANS HAVING ITS BASE ATTACHED TO THE SAID FIRST MEANS FOR MOVEMENT THEREBY AND ITS APEX FREE STANDING, AND A TRANSDUCER MOUNTED WITHIN THE CONICAL SUPPORT MEANS AND ATTACHED TO THE SUPPORT MEANS AT THE APEX FOR PROVIDING A VOLTAGE CORRESPONDING TO THE CONE ACCELERATION.
US370262A 1963-06-21 1964-05-26 Loudspeaker with feedback signal generator Expired - Lifetime US3334184A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL294443 1963-06-21
NL298464 1963-09-26

Publications (1)

Publication Number Publication Date
US3334184A true US3334184A (en) 1967-08-01

Family

ID=26641913

Family Applications (1)

Application Number Title Priority Date Filing Date
US370262A Expired - Lifetime US3334184A (en) 1963-06-21 1964-05-26 Loudspeaker with feedback signal generator

Country Status (11)

Country Link
US (1) US3334184A (en)
AT (1) AT247437B (en)
BE (1) BE649606A (en)
CH (1) CH434372A (en)
DE (1) DE1268680B (en)
DK (1) DK117642B (en)
ES (1) ES301214A1 (en)
FR (1) FR1401643A (en)
GB (1) GB1016115A (en)
NL (2) NL294443A (en)
SE (1) SE301503B (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5034223A (en) * 1973-06-12 1975-04-02
US3937887A (en) * 1969-05-15 1976-02-10 Ben O. Key Acoustic power system
US4176305A (en) * 1976-12-23 1979-11-27 Siemens Aktiengesellschaft Galvano magnetic position control system
FR2455839A1 (en) * 1979-05-03 1980-11-28 Electro Audio Dynamics METHOD AND DEVICE FOR PROTECTING AN ELECTROMECHANICAL TRANSDUCER
US4759065A (en) * 1986-09-22 1988-07-19 Harman International Industries, Incorporated Automotive sound system
US4809338A (en) * 1985-07-05 1989-02-28 Harman International Industries, Incorporated Automotive sound system
US5471527A (en) * 1993-12-02 1995-11-28 Dsc Communications Corporation Voice enhancement system and method
US5493620A (en) * 1993-12-20 1996-02-20 Pulfrey; Robert E. High fidelity sound reproducing system
US20120213388A1 (en) * 2011-02-18 2012-08-23 Rockefeller University Unidirectional Mechanical Amplification in a Microphone

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2420689C3 (en) * 1974-04-29 1984-09-20 Arndt 7500 Karlsruhe Klingelnberg Method and arrangement for improving the properties of electrodynamic transducers by means of negative motion
NO172469C (en) * 1984-01-25 1993-07-21 Per Kirksaeter SOUND REPLACEMENT SYSTEM
GB2201318B (en) * 1987-02-12 1990-10-24 Udi Group Ltd Electromechanical transducer
DE3707620A1 (en) * 1987-03-10 1987-10-15 Ultrasonics Schallfeld Messtec Acceleration sensor for dynamic loudspeakers
GB2260875B (en) * 1991-10-23 1995-06-28 Anthony Best Dynamics Ltd Noise source

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2948778A (en) * 1956-05-07 1960-08-09 Warner W Clements Sound reproducing means
US3009991A (en) * 1955-12-01 1961-11-21 Bekey Ivan Sound reproduction system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE451710A (en) * 1942-08-14
US2860183A (en) * 1954-02-01 1958-11-11 Conrad Ivan Willard Sound reproducing system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3009991A (en) * 1955-12-01 1961-11-21 Bekey Ivan Sound reproduction system
US2948778A (en) * 1956-05-07 1960-08-09 Warner W Clements Sound reproducing means

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937887A (en) * 1969-05-15 1976-02-10 Ben O. Key Acoustic power system
JPS5034223A (en) * 1973-06-12 1975-04-02
US3941932A (en) * 1973-06-12 1976-03-02 U.S. Philips Corporation Loudspeaker having a voice coil and a piezoelectric feedback transducer
US4176305A (en) * 1976-12-23 1979-11-27 Siemens Aktiengesellschaft Galvano magnetic position control system
FR2455839A1 (en) * 1979-05-03 1980-11-28 Electro Audio Dynamics METHOD AND DEVICE FOR PROTECTING AN ELECTROMECHANICAL TRANSDUCER
US4327250A (en) * 1979-05-03 1982-04-27 Electro Audio Dynamics Inc. Dynamic speaker equalizer
US4809338A (en) * 1985-07-05 1989-02-28 Harman International Industries, Incorporated Automotive sound system
US4759065A (en) * 1986-09-22 1988-07-19 Harman International Industries, Incorporated Automotive sound system
US5471527A (en) * 1993-12-02 1995-11-28 Dsc Communications Corporation Voice enhancement system and method
US5493620A (en) * 1993-12-20 1996-02-20 Pulfrey; Robert E. High fidelity sound reproducing system
US20120213388A1 (en) * 2011-02-18 2012-08-23 Rockefeller University Unidirectional Mechanical Amplification in a Microphone
US9084051B2 (en) * 2011-02-18 2015-07-14 The Rockefeller University Unidirectional mechanical amplification in a microphone

Also Published As

Publication number Publication date
FR1401643A (en) 1965-06-04
CH434372A (en) 1967-04-30
ES301214A1 (en) 1965-01-16
GB1016115A (en) 1966-01-05
AT247437B (en) 1966-06-10
BE649606A (en) 1964-12-22
DK117642B (en) 1970-05-19
NL298464A (en)
DE1268680B (en) 1968-05-22
SE301503B (en) 1968-06-10
NL294443A (en)

Similar Documents

Publication Publication Date Title
US3334184A (en) Loudspeaker with feedback signal generator
US3798374A (en) Sound reproducing system utilizing motional feedback
US6611606B2 (en) Compact high performance speaker
US4573189A (en) Loudspeaker with high frequency motional feedback
US3665124A (en) Loudspeaker having annular diaphragm with double voice coil
US2860183A (en) Sound reproducing system
US1907723A (en) Sound reproducing device
US4256923A (en) Sound reproducing system utilizing motional feedback and integrated magnetic structure
US2007746A (en) Acoustic device
US4163876A (en) Electro-acoustic transducer with variable thickness foam surfaced diaphragm
US3955055A (en) Dynamic loudspeaker
US1755636A (en) Loud-speaker
US3073899A (en) Transducing apparatus
US1766473A (en) Electrodynamic device
US2942071A (en) Horn-type transducer
US3114429A (en) Loudspeaker
US3014099A (en) Electroacoustic transducer
US2489862A (en) Damping for dynamic loudspeakers
US2205365A (en) Radio receiver
EP1329130B1 (en) Compact high performance speaker
US2303989A (en) Signal translating apparatus
US3193627A (en) High fidelity loudspeakers
US2922849A (en) Compound electric speaker
US1812389A (en) Acoustic device
US1895441A (en) Sound translating device