DE2448506A1 - Overload protection circuit for loudspeakers - has temperature sensor monitoring vibrating coil and controlling output power of amplifier system - Google Patents

Overload protection circuit for loudspeakers - has temperature sensor monitoring vibrating coil and controlling output power of amplifier system

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Publication number
DE2448506A1
DE2448506A1 DE19742448506 DE2448506A DE2448506A1 DE 2448506 A1 DE2448506 A1 DE 2448506A1 DE 19742448506 DE19742448506 DE 19742448506 DE 2448506 A DE2448506 A DE 2448506A DE 2448506 A1 DE2448506 A1 DE 2448506A1
Authority
DE
Germany
Prior art keywords
voice coil
temperature
temperature sensor
loudspeakers
output power
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.)
Pending
Application number
DE19742448506
Other languages
German (de)
Inventor
Wolfgang Backes
Friedrich Mueller
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.)
Backes & Mueller
Original Assignee
Backes & Mueller
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 Backes & Mueller filed Critical Backes & Mueller
Priority to DE19742448506 priority Critical patent/DE2448506A1/en
Publication of DE2448506A1 publication Critical patent/DE2448506A1/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
    • 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
    • H04R3/007—Protection circuits for transducers

Abstract

The overload protection circuit, for loudspeakers, has a temperature sensor which is used to reduce the output power of the amplifier according to the temperature of the vibrating coil. The temperature sensor may be a temperature sensitive resistor which is kept in good thermal contact with the vibrating coil, or it may be the coil itself -- i.e. changes in the resistance of the coil due to changes of temperature may be monitored. Another method uses an electronic model of the behavious of the loudspeaker and obtains the criterion for controlling the input power from this.

Description

Schaltungsanordnung zum Schutz dynamischer Lautsprecher vor Uberlastung.Circuit arrangement for protecting dynamic loudspeakers from overload.

Zum Schutz dynamischer Lautsprecher vor Uberlastung ist es üblich, den zur Ansteuerung verwendeten Verstärker so zu dimensionieren, daß die maximal abgegebene Leistung geringer ist als die Leistung, die der Lautsprecher im Dauerbetrieb verarbeiten kann, ohne Schaden zu nehemen.To protect dynamic loudspeakers from overload, it is common to to dimension the amplifier used for control so that the maximum The output power is less than the power that the loudspeaker can produce in continuous operation can handle without harm.

Oder aber man dimensoiniert den Verstärker, z.B. durch geeignete Wahl der Zeitkonstanten im Netzteil, so, daß er kurzzeitig eine hohe Spitzenleistung abgibt, die dann bei längerer Dauer absinkt.Or the amplifier is dimensioned, e.g. through a suitable choice the time constants in the power supply so that it briefly has a high peak power releases, which then decreases with longer duration.

Die Wirksamkeit aller dieser Verfahren ist abhängig vom Verlauf des auf den Lautsprecher gegebenen Niederfrequenzsignals. Zwar lassen sich derartige Schaltungen so dimensionieren, daß sie für bestimmte Arten von Programm (z.B.The effectiveness of all of these procedures depends on the course of the low frequency signal given to the speaker. It is true that such Dimension circuits so that they are suitable for certain types of program (e.g.

entweder symphonische Musik oder Popmusik) hinreichend funktionieren. Jedoch erfüllen sie bei wechselndem Programm wegen der stark unterschiedlichen Amplitudenverteilungen ihren Zweck nur unzulänglich.either symphonic music or pop music) work adequately. However, they meet with a changing program because of the greatly different amplitude distributions their purpose only inadequate.

Das nachfolgend beschriebene Verfahren vermeidet diesen Nachteil und gewährleistet bei allen Arten von Programm eine optimale Ausnutzung der Lautsprecherbelastbarkeit.The method described below avoids this disadvantage and ensures optimum use of the loudspeaker capacity for all types of program.

Erfindungsgemäß wird als Kriterium zur Verringerung der Verstärkerleistung eine Größe herangezogen, die eine zuverlässige Aussage darüber liefert, ob der Lautsprecher überlastet ist oder nicht, nämlich die Temperatur der Schwingspule.According to the invention, the criterion for reducing the amplifier power a variable is used that provides a reliable statement as to whether the loudspeaker is used overloaded or not, namely the temperature of the voice coil.

Abb.1 zeigt ein Ausführungsbeispiel. Auf die Schwingspule S ist eine weitere Spule S' aus Widerstandsdraht mit hohem positivem Temperaturkoeffizienten aufgebracht. Der von der Spannung U hervorgerufene Strom I läßt das Relais Re bei geringen Temperaturen anziehen. Sobald die Schwingspulentemperatur ansteigt, erhöht sich der Widerstand von S', der Strom I verringert sich, schließlich fällt das Relais ab und trennt den Lautsprecher vom Verstärker.Fig.1 shows an embodiment. On the voice coil S is a further coil S 'made of resistance wire with a high positive temperature coefficient upset. The current I caused by the voltage U leaves the relay Re at attract low temperatures. As soon as the voice coil temperature increases, increase the resistance of S 'decreases, the current I decreases, and finally the relay drops and disconnects the speaker from the amplifier.

Eine andere Ausführungsmöglichkeit zeigt Abb.2. Dem Ausgang des Verstärkers V ist eine geringe Gleichspannung, vorzugsweise mehrere hundert Millivolt, überlagert; an R entsteht ein Spannungsabfall, dessen von der Gleichspannung hervorgerufene Komponente durch einen Tiefpass ausgefiltert wird. Wegen der Temperaturabhängigkeit des ohmschen Schwingspulenwiderstandes ist diese Spannung ein Maß für die Schwingspulentemperatur. Sie kann bei zu hoher Temperatur über einen spannungsabhängigen Verstärker V' die Eingangsspannung des lautsprecherbetreibenden Verstärkers V herabsetzen.Another possible design is shown in Fig.2. The output of the amplifier A low DC voltage, preferably several hundred millivolts, is superimposed on V; at R there is a voltage drop, the one caused by the direct voltage Component is filtered out by a low pass. Because of the temperature dependence of the ohmic voice coil resistance, this voltage is a measure of the voice coil temperature. If the temperature is too high, you can use a voltage-dependent amplifier V 'die Reduce the input voltage of the loudspeaker-driving amplifier V.

Für bewegungsgegengekoppelte Lautsprecher, bei denen möglichst wenig in das Zusammenspiel zwischen Verstärker und Lautsprecher eingegriffen werden soll, ist eine Ausführung nach Abb.3 besonders geeignet.For speakers with negative motion, where as little as possible the interaction between amplifier and loudspeaker is to be interfered with, a version according to Fig. 3 is particularly suitable.

Dabei wird das thermische Verhalten des Lautsprechers elektrisch simuliert: Ein Strom I, der dem augenblicklichen Betrag der Verstärkerleistung N proportional ist und dem Wärmezustrom Ith entspricht, wird einer der Wärmekapazität der Schwingspule entsprechenden Kx Kapazität C eingeprägt. Der Widerstand R simuliert den Wärmewiderstand zwischen Schwingspule und Umgebung. An C stellt sich nunmehr eine Spannung U ein, die ein exaktes Maß für die übertemperatur g der Schwingspule ist. Diese Spannung kann dann z.B. zu einer optischen Überlastungsanzeigt benutzt werden.The thermal behavior of the loudspeaker is simulated electrically: A current I that is proportional to the instantaneous magnitude of the amplifier power N. and corresponds to the heat influx Ith, one becomes the heat capacity of the voice coil corresponding Kx capacity C impressed. The resistance R simulates the thermal resistance between the voice coil and the environment. A voltage U is now established at C, which is an exact measure for the excess temperature g of the voice coil. This tension can then be used, for example, for an optical overload indicator.

Der leistungsproportionale Strom I kann näherungsweise gewonnen werden durch Quadrieren der Verstärkerausgangsspannung und nachfolgende Umwandlung in einen Strom.The power-proportional current I can be obtained approximately by squaring the amplifier output voltage and then converting it into one Current.

Claims (4)

Patentansprüche:Patent claims: G Schaltungsanordnung zum Schutz dynamischer Lautsprecher vor Überlastung, dadurch gekennzeichnet, daß die Ausgangsleistung des zur Ansteuerung verwendeten Verstärkers in Abhängigkeit von der Temperatur der Schwingspule verringert wird.G Circuit arrangement to protect dynamic loudspeakers from overload, characterized in that the output power of the used for control Amplifier is decreased depending on the temperature of the voice coil. 2. Schaltungsanordnung gem. Anspruch 1, dadurch gekennzeichnet, daß zur Ermittlung der Schwingspulentemperatur ein temperaturabhängiges Widerstands -element in engen thermischen Kontakt mit der Schwingspule gebracht wird.2. Circuit arrangement according to Claim 1, characterized in that a temperature-dependent resistor to determine the voice coil temperature element is brought into close thermal contact with the voice coil. 3. Schaltungsanordnung gem. Anspruch 1, dadurch gekennzeichnet, daß zur Ermittlung der Schwingspulentemperatur der von dieser abhängige Schwingspulenwiderstand gemessen wird.3. Circuit arrangement according to Claim 1, characterized in that To determine the voice coil temperature, the voice coil resistance is dependent on it is measured. 4. Schaltungsanordnung gam. Anspruch 1, dadurch gekennzeichnet, daß ein elektrisches Analogmodell aus den Größen Verstärkerleistung, Wärmekapazität der Schwingspule und Wärmewiderstand von Schwingspule zur Umgebung eine Größe herleitet EESshs wird, welche der Schwingspulentemperatur entspricht.4. Circuit arrangement gam. Claim 1, characterized in that an electrical analog model from the quantities amplifier power, heat capacity the voice coil and the thermal resistance of the voice coil to the environment derives a quantity EESshs which corresponds to the voice coil temperature.
DE19742448506 1974-10-11 1974-10-11 Overload protection circuit for loudspeakers - has temperature sensor monitoring vibrating coil and controlling output power of amplifier system Pending DE2448506A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE19742448506 DE2448506A1 (en) 1974-10-11 1974-10-11 Overload protection circuit for loudspeakers - has temperature sensor monitoring vibrating coil and controlling output power of amplifier system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19742448506 DE2448506A1 (en) 1974-10-11 1974-10-11 Overload protection circuit for loudspeakers - has temperature sensor monitoring vibrating coil and controlling output power of amplifier system

Publications (1)

Publication Number Publication Date
DE2448506A1 true DE2448506A1 (en) 1976-04-22

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DE19742448506 Pending DE2448506A1 (en) 1974-10-11 1974-10-11 Overload protection circuit for loudspeakers - has temperature sensor monitoring vibrating coil and controlling output power of amplifier system

Country Status (1)

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DE (1) DE2448506A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2624252A1 (en) * 1976-05-29 1977-12-01 Rudolf Goebel OVERLOAD PROTECTION CIRCUIT FOR SPEAKER ARRANGEMENT
DE2641079A1 (en) * 1976-09-11 1978-03-16 Licentia Gmbh Loudspeaker overload monitoring system - uses diodes to indicate overload threshold of loudspeaker operation by lighting lamp
FR2455839A1 (en) * 1979-05-03 1980-11-28 Electro Audio Dynamics METHOD AND DEVICE FOR PROTECTING AN ELECTROMECHANICAL TRANSDUCER
US20120250891A1 (en) * 2011-03-28 2012-10-04 Hon Hai Precision Industry Co., Ltd. Personal listening device with self-adjusting sound volume
DE102012000499A1 (en) * 2011-06-03 2012-12-06 Mundorf Eb Gmbh Sound transducer e.g. air motion transformer for public address system used in e.g. building, has fan that is provided for producing cool air for cooling membrane portion which is arranged in air gap between pole plates

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2624252A1 (en) * 1976-05-29 1977-12-01 Rudolf Goebel OVERLOAD PROTECTION CIRCUIT FOR SPEAKER ARRANGEMENT
DE2641079A1 (en) * 1976-09-11 1978-03-16 Licentia Gmbh Loudspeaker overload monitoring system - uses diodes to indicate overload threshold of loudspeaker operation by lighting lamp
FR2455839A1 (en) * 1979-05-03 1980-11-28 Electro Audio Dynamics METHOD AND DEVICE FOR PROTECTING AN ELECTROMECHANICAL TRANSDUCER
US20120250891A1 (en) * 2011-03-28 2012-10-04 Hon Hai Precision Industry Co., Ltd. Personal listening device with self-adjusting sound volume
US8965007B2 (en) * 2011-03-28 2015-02-24 Fu Tai Hua Industry (Shenzhen) Co., Ltd. Personal listening device with self-adjusting sound volume
DE102012000499A1 (en) * 2011-06-03 2012-12-06 Mundorf Eb Gmbh Sound transducer e.g. air motion transformer for public address system used in e.g. building, has fan that is provided for producing cool air for cooling membrane portion which is arranged in air gap between pole plates
DE102012000499B4 (en) * 2011-06-03 2013-01-31 Mundorf Eb Gmbh Sound transducers, namely air-motion transformers

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