DE102005035604B4 - Loudspeaker and method for function control of the same - Google Patents

Abstract

A loudspeaker (100) having at least one device for generating a magnetic field (10) and at least one first coil (16) which is arranged in the magnetic field (10) and coupled to a mechanical vibration system, in particular to a membrane (24) in that the mechanical vibration system is oscillatable in response to a changing electrical excitation signal applied to the first coil (16), at least one second coil (18), conductor loop or the like being motion coupled to at least a portion of the mechanical vibration system and in the Magnetic field (10) is arranged such that when a movement of the mechanical vibration system evaluable as a test signal voltage is inducible, characterized in that the tapped at the test coil (18) test signal modulated by a modulator in a range around 100 kHz and on the two-wire feed line (36) of the loudspeaker wi approx.

Description

Technical area

The invention relates to a loudspeaker according to the preamble of claim 1 and a method for functional control thereof according to the preamble of claim 4.

Loudspeakers are electroacoustic transducers, which convert electrical energy into acoustic energy, that is sound. This conversion can be done with different transducer principles. This differentiates between dynamic, electrostatic, piezoelectric and magnetic loudspeakers.

The dynamic loudspeaker makes use of the effect of the Lorenz force, which is experienced by a current-carrying conductor in a permanent magnetic field. When arranging a coil in a magnetic field and coupled to a mechanical vibration system, in particular to a membrane, the membrane is vibrated in response to the current flowing through the coil excitation current, whereby the adjacent air compresses and relaxes. By this mechanism, sound waves are generated, which propagate in the environment of the speaker.

Disturbances in the conversion of electrical to acoustic energy can severely affect the performance of a speaker or speaker system. In particular, it is possible that the membrane is damaged or pinched. It is desirable to be able to identify as quickly as possible such an impairment of the vibrational capability of the membrane. In many cases, the simple use of the human ear to function diagnosis is sufficient. The functional diagnosis becomes problematic in the case of large-scale public address systems, such as in large buildings, in airports or the like. The discovery of speaker failures is then not always possible, especially in hard to reach places.

Even in vehicles of the upper price range, the functionality of loudspeaker systems must be able to be closely monitored. A vehicle occupant can easily notice the malfunction of woofers or midrange drivers, but not that of tweeters, since the radiated power of the woofers and midrange drivers usually far exceeds that of the tweeter. The certainty that a particular speaker actually works is very important here, as it is unacceptable for a customer if the sound is degraded by the loss of a speaker.

State of the art

Function checks are known from the prior art, in which the radiation of sound is detected by microphone systems, which are arranged in front of the loudspeaker diaphragm. A disadvantage of such devices is that separate components with separate power supply are needed for diagnosis.

In addition, their feedback is often associated with certain imponderables, especially in a strong noise in the immediate vicinity of the speaker.

The US 2003/0021427 A1 discloses a speaker having at least one device for generating a magnetic field and having at least one first coil which is arranged in the magnetic field and coupled to a mechanical vibration system, in particular to a membrane such that the mechanical vibration system in response to a changing, at the first Coil adjacent electrical excitation signal is set into vibration, wherein at least a second coil, conductor loop or the like with at least a part of the mechanical vibration system is coupled and arranged in the magnetic field such that upon movement of the mechanical vibration system can be evaluated as a test signal voltage in her inducible ,

Presentation of the invention; Task, solution, benefits

It is an object of the present invention to provide a speaker in which a functional diagnosis can be carried out with simple means and leads to a reliable feedback of the system.

This object is achieved by means of a loudspeaker with the features mentioned in claim 1 or by means of a method with the features mentioned in claim 4.

Due to the fact that at least one second coil, conductor loop or the like is motion-coupled to at least part of the mechanical vibration system and arranged in the magnetic field such that a voltage that can be evaluated as a test signal can be induced in it during movement of the mechanical vibration system Microphone principle based diagnosis possible. It is also advantageous that the speaker is present together with the diagnostic element as a compact component.

In a preferred embodiment of the invention it is provided that the speaker is an electrodynamic. A loudspeaker with a permanent magnet with a pole core and with a voice coil carrier comprising the pole core, wherein the windings of the first and the second coil are arranged on the voice coil bobbin. Such an arrangement results from slight modifications of conventional electrodynamic loudspeakers of the prior art.

For the transmission of the test signal several configurations are possible. In the simplest configuration, it is provided that the excitation signal and the test signal are transmitted on separate power supply lines of the loudspeaker. For this purpose, a speaker must have three or four ports.

Alternatively, it is possible for the excitation signal and the test signal to be transmitted on the same power supply lines of the loudspeaker. This has the advantage that no additional strands need be provided on the speaker body, but here the evaluation of the test signal is generally not feasible without additional signal modulation. Such a modulation may be, for example, that a sinusoidal signal is converted into a test signal essentially corresponding to a square wave voltage using a Schmitt trigger and a flip-flop. In order to prevent a sound excitation signal for the diaphragm from arising in the audible range, the method for controlling the operation of the loudspeaker is carried out using an excitation signal at a sufficiently high frequency, for example 40 kHz.

Further preferred embodiments of the invention will become apparent from the remaining, mentioned in the dependent claims characteristics.

Brief description of the drawings

The invention will be explained in more detail in an embodiment with reference to the accompanying drawings. In schematic representations:

1 a section through a loudspeaker according to the invention;

2 a switching arrangement with modulation of the test signal and

3 a switching arrangement with digital transmission of the test signal.

Best way to carry out the invention

In a total in the 1 to 3 With 100 designated speaker forms in which by a permanent magnet 10 a yoke 12 and a pole plate 14 formed magnetic system from an air gap, in which a voice coil bobbin 32 is suspended. On the voice coil bobbin 32 are an excitation coil 16 and a test coil according to the invention 18 arranged. One to the voice coil bobbin 32 coupled membrane 24 , which together with a centering membrane 20 and a dust cover designed as a dome 22 forms a mechanical vibration system, transmits vibrations of the voice coil bobbin 32 into the air and converts them into audible sound waves. On a loudspeaker basket 28 , which takes over the task, the voice coil bobbin 32 and the magnet system 10 take up, are Zuführungslitzen 26 . 30 arranged, which as connections for the exciting coil 16 and the test coil 18 serve. The exciter coil 16 gets through the feedlines 30 supplied with an excitation current. Through the flow of current an alternating magnetic field is built up, which moves the membrane forward and backward. In this way, current vibrations are converted into air vibrations and emitted as sound waves. When the membrane 24 moved freely, is a evaluable as a test signal voltage in the test coil 18 which, given a suitable potential reference, acts as a test signal on the feed strand 26 is applied. If the membrane vibration is impaired, no test signal is measured or the test signal is at a lower level than with a functional membrane. By evaluation of the test signal at the feed strand 26 Thus, a simple diagnosis of the speaker function is possible.

2 shows a switching arrangement in which the on the test coil 18 tapped test signal by a modulator 34 (eg, in a range around 100 kHz) and modulated onto the two-wire feed line 36 of the speaker 100 is placed. The resulting in a functional membrane movement high-frequency signal can thus be easily evaluated. A the speaker 100 upstream bandpass filter 38 , which transmits a frequency range from 0 to 30 kHz and from a power amplifier 40 (12 V / 240 V), prevents the transmission of the high-frequency signal to the exciter coil 16 and thus also the generation of unwanted movements of the speaker diaphragm 24 ,

3 shows a switching arrangement in which the on the test coil 18 tapped test signal via a WLAN Bluetooth module 42 is transmitted digitally with an upstream A / D converter to a collecting station, not shown. Alternatively, not the test signal itself is transmitted, but information derived therefrom, which merely provides information about the function and the identifier of the loudspeaker. For example, this signal includes only a single bit indicating the proper functioning of the loudspeaker, as well as a name or location of the loudspeaker. On a return of the test signal on the supply line 36 of the speaker 100 can be omitted in this embodiment.

LIST OF REFERENCE NUMBERS

100

speaker

10

Permanent magnet with pole core

12

yoke

14

pole plate

16

excitation coil

18

test coil

20

centering diaphragm

22

Dust / cap

24

membrane

26

Feed wire for test coil

28

Loudspeaker frame

30

Feeding strands for exciting coil

32

Voice coil former

34

modulator

36

feed pipe

38

Bandpass filter

40

power amplifier

42

WLAN Bluetooth module with upstream A / D converter

Claims (6)

Speaker ( 100 ) with at least one device for generating a magnetic field ( 10 ) and at least one first coil ( 16 ), which in the magnetic field ( 10 ) and to a mechanical vibration system, in particular to a membrane ( 24 ) is coupled in such a way that the mechanical vibration system in response to a changing, on the first coil ( 16 ) applied electrical excitation signal is oscillatable, wherein at least one second coil ( 18 ), Conductor loop or the like with at least a part of the mechanical vibration system and coupled in the magnetic field ( 10 ) is arranged such that upon movement of the mechanical vibration system, a testable as a test signal voltage is inducible in it, characterized in that the at the test coil ( 18 ) modulated test signal by a modulator in a range around 100 kHz and on the two-wire feed line ( 36 ) of the loudspeaker. Loudspeaker according to claim 1, characterized in that the loudspeaker ( 100 ) an electrodynamic loudspeaker with a permanent magnet ( 10 ) with a pole core and a voice coil carrier comprising the pole core ( 32 ), wherein the windings of the first and the second coil ( 16 . 18 ) on the voice coil former ( 32 ) are arranged. Loudspeaker according to one of the preceding claims, characterized in that the loudspeaker ( 100 ) an active speaker with an amplifier ( 40 ) for feeding the first coil ( 16 ). Method for checking the function of a loudspeaker ( 100 ), where the speaker ( 100 ) at least one device for generating a magnetic field ( 10 ) and at least one first coil ( 16 ), which are arranged in the magnetic field and to a mechanical vibration system, in particular to a membrane ( 24 ) is coupled in such a way that the mechanical vibration system in response to a changing, on the first coil ( 16 ) is applied, wherein a test signal is evaluated, which results from the fact that during the movement of the mechanical vibration system, a voltage in at least one second coil ( 10 ), Conductor loop or the like ( 18 ), the second coil ( 18 ), Conductor loop or the like with at least a part of the mechanical vibration system is coupled in motion and arranged in the magnetic field, characterized in that on the test coil ( 18 ) modulated test signal by a modulator in a range around 100 kHz and on the two-wire feed line ( 36 ) of the loudspeaker. A method according to claim 4, characterized in that the function control is carried out in a test phase. Method according to one of claims 4 or 5, characterized in that at least one inaudible frequency component is evaluated in the test signal.

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