Headset and earphone

0001The present invention relates to a headset as well as an earphone.

0002Known headsets as well as known earphones or headphones are subject to noise in particular in airplanes which can result from the magnetic fields produced by the onboard power supply. Therefore, the headsets and earphones or headphones are prone to low frequent inductive radiation.

0003In <patcit id="pcit0001" dnum="US6587568B1"><text>US 6 587 568 B1</text></patcit>, a hearing aid device is disclosed comprising a magnetic interference sensor for measuring a magnetic interference field and a signal processing unit, wherein in order to suppress magnetic interference the system is re-clocked, a set of filter coefficients is derived, and filtering with the derived coefficients is carried out.

0004In <patcit id="pcit0002" dnum="EP1587342A2"><text>EP 1 587 342 A2</text></patcit> a headphone with active noise control reduction is disclosed, although nothing is disclosed about magnetic interference control.

0005It is therefore an object of the invention to provide a headset as well as an earphone which are less prone to inductively produced radiation.

0006This object is solved by a headset or earphone according to claim 1.

0007Therefore, a headset or earphone is provided which comprises an electro-acoustic reproduction transducer having an oscillator coil, an amplifier coupled to the electro-acoustic transducer, a magnetic interference sensor for measuring a magnetic interference field, a correction unit coupled to the magnetic interference sensor for analyzing an output of the magnetic interference sensor and for producing a compensation signal. The headset or earphone furthermore comprises an adding unit for adding the compensation signal to an input signal and for outputting the result thereof to the amplifier.

0008According to an aspect of the invention, the magnetic interference sensor is arranged adjacent or in close proximity to the electro-acoustic reproduction transducer. This is advantageous as in this case, the magnetic interference sensor will exactly detect the magnetic interference that is detected by the electro-acoustic reproduction transducer.

0009According to an aspect of the invention, the magnetic interference field sensor is arranged in the same axis as the oscillator coil of the electro-acoustic reproduction transducer. This is also advantageous as the magnetic interference field sensor will detect approximately the same magnetic interference as the electro-acoustic reproduction transducer.

0010The invention also relates to a headset or earphone comprising an active noise reduction unit, an electro-acoustic reproduction transducer having an oscillator coil, an amplifier coupled to the electro-acoustic reproduction transducer, a magnetic interference sensor for measuring a magnetic interference field, a correction unit coupled to the magnetic interference sensor for analyzing an output of the magnetic interference sensor and for producing a compensation signal and an adding unit for adding the compensation signal, an output of the active noise reduction unit to an input signal and for outputting a result to the amplifier.

0011The present invention relates to the idea that instead of shielding a headset or an earphone from inductive noise radiation or magnetic interference fields, a sensor is provided for sensing the inductive noise signal produced by the inductive radiation or the magnetic interference fields. The output of the sensor is processed and added to the audio input signal for the earphone or headset. The output signal of the signal processing unit is added to the input signal such that a noise signal with a reduced noise level is achieved.

0012According to the invention the above described inductive noise compensation can also be used for other electro-acoustic devices where a magnetic interference field or noise field can act upon the moving or oscillator coil.

0013Preferably, the sensor is arranged close to the electro-acoustic transducer and in particular to the oscillator coil.

0014Advantages and further aspects of the embodiments will now be described in more detail with reference to the figure. <dl id="dl0001"><dt>Fig. 1</dt><dd>shows a schematic block diagram of an earphone or headset according to a first embodiment, and</dd><dt>Fig. 2</dt><dd>shows a schematic block diagram of an earphone or headset according to a second embodiment.</dd></dl>

0015<figref idref="f0001">Fig. 1</figref> shows a schematic block diagram of an earphone or headset according to a first embodiment of the invention. The headset or earphone comprises an electro-acoustic reproduction transducer 10 connected to an amplifier 20 and a magnetic interference sensor 50 coupled to a correction unit 40. The headset or earphone also comprises an adding unit 30 for adding the compensation signal from the correction unit 40 to an input signal IN of the headset or earphone. The electro-acoustic transducer 10 comprises an oscillator coil 11. The amplifier unit 20 comprises an internal resistor Ri. The magnetic interference sensor 50 comprises a coil 51 for detecting a magnetic interference field. The output of the magnetic interference sensor 50 is coupled to the correction unit 40, which generates a compensation signal based on the output signal of the sensor 50. The compensation signal is added to the input signal IN by means of the adding unit 30.

0016The present invention relates to the realization that the oscillator coil in the electro-acoustic transducer together with the electrical output resistance Ri of the amplifier 50 form a closed conductor loop. Any magnetic field in the vicinity of the closed conductor loop will induce an electrical current into it. This current can act upon the oscillator coil and can produce a movement of the oscillator coil which will correspond to an unwanted noise signal.

0017With the magnetic interference field sensor according to the invention it is possible to detect the presence of a magnetic interference field. The output of the sensor serves as input to the correction unit 40, which will produce a compensation signal for compensating the effect of the noise signal introduced by the magnetic interference noise. Preferably the compensation signal is produced such that after adding that to the noise signal (i. e. the input signal), the resulting signal will be zero such that the noise signal due to the magnetic interference is significantly reduced.

0018The sensor according to the invention should be arranged such that it can detect the magnetic interference field as it is experienced by the electrical acoustic reproduction transducer (the oscillator coil). Therefore, the sensor should be arranged in close proximity or adjacent to the oscillator coil. Preferably the magnetic interference should be arranged at the same axis as the oscillator coil.

0019<figref idref="f0001">Fig. 2</figref> shows a schematic block diagram of an earphone or headset according to second embodiment. The earphone or headset according to the second embodiment substantially corresponds to the earphone or headset according to a first embodiment. Therefore, it comprises an adding unit 30, an amplifier 20, an electro-acoustic reproduction transducer 10, a magnetic interference sensor 50, and a correction unit 40. In addition, the earphone or headset comprises a microphone 70 for detecting noise signals and an active noise reduction unit 60 for performing an active noise reduction or an active noise cancelling based on the output signal of the microphone. The active noise reduction unit 60 generates a noise compensation signal which is forwarded to the adding unit 30 such that it is combined with the compensation signal from the correction unit 40 and the input signal IN. The output of the adding unit is forwarded to the amplifier 20 and reproduced by the electro-acoustic transducer 10.

0020The basic idea of the invention is in particular advantageous for earphones or headsets with an ANR (active noise reduction) as this active noise reduction can be so good that the noise introduced by the magnetic interference can be audible. If the active noise reduction is not of such a good quality, the noise introduced by the magnetic interference field may not be audible. The same applies to earphones with an active noise reduction capability.

0021According to a third embodiment, the sensor 50 can be arranged on the housing of the electrical transducer or alternatively it can be arranged on a circuit board fixedly connected to the housing of the transducer. Alternatively, the sensor 50 can be arranged on the side of the transducer which is towards the ear of the user. As mentioned above, the arrangement of the sensor 50 should be such that it is acted upon by the same magnetic field as the oscillator coil.