초록 ▼

To reduce the effects of disturbing electromagnetic effects on a loudspeaker of a mobile telephone, the loudspeaker is provided with a compensation coil in addition to an excitation coil. The compensation coil is series-connected with the excitation coil. However, it is dispensed of the need for pla

To reduce the effects of disturbing electromagnetic effects on a loudspeaker of a mobile telephone, the loudspeaker is provided with a compensation coil in addition to an excitation coil. The compensation coil is series-connected with the excitation coil. However, it is dispensed of the need for playing a driving role by being bonded to the permanent magnet of the loudspeaker: It is shown that the harmful effects are reduced without stopping the loudspeaker from working.

대표청구항 ▼

1. A mobile telephone loudspeaker comprising a permanent magnet and a diaphragm, the mobile telephone loudspeaker having only a first electrical coil and a second electrical coil, wherein the first electrical coil for mechanical excitation is movable with respect to the magnet and fixed to the diaph

1. A mobile telephone loudspeaker comprising a permanent magnet and a diaphragm, the mobile telephone loudspeaker having only a first electrical coil and a second electrical coil, wherein the first electrical coil for mechanical excitation is movable with respect to the magnet and fixed to the diaphragm, and wherein the second electrical coil is operably electrically coupled in series with the first coil so as to produce a counter electromotive force that is the reverse of the force produced by the first coil when they are both subjected to one and the same temporally variable electromagnetic or magnetic field, the second coil being held fixed with respect to the magnet.2. A mobile telephone loudspeaker according to claim 1, wherein the second coil is separated mechanically from the first coil by a sliding wall.3. A mobile telephone loudspeaker according to claim 1, wherein the permanent magnet produces a magnetic field B0 and includes an air gap through which the magnetic field B0 extends and wherein the second coil is placed outside the air gap.4. A mobile telephone loudspeaker according to claim 1, wherein the permanent magnet produces a magnetic field B0 and includes an air gap through which the magnetic field B0 extends and wherein the second coil is placed inside the air gap.5. A mobile telephone loudspeaker according to claim 1, wherein the second coil is fitted into the first coil, the first and second coils each have a pair of power supply strands issuing side by side, the first coil going up to an end opposite the end of the second coil to which the pair of strands of this second coil goes up to.6. A mobile telephone loudspeaker according to claim 5, wherein the strands of the two coils are bonded to the diaphragm.7. A mobile telephone loudspeaker according to claim 5, wherein the ends of the strands of the two coils are bonded to the back of the diaphragm or a peripheral structure.8. A mobile telephone loudspeaker according to claim 1, wherein the second coil is fixed to the outer periphery of the diaphragm.9. A mobile telephone loudspeaker including a permanent magnet and a diaphragm, the mobile telephone loudspeaker having only a first mechanical excitation electrical coil, mobile relative to the magnet and fixed to the diaphragm, and a second electrical coil, wherein the second coil is wound in series with the first coil so as to produce a counter electromotive force opposite to that produced by the first coil when they are both subjected to a same electromagnetic or time variable magnetic field, by the fact that the second coil is kept fixed relative to the first coil, and by the fact that the two coils are placed within the magnetic field of the magnet opposite a zone of the air-gap of this magnet in which the field undergoes a reversal of orientation depending on whether it passes through the first coil or the second coil.