Method of production of an electrodynamic acoustic transducer with a high density coil
A method for manufacturing an electrodynamic acoustic transducer is disclosed. The electrodynamic acoustic transducer comprises a frame and/or a housing, a membrane, at least one coil and a magnet system, wherein the coil, in a cross sectional view with a coil axis being part of the sectional plane, comprises a plurality of conductive layers formed by an electrical conductor of the coil. The electrical conductor has a rectangular cross section in said cross sectional view, wherein a longer side of the rectangular cross section is substantially perpendicular to the loop axis. According to this method, a stack of conductive layers is made from the electrical conductor by stacking of separate pieces of the electrical conductor and electrically connecting the stacked separate pieces and/or by folding of the electrical conductor.
1. A method of manufacturing an electrodynamic acoustic transducer with a frame and/or a housing, a membrane fixed to said frame or said housing, at least one coil, which is attached to the membrane and which has an electrical conductor in the shape of loops running around a coil axis in a loop section, and a magnet system being designed to generate a magnetic field transverse to the conductor in the loop section, comprising the steps of:
a) cutting the electrical conductor and a supporting structure out of a metallic foil, wherein the supporting structure is connected to the electrical conductor by a plurality of bars;
b) forming an insulation layer on the electrical conductor;
c) making a stack of conductive layers from the electrical conductor by stacking of separate pieces of the electrical conductor and electrically connecting the stacked separate pieces;
d) connecting the conductive layers to each other by means of an adhesive; and
e) removing the supporting structure and bars from the electrical conductor.
2. The method as claimed in claim 1 , characterized in that the electrical conductor is cut out of an aluminum foil in step a) and a passivation layer, which is part of the insulation layer, is formed on the electrical conductor by exposing the electrical conductor to hot distilled or de-ionized water and/or to hot vapor of distilled or de-ionized water.
3. The method as claimed in claim 1 , characterized in that the conductive layer is cut by means of a laser beam or a water beam in step a).
4. The method as claimed in claim 1 , characterized in that the separate pieces of the electrical conductor are electrically connected by means of laser welding or ultrasonic welding in step c).
5. The method as claimed in claim 1 , characterized in that first the stack of conductive layers is made from the electrical conductor without an adhesive and then an adhesive is applied to the stacked electrical conductor.
6. The method as claimed in claim 5 , characterized in that superfluous adhesive is removed by means of a laser.
7. The method as claimed in claim 1 , characterized in that the bars of adjacent conductive layers are located at different positions after step c) when viewed in a direction of the loop axis.
8. The method as claimed in claim 1 , characterized in that the coil is coated with an insulating material after step d).
9. The method as claimed in claim 1 , characterized in that tensile stress in the electrical conductor is kept below 50 N/mm 2 during steps a) to d).
10. The method as claimed in claim 1 , characterized in that an indentation is formed along a tear off line of a bar connecting the electrical conductor to a supporting structure.
11. A method of manufacturing an electrodynamic acoustic transducer with a frame and/or a housing, a membrane fixed to said frame or said housing, at least one coil, which is attached to the membrane and which has an electrical conductor in the shape of loops running around a coil axis in a loop section, and a magnet system being designed to generate a magnetic field transverse to the conductor in the loop section, comprising the steps of:
a) cutting the electrical conductor out of a metallic foil;
b) forming an insulation layer on the electrical conductor;
c) making a stack of conductive layers from the electrical conductor by folding of the electrical conductor; and
d) connecting the conductive layers to each other by means of an adhesive.
12. The method as claimed in claim 11 , characterized in that an indentation is formed along a folding line, around which the electrical conductor is to be folded, before step c).