EP0040948A1 — Method of making an electro dynamic transducer

Claim 1

Independent Claim 313 words

A method of making an electro-dynamic transducer having a diaphragm (13) connected to a coil (15) which is axially movable in an annular slit (6) between two pole shoes (3, 4) which are connected to their respective poles of a magnet (5), characterized by making the transducer from two parts, which when fitted together provide for a predetermined number of integral acoustic resistors in the form of pins inserted into holes: a) a magnet part which is made by attaching the pole shoe/magnet unit (3, 4, 5) which in a previous step known per se is provided with a central hole, to a guide pin (2) forming an integral part of a casing unit (1), b) a coil-diaphragm part which is made by fixing, e.g. by ultra sound welding, glutination or the like, in a first station a heat deformable, plane diaphragm material to one side of a carrier ring (10) whose inwardly facing, cylindrical face (11) has the same diameter as the outwardly facing, cylindrical face (12) of the outer pole shoe (3), applying in a second station a heat activatable glue on the diaphragm side facing towards the carrier ring (10), or on the coil and in a region which is coaxial with the carrier ring has the same diameter as the annular slit (6) between the two pole shoes (3, 4), and directing in a third station a heat emitting diaphragm forming tool coaxially towards the diaphragm side facing away from the carrier ring (10), simultaneously with the diaphragm being pressed into engagement with the forming tool by means of a source of pressurized air supplied on the opposite side of the diaphragm, and the coil (15) being pressed against said region, said coil (15) being fitted on a guide templet (21) which has an annular engagement face (22) of the same outer diameter as the outer pole shoe (3).

Claim 2

Independent Claim 313 words

A method of making an electro-dynamic transducer having a diaphragm (13) connected to a coil (15) which is axially movable in an annular slit (6) between two pole shoes (3, 4) which are connected to their respective poles of a magnet (5), characterized by making the transducer from two parts, which when fitted together provide for a predetermined number of integral acoustic resistors in the form of pins inserted into holes: a) a magnet part which is made by attaching the pole shoe/magnet unit (3, 4, 5) which in a previous step known per se is provided with a central hole, to a guide pin (2) forming an integral part of a casing unit (1), b) a coil-diaphragm part which is made by fixing, e.g. by ultra sound welding, glutination or the like, in a first station a heat deformable, plane diaphragm material to one side of a carrier ring (10) whose inwardly facing, cylindrical face (11) has the same diameter as the outwardly facing, cylindrical face (12) of the outer pole shoe (3), applying in a second station a heat activatable glue on the diaphragm side facing towards the carrier ring (10), or on the coil and in a region which is coaxial with the carrier ring has the same diameter as the annular slit (6) between the two pole shoes (3, 4), and directing in a third station a heat emitting diaphragm forming tool coaxially towards the diaphragm side facing away from the carrier ring (10), simultaneously with the diaphragm being pressed into engagement with the forming tool by means of a source of pressurized air supplied on the opposite side of the diaphragm, and the coil (15) being pressed against said region, said coil (15) being fitted on a guide templet (21) which has an annular engagement face (22) of the same outer diameter as the outer pole shoe (3).

Claim 3

Dependent Claim 79 words

Method according to claim 1, characterized in this that in a step prior to the third station for making the coil-diaphragm part, the coil (15) fitted on the guide templet (21) is terminated by connecting the coil leads (16) to coil terminals (8) also being fitted to the guide templet (21), whereupon in the third station the coil terminals (8) are secured to the carrier ring (10) by pressing their ends into apertures (28) in the carrier ring (10).

Claim 4

Dependent Claim 66 words

Method according to claim 2, characterized in this that the connection between the coil leads (16) and the coil terminals (8) is facilitated by fitting the coil terminals (8) to a displacable part (29) of the guide templet (21), which part may be temporarily displaced to allow dip soldering of the connection prior to securing the terminals (8) to the carrier ring in the third station.

Claim 5

Dependent Claim 54 words

Electro-dynamic transducer made in accordance with claims 1, 2 or 3, characterized in this that the carrier (10) has secured coil terminals (8) which protrude on the side facing away from the diaphragm (13) and a groove (23) for the coil ends (16) between each terminal (8) and the inwardly facing, annular face (11).

Claim 6

Dependent Claim 56 words

Transducer according to claim 4, characterized in this that the acoustic resistors are constituted by pin shaped projections (9) being integral part(s) of the casing unit (1) and having substantially circular cross section, which are adapted to be closely fitted (inscribed) within a corresponding number of square cross sectional holes (17) in the carrier ring (10).

Method of making an electro dynamic transducer

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