PURPOSE: To make a device small-sized and light-weight and reproduce sound with a high fidelity by dividing a coil into two with the about center part of each yoke as the boundary to wind the coil and cancelling an external induced noise with the coil itself.
CONSTITUTION: When a magnet 3 is placed in the center position of the winding width of a coil 6, directions of the magnetic flux, which is moved by displacement of a stylus point, in the N pole part and the S pole part of the magnet are equal to each other, and therefore, electromotive forces having phases opposite to each other are generated in the coil 6 on both sides of the boundary where the magnet is divided equally into two by a face orthogonal to the axis of a stylus cantilever, and no output voltages are induced in both ends of the coil. When the winding direction of one of two equally divided and wound coils is made opposite to that of the other and the winding end of one coil and the winding start of the other are connected and output voltages are taken out from the winding start of one coil and the winding end of the other, a voltage is induced in an output terminals as the sum of output voltages of both coils. Since an external induced noise signal is cancelled by the coil itself, a shield case is unnecessary, and the device is made small-sized and light-weight, and sounds are reproduced with a high fidelity.
JPS52121302 | BOTHHSIDE ELECTROMAGNETIC STEREOPHONIC CARTRIDGE |
JPS56153900 | PICKUP CARTRIDGE |
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