Echlin, Inc.

Carroll D Sloan

John E Opie

John R Wiegand, Deceased

A read head for a Wiegand wire has an E-core with a pick-up coil for the '1' bit wound on one outer leg and a separate pick-up coil for the '0' bit wound on a second outer leg. The E-core is composed of a relatively thin ferromagnetic E-laminae spaced from a relatively thick E-laminae. Between thin and thick laminae in each leg there is an appropriately polarized magnet. The result is to establish a first field across the face of the read head between the center leg and a first outer leg. This first field reads the one bits. Similarly, a second field between the center leg and the other outer leg reads the zero bits. Each one bit wire is on one side of the code strip and each zero bit wire is on the other side of the code strip so that the one bit and zero bit wires are passed respectively across the first and second reading fields provided by the read head. Saturation of the thin E-laminae and non-saturation of the thick E-laminae assures that the field configuration is appropriate to set and switch the Wiegand wires.

Read head for Wiegand wire

A read head for a Wiegand Wire has a low reluctance core on which a pick-up coil is wound. The Wiegand Wires are passed over a face of the core and coil and switch state directly over the core and coil so that the change in the magnetic field is coupled to the coil to produce an output pulse. Outboard of the direction in which the Wiegand Wires travels are first and second magnets that generate the field. In contact with these magnets and bridging both sides of the coil are first and second magnetic shunt members which control and determine the shape of the field. A first magnetic shunt member has a relatively narrow bridge portion which saturates under the field involved and thus there is a large leakage field adjacent to the face of the read head for the purpose of appropriately setting the Wiegand Wires. The second shunt has a much larger bridge portion so that there is much less leakage flux. However this smaller leakage flux is in the opposite direction from the leakage flux from the first shunt. The leakage flux from the second shunt serves to establish, accordingly, a negative field having a magnitude sufficient to reset the Wiegand Wire. In this fashion the two magnets and two shunts determine the strength and configuration of the field.

Growing community of inventors

Ambler, PA, United States of America

Carroll D Sloan