Magnetic sensor with laminated field concentrating flux bar

A sensor apparatus for sensing movement in a first direction of an object adjacent the apparatus and having alternating zones of different magnetic conductivity, the sensor apparatus comprising:

• cylindrical magnetic field generating means for generating a magnetic field, the magnetic field generating means having a longitudinal axis and a substantially planar first surface side facing said object;
• magnetic field sensor element means, mounted directly on said first surface side and on opposite sides of said longitudinal axis with respect to said first direction and having a first width transverse said first direction and a first length in said first direction, for sensing the magnetic field in relation to said object;
• and
• flux guide means directly connected to said magnetic field sensor element means for concentrating a portion of the magnetic field into passage through the sensor element, the guide means having i) said first width, ii) alternating layers of ferromagnetic material and non-magnetic material along said first direction, each ferromagnetic material layer having said first length and iii) an overall length in said first direction corresponding to the diameter of said magnetic field generating means.

A transducer for producing electrical pulse signals in response to movement in a first direction relative thereto of an object having alternating zones of different magnetic conductivity, the transducer comprising:

• cylindrical magnetic field generating means for generating a magnetic field, the field generating means having a longitudinal axis perpendicular said first direction and a continuous planar end surface facing the object, the end surface having a first diameter;
• first and second magnetic field sensor means mounted directly on the end surface of the field generating means, the first sensor means being offset from said longitudinal axis on a first side of the end in said first direction of the movement of the object, and the second sensor means being offset from said longitudinal axis on a second side of the end opposite the first side, and each of the sensor means having i) a positive and negative circuit leg sensitive to the magnetic field, ii) a first length in said first direction, and iii) a first width transverse said first direction;
• and
• magnetic field guide means for concentrating a portion of the magnetic field through each of the positive and negative circuit legs, the guide means being directly connected layered magnetic material and non-magnetic material and having substantially said first width and an overall length substantially corresponding to said diameter, the magnetic material layers each having said first length.