Rotational angle sensor

A rotational angle sensor device, comprising:

• a casing;
• rotatable shaft means rotatably supported by said casing, the angular position of said rotatable shaft means being responsive to an angular displacement of an external object;
• permanent magnet means firmly mounted inside said casing for providing a magnetic field;
• at least one core means disposed adjacent to said permanent magnet means, said at least one core means being firmly mounted inside said casing, said at least one core means including a thin sheet of magnetically soft material;
• electrical coil means including at least one coil wound about said at least one core means;
• a ferromagnetic member secured to said rotatable shaft means and movable therewith, said ferromagnetic member being capable of angular movement in a spaced relationship with respect to said at least one core means and to said permanent magnetic means;
• means for applying an electrical signal to a first terminal of said coil to saturate said core means magnetically;
• and
• means for producing an angular position output signal indicative of the rotation of said rotatable shaft means based on the amount of time between application of said electrical signal and saturation of said core means.