Detent mechanism for a hand-operated transducer

A detent mechanism for a manually activated transducer, particularly an angular distance transducer, in which the transducer element is movable along a predetermined path by means of a handle and which includes a sensor for scanning markings on the transducer element, said detent mechanism comprising:

• fixed first magnetic means including at least one permanent magnet with two pole shoes which form an air gap between them;
• second magnetic means spaced apart from and being movable with respect to said fixed first magnetic means for cooperating therewith such that said transducer element can be located by magnetic force in one of a plurality of definite positions;
• said second magnetic means is a rotatably mounted disc of a magnetizable material, the edge zone of which, like the portion of the two pole shoes overlapping said edge zone, has a plurality of grooves and teeth of the same size and angular displacement, running radially with respect to the rotational axis of the disc;
• at least one air gap formed between said first and second magnetic means across which said magnetic means cooperate with each other without physically contacting each other;
• said first and second magnetic means being constructed of a predetermined shape so that the configuration of the magnetic field in the air gap is such that a smaller effective air gap is created when said first and second magnetic means correspond to said one of a plurality of definite positions of the transducer element than when in other positions and the first and second magnetic means which determine the magnetic field in the air gap include adjacent, spaced grooves spaced in the direction of movement of the second magnetic means;
• and
• all of said grooves have the same width and the teeth formed between two adjacent grooves also have the same width, measured respectively in the direction of movement of the second magnetic means.