Sensor with low bulkiness for detecting determined position of a mobile

A sensor for detecting determined positions of a mobile (2) moving along a displacement axis (A), with a determined measuring stroke (C), the sensor including:

• a coder (5), connected to the mobile and having at least two coding tracks (10) extending parallel to the displacement axis, each of the tracks being formed with coding elements (11) with a physical quantity,
• detection elements (6) mounted relatively to the coding tracks and suitable for delivering a different combination of binary signals for each determined position of the mobile,
• characterized in that:
• the bulkiness of the coding tracks (10) is less than the measuring stroke of the mobile,
• the detection elements (6) are sensitive to the value of the physical quantity of the coding elements, so that each detection element occupies:
• a first binary state when the value of the physical quantity is larger than a threshold,
• a second binary state when the value of the physical quantity is less than said threshold,
• one of the two determined binary states when said detection elements are not found located opposite a coding track,
• at least one coding track (10) includes, as a coding element (11), at least one coding element of a first type (11v) which allows a detection element placed oppositely to deliver a determined binary state identical with the one delivered when said detection element is not found opposite to a coding track on the one hand, and at least one coding element of the second type (11i) which allows a detection element placed opposite to deliver a binary state different from the one delivered when said detection element is found opposite a coding element of the first type, on the other hand.