Improvements in and relating to sensors.

摘要

The sensor is adapted for sensing relative displacement of a relatively movable body and is advantageously sensitive to displacements of the order of or less than 1 mm or is sensitive to displacements caused by forces or pressures or changes in force or pressure of the order of or less than 10 millibar. The sensor (1) comprises an elongate member (16) longitudinally slidable in a housing (33) in dependence on the relative displacement of the body (10). The elongate member has a longitudinal engagement surface provided for example with teeth (18) which engage with teeth provided on the periphery of a rotatable member (19) mounted for rotation in the housing. The rotatable member is associated with an arm (21) which may carry an indicator (23) at its end which is movable with rotation of the rotatable member over a scale (22). The assembly comprising the elongate member, the rotatable member and the arm is arranged to be substantially balanced about the axis of the rotatable member with a slight resultant force on the elongate member tending to move it in the direction of the body, the resultant force being less than the force on the body causing the displacement to be sensed by the sensor. For this purpose, the assembly may include a spring (25) acting for example on the rotatable member about its axis for counterbalancing any imbalance in the moments of the elongate member and arm about the axis of the rotatable member.