Digital liquid-level sensor having at least one tunneling magnetoresistance switch

Abstract

A digital liquid-level sensor comprises a non-magnetic conduit, a floater provided outside the non-magnetic conduit and capable of axially moving along the non-magnetic conduit, and a permanent magnet fixed on the floater. The non-magnetic conduit further comprises a switch unit and an encoding unit. The switch unit comprises at least one tunneling magnetoresistance switch which is turned on or turned off under the effect of the magnetic field produced by the permanent magnet; and the encoding unit comprises at least one encoder, of which an input end receives an on/off signal from the tunneling magnetoresistance switch and outputs a digital signal indicating the position of the floater. The digital liquid-level sensor is of a small size; has low cost, low power consumption, high reliability, high sensitivity, high solution, long service life, and a good anti-interference capability; and can directly output the digital signal.