A digital depth gauge apparatus is provided for measuring a depth of a hole in, or surface of, an object using a variable-resistance sensor. The apparatus comprises an elongated reader body that includes a distal end and a proximal end having a longitudinal axis and a user interface including a display...http://www.google.fr/patents/US7895767?utm_source=gb-gplus-shareBrevet US7895767 - Electronic depth gauge with variable electrical resistance sensing
Electronic depth gauge with variable electrical resistance sensing
