Device for measuring the position of the plunger in a glassware forming machine

A sensor in a position measurement device for employment with a machine having a mounting base, a movable operating member, a casing mounted to the mounting base and an actuation member mounted to the movable operating member and disposed adjacent to the casing to undergo movement relative thereto with the movable operating member, said sensor for providing continuous measurement of the position of the actuation member as the actuation member moves relative to the casing and thereby of the position of the movable operating member, said sensor comprising:

• (a) a first part including a resonance circuitry formed of a coil and a capacitor, said coil supported on the casing, said capacitor having first, second and third capacitor elements, said first and second capacitor elements supported on the casing in a stationary relation to one another, said third capacitor element supported on the actuation member and being movable therewith relative said first and second capacitor elements such that said resonance circuitry has a resonance frequency which is variable in proportion to the change of capacitance of said capacitor in response to the change of the position of the actuation member relative to the casing and thereby of said third capacitor element relative to said first and second capacitor elements caused by movement of the movable operating member of the machine;
• and
• (b) a second part provided on the mounting base such that said second part is galvanically isolated and mechanically separated from said first part, said second part including a coupling coil supported on the mounting base adjacent to and inductively coupled with said coil of said resonance circuitry of said first part so as to produce an output oscillation frequency proportional to said resonance frequency of said resonance circuitry.