Browse Prior Art Database

Noiseless Temperature, Pressure, and Position Transducers

IP.com Disclosure Number: IPCOM000094489D
Original Publication Date: 1965-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 3 page(s) / 64K

Publishing Venue

IBM

Related People

Smeltzer, NG: AUTHOR

Abstract

The transducer devices utilize resistance wires and pools of mercury. These are sealed in enclosures and varied in position to provide electrical indications of changes in temperature, pressure and position, or combinations of such changes. Among other advantages, these devices have high current handling capabilities, rugged construction, and noiseless operation.

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Noiseless Temperature, Pressure, and Position Transducers

The transducer devices utilize resistance wires and pools of mercury. These are sealed in enclosures and varied in position to provide electrical indications of changes in temperature, pressure and position, or combinations of such changes. Among other advantages, these devices have high current handling capabilities, rugged construction, and noiseless operation.

Device A is an ordinary mercury thermometer with resistance rod 10 fitted into its core. The thermometer now becomes a contactless variable resistor. As the temperature rises, more of rod 10 is shorted out by mercury 1 1, thus changing the resistance between the two terminals. The core of the thermometer can be easily segmented to give practically any rising function needed for wide range temperature control. Rod 10 can also be made by depositing carbon or a metal film on the inside of the glass envelope.

Drawing B shows the same principle applied to a pressure sensor. The change in pressure of fluid 12 is indicated by the change in resistance between terminals 13 and 14. In order to measure the pressure profile from shock against diaphragm 15, the vent is terminated in accumulator 16.

A gravity or tilt sensor is shown in drawing C. The mercury pool 17 rides in a semicircular metallic tube 18. Contact is made from the mercury wiper to the wall of tube 18. The direction and magnitude of the tilt is determined by measuring the resistance between terminals 19, 20, and 21. This sensor is useful for servo control applications and is capable of carrying much higher currents than other devices.

A linear travel transducer is shown in drawing D. Resistance rod 22 is mounted on bearings 24 which act as seals and trap the mercury pools inside each pair of bearings. The center pair of bearings is securely attach...