Texas Instruments Corporation

John E Brennan

Bryan J Dague

Richard A Stander

A pressure responsive electric switch (10) is shown having an improved flexible diaphragm (28) to extend the useful life of the switch particularly when used with fluid media of a corrosive nature. The flexible diaphragm (28) comprises a base layer (28a) of resin having excellent mechanical properties over a wide range of temperature and a first level of fold endurance capability covered on one or both face surfaces with a protective layer (28b) of resin having excellent corrosion resistance capability and a second level of fold endurance capability at least as great as the first level. In a second embodiment, the flexible diaphragm is composed of biaxially oriented polyphenylene sulfide which can be used without additional protective layers.

Pressure switch with biaxially oriented thermoplastic diaphragm

Transponder �A,B! formed of a bottom-closed elongate tubular enclosure �12! having a mouth �12'! at an upper end and circuit-receiving space within the enclosure for fully receiving an electronic transponder circuit assembly �15!. A cap �14,114! closes the mouth, the enclosure and cap each being of tough synthetic resin material which will not be damaged by being dropped and is intrinsically capable of absorbing shock to a substantial degree when so dropped. The circuit assembly is completely immersed in silicone oil or gel cushioning medium �16! so that it completely surrounds the circuit assembly in all directions, the cushioning medium providing absorption of impact energy. The silicone cushioning medium when within the closure has its fluid level extending above the seal and above an upper end �15'! of the circuit assembly. The cap is hermetically joined to the enclosure by ultrasonic welding. The transponder repeatedly survives a 2-meter drop test without failure of the circuit assembly. Method for assembling the transponder involves introducing silicone fluid is introduced into the enclosure using a dispensing needle having a tip placed at a closed bottom of the enclosure in order to minimize the creation of air pockets in the silicone, and the predetermined volume of silicone fluid so dispensed is slightly greater than volume available for the silicone fluid after introduction of the circuit assembly.

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North Attleboro, MA, United States of America

John E Brennan