Browse Prior Art Database

Strain Gage Crucible Weighing Device

IP.com Disclosure Number: IPCOM000048558D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Line, RJ: AUTHOR

Abstract

This discloses a simple means for assuring that metal evaporation crucibles in evaporation systems can be continuously provided with sufficient charge to assure complete evaporation and coverage of the material being coated.

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Strain Gage Crucible Weighing Device

This discloses a simple means for assuring that metal evaporation crucibles in evaporation systems can be continuously provided with sufficient charge to assure complete evaporation and coverage of the material being coated.

As shown in the figure, the crucible 10 is filled with a charge of evaporant material 11, such as aluminum. The crucible is maintained within a silica heat shield 12 surrounded by heating coils 13. The bottom 14 of the crucible 10 is provided with a pedestal 15 which passes through the bottom 16 of the silica heat shield and through the support 17 on which the heat shield and induction coils are mounted. Directly beneath the pedestal 15 and in contact therewith is a cantilever beam 18. The cantilever end 19 supports the pedestal, while the other end 20 is rigidly fixed to the support carrying both the silica heat shield and the induction coils. The beam is provided with a set of strain gages 21 and 22 for measuring the compression and tension created in the beam by the crucible bearing against the beam. As the weight of the crucible changes, as the charge evaporates, the strain in the beam also changes. Thus, the weight of the crucible is directly proportional to the change in the strain gages. Thus, the strain gages permit constant monitoring of the amount of charge in the crucible, permitting the charge to be automatically replenished whenever it falls beneath a certain level.

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