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Title: Thermoelectric metal sorter
Claims: We claim: 1. A metal sorter comprising a pair of electrically conductive probes of identical metallic composition, means for producing a temperature difference between said probes, sensing means for providing a first electrical signal indicative of said temperature difference, and detection means for detecting a second electrical signal indicative of the potential difference between said probes when said probes are contacted, in operation, with a metallic specimen to be identified and providing an indication of the ratio of said signals, wherein said means for providing said temperature difference comprises a thermoelectric heat pump effective to pump heat between a pair of opposed faces thereof in response to electrical power supplied thereto, said heat pump being mounted between said probes such that each of said probes is maintained in thermal contact with a respective one of said opposed faces, and means responsive to said first signal for supplying electrical power to said heat pump so as to maintain said first signal substantially at a predetermined operating level. 2. A sorter according to claim 1 which is encased in a housing of electrically insulating material of low thermal conductivity, wherein said probes comprise a pair of elongate bodies mounted with their longitudinal axes parallel to one another within said housing such that only a small portion adjacent to a longitudinal extremity of each probe protrudes from said housing, said probes being slideable longitudinally over a short distance independently of one another, and wherein resilient means are provided to urge each probe towards its position of maximum protrusion from said housing. 3. A sorter according to claim 2 wherein said thermoelectric heat pump is mounted to fixed relation to one of said probes and slideable therewith relative to said other probe and to said housing, and including lateral urging means for resiliently urging said probes towards one another in a direction normal to their longitudinal axes, thereby maintaining thermal contact between said heat pump and said probes throughout sliding displacement thereof. 4. A sorter according to claim 3 wherein each probe is provided with a longitudinal bore terminating close to said extremity, and wherein said sensing means includes a thermocouple contained in said bore of each probe and in thermal contact with said extremity thereof. 5. A sorter according to claim 4 wherein said detection means comprises a potentiometric bridge circuit for comparing said first and second signals. 6. A sorter according to claim 4 wherein said detection means comprises first and second amplifier means for amplifying said first and second signals respectively, a dividing circuit responsive to the amplified first and second signals to produce a third electrical signal indicative of the ratio of said amplified signals, and a meter for displaying said third signal. 7. A sorter according to claim 6 wherein said meter provides a digital display of said third signal. 8. A sorter according to claim 7 including switching means and a timer, said switching means being effective to energize said timer in response to a predetermined displacement of both of said probes from their respective maximum protrusion positions, and said timer being connected to said meter and effective upon energizing thereof to provide sequentially an enabling signal to cause said meter to display an indication of said third signal and a holding signal to prevent any change in the displayed indication with changes in said third signal. 9. A sorter according to claim 8 wherein said enabling and holding signals are maintained throughout the period of energization of said timer and for a predetermined duration after de-energization of said timer unless said timer is re-energized prior to said duration. Other info: Inventors: Rowsey, James H. (Huntington, WV, US) Snavely, Charles E. (Proctorville, OH, US) Luce, Clayton D. (Huntington, WV, US) Application Number: 916703 Filing Date: 1978-06-19 Publication_date: 1979-05-29 Assignee: Huntington Alloys, Inc. (Huntington, WV) Primary Class(es): 324/451 374/15 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Woodiel, Donald O. Assistant Examiner: Attorney: Messulam; Lewis, MacQueen; Ewan C. |
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