| 摘要 |
943,548. Temperature dependent resistors. A. ARGAMAKOFF. Dec. 28, 1960 [Dec. 28, 1959], No. 44456/60. Heading H1K. [Also in Division G1] In a process for producing a thermistor of very small dimensions, e.g. a sphere with a diameter of 0.0004 in. two electrodes are arranged a small distance apart, a drop of a dispersion of a semi-conductor material is deposited on the adjacent ends of the electrodes, and the said ends and the semi-conductor material thereon are subjected to the action of a flame. As shown, Fig. 1a a wire 6 of Pt-Ir or Pt is clamped in bores 4 in the jaws 3 of tongs, the wire is tautened by manipulation of a screw 2 and cut to provide two electrodes close together. A drop 7, Fig. 1c of a semi-conductor material such as oxides of U, A1, Mg, Ti, Ni, V, ground to a fine powder and suspended in a carrier liquid such as distilled water, glycerine, or a mineral or vegetable oil, is deposited on the adjacent ends of these electrodes. When the carrier liquid has evaporated, the ends of the electrodes and the semi-conductor deposit on them are placed in a flame the temperature of which is higher than the melting-point of the semi-conductor material to fuse the latter into a spherical or oval pellet. The distance between the ends of the electrodes may be determined by a micrometer 1, Fig. la, or by measuring the resistance of the molten semi-conductor between the said ends. To avoid tensions in the recrystallized semi-conductor material, the process may be accompanied by ultra-sonic vibrations. To enable oxides having high melting-points to be used, the melting-point may be reduced by the addition of a small proportion of a different oxide, e.g. of an oxide of Fe or Ti to U0 2 . Fig. 6 shows a temperature probe comprising a metal tube 15 having at one end a Ag cap 16, to the interior wall of which a thermistor 17, made by the process of the invention, is secured by means of a glass bead; leads 18, 18<SP>1</SP> from the thermistor are soldered to conductors 19, 19<SP>1</SP>, which are supported by an insulator 20. Fig. 7 shows apparatus for manufacturing such a probe; the Ag cap is kept in contact with a heating resistor 22, and an assembly of conductors, leads and a thermistor to which the glass bead has already been attached is inserted by a ratchet and pawl device 23 into the tube 15 until the glass bead contacts the heated Ag cap and is flattened against, and fused to, it. The thickness of glass in the finished probe is determined by a meter 26 whose reading depends, inter alia, upon the resistance of the glass. |
