| 摘要 |
1,107,046. Sorting postal mail. DE STAAT DER NEDERLANDEN, TEN DEZE VERTEGENWOORDIGD DOOR DE DIRCTEUR - GENERAAL DER POSTERIJEN, TELEGRAFIE EN TELEFONIE. 22 March, 1966 [29 April, 1965], No. 18060/65. Heading B8A. In a system for sorting or culling postal mail, the letters are marked by being faced with a metal layer d, the thickness of which is between 50 and 500 millimicrons. The presence of the mark is detected by passing through a magnetic field of 10-100 Mc/s. frequency generated in an inductance L by an oscillator G. The absorbtion of the field is measured by a wattmeter W which operates a switch W1 at a predetermined reading. In modifications, the meter W may be a voltmeter (Fig. 2, not shown), and the inductance L may have an E-shaped core (Fig. 4, not shown). The layer d may be of gold, silver, copper, zinc, or aluminium, applied by vapour deposition, either on to the letter, or on to a stamp for sticking to the letter.
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