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Apparatus and method for identifying metallic tokens and coins

  • US 5,573,099 A
  • Filed: 01/12/1995
  • Issued: 11/12/1996
  • Est. Priority Date: 01/14/1994
  • Status: Expired due to Fees
First Claim
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1. An apparatus for detecting the presence and identity of coins/tokens, comprising:

  • a bridge including two inductors of equal value and two impedances of equal value, one in each arm of said bridge, said bridge having a pair of input nodes and a pair of output nodes, said bridge producing a normally balanced output signal in the absence of coins/tokens in the vicinity of said bridge and an unbalanced signal in the presence of coins/tokens;

    signal generating means for applying a sequence of signals of different predetermined frequencies to said input nodes;

    phase detection means for receiving said input and output signals and detecting a predetermined phase shift between said input and output signals; and

    amplitude detection means for producing a "coin in" signal when said output signal exceeds a predetermined threshold;

    means for detecting at least two parameters of said bridge when said phase detection means detects said predetermined phase shift and comparing said parameters with corresponding predetermined parameters of known coins/tokens and identifying the coin/token when a match is detected.

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