PROCEDURE AND APPARATUS FOR THE INVESTIGATION OF MENTIONS FOR AUTHENTICITY

摘要

1452740 Testing coins MARS Inc 8 Oct 1973 [12 Oct 1972] 47161/72 Heading G4V A method of testing coins comprises examining a coin, producing an electrical signal having a value indicative of a characteristic of the coin and comparing the value with a value stored in a programmable memory. In the embodiment shown coins of three denominations (5c, 10c and 25c) are examined at high frequency inductive sensing stations 511, 514, the effect of the coin on the frequency of associated oscillators 521, 524 being measured, and low frequency inductive sensing station 512 associated with a bridge circuit 522. The circuit 522 will produce one pulse on one of three denomination associated output lines if the coin is authentic, Specification 1397087 is referred to in this respect. The outputs of oscillators are alternately gated into a counter 580 under the control of timing pulse generator 540 and the count level is compared by comparator 560 with the output of memory 550. Three-bit address registers 551, 554 associated with oscillators 521, 524 respectively have their outputs alternately gated into memory 550, depending on which oscillator is being sampled, to select the memory address and hence determine its output. Whenever the count in counter 580 exceeds the output of memory 550 the appropriate address register is counted up one to select the next address of the memory and the maximum frequency shift caused by the coin (and hence an indication of its authenticity and denomination) can be determined from the output of the address register Figs. 6A, 6B (not shown). A logic unit 590 receives the outputs from address registers 551, 554 and low frequency examination circuit 522 and produces signals indicative of the authenticity and value of the coin if the results of each examination are positive, relate to the same denomination of coin and have been received in the correct order. A similar embodiment Fig. 7, (not shown) includes means for modifying the results of the high frequency examinations in dependence on the results when no coin is present in order to compensate for changes in the operating parameters, Specification 1443934 is referred to in this respect. Another embodiment Figs. 2 to 4, (not shown) includes a circuit (301) for detecting the peak frequency shift of the oscillator (370), this peak value being compared with the values stored in memory (250). The circuit (301) includes a counter (320) connected to sample the output of oscillator (370) during timed testing periods, the content of the counter being transferred into a register (340) if at the end of each period the count level exceeds the content of the register. The memories may be programmed by the application of a control signal and passing a set of standard coins through the apparatus.