GB1272671A - Coin acceptor having resistivity and permeability detector - Google Patents

Abstract

1,272,671. Bridge-network coin testers. VENDO CO. 23 April, 1969 [8 Jan., 1969], No. 20652/69. Heading G4V. A coin tester comprises a bridge network which assumes a validity-indicating condition when a valid coin passes through a test station and delay means having a predetermined signal output condition assumed after a time period following sensing of a coin passing through the test station, the arrangement being such that a coin is accepted if the network is in its validityindicating condition when the delay means assumes its predetermined output condition. In the embodiment shown an elliptical coil 16 is situated either side of passageway 14, Fig. 2, each with its major axis along the length of the passageway. A light source 24 and a light detector (26), Fig. 3 (not shown), are vertically adjustable in slots 22, their positions relative to coils 16 being adjusted in dependence of the diameter of the coins to be tested so that the test may be completed while a respective coin is approximately centrally positioned relative to the coils; typically a test period is 4 m sec. If a coin is acceptable an accept electromagnet 36, Fig. 1 and Fig. 4 (not shown), is actuated to withdraw deflector 30, Fig. 2, and allow the coin to enter accept path 34, otherwise coins follow reject path 32. Coils 16 form one arm of a bridge circuit 42, Fig. 1, aligned to be in a balanced condition at terminals 62, 64 when an acceptable coin passes between the coils. As shown. a further bridge is formed by the provision of arms 120, 122 to allow, for example, testing of coins of the same denomination but different composition. In this case a balanced condition is obtained at outputs 62, 124. When light from soucre 24 is obturated, detector 26 becomes non-conductive as consequently does a transistor 92, the latter being held in this state for the test period, e.g. 4 m sec., by capacitor 94 and resistor 90. With change of state of transistor 92 a positive pulse is delivered to the gate of silicon controlled rectifier 84. The period of gating of SCR 84 depends on the cessation or otherwise of a pulse train (146), Fig. 6 (not shown), from differential amplifier 70. Cessation occurs when bridge 42 is balanced, i.e. on valid coin insertion, and in consequence a transistor 80 remains in continuous conduction as does SCR 84. When transistor 92 becomes condutive at the end of the test period, an amplifier 100 is turned off and an accept transistor 114 is placed in conduction. If at this instance SCR 84 is also in conduction, i.e. the coin is valid, accept electromagnet 36 is actuated. The apparatus may comprise a plurality of channels 14, Fig. 2, each for a different denomination and each comprising units such as 134, 136, Fig. 1, comprising the same network as shown in Fig. 1, but sharing a common oscillator 54.