Abstract: Disclosed are various apparatus and methods for discriminating between fake and reject coins. The term ‘coin’ includes any type of monetary token or token that is associated with a value. Various different apparatus and methods are disclosed. These include a method and apparatus of applying multiple input currents of different frequencies to a coin and monitoring the apparent change in impedance of a coil or coils resulting from eddy currents induced in the layers of the coin from the multiple input currents. Other methods and apparatus relate to applying electromagnetic radiation to the coin and measuring various resulting characteristics including the amount of light fluoresced or reflected from the coin, or the absorption characteristic of the coin. Other methods and apparatus relate to measuring vibration of a coin. Other methods and apparatus relate to identifying genuine and bogus coins via particular identifying characteristics of the coins including magnetic codes/serial numbers.

Abstract: A coin discriminator measures both the surface and average electrical conductivity of coins in order to distinguish genuine minted coins from fake or bogus coins such as cast coins which may be nominally of the same material as a minted coin. The conductivities are measured using a coil to induce eddy currents within the coin. The high frequency components of the eddy current are monitored to measure the surface conductivity. The low frequency components are measured to monitor the bulk or average conductivity.

Abstract: A coin processing machine with a coin discriminator operated by a method is provided. The coin discriminator measures how a coin having an iron core covered by a layer of copper, brass, or bronze affects a coil when the coin is subjected to magnetic fields generated by the coil, external to the coin. Eddy currents induced in the coin are detected external of the coin. The discriminator induces a magnetic field in the coil by driving the coil with time varying drive signals having high frequencies. The coin discriminator receives the coin at precise positions in the magnetic field and detects the eddy currents induced in the coin by measuring the eddy currents through the coil. Then, the coin discriminator compares the measured eddy currents with predetermined values for different types of coils, and determines the structure, materials and type of the coin.

Abstract: A coin discriminator measures both the surface and average electrical conductivity of coins in order to distinguish genuine minted coins from fake or bogus coins such as cast coins which may be nominally of the same material as a minted coin. The conductivities are measured using a coil to induce eddy currents within the coin. The high frequency components of the eddy current are monitored to measure the surface conductivity. The low frequency components are measured to monitor the bulk or average conductivity. First and second signals are derived for each coin to provide a measurement set for that coin, the first signal being a measure of the conductivity of the surface skin of the coin, and the second signal being a measure of the conductivity of the body of the coin. The measurement set is then compared in some way with stored sets of reference signals obtained from a batch of minted coins in a calibration procedure, to determine the authenticity of the coin.

Abstract: A coin processing machine with a coin discriminator operated by a method is provided. The coin discriminator measures how a coin having an iron core covered by a layer of copper, brass, or bronze affects a coil when the coin is subjected to magnetic fields generated by the coil, external to the coin. Eddy currents induced in the coin are detected external of the coin. The discriminator induces a magnetic field in the coil by driving the coil with time varying drive signals having high frequencies. The coin discriminator receives the coin at precise positions in the magnetic field and detects the eddy currents induced in the coin by measuring the eddy currents through the coil. Then, the coin discriminator compares the measured eddy currents with predetermined values for different types of coils, and determines the structure, materials and type of the coin.

Abstract: A coin discriminator has a coin path along which a coin, containing a first portion and a second portion made of different metals and/or metal alloys, is arranged to pass. An electrical mechanism supplies time-varying drive signals to the coil mechanism. A detection mechanism detects eddy currents induced in the coin by the coil mechanism. The coil mechanism is arranged to induce in the coin an eddy current loop, which in a predetermined region of the coin crosses a bond between the first and the second portions of the coin.

Abstract: A high speed coin sorter of the belt type has an elongate plate (8') along which coins (12) to be sorted are carried in single file by a belt (1) which is driven by a pulley (2). A series of coin deflecting recesses (15 to 18) of hockey stick shape are formed in the upper surface (8) of the plate (8'), and in dependence upon the denomination of a coin, as determined by a coin discriminator (10, 11) positioned in advance of the recesses, the coins are selectively deflected from their straight line paths along the surface (8) by respective solenoid-actuated pins (19 to 22), such that a coin is pressed by the belt into the appropriate deflection recess corresponding to that coin denomination. A shaft encoder (4, 6) is associated with the belt drive pulley (2), and the signals from the encoder are used to track the progress of the coins along the surface (8) from the discriminator to provide a timing signal for projecting the appropriate deflection pin.

Abstract: A coin detecting device suitable for use in conjunction with a coin acceptor of a type employed in a gaming or vending machine comprises an inclined channel-shaped track which is formed from an insulating material and along which a coin may roll. Three flat metal plates are located on one side wall of the track, the plates being spaced apart in the direction of movement of the coin down the track and being separated from the coin by the (insulating material) wall of the track. The plates are spaced apart by a distance such that the coin will initially overlap first and second ones of the plates to form a first pair of series capacitors and, thereafter, will overlap the second and third plates to form a second pair of series capacitors. Voltage pulses are applied to the second (intermediate) plate and a detector circuit is connected in circuit with the first and third plates.

Abstract: Various electrical coin testing arrangements are described which may be used in coin sorters or in coin validators for example. In each arrangement a transmit coil is pulsed with a rectangular voltage pulse and the eddy currents in an adjacent coin under test are monitored, either by monitoring the resulting current in the same coil or in a different coil. In one arrangement, FIG. 7particularly suitable for a coin validator, a single coil acts as both a transmitter and receiver and is successively pulsed with voltage pulses of different lengths, and the decaying eddy currents are measured by measuring the coil voltage after delays which are longer for longer voltage pulses, in order to reduce the dynamic range requirements of the monitoring circuitry. In a second arrangement, FIG. 4two transmit coils are used, the larger coil being larger than each of the coins to be tested, and the smaller coil being smaller than each coin.