Telephonic communications – With check operated control – Coin signalling or control
Reexamination Certificate
2000-01-14
2003-03-25
Barnie, Rexford (Department: 2743)
Telephonic communications
With check operated control
Coin signalling or control
C379S147000, C379S148000, C194S316000, C194S324000, C194S320000
Reexamination Certificate
active
06539083
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a system and method for validating coins, and to pay telephones using the system or method. The term “coin” is not limited to coins issued as currency on behalf of Governments, but also covers any other tokens which it may be desirable to identify automatically, such as private currencies circulating within large organizations or telephone call tokens issued by telephone companies.
Coin validation systems are used in a wide variety of machines, such as in turnstiles, automatic vending machines and automatic ticket issuing machines, and pay telephones. A wide variety of methods are known for sensing coins and for processing the outputs of the sensors. For example, input coins may be sensed by their influence on a capacitor or an inductor, they may be detected by optical sensors, and the nature of the material of the coin may be examined by causing the coin to vibrate and examining the nature of the vibrations.
The normal use of inductive sensors is to provide a manner of investigating the nature of the material which an input coin is made from. If the coin passes through the field generated by an inductor, so that the coin affects the inductance of the inductor, a ferromagnetic coin will tend to increase the inductance whereas a diamagnetic coin will tend to decrease the inductance. Additionally, if the magnetic field from the inductor is continually fluctuating, eddy currents generated in an electrically conductive coin will tend to reduce the effective inductance of the inductor. These effects can oppose each other. For example, if a coin is electrically conductive and also ferromagnetic or paramagnetic, then its ferromagnetism or paramagnetism will tend to increase the inductance of the inductor whereas its electrical conductivity will tend to decrease the inductance of the inductor owing to the eddy currents. The relative magnitudes of these opposing effects, and hence the net effect of the coin, will depend on various factors including the frequency of fluctuation of the magnetic field. In general, inductive sensing systems can be divided into “high frequency” systems, in which the magnetic field oscillates at a frequency of at least 100 kHz, and in which the effect of a coin on the inductance is almost entirely due to eddy currents, and “low frequency” systems in which the magnetic field oscillates at no more than 75 kHz, and in which the magnetic nature of any ferromagnetic coin material has a significant effect on the inductance of the sensor. The magnetic effect of a paramagnetic material to increase the effective inductance and the magnetic effect of diamagnetic material to reduce the inductance are both so small that the effect of eddy currents normally predominates unless the oscillation frequency is very low (less than about 10 kHz).
In high frequency systems the change of the inductance of the sensor can be used simply to detect the presence or absence of a coin at the position of the sensor, or the magnitude of the change in inductance can be measured. The magnitude of the change in inductance will depend, for example, on the degree to which the coin entirely overlaps the coil, the electrical resistivity of the material from which the coin is made, and perhaps to some extent the pattern embossed on the face of the coin. In a low frequency system, the direction of the change in inductance can be used to identify whether a coin is ferromagnetic.
GB Patent No. A-2055498 proposes a system using two coin sensors, each of which is a pair of coils arranged one on each side of the coin path, with one of the coils being an oscillating coil and the other being a receiving coil. In one sensor the coils are about the same size as the height of the coin path, which is considered to be the diameter of the largest diameter coin which passes along the coin path. The oscillating coil of this sensor is energized with a low frequency (e.g., 10 kHz), which is stated to be suitable for discriminating the material of the coin. The other sensor uses relatively small coils (it proposes a range of 10 to 30 mm for the height of the coil), arranged at the top of the coin path and extending down sufficiently that its field interacts with the smallest diameter coin expected in the coin path, but not extending all the way down to the bottom of the coin path. The oscillating coil of this sensor is excited by a high frequency (e.g., 100 kHz). The extent to which the sensor is affected by a coin depends on the degree to which the mass of metal of the coin occupies the area of the electromagnetic field between the coils, and therefore the level of signal received in the receive coil is a measure of coin diameter.
WO Patent No. A-87/00662 proposes a system which is stated to be “high frequency” although no specific frequency is mentioned. It proposes an arrangement of several coils at different heights above the bottom of a coin path. No dimensions for the coils are given, but it is stated that each sensor is arranged so that it is influenced to some extent by coins whose diameter lies in a region attributed to the sensor, whereas the sensor is not influenced by coins whose diameter lies under this region and is influenced by a maximum extent by coins whose diameter lies above this region. Accordingly, the arrangement of several sensors at different heights provides an arrangement for discriminating coins of different diameters.
GB Patent No. A-2169429 proposes an arrangement in which three inductive sensor coils are used for coin validation. Two of these are placed alongside the coin path, whereas the third is placed across the coin path so that the coin passes through the windings of the coil. It is stated that with the coils placed alongside the coin path, coin discrimination improves with frequency, coil frequencies of 100 kHz and 160 kHz are proposed, and it is stated that the change in impedance of a coil occurs by virtue of skin effect type eddy current being induced by the coil in the coin (at least in respect of a coil alongside the coin path). Of the two coils arranged alongside the coin path, one is arranged so that its diameter is generally (but not always) larger than the maximum diameter of coins that pass along the coin path. It is stated that the whole of the coin under test occludes this coil. The other coil alongside the coin path is disposed on the opposite side of the coin path and is placed offset above the floor of the coin path such that only the upper part of the coin under test occludes it. It is stated that the effect of the coin on the first coil provides a parameter indicative of the size, metallic content and the embossed pattern of the coin. It is not stated what the effect of the coin on the second coil indicates. However, it is stated that the coin of particular denomination, a substantially unique set of effects of the coin on the coils is produced.
GB Patent No. A-2045498 proposes an inductive sensor for detecting coin diameter. This uses an oblong inductor mounted so that the smallest acceptable coin overlaps the lower end of the inductor and the largest acceptable coin does not extend above the upper end of the inductor. The inductor is connected to an oscillator circuit which should oscillate at a high frequency (e.g. above 75 kHz), and the normal oscillating frequency in the absence of a coin is proposed to be 600 to 700 kHz, in order that the oscillating magnetic field penetrates only the surface of the coin under test.
EP Patent No. A-0164110 proposes a system using two sensors, each of which comprises a pair of coils arranged one on each side of the coin path. One coil of each pair is an oscillator coil, connected to an oscillator so as to generate oscillating magnetic fields, and the other coil of each pair is a receiving coil. The frequencies of the magnetic fields are stated to be low enough to cause the magnetic fluxes to pass through the coins, but no particular values for the frequency are proposed. It is proposed that the coin material can be discriminated by measuring the maximum signal o
Barnie Rexford
Kirschstein, et al
Marconi Communications Limited
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