Coin validation

Details Coin validation Coin validation

1996-03-04

1998-08-25

Bartuska, F. J.

Check-actuated control mechanisms

Including means to test validity of check

By testing material composition

194327, 194331, G07D 504

Patent

active

057974756

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to coin validation, and, more particularly, to coin validation using acoustic measurement of coin impact upon an impact member.


BACKGROUND OF THE INVENTION

Historically, validation of coins was originally carried out using mechanical sensors of parameters such as the coin weight, thickness or diameter. Examples of mechanical coin validators are shown in GB-A-1184843 and GB-A-0941211, in both of which mechanical sensing of the coin diameter is employed. In GB-A-0941211, faceted coins are detected by providing serrations on the coin ramp and corresponding serrations on an upper member, spaced from the coin ramp by the diameter of the coin. In GB-A-1184843, the arrangement is for detecting particular milled coins, and serrations are providing on the ramp to engage with the milling on the coins so that, in conjunction with an upper element which engages the top edge of the coins, the ramp controls movement of the coins so that they roll rather than slipping alone the ramp.
More recently, the art has moved on from such mechanical validators. Nowadays, electronic coin validators are almost universally employed.
In the past, various attempts have been made to utilise the vibrations caused by the impact of a coin on an impact element forming part of a coin validation apparatus as an indication of coin validity or denomination. An example is disclosed in EP-A-0543212. The different hardness of different coin materials produces a different vibration spectrum on impact, which can be used to discriminate between coins which are otherwise quite similar; for example, lead counterfeit coins ("slugs") of a similar size and/or weight and/or conductivity to a genuine coin can be distinguished from such coins by the fact that they have a much lower hardness, which results in a different vibration pattern on impact.
In use, an electro acoustic transducer (for example a piezoelectric sensor) is mechanically coupled (directly or indirectly) to the impact element, and some feature of the sensor output is used to validate or discriminate a coin. For example, as in EP-A-0543212, the width of the sensor output pulse caused by the impact may be utilised, or as in GB-A-2236609 the gradient of the pulse may be utilised; alternatively, the peak height of the output pulse, or some other spectral or temporal feature of the output signal, or some combination thereof is used.
To date, such acoustic validation techniques have not been widely employed, because they are sensitive not only to coin material but also to variations in the coin flight and extraneous external noise.


SUMMARY OT THE INVENTION

According to the present invention, in one aspect, there is provided a coin validator comprising an impact member configured to create multiple impacts with a coin.
We have found that the provision of multiple impacts enables the reduction of the effect of variations in the sensor output caused by irregularities in coin flight and/or extraneous noise.
A separate problem in the art is the discrimination of so called bi-color coins; that is to say, coins having an inner disk of a first material surrounded by one or more concentric outer rings of different materials. Approaches to solving this problem to date have provided different sensors to sense different regions of the coin, as described, for example, in GB-A-2266804.
Although such bi-color coins are generally made of one or more metals which may of themselves be hard, for example of a comparable hardness to other coins to be discriminated therefrom, we have found that, surprisingly, such bi-color coins behave on impact in a manner somewhat similar to soft slugs; that is to say, they do not give rise to such sharp, high amplitude oscillations as comparable homogeneous coins, but instead to damped, lower amplitude vibrations on impact. It is believed that this damping is due to acoustic reflections within the coin, at the interface between the different metals.
Accordingly, in another aspect, we make use of this surprising property of bi-colo

REFERENCES:
patent: 2076862 (1937-04-01), Patzer
patent: 3910394 (1975-10-01), Fujita

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