Check-actuated control mechanisms – Including means to test validity of check – By testing material composition
Reexamination Certificate
1998-07-13
2001-05-15
Ellis, Christopher P. (Department: 3652)
Check-actuated control mechanisms
Including means to test validity of check
By testing material composition
Reexamination Certificate
active
06230869
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a coin validator and is particularly concerned with setting up coin acceptance windows for comparison with coin data derived from coins to be validated, in order to determine coin acceptability.
BACKGROUND
Coin validators which discriminate between coins of different denominations are well known and one example is described in our GB-A-2 169 429. This coin validator includes a coin rundown path along which coins pass edgewise through a sensing station at which coils perform a series of inductive tests on the coins to develop coin parameter signals which are indicative of the material and metallic content of the coin under test. The coin parameter signals are digitised so as to provide digital coin parameter data, which are then compared with stored data by means of a microprocessor to determine the acceptability of otherwise of the coin under test. If the coin is found to be acceptable, the microprocessor operates an accept gate so that the coin is directed to an accept path. Otherwise, the accept gate remains inoperative and the coin is directed to a reject path.
The stored data is representative of acceptable values of the coin parameter data. The stored data in theory could be represented by a single digital value but in practice, the coin parameter data varies from coin to coin, due to differences in the coins themselves and consequently, it is usual to store window data corresponding to windows of acceptable values of the coin parameter data. The width of the windows is a compromise between a number of factors. In order to achieve satisfactory discrimination between true and false coins, the window widths should be made as narrow as possible. However, if the windows are made too narrow, there is a risk that true coins will be rejected as a result of minor differences between the characteristics of true coins.
Another problem is that the window data needs to vary from validator to validator due to minor manufacturing differences that occur between validators manufactured to the same design. Consequently, it is not possible to program a fixed set of window data into mass produced coin validators of the same design. A conventional solution to this problem is to calibrate coin validators individually by passing a series of known true coins of a particular denomination through the validator so as to derive test data from which appropriate window data can be computed and stored in the memory of the validator. Reference is directed to GB-A-1 452 740. This calibration method is however time consuming because a group of test coins for each denomination needs to be passed through the validator in order to derive data from which the w windows can be computed. Alternative techniques are disclosed in WO94/04998 and U.S. Pat. No. 5,067,604.
The present invention provides an alternative approach which allows a single set of window data to be used for all coin validators for a particular design, notwithstanding differences in their characteristics that arise within normal manufacturing tolerances, from validator to validator.
SUMMARY OF THE INVENTION
In accordance with the invention there is provided a coin validator comprising: means for producing coin parameter data as a function of a characteristic of a coin under test; means for comparing the coin data with window data corresponding to a window of acceptable values within a range of values for the coin parameter data, for determining coin acceptability; and window set up means operable during a set up mode prior to normal operation of the validator, said set up means comprising: memory means storing initial window data corresponding to an initial window with an initial width within said range of values; control means for deriving operating window data corresponding to an operating window of values in said range of values, in response to coin parameter test data derived from a known true coin validation performed by the validator for the set up mode, said control means being operative to drag the initial window through the range of values of coin data by an amount determined in response to the coin parameter test data, and to shrink the width of the initial window so as to derive the operating window; and means for switching the validator from the set up mode to a normal operating mode in which the comparing means compares the coin data from coins to be validated with the operating window data derived during the set up mode, for determining coin acceptability based on said operating window.
In accordance with the invention, the same initial window data may be stored in the memory of each individual coin validator of the same design. The initial window data can constitute an approximation of the desired operating window, but with a window width which is sufficiently broad to cover all manufacturing tolerances that can be expected for the particular validator design. During the set up mode, the operating window data is produced for each individual validator in response to a coin test performed by the individual validator, by dragging and shrinking the initial window in order to produce operating an window data specific to the validator concerned, which can satisfactory discrimination between true coins and frauds.
This has the significant advantage that it is not necessary to feed a large number of coins through the validator for calibration purposes at the time of manufacture. Instead, the calibration can be performed by the user, as an initial set up procedure, whereafter the set up means is disabled and the validator switched to normal operating mode.
The invention extends to a method of setting up an operating window in a coin validator which in a normal operating mode produces coin parameter data as a function of a characteristic of a coin under test and compares the coin data with operating window data corresponding to an operating window of acceptable values within a range of values for the coin parameter data, for determining coin acceptability; wherein prior to the setting up the operating window, initial window data has been stored in a memory means in the validator, the initial window data corresponding to an initial window within said range of values, that approximates to the operating window; the setting up method comprising: performing a validation operation with the validator with a known true coin so as to produce coin parameter test data; deriving operating window data corresponding to an operating window in said range of values of coin data, by dragging the initial window through the range by an amount determined in response to the coin parameter test data, and shrinking the width of the initial window; and thereafter switching the validator into said normal operating mode in which coin data from coins to be validated are compared with the operating window data for determining coin acceptability.
The method according to the invention permits remote setting up of coin validators. For example, the validators may be manufactured and sold with no initial window data in their memories. Initial window data corresponding to a coin set of a particular currency may be supplied together with the validators so that it can be loaded into the validators in the country of sale. For example, if the validators are manufactured in the United Kingdom and then sold in Brazil, validators may be supplied with initial window data on a floppy disc or some other suitable memory, so that it can be loaded at the point of sale by the local distributor of the validators. The set up procedure can be carried out by the local distributor or can be carried out by the purchaser of the validator. Once the set up has been performed with a set of local currency coins, the set up procedure is disabled.
Moreover, if the coin set for the country concerned is subsequently changed, for example to introduce a new coin, a revised set of initial window data may be supplied by the manufacturer to the distributor in the country concerned which can be re-loaded into the validators. The initial window data or the rev
Coin Controls Ltd
Ellis Christopher P.
Morgan & Finnegan , LLP
Tran Thuy V.
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