Coin validator

A method of validating a coin/token, including the steps of:

• energizing detect coils, between which at least part of a coin/token is located at the time of energization;
• de-energizing said coils after a predetermined time;
• inverting and amplifying at least one portion of a voltage-limited back EMF curve;
• obtaining a first number of system clock counts from the time between de-energization of said coils and that when the curve intersects a first reference voltage;
• obtaining a second number of system clock counts from the de-energization of said coils and that when the curve intersects a second reference voltage;
• obtaining a third number of system clock counts from the time between de-energization of said coils and that when the curve intersects and third reference voltage;
• comparing said first number, said second number and said third number respectively with a first range of stored numbers, a second range of stored numbers and a third range of stored numbers;
• and
• producing a signal representative of the acceptance of said coin/token if said first number, said second number and said third number fall respectively within said first range, said second range and said third range of numbers.

A method of programming a coin/token validator to store reference values for one type of coin/token, including the steps of:

• energizing detect coils, between which at least part of a first coin/token of a first type is located at the time of energization with a single pulse;
• extracting from the back EMF of the decaying pulse information in the form of a first set of numbers, which set constitutes a definition of said first coin/token;
• storing said first set of numbers;
• repeating said first and second steps for a predetermined number of coins/tokens of a first type, and storing each set of numbers produced by said steps with said first set of numbers, to produce a set of ranges of numbers;
• and
• establishing the set of stored ranges of numbers obtained for all the coins/tokens of said first type as a set of ranges of numbers representative of said first type of coin/token.

A coin/token validator including:

• a reference path;
• detect coils located on either side of said path;
• detect means to detect the presence of at least part of a coin/token between said coils;
• means to energize and de-energize said coils with a single pulse;
• and
• means to derive a definition of said coin/token after the period of energization, said definition being constituted by at least one number of system clock counts, derived from portions of the post de-energization decay curve of the voltage in said detect coils.