Coin discrimination apparatus and method

An electronic coin detector comprising:

• a path in which a coin under test travels from a first end to a second end;
• a first inductor coil having a surface extending along said path, said surface being disposed adjacent said path such that when the coin travels along said path the coin passes adjacent the coils;
• a longitudinal channel extending through said duct for receiving coins traveling along said path;
• a second inductor coil surrounding said channel;
• means for providing a first oscillation signal to said first inductor coil and for providing a first altered oscillation signal in response to the effect of a coin passing adjacent said first inductor coil;
• means for providing a second oscillation signal to said second inductor coil and for providing a second altered oscillation signal in response to the effect of a coin passing through said channel;
• means for storing into a memory statistical variables determined from measurements of the predetermined electrical characteristics of a plurality of coins of the same type as the coin under test;
• and
• means responsive to said first and second altered signals for determining for the coin under tests a deviation value in relation to the stored statistical variables.

A method of determining whether or not a coin being sampled is acceptable, the method comprising the steps of:

• providing a signal having electrical characteristics corresponding to physical characteristics of the coin being sampled;
• storing into memory statistical variables determined from electrical characteristics for acceptable coin types;
• determining for said coin being sampled a statistical variation of said electrical characteristics of said signal from the stored statistical variables;
• and
• providing an indication that the coin being sampled is acceptable if said statistical variation is within a predetermined range.

The method of determining whether or not a coin is acceptable, the method comprising the steps of:

• providing a signal having a plurality of electrical characteristics, each of said characteristics corresponding to an effect resulting from a coin under test passing through an inductively induced electromagnetic field;
• providing variables which are statistical functions of a plurality of said electrical characteristics for each acceptable coin type;
• storing said variables in a memory;
• determining a statistical variation of said electrical characteristics of said signal with reference to said stored variables;
• and
• indicating when a coin under test has a statistical variation within a predetermined limit.

A method for detecting the presence of a coin comprising the steps of:

• passing a coin along a path from a first end to a second end;
• providing an inductor coil establishing a magnetic flux along the path;
• providing a correction signal that changes to a changed correction signal in response to changes in magnetic flux caused by the presence of the coin in the path;
• sensing a characteristic of the correction signal before the coin is present in the path;
• setting a first threshold level corresponding to the characteristic of the correction signal;
• incrementing the first threshold level by a preset amount to a second threshold level;
• comparing the second threshold level to the characteristic of the changed correction signal;
• and
• indicating that the coin is passing along the path when the characteristic of the changed correction signal exceeds the second threshold level.

A method for discriminating between acceptable and unacceptable metal members of a given type, the method comprising the steps of:

• evaluating a plurality of acceptable members of a given type with an electrical sensing means for determining statistical variables for selected electrical characteristics of the given type;
• evaluating the selected electrical characteristics for a member of the given type under test and determining a deviation value in relation to a plurality of the statistical variables;
• and
• accepting or rejecting the member under test by determining whether its deviation vale falls within a predetermined range of the statistical variables.