Back to results
US 4,398,626 AGranted
Low frequency phase shift coin examination method and apparatus
AssigneeMars, Incorporated
InventorElwood E. Barnes
Life of this patent
Estimating the term…
Abstract
A method and apparatus for coin examination which subjects one side of a coin to a low frequency electromagnetic field from a transmitter inductor driven by an astable oscillator and frequency divider, receives a portion of the field on the other side of the coin with a receiving inductor, amplifies the output of the receiving inductor with a non-linear amplifier, and measures the phase shift between the signal driving the transmitter inductor and the amplifier output.
Claims16
A method for examining coins comprising the steps of
- generating a low frequency electrical signal,
- subjecting a coin to an electromagnetic field produced by a first inductor driven by the low frequency signal,
- receiving a portion of the field with a second inductor when the coin is between the first and second inductors,
- amplifying the electrical output of the second inductor which is produced by the field, and
- measuring the phase shift between the low frequency signal which drives the first inductor and the amplified output of the second inductor,
- wherein an additional phase shift inversely related to the amplitude of the output of the second inductor is introduced in the amplifying step.
3 more elements
Apparatus for examining coins comprising means defining a coin passageway,
- means for producing a low frequency electrical signal,
- a first inductor connected to the output of the signal producing means, the first inductor being located on one side of the coin passageway and arranged to produce an electromagnetic field in the coin passageway,
- a second inductor located on the other side of the coin passageway from the first inductor at a place where coins to be examined will pass between the first and second inductors, the second inductor being arranged to receive a portion of the field in the passageway,
- an amplifier connected to receive the output of the second inductor, and
- means for measuring the phase shift between the low frequency signal and the output of the amplifier,
- wherein the amplifier introduces an additional phase shift which is inversely related to the amplitude of the output of the second inductor.
3 more elements
Dependencies are inferred from the claim text.