The process involves examining the coins and/or notes that have been inserted into the machine, and conducts various tests to determine if the currency is counterfeit.
Because the parameters are different for each coin or note, these currency acceptors must be correctly programmed for each item to be accepted.
If a banknote, card or ticket is rejected, it is ejected out of the machine so that the customer can remove it from the slot into which it was inserted.
Normal circulation coins eventually collect microscopic particles of dirt, dust, oil and grease from people's fingers.
[citation needed] Optical sensing with a small light detector called a photocell or a miniature digital camera is one of the main techniques that vending machines use.
Some machines shine an ultraviolet light on the note and measure the glow to help determine the banknote's material composition.
A magnetic sensor located several inches away with its sensitive axis parallel to the direction of travel can detect the remnant[clarification needed] field of the ink particles.
[6] Miniature transducers, approximately 3⁄8 inches in diameter, offer high accuracy linear measurement in a compact space where size constraints prohibit the use of standard LVDTIs.
In addition, the low-mass core is ideal for systems with low driving forces or high acceleration, and therefore will not adversely influence the delicate nature of these applications.
Recent innovations include remote auditing and reporting by these devices as part of an Automated Cash Handling network for entertainment, banking, retail, casino and other industries.