To determine if bills or coins are counterfeit or genuine, currency detectors or currency validator devices are used. Many automated machines found in self-checkout machines, transportation parking machines, gaming machines, vending machines, automated fare collection machines, retail kiosks, transportation parking machines use this currency detector device. After it has been inserted into the machine the currency will be examined and using various tests are done to determine if the currency is a genuine or a counterfeit. To get your own counterfeit detectors, you can trust iTestCash. The process is different for coins and currency and the detectors are programmed for each item they are to receive.
If the item is accepted it will be retained by the machine and put in a storage container and the currency or coins that are not accepted by the machine are rejected. If the bill is rejected it will be pushed out of the machine and the customer should take the bill back and the same goes with coin if rejected the coins will be dropped into a slot outside the machine and the customers should take the coin out. To check if a currency is genuine or not the change machines and vending machines use several different techniques.
Different testing methods are used by the machines to check to see if currency or bill is genuine or a counterfeit.
GMR sensor proximity detection: On the currency on many countries currencies have particles in the ink on the currencies have ferromagnetic properties and the iron on the dollar bill is elemental. Bills are passed over a permanent magnetic array and in the direction of the travel magnetized. The remnant field of the ink particles which ha ferromagnetic properties are detected by the magnetic sensors located several inches away located parallel to the travel of the bills or currencies. Biasing magnet, in this case, is to achieve controlled orientation of the ink particles which result in a recognizable magnetic signature.
Optic sensing: Vending machines use a small light detector called photocell. Optic sensing is done with a miniature camera or with a photocell. Bills are made out of small dots and are pixelated. Dots have different sizes and spaced differently depending on the bill. To determine what kind of bill has been inserted optic sensors are used which looks for the different patterns on the bill and determine the type of the bill inserted in the slot. Ultraviolet light has been used as a counterfeit detector for years. When UV light is is shined on the dollar bills which are florescent the bills glow. Some machines use UV light to measure the glow of the bill and to help them determine what they are looking at.
Physical attributes: They also play an important role in counterfeit detection. The dimension and thickness of bill are tested to ensure they are correct.