currency detector a currency detector or currency validator is a device that determines whether notes or coins are genuine or counterfeit these devices are used in many automated machines found in retail kiosks self checkout machines arcade gaming machines payphones launderette washing machines car park ticket machines automatic fare collection machines railway station ticket machines and vending machines the process involves examining the coins andor notes that have been inserted and by using various tests determining if the currency is counterfeit since the parameters are different for each coin or note these detectors must be programmed for each item that they are to accept in normal operation if any item such as a coin note card or ticket is accepted it is retained within the machine and it falls into a storage container to allow a member of staff to collect it later when the machine is being emptied if the item is rejected the machine returns the item to the customer if a coin or token is rejected it usually falls into a tray or rolls out of a slot at the bottom where the customer can remove the coin if a banknote card or ticket is rejected it is pushed back out through the machine so that the customer can remove it from the slot into which it was inserted coin acceptors the basic principle for coin detection is to test the physical properties of the coin against known characteristics of acceptable coins the coin acceptor analyses the coin according to its mass size diameter thickness metal composition andor magnetism and then sends an appropriate electrical signal via its output connection the next step is generally performed by the banknotetocoins exchanger today sophisticated electronic coin acceptors are being used in some places that in addition to validating weight and size also scan the deposited coin using optics and match the image to a predefined list or test the coins metallic signature based on its alloy composition normal circulation coins eventually collect microscopic particles of dirt dust oil and grease from peoples fingers when a coin acceptor is used long enough thousands of coins rolling along a track will leave enough dirt dust oil and grease to be visible for this reason the coin acceptor has to be cleaned on a regular basis to prevent malfunction or damage coin acceptors are modular so a dirty acceptor can be replaced with a clean unit preventing downtime the old unit is then cleaned and refurbished some new types of coin acceptors are able to recognize the coins through training so they will support any new types of coins or tokens when properly introduced testing methods vending and change machines use several techniques to check whether a note is genuine toggling these settings and the sensitivity of each is programmed via means of dip switches on the internal circuitry optical sensing 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 many countries banknotes are pixelatedthat is they are made out of small dots the dots are spaced differently and have different sizes depending on the note the optical sensors can look for these different patterns to determine what sort of note has been inserted some paper money is also fluorescent it glows when ultraviolet light is shined on it some machines shine an ultraviolet light on the note and measure the glow to help determine the notes composition gmr sensor proximity detection the particles in the ink on many countries currency have ferromagnetic properties including some elemental iron notes are passed over a permanent magnet array and magnetized along their direction of travel a magnetic sensor located several inches away with its sensitive axis parallel to the direction of travel can detect the remnant field of the ink particles the purpose of the biasing magnet in this case is to achieve a controlled orientation of the magnetic moments of the ink particles resulting in a maximum and recognizable magnetic signature reversing the magnetizing field can actually invert the signature physical attributes the thickness and dimensions of a banknote are tested to ensure they are correct us currency is 261 inches wide by 614 inches in length and are 00042 inches thick and weigh 1 gram miniature transducers approximately 38 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 operating ranges are available from 0005 to 100 divided into eight intermediate strokes genuine federal reserve notes have a clear polyester thread embedded vertically in the paper the thread is inscribed with the denomination of the note and is visible only when held up to light each denomination has a unique thread position and will glow a unique color in ultraviolet uv light banknote acceptors a typical us validator with a green bezel also known as validators or acceptors paper currency detectors scan paper currency using optical and magnetic sensors upon validation the validator will inform the vending machine controller vmc or other host device of a credit via a parallel or serial interface various interfaces exist for the host device including a singleline pulse interface a multiline parallel interface a multiline binary interface and serial interfaces such as cctalk ssp and mdb wrinkled or creased notes can cause these machines to reject them an american banknote passing through the device note the pistons that grab it when it detects an insert tiny cameras are mounted on the printed circuit board there are currently only a handful of companies manufacturing this equipment crane payment innovations joining crane payment solutions and mei and japan cash machine jcm are two of the largest each maintaining dominance in a particular market segment other notable companies producing this type of equipment include coinco pyramid technologies inc pti international currency technologies ict alpha cms cash management solutions astrosystems money controls pyramid technologies validation technologies international vti innovative technology ltd itl global payment technologies gpt and jofemar recent innovations include remote auditing and reporting by these devices as part of an automated cash handling network for amusement banking retail casino and other industries automated cash handling counterfeit banknote detection pen eurion constellation intelligent banknote neutralisation system watermark 