Currency detector

A currency detector is a device that determines if a piece of currency is, or is not, counterfeit. These devices are used in vending machines that accept payment and dispense a product to a customer. They are also used in change machines and in slot machines.

The process involves examining the currency that has been inserted, and by using various tests, determine if the currency is counterfeit. Since the parameters are different for each coin or paper money, these detectors must be programmed for each item that they are to accept.

In operation, if the item is accepted it is retained by the machine and placed in a storage device. If the item is rejected, the machine returns the item. If it is a coin, it usually drops into a container for the customer to take back. If it is a bill, the machine pushes the bill out and the customer must remove it from the slot in which it was placed.

Banknote acceptors
Also known as bill validators or bill acceptors, paper currency detectors scan pliant currency using optical and magnetic sensors. Upon validation, the bill 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 single-line pulse interface, a multi-line parallel interface, a multi-line binary interface, and serial interfaces such as ccTalk, SSP, and MDB. Wrinkled or creased bills can cause these machines to reject them.

There are currently only a handful of companies manufacturing this equipment. MEI, Japan Cash Machine (JCM) and Coin Acceptors Inc. (CoinCo) are three of the largest, each maintaining dominance in a particular market segment. Other notable companies producing this type of equipment include CashCode CRANE, 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.

Bill validators were introduced in the US in the early 1980s. Recent innovations include remote auditing and reporting by these devices as part of an Automated Cash Handling network for banking, retail, casino and other industries.

Pricing on these types of units can be less than $50 for a used refurbished unit, to over $1000 or more on a new, state of the art, high security unit.

While in the past these devices were extremely susceptible to failure and jamming due to folded or damaged notes, they have improved remarkably in recent years, and now include such features as automatic jam ejection and automatically calibrating sensors. Cleaning cards are available to remove contaminants from the machines.

Coin detectors
The basic principle for coin detection is to test the physical properties of the coin against known composites from acceptable coins. It evaluates the coin based on its weight, size, and/or magnetism, and then sends an appropriate electrical signal via its output connection. The next step is generally performed by the coin changer.

Simple mechanical coin acceptors are relatively easy to cheat by using slugs and other coin-like materials that pass the rudimentary validation. Today, sophisticated electronic coin acceptors are in use in some places that, in addition to validating weight and size, also scan the deposited coin using optics and match the image to a pre-defined list.

Normal coins pick up microscopic deposits from human fingers. When a coin acceptor is used long enough, thousands of coins rolling down a ramp will leave enough dirt to be visible. The acceptor requires periodic cleaning to prevent malfunctioning. Coin acceptors are modular, so a dirty acceptor can be replaced with a clean unit, preventing downtime.

Some new types of coin acceptors are able to recognize the coins through training, so they will support any types of coins or tokens.