Coin flow in a game
Subjects:
Coin Head
Coin accepting mechanism
Mechanical coin acceptor, lockout coil and whisker switch
Electronic coin comparator and coin-in optics
Electronic coin acceptor with built-in coin-in optics
Diverter
Hopper and hopper level probe
Coin drop
Coin head
The first place a coin is evaluated is at the coin head where the coins are inserted into the game. The coin head is designed to not allow entry of a coin larger than what the game is designed to accept.
Coin accepting mechanism
There have been many specific systems used here. We will attempt to break them down into three basic categories.
Mechanical coin acceptor
Early games used a mechanical coin acceptor physically designed to evaluate a coin by its physical characteristics; diameter, thickness, metallic content, and such. Each acceptor has to be designed for a specific denomination of coin.
A Lockout Coil is an electrically activated plunger. When not activated a spring mechanism pushes out a plunger into the coin path of the mechanical coin acceptor, blocking the path of the coin returning the coin back to the player. When the game is ready to accept coins the Insert Coin lamp is lit and the Lockout Coil is activated pulling the plunger in allowing coins to pass through the coin acceptor.
Rejected coins pass out one side of the acceptor and are returned to the player. Good coins pass out the other side of the coin acceptor and to a Whisker Switch. A whisker switch is a switch with a long wire actuator that bends into the coin path. Accepted coins pass over the wire and the MPU monitors the switch to see that a coin has been accepted.
One big disadvantage of this system is that you could put a coin on a string and pull the string back out once it has passed through the switch. The system could not tell if the coin is going up or down.
Electronic Coin Comparator and Coin-In Optics
These are an analog electronic circuit (op amps) that compares the incoming coin against a reference coin inserted in the comparator. An AC signal is passed through an E-shaped coil. A reference coin is inserted into one of the hollows of the E. The other hollow of the E is the coin-in path. When the incoming coin is the same as the reference coin a Null pulse is generated. This Null signal eventually becomes a signal out to the game MPU telling it a good coin has been recognized and also pulls in a solenoid that allows the coin to pass through the Accepted side of the comparator. If the coil is irregular the solenoid stays in place and the coin is returned to the customer.
Once the coin has been accepted it passes through two or three sets of optics. Each set of optics is a Light Emitting Diode (usually Infrared) and a phototransistor. The coin passes between the LED and phototransistor giving a pulse out of the phototransistor. With two or three sets of optics we can not only judge the presence and speed of the coin but also the direction the coin was passing.
Electronic Coin Acceptors
These do not use a reference coin, but instead are microprocessor-based designs that are programmed to recognize the electronic signature of the coin and accept it or reject it. The metallic coin passing through a coil creates an analog signal. This analog signal is digitized and compared against the pattern of a good coin. The Acceptor is programmed to accept a certain coin through a training routine. Some acceptors can accept and recognize multiple coins.
Most games have a flexible interface between the MPU and the coin-in system so different types of systems can be used on a given game. When you buy a game it may come with a standard system popular to your industry or you may specify what type of coin-in system you want. Software has to be changed to recognize the system you choose. These things are specified hen setting up a game after a RAM Clear.
Most times such coin acceptors have the coin-in optics built into the acceptor and operation is under the control of the microprocessor in the acceptor.
Errors
Stuck Coin-In
This implies that a coin was sensed passing through the coin-in switch for too long or may be stuck there.
Coin Direction Error
This error means that a coin was sensed passing up through the optics. It may imply that an attempt was made to string a coin or a coin just bounced back up through the optics after hitting something.
Coin Sensing Error
This error means that a coin was sensed passing through coin-in optics but a signal was not received from the coin acceptor that a good coin has been accepted.
Terminology may vary but it will fall into one of these categories.
Diverter
Once the coin has passed through the coin-in switch, or optics, it may take one of two paths. It may go to a coin hopper and held there to eventually be returned to the customer when they cash out. Coins in the hopper belong to some customer some time and are not counted as casino revenue. The accepted coin may alternately be forwarded to the coin drop and collected as revenue to the casino.
The position of the diverter is controlled by the game MPU. The MPU monitors the Hopper Full Probe on the hopper. When the hopper is empty the diverter position forwards coins to the hopper. When the hopper is full the coins themselves make a connection between the probe and ground. The MPU monitors the probe and when grounded the MPU moves the diverter and coins are then forwarded to the drop. After a Cash Out by a customer that brings the coin level down below the probe level the diverter is moved back to refill the hopper.
Coin Hopper
Coins to be paid out to the customer are held in the hopper. The hopper is designed to work with a specific denomination of coin. When the customer hits the Cash Out button the MPU turns on the hopper motor. A Coin Out Switch monitors coins leaving the hopper. The MPU monitors the Coin Out Switch and counts the outgoing coins. When the proper number of coins has been counted the MPU turns off the hopper motor.
Some hoppers are dumb and the game MPU controls the hopper directly. Some smarter hoppers have a microprocessor and hopper operation is monitored and controlled by the Hopper Control Board.
Errors
Hopper Jam
This means that a coin has been sensed under the coin out switch for too long a period.
Hopper Empty
After the MPU has started a payout no coins were sensed passing through the coin out switch for a certain length of time.
Extra Coin Paid Out
This means a coin was sensed passing through the coin out switch when the MPU was not expecting it to happen.