Automatic teller machines

[0002] This invention relates to Automatic Teller Machines (ATMs). It is particularly concerned with the detection of fraud in such machines.

[0003] One function of an ATM is to dispense banknotes to a user. A standard ATM having the facility to dispense banknotes includes electronic control means in the form of a central processing unit (CPU) which is connected to a cash dispenser unit and a user interface device. The user interface device comprises a display unit, a keypad, a card reader and an output slot through which the cash dispenser unit dispenses banknotes to a user. As is well known, to operate such an ATM a user inserts a user's identity card into the card reader and then enters certain data, such as a personal identification number (PIN) and the quantity of currency required to be dispensed, by mean of the keypad. The ATM will then process the requested transaction, dispense banknotes extracted from one or more storage cassettes within the currency dispenser unit, update the user's account to reflect the transaction and return the card to the user.

[0004] One advantage of ATMs is that they operate without human supervision and can be located at sites away from bank premises. A drawback is that they are vulnerable to being tampered with for the perpetration of fraud or other types of theft. One of the more common methods of attack is to add or insert mechanisms into the ATM to prevent their standard operation and either capture the contents of a transaction or record confidential information.

[0005] It is an object of the invention to detect the presence or absence of fraudulent equipment in an ATM.

[0006] According to the invention an automatic teller machine includes a loudspeaker and a microphone, signal generator means connected to the loudspeaker for enabling the loudspeaker to generate an acoustic signal and means for evaluating the signal received by the microphone to determine whether the signal has been modified by the presence of any foreign object in the machine.

[0007] Preferably the acoustic signal that is generated is white noise.

[0008] In carrying out the invention means may be provided for comparing the received signal with a previously recorded standard received signal. Any significant difference between the compared signals indicates the presence of a foreign object.

[0009] The generator means may be operated at the start of a teller operation and again on its completion. Provided that the two received signals are not significantly different the latter signal is then used thereafter as the standard received signal. This allows for the small incremental changes in the received signal that take place over time due to wear in the parts of the ATM without such wear being mistaken for tampering.

[0010] In order that the invention may be more fully understood reference will now be made to the accompanying drawings in which:

[0011] FIG. 1 is an external perspective view of an ATM,

[0012] FIG. 2 is an internal diagrammatic view of an ATM embodying the invention, and

[0013] FIG. 3 shows the ATM of FIG. 2 after a fraudulent device has been added.

[0014] As shown in FIG. 1 an ATM 2 includes a user interface 6 incorporating a slot 8 for receiving a user identity card. Slot 8 is part of a card reader contained within ATM 2. User interface 6 also includes a keypad 10 through which data can be inputted, a screen 12 for displaying information and an output slot 14 for dispensing banknotes to a user. ATM 2 incorporates a CPU to receive data from the card reader and keyboard 10 and control a cash dispenser unit which extracts banknotes from one or more storage cassettes and dispenses the extracted banknotes to output slot 14. The CPU, cash dispenser unit and banknote storage cassettes are all located within ATM 2 and are not visible in the external view of ATM 2 shown in FIG. 1. These items of equipment are well-known and are therefore not described herein in detail.

[0015] Referring now to FIG. 2 there is shown therein part of the internal mechanism of ATM 2 in diagrammatic form. In particular the cash dispenser unit of ATM 2 includes a transport mechanism 3 by which banknotes are transferred from storage cassettes to output slot 14 of FIG. 1. Included within ATM 2 is a loudspeaker 4 which is energized from a signal generator 5. A microphone 7 is positioned within ATM 2 to receive signals from loudspeaker 4 and the output from microphone 7 is taken to a signal detector 9 which incorporates a processor. Signal generator 5 is designed to generate white noise. The nature of the sound detected in microphone 7 when signal generator 5 is functioning depends on the nature and positioning of the various pieces of equipment contained within ATM 2. The detected sound constitutes a sound signature distinctive of the particular ATM and this signature will be different if the equipment within ATM 2 is added to or is moved.

[0016] An illustration of an ATM that has been tampered with is shown in FIG. 3, in which like parts have the same reference numerals as in FIG. 2. ATM 2 in FIG. 3 includes a mechanism 13 that has been fraudulently added. Mechanism 13 is positioned relative to banknote transport mechanism 3 to trap banknotes in their passage from storage cassettes to output slot 14.

[0017] To detect the presence or absence of mechanism 13 an initial signal is first detected and recorded by sampling the white noise generated by loudspeaker 4 when it is known that ATM 2 is in an untampered state. This signal then constitutes a standard signal. After each operation of ATM 2 signal generator 5 is energized again and the detected signal compared with the standard signal. If there is a significant difference between the two signals then this is an indication that ATM 2 has been tampered with and an alarm signal can then be generated.

[0018] In practice a standard signal can be generated on a regular basis, conveniently before each operation of ATM 2. If the new standard signal is not significantly different from the previous standard signal then the new signal is used as the standard. This updating of the standard signal ensures that wear within ATM 2 is automatically catered for without such wear being mistaken for tampering.