Shopping cart monitoring system

A system for monitoring contents of a tray located beneath a basket of a shopping cart as the latter is passed through an aisle adjacent a checkout station having a point of sale terminal capable of receiving a signal through a communications interface which signal prevents completion of a transaction unless overridden by operator input of one of a product and an override code, the system comprising apparatus adjacent the aisle for detecting and signalling presence of the cart in the aisle, apparatus adjacent the aisle for scanning a space above the tray of the cart to detect and signal the presence of objects thereon, and apparatus responsive to signals from both said cart detection apparatus and said object detection apparatus to output said signal to the communications interface of the terminal, thereby forcing the operator to enter one of a product and an override code;

• wherein the apparatus for detecting and signalling the presence of objects on the tray comprises second radiation transmitters on one side of the aisle and second radiation receivers on an opposite side of the aisle, the further transmitters and receivers facing each other across a space between the tray and the basket when the cart is in said predetermined position, such that the outputs of at least one of said receivers will be reduced by the presence of an object on the tray which obstructs radiation from the transmitters;
• and
• wherein the transmitters transmit pulse modulated radiation, and the receivers include demodulators.

A system for monitoring contents of a tray located beneath a basket of a shopping cart as the latter is passed through an aisle adjacent a checkout station having a point of sale terminal capable of receiving a signal through a communications interface which signal prevents completion of a transaction unless overridden by operator input of one of a product and an override code, the system comprising apparatus adjacent the aisle for detecting and signalling presence of the cart in the aisle, apparatus adjacent the aisle for scanning a space above the tray of the cart to detect and signal the presence of objects thereon, and apparatus responsive to signals from both said cart detection apparatus and said object detection apparatus to output said signal to the communications interface of the terminal, thereby forcing the operator to enter one of a product and an override code;

• wherein the apparatus for detecting and signalling the presence of objects on the tray comprises second radiation transmitters on one side of the aisle and second radiation receivers on an opposite side of the aisle, the further transmitters and receivers facing each other across a space between the tray and the basket when the cart is in said predetermined position, such that the outputs of at least one of said receivers will be reduced by the presence of an object on the tray which obstructs radiation from the transmitters;
• and
• wherein the signal responsive apparatus is a controller including a first routine to compare the pattern of outputs of the first receivers for similarity to a previously stored pattern of outputs, a routine to compare the pattern of outputs of the second receivers for differences from a previously stored pattern of outputs, and a routine to emit said signal in response to detecting both a sufficient degree of similarity between the patterns in said first routine, and a sufficient degree of dissimilarity between the patterns in said second routine.