GB2052821A

GB2052821A - Monitoring system

Info

Publication number: GB2052821A
Application number: GB8016515A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-05-17
Filing date: 1980-05-19
Publication date: 1981-01-28
Also published as: BE883358A; FI801567A; NO146830C; NO801408L; FI67969C; DE3018661A1; SE7904340L; GB2052821B; SE417024B; NO146830B; FI67969B; FR2456981A1; DK130780A

Abstract

A monitoring system for a shopping trolley in a self-service store, the trolley having a support surface below the basket for the goods, which support surface is not normally visible to the check-out operator, comprises a transmitter/ receiver (F2) to detect an article (7) on the support surface, a further transmitter/receiver (F1) disposed at a lower level than (F2) to block operation of the transmitter/receiver (F2) in response to detection of the legs of the customer, parts of the trolley running gear and the like, and a device to provide a visual and/or audible signal in response to operation of the transmitter/receiver (F2). <IMAGE>

Description

SPECIFICATION Monitoring system This invention relates to a monitoring system for shopping trolleys of the kind used in selfservice stores, including a basket for the goods and having at least one support surface below the basket and which is therefore not normally visible to the check-out operator.

U.S. Patent Specifications 3 725 894 describes a monitoring system for detecting articles disposed on such a lower support surface as the trolley passes through the check-out. In this known system, the trolley has a lightreflecting element which reflects a substantial proportion of light from a source back to the source. Sensing means are provided in order to direct a beam of light towards the reflecting element and to produce a signal only when the intensity of light reflected back to the sensing means exceeds a certain value.

Scanning means are also provided and are operable when actuated by the output signal from said sensing means in order to scan the trolley contents as the trolley passes through the sensing zone. If there is an article on the bottom support surface the check-out operator's attention is drawn to it by a signal system co-operating with the scanning means.

It has been found in practice that this known and similar systems very often given unnecessary or false alarms, due to the structure of the trolley itself particularly upright members forming part of the trolley running gear, the customer's legs, and so on. Consequently, checkout operators tend to disregard signals given by the system.

The object of the invention is so to devise a monitoring system in which only the level of the trolley at which a lower support surface may be expected to be found is scanned and the operator's attention is not unnecessarily distrated.

To this end, the invention provides a transmitter/receiver to detect an article on such a lower surface of a trolley, and a further transmitter/receiver disposed at a lower level than the first mentioned transmitter/receiver in order to block operation of the first mentioned transmitter/receiver in response to the legs of the customer, the trolley running gear and the like, and a device controlled by the first mentioned transmitter/receiver to provide a signal in response to operation of the first mentioned transmitter/receiver.

One example of a monitoring system according to the invention will be described below with reference to the accompanying drawings in which: Figure 1 shows a monitoring zone with a trolley passing therethrough; Figure 2 shows three photoelectric cells used in the monitoring system; Figure 3 is a circuit diagram of the monitoring system; and Figure 4 shows two of the transmitter/receivers combined to form a unit.

Fig. 1 shows a trolley 3 as it passes through a passage between two check-out counters 1. Reference 2 denotes the handle bar of the trolley, reference 4 structural members and 5 trolley wheels. An upper transmitter/receiver F2 is disposed at a height h2 above the floor 6 while a lower transmitter/receiver F1 is disposed at height h1 above the floor. An article 7 is shown on a lower support surface of the trolley.

Referring to Fig. 2, where the direction of travel of the trolley is shown by arrow 8,-'there are in fact two upper transmitter/receiver devices F2, F3. Each of the devices F1, F2 and F3, is a photo-cell device comprising a transmitter and a receiver and together they form a unit 9, which also contains other electronic components. F3 and F2 are disposed at level h2 (see Fig. 1), and F1 is at level h1, normally immediately above wheels 5. The light from each transmitter is a directional frequency-modulated infra-red light.The vertical distance between F3/F2 and F1 is advantageously about 1 46 mm, and the horizontal distance betwee F3 and F1 about 22 mm, the centre-to-centre distance between F2 and F3 about 80 mm, the distance between the transmitter and receiver of F1 about 23 mm, the distance between the centre of F2 and F3 and the edge of the unit 9 is about 1 6 mm, and the centre of the F1 device from the said edge about 38 mm. The values of h1 and h2 in Fig. 1 correspond respectively approximately to the position of the wheel holders and a height somewhat above the bottom trolley support surface. F1 is therefore situated between F2 and F3 but as a lower level. The openings 10 of F1 are about 6 mm in diameter.

Fig. 3 shows the devices F1-F3 with their transmitters T and receivers R. The surface of the article is denoted by reference 7. Reference 22 is the surface of a human leg, for example. Current is produced from the 220 V mains via a transformer 11 and a rectifier unit 1 2 with voltage stabilization, to give 1 2 V d.c. supply. An LED (e.g. green) with a protective resistor 14 indicates when the monitoring system is switched on. F1-F3 are fed at 1 2 V by the rectifier unit and each has a contact system 15, 1 6 and 1 7 respectively.

These contacts change on each interruption of the beam from the particular transmitter T to the surface 7 or 22 and back to the respective receiver R. The devices F1-F3 control an adjustable time relay 18, which controls a flasher relay 1 9. The latter feeds a flasher warning light 20. As soon as F2 and F3 are actuated, time relay 1 8 is operated. The flashing effect may be avoided by means of a switch 21, so that the lamp 20 will light with a permanent, e.g. red, light in the event of an alarm. The lamp 20 may be replaced by orcombined with an acoustic alarm system.

Fig. 4 shows how the transmitters and receivers are combined in a box 9' adapted to be inserted into the unit 9. Box 9' has apertures 40 of about 6 mm in cliameter, while the apertures of the transmitter/receivers 41 are must smaller, about 3-4 mm. The dimensions are selected to give an optimum narrow dispersion angle for the light so that F2/F3 do not interfere with one another: The monitoring system is thus constructed on the basis of three photoelectric cells which are combined with one another, and in which two series-connected devices F2 and F3 "sight" an article 7 on the lower support surface of the trolley. When an article has been detected by both F2 and F3 a warning signal is given.To obviate false alarms due to circumstances associated with the trolley running gear, the photoelectric cells are built into a box 9' as indicated above, the box being so designed that the photoelectric cells and the transmitters do not interfere with one another (Fig. 4). The third photo-cell device F1 is connected in series with the other two in order to avoid indicating insignificant details, e.g. a customer's legs. To this end, F1 is disposed between the bottom edge of the trolley support surface and the floor and is normally closed (i.e. the contacts open when the device F1 detects something) whereas the contacts of F2 and F3 are normally open.

Time relay 1 8 also incorporates a delay feature to cover the case in which a trolley passes rapidly through the monitoring zone.

An alarm signal is generated if both F2 and F3 are operated. However, nothing happens if Fl, F2 and F3 are operated simultaneously.

The coupling interval is trimmed for reflection of the pulsating infra-red light or for the sensitivity of the monitoring system so that details (e.g. a customer) behind a trolley do not result in an alarm.

Claims

1. A monitoring system for shopping trolleys of the kind used in self-service stores, including a basket for the goods and having at least one support surface below the basket and which is not normally visible to the checkout operator, characterised by a transmitter/ receiver to detect an article on such a lower surface of a trolley, and a further transmitter/ receiver disposed at a lower level than the first mentioned transmitter/receiver in order to block operation of the first mentioned transmitter/receiver in response to the legs of the customer, parts of the trolley running gear and the like. and a device controlled by the first mentioned transmitter/receiver in order io provide a signal in response to operation of -he first mentioned transmitter/receiver.

2. A monitoring system according to claim 1, characterised by at least two transmitter/ receivers to detect an article on said lower surface and in that the further transmitter/receiver is disposed at a lower level than, and between, said two transmitter/receivers.

- 2. A monitoring system according to claim 1 or 2, characterised in that the transmitters are arranged to emit frequency-modulated infra-red light in the form of a beam, which is reflected by the article or other detail as the case may be towards respective receivers.

4. A monitoring system according to claim 2 or claim 3 as appendant to claim 2, characterised in that the two transmitter/receivers are combined in a unit.

5. A monitoring system according to claim 4, characterised in that the unit has inlet/outlet apertures for the transmitter/receivers which are larger or substantially larger than the apertures of h e the transmitter/receivers.

6. A monitoring system for shopping trolleys substantially as hereinbefore described with reference to the accompanying drawings.