GB2194349A - Weighing apparatus - Google Patents

Abstract

This invention relates to weighing apparatus 1 having a weighing pan 8 adapted for the weighing of bagged items wherein the weighing pan 8 carries thereon a bag closure detector 16 for monitoring during the weighing operation the closure of the bag of items. Preferably the weighing apparatus 1 is connected to a label printer 4 for customer labelling of customer weighed bagged items. The bag closure detector may comprise a metal detector. <IMAGE>

Description

SPECIFICATION Weighing apparatus The present invention relates to weighing apparatus.

In accordance with the present invention there is provided a weighing apparatus having a weighing pan adapted for the weighing of bagged items wherein the weighing pan carries thereon a bag closure detector for monitoring during the weighing operation the closure of the bag of items.

Since bags of paper and of plastics materials can be closed in a variety of ways, the present invention is not limited to any particular type of closure detector. However, the preferred detector from the cost and reliability point of view is a metal detector. By utilising a metal detector the presence of staples and other metallic closure members is detectable.

In order to detect bag closure members of plastic and of other non-metallic materials it is necessary with such a detector to incorporate into the closure member a metallic element for example in the form of a wire, strip or coating. One well-known plastics closure member comprises a length of adhesive tape wrapped around the twisted neck of a bag and stuck to itself. A layer of, say, aluminium can be readily incorporated into such tape in order to render it detectable.

It will be appreciated that by placing a detector on the weighing pan itself the detector will move during the weighing operation with respect to the rest of the weighing apparatus, including the control system under whose management it operates. It is therefore important that there should be either no physical connection between the detector and its control system or a physical connection whose loading on the detector, and hence on the weighing platform, only alters during the weighing operation by an amount which is less than the detection threshold of the weighing apparatus. An example of the former type of communication is an optical link, whilst the latter is a carefully arranged loop of wire whose ends are held at very similar heights.Because of the cost of optical links and the very small movement during loading of present day load cells, a wire loop connection is the preferred means of connection for the detector.

In its preferred embodiment, the weighing apparatus of the present invention includes a label printing apparatus operatively connected to the detector whereby printing of a label is inhibited until the detector detects the closure of the bag. Although the bag closure detector could be used to inhibit or alter any of the functions of a weighing apparatus, it will be appreciated that it is usually only when the label for the bag is to be printed that the closure of the bag need be detected. Thus in the self-service supermarket context a customer should be able freely to add or subtract items from the contents of the bag and repeatedly weigh the bag in order to achieve some desired weight before any label can be printed.

When incorporating a label printing apparatus, the weighing apparatus of the present invention desirably also includes a weighing pan vibration detector operatively connected to the label printing apparatus whereby printing of a label is inhibited until the vibration detector detects that the weighing pan is in stable equilibrium, a zero weight detector operatively connected to the label printing apparatus whereby printing of a label is inhibited until the zero weight detector detects that at least one zero weight condition of the weighing pan has been achieved since the last label was printed, and a minimum weight detector operatively connected to the label printing apparatus whereby printing of a label is inhibited until the minimum weight detector detects that the items to be weighed exceed a pre-determined minimum weight.Whilst the main purpose of these additional detectors is self-evident, the former two have the useful secondary function of preventing interference with the weighing operation by a customer when the present apparatus is used at the self-service counters of supermarkets.

Although the present apparatus can be used simply for weighing bagged items, it is readily possible to incorporate thereinto a weight-toprice converter for pricing the bagged items.

By using an electronic memory device, accessable by for example a keyboard, a plurality of different conversion factors can be stored within the apparatus so as to permit the weighing and pricing of a variety of commodities. In a preferred embodiment, designed especially for customer self-service operation, this keyboard can take the form of a plurality of keys each bearing a representation and/or description of one of the purchasable commodities.

Generally for the retail trade the weighing apparatus of the present invention includes at least one electronic display for displaying information, including for example instructions, about the weighing operation.

One embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a front elevational view of a weighing apparatus of the present invention comprising a weighing unit incorporating an integrated label printer and an integrated electronic display and a remote keyboard, Figure 2 is a plan view of the weighing unit of Figure 1, and Figure 3 is an enlarged side elevational view of the bag closure detector of the weighing unit of Figures 1 and 2.

Referring to Figures 1 and 2, the generally rectangular weighing apparatus comprises a weighing unit shown generally as 1 and a remote keyboard unit 2, the two being electrically connected by wiring 3. Incorporated into the weighing unit 1 is a label printer 4 and an electronic display unit 5.

The weighing unit 1 comprises a chassis 6 supported on four adjustable legs 7, a weighing platform 8 connected to a load cell (not shown) and a weighing control system (not shown). At the front of the unit, a control panel 9 for the control system and a bubbletype level indicator 10 are provided, whilst at the back (not shown) are the mains electrical supply input, the main fuse for the unit and an on/off switch. The panel 9 carries a management key-pad 11, a "label printing" key 12, a "test" key 13, and an area 14 for the display of instructions or information for the user. The control system includes a programmable microprocessor (not shown) and a memory device (not shown) for the costs per unit weight of the commodities on sale.

The weighing platform 8 is rectangular in shape and has bolted thereto along three of its sides upstanding guard rails 15, whilst centrally positioned along the fourth side is a bag closure detector shown generally as 16. The purpose of the guard rails 15 is to ensure that the bag of items to be weighed on the weighing platform 8 are retained in the middle of the platform during weighing and do not spill over onto the chassis 6 thereby possibly distorting the unit's reading.

As shown better in Fig. 3, the detector 16 comprises two parts with a gap 1 7 therebetween for accommodating the neck of the bag being weighed. The larger part 18 is the housing for the detector itself, whilst the smaller part 19 is the housing for a springloaded latch, the beak 20 of which latch projects out of the housing 19 towards the detector housing 18 thereby narrowing the detector gap 17. The upper surfaces of both the latch housing 19 and the latch beak 20 are bevelled towards the gap 17 as shown at 21 and 22, respectively, in order to guide and compress the bag neck when pressed thereinto.The beak bevel also promotes the retraction of the beak into its housing 19 against the pressure of the latch spring (not shown) as the bag neck is pushed past the beak 20 into the lower part 23 of the detector gap 17 where a major part of the detector of the bag closure occurs. The underside of the beak 20 is notched as shown at 24 to assist the holding of the bag neck in the gap 17 during the detection process.

Extending upwardly away from the weighing unit 1 at a back corner thereof is a column 25 surmounted by the electronic display unit 5.

The display unit comprises three display panels 26, 27 and 28 for weight, cost per unit weight and price, respectively, and two lights 29 and 30 to indicate a zero weight reading and the end of the roll of labels, respectively. The weight display panel 26 is arranged to operate whenever the weighing unit is functioning, but the other two panels are programmed by the weighing unit's microprocessor to operate only when a signal is received from the remote keyboard unit 2.

The remote keyboard unit 2, standing on its supporting pillar 31, comprises a 5 x 10 keyboard 32 and a dot matrix display 33. Each key of the keyboard 32 carries a picture and written description of one of the commodities on sale, and when depressed causes the display 33 to repeat the commodity description whilst at the same time instructing the microprocessor of the weighing unit 1 to display on panel 27 the cost per unit weight of that commodity. When setting-up the weighing apparatus for operation all of the costs per unit weight of the commodities on sale are programmed into the weighing unit's microprocessor by means of the management keypad 11, which key-pad is inactivated during normal use of the apparatus in order to avoid interference with the correct pricing of the items being bought.Once the cost per unit weight signal has been received by the microprocessor the price of the items being weighed can then be calculated and displayed on panel 28. The dot matrix display 33 also displays messages to the user of the apparatus such as "SELECT PRODUCT" to guide them through the weighing operation.

As with many modern weighing apparatus, detectors (not shown) are included for the detection of stable equilibrium i.e. vibration of the weighing platform and the exceeding of a minimum weight for the items being weighed.

In weighing apparatus which incorporates a label printer, these detectors are operatively connected to the label printer to inhibit the printing of a label until both stable equilibrium is reached and the pre-determined minimum weight exceeded. In the illustrated apparatus of the present invention there is a further inhibition to the label printing operation, namely from the bag closure detector 16. Unless the presence of a bag closure is detected in the detector gap 17, the key 12 for instructing the label printer 4 will remain inoperative despite all the other conditions such as stable equilibrium, etc, being satisfied. As an added security feature, a zero weight detector (not shown) is included operatively connected to the label printer 4 whereby printing of a label is also inhibited unless at least one zero weight condition has been achieved since the last label was printed.

Although the bag closure detector 16 could operate on a variety of principles, it has been found that one of the most reliable detection methods for bag closures is simple inductive proximity detection. This of course means that the closure member should possess an amount of detectable material such as aluminium sufficient for repeated fault-free detection when like closure members are held by the latch beak in the detector gap 17. With transparent plastics bags, one well-known closure member is a short section of adhesive tape wrapped around the twisted neck of the bag and stuck to itself. Since such bags can be arranged to be of a uniform size and thickness it is readily possible to arrive at the weight of aluminium needed per unit length of tape so as to achieve the requisite total amount of aluminium per average closure for repeated fault-free detection.Conveniently this adhesive tape is dispensed from a standard manual dispenser (not shown) positioned near the weighing unit.

A physical link (not shown) connects the detector 16 with the weighing control system in the chassis 6. It consists of a loop of wire hanging beneath the weighing platform 8 such that its two ends are held at approximately the same height and with none of the loop intermediate its ends touching any part of the platform 8 or chassis 6. Since the movement of the load cell and hence of the platform 8 during weighing is only of the order of 1 mm, it has been found that the variation in loading of the platform 8 by the loop is less than the detection threshold of approximately 0.4 grams-of current supermarket weighing apparatus.

The method of using the illustrated weighing apparatus is as follows: After switching the weighing unit 1 and remote keyboard unit 2 on, the level indicator 10 is checked to ensure that the weighing unit 1 is level and one or more legs 7 adjusted as necessary. By means of the management keypad 11 and the "test" key 13 the functions of the weighing unit are checked and the unit's microprocessor programmed or re-programmed as the case may be with the current commodity prices. Once zero weight for the weighing platform 8 has been detected by the corresponding detector and indicated by light 29, the display 33 will display "SELECT PRO DUCT", the weight display panel 26 will show zero, and the remaining two panels 27 and 28 of the display unit 5 will both be blank.

The customer then selects the commodity he wishes to buy, presses the appropriate key of keyboard 32 and places the desired quantity of this commodity in a plastics bag on the weighing platform 8 to be weighed. The display 33 will change its message to repeat the commodity description whilst causing the panels 27 and 28 to be activated to show the cost per unit weight of that commodity and the price of the quantity being weighed. The customer is at this time free to alter the quantity chosen or even the commodity selected without being able to initiate the printing of a label.

Once the customer is satisfied with the commodity selected and its quantity, he then removes the filled bag from the platform 8, seals its neck using the tape dispenser and replaces the sealed bag on the platform 8 such that the seal is held firmly in the detector gap 17 by latch beak 20. As a prompt to the customer the display 33 will show the temporary message "LOCATE BAG SEAL", before reverting to "SELECT PRODUCT", if the "print" key is depressed before correct location of the bag closure in the gap 17. If correct location is achieved then the pressing of the "print" key 12 will initiate printing of the label by printer 4, unless zero weight has not been achieved since the last label was printed, the platform 8 is in stable equilibrium, a weight in excess of a pre-determined minimum weight is detected and a commodity key has been pressed.

Following printing of the label, the display 33 will change to "ATTACH LABEL-RE- MOVE BAG" and it will then be up to the customer to remove the printed label from the printer 4, attach it to the sealed bag and removed the bag from the platform 8.

As a further security feature an interlock (not shown) is provided between the zero weight detector and the vibration detector which is activated as soon as movement is detected after a label has been printed. Unless zero weight is detected within a pre-set time, e.g. ten seconds, from platform movement this interlock comes into operation to block all further operation of the apparatus and to cause the display 33 to show the message "CALL OPERATOR".

In order to facilitate the attachment of the printed label to the sealed bag by the customer, the labels are of the self adhesive type dispensed from a roll on backing sheet which is peeled away after printing to expose the adhesive layer. Dot matrix printing is very suitable for such labels and allows for the easy alteration of the data displayed on the label, e.g. the addition or omission of a bar code, by reprogramming of the weighing unit's microprocessor. The data that will usually be displayed includes weight, cost per unit weight, price and commodity description.

A link can also be installed from the weighing unit's microprocessor to the store's computer for stock control purposes.

In certain supermarkets the illustrated weighing apparatus may be required for weighing and labelling only one commodity, e.g. potatoes. In that case, the remote keyboard unit can be detached and the microprocessor of the weighing unit programmed with a single commodity cost per unit weight.

Claims (9)

1. A weighing apparatus having a weighing pan adapted for the weighing of bagged items wherein the weighing pan carries thereon a bag closure detector for monitoring during the weighing operation the closure of the bag of items.

2. An apparatus as claimed in claim 1 wherein the detector is a metal detector.

3. An apparatus as claimed in claim 1 or claim 2 including a label printing apparatus operatively connected to the detector whereby printing of a label is inhibited until the detector detects the closure of the bag.

4. An apparatus as claimed in claim 3 including a weighing pan vibration detector op operatively connected to the label printing apparatus whereby printing of a label is inhibited until the vibration detector detects that the weighing pan is in stable equilibrium.

5. An apparatus as claimed in claim 3 orclaim 4 including a minimum weight detector operatively connected to the label printing apparatus whereby printing of a label is inhibited until the minimum weight detector detects that the items to be weighed exceed a pre-determined minimum weight.

6. An apparatus as claimed in any one of claims 3 to 5 including a zero weight detector operatively connected to the label printing apparatus whereby printing of a label is inhibited until the zero weight detector detects that at least one zero weight condition of the weighing pan has been achieved since the last label was printed.

7. An apparatus as claimed in any one of the preceding claims including a keyboard for setting the price per unit weight of items to be weighed.

8. An apparatus as claimed in any one of the preceding claims including at least one electronic display for displaying information about the weighing operation.

9. An apparatus as claimed in claim 1 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.