GB2278839A

GB2278839A - Article dispensing machine

Info

Publication number: GB2278839A
Application number: GB9311866A
Authority: GB
Inventors: John Nicholas Reid
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-06-09
Filing date: 1993-06-09
Publication date: 1994-12-14
Also published as: GB9311866D0

Abstract

A dispensing machine is for dispensing articles in a cold environment, such as in a freezer compartment of a hot food vending machine. Each article 16 has attached to it an electrical conductor 10. The machine comprises at each dispensing location a pair of spaced electrodes 18 from which an article may be suspended by means of the electrical conductor 10. By applying an electric potential across the electrodes 18 a heating current is made to flow in the section of the electrical conductor bridging the electrodes 18 which causes the conductor 10 to break and the article 16 to drop. <IMAGE>

Description

ARTICLE DISPENSING MACHINE Field of the invention The present invention relates to an article dispensing machine.

Oblect of the invention The invention seeks to provide a dispensing machine that operates reliably in an outdoor environment, and that can be constructed inexpensively.

Summary of the invention According to a first aspect of the present invention, there is provided a method of dispensing an article which comprises suspending the article by means of an electrical conductor attached to the article and passing a current through the conductor when the article is to be dispensed to heat the conductor sufficiently to cause it to melt, to vaporise or to be weakened so as to render it incapable of supporting the weight of the article.

According to a second aspect of the invention, there is provided a dispensing machine for dispensing articles, each article having attached thereto an electrical conductor from which the article may be suspended, the machine comprising a plurality of dispensing locations each having a pair of spaced electrodes from which an article may be suspended by means of the electrical conductor attached thereto, and means for applying an electric potential across the electrodes to cause a heating current to flow in the section of the electrical conductor bridging the electrodes.

Though the electrical conductor may be formed of a wire of high conductivity in the case where the article to be dispensed is relatively light, it is preferred to use resistance wire made for example of a nickel chromium alloy or a copper nickel alloy for its strength, resistance to corrosion and ability to heat to a melting temperature at a low current.

An advantage of the invention is that the presence of an article at a dispensing location can be sensed before and after a vending cycle by monitoring the resistance between the electrodes at that location. This information can be used both to prevent attempts to dispense from empty locations and to ensure that a vending cycle has been correctly completed. Thus, in a vending cycle, a small current may first be passed through the electrodes at the selected location to ensure the presence of an article.

Thereafter, the current is increased to cause the electrical conductor to be heated to the point where it can no longer support the weight of the article. At this point, the article should fall under gravity and break the electrical circuit through the electrodes. If the current drops to zero, then it may safely be assumed that the article has fallen away from the dispensing location.

The ability to detect the presence of an article at a dispensing location has another important advantage in enabling dispensing in strict rotation. When the dispensing machine is refilled, the control processor may determine which locations had articles before the refill and which have fresh article loaded into them. A dispensing order can therefore be established to ensure that the older stock is totally exhausted before dispensing from the newer stock commences. Indeed, it is possible to store in memory the date when an fresh article was loaded at a given location not only to ensure stock rotation but also to prevent an article from being dispensed after a "sell by date".

The invention is particularly applicable to a hot food dispensing machine such as those in which a hamburger from a freezer compartment is dropped into a microwave oven which heats it prior to its being dispensed. In such an application, the shape of the electrical conductor is important and it should be ensured that it does not contain any inductive loops that would result in overheating within the microwave oven.

Conveniently, the electrical conductor may be a U-shaped conductor having the free ends of its limbs trapped between two layers of a self-adhesive tape which may be attached to the packaging of the article to be dispensed. Such a suspension device may readily be formed in a automated process.

Brief description of the drawings The invention will now be described further, by way of example, with reference to the accompanying drawings, in which Figure 1 shows a suspension device for attachment to a package, Figure 2 shows a package suspended by means of the device of Figure 1 at a dispensing location within a dispensing machine, Figure 3 shows a continuous strip from which the device of Figure 1 may be cut, and Figure 4 is a sketch of an apparatus for automatically producing the strip shown in Figure 3.

Detailed description of the preferred embodiment Figure 1 shows a suspension device that comprises a wire 10 sandwiched between two layers of a tape 12 having an adhesive region 14 by means of which it may attached to an article to be dispensed.

The wire 10 has an exposed loop that enables an article to be suspended and is made of resistance wire such as a nickel chromium or a copper-nickel alloy. Such a wire has sufficient strength to support the weight of an article yet will melt when a relatively low current is passed though it.

Figure 2 shows the device of Figure 2 adhered to the box of a hamburger that is to be dispensed within an automatic vending machine. The machine itself need not be described in detail as it may be generally similar to known machines.

Typically, the machine contains trays in a freezer compartment on which the articles are supported at several dispensing locations arranged in a rectangular matrix on the tray. Any location can be selected by suitable control electronics to cause an article to be released from that location, whereupon the article falls through a trap door into a microwave oven which heats it prior to its being dispensed.

The invention is primarily concerned with the release mechanism employed at the individual locations. At each location, the tray includes a pair of electrodes 18 spaced from one another by a thin insulating wafer and over which the looped conductor 10 may be slipped to support the article 16 on the tray. The weight of the article ensures good electrical contact between the wire loop 10 and the spaced electrodes 18.

When the article is to be dispensed, a voltage is applied across the electrodes 18 to cause a current to flow in the section of the wire bridging the gap between the two electrodes. The magnitude of the current is set to be sufficiently high to cause the wire 10 to melt and break, thereby allowing the article 16 to fall from the tray under its own weight. As alternative to the wire melting, it is possible for it to vaporise the wire but it is preferred to avoid the resultant sputtering of metal.

Figures 3 and 4 show a simple manner of mass producing the device shown in Figure 1. Wire 70 is drawn from a reel 50 and passes over a guide roller 52 into a forming station 54 in which it is bent to form loops. The bent wire is fed through two pinch rollers that act as drive rollers onto a wide adhesive tape 72 drawn from a reel 60. The wire is located onto the tape so that the loops project beyond one side of the tape 72. The tape 72, with the wire resting on it and partly adhering to it, passes over a guide roller 58 towards two pressure rollers 64 where a further but narrower adhesive tape 74, drawn from a reel 62 is placed to overlie the edge of the wider tape 72 from which the wire loops project. This results in the formation of a strip as shown in Figure 3 that can be cut between the wire loops to form the individual suspension devices. In the apparatus of Figure 4, the cutting is effected at a cutting station 68 towards which the strip is fed by a suitable indexing mechanism represented by the rollers 66.

An important advantage of the use of a conductor on each article as a suspension device is that it is possible to determine the presence of an article at any dispensing location by monitoring the resistance between the electrodes 18. In a dispensing cycle, a low current is first passed through the conductor to ensure that an article is present and making contact with the electrodes 18. If so, a higher current is made to flow until the wire breaks and current no longer flows. This combination of events enables the control circuit to ensure that an article is always dispensed at the end of a dispensing cycle. It is possible additionally to monitor the falling of the article on to a dispensing chute to ensure that the article has not become jammed anywhere in the machine and been prevented from reaching the microwave oven.

The ability to detect the presence of a package at a dispensing location also enables the control processor to determine the date on which any article was loaded into the machine to permit stock rotation, in other words to ensure that fresh stock is not dispensed while older stock remains in the vending machine.

It will be appreciated that various alterations may be made to the embodiment described above without departing from the scope of the invention as set out in the appended claims.

For example, the conductor need not be melted by the heating current. It is sufficient for it, or its connection to the article, to be sufficiently weakened by the heating current to prevent it from being able to support the weight of the article.

Claims

1. A method of dispensing an article which comprises suspending the article by means of an electrical conductor attached to the article and passing a current through the conductor when the article is to be dispensed to heat the conductor sufficiently to cause it to melt, to vaporise or to be weakened so as to render it incapable of supporting the weight of the article.

2. A dispensing machine for dispensing articles, each article having attached thereto an electrical conductor from which the article may be suspended, the machine comprising a plurality of dispensing locations each having a pair of spaced electrodes from which an article may be suspended by means of the electrical conductor attached thereto, and means for applying an electric potential across the electrodes to cause a heating current to flow in the section of the electrical conductor bridging the electrodes.

3. A machine as claimed in claim 2, wherein the conductor is formed of resistance wire, such as a nickel chromium alloy or a copper nickel alloy.

4. A machine as claimed in claim 1 or 2, comprising means for detecting the presence of an article at a dispensing location prior to the article being dispensed by determining the resistance between the electrodes at the dispensing location.

5. A dispensing machine constructed, arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.