DEVICE FOR DETECTING THE PRESENCE OF ARTICLES

Abstract: The invention relates to a device for detecting the presence of articles in a space, comprising: means for determining a location for each of the articles in the space; and a detector arranged at each location for detecting the presence of an article at the relevant location, wherein the detector is adapted to react to the displacement of a part of the detector caused by the force of gravity, wherein the detector is a solid-state detector. Solid-state detectors are not susceptible to wear, or hardly so, while being equally insensitive to moisture. It is therefore recommended that the detected comprises a magnet and an element reacting to a change in the magnetic field caused by the magnet. This is a type of detector which is wholly insensitive to dirt and moisture. According to another preferred embodiment the element reacting to the magnetic field is a Hall element. Hall elements are small and have a low energy consumption.

Description: DEVICE FOR DETECTING THE PRESENCE OF ARTICLES The invention relates to a device for detecting the presence of articles in a space, comprising: - means for determining a location for each of the articles in the space; and - a detector arranged at each location for detecting the presence of an article at the relevant location, wherein the detector is adapted to react to the displacement of a part of the detector caused by the force of gravity. Such a device is known from EP-A-0 340 420. In this known device micro-switches are applied. These micro-switches have the drawback of being susceptible to wear and of being sensitive to moisture. Experience has shown that such presence detector circuits are used mainly, though not exclusively, in the catering industry, wherein they form part of an integrated payment and administrative system and wherein the removal of an article, for instance a bottled drink to be served, is detected by the presence detector and transmitted to a recording device. Such a device must be cleaned regularly, wherein a large amount of water is usually used and whereby moisture can affect the operation of the switch. Furthermore, it sometimes occurs that a bottle breaks and that the detector comes into contact with liquid, in particular sugary liquid, thereby causing malfunction of the detector. The object of the present invention is to provide such a device, wherein detectors are applied which are less sensitive to water and which have a longer life- span. This objective is achieved in that the detector is a solid-state detector. Solid-state detectors are not susceptible to wear, or hardly so, while being equally insensitive to moisture. It is possible in principle to embody the detector with a light source and a light-sensitive element. Although the sensitivity of such detectors to fouling and water is considerably better than that of detectors provided with switches, they suffer from the drawback that the light path can be affected by fouling, while it is moreover possible that the light source fails and has to be replaced. It is therefore recommended that the detector comprises a magnet and an element reacting to a change in the magnetic field caused by the magnet. This is a type of detector which is wholly insensitive to dirt and moisture. According to another preferred embodiment the element reacting to the magnetic field is a Hall element. Hall elements are small and have a low energy consumption. According to yet another preferred embodiment the magnet is f^xed on a spring which is pressed downward by an article placed in the position. This is found to be an attractive switching configuration. The Hall element is preferably fixedly mounted on a printed circuit board which extends over all detectors located in a surface. This is an attractive manner of preventing connection problems; the Hall elements are each placed on a printed circuit board in a matrix configuration and connected by means of the wiring present on the printed circuit board to a connector or the like. According to yet another preferred embodiment a cover plate is placed above the printed circuit board, recesses are made in the cover plate at the location of the positions at which the articles must be placed, and in each recess is arranged a cap manufactured from flexible material which is connected to the cover plate and which extends over the magnet and the spring. An additional protection of the switch elements is obtained with this configuration, while this moreover results in an exceptionally simple, operationally reliable and inexpensive solution. According to yet another preferred embodiment the magnet is received in the cap. This avoids the presence of further structural elements. According to a particularly advantageous embodiment the spring is connected clampingly on its top side to the cap. This also obviates further structural elements. According to a new preferred embodiment a vapour- tight layer is arranged between the printed circuit board and the cap. An additional protection against moisture is obtained with this measure. When the vapour-tight layer comprises a rigid plate, a sturdy base is created for the bottles; the upper, thin plate could after all easily sag. As already stated above, the present device is particularly applicable in the catering industry. It is therefore recommended that the space be formed by a closable space to be opened by a key, that the articles be formed by bottles and that the detectors be connected to the recording device. Other attractive preferred embodiments are stated in the remaining claims . The invention will be elucidated hereinbelow with reference to the annexed drawings, in which: figure 1 shows a perspective view of an opened cabinet in which the device according to the present invention is applied; and figure 2 is a cut-away detail view of the device shown in figure 1. Figure 1 shows a cabinet 1 in which are arranged two drawers 6. An insert 3 is placed in each of the drawers 6. Cabinet 1 can be closed on its front side by a door which is not shown in the drawing. In addition, the cabinet is preferably formed by a refrigerator for cooled storage of the content of the cabinet. Each of the inserts 2,3 is formed by a metal plate 4 which is bent on its sides and which thus forms a tray. A plate 5 manufactured for instance from plastic or wood is arranged on top of this tray 4. A cover plate 7 is arranged above plate 5. Cover plate 7 is preferably manufactured from metal and extends over the whole surface of plate 4, wherein plate 7 is likewise bent at its edges so that together with plate 4 a box is formed. Plate 7 is provided with openings 8 ordered in a matrix. A hat-shaped element 9 manufactured from flexible plastic is arranged in each of the openings 8. Hat-shaped element 9 is fixed clampingly round the edges of the relevant opening 8 and can be further connected to plate 7 by vulcanizing or glueing. This is however not essential. A spiral spring 10 is arranged inside hat-shaped element 9. This spiral spring 10 rests with its underside on plate 5 which is provided with an opening 6 smaller than the openings 9 in plate 7. On its upper side the spiral 10 is connected by a clamping connection to hat-shaped element 9. Further arranged in the top of hat element 9 is a cavity which is filled by a permanent magnet 11. Spiral spring 10 is dimensioned such that when an article, for instance a bottle 12, is placed on hat-shaped element 9 the top of hat-shaped element 9 is pressed downward. The permanent magnet 11 herein moves downward. Because bottles 12 must be supported not only on their underside but also on their sides, there is arranged above plate 7 a frame 13 in which an opening 14 is arranged at the position of each of the hat-shaped elements. Openings 14 thus form the positioning means for the bottles. In order to detect the presence of a bottle 12 a printed circuit board 15 is arranged extending over the whole surface of the drawer. The printed circuit board is provided with a Hall element 16 at the position of each of the magnets 9. Print tracks 17 are arranged on printed circuit board 15 to connect each of the Hall elements 16 to for instance a connector not shown in the drawing. The connector is then connected to a plug which is connected in turn to a cable connected through the rear of the cabinet 1 to a computer not shown in the drawing. _ As already stated in the preamble, such a device usually finds application in the catering industry, this for recording the consumption of drinks. In order to record which waiter or waitress has removed the ordered drink from the cabinet, use is made of a recording sensor 18 arranged on the side of cabinet 1. The waiter or waitress places his/her identification element 19, for instance a magnetic card, into recording sensor 18, whereby for ( instance the door (not shown) of cabinet 1 opens. The waiter or waitress can then remove the required ordered drink, wherein he/she can moreover enter on a keyboard for instance the table number of the group which has ordered the drink. He/she then closes the door and serving of the drink is recorded. It will be apparent here that if a bottle position is occupied by a bottle, the weight of bottle 12 will press the permanent magnet 11 downward counter to the force of spring 10, whereby the permanent magnet 11 is urged into the vicinity of the Hall element 16. The Hall element detects this displacement of the permanent magnet; the Hall element will after all detect a much stronger magnetic field because the distance to the permanent magnet has become shorter, this being recorded in per se known manner by the computer forming part of the device. When the bottle is taken away the permanent magnet 11 will move upward due to the action of spring 10, whereby the Hall element 16 will be subjected to a magnetic field of lesser magnitude. This is also transmitted, which will record the removal of an ordered drink. It will be apparent that it is possible to depart from the construction shown here in numerous ways. It is thus possible for instance only to read the detectors when the door of cabinet 1 is closed; drawers 2,3 are then pushed in fully and are then connected galvanically by for instance a plug connection to a socket received in the rear wall. It is further possible to apply a larger or smaller number of drawers and the door for closing the drawers can be omitted if the drawer fronts close the interior of the cabinet and if the lock acts on the drawers.

Claims: CLAIMS 1. Device for detecting the presence of articles in a space, comprising: - means for determining a location for each of the articles in the space; and - a detector arranged at each location for detecting the presence of an article at the relevant location, wherein the detector is adapted to react to the displacement of a part of the detector caused by the force of gravity, characterized in that the detector is a solid-state detector. 2. Device as claimed in claim 1, characterized in- that the detector comprises a light source and a light- sensitive element. 3. Device as claimed in claim 1, characterized in that the detector comprises a magnet and an element reacting to a change in the magnetic field caused by the magnet . 4. Device as claimed in claim 3, characterized in that the element reacting to the magnetic field is a Hall element. 5. Device as claimed in claim 3 or 4, characterized in that the magnet is fixed on a spring which is pressed downward by an article placed in the position. 6. Device as claimed in claim 5, characterized in that the Hall element is fixedly mounted on a printed circuit board which extends over all detectors located in a surface. 7. Device as claimed in claim 6, characterized in that a cover plate is placed above the printed circuit board, that recesses are made in the cover plate at the location of the positions, and that in each recess is arranged a cap which is manufactured from flexible material and which is connected to the cover plate and which extends over the magnet and the spring. 8. Device as claimed in claim 7, characterized in that the magnet is received in the cap. 9. Device as claimed in claim 7 or 8, characterized in that the spring is connected clampingly on its top side to the cap. 10. Device as claimed in claim 7, 8 or 9, characterized in that a vapour-tight layer is arranged between the printed circuit board and the cap. 11. Device as claimed in claim 10, characterized in that the vapour-tight layer comprises a rigid plate. 12. Device as claimed in any of the foregoing claims, characterized in that the space is a closable space to be opened by a key, that the articles are formed by bottles and that the detectors are connected to a recording device. 13. Device as claimed in claim 12, characterized in that at least one outward movable drawer is arranged in the space and that the positions are placed on the drawer. 14. Device as claimed in claim 12, characterized in r that the detectors are received in the drawer and that the detectors are connected by means of a cable to the recording device.

Inventors: BOELSMA ROB, VAN DER WEIJDEN ENGEL, VOLLAARD PETER, BOELSMA, ROB, VAN DER WEIJDEN, ENGEL, VOLLAARD, PETER
Applicants: BOELSMA ROB, FRI JADO BV, VOLLAARD PETER, WEIJDEN ENGEL V D, BOELSMA, ROB, FRI-JADO B.V., VAN DER WEIJDEN, ENGEL, VOLLAARD, PETER
Application year: 2001
Main classification: G07F5
IPC codes: G07F5