EP0581699A1 - Sorting installation for collectivity cutlery - Google Patents

Abstract

The installation according to the invention comprises at least three sensors C1, C2, C3 arranged in a detection area (11) bounded by a support plane (16) and a lateral guide plane (17). The place settings are pushed longitudinally one after the other into the detection area (11), and held laterally supported against the lateral guide plane (17). The sensors (C1, C2, C3) are positioned at respective distances (D1, D2, D31, D32) making it possible to define sequences of signals which are different as a function of the types of place setting and possibly as a function of their direction. The signals are transmitted to a signal processing device which drives sorting flaps in a sorting area downstream of the detection area (11). The invention makes it possible to sort mass catering place settings depending on their type, in order to bring them to separate reception compartments. A fourth sensor makes it possible to recognise their direction. <IMAGE>

Description

The present invention relates to the sorting of community cutlery at the outlet of a dishwasher.

In a collective restaurant, the cutlery is generally presented in a series of separate compartments each comprising a single piece of cutlery such as knives, forks, large spoons and small spoons.

It is also advantageous, even essential for hygiene reasons, to present the cutlery in a unique orientation in each compartment, so that the user can grasp each cutlery chosen by the handle without being tempted to grasp it by the cutlery head or without touching the neighboring cutlery heads which could be near the handle chosen if the cutlery is out of order.

In addition, in a community dishwasher, the cutlery is generally mixed with each other and arranged out of order. Thus, at the end of washing, the cutlery ends up out of order on a conveyor intended to bring them from the dishwasher to the compartments of use. It is then necessary to sort the cutlery to distribute them in their respective compartments according to their type, and it is also necessary to orient them properly in the respective compartments so that all the handles are in the same direction in the same compartment. These sorting operations are generally carried out manually.

The document WO-A-8 606 661 describes a device in which a ramp of optical cells, arranged transversely with respect to the direction of travel of the cutlery, is associated with a computer to evaluate the entire contour of the cutlery and thus recognize its type. Such a device is complex and expensive.

The same applies to the device described in document EP-A-0 220 832, comprising several photoelectric cells and a computer for sorting cutlery arranged transversely with respect to their direction of travel.

Document FR-A-2 651 696 describes a device with two sensors detecting respectively the minimum diameter and the maximum diameter of the dishes. Such detection is insufficient for a complete sorting of cutlery.

An automatic sorting device for community cutlery has also been proposed, implementing a complete recognition of the shape of the cutlery by a video camera and a video image processing device. Such an installation is particularly complex and expensive, and proves incapable of sorting the cutlery at a sufficient speed because the recognition of images requires a particularly complex processing of information.

The problem proposed by the present invention is to considerably simplify the recognition of the shape of the cutlery, in order to carry out an almost instant sorting and over a short distance, while considerably simplifying the means necessary for the implementation of sorting and by reducing the cost of installation.

The invention allows sorting of cutlery by simple means that do not require video cameras and complex image processing means.

The invention aims to recognize the types of cover when they pass through a detection area.

According to an improved embodiment, the invention also aims to recognize not only the type of cutlery, but also the direction of the cutlery when they pass through the detection area, then making it possible to switch the cutlery into different compartments according to of their direction of progression, in order to place the sleeves in the same orientation in each compartment.

• - un plan support sensiblement parallèle à la direction de progression,
• - un plan de guidage latéral sensiblement parallèle à la direction de progression, et des moyens pour maintenir les couverts en appui contre le plan de guidage latéral pendant leur défilement dans l'aire de détection,
• - une pluralité de capteurs de présence de matière agencés pour détecter la présence de matière au regard d'une pluralité de zones de détection correspondantes du plan support dans l'aire de détection et pour produire des signaux de détection envoyés à un dispositif de traitement de signaux, ladite pluralité de capteurs comprenant au moins :
  • . un premier capteur C1 dont la zone de détection est positionnée par rapport au plan de guidage latéral à une distance D1 telle qu'il est activé lors du passage d'une grosse cuillère à l'exclusion des autres couverts,
  • . un second capteur C2 dont la zone de détection est positionnée par rapport au plan de guidage latéral à une distance D2 telle qu'il est activé lors du passage de tous les couverts à l'exclusion des couteaux,
• - un troisième capteur C3 dont la zone de détection est positionnée par rapport au plan de guidage latéral

à une distance D31 telle qu'il est activé lors du passage de tous les couverts, et positionnée par rapport à la seconde zone de détection du second capteur C2 et dans la direction de progression des couverts à une distance D32 telle qu'il est activé simultanément au second capteur C2 pendant une partie du parcours d'une fourchette et d'une grosse cuillère, et telle qu'il n'est à aucun moment activé simultanément au second capteur C2 lors du passage d'une petite cuillère.To achieve these and other objects, a sorting installation for community cutlery according to the invention comprises means for scrolling one by one the cutlery in a detection area in a direction and a direction of progression, and means to detect the type of cover which crosses the detection area, the detection area according to the invention, comprising:

• - a support plane substantially parallel to the direction of progression,
• a lateral guide plane substantially parallel to the direction of progression, and means for keeping the cutlery in abutment against the lateral guide plane during their travel in the detection area,
• - a plurality of material presence sensors arranged to detect the presence of material with regard to a plurality of corresponding detection zones of the support plane in the detection area and to produce detection signals sent to a device for processing signals, said plurality of sensors comprising at least:
  • . a first sensor C1, the detection zone of which is positioned with respect to the lateral guide plane at a distance D1 such that it is activated during the passage of a large spoon to the exclusion of other cutlery,
  • . a second sensor C2, the detection zone of which is positioned with respect to the lateral guide plane at a distance D2 such that it is activated during the passage of all the cutlery excluding the knives,
• - a third sensor C3 whose detection zone is positioned relative to the lateral guide plane

at a distance D31 as it is activated during the passage of all the cutlery, and positioned relative to the second detection zone of the second sensor C2 and in the direction of progression of the cutlery at a distance D32 as it is activated simultaneously with the second sensor C2 during part of the course of a fork and a large spoon, and such that it is at no time activated simultaneously with the second sensor C2 during the passage of a small spoon.

Such an installation makes it possible to detect the type of cover for communities, between knives, forks, large spoons and small spoons. It is also possible to detect the direction of certain covers, but detecting the direction of all covers requires additional sensors.

• - simultanément au troisième capteur C3 pendant une partie du parcours d'un couteau,
• - simultanément au second capteur C2 et au troisième capteur C3 pendant une partie du parcours d'une fourchette.

According to an improved embodiment, the installation comprises a fourth sensor C4 whose detection zone is positioned so that it is activated:

• - simultaneously with the third sensor C3 during part of the course of a knife,
• - simultaneously with the second sensor C2 and the third sensor C3 during part of the course of a fork.

• - les figures 1 à 4 illustrent de façon très schématique les formes générales de couverts de collectivités que l'on trie avec l'installation selon la présente invention ;
• - la figure 5 illustre en vue de dessus une vue générale d'une installation de tri selon un mode de réalisation de la présente invention ;
• - la figure 6 est une vue de dessus de l'aire de détection des couverts
• - la figure 7 est une vue de face de l'aire de détection de la figure 6 ;
• - la figure 8 est une vue de dessus d'une aire de détection selon un autre mode de réalisation de la présente invention, montrant en outre les zones de positionnement des capteurs ; et
• - la figure 9 illustre le schéma électrique des organes de détection et de commande de l'installation selon la présente invention.

Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, given in relation to the attached figures, among which:

• - Figures 1 to 4 illustrate very schematically the general forms of cutlery communities that are sorted with the installation according to the present invention;
• - Figure 5 illustrates a top view of a general view of a sorting installation according to an embodiment of the present invention;
• - Figure 6 is a top view of the cutlery detection area
• - Figure 7 is a front view of the detection area of Figure 6;
• - Figure 8 is a top view of a detection area according to another embodiment of the present invention, further showing the positioning zones of the sensors; and
• - Figure 9 illustrates the electrical diagram of the detection and control members of the installation according to the present invention.

Figure 1 shows a top view of a collective fork, comprising a fork head 1 and a fork handle 2. The fork head 1 comprises teeth such as tooth 3, and a solid portion 4 of the fork head. A width IF of a fork is defined, which is the width of the head 1. A length LF of the full portion of the fork is also defined, as shown in the figure, which is the sum of the length of the handle 2 and the length of the solid part 4 of the fork head. Finally, define a width IMF of the fork handle.

FIG. 2 represents a top view of a large collective spoon, in which the width IGC of large spoon is defined, which is the width of the head 5 at the end of the handle 6.

FIG. 3 represents a collective knife, in which the width IMC of the knife handle is defined.

FIG. 4 represents a small collective spoon, in which there are the head 7, the handle 8, the length LPC of the small spoon, the width IPC of the small spoon or width of the head 7, and the width IMPC of the handle 8.

The object of the invention is to recognize the shape of these four cutlery, by simple means, according to the dimensions of the parts identified in the figures.

In an installation as shown in FIG. 5, the cutlery is placed on an inlet conveyor 9 possibly provided with known means for placing the cutlery one by one in a file in a longitudinal orientation in the direction of movement of the conveyor as shown by the arrow 10. The cutlery is thus brought one by one into a detection area 11, in which one recognizes their shape and possibly their direction. The cutlery then moves through a sorting area 12 provided with a series of sorting flaps such as the flap 13, each flap 13 being actuated by a drive device such as the device 14 controlled by a processing device for signals, the flap 13 being movable between a passage position in which the flap lets the cutlery pass along the sorting area to the next flap, and an interception position as shown in FIG. 5 in which the flap deviates the cover to a corresponding reception compartment 15. The embodiment of FIG. 5 represents seven reception compartments, each corresponding to a type among the four covers shown in FIGS. 1 to 4, and to a single orientation of this covered. In the same compartment such as compartment 15, all sorted cutlery is of the same type and is oriented with the handle in the same direction. The compartments can then be used directly for the presentation of cutlery in a self-service.

Figures 6 and 7 illustrate a detection area structure 11 according to an embodiment of the invention.

In this embodiment, the detection area comprises a support plane 16, parallel to the direction of progression 10 as shown in FIG. 5, and associated with a lateral guide plane 17 also parallel to the direction of progression 10, and for example vertical.

Means are provided for keeping the cutlery in abutment against the lateral guide plane 17 during their travel on the support plane 16 in the detection area 11. For example, these means consist in tilting the support plane 16 laterally so that it either in slope towards the lateral guide plane 17 as shown in FIG. 7. Thus, the cutlery slides by gravity on the support plane 16 and comes to bear against the lateral guide plane 17.

The detection area further comprises a plurality of material presence sensors, positioned in the detection area with respect to a plurality of corresponding detection areas of the support plane 16. Thus, in the embodiment of Figures 6 and 7, the detection area 11 comprises a first sensor C1, a second sensor C2 and a third sensor C3, arranged for example as shown in the figures.

The first sensor C1 is such that its detection zone is positioned relative to the lateral guide plane 17 at a distance D1 such that the sensor C1 is activated during the passage of a large spoon, and such that the sensor C1 is not not activated when passing a knife, fork or teaspoon.

The second sensor C2 is such that its detection zone is positioned relative to the lateral guide plane 17 at a distance D2 such that the second sensor C2 is activated during the passage of a small spoon, a large spoon or a fork, but is not activated when passing a knife.

The third sensor C3 is such that its detection zone is positioned relative to the lateral guide plane 17 at a distance D31 such that the sensor C3 is activated during the passage of all types of cutlery. In addition, its detection zone is positioned relative to the second detection zone of the second sensor C2, and in the direction of progression of the cutlery, at a distance D32 such that the third sensor C3 is activated simultaneously with the second sensor C2 for part of the course of a fork, and such that the third sensor C3 is at no time activated simultaneously with the second sensor C2 when passing a small spoon.

In practice, the conditions for positioning the sensors as defined above are achieved as a function of the dimensions of the cutlery which it is desired to sort. The community cutlery has generally little different shapes, in particular with regard to the stainless steel cutlery which is most generally used. We can first measure the maximum and minimum dimensions of all parts of the cutlery of a battery of cutlery that we want to sort with the device of the invention. When these dimensions are determined, it is easy to deduce therefrom, according to the invention, the positions which must be given to the sensors in the detection area 11 in order to sort with certainty all the cutlery from the cutlery battery.

Depending on the dimensions as illustrated in FIGS. 1 to 4, the choice of the positions of the sensors can thus be done as explained below.

• - supérieure à la plus grande largeur IF des fourchettes et IPC des petites cuillères dans l'ensemble des couverts à trier,
• - inférieure à la plus petite largeur IGC des grosses cuillères dans l'ensemble des couverts à trier.

The detection zone of the first sensor C1 must be located at a distance D1 from the lateral guide plane 17, said distance D1 being:

• - greater than the greatest width IF of the forks and IPC of the small spoons in the set of cutlery to be sorted,
• - less than the smallest IGC width of the large spoons in all of the cutlery to be sorted.

• - supérieure à la plus grande largeur de manche IMF des fourchettes et IMC des couteaux et des grosses cuillères dans l'ensemble des couverts à trier,
• - inférieure à la plus petite largeur IF des fourchettes et IPC des petites cuillères dans l'ensemble des couverts à trier.

The detection zone of the second sensor C2 must be located at a distance D2 from the lateral guide plane 17, said distance D2 being:

• - greater than the largest IMF handle width of the forks and BMI of knives and large spoons in all cutlery to be sorted,
• - less than the smallest width IF of the forks and IPC of the small spoons in all the cutlery to be sorted.

• - par rapport au plan de guidage latéral 17, à une distance D31 inférieure à la plus petite largeurde manche IMF des fourchettes dans l'ensemble des couverts à trier,
• - par rapport à la zone de détection du second capteur C2, à une distance D32 supérieure à la plus grande longueur LPC des petites cuillères et inférieure à la plus petite longueur LF de partie pleine des fourchettes dans l'ensemble des couverts à trier.

The detection area of the third C3 sensor must be located:

• - relative to the lateral guide plane 17, at a distance D31 less than the smallest width of the IMF handle of the forks in the set of cutlery to be sorted,
• - relative to the detection zone of the second sensor C2, at a distance D32 greater than the longest length LPC of the small spoons and less than the shortest length LF of the full part of the forks in all of the cutlery to be sorted.

The sensors C1, C2, C3 are thus positioned in positioning zones as shown in FIG. 8: considering that the sensor C2 is fixed, the sensor C1 can be moved in a longitudinal strip 18 parallel to the lateral guide plane 17, said strip 18 being defined by the two limit values of the distance D1 relative to this lateral guide plane 17, the strip being able to have the same length as the detection area 11. The sensor C3 can be placed in an area rectangular 19 defined by the limit values of the distance D31 and the distance D32.

• - simultanément au troisième capteur C3 pendant une partie du parcours d'un couteau dans l'aire de détection 11,
• - simultanément au second capteur C2 et au troisième capteur C3 pendant une partie du parcours d'une fourchette dans l'aire de détection 11.

In the embodiment shown in FIG. 8, the detection area 11 also includes a fourth sensor C4, the detection area of which is positioned so that it is activated:

• - simultaneously with the third sensor C3 during part of the path of a knife in the detection area 11,
• - simultaneously with the second sensor C2 and the third sensor C3 during part of the course of a fork in the detection area 11.

This second embodiment makes it possible to recognize not only the type of cutlery, but also the direction of the forks, large spoons and small spoons. Only the direction of the knives is not detected by this device. The detection of the direction of knife orientation requires an additional device, not shown in the figures.

• - par rapport au plan de guidage latéral 17, à une distance D4 inférieure à la largeur la plus petite de manche de tous les types de couverts dans l'ensemble des couverts à trier,
• - par rapport au plan de guidage latéral 17 et à la zone de détection du troisième capteur C3, dans une plage occupée par la partie pleine 4 de tête 1 de fourchette lorsque l'extrémité de son manche est en regard du troisième capteur C3.

In practice, the detection zone of the fourth sensor C4 can be located:

• - relative to the lateral guide plane 17, at a distance D4 less than the smallest handle width of all types of cutlery in the set of cutlery to be sorted,
• - relative to the lateral guide plane 17 and to the detection zone of the third sensor C3, in a range occupied by the solid part 4 of the fork head 1 when the end of its handle is opposite the third sensor C3.

Thus, as shown in FIG. 8, the area 20 in which the fourth sensor C4 must be located is limited by a first segment 21 perpendicular to the lateral guide plane 17, a second adjacent segment 22 parallel to the lateral guide plane 17, and a curved arc 23 connecting the ends of the two segments 21 and 22 to form a curvilinear triangle as shown in FIG. 8.

As shown diagrammatically in FIG. 7, each sensor such as the sensors C1, C2, C3 or C4, can advantageously be an optical sensor with beam interruption. Each sensor comprises, with regard to the detection zone, a transmitter such as the respective transmitters E1, E2, E3 of the first three sensors, and comprises, placed opposite the corresponding transmitter, a receiver such as the respective receivers R1, R2 and R3 of the first three sensors. For example, the receivers are placed above the detection area 11, facing the corresponding detection zone, while the transmitters E1, E2, E3 are incorporated in the support plane 16 in said corresponding detection zone. The light beam such as the beam 24 of the sensor C1 is cut off when the corresponding cover passes, such as a large spoon, the corresponding receiver R1 then producing an electrical signal sent to a signal processing device.

FIG. 9 illustrates the electrical connection diagram between the sensors and the sorting flaps. There are thus the four sensors C1, C2, C3 and C4, the outputs of which are connected to four corresponding inputs of a signal processing device 25. The signal processing device can advantageously be an automaton programmed to recognize each of the sequences different from signals emitted by the sensors C1, C2, C3 and C4 during the passage of the cutlery in the detection area 11, and to emit a separate indication or command signal for each recognized sequence. In the embodiment shown, the signal processing device 25 or programmed automaton thus comprises a plurality of separate outputs each connected to a drive device actuating an associated sorting flap. There is thus an output connected to the drive device 14 which actuates the sorting flap 13. There is a number of outputs and a number of driving devices and sorting flaps corresponding to the number of different sequences that the device can recognize processing signals 25 as a function of the signals emitted by the sensors C1, C2, C3 and C4.

Thus, in the embodiment of FIG. 6, with three sensors C1, C2 and C3, it is known to recognize all the pieces of cutlery without differentiating their direction. It is then possible to provide four outputs from the signal processing device 25, with four drive devices and four sorting flaps. The cutlery which has not been recognized according to one of the four possible sequences continues their progression to a terminal reception compartment 26 shown in FIG. 5, intended to contain defective cutlery, for example twisted cutlery which does not correspond more to one of the correct forms.

In the embodiment of FIG. 8, the four sensors make it possible to recognize the four pieces of cutlery, and the direction of orientation of the forks, small spoons and large spoons. Seven outputs of the signal processing device 25 can then be provided, with seven drive devices and seven sorting flaps.

By combining an additional device for recognizing the direction of the knives, it is then possible to add an eighth drive device and an eighth sorting flap.

In all cases, means are provided for scrolling the cutlery one by one in the detection area 11. It is possible to use various known means, for example driving rollers, support plane zones 16 made up of conveyor belts , an anteroposterior inclination of the support plane 16 for sliding the cutlery by gravity in the direction of progression 10, and generally all known means which do not disturb detection by the sensors.

• - largeurs :
  • . grosse cuillère 42 mm - 44,7 mm
  • . fourchette 25,2 mm - 27 mm
  • . petite cuillère 28 mm - 30,5 mm
  • . couteau 16,5 mm - 18,5 mm;
• - longueurs :
  • . grosse cuillère 187,5 mm - 207 mm
  • . fourchette 186 mm - 206 mm
  • . petite cuillère 130 mm - 140 mm
  • . couteau 202 mm - 219 mm
• - largeurs des manches :
  • . grosses cuillères 10,5 mm - 20,5 mm
  • . fourchette 10 mm - 20 mm
  • . petite cuillère 5 mm - 15 mm
  • . couteau 10,5 mm - 16,5 mm;
• - longueurs de partie pleine :
  • . des fourchettes 153 mm - 166 mm.

A conclusive test of an installation according to the present invention could be carried out on a population of cutlery of several types, the dimensions of which were included within the following limits:

• - widths:
  • . large spoon 42 mm - 44.7 mm
  • . fork 25.2 mm - 27 mm
  • . teaspoon 28 mm - 30.5 mm
  • . knife 16.5 mm - 18.5 mm;
• - lengths:
  • . large spoon 187.5 mm - 207 mm
  • . fork 186 mm - 206 mm
  • . small spoon 130 mm - 140 mm
  • . knife 202 mm - 219 mm
• - sleeve widths:
  • . large spoons 10.5 mm - 20.5 mm
  • . fork 10 mm - 20 mm
  • . teaspoon 5 mm - 15 mm
  • . knife 10.5 mm - 16.5 mm;
• - solid part lengths:
  • . forks 153 mm - 166 mm.

• D1 = 30 mm
• D2 = 20 mm
• D31 = 10 mm
• D32 = 140 mm
• D4 = 5 mm

les capteurs C4 et C2 étant sur la même perpendiculaire au plan du guidage latéral 17.An example of arrangement of the sensors for sorting such a population of covers was:

• D1 = 30 mm
• D2 = 20 mm
• D31 = 10 mm
• D32 = 140 mm
• D4 = 5 mm

the sensors C4 and C2 being on the same perpendicular to the plane of the lateral guide 17.

• - fourchette
• 
  - petite cuillère
  
• - couteau
  • C3
  • C3&C4
  • C4
• - grosse cuillère :
  

In this example, the signal sequences to be recognized by the signal processing device are as follows:

• - fork
• 
  - little spoon
  
• - knife
  • C3
  • C3 & C4
  • C4
• - large spoon:
  

It has been noted that the device according to the invention allows reliable sorting even when the sorted cutlery has common deformations which do not hinder their use. While being particularly simple, this device thus has a great tolerance for common deformations of cutlery as found in community kitchens.

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations contained in the claims below.

Claims (10)

1 - Sorting facility for institutional cutlery, comprising: - means for scrolling one by one the cutlery in a detection area (11) in a direction (10) and a direction of progression, - means for detecting the type of cover which crosses the detection area (11), characterized in that the detection area comprises: - a support plane (16) substantially parallel to the direction of progression (10), - a lateral guide plane (17) substantially parallel to the direction of progression (10), and means for keeping the cutlery in abutment against the lateral guide plane (17) during their travel in the detection area (11) , - a plurality of material presence sensors arranged to detect the presence of material with regard to a plurality of corresponding detection zones of the support plane (16) and to produce detection signals sent to a signal processing device (25 ), said plurality of sensors comprising at least: . a first sensor C1, the detection zone of which is positioned with respect to the lateral guide plane (17) at a distance D1 such that it is activated during the passage of a large spoon to the exclusion of other cutlery, . a second sensor C2, the detection zone of which is positioned with respect to the lateral guide plane (17) at a distance D2 such that it is activated during the passage of all the cutlery excluding the knives, . a third sensor C3, the detection zone of which is positioned relative to the lateral guide plane (17) at a distance D31 such that it is activated during the passage of all the cutlery, and positioned relative to the second zone of detection of the second sensor C2 and in the direction of cutlery progression at a distance D32 such that it is activated simultaneously with the second sensor C2 during part of the course of a fork and a large spoon, and such that it is not at no time activated simultaneously with the second sensor C2 when passing a small spoon. 2 - Installation according to claim 1, characterized in that the detection zone of the first sensor C1 is located at a distance D1 from the lateral guide plane (17), said distance D1 being: - greater than the greatest width IF of the forks and IPC of the small spoons in the set of cutlery to be sorted, - less than the smallest IGC width of the large spoons in all of the cutlery to be sorted. 3 - Installation according to claim 1, characterized in that the detection zone of the second sensor C2 is located at a distance D2 from the lateral guide plane (17), said distance D2 being: - greater than the largest IMF handle width of the forks and BMI of knives and large spoons in all cutlery to be sorted, - less than the smallest width IF of the forks and IPC of the small spoons in all the cutlery to be sorted. 4 - Installation according to claim 3, characterized in that the detection zone of the third sensor C3 is located: - relative to the lateral guide plane (17), at a distance D31 less than the smallest width of the IMF handle of the forks in the set of cutlery to be sorted, - relative to the detection zone of the second sensor C2, at a distance D32 greater than the longest length LPC of the small spoons and less than the shortest length LF of the full portion (4) of the forks in all of the cutlery sort. 5 - Installation according to any one of claims 1 to 4, characterized in that it comprises a fourth sensor C4 whose detection zone is positioned so that it is activated: - simultaneously with the third sensor C3 during part of the path of a knife in the detection zone (11), - simultaneously with the second sensor C2 and the third sensor C3 during part of the course of a fork in the detection zone (11). 6 - Installation according to claim 5, characterized in that the detection zone of the fourth sensor C4 is located: - relative to the lateral guide plane (17), at a distance D4 less than the smallest handle width of all types of cutlery in the set of cutlery to be sorted, - relative to the lateral guide plane (17) and to the detection zone of the third sensor C3, in a range occupied by the solid part (4) of the fork head when the end of its handle (2) is opposite of the third sensor C3. 7 - Installation according to any one of claims 1 to 6, characterized in that each sensor (C1, C2, C3, C4) is an optical sensor with beam interruption, with a transmitter (E1, E2, E3) placed at with regard to the corresponding detection zone, and with a receiver (R1, R2, R3) placed opposite the corresponding transmitter in said corresponding detection zone. 8 - Installation according to any one of claims 1 to 7, characterized in that the support plane (16) is inclined in slope towards the lateral guide plane (17). 9 - Installation according to any one of claims 1 to 8, characterized in that the signal processing device (25) is an automaton programmed to recognize each of the different sequences of signals emitted by the sensors C1, C2, C3, C4 when passing the cutlery through the detection area (11), and to send a separate indication or command signal for each recognized sequence. 10 - Installation according to claim 9, characterized in that it comprises a sorting area (12) provided with a series of sorting flaps (13), each sorting flap being actuated by a drive device (14) controlled by the signal processing device (25), and being movable between a passage position in which the sorting flap (13) lets pass the cutlery and an interception position in which the sorting flap (13) deflects the covered to a receiving compartment (15).

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