EP0676718A1 - Arrangement for optically counting stacked products - Google Patents

Abstract

The counting device comprises a support on which a bar (2) can be placed containing a stack of products to be counted. the bar is illuminated by a fluorescent tube, and the reflected light is collected by first (5) and second 96) mirrors. the light is focussed on to a linear bar of photosensitive elements (41) associated with a camera (4). The bar may include, for example, 5000 sensitive elements so that it can be used to detect the presence of up to 500 products stacked in the supporting bar (2). Each element of the detector is able to determine the intensity of incident light on a 256 level scale. <IMAGE>

Description

The present invention relates to a device for counting thin products stacked side by side.

It is known devices for counting products by matrix camera requiring the implementation of a calibration procedure, thus resulting in a complex and expensive device.

The object of the invention is therefore to propose a counting device which is simple and inexpensive and allows the reading of the products stored in batches under a translucent shrink film.

• des moyens d'éclairer la barquette ;
• des moyens de détecter la mise en place d'une barquette sur une navette mobile animée d'un mouvement de déplacement ;
• des moyens d'effectuer une pluralité de balayages de la barquette par un faisceau linéaire de lecture d'une caméra linéaire pendant le mouvement de déplacement de direction perpendiculaire au faisceau linéaire ;
• des moyens de mémorisation des informations lumineuses contenues dans le faisceau linéaire et
• des moyens de comptage pour chaque balayage du nombre de produits.

This object is achieved by the fact that the device for counting thin products stacked side by side and stored on the field in trays packed in translucent shrink film is characterized in that it comprises:

• means for illuminating the tray;
• means for detecting the placement of a tray on a mobile shuttle animated by a movement of displacement;
• means for carrying out a plurality of scans of the tray by a linear reading beam from a linear camera during the movement of movement of direction perpendicular to the linear beam;
• means for memorizing the light information contained in the linear beam and
• counting means for each scan of the number of products.

According to another particular feature, the movement of movement of the shuttle is a reciprocating movement obtained by an electric motor whose drive shaft is connected by a mechanism for transforming the rotary movement into linear movement transmitted to the shuttle made integral with linear guide columns.

According to another particular feature, the movement of the tray is obtained by a cleat belt supporting a plurality of trays driven in a continuous movement of direction transverse to the linear reading beam.

According to another particularity, a push button actuable by the user triggers a movement and during this movement the plurality of scans.

According to another particular feature, the storage means consist of as many memory bytes as photosensitive elements of the read bar of the camera.

According to another particularity, the number of photosensitive elements is at least greater than twice the maximum number of objects that the device can count.

According to another particular feature, the number of photosensitive elements is preferably equal to ten times the maximum number of objects that the device can count.

In another feature, the linear beam is returned by a plurality of mirrors to ensure with a compact device the scanning of a large container.

According to another particular feature, each photosensitive element allows the detection of 256 brightness levels translated into words of one byte constituting the representation of a pixel.

According to another particularity, the counting means allow the alternating detection of vertices and valleys starting with a vertex detection and the counting of the vertices and valleys constituting the stored sinusoidal signal representative of the linear beam.

According to another particularity, the detection of the vertices ensures the detection of the first edge and the determination of the vertices by measuring the distance between the previous vertex and the pixel being processed and by comparing the distance with a minimum value which corresponds to l thickness of a product and also includes a step of calculating the percentage of variation of the top which makes it possible, in the event of the percentage being exceeded relative to a set value, to determine the presence of an edge.

According to another particular feature, the detection of the valleys is carried out with respect to the previous memorized vertex by measuring the distance between the vertex and the processed pixel and with respect to the previous memorized valley by measuring the distance between the valley and the treated pixel and retaining the pixel as forming a valley if the two distances are correct with respect to reference values and, if not, by processing the next pixel.

• la figure 1 représente une vue en perspective du principe mécanique et optique de la machine de comptage ;
• la figure 2 représente une vue schématique de côté du principe mécanique de la machine ;
• la figure 3 représente l'organigramme représentatif du déroulement de l'opération de comptage ;
• la figure 4 représente l'organigramme représentatif du traitement d'une ligne ;
• la figure 5 représente l'organigramme représentatif du processus de localisation des bords de la boîte contenant les produits ;
• la figure 6 représente l'organigramme représentatif du processus d'analyse et de comptabilisation des produits ;
• la figure 7 représente l'organigramme représentatif du processus d'analyse et de traitement des résultats ;
• la figure 8 représente une vue schématique de côté d'une autre variante de principe mécanique de la machine ;
• la figure 9 représente la forme du signal en sortie des éléments photosensibles et mémorisé sous forme d'octets dans la mémoire de la caméra.

Other particularities and advantages of the present invention will appear more clearly on reading the description below of an embodiment given by way of example and made with reference to the appended drawings in which:

• Figure 1 shows a perspective view of the mechanical and optical principle of the counting machine;
• Figure 2 shows a schematic side view of the mechanical principle of the machine;
• FIG. 3 represents the flowchart representative of the progress of the counting operation;
• FIG. 4 represents the flowchart representative of the processing of a line;
• FIG. 5 represents the flowchart representative of the process of locating the edges of the box containing the products;
• Figure 6 shows the representative flowchart of the product analysis and accounting process;
• FIG. 7 represents the representative flowchart of the process of analysis and processing of the results;
• FIG. 8 represents a schematic side view of another variant of the mechanical principle of the machine;
• FIG. 9 represents the shape of the signal at the output of the photosensitive elements and stored in the form of bytes in the memory of the camera.

The invention will now be described in conjunction with Figures 1 to 9 and in particular with Figures 1 and 2 which show the mechanical part consisting of a support (81, Figure 2) on which can be placed trays (2) containing a stack (1) of products such as magnetic or chip cards, access badges, tickets, bundles of paper, envelopes, etc., the batch of product being wrapped in a translucent shrink film not shown.

The tray (2) is lit by a fluorescent tube (7) and the light beam reflected on the edge of the objects (1) to be counted and sent to a reflection device comprising a first mirror (5) and a second mirror (6) for converging the beam on a linear strip (41) of photosensitive elements belonging to a camera (4). The beams (32, 31, 30) represent the light beam which converges towards the array of photosensitive elements (41). This bar (41) comprises, for example, 5000 elements to allow the reading of a tray containing, for example, at most 500 products. Each photosensitive element of the strip makes it possible to detect a light signal and to express this signal in the form of an electrical signal representative of 256 levels of brightness. This signal is translated into words, for example, of 8 bits and each word is recorded in a memory element of the device. Thus, the memory of the device consists, for the example given, of a random access memory of 5000 words of one byte. The plane light beam (30) represents a scan and the device allows the camera to perform a plurality of scans transverse to the movement of the tray (2) represented by the arrows A and B and provided by a mechanism shown, for example, in Figure 2. This mechanism consists of a support (81) made integral with two columns (84) mounted sliding each in two bearings mounted on legs (82, 83). At least one of the columns (84) has a deflection piece (85) which makes it possible to transform a rotational movement imparted by an electric motor (86) into a linear movement communicated to the columns (84). The purpose of this device is to ensure a back and forth movement which allows each cycle triggering caused by the depressing of a push button not shown and arranged on the cover of the machine, to have the tray (2 ) a back and forth movement, as shown in FIG. 1. A switch (91) makes it possible to detect the presence of a tray (2) and to validate the reading sequences carried out during the plurality of scans as well as the counts some products.

As will be seen hereinafter, the camera (4) performs during a forward movement about fifty scans, carried out alternately from left to right and from right to left and during the return movement another fifty alternating scans. As shown in FIG. 9, at each scan, the light signal recorded by the photosensitive elements is constituted by a sinusoidal signal the vertices of which represent approximately the mediums of the products, the valleys, the edges and the distance separating two valleys corresponds to the thickness of a product to be counted. The first vertex of coordinates ys0 corresponds in fact to a detection edge of the tray while the first vertex ys1 corresponds to the first product to be counted.

Between scan N ° 1 and scan N ° 2, a microprocessor device controlled by a program implementing the algorithms described below makes it possible to process the information stored during the first scan before validating the storage of a second scan, shown in Figure 9.

The program for reading the stored scans and counting the products corresponds to the implementation of the algorithms shown in FIGS. 3 to 7. In FIG. 3, after the start of the cycle detected by the pushing of the push button by the user, represented in step (30), the program performs the processing of a line represented in step (31) and after this line processing performs in step (32) a test to determine whether a determined number of lines , for example, were scanned, shown. If not, the result is stored in step (33) and if so, the program jumps to step (34) which is a test to determine whether it is an end of cycle. If the test is negative, the program loops before step (31). In the case where the test is positive, that is to say if the scan counter indicates that the determined number of linear scans has been carried out, the program continues with step (35) which is a processing step results. The next step (36) is constituted by the display of the report. A test, represented in step (37), makes it possible to know whether it is necessary to carry out a following cycle. If not, the program loops back on itself between steps (36) and (37) and if it does, the program loops back to cycle start. This "next cycle" test consists of detecting that the push button has been pressed. The line processing step (31) corresponds to the succession of steps represented in FIG. 4 and this sequence begins with a step of reversing the scanning direction (312) and continues with a step (313) of testing on determining the meaning. In the case of a scanning from left to right, the filling of the line memory is carried out in step (314) and in the other case of scanning right to left, the filling of the line memory is also carried out by a step (316).

Each of these memory filling steps is followed by a step (317) of finding the edges of the tray and by this step is followed by a step (318) of analysis and accounting of the products between the edges. The program ends with the processing of the results represented in step (319) for each of the lines. The edge search sequence represented by step (317) and the steps of which are shown in FIG. 5. This sequence begins with a step 51 of incrementing a "pixel" image point pointer making it possible to determine whether the we are at the beginning or at the end of the stored information corresponding to each of the photosensitive cells of the line. When the processing of 5000 memory words is finished, the processing of a line memory is carried out.

This step is followed by a step 52 of loading the reference value which is equal to the value of the pixel whose processing is in progress. This information consists of an 8-bit word representative of one of the 256 brightness levels received by the photosensitive element corresponding to the word memory processed.

This step is followed by a step 53 for local search for vertices which is continued by a step 54 for calculating the difference between the local level and the reference value stored in step 52.

This step 54 is followed by a step 55 of testing the value of the difference to determine whether this difference is greater than a set value. If so, the program knows in step 59 that an edge has been found. If not, the program continues with the step 56 of storage as the reference pixel of the pixel being processed.

This step is followed by a test step 57 determining whether it is the end or the beginning of a line by comparing the counter of the pixel pointer to determine whether it has reached the defined value set at 5000 for the example, or not. In the affirmative, the program displays "edge not detected" in step 58 by positioning a semaphore used in step 75 of FIG. 7, and in the negative the program loops before step 53 of search for local vertex .

The setpoint of step 55 generally corresponds to the distance which separates on average a summit of a valley and, as can be seen in the diagram in FIG. 9, the program in FIG. 5 makes it possible to detect as an edge the vertex Ys0 then, as we will see later, during the processing of the valley, noticing that the distance d1 between the summit and the next valley being less than another setpoint and the percentage of variation of the vertices being greater than one determined value, it considers that it is not the edge of the tray and detects the next vertex YS1 as being the effective edge of the tray.

The sequence 318 for analyzing and counting the products between the edges corresponds to the steps represented in FIG. 6 which begin with a step (61) for reading a pixel and then continue with a step 62 for testing on the type of sequence . This test is carried out by determining whether the difference between the pixel being processed and the previous pixel is positive or negative and, if it is positive, triggers the local top processing sequence and if it is negative triggers the local valley processing sequence. The local vertex processing sequence begins with a step 63 for measuring the distance (dss) between vertices and continues with a test step 64 to determine if this distance (dss) is greater than a minimum value. In the negative case, the program continues with step 641 of processing the next pixel and loops back between steps 61 and 62 of testing the type of sequence. In the affirmative case, if the distance (64) is greater than the minimum distance, the distance between vertices being represented on graph 9 by the value dss, the program continues with a step 65 of calculation of the percentage of variation of the vertices which determines the information (ys2 - ys1) x100 / ys1 and ensures in the next step 66 that this variation is greater than a setpoint or not. In the affirmative case, the program continues with a test step 691 to determine whether the variation is negative. if it is negative, the program loops before step 61 of reading a pixel. If the variation is positive, the program continues with a test step 692 consisting in reading the content of the counter for the number of products and in determining whether the content of this counter is less than 3. If the answer is negative, the program loops before step 61 of reading a pixel. If the answer is yes, the program continues with a step (693) of readjusting the edge, considering that the treated vertex is in fact the real edge of the tray. This corresponds exactly to the situation where at first the program has detected ys0 and then by detecting ys1 it finds that the variation for ys1 is greater than the setpoint of step 66 and then, verifying that the number of products is less than 3, it considers that ys1 is the real edge of the set of products to be counted. This step 693 allows at the same time positioning a semaphore which will be used in step 75 of the sequence in FIG. 7. If the variation is less than the setpoint, the program in step 67 validates the vertex by incrementing a counter which counts the vertices.

This step 67 is followed by a jump to the local valley sequencer, therefore returning the program before step 62 to process a local valley according to the sequence below. This processing always begins with the test (62) on the type of sequence and then continues with a step of measuring the summit-valley distance (dsv) and the valley-valley distance (dvv). This step 621 is followed by a test step 622 making it possible to determine whether the two distances are correct with respect to reference values. If not, the program continues with the processing of the next pixel represented in step 625 and loops back before step 62. If so, if the distances are correct the program continues with a step 623 of validation of the valley which consists of incrementing a valley counter. This step is followed by a step 623 of processing a local vertex by looping the program between steps 61 and 62.

After this sequence of analysis and accounting of the products for each scan where the number of products counted is stored in step 319 for each scan, the program executes a sequence (35) for processing the results. When the program has determined that it is an end of cycle step in step 34 of FIG. 3, it performs the sequence of processing of the results which corresponds to the sequence of steps of FIG. 7 During this processing, the program begins by carrying out a step 71 of sorting the results in ascending order and then constructs, at step 72, a histogram of the results and searches at step 73 for the largest occurrence between the results.

Thus, on the hundred scans, he will be able to determine for example, that the number 450 returns most often compared to the number 439, 440, 445, and retaining this number 450, he will examine in step 74 the rate of success compared to a benchmark rate value. In the treatment, a fairly high success rate was chosen but this instruction can possibly be modified. If for example the value 450 returns more than 7 times on 8 counts, the program considers that the reference rate value has been reached and the program will continue with a test step (75) to find out if there has been a good detection of extremities. This step 75 consists in reading the semaphore which will have been positioned during step 693 indicating that the edges have indeed been detected. In the negative case, step 751 signals a poor detection of the edges corresponding to step 50 and ends with the display (792) "no card found". If so, the sequence continues with a test step 76 on the detection of the saturation of the photosensitive sensors. If so, step 771 indicates that there is too much brightness and ends with a display "too much light", and if not the sequence continues with a processing step 77 constituting a test to determine whether the information read had good clarity. If not, the device displays a contrast defect and the sequence ends with a display "no card found", if so, the program ends with a test step 78 on the number of products to determine if this number is greater than zero. If so, the program ends with step 791 of displaying the number of products and the success rate.

FIG. 8 shows another variant of the device for mechanically moving the trays under the reading beam so as to be able to carry out a plurality of transverse scans with respect to the direction of movement of the trays (2). As can be seen, these trays (2) are mounted on a cleat belt (21) itself stretched between two drive pulleys (22, 23) at least one of which is rotated by an electric motor fed sequentially after processing the 100 scan lines or the desired number of scan lines to achieve a sufficient success rate.

Other modifications within the reach of the skilled person are also part of the spirit of the invention.

Claims (12)

Device for counting thin products (1) stacked side by side and stored on the field in trays (2) packed in translucent shrink film, characterized in that it comprises: - Means (7) for lighting the tray; - Means (91) for detecting the placement of a tray on a mobile shuttle (81, 21) driven by a movement of movement; - Means (4, 5, 6) for carrying out a plurality of scans of the tray by a linear reading beam from a linear camera during the movement of movement of direction perpendicular to the linear beam; means for memorizing the light information contained in the linear beam and - counting means for each scan of the number of products. Counting device according to claim 1, characterized in that the movement of movement of the shuttle is a reciprocating movement obtained by an electric motor whose drive shaft (80) is connected by a mechanism (85) of transformation of the rotary movement into a linear movement transmitted to the shuttle (81) made integral with linear guide columns (84). Counting device according to claim 1, characterized in that the movement of the tray (2) is obtained by a belt (21) with tabs supporting a plurality of trays driven in a continuous movement of direction transverse to the linear reading beam. Counting device according to one of claims 1 to 3, characterized in that a push button actuatable by the user triggers a displacement and during this displacement the plurality of scans. Counting device according to one of claims 1 to 4, characterized in that the storage means consist of as many memory bytes as photosensitive elements of a bar (41) for reading the camera. Counting device according to claim 5, characterized in that the number of photosensitive elements is at least greater than twice the maximum number of objects that the device can count. Counting device according to claim 5, characterized in that the number of photosensitive elements is preferably equal to ten times the maximum number of objects that the device can count. Counting device according to claim 5, characterized in that each photosensitive element allows the detection of 256 brightness levels translated into words of a byte constituting the representation of a pixel. Counting device according to one of claims 1 to 8, characterized in that the linear beam is returned by a plurality of mirrors (5, 6) to ensure with a compact device the scanning of a large tray. Counting device according to one of the preceding claims, characterized in that the counting means enable the vertices and valleys to be detected alternately, starting with vertex detection and the counting of the vertices and valleys constituting the stored sinusoidal signal representative of the beam. linear of a scan. Counting device according to one of the preceding claims, characterized in that the detection of the vertices ensures the detection of the first edge and the determination of the vertices by measuring the distance between the previous vertex and the pixel being processed, comparison of the distance with a minimum value which corresponds to the thickness of a product and a calculation of the percentage of variation of the vertex which allows, in the event of an overshoot with respect to a setpoint, to determine the presence of an edge. Counting device according to one of the preceding claims, characterized in that the detection of the valleys is carried out with respect to a previous vertex memorized by measuring the distance between vertex and processed pixel and with respect to the previous valley memorized by measuring the distance between the valley and the processed pixel and retaining the pixel as forming a valley if the two distances are correct with respect to reference values and, if not, processing the next pixel.

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