EP0714710B1 - Plastic envelope detector and flat article processing equipment including such a detector - Google Patents

Description

The invention relates to a device for discriminating a letter put in a paper envelope and a letter put in plastic envelope.

Some postal applications require barcode printing on envelope envelopes postal. It turns out that the mail to be processed by sorting machines is packed not only in an envelope paper but often also in an envelope plastic (transparent or not). It then arises on problem of printing bar codes on plastic envelopes because on this kind of medium, ink takes a long time to dry and bar codes prints are likely to rub off from envelopes on the organs of the sorting machine.

In order to avoid affixing on all the folds treated by postal sorting machine, labels with codes it was considered to discriminate envelopes in plastic and the paper envelopes so only one label is affixed to each envelope made of plastic.

The usual techniques of discrimination of these envelopes are based on an optical principle by reflection of a light ray and measurement of the energy reflected by the envelope to be checked. Plastic being more reflective than paper, discrimination is easy to enforce. However, these techniques no longer give complete satisfaction with the generalization of envelopes in colored and matt plastic material whose reflectance is very close to that of paper.

In fact, the mail processing equipment at broad spectrum include a labeling device operating to systematically affix a label on each fold processed which is extremely expensive.

The object of the invention is to remedy this disadvantage.

In particular, an object of the invention is to propose a device capable of discriminating, in real time, on a postal mail conveyor scrolling at a rate of approximately three folds per second, the folds having an envelope of material plastic, whether colored, mat or transparent and the folds with a paper envelope.

Another object of the invention is to propose such a discriminatory device that is simple to construction, reliable, robust and space-saving.

Yet another object of the invention is to provide a such a system of discrimination, the integration and maintenance inside a postal sorting machine is easy.

According to the invention, the device for discriminating a mail put in paper envelope and mail put in plastic envelope is characterized by a pneumatic system able to deform by suction a envelope to control and measure a pressure variation related to this deformation on the basis of which the envelope controlled is detected as a paper envelope or as plastic casing. In particular, the variation pressure is an increasing function of the deformation of the envelope.

La figure 1 est un synoptique général du dispositif selon l'invention.

La figure 2 montre, en perspective, une buse d'aspiration faisant partie du dispositif selon l'invention.

La figure 3 est un synoptique d'un circuit électronique faisant partie du dispositif selon l'invention.

La figure 4 montre une machine de tri postal incorporant le dispositif selon l'invention.

Le figure 5 montre une machine de tri postal équipée d'un dispositif de discrimination de plis par effet optique associé à un dispositif de discrimination de plis par effet pneumatique.

La figure 6 montre de façon plus détaillé l'agencement des deux dispositifs de discrimination de plis de la figure 5.

La figure 7 est un tableau résumant l'état de la commande d'un dispositif d'étiquetage faisant partie de la machine de tri postal de la figure 5.

Other characteristics and advantages will appear in the following description of an embodiment of the invention.

Figure 1 is a general block diagram of the device according to the invention.

Figure 2 shows, in perspective, a suction nozzle forming part of the device according to the invention.

Figure 3 is a block diagram of an electronic circuit forming part of the device according to the invention.

Figure 4 shows a postal sorting machine incorporating the device according to the invention.

FIG. 5 shows a postal sorting machine equipped with a ply discrimination device by optical effect associated with a ply discrimination device by pneumatic effect.

FIG. 6 shows in more detail the arrangement of the two fold discrimination devices of FIG. 5.

FIG. 7 is a table summarizing the state of control of a labeling device forming part of the postal sorting machine of FIG. 5.

Figure 1, the device for discriminating letters put in paper envelope and mail put in plastic envelope (hereinafter called "folds" paper "and" plastic folds ") mainly consists of a pneumatic system 1 which acts on each ply such as 2 to control to deform part of its envelope 3 and recover a pneumatic pressure quantity representative of the rigidity of this envelope on the basis of which fold 2 is detected as a plastic fold or like a paper fold. In this figure, fold 2 contains a mail c and scrolls flat on a plate 5 following a conveying direction indicated by arrow d, fold 2 being for example conveyed using strips, rollers pressers or the like not shown in the figure.

The pneumatic system 1 comprises a circuit air intake connected to a nozzle 5 whose air inlet 6 opens on the upper face of the plate on which moves fold 2 so as to exert a force suction or suction on the surface part of the envelope of the fold when it covers the air inlet of the nozzle.

More particularly, the nozzle 5 is provided with a cavity 6 visible in FIG. 2 and which has a shape substantially parallelepiped, the bottom of the cavity being open on a channel 7 crossing the nozzle 5 and connected to the suction circuit. The top of the cavity constitutes the air inlet of the nozzle and is spaced from the bottom of a height h by certain sides of the parallelepiped.

In particular, the nozzle 6 has a front edge following the direction d, which is closed to decrease the pressure losses of the cavity and a following rear edge this direction of which is open. By the way, the front front of nozzle 6 is chamfered to facilitate displacement of the fold 2 on the top of the nozzle.

Returning to FIG. 1, when the face of the fold 2 in contact with the plate 5 covers the cavity 6 of the nozzle, part of the envelope 3 of the fold is deformed by suction (part in dashes) and comes to close more or less the air inlet of the nozzle by decreasing the volume of the cavity 6 depending on whether the envelope is made of plastic or in paper. This results in a decrease in pressure in the air intake circuit, this decrease in pressure being dependent on the stiffness of the envelope and can be measured to detect the nature of fold 2 (paper fold or fold plastic).

According to the invention, a vacuum switch 8 is connected to the outlet of the air intake circuit to measure this pressure variation and deliver indicative information either the detection of a paper fold or the detection with a plastic fold. This is typically a sensor tire sold by COPAL under the reference PS4-102V-3 capable of measuring absolute pressure and compare the absolute pressure measured with a value of adjustable reference pressure PREF. If the pressure measured is smaller than the reference pressure, a fold plastic is detected and otherwise a paper fold is detected.

Indeed, a paper envelope is generally stiffer, thicker and rougher than an envelope made of plastic. As a result, a paper fold generates a lower pressure variation in the air suction circuit than a plastic fold because its envelope deforms less than that of the plastic fold.

Note that the height h of the cavity must be adapted to the texture of the envelope of the folds, but a height of about 3/10 of a millimeter for pressure suction at the outlet of the nozzle 5 of the order of 700 millibars is suitable for discriminating postal folds with a good detection rate of around 90%.

Also note that envelope 3 of the fold must be suitably pressed against the air inlet of the nozzle 5, while fold 2 can be conveyed at a speed of about 3 meters per second, this tackle can be obtained by the presence of a deflector, pressure roller or analog, which presses on the upper face of the fold in direction of stage 4 and near nozzle 5.

According to the invention, the air suction circuit includes a compressed air supply 9 connected to through a venturi 10 to nozzle 5 so as to create a vacuum at the outlet of the nozzle. Air supply 9 is connected to the venturi through a valve 11 left open to constantly operate nozzle 5 in suction, an air filter 12 and a pressure regulator 13 high precision with pressure gauge to regulate the pressure at the inlet of the venturi, for example at a level of approximately 0.7 bar.

A second air filter 14 is connected between the outlet of the venturi and the vacuum switch 8 to prevent fouling of this last.

According to the invention, an inverter 15 is provided for divert pressure air from regulator 13 directly to nozzle 5 so that it operates blowing, which helps facilitate cleaning to remove any dust that may collect inside its cavity 6 or its channel 7.

As part of the postal application, if the mail is detected as a plastic fold, an indexing label on which bar codes are printed is affixed on the face of the fold in a specific area (usually at midfoot of the fold).

If the fold is detected as a paper fold, the codes to bars are directly printed on the envelope in this specified area.

According to the invention, an electronic circuit 16 is intended to accumulate detection information delivered successively for sensor 8 for different positions of the fold to be checked in relation to nozzle 5 and compare the result of the accumulation at a preset threshold value, possibly adjustable, in order to decide if the fold checked is a paper fold or a plastic fold.

More particularly, the electronic circuit 16 works to raise the output of sensor 8 when the area determined of the fold to be checked passes over the nozzle 5. By making several measurement points, we get rid of measurement errors and the reliability of the device according to the invention.

Figures 1 and 3, a position sensor 17, for example an optoelectronic sensor, provides an indicative C signal detecting the presence of a fold 2 upstream of the nozzle following direction d.

The electronic circuit 16 includes a sequencer 161 which provides two clocks 162,163 each starting at time t0 defined as the time from which the start of the determined area of the fold faces the nozzle for make a first pressure measurement.

The sequencer 161 determines this instant t0 from the signal C, with a preset and adjustable delay value R on a data input device 165 and a data of offset D preset and adjustable on an input member of data 166. The delay value R corresponds to the time necessary for fold 2 to move from sensor 17 to nozzle 5. The offset value D corresponds to the time necessary for fold 2 to move from a position where its front edge is above nozzle 5 at one position where the start of the specified area is above this nozzle 5.

The clocks end at an instant t1 defined as the instant from which the end of the predetermined area begins located above nozzle 5. The sequencer 161 determines this instant t1 from instant t0 and a second offset value L preset and adjustable on a device data entry 167, this second corresponding value at the time required for fold 2 to move from position where the start of the specified area is above the nozzle 5 to a position where the end of the determined area is located above nozzle 5.

Figure 3, the clock 163 has several transitions during a single transition from clock 162: clock 162 indicates the beginning and the end of the sequence of accumulation of information from sensor 8 while clock 163 indicates the moments of acquisition of information in output from sensor 8 during this sequence.

Note that the acquisitions of information in exit of sensor 8 takes place while fold 2 moves on stage 4. Tests have been carried out with approximately hundreds of information acquisitions for a sequence accumulation. The result of the accumulation is then compared, in member 164, to a threshold value S preset and adjustable on a data entry device 168 on the basis of which a detection decision is rendered. For example, if organ 164 has accumulated 70 information indicative of a plastic fold detection on 100 measurement points for this fold and that the threshold S is set at 60, this body 164 decides that a plastic fold is detected. It is understood that the functions of the circuit electronics 16 can be performed programmatically without depart from the scope of the invention.

The device according to the invention is intended to be mounted in a postal sorting machine shown in Figure 4 which includes a destacker 41 of folds such as 2 (paper folds and plastic folds) separating the folds to provide them in series, an optical character recognition system 42 capable of read the mailing address characters on each fold provided by the destacker, a device for discriminating folds 43 paper and plastic folds that come with each fold controlled, information on the nature of the envelope of the fold, and a labeling device 44 which prints an index (bar codes) or affixes an indexing label to each fold according to the detection information provided by the device 43, after which each fold is referred to a mailing sorting carousel.

Therefore, when the discriminatory device 43 detects that the envelope of the checked fold is not in plastic, the labeling device 44 is ordered to print, directly an index on the envelope, i.e. is ordered so as not to affix a label on the envelope of this fold.

It is common for destackers to sort machines postal installation of air supply compressed. Therefore, the compressed air supply 9 required by the discriminator 43 according to the invention can come from the destacker 41 which contributes to an economy of means.

In addition, another device of discrimination operating on an optical principle can be added to the device 43 operating on a pneumatic principle for further increase the rate of good paper fold detection or plastic folds.

Note that the addition of a working detector by optical effect allows to extend the spectrum of folds processed by mail processing equipment, these folds which may include folds in a paper envelope with or without transparent window, folds in an envelope made of plastic or other flat articles. More particularly Figure 5, the discriminating device of flat articles consists of a first device for 43A discrimination operating by optical effect and a second discrimination device operating by effect pneumatic 43B (shown in more detail in Figure 6) which supply signals to a control unit, for example a microprocessor 45. On the basis of these signals, the unit or not prevents the affixing of a label on the controlled flat article following the logic diagram shown at Figure 7. Thus, a label is not affixed on the flat article (command worth 0 in the column "LABELING" in FIG. 7) when the two detectors 43A and 43B do not detect the presence of plastic (signals set to value 0 in the "DETECT OPT" columns and "DETECT PNEUM" in figure 7), the index being directly printed on the flat item in this case. A label is affixed to the flat article (order worth 1 in the column "LABELING") when one or both detectors 43A and 43B detect the presence of plastic material (one of the "DETECT OPT" or "DETECT PNEUM" signals set to 1), the index then being printed on the label.

The classic 43A optical discrimination device in itself is shown in Figure 6. It consists of a array of phototransistors 20 arranged transversely to the direction d under the plate 4 and operating with a incident lighting system 21. Electrical signals delivered by phototransistors are compared by a circuit 22 to an NREF threshold value whose level is set for recognize the presence of plastic. In particular, the presence of plastic is checked by device 43A in the index printing area on the face of a flat item like a paper envelope with transparent plastic window so that a label be affixed on the face of this envelope when the index printing area is precisely located on the transparent window of the envelope.

Such an arrangement therefore makes it possible to discriminate folds wrapped entirely in paper, folds wrapped in paper with a transparent window plastics, folds wrapped in material plastic, rigid plastic folds, etc.

This arrangement saves money important in the operating budget of an equipment mail processing including a device labeling when the proportion of envelopes folded entirely made of paper is large compared to others types of folds.

Note that the pneumatic system 1 of the discrimination 43.43B (except nozzle 5) can be advantageously deported near the apparatus pneumatic destacker 41 which limits the size of the sorting machine and simplifies its maintenance.

Claims (9)

1. A device for discriminating between mail in paper envelopes and mail in plastic envelopes, characterized by a pneumatic system (1) capable of deforming, by suction, an envelope (3) to be inspected and of measuring a variation in pressure resulting from this deformation on the basis of which the inspected envelope is detected as a paper envelope or as a plastic envelope.
2. The device according to Claim 1, in which the pneumatic system (1) comprises a suction nozzle (5) connected to an air suction circuit and mounted in a plate (4) on which the envelope to be inspected (3) lies flat, the nozzle having an air inlet forming a cavity (6) intended to be closed, at least in part, by the envelope (3) and a pressure sensor (8) being provided for measuring a variation in pressure in the suction circuit at the moment when the envelope closes said air inlet of the nozzle.
3. The device according to Claim 2, in which the air suction circuit comprises a compressed air feed (9) which creates a negative pressure at the outlet of the nozzle (5) by means of a venturi (10).
4. The device according to Claim 3, in which the compressed air feed (9) is connected to the outlet of the nozzle (5) via a reversing switch (15) which causes the nozzle to operate as a blower.
5. The device according to Claim 2, in which the pressure sensor (8) is a vacuum gauge adjustable to a reference pressure value (VREF) to deliver an item of information indicating detection of a plastic envelope or detection of a paper envelope.
6. The device according to Claim 5, comprising an electronic circuit (16) which accumulates items of information delivered successively by the pressure sensor (8) for different positions of the envelope (3) relative to the nozzle (5) and which compares the result of the accumulation with a preset threshold value to detect whether the inspected envelope is a plastic envelope or a paper envelope.
7. Equipment for processing flat articles, in particular mail items, including a labelling device (44) for affixing a label to a face of a flat article (2) to be processed, this label serving as a medium on which an indexing code is printed, and a discriminating device (43) according to one of the preceding claims for detecting whether a face of said flat article is made of plastic, the labelling device being prevented from affixing a label to the flat article to be processed when the discriminating device detects that the inspected face of this flat article is not made of plastic.
8. Equipment for processing flat articles, in particular mail items, including a labelling device (44) for affixing a label to a face of a flat article (2) to be processed, this label serving as a medium on which an indexing code is printed, a first discriminating device (43A), operating by an optical effect, for detecting whether an inspected face of a flat article to be processed is made of plastic, a second discriminating device (43B), operating by a pneumatic effect, according to one of Claims 1 to 6, for detecting whether the inspected face of said flat article is made of plastic, the labelling device being prevented from affixing a label to the flat article to be processed when said first and second discriminating devices (43A,43B) detect that the inspected face of this flat article is not made of plastic.
9. The equipment according to Claim 8, in which the first discriminating device (43A), operating by an optical effect, is arranged to detect the presence of plastic in the zone on said face of the flat article to be processed in which the indexing code is printed.

Images