EP1450310A1 - Module for fast weight determination - Google Patents

Abstract

The module has a weighing pan (18) which integrates a weighing cell and a motorized driving unit (22) for transport of a courier article from one end of the pan to another end. A detecting unit with Hall effect detector and an optical sensor detects size of the courier article. A processing unit calculates weight of the article in a determined weight interval obtained from the size.

Description

Field of the invention

The present invention relates to the specific field of mail processing. It particularly targets a weighing module dynamics of a mail processing machine inserted between a mail item supply module and a module postage for these items.

Prior art

Dynamic weighing modules intended to be used with franking machines are well known. French demand No. 2,388,352 illustrates a particular example. These devices are trained weighing pan and transport belts automatic mail items across the board. The weigh module can be used alone but is usually inserted in a set of mail processing between the entry of the module franking and the output of the power module from which are ejected closed envelopes to be franked.

In these devices, weighing is carried out on the fly, i.e. during the transfer of the envelope through the weighing module, and without interrupt the means of transport of this envelope. When the processing rates become important, i.e. in practice more than 8000 envelopes per hour (i.e. more than 2 envelopes each second), it appears that the weighing cannot be carried out without reducing the transport speed and therefore the general franking rate.

Object and definition of the invention

The invention proposes to overcome this drawback with a module for weighing implementing an improved weighing process allowing a processing envelopes on the fly with particularly high rates high, in particular at more than 8000 envelopes per hour. A goal of the invention is to allow this treatment without structural modifications of the weigh module.

These goals are achieved by a weigh module with a platform weighing scale incorporating a weighing cell and at least one strip motorized drive for transporting a mail item from a side to side of the weighing pan, characterized in that it includes means of detecting the format of this mail item and means of processing to calculate the weight of this mail item in an interval determined weight obtained from this format.

So with this predetermination of a weight interval in depending on the format of the envelope upon entering the weighing module, it is possible to significantly speed up the measurement of the actual weight of the envelope and therefore obtain this weight value before it leaves the weighing module and without reducing the transport speed of this envelope.

The format detection means include a means of detecting the length of this mail item, a means of detecting the thickness of this mail item and a means of detecting the width of this mail item. Preferably, said means for detecting the length of the mail item includes a blackout flag, said flag means for detecting the thickness of the mail item comprises a Hall effect detector and said article width detection means mail has an optical sensor.

The processing means include an amplification chain a measurement signal supplied by said load cell, the gain of which varies selectively based on the format of the mail item.

Brief description of the drawings

• la figure 1 représente une vue de dessus d'un module de pesée selon l'invention,
• la figure 2 est une vue en coupe longitudinale du module de pesée de la figure 1, et
• la figure 3 illustre la structure matérielle du circuit de commande du module de la figure 1.

Other characteristics and advantages of the present invention will emerge more clearly from the following description, given by way of non-limiting illustration, with reference to the appended drawings, in which:

• FIG. 1 represents a top view of a weighing module according to the invention,
• FIG. 2 is a view in longitudinal section of the weighing module of FIG. 1, and
• FIG. 3 illustrates the hardware structure of the control circuit of the module of FIG. 1.

Detailed description of a preferred embodiment

A mail processing machine conventionally comprises at less, arranged from upstream to downstream relative to the direction of advance of the mail items, a mail item supply module 10, a dynamic weighing module 12 and a franking module 14. Each of these elements is linked to the previous one by a computer link 16A, 16B.

Such a machine can frank mail items from different formats, from the American format N ° 5 (76.2mm * 127mm) up to European format b4 (250mm * 353mm) through the format European C6 / 5 (114mm * 229mm) and this up to a determined thickness, for example 16 mm, corresponding to the height of the insertion slot mail items in the feeder.

In accordance with Figures 1 and 2, the weighing module 12 comprises a weighing plate 18 with its weighing cell 20 and a single belt or drive belt 22 for transporting mail items from a edge to edge of this plateau, more precisely from a position upstream of this platform, at an upstream transverse face 24 of the weighing platform, towards a downstream position, at a downstream transverse face 26 of this tray. These conveyor belts are powered by a motor 28, advantageously of the electric type, actuated from processing means 30, advantageously comprising a circuit microprocessor, which also manages the information passing through the computer links.

A device for holding mail items intended to tackle these items on the weighing pan during transport include example three support elements arranged one behind the other in the direction of transport of mail items and each formed by an arm holding 32, 34, 36 at the lower end of which a flap 38 is fixed, 40, 42 or any other similar flexible pressure means (brush, roller, roller) whose length is relatively large to exert a force sufficient pressure on the mail item. These supporting elements are mounted perpendicular to a longitudinal vertical wall 44 for placing with reference to mail items.

The motorized drive belt 22 has a width at least equal to that of the bib or elastic pressure means, so optimize the guidance and lateral wedging of mail items, advantageously favored by its inclination towards the longitudinal wall of reference of a determined angle with respect to the direction of transport of mail items. The value of this angle depends in particular on the length of the weigh module. For a weigh module with a weighing pan weighing 60 cm long on which three support elements fitted each of an 8 cm wide flap, this angle is approximately 2.5 °.

The weighing module also incorporates a series of rollers transport 46, 48 arranged at the input of the module at its face upstream transverse 24 and intended to ensure an extraction of the articles of mail ejected from the feed module 10. Depending on the configuration of the mail processing machine, these rollers can sometimes be present directly at the output of the power supply module.

According to the invention, the weighing module comprises at its level input of the format detection means 50 connected to the processing 30 and making it possible to provide it with data relating to the thickness, the length and width of this mail item.

These format detection means include a flag blackout 52 for measuring the length of mail items advantageously disposed between the drive rollers and actuated by the front and rear end of mail items, an optical sensor 54 for measuring the width of mailpieces and an effect detector Hall 56 for the measurement of the thickness of these mail items.

It is important to note that, if in the example illustrated, these means format sensors are arranged in the weighing module, they are not in no way of an obligation and that, due to the computer link 16A existing with the power module 10, it is perfectly conceivable that the corresponding data be provided directly by this module when it has it by construction.

Figure 3 shows in more detail the material structure of the means processing 30 connected to the load cell 20 which delivers a signal analog measurement V1 proportional to the force exerted on its gauges internal constraints. Signal V1 is amplified in a gain amplifier variable 60 which delivers an amplified signal V2 which has passed through a low pass filter 62 to eliminate the high frequency components (which also acts as an anti-aliasing filter) and at the output of which is available a filtered signal V3. This filtered signal is then sampled in an analog / digital converter 64 which delivers a series of Vi samples for a microcontroller circuit 66 which is responsible for process these digital signals to develop a weight value P which is then transmitted to the machine through the computer link 16B to work out the postage amount. This microcontroller 66 which conventionally comprises computing means and memory means also receives, from the various detectors 52, 54, 56, the information relating to the size of the envelopes to be weighed which, if necessary (a simple counter is sufficient for length measurement), will have been previously digitized by a second analog / digital converter 68. The sampling frequency Fi of the two converters, which can be identical or not, is developed by circuit 66 from its clock internal. Note however that the presence of the second converter 68 is of course only justified if the signals supplied by the detectors are analog type.

The processing means 30 also comprise at the level of its microcontroller 66 software means for prior to the determination of the weight P of a mail item, predetermine a likely weight range for this mail item based on format of this mail article when it is introduced in the module weighing 12.

Indeed, the inventors have found that knowing the format of a mail item made it possible to approach its weight and that therefore this finding made it possible to considerably simplify the measurement of this weight by limiting the measurement range and therefore accelerating this measurement. . The table below shows the dimensions (width, length) of the different envelopes used in Europe. A similar table, of course with different values, exists for envelopes issued from the United States. Type of envelope width Length C7 81 mm 114 mm C7 / 6 81 mm 162 mm C6 114 mm 162 mm B6 125 mm 176 mm E6 140 mm 200 mm DL 110mm 200 mm C6 / 5 114 mm 229 mm C5 162 mm 229 mm Italian 110 mm 230 mm B5 176 mm 250 mm E5 200 mm 280 mm 1 / 2bc4 125 mm 324 mm C4 229 mm 324 mm B4 250 mm 353 mm E4 280 mm 400 mm C4 pocket 324 mm 229mm

For each of these types of envelopes, the inventors established a curve showing the evolution of the weight of this envelope as a function of its thickness (up to a thickness of 16 mm) when filled with documents of standard grammage. and closed. The following table shows an extract of the results of these measurements, corresponding respectively to the envelopes DL, C5 and C4 pocket for four different thicknesses, the first corresponding to a maximum admissible thickness for this envelope (beyond a closure becomes difficult without rupture) and the the latter being relative to a minimum thickness corresponding to the insertion of a single document per envelope. Type of envelope Measured thickness Weight lifted 324mm * 229mm (C4p) 16 mm 750 g 8 mm 360 g 2 mm 100g 1 document inserted 20g 162mm * 229mm (C5) 10 mm 240g 6 mm 145g 2 mm 55g 1 document inserted 10g 110mm * 220mm (DL) 6 mm 90 g 4mm 50g 2 mm 30g 1 document inserted 10g

Knowledge of the format of the mail item to be weighed determines a likely weight range for this item and adjust the gain of the variable gain amplifier 60 accordingly so as to ensure maximum excursion for the converter analog / digital 64 and therefore benefit from its full resolution.

The operation of the weighing module is as follows. The process measurement begins with the passage of the front front of the mail item, leaving the power supply module 10, on the length detector 52. This passage gives indeed the starting point for the measurement of the length of this article but also its thickness by the detector 56 and its width by the detector 54. In practice, the sample recording sequence from the thickness and width sensors does not start immediately at passage of the occulting flag 52 but a few millimeters after (by example 20 mm) to take into account the non-linear shape of this flag. This registration process continues during the advancement of the article. mail on the weighing pan 18 and its transfer to the module franking 14, but over a determined distance (for example 70 mm) less than the shortest envelope length (that of C7 format), for measuring this thickness and width. So these measures thickness and width are finished when the rear edge of the article of mail goes over the occulting flag which resumes its position of initial rest, this passage putting an end to the measurement of the length of the mail article. This passage also gives the start signal for the actual weighing, subject as previously to an offset of precaution of 20 mm for example. A statement can then be made series of samples from the load cell 20 through the chain amplification whose gain will have been adapted beforehand by the microcontroller 66 depending on the format of the mail item to be weighed obtained from the above three measurements. The sampling frequency determine the number of samples taken from which will be calculated the weight of the mail item. Adaptation of the gain of the chain amplification always allowing converter operation with maximum resolution, the measurement accuracy obtained is particularly high over the entire weight range of the weigh module.

Of course, the present invention cannot be limited to only format detection means described in this application and any other similar device allowing the desired measurement is possible. So, measurement of the length of mail items can also be carried out simply by an optical measuring device and the thickness measurement of these items by a probe for example. Similarly, if the module illustrated does not has only one motorized drive belt, it is of course possible to consider a module comprising several of these strips of width then reduced proportionally.

Claims (6)

Weighing module comprising a weighing pan (18) incorporating a weighing cell (20) and at least one motorized drive belt (22) for transporting a mail item from one edge of the pan to the other weighing machine, characterized in that it comprises means (50) for detecting the format of this mail item and processing means (30) for calculating the weight of this mail item in a determined weight interval obtained from of this format. Device according to claim 1, characterized in that said format detection means comprise a means for detecting the length of this mail item, a means for detecting the thickness of this mail item and a means for detecting the width of this mail item. Device according to claim 2, characterized in that said means for detecting the length of the mailpiece comprises a blanking flag (52). Device according to claim 2, characterized in that said means for detecting the thickness of the mailpiece comprises a Hall effect detector (56). Device according to claim 2, characterized in that said means for detecting the width of the mailpiece comprises an optical sensor (54). Device according to claim 1, characterized in that said processing means comprise an amplification chain (60) of a measurement signal supplied by said weighing cell, the gain of which varies selectively as a function of the format of the mail item .

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