WO2000057346A1

WO2000057346A1 - Device for recognizing objects

Info

Publication number: WO2000057346A1
Application number: PCT/NL2000/000194
Authority: WO
Inventors: Franciscus Gerardus Antonius Van Der Loo; Klaas Wubs
Original assignee: Beheermaatschappij Van Der Loo B.V.
Priority date: 1999-03-22
Filing date: 2000-03-22
Publication date: 2000-09-28
Also published as: NL1011635C2; AU3576100A

Abstract

A device for reading bar code labels (3) on articles (2), such as, for example, shopping items in a supermarket, is described. The device comprises a reader unit (30) with at least two scanners (31, 32). One scanner (31) has a line of sight (51) which is oriented substantially horizontally, and the other scanner (32), which is disposed above the first scanner (31), has a line of sight (52) which is oriented obliquely downwards. The device is provided with a conveyor device (10) for conveying articles (2) in a direction (P) that is opposite to the direction of the line of sight (51) of the first scanner (31).

Description

Title : DEVICE FOR RECOGNIZING OBJECTS

The present invention relates in general to a device for recognizing objects, more particularly objects provided with an identification label or tag with a bar code.

More particularly, the present invention relates to a device for recognizing articles purchased in a shop, such as supermarket shopping items, in the case of which an automated checkout automatically calculates the price of the recognized article.

Checkout systems in supermarkets nowadays are usually provided with a bar code reader, hereinafter also indicated by the term "scanner" , for reading the bar code identification of the shopping items, wherein a computer automatically calculates the price of the recognized article and adds up the prices of all the recognized articles. Of course, such scanners have considerable advantages compared with the conventional checkout systems, where personnel had to recognize the articles visually, had to learn the price by heart or look it up in a table, and then had to enter that price manually by means of a keyboard. Compared with such a conventional checkout system, a scanner offers the advantage that fewer mistakes are made and paying for the goods is speeded up, which is, of course, in the interest of the consumer.

In the case of known checkout systems provided with a bar code reading device or scanner, the idea is that the articles to be paid for are moved manually past a reading window of the scanner, with the bar code facing that reading window. A major disadvantage here is that in the case of such checkout systems service personnel still have to be present, which means a checkout assistant for each checkout system. A first disadvantage of the need for manual service is that mistakes can be made in the process, since, for accurate detection, the standard scanners on the market require that the articles to be recognized are moved in a certain way past the scanner. Known manual scanner checkouts are therefore provided with a signal emitter which indicates the status of the reading by a sound signal. If the reading of the bar code is successful, a first sound signal is generated. A second signal, which is recognized as a fault signal, is emitted if the presence of a bar code has been recognized, but the bar code has not been successfully read. If the reader does not recognize the presence of a bar code, it does not emit a sound signal. To the service personnel, the sound signals are an indication as to whether or not the object in question has been successfully recognized; if it has not, one will have to move that object past the reading window of the reading device again, until such time as reading has been successfully completed.

There is also a growing need among consumers nowadays for the possibility of shopping with a greater degree of independence, in other words the possibility of shopping without being dependent upon service personnel. This possibility has already been realized as regards the selection of the shopping items, but not yet as regards paying for them.

Moreover, many consumers experience the time during which the checkout assistant is performing the scanning of the shopping items as "waiting time".

The object of the present invention is therefore to meet the above-mentioned need by providing a computerized checkout system that is fully automated, in other words, the customers can pay for their shopping totally independently, without the need for the assistance of service personnel.

Such a fully automated checkout system also offers the advantage that in the running of a supermarket there is a considerable saving in the operational costs of the checkout system. With the same number of checkout systems, the operational costs of that supermarket would consequently be lower. On the other hand, it is possible with the same or even reduced operational costs for the supermarket as a whole to install a larger number of checkout systems, so that the waiting times at the checkouts can be reduced.

An important condition for good functioning of such a fully automatic checkout system is a reliable device for detecting and recognizing the articles, without those articles having to be conveyed manually past a viewing window of a scanner. More particularly, it is desirable for the recognition device to be of such design that said device can cooperate simply and reliably with a conveyor system such as, for example, a conveyor belt.

In the case of known checkout systems, the scanner is disposed next to a processing platform, opposite the checkout assistant. A supply conveyor belt feeds in the articles to be recognized to said processing platform. The articles fed in are picked up by the checkout assistant from the end of the supply conveyor belt and swung in a swinging motion over the processing platform, through a field of view of the scanner. After being processed, the articles are placed by the checkout assistant on a discharge conveyor belt. During the above-mentioned swinging motion, an article to be recognized substantially passes along a path which can be described as a rotational movement in a horizontal plane relative to a point of rotation substantially coinciding with an elbow of the checkout assistant . This path is substantially perpendicular to the viewing direction of the scanner. It has been found that such a swinging motion makes successful reading of a bar code difficult. One explanation for this could be that the bar code to be read is correctly oriented at the correct distance from the scanner only for a relatively short period of time.

The chance of a successful reading of the bar code increases dramatically if the objects to be recognized pass along a path which has a considerable component directed substantially parallel to the viewing direction of the scanner, in other words, substantially perpendicular to the reading window of said scanner. This therefore implies that the objects to be recognized are moved towards the scanner. Moreover, the bar code to be read of the article to be recognized must always be directed towards the reading window of the scanner during said movement. This ensures that the bar code to be read is situated in the field of view of the detector for a relatively long time, the lateral displacement of the bar code relative to the line of view of the detector being relatively small, while the chance is increased that the bar code to be read will intersect a scanning pattern, drawn in space by the scanner, at a suitable (focusing) distance. Bar code readers are found to give their best performance in these circumstances .

Based on this insight, a reading station according to the present invention is therefore characterized in that at least one scanner is disposed in such a way that its line of view is directed substantially horizontally, substantially antiparallel to the direction of conveyance of a conveyor system.

In special circumstances, a reading station can suffice with only one bar code scanner, for example if all articles to be detected are of equal size and the bar code is always in the same position. However, in the case of an automatic checkout system, a varied supply of articles can be expected, and not only can those articles differ in size and shape from each other, but the bar codes of those articles can also be of differing sizes and can be applied at different positions from each other. In many cases, it will be difficult or impossible to position the articles in such a way that they move towards the scanner with their bar code facing forward. For use in the case of an automatic checkout system, a reading station therefore preferably comprises a second bar code scanner, which is disposed above the first-mentioned scanner and has a line of view which is directed obliquely downwards. This second scanner will be able to scan, inter alia, articles whose bar code is facing upwards .

Furthermore, a reading station for use with an automatic checkout system preferably comprises a third scanner, which is disposed above the first-mentioned scanner and has a line of view which is directed substantially horizontally. The first- mentioned scanner then serves for being able to scan small articles, wherein the bar code is at a low position, and the third scanner serves for being able to scan large articles, wherein the bar code is at a high position.

These and other aspects, features and advantages of the present invention will be explained further by the following description of an exemplary embodiment of an automatic checkout system according to the invention, with reference to the drawing, in which identical reference numerals indicate identical or comparable parts, and in which: figure 1 diagrammatically shows a top view of a recognition station; figure 2 diagrammatically shows a side view of the recognition station of Figure 1; and figure 3 diagrammatically illustrates a preferred detail of a recognition station.

Figure 1 diagrammatically shows a top view of a recognition station, generally indicated by the reference numeral 1, of the type that could be used in the case of an automatic checkout system. The recognition station 1 comprises a conveyor device

10, for conveying articles 2 to be recognized, and also a reader unit 30 for reading the bar codes 3 of the articles 2. The conveyor device 10 can be any suitable type, and is shown here as being of the type with a movable conveyor surface 11 for depositing the articles 2 to be recognized thereon, which conveyor surface 11 can be moved in the direction of conveyance indicated by the letter P. The design of the conveyor device 10 and the way in which the conveyor surface 11 of the conveyor device 10 is moved are not a subject of the present invention and will therefore not be explained further. It will suffice to point out that conveyor devices for checkout systems are known per se, wherein a rubber belt is mounted on drive rollers and driven by a motor, and that such conveyor devices known per se, with some obvious modifications if necessary, can be used in the case of the present invention. The invention will be explained in greater detail below for the case where the conveyor device 10 comprises such a conveyor belt 11. However, it is expressly pointed out that the present invention can also be used in combination with conveyor devices of another type: in the context of the present invention it is only necessary that means are present which can move the objects to be recognized along a previously defined path section. The conveyor device 10 discussed here by way of illustration further comprises longitudinal guides 15 disposed next to the conveyor belt 11, and also a deflection guide 12 extending obliquely across the conveyor belt 11. The conveyor device 10 can be provided with centring guide means 13, for example in the form of flexible strips interacting with each other, in order to ensure that articles 2 which are placed by the user on the conveyor belt 11 at an entry section 14 of the conveyor device 10, at an arbitrary widthwise position of said conveyor belt 11, ultimately acquire a widthwise position situated closer to the centre of the conveyor belt ll.

In figures 1 and 2 is shown that an article 2 to be recognized - in the example illustrated a bottle - has been placed on the conveyor belt 11 of the conveyor device 10, which article 2 is provided with a bar code label 3 which is facing forwards in relation to article 2 and with respect to the direction of conveyance P. With respect to the conveyor device 10, the article 2 passes along a conveyance path 4, which is indicated by a dotted line in figure 1. The conveyance path 4 has a first straight path section 4a, which is parallel to the direction of conveyance P and substantially coincides with the centre of the conveyor belt 11. This first path section 4a ends at the deflection guide 12 , where the first path section 4a merges into a second path section 4b, the precise direction of which is determined by the direction of the deflection guide 12. The articles 2 are consequently discharged in the lateral direction from the conveyor belt 11, during which discharge they preferably acquire from the deflection guide 12 a rotational movement with respect to a vertical axis of rotation. The articles 2 can ultimately, for example, arrive on a collection table or the like. The further handling of the articles 2 discharged in the lateral direction is not a subject of the present invention and will therefore not be discussed in further detail.

In line with the first path section 4a, a bar code reader unit 30 is disposed stationary with respect to the conveyor device 10. In the embodiment shown, the bar code reader unit 30 comprises a mounting support 20, which is immovably fixed on the conveyor device 10. The mounting support 20 comprises a first support section 21, which is directed substantially vertically and at its top end merges into a second support section 22, which is curved relative to the vertical in the direction opposite to the direction of conveyance P.

The bar code reader unit 30 comprises a number of bar code reader devices 31, 32, 33, 34 fixed on the mounting support 20, which are also indicated here as scanners. Since scanners are known per se, they will be discussed only briefly here. It will suffice to point out that a scanner in general comprises a source for generating a narrow beam of laser light, which beam leaves the scanner via a viewing window. The direction in which said beam of laser light is transmitted is varied in order to allow said beam of laser light to scan a certain part of space according to a predetermined pattern of lines . In the context of the present invention, the part of space scanned by the laser beam is indicated by the term "field of sight". A central line of the field of sight is indicated by the term "line of view", and is generally perpendicular to said viewing window. Scanners also have a design parameter which will be indicated as "depth of view" : with this term, the effective length of the field of view is meant, measured along the line of view from the viewing window. If an article is in the field of sight, at a distance relative to the viewing window which is shorter than the depth of view, the laser beam will be reflected in the direction of the scanner, and a detector of the scanner will detect the reflected laser light and convert it into an electrical signal. If the object has a bar code on its front end, as shown in the figures, and if that bar code is oriented in accordance with the said pattern of lines, a generated electrical signal will be indicative of the code represented by the bars . This electrical signal is passed on to a data processing device such as a computer, which processes the signal in order to provide data of the detected article, such as article description and price. Since data processing devices for suitably processing the electrical signals generated by the scanners are known per se, they will not be discussed in further detail here. It is pointed out that all scanners of the reader unit 30 are connected to a common data processing device such as a computer, which is designed to process the signals received from all said scanners for optimum recognition, and in such a way that double recognition is avoided.

The fields of sight of the scanners 31-34 will be indicated by the reference numerals 41-44; for the sake of simplicity, only the field of sight for the scanner 31 is indicated by means of dotted lines in the figures. The lines of sight of the scanners 31-34 will be indicated by the reference numerals 51- 54.

According to an important feature of the present invention, the line of sight 51 of the first scanner 31 is directed substantially horizontally, antiparallel to the direction of the first path section 4a, in other words antiparallel to the direction of conveyance P. It is recommended that the line of sight 51 of the first scanner 31 coincides substantially with the first path section 4a; for this purpose, the first scanner 31 is disposed at the centre of the conveyor belt 11 in the example shown.

By the arrangement described above, it is achieved that the bar code label 3 of the article 2 is in the field of sight 41 of the first scanner 31 for a relatively long time, and in that field of sight 41 undergoes virtually no lateral displacement in a direction perpendicular to the line of sight 51. Moreover, since the distance of the article 2 from the viewing window of the scanner is being constantly reduced, at the position of the bar code label 3 of said article 2 the spatial density of the pattern of lines of the scanner will constantly increase. In such circumstances, the first scanner 31 can generate a reliable detection signal with a particularly great degree of certainty. The exact height of the line of sight 51 of the first scanner 31 relative to the conveyor belt 11 can be selected in a suitable manner. The selected height can be dependent upon, inter alia, the type of scanner used. The following data, inter alia, will play a role here: size of the angle of sight of the field of sight 41; the maximum dimensions of the articles 2 which the reading station 1 must be able to detect (design parameter) ; the dimensions of the bar code labels 3 to be expected, their contrast, their quality etc.

In order for the reader unit 30 to be capable of processing a large range of articles with dimensions differing from each other, while the bar codes can be situated at greatly varying heights, a further scanner 33 is mounted on the first vertical support section 21 of the mounting support 20, above the first scanner 31, the line of sight 53 of which further scanner forming an angle in the range from 0° to approximately 10° with the line of sight 51 of the first scanner 31. Figure 2 illustrates the situation in which the line of sight 53 of the further scanner 33 is directed parallel to the line of sight 51 of the first scanner 31.

The further scanner 33 can be attached in a fixed manner to the first section 21 of the mounting support 20, in which case the orientation of the further scanner 33, in other words the angle between the line of sight 53 of the further scanner 33 and the horizontal, is then determined by the shape of the first section 21 of the mounting support 20. If said first section 21 of the mounting support 20 is directed vertically, as in the illustration of figure 2, the above-mentioned angle would therefore be 0°. If the entire mounting support 20 were curved, which for the sake of simplicity is not shown, said angle would be slightly larger than 0°, depending on the height of mounting and the curvature of the mounting support 20. However, greater adjustment flexibility is offered if the further scanner 33 is attached to the mounting support 20 in such a way that it can pivot relative to a horizontal pivot axis, in other words the angle between the line of sight 53 of the further scanner 33 and the horizontal is adjustable. It is further preferable for the vertical position of the further scanner 33 relative to the mounting support 20 to be adjustable.

The further scanner 33 can be identical to the first scanner 31. In a test arrangement which proved successful, the vertical distance between the line of sight 51 of the first scanner 31 and the conveyor belt 11 was several centimetres, while the vertical distance between the first scanner 31 and the further scanner 33 was approximately 15 cm.

It will frequently happen in practice with a checkout system that an article to be recognized cannot be positioned in such a way on a conveyor belt that the bar code is situated at the front end, in other words, is directed towards the reader unit 30. In order to ensure that the reader unit 30 is capable of processing articles positioned with the bar code facing upwards, a second scanner 32, of which the line of sight 52 is directed obliquely downwards, is mounted on the top end of the mounting support 20. As shown, the second scanner 32 is preferably situated in a vertical plane running through the line of sight 51 of the first scanner 31, and the line of sight 52 of the second scanner 32 is also situated in that vertical plane. The exact height of the second scanner 32 relative to the conveyor belt 11 and the exact value of the angle between the line of sight 52 of the second scanner 32 and the horizontal can be selected in a suitable manner, inter alia depending on the maximum height of the articles to be expected. In a test arrangement which proved suitable, the height of the second scanner 32 was approximately 40 cm, and the abovementioned angle was selected in a range of approximately 30° - 50°.

The second scanner 32 further has a depth of view which is greater than the depth of view of the first scanner 31.

In order to increase the accuracy of the reader unit 30, several scanners can be fixed above one another on the mounting support 20. A fourth scanner 34 is illustrated in figure 2 , at a position between the second scanner 32 and the third scanner 33, which fourth scanner 34 can be identical to the first and third scanners 31 and 33. The line of sight 54 of this fourth scanner 34 is preferably directed obliquely downwards, likewise in the said vertical plane, the angle which the line of sight 54 of the fourth scanner 34 forms with the horizontal being smaller than the angle which the line of sight 52 of the second scanner 32 forms with the horizontal .

The height positions of the scanners on the mounting support 20 are preferably adjustable, it being preferable for the scanners to be fixed in a sliding manner on the mounting support 20. The scanners 31-34, or at least the second to fourth scanners 32-34, are preferably fixed in a pivoting manner on the mounting support 20, so that the angle of their line of sight is adjustable, as described in greater detail above with reference to the further scanner 33. If a curved mounting support 20 is used as illustrated, the adjustment of the angle of the line of sight of the scanners can also be carried out by sliding the scanner in question along a curved section of the mounting support 20.

A further increase in ease of use of the recognition device 1 is offered if the reader station 30 is provided with means for reading a bar code applied to the underside of the articles to be recognized. To this end, the reader station 30 is provided with a fifth scanner 35, as illustrated diagrammatically in figure 3, which fifth scanner 35 is situated below the level of the articles 2 to be detected. The line of sight 55 of the fifth scanner 35 is directed obliquely upwards, in the opposite direction to the direction of the path taken by the articles 2 on the spot. The way in which the fifth scanner 35 is fixed is not critical and will not be discussed in any further detail. It will suffice to point out that the fifth scanner 35 is preferably mounted in an adjustable manner, so that the position of the fifth scanner 35 and the direction of the line of sight 55 thereof can be adjusted.

In order to ensure that the fifth scanner 35 can "see" the underside of the passing articles 2, the conveyor device 10 in the example illustrated is provided with means (for the sake of simplicity not shown) for sliding the articles over a transparent plate 60. In a preferred embodiment, which for the sake of simplicity is not illustrated separately, the recognition device 1 is provided with an article sensor for detecting the presence of a passing article. Such an article sensor can be in the form of a proximity detector, wherein a transmitting part transmits a predetermined signal, for example an infrared pulse or an ultrasonic pulse, and wherein a receiving part receives a signal reflected by an article. The article sensor can be fitted on the end of the mounting support 20, and the line of sight of the sensor, in other words, the direction in which the predetermined signal is transmitted, can be vertically downwards. As is known, the time which has elapsed between the transmission of a signal pulse and the receipt of a reflection pulse is indicative of the distance from a reflection point to the sensor. The article sensor is coupled to the said data processing device, which can therefore deduce from the signals received whether an article is passing. This event should be associated with a detection and recognition of a bar code; if that does not happen, or at least if it does not happen within a predetermined time interval, the data processing device can generate an error signal. As a result of this, the article which has been detected, but has not been recognized, can undergo a separate further treatment.

It will be clear to a person skilled in the art that the scope of the present invention is not restricted to the examples discussed above, but that various changes and modifications thereto are possible without deviating from the scope of the invention as defined in the appended claims. For instance, the conveyor means can be provided with grippers or with transparent baskets.

It will also be clear that a method and device such as would be immediately and unambiguously clear to a person skilled in the art after reading of the description and studying of the drawings are also covered by the inventive idea.

Claims

1. Device for recognizing articles (2) which are provided with a bar code (3) , comprising: a conveyor device (10) which has means (11) for moving articles (2) along a substantially linear path (4a) ; and a reader unit (30) which comprises: at least one first scanner (31) with a line of sight (51) which is directed substantially horizontally, antiparallel to the said linear path (4a) ; and at least one second scanner (32) , which is disposed above the first scanner (31) , and has a line of sight (52) which is directed obliquely downwards .

2. Device according to claim 1, wherein the second scanner (32) has a greater depth of view than the first scanner (31) .

3. Device according to claim 1 or 2 , wherein the reader unit

(30) comprises a third scanner (33) , which is disposed above the first scanner (31) and has a line of sight (53) which is directed parallel to the line of sight (51) of the first scanner

(31) or forms an angle in the range from 0° to approximately 10° with the line of sight (51) of the first scanner (31) .

4. Device according to claim 3, wherein the third scanner (33) is identical to the first scanner (31) .

5. Device according to any of the preceding claims, wherein the lines of sight of the scanners are all situated in one vertical plane.

6. Device according to any of the preceding claims, wherein the scanners are mounted in such a way that their height and/or the direction of their line of sight is adjustable.

7. Device according to any of the preceding claims, wherein the conveyor device (10) is provided with path deflection means (12) for deflecting, near the first scanner (31) , the conveyance path (4) of the articles (2) to be conveyed by the conveyor device (10) from the first linear path section (4a) to a second path section (4b) which is directed obliquely with respect to the direction of conveyance (P) .

8. Device according to claim 7 , wherein the conveyor device (10) comprises a conveyor surface (11) which can be moved in the direction of conveyance (P) of the said path (4a) , and wherein said path deflection means (12) comprise a deflection guide which is directed obliquely with respect to the direction of conveyance (P) of the conveyor device (10) and extends transversely across the conveyor surface (11) of the conveyor device (10) .

9. Device according to any of the preceding claims, further comprising a further scanner (35) , which is disposed below the conveyance path (4) of the articles (2) , and a line of sight (55) , which is directed obliquely upwards with respect to said conveyance path (4) , for reading bar codes applied to the underside of the articles (2) .

10. Device according to any of the preceding claims, further provided with an article sensor for detecting the passing of an article to be recognized.

11. Reader unit (30) for an automatic checkout system with a conveyor device (10), which reader unit (30) comprises: a mounting support (20) , which is destined for vertical mounting on the conveyor device (10) , which mounting support

(20) comprises a lower mounting support section (21) , which is preferably vertically directed, and which at its top end merges into an obliquely directed and/or curved section (22) ; wherein a first scanner (31) with a first line of sight (51) is fixed on the lower mounting support section (21) ; wherein a second scanner (32) with a second line of sight (52) is fixed on the oblique or curved mounting support section (22) ; wherein the first line of sight (51) of the first scanner (31) forms an angle with respect to the second line of sight (52) of the second scanner (32) ; and wherein the depth of view of the second scanner (32) is preferably greater than the depth of view of the first scanner (31) .

12. Reader unit according to claim 11, wherein a third scanner (33) with a third line of sight (53) is fixed on the lower mounting support section (21) , at a position between the first scanner (31) and the second scanner (32) , the third line of sight (53) of the third scanner (33) forming an angle in the region of 0° to approximately 10° with the first line of sight (51) of the first scanner (31) , or being parallel thereto, which third scanner (33) is preferably identical to the first scanner (31) .