A WEIGHING SYSTEM FOR A CONVEYOR

Abstract: A weighing system for weighing articles conveyed on a conveyor comprising at least a first and second belt unit (1b, 1c). The weighing system comprises at least a first and second weighing cell (2) supporting the first and second belt unit, respectively, and adapted to provide data of the weight of one or more articles being supported by said belt units. The system comprises a control system that comprises detecting means (8) for providing data of at least the location of one or more edges of the article on the conveyor. A processor unit (2a, 2b, 11, 12, 13) for processing data obtained from said detecting means (8) and weighing cells (2) and for determining at least a weight of the article(s) and storing said determining weight is provided.

Description: A WEIGHING SYSTEM FOR A CONVEYOR Technical field The invention relates to a weighing system for and a method of weighing articles on a conveyor and/or a conveyor system for conveying and/or sorting articles. Background of the invention US 5,990,422 discloses an apparatus for measuring weights of articles having different shapes and weights successively transported on a conveyor. A weight of an article is calculated by processing weight signals supplied from a first and second weighing conveyor in accordance with a measuring sequence. WO 99/36753 discloses a conveyor-type weighing unit for weighing objects transported along a conveyor. A plurality of weighing platforms positioned below a conveyor belt weigh the objects transported on the conveyor belt. US 4,912,972 discloses a method and apparatus for determining the length of a flexible web or string material by determining a first measure of the weight of the web and determining a second measure of the weight of a predetermined length of the flexible web, and calculating the total length of the flexible web material on the basis of said predetermined length and said first and second weight measures. EP 0 342 561 discloses a weighing system for a conveyor wherein a plurality of conveyor belts are arranged successively, each having weighing cells below. This weighing system is adapted to weigh the same article on a plurality of weighing cells when the article is conveyed on the plurality of conveyor belts, so as to obtain a more precise weight of the article. US 5,547,034 discloses a conveyor scale for use in a combination with a conveyor belt for weighing an article on the moving belt. The weight of the article is determined from the measured friction force between a slider bed and the belt. US 4,049,069 discloses a further type of scales/weights. Description of the invention It is an object of the present invention to provide a weighing system wherein it is possible to weigh both short and long articles at a time on the same conveyor with a very high capacity. It is a further object of the present inventions to provide a weighing system which may be used for a number of different purposes and which is easy and cheap to manufacture and implement. It is a further object of the present invention to provide a weighing system wherein the weighing data and article identification are stored for retrieval. It is a further object of the present invention to provide a weighing system wherein the obtained weighing data and article identification are 100% retrieval. According to a first aspect, the present invention relates to a weighing system and weighing method for weighing articles conveyed on a conveyor comprising at least a first and second belt unit, the weighing system comprising: - at least a first and second weighing cell supporting the first and second belt unit, respectively, and adapted to provide data of the weight of one or more articles being supported by said belt units, - a control system comprising: - detecting means for providing data of at least the location of one or more edges of the article on the conveyor, and - a processor unit for processing data obtained from said detecting means and weighing cells and determining at least a weight of the article(s) and storing said determined weight. One of the first and the second belt unit may be shorter than the other one, when seen in the conveying direction, such that long articles may be weighed on the first belt unit and short articles may be weighed on the second belt unit, or vice versa. As an example, a short article may be shorter than 70 cm and a long article may be longer than 70 cm. The belt unit may comprise cross-belt units, but the weighing system may also be applied to a tilt-tray conveyor or other types of conveyors. The length of the article is preferably determined by measuring the time elapsing between a detection of the front and the rear edge of the article by the detecting means, and then based on this time and the speed of the conveyor, it is possible to determine the length of the article. Based on the length of the article, the processor unit may decide which belt unit to weigh the article. Preferably, the weighing system comprises a plurality of weighing cells, which are positioned below and in each corner of the first and/or second belt unit. In a preferred embodiment, four weighing cells are positioned in each corner of the belt units of the conveyor, but more than four cells may be used for each belt unit. Alternatively, one cell may support each belt unit, and wherein the cell is positioned in the middle of the belt unit. The weighing cells may be positioned at any position below the belt units, such as in the centre of the units. The conveyor may comprise two or more belt units, one or more of which may be supported by one or more weighing cells. If, only some of the belt units are supported by weighing cells, the other ones may be used as transporting belt only. Preferably, the first and second belt units are positioned successively in the conveyor, and the first belt may be positioned before the second belt or vice versa, when seen in the conveying direction. The first weighing cell(s) may support the first belt unit and the second weighing cell(s) may support both the first and the second belt unit. Thus, it is possible to weigh an article that only extends over the first belt unit by the first weighing cell(s) and to weigh an article that extends over both the first and second belt unit by the second weighing cell(s). Of course, the weighing system may be adapted to weigh an article that extends over three or more belt units. The first weighing cell(s) may support the first belt unit and the second weighing cells may support the second belt unit, so that an article can be weighed on the first or the second belt unit only. Preferably, the detecting means comprises sensors such as OCR cameras, photocells (PEC) or any other photo sensors, such as photo-electric sensor, diode-based sensors and CCD-sensors for detecting an edge portion of the article to be weighed. The processor unit may comprise one or more scale computers connected to said weighing cells. The control system may comprise an IC-controller connected to the scale computer(s) for processing weight signals received from the scale computer(s). The control system may further comprise a system server with a database connected to the IC-controller and/or scale computer and detecting means. The system server may be adapted to process and store at least weighing data and article identification data. The control system may comprise a host connected to the IC-controller, the scale computers, IC-controller and host communicating via a line of communication. The host may be positioned at a remote location in relation to the weighing system. The scale computers may be adapted to encrypt the weight data and provide it with an electronic signature and a start value, which is only readable by the system server and/or host, so as to checksum protect the data. Thus, at least the weight data provided in the scale computer(s) cannot be tampered by other units than the system server and/or host, so that the data may be legally stored in a database of the system server. Due to this checksum protection, it is not required to have protection on each unit in the control system, as the data send in the system only can be tampered by the unit knowing the electronic signature and start value. This is a very advantageous feature in relation to known weighing systems. Preferably, a detecting means is positioned in each end of a belt unit, when seen in the conveying direction, so as to detect a front and/or rear edge of the article on the first and/or second belt unit. The detecting means may further comprise handheld scanners or barcode scanners positioned above the conveyor for detecting article identification data. The detecting means may further be adapted to detect the position of the article and identification data of the article. The processor unit may, based on data obtained from the detecting means and/or weighing cells, further be adapted to: - determine which belt unit(s) the article is to be positioned on at the conveyor depending on the length of the article, - determine the speed of the belt(s) when loading the article on to the belt units, - determine the time at which the weighing cells are to be activated for weighing the article, - determine the time at which a succeeding article (in relation to the article being weighed) is to be loaded on to the belt unit(s). The combination of having a plurality of belt units with different lengths and the sensors for detecting the position and length of the article by detection of the front and rear edge of the article increases the capacity of the weighing system. The articles to be weighed may be conveyed on to the belt units having a length, which fits the length of the articles, so that all the articles do not need to be weighed on one single belt unit, which is long enough to weigh the longest articles. Preferably, the weighing system is adapted to weigh the article while the article is continuously conveyed along the conveyor. Thereby, the capacity of the weighing system is increased, as the conveyor does not have to stop when weighing the articles. In an embodiment of the invention a sensor is positioned in each end of the conveyor, when seen in the conveying direction, so as to detect when the article enters and leaves the belt unit(s), so as to ensure that only one article is weighed at a time. When an article is conveyed past the first coming sensor, when seen in the conveying direction, the front and rear edge of the article may be detected. Thus, the system knows on which belt units the article is to be positioned depending on the length of the article and the time at which the article is positioned in its correct position on the conveyor, so that it can be weighed. When the article has been weighed, the succeeding article can be conveyed on to the belt unit, and when the rear edge of previously weighed article has been detected by the second coming sensor in the end of the conveyor, when seen in the conveying direction, the succeeding article can be weighed. Thus, the weighing system allows that an article to be weighed may be conveyed on to the belt unit(s) before the previously weighed article has left the belt unit(s). When an article is detected for the first time by a sensor, it is given an index number, which follows the article all the way on the conveyor, so that it is possible to follow the article all the way from loading it and until is leaves the conveyor system. As the belt units being supported by the weighing cells may have different lengths, the weighing system is adapted to weigh articles of different lengths that extend over one or more of the belt units. In case the length of the article is equal to or smaller than the length of the first belt unit (the long belt), the article is conveyed onto the first belt unit, and in case the length of the article is equal to or smaller than the length of the second belt unit, the article is conveyed onto the second belt unit. In case the length of the article is larger than the length of the first belt unit, the article is conveyed onto the first and second belt unit. Because of the detecting means detecting the front and rear edge of the articles, it is possible to convey the succeeding article on to the belt unit(s) before the previous article has left the belt unit(s). Thereby, the capacity of the weighing system is further increased. According to a further aspect, the present invention relates to a weighing system for incorporation in a conveyor system for conveying and/or sorting articles comprising: - a plurality of conveyor units adapted to run along a conveyor path, - at least one loading station with a loading conveyor comprising at least a first and a second belt unit, when seen in the conveying direction, for loading articles on to the conveyor units, - at least one unloading station, and wherein the weighing system comprises any of the features mentioned in connection with the first aspect. According to a further aspect, the present invention relates to a method of weighing articles conveyed on a conveyor comprising at least a first and second belt unit, the weighing system comprising: - at least a first and second weighing cell supporting the first and second belt unit, respectively, and adapted to provide data of the weight of one or more articles being supported by said belt units, - a control system comprising: - detecting means for providing data of at least the location of one or more edges of the article on the conveyor, and - a processor unit for processing data obtained from said detecting means and weighing cells and determining at least a weight of the article(s) and storing said determined weight, the method comprising the steps of: - conveying an article past said detecting means, for detecting edges of the article, and onto said first or second belt unit, - providing weighing data of the article by means of the said weighing cells, - processing, by means of said processor unit, data obtained from said detecting means and weighing cells, so as to determine the weight data of the articles, and - storing said determined weight data. The processor unit may comprise at least one scale computer connected to the first and/or second weighing cell, an IC-controller, a system server and a host, the method comprising, subsequently to the step of conveying the article onto the first or second belt unit, the steps: - sending a message from the IC-controller to the scale computer indicating that the scale shall provide weight data, - providing weight data on the scale computer by means of said weighing cells, - sending a weight message from the scale computer to the IC-controller and/or system server indicating weight data and a control code indicating at least the validity of the weighing data. In order to provide almost 100% retrieval of the weight data, the method may further comprise, prior to the step of sending the weight message, the steps of: - encrypting the data of the weight message, - generating an electronic signature (checksum) and a start key value for the message, said signature and start value being readable only by the system server. Thus, every data send to the system server be only tampered by the system server, which is advantageously as the data often is sent via other units, e.g. the IC-controller. Preferably, the system comprises two scale computers, each being connected to a weighing cell. Preferably, the detecting means is positioned in each end of the belt units, when seen in the conveying direction, so as to detect the front and/or rear edge of the article entering the belt unit, the method comprising the steps of: - conveying the article past a first coming sensor, when seen in the conveying direction, - detecting the front edge of the article, - detecting the rear edge of the article, - weighing the article by means of the weighing cells on the first or second belt unit depending on the length of the article, - conveying the article past a succeeding sensor, and - detecting the front edge of the article by means of the succeeding sensor. The method may further comprise, subsequently to the step of detecting the front edge by means of the succeeding sensor, the steps of conveying a succeeding article to be weighed on to the belt unit(s). The succeeding article may be conveyed on to the belt unit(s) before the previous article has left the belt unit(s). The detecting means may further comprise handheld scanners or barcode scanners positioned above the conveyor for detecting article identification data, the method comprising, prior to the step of providing weighing data, the steps of: - detecting article identification data by means of said scanners, - assigning the article with an index number after the article has been identified by the detecting means, and - sending the article identification and the index number to the system server or host. When the IC-controller receives the weight data from the scale computer(s), it may compare the weight data with a reference table of control codes, as shown below (see page 13). After having compared the weight data (weight data from the first and second weighing cell) from the scale computer(s), it chooses the correct weight data and transmits it to the system server or host. The step of sending a weight message from the scale computer(s) to the IC-controller and/or system server may comprise sending messages indicating one or more of the following: - an index number for the article, - said control code indicating at least one of the following: - "the weight result from the first or second weighing cell is valid", - "the weight result from the first or second weighing cell is invalid" - a decimal point position (the number of decimals in the weight result), - weight data, - weighing duration, - unit of measurement, - a scale ID indicating the belt unit on which the article is weighed. Preferably, the scale ID is typed in on the scale computer before providing a weighing data. Thus, it is always possible to check on which belt unit the article has been weighed. The method may further comprise the step of: - receiving the article identification data from the detecting means in the system server, - receiving the weight data from the IC-controller in the system server, - verifying the validity of the received weight data on the basis of said electronic signature (checksum) and start value. The method may comprise the subsequent steps of: - transforming the article identification data and weight data from a numerical format used by the scale computer(s) and IC-controller to an object-oriented article history format, and - storing the transformed data in a database on the system server. When the article is unloaded from the conveyor, the article data (at least the weight data and identification data) may be transmitted from the database to a recording system of the system server for recording said data for one or more weeks. Thus, the control provide the possibility of legally storing the article data in a database for a long time, so that it is always possible to go back in the system and check e.g. how the weight of the article was carried out. Preferably, the scale computer(s) and IC-controller and system server and host communicates via a line of communication, which may provided by Ethernet TCP/IP. The step of processing may further comprise one or more of the steps of: - determining which belt unit(s) the article is to be positioned on at the loading conveyor depending on the length of the article, - determining the speed of the belt(s) when loading the article on to the belt units, - determining the time at which the weighing cells are to be activated for weighing the article, - determining the time at which a succeeding article (in relation to the article being weighed) is to be loaded on to the belt unit(s). One of the first and the second belt unit may be shorter than the other one, when seen in the conveying direction. The article may be continuously conveyed along the conveyor during weighing of said article, and an article to be weighed may be conveyed on to the belt unit(s) before the previously weighed article has left the belt unit(s). The processor unit may comprise one or more scale computers, one or more IC- controllers and one or more hosts that communicate via a line of communication. A method of weighing articles with a weighing system comprising said processor unit and a way of processing the data is described in connection with Fig. 4 and 6, respectively. The control system may further comprise other sensors for deriving the address identification information from the article. The sensors may comprise OCR cameras. According to a further aspect, the present invention relates to a weighing system for a conveyor, the weighing system comprising: - at least a first and a second weighing cell supporting a first and second belt unit, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units, wherein a weighing cell is positioned in the middle of the first and/or second belt unit. According to a further aspect, the present invention relates to a weighing system for a conveyor, the weighing system comprising: - first and a second weighing cells supporting a first and second belt unit, respectively, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units, wherein a weighing cell is positioned in each corner of the first and/or second belt unit. According to a further aspect, the present invention relates to a method of weighing articles on a conveyor, the weighing system comprising: - at least a first and a second weighing cell supporting a first and second belt unit, - a control system comprising: - detecting means for detecting the position and length of the article by detection of the front and rear edge of the article on the first and/or second belt unit, - a processor unit for: - determining which belt unit(s) the article is to be positioned on at the loading conveyor depending on the length of the article, and/or - determining the speed of the belt(s) when loading the article on to the belt units, and/or - determining the time at which the weighing cells are to be activated for weighing the article, and/or - determining the time at which a succeeding article (in relation to the article being weighed) is to be loaded on to the belt unit(s), and/or - processing data obtained from the weighing cells, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units, the method comprising the steps of: - conveying an article along the conveyor on to the first and/or second belt unit, - weighing the article by means of said weighing cells. According to a further aspect, the present invention relates to a weighing system for a conveyor, the weighing system comprising: - at least a first and a second weighing cell supporting a first and second belt unit, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units, wherein a weighing cell is positioned in the middle of the first and/or second belt unit. According to an further aspect, the present invention relates to a weighing system for a conveyor, the weighing system comprising: - first and a second weighing cells supporting a first and second belt unit, respectively, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units, wherein a weighing cell is positioned in each corner of the first and/or second belt unit. According to a further aspect, the present invention relates to a weighing system for incorporation in a conveyor system for conveying and/or sorting articles comprising: - a plurality of conveyor units adapted to run along a conveyor path, - at least one loading station with a loading conveyor comprising at least a first and a second belt unit successively arranged, when seen in the conveying direction, for loading articles on to the conveyor units, - at least one unloading station, the weighing system comprising: - at least a first and a second weighing cell supporting the first and second belt unit, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units. According to a further aspect, the present invention relates to a method of weighing articles on a conveyor, the weighing system comprising: - at least a first and a second weighing cell supporting a first and second belt unit, - a control system comprising: - detecting means for detecting the position and length of the article by detection of the front and rear edge of the article on the first and/or second belt unit, - a processor unit for: - determining which belt unit(s) the article is to be positioned on at the loading conveyor depending on the length of the article, and/or - determining the speed of the belt(s) when loading the article on to the belt units, and/or - determining the time at which the weighing cells are to be activated for weighing the article, and/or - determining the time at which a succeeding article (in relation to the article being weighed) is to be loaded on to the belt unit(s), and/or - processing data obtained from the weighing cells, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units, the method comprising the steps of: - conveying an article along the conveyor on to the first and/or second belt unit, - weighing the article by means of said weighing cells. It should be understood that, though the present invention relates to a number of independent aspects, any combination of these aspects and the features and elements mentioned in connection therewith is possible within the scope of the present document. Brief description of the figures Embodiments of the invention will be described in details below with reference to the figures, wherein Fig. 1 shows a conveyor with a belt unit being supported by weighing cells, Fig. 2 shows a conveyor with two successively arranged belt units, each of which being supported by weighing cells, Fig. 3 shows a conveyor with two successively arranged belt units, each of which being supported by weighing cells, Fig. 4 shows a conveyor system with a loading conveyor comprising belt units, and Fig. 5 shows a conveyor with two successively arranged belt units, each of which being supported by weighing cells that are connected to a processor unit, and Fig. 6 shows a diagram of the weight and identification data's way through the control system. Detailed description of the figures Fig. 1 shows a conveyor comprising three belt units (1a, 1 b and 1c) wherein the unit (1 b) is supported by weighing cells (2). The unit (1 b) is preferably supported by four weighing cells each of which being positioned below and in each corner of the belt unit. The articles are conveyed in the conveying direction (3). Fig. 2 shows a conveyor comprising four belt units (1a, 1b, 1c, and 1d) wherein the units (1b, 1c) are supported by weighing cells (2a and 2b). Each of the units (1b and 1c) is preferably supported by four weighing cells each of which being positioned in each corner of the belt units. The unit (1c) is adapted to weigh long articles and the unit (1b) is adapted to weigh short articles. Fig. 3 shows a conveyor comprising four belt units (1a, 1 b, 1c, and 1d) wherein the units (1b, 1c) are supported by weighing cells (2a and 2b). The weighing cells (2a) support the unit (1b) and the weighing cells (2b) support both units (1 b and 1c). Thus, the weighing cells (2a) are adapted to weigh articles occupying the unit (1b) and the weighing cells (2b) are adapted to weigh articles occupying both units (1b and 1c) or only the unit (1c). Fig. 4 shows a conveyor comprising four belt units (1a, 1 b, 1c, and 1d) wherein each of the units (1 b, 1c) is supported by four weighing cells (2) that are connected to a scale computer (2A and 2B), respectively. The four weighing cells are positioned in each corner of the belt units. The unit (1c) is adapted to weigh long articles and the unit (1 b) is adapted to weigh short articles. When only the unit (1c) is used for weighing, the unit (1 b) is used as a transporting belt only and vice versa. The articles are conveyed in the conveying direction (3). A sensor (8) is positioned in each end of the units (1b, 1c) and connected to the scale computers. The scale computers are connected to an IC-controller (11) that is connected to a host (12) via a system server (13). Fig. 5 shows a conveyor system with a main conveyor (4) and a loading conveyor (5). The main conveyor and the loading conveyor run in the conveying directions (6,7), respectively. The loading conveyor comprises a sensor (8), which may detect the address identification information and/or the length and/or the front/rear edge of the article (9). The loading conveyor is divided into belt units (10a, 10b and 10c) each of which may be supported by weighing cells (not shown), so as to weigh the articles before they are loaded on to the main conveyor (4). A preferred method of weighing the articles will be described below with reference to Fig. 4. An article is conveyed along both the units (1c, 1b). The IC-controller (11) sends a message (index telegram) to each of the scale computers. Firstly, the scale computer 2A calculates the weight and sends a signal to the IC-controller indicating that is has a weight message (as mentioned in claim 21) comprising the weight data and a control code ready for transmission. Subsequently, the scale computer 2B calculates the weight and sends a signal to the IC-controller indicating that is has a weight message comprising the weight data and a control code ready for transmission. If the control code = 0, the weight result is valid. If the control code ≠ 0, the weight result is invalid. Then the IC-controller collects the message from the scale computer 2A and then from the scale computer 2B. The IC-controller compares the control codes from the two messages with the table below: Depending on these two control codes, the IC-controller decides which message to be transferred to the host. If the result from scale 2A is ok, the IC-controller cancels the weighing data from the scale computer 2B and subsequently sends the weighing data from the scale computer 2A to a host. If the weighing result from the scale computer 2A is invalid, the result is cancelled and the IC-controller asks the scale computer 2B for a weighing data. If this result is ok, the result is sent to a host. If the weighing results from both the scale computers 2A, 2B are invalid, no messages are sent, but a control code from the scale computer 2A is sent to a host. Every weighing result is affiliated with a control code that determines whether the result is valid (code 0) or invalid (code 1-21). The control code follows the article up to the host of the customer. 5 Each time a weighing result is to be used, the control is checked for ensuring whether the weighing result is valid or invalid. The control codes may have the following "message type": 10 0= no error, weight is returned, 1= negative weight value, the weight is sign reversed and returned, 2= overweight item, item is heavier than the protocol maximum weight, 3= zero error, scale is unable to zero, 4= no weight signal detected, there is no weight value present for this index, 15 5= measuring not finished, there is no weight value present for this index, 6= weight calculation not finished, there is no weight value present for this index, 7= scale is in calibration mode or test mode, scale has to be in normal mode in order to weigh 8= item too long, 20 9= more than one item on the weighing belt, this error is returned when an item cannot be weighed because an item has been seen in the PEC while another parcel is being weighed, 10= underweight item detected, the item is below the protocol minimum weight, 11= reserved, 25 12= calibration constant(s) or specific gravity is invalid, the scale has lost its calibration or has never been calibrated before. A deficient battery in the scale may cause this, 13= load cell error, one or more load cells are not connected correctly or they are deficient, 14= unknown index, the scale has been requested for data for an index not present in its 30 buffer 15= weight buffer error, the weight values needed to calculate the weight were not present in the scale's internal weight buffer, 16= power up error, this status code signals that the scale has one or more power-up errors. Most likely the number of load cells or the presence of an accelerometer is configured wrong. Also the power up zeroing range can be exceeded, so the scale did not zero during power-up, 17= item missing, this control code indicated that an item did not arrive in PEC 2 in a calculated time window, this control code is only returned when the scale is configured to use 2 PEC's, 18= too many items detected in PEC, this error is returned when an item cannot be weighed because three or more items have been detected by the PEC and they are still present on the weighing plate (the middle item cannot be weighed). This error can only be returned when the scale is configured to allow more than one item on the weighing belt at the same time (weighing multiple/several parcels). 19= weight integration period too short, 20= warm-up time, 21= item outside weighing belt. EXAMPLES Article 1 = short article Article 2 = short article Article 3 = long article Ex. 1 If article 1 is conveyed onto the unit (1c) and the article 2 follows immediately after, the scale computer 2A sends a control code 9 "more than one article on the belt unit (1 c)" as the distance between the two articles is too small. The scale computer 2B will also weigh these articles, but it will send a valid weighing result and a control code 0 for both articles, as this belt unit is shorter. Ex. 2 If article 1 is conveyed onto the unit (1c) and the article 3 follows immediately after, the scale computer 2A sends a control code 9 "more than one article on the belt unit (1c)", as the distance between the two articles is too small for article 1 , and a valid weighing result (incl. a control code 0) for article 3. The scale computer 2B will also weigh these articles, but it will send a valid weighing result and a control code 0 for article 1 and a control code 8 "article too long" for article 3. The IC-controller will send message from scale computer 2B for article 1 and message from scale computer 2A for article 3 to the system server or host. Also, the scale computers will send a message to the system server or host. The message may comprise the following data: - an index number (which is sent to a scale computer just before the article is loaded onto the belt unit, - a control code, - decimal point position (number of decimals contained in the weighing result in the message) - a weight value (weight result) - weighing duration (time of weighing) - unit of measurement (weighing unit, kg/lb/oz, which parameter is determined in the weighing system) - scale ID (in order to have 100% detection of the article, it is possible to determine on which belt unit the article has been weighed. This ID is a parameter value that is typed in the scale, which makes this weighing system unique). All these data of the above message may be checksum protected before being send from the scale computers, and below is described, with reference to Fig. 6, a preferred embodiment of how the weigh data and item identification propagates from the scale 2A, 2B, and detecting means (14,15) to the CMC, system server and host for legally storage and retrieval. The scale, which may be an integrated part of a loading conveyor (5), samples an article weight when directed to it by the CMC (IC-controller) (11). The scale builds a weight data telegram and adds an electronic signature to it. The scale transmits the weigh data to the CMC (11) on request. In some applications the scale will not communicate with the CMC, but instead transmit the telegram to the CSS (system server) (13). The CMC assigns all articles with an index when the article is identified by the detecting means on the conveyor. The index follows the article in its lifetime on the conveyor, and it is used in a dialog with the CSS. When the article is unloaded from the conveyor, the index may be released and can be used again. The CMC receives the weigh data form the scale and passes it unaffected to the CSS together with the item index. The CMC inspects the weigh data and take eventually action on it. If the weigh data is within an acceptable range, the article is loaded onto a main conveyor and sorted. Any deviations from the acceptable range in the weigh data is taken care of by the CMC, e.g. stop of the weighing belt units with an appropriate error indication and reported to the CSS. The interface between the CMC and CSS may be a local area network based on Ethernet TCP/IP. All articles are given unambiguous article identification as search key for later retrieval of weigh data for legal purpose. The article identification can be given by different sources, e.g. a keyboard (CEU) (14) or barcode scanner above the conveyor (4) - an over-head scanner (OHS) (15). The CEU is placed next to the loading conveyor (5) it is associated to. The operator fetches the article identification with e.g. a hand held scanner or a keypad. The CEU transmit the article identification to the directly connected CSS. The CEU may use Ethernet between the CMC and CSS as transport media. The OHS is placed above the conveyor and is activated by the CMC when the conveyor with the article in question is underneath it. After the OHS has processed the reading, the resulting article identification is transmitted to the CSS either routed unaffected through the CMC or directly. When the weigh data and the article identification are received from the CMC, they are undergoing a transformation from a numerical format used by the scale computers and the CMC to an object-oriented article history format. While an article is on its way from induction to unloading, all article history events are kept by e.g. a java-class in a data domain. First time the article is identified by the CSS an additional unique CSS index is created and associated with the CMC index. Also a time stamp may be a fixed part of the article history events. Events with indexes and time stamp may be added step-by-step to the java-class, and wherein no one is modifying already received events. Weigh data may be kept here too, and the java-class is continuously transferring all article history events to the CSS database. Other java-classes may be observers to the java-class. When the article is unloaded, the belt unit is verified as empty by a succeeding SPS (Stray Parcel Supervision). The observers may be notified by a message containing all events from the article, one of the observers being an isolated module (java-class). This and other observers take care of the long-time storage of the weigh data and provide tools for retrieval of them again. When the article is sorted to its final destination, the article history events weigh data and identification data of the sorted article are transmitted from the observable java-class. All events have attached the same unique index. The weigh data and its electronic signature originally generated by the scale computer are verified to prove that no one had tampered the weigh data on its way through the control system. The weigh data and article identification are joined in a weigh record together with other relevant data like e.g. date and time, operator identity, and indexes which can be relevant to present to the operator while retrieved. The weigh record is protected with a common electronic signature and long-time stored on a hard disk. The electronic signature (checksum) is calculated from a CRC (Cyclic Redundancy Check) with a start value only known by legally relevant modules of the CSS. Each time the CSS receives weight data, it verifies whether the received data is valid based on the same electronic signature and start value. By using this principle with electronic signature (checksums) and start value, it is possible to send weight data through a serial communication, industrial network, IC-controllers, processor units, via the Internet or other "unprotected areas" and still obtain 100% retrieval of the weight data, as it is only the scale computer and the CSS that knows the electronic signature and start value. The same principle with the electronic signature and the start value may be used between the CSS and the host. Thus, it is possible to send weight data through "unprotected" areas, and still validate the weight data received in the host. The CSS may hold the tools to validate the correctness of the data collected by the scale computers. Preferably, all legally relevant modules are equipped with checksums, which can be inspected at the CWS, and the user can compare them with the checksums. The weigh record may be stored for at least a month, but the period can be extended. A weigh record may be retrieved from the store with a search based on the article identification. Both the electronic signatures in the record are verified upon retrieval. The CWS (16) provides the operator with a user interface, where the article identification can be entered, and when found on the disk, all data are displayed to the operator. A CGS (17) is provided for covering the entire material handling installation, which is connected to a sorting system.

Claims: CLAIMS 1. A weighing system for weighing articles conveyed on a conveyor comprising at least a first and second belt unit, the weighing system comprising: - at least a first and second weighing cell supporting the first and second belt unit, respectively, and adapted to provide data of the weight of one or more articles being supported by said belt units, - a control system comprising: - detecting means for providing data of at least the location of one or more edges of the article on the conveyor, and - a processor unit for processing data obtained from said detecting means and weighing cells and for determining at least a weight of the article(s) and storing said determined weight. 2. A weighing system according to claim 1 , wherein the detecting means comprises sensors such as OCR cameras, photocells (PEC) or any other photo sensors, such as photo-electric sensor, diode-based sensors and CCD-sensors. 3. A weighing system according to claim 1 or 2, wherein the processor unit comprises one or more scale computers connected to said weighing cells. 4. A weighing system according to claim 3, further comprising an IC-controller connected to the scale computers for processing weight signals received from the scale computers. 5. A weighing system according to claim 4, further comprising a system server connected to the IC-controller and/or scale computer and detecting means and comprising a database for storage of at least weighing data and article identification data. 6. A weighing system according to claim 5, further comprising a host connected to the IC- controller, the scale computers, IC-controller and host communicating via a line of communication. 7. A weighing system according to claim 5 or 6, wherein the scale computers are adapted to encrypt the weight data and provide it with an electronic signature and start value only readable by the system server and/or host, so as to checksum protect said data. 8. A weighing system according to any of the preceding claims, wherein a detecting means is positioned in each end of a belt unit, when seen in the conveying direction, so as to detect a front and/or rear edge of the article on the first and/or second belt unit. 9. A weighing system according to any of the preceding claims, wherein the detecting means further comprises handheld scanners or barcode scanners positioned above the conveyor for detecting article identification data. 10. A weighing system according to any of the preceding claims, wherein the detecting means further is adapted to detect the position of the article and identification data of the article. 11. A weighing system according to any of the preceding claims, wherein one of the first and the second belt unit is shorter than the other one, when seen in the conveying direction. 12. A weighing system according to any of the preceding claims, wherein the processor unit, based on data obtained from the detecting means and/or weighing cells, further is adapted to: - determine which belt unit(s) the article is to be positioned on at the conveyor depending on the length of the article, - determine the speed of the belt(s) when loading the article on to the belt units, - determine the time at which the weighing cells are to be activated for weighing the article, - determine the time at which a succeeding article (in relation to the article being weighed) is to be loaded on to the belt unit(s). 13. A weighing system according to any of the preceding claims, wherein a weighing cell is positioned in each corner of the first and/or second belt unit. 14. A weighing system according to any of the preceding claims, wherein the first weighing cell(s) support the first belt unit and the second weighing cell(s) support both the first and the second belt unit, so that an article only extending over the first belt unit is weighed by the first weighing cell(s) and so that an article extending over both the first and second belt unit is weighed by the second weighing cell(s). 15. A weighing system according to any of the preceding claims, wherein the conveyor comprises three or four or more belt units being supported by one or more weighing cells for weighing articles thereon. 16. A weighing system for incorporation in a conveyor system for conveying and/or sorting articles comprising: - a plurality of conveyor units adapted to run along a conveyor path, - at least one loading station with a loading conveyor comprising at least a first and a second belt unit, when seen in the conveying direction, for loading articles on to the conveyor units, - at least one unloading station, and wherein the weighing system comprises any of the features according to any of claims 1-15. 17. A method of weighing articles conveyed on a conveyor comprising at least a first and second belt unit, the weighing system comprising: - at least a first and second weighing cell supporting the first and second belt unit, respectively, and adapted to provide data of the weight of one or more articles being supported by said belt units, - a control system comprising: - detecting means for providing data of at least the location of one or more edges of the article on the conveyor, and - a processor unit for processing data obtained from said detecting means and weighing cells and determining at least a weight of the article(s) and storing said determined weight, the method comprising the steps of: - conveying an article past said detecting means, for detecting edges of the article, and onto said first or second belt unit, - providing weighing data of the article by means of the said weighing cells, - processing, by means of said processor unit, data obtained from said detecting means and weighing cells, so as to determine the weight data of the articles, and - storing said determined weight data. 18. A method according to claim 17, wherein the processor unit comprises at least one scale computer connected to the first and/or second weighing cell, an IC-controller, a system server and a host, the method comprising, subsequently to the step of conveying the article onto the first or second belt unit, the steps: - sending a message from the IC-controller to the scale computer indicating that the scale shall provide weight data, - providing weight data on the scale computer by means of said weighing cells, - sending a weight message from the scale computer to the IC-controller and/or system server indicating weight data and a control code indicating at least the validity of the weighing data. 19. A method according to claim 18, further comprising, prior to the step of sending the weight message to the system server, the steps of: - encrypting the data of the weight message - generating an electronic signature (checksum) and a start key value for the message, said signature and start value being readable only by the system server. 20. A method according to any of claims 17-19, wherein a detecting means is positioned in each end of the belt units, when seen in the conveying direction, so as to detect the front and/or rear edge of the article entering the belt unit, the method comprising the steps of: - conveying the article past a first coming sensor, when seen in the conveying direction, - detecting the front edge of the article, - detecting the rear edge of the article, - weighing the article by means of the weighing cells on the first or second belt unit depending on the length of the article, - conveying the article past a succeeding sensor, and - detecting the front edge of the article by means of the succeeding sensor. 21. A method according to claim 20, further comprising, subsequently to the step of detecting the front edge by means of the succeeding sensor, the steps of conveying a succeeding article to be weighed on to the belt unit(s). 22. A method according to claim 21 , wherein the succeeding article is conveyed on to the belt unit(s) before the previous article has left the belt unit(s). 23. A method according to any of claims 17-22, wherein the detecting means further comprises handheld scanners or barcode scanners positioned above the conveyor for detecting article identification data, the method comprising, prior to the step of providing weighing data, the steps of: - detecting article identification data by means of said scanners, - assigning the article with an index number after the article has been identified by the detecting means, and - sending the article identification and the index number to the system server or host. 24. A method according to claim 23, further comprising the steps of: - receiving the weight data from the scale computer(s) in the IC-controller, - comparing the weight data with a reference table of control codes, - choosing one of the weight data, and - transmitting the chosen weight data to the system server or host. 25. A method according to claim 18, wherein the step of sending a weight message from the scale computer(s) to the IC-controller and/or system server comprises sending messages indicating one or more of the following: - an index number for the article, - said control code indicating at least one of the following: - "the weight result from the first or second weighing cell is valid", - "the weight result from the first or second weighing cell is invalid" - a decimal point position (the number of decimals in the weight result), - weight data, - weighing duration, - unit of measurement, - a scale ID indicating the belt unit on which the article is weighed, 26. A method according to claim 25, and comprising the step of typing in a scale ID in the scale computer(s) before providing a weighing data. 27. A method according to any of claims 17-26, further comprising, subsequently to the step of claim 23, the step of: - receiving the article identification data from the detecting means in the system server, - receiving the weight data from the scale computers and/or IC-controller in the system server, and - verifying the validity of the received weight data on the basis of said electronic signature (checksum) and start value. 28. A method according to claim 27, further comprising the steps of: - transforming the article identification data and weight data from a numerical format used by the scale computer(s) and IC-controller to an object-oriented article history format, and - storing the transformed data in a database on the system server. 29. A method according to claim 28, further comprising, after the article is unloaded from the conveyor, the steps of: - transmitting at least the weight data and identification data from the database to a 5 recording system of the system server for recording said data for one or more weeks. 30. A method according to any of claims 18-29, wherein the scale computer(s) and IC- controller and system server and host communicates via a line of communication. 10 31. A method according to claim 30, wherein the line of communication is provided by Ethernet TCP/IP. 32. A method according to any of claims 17-31 , wherein the step of processing further comprises one or more of the steps of: 15 - determining which belt unit(s) the article is to be positioned on at the loading conveyor depending on the length of the article, - determining the speed of the belt(s) when loading the article on to the belt 0 units, - determining the time at which the weighing cells are to be activated for weighing the article, 5 - determining the time at which a succeeding article (in relation to the article being weighed) is to be loaded on to the belt unit(s). 33. A method according to any of claims 17-32, wherein the detecting means comprises sensors such as OCR cameras, photocells (PEC) or any other photo sensors, such as 0 photo-electric sensor, diode-based sensors and CCD-sensors. 34. A method according to any of claims 17-33, wherein one of the first and the second belt unit is shorter than the other one, when seen in the conveying direction. 35. A method according to any of claims 17-34, the article is continuously conveyed along the conveyor during weighing of said article. 36. A method according to any of claims 17-35, wherein an article to be weighed is 5 conveyed on to the belt unit(s) before the previously weighed article has left the belt unit(s). 37. A weighing system for a conveyor, the weighing system comprising: 10 - at least a first and a second weighing cell supporting a first and second belt unit, wherein the weighing system is adapted to: 15 - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units, 20 wherein a weighing cell is positioned in the middle of the first and/or second belt unit. 38. A weighing system according to claim 37, wherein one of the first and the second belt unit is shorter than the other one, when seen in the conveying direction. 25 39. A weighing system according to claim 37 or 38, wherein a weighing cell is positioned in the middle of the first and/or second belt unit. 40. A weighing system according to claim 37 or 38, wherein a weighing cell is positioned in each corner of the first and/or second belt unit. 30 41. A weighing system according to any of claims 37-40, wherein the first weighing cell(s) support the first belt unit and the second weighing cell(s) support both the first and the second belt unit, so that an article only extending over the first belt unit is weighed by the first weighing cell(s) and so that an article extending over both the first and second belt 35 unit is weighed by the second weighing cell(s). 42. A weighing system according to any of claims 37-41 , further comprising a control system comprising: - sensors for detecting the position and length of the article by detection of the front and rear edge of the article on the first and/or second belt unit, - a processor unit for: - determining which belt unit(s) the article is to be positioned on at the conveyor depending on the length of the article, - determining the speed of the belt(s) when loading the article on to the belt units, - determining the time at which the weighing cells are to be activated for weighing the article, - determining the time at which a succeeding article (in relation to the article being weighed) is to be loaded on to the belt unit(s), and - processing data obtained from the weighing cells. 43. A weighing system according to any of claims 37-42, wherein the conveyor comprises more than two belt units, one or more of which is supported by one or more weighing cells for weighing articles thereon. 44. A weighing system according to claim 42 or 43, wherein the sensors comprise OCR cameras, photocells (PEC) or any other photo sensors, such as photo-electric sensor, diode-based sensors and CCD-sensors. 45. A weighing system according to any of claims 37-44, wherein the processor unit comprises a scale computer, an IC-controller and a host that communicate via a line of communication. 46. A weighing system according to any of claims 37-45, the article is continuously conveyed along the conveyor during weighing of said article. 47. A weighing system according to any of the claims 42-46, wherein a sensor is 5 positioned in each end of the conveyor, when seen in the conveying direction, so as to detect when the article enters and leaves the belt unit(s), so as to ensure that only one article is weighed at a time. 48. A weighing system according to claim 47, wherein an article to be weighed is 10 conveyed on to the belt unit(s) before the previously weighed article has left the belt unit(s). 49. A weighing system according to claim 37, and comprising any of the features of claims 1-15. 15 50. A weighing system for a conveyor, the weighing system comprising: - first and a second weighing cells supporting a first and second belt unit, respectively, 20 wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, 25 - weigh an article by means of said two weighing cells when the article occupies said two belt units, wherein a weighing cell is positioned in each corner of the first and/or second belt unit. 30 51. A weighing system according to claim 50, and comprising any of the features of claims 1-15 or 37-49. 52. A weighing system for incorporation in a conveyor system for conveying and/or sorting articles comprising: 35 - a plurality of conveyor units adapted to run along a conveyor path, - at least one loading station with a loading conveyor comprising at least a first and a second belt unit successively arranged, when seen in the conveying direction, for loading articles on to the conveyor units, - at least one unloading station, the weighing system comprising: - at least a first and a second weighing cell supporting the first and second belt unit, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units. 53. A weighing system according to claim 52, and comprising any of the features of claims 37-49. 54. A method of weighing articles on a conveyor, the weighing system comprising: - at least a first and a second weighing cell supporting a first and second belt unit, - a control system comprising: - detecting means for detecting the position and length of the article by detection of the front and rear edge of the article on the first and/or second belt unit, - a processor unit for: - determining which belt unit(s) the article is to be positioned on at the loading conveyor depending on the length of the article, and/or - determining the speed of the belt(s) when loading the article on to the belt units, and/or - determining the time at which the weighing cells are to be activated for weighing the article, and/or - determining the time at which a succeeding article (in relation to the article being weighed) is to be loaded on to the belt unit(s), and/or - processing data obtained from the weighing cells, wherein the weighing system is adapted to: - weigh an article by means of one of said weighing cells when the article occupies one of the belt units only, - weigh an article by means of said two weighing cells when the article occupies said two belt units, the method comprising the steps of: - conveying an article along the conveyor on to the first and/or second belt unit, - weighing the article by means of said weighing cells. 55. A method according to claim 54, wherein the length of the article is equal to or smaller than the length of the first belt unit, the method further comprising the steps of: - conveying the article on to the first belt unit. 56. A method according to claims 54 or 55, wherein the length of the article is equal to or smaller than the length of the second belt unit, the method further comprising the steps of: - conveying the article on to the second belt unit. 57. A method according to claims 54 or 55, wherein length of the article is larger than the length of the second belt unit, the method further comprising the steps of: - conveying the article on to the first and second belt unit. 58. A method according to any of claims 54-57, wherein the article is continuously conveyed along the conveyor during weighing of said article, the method comprising the step of: - conveying the article along the conveyor and simultaneously weighing said article by means of the weighing cells. 59. A method according to any of claims 54-58, wherein a sensor is positioned in each end of the conveyor, when seen in the conveying direction, so as to detect when the article enters and leaves the belt unit(s), so as to ensure that only one article is weighed at a time, the method comprising the steps of: - conveying the article past a first coming sensor, when seen in the conveying direction, - detecting the front edge of the article, - detecting the rear edge of the article, - sending a signal to the processor unit when the article is positioned correct on the first and/or second belt unit, - weighing the article by means of the weighing cells, - conveying the article past a succeeding sensor, and - detecting the front edge of the article by means of the succeeding sensor. 60. A method according to claim 59, further comprising, subsequently to the step of detecting the front edge by means of the succeeding sensor, the steps of: - conveying a succeeding article to be weighed on to the belt unit(s). 61. A method according to claim 60, wherein the succeeding article is conveyed on to the belt unit(s) before the previous article has left the belt unit(s). 62. A method according to any of claims 54-61 , wherein the processor unit comprises a first scale computer (A) connected to the first weighing cell, a second scale computer (B) connected to the second weighing cell, an IC-controller connected to the scale computers and to a host, the method comprising: 5 - sending signal codes from the first and/or second scale computers to the IC-controller indicating at least the following: - "the weighing result from the first or second weighing cell is valid", or 10 - "the weighing result from the first or second weighing cell is invalid". 63. A method according to claim 62, further comprising the step of sending the signal codes from the IC-controller to the host. 15 64. A method according to claim 54, and comprising any of the steps according to claims 17-36.

Inventors: CHRISTENSEN LARS OLE, HAMBORG WILLY, KJAER ARNE, NIELSEN PER, PEDERSEN FINN LYNG, CHRISTENSEN, LARS, OLE, HAMBORG, WILLY, KJAER, ARNE, NIELSEN, PER, PEDERSEN, FINN, LYNG
Applicants: CHRISTENSEN LARS OLE, CRISPLANT AS, HAMBORG WILLY, KJAER ARNE, NIELSEN PER, PEDERSEN FINN LYNG, CHRISTENSEN, LARS, OLE, CRISPLANT A/S, HAMBORG, WILLY, KJAER, ARNE, NIELSEN, PER, PEDERSEN, FINN, LYNG
Application year: 2001
Main classification: G01G11
IPC codes: G01G11