weighing device

Abstract

Weighing device, namely belt weighing device, for determining the weight of a product, with a weighing plate (11) and a scale (13), wherein the weighing plate (11) comprises a weighing plate body (17) and a conveyor belt (15) running around the weighing plate body (17), wherein, for the purpose of transmitting data characterizing, in particular identifying, the weighing plate (11) from the weighing plate (11) to the scale (13), the weighing plate (11) is provided with at least one data transmission device (25) and the scale (13) with a receiving device (27), wherein the data transmission is contactless, wherein the at least one data transmission device (25) is designed as an RFID transponder and the receiving device (27) as an RFID reader, wherein the weighing device is designed to transmit operating parameters associated with the weighing plate (11) which are required for the operation of the scale (13) with the weighing plate (11), and the operating parameters assigned to the weighing platform (11) are correction parameters which are taken into account when calculating the weight of a product.

Description

[0001] The present invention relates to a weighing device, namely a belt weighing device, for determining the weight of a product, comprising a weighing plate and a scale.

[0002] Checkweighers are typically used within production processes for product inspection or weight control, for example, to verify filling or packaging operations. The data obtained can then form the basis for statistical analyses for quality control. However, this data can also be evaluated immediately as part of an "inline" process control to manage further production steps, such as the rejection of underweight products, trend forecasting for the continuous adjustment of a filling or dosing system, sorting, or classification.

[0003] These static or dynamic checkweighers are equipped with a weighing platform supported by a load cell that performs the actual weight determination. Particularly in wet environments such as the food industry and / or with unpackaged food products, the weighing platform can become contaminated and is then removed for cleaning. The weighing platform is also removed whenever the checkweigher undergoes repair or servicing.

[0004] Accurate weight determination using a load cell or measuring cell can generally only be performed with the weighing platform for which the associated checkweigher has been configured. This configuration primarily involves defining operating parameters, especially correction parameters, for a particular weighing platform. These parameters are stored in the corresponding checkweigher and can then be taken into account during weight determination. If a checkweigher is operated with a weighing platform for which it is not calibrated, the weight determination will generally be inaccurate because the weighing platforms differ due to manufacturing tolerances. These deviations typically lead to unacceptable errors in weight determination, especially with dynamic checkweighers operating at high belt speeds.

[0005] The above explanations regarding exact weight determination also apply analogously, for example, to a price labeller, which is generally used for the dynamic weighing of unevenly weighted goods.

[0006] German patent application DE 10 2007 025 580 A1 discloses a transport device with a weighing belt, wherein the transport device is supported on a load cell. The weight signal generated by the load cell has a periodic disturbance component caused by a periodically rotating part and is corrected by means of a stored weight correction signal, wherein the phase of the rotating part is detected by a signal transmitter.

[0007] German patent application DE 44 44 263 C1 discloses a conveyor belt in which transmitters in the form of transponder chips are inserted successively at intervals along the belt's direction of travel. A stationary transmitting and receiving device is provided outside the conveyor belt, and individual identifiers are transmitted from the transmitters to this device. The position of each transmitter can then be determined based on its respective identifier. By monitoring the presence of a transmitter at a defined location, wear monitoring can be performed. Furthermore, various measurement and storage data, such as belt number and length in meters, as well as operating status data, such as the number of cycles, temperature, and connection monitoring data, can be transmitted.

[0008] The publication JP 2005-10951 A discloses a price-calculating scale in which the price of a dish is determined by weighing. For this purpose, the dish is placed in a bowl or on a food tray and weighed together with the bowl or tray. The weight of the bowl or tray, which is communicated to the scale via an RFID transponder integrated into the bowl or tray, is then subtracted from the total weight to determine the weight of the dish alone, thus enabling the price of the dish to be calculated.

[0009] The invention is based on the objective of providing a weighing device of the type mentioned above which can ensure that a scale is operated only with a weighing plate that allows for an exact determination of weight.

[0010] This problem is solved by a device having the features of claim 1 and in particular by the fact that, for the purpose of transmitting data characterizing, in particular identifying, the weighing plate to the scale, the weighing plate is provided with at least one data transmission device and the scale with a receiving device.

[0011] This allows data to be transmitted from the weighing platform to the scale, enabling precise weight determination. The transmitted data can include, for example, at least one identification of the weighing platform, particularly at least one part thereof, for which the scale stores operating parameters relevant to weight determination when calculating the weight, and / or operating parameters of the weighing platform itself, particularly at least one part thereof. Specifically, one or more correction values ​​for weight determination can be derived from the operating parameters, especially the aforementioned correction parameters, and the set belt speed. The aforementioned at least one part is, in particular, a weighing platform body and / or a conveyor belt of the weighing platform.The data identifying the weighing plate may include, in particular, data identifying the weighing plate as a whole or as a unit, data identifying the weighing plate body and / or data identifying the conveyor belt.

[0012] In particular, the at least one data transmission device and the receiving device form a communication system. The weighing platform comprises, in particular, the aforementioned weighing platform body, which is generally equipped with the aforementioned conveyor belt, i.e., at least one transport belt or conveyor, on which the goods are transported over the load cells. The at least one data transmission device can, in principle, be provided on the weighing platform body and / or the conveyor belt. In principle, several receiving devices can also be provided, each of which can be assigned to its own data transmission device. The goods can be, for example, a product, packaging, or a parcel.

[0013] Particularly in cases where only the data identifying the weighing plate is transmitted, the weighing device according to the invention can detect or prevent the accidental exchange of weighing plates between multiple scales. Furthermore, to eliminate the need for the aforementioned special adjustments, highly precise weighing plates are known. The present invention reduces the requirements for dimensional accuracy, especially the flatness of the weighing plates. Moreover, higher maximum belt speeds, as mentioned above, can be achieved.

[0014] In principle, the at least one data transmission device and the receiving device can be connected to each other via an electrical line, for example via an electrical connector. According to the invention, however, the data transmission takes place without contact, in particular to avoid a potential force shunt caused by an electrical line; i.e., the aforementioned communication system is preferably designed for contactless or wireless data transmission.

[0015] According to the invention, at least one data transmission device is designed as an RFID transponder or RFID tag, and the receiving device is designed as an RFID reader; that is, the aforementioned communication system is designed as an RFID system. RFID systems are readily available and therefore do not incur high additional costs. The transponder can be an active transponder or a passive transponder whose operation is based on the principle of load modulation. RFID systems are generally known and therefore do not need to be explained further here.

[0016] In principle, the data, or part thereof, can be stored in a memory separate from the at least one data transmission device. However, it is preferred if the data, or part thereof, is stored in the at least one data transmission device, in particular the aforementioned RFID transponder, for example in an EEPROM. This part may, in particular, be the data identifying the weighing platform.

[0017] The weighing platform can comprise a weighing platform body with a first data transmission device and a conveyor belt with a second data transmission device, wherein data identifying the weighing platform body is stored in the first data transmission device and data identifying the conveyor belt is stored in the second data transmission device. This is particularly advantageous when operating parameters of the weighing platform are determined separately for the weighing platform body and the conveyor belt. Preferably, the first data transmission device and the second data transmission device are each configured as described above.

[0018] According to one embodiment of the invention, the scale is designed to compare the data identifying the weighing platform, or at least one ID (e.g., a unique number), with weighing platform identification data stored in the scale's memory. The weighing platform identification data stored in the memory can include the identification, or at least one ID, of one or more weighing platforms, in particular at least one part of the respective weighing platform, for which the scale has been configured. By comparing the identification data transmitted to the scale with the identification data stored in the scale, it can be verified whether an attached weighing platform, or at least one part thereof, is intended or approved for use with the respective scale. This effectively prevents a scale from being used with an "incorrect" weighing platform or...Operating with the "wrong" part would generally result in an incorrect weight determination. The aforementioned operating parameters belonging to the respective weighing platform are preferably stored on the scale side, but can also be stored, if necessary additionally, on the weighing platform side and transmitted with the identification data.

[0019] The comparison can be carried out, for example, when the weighing plate is placed on the scale and / or when the weighing device is at least attempted to be started.

[0020] Preferably, the weighing device is designed such that its intended operation, particularly weight determination, is only possible if a comparison shows that the scale possesses the operating parameters required for operation with the weighing platform. Otherwise, the operation of the weighing device can be blocked and / or an error message can be issued.

[0021] According to the invention, the weighing device, and in particular the aforementioned communication system, is designed to transmit, optionally in addition to the data identifying the weighing plate, operating parameters assigned to the weighing plate that are necessary for the correct operation of the scale with the weighing plate. The operating parameters assigned to the weighing plate can therefore also be stored on the weighing plate itself, preferably in the data transmission device. This makes it possible to use a weighing plate with any scale; that is, a scale can also be operated with weighing plates about which the scale has no information. Weighing plates are thus freely interchangeable and can be easily replaced, for example, for repair purposes, without the need to determine the operating parameters on the respective scale. Rather, the operating parameters can be determined at the factory.This means that the operating parameters only need to be determined once. The operating parameters assigned to the weighing platform are correction parameters that are taken into account when calculating the weight of a product.

[0022] Multiple sets of operating parameters can be provided for different belt speeds. This is particularly advantageous if the scale is a dynamic or continuous weighing scale, as the aforementioned operating parameters, especially correction parameters, are generally speed-dependent. This applies both when the operating parameter sets are located on the weighing platform and when they are stored within the scale itself. During operation, the operating parameter set assigned to the selected belt speed can then be used. Alternatively, a single operating parameter set can be provided for multiple, and in particular all, belt speeds.

[0023] To enable quick and easy removal of the weighing plate for cleaning, for example, it is preferred if the weighing plate is mounted on the scale via a quick-change system, preferably being removable and lockable without tools.

[0024] Furthermore, the present invention relates to a method for operating a weighing device with a weighing platform and a scale for determining the weight of goods, in which characteristic, in particular identifying, data are transmitted from the weighing platform to the scale, or a code of the weighing platform is recorded, in particular evaluated, or means characteristic of the weighing platform are detected. Advantageous embodiments of the method result analogously from further developments of the weighing devices according to the invention.

[0025] Further advantageous embodiments of the invention are described in the dependent claims, the description of the figures and the drawing.

[0026] The invention is described below by way of example with reference to the drawing. It shows, in schematic representation, Fig. 1 a weighing device according to the invention comprising a weighing plate and a scale.

[0027] The in Fig.The weighing device shown in Figure 1, for example a price labeler or a checkweigher, comprises a weighing platform 11 or a weighing belt and a scale 13, in particular a conveyor belt scale. The weighing platform 11, which can be coupled to the scale 13, comprises a weighing platform body or weighing belt body 17, which is provided with two parallel conveyor belts 15 that run around the weighing platform body 17 and form a conveyor belt. The weighing platform body 17 is provided on its two end faces with belt rollers 19 (for the conveyor belts 15) driven by a motor 31, by which the two conveyor belts 15 are then driven synchronously. The scale 13 comprises a frame 21 and a load cell 23, onto which the weighing platform 11 can be quickly and easily removed to determine the weight of goods placed on the weighing platform 11. The scale 13 is designed as a dynamic scale, i.e.The goods are moved across the weighing platform body 17 without stopping during the ongoing operation of the weighing device at belt speeds of, for example, 120 meters / min.

[0028] A scale typically also includes additional belts or conveyor belts (not shown), in particular a feed belt that receives goods from an upstream process, a separating belt that ensures only one item is fed to the weighing platform at a time, and / or a discharge belt that transfers the goods to a downstream process, as well as evaluation and control logic. The scale may also be equipped with additional devices, such as a metal detector.

[0029] According to the invention, a data transmission device designed as a passive RFID transponder 25 is provided on the weighing platform 11, e.g., laterally on the weighing platform body 17, and a receiving device designed as an RFID reader 27 is provided on the scale 13, in particular on the device frame 21. The RFID transponder 25 can, for example, also be arranged on the underside of the lateral end of the weighing platform body 17. The reading distance between the transponder 25 and the reader 27 can be, for example, approximately 10 mm. The transponder 25 and the reader 27 form a communication system by which data can be transmitted contactlessly from the weighing platform 11 to the scale 13. For this purpose, the reader 27 generates a short-range, high-frequency electromagnetic field, which serves on the one hand to supply power to the transponder 25 and on the other hand can be subjected to load modulation by the transponder 25.In principle, the RFID transponder 25 can also be arranged in or on one of the conveyor belts 15.

[0030] The data to be transmitted is stored in a memory of the RFID transponder 25. This data is the data identifying the weighing plate 11. The transmitted data can then be forwarded to the receiver via a cable 29 from the RFID reader 27 to the load cell 23.

[0031] The data to be transmitted contains information that allows the weighing plate 11 to be identified, i.e., a unique ID, such as a serial number. The weighing plate 11 can thus identify itself to the scale 13. Operating and configuration parameters for one or more weighing plates are stored in a memory of the scale 13; these parameters are taken into account when the load cell 23 determines the weight. Based on the identification of the weighing plate 11 transmitted to the scale 13, the scale 13 checks whether the operating parameters belonging to the weighing plate 11 are stored in its memory. If this is not the case, an error message is issued, and the operation of the weighing device is prevented. This check can be performed, for example, when the weighing device is started.

[0032] This is advantageous because accurate weight determination by the load cell 23 is only possible with a weighing plate 11 for which the scale 13 has the corresponding operating parameters. This is because weight determination is sensitive to manufacturing tolerances in the production of the weighing plates. Therefore, correction parameters, empirically determined specifically for the respective weighing plate, are taken into account when calculating the weight. If necessary, due to a dependency of the belt speed on the correction parameters, several sets of parameters are stored in the memory of the scale 13 for the respective weighing plate, each assigned to different belt speeds. In such cases, the parameter set corresponding to the currently set belt speed can be selected.

[0033] As an alternative to the data identifying the weighing plate 11, the transponder 25 and the reader 27 can also transmit only the aforementioned operating parameters or sets of operating parameters, which are preferably stored in the aforementioned memory of the transponder 25, from the weighing plate 11 to the scale 13. In this case, the operating parameters or sets of operating parameters no longer need to be stored on the scale itself. This has the advantage that a weighing plate can be used with any scale, or a scale can be operated with any weighing plates; that is, weighing plates are freely interchangeable without the scales needing to be specially prepared for them. This enables flexible use of the weighing plates.

[0034] Furthermore, the RFID system can transmit both weighing plate identification data and operating parameters, with both weighing plate identification data and operating parameters stored on the scale itself. This allows for the comparison of identification data and operating parameters, and the redundancy ensures a particularly high degree of reliability for accurate weight determination. Reference symbol list 11 Weighing plate 13 Scales 15 conveyor belt 17 weighing platform bodies 19 Tape roll 21 Equipment rack 23 Load cell 25 RFID transponders 27 RFID reader 29 cables 31 Engine

Claims

Weighing device, namely belt weighing device, for determining the weight of goods, comprising a weighing platform (11) and a scale (13), wherein the weighing platform (11) comprises a weighing platform body (17) and a conveyor belt (15) running around the weighing platform body (17), wherein, for the transmission of data characterizing, in particular identifying, the weighing platform (11) to the scale (13), the weighing platform (11) is provided with at least one data transmission device (25) and the scale (13) with a receiving device (27), wherein the data transmission is contactless, wherein the at least one data transmission device (25) is designed as an RFID transponder and the receiving device (27) as an RFID reader, wherein the weighing device is designed to transmit operating parameters assigned to the weighing platform (11) that are necessary for the operation of the scale (13). are required with the weighing platform (11),and wherein the operating parameters assigned to the weighing platform (11) are correction parameters which are taken into account when calculating the weight of a product. Weighing device according to claim 1, characterized in that the data or a part thereof are stored in the at least one data transmission device (25). Weighing device according to one of the preceding claims, characterized in that the weighing plate (11) comprises the weighing plate body (17) with a first data transmission device and the conveyor belt (15) with a second data transmission device, wherein data characterizing the weighing plate body (17) are stored in the first data transmission device and data characterizing the conveyor belt (15) are stored in the second data transmission device. Weighing device according to one of the preceding claims, characterized in that the scale (13) is designed to compare the data identifying the weighing plate (11) with weighing plate identification data stored in a memory of the scale (13). Weighing device according to claim 4, characterized in that the scale (13) is designed to perform the comparison when the weighing plate (11) is placed on the scale (13) and / or when the weighing device is started. Weighing device according to claim 4 or 5, characterized in that the weighing device is designed such that operation of the weighing device is only possible if the comparison shows that the scale (13) has the operating parameters required for operation with the weighing plate (11). Weighing device according to one of the preceding claims, characterized in that the weighing plate (11) is mounted on the scale (13) via a quick-change system.Method for operating a weighing device, namely a belt weighing device, with a weighing platform (11) and a scale (13) for determining the weight of a product, wherein the weighing platform (11) comprises a weighing platform body (17) and a conveyor belt (15) running around the weighing platform body (17), wherein the weighing platform (11) transmits characteristic, in particular identifying, data from the weighing platform (11) to the scale (13), wherein the data transmission is contactless, wherein the at least one data transmission device (25) is designed as an RFID transponder and the receiving device (27) as an RFID reader, wherein the weighing device is designed to transmit operating parameters assigned to the weighing platform (11) that are necessary for the operation of the scale (13) with the weighing platform (11), and wherein the operating parameters assigned to the weighing platform (11) are These are correction parameters.which are taken into account when calculating the weight of a product.

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