Weighing device and calibration method

Abstract

A weighing device according to an embodiment comprises: a weighing unit that measures, on the basis of detection results of a plurality of ports for connecting a load cell and load cells individually connected to the plurality of ports, the weight of an object to be weighed; and a storage unit that stores a correction value, which is related to detection of the weight derived for each load cell, in association with a port identifier capable of identifying the port to which the load cell is connected. The weighing unit measures the weight of the object to be weighed on the basis of a result obtained by correcting a detection result of the weight detected by each of the load cells with a correction value corresponding to the port identifier of the port to which the load cell is connected.

Description

Measuring device and calibration method

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to a weighing device and a calibration method.

[0002] As a device for weighing an item such as a commodity, there is a weighing device that includes a base on which the item is placed and a load cell that weighs the item placed on the base. There is also a weighing device that includes multiple load cells attached to one base. For example, a technique has been proposed for evaluating the initial load at the time of power supply for each of multiple connected load cells, using an initial load corresponding to a load signal in an unloaded state at the time the weighing device is adjusted (see, for example, Patent Document 1).

[0003] In order to improve the weighing accuracy of a weighing device equipped with multiple load cells, it is necessary to improve the weighing accuracy of each load cell. Conventionally, to improve the weighing accuracy, a calibration process (hereinafter also referred to as calibration) has been performed on the output result of the weighing device.

[0004] However, in a weighing device equipped with a plurality of load cells, it is necessary to perform calibration for each of the plurality of load cells in order to further improve the weighing accuracy of the weighing device.

[0005] The problem to be solved by the present invention is to provide a weighing device and a calibration method that can improve the weighing accuracy of a weighing device equipped with a plurality of load cells.

[0006] The weighing device of the embodiment comprises a plurality of ports for connecting load cells, a weighing unit that weighs the weight of the object to be weighed based on the detection results of each of the load cells individually connected to the plurality of ports, and a memory unit that stores a correction value related to the weight detection derived for each of the load cells in association with a port identifier that can identify the port to which the load cell is connected, and the weighing unit measures the weight of the object to be weighed based on the result of correcting the weight detection result detected by each of the load cells with a correction value corresponding to the port identifier of the port to which the load cell is connected.

[0007] FIG. 1 is a schematic diagram showing a general configuration of a weighing device according to an embodiment. FIG. 2 is a block diagram showing an example of a hardware configuration of a weighing device according to an embodiment. FIG. 3 is an example of a graph showing the relationship between weight and AD value output by a load cell according to an embodiment. FIG. 4 is a diagram showing an example of a graph showing the relationship between weight and AD value according to an embodiment. FIG. 5 is a flowchart showing an example of processing performed by a control unit of a weighing device according to an embodiment. FIG. 6 is a flowchart showing an example of load cell calibration processing performed by a control unit of a weighing device according to an embodiment. FIG. 7 is a flowchart showing an example of processing related to measuring the weight of an object to be weighed by a load cell performed by a control unit of a weighing device according to an embodiment.

[0008] Hereinafter, an embodiment of a weighing device 1 will be described with reference to the drawings. Note that the present invention is not limited to the following embodiment. The components in the following embodiment include those that can be easily conceived by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalent. Furthermore, various omissions, substitutions, modifications, and combinations of the components can be made without departing from the spirit of the following embodiment.

[0009] 1 is a schematic diagram showing the overall configuration of a weighing device 1 according to an embodiment. As shown in FIG. 1, the weighing device 1 includes an I / O port 2, a load cell 3, and a weighbridge 4.

[0010] The weighing device 1 is an example of a weighing device. The weighing device 1 measures the weight of an object to be weighed placed on the top surface of a weighing platform 4 based on the output of a load cell 3 connected to an I / O port 2 (described later).

[0011] The I / O port 2 is an example of a port. The I / O port 2 is an interface for electrically connecting the control unit 100 (see FIG. 2) of the weighing device 1 and the load cell 3. The weighing device 1 has a plurality of I / O ports 2. In FIG. 1, the weighing device 1 is configured to have six I / O ports 2, but the number of I / O ports 2 is not limited to this.

[0012] The load cell 3 is an example of a load cell. The load cell 3 is electrically connected to the control unit 100 (see FIG. 2 ) of the weighing device 1 by being connected to the I / O port 2. In the weighing device 1 of this embodiment, a plurality of load cells 3 are connected to the I / O port 2. Note that the number of load cells 3 is not limited to the illustrated example.

[0013] The load cell 3 is a load cell that is composed of, for example, a metal called a strain element, a resistance wire (hereinafter also referred to as a strain gauge) adhered to the strain element, and a circuit attached to the strain element. When weight (hereinafter also referred to as a load) acts on the strain element, the strain gauge deforms along with the strain element, causing a change in the resistance value of the strain gauge. A voltage (analog signal) is then output in accordance with the change in the resistance value of the strain gauge. In other words, an analog signal is output in accordance with the load acting on the load cell 3.

[0014] The load cell 3 may be a digital load cell integrated with an A / D conversion unit 5, which will be described later. The load cell 3 may also be a load cell that converts the load acting on the load cell 3 into an analog signal using a mechanism different from the mechanism described above.

[0015] The weighing platform 4 is a base that supports an object to be weighed by the weighing device 1. As shown in FIG. 1 , the weighing platform 4 is disposed so as to be in contact with the upper surface of the load cell 3. The weighing platform 4 applies the weight of the object to be weighed placed on the upper surface of the weighing platform 4 to the load cell 3.

[0016] Next, the configuration of the weighing device 1 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of the hardware configuration of the weighing device 1 according to the embodiment. As shown in Fig. 2, the weighing device 1 includes a CPU (Central Processing Unit) 101, which is an example of a processor, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a memory unit 104, etc.

[0017] The CPU 101 comprehensively controls each unit of the weighing device 1. The ROM 102 stores various programs. The RAM 103 is a workspace for developing programs and various data. The memory unit 104 stores various programs.

[0018] The CPU 101, ROM 102, RAM 103, and memory unit 104 are connected to one another via a bus 111. The CPU 101, ROM 102, and RAM 103 constitute a computer-configured control unit 100. That is, the control unit 100 executes the control processing of the weighing device 1, which will be described later, by the CPU 101 operating in accordance with a control program unit 105 stored in the ROM 102 and memory unit 104 and loaded into the RAM 103.

[0019] The memory unit 104 is a non-volatile memory such as a hard disk drive (HDD) or flash memory that retains stored information even when the power is turned off. The memory unit 104 includes a control program unit 105, a correction value DB 106, and a calibration setting DB 107.

[0020] The correction value DB 106 is an example of a storage unit. The correction value DB 106 is a database that stores correction values ​​used in a process related to the calibration of the load cell 3 (hereinafter also referred to as the calibration process), which will be described later. The correction value DB 106 also stores, for example, the identification number (hereinafter also referred to as the port number) of the I / O port 2 to which the load cell 3 is connected and a correction value related to the detection of weight derived for each load cell 3 associated with the port number, in association with each other.

[0021] The calibration setting DB 107 is a database that stores values ​​referenced as a correction standard (hereinafter also referred to as a master) in the calibration process. The calibration setting DB 107 stores, for example, AD values ​​at zero weight (hereinafter also referred to as the zero point). The calibration setting DB 107 also stores, for example, AD values ​​at the weight of a weight used in the calibration process (hereinafter also referred to as the calibration load). The calibration setting DB 107 also stores, for example, a threshold value (hereinafter also referred to simply as the threshold value) used to determine an abnormality in the load cell 3 in the calibration process.

[0022] Here, the threshold value stored in the calibration setting DB 107 is a master of the change characteristics of the AD value when the weight of the load cell 3 changes in the calibration process of the load cell 3, which will be described later. Hereinafter, for convenience, the AD value stored in the calibration setting DB 107 will be referred to as the master AD value, and the change characteristics of the AD value when the weight of the load cell 3 changes, which are stored in the calibration setting DB 107, will be referred to as the master change characteristics.

[0023] Here, the AD value is the output value when an analog signal output from the load cell 3 in response to a load is converted into a digital signal by the A / D converter 5, which will be described later. In other words, the AD value increases in proportion to the load acting on the load cell 3.

[0024] Next, the correction value will be described with reference to Fig. 3. Fig. 3 is an example of a graph showing the relationship between the AD value output by the load cell 3 according to the embodiment and the weight.

[0025] FIG. 3 is an example of a graph in which the horizontal axis represents weight and the vertical axis represents AD values. Note that the values ​​written on each axis are merely examples, and the scale of the axes is not limited. For example, FIG. 3 shows lines A and B corresponding to load cell A, which serves as the master in the calibration process, and load cell B, which is the load cell before the calibration process. Here, the change characteristics of the AD values ​​when the weight of the load cell 3 changes are defined as the slope of the lines in FIG. 3. The correction value is defined as the difference between the master change characteristics stored in the calibration setting DB 107, i.e., the slope of line A, and the change characteristics of the AD values ​​when the weight of the load cell 3 before the calibration process changes, i.e., the slope of line B.

[0026] 3, for example, if the AD values ​​at the zero point on both lines A and B are 20, and the calibration load is a weight of 20, and the AD value at weight 20 is 40 on line A and 30 on line B, the correction value is the difference between the slope of line A and the slope of line B, i.e., 0.5. The calculated correction value is an index that indicates how much adjustment is required for an arbitrary load cell 3 on which calibration processing is performed, relative to the master load cell 3.

[0027] 2 , the control unit 100 is connected to the I / O port 2, the display unit 109, and the operation unit 110 via the I / O controller 108 and the bus 111. The I / O controller 108 is connected to the display unit 109 and the operation unit 110. The I / O controller 108 controls each of the connected units based on commands from the control unit 100.

[0028] The display unit 109 is a display device such as an LCD (Liquid Crystal Display). The display unit 109 displays various information under the control of the CPU 101. The operation unit 110 is an input device such as a keyboard or a pointing device. The operation unit 110 outputs operation details input via the input device to the CPU 101. The operation unit 110 may be a touch panel provided on the display unit 109.

[0029] The A / D conversion unit 5 converts into a digital signal the analog signal output from the load cell 3 connected to the I / O port 2. The load cell 3 is connected to the I / O port 2. That is, the analog signal from the load cell 3 is converted into a digital signal by the A / D conversion unit 5 and input to the CPU 101.

[0030] The control unit 100 (CPU 101 ) can then calculate the load acting on the load cell 3 based on the AD value output by the load cell 3 that is input to the I / O port 2 .

[0031] Next, the control unit 100 of the weighing device 1 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing an example of the functional configuration of the control unit 100 in the weighing device 1 according to the embodiment. As shown in Fig. 4, the control unit 100 includes a calibration processing unit 1001, a weight detection unit 1002, and a display control unit 1003 as functional components.

[0032] Specifically, the control unit 100 (CPU 101) of the weighing device 1 realizes the above-mentioned functional configuration by executing the control program unit 105 stored in the memory unit 104. Note that in this embodiment, the above-mentioned functional configuration is a software configuration realized by cooperation between the processor and program of the weighing device 1, but this is not limiting, and some or all of the functional configuration may be realized as a hardware configuration using a dedicated circuit or the like.

[0033] The calibration processing unit 1001 is an example of a derivation means and a storage control means. Specifically, the calibration processing unit 1001 performs a calibration process to adjust (also called calibrate) the load cell 3 connected to the I / O port 2. There is no particular restriction on the method of the calibration process, and any publicly known and commonly used method can be adopted. The calibration processing unit 1001 performs the calibration process for each load cell 3, for example, by the method shown below.

[0034] The calibration processing unit 1001 calculates a correction value for weight detection for each load cell 3 connected to the I / O port 2 based on the AD value output by the load cell 3 with the calibration load attached to the load cell 3 and the AD value output by the load cell 3 with the calibration load removed. The calibration processing unit 1001 also stores the correction value for each load cell 3 in the correction value DB 106 in association with the port number of the I / O port 2 to which the load cell 3 is connected.

[0035] Furthermore, when the calibration processing unit 1001 receives an instruction to execute the calibration process via the operation unit 110, for example, it checks the electrical connection state of each of the I / O ports 2. Next, the calibration processing unit 1001 sequentially processes each of the I / O ports 2 to which the load cell 3 is connected, and sequentially executes the calibration process.

[0036] First, the calibration processing unit 1001 acquires the AD value at the zero point for the load cell 3 connected to the I / O port 2 to be processed. Next, the calibration processing unit 1001 extracts the AD value at the zero point, i.e., the master AD value, stored in the calibration setting DB 107. Next, based on the acquired AD value and the extracted master AD value, the calibration processing unit 1001 calculates a correction value (hereinafter also referred to as the correction value at the zero point) for correcting the acquired AD value to the master AD value.

[0037] The calibration processing unit 1001 determines whether the calculated correction value at the zero point is within the threshold range stored in the calibration setting DB 107. If the calculated correction value at the zero point is within the threshold range stored in the calibration setting DB 107, the calibration processing unit 1001 associates the calculated correction value at the zero point with the port number of the I / O port 2 to be processed and stores them in the correction value DB 106, that is, performs zero point correction.

[0038] When performing zero-point correction, the calibration processing unit 1001 determines whether the acquired AD value is within the threshold range of the master AD value at the zero point stored in the calibration setting DB 107. If the acquired AD value is outside the threshold range, the calibration processing unit 1001 determines that the target I / O port 2 is in an invalid state and, in cooperation with the display control unit 1003 (described later), displays on the display unit 109 the port number of the I / O port 2 to which the load cell 3 corresponding to the acquired AD value is connected. For example, the calibration processing unit 1001 displays on the display unit 109 the port number of the I / O port 2 to which the load cell 3 is connected, as well as a message informing the user that there is an abnormality in the load cell 3. Here, the fact that the target I / O port 2 is in an invalid state means that the I / O port 2 is in an unusable state and is not subject to calibration processing.

[0039] After performing zero-point correction for all I / O ports 2 targeted for processing, the calibration processing unit 1001 extracts the master change characteristics stored in the calibration setting DB 107. Next, the calibration processing unit 1001 causes the display unit 109 to display a message instructing the user to attach a weight of a predetermined weight (e.g., a calibration load) to any one of the load cells 3. At this time, it is preferable that the display control unit 1003 causes the display unit 109 to display a message instructing the user to apply the predetermined weight directly to the load cell 3, for example, by removing the weighing platform 4 from the weighing device 1 and attaching a weight to the load cell 3.

[0040] When the calibration processing unit 1001 and the weight detection unit 1002 described later detect, based on a change in the AD value, that a weight has been placed on one of the load cells 3, they acquire an AD value corresponding to the weight of the detected weight. Next, the calibration processing unit 1001 calculates the change characteristics of the AD value when the weight changes from the master AD value at the zero point and the AD value corresponding to the weight of the weight detected by the weight detection unit 1002 described later.

[0041] Next, the calibration processing unit 1001 calculates a correction value for the change characteristic based on the difference between the master change characteristic extracted from the calibration setting DB 107 and the calculated change characteristic.

[0042] Next, the calibration processing unit 1001 determines whether the calculated correction value for the change characteristic is within the threshold range stored in the calibration setting DB 107. If the correction value for the change characteristic is within the threshold range stored in the calibration setting DB 107, the calibration processing unit 1001 associates the correction value for the change characteristic with the port number of the I / O port 2 to be processed and stores the associated value in the correction value DB 106, i.e., executes the calibration process.

[0043] On the other hand, if the correction value related to the change characteristic is outside the threshold range, the calibration processing unit 1001 determines that the target I / O port 2 is in an invalid state, and in cooperation with the display control unit 1003 (described later), displays on the display unit 109 the port number of the I / O port 2 to which the load cell 3 corresponding to the acquired AD value is connected. For example, the calibration processing unit 1001 displays on the display unit 109 the port number of the I / O port 2 to which the load cell 3 is connected, as well as a message informing that there is an abnormality in the load cell 3.

[0044] It is desirable to carry out the above-described series of calibration processes in a configuration in which the weighing platform 4 is excluded from the configuration of the weighing device 1 in order to improve the accuracy of the calibration process of the load cell 3.

[0045] The weight detection unit 1002 is an example of a weighing unit. Specifically, the weight detection unit 1002 measures the load acting on each of the load cells 3. More specifically, the weight detection unit 1002 measures the weight of the object to be weighed based on the AD value output by the load cell 3 connected to the I / O port 2.

[0046] Furthermore, when the weight detection unit 1002 detects that a weight has been placed on one of the load cells 3 based on a change in the AD value output by the load cell 3, it outputs an AD value corresponding to the detected weight of the weight.

[0047] Furthermore, the weight detection unit 1002 measures the weight of the object to be weighed placed on the weighing platform 4 of the weighing device 1. Then, the weight detection unit 1004 applies a correction value calculated for each load cell 3 to the AD value output from each load cell 3 individually connected to the I / O port 2. Then, the weight detection unit 1002 measures the weight of the object to be weighed based on the AD value to which the correction value has been applied.

[0048] The display control unit 1003 displays various information on the display unit 109. Specifically, when the calibration processing unit 1001 checks the electrical connection state of each I / O port 2 and determines that the I / O port 2 being checked is in an invalid state, the display control unit 1003 displays on the display unit 109 the port number of the I / O port 2 that has been determined to be in an invalid state and a message indicating that the I / O port 2 being checked is in an invalid state.

[0049] Furthermore, the display control unit 1003 cooperates with the calibration processing unit 1001 to cause the display unit 109 to display various types of information.

[0050] Furthermore, in the process of measuring the weight of the objects to be measured, the display control unit 1003 displays on the display unit 109 an instruction to place the objects to be measured on the upper surface of the weighing platform 4. Furthermore, the display control unit 1003 calculates the total weight of the objects to be measured from the weights of the objects to be measured calculated for each load cell 3, and displays this on the display unit 109.

[0051] An example of the processing performed by the weighing device 1 described above will be described below.

[0052] FIG. 5 is a flowchart showing an example of processing performed by the control unit 100 of the weighing device 1 according to the embodiment.

[0053] First, the calibration processing unit 1001 waits until a calibration process is executed via the operation unit 110 (step S101; No). When the calibration processing unit 1001 receives a command to execute the calibration process via the operation unit 110 (step S101; Yes), the calibration processing unit 1001 sequentially checks the electrical connection status of each of the I / O ports 2 (step S102).

[0054] If it is confirmed that the load cell 3 is electrically connected to the I / O port 2 being checked (step S102; Yes), the calibration processing unit 1001 determines that the I / O port 2 being checked is in a valid state and proceeds to step S104.

[0055] Furthermore, if it cannot be confirmed that the load cell 3 is electrically connected to the I / O port 2 to be checked (step S102; No), the calibration processing unit 1001 determines that the I / O port 2 to be checked is in an invalid state. In this case, the calibration processing unit 1001, in cooperation with the display control unit 1003 (described later), displays a message on the display unit 109 indicating that the I / O port 2 to be checked is in an invalid state (step S103), and proceeds to step S104.

[0056] In the next step S104, it is determined whether the status of all I / O ports 2 has been confirmed (step S104). If an unconfirmed I / O port 2 exists (step S104; No), the calibration processing unit 1001 returns to step S102 and determines whether the unconfirmed I / O port 2 is valid or invalid. On the other hand, if it is determined that the status of all I / O ports 2 has been confirmed (step S104; Yes), the calibration processing unit 1001 selects the load cells 3 connected to the valid I / O ports 2 as the processing targets for the calibration processing, and sequentially executes the calibration processing (step S105).

[0057] Next, an example of processing performed by the weighing device 1 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing an example of a calibration process for the load cell 3 performed by the control unit 100 of the weighing device 1 according to the embodiment. Note that the series of steps shown in Fig. 6 corresponds to the subroutine processing of step S105 shown in Fig. 5.

[0058] First, the calibration processing unit 1001 extracts the AD value at the zero point stored in the calibration setting DB 107, that is, the master AD value (step S201).

[0059] Next, the calibration processing unit 1001 acquires the AD value at the zero point of the load cell 3 for the load cell 3 connected to the I / O port 2 to be processed (step S202). At this time, nothing is placed on the top surface of the weighbridge 4. Note that the calibration processing unit 1001 preferably performs the calibration in a state where the weighbridge 4 and the load cell 3 are separated from each other, for example, by removing the weighbridge 4.

[0060] Next, the calibration processing unit 1001 calculates a correction value (hereinafter also referred to as a correction value at the zero point) for correcting the acquired AD value to the master AD value based on the acquired AD value and the extracted master AD value (step S203).The calibration processing unit 1001 then determines whether the calculated correction value at the zero point is within a threshold range stored in the calibration setting DB 107 (step S204).

[0061] If the calculated correction value at the zero point is within the threshold range stored in the calibration setting DB 107 (step S204; Yes), the calibration processing unit 1001 associates the calculated correction value at the zero point with the port number of the I / O port 2 to be processed and stores the associated value in the correction value DB 106 (step S206). Next, the calibration processing unit 1001 proceeds to step S207.

[0062] Furthermore, if the calculated correction value at the zero point is outside the threshold range stored in the calibration setting DB 107 (step S204; No), the calibration processing unit 1001, in cooperation with the display control unit 1003 described later, displays a message on the display unit 109 indicating that the target I / O port 2 is in an invalid state (step S205), and proceeds to step S207.

[0063] In the next step S207, the calibration processing unit 1001 determines whether or not the processes of steps S202 to S206 have been executed for all valid I / O ports 2 (step S207). If an unprocessed I / O port 2 remains (step S207; No), the calibration processing unit 1001 returns the process to step S202. If all I / O ports 2 have been processed (step S207; Yes), the calibration processing unit 1001 extracts the master change characteristics stored in the calibration setting DB 107 (step S208).

[0064] Next, the calibration processing unit 1001, in cooperation with the display control unit 1003 (described later), causes the display unit 109 to display a message instructing the user to place a weight of a predetermined weight (e.g., a calibration load) on any one of the load cells 3 (step S209). At this time, the display unit 109 also displays a message instructing the user to apply the predetermined weight directly to the load cell 3, for example, by removing the weighbridge 4 and then attaching the weight to the load cell 3.

[0065] The calibration processing unit 1001 waits until the weight detection unit 1002 detects that a weight has been placed on one of the load cells 3 based on a change in the AD value (step S210; No), and when it detects that a weight has been placed on one of the load cells 3 (step S210; Yes), it acquires the AD value corresponding to the weight of the detected weight (step S211).

[0066] In step S210, the load cell 3 connected to the I / O port 2 that detected the installation of a weight is treated as the processing target, and processing proceeds to step S211 and subsequent steps. However, the load cell 3 to be processed may also be specified by inputting a port number from the operation unit 110, etc.

[0067] Next, the calibration processing unit 1001 calculates a change characteristic of the AD value when the weight changes from the master AD value at the zero point and the AD value corresponding to the weight of the weight detected by the weight detection unit 1002 (step S212). Next, the calibration processing unit 1001 calculates a correction value for the change characteristic from the difference between the master change characteristic extracted from the calibration setting DB 107 and the calculated change characteristic (step S213). Then, the calibration processing unit 1001 determines whether the calculated correction value for the change characteristic is within a threshold range stored in the calibration setting DB 107 (step S214).

[0068] If the calculated correction value for the change characteristic is within the threshold range stored in the calibration setting DB 107 (step S214; Yes), the calibration processing unit 1001 associates the calculated correction value for the change characteristic with the port number of the I / O port 2 to be processed and stores the associated value in the correction value DB 106 (step S216). Next, the calibration processing unit 1001 proceeds to step S217.

[0069] Furthermore, if the calculated correction value for the change characteristic is outside the threshold range stored in the calibration setting DB 107 (step S214; No), the calibration processing unit 1001, in cooperation with the display control unit 1003 described later, displays a message on the display unit 109 indicating that the target I / O port 2 is in an invalid state (step S215), and proceeds to step S217.

[0070] In the next step S217, the calibration processing unit 1001 determines whether or not the processes of steps S209 to S216 have been executed for all valid I / O ports 2 (step S217). If an unprocessed I / O port 2 exists (step S217; No), the calibration processing unit 1001 returns the process to step S209. On the other hand, if all I / O ports 2 have been processed (step S217; Yes), the calibration processing unit 1001 ends the process by returning to the process of FIG. 5.

[0071] 6, the connection status of the load cell 3 can be checked for each I / O port 2 and the load cell 3 can be calibrated, thereby efficiently acquiring and managing the correction values ​​for each load cell 3. Furthermore, by applying the correction values ​​calculated in the calibration process to the AD values ​​output by the load cells 3 of the corresponding port numbers, each load cell 3 can have the same weighing accuracy.

[0072] Next, an example of processing performed by the weighing device 1 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of processing related to measuring the weight of an object to be weighed by the load cell 3, performed by the control unit 100 of the weighing device 1 according to the embodiment.

[0073] First, the calibration processing unit 1001 sequentially checks the electrical connection state of each of the I / O ports 2 (step S301). If it is confirmed that the load cell 3 is electrically connected to the I / O port 2 being checked (step S301; Yes), the calibration processing unit 1001 determines that the I / O port 2 being checked is in a valid state, and proceeds to step S303.

[0074] Furthermore, if it cannot be confirmed that the load cell 3 is electrically connected to the I / O port 2 to be confirmed (step S301; No), the calibration processing unit 1001 determines that the I / O port 2 to be confirmed is in an invalid state. In this case, the calibration processing unit 1001, in cooperation with the display control unit 1003 (described later), displays a message on the display unit 109 indicating that the I / O port 2 to be confirmed is in an invalid state (step S302), and proceeds to step S303.

[0075] In the next step S303, it is determined whether or not the status of all I / O ports 2 has been confirmed (step S303). If an unconfirmed I / O port 2 exists (step S303; No), the calibration processing unit 1001 returns the process to step S301 and determines whether the unconfirmed I / O port 2 is valid or invalid.

[0076] Furthermore, if it is determined that the status of all I / O ports 2 has been checked (step S303; Yes), the display control unit 1003, in cooperation with the calibration processing unit 1001, displays on the display unit 109 an instruction to place the object to be weighed on the top surface of the weighing platform 4 (step S304).

[0077] It should be noted that the processes from step S301 to step S303 do not necessarily have to be performed, and the process may start from step S304.

[0078] Next, the calibration processing unit 1001 waits until the weight detection unit 1002 detects the weight of the object to be weighed by one of the load cells 3 due to a change in the AD value (step S305; No), and when one of the load cells 3 detects the weight of the object to be weighed (step S305; Yes), it acquires the AD value corresponding to the weight of the object to be weighed detected for each of the load cells 3 connected to the I / O port 2 that is in an active state (step S306).

[0079] Next, the calibration processing unit 1001 refers to the correction value DB 106 and extracts the port number and the correction value associated with the port number stored in the correction value DB 106. Then, the calibration processing unit 1001 applies the correction value corresponding to the port number of the I / O port 2 to which the load cell 3 is connected to the valid I / O port 2, to the AD value corresponding to the weight of the object to be weighed detected by the load cell 3 connected to the valid I / O port 2 (step S307).

[0080] Next, the calibration processing unit 1001 calculates the weight of the object to be weighed from the AD value detected by the load cell 3 connected to the valid I / O port 2 and to which the correction value has been applied (step S308). Subsequently, the calibration processing unit 1001, in cooperation with the display control unit 1003, calculates the total weight of the object to be weighed from the weights of the object to be weighed calculated for each load cell 3 and displays it on the display unit 109 (step S309).

[0081] As described above, the weighing device 1 of this embodiment determines whether one or more load cells 3 connected to the I / O port 2 are connected to the I / O port 2. Next, the weighing device 1 performs zero-point correction for the load cells 3 whose connection to the I / O port 2 is valid by receiving an execution instruction from the operation unit 110. Next, the weighing device 1 calculates the change characteristics of the AD value when weight changes, i.e., the correction value, for the load cells 3 whose connection to the I / O port 2 is valid. Then, if the calculated correction value is within the threshold range, calibration is performed, and then the identification number of the I / O port 2 and the calculated correction value are stored in the database.

[0082] This makes it possible to calculate a correction value related to the weighing accuracy for each load cell 3 and perform calibration of one or more load cells 3. Therefore, it is possible to improve the weighing accuracy of a weighing device 1 equipped with multiple load cells 3.

[0083] The above-described embodiment can be modified as needed by partially changing the configuration or functions of each of the above-described devices. Therefore, several modifications of the above-described embodiment will be described below as other embodiments. The following mainly focuses on differences from the above-described embodiment, and detailed descriptions of commonalities with the content already described will be omitted. The modifications described below may be implemented individually or in appropriate combination.

[0084] (Variation 1) The weighing device 1 described in the above embodiment may be applied to, for example, a sales data processing device used in the field of commercial transactions. In this case, the sales data processing device may be applied as, for example, a weighing device that weighs products to be registered and / or products that have already been registered in a semi-self-service or full-self-service POS.

[0085] (Variation 2) In the above embodiment, the calibration process is performed with the load cell 3 attached to the weighing device 1, but this is not limiting, and the calibration process may be performed with the load cell 3 removed from the weighing device 1. Furthermore, the calibration process may be performed before the load cell 3 is attached to the weighing device 1.

[0086] The programs executed by the weighing device 1 of the embodiment and the modified examples may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the programs executed by the weighing device 1 of the embodiment and the modified examples may be provided or distributed via a network such as the Internet.

[0087] The programs executed by each device in the above-described embodiments are provided in a state where they are pre-installed in a ROM, a storage unit, etc. The programs executed by each device in the above-described embodiments may be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a digital versatile disk (DVD).

[0088] Furthermore, the programs executed by each device in the above-described embodiments may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the programs executed by each device in the above-described embodiments may be provided or distributed via a network such as the Internet.

[0089] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments and their modifications can be embodied in various other forms, and various omissions, substitutions, changes, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims.

[0090] (Additional Notes) The above description of the embodiments discloses the following technologies: (1) A weighing device comprising: a plurality of ports for connecting load cells; a weighing unit that weighs the weight of an object to be weighed based on the detection results of each of the load cells individually connected to the plurality of ports; and a memory unit that stores a correction value related to the weight detection derived for each of the load cells in association with a port identifier that can identify the port to which the load cell is connected, wherein the weighing unit measures the weight of the object to be weighed based on the result of correcting the weight detection result detected by each of the load cells with the correction value corresponding to the port identifier of the port to which the load cell is connected. (2) The weighing device described in (1), further comprising a base for supporting the object to be weighed, wherein each of the load cells connected to the plurality of ports is provided on the common base. (3) The weighing device according to (1), further comprising: a derivation means for deriving a correction value for weight detection based on the detection result of a state in which an object of a predetermined weight is attached to the load cell and the detection result of the load cell with the object removed, for each of the load cells connected to the port; and a memory control means for storing the correction value for each of the load cells derived by the derivation means in the memory unit in association with the port identifier of the port to which the load cell is connected. (4) The weighing device according to (3), further comprising: a derivation means for notifying the port identifier of the port to which the load cell is connected when the detection result of the load cell with the object removed deviates from a first threshold range. (5) The weighing device according to (3) or (4), wherein the derivation means disables the port to which the load cell is connected when the characteristic of the load cell derived based on the detection result of the load cell when the object to be weighed is removed, the detection result of the load cell when the object to be weighed is attached, and the weight of the object to be weighed deviates from a second threshold range.(6) A method for calibrating a load cell attached to a weighing device, wherein the weighing device has a plurality of ports for connecting the load cells, the calibration method including: an acquisition step of acquiring, for each of the load cells individually connected to the plurality of ports, a detection result of the load cell when a weighing object of a predetermined weight is attached to the load cell and a detection result of the load cell when the weighing object is removed; a derivation step of deriving a correction value related to weight detection for each of the load cells based on the detection results acquired in the acquisition step; and a storage step of storing the correction value derived for each of the load cells in association with a port identifier that can identify the port to which the load cell is connected.

[0091] Japanese Patent Application Laid-Open No. 2003-035592

Claims

1. A weighing device comprising: a plurality of ports for connecting load cells; a weighing unit that weighs the weight of an object to be weighed based on detection results of each of the load cells individually connected to the plurality of ports; and a storage unit that stores correction values related to detection of the weight derived for each load cell in association with a port identifier capable of identifying the port to which the load cell is connected, wherein the weighing unit weighs the weight of the object to be weighed based on a result of correcting the detection result of the weight detected by each of the load cells with the correction value corresponding to the port identifier of the port to which the load cell is connected.

2. The weighing device according to claim 1, further comprising: a derivation means for deriving a correction value related to weight detection based on a detection result in a state where a weighing object of a predetermined weight is attached to the load cell and a detection result of the load cell in a state where the weighing object is removed, for each load cell connected to the port; and a storage control means for storing, in the storage unit, the correction value for each load cell derived by the derivation means in association with the port identifier of the port to which the load cell is connected.

3. The weighing device according to claim 2, wherein the derivation means notifies the port identifier of the port to which the load cell is connected when the detection result of the load cell in a state where the weighing object is removed deviates from a first threshold range.

4. The weighing device according to claim 2 or 3, wherein the derivation means invalidates the port to which the load cell is connected when the characteristics of the load cell derived based on the detection result of the load cell in a state where the weighing object is removed, the detection result of the load cell in a state where the weighing object is attached, and the weight of the weighing object deviate from a second threshold range.

5. A calibration method for a load cell attached to a weighing device, the weighing device including a plurality of ports for connecting the load cell, and for each load cell individually connected to the plurality of ports, an acquisition step of acquiring a detection result in a state where a weighing object of a predetermined weight is attached to the load cell and a detection result of the load cell in a state where the weighing object is removed; a derivation step of deriving a correction value related to weight detection for each load cell based on the detection result acquired in the acquisition step; and a storage step of storing the correction value derived for each load cell in association with a port identifier capable of identifying the port to which the load cell is connected.

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