Span adjustment method

Abstract

To perform more accurate weight measurement by reducing deviation value errors in a weight measurement instrument having a hopper-type load cell at one end.SOLUTION: Using a weight measurement instrument capable of performing more accurate weight measurement by placing an object to be measured in weight directly above a load cell such as a platform balance or a general load cell balance, the weight of a reference object for performing span adjustment is carried out. Then, by placing the reference object on a weight measurement unit of the weight measurement instrument having a load cell of a hopper type or the like at one end to perform the span adjustment, weight measurement can be carried out as accurately as possible.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a span adjustment method for measuring the weight of agricultural produce using a hopper-type weighing machine. [Background technology]

[0002] A load cell scale, which is one type of weight measuring device, performs span adjustment for calibration when measuring the weight of an object to be measured. This span adjustment has the purpose of making the weight measuring device recognize the accurate weight under the measurement environment.

[0003] At this time, a standard weight for calibration is generally used to perform span adjustment. However, with this method, if the size or shape of the standard weight and the weight measurement target differ, an error will occur between the measured value and the actual weight due to eccentricity error. This error is very small, so it does not pose a major problem in general weight measurements.

[0004] However, if the weight of the object to be weighed increases and the weighing pan mechanism is made cantilevered to accommodate a long object, the distance between the fulcrum of the weighing sensor and the point of application of the actual weight increases, causing an increase in bias error, resulting in an amount greater than the actual weight being discharged.

[0005] This problem becomes more pronounced, for example, when measuring the weight of agricultural produce. This is because agricultural produce has a variety of shapes, making it impossible to standardize the measurement conditions, and the weight of each produce is relatively large. Therefore, the standard for span adjustment is important, and it is necessary to adjust it so that measurement errors are less likely to occur.

[0006] This offset error can be eliminated by changing the long weighing gate with a cantilever structure to a weighing gate with a double-support structure, or by adopting a structure in which the fulcrum of the weighing sensor is located at the center of the weighing gate. However, adopting such a structure leads to problems such as a complex structure, high costs, and difficulty in maintenance such as cleaning, reducing workability.

[0007] Accurate weight measurement of agricultural products can prevent problems during shipping. In particular, shipping products that are underweight can cause problems, while products that are overweight can result in unnecessary costs. For this reason, accurate gravity measurement is important.

[0008] In addition, accurate weight measurement can prevent errors caused by weight-based classification, making this a more desirable technique for measuring the weight of agricultural produce, which is frequently classified into classes and weighed in combination based on weight measurements.

[0009] The present invention proposes a new measurement method for measuring the weight of long objects or objects with irregular shapes, such as agricultural products, by improving on the conventional span adjustment method and minimizing the occurrence of weight measurement errors. Summary of the Invention [Problem to be solved by the invention]

[0010] Before measuring weight with a scale, it is common to calibrate it by performing zero point correction and span adjustment to set a standard. The purpose of these calibrations is that the measured value varies depending on the measurement environment, such as latitude and altitude. For this reason, it is necessary to make the scale accurately recognize the weight based on the load in the measurement environment.

[0011] When measuring the weight of an object after span adjustment using a standard weight, if the shape of the object to be weighed is irregular and the center of gravity is not stable, an error will occur between the measured value and the true weight. This difference becomes larger as the weight of the object increases.

[0012] Here, if the weight measurement object is a relatively light item or does not require precise weight measurement, this is not a big problem. However, in the case of agricultural produce in the agricultural field, this problem becomes more pronounced. This is because the outer shape of the agricultural produce differs from that of the standard weight, and there are various shapes such as rectangular or spherical.

[0013] For this reason, in the past, when measuring weight in agricultural operations, efforts were made to ensure accurate weight measurement by fixing the loading position of the measurement object as much as possible to prevent offset errors, or by aligning the measurement direction of the weight measurement object. However, there is a limit to how accurate weight measurement can be, and when measuring the weight of agricultural products, there are many cases where the measured weight value differs from the actual weight by several grams. Therefore, there is room for improvement in measuring the weight of agricultural products.

[0014] Furthermore, when measuring weights in agricultural operations, there are hopper-type weighing instruments with a load cell disposed at one end. When measuring weights using such weighing instruments, the deviation error described above during span adjustment becomes even larger. This is because the load cell is located at the end, and the forces acting on the load cell are not uniform. In particular, since a standard weight is used for general span adjustment, when a span adjustment is performed with a standard weight for such a hopper-type weighing device and the measurement target is an agricultural product or the like, the measured weight value and the actual weight value will differ significantly.

[0015] In the present invention, when using such a hopper-type weight measuring device to measure the weight of agricultural produce in the agricultural field, the conventional span adjustment method is improved, and a new span adjustment method is provided that enables more accurate weight measurement. [Means for solving the problem]

[0016] The present invention provides a span adjustment method for agricultural products, which vary widely in size, length, and shape even for the same type of product, when measuring the weight of the product using a weight measuring device having a load cell arranged at one end of the device, such as a hopper type.The method performs span adjustment in advance using an item of the same type as the product to be weighed, and then measures the same type of product to be weighed continuously without delay, thereby reducing offset errors and enabling as accurate weight measurement as possible.

[0017] More specifically, when performing span adjustment in a weight measuring device, the span adjustment is performed using the object to be measured itself instead of a weight, and the weight of the object is fixed. Effect of the Invention

[0018] The present invention enables more accurate weight measurement of agricultural produce. This reduces errors such as errors from the target weight at the time of shipping and errors when determining whether the product complies with standards based on the product's weight. When measuring the weight of agricultural produce, the weight of each product is considerable, and the products may be weighed one by one and then packed together. In this case, the weight of the packed products becomes considerable, and the difference from the actual weight increases. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram showing an embodiment of the present invention. [Diagram 2] FIG. 13 is a diagram showing average deviation errors when adjustment is performed using a conventional span adjustment method and when adjustment is performed using the span adjustment method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [1. Principle of the present invention] An embodiment of the present invention will be described below. First, the principle of the present invention will be described with reference to FIG. 1. As shown in FIG. 1, in the case of a scale 10 such as a general load cell scale or platform scale, a load cell (load cell 4 for platform scale) is present at the bottom of a platform scale weight measurement portion 1 on which an object 3 to be weighed is placed. The load cell functions as a sensor for detecting gravity and detects the force acting on that portion. Specifically, when a specific force is applied to a certain portion of the load cell, a strain is generated in one direction in the strain body inside the load cell, and the resistance value of the strain gauge connected to the strain body changes. The amount of change in the resistance value of this strain gauge is output as an electric signal and displayed as a weight measurement value.

[0021] When measuring weight using this mechanism, a standard weight is used to perform span adjustment in advance. That is, a standard weight with a known weight is used, the weight measuring device recognizes a strictly accurate weight, and the weight is measured using this value as a reference. A typical load cell scale is a scale that senses gravity and calculates weight, so the measured value varies depending on the measurement location due to differences in gravitational acceleration based on latitude and altitude, horizontal errors due to the inclination of the scale, and the like. For this reason, this span adjustment needs to be performed in the same environment as the environment in which the weight of the object to be measured is measured.

[0022] In a typical span adjustment, the reference weight having a circular cross section is placed on a weighing pan or the like located at the platform scale weight measurement area 1, and the span adjustment is performed. However, after the span adjustment, when an agricultural product item is placed on the platform scale weight measurement area 1 and its weight is measured, the shape and size of the agricultural product item differs from that of the reference weight. Therefore, the direction of the force applied to the load cell is not the same when the reference weight is placed and when the agricultural product item is placed.

[0023] Here, since the load cell is a device that senses gravity for weight measurement, if the direction of gravity acting on the load cell is not the same, the measured value will be inaccurate. For this reason, since the system uses a standard weight to calculate the weight measurement from a span-adjusted standard weight value, if the size or shape of the standard weight and the weight object are different, the direction of the force acting on the load cell will not be in one direction like the standard weight, and precise gravity measurement will not be possible.

[0024] In particular, agricultural produce has a non-uniform shape and each individual produce is large in weight, so that the above-mentioned error becomes particularly noticeable and causes a problem when measuring the weight of agricultural produce.

[0025] In addition, as shown in FIG. 1, a hopper-type device 20 for measuring the weight of agricultural products includes a load cell disposed at one end of the device and measuring the weight of products loaded on a container connected to the load cell. In such a device, the load cell is unevenly located at one end, and force is not applied directly from directly above the load cell. Therefore, deviation errors are likely to occur, and the difference between the measured weight and the actual weight increases. This weight difference can be as much as 2 g for an item weighing about 100 g, such as chives, when the distance between the fulcrum of the weighing sensor and the point of application of the weight measurement is 20 cm, by changing the weight measurement position on the same device. Therefore, in combination weighing, which performs weighing based on a single weight result, a deviation error of up to 6 g can occur when selecting three optimal combinations, for example, when a deviation error of 2 g occurs per item as described above.

[0026] A detailed explanation of the case of a hopper-type weighing machine will be given below with reference to Fig. 1. As shown in the hopper-type device 20, the hopper-type weighing machine has a weight measurement section 5 of the hopper-type weighing machine disposed adjacent to a main body section 6 of the hopper-type weighing machine, and weight measurement is performed on the weight measurement section 5 of the hopper-type weighing machine.

[0027] Here, the load cell 7 for the hopper type weighing machine of the hopper type weighing device is disposed inside the hopper type weighing machine main body portion 6. The reason for such a structure is related to the process of processing the weight measurement object 3 after the weight measurement. That is, after the weight of the weight measurement object 3 is measured, the hopper lower opening of the hopper type weighing machine weight measurement portion 5 located directly below the weight measurement object 3 opens, and the weight measurement object 3 falls to the bottom as it is. Then, the weight measurement object 3 lands on the hopper type weighing machine transport conveyor 8, and the hopper type weighing machine transport conveyor 8 is operated to transport the weight measurement object 3. For this reason, a load cell cannot be disposed directly below the weight measurement object 3.

[0028] Therefore, if a span adjustment is performed using a standard weight and then a weight measurement is performed on an agricultural item of a different shape, the direction of the force applied to the load cell 7 for the hopper type weighing machine will differ, resulting in an inaccurate weight measurement. In the present invention, by performing span adjustment using an item of the same type as the object to be weighed instead of a standard weight, the direction of the force applied to the load cell 7 for the hopper type weighing machine during span adjustment and weight measurement will be the same, making it possible to perform accurate weight measurements.

[0029] 2. EMBODIMENTS OF THE PRESENT APPLICATION First, the device constituting the present invention will be described. The device constituting the present invention is the device shown in FIG. 1. The device on the left side of FIG. 1 is a general platform scale or load cell scale. The hopper-type weight measuring device on the right side of FIG. 1 is composed of a hopper-type weight measuring machine weight measuring section 5 which is a weighing section, a hopper-type weight measuring machine main section 6 which is a main section, a hopper-type weight measuring machine load cell 7 which is a weight measuring position, and a hopper-type weight measuring machine transport conveyor 8 which is a transport path for weight measurement objects. Among these, the hopper-type weight measuring machine weight measuring section 5 is a weighing dish or the like, and is composed of two vertically long rectangular plastic plate-like structures. This section is fixed by a fixing device such as a screw on the hopper-type weight measuring machine main section 6 side. Each of these sections constitutes a side portion of the V shape so that it forms a V shape in cross section. Then, the weight measurement object is loaded in the valley of the V shape, and weight measurement is performed. After the weight measurement, the two plastic plates are opened to the left and right, that is, the bottom of the V-shape opens, and the object to be weight measured falls onto the hopper-type weight measuring machine conveyor 8 directly below.

[0030] The two plastic plates constituting the weight measuring unit are made of, for example, polycarbonate resin and have a thickness of approximately 2 mm. However, other synthetic resins, metals, and the like can be used regardless of their form as long as they provide the same effects.

[0031] Next, a specific procedure of the present invention will be described with reference to Fig. 1. First, an object 3 to be weighed, such as chives, is placed on a platform scale weight measurement section 1 arranged on top of a general platform scale main body section 2 (or a load cell scale would also do), and its weight is measured (step S1). In such a platform scale weight measurement section 1, a platform scale load cell 4 is arranged directly below the approximate center of the platform scale weight measurement section 1, so that the gravity of the object 3 to be weighed is applied to the load cell 4 from directly above it. Therefore, the direction of the force applied to the load cell is the same as the direction of gravity, and the platform scale that measures gravity can perform accurate weight measurements.

[0032] Next, the objects 3 to be weighed are loaded onto the weight measurement site 5 of the hopper-type weighing machine (step S2). This step S2 should be carried out as quickly as possible, but if it is carried out within, for example, 10 minutes after the weight measurement on the platform scale 2, there will be no significant change in weight due to drying, and the weight measurement will not be significantly hindered.

[0033] Then, the weight measurement object 3 is loaded on the weight measurement portion 5 of the hopper type weighing machine, and the span adjustment is performed (step S3).

[0034] After the span adjustment, the objects to be weighed are loaded one by one onto the weight measurement site 5 of the hopper-type weighing machine and measured. At this time, the weight of an object of the same type as the object to be weighed 3 used for the span adjustment is measured. In this figure, the object is, for example, chives. The objects are loaded in the same orientation and in the same position as during the span adjustment, and their weights are measured. The objects to be weighed are as similar in length and size as possible.

[0035] [3. Advantages of the present invention] The span adjustment method of the present invention has the following advantages.

[0036] As mentioned above, the direction of the load on the load cell is almost the same during span adjustment and during weight measurement. As a result, it is possible to perform precise weight measurements of agricultural products. This precise weight measurement is particularly effective for measurements in which the load cell is located at one end, such as with a hopper type. As a result, it is possible to expect more accurate weight measurements, correcting for errors of about 2 g, for agricultural products such as chives weighing about 100 g.

[0037] Detailed measurement data is shown in Figure 2. The measurement data was obtained by measuring a 45 cm long leek weighing approximately 100 g using the hopper-type weighing device shown on the right in Figure 1. The number of samples used in the measurement, n, was 30, and weight measurements were performed using either the conventional span adjustment method using weights or the span adjustment method of the present invention that takes measures against bias errors. After each span adjustment, the weight was measured using the hopper-type weighing device at each stage, and then using the general weighing device shown on the left in Figure 1.

[0038] Then, the weight measurement data measured using a general weight measuring device is used as the actual weight value, and the weight measurement data measured using a hopper-type weight measuring device is used as the measured value. The measured value is subtracted from the actual weight value, and the resulting value is calculated as the weight error.

[0039] As shown in Fig. 2, for an article weighing approximately 100g, the average weight error with conventional span adjustment was as much as 2.2g, whereas the span adjustment method of the present invention produced a deviation error of only 0.25g. As shown by such measurement data, the span adjustment method of the present invention is useful in a weight measuring device in which a hopper-type or other load cell is disposed at one end of the weight measuring device.

[0040] Improving the accuracy of errors of a few grams is important in agricultural operations. In other words, in the agricultural process, shipments of about several hundred grams to a few kilograms are very common. For this reason, when dividing and measuring, if an error of a few grams occurs in an amount of about 100 grams, this results in a large error in the total amount. As mentioned above, for example, in the case of Chinese chives, an error of about 2 grams occurs in an item of about 100 grams, and the item is displayed as 98 grams. The present invention can address such problems.

[0041] Furthermore, when performing span adjustment using the same type of item, there is no need to prepare a standard weight, and it is possible to easily perform the adjustment by using one of the harvested items.

[0042] Furthermore, as the span adjustment can be performed on any type of product, the method is versatile and can be used regardless of the type of crop.

[0043] The present invention relates to a special weight measurement method, which is a span adjustment method for a hopper type weight measurement device, and therefore, no prior art documents are described.

[0044] The present invention is not limited to the above embodiment. The span adjustment method can be applied to any agricultural product regardless of the type of weight measurement object. In addition, the span adjustment method is not limited to agricultural products, but can be applied to all natural objects such as seafood, etc., as long as there is a certain degree of commonality in shape within the same type. In addition, the size of the measurement object does not matter, from a few centimeters to a few meters. [Explanation of symbols]

[0045] 1 scale weight measurement area 2 Scale body part 3. Weight measurement object 4. Load cell for platform scales 5 Hopper type weighing machine weight measurement part 6 Hopper type weighing machine main body 7. Load cell for hopper type weighing machine 8 Hopper type weighing machine transport conveyor 10 scales 20 Hopper type device

Claims

[Claim 1] The weight measurement targets are agricultural products, which vary in size, length, and shape even within the same type of product. When measuring weight using a weight measuring device with a load cell at one end of the device, such as a hopper type, After performing span adjustment in advance using an article of the same type as the article to be weight measured, By continuously measuring the weight of the object to be weighed of the type without delay, A span adjustment method that reduces eccentricity errors and enables the most accurate weight measurement possible.

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