Measuring device

Abstract

Provided is a measuring apparatus such that it is possible to realize the occurrence of an abnormality. A measuring apparatus (10) comprises a rectangular measuring platform (12), measuring sensors (42) disposed at four corners of the measuring platform (12), a control unit (38) that calculates a measurement value of a measured object on the measurement platform (12) on the basis of the outputs of the measuring sensors (42), and an abnormality detection means (39) that detects the occurrence of an abnormality on the basis of the output values of the measuring sensors. The occurrence of the abnormality is detected by comparing the sum of the output values of, among the measurement sensors (42), a pair of the measurement sensors (42) that are disposed on one side of the measuring platform (12), with a sum of past output values of said pair of measuring sensors (42).

Description

[Technical Field]

[0001] The present invention relates to a weighing device such as a weight scale, and more particularly to a large-sized weight scale used in medical facilities. [Background technology]

[0002] Large scales used in medical facilities have a large scale platform with weighing sensors attached to the four corners of the underside. The four weighing sensors convert the total weight into a single measurement value and display it (see Patent Document 1).

[0003] Even with these large scales, consideration has recently been given to making it easier for elderly people to get on and off the platform, with the platform being placed as low as possible. As a result, the gap between the platform and the floor has become smaller, causing the platform to easily come into contact with uneven surfaces. Another problem has arisen: pens and other foreign objects can get into the gap and come into contact with the underside of the platform.

[0004] Similar problems can occur with small scales for home use. However, with small scales, the weighing platform is light, so if the platform comes into contact with the floor or a foreign object, the percentage of error caused by this becomes larger, making it easier to notice abnormalities. Also, with small scales, the weighing platform is small and light, so if an abnormality is noticed, it is possible to lift the entire platform and check it, and the cause of the abnormality can be discovered. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2015-206681 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of large scales used in medical facilities, the weighing platform itself is heavy, so the percentage of error when the weighing platform comes into contact with the floor or a foreign object is small, making it difficult to notice an abnormality. Furthermore, it is difficult to lift and check the large and heavy weighing platform of a large scale, making it difficult to discover the cause of the abnormality. For this reason, with conventional large scales, even if a contact abnormality occurs due to the weighing platform coming into contact with the floor or a foreign object, and an inaccurate value is displayed, there is a risk that the displayed value will be used without being noticed.

[0007] This problem is particularly likely to occur immediately after a large scale is moved and set up: when the scale is moved to its intended location and the platform is set up on the floor, a foreign object may become trapped under the platform or the platform may come into contact with a wall or other object, causing an abnormality.

[0008] The present invention has been made in view of the above circumstances, and has as its object to provide a weighing device that can detect abnormalities that occur when the weighing device is moved and installed. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the invention described in claim 1 provides a weighing device comprising a rectangular weighing platform on which an object to be weighed is placed, weighing sensors arranged at the four corners of the weighing platform, and a control unit that calculates the weighing value of the object to be weighed on the weighing platform based on the output values ​​of the weighing sensors, characterized in that the weighing device is equipped with an abnormality detection means that detects the occurrence of an abnormality based on the sum of the output values ​​of a pair of weighing sensors arranged on one side of the weighing platform.

[0010] The inventors of the present invention noticed that when an abnormality occurs, such as when a foreign object or the like comes into contact with the weighbridge, the sum of the output values ​​of a pair of weigh sensors arranged on one side of the weighbridge changes significantly. Specifically, when weigh sensors are arranged at the four corners of the weighbridge and an output is generated from each sensor, the sum of the overall output value may fluctuate only slightly even when an abnormality occurs, making it difficult to use for detecting abnormalities. On the other hand, the individual output values ​​often fluctuate even when no abnormality occurs, making this also difficult to use for detecting abnormalities. In contrast, the inventors discovered that the sum of the output values ​​of a pair of weigh sensors arranged on one side of the weighbridge often fluctuates significantly when an abnormality occurs, such as when a foreign object comes into contact with the weighbridge, and can be used for detecting abnormalities. The present invention is based on this finding, and by monitoring the sum of the output values ​​of a pair of weigh sensors arranged on one side of the weighbridge, it is possible to detect the occurrence of an abnormality.

[0011] The invention of claim 2 is the invention of claim 1, wherein the abnormality detection means detects the abnormality by comparing the sum of the output values ​​of the pair of weighing sensors with the sum of past output values ​​of the pair of weighing sensors. For example, the occurrence of an abnormality can be detected by storing the sum of past output values ​​when the weighing sensors were normal in the past and comparing it with that.

[0012] The invention of claim 3 is characterized in that, in claim 2, the past output value is an output value when the weighbridge is unloaded, and the abnormality detection / cutoff means compares the sum of the output values ​​at the time of power-on with the past output value. According to this invention, it is possible to detect abnormalities at the time of power-on, and in particular to detect abnormalities related to installation.

[0013] The invention of claim 4 is characterized in that in any one of claims 1 to 3, the abnormality diagnosis means identifies and notifies the pair of weighing sensors that have determined that the abnormality has occurred. According to the present invention, the pair of weighing sensors that have detected the occurrence of an abnormality are identified and notified, so that the location where the abnormality has occurred can also be identified.

[0014] The invention of claim 5 is characterized in that, in any one of claims 1 to 4, the weighing device is movable, and the abnormality detection means detects installation abnormalities when the weighing device is moved and set up. The present invention is effective in a movable weighing device such as a weighing scale, and can detect abnormalities immediately after setting up. Note that the present invention is particularly effective in a large weighing scale equipped with wheels to make the weighing device easily movable. [Effects of the Invention]

[0015] According to the present invention, abnormalities are detected based on the sum of a pair of weighing sensors arranged on one side of the weighing platform, so that even in large weighing devices with large or heavy weighing platforms, the occurrence of an abnormality can be detected and the operator can respond immediately. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view of a weighing device to which the present invention is applied; [Figure 2] FIG. 2 is a front view of the weighing device of FIG. [Figure 3] Control block diagram of the weighing device in Figure 1 [Figure 4] Diagram showing abnormality diagnosis flow [Figure 5] Flow diagram with different abnormality diagnosis from Fig. 4 [Figure 6] 5 is a schematic diagram illustrating an example of abnormality diagnosis. DETAILED DESCRIPTION OF THE INVENTION

[0017] A preferred embodiment of a weighing device according to the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of the weighing device 10, and Fig. 2 is a front view of the weighing device 10. Fig. 3 shows a control block diagram of the weighing device 10.

[0018] The weighing device 10 shown in these figures is primarily composed of a weighing platform 12, handrails 14, and a display 16. The weighing platform 12 is formed in a large rectangular shape, and the person to be measured can stand on this weighing platform 12 either directly or in a wheelchair. The weighing platform 12 has a flat and sufficiently rigid structure, and is constructed, for example, by sandwiching a honeycomb-shaped reinforcing plate (not shown) between an iron frame and iron plates from above and below. Slopes 18, 18 are provided at the front and rear ends of the weighing platform 12, and they become lower toward the outside, making it easier for the person to get on and off. Each slope 18 is equipped with anti-slip pads 20 to prevent the person to be measured from slipping when getting on and off.

[0019] Side bars 22, 24 are connected to both the left and right ends of the weighbridge 12. Each side bar 22, 24 is formed in a hollow column shape, and houses wiring, electronic boards, etc. Also, handrails 14 are attached to the top surface of each side bar 22, 24, so that the person being measured can hold on to the handrails 14 to ascend and descend.

[0020] Of the side bars 22, 24, a handle 26 is attached to the outer surface of one of the side bars 22, and two wheels 28 (see Figure 2) are attached to the outer surface of the other side bar 24 so that they can rotate freely at a certain width. Therefore, by tilting the weighing platform 12 so that the side bar 22 is on the upper side and the side bar 24 is on the lower side, and then moving the weighing platform 12 by holding the handle 26 with the wheels 28 in the ground, the weighing device 10 can be moved freely.

[0021] Additionally, a pole 30 is detachably and rotatably attached to the top surface of the side bar 22, near the handrail 14. The pole 30 stands vertically, then curves to become horizontal, and a display 16 is attached to its tip. Therefore, the position of the display 16 can be adjusted by rotating the pole 30. The display 16 is provided with a display screen 34 (see FIG. 3) for displaying measurement values ​​and setting conditions, and operation buttons 36 for performing various settings, etc. Inside the display 16, a control unit (board, etc.) 38 for performing various calculation processes and a power source (battery, etc.) 40 are provided.

[0022] As shown in FIG. 2, legs 32 are provided on the underside of each side bar 22, 24. The legs 32 are located at both ends of each side bar 22, 24, i.e., at each corner of the weighbridge 12. A weighing sensor 42 (see FIG. 3) is provided between each leg 32 and the side bar 22, 24, and the weighbridge 12 is supported via this weighing sensor 42. The weighing sensor 42 is a sensor that measures the load acting on the weighbridge 12, and is, for example, a load cell. In this embodiment, as shown in FIG. 3, the weighing sensors 42 each output separately, which are amplified by an amplifier 44 and sent to the control unit 38 in the display 16. Therefore, the control unit 38 can compare the outputs of the weighing sensors 42 and perform the abnormality diagnosis described below. In other words, the weighing sensors 42 are configured to output signals in a comparable manner so that the control unit 38 (more specifically, the abnormality detection means 39 included in the control unit 38) can perform abnormality diagnosis. The specific configuration of the weighing sensor 42 (not shown) is that four gauges are attached to four thin sections of the strain body of a Roberval load cell, and these four gauges are connected to form a bridge circuit, so that the control unit 38 can determine the output values ​​of each (= data that has not been converted into a weighing value or processed by calculation, etc.).

[0023] The control unit 38 is a microcomputer with at least a CPU and memory implemented in an integrated circuit. Based on the outputs from the four weighing sensors 42, it calculates the weight values ​​of the objects to be weighed on the weighing platform 12 and controls the display 16 to display the calculated values ​​on the screen 34. The abnormality detection means 39 is implemented as software in the control unit 38. The output values ​​of the weighing sensors 42 and data stored in memory are also provided to the control unit 38. The abnormality detection means 39 performs calculations based on these data and detects the occurrence of an abnormality from the calculation results. The abnormality detection means 39 calculates the sums of all pairs of weighing sensors 42 located on one side of the weighing platform 12 (i.e., all four combinations of sums) and uses them to detect the occurrence of an abnormality. Furthermore, the control unit 38 is capable of storing reference values ​​for each sum in memory, and the abnormality detection means 39 detects an abnormality by comparing the calculated sums with the reference values.

[0024] Fig. 4 shows an example of a control flow for performing abnormality diagnosis. As shown in the figure, when the power is turned on (step S1), first, a determination is made as to whether the initial load value is abnormal (step S2). In this determination, it is determined whether a load exceeding, for example, ±10% of the weighing value is applied, and if so, it is determined that the initial load value is abnormal. If it is determined that the initial load value is abnormal, a message indicating that the initial load value is abnormal is displayed on the display screen 34 (step S6). This function for determining whether the initial load value is abnormal is also provided in conventional weighing devices, and a detailed description thereof will be omitted.

[0025] Next, an installation abnormality is determined (Step S3). In this determination, the sum of the output values ​​of the four weighing sensors 42 arranged on one side of the weighing platform 12 is calculated. Specifically, the sum of the output values ​​of the two weighing sensors 42 arranged on the entrance side of the weighing platform 12 (the side where the person to be measured gets on) is calculated, the sum of the output values ​​of the two weighing sensors 42 arranged on the exit side, the sum of the output values ​​of the two weighing sensors 42 arranged on the right side (as viewed from the entrance), and the sum of the output values ​​of the two weighing sensors 42 arranged on the left side is calculated. Then, it is determined whether each of the calculated sums (hereinafter referred to as "calculated values") falls within an allowable range with respect to a reference value. Here, the reference value is the sum of the output values ​​of a pair of weighing sensors 42 previously calculated under normal conditions, and is stored in advance. The allowable range is a value determined in advance for each type of weighing device 10 through testing or the like, and is set to, for example, an output value equivalent to approximately 0.1% of the weighing value. When comparing, the reference value and the calculated value are compared for the same combination of weighing sensors 42. If the comparison result shows that any of the sums exceeds the allowable range, it is determined that an installation abnormality has occurred. If so, a message indicating an installation abnormality is displayed on the display screen 34 (step S7).

[0026] On the other hand, if it is determined that there is no installation abnormality, the weighing process is carried out (step S4). The weighing process is automatically started when the person to be weighed steps onto the weighing platform 12. At that time, it is preferable to display a message on the display screen 34 prompting the person to start weighing (i.e., a message prompting the person to step onto the weighing platform 12). When weighing starts, the control unit 38 calculates one weighing value from the output values ​​of the four weighing sensors 42 and displays the calculated weighing value on the display screen 34 (step S5).

[0027] Next, the operation of the weighing device 10 configured as above will be described.

[0028] In the weighing device 10 of this embodiment, a bridge circuit using gauges is configured within each weighing sensor 42, and an output value is obtained from each weighing sensor 42. Conventionally, such output values ​​are meaningless as they are, so they are immediately converted into a single measurement value. However, there is a problem in that the converted measurement value makes it difficult to detect the occurrence of an abnormality when a foreign object or the like comes into contact with the weighing platform 12. In particular, when the weighing platform 12 is heavy, such as in a large scale, the amount of change in the measurement value is small even if a foreign object or the like comes into contact with the weighing platform 12, making it difficult to detect an abnormality.

[0029] Therefore, the inventors of the present invention investigated the output values ​​of each weighing sensor 42 and found that the output values ​​react very sensitively, and that they will show an entirely different value if the weighing platform 12 is rearranged or if a temporary load or impact is applied to the weighing platform 12. For example, if the output value of a certain weighing sensor 42 is "+100 (raw data before conversion to a weighing value)," and the output value of the weighing sensor 42 is examined again after the weighing platform 12 is rearranged, it may change to "-100" or "+200" (even though no load remains). Therefore, since the output value of the weighing sensor 42 changes regardless of whether an abnormality has occurred, it is difficult to detect the occurrence of an abnormality by simply monitoring this output value.

[0030] The inventors of the present invention further investigated the output values ​​of the weighing sensors 42 and found that, under normal conditions (i.e., when no abnormalities are occurring), the output values ​​fluctuate according to a certain rule. Specifically, under normal conditions, the sum of the output values ​​of a pair of adjacent weighing sensors 42 fluctuates to fall within a predetermined range relative to a reference value (the sum of past output values ​​under normal conditions). For example, if the past output values ​​of a pair of weighing sensors 42 were "+100" and "+200," respectively, and their sum was "+300," under normal conditions, the two output values ​​will change to fall within a predetermined range relative to "+300." Therefore, under normal conditions, when the output value of one weighing sensor 42 changes from "+100" to "-100," the output value of the other weighing sensor 42 will change around "+400" so that their sum becomes "+300." Conversely, if an abnormality occurs, the sum will change significantly. For example, if the output value of one weighing sensor 42 becomes "-100," the output value of the other weighing sensor 42 will change to "-100" or "1000," resulting in a significant change in the sum from the previous value of "+300." In this way, the sum of the output values ​​of a pair of weighing sensors 42 will change little if the sensor is normal, but will change more if an abnormality occurs. Therefore, in this embodiment, the sum of the output values ​​of a pair of weighing sensors 42 is compared with the sum of past output values ​​of the same pair of weighing sensors 42, and if the difference exceeds a threshold, it is determined that an abnormality has occurred.

[0031] As mentioned above, the output value of the weighing sensor 42 shows a sensitive response, so by using the sum of the output values ​​for abnormality diagnosis, it is possible to detect the occurrence of an abnormality with a high probability. Therefore, even if the weighing platform 12 is heavy or large, as in a medical weighing scale, it is possible to detect the occurrence of an abnormality, and it is possible to prevent weighing without noticing the abnormality.

[0032] In the above-described embodiment, installation abnormalities are automatically diagnosed, but this is not limited to this. It is also possible to allow the user to select whether or not to diagnose installation abnormalities, and to perform the diagnosis only when selected.

[0033] Furthermore, in the above-described embodiment, when an abnormality occurs, it is displayed on the display screen 34, but the means for notifying the abnormality is not limited to this, and the operator may be notified of the occurrence of an abnormality by emitting a sound or by turning on or flashing a light.

[0034] Furthermore, in the above-described embodiment, a value determined in advance by testing or the like, or a past output value in a no-load state, for example, is set and used as the reference value, but this is not limited to this. When it is determined that the condition is normal (i.e., a state in which no abnormality has occurred), the sum of the output values ​​may be newly stored, and this newly stored value may be used as an updated reference value.

[0035] In the above-described embodiment, the content of the abnormality that has occurred may be determined. Specifically, a database showing the correspondence between the sum of the output values ​​of the weighing sensor 42 (or the difference between the calculated value and the reference value) when an abnormality occurs and the content of the abnormality may be stored in advance in the memory of the control unit 38, and the abnormality detection means 39 may diagnose the content of the abnormality based on the sum of the output values ​​and the database, and may be controlled to display the result on the display screen 34.

[0036] In the above-described embodiment, the occurrence of an abnormality is detected by the sum of the output values ​​of the pair of weighing sensors 42. However, the occurrence of an abnormality may also be detected by the output value of each weighing sensor 42. For example, past (normal) output values ​​of each weighing sensor 42 may be stored in the memory of the control unit 38, and the abnormality detection means 39 may compare the past output value with the output value currently being measured and determine that an abnormality has occurred if the difference exceeds an allowable range. In this case, abnormality detection can be more reliably performed by also diagnosing using the sum of the output values ​​of the pair of weighing sensors 42.

[0037] Furthermore, in the above-described embodiment, the abnormality detection means 39 may perform other abnormality detection using the output values ​​of each weighing sensor 42. For example, the control flow in Figure 5 shows an example of detecting an abnormality during weighing (hereinafter referred to as a weighing abnormality). Compared to the control flow in Figure 4, the control flow in Figure 5 has steps S8 and S9 added. The other steps are the same, so a description thereof will be omitted.

[0038] During weighing in step S4 of Fig. 5, the output values ​​of each weighing sensor 42 are stored in memory, and a weighing abnormality is determined based on the fluctuation and convergence of the stored output values ​​(step S8). If it is determined that a weighing abnormality has occurred, a display indicating the weighing abnormality is displayed (step S9). FIG. 6 is an explanatory diagram illustrating the weighing abnormality, and FIGS. 6(a) to 6(d) each show an example of a weighing abnormality. In FIG. 6, the dotted line shows the fluctuation in the output value of the weighing sensor where the abnormality occurred, and the solid lines show the fluctuation in the output values ​​of the other three (normal) weighing sensors. Note that the output values ​​of the other three weighing sensors do not completely match, but are shown as representative examples that show roughly the same trend. Also, T1 in FIG. 6 is the time when the person to be measured steps onto the weighing platform 12, and T2 is the approximate time when the weighing value stabilizes.

[0039] In the example of Figure 6(a), the output value (dotted line) of one weigh sensor 42 shows unstable fluctuations compared to the output values ​​(solid lines) of the other weigh sensors 42, and it is determined that an abnormality has occurred. In the example of Figure 6(b), the output (dotted line) of only one weigh sensor 42 converges faster than the outputs (solid lines) of the other weigh sensors 42, and it is determined that the weigh platform 12 has come into contact with the floor or a foreign object around the weigh sensor 42. In the example of Figure 6(c), the output (dotted line) of only one weigh sensor 42 converges slower than the outputs (solid lines) of the other weigh sensors 42, and it is determined that an abnormality has occurred, such as interference caused by contact with the floor or a foreign object, or an abnormality that makes the weigh sensor 42 unstable. In the example of Figure 6(d), the convergence value of the output (dotted line) of one weighing sensor 42 is much smaller than the convergence values ​​of the outputs (solid lines) of the other weighing sensors 42, and it is determined that the weighing sensor 42 has failed or is not properly attached, or that an abnormality has occurred in the vicinity of the weighing sensor 42 due to contact with a foreign object. In this way, by comparing the output value of each weighing sensor 42 with the output values ​​of the other weighing sensors 42, it is possible to detect abnormalities even during weighing processing. Furthermore, by performing the above comparison, it is possible to identify and report the weighing sensor in which an abnormality has occurred.

[0040] In the above-described embodiment, the weighing device 10 has been described as a large medical scale, but this is not limited to this, and the weighing device can be applied to various weighing devices such as small household scales, scales with body fat meters, scales with height meters, as well as platform scales and balances. [Explanation of symbols]

[0041] 10...weighing device, 12...weighing platform, 14...handrail, 16...display, 18...slope, 20...anti-slip, 22...side bar, 24...side bar, 26...handle, 28...wheel, 30...pole, 32...leg, 34...display screen, 36...operation button, 38...control unit, 39...abnormality detection means, 40...power supply, 42...weighing sensor, 44...amplifier

Claims

1. A weighing device comprising: a rectangular weighing platform on which an object to be weighed is placed; weighing sensors disposed at the four corners of the weighing platform; and a control unit that calculates a weighing value of the object to be weighed on the weighing platform based on output values ​​of the weighing sensors, an abnormality detection means for detecting the occurrence of an abnormality based on the sum of output values ​​of a pair of the weighing sensors arranged on one side of the weighing platform; The weighing device is movable, and the abnormality detection means detects an installation abnormality when the weighing device is moved and installed.

2. 2. The weighing device according to claim 1, wherein the abnormality detection means detects the abnormality by comparing the sum of the output values ​​of the pair of weighing sensors with the sum of past output values ​​of the pair of weighing sensors.

3. The weighing device according to claim 2, characterized in that the past output value is a past output value when the weighing platform is in an unloaded state, and the abnormality detection means compares the sum of the output values ​​of the weighing sensor when power is turned on with the past output value.

4. 4. The weighing device according to claim 1, wherein the abnormality detection means identifies a pair of weighing sensors in which it is determined that the abnormality has occurred and notifies the identified pair of weighing sensors.

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