JP2008298439A - Weight measuring device - Google Patents

Abstract

An object of the present invention is to achieve a further reduction in thickness while maintaining measurement accuracy, and even when the object to be measured is deviated, there is less error than when a load is applied to the center of the strain generating body. Provided is a weight measuring device capable of obtaining a stable measurement result.
A load cell in which a fixed end portion of a strain generating body is cantilevered, and a mounting portion that is supported by a movable end portion of the strain generating body and is disposed to face the strain generating body. A weight measuring device in which a strain generating body deforms in response to a load of a measurement object placed on a mounting portion, wherein the strain generating body includes a pair of strain sensors in a direction connecting a fixed end and a movable end. And a pair of strain generating portions at positions corresponding to the pair of strain sensors, and the mounting portion has both end portions in the direction connecting the fixed end portion and the movable end portion from each of the pair of strain generating portions. , The distance between the pair of strain generating portions is within a range having both ends at the outer positions by ½.
[Selection] Figure 1

Description

  The present invention relates to a weight measuring device, and more particularly, to a weight measuring device including a thin load cell that can accurately measure the weight of a light-weight measuring object.

  In recent years, for example, a weight measuring apparatus that measures the weight of a relatively light measurement object of less than 1 kilogram, for example, is required to be further downsized while maintaining high measurement accuracy. Along with this, the load cell used in the weight measuring device is also expected to be thin.

  On the other hand, as a load cell used in a weight measuring device for detecting the weight of an object to be measured, there is a configuration in which a strain sensor is arranged on an upper surface of a long plate-like strain generating body. In this load cell, a strain generating portion is provided at a position corresponding to the strain sensor by a through-hole formed in the strain generating body along the width direction or the longitudinal direction. When placed on the mounting portion supported by the strain generating body, the strain generating section of the strain generating body is deformed according to the load, and the strain sensor expands and contracts. The strain sensor forms part of the Wheatstone bridge, and the weight of the measurement object can be calculated from the electrical resistance value of the strain sensor determined by the amount of expansion and contraction of the strain-generating portion corresponding to the load.

JP 2000-214008 A

  However, the above-described conventional load cell has already been reduced in thickness, and the thickness of the strain generating body can be reduced to meet the demand for further reduction in thickness, but with high accuracy that can maintain high measurement accuracy. Providing a through hole has become difficult.

  Further, in the conventional load cell, the through hole is often provided at the approximate center of the strain generating body in plan view, and when the load due to the measurement object is applied to the center of the mounting portion, the load is applied to the peripheral portion side of the mounting portion. There is a possibility that the measurement result will be different in the case where the load is applied (deviation state). Regarding this, it is necessary to satisfy the standard of the deviation error defined in the specific measuring instrument certification inspection rule, but there is a possibility that the standard will not be satisfied if the conventional load cell is made thin.

  Therefore, an object of the present invention is to realize a load cell capable of realizing further reduction in thickness while maintaining high measurement accuracy, and to provide a weight measuring device using such a load cell. Furthermore, an object of the present invention is to provide a weight measuring device capable of obtaining an accurate measurement result in the same manner as when a load is applied to the center of the mounting portion even when the measurement object is displaced. It is in.

  In order to solve the above-mentioned problems, the weight measuring device of the present invention includes a load cell in which a fixed end of a strain generating body is cantilevered, a load end supported by the movable end of the strain generating body, and the strain generating body. A weight measuring device in which the strain body deforms in response to a load of a measurement object placed on the placement portion. A pair of strain sensors in a direction connecting the fixed end portion and the movable end portion, and a pair of strain generating portions at positions corresponding to the pair of strain sensors. Both end portions in the direction connecting the fixed end portion and the movable end portion are within a range in which both ends are located at positions outside of each of the pair of strain generating portions by ½ of the distance between the pair of strain generating portions. It is characterized by being.

  In the weight measuring device of the present invention, the mounting portion may be configured such that both end portions in the direction connecting the fixed end portion and the movable end portion respectively correspond to the pair of strain generating portions, or the pair of pair It exists in the position corresponding to between strain generating parts.

  In the weight measuring device according to the present invention, the placing portion is cantilevered by the movable end portion of the strain generating body via a support frame.

  In the weight measuring device of the present invention, the strain body has a substantially rectangular plate shape, and includes the fixed end portion at one end portion in the longitudinal direction and the movable end portion at the other end portion. And

  In the weight measuring device of the present invention, the strain-generating portion is provided as at least one recess at a position corresponding to the pair of strain sensors.

  In the weight measuring device of the present invention, the strain-generating portion is provided as a concave line along a direction orthogonal to a direction connecting the fixed end portion and the movable end portion.

  In the weight measuring device of the present invention, the strain sensor is provided on the first surface of the strain generating body, and the strain generating portion is provided on a second surface different from the first surface of the strain generating body. It is characterized by.

  In the weight measuring apparatus of the present invention, the first surface is an upper surface and the second surface is a lower surface.

  According to the present invention, both end portions of the mounting portion in the direction connecting the fixed end portion and the movable end portion are positioned outside each of the pair of strain generating portions by a distance that is ½ of the distance between the pair of strain generating portions. When the measurement object is displaced, an accurate measurement result with little error can be obtained even when a load is applied to the center of the strain generating body. Further, the strain generating body has a substantially rectangular plate shape, and one end portion in the longitudinal direction is a fixed end portion and the other end portion is a movable end portion, and the strain generating portion is provided as a recess at a position corresponding to the strain sensor. By adopting the configuration, it becomes easy to process the strain generating body, so that further thinning can be realized while maintaining measurement accuracy.

  Hereinafter, the weight measuring device 100 according to the first embodiment of the present invention will be described in detail with reference to the drawings. Here, FIG. 1 is a plan view showing the configuration of the weight measuring device 100 according to the first embodiment, and FIG. 2 is a partial cross section showing the internal configuration of the weight measuring device 100 except for the side wall of the weight measuring device 100. 3 and 3 are plan views showing the configuration of the load cell 10 according to the first embodiment.

  As shown in FIGS. 1 and 2, the weight measuring device 100 according to the first embodiment includes a load cell 10, a mounting table 40 as a mounting unit, a support frame 50, and a base 60. As shown in FIGS. 1 to 3, the load cell 10 includes a strain generating body 20 and a strain sensor 30. When the user presses the switch 74, the weight measuring device 100 adjusts the zero point at the start, and when a measurement object is placed on the platform 40, the weight is measured and the measurement result is displayed on the display unit 72. . The weight measuring device 100 according to the first embodiment is suitable for measuring a relatively light object such as 1 kg or less as a measurement object, but the weight measuring device according to the present invention is not limited thereto. There is no limit. In FIG. 1, detailed configurations of the strain generating body 20 and the strain sensor 30 are omitted. Below, the detailed structure of each member is demonstrated.

  The strain body 20 is a rectangular plate member formed by molding a metal (for example, steel or aluminum alloy) into a substantially rectangular parallelepiped shape, and has an upper surface 23 (first surface) as shown in FIGS. A strain sensor 30 is attached. Both ends of the strain generating body 20 in the longitudinal direction (left-right direction in FIGS. 1 to 3) are a fixed end 25 and a movable end 26, and are fixed for fixing the strain generating body 20 to the base 60. Two end-side hole portions 25a and two movable end-side hole portions 26a for fixing the mounting table 40 as the mounting portion to the strain body 20 are formed so as to penetrate each. Further, on the lower surface 24 (second surface) of the strain generating body 20, strain generating portions 21 and 22 are formed at positions corresponding to the pair of strain sensors 30. The strain body 20 may have a shape other than a rectangular parallelepiped shape (for example, an oblong plate shape or an elliptical plate shape), and is not particularly limited. Further, the strain sensor 30 and the strain generating portions 21 and 22 may be disposed only on one surface of the upper surface 23 or the lower surface 24 of the strain generating body 20.

  The strain sensor 30 includes a fixed end side sensor pair 31 composed of fixed end side sensors (strain sensors) 31a and 31b, and a movable end side sensor pair 32 composed of movable end side sensors (distortion sensors) 32a and 32b. And two sensor pairs. These sensors have the same known shape and characteristics, and the fixed end side sensor pair 31 and the fixed end side sensor pair 32 are arranged so as to be symmetric with respect to the longitudinal center of the strain body 20. The Further, the fixed end side sensors 31a and 31b and the movable end side sensors 32a and 32b are respectively arranged so as to extend along the longitudinal direction of the strain body 20 (the left-right direction in FIGS. 1 to 3).

  The fixed end side sensors 31a and 31b constituting the fixed end side sensor pair 31 have a terminal portion for connecting to the external device along the longitudinal direction of the strain generating body 20 and the longitudinal direction of the strain generating body 20. They are arranged in parallel to each other in the width direction (vertical direction in FIGS. 1 and 3) of the strain generating body 20 so as to be arranged at the center in the direction. On the other hand, the movable end side sensors 32a and 32b constituting the movable end side sensor pair 32 are also connected to an external circuit (circuit on the electronic substrate 70) along the longitudinal direction of the strain generating body 20. Are arranged in parallel to each other so that the terminal portions are arranged on the center side in the longitudinal direction of the strain body 20.

  The fixed end side sensors 31a and 31b and the movable end side sensors 32a and 32b constitute a Wheatstone bridge together with an external circuit (circuit on the electronic board 70). These sensors expand and contract according to the load applied to the strain body 20 by placing the measurement object on the weight measuring device. Since the electrical resistance value of the compressed sensor decreases and the electrical resistance value of the expanded sensor increases, the weight of the placed measurement object can be calculated by a calculation program stored in advance in an external circuit. it can. The calculation result is displayed on the display unit 72 (for example, a liquid crystal display unit).

  As shown in FIG. 2, the base 60 is fixed on the bottom wall 101 of the weight measuring device 100, and is fixed to the fixed end side hole 25 a of the strain body 20 via the connecting member 65. Has been. Fixing with the strain body 20 is performed by fastening the fixed end side hole 25a, the connecting member 65, and the base 60 with screws (not shown). When the connecting member 65 and the base 60 are integrally formed, the strain-generating body 20 and the base 60 are fixed to each other by fastening the fixed end side hole 25a and the connecting member 65 with screws. . Thereby, the strain body 20 is cantilevered by the base 60 at the fixed end 25. The strain body 20 and the base 60 may be fixed using a connecting pin (for example, a rivet) instead of a screw.

  The mounting table 40 as the mounting unit can be selected in shape and material according to the specifications of the weight measuring device 100 (for example, a measurable weight range). For example, a plastic material is formed into a rectangular shape in plan view. Things can be used. As shown in FIG. 2, for example, the mounting table 40 is disposed concentrically on a columnar support portion 51 extending upward from the center of the support frame 50, and the center 40 c of the mounting table 40 and the center 50 c of the support frame 50 are arranged. The platform 40 and the support frame 50 may be fixed by fastening the platform 40, the columnar support 51, and the support frame 50 with screws (not shown) while matching. The support frame 50 is fixed to the movable end side hole 26a of the strain body 20 via the connecting member 45. Specifically, the center 20c of the strain body 20 and the center 50c of the support frame 50 are mutually connected. So that the movable end side hole 26a, the connecting member 45, and the support frame 50 are fastened with screws. With this configuration, in the state where the centers (centers of gravity) 40 c, 20 c, 50 c of the mounting table 40, the strain generating body 20, and the support frame 50 coincide with each other, the mounting table 40 is interposed between the strain generating body 20 via the support frame 50. The movable end portion 26 is cantilevered by the movable end portion 26 and disposed opposite to the strain body 20 via the support frame 50. The platform 40 can be directly supported by the movable end portion 26 of the strain body 20 without the support frame 50 interposed therebetween. In addition, a fixing pin (rivet) may be used in place of the screw for fixing the mounting table 40 and the support frame 50 and fixing the strain body 20 and the support frame 50. Note that the present invention can be practiced without a configuration in which the platform 40 and the columnar support 51 are fixed concentrically.

  The strain generating portions 21 and 22 are formed on the lower surface 24 of the strain generating body 20 at positions corresponding to the fixed end side sensor pairs 31 and 32, respectively. That is, it arrange | positions so that it may become symmetrical about the center (center 20c) of the longitudinal direction of the strain body 20. FIG. The strain generating portions 21 and 22 are preferably formed together with the strain generating body 20, but may be separately formed by pressing or cutting after the strain generating body 20 is formed.

  Further, as an example, the strain generating portions 21 and 22 extend along the width direction of the strain generating body 20 (a direction perpendicular to the direction connecting the fixed end portion 25 and the movable end portion 26) and are parallel to each other. The groove is formed in a groove shape (concave line) so that the cross section perpendicular to the width direction of the strain generating body 20 has a semicircular shape. The fixed end side sensors 31a and 31b extending in the longitudinal direction of the strain generating body 20 are pasted on the strain generating section 22, and the movable end side sensors 32a and 32b are pasted on the strain generating section 21, respectively. Is provided. In the first embodiment, the groove-shaped (concave) strain-generating portions 21 and 22 are provided as the strain-generating portion, but the shape of the strain-generating portion is a concave shape other than the groove-shaped (concave) (for example, , Hemispherical) or through-holes, and is not particularly limited.

  In the first embodiment, the strain generating portions 21 and 22 are centered corresponding to the position at a distance of 1/4 from the end portions 41 and 42 in the longitudinal direction of the mounting table 40 in plan view (see FIG. 1). 21c and 22c are provided. That is, as shown in FIG. 1, when the length of the mounting base 40 is P, the center 21c of the strain-generating part 21 is at a position of 1 / 4P from the end 41 on the connecting member 45 side of the mounting base 40. The center 22c of the strain generating portion 22 is disposed at a position of 1 / 4P from the other end portion 42 of the mounting table 40. In other words, as shown in FIG. 2, when the interval between the strain-generating portions 21 and 22 (in this embodiment, the interval between the center 21c of the strain-generating portion 21 and the center 22c of the strain-generating portion 22) is L2, Since this interval L2 is equal to 1 / 2P, both end portions 41, 42 of the mounting base 40 are outside by 1/2 of the interval L2 between the strain-generating portions 21, 22 from the strain-generating portions 21, 22 respectively. It is supposed to be in the position.

  In the present embodiment, a description will be given of a configuration in which both end portions 41 and 42 of the mounting table 40 are arranged at positions outside the respective strain generating portions 21 and 22 by 1/2 of the interval L2 between the strain generating portions 21 and 22. However, from the viewpoint of obtaining the same accurate measurement result as when a load is applied to the center of the mounting table 40 even when the measurement object is displaced, at least the fixed end 25 and the movable end 26. The end portions 41 and 42 of the platform 40 in the direction connecting the two are within a range in which both ends are located at positions outside the strain generating portions 21 and 22 by 1/2 of the interval L2 between the strain generating portions 21 and 22. I just need it. Therefore, the length P of the platform 40 only needs to be set to be not more than twice the interval L2 between the strain generating portions 21 and 22, and the deviation value of the measurement object becomes shorter as the length P is shorter than the interval L2. Thus, it is possible to provide a weight measuring apparatus that can reduce the influence of the above and thereby obtain an accurate measurement result. In the second embodiment to be described later, both end portions in the direction connecting the fixed end portion 25 and the movable end portion 26 are arranged on the inner side than in the case of the first embodiment.

  According to the standard of the deviation error defined in the specific measuring instrument certification inspection rule, the position where the measurement object is displaced to the outermost side with respect to the platform 40 is the length of the platform 40 from the end portions 41 and 42. It is a position inside by 1/4 of P, and an eccentric load is applied to this position. That is, the eccentric load loaded on the outermost side with respect to the mounting table 40 acts at a position corresponding to the strain-generating portions 21 and 22. The present embodiment is configured as described above, thereby providing a weight measuring apparatus that can further reduce the influence of the deviation value of the measurement object and thereby obtain an accurate measurement result. It becomes possible.

  In the first embodiment, the strain body 20 and the mounting table 40 have a rectangular shape in plan view, but any of them may have a shape other than the rectangular shape. Further, the fixed end portion 25 and the movable end portion 26 can also be provided at positions other than both end portions in the longitudinal direction of the strain body 20.

  In the weight measuring apparatus 100 having the above configuration, when a measurement object is placed on the mounting table 40, the load is distorted in the strain-generating portions 21 and 22 of the strain-generating body 20. Elastically deforms in a substantially S-shape when viewed from the side. The amount of deformation in the strain generating portions 21 and 22 is detected as an electric resistance value corresponding to the amount of expansion and contraction of the fixed end side sensors 31a and 31b and the movable end side sensors 32a and 32b, and the weight is measured based on this. Can do.

  Next, effects of the configuration of the weight measuring device 100 according to the first embodiment will be described with reference to FIGS. 4 to 8. Here, FIG. 4 is a graph showing the amount of deflection at each position of the strain body 20 when the center of gravity of the measurement object is disposed on the fixed end 25 side of the weight measuring device 100 according to the first embodiment. FIG. 5 is a graph showing the amount of deflection at each position of the strain-generating body 20 when the center of gravity of the measurement object is arranged at the center of the weight measuring device 100, and FIG. 6 is the movable end portion 26 of the weight measuring device 100. FIG. 7 is a graph showing the amount of deflection at each position of the strain generating body 20 when the center of gravity of the measurement object is arranged on the side, and FIG. 7 shows the non-linearity on the vertical axis and the load on the horizontal axis for the reference model. FIG. 8 is a graph with the non-linearity on the vertical axis and the load on the horizontal axis for the first embodiment model.

  4 to 6, by using a model in which the distance from the end portion 27 to the end portion 28 (distance from the fixed end portion 25 to the movable end portion 26) L1 (FIG. 2) is set to 50 mm, the finite element method is used. Analysis is performed (load (weight of the object to be measured) 0.2 kg). Here, the end portion 27 is an end portion on the connecting member 45 side in the connecting portion with the connecting member 65 in the strain body 20, and the end portion 28 is the connecting member 65 in the connecting portion with the connecting member 45. This is the end of the side. Further, as a reference model for comparing the effect with the load cell 20 according to the first embodiment, an interval from the center 21c of the strain-generating part 21 to the center 22c of the strain-generating part 22 in the longitudinal direction of the load cell 10 ( As a model of the load cell (weight measuring device) according to the first embodiment, a distance L2 of 40 mm (thickness of 0.2 mm) is used. 71 mm) is used. The thickness 0.5 mm when the distance L2 is 20 mm and the thickness 0.71 mm when the distance L2 is 40 mm are values determined so that the rated output as the load cell is the same.

  4 to 6 are graphs showing the amount of bending at each position of the strain generating body 20 when the measurement object is placed on the mounting table 40, and the horizontal axis is the end of the connecting member 65 on the side of the connecting member 45. The distance (unit mm) from the part 27 is shown, and the vertical axis shows the amount of deflection (unit mm). In FIG. 4, the center line 40a of the platform 40 (a straight line passing through the center 40c and extending in the width direction of the platform (vertical direction in FIG. 1)) from the connecting member 65 side (fixed end 25 side) is 15 mm away. In FIG. 5, the center of gravity of the measurement object is arranged on the center line 40 a of the mounting table 40, and in FIG. 6, the connecting member 45 side (movable end portion) from the center line 40 a of the mounting table 40 is arranged. 26 side), the center of gravity of the measurement object is arranged at a position of 15 mm. 4 to 6, curves R1, R2, and R3 show the analysis results of the reference model, and curves E1, E2, and E3 show the analysis results of the load cell model according to the first embodiment, respectively.

  4 to 6, when the reference model and the load cell model according to the first embodiment are compared, first, when the measurement object is placed on the center line 40a of the platform 40 (FIG. 5), the strain is generated. It can be seen that there is almost no difference in the amount of distortion at each position of the body 20 between the two models. On the other hand, when the measurement object is placed on the fixed end 25 side (FIG. 4) and when the measurement object is placed on the connection member 45 side (FIG. 6), the distance from the connection member 65 is small. The larger the amount, the larger the amount of bending of the reference model, whereas the amount of bending of the first embodiment model is suppressed.

  FIG. 7 shows a calculation result of nonlinearity based on actual measurement when the same reference model as in FIGS. 4 to 6 is used. A curved line RL1 represents a case where the center of gravity of the measurement object is arranged at a position of 15 mm from the center 40c of the mounting table 40 to the connecting member 65 side (fixed end portion 25 side), and the load is sequentially increased. A curve RL2 indicates a case where the center of gravity of the measurement object is arranged at the center 40c of the mounting table 40 and the load is sequentially increased. A curve RL3 is a case where the center of gravity of the measurement object is arranged at a position of 15 mm from the center 40c of the mounting base 40 to the connecting member 45 side (movable end portion 26 side), and the load is sequentially increased.

  On the other hand, FIG. 8 shows a calculation result of nonlinearity when the same first embodiment model as in FIGS. 4 to 6 is used. A curve EL1 represents a case where the center of gravity of the measurement object is arranged at a position of 15 mm from the center 40c of the mounting base 40 to the connecting member 65 side (fixed end portion 25 side), and the load is sequentially increased. A straight line EL2 indicates a case where the center of gravity of the measurement object is arranged at the center 40c of the mounting table 40 and the load is sequentially increased. A curved line EL3 shows a case where the center of gravity of the measurement object is arranged at a position of 15 mm from the center 40c of the mounting base 40 to the connecting member 45 side (movable end portion 26 side), and the load is sequentially increased.

  Here, the non-linearity when the first embodiment model is used and when the reference model is used will be examined. In both models, the non-linearity in the case where an offset load is applied is considered to be the case where it is offset to the connecting member 65 side (fixed end 25 side) (RL1, EL1), and the connecting member 45 side (movable end). In the case of being offset to the part 26 side (RL3, EL3), the output result is opposite, so both models have a shape with a bulge up and down with the maximum width at the time of 0.5kg load for both models. However, it can be seen that the shape of the bulge is clearly smaller in the first embodiment model. That is, according to the first embodiment model, even when it is displaced to the connecting member 65 side (fixed end portion 25 side), it is a case where it is displaced to the connecting member 45 side (movable end portion 26 side). However, it can be seen that, with any load amount, the non-linearity can be kept small and an accurate measurement result with less error due to the offset load can be obtained.

  Next, a second embodiment of the present invention will be described with reference to FIGS. 9 and 10. Here, FIG. 9 is a plan view showing the configuration of the weight measuring device 200 according to the second embodiment, and FIG. 10 is a partial cross-sectional view showing the internal configuration of the weight measuring device 200 excluding the side wall. In 2nd Embodiment, it replaces with the mounting base 40 of 1st Embodiment, and the length Q of one side is the same as the space | interval (space | interval of the strain generation parts 21 and 22) L2 between the strain generation parts 21 and 22 center. This is different from the first embodiment in that a platform 140 having a square shape in plan view is used. That is, in plan view (see FIG. 9), since both end portions 141 and 142 of the mounting base 140 are arranged at positions corresponding to the strain-generating portions 21 and 22, the fixed end portion 25 and the movable end portion 26 are connected to each other. Both end portions 141 and 142 of the placing portion 140 in the connecting direction are arranged inside the case of the first embodiment. Other configurations are the same as those of the first embodiment, and the same reference numerals are used for the same members.

  In the weight measuring device 200, as in the weight measuring device 100 of the first embodiment, the center 20c of the strain body 20, the center 50c of the support frame 50, and the center 140c of the mounting table 140 seem to be in a straight line. In addition, the strain body 20, the support frame 50, and the mounting table 140 are disposed to face each other.

  According to the standard of the deviation error defined in the specific measuring instrument certification inspection rule, the position where the measurement object is displaced to the outermost side with respect to the stage 140 is the length of the stage 140 from the end portions 141 and 142. It is a position inside by 1/4 of Q, and an eccentric load is applied to this position. In other words, the eccentric load applied to the outermost side with respect to the mounting table 140 acts in a region inside the strain-generating portions 21 and 22. Since the second embodiment is configured as described above, the length Q of the mounting table 140 in the second embodiment is set to the interval L2 rather than the length P of the mounting table 40 in the first embodiment. On the other hand, since the influence of the deviation value of the measurement object is further reduced and the non-linearity can be reduced, it is possible to provide a weight measuring apparatus that can obtain an accurate measurement result. It becomes.

It is a top view which shows the structure of the weight measuring apparatus which concerns on 1st Embodiment of this invention. It is a partial cross section figure which shows the internal structure of the weight measuring apparatus which concerns on 1st Embodiment of this invention except a side wall. It is a top view which shows the structure of the load cell which concerns on 1st Embodiment of this invention. It is the graph which showed the amount of bending in each position of a strain body, when the gravity center of a measuring object is arranged at the fixed end side of a weight measuring device concerning a 1st embodiment of the present invention. It is the graph which showed the amount of bending in each position of a strain body when the gravity center of a measuring object is arranged in the center of the weight measuring device concerning a 1st embodiment of the present invention. It is the graph which showed the amount of bending in each position of a strain body when the gravity center of the measuring object is arranged at the movable end side of the weight measuring device concerning a 1st embodiment of the present invention. It is a graph which took the non-linearity on the vertical axis and the load on the horizontal axis for the reference model. It is a graph which took the nonlinearity on the vertical axis and took the load on the horizontal axis for the first embodiment model. It is a top view which shows the structure of the weight measuring apparatus which concerns on 2nd Embodiment of this invention. It is a partial cross section figure which shows an internal structure except the side wall of the weight measuring apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Load cell 20 Strain body 21 Strain part 22 Strain part 23 Upper surface (1st surface)
24 Lower surface (second surface)
25 fixed end 26 movable end 30 strain sensor 31 fixed end side sensor pair 31a fixed end side sensor 31b fixed end side sensor 32 movable end side sensor pair 32a movable end side sensor 32b movable end side sensor 40 Platform (mounting section)
45 connecting member 50 support frame 60 base 65 connecting member 100 weight measuring device 140 mounting base (mounting portion)
200 Weight measuring device

Claims (8)

A load cell in which the fixed end of the strain generating body is cantilevered; and
A mounting portion that is supported by the movable end portion of the strain body and is disposed to face the strain body, and
A weight measuring device in which the strain body deforms in response to a load of a measurement object placed on the placing portion,
The strain body includes a pair of strain sensors in a direction connecting the fixed end and the movable end, and a pair of strain portions at a position corresponding to the pair of strain sensors.
In the mounting portion, both end portions in a direction connecting the fixed end portion and the movable end portion are positioned outside each of the pair of strain generation portions by ½ of the interval between the pair of strain generation portions. The weight measuring device is in a range with the two ends.   The mounting portion is configured such that both end portions in the direction connecting the fixed end portion and the movable end portion correspond to the pair of strain generating portions, or between the pair of strain generating portions. The weight measuring device according to claim 1, wherein   The weight measuring device according to claim 1, wherein the placement unit is cantilevered by a movable end of the strain generating body via a support frame.   The said strain generating body comprises a substantially rectangular plate shape, and is provided with the said fixed end part in the one end part of the longitudinal direction, and the said movable end part in the other end part. 3. The weight measuring device according to claim 1.   5. The weight measuring device according to claim 1, wherein the strain generating portion is provided as at least one concave portion at a position corresponding to the pair of strain sensors. 6. .   The weight measuring device according to claim 5, wherein the strain generating portion is provided as a concave stripe along a direction orthogonal to a direction connecting the fixed end portion and the movable end portion.   The strain sensor is provided on a first surface of the strain generating body, and the strain generating portion is provided on a second surface different from the first surface of the strain generating body. The weight measuring device according to any one of claims 1 to 6.   The weight measuring apparatus according to claim 7, wherein the first surface is an upper surface and the second surface is a lower surface.

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