load cell

Abstract

The weighing sensor (1) of the present application comprises: a strain body (10); a bridge circuit (C) comprising a first strain gauge (R1), a second strain gauge (R2), a third strain gauge (R3) and a fourth strain gauge (R4) arranged on the strain body (10); a first thermistor (R6) arranged on a wire (L1) for applying voltage to the bridge circuit (C) and containing at least copper; and a second thermistor (R7) arranged on a wire (L2) and having a material or a material containing ratio different from the first thermistor (R6), the resistance value of the first thermistor (R6) being 1.12 times or more of the resistance value of the second thermistor (R7).

Description

Technical Field

[0001] This invention relates to weighing sensors. Background Technology

[0002] As an existing type of load cell, a load cell described in Patent Document 1 (Japanese Patent Application Publication No. 61-165606) is known. The load cell described in Patent Document 1 includes: a strain gauge; a bridge circuit composed of multiple strain gauges disposed on the strain gauge; a first thermistor made of copper and disposed on wiring that applies voltage to the bridge circuit; and a second thermistor made of nickel and disposed on the aforementioned wiring. In this load cell, the first and second thermistors are used to correct the primary and secondary components of the temperature dependence of the output voltage, thereby compensating for temperature sensitivity. Summary of the Invention

[0003] Traditionally, in load cells, the resistance ratio of the first thermistor to the second thermistor is designed to be 1:1 (resistance of the first thermistor / resistance of the second thermistor = 1.0). In this configuration where the resistance values ​​of the first and second thermistors are equal, when the temperature is lower (e.g., -10°C) or higher (e.g., 50°C) than a reference temperature (e.g., 20°C), the presence of a secondary component causes a difference in temperature sensitivity (ppm / °C). If a difference in temperature sensitivity occurs between low and high temperatures, it becomes difficult to simultaneously correct the temperature sensitivity on both the low-temperature and high-temperature sides. Furthermore, when there is a significant difference between the reference temperature used for range adjustment and the temperature at which the load cell is used (high or low temperature), the temperature sensitivity increases significantly at the operating temperature. These factors prevent the temperature dependence of the output voltage from being reduced over a wide temperature range. To further improve temperature sensitivity, it is necessary to reduce the temperature dependence of the output voltage over a large temperature range.

[0004] One objective of this invention is to provide a weighing sensor whose temperature sensitivity characteristics can be improved.

[0005] In its intensive research into the aforementioned technical problems, the applicant discovered that by setting an appropriate ratio between the resistance values ​​of the first thermistor and the second thermistor, the difference in temperature sensitivity at low and high temperatures can be reduced, thereby improving temperature sensitivity characteristics. This invention is based on this novel discovery.

[0006] One aspect of the present invention relates to a weighing sensor comprising: a strain gauge; a bridge circuit configured to include a plurality of strain gauges disposed on the strain gauge; a first thermistor disposed on wiring for applying voltage to the bridge circuit and containing at least copper; and a second thermistor disposed on the wiring and having a different material or material content ratio than the first thermistor, wherein the resistance value of the first thermistor is at least 1.12 times the resistance value of the second thermistor.

[0007] The applicant discovered that the higher the resistance value of the second thermistor, the more excessive the correction function of its secondary component becomes. If the secondary component is overcompensated by the second thermistor, a reversed positive and negative secondary component still exists, making it impossible to reduce the temperature dependence of the output voltage over a wide temperature range. Therefore, in a weighing sensor according to one aspect of the present invention, the resistance value of the first thermistor is set to be at least 1.12 times that of the second thermistor. In this way, the resistance value of the first thermistor is set higher than that of the second thermistor in the weighing sensor. In other words, the resistance value of the second thermistor is set lower than that of the first thermistor. Thus, in the weighing sensor, over-correction of the secondary component by the second thermistor can be suppressed, and after appropriately correcting both the primary and secondary components of the output voltage, the temperature dependence of the output voltage is reduced over a wide temperature range from low to high. Therefore, the temperature sensitivity characteristics of the weighing sensor are improved. As a result, the measurement accuracy of the weighing sensor is improved.

[0008] In one embodiment, the resistance value of the first thermistor can be at least 1.32 times that of the second thermistor. This configuration further reduces the difference in temperature sensitivity between low and high temperatures. Therefore, the temperature sensitivity characteristics can be further improved.

[0009] In one embodiment, the resistance value of the first thermistor may be 5.76 times or less than the resistance value of the second thermistor. In this configuration, the secondary component can be appropriately corrected by the second thermistor.

[0010] In one embodiment, the resistance value of the first thermistor may be 3.21 times or less than the resistance value of the second thermistor. In this configuration, the secondary component can be appropriately corrected by the second thermistor.

[0011] In one embodiment, the second thermistor may also contain at least one of nickel, aluminum, gold, cobalt, tantalum, iron, and platinum. In this configuration, the secondary component can be appropriately corrected using the second thermistor.

[0012] According to one aspect of the invention, the temperature sensitivity characteristics are improved. Attached Figure Description

[0013] Figure 1 This is a diagram showing the bridge circuit of a load cell.

[0014] Figure 2 This is a diagram showing the strain gauge of the load cell.

[0015] Figure 3 This is a table showing the simulation results of the weighing sensor involved in Example 1.

[0016] Figure 4 This is a graph showing the simulation results of the weighing sensor involved in Example 1.

[0017] Figure 5 This is a table showing the simulation results of the weighing sensor involved in Example 2.

[0018] Figure 6 This is a graph showing the simulation results of the weighing sensor involved in Example 2. Detailed Implementation

[0019] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in describing the drawings, the same or equivalent elements will be labeled with the same reference numerals, and repeated descriptions will be omitted.

[0020] [Composition of a Weighing Sensor]

[0021] like Figure 1 and Figure 2 As shown, the weighing sensor 1 includes a strain gauge 10, a bridge circuit C, a first thermistor (first thermistor) R6, and a second thermistor (second thermistor) R7.

[0022] like Figure 2 As shown, strain gauge 10 is a metal block in the shape of a cuboid. Strain gauge 10 has a Roborová (parallelogram) shape. Strain gauge 10 is an elastic body formed of metals such as aluminum alloy or stainless steel. Strain gauge 10 has a pair of main faces (not shown) and four side faces 10a, 10b, 10c, and 10d connecting the main faces. In strain gauge 10, for example, side face 10c is a fixed end fixed to the housing of a combined metering device, etc., and side face 10d is a free end to which a load is applied.

[0023] A through portion 12 is provided on the strain gauge 10. The through portion 12 is formed to penetrate a pair of main surfaces of the strain gauge 10. The through portion 12 is generally H-shaped. Specifically, the through portion 12 is formed by two first portions and a second portion with the opposing direction of a pair of side surfaces 10a, 10b as the length direction, and a third portion, the third portion being located between the first portions and the second portions, and having a smaller dimension in the aforementioned opposing direction than the first portions and the second portions.

[0024] The strain gauge 10 includes a first groove portion 14a, a second groove portion 14b, a third groove portion 14c, and a fourth groove portion 14d. The first groove portion 14a, the second groove portion 14b, the third groove portion 14c, and the fourth groove portion 14d are thin-walled portions of the strain gauge 10. The first groove portion 14a and the second groove portion 14b are located between the side surface 10a and the through portion 12. The third groove portion 14c and the fourth groove portion 14d are located between the side surface 10b and the through portion 12.

[0025] like Figure 3 As shown, bridge circuit C has two input terminals T1 and T2, and two output terminals T3 and T4. The output voltage (e) between the two output terminals T3 and T4 of bridge circuit C is... out The output voltage between output terminals T3 and T4 is filtered and then output as a signal indicating the measurement value of the item.

[0026] The bridge circuit C includes a first strain gauge R1, a second strain gauge R2, a third strain gauge R3, and a fourth strain gauge R4. The first strain gauge R1, second strain gauge R2, third strain gauge R3, and fourth strain gauge R4 are constructed, for example, by placing a resistive element, such as a resistance foil, on an electrically insulating material (e.g., polyimide resin). The resistive element is formed, for example, from a metal such as a nickel-chromium alloy. The first strain gauge R1, second strain gauge R2, third strain gauge R3, and fourth strain gauge R4 exhibit resistance changes according to the strain. The first strain gauge R1, second strain gauge R2, third strain gauge R3, and fourth strain gauge R4 form a bridge resistor R. B .

[0027] like Figure 2 As shown, a first strain gauge R1 is disposed on the side 10a of the strain gauge 10. The first strain gauge R1 is disposed on the side 10a at the first slot 14a. A second strain gauge R2 is disposed on the side 10a of the strain gauge 10. The second strain gauge R2 is disposed on the side 10a at the second slot 14b. The first strain gauge R1 and the second strain gauge R2 are disposed at a predetermined interval on the side 10a.

[0028] The third strain gauge R3 is disposed on the side 10b of the strain gauge 10. The third strain gauge R3 is disposed on the side 10b at the third slot 14c. The fourth strain gauge R4 is disposed on the side 10b of the strain gauge 10. The fourth strain gauge R4 is disposed on the side 10b at the fourth slot 14d. The third strain gauge R3 and the fourth strain gauge R4 are disposed at a predetermined interval on the side 10b.

[0029] like Figure 1As shown, a zero-point compensation element R5 is provided in the bridge circuit C. The zero-point compensation element R5 is a component that compensates for the deviation caused by temperature changes in the bridge circuit C at zero point. The zero-point compensation element R5 has a resistance value set for compensating for the zero-point temperature of the bridge circuit C. The zero-point compensation element R5 is connected, for example, between the output terminal T3 and the third strain gauge R3. The zero-point compensation element R5 is, for example, disposed on the side 10b of the strain gauge 10. The zero-point compensation element R5 is, for example, disposed between the third strain gauge R3 and the fourth strain gauge R4.

[0030] A power supply V is connected to input terminals T1 and T2 of the bridge circuit C. A second thermistor R7 is connected to wiring L1, which connects input terminal T1 and power supply V. A first thermistor R6 is connected to wiring L2, which connects input terminal T2 and power supply V. Wiring L1 and L2 are used to apply voltage to the bridge circuit C.

[0031] The first thermistor R6 is a component used to compensate for the temperature sensitivity of the weighing sensor 1. The first thermistor R6 is made of copper. Besides copper, the first thermistor R6 may also contain other materials. For example... Figure 2 As shown, the first thermistor R6 is disposed on the side 10b of the strain gauge 10. The first thermistor R6 is disposed between the third strain gauge R3 and the fourth strain gauge R4.

[0032] The second thermistor R7 is a component used to compensate for the temperature sensitivity of the weighing sensor 1. The second thermistor R7 is made of nickel. The material of the second thermistor R7 is different from that of the first thermistor R6, or the proportions of the materials are different. The second thermistor R7 may contain other substances besides nickel.

[0033] The second thermistor R7 is disposed on the side 10a of the strain gauge 10. The second thermistor R7 is disposed between the first strain gauge R1 and the second strain gauge R2. Furthermore, the first thermistor R6 and the second thermistor R7 are preferably disposed near the positions of the first strain gauge R1, the second strain gauge R2, the third strain gauge R3, and the fourth strain gauge R4 (i.e., the positions of the first slot 14a, the second slot 14b, the third slot 14c, and the fourth slot 14d) so that their temperatures are as equal as possible to those of the first strain gauge R1, the second strain gauge R2, the third strain gauge R3, and the fourth strain gauge R4. They are also preferably disposed away from the positions of the first slot 14a, the second slot 14b, the third slot 14c, and the fourth slot 14d so as not to affect the deformation of the strain gauge 10. Therefore, the first thermistor R6 and the second thermistor R7 are disposed between the first slot 14a and the second slot 14b, and between the third slot 14c and the fourth slot 14d. Therefore, the measurement accuracy will not be reduced due to the physical settings of the first thermistor R6 and the second thermistor R7, thus enabling proper correction of the temperature change curve of the output voltage.

[0034] In this embodiment, the resistance value of the first thermistor R6 is at least 1.12 times the resistance value of the second thermistor R7. Preferably, the resistance value of the first thermistor R6 is at least 1.32 times the resistance value of the second thermistor R7. The resistance value of the first thermistor R6 is at least 5.76 times the resistance value of the second thermistor R7. Preferably, the resistance value of the first thermistor R6 is at least 3.52 times the resistance value of the second thermistor R7. That is, the resistance value of the first thermistor R6 is preferably at least 1.32 times and at least 3.52 times the resistance value of the second thermistor R7.

[0035] [simulation]

[0036] Next, we will explain the simulation results of weighing sensor 1. Figure 3 This is a table showing the simulation results of the weighing sensor 1 involved in Example 1. Figure 4 This is a graph showing the simulation results of the weighing sensor 1 involved in Example 1. Figure 5 This is a table showing the simulation results of the weighing sensor 1 involved in Example 2. Figure 6 This is a graph showing the simulation results of the weighing sensor 1 involved in Example 2.

[0037] The load cell 1 described in Embodiment 1 and the load cell 1 described in Embodiment 2 have different rated loads. The load cell 1 described in Embodiment 1 is, for example, set to a rated load of 6 kg. The load cell 1 described in Embodiment 2 is, for example, set to a rated load of 25 kg. The structure of the load cell 1 described in Embodiments 1 and 2 is the same as that of the strain gauge 10 and the bridge circuit C.

[0038] exist Figure 3 and Figure 5 In this diagram, "Cu" represents the resistance value of the first thermistor R6. "Ni" represents the resistance value of the second thermistor R7. "Cu / Ni" represents the ratio of the resistance values ​​of the first thermistor R6 to the second thermistor R7. "LL" represents the temperature sensitivity (ppm / ℃) when the ambient temperature of the load cell 1 becomes lower than the reference temperature (e.g., -10℃). "HH" represents the temperature sensitivity (ppm / ℃) when the ambient temperature of the load cell 1 becomes higher than the reference temperature (e.g., 50℃). "|LL-HH|" represents the absolute value (ppm / ℃) of the difference between the temperature sensitivity at low temperature and the temperature sensitivity at high temperature.

[0039] exist Figure 4 and Figure 6 In the diagram, the horizontal axis represents the ratio of the first thermistor R6 to the second thermistor R7 (Cu / Ni), and the vertical axis represents the temperature sensitivity (ppm / ℃). Figure 4 and Figure 6 In the diagram, "white dots" represent temperature sensitivity at low temperatures (ppm / ℃), and "black dots" represent temperature sensitivity at high temperatures (ppm / ℃).

[0040] Simulations can be performed using well-known methods. For example, the following formula can be used for simulation. The output voltage of the load cell 1 at a reference temperature (e.g., 20°C) is set to e. out 0 Set the output voltage of the weighing sensor 1 at temperature t to e. out t At that time, e out 0 With e out t The relationship is represented by the following formula (1).

[0041]

[0042] In the above equation (1), R B R is the total resistance value of C in the bridge circuit. M 0 α is the resistance value of the first thermistor R6 and the second thermistor R7 at the reference temperature. ΔT is the difference between the temperature t℃ and the reference temperature. αΔT + βΔT2 This represents the temperature coefficient of resistance (TCR) of the first thermistor R6 and the second thermistor R7. The primary temperature coefficient α and the secondary temperature coefficient β are inherent values ​​of the first thermistor R6 and the second thermistor R7.

[0043] When using a first thermistor R6 containing copper as the material, the resistance value R M(Cu) 0 ( Figure 3 and Figure 4 The value of Cu in the first thermistor R6 and the inherent value α. (Cu) and β (Cu) The resistance value R of the second thermistor R7, which contains nickel as a material, is... M(Ni) 0 ( Figure 3 and Figure 4 The value of Ni in the second thermistor R7 and the inherent value α. (Ni) and β (Ni) When, e can be obtained by the following formula (2). out t .

[0044]

[0045] The output voltage e of the weighing sensor 1 at the actual measured reference temperature is obtained. out 0 e can be calculated out t Furthermore, by using the obtained e out t The temperature sensitivity S (“LL” or “HH”) can be calculated using the following formula (3).

[0046]

[0047] Here, the temperature sensitivity when the resistance values ​​of the first thermistor R6 and the second thermistor R7 change is simulated. The simulation of the weighing sensor 1 is performed in Examples 1 and 2 below. Figure 3 and Figure 4In this context, LL is the temperature sensitivity S calculated at a reference temperature of 20℃ and t = -10℃ (ΔT = -30℃). HH is the temperature sensitivity S calculated at a reference temperature of 20℃ and t = 50℃ (ΔT = 30℃). |LL-HH| is the absolute value of the difference between LL and HH. The more properly the second-order component of the temperature sensitivity is corrected, the closer it is to 0. That is, the smaller |LL-HH| is, the more effectively the temperature dependence of the second-order component of the output voltage can be reduced within a temperature range that deviates significantly from the reference temperature from low to high temperatures.

[0048] Furthermore, after careful investigation, the following situation became clear. Because the resistance value R of the first thermistor R6... M(Cu) 0 The resistance value R of the second thermistor R7 M(Ni) 0 These can be set independently, thus allowing for the determination of a specific resistance value relative to Cu / Ni(R). M(Cu) 0 / R M(Ni) 0 The combination of resistance values ​​(R) M(Cu) 0 and R M(Ni) 0 This is not the only one. However, when the combination of resistance values ​​(R) is varied within the same resistance ratio Cu / Ni range, it can be effective. M(Cu) 0 and R M(Ni) 0 When this was observed, the relationship was: improving LL worsens HH, and improving HH worsens LL. It was also found that regardless of the combination of resistor values ​​(R)... M(Cu) 0 and R M(Ni) 0 For a given resistance value, the absolute value of the difference in temperature sensitivity between Cu / Ni and |LL-HH| does not change significantly. Based on these findings, the range of resistance values ​​for Cu / Ni where |LL-HH| decreases was determined through simulation.

[0049] like Figure 3As shown, in the weighing sensor 1 according to Embodiment 1, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is 1.32, |LL-HH| is less than 10 ppm / ℃ (9.39). In the weighing sensor 1 according to Embodiment 1, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is less than 1.32 (1.24), |LL-HH| is 10 ppm / ℃ or more (10.04). In the weighing sensor 1 according to Embodiment 1, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is 5.76, |LL-HH| is less than 10 ppm / ℃. In the weighing sensor 1 of Embodiment 1, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is greater than 5.76 (6.58), |LL-HH| is 10 ppm / ℃ or more (11.45). In the weighing sensor 1 of Embodiment 1, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is 2.74, |LL-HH| is minimum (0.08 ppm / ℃).

[0050] like Figure 5 As shown, in the weighing sensor 1 of Embodiment 2, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is 1.12, |LL-HH| is less than 10 ppm / ℃ (9.39). In the weighing sensor 1 of Embodiment 2, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is less than 1.12 (1.06), |LL-HH| is 10 ppm / ℃ or more (10.04). In the weighing sensor 1 of Embodiment 2, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is 3.52, |LL-HH| is less than 10 ppm / ℃. In the weighing sensor 1 of Embodiment 2, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is greater than 3.52 (4.22), |LL-HH| is 10 ppm / ℃ or more (10.28). In the weighing sensor 1 of Embodiment 2, when the ratio of the resistance value of the first thermistor R6 to the resistance value of the second thermistor R7 is 2.25, |LL-HH| is minimum (0.08 ppm / ℃).

[0051] [Effects]

[0052] As described above, in the weighing sensor 1 according to this embodiment, the resistance value of the first thermistor R6 is set to be at least 1.12 times the resistance value of the second thermistor R7. In this way, in the weighing sensor 1, the resistance value of the first thermistor R6 is set higher than the resistance value of the second thermistor R7. In other words, the resistance value of the second thermistor R7 is set lower than the resistance value of the first thermistor R6. Therefore, in the weighing sensor 1, over-correction of the second thermistor R7 to the secondary component (reducing the |LL-HH| value) can be suppressed, and the output voltage (e) can be appropriately corrected. out The primary and secondary components of the voltage reduce the output voltage (e) over a wide temperature range from low to high. out Temperature dependence. Specifically, in the weighing sensor 1 according to Example 1, the temperature sensitivity can be set to less than 10 ppm / ℃. Therefore, the temperature sensitivity characteristics of the weighing sensor 1 can be improved. As a result, the measurement accuracy of the weighing sensor 1 is improved.

[0053] In the weighing sensor 1 according to this embodiment, the resistance value of the first thermistor R6 is preferably 1.32 times or more the resistance value of the second thermistor R7. In this configuration, the temperature sensitivity of the weighing sensor 1 according to Embodiment 1 and the weighing sensor 1 according to Embodiment 2 can be less than 10 ppm / ℃. In the weighing sensor 1 according to Embodiment 1, the difference in temperature sensitivity between low and high temperatures can be further reduced. In particular, in the weighing sensor 1 according to Embodiment 1, the temperature sensitivity characteristics can be further improved.

[0054] In the weighing sensor 1 according to this embodiment, the resistance value of the first thermistor R6 is less than 5.76 times the resistance value of the second thermistor R7. In this configuration, the secondary component can be appropriately corrected using the second thermistor R7. In the weighing sensor 1 according to Embodiment 1, the temperature sensitivity can be less than 10 ppm / ℃.

[0055] In the weighing sensor 1 according to this embodiment, the resistance value of the first thermistor R6 is preferably 3.21 times or less than the resistance value of the second thermistor R7. In this configuration, the secondary component can be appropriately corrected using the second thermistor R7. In the weighing sensor 1 according to Embodiment 1 and the weighing sensor 1 according to Embodiment 2, the temperature sensitivity can be less than 10 ppm / ℃.

[0056] In the weighing sensor 1 according to this embodiment, the second thermistor R7 contains nickel. In this configuration, the second thermistor R7 can be used to appropriately correct the secondary component.

[0057] The embodiments of the present invention have been described above, but the present invention is not necessarily limited to the above embodiments, and various modifications can be made without departing from its spirit.

[0058] In the above embodiments, a first thermistor R6 is illustrated as containing copper. Copper is a material with a relatively small second temperature coefficient. However, the first thermistor R6 may also contain molybdenum. Furthermore, a second thermistor R7 is illustrated as containing nickel. Nickel is a material with a relatively large second temperature coefficient. However, the second thermistor R7 may contain at least one of aluminum, gold, cobalt, tantalum, iron, platinum, etc., in addition to nickel, or instead of nickel. The second thermistor R7 preferably contains gold, aluminum, cobalt, tantalum, iron, or platinum, and more preferably gold, aluminum, or cobalt. Additionally, the materials contained in the first thermistor R6 and the second thermistor R7 can be a single metal or an alloy mixed with other impurities.

[0059] In the above embodiment, an example is given where the first thermistor R6 is connected between the power supply V and the input terminal T1, and the second thermistor R7 is connected between the power supply V and the input terminal T2. However, the first thermistor R6 and the second thermistor R7 can also be located in other positions. For example, both the first thermistor R6 and the second thermistor R7 can be located between the power supply V and the input terminal T1, or between the power supply V and the input terminal T2.

[0060] In the above embodiment, an example is illustrated where a first thermistor R6 is disposed on side 10a of the strain gauge 10 between the first strain gauge R1 and the second strain gauge R2, and a second thermistor R7 is disposed on side 10b of the strain gauge 10 between the third strain gauge R3 and the fourth strain gauge R4. However, the first thermistor R6 and the second thermistor R7 may also be disposed in opposite directions on the sides 10c and 10d, outside the first strain gauge R1 and the second strain gauge R2 on side 10a. Furthermore, the first thermistor R6 and the second thermistor R7 may also be disposed in opposite directions on the sides 10c and 10d, outside the third strain gauge R3 and the fourth strain gauge R4 on side 10b. The first thermistor R6 and the second thermistor R7 only need to be positioned away from directly above the first slot 14a, the second slot 14b, the third slot 14c, and the fourth slot 14d (relative to the deformation of the strain gauge 10), and close to the first strain gauge R1, the second strain gauge R2, the third strain gauge R3, and the fourth strain gauge R4. Therefore, the first thermistor R6 and the second thermistor R7 can also be mounted on the main surface of the load cell 1.

[0061] The first thermistor R6 and the second thermistor R7 can also be configured with their resistance values ​​divided separately.

Claims

1. A weighing sensor, comprising: Strain; A bridge circuit is configured to include a plurality of strain gauges disposed on the strain body; A first thermistor, disposed in the wiring for applying voltage to the bridge circuit, and containing at least copper; and A second thermistor is disposed in the wiring, and its material or material content ratio is different from that of the first thermistor. The resistance value of the first thermistor is more than 1.12 times the resistance value of the second thermistor.

2. The weighing sensor according to claim 1, wherein, The resistance value of the first thermistor is more than 1.32 times the resistance value of the second thermistor.

3. The weighing sensor according to claim 1 or 2, wherein, The resistance value of the first thermistor is less than 5.76 times the resistance value of the second thermistor.

4. The weighing sensor according to claim 3, wherein, The resistance value of the first thermistor is less than 3.52 times the resistance value of the second thermistor.

5. The weighing sensor according to claim 1, 2, or 4, wherein, The second thermistor contains at least one of nickel, aluminum, gold, cobalt, tantalum, iron, and platinum.

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