Load measurement system, load transducer

Abstract

To provide a load converter and load measurement system for precisely detecting a load by reducing the influence of noise.SOLUTION: A load converter includes a strain part 2b, strain-sensitive resistance body parts G, wiring parts, and a conductive layer part. The strain part 2b is constituted by a conductive material to be elastically deformed by introducing a load. The strain-sensitive resistance body part G arranged on the strain part 2b via an insulation body so as to detect a strain to be generated in the strain part 2b. The wiring part connects a Wheatstone bridge circuit constituting by including the strain-sensitive resistance body parts G. The conductive layer part is arranged between the wiring parts of output signals at least from the Wheatstone bridge circuit and the strain part 2b respectively via a dielectric body.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a load transducer that converts a load into an electrical signal and a load measurement system including the load transducer. [Background technology]

[0002] Strain-sensitive resistors are used in load transducers to detect minute strains occurring in metals and other materials and convert them into electrical signals. Load transducers include a strain-generating part and a strain-sensitive resistor attached to the strain-generating part. The strain-generating part is a conductive metal component that generates strain when an external force is applied. The strain-sensitive resistor has a base material made of a dielectric material, such as polyimide resin, a folded pattern consisting of a metal resistor formed on the base material, and terminal parts for wiring connection drawn out from the folded pattern. Wiring leads are soldered to the terminal parts to form a Wheatstone bridge circuit.

[0003] In this configuration, when the strain-sensitive resistor is attached to the strain-generating part, the adhesive used to attach the strain-sensitive resistor to the substrate is an insulator (dielectric), so a parasitic capacitance occurs between the pattern part and the strain-generating part. If there is a difference in capacitance between the strain-generating part and the outputs +SIG and -SIG of the Wheatstone bridge circuit, a potential difference occurs between +SIG and -SIG, which is amplified in the amplifier part and appears as noise. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-090394 [Patent Document 2] Patent Publication No. 2021-60267 Summary of the Invention [Problem to be solved by the invention]

[0005] As an example of this noise countermeasure, Patent Document 1 discloses a strain-sensitive resistor-type converter in which a conductive shield layer is provided between multiple strain-sensitive resistors and lead wires and the surface of the strain-generating part, and connected to an amplifier. However, Patent Document 1 leaves room for improvement, as there are insulators (dielectrics) and adhesives between the shield layer and the strain-generating part and between the shield layer and the base of the strain-sensitive resistor, making it difficult to accurately detect the strain in the strain-generating part. Furthermore, the load converter of Patent Document 2 is provided with electrodes to adjust the capacitance, but this requires adjustment time and increases the number of parts, which increases assembly time, leaving room for improvement.

[0006] In view of the above problems, an object of the present invention is to provide a load measurement system and a load transducer that can reduce the influence of noise and accurately detect a load. [Means for solving the problem]

[0007] In order to achieve the above object, a load measurement system according to one aspect of the present invention comprises: A load transducer; The load value is calculated based on the signal obtained by amplifying the output of the load converter. a calculator, a shielded cable connecting the load converter and the calculator; A load measurement system comprising: The load converter is Deformable parts and Load introduction section, The load bearing device has a structure provided with a load receiving portion, a gauge portion, a wiring portion, and a conductive layer portion, The strain-generating part is From the load introduction point load With the introduction of It is made of an elastically deformable conductive material, The gauge section is Divided into a strain-sensitive resistor part and a conductor pattern part It has a surface configuration and is made of insulating material. The sensor has a base body, and is attached to a strain-generating part so that strain occurring in the strain-generating part can be detected. The wiring section is A Wheatstone bridge circuit including a strain sensitive resistor is connected to the signal line of the shielded cable. The conductive layer portion is A multi-layer structure is formed with a first dielectric or a second dielectric interposed between an insulator attached to the load receiving portion, a first opening formed based on a first dielectric stack, and a partially exposed upper conductive layer portion; a second opening formed based on the second dielectric stack, and a lower conductive layer portion partially exposed; The upper conductive layer portion exposed from the first opening is The output signal from the strain-sensitive resistor section, which is at least configured as a Wheatstone bridge circuit, Transmit Wiring section For connecting with connection Part , The lower conductive layer portion exposed from the second opening is The lead wire for connecting to the conductor pattern is connected, and the shielded part of the shielded cable that is connected to the ground of the calculator is connected to the ground. It is configured to be a connecting part for forming a line. .

[0008] In order to achieve the above object, a load measurement system according to one aspect of the present invention comprises: The conductive layer portion is further configured to be provided between a load-receiving portion, which is electrically connected to the strain-generating portion and is made of a conductive material that does not easily deform, and the wiring portion, with a dielectric therebetween.

[0009] In order to achieve the above object, a load converter according to one aspect of the present invention comprises: Deformable parts and Load introduction section, a structural body provided with a load receiving portion, a gauge portion, a wiring portion, and a conductive layer portion; A load transducer having: The strain-generating part is From the load introduction point load With the introduction of It is made of an elastically deformable conductive material, The gauge section is Divided into a strain-sensitive resistor part and a conductor pattern part It has a surface configuration and is made of insulating material. The sensor has a base body, and is attached to a strain-generating part so that strain occurring in the strain-generating part can be detected. The wiring section is A Wheatstone bridge circuit including a strain-sensitive resistor is connected. The conductive layer portion is A multi-layer structure is formed with a first dielectric or a second dielectric interposed between an insulator attached to the load receiving portion, a first opening formed based on a first dielectric stack, and a partially exposed upper conductive layer portion; a second opening formed based on the second dielectric stack, and a lower conductive layer portion partially exposed; The upper conductive layer portion exposed from the first opening is The output signal from the strain-sensitive resistor section, which is at least configured as a Wheatstone bridge circuit, Transmit Wiring section For connecting with connection Part , The lower conductive layer portion exposed from the second opening is A lead wire is connected to connect to the conductor pattern portion, and a ground wiring is connected to connect to the conductor pattern portion. The structure is such that it is a connecting part. .

[0010] In order to achieve the above object, a load converter according to one aspect of the present invention comprises: The conductive layer portion is further configured to be provided between a load-receiving portion, which is electrically connected to the strain-generating portion and is made of a conductive material that does not easily deform, and the wiring portion, with a dielectric therebetween.

[0011] In order to achieve the above object, a load converter according to one aspect of the present invention comprises: The wiring section is connected to a calculator that calculates a load based on an output signal by a shielded cable, and the ground of the calculator and the conductive layer section are connected by the shielded section of the shielded cable. [Effects of the Invention]

[0012] According to the load transducer and load measurement system of the present invention, by providing an electrode for adjusting the capacitance on the strain-flexing part, the influence of noise can be reduced and the load can be detected accurately. [Brief explanation of the drawings]

[0013] [Figure 1]1A is a perspective view of a load converter according to a first and second embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view thereof. [Figure 2] FIG. 2 is a bottom view of the load converter according to the first embodiment of the present invention, with some components omitted. [Figure 3] 1A is a plan view, FIG. 1B is a cross-sectional view, and FIG. 1C is a cross-sectional view of a gauge portion of a load converter according to a first and second embodiment of the present invention. [Figure 4] 1A is a cross-sectional schematic diagram of a wiring board of a load converter according to a first embodiment of the present invention, and FIG. 1B is an exploded schematic diagram showing the connections between the wiring board and a gauge section. [Figure 5] FIG. 10 is a bottom view of a load converter according to a second embodiment of the present invention, with some components omitted. [Figure 6] 10(a) is a cross-sectional view of a wiring board of a load converter according to a second embodiment of the present invention, and FIG. 10(b) is a schematic development showing the connections between the wiring board and a gauge section in an expanded form. [Figure 7] FIG. 4 is a circuit diagram of a load measurement system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a load converter according to an embodiment of the present invention will be described with reference to the drawings.

[0015] Fig. 1(a) is a perspective view of a load converter 1 according to first and second embodiments of the present invention. Fig. 1(b) is a cross-sectional view showing the inside of the load converter 1, with some components omitted. The load converter 1 includes a load introducing portion 2c, a strain-generating portion 2a, a load receiving portion 2d, a gauge portion 7, a wiring board 5, a connector 3, a cover 4, etc.

[0016] Load introduction portion 2c is in direct contact with load P, has high rigidity, does not deform easily, and introduces the load to strain-flexing portion 2a. Strain-flexing portion 2a is relatively thin compared to load introduction portion 2c, and is the portion that elastically deforms due to load P introduced by load introduction portion 2c. Load receiving portion 2d is a highly rigid portion that does not deform easily and receives and supports load P introduced by load introduction portion 2c via strain-flexing portion 2a in the middle. Load receiving portion 2d has a hollow cylindrical shape and has a screw hole 2f on its bottom surface so that it can be attached to a fixed structure or the like (see Figure 2). Load introduction portion 2c, strain-flexing portion 2a, and load receiving portion 2d of housing 2 are made of an integral structure made of a conductive metal material, such as stainless steel, and the overall shape is approximately hollow and cylindrical with a bottom.

[0017] The load converter 1 houses a gauge section 7, which is an element constituting a Wheatstone bridge circuit, an insulating lead wire J (wiring section), and a wiring board 5 (including the wiring section). The gauge section 7 is attached to the strain-flexing section surface 2b, and its resistance value changes in response to the strain generated in the strain-flexing section 2a when a load is applied. The wiring board 5 is a flexible printed wiring board and has part of the wiring of the Wheatstone bridge circuit. The wiring board 5 is fixed to the inner wall surface 2e of the load-receiving section 2d with, for example, an insulating adhesive. Compared to a conventional configuration in which a circular rigid wiring board is arranged parallel to the cover 4, the wiring board 5 has a larger fixed area and is positioned so as to be less susceptible to damage caused by vibrations when a relatively large load P is repeatedly applied to the load-applying section 2c at high speed.

[0018] The lead wire J is an insulating-coated wiring member that connects the gauge section 7 and the wiring board 5. The connector 3 is connected to the wiring board 5. The connector 3 is installed so as to connect the calculator 14 (described below) and the load converter 1 with a shielded cable 6. The lid 4 is a thin, flexible metal plate. The lid 4 is fixed to the load-receiving section 2d by adhesive or welding, and is thin so as not to affect the elastic deformation of the strain-flexing section 2a. The gauge section 7 and wiring board 5 are protected from the external environment by the lid 4.

[0019] FIG. 2 is a bottom view of the load transducer 1 according to the first embodiment of the present invention, omitting some components such as the lead wire J. Each of the gauge sections 7 and 8 has two strain-sensitive resistors, which are arranged at 90-degree intervals in the circumferential direction so that their longitudinal directions are aligned with the radial direction of the strain-generating surface 2b. The gauge sections 7 and 8 are attached to the strain-generating surface 2b with a dielectric adhesive (e.g., epoxy or phenolic). In this embodiment, the strain-sensitive resistor section G1 is composed of two strain-sensitive resistor sections G1a and G1b in a folded pattern formed on a single insulating substrate. The insulating (dielectric) material of the substrate is, for example, a polyimide film, and the strain-sensitive resistor sections G1a and G1b are made of a copper-nickel alloy or a nickel-chromium alloy. The strain-sensitive resistor sections G2 to G4 are also composed of the same material as the strain-sensitive resistor section G1. The maximum sensitivity direction of each of the strain-sensitive resistor sections G1 to G4 is the radial direction of the strain-generating surface 2b. Each strain sensitive resistor portion G is provided with a connection portion Tg for soldering a lead wire J (see FIG. 3).

[0020] The wiring board 5 is attached to the inner wall surface 2e with a dielectric adhesive (epoxy or phenolic). Wiring from the terminals of the connector 3 is electrically connected to the connection terminals T1 to T5 of the wiring board 5 by soldering. Furthermore, the terminals of the connector 3 are connected to the lead wires and shield portion of the shielded cable 6.

[0021] Fig. 3(a) is a plan view of the gauge section 7 of the load transducer according to the first and second embodiments of the present invention. Fig. 3(b) is a schematic cross-sectional view taken along line AA in Fig. 3(a), and Fig. 3(c) is a schematic cross-sectional view taken along line BB in Fig. 3(a). In Fig. 3(a), the gauge section 7 has strain-sensitive resistor sections G1a / G1b and G2a / G2b and conductive layers Sp1 / Sp2. The strain-sensitive resistor sections G1a / G1b and G2a / G2b each have a grid shape with maximum sensitivity in the X direction in the figure, and have a connection section Tg drawn out from this grid section. On the other hand, the conductive layers Sp1 / Sp2 are a roughly U-shaped conductor pattern arranged to surround the strain-sensitive resistor sections G1a / G1b and G2a / G2b in a plan view. The conductive layers Sp1 / Sp2 may be made of the same metal as the strain sensitive resistor portions G1a / G1b and G2a / G2b, or may be made of a metal such as copper.

[0022] As shown in FIG. 3(b), the gauge section 7 has a layered structure. The strain-sensitive resistor sections G1a / G1b and G2a / G2b are laminated on a substrate 7a, and a protective layer 7c is further laminated on top of that. The protective layer 7c protects the strain-sensitive resistor sections G1a / G1b and G2a / G2b from moisture and the like, and is made of, for example, a polyimide film. The protective layer 7c has a portion opening so that the connection section Tg is exposed. Meanwhile, as shown in FIG. 3(c), the conductive layers Sp1 / Sp2 are also sandwiched between the substrate 7a and the protective layer 7c, and an opening is provided in a portion of the protective layer 7c so that the connection section Tg is exposed. The gauge section 7 can be formed by laminating the protective layer 7c after drilling holes corresponding to the connection sections Tg in the film.

[0023] In this embodiment, the conductive layers Sp1 / Sp2 are formed as part of the gauge section 7, but they may be formed as separate bodies. That is, a U-shaped member having the conductive layers Sp1 / Sp2 on a dielectric layer may be attached to the strain-generating surface 2b around the strain-sensitive resistor sections G1a / G1b and G2a / G2b.

[0024] In addition, the formation of the strain-sensitive resistor portions G1a / G1b, G2a / G2b and the conductive layers Sp1 / Sp2 may be modified by forming an insulating layer such as SiO2 on the strain-generating portion surface 2b, laminating a metal foil thereon, and then selectively removing the metal foil by laser irradiation to perform patterning.

[0025] Fig. 4(a) is a cross-sectional view of the wiring board of the load converter of the first embodiment of the present invention, and Fig. 4(b) is an exploded view showing the state of connection between the wiring board 5 and the gauge sections 7 and 8. Fig. 4(a) is a cross-sectional view taken along CC in Fig. 4(b).

[0026] The wiring board 5 is, for example, a flexible substrate. The wiring board 5 includes a base material 5a, a conductive layer portion 5b, a dielectric layer 5c, a conductive layer 5d, and a dielectric layer 5e. The base material 5a is, for example, a rectangular polyimide film. The conductive layer portion 5b is, for example, copper foil, laminated on the base material 5a via an adhesive, and has approximately the same area as the entire surface of the base material 5a. The dielectric layer 5c is also a polyimide film, and has openings formed in portions of the conductive layer portion 5b that are to be exposed. The conductive layer 5d is also, for example, copper foil, and is laminated on the dielectric layer 5c via an adhesive, and has patterns P1 to P8 and connection terminals T1 to T5 formed thereon. The patterns P1 to P8 and connection terminals T1 to T4 are portions of the foil that is attached to the entire surface and selectively left unetched by etching or the like. The dielectric layer 5e is also a polyimide film, and has openings formed in portions of the conductive layer 5d that are to be exposed. The wiring board 5 is manufactured using a typical two-layer flexible substrate manufacturing method, but this is not a limitation. For example, a first substrate is prepared by laminating a conductive layer 5b over the entire surface of a base material 5a, which is a dielectric layer. Separately, a single-sided copper-clad substrate is prepared by cutting out only the portions where the conductive layer 5b will be opened. A predetermined pattern is then applied to the substrate, and a dielectric layer 5e is laminated on the substrate, and a predetermined portion of the dielectric layer 5e is removed to prepare a second substrate. The wiring substrate 5 can then be prepared by laminating the second substrate onto the first substrate. The exposed copper foil portions, such as the connection terminals T1 to T5, can be easily bonded to the lead wires J by applying an anti-rust treatment or solder coating.

[0027] As shown in Fig. 4(b), the wiring board 5 and each of the gauge sections 7 and 8 are connected by lead wires J. In the first embodiment, two gauge sections 7 and two gauge sections 8 are connected to the wiring board 5. The gauge sections 8 are of a type in which there is no conductive layer Sp around the strain-sensitive resistor.

[0028] The following will be explained starting from the left side of Fig. 4(b). One end of the connection portion Tg of the strain-sensitive resistor portion G2a of the gauge portion 7 is connected by a lead wire J2a1 to a land provided on the pattern P5, and the other end is connected by a lead wire J2a2 to a land provided on the pattern P1. These lands are the portions of the patterns P1 to P8 where the dielectric layer 5e is opened and the copper foil of the pattern P is exposed. This land can also be easily joined to the lead wire J by applying an anti-corrosion treatment agent or solder coating. One end of the connection portion Tg of the strain-sensitive resistor portion G2b of the gauge portion 7 is connected by a lead wire J2b1 to a land provided on the pattern P5, and the other end is connected by a lead wire J2b2 to a land provided on the pattern P2. The coatings of the lead wires J2a1, J2a2, J2b1, and J2b2 all pass over the conductive layer Sp2 and are fixed to the protective layer 7c and the top surface of the dielectric layer 5e with a silicone adhesive, etc. The connection portion Tg of the conductive layer Sp2 is connected to the conductive layer portion 5b by the lead wire JB, and the coating of the lead wire JB is fixed to the strain-flexing surface 2b with a silicone adhesive, etc.

[0029] One end of the connection portion Tg of the strain-sensitive resistor portion G1a of the gauge section 7 is connected to a land provided on pattern P7 by a lead wire J1a1, and the other end is connected to a land provided on pattern P3 by a lead wire J1a2. Similarly, one end of the connection portion Tg of the strain-sensitive resistor portion G1b of the gauge section 7 is connected to a land provided on pattern P7 by a lead wire J1b1, and the other end is connected to a land provided on pattern P4 by a lead wire J1b2. The coatings of the lead wires J1a1, J1a2, J1b1, and J1b2 all pass through the upper part of the conductive layer Sp1 and are fixed to the protective layer 7c and the upper surface of the dielectric layer 5e via a silicone-based adhesive or the like. The connection portion Tg of the conductive layer Sp1 is connected to the conductive layer portion 5b by a lead wire JA, and the coating of the lead wire JA is fixed to the strain-flexing portion surface 2b via a silicone-based adhesive or the like.

[0030] One end of the connection portion Tg of the strain-sensitive resistor portion G4a of the gauge portion 8 is connected by a lead wire J4a1 to a land provided on the pattern P8, and the other end is connected by a lead wire J4a2 to a land provided on the pattern P1. Similarly, one end of the connection portion Tg of the strain-sensitive resistor portion G4b of the gauge portion 8 is connected by a lead wire J4b1 to a land provided on the pattern P6, and the other end is connected by a lead wire J4b2 to a land provided on the pattern P2. The coatings of the lead wires J4a1, J4a2, J4b1, and J4b2 are all fixed to the strain-flexing portion surface 2b and the dielectric layer 5e via a silicone adhesive or the like.

[0031] One end of the connection portion Tg of the strain-sensitive resistor portion G3a of the gauge portion 8 is connected by a lead wire J3a1 to a land provided on the pattern P6, and the other end is connected by a lead wire J3a2 to a land provided on the pattern P3. Similarly, one end of the connection portion Tg of the strain-sensitive resistor portion G3b of the gauge portion 8 is connected by a lead wire J3b1 to a land provided on the pattern P8, and the other end is connected by a lead wire J3b2 to a land provided on the pattern P4. The coatings of the lead wires J1a1, J1a2, J1b1, and J1b2 are all fixed to the strain-flexing portion surface 2b and the dielectric layer 5e via a silicone adhesive or the like.

[0032] 4(b), the connection terminals T1 to T5 are electrically connected to the shielded cable 6 via the connector 3 shown in Fig. 1 and Fig. 2. The electric wire for supplying power to the shielded cable 6 is connected to the connection terminals T1 and T2, the signal wire for analog output from the load converter of the shielded cable 6 is connected to the connection terminals T3 and T4, and the shield portion 6a of the shielded cable 6 is connected to the connection terminal T5.

[0033] FIG. 5 is a bottom view of a load transducer 1 according to a second embodiment of the present invention, with some components such as the lead wires J omitted. In the second embodiment, four gauge sections 7 are arranged in the same pattern. Two strain-sensitive resistors are provided in each gauge section 7, and the resistors are arranged at 90-degree intervals in the circumferential direction so that their longitudinal directions are aligned with the radial direction of the strain-generating surface 2b. The gauge sections 7 are attached to the strain-generating surface 2b with a dielectric adhesive (e.g., epoxy or phenol-based). As the other parts are the same as those in the first embodiment, their explanations will be omitted.

[0034] Fig. 6(a) is a cross-sectional view of the wiring board of a load converter according to a second embodiment of the present invention, and Fig. 6(b) is a schematic development view (b) showing the connections between the wiring board and the gauge section. Fig. 6(a) is a cross-sectional view taken along line DD in Fig. 6(b). Only the differences from the first embodiment will be explained below. In the second embodiment of the present invention, the gauge section 7 is arranged in the same four patterns. The points where the gauge section 7 is connected to the strain-sensitive resistor sections G1a, G1b, G2a, and G2b are the same as in the first embodiment.

[0035] A conductive layer Sp4 is arranged around the strain sensitive resistor portions G4a and G4b of the gauge portion 7, and a conductive layer Sp3 is arranged around the strain sensitive resistor portions G3a and G3b of the gauge portion 7.

[0036] One end of the connection portion Tg of the strain-sensitive resistor portion G4a of the gauge section 7 is connected to a land on pattern P8 by lead wire J4a1, and the other end is connected to a land on pattern P1 by lead wire J4a2. Similarly, one end of the connection portion Tg of the strain-sensitive resistor portion G4b of the gauge section 7 is connected to a land on pattern P6 by lead wire J4b1, and the other end is connected to a land on pattern P2 by lead wire J4b2. The coatings of the lead wires J4a1, J4a2, J4b1, and J4b2 all pass through the upper portion of the conductive layer Sp4 and are fixed to the protective layer 7c and the upper surface of the dielectric layer 5e via a silicone adhesive or the like. The connection portion Tg of the conductive layer Sp4 is connected to the conductive layer portion 5b by lead wire JD, and the coating of the lead wire JD is fixed to the strain-flexing portion surface 2b via a silicone adhesive or the like.

[0037] One end of the connection portion Tg of the strain-sensitive resistor portion G3a of the gauge section 7 is connected to a land on pattern P6 by a lead wire J3a1, and the other end is connected to a land on pattern P3 by a lead wire J3a2. Similarly, one end of the connection portion Tg of the strain-sensitive resistor portion G3b of the gauge section 7 is connected to a land on pattern P8 by a lead wire J3b1, and the other end is connected to a land on pattern P4 by a lead wire J3b2. The coatings of the lead wires J3a1, J3a2, J3b1, and J3b2 all pass through the upper portion of the conductive layer Sp3 and are fixed to the protective layer 7c and the upper surface of the dielectric layer 5e with a silicone-based adhesive or the like. The connection portion Tg of the conductive layer Sp3 is connected to the conductive layer portion 5b by a lead wire JC, and the coating of the lead wire JC is fixed to the strain-flexing portion surface 2b with a silicone-based adhesive or the like.

[0038] FIG. 7 is a schematic circuit diagram showing a load converter 1 according to a second embodiment of the present invention, including a shielded cable 6 and a calculator 14. The load converter 1 has a Wheatstone bridge circuit including a strain-sensitive resistor. The calculator 14 includes a power supply 10, an amplifier 11, and an A / D (analog-to-digital) converter 12. The power supply 10 applies a voltage to connection terminals T1 and T2 of the Wheatstone bridge circuit. The amplifier 11 amplifies and outputs output signals +SIG and -SIG from connection terminals T3 and T4 of the Wheatstone bridge circuit. The amplifier 11 is, for example, a differential amplifier. The analog signal output from the amplifier 11 is converted into a digital signal by the A / D converter 12, and then a load value is calculated and displayed by a calculation display device (not shown) or the like. These power supplies and analog signals are transmitted by electric wires surrounded by the shield portion 6a of the shielded cable 6.

[0039] Strain sensitive resistor sections G2a and G4a are arranged on side S1 of the Wheatstone bridge circuit between connection terminals T1 and T4. Strain sensitive resistor sections G1b and G3b are arranged on side S4, which is adjacent to side S1 with connection terminal T1 in between. Strain sensitive resistor sections G2b and G4b are arranged on side S2. Strain sensitive resistor sections G1a and G3a are arranged on side S3, which is adjacent to side S2 with connection terminal T2 in between. Analog signal outputs +SIG and -SIG travel through patterns P1 to P8 on wiring board 5 and insulating lead wires J. The strain sensitive portion surface 2b and inner wall surface 2e of housing 2 are connected to noise source 13.

[0040] A parasitic capacitance Cg1 exists between the strain-generating portion surface 2b and the conductive layer Sp1 due to the presence of the substrate 7a, which is a dielectric layer. Note that all of the capacitors shown in FIG. 7 represent parasitic capacitances. Similarly, parasitic capacitances Cg2 to Cg4 exist between the strain-generating portion surface 2b and each of the conductive layers Sp2 to Sp4 due to the presence of the substrate 7a. Meanwhile, a parasitic capacitance Cf exists between the inner wall surface 2e and the conductive layer portion 5b of the wiring board 5 due to the presence of the substrate 5a, which is a dielectric layer. The conductive layer portion 5b of the wiring board 5 and each of the conductive layers Sp1 to Sp4 are electrically connected by lead wires JA to JD, respectively. The end of the shield portion 6a of the shielded cable 6 is connected to a connection terminal T5 provided on the conductive layer portion 5b of the wiring board 5, and this shield portion 6a is connected to the ground on the amplifier section 11 side.

[0041] Next, the parasitic capacitance around each strain-sensitive resistor will be described. A parasitic capacitance C1a1 exists between the lead wire J1a1 drawn from the connection portion Tg of the strain-sensitive resistor portion G1a and the conductive layer Sp1, and between the lead wire J1a1 and the conductive layer portion 5b. A parasitic capacitance C1a2 exists between the lead wire J1a2 drawn from the connection portion Tg of the strain-sensitive resistor portion G1a and the conductive layer Sp1, and between the lead wire J1a2 and the conductive layer portion 5b. Similarly, a parasitic capacitance C1b1 exists between the lead wire J1b1 drawn from the connection portion Tg of the strain-sensitive resistor portion G1b and the conductive layer Sp1, and between the lead wire J1b1 and the conductive layer portion 5b. A parasitic capacitance C1b2 exists between the lead wire J1b2 drawn from the connection portion Tg of the strain-sensitive resistor portion G1b and the conductive layer Sp1, and between the lead wire J1b2 and the conductive layer portion 5b. The same applies to the strain sensitive resistor portion G2a and the strain sensitive resistor portion G2b.

[0042] Next, we will explain the parasitic capacitance in each wiring pattern of the wiring board 5. A parasitic capacitance Cp1 exists between the pattern P1 and the conductive layer portion 5b of the wiring board 5. Similarly, parasitic capacitances Cp2 to Cp8 exist between each of the patterns P2 to P8 and the conductive layer portion 5b, respectively.

[0043] Here, noise source 13 penetrates into conductive layer portion 5b through housing 2, but since conductive layer portion 5b and each conductive layer Sp are wired and therefore at the same potential, and conductive layer portion 5b is connected to the ground of calculator 14, no noise current flows in the lines of output signals +SIG and -SIG of the Wheatstone bridge circuit, and therefore no noise influence occurs.

[0044] Furthermore, in the strain sensitive resistor portions G3a, G3b, G4a, and G4b, by connecting the conductive layers Sp3 and Sp4 of these wirings to the conductive layer portion 5b, respectively, and arranging the lead wires J3a1, J3a2, J3b1, J3b2, J4a1, J4a2, J4b1, and J4b2 on the upper surfaces of the conductive layers Sp3 and Sp4, respectively, noise intrusion can be further prevented.

[0045] According to an embodiment of the present invention, each strain-sensitive resistor is directly attached to the strain-generating part via an insulator, and at least the wiring material for the output signal that detects the strain is placed on the upper surface of the conductive layer. This conductive layer and the ground of the amplifier are connected by the shield part of the shielded cable, thereby preventing the influence of noise and enabling accurate detection of the load.

[0046] The present invention has been described above based on a preferred embodiment, but the present invention is not limited to the above-described embodiment and various modifications are possible without departing from the spirit of the present invention. [Industrial Applicability]

[0047] As an example of application of the present invention, it can be applied to load cells, etc. [Explanation of symbols]

[0048] 1: Load converter 2: Housing 2a: Strain part 2b: Strain-generating part surface 2c: Load introduction section 2d: Load receiving part 2e: Inner wall 2f: screw hole 3: Connector 4: Lid 5: Wiring board 5b: Conductive layer portion 6: Shielded cable 6a: Shield part 7: Gauge section 7a: Base material (insulator) 8: Gauge section 10: Power supply 11: Amplification section 12: A / D conversion section 13: Noise source 14: Calculator G1a~G4a: Strain sensitive resistor part G1b~G4b: Strain sensitive resistor part J: Lead wire (wiring part) P1 to P8: Pattern (wiring section) Sp1~Sp4: Conductive layer part Tg: Connection T1~T5: Connection terminals

Claims

1. a load converter, a calculator that calculates a load value based on a signal obtained by amplifying the output of the load converter, and a shielded cable that connects the load converter and the calculator; A load measurement system comprising: The load converter is The device has a structure in which a strain-flexing portion, a load-introducing portion, and a load-receiving portion are provided, a gauge portion, a wiring portion, and a conductive layer portion, The strain-flexing part is The load-applied portion is made of a conductive material that elastically deforms when a load is applied thereto through the load-applied portion, The gauge section is The device has a surface structure divided into a strain-sensitive resistor portion and a conductor pattern portion, and has a planar substrate made of an insulating material, and is capable of detecting strain occurring in the strain-generating portion by attaching the substrate to the strain-generating portion, The wiring portion is a Wheatstone bridge circuit including the strain sensitive resistor section is connected to the signal line of the shielded cable; The conductive layer portion is a multi-layer structure in which a first dielectric or a second dielectric is interposed between the insulator attached to the load receiving portion, a first opening formed on the first dielectric layer stack to partially expose an upper conductive layer portion; a second opening formed based on the second dielectric stack, and a lower conductive layer portion partially exposed; The upper conductive layer portion exposed from the first opening is a connecting portion for connecting to the wiring portion that transmits an output signal from the strain sensitive resistor portion that is configured as at least the Wheatstone bridge circuit, The lower conductive layer portion exposed from the second opening is a connection portion to which a lead wire for connecting to the conductor pattern portion is connected and which serves as a conductive connection to a shield portion of the shielded cable that is connected to the ground of the calculator; A load measurement system comprising:

2. A load transducer having a structure provided with a strain-flexing part, a load-introducing part, and a load-receiving part, a gauge part, a wiring part, and a conductive layer part, The strain-flexing part is The load-applied portion is made of a conductive material that elastically deforms when a load is applied thereto through the load-applied portion, The gauge section is The device has a surface structure divided into a strain-sensitive resistor portion and a conductor pattern portion, and has a planar substrate made of an insulating material, and is capable of detecting strain occurring in the strain-generating portion by attaching the substrate to the strain-generating portion, The wiring portion is a Wheatstone bridge circuit including the strain sensitive resistor section is connected; The conductive layer portion is a multi-layer structure in which a first dielectric or a second dielectric is interposed between the insulator attached to the load receiving portion, a first opening formed on the first dielectric layer stack to partially expose an upper conductive layer portion; a second opening formed based on the second dielectric stack, and a lower conductive layer portion partially exposed; The upper conductive layer portion exposed from the first opening is a connecting portion for connecting to the wiring portion that transmits an output signal from the strain sensitive resistor portion that is configured as at least the Wheatstone bridge circuit, The lower conductive layer portion exposed from the second opening is A lead wire for connecting to the conductor pattern portion is connected to the connecting portion, and the connecting portion serves as a connection portion for connecting to a ground wiring. A load converter comprising:

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