Load Sensor Element
The load sensor element with a reinforcing layer aligned with the inorganic layer on the substrate addresses stress concentration issues by forming a gap, improving durability and accuracy in load detection.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-03-25
- Publication Date
- 2026-03-06
AI Technical Summary
The deformation of the base when a load sensor element is applied causes stress concentration at the boundary between the covered and exposed portions, leading to potential substrate deformation and damage.
A load sensor element with a reinforcing layer on the back surface of the substrate, aligned with the inorganic layer on the front surface, forms a gap between the exposed substrate and the base, preventing the edge of the depression from pushing up the substrate and reducing stress concentration.
This configuration suppresses substrate deformation and stress concentration, enhancing durability and accuracy in load detection by maintaining the substrate's integrity and reducing material costs.
Smart Images
Figure 0007825481000001 
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Figure 0007825481000003
Abstract
Description
[Technical Field]
[0001] The present invention relates to a load sensor element. [Background technology]
[0002] Patent Document 1 discloses a load sensor element.
[0003] The load sensor element includes a substrate, a thin-film resistor provided on the surface of the substrate, and an inorganic layer provided on the surface of the substrate so as to cover the main body of the thin-film resistor. The surface of the substrate is formed with a covered portion covered with the inorganic layer and an exposed portion not covered with the inorganic layer. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Patent Publication No. 2021-032805 Summary of the Invention [Problem to be solved by the invention]
[0005] When such a load sensor element is placed on a flat base to be measured and a load is applied to the inorganic layer, the base may deform so that the portion of the base that receives the load from the inorganic layer is recessed in response to the load. When the base returns to its original state after the load is applied, this deformation also returns to its original flat state. In other words, the base repeatedly deforms each time a load is applied.
[0006] As a result, the substrate receives force from the edge of the recess, which can cause deformation of the substrate such that the exposed portion lifts off the pedestal, resulting in stress concentration at the boundary between the covered portion and the exposed portion.
[0007] Therefore, an object of the present invention is to make it possible to suppress the concentration of stress occurring in the substrate. [Means for solving the problem]
[0008] A load sensor element according to one embodiment of the present invention is a load sensor element for measuring a surface pressure load. The load sensor element comprises a substrate and a first layer provided on one surface of the substrate and covering a part of the substrate. The load sensor element comprises a thin-film resistor, which is a resistor whose resistance value changes depending on the load received from the first layer, provided on the one surface and having a main body sandwiched between the substrate and the first layer and both ends placed on exposed parts of the substrate that are not covered by the first layer. The load sensor element comprises a pair of electrodes electrically connected to both ends of the thin-film resistor, respectively, and a first layer that sandwiches the substrate together with the first layer. The whole inside On the other side of the substrate Contact Established Alternatively, the entire inner surface is provided on the other surface of the substrate via only an adhesive layer. The load sensor element has a first layer on one surface of the substrate, which is one side of the first layer that contacts the one surface of the substrate, forming a boundary line between the covered portion covered with the first layer and the exposed portion, and a second layer on the other surface of the substrate, which is one side of the second layer that contacts the other surface of the substrate, forming a boundary line between the portion covered with the second layer and a portion where the second layer is not provided, and the first layer and the second layer are arranged so that the two boundary lines are aligned in the thickness direction of the substrate. [Effects of the Invention]
[0009] According to this aspect, the second layer is provided on the other surface of the substrate of the load sensor element, and the first layer and the second layer are arranged so that the edge of the first layer in contact with one surface of the substrate and the edge of the second layer in contact with the other surface of the substrate are aligned in the thickness direction of the substrate.
[0010] When this load sensor element is set on the object to be measured, the second layer of the load sensor element comes into contact with the base of the object on which the load sensor element is placed, and a gap is formed between the exposed part of the substrate that is not covered by the second layer and the base.
[0011] In this state, even if the load applied to the load sensor element is generated in the second layer, causing a deformation that causes a depression in the base (sometimes simply referred to as a depression), as long as the depth of the depression is equal to or less than the thickness dimension of the second layer, the edge of the depression will not push up the substrate.
[0012] This makes it possible to suppress the concentration of stress on the substrate compared to when the edge of the recess to be measured comes into contact with the substrate of the load sensor element, deforming the substrate and concentrating stress at the boundary between the covered portion and the exposed portion. [Brief explanation of the drawings]
[0013] [Figure 1] FIG. 1 is a perspective view of a load sensor element according to a first embodiment, as viewed from the front surface side. [Figure 2] FIG. 2 is a diagram showing the load sensor element according to the first embodiment, and is a plan view showing the load sensor element from which the leads have been removed as viewed from the front surface side. [Figure 3] FIG. 3 is a diagram showing the load sensor element according to the first embodiment, and is a plan view showing the load sensor element from which the leads have been removed, as viewed from the back surface side. [Figure 4] FIG. 4 is a perspective view of the load sensor element according to the second embodiment as viewed from the front surface side. [Figure 5] FIG. 5 is a perspective view of the load sensor element according to the third embodiment as viewed from the front surface side. [Figure 6] FIG. 6 is a perspective view of the load sensor element according to the fourth embodiment as viewed from the front surface side. [Figure 7] FIG. 7 is a perspective view of the load sensor element according to the fifth embodiment as viewed from the front surface side. [Figure 8] FIG. 8 is a diagram showing a load sensor element according to a fifth embodiment, and is a plan view showing a state in which the load sensor element with the leads removed is viewed from the front surface side. [Figure 9] FIG. 9 is a diagram showing the load sensor element according to the first embodiment, and is a plan view showing the load sensor element from which the leads have been removed, as viewed from the back surface side. [Figure 10]FIG. 10 is a circuit diagram showing an example of use of the load sensor element according to the fifth embodiment. [Figure 11] FIG. 11 is a perspective view of the load sensor element according to the sixth embodiment as viewed from the back surface side. DETAILED DESCRIPTION OF THE INVENTION
[0014] Hereinafter, an embodiment of the invention will be described with reference to the accompanying drawings.
[0015] (First embodiment) First, a load sensor element 10 according to a first embodiment will be described with reference to FIGS.
[0016] Fig. 1 is a perspective view of the load sensor element 10 according to the first embodiment as seen from the front side. Fig. 2 is a diagram showing the load sensor element 10 according to the first embodiment, and is a plan view showing the load sensor element 10 with the leads removed as seen from the front side. Fig. 3 is a diagram showing the load sensor element 10 according to the first embodiment, and is a plan view showing the load sensor element 10 with the leads removed as seen from the back side.
[0017] The load sensor element 10 according to this embodiment is a sensor element for measuring a surface pressure load. The load sensor element 10 is provided, for example, in a machine tool and is used to detect a load in the machining axis direction of the machine tool and perform preload management.
[0018] In this embodiment, the load sensor element 10 is used in a machine tool, but the use of the load sensor element 10 is not limited to this. The load sensor element 10 according to this embodiment can be used for other purposes.
[0019] 1, the load sensor element 10 includes a substrate 20 and an inorganic layer 24 as a first layer provided on a front surface 22, which is one surface of the substrate 20, and covering a part of the front surface 22 of the substrate 20. The load sensor element 10 also includes a reinforcing layer 28 as a second layer provided on a back surface 26, which is the other surface of the substrate 20, so as to sandwich the substrate 20 together with the inorganic layer 24.
[0020] 2, the load sensor element 10 is provided on the surface 22 of the substrate 20 and includes a thin-film resistor 30 configured as a resistor whose resistance value changes in response to the load received from the inorganic layer 24. The thin-film resistor 30 has a main body portion 32 sandwiched between the substrate 20 and the inorganic layer 24, and one end portion 36 and the other end portion 38 disposed in an exposed portion 34 on the surface 22 of the substrate 20 that is not covered with the inorganic layer 24.
[0021] A first electrode 40 is electrically connected to one end 36 of the thin film resistor 30. A second electrode 42 is electrically connected to the other end 38 of the thin film resistor 30.
[0022] (substrate) The substrate 20 has a rectangular shape in a plan view. The substrate 20 is formed in the shape of a vertically long rectangular plate.
[0023] The edge of one side 50 of the substrate 20 in the length direction (longitudinal or vertical axis direction) constitutes one substrate edge 52. The edge of the other side 54 of the substrate 20 constitutes the other substrate edge 56. The edge of one side 60 of the substrate 20 in the width direction (short direction or horizontal axis direction) constitutes one substrate edge 62. The edge of the other side 64 of the substrate 20 constitutes the other substrate edge 66.
[0024] The substrate 20 is made of, for example, an insulating material, such as a glass epoxy substrate made of woven glass fabric impregnated with epoxy resin, a metal substrate made of a metal material with an insulating layer formed on the surface, or a ceramic substrate made of a ceramic material.
[0025] The substrate 20 of this embodiment is made of, for example, a ceramic substrate. From the viewpoint of improving compressive strength and providing the substrate with appropriate flexibility, it is preferable that the substrate 20 uses zirconia (ZrO2) or alumina (Al2O3) as the main component of the ceramic material.
[0026] The surface 22 of the substrate 20 has a rectangular (including square) covered portion 70 that is covered with the inorganic layer 24, and a rectangular exposed portion 34 that is not covered with the inorganic layer 24. The covered portion 70 forms a pressure-receiving region 74 to which a load is applied when the inorganic layer 24 is pressurized.
[0027] (Inorganic layer) As shown in FIG. 1 , the inorganic layer 24 has a surface 22 that forms a pressure-receiving surface 80. The entire surface of the pressure-receiving surface 80 is pressurized almost uniformly by a load. The inorganic layer 24 has a rectangular (including square) plate shape in a plan view. The inorganic layer 24 is made of an inorganic material. The material forming the inorganic layer 24 may be the same material as the substrate 20 or a different material from the substrate 20.
[0028] The inorganic layer 24 is made of, for example, an insulating ceramic substrate. As with the substrate 20, the material of the inorganic layer 24 is preferably made of zirconia (ZrO2) or alumina (Al2O3) as the main component of the ceramic material.
[0029] The inorganic layer 24 may be formed by a lamination method such as sputtering, etc. As a method for forming the inorganic layer 24, other forming methods can be selected depending on the thickness dimension of the inorganic layer 24, etc.
[0030] As shown in Figure 2, the inorganic layer 24 has a smaller area than the substrate 20. The edge of one side 50 of the inorganic layer 24 constitutes an inorganic layer one end edge 82. The edge of the other side 54 of the inorganic layer 24 constitutes an inorganic layer other end edge 84. The edge of one side 60 in the width direction of the inorganic layer 24 constitutes an inorganic layer one side edge 86. The edge of the other side 64 of the inorganic layer 24 constitutes an inorganic layer other side edge 88.
[0031] An inorganic layer one edge 82, which is one side of the inorganic layer 24 in contact with one surface of the substrate 20, forms a boundary line 90 between the covered portion 70 and the exposed portion 34 of the substrate 20. An inorganic layer other edge 84 is located on the substrate other edge 56. An inorganic layer one side edge 86 is located on the substrate one side edge 62. An inorganic layer other side edge 88 is located on the substrate other side edge 66.
[0032] The inorganic layer 24 covers a portion of the surface 22 of the substrate 20. The inorganic layer 24 covers a portion (main body 32) of the thin-film resistor 30 provided on the substrate 20, but does not cover the ends 36, 38 (both ends) of the thin-film resistor 30.
[0033] The inorganic layer 24 is fixed to the substrate 20 by an adhesive layer (not shown) made of a resin material. The adhesive layer is mainly made of, for example, epoxy resin.
[0034] (reinforcement layer) 3, the reinforcing layer 28 has a rectangular (including square) plate shape in a plan view. The reinforcing layer 28 has the same shape as the inorganic layer 24.
[0035] The reinforcing layer 28 has approximately the same size as the inorganic layer 24. The same size means that the degree of size is the same (in this embodiment, at least the width and length are the same).
[0036] Furthermore, the phrase "the reinforcing layer 28 and the inorganic layer 24 are approximately the same size" also includes cases where the reinforcing layer 28 and the inorganic layer 24 are different in size within the range of size variations that occur during manufacturing.
[0037] The reinforcing layer 28 is formed of the same material as the inorganic layer 24. The reinforcing layer 28 is made of an inorganic material. The material forming the reinforcing layer 28 may be the same as the material of the substrate 20, or a different material from that of the substrate 20.
[0038] The reinforcing layer 28 is made of, for example, an insulating ceramic substrate. As with the substrate 20, the material of the reinforcing layer 28 is preferably made of zirconia (ZrO2) or alumina (Al2O3) as the main component of the ceramic material.
[0039] The reinforcing layer 28 may be formed by a lamination method such as sputtering, etc. As a method for forming the reinforcing layer 28, other forming methods can be selected depending on the thickness dimension of the reinforcing layer 28, etc.
[0040] The reinforcing layer 28 has a smaller area than the substrate 20. An edge on one side 50 of the reinforcing layer 28 constitutes a reinforcing layer one end edge 100. An edge on the other side 54 of the reinforcing layer 28 constitutes a reinforcing layer other end edge 102. An edge on one side 60 of the reinforcing layer 28 in the width direction constitutes a reinforcing layer one side edge 104. An edge on the other side 64 of the reinforcing layer 28 constitutes a reinforcing layer other side edge 106.
[0041] of the substrate 20 other side come into contact with Reinforcement layer 28 One edge 100 of the reinforcing layer, which is one side of the substrate 20, is located on a line that overlaps with the boundary line 90 between the covered portion 70 and the exposed portion 34 of the substrate 20 in the thickness direction 108 of the substrate 20 (see FIG. 1). The other edge 102 of the reinforcing layer is located on the other edge 56 of the substrate. One side edge 104 of the reinforcing layer is located on one side edge 62 of the substrate. The other edge 102 of the reinforcing layer is located on the other side edge 66 of the substrate.
[0042] The inorganic layer 24 and the reinforcing layer 28 are arranged so that one end edge 82 (see Figure 2) of the inorganic layer 24 that contacts the surface 22 of the substrate 20 and one end edge 100 (see Figure 3) of the reinforcing layer 28 that contacts the back surface 26 are aligned in the thickness direction 108 of the substrate 20.
[0043] In this embodiment, the inorganic layer 24 and the reinforcing layer 28 have the same shape and approximately the same size, but the present embodiment is not limited to this.
[0044] For example, the dimension from the one reinforcement layer edge 104 to the other reinforcement layer edge 106 of the reinforcement layer 28 is made larger than the dimension from the one inorganic layer edge 86 to the other inorganic layer edge 88 of the inorganic layer 24. The reinforcement layer 28 may be disposed so that the one reinforcement layer edge 104 and the other reinforcement layer edge 106 of the reinforcement layer 28 are located outside the substrate 20.
[0045] The reinforcing layer 28 covers a part of the back surface 26 of the substrate 20. The reinforcing layer 28 covers the back side of the covered portion 70 but does not cover the back side of the exposed portion 34.
[0046] The reinforcing layer 28 is fixed to the substrate 20 by an adhesive layer (not shown) made of a resin material. The adhesive layer is mainly made of, for example, epoxy resin.
[0047] (thin film resistor) 2, the thin-film resistor 30 is a resistor whose resistance value changes depending on the load applied to the inorganic layer 24. The thin-film resistor 30 has a main body 32 sandwiched between the substrate 20 and the inorganic layer 24, and one end 36 and the other end 38 disposed in an exposed portion 34 of the substrate 20 that is not covered by the inorganic layer 24.
[0048] The main body portion 32 of the thin film resistor 30 is composed of the portion sandwiched between the substrate 20 and the inorganic layer 24, and the main body portion 32 of the thin film resistor 30 is composed of the thin film connecting portion 114, a portion of the first thin film extending portion 110, and a portion of the second thin film extending portion 112.
[0049] The thin film resistor 30 is made of, for example, a nichrome (NiCr)-based material or a chromium (Cr)-based material, which reduces the temperature coefficient of resistance (TCR), allowing the load sensor element 10 to accurately detect load even in a high-temperature environment of 50°C or higher.
[0050] The thin-film resistor 30 is a resistive layer formed on the surface 22 of the substrate 20 by vacuum processing such as vapor deposition and sputtering. Sputtering formation methods tend to produce films with uniform characteristics and thickness. Therefore, a uniform resistive layer is formed by vacuum processing such as vapor deposition and sputtering, allowing the load sensor element 10 to detect loads with high accuracy.
[0051] The thin film resistor 30 has a first thin film extension 110 that extends linearly along the one side edge 62 of the substrate. The first thin film extension 110 extends from one side 50 to the other side 54 of the substrate 20. The thin film resistor 30 has a second thin film extension 112 that extends linearly along the other side edge 66 of the substrate. The second thin film extension 112 extends from one side 50 to the other side 54 of the substrate 20.
[0052] The thin-film resistor 30 has a thin-film connecting portion 114 connecting the first thin-film extending portion 110 and the second thin-film extending portion 112. The thin-film connecting portion 114 is disposed on the other side 54 of the substrate 20 and extends linearly along the other edge 56 of the substrate.
[0053] As a result, the main body 32 of the thin-film resistor 30 is formed in a U-shape.
[0054] In this embodiment, the main body 32 is formed in a U-shape, but the present embodiment is not limited to this shape. For example, the main body 32 may be formed in a serpentine shape with repeated folds.
[0055] The first thin film extending portion 110, the second thin film extending portion 112, and the thin film continuous portion 114 are set to have approximately the same width dimension.
[0056] A first widened portion 116 is connected to one side 50 of the first thin film extending portion 110, and the width dimension of the first widened portion 116 increases toward one edge 52 of the substrate. A first rectangular portion 118 having a rectangular shape is connected to the first widened portion 116.
[0057] A second widened portion 120 whose width increases toward one edge 52 of the substrate is connected to one side 50 of the second thin film extending portion 112. A second rectangular portion 122 having a rectangular shape is connected to the second widened portion 120.
[0058] In this thin-film resistor 30, the thin-film continuous portion 114, a part of the first thin-film extending portion 110, and a part of the second thin-film extending portion 112 are covered with the inorganic layer 24 to form the main body portion 32.
[0059] In the thin-film resistor 30, a part of the first thin-film extension 110, the first widened portion 116, and the first rectangular portion 118 form one end portion 36 that is not covered by the inorganic layer 24. In addition, in the thin-film resistor 30, a part of the second thin-film extension 112, the second widened portion 120, and the second rectangular portion 122 form the other end portion 38 that is not covered by the inorganic layer 24.
[0060] A first electrode 40 having, for example, a rectangular shape (including a square shape) is provided on the first rectangular portion 118 of the thin-film resistor 30. The first electrode 40 is electrically connected to the first rectangular portion 118 and is disposed on one side 50 of the substrate 20.
[0061] Furthermore, a second electrode 42 having, for example, a rectangular shape (including a square shape) is provided on the second rectangular portion 122 of the thin-film resistor 30. The second electrode 42 is electrically connected to the second rectangular portion 122 and is disposed on one side 50 of the substrate 20.
[0062] The electrodes 40, 42 are formed of a material such as copper (Cu), silver (Ag), or gold (Au). The electrodes 40, 42 are formed by laminating them on the first rectangular portion 118 of the thin-film resistor 30 and the second rectangular portion 122 of the thin-film resistor 30 by a method such as sputtering or vapor deposition. The first electrode 40 and the second electrode 42 are formed to have dimensions smaller than the first rectangular portion 118 of the thin-film resistor 30 and the second rectangular portion 122 of the thin-film resistor 30, respectively.
[0063] 1, a first lead wire 132 is connected to the first electrode 40 by solder 130. A second lead wire 134 is connected to the second electrode 42 by solder 130.
[0064] Each of the lead wires 132, 134 is made of a material such as a copper (Cu) alloy or an iron (Fe) alloy. Each of the lead wires 132, 134 may be made of, for example, an uncoated conductor wire (a metal wire plated with tin (Sn) or the like), a coated conductor wire covered with a coating, or an enameled conductor wire covered with an insulating layer. Alternatively, a terminal made of a flat lead frame may be used.
[0065] (Action and effect) Next, the effects of the first embodiment will be described.
[0066] The load sensor element 10 of this embodiment is a load sensor element that measures a surface pressure load. The load sensor element 10 includes a substrate 20 and an inorganic layer 24, which is a first layer provided on a front surface 22 of the substrate 20 and covers a portion of the substrate 20. The load sensor element 10 includes a thin-film resistor 30, which is a resistor whose resistance value changes in response to a load received from the inorganic layer 24, provided on the front surface 22. The thin-film resistor 30 has a main body 32 sandwiched between the substrate 20 and the inorganic layer 24, and one end 36 and the other end 38 placed on an exposed portion 34 of the substrate 20 that is not covered by the inorganic layer 24. The load sensor element 10 includes a first electrode 40 and a second electrode 42 electrically connected to the one end 36 and the other end 38 of the thin-film resistor 30, respectively, and a reinforcing layer 28, which is a second layer provided on a back surface 26 of the substrate 20 so as to sandwich the substrate 20 together with the inorganic layer 24. In the load sensor element 10, the inorganic layer 24 and the reinforcing layer 28 are arranged so that one end edge 82 of the inorganic layer 24 in contact with the front surface 22 and one end edge 100 of the reinforcing layer 28 in contact with the back surface 26 are aligned in the thickness direction 108 of the substrate 20.
[0067] In this configuration, a reinforcing layer 28 is provided on the back surface 26 of the substrate 20 of the load sensor element 10. The inorganic layer 24 and the reinforcing layer 28 are arranged such that one end edge 82 of the inorganic layer 24, which contacts the front surface 22 of the substrate 20, and one end edge 100 of the reinforcing layer 28, which contacts the back surface 26, are aligned in the thickness direction 108 of the substrate 20.
[0068] Therefore, the reinforcing layer 28 of the load sensor element 10 contacts the base of the measurement object on which the load sensor element 10 is placed during load measurement, and a gap is formed between the exposed part of the substrate 20 that is not covered by the reinforcing layer 28 and the base.
[0069] In this state, even if the load applied to the load sensor element 10 is also applied to the reinforcing layer 28, causing deformation such as a depression in the base, the edge of the depression caused by the deformation will not push up the substrate 20 as long as the depth of the depression caused by the deformation is equal to or less than the thickness dimension of the reinforcing layer 28. This makes it possible to suppress deformation of the substrate 20 caused by the edge of the depression caused by the deformation pushing up the substrate 20.
[0070] Therefore, it is possible to suppress the concentration of stress on the substrate 20 compared to when the edge of the depression caused by deformation abuts against the substrate 20, deforming the substrate 20 and concentrating stress at the boundary line 90 between the covered portion 70 and the exposed portion 34 of the substrate 20.
[0071] In addition, the inorganic layer 24 and the reinforcing layer 28 are arranged so that one end edge 82 of the inorganic layer 24 that contacts the surface 22 of the substrate 20 and one end edge 100 of the reinforcing layer 28 that contacts the back surface 26 are aligned in the thickness direction 108 of the substrate 20.
[0072] Therefore, compared to when the position where one edge 82 of the inorganic layer contacts the substrate 20 and the position where one edge 100 of the reinforcing layer contacts the substrate 20 are different, stress concentration at the position where one edge 82 of the inorganic layer contacts or the position where one edge 100 of the reinforcing layer contacts can be suppressed.
[0073] Furthermore, compared to the case where stress is repeatedly concentrated on the boundary line 90 of the substrate 20, it is possible to prevent damage to the substrate 20 along the boundary line 90 and breakage of the portion of the thin-film resistor 30 that straddles the boundary line 90. This makes it possible to improve the durability of the load sensor element 10.
[0074] Furthermore, since deformation of the substrate 20 due to stress concentration at the boundary line 90 is suppressed, it becomes possible to accurately and precisely detect only the change in resistance value when the thin-film resistor 30 is compressed by a load.
[0075] In the load sensor element 10 of this embodiment, the inorganic layer 24, which is the first layer, has approximately the same size as the reinforcing layer 28, which is the second layer.
[0076] In this configuration of the load sensor element 10, the inorganic layer 24 and the reinforcing layer 28 are approximately the same size, which simplifies the manufacture of the inorganic layer 24 and the reinforcing layer 28 compared to when the inorganic layer 24 and the reinforcing layer 28 are different sizes.
[0077] Furthermore, compared to when the length dimension from one side edge 104 of the reinforcing layer 28 to the other side edge 106 of the reinforcing layer is made larger than the length dimension from one side edge 86 of the inorganic layer 24 to the other side edge 88 of the inorganic layer, the material cost of the reinforcing layer 28 can be reduced, making it possible to reduce costs.
[0078] In this embodiment, the inorganic layer 24, which is the first layer, and the reinforcing layer 28, which is the second layer, are made of the same material.
[0079] In this configuration, the inorganic layer 24 and the reinforcing layer 28 are formed from the same material, which reduces the cost of procuring materials and enables lower costs compared to when the inorganic layer 24 and the reinforcing layer 28 are formed from different materials.
[0080] Furthermore, the inorganic layer 24 and the reinforcing layer 28 are formed of the same material. Therefore, when a load is applied, the behavior of the inorganic layer 24 on the front surface 22 of the substrate 20 can be made uniform with the behavior of the reinforcing layer 28 on the back surface 26 of the substrate 20.
[0081] Specifically, the inorganic layer 24 and the reinforcing layer 28 are compressed by the same amount when the same load is applied, and return to their original shape when the load is removed. Therefore, the positional relationship between the edges of the inorganic layer 24 and the reinforcing layer 28 (one end edge 82 of the inorganic layer and one end edge 100 of the reinforcing layer, the other end edge 84 of the inorganic layer and the other end edge 102 of the reinforcing layer, one side edge 86 of the inorganic layer and one side edge 104 of the reinforcing layer, and the other side edge 88 of the inorganic layer and the other side edge 106 of the reinforcing layer) does not change. This allows the strength of the load sensor element 10 to be maintained high compared to when the positional relationship between the edges of the inorganic layer 24 and the reinforcing layer 28 changes.
[0082] Second Embodiment A load sensor element 200 according to the second embodiment will be described with reference to Fig. 4. In this embodiment, the same or equivalent parts as those in the first embodiment will be denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted, and only the parts different from the first embodiment will be described.
[0083] 4 is a perspective view of the load sensor element 200 according to the second embodiment as viewed from the front side. The load sensor element 200 according to the second embodiment differs from the first embodiment in the thickness dimension of the reinforcing layer 28.
[0084] In the load sensor element 200 according to this embodiment, the thickness T1 of the reinforcing layer 28, which is the second layer, is larger than the thickness T2 of the inorganic layer 24, which is the first layer.
[0085] The inorganic layer 24 may be formed by a lamination method such as sputtering. By forming the inorganic layer 24 by a lamination method such as sputtering, the thickness dimension T2 of the inorganic layer 24 and the thickness dimension T1 of the reinforcing layer 28 can be easily made different from each other.
[0086] Specifically, the substrate 20, the reinforcing layer 28, and the inorganic layer 24 have the same width W in the width direction, and the width W is, for example, 4 mm or more and 15 mm or less.
[0087] The reinforcing layer 28 and the inorganic layer 24 have the same length L1 in the longitudinal direction, and the length L1 is, for example, 4 mm or more and 15 mm or less. The length L2 of the substrate 20 is, for example, L1 or more and 20 mm or less. The pressure-receiving area formed by the pressure-receiving surface 80 of the inorganic layer 24 is, for example, 60 mm. 2 Over 70mm 2 The following applies.
[0088] The thickness T1 of the reinforcing layer 28 is, for example, 0.1 mm or more and 5.0 mm or less. In this embodiment, the thickness T1 of the reinforcing layer 28 is, for example, 1.0 mm. The thickness T2 of the inorganic layer 24 is, for example, 0.1 mm or more and 5.0 mm or less. In this embodiment, the thickness T2 of the inorganic layer 24 is, for example, 0.3 mm. The thickness T3 of the substrate 20 is, for example, 0.1 mm or more and 5.0 mm or less. In this embodiment, the thickness T3 of the substrate 20 is, for example, 0.3 mm.
[0089] These dimensions are merely examples, and the present embodiment is not limited to these dimensions.
[0090] (Action and effect) Next, the effects of the second embodiment will be described.
[0091] In this embodiment, the same or equivalent parts as those in the first embodiment can also obtain the same effects as those in the first embodiment.
[0092] In the load sensor element 200 of this embodiment, the thickness T1 of the reinforcing layer 28, which is the second layer, is larger than the thickness T2 of the inorganic layer 24, which is the first layer.
[0093] In this configuration, if the deformation of the base of the object to be measured on which the load sensor element 200 is placed is less than the thickness dimension T1 of the reinforcing layer 28, it is possible to suppress deformation of the portion of the thin-film resistor 30 arranged across the boundary line 90 of the substrate 20.
[0094] Therefore, by making the thickness dimension T1 of the reinforcing layer 28 larger than the thickness dimension T2 of the inorganic layer 24, the effect of suppressing deformation of the substrate 20 can be enhanced.
[0095] (Third embodiment) A load sensor element 300 according to the third embodiment will be described with reference to Fig. 5. In this embodiment, the same or equivalent parts as those in the first embodiment will be denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted, and only the parts different from the first embodiment will be described.
[0096] 5 is a perspective view of the load sensor element 300 according to the third embodiment, seen from the front side. The load sensor element 300 according to the third embodiment has different structures of the inorganic layer 24 and the reinforcing layer 28 compared to the first embodiment.
[0097] The load sensor element 300 according to this embodiment has an outer layer with a lower elastic modulus than the substrate 20 on at least one of the outer surface (pressure-receiving surface 80) of the inorganic layer 24 as the first layer and the outer surface of the reinforcing layer 28 as the second layer.
[0098] Here, the outer surface refers to the surface facing outward, that is, the surface opposite to the substrate 20.
[0099] The modulus of elasticity is the ratio of the increment of stress to the increment of strain, and is expressed as "modulus of elasticity = (stress) / (strain)." A material with a higher modulus of elasticity is harder, and a material with a lower modulus of elasticity is softer.
[0100] In the load sensor element 300 of this embodiment, a first outer layer 310 is formed over the entire outer surface of the inorganic layer 24 on the side opposite to the substrate 20. The first outer layer 310 is made of a resin film formed from a synthetic resin.
[0101] As the synthetic resin forming the first outer layer 310, a resin material having a lower modulus of elasticity than the ceramic material forming the substrate 20, such as polyimide or PET, is used.
[0102] A second outer layer 312 is formed over the entire outer surface of the reinforcing layer 28 on the side opposite to the substrate 20. The second outer layer 312 is made of a resin film made of a synthetic resin. The synthetic resin used to form the second outer layer 312 is a resin material such as polyimide or PET, which has a lower elastic modulus than the ceramic material that forms the substrate 20.
[0103] It is desirable that the first outer layer 310 and the second outer layer 312 are made of the same material, but they may be made of different materials.
[0104] (Action and effect) Next, the effects of the third embodiment will be described.
[0105] In this embodiment, the same or equivalent parts as those in the first embodiment can also obtain the same effects as those in the first embodiment.
[0106] In this embodiment, at least one of the outer surface of the inorganic layer 24 as the first layer and the outer surface of the reinforcing layer 28 as the second layer has a first outer layer 310 or a second outer layer 312 having a modulus of elasticity smaller than that of the substrate 20 .
[0107] Specifically, in the load sensor element 300 of this embodiment, a first outer layer 310 is formed on the outer surface of the inorganic layer 24, and a second outer layer 312 is formed on the outer surface of the reinforcing layer .
[0108] In this configuration, the output characteristics of the load sensor element 300 can be improved.
[0109] This effect will be specifically described.
[0110] The substrate 20, inorganic layer 24, and reinforcing layer 28, which are made of ceramics, are prone to warping and undulation during the manufacturing process. Furthermore, minute irregularities may be formed on the surface 22 of the substrate 20, the inner surface of the inorganic layer 24, and the inner surface of the reinforcing layer 28.
[0111] For example, when a plate-shaped inorganic layer 24 is placed on the surface 22 of the substrate 20 and a load is applied to the thin-film resistor 30 on the substrate 20, a large force is applied to the portion of the thin-film resistor 30 located in the convex portion of the surface 22. Furthermore, a smaller force is applied to the portion of the thin-film resistor 30 located in the concave portion of the surface 22 than to the convex portion.
[0112] When the load applied to the thin film resistor 30 is released, the resistance value returns quickly in the areas of the thin film resistor 30 where a small force was applied, but the return of the resistance value is delayed in the areas where a large force was applied.
[0113] As a result, the stress-resistance response behavior is not the same in the load application process and the load release process, and hysteresis tends to become large.
[0114] Therefore, in the load sensor element 300 of this embodiment, a first outer layer 310 having a lower elastic modulus than the substrate 20 is formed on the outer surface of the inorganic layer 24, and a second outer layer 312 having a lower elastic modulus than the substrate 20 is formed on the outer surface of the reinforcing layer 28.
[0115] As a result, when a load is applied to the inorganic layer 24, the first outer layer 310, which has a smaller elastic modulus than the substrate 20, deforms significantly at the convex portions that receive a large reaction force and functions as a buffer material, thereby making it possible to uniformly distribute the load applied to the thin-film resistor 30 on the substrate 20. This makes it possible to improve the output characteristics of the load sensor element 300.
[0116] In this embodiment, the first outer layer 310 is provided on the inorganic layer 24, and the second outer layer 312 is provided on the reinforcing layer 28. However, this embodiment is not limited to this. The above-described effects can be obtained by forming either the outer layer 310 or the outer layer 312 on at least one of the outer surfaces of the inorganic layer 24 and the reinforcing layer 28.
[0117] (Fourth embodiment) A load sensor element 400 according to the fourth embodiment will be described with reference to Fig. 6. In this embodiment, the same or equivalent parts as those in the first embodiment will be denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted, and only the parts different from the first embodiment will be described.
[0118] 6 is a perspective view of a load sensor element 400 according to the fourth embodiment, viewed from the front side. The load sensor element 400 according to the fourth embodiment differs from the first embodiment in the arrangement of the first electrode 40 and the second electrode 42 provided on the thin-film resistor 30.
[0119] (substrate) The substrate 410 according to this embodiment is formed in a horizontally long rectangular shape.
[0120] The surface 22 of the substrate 410 has a covered portion 70 that is covered with the inorganic layer 24 , and a first exposed portion 412 and a second exposed portion 414 that are not covered with the inorganic layer 24 .
[0121] The first exposed portion 412 is formed on the substrate one side edge 62 side of the substrate 410. A first boundary line 416 is formed between the covering portion 70 and the first exposed portion 412. The second exposed portion 414 is formed on the substrate other side edge 66 side of the substrate 410. A second boundary line 418 is formed between the covering portion 70 and the second exposed portion 414.
[0122] (Inorganic layer) One edge 82 of the inorganic layer 24 is located on one edge 52 of the substrate 410. The other edge 84 of the inorganic layer is located on the other edge 56 of the substrate (not shown). One side edge 86 of the inorganic layer is located on a first boundary line 416 of the substrate 410. The other side edge 88 of the inorganic layer is located on a second boundary line 418 of the substrate 410.
[0123] The inorganic layer 24 covers the main body 32 (not shown) of the thin-film resistor 30 provided on the substrate 410 , but does not cover one end 36 or the other end 38 of the thin-film resistor 30 .
[0124] (reinforcement layer) One reinforcing layer edge 100 of the reinforcing layer 28 is located on a line overlapping one substrate edge 52 of the substrate 410 in the thickness direction 108. The other reinforcing layer edge 102 (not shown) is located on a line overlapping the other substrate edge 56 (not shown) in the thickness direction 108. One reinforcing layer side edge 104 is located on a line overlapping a first boundary line 416 of the substrate 410 in the thickness direction 108 of the substrate 410. The other reinforcing layer side edge 106 is located on a line overlapping a second boundary line 418 of the substrate 410 in the thickness direction 108 of the substrate 410.
[0125] The inorganic layer 24 and the reinforcing layer 28 are arranged so that one inorganic layer side edge 86 of the inorganic layer 24 in contact with the front surface 22 of the substrate 410 and one reinforcing layer side edge 104 of the reinforcing layer 28 in contact with the back surface 26 are aligned in the thickness direction 108 of the substrate 410. Furthermore, the inorganic layer 24 and the reinforcing layer 28 are arranged so that one inorganic layer edge 82 of the inorganic layer 24 in contact with the front surface 22 of the substrate 410 and one reinforcing layer edge 100 (not shown) of the reinforcing layer 28 in contact with the back surface 26 are aligned in the thickness direction 108 of the substrate 410.
[0126] The reinforcing layer 28 covers a part of the back surface 26 of the substrate 410. The reinforcing layer 28 covers the back side of the covering portion 70, but does not cover the back sides of the first exposed portion 412 and the second exposed portion 414.
[0127] (thin film resistor) The thin-film resistor 30 has a body portion 32 (not shown) sandwiched between the substrate 410 and the inorganic layer 24, and one end portion 36 disposed in a first exposed portion 412 of the substrate 410 that is not covered by the inorganic layer 24. The thin-film resistor 30 has another end portion 38 disposed in a second exposed portion 414 of the substrate 410 that is not covered by the inorganic layer 24.
[0128] The main body 32 of the thin-film resistor 30 is not shown in FIG. 6 because it is covered with the inorganic layer 24.
[0129] In the thin-film resistor 30, the first widened portion 116 and the first rectangular portion 118 form one end 36 that is not covered by the inorganic layer 24. In addition, in the thin-film resistor 30, the second widened portion 120 and the second rectangular portion 122 form the other end 38 that is not covered by the inorganic layer 24.
[0130] A rectangular first electrode 40 is provided on the first rectangular portion 118 of the thin-film resistor 30. The first electrode 40 is electrically connected to the first rectangular portion 118 and is disposed on the side of one side edge 62 of the substrate.
[0131] A rectangular second electrode 42 is provided on the second rectangular portion 122 of the thin-film resistor 30. The second electrode 42 is electrically connected to the second rectangular portion 122 and is disposed on the other-side edge 66 side of the substrate.
[0132] A first lead wire 132 is connected to the first electrode 40 by solder 130. The first lead wire 132 extends along one side edge 86 of the inorganic layer 24.
[0133] A second lead wire 134 is connected to the second electrode 42 by solder 130. The second lead wire 134 extends along the other side edge 88 of the inorganic layer 24.
[0134] (Action and effect) Next, the effects of the fourth embodiment will be described.
[0135] In this embodiment, the same or equivalent parts as those in the first embodiment can also obtain the same effects as those in the first embodiment.
[0136] Moreover, in the load sensor element 400 of this embodiment, the exposed portion has a first exposed portion 412 formed on one side portion 420 of the substrate 410 and a second exposed portion 414 formed on the other side portion 422 of the substrate 410. One end portion 36, which is one end of the thin-film resistor 30, is disposed in the first exposed portion 412, and the other end portion 38, which is the other end of the thin-film resistor 30, is disposed in the second exposed portion 414. The pair of electrodes provided on the thin-film resistor 30 includes a first electrode 40 provided on the one end portion 36, which is one end, and a second electrode 42 provided on the other end portion 38, which is the other end.
[0137] In this configuration, when the load sensor element 400 is sandwiched between the object to be measured, a gap equal to the thickness of the inorganic layer 24 is formed between the pressure surface of the object to be measured that contacts the pressure-receiving surface 80 of the inorganic layer 24 and the surface 22 of the substrate 410 on which each electrode 40, 42 is provided.
[0138] Therefore, compared to when the substrate 410 of the load sensor element 400 is close to the pressure surface to be measured, it is possible to protect the joints of each electrode 40, 42 and each lead wire 132, 134, and each lead wire 132, 134 extending from each electrode 40, 42, from the pressure surface.
[0139] Furthermore, since contact between the joint and each lead wire 132, 134 and the pressure application surface can be suppressed, it is possible to prevent problems such as output short circuits that may occur if the pressure application surface is made of a conductor such as metal.
[0140] Furthermore, interference between the joints and the lead wires 132, 134 and the pressure surface can be suppressed without moving the electrodes 40, 42 away from the inorganic layer 24, thereby enabling miniaturization of the load sensor element 400. Furthermore, restrictions on the placement of the electrodes 40, 42 are relaxed, increasing design freedom.
[0141] In this embodiment, the case where the tip of the first lead wire 132 is soldered to the first electrode 40 and the tip of the second lead wire 134 is soldered to the second electrode 42 has been described, but this embodiment is not limited to this.
[0142] For example, a flat terminal that sandwiches the corresponding electrode 40, 42 together with the substrate 410 may be provided at the tip of each lead wire 132, 134. In this way, by sandwiching the corresponding electrode 40, 42 together with the substrate 410 using the flat terminal, each electrode 40, 42 and each lead wire 132, 134 can be electrically connected.
[0143] In this case, the height of the load sensor element 400 to which the lead wires 132 and 134 are attached can be reduced.
[0144] Fifth Embodiment A load sensor element 500 according to the fifth embodiment will be described with reference to Fig. 7 to Fig. 10. In this embodiment, the same or equivalent parts as those in the first embodiment will be denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted, and only the parts different from the first embodiment will be described.
[0145] Fig. 7 is a perspective view of the load sensor element 500 according to the fifth embodiment as seen from the front side. Fig. 8 is a diagram showing the load sensor element 500 according to the fifth embodiment, and is a plan view showing the load sensor element 500 with the leads removed as seen from the front side. Fig. 9 is a diagram showing the load sensor element 500 according to the first embodiment, and is a plan view showing the load sensor element 500 with the leads removed as seen from the back side.
[0146] The load sensor element 500 according to the fifth embodiment is different from the first embodiment in the number of resistors provided on the substrate 20.
[0147] As shown in FIG. 8, a first resistor 506 having a third electrode 502 and a fourth electrode 504 at its end portions is provided on a surface 22, which is one surface of a substrate 20 of a load sensor element 500.
[0148] As shown in FIG. 9, a second resistor 514 having a fifth electrode 510 and a sixth electrode 512 at its ends, and a third resistor 524 having a seventh electrode 520 and an eighth electrode 522 at its ends are provided on the rear surface 26, which is the other surface of the substrate 20.
[0149] (first resistor) 8, the first resistor 506 is separate from the thin-film resistor 30 and is disposed in the exposed portion 34 of the substrate 20. The first resistor 506 is disposed between one end 36 and the other end 38 of the thin-film resistor 30.
[0150] The first resistor 506 is formed of the same material as the thin-film resistor 30. The first resistor 506 is also formed on the substrate 20 by the same method as the thin-film resistor 30.
[0151] The first resistor 506 has a first surface extension 530 and a second surface extension 532 that extend linearly from one side 50 to the other side 54 within the exposed portion 34 of the substrate 20. The first surface extension 530 and the second surface extension 532 are spaced apart from each other.
[0152] The first surface extending portion 530 is disposed at a position closer to one end 36 of the thin-film resistor 30 than the second surface extending portion 532. The second surface extending portion 532 is disposed at a position closer to the other end 38 of the thin-film resistor 30 than the first surface extending portion 530.
[0153] The first resistor 506 has a front-side connecting portion 534 connecting the other side 54 of the first front-side extending portion 530 and the other side 54 of the second front-side extending portion 532. The front-side connecting portion 534 extends linearly along the boundary line 90 between the covered portion 70 and the exposed portion 34. This allows the first resistor 506 to be formed in a U-shape.
[0154] A rectangular (including square) third rectangular portion 536 is connected to the end of one side 50 of the first front extension portion 530. A rectangular (including square) fourth rectangular portion 538 is connected to the end of one side 50 of the second front extension portion 532.
[0155] A rectangular (including square) third electrode 502 is provided on the third rectangular portion 536 of the first resistor 506. The third electrode 502 is electrically connected to the third rectangular portion 536.
[0156] A rectangular fourth electrode 504 is provided on the fourth rectangular portion 538 of the first resistor 506. The fourth electrode 504 is electrically connected to the fourth rectangular portion 538.
[0157] The length from the first surface extension portion 530 to the second surface extension portion 532 of the first resistor 506 is shorter than the length from the first thin film extension portion 110 to the second thin film extension portion 112 of the thin film resistor 30. In addition, the width dimension of the region from the first surface extension portion 530 to the second surface extension portion 532 of the first resistor 506 is narrower than the width dimension of the region from the first thin film extension portion 110 to the second thin film extension portion 112 of the thin film resistor 30.
[0158] As a result, the first resistor 506 and the thin-film resistor 30 are set to have approximately the same resistance value.
[0159] (Second resistor) 9, the second resistor 514 is disposed on the other surface, that is, the back surface 26, of the substrate 20. The second resistor 514 behaves in the same manner as the thin-film resistor 30.
[0160] "Show the same behavior" means that the thin-film resistor 30 and the second resistor 514 have approximately the same temperature coefficient of resistance, and the change in resistance value of the thin-film resistor 30 and the change in resistance value of the second resistor 514 when deformed by the same load are approximately the same.
[0161] The term "the temperature coefficients of resistance are substantially the same" means that the difference between the temperature coefficient of resistance of the thin-film resistor 30 and the temperature coefficient of resistance of the second resistor 514 is within a predetermined first range.
[0162] The first range is, for example, 100 ppm / K.
[0163] The resistance change being approximately the same means that the difference between the resistance change occurring in the thin-film resistor 30 and the resistance change occurring in the second resistor 514 before and after applying a predetermined identical load to the thin-film resistor 30 and the second resistor 514 is within a predetermined second range.
[0164] An example of the predetermined uniform load is 10 kN. An example of the second range is 100 ppm.
[0165] The second resistor 514 is formed of the same material as the thin-film resistor 30. The second resistor 514 is also formed on the substrate 20 by the same method as the thin-film resistor 30.
[0166] The second resistor 514 is disposed on the rear side of the position where the thin film resistor 30 is disposed. The second resistor 514 is formed in substantially the same shape as the thin film resistor 30.
[0167] As a result, the second resistor 514 is disposed at a position overlapping the thin-film resistor 30 in the thickness direction 108 of the substrate 20. The second resistor 514 is set to have substantially the same resistance value as the thin-film resistor 30.
[0168] Here, when the second resistor 514 overlaps with the thin-film resistor 30, this does not exclude the possibility that a non-overlapping area will be formed at part of the outer edge when the second resistor 514 is overlapped with the thin-film resistor 30 in the thickness direction 108 of the substrate 20.
[0169] The second resistor 514 has a first back extension portion 540 arranged at a position overlapping the first thin film extension portion 110 of the thin film resistor 30 in the thickness direction 108 of the substrate 20, and a second back extension portion 542 arranged at a position overlapping the second thin film extension portion 126. The second resistor 514 also has a back connection portion 544 arranged at a position overlapping the thin film connection portion 114 of the thin film resistor 30.
[0170] The second resistor 514 has a first back widened portion 546 arranged in a position overlapping with the first widened portion 116 in the thickness direction 108 of the substrate 20, and a second back widened portion 548 arranged in a position overlapping with the second widened portion 120 of the thin-film resistor 30.
[0171] The second resistor 514 has a fifth rectangular portion 550 arranged in a position overlapping the first rectangular portion 118 in the thickness direction 108 of the substrate 20, and a sixth rectangular portion 552 arranged in a position overlapping the second rectangular portion 122 of the thin-film resistor 30.
[0172] A rectangular fifth electrode 510 is provided on a fifth rectangular portion 550 of the second resistor 514. The fifth electrode 510 is electrically connected to the fifth rectangular portion 550. In addition, a rectangular sixth electrode 512 is provided on a sixth rectangular portion 552 of the second resistor 514. The sixth electrode 512 is electrically connected to the sixth rectangular portion 552.
[0173] A portion of the first back extension portion 540, the first back widening portion 546, and the fifth rectangular portion 550 constitute one back end portion 554 of the second resistor 514. A portion of the second back extension portion 542, the second back widening portion 548, and the sixth rectangular portion 552 constitute the other back end portion 556 of the second resistor 514.
[0174] (Third resistor) The third resistor 524 is provided independently from the second resistor 514. The third resistor 524 exhibits the same behavior as the first resistor 506.
[0175] The expression "showing the same behavior" means that the third resistor 524 and the first resistor 506 have substantially the same temperature coefficient of resistance.
[0176] The term "the temperature coefficients of resistance are substantially the same" means that the difference between the temperature coefficient of resistance of the third resistor 524 and the temperature coefficient of resistance of the first resistor 506 is within a third predetermined range.
[0177] The third range is, for example, 100 ppm / K.
[0178] The third resistor 524 is formed of the same material as the first resistor 506. The third resistor 524 is also formed on the substrate by the same method as the first resistor 506.
[0179] The third resistor 524 is disposed on the rear side of the position where the first resistor 506 is disposed. The third resistor 524 is formed in substantially the same shape as the first resistor 506.
[0180] As a result, the third resistor 524 is disposed at a position overlapping the first resistor 506 in the thickness direction 108 of the substrate 20. The third resistor 524 is set to have substantially the same resistance value as the first resistor 506.
[0181] Here, when the third resistor 524 overlaps with the first resistor 506, it does not mean that when the third resistor 524 is overlapped with the first resistor 506 in the thickness direction 108 of the substrate 20, a non-overlapping area may be generated in part of the outer edge.
[0182] The third resistor 524 has a first small back extension 551 arranged at a position overlapping the first front extension 530 of the first resistor 506 in the thickness direction 108 of the substrate 20, and a second small back extension 553 arranged at a position overlapping the second front extension 532. The third resistor 524 also has a small back connection 555 arranged at a position overlapping the front connection 534 of the first resistor 506.
[0183] The third resistor 524 has a seventh rectangular portion 557 arranged in a position overlapping the third rectangular portion 536 in the thickness direction 108 of the substrate 20, and an eighth rectangular portion 558 arranged in a position overlapping the fourth rectangular portion 538 of the first resistor 506.
[0184] A rectangular seventh electrode 520 is provided on a seventh rectangular portion 557 of the third resistor 524. The seventh electrode 520 is electrically connected to the seventh rectangular portion 557. Furthermore, a rectangular eighth electrode 522 is provided on an eighth rectangular portion 558 of the third resistor 524. The eighth electrode 522 is electrically connected to the eighth rectangular portion 558.
[0185] 7, a third lead wire 560 is connected to the third electrode 502 by solder 130. A fourth lead wire 562 is connected to the fourth electrode 504 by solder 130.
[0186] Similarly, a fifth lead wire 564 is connected to the fifth electrode 510 by solder. A sixth lead wire 566 is connected to the sixth electrode 512 by solder. A seventh lead wire 568 is connected to the seventh electrode 520 by solder. An eighth lead wire 570 is connected to the eighth electrode 522 by solder.
[0187] (Action and effect) Next, the effects of the fifth embodiment will be described.
[0188] In this embodiment, the same or equivalent parts as those in the first embodiment can also obtain the same effects as those in the first embodiment.
[0189] In the load sensor element 500 of this embodiment, a first resistor 506 having a third electrode 502 and a fourth electrode 504 at its ends is provided on the front surface 22, which is one surface of the substrate 20. A second resistor 514 having a fifth electrode 510 and a sixth electrode 512 at its ends, and a third resistor 524 having a seventh electrode 520 and an eighth electrode 522 at its ends are provided on the back surface 26, which is the other surface of the substrate 20.
[0190] In this configuration, the load sensor element 500 includes a thin-film resistor 30 and a first resistor 506 provided on the front surface 22 of the substrate 20. The load sensor element 500 also includes a second resistor 514 and a third resistor 524 provided on the back surface 26 of the substrate 20.
[0191] Therefore, a bridge circuit can be formed by the four resistors included in the load sensor element 500. Furthermore, by performing measurements using the output from the bridge circuit, highly accurate measurements become possible.
[0192] Fig. 10 is a circuit diagram showing an example of use of the load sensor element 500 according to the fifth embodiment. Fig. 10 shows a bridge circuit 580 formed by connecting the resistors of the load sensor element 500.
[0193] It should be noted that there are many other types of bridge circuit 580. Fig. 10 shows a Wheatstone bridge circuit as an example of bridge circuit 580.
[0194] This bridge circuit 580 is provided on the side where the thin-film resistor 30 that receives the load and the second resistor 514 face each other. Also, the bridge circuit 580 is provided on the side where the first resistor 506 that does not receive the load and the third resistor 524 face each other.
[0195] The first electrode 40 of the thin-film resistor 30 and the third electrode 502 of the first resistor 506 are connected to a positive electrode 584 of a power source 582. The sixth electrode 512 of the second resistor 514 and the eighth electrode 522 of the third resistor 524 are connected to a negative electrode 586 of the power source 582.
[0196] The second electrode 42 of the thin-film resistor 30 and the seventh electrode 520 of the third resistor 524 are connected to a first terminal 592 of a voltage measuring device 590. The fourth electrode 504 of the first resistor 506 and the fifth electrode 510 of the second resistor 514 are connected to a second terminal 594 of the voltage measuring device 590.
[0197] In this way, by forming a bridge circuit 580 using the resistors 30, 506, 514, and 524 of the load sensor element 500, it is possible to increase the change in output voltage compared to when only the change in the resistance value of the thin-film resistor 30 is used as a measurement value. Therefore, even if the change in the resistance value of a single thin-film resistor 30 is small, the output can be increased (amplified), enabling more accurate load detection and improving measurement accuracy.
[0198] Moreover, this bridge circuit 580 is composed of four resistors provided on the substrate 20 of the load sensor element 500. Therefore, compared to a case where a bridge circuit is composed of three external resistors in addition to the thin-film resistor 30 of the load sensor element 500, the bridge circuit 580 can be composed only with the load sensor element 500. Therefore, the space occupied by the bridge circuit 580 can be reduced, and the measuring device composed of the bridge circuit 580 can be made smaller.
[0199] Furthermore, compared to four resistors prepared individually, four resistors formed on the same substrate 20 have less variation in characteristics such as resistance value of each resistor. Therefore, by configuring the bridge circuit 580 with four resistors formed on the substrate 20, it is possible to improve the accuracy of the output signal.
[0200] In this embodiment, the thin-film resistor 30 on the front surface 22 of the substrate 20 and the second resistor 514 on the back surface 26 of the substrate 20 have the same shape and are arranged at positions overlapping in the thickness direction 108 of the substrate 20. The first resistor 506 on the front surface 22 of the substrate 20 and the third resistor 524 on the back surface 26 of the substrate 20 have the same shape and are arranged at positions overlapping in the thickness direction 108 of the substrate 20.
[0201] This allows the resistors to be formed in the same state on the front surface 22 and the back surface 26 of the substrate 20. Therefore, compared to a case where the resistors are formed in different states on the front surface 22 and the back surface 26 of the substrate 20, it is possible to suppress unevenness in the stress generated in the substrate 20.
[0202] The inorganic layer 24 and the reinforcing layer 28 are made of the same material.
[0203] Therefore, it is possible to match the pressure conditions under which the inorganic layer 24 applies pressure to the thin-film resistor 30 with the pressure conditions under which the reinforcing layer 28 applies pressure to the second resistor 514. This makes it possible to improve the accuracy of the measurement results obtained from the output of the bridge circuit 580.
[0204] In this embodiment, the bridge circuit 580 is formed by the thin-film resistor 30 and the first resistor 506 provided on the front surface 22 of the substrate 20, and the second resistor 514 and the third resistor 524 provided on the back surface 26, but this embodiment is not limited to this.
[0205] The four resistors that make up the bridge circuit 580 may be provided on the front surface 22, or the three resistors excluding the thin film resistor 30 may be provided on the back surface 26, and this embodiment does not exclude these configurations.
[0206] (Sixth embodiment) A load sensor element 600 according to the sixth embodiment will be described with reference to Fig. 11. In this embodiment, the same or equivalent parts as those in the first embodiment will be denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted, and only the parts different from the first embodiment will be described.
[0207] 11 is a perspective view of a load sensor element 600 according to the sixth embodiment as viewed from the back surface side. The load sensor element 600 according to the sixth embodiment differs from the first embodiment in the state of the back surface 26 of the substrate 20.
[0208] In this load sensor element 600, at least one of the edge of the inorganic layer 24, which is the first layer, and the edge of the reinforcing layer 602, which is the second layer, contacts a convex portion 604 provided on the substrate 20. In the load sensor element 600 according to this embodiment, the edge of the reinforcing layer 602 contacts the convex portion 604 provided on the substrate 20.
[0209] More specifically, a convex portion 604 is formed on the rear surface 26 of the substrate 20. The convex portion 604 is formed as a ridge, and the cross section of the convex portion 604 is substantially rectangular. The convex portion 604 has substantially the same thickness as the reinforcing layer 602.
[0210] The protrusion 604 is provided on the other side 54 of the substrate 20. The protrusion 604 extends along the other edge 56 of the substrate. The protrusion 604 has a length that extends from the one side edge 62 (not shown) of the substrate to the other side edge 66 of the substrate.
[0211] The protrusions 604 are formed from, for example, a synthetic resin. The protrusions 604 are formed at accurate positions on the substrate 20 by, for example, a printing technique. An example of the printing technique is screen printing.
[0212] The other reinforcing layer edge 102 of the reinforcing layer 602 is in contact with the entire convex edge 610 on one side 50 of the convex portion 604. The reinforcing layer 602 is positioned by this convex portion 604. As a result, the reinforcing layer one edge 100 of the reinforcing layer 602 is positioned on the boundary line 90, and the reinforcing layer one edge 100 and the inorganic layer one edge 82 of the inorganic layer 24 overlap in the thickness direction 108.
[0213] The reinforcing layer 602 has a length L3 that is smaller than the length L4 of the protrusions 604 of the reinforcing layer 28 of the first embodiment.
[0214] In this embodiment, a case has been described in which the convex portion 604 is provided on the rear surface 26 of the substrate 20 and the other end edge 102 of the reinforcing layer 602 abuts against the one end edge 610 of the convex portion 604, but the embodiment is not limited to this. For example, a convex portion may be provided on the front surface 22 of the substrate 20 and the edge of the inorganic layer 24 may abut against the convex portion.
[0215] Alternatively, the other end edge 102 of the reinforcing layer 602 may be in contact with the convex portion 604 , and the edge of the inorganic layer 24 may be in contact with the convex portion formed on the surface 22 .
[0216] (Action and effect) Next, the effects of the sixth embodiment will be described.
[0217] In the load sensor element 600 of this embodiment, the same or equivalent parts as those in the first embodiment can also achieve the same effects as those in the first embodiment.
[0218] In the load sensor element 600 of this embodiment, at least one of the edge of the inorganic layer 24 as the first layer and the edge of the reinforcing layer 602 as the second layer contacts a convex portion 604 provided on the substrate 20 .
[0219] In the load sensor element 600 of this configuration, for example, during manufacturing, the other end edge 102 of the reinforcing layer 602 can be aligned with the convex portion 604 formed in advance on the substrate 20, and the reinforcing layer 602 can be fixed to the substrate 20, so that one end edge 100 of the reinforcing layer can be positioned on the boundary line 90.
[0220] Specifically, one end edge 82 of inorganic layer 24 is aligned and fixed on boundary line 90, and then reinforcing layer 602 is fixed with the other end edge 102 of reinforcing layer 602 abutting against convex portion 604. This makes it possible to position reinforcing layer 602 so that one end edge 100 of reinforcing layer 602 and one end edge 82 of inorganic layer 24 overlap in thickness direction 108.
[0221] Therefore, compared to the case where accurate alignment is required when fixing the reinforcing layer 602 to the substrate 20, it is possible to more easily align the reinforcing layer 602 with respect to the inorganic layer 24.
[0222] Although the present embodiment has been described above, the above embodiment merely shows some of the application examples of the present invention, and is not intended to limit the technical scope of the present invention to the specific configurations of the above embodiment. [Explanation of symbols]
[0223] 10, 200, 300, 400, 500, 600 Load sensor element 20,410 board 22 Surface 24 Inorganic layer 26 Back side 28,602 Reinforcement layer 30 Thin film resistor 32 Main body 34, 70 Exposed part 36, 420 One end 38, 422 Other end 40 First electrode 42 Second electrode 50 one side 52 One edge of the board 54 Other side 80 Pressure-receiving surface 82 Inorganic layer one edge 90 Borderline 100 One edge of reinforcement layer 108 Thickness direction 412 First exposed part 414 Second exposed part 416 First Boundary Line 418 Second boundary line 502 Third electrode 504 Fourth electrode 506 First resistor 510 Fifth electrode 512 Sixth electrode 514 Second resistor 520 Seventh electrode 522 Eighth electrode 524 Third resistor 554 Back end 556 Back other end 604 Convex part T1, T2 thickness dimensions
Claims
1. A load sensor element for measuring a surface pressure load, A substrate; a first layer provided on one surface of the substrate and covering a portion of the substrate; a thin-film resistor whose resistance value changes depending on the load received from the first layer, the thin-film resistor being provided on the one surface of the substrate and having a main body portion sandwiched between the substrate and the first layer and both ends disposed on exposed portions of the substrate that are not covered by the first layer; a pair of electrodes electrically connected to both ends of the thin film resistor; a second layer whose entire inner surface is provided in contact with the other surface of the substrate so as to sandwich the substrate together with the first layer, or whose entire inner surface is provided on the other surface of the substrate via only an adhesive layer; a first layer edge, which is one side of the first layer that contacts the one surface of the substrate, forms a boundary line between a covered portion covered with the first layer and the exposed portion, a boundary line between a portion covered with the second layer and a portion not provided with the second layer is formed on the other surface of the substrate by one edge of the second layer, which is one side of the second layer that contacts the other surface of the substrate, the first layer and the second layer are arranged so that the two boundary lines are aligned in the thickness direction of the substrate; Load sensor element.
2. The load sensor element according to claim 1, The first layer is approximately the same size as the second layer. Load sensor element.
3. The load sensor element according to claim 1 or 2, The thickness dimension of the second layer is greater than the thickness dimension of the first layer. Load sensor element.
4. The load sensor element according to any one of claims 1 to 3, an outer layer having a modulus of elasticity lower than that of the substrate on at least one of an outer surface of the first layer and an outer surface of the second layer; Load sensor element.
5. The load sensor element according to any one of claims 1 to 4, the exposed portion includes a first exposed portion formed on one side of the substrate and a second exposed portion formed on the other side of the substrate, one end of the thin-film resistor is disposed in the first exposed portion, and the other end of the thin-film resistor is disposed in the second exposed portion; The pair of electrodes includes a first electrode provided at the one end and a second electrode provided at the other end. Load sensor element.
6. The load sensor element according to any one of claims 1 to 5, a first resistor having a third electrode and a fourth electrode at its end is provided on the one surface of the substrate; a second resistor having a fifth electrode and a sixth electrode at an end thereof, and a third resistor having a seventh electrode and an eighth electrode at an end thereof, provided on the other surface; Load sensor element.
7. The load sensor element according to any one of claims 1 to 6, The first layer and the second layer are formed of the same material. Load sensor element.
8. The load sensor element according to any one of claims 1 to 7, At least one of an edge of the first layer and an edge of the second layer is in contact with a protrusion provided on the substrate. Load sensor element.
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