Shear force detector

Abstract

To prevent wrong detection of a shear force acting in a direction in which the shear force does not act.SOLUTION: A shear force sensor cell 10 comprises: a first electrode 11 and a second electrode 12 arranged opposite to each other with a first gap G1 in a Y direction, first wiring 31a connected to the first electrode 11, and second wiring 31b connected to the second electrode 12, in a first conductive layer; a third electrode 14 arranged overlapping the first gap G1, the first electrode 11, and the second electrode 12 in a second conductive layer; an insulating elastic body elastically deformable and arranged between the first conductive layer and the second conductive layer; and a ground electrode 15 which is arranged, between the first conductive layer and the second conductive layer, in a portion where a portion electrically connected to the third electrode 14 and the first wiring 31a overlap each other and in a portion where a portion electrically connected to the third electrode 14 and the second wiring 31b overlap each other, and is connected to a ground potential.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a shear force detection device that measures a shear force based on a change in capacitance. [Background technology]

[0002] Conventionally, there is known a shear force detection device that detects shear force and pressing force using changes in capacitance. This shear force detection device includes a first electrode and a second electrode that are arranged in a first conductive layer facing each other with a gap in a predetermined direction, a third electrode that is arranged in a second conductive layer facing the first conductive layer, overlaps with the gap, the first electrode, and the second electrode, and generates a first capacitance between the first electrode and a second capacitance between the second electrode, and an elastically deformable insulating elastic body that is arranged between the first conductive layer and the second conductive layer (for example, see Patent Document 1).

[0003] In the above shear force detection device, when a shear force is applied in the predetermined direction, the insulating elastic body is elastically deformed in the predetermined direction, changing the positional relationship between the first electrode, the second electrode, and the third electrode in the predetermined direction, and changing the area of ​​the region where the first electrode and the third electrode overlap and the area where the second electrode and the third electrode overlap. This change in area is detected as a change in the first capacitance formed by the first electrode and the third electrode and the second capacitance formed by the second electrode and the third electrode. In other words, the above shear force detection device can detect the application of a shear force in the predetermined direction as a change in the first capacitance and the second capacitance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6280579 Summary of the Invention [Problem to be solved by the invention]

[0005] In the shear force detection device having the above configuration, in addition to the first electrode, the second electrode, and the third electrode, a wiring section for connecting these electrodes to an external device (e.g., a capacitance measuring device) is provided. In conventional shear force detection devices, the wiring section and the electrode facing it overlap each other to form a capacitance component. In conventional shear force detection devices, the presence of this capacitance component can cause erroneous detection of shear force.

[0006] For example, when force is applied to the overlapping portion between the wiring part connected to the first electrode and the third electrode, the thickness of the insulating elastic body in this portion changes (becomes smaller), and the capacitance of the capacitance component formed between the wiring part and the third electrode changes (increases). Since the wiring part is connected to the first electrode (i.e., conductive), this change in capacitance is judged to be a change in the first capacitance, and it is detected that a shear force has acted in a specific direction, even though no shear force has acted in that direction. This type of false detection is sometimes called "multi-axis interference."

[0007] An object of the present invention is to suppress the above-mentioned multi-axis interference. [Means for solving the problem]

[0008] In the following, several aspects will be described as means for solving the problems. These aspects can be arbitrarily combined as necessary. A shear force detection device according to one aspect of the present invention includes a first conductive layer, a second conductive layer facing the first conductive layer, and an insulating elastic body disposed between the first conductive layer and the second conductive layer and capable of elastic deformation. The first conductive layer includes a first electrode and a second electrode disposed facing each other with a first gap in a first direction, a first wiring portion connected to the first electrode, and a second wiring portion connected to the second electrode. The second conductive layer includes a third electrode disposed to overlap the first gap, the first electrode, and the second electrode, and generates a first capacitance between the first electrode and the second electrode and generates a second capacitance between the second electrode. The shear force detection device includes a ground electrode disposed between the first conductive layer and the second conductive layer at a portion where a portion electrically connected to the third electrode overlaps with the first wiring portion and at a portion where a portion electrically connected to the third electrode overlaps with the second wiring portion, and connected to a ground potential.

[0009] As described above, by disposing the ground electrode connected to the ground potential between the first conductive layer and the second conductive layer in the overlapping portion between the portion electrically connected to the third electrode and the first wiring portion and the overlapping portion between the portion electrically connected to the third electrode and the second wiring portion, a capacitance component is unlikely to be formed in the overlapping portion between the portion electrically connected to the third electrode and the first wiring portion and the overlapping portion between the portion electrically connected to the third electrode and the second wiring portion. Since no capacitance component is formed in these overlapping portions (or the capacitance is small even if a force is applied only to any of these overlapping portions), it is not determined that the force has caused a change in the first capacitance formed between the first electrode and the third electrode and / or the second capacitance formed between the second electrode and the third electrode. As a result, it is possible to suppress the occurrence of erroneous detection of shear force when a force is applied only to the overlapping portion.

[0010] In the above shear force detection device, the first conductive layer may have a fourth electrode and a fifth electrode arranged to face each other with a second gap in a second direction different from the first direction, the fourth electrode being connected to the first wiring portion, and the fifth electrode being connected to the second wiring portion. The second conductive layer may also have a sixth electrode. The sixth electrode is overlapped with the second gap, the fourth electrode, and the fifth electrode, and generates a third capacitance between the fourth electrode and the fifth electrode, and generates a fourth capacitance between the fifth electrode and the fourth electrode. In this case, the ground electrode may be arranged in a portion where the first wiring portion and a portion electrically connected to the sixth electrode overlap, and in a portion where the second wiring portion and a portion electrically connected to the sixth electrode overlap. As a result, no capacitance component is formed in the overlapping portion between the first wiring portion and the portion electrically connected to the sixth electrode, and in the overlapping portion between the second wiring portion and the portion electrically connected to the sixth electrode, so that even if a force is applied only to one of these overlapping portions, it is not determined that the third capacitance formed between the fourth electrode and the sixth electrode and / or the fourth capacitance formed between the fifth electrode and the sixth electrode has changed due to this force. As a result, it is possible to suppress the occurrence of erroneous detection of shear force when a force is applied only to these overlapping portions of the first wiring portion and the second wiring portion.

[0011] In the above shear force detection device, the ground electrode may be disposed between the first and second conductive layers and close to the second conductive layer, thereby further suppressing the generation of capacitance components in the overlapping portions.

[0012] In the above shear force detection device, the ground electrode may be disposed between the first conductive layer and the second conductive layer and close to the first conductive layer, which makes it easier to manufacture the shear force detection device while suppressing generation of a capacitance component.

[0013] The shear force detector may further include an insulator layer disposed on the first conductive layer. In this case, the ground electrode may be formed on the insulator layer. This makes it possible to form the ground electrode by utilizing the insulator layer while suppressing damage to the first conductive layer.

[0014] In the above shear force detection device, the ground electrode may be disposed in a portion where the third electrode and the first wiring portion overlap, and in a portion where the third electrode and the second wiring portion overlap, so that a capacitance component is unlikely to be formed in these overlapping portions.

[0015] In the above shear force detector, the second conductive layer may have a third wiring portion connected to the sixth electrode. In this case, the ground electrode may be disposed in a portion where the first wiring portion and the third wiring portion overlap, and in a portion where the second wiring portion and the third wiring portion overlap. This makes it difficult for a capacitance component to be formed in these overlapping portions.

[0016] In the above shear force detector, the second conductive layer may have a fourth wiring portion connected to the third electrode. In this case, the ground electrode may be disposed in a portion where the first wiring portion and the fourth wiring portion overlap, and in a portion where the second wiring portion and the fourth wiring portion overlap. This makes it difficult for a capacitance component to be formed in these overlapping portions. Effect of the Invention

[0017] The shear force detection device according to the present invention suppresses erroneous detection (multi-axis interference) in which a shear force is detected as acting in a direction in which no shear force is acting. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing an overall configuration of a shear force detection device. [Diagram 2] FIG. 4 is a cross-sectional view of the shear force sensor cell in the Y direction. [Diagram 3] 4 is a diagram showing the planar shapes of a first electrode, a second electrode, a fourth electrode, and a fifth electrode. FIG. [Figure 4] FIG. 4 is a diagram showing the planar shapes of a third electrode and a sixth electrode. [Diagram 5] FIG. 4 is a diagram showing a planar shape of a ground electrode. [Figure 6] 5A and 5B are diagrams illustrating an example of a state in which a shear force is applied to a shear force sensor cell. [Figure 7]FIG. 2 is a cross-sectional view of the shear force sensor cell in the X direction. [Figure 8A] 11A to 11C are diagrams showing other configurations of electrodes and wiring in the shear force sensor cell. [Figure 8B] 11A to 11C are diagrams showing other configurations of electrodes and wiring in the shear force sensor cell. [Figure 9A] 13A and 13B are diagrams showing still other configurations of electrodes and wiring in the shear force sensor cell. [Figure 9B] 13A and 13B are diagrams showing still other configurations of electrodes and wiring in the shear force sensor cell. [Figure 10A] 13A and 13B are diagrams showing still other configurations of electrodes and wiring in the shear force sensor cell. [Figure 10B] 13A and 13B are diagrams showing still other configurations of electrodes and wiring in the shear force sensor cell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 1. First embodiment (1) Overall configuration of the shear force detection device The configuration of a shear force detection device 1 of the first embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing the overall configuration of the shear force detection device 1. The shear force detection device 1 includes a shear force sensor cell 10, a drive circuit 2, and a sense circuit 3. The shear force sensor cell 10 is a sensor unit for detecting shear force. In the shear force detection device 1, a plurality of shear force sensor cells 10 are arranged side by side in the X-axis direction, and a plurality of shear force sensor cells 10 are arranged side by side in the Y-axis direction. This allows the shear force detection device 1 to measure the positions where a shear force is acting, and the direction and magnitude of the shear force acting at each position.

[0020] The drive circuit 2 is a circuit for providing an AC voltage for driving each shear force sensor cell 10 of the shear force detection device 1. The sense circuit 3 is a circuit for measuring the electrostatic capacitance (first capacitance C1 to fourth capacitance C4 described later) formed in each shear force sensor cell 10.

[0021] (2) Shear force sensor cell The detailed configuration of the shear force sensor cell 10 will be described below with reference to Fig. 1 to Fig. 4. Fig. 2 is a cross-sectional view of the shear force sensor cell 10 in the Y direction. Fig. 3 is a diagram showing the planar shapes of the first electrode, the second electrode, the fourth electrode, and the fifth electrode. Fig. 4 is a diagram showing the planar shapes of the third electrode and the sixth electrode.

[0022] As shown in FIG. 2, the shear force sensor cell 10 includes a first surface layer L1, a first shield layer L2, a first insulating layer L3, a first conductive layer L4, a second shield layer L5, an insulating elastomer layer L6, a second conductive layer L7, a second insulating layer L8, a third insulating layer L9, a second surface layer L10, a third conductive layer L11, a fourth conductive layer L12, and a fifth conductive layer L13.

[0023] The first surface layer L1 is an insulating layer that serves as the first surface of the shear force detection device 1. The first shield layer L2 is formed on the first surface layer L1. The first shield layer L2 is an insulating layer that protects the third conductive layer L11 from destruction.

[0024] The first insulating layer L3 is an insulating layer formed on the third conductive layer L11. The first insulating layer L3 is, for example, a layer of an insulating material such as polyethylene terephthalate (PET) resin.

[0025] The first conductive layer L4 is provided on the first insulating layer L3. The first conductive layer L4 is provided with a first electrode 11 and a second electrode 12. That is, the first electrode 11 and the second electrode 12 are formed on the first insulating layer L3. The first electrode 11 and the second electrode 12 are made of a thin film having electrical conductivity.

[0026] 3, the first electrode 11 and the second electrode 12 have a rectangular shape extending in the X direction. The first electrode 11 and the second electrode 12 face each other with a first gap G1 in the Y direction. The first electrode 11 is connected to a first wiring 31a. The second electrode 12 is connected to a second wiring 31b. The first wiring 31a and the second wiring 31b are made of a conductive thin film and extend in the Y direction.

[0027] 1, the first electrode 11 and the second electrode 12 are connected to the drive circuit 2 by a first wiring 31a and a second wiring 31b, respectively. When measuring a shear force, the drive circuit 2 applies AC voltages to the first electrode 11 and the second electrode 12 at different timings. That is, the first electrode 11 and the second electrode 12 function as drive electrodes when the shear force sensor cell 10 measures the shear force.

[0028] The second shield layer L5 is formed on the first conductive layer L4. The second shield layer L5 is an insulating layer for protecting the first electrode 11, the second electrode 12, and the first wiring 31a formed on the first conductive layer L4 from destruction.

[0029] The insulating elastomer layer L6 is disposed on the second shield layer L5. The insulating elastomer layer L6 is a layer including an insulating elastomer 13. When a shear force is applied to the shear force sensor cell 10, the insulating elastomer 13 is elastically deformable in the direction in which the shear force acts.

[0030] The second conductive layer L7 is provided on the insulating elastomer layer L6. The second conductive layer L7 is provided with a third electrode 14. That is, the third electrode 14 is formed on the insulating elastomer layer L6. The third electrode 14 is made of a conductive thin film.

[0031] 4, the third electrode 14 has a rectangular shape extending in the X direction. The third electrode 14 is disposed so as to overlap a part of the first electrode 11 formed on the first conductive layer L4, the first gap G1, and a part of the second electrode 12. As a result, a first capacitance C1 and a second capacitance C2 are formed in the overlapping portion between the first electrode 11 and the third electrode 14 and the overlapping portion between the second electrode 12 and the third electrode 14, respectively.

[0032] 2, the third electrode 14 is preferably disposed so that an overlapping area A1 between the first electrode 11 and the third electrode 14 is equal to an overlapping area A2 between the second electrode 12 and the third electrode 14 when no shear force is applied to the shear force sensor cell 10. This makes the first capacitance C1 and the second capacitance C2 equal when no shear force is applied, making them easy to use as a reference.

[0033] 1, the third electrode 14 is connected to the sense circuit 3. The sense circuit 3 measures the first capacitance C1 and the second capacitance C2 based on the charge detected by the third electrode 14 when a voltage is applied to the first electrode 11 and when a voltage is applied to the second electrode 12. That is, the third electrode 14 functions as a detection electrode when the shear force sensor cell 10 measures the shear force in the Y direction.

[0034] The second insulating layer L8 is an insulating layer formed on the second conductive layer L7.

[0035] The third insulating layer L9 is an insulator layer formed on the fourth conductive layer L12. The second surface layer L10 is an insulator layer that becomes the second surface of the shear force detection device 1.

[0036] The third conductive layer L11 is provided on the first shield layer L2. A seventh electrode 19 is formed on the third conductive layer L11 over the entire shear force sensor cell 10. The seventh electrode 19 is made of a conductive thin film. The seventh electrode 19 is connected to a ground potential. The seventh electrode 19 reduces noise in the shear force sensor cell 10.

[0037] The fourth conductive layer L12 is provided on the second insulating layer L8. An eighth electrode 20 is formed on the fourth conductive layer L12 over the entire shear force sensor cell 10. The eighth electrode 20 is made of a conductive thin film. The eighth electrode 20 is connected to a ground potential. The eighth electrode 20 reduces noise in the shear force sensor cell 10.

[0038] The principle of measuring shear force in the above-mentioned shear force sensor cell 10 is as follows. As shown in Fig. 6, for example, consider a case where a shear force in the positive Y direction is applied to the shear force sensor cell 10. Note that a shear force in the negative Y direction can also be measured based on the following principle. Fig. 6 is a diagram showing an example of a state where a shear force is applied to the shear force sensor cell 10.

[0039] When a shear force in the positive Y direction is applied to the shear force sensor cell 10, the insulating elastic body 13 is elastically deformed in the positive Y direction. Due to this elastic deformation of the insulating elastic body 13 in the positive Y direction, the third electrode 14 moves in the positive Y direction relative to the first electrode 11 and the second electrode 12. As a result, the overlapping area A1 between the first electrode 11 and the third electrode 14 and the overlapping area A2 between the second electrode 12 and the third electrode 14 change more than when no shear force is applied. Specifically, the overlapping area A1 between the first electrode 11 and the third electrode 14 arranged in the positive Y direction becomes larger, and the overlapping area A2 between the second electrode 12 and the third electrode 14 arranged in the negative Y direction becomes smaller.

[0040] The shear force in the positive direction of Y increases the overlap area A1 between the first electrode 11 and the third electrode 14, thereby increasing the first capacitance C1, and decreases the overlap area A2 between the second electrode 12 and the third electrode 14, thereby decreasing the second capacitance C2. In this way, by detecting the increase in the first capacitance C1 and the decrease in the second capacitance C2, it is possible to detect that a shear force has been applied in the positive direction of Y, that is, the direction in which the shear force has been applied. For example, when the difference (C1-C2) between the first capacitance C1 and the second capacitance C2 is greater than when no shear force is applied, it can be determined that a shear force has been applied in the positive direction of Y. On the other hand, when the difference between the first capacitance C1 and the second capacitance C2 is smaller than when no shear force is applied, it can be determined that a shear force has been applied in the negative direction of Y.

[0041] The amount of deformation of the insulating elastomer 13 due to the application of a shear force depends on the magnitude of the shear force. Therefore, the magnitude of the shear force can be measured from the amount of change in the first capacitance C1 and / or the second capacitance C2, or the absolute value of the difference between the first capacitance C1 and the second capacitance C2.

[0042] Furthermore, when a force is applied to the shear force sensor cell 10 in the vertical direction (Z direction), the insulating elastic body 13 deforms in the vertical direction, and its thickness changes (decreases). This change in thickness changes the distance between the first electrode 11 and the second electrode 12 and the third electrode 14, and therefore the first capacitance C1 and the second capacitance C2 change (increase). By capturing this change in capacitance, it is possible to detect the application of a force in the vertical direction and measure the magnitude of the detected force in the vertical direction.

[0043] 4, in the above-described shear force sensor cell 10, the third electrode 14 extends in the X direction throughout the entire shear force sensor cell 10. Therefore, the third electrode 14 not only overlaps the first electrode 11 and the second electrode 12, but also overlaps with the first wiring 31a formed continuously with the first electrode 11 and the second wiring 31b formed continuously with the second electrode 12 at the end of the shear force sensor cell 10 (the portion surrounded by the dashed dotted line in FIG. 4).

[0044] In this case, for example, when a predetermined object (e.g., a roller) moves in the X direction and applies a shear force only in the X direction, when the predetermined object passes through an overlapping portion between the portion of the second conductive layer L7 electrically connected to the third electrode 14 and the first wiring 31a (the end portion in the positive X direction of the shear force sensor cell 10), the predetermined object presses against the overlapping portion between the portion electrically connected to the third electrode 14 and the first wiring 31a. Also, when the predetermined object passes through an overlapping portion between the portion electrically connected to the third electrode 14 and the second wiring 31b (the end portion in the negative X direction of the shear force sensor cell 10), the predetermined object presses against the overlapping portion between the portion electrically connected to the third electrode 14 and the second wiring 31b.

[0045] When the overlapping portion between the part electrically connected to the third electrode 14 and the first wiring 31a, or the overlapping portion between the part electrically connected to the third electrode 14 and the second wiring 31b is pressed, the thickness of the insulating elastic body 13 at this overlapping portion changes (becomes smaller), and the capacitance of the capacitance component formed between the part electrically connected to the third electrode 14 and the first wiring 31a, or between the part electrically connected to the third electrode 14 and the second wiring 31b changes (increases). Since the first wiring 31a is electrically connected to the first electrode 11 and the second wiring 31b is electrically connected to the second electrode 12, the change in capacitance is determined to be a change in the first capacitance C1 or the second capacitance C2, and it is erroneously detected that a shear force has acted in the Y direction, even though no shear force has acted in the Y direction. Specifically, when a predetermined object reaches an end in the negative direction of X, it is detected that a shear force has acted in the negative direction of Y, and when a predetermined object reaches an end in the positive direction of X, it is detected that a shear force has acted in the positive direction of Y.

[0046] In order to suppress such erroneous detection, the shear force sensor cell 10 includes a ground electrode 15. As shown in FIG. 5, the ground electrode 15 is disposed between the first conductive layer L4 (the first electrode 11, the second electrode 12, and the first wiring 31a) and the second conductive layer L7 (the third electrode 14) at least in a portion where a portion of the second conductive layer L7 electrically connected to the third electrode 14 overlaps with the first wiring 31a, and in a portion where a portion of the second conductive layer L7 electrically connected to the third electrode 14 overlaps with the second wiring 31b (a portion surrounded by a dashed line in FIG. 4). Specifically, the ground electrode 15 is disposed in the overlapping portion between the third electrode 14 and the first wiring 31a and its periphery, on the first wiring 31a, in the overlapping portion between the third electrode 14 and the second wiring 31b and its periphery, and on the second wiring 31b. As shown in FIG. 5, the ground electrode 15 is connected to a ground potential. FIG. 5 is a diagram showing a planar shape of the ground electrode 15.

[0047] The ground electrode 15 is disposed on the fifth conductive layer L13 between the first conductive layer L4 and the second conductive layer L7. In this embodiment, the fifth conductive layer L13 is disposed closer to the second conductive layer L7 in the Z direction (thickness direction of the shear force sensor cell 10). That is, the ground electrode 15 is disposed closer to the second conductive layer L7 (third electrode 14). For example, another insulating layer may be formed under the second conductive layer L7, and the ground electrode 15 (fifth conductive layer L13) may be formed on the opposite side of the insulating layer to the second conductive layer L7. This makes it difficult for an electric field to be generated around the ground electrode 15 between the portion electrically connected to the third electrode 14 and the overlapping portion of the first wiring 31a, and therefore makes it difficult for a capacitance component to be generated between the overlapping portion of the third electrode 14 and the first wiring 31a.

[0048] In this way, by arranging a ground electrode 15 connected to a ground potential between the first conductive layer L4 and the second conductive layer L7 in the overlapping portion between the portion electrically connected to the third electrode 14 formed on the second conductive layer L7 and the first wiring 31a formed on the first conductive layer L4, and in the overlapping portion between the portion electrically connected to the third electrode 14 and the second wiring 31b formed on the first conductive layer L4, a capacitance component is less likely to be formed in the overlapping portion between the portion electrically connected to the third electrode 14 and the first wiring 31a, and in the overlapping portion between the portion electrically connected to the third electrode 14 and the second wiring 31b. Since no capacitance component is formed, or even if a capacitance component is formed, the capacitance is small in the overlapping portion between the portion electrically connected to the third electrode 14 and the first wiring 31a and the overlapping portion between the portion electrically connected to the third electrode 14 and the second wiring 31b, for example, even if a certain object is present at the end of the shear force sensor cell 10 in the X direction and a force is applied only to one of these overlapping portions, it is not determined that the first capacitance C1 formed between the first electrode 11 and the third electrode 14 or the second capacitance C2 formed between the second electrode 12 and the third electrode 14 has changed. As a result, it is possible to suppress the erroneous determination that a shear force has been applied in the Y direction when no shear force is acting in the Y direction when a force is applied only to the end of the shear force sensor cell 10 in the X direction.

[0049] By including the first electrode 11, the second electrode 12, the third electrode 14, and the ground electrode 15, the shear force sensor cell 10 can accurately measure the shear force in the Y direction acting on the shear force sensor cell 10. The shear force sensor cell 10 can not only measure the shear force in the Y direction, but also measure the shear force in a direction different from the Y direction (the X direction). In order to measure the shear force in the X direction, the shear force sensor cell 10 further includes a fourth electrode 16, a fifth electrode 17, and a sixth electrode 18.

[0050] The fourth electrode 16, the fifth electrode 17, and the sixth electrode 18 will be described below with reference to Figures 3 to 5 and 7. Figure 7 is a cross-sectional view of the shear force sensor cell 10 in the X direction.

[0051] The fourth electrode 16 and the fifth electrode 17 are provided on the first conductive layer L4. The fourth electrode 16 and the second electrode 12 are made of a thin film having conductivity. As shown in FIG. 3, the fourth electrode 16 and the fifth electrode 17 have a rectangular shape extending in the Y direction. The fourth electrode 16 and the fifth electrode 17 face each other with a second gap G2 in the X direction. The shear force sensor cell 10 of this embodiment has four fourth electrodes 16 and four fifth electrodes 17. In the shear force sensor cell 10, the fourth electrodes 16 and the fifth electrodes 17 are alternately arranged in the X direction. Specifically, one fourth electrode 16 is arranged between two fifth electrodes 17 arranged in the X direction with a second gap G2 between the fourth electrode 16 and the fifth electrode 17. One fifth electrode 17 is arranged between two fourth electrodes 16 arranged in the X direction with a second gap G2 between the fourth electrode 16 and the fifth electrode 17.

[0052] The fourth electrode 16 is connected to the first wiring 31a. The fifth electrode 17 is connected to the second wiring 31b. Specifically, the fourth electrode 16 arranged at the end in the positive X direction is directly connected to the first wiring 31a on the positive X direction side. In addition, the four fourth electrodes 16 are connected to the first electrodes 11 for the shear force sensor cells 10 adjacent in the Y direction at the end in the negative Y direction. Since the first electrodes 11 are connected to the first wiring 31a on the positive X direction side, the four fourth electrodes 16 are connected to the first electrodes 11 and are therefore connected to the first wiring 31a on the positive X direction side.

[0053] Furthermore, the fifth electrode 17 arranged at the end in the negative X direction is directly connected to the second wiring 31b on the negative X direction side. Furthermore, the four fifth electrodes 17 are connected to the second electrode 12 at the end in the positive Y direction. Since the second electrode 12 is connected to the second wiring 31b on the negative X direction side, the four fifth electrodes 17 are connected to the second electrode 12, and are thereby connected to the second wiring 31b on the negative X direction side.

[0054] 5, the fourth electrode 16 and the fifth electrode 17 are connected to the drive circuit 2 by a first wiring 31a and a second wiring 31b, respectively. That is, the fourth electrode 16 and the fifth electrode 17 function as drive electrodes when the shear force sensor cell 10 measures the shear force.

[0055] The sixth electrode 18 is provided on the second conductive layer L7. The sixth electrode 18 is made of a conductive thin film. As shown in FIG. 4, the sixth electrode 18 has a rectangular shape extending in the Y direction. However, the length of the sixth electrode 18 is shorter than the fourth electrode 16 and the fifth electrode 17. As described above, since there are four pairs of the fourth electrode 16 and the fifth electrode 17, four sixth electrodes 18 are also provided lined up in the X direction corresponding to the four pairs.

[0056] Each sixth electrode 18 is disposed so as to overlap a part of each fourth electrode 16 formed on the first conductive layer L4, each second gap G2, and a part of each fifth electrode 17. As a result, a third capacitance C3 and a fourth capacitance C4 are formed in the overlapping portion between the fourth electrode 16 and the sixth electrode 18, and in the overlapping portion between the fifth electrode 17 and the sixth electrode 18, respectively.

[0057] 7, the sixth electrode 18 is preferably disposed so that an overlapping area A3 between the fourth electrode 16 and the sixth electrode 18 is equal to an overlapping area A4 between the fifth electrode 17 and the sixth electrode 18 when no shear force is applied to the shear force sensor cell 10. This makes the third capacitance C3 and the fourth capacitance C4 equal when no shear force is applied, making them easy to use as a reference.

[0058] As shown in Fig. 4, the sixth electrodes 18 are connected to each other by a third wiring 31c disposed on the second conductive layer L7. Also, as shown in Fig. 1, the sixth electrodes 18 are connected to the sense circuit 3 by the third wiring 31c. That is, the sixth electrodes 18 function as detection electrodes when the shear force sensor cell 10 measures the shear force in the X direction.

[0059] As described above, the third wiring 31c connects the sixth electrodes 18 in the shear force sensor cell 10 and connects each of the sixth electrodes to the sense circuit 3. For this reason, the third wiring 31c extends in the X direction throughout the entire shear force sensor cell 10.

[0060] The principle of measurement of a shear force in the X direction in the shear force sensor cell 10 is the same as the principle of measurement of a shear force in the Y direction described above. When a shear force in the X direction is applied to the shear force sensor cell 10, the insulating elastic body 13 is elastically deformed in the X direction. Due to this elastic deformation of the insulating elastic body 13 in the X direction, the sixth electrode 18 moves in the X direction relative to the fourth electrode 16 and the fifth electrode 17. As a result, the overlapping area A3 between the fourth electrode 16 and the sixth electrode 18 and the overlapping area A4 between the fifth electrode 17 and the sixth electrode 18 change more than when no shear force is applied.

[0061] The shear force in the X direction changes the overlap area A3 between the fourth electrode 16 and the sixth electrode 18 and the overlap area A4 between the fifth electrode 17 and the sixth electrode 18, so that one of the third capacitance C3 and the fourth capacitance C4 increases and the other decreases. By detecting the increase and decrease in the third capacitance C3 and the fourth capacitance C4, it is possible to detect that a shear force has been applied in the X direction. In addition, the magnitude of the shear force can be measured from the amount of change in the third capacitance C3 and / or the fourth capacitance C4 and the magnitude of the absolute value of the difference between the third capacitance C3 and the fourth capacitance C4.

[0062] In addition, measurement of forces in the vertical direction (Z direction) using the fourth electrode 16, the fifth electrode 17, and the sixth electrode 18 can be achieved using a principle similar to the measurement principle using the first electrode 11, the second electrode 12, and the third electrode 14 described above.

[0063] As described above, in the shear force sensor cell 10, the third wiring 31c electrically connected to the sixth electrode 18 in the second conductive layer L7 extends in the X direction throughout the shear force sensor cell 10. Therefore, as shown in Fig. 4, the third wiring 31c overlaps with the fourth electrode 16, the fifth electrode 17, the first wiring 31a, and the second wiring 31b.

[0064] In this case, for example, when a specific object (e.g., a roller) moves in the X direction and applies a shear force in the positive X direction, when the specific object passes through an overlapping portion between the first wiring 31a and the third wiring 31c electrically connected to the sixth electrode 18, or an overlapping portion between the second wiring 31b and the third wiring 31c electrically connected to the sixth electrode 18 (an end portion of the shear force sensor cell 10), the specific object presses against these overlapping portions.

[0065] When the overlapping portion between the first wiring 31a and the third wiring 31c electrically connected to the sixth electrode 18, or the overlapping portion between the second wiring 31b and the third wiring 31c electrically connected to the sixth electrode 18, is pressed, the thickness of the insulating elastic body 13 at the overlapping portion between the first wiring 31a and the third wiring 31c and the overlapping portion between the second wiring 31b and the third wiring 31c changes (becomes smaller), and the capacitance of the capacitance component formed between the first wiring 31a and the third wiring 31c and between the second wiring 31b and the third wiring 31c changes (increases). Since the first wiring 31a and the second wiring 31b are connected to the fourth electrode 16 and the fifth electrode 17, respectively, and the third wiring 31c is connected to the sixth electrode 18, this change in capacitance is determined as a change in the third capacitance C3 and the fourth capacitance C4, and a false detection of a shear force occurs.

[0066] For example, when a predetermined object reaches the end in the negative X direction, only the overlapping portion between the first wiring 31a and the third wiring 31c connected to the fifth electrode 17 is pressed, and the capacitance of that portion increases. As a result, the fourth capacitance C4 increases while the third capacitance C3 does not change, and it is erroneously detected that a shear force acts in the negative X direction.

[0067] In order to suppress such erroneous detection, as shown in Fig. 5, the ground electrode 15 is also provided in the overlapping portion between the first wiring 31a and the third wiring 31c and the overlapping portion between the second wiring 31b and the third wiring 31c. As a result, as described above, a capacitance component is unlikely to be formed in these overlapping portions, so that even if a force is applied only to one of these overlapping portions, it is not determined that the third capacitance C3 formed between the fourth electrode 16 and the sixth electrode 18 and the fourth capacitance C4 formed between the fifth electrode 17 and the sixth electrode 18 have changed due to this force. As a result, it is possible to suppress the occurrence of erroneous detection of a shear force (for example, erroneous detection of the direction of the shear force) when a force is applied only to one of these overlapping portions.

[0068] (3) Material The materials used for each shear force sensor cell 10 will be described below. The surface layer (first surface layer L1, second surface layer L10) and insulating layer (first shield layer L2, second shield layer L5, second insulating layer L8, third insulating layer L9) of the shear force sensor cell 10 can be made of, for example, silicone resin. They can also be made of, for example, thermoplastic resin, thermosetting resin, and ultraviolet curing resin. Examples of thermoplastic resin and thermosetting resin include polyethylene terephthalate (PET) resin, acrylic resin, urethane resin, fluororesin, polyester resin, polycarbonate resin, polyacetal resin, polyamide resin, and olefin. Examples of ultraviolet curing resin include acrylic resin and epoxy resin.

[0069] The first electrode 11, the second electrode 12, the third electrode 14, the ground electrode 15, the fourth electrode 16, the fifth electrode 17, the sixth electrode 18, the seventh electrode 19, the eighth electrode 20, the first wiring 31a, and the third wiring 31c of the shear force sensor cell 10 can be configured as, for example, a metal film, a conductive ceramic film, a conductive paste film, or a conductive polymer film. Examples of metal films include films of gold, silver, copper, nickel, aluminum, titanium, and palladium. Examples of conductive ceramic films include films of indium tin oxide and zinc oxide. Examples of conductive paste films include thin films of materials in which metal particles are dispersed in a resin binder. Examples of materials for conductive paste films include silver paste. Examples of conductive polymer films include films of polyhexylthiophene, polydioctylfluorene, pentacene, and tetrabenzoporphyrin.

[0070] As a method for forming electrodes and wiring (first electrode 11, second electrode 12, third electrode 14, ground electrode 15, fourth electrode 16, fifth electrode 17, sixth electrode 18, first wiring 31a, third wiring 31c) having a predetermined shape, for example, there is a method of forming a conductive film on the entire layer and then patterning it by etching. To form a conductive film on the entire layer, for example, lamination of a rolled conductive film, plating, sputtering, vapor deposition, or ion plating can be used. In addition, in the case of a conductive paste film, a method of directly forming a pattern by a printing method such as screen, gravure, or offset can be used. The thickness of the above electrodes and wiring is appropriately selected from the range of, for example, 0.1 μm to 5 mm.

[0071] The insulating elastic body 13 is made of, for example, a foam or gel. An example of a foam is one in which gas is finely dispersed in resin and molded into a foamed or porous shape. Examples of the foam material include silicone, urethane, polyethylene, and polystyrene. The thickness of the insulating elastic body 13 is appropriately selected from the range of, for example, 2 μm to 5 mm.

[0072] Conductive particles may be added to the insulating elastomer 13 in a proportion that allows the insulating properties to be maintained. Examples of the material of the conductive particles include carbon black, gold, silver, and nickel. This has the effect that when the insulating elastomer 13 is pressed, the distance between the conductive particles contained in the insulating elastomer 13 becomes closer, causing a sudden increase in the capacitance value between the first electrode 11 and the second electrode 12 and the third electrode 14, thereby improving the detection sensitivity of the shear force. The average particle size of the conductive particles is preferably 1 / 10 or less of the thickness of the insulating elastomer 13.

[0073] 2. Other embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple embodiments and modifications described in this specification can be arbitrarily combined as necessary. (A) The ground electrode 15 may be formed on the second shield layer L5 and disposed at a position closer to the first conductive layer L4 (first electrode 11, second electrode 12). By forming the ground electrode 15 on the second shield layer L5 in this manner, it is possible to easily form the ground electrode 15 by utilizing the second shield layer L5 while suppressing damage to the first conductive layer L4.

[0074] (B) The planar (XY plane) shapes of first electrode 11, second electrode 12, third electrode 14, ground electrode 15, fourth electrode 16, fifth electrode 17, and sixth electrode 18 are not limited to the shapes shown in Figures 3, 4, and 5.

[0075] For example, as shown in Fig. 8A, the first electrode 11 and the second electrode 12 extending in the X direction are arranged to face each other in the Y direction, and the fourth electrode 16 and the fifth electrode 17 extending in the Y direction are arranged to face each other in the X direction at the negative Y position of these electrodes, and these electrodes can be connected to the linear first wiring 31a and the second wiring 31b. In addition, the third electrode 14 extending in the X direction throughout the entire shear force sensor cell 10 is arranged to face the first electrode 11, the second electrode 12, and the gap between the first electrode 11 and the second electrode 12 in the Z direction (thickness direction), and the sixth electrode 18 is arranged to face the fourth electrode 16, the fifth electrode 17, and the gap between the fourth electrode 16 and the fifth electrode 17 in the Z direction. Furthermore, a third wiring 31c electrically connected to the sixth electrode 18 is provided.

[0076] In this case, as shown in Fig. 8B, the ground electrode 15 can be formed, for example, in and around the overlapping portion between the third electrode 14 and the first wiring 31a and the second wiring 31b. By forming the ground electrode 15 so as to overlap the entire first wiring 31a and the second wiring 31b, the ground electrode 15 can also be formed in the overlapping portion between the first wiring 31a and the second wiring 31b and the third wiring 31c electrically connected to the sixth electrode 18. Figs. 8A and 8B are diagrams showing other forms of electrodes and wiring in the shear force sensor cell 10.

[0077] (C) For example, as shown in Fig. 9A, the first electrode 11 and the second electrode 12 are arranged to face each other in the Y direction, and the fourth electrode 16 and the fifth electrode 17 extending in the Y direction are arranged to face each other in the X direction at the negative Y direction position of these electrodes, and these electrodes can be connected to the linear first wiring 31a and the second wiring 31b. Also, the third electrode 14 is arranged to face the first electrode 11, the second electrode 12, and the gap between the first electrode 11 and the second electrode 12 in the Z direction (thickness direction), and the sixth electrode 18 is arranged to face the fourth electrode 16, the fifth electrode 17, and the gap between the fourth electrode 16 and the fifth electrode 17 in the Z direction. Furthermore, in addition to the third wiring 31c electrically connected to the sixth electrode 18, a fourth wiring 31d electrically connected to the third electrode 14 is provided.

[0078] In this case, as shown in Fig. 9B, the ground electrode 15 can be formed, for example, in an overlapping portion between the fourth wiring 31d electrically connected to the third electrode 14 and the first wiring 31a and second wiring 31b and around the overlapping portion. Moreover, by forming the ground electrode 15 so as to overlap the entire first wiring 31a and second wiring 31b, the ground electrode 15 can also be formed in an overlapping portion between the first wiring 31a and second wiring 31b and the third wiring 31c electrically connected to the sixth electrode 18. Figs. 9A and 9B are diagrams showing still other forms of electrodes and wirings in the shear force sensor cell 10.

[0079] (D) For example, as shown in Fig. 10A, the first electrode 11 and the second electrode 12 extending in the X direction may simply be arranged to face each other in the Y direction. In this case, the shear force sensor cell 10 can measure only the shear force in the Y direction. In this case, as shown in Fig. 10B, for example, a rectangular ground electrode 15 extending in the Y direction covering the overlapping portion between the first electrode 11 and the second electrode 12 and the first wiring 31a can be formed to overlap the entire first wiring 31a. Figs. 9A and 9B are diagrams showing still other forms of electrodes and wiring in the shear force sensor cell 10.

[0080] (E) The first electrode 11, the second electrode 12, the third electrode 14, the fourth electrode 16, the fifth electrode 17, and the sixth electrode 18 may have a shape other than a rectangle.

[0081] (F) The shear force sensor cell 10 may have an electrode arrangement capable of detecting shear force in a direction other than the X direction, the Y direction, and the Z direction.

[0082] (G) It is also possible to connect a sense circuit 3 to the first electrode 11 and the second electrode 12, causing the first electrode 11 and the second electrode 12 to function as detection electrodes, and to connect a drive circuit 2 to the third electrode 14, causing the third electrode 14 to function as a drive electrode.

[0083] (H) It is also possible to connect the sense circuit 3 to the fourth electrode 16 and the fifth electrode 17, causing the fourth electrode 16 and the fifth electrode 17 to function as detection electrodes, and to connect the drive circuit 2 to the sixth electrode 18, causing the sixth electrode 18 to function as a drive electrode.

[0084] 3. Notes The above embodiment can also be explained as follows. (1) A shear force detection device (e.g., shear force detection device 1) includes a first conductive layer (e.g., first conductive layer L4), a second conductive layer (e.g., second conductive layer L7) facing the first conductive layer, and an elastically deformable insulating elastomer (e.g., insulating elastomer 13) disposed between the first conductive layer and the second conductive layer. The first conductive layer includes a first electrode (e.g., first electrode 11) and a second electrode (e.g., second electrode 12) disposed opposite each other with a first gap (e.g., first gap G1) in a first direction (e.g., Y direction), a first wiring portion (e.g., first wiring 31a) connected to the first electrode, and a second wiring portion (e.g., second wiring 31b) connected to the second electrode. The second conductive layer has a third electrode (e.g., third electrode 14) arranged to overlap the first gap, the first electrode, and the second electrode, and generating a first capacitance (e.g., first capacitance C1) between the first electrode and a second capacitance (e.g., second capacitance C2) between the second electrode. The shear force detection device includes a ground electrode (e.g., ground electrode 15) connected to a ground potential, which is arranged between the first conductive layer and the second conductive layer at a portion where a portion electrically connected to the third electrode overlaps with the first wiring portion and at a portion where a portion electrically connected to the third electrode overlaps with the second wiring portion.

[0085] As described above, by disposing the ground electrode connected to the ground potential between the first conductive layer and the second conductive layer in the overlapping portion between the portion electrically connected to the third electrode and the first wiring portion and the overlapping portion between the portion electrically connected to the third electrode and the second wiring portion, a capacitance component is unlikely to be formed in the overlapping portion between the portion electrically connected to the third electrode and the first wiring portion and the overlapping portion between the portion electrically connected to the third electrode and the second wiring portion. Since no capacitance component is formed in these overlapping portions (or the capacitance is small even if a force is applied only to any of these overlapping portions), it is not determined that the first capacitance formed by the first electrode and the third electrode or the second capacitance formed by the second electrode and the third electrode has changed due to the force. As a result, it is possible to suppress the occurrence of erroneous detection of shear force when a force is applied only to the overlapping portion.

[0086] (2) In the shear force detection device of (1) above, the first conductive layer may have a fourth electrode (e.g., fourth electrode 16) and a fifth electrode (e.g., fifth electrode 17) arranged to face each other with a second gap (e.g., second gap G2) in a second direction (e.g., X direction) different from the first direction, and the fourth electrode may be connected to the first wiring section and the fifth electrode may be connected to the second wiring section. The second conductive layer may also have a sixth electrode (e.g., sixth electrode 18). The sixth electrode is overlapped with the second gap, the fourth electrode, and the fifth electrode, and generates a third capacitance (e.g., third capacitance C3) between the fourth electrode and the fifth electrode, and generates a fourth capacitance (e.g., fourth capacitance C4) between the fifth electrode and the fourth electrode. In this case, the ground electrode may be arranged in a portion where the first wiring section and a portion electrically connected to the sixth electrode overlap, and in a portion where the second wiring section and a portion electrically connected to the sixth electrode overlap. As a result, no capacitance component is formed in the overlapping portion between the first wiring portion and the portion electrically connected to the sixth electrode, and in the overlapping portion between the second wiring portion and the portion electrically connected to the sixth electrode, so that even if a force is applied only to one of these overlapping portions, it is not determined that the third capacitance formed between the fourth electrode and the sixth electrode, or the fourth capacitance formed between the fifth electrode and the sixth electrode, has changed due to this force. As a result, it is possible to suppress the occurrence of erroneous detection of shear force when a force is applied only to these overlapping portions of the first wiring portion and the second wiring portion.

[0087] (3) In the shear force detection device of (1) or (2) above, the ground electrode may be disposed between the first conductive layer and the second conductive layer and close to the second conductive layer, thereby further suppressing the generation of a capacitance component in the overlapping portion.

[0088] (4) In the shear force detection device of (1) or (2) above, the ground electrode may be disposed between the first conductive layer and the second conductive layer and close to the first conductive layer, which makes it easier to manufacture the shear force detection device while suppressing generation of a capacitance component.

[0089] (5) Any of the shear force detectors (1) to (4) above may further include an insulator layer (e.g., a second shield layer L5) disposed on the first conductive layer. In this case, the ground electrode may be formed on the insulator layer. This allows the ground electrode to be formed using the insulator layer while suppressing damage to the first conductive layer.

[0090] (6) In any of the shear force detection devices (1) to (5) above, the ground electrode may be disposed in an overlapping portion between the third electrode and the first wiring portion and an overlapping portion between the third electrode and the second wiring portion, so that a capacitance component is unlikely to be formed in these overlapping portions.

[0091] (7) In any of the shear force detectors (2) to (6) above, the second conductive layer may have a third wiring portion (e.g., the third wiring 31c) connected to the sixth electrode. In this case, the ground electrode may be disposed in a portion where the first wiring portion and the third wiring portion overlap, and in a portion where the second wiring portion and the third wiring portion overlap. This makes it difficult for a capacitance component to be formed in these overlapping portions.

[0092] (8) In any of the shear force detectors (1) to (7) above, the second conductive layer may have a fourth wiring portion (e.g., the fourth wiring 31d) connected to the third electrode. In this case, the ground electrode may be disposed in a portion where the first wiring portion and the fourth wiring portion overlap, and in a portion where the second wiring portion and the fourth wiring portion overlap. This makes it difficult for a capacitance component to be formed in these overlapping portions. [Explanation of symbols]

[0093] 1: Shear force detector 11: 1st electrode 12:Second electrode 13: Insulating elastomer 14:Third electrode 15: Ground electrode 16: 4th electrode 17: 5th electrode 18: 6th electrode 31a: 1st wiring 31b: 2nd wiring 31c: 3rd wiring 31d: 4th wiring A1~A4: Overlapping area C1: 1st capacity C2: 2nd capacity C3: 3rd capacity C4: 4th capacity G1: First gap G2: Second gap L4: First conductive layer L5: Second shield layer L7: Second conductive layer

Claims

1. A first conductive layer; a second conductive layer facing the first conductive layer; an insulating elastomer disposed between the first conductive layer and the second conductive layer and capable of elastic deformation; Equipped with the first conductive layer includes a first electrode and a second electrode arranged to face each other with a first gap in a first direction, a first wiring portion connected to the first electrode, and a second wiring portion connected to the second electrode; the second conductive layer has a third electrode arranged to overlap the first gap, the first electrode, and the second electrode, and generating a first capacitance between the third electrode and the first electrode and a second capacitance between the third electrode and the second electrode; a ground electrode connected to a ground potential, the ground electrode being disposed between the first conductive layer and the second conductive layer at a portion where a portion electrically connected to the third electrode and the first wiring portion overlap, and at a portion where a portion electrically connected to the third electrode and the second wiring portion overlap, Shear force detection device.

2. the first conductive layer includes a fourth electrode and a fifth electrode arranged to face each other with a second gap in a second direction different from the first direction; the fourth electrode is connected to the first wiring portion, and the fifth electrode is connected to the second wiring portion; the second conductive layer has a sixth electrode overlapping the second gap, the fourth electrode, and the fifth electrode, and forming a third capacitance between the sixth electrode and the fourth electrode, and forming a fourth capacitance between the sixth electrode and the fifth electrode; 2. The shear force detection device according to claim 1, wherein the ground electrode is arranged in a portion where the first wiring portion and a portion electrically connected to the sixth electrode overlap, and in a portion where the second wiring portion and a portion electrically connected to the sixth electrode overlap.

3. The shear force detection device according to claim 1 , wherein the ground electrode is disposed between the first conductive layer and the second conductive layer and in a position close to the second conductive layer.

4. The shear force detection device according to claim 1 , wherein the ground electrode is disposed between the first conductive layer and the second conductive layer and in a position close to the first conductive layer.

5. further comprising an insulator layer disposed on the first conductive layer; The shear force detection device according to claim 1 , wherein the ground electrode is formed on the insulating layer.

6. The shear force detection device according to claim 1 , wherein the ground electrode is disposed in a portion where the third electrode and the first wiring portion overlap, and in a portion where the third electrode and the second wiring portion overlap.

7. the second conductive layer has a third wiring portion connected to the sixth electrode, The shear force detection device according to claim 2 , wherein the ground electrode is arranged in a portion where the first wiring portion and the third wiring portion overlap, and in a portion where the second wiring portion and the third wiring portion overlap.

8. the second conductive layer has a fourth wiring portion connected to the third electrode, The shear force detection device according to claim 1 or 2, wherein the ground electrode is arranged in a portion where the first wiring portion and the fourth wiring portion overlap, and in a portion where the second wiring portion and the fourth wiring portion overlap.

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