JP2024065855A - Tactile Sensor - Google Patents

Abstract

[Problem] To provide a tactile sensor that ensures fixing strength between substrates and has high detection accuracy. [Solution] A tactile sensor comprising a first substrate, a first laminate provided on one side of the first substrate and having, in order from the first substrate side, a first electrode and a first resin layer having electrical conductivity, a second substrate facing one side of the first substrate, a second laminate provided on a surface of the second substrate facing the first substrate at a position facing the first laminate and having, in order from the second substrate side, a second electrode and a second resin layer having electrical conductivity, and a fixing layer provided so as to surround the first laminate and to bond and fix the opposing surfaces of the first substrate and the second substrate to each other, the tactile sensor being capable of detecting a shear force in a predetermined direction based on an electrical resistance value between the first electrode and the second electrode that corresponds to an overlapping area of the first resin layer and the second resin layer, and a slit for mitigating movement of the second substrate in the predetermined direction is provided inside the fixing layer in the second substrate and at a position spaced from the second laminate. [Selected Figure] Figure 1

Description

The present invention relates to a tactile sensor that detects pressure and shear force.

Tactile sensors that detect pressure and shear stress are known to have a structure in which a conductive layer or a resin layer is sandwiched between two opposing electrodes. In this type of tactile sensor, the conductive layer or the resin layer changes in shape when subjected to an external force, changing the physical quantity between the electrodes, and the sensor can detect pressure or shear force (shear stress) based on the change in the physical quantity between the electrodes.

For example, Patent Document 1 describes a resistive tactile sensor that has a pair of conductive layers and a pair of resistor layers covering each of the conductive layers between two opposing substrates, and utilizes the fact that the inter-electrode resistance value changes as the conductive layers deform when a force is input.
It is being done.

Patent document 2 also describes a tactile sensor in which a conductive and flexible magnetic rubber body is attached between two rectangular electrodes, and the sensor detects a shear force applied in a direction parallel to the contact surface (shear direction) based on the change in the amount of current between the electrodes that changes in response to the deformation of the magnetic rubber body.

When detecting changes in resistance, the detection layer is formed by sandwiching conductive rubber between two opposing electrodes, or by printing electrodes directly onto the conductive layer, or by creating two electrodes with conductive layers printed on them and overlapping the conductive layers.

However, when sandwiching conductive rubber between electrodes, the contact state between the conductive rubber and the electrodes can become noise during sensor detection. Also, when printing electrodes directly on the conductive layer, in principle the conductive layer detects signals by deforming, but if the conductive layer is made thin in order to miniaturize the sensor, it cannot deform sufficiently in response to an applied external force, resulting in poor detection accuracy.

For this reason, attention has been focused on a method in which two electrodes are printed with conductive layers and then these conductive layers are stacked together. This configuration is easy to manufacture, and has the advantage that it is easy to detect because the resistance value changes when the distance between the opposing electrodes changes due to an external force.

Japanese Patent No. 3664622 JP 2013-232293 A

When a shear force is applied to this type of tactile sensor, the overlapping area of the opposing electrodes changes, and the voltage between the electrodes also changes accordingly. Therefore, the shear force can be calculated from the relative amount of displacement between the opposing electrodes.

Furthermore, such a tactile sensor is constructed by fixing two substrates, each having electrodes and a conductive layer laminated thereon, via a fixing layer formed between the substrates. When detecting shear force, the opposing electrodes need to be configured to be able to shift relative to one another in response to the input shear force, but if the fixing strength of the fixing layer is too strong, the shift between the two substrates is hindered, reducing the accuracy of shear force detection. On the other hand, if the fixing strength is too weak, the fixing layer may break during use, causing the tactile sensor to break.

Therefore, the present invention aims to provide a tactile sensor that ensures the fixing strength between the substrates while also achieving high detection accuracy.

A tactile sensor comprising: a first substrate; a first laminate provided on one side of the first substrate, the first laminate having, in order from the first substrate side, a first electrode and a first resin layer having electrical conductivity; a second substrate facing the one side of the first substrate; a second laminate provided on the surface of the second substrate facing the first substrate at a position facing the first laminate, the second laminate having, in order from the second substrate side, a second electrode and a second resin layer having electrical conductivity; and a fixing layer provided to surround the first laminate and the second laminate, bonding and fixing the opposing surfaces of the first substrate and the second substrate to each other; the tactile sensor is capable of detecting a shear force in a predetermined direction based on an electrical resistance value between the first electrode and the second electrode according to an overlapping area of the first resin layer and the second resin layer; and a slit for mitigating movement of the second substrate in a predetermined direction is provided inside the fixing layer in the second substrate and at a position spaced from the second laminate.

The present invention provides a tactile sensor that ensures the fixing strength between the substrates while also achieving high detection accuracy.

1 is a schematic diagram showing a schematic configuration of a tactile sensor according to a first embodiment of the present invention; FIG. 4 is a partial schematic diagram of a first substrate side of the tactile sensor. FIG. 4 is a partial schematic diagram of a second substrate side of the tactile sensor. FIG. 4 is a partial cross-sectional view of the vicinity of a detection portion O and a detection portion Y in the tactile sensor. FIG. 2 is a cross-sectional view showing a schematic configuration of a tactile sensor. FIG. 4 is a partial cross-sectional view of the laminated body and its vicinity of the tactile sensor during pressure measurement. FIG. 4 is a partial cross-sectional view of the laminated body and its vicinity of the tactile sensor during shear force measurement. FIG. 13 is a diagram showing a tactile sensor in a state in which a shear force is input. FIG. 5 is a schematic diagram showing a schematic configuration of a tactile sensor according to a second embodiment of the present invention. FIG. 4 is a partial schematic diagram of a second substrate side of the tactile sensor. FIG. 13 is a diagram showing a tactile sensor in a state in which a shear force is input.

The following describes an embodiment of the present invention. The shape and number of electrodes are merely examples, and are not limited to the specific examples described here. In addition, to simplify the explanation, the figures are drawn at ratios different from the actual dimensions, but this does not detract from the gist of the technology related to the present invention.

First Embodiment
FIG. 1 is a schematic diagram showing the schematic configuration of a tactile sensor according to a first embodiment of the present invention, and more specifically, FIG. 1(a) is a plan view of the tactile sensor, and FIG. 1(b) is a cross-sectional view taken along line A-A' in FIG. 1(a). In FIG. 1(a), for convenience, electrodes and wiring (leads) are shown in a see-through manner. FIG. 2 is a partial schematic diagram of the first substrate side of the tactile sensor, and more specifically, FIG. 2(a) is a partial plan view of the first substrate side of the tactile sensor, and FIG. 2(b) is a cross-sectional view taken along line B-B' in FIG. 2(a). FIG. 3 is a partial schematic diagram of the second substrate side of the tactile sensor, and more specifically, FIG. 3(a) is a partial plan view of the second substrate side of the tactile sensor, and FIG. 3(b) is a cross-sectional view taken along line C-C' in FIG. 3(a).

The tactile sensor 100 is a sensor capable of detecting pressure and shear force applied to a substrate, and includes a first substrate 1, a second substrate 2 facing the first substrate 1 and having a slit 16, a first laminate 11, a second laminate 12, a third laminate 13, and a fourth laminate 14 provided between the first substrate 1 and the second substrate 2, and a fixing layer 15 that fixes the first substrate 1 and the second substrate 2. Pressure refers to the force component perpendicular to the sensor surface, and shear force refers to the force component in the surface direction of the substrate.

(Laminate)
The first laminate 11 is provided on one side (opposite to the second substrate 2) of the first substrate 1, and has, in order from the first substrate 1 side, a first electrode 11a and a first resin layer 11b laminated on the first electrode 11a. The second laminate 12 is provided on one side (opposite to the first substrate 1) of the second substrate 2, and has, in order from the second substrate 2 side, a second electrode 12a and a second resin layer 12b laminated on the second electrode. The third laminate 13 is provided on one side (opposite to the second substrate 2) of the first substrate 1, and has, in order from the first substrate 1 side, a third electrode 13a and a third resin layer 13b laminated on the third electrode 13a. The fourth laminate 14 is provided on one side (opposite to the first substrate 1) of the second substrate 2, and has, in order from the second substrate 2 side, a fourth electrode 14a and a fourth resin layer 14b laminated on the fourth electrode. The first laminate 11 and the second laminate 12 face each other between the first substrate 1 and the second substrate 2. The third laminate 13 and the fourth laminate 14 face each other between the first substrate 1 and the second substrate 2. Hereinafter, the upper and lower pair of laminates will be collectively referred to as a detection unit.

One or more laminates may be provided on one substrate, but three may be provided. That is, one or more detection units may be provided in the tactile sensor 100, but three may be provided. In the case of three, pressure and shear force in two axial directions can be detected. Specifically, as shown in FIG. 1, in an XY coordinate system with one detection unit O (third laminate 13 and fourth laminate 14) as the origin, detection unit X (first laminate 11 and second laminate 12) is arranged on the X axis, and detection unit Y (first laminate 11 and second laminate 12) is arranged on the Y axis. This makes it possible to detect shear force in the first direction (X-axis direction in FIG. 1) using detection unit X, and to detect shear force in the second direction (Y-axis direction in FIG. 1) perpendicular to the first direction using detection unit Y. In addition, pressure can be detected by detection unit O. Specifically, since the contact state between the third laminate 13 on the first substrate 1 and the fourth laminate 14 on the second substrate 2 changes according to the external force applied to the tactile sensor 100, the pressure applied to the tactile sensor 100 can be calculated from the change in resistance between the third electrode 13a and the fourth electrode 14a. In addition, when a shear force is applied to the tactile sensor 100, the contact area between the first laminate 11 on the first substrate 1 and the second laminate 12 on the second substrate 2 changes, so the shear force applied to the tactile sensor 100 can be calculated from the change in resistance between the first electrode 11a and the second electrode 12a. Note that, if the input direction of the shear force to be detected is determined to be one direction, one laminate is sufficient. In addition, by increasing the number of laminates, it becomes possible to measure the shear force with higher accuracy. For example, in order to improve accuracy, an additional laminate may be provided in a third direction that is not perpendicular to the first and second directions. Increasing the number of laminates is effective when it is desired to increase the measurement resolution even when the shear detection direction of the measurement target is completely specified.

(electrode)
The first electrode 11a and the second electrode 12a (shear force detection electrodes) in the detection unit X and the detection unit Y that contribute to the detection of the shear force have a shape (U-shape) in which two rectangular small electrodes s are arranged side by side. Specifically, the first electrode 11a and the second electrode 12a of the detection unit X that can detect the shear force in the X-axis direction have a pair of small electrodes s extending in the Y-axis direction and a connection part that electrically connects the pair of small electrodes s. Each pair of small electrodes s is arranged in parallel with a predetermined interval. In addition, the first electrode 11a and the second electrode 12a of the detection unit Y that can detect the shear force in the Y-axis direction have a pair of small electrodes s extending in the X-axis direction and a connection part that electrically connects the pair of small electrodes s. As a result, compared to the case in which each of the first electrode 11a and the second electrode 12a is formed as a single square, the area change when the first electrode 11a and the second electrode 12a are shifted up and down is larger, and the detection sensitivity can be improved.

The long side of the small electrode s of the first electrode 11a is formed longer than the long side of the small electrode s of the second electrode 12a, and when no shear force is input in either the X-axis or Y-axis direction, both ends of the small electrode s of the second electrode 12a in the long side direction are located inside both ends of the small electrode s of the first electrode 11a in the long side direction. Specifically, in the detection unit X, the end of the first electrode 11a on the positive side of the Y axis is located on the positive side of the Y axis from the end of the second electrode 12a on the positive side of the Y axis, and the end of the first electrode 12a on the negative side of the Y axis is located on the negative side of the Y axis from the end of the second electrode 12a on the positive and negative sides of the Y axis. Similarly, in the detection unit Y, the end of the first electrode 11a on the positive side of the X axis is located on the positive side of the X axis from the end of the second electrode 12a on the positive and negative sides of the X axis, and the end of the first electrode 12a on the negative side of the X axis is located on the negative side of the X axis from the end of the second electrode 12a on the positive and negative sides of the X axis. In this way, the first electrode 11a has a margin in the Y-axis direction in the detection unit X and in the X-axis direction in the detection unit Y with respect to the second electrode 12b, and it is preferable that the margin portion is equal to or greater than the allowable movement (shift) amount of the substrate in the long side direction (X-axis direction or Y-axis direction). As a result, even if a shear force is input in the Y-axis direction and the first electrode 11a and the second electrode 12a are shifted, for example, there is no change in the overlap area between the first electrode 11a and the second electrode 12a in the detection unit X. Therefore, the detection unit X can only detect the shear force in the X-axis direction, and the detection unit Y can only detect the shear force in the Y-axis direction.

In addition, assuming that the tactile sensor 100 is used by attaching it to a finger, it is preferable that each small electrode s is no larger than 4 mm x 4 mm in size, since multiple small electrodes s can be placed on the pad of the finger. The shape and size of the first electrode 11a and the second electrode 12a can be freely selected depending on the size of the object to be measured, and may be, for example, a square. In this case, the alignment of the first electrode 11a and the second electrode 12a with respect to the base material can be simplified, thereby reducing the difficulty of manufacturing.

Figure 4 is a partial cross-sectional view of the vicinity of the detection unit O and the detection unit Y in the tactile sensor. When no shear force is input, the shear force detection electrodes are offset from each other (partially not overlapping) in the direction of the detectable shear force, as shown in Figure 4. In addition, in the XY coordinate system with the detection unit O as the origin, the overlapping area of the corresponding shear force detection electrodes increases when a shear force is input in the positive direction, and decreases when a shear force is input in the negative direction. This allows the direction of shear and the shear force to be detected. In both the shear detection electrodes in the detection units X and Y, the sum of the overlapping area S1 of one small electrode s and the overlapping area S2 of the other small electrode s is equal to the overlapping area S of the pressure detection electrodes (the third electrode 13a and the fourth electrode 14a). Therefore, the output of the pressure detection electrode when pressure is input is equal to the output of the shear force detection electrode, and the output change when the small electrode s is offset in the direction of the shear force input and the overlapping area changes can be captured as a pure change in shear force.

Assuming that a shear force is input in the Y-axis direction, focusing on the electrodes of the detection unit Y, when the second electrode 12a is shifted in the positive direction in the Y-axis direction (to the right in FIG. 4), the overlapping area of the small electrodes s increases, and when the second electrode 12a is shifted in the negative direction in the Y-axis direction (to the left in FIG. 4), the overlapping area of the small electrodes s decreases. If the overlapping area when no shear force is input is 1, the amount of change in the overlapping area is allowed to be a minimum of 0.25 times in the decreasing direction and a maximum of 1.75 times in the increasing direction. At this time, since the length of the first electrode 11a in the Y-axis direction is longer than the second electrode 11a in the detection unit X, when a shear force is input in the Y-axis direction, the overlapping area of the small electrodes s in the detection unit X corresponding to the shear force in the X-axis direction does not change. Therefore, it is possible to extract the signal change of the shear force from only one electrode, improving the detection accuracy. The increase or decrease in the overlapping area of each small electrode s of the detection unit X when a shear force is input in the X-axis direction is the same. In addition, while the overlapping area of the shear force detection electrodes increases or decreases with the input of shear force, the overlapping area of the pressure detection electrodes does not change.

The fourth electrode 14a in the detection section O that contributes to pressure detection is formed larger than the third electrode 13a in a plan view. As a result, even when the first substrate 1 and the second substrate 2 are relatively displaced due to the input of shear force, the overlapping area of the electrodes changes only in the shear force detection electrodes (first electrode 11a and second electrode 12a), and the overlapping area of the pressure detection electrodes (third electrode 13a and fourth electrode 14a) does not change. Therefore, even if a shear force is input, the resistance value of the pressure detection electrodes does not change, and the detection accuracy of the shear force is improved. The third electrode 13a only needs to have the same area as one small electrode s of the shear force detection electrode, and can be the same shape (rectangle) as the small electrode s, for example, as shown in FIG. 2.

The electrodes are generally formed using a paste in which a precious metal powder of several micrometers to several tens of nanometers is mixed with a thermosetting resin, but carbon, aluminum, alloys, or mixtures of these may also be used. Since the lower the resistance value of the electrode, the better the resistance value detection by the pressure-sensitive layer described below, it is preferable that the volume resistance after formation is 5 x 10-5 Ω cm or less. Under these conditions, and taking into consideration cost and oxidation resistance, silver paste is suitable. The electrodes can be formed using a known printing method such as screen printing or gravure offset printing. They may also be formed by etching a plated or sputtered film. Although not shown, alignment marks may be attached to the substrate in order to form the electrodes. There are no particular restrictions on the shape or size of the marks.

Wiring (leads) are connected to the electrodes, and signals are taken from the ends of the leads (the lead ends are not shown in the figure). Any routing is acceptable for the paths along which the leads are formed as long as the leads do not cross along the way, but considering the miniaturization of the tactile sensor 100, it is preferable to gather the leads in one place at the end of the substrate. In addition, although not shown, the leads may be coated with an insulating material to protect them from scratches and moisture during the manufacturing process and use.

The electrodes may be formed with a raised center as shown in Figures 1 to 4. In this case, the resin layer on each electrode is also formed with a raised center along the surface of the electrode, but is shown in the figures as a flat surface for simplification. By making the center raised, it becomes easier for the upper and lower resin layers to come into contact with each other when the upper and lower electrodes are placed opposite each other.

(Resin Layer)
The first resin layer 11b, the second resin layer 12b, the third resin layer 13b, and the fourth resin layer 14b serve as detection layers. Since the tactile sensor 100 needs to detect a change in resistance between opposing electrodes, a conductive material is selected for the resin layers.

For example, a material having a resistivity of 0.05 Ωcm to 1000 Ωcm, more preferably 5 Ωcm to 500 Ωcm, can be used for the resin layer. If the resistivity is less than 0.05 Ωcm, it is difficult to distinguish it from the electrode in terms of electrical signal, making it difficult to detect the signal change. If the resistivity exceeds 1000 Ωcm, noise is likely to be carried in the detection signal, making it difficult to detect the signal change. Materials that can be used include conductive polymers such as polyethylenedioxythiophene, polyaniline, and polypyrrole, carbon pastes using graphite or carbon nanotubes, and materials in which the resistivity is adjusted by mixing these with an adjuster such as medium.

The first resin layer 11b, the second resin layer 12b, the third resin layer 13b, and the fourth resin layer 14b are formed so as to completely cover the first electrode 11a, the second electrode 12a, the third electrode 13a, and the fourth electrode 14a, respectively, and to be separated from the resin layers covering the other electrodes formed on the same substrate. If the resin layers on the same substrate come into contact with each other, noise will be generated and the detection accuracy will decrease, which is not preferable. The first resin layer 11b and the second resin layer 12b are formed to be the same size. This makes it possible to prevent the electrodes on one substrate from protruding from the resin layer formed on the electrodes of the other substrate when the first substrate 1 and the second substrate 2 are misaligned relative to each other, stabilizing signal detection.

The resin layer can be formed using a known printing method such as screen printing or a known coating method such as spray coating, but in order to selectively form it only near each electrode, it is preferable to use a printing method that can be formed in a single printing run.

The resin layer is shown in the figure as a flat surface for simplification, but in reality it is formed with a raised center along the surface of the electrode. By making the center raised, it becomes easier for the upper and lower resin layers to come into contact with each other when the upper and lower electrodes are placed opposite each other.

When a shear force is applied to the tactile sensor 100, the first resin layer 11b and the second resin layer 12b, which face each other vertically, are displaced relative to each other, and the resistance value between the first electrode 11a and the second electrode 12a also changes, so that the tactile sensor 100 can detect the shear force based on the change in resistance value. Therefore, if the deformation of the first resin layer 11b and the second resin layer 12b caused by the input of the shear force is large relative to the displacement between the first resin layer 11b and the second resin layer 12b, the noise dependent on the deformation also becomes large, and the detection accuracy decreases. Therefore, it is preferable that the resin layer has a higher modulus of elasticity (Young's modulus) than the materials selected for the first substrate 1 and the second substrate 2. As described later, polyimide (with a modulus of elasticity of about 3 GPa) is preferably used as the substrate, so that the modulus of elasticity of the resin layer can be 3 GPa or more, preferably 4 GPa or more.

(Base material)
The first substrate 1 and the second substrate 2 may be made of any material as long as they are flexible, and may be selected appropriately according to the conditions of the electrodes formed by printing ink, photolithography, and the use as a sensor, such as plastic films, such as PET, PEN, and polyimide, or paper. However, since the second substrate 2 is formed with slits 16 (described later), it is preferable to use polyimide as a material that is heat resistant and can withstand the formation of the slits 16. The first substrate 1 and the second substrate 2 may be made of different types or thicknesses.

(Fixed layer)
The fixing layer 15 bonds and fixes the opposing surfaces of the first substrate 1 and the second substrate 2 to each other, thereby maintaining the positional relationship of the opposed laminates. The fixing layer 15 is provided in an area surrounding all of the first laminate 11, the second laminate 12, the third laminate 13, and the fourth laminate 14. The shape of the fixing layer 15 is not particularly limited, but it is preferable that the outer shape is a square or a circle.

The material of the fixing layer 15 is not particularly limited, but it is preferable that the adhesive strength is high in order to prevent damage due to shear force or pressure. When the tactile sensor 100 is used, a force is applied only in the direction of pressing against the surface of the base material, but if the adhesive strength is weak, the sensor may be damaged by the bending stress applied to the sensor when removing the tactile sensor 100 from the measurement object. Therefore, the adhesive strength in the pressure direction is preferably 5N or more for a width of 25 mm. In addition, when removing the tactile sensor 100 from the measurement object, the shear direction component due to the bending stress is large, so the adhesive strength in the shear direction is preferably 80N/ ^cm2 . Since the adhesive strength also changes depending on the width of the fixing layer 15, the width may be determined so as to exceed these numerical values.

The thickness of the fixing layer 15 is set to be equal to or greater than the combined thickness of the stacks facing each other above and below. As a result, when the first stack 11 and the second stack 12 (the third stack 13 and the fourth stack 14) are placed facing each other, the fixing layer 15 serves as a fulcrum, and the second base material 2 sags, bringing the first resin layer 11b and the second resin layer 12b (the third resin layer 13b and the fourth resin layer 14b) into contact with each other (FIG. 5). In this state, no extra stress acts on the upper and lower resin layers, and it is possible to shift the second resin layer 12b relative to the first resin layer 11b by shear force. In addition, in order to sufficiently change the contact rate by pressure in detecting the pressure direction, it is desirable that the contact rate between the first resin layer 11b and the second resin layer 12b when no pressure is input is 0.01 to 0.1 times the contact rate when complete contact is set to 1. By inputting pressure from this state and increasing the contact rate, the resistance value change due to pressure can be obtained with good reproducibility. If the fixing layer 15 is made thinner than the combined thickness of the laminates facing each other above and below, the first laminate 11 and the second laminate 12, and the third laminate 13 and the fourth laminate 14 will always be in contact with each other, and a large load will be applied especially to the parts close to the fixing layer 15, resulting in a decrease in detection accuracy and damage. The amount of sagging can be approximated as the deflection of a beam with the fixing layer 15 as a fulcrum, and varies depending on the thickness and hardness of the substrate and the distance from the fulcrum. The amount of deflection D is expressed as D=WL^3/48EI, where L is the distance between the fulcrums, W is the load (the weight of the substrate in this case), I is the second moment of area, and E is the modulus of longitudinal elasticity.
As an example, when calculating a polyimide film having a length (distance between the fixing layers 15) of 1.7 cm, a thickness of 125 μm, a density of 1.4 g/cm ³ , and a Young's modulus of 3.5 GPa, the deflection amount D is 5.3 μm. In this case, if the thickness of the fixing layer 15 is made 5.3 μm thicker than the combined thickness of the stacks facing each other above and below, the upper and lower stacks will just come into contact with each other.

The fixing layer 15 may be formed by patterning by printing an adhesive, or by punching out double-sided tape with a Pinnacle (registered trademark) blade or the like and attaching it to the position where the fixing layer 15 is to be formed. Double-sided tape is preferably used when it is desired to avoid applying unnecessary thermal load to the substrate or to avoid uneven adhesion due to printing variations.

This section explains how to measure pressure and shear force using the tactile sensor 100.

Figure 6 is a partial cross-sectional view of the laminated body of the tactile sensor during pressure measurement. In addition, in Figure 6, the outline of the resin layer is shown in accordance with the shape of the electrode.

The pressure detection electrode (third electrode 13a) on the first substrate 1 and the pressure detection electrode (fourth electrode 14a) on the second substrate 2 are connected via a pair of third and fourth resin layers 13b and 14b. When there is no load in the pressure direction, the contact area between the third and fourth resin layers 13b and 14b is small, so the electrical resistance between the electrodes is large (see FIG. 6(a)). When pressure is applied, the contact area between the third and fourth resin layers 13b and 14b increases (see FIG. 6(b)). When the contact area increases, the conductive path between the upper and lower electrodes increases, so the electrical resistance decreases. Therefore, pressure can be detected based on the electrical resistance between the pressure detection electrodes.

Figure 7 is a partial cross-sectional view of the tactile sensor near the laminate when measuring shear force. More specifically, Figure 7(a) shows the state of the tactile sensor 100 when no shear force is applied, and Figure 7(b) shows the state of the tactile sensor 100 when a shear force is applied. In Figure 7, the outer shapes of the electrodes and resin layer are shown as rectangular shapes.

In the state of FIG. 7(a), the first electrode 11a and the second electrode 12a are shifted so that they overlap only partially in a plan view. When a shear force is input from the state of FIG. 7(a) to the right of the paper, the overlapping area between the first electrode 11a and the second electrode 12a increases and the electrical resistance between the electrodes decreases, so that the shear force can be measured based on this change in resistance. In this embodiment, the structure is such that the overlapping area between the first electrode 11a and the second electrode 12a increases when a shear force is input, but it may also be such that it decreases. In this case, the initial positions of the first electrode 11a and the second electrode 12a can be such that the first electrode 11a and the second electrode 12a completely overlap.

(slit)
The slits 16 are formed by punching the surface of the second substrate 2, and are provided inside the fixing layer 15 in the second substrate 2 and at a position spaced apart from the second laminate 12. By forming the slits 16 in the second substrate 2, movement of the second substrate 2 in a predetermined direction can be reduced.

For example, as shown in FIG. 1 and FIG. 3, four slits 16 are provided along each side of a rectangular region surrounding the second laminate 12 and the fourth laminate 14. The tactile sensor 100 detects a shear force by the relative displacement of the first electrode 11a and the second electrode 12a with the input of a shear force. However, since it is necessary to bond the first substrate 1 and the second substrate 2, the fixing layer 15 is provided, which may hinder the displacement of the first electrode 11a and the second electrode 12a. Therefore, by providing the slits 16 inside the fixing layer 15, it is possible to easily move the region inside the fixing layer 15 in the direction of the input shear force. Specifically, as shown in FIG. 8, when a shear force is input in the X-axis direction, one of the two slits 16 extending in the Y-axis direction is deformed so as to widen and the other is narrowed, so that the second electrode 12a is easily moved in the shear direction. FIG. 8 shows a state in which a shear force is input in the positive direction of the X-axis (to the right of the paper).

When four slits 16 are provided along each side of a rectangular region surrounding the second laminate 12 and the fourth laminate 14 as in this embodiment, it is preferable to provide non-punched portions (non-punched portions) at the four corners of the rectangle as shown in FIG. 3. If non-punched portions are formed at the portions that correspond to the sides of the rectangle, the base material that remains unpunched will prevent rubbing. In addition, by making the non-punched portions symmetrical, space is secured for routing the leads, and the base material is supported by the connected portions, allowing it to return to its initial position when the shear force is removed.

As described above, if the overlap area of the small electrode s when no shear force is applied is 1, the change in the overlap area is allowed to be a minimum of 0.25 times in the decreasing direction and a maximum of 1.75 times in the increasing direction, but it is preferable that the slit width d1 is equal to or greater than the allowable change in the overlap area of the small electrode s. For example, if the overlap width of the small electrode s when no load is applied is 1 mm, then by forming a slit 16 with an overlap width of 1 mm x 0.75 = 750 μm width, a movement amount of 750 μm can be ensured, and an area change can be obtained favorably.

The distance d2 between the slit 16 and the second laminate 12 and the fourth laminate 14 is equal to the width of the slit 16 (d1 = d2). If the slit 16 is too close to the lead, there is a concern that it may interfere with and damage the lead when the second substrate 2 deforms. If it is too far away, the effect of the slit 16 cannot be obtained and it becomes difficult to move the second substrate 2.

The method for making the slits 16 can be selected depending on the width of the slits 16. If the width of the slits 16 is 0.6 mm or more, punching with a pinnacle blade is effective, and laser cutting can be selected to form a smaller slit. Also, although the slits 16 are shown as angular in the figure, it is preferable to process the edges of the slits 16 in a curved shape. If the shape has corners, there is a risk that when the second substrate 2 moves due to the repeated input of shear forces, stress will concentrate at the corners of the slits, causing the second substrate 2 to tear.

As described above, the tactile sensor 100 according to this embodiment has four slits 16 provided along each side of a rectangular region surrounding the second laminate 12 and the fourth laminate 14 of the second substrate 2. Therefore, when a shear force is input, the slits 16 deform according to the direction of the shear force, making it easier for the second electrode 12a to move in the shear direction. In addition, because the slits 16 are provided inside the fixing layer 15, it is possible to prevent the fixing layer 15 from impeding the movement of the second substrate 2 due to the shear force.

In addition, since the slits 16 are provided, the fixing layer 15 can sufficiently secure the fixing strength between the substrates, while preventing the second substrate 2 from being hindered from shifting due to the fixing layer 15, resulting in a tactile sensor 100 with high detection accuracy.

Second Embodiment
The tactile sensor according to the second embodiment will be described with a focus on the differences from the first embodiment. The tactile sensor 200 according to the second embodiment is different from the tactile sensor 100 according to the first embodiment in the position at which the slit 16 is formed. FIG. 9 is a schematic diagram showing the schematic configuration of the tactile sensor according to the second embodiment of the present invention, and more specifically, FIG. 9(a) is a plan view of the tactile sensor, and FIG. 9(b) is a cross-sectional view taken along the line D-D' shown in FIG. 9(a). FIG. 10 is a partial schematic diagram of the second substrate side of the tactile sensor, and more specifically, FIG. 10(a) is a partial plan view of the second substrate side of the tactile sensor, and FIG. 10(b) is a cross-sectional view taken along the line E-E' shown in FIG. 10(a). FIG. 11 is a diagram showing the tactile sensor in a state in which a shear force is input.

The second substrate 2 is provided with a pair of slits 16a extending in the Y-axis direction with the detection unit X (first laminate 11 and second laminate 12) in between, and a pair of slits 16b extending in the X-axis direction with the detection unit Y (first laminate 11 and second laminate 12) in between. With this configuration, the second laminate 12 of the detection unit X that detects the shear force in the X-axis direction is easily movable in the X-axis direction, but its movement in the Y-axis direction is restricted. Also, the second laminate 12 of the detection unit Y that detects the shear force in the Y-axis direction is easily movable in the Y-axis direction, but its movement in the X-axis direction is restricted (FIG. 11). Therefore, compared to the first embodiment, the electrode corresponding to the direction in which the shear force is input can be shifted more selectively. Also, in this embodiment, the slits 16 are not formed except near the shear force detection electrode (second electrode 12a), so that the pressure detection electrode (fourth electrode 14a) can be suppressed from moving, and further, the strength of the second substrate 2 can be prevented from decreasing due to punching. It also allows for greater freedom in handling the lead.

Example 1
A 125 μm polyimide film (Toray: Kapton 500V) was used as the first substrate 1, and the first electrode 11a and the third electrode 13a shown in FIG. 2 were produced within a range of 7 mm × 7 mm by printing using silver paste. At this time, the pressure detection electrode was produced in a square shape. In addition, the shear force detection electrodes were each produced in a U-shape, and the dimensions of the rectangular small electrodes s were 0.5 mm wide and 3.2 mm long, and the distance between the small electrodes s was 2.5 mm. In addition to the first electrode 11a and the third electrode 13a, the leads were also 0.03 mm wide and arranged so as not to cross each other. The average thickness of the first electrode 11a, the third electrode 13a, and the leads was 5.5 μm.

Next, a carbon ink JELCON CH-N manufactured by Jujo Chemical was printed on the first electrode 11a and the third electrode 13a to form a first resin layer 11b and a third resin layer 13b, producing the first laminate 11 and the third laminate 13. The film thickness of CH-N was 6 μm on average, and the film thickness on the first electrode 11a and the third electrode 13a was 12.5 μm.

A 125 μm polyimide film (Toray: Kapton 500V) was used as the second substrate 2, and the second electrode 12a, fourth electrode 14a, and leads shown in FIG. 3 were produced by printing using silver paste.

Next, a carbon ink JELCON CH-N manufactured by Jujo Chemical was printed on the second electrode 12a and the fourth electrode 14a to form a second resin layer 12b and a fourth resin layer 14b, producing the second laminate 12 and the fourth laminate 14. The film thickness of CH-N was 6 μm on average, and the film thickness on the second electrode 12a and the fourth electrode 14a was 12.5 μm.

Next, the second substrate 2 was punched by laser processing to form a slit 16 with a width of approximately 200 μm (Figure 3). The slit 16 was formed at a position 200 μm away from the edge of the second laminate 12.

Next, the first substrate 1 and the second substrate 2 were bonded and fixed via the fixing layer 15 so that the first resin layer 11b and the second resin layer 12b, and the third resin layer 13b and the fourth resin layer 14b faced each other, thereby obtaining the tactile sensor 100 according to Example 1 (Figure 1). At this time, the overlap width between the small electrodes s of the first electrode 11a and the small electrodes s of the second electrode 12a was 250 μm in plan view. In addition, the fixing layer 15 was made of Teraoka double-sided tape 707#4 with a thickness of 30 μm, which was punched into a square shape with a width of 1.5 mm, and was positioned so that each side of the fixing layer 15 was 1.4 cm from the center of the substrate.

When pressure was applied to this sensor with a finger, a change in the resistance value of the pressure detection electrode was confirmed according to the force applied. In addition, when a shear force was applied to this sensor with a finger, the second substrate 2 shifted in the direction of the input shear force, and a corresponding change in the resistance value of the shear force detection electrode was confirmed. When the input of the shear force was stopped, the substrate returned to its original position.

Example 2
A 125 μm polyimide film (Toray: Kapton 500V) was used as the first substrate 1, and the first electrode 11a and the third electrode 13a shown in FIG. 2 were produced within a range of 7 mm × 7 mm by printing using silver paste. At this time, the pressure detection electrode was produced in a square shape. In addition, the shear force detection electrodes were each produced in a U-shape, and the dimensions of the rectangular small electrodes s were 0.5 mm wide and 3.2 mm long, and the distance between the small electrodes s was 2.5 mm. In addition to the first electrode 11a and the third electrode 13a, the leads were also 0.03 mm wide and arranged so as not to cross each other. The average thickness of the first electrode 11a, the third electrode 13a, and the leads was 5.5 μm.

Next, a carbon ink JELCON CH-N manufactured by Jujo Chemical was printed on the first electrode 11a and the third electrode 13a to form a first resin layer 11b and a third resin layer 13b, producing the first laminate 11 and the third laminate 13. The film thickness of CH-N was 6 μm on average, and the film thickness on the first electrode 11a and the third electrode 13a was 12.5 μm.

A 125 μm polyimide film (Toray: Kapton 500V) was used as the second substrate 2, and the second electrode 12a, fourth electrode 14a, and leads shown in FIG. 3 were produced by printing using silver paste.

Next, the second electrode 12a and the fourth electrode 14a were printed with carbon ink JELCON CH-N manufactured by Jujo Chemical to form the second resin layer 12b and the fourth resin layer 14b, thereby producing the second laminate 12 and the fourth laminate 14. The film thickness of CH-N was 6 μm on average, and the film thickness in the parts above the second electrode 12a and the fourth electrode 14a was 12.5 μm.

Next, the second substrate 2 was punched out by laser processing to form a pair of slits 16a extending in the Y-axis direction with the detection unit X in between, and a pair of slits 16b extending in the X-axis direction with the detection unit Y in between (Figure 10). The slits 16 were formed at a position 200 μm away from the end of the second laminate 12, with a slit width of approximately 200 μm.

Next, the first substrate 1 and the second substrate 2 were bonded and fixed via the fixing layer 15 so that the first resin layer 11b and the second resin layer 12b, and the third resin layer 13b and the fourth resin layer 14b faced each other, thereby obtaining the tactile sensor 100 according to Example 2 (FIG. 9). At this time, the overlap width between the small electrodes s of the first electrode 11a and the small electrodes s of the second electrode 12a was 250 μm in plan view. In addition, the fixing layer 15 was made of Teraoka double-sided tape 707#4 with a thickness of 30 μm, which was punched into a square shape with a width of 1.5 mm, and was positioned so that each side of the fixing layer 15 was 1.4 cm from the center of the substrate.

When pressure was applied to this sensor with a finger, a change in the resistance value of the pressure detection electrode was observed depending on the force applied. When a shear force was applied to this sensor with a finger, the shear force detection electrode of detection unit X shifted up and down in response to the shear force in the X-axis direction, and a change in the resistance value was observed. Additionally, the shear force detection electrode of detection unit Y shifted up and down in response to the shear force in the Y-axis direction, and a change in the resistance value was observed. When the input of shear force was stopped, the electrodes returned to their original positions.

(Comparative Example 1)
A 125 μm polyimide film (Toray: Kapton 500V) was used as the first substrate 1, and the first electrode 11a and the third electrode 13a shown in FIG. 2 were produced within a range of 7 mm × 7 mm by printing using silver paste. At this time, the pressure detection electrode was produced in a square shape. In addition, the shear force detection electrodes were each produced in a U-shape, and the dimensions of the rectangular small electrodes s were 0.5 mm wide and 3.2 mm long, and the distance between the small electrodes s was 2.5 mm. In addition to the first electrode 11a and the third electrode 13a, the leads were also 0.03 mm wide and arranged so as not to cross each other. The average thickness of the first electrode 11a, the third electrode 13a, and the leads was 5.5 μm.

Next, a carbon ink JELCON CH-N manufactured by Jujo Chemical was printed on the first electrode 11a and the third electrode 13a to form a first resin layer 11b and a third resin layer 13b, producing the first laminate 11 and the third laminate 13. The film thickness of CH-N was 6 μm on average, and the film thickness on the first electrode 11a and the third electrode 13a was 12.5 μm.

A 125 μm polyimide film (Toray: Kapton 500V) was used as the second substrate 2, and the second electrode 12a, fourth electrode 14a, and leads shown in FIG. 3 were produced by printing using silver paste.

Next, a carbon ink JELCON CH-N manufactured by Jujo Chemical was printed on the second electrode 12a and the fourth electrode 14a to form a second resin layer 12b and a fourth resin layer 14b, producing the second laminate 12 and the fourth laminate 14. The film thickness of CH-N was 6 μm on average, and the film thickness on the second electrode 12a and the fourth electrode 14a was 12.5 μm.

Next, the first substrate 1 and the second substrate 2 were bonded and fixed via the fixing layer 15 so that the first resin layer 11b and the second resin layer 12b, and the third resin layer 13b and the fourth resin layer 14b faced each other, thereby obtaining the tactile sensor 100 according to Comparative Example 1. At this time, the overlap width in plan view between the small electrodes s of the first electrode 11a and the small electrodes s of the second electrode 12a was 250 μm. In addition, the fixing layer 15 was made of Teraoka double-sided tape 707#4 with a thickness of 30 μm, which was punched into a square shape with a width of 1.5 mm, and was positioned so that each side of the fixing layer 15 was 1.4 cm from the center of the substrate.

When pressure was applied to this sensor with a finger, a change in the resistance value of the pressure detection electrode was confirmed in accordance with the input force. However, when a shear force was applied to this sensor with a finger, no shift occurred in the second substrate 2, and no change in the resistance value of the corresponding shear force detection electrode could be confirmed.

The present invention can be applied to tactile sensors that measure shear forces.

1 First substrate 2 Second substrate 11 First laminate 11a First electrode 11b First resin layer 12 Second laminate 12a Second electrode 12b Second resin layer 13 Third laminate 13a Third electrode 13b Third resin layer 14 Fourth laminate 14a Fourth electrode 14b Fourth resin layer 15 Fixing layer 16 Slit 16a Slit 16b Slit 100 Tactile sensor 200 Tactile sensor O: Detection section X: Detection section Y: Detection section
bY: Detecting unit s: Small electrode

Claims (7)

A first substrate;
a first laminate provided on one surface of the first base material, the first laminate having, in this order from the first base material side, a first electrode and a first resin layer having electrical conductivity;
a second substrate facing the one surface of the first substrate;
a second laminate provided on a surface of the second base material facing the first base material at a position facing the first laminate, the second laminate including, in order from the second base material side, a second electrode and a second resin layer having electrical conductivity;
a fixing layer provided so as to surround the first laminate and the second laminate, and bonding and fixing opposing surfaces of the first base material and the second base material to each other,
a shear force in a predetermined direction can be detected based on an electrical resistance value between the first electrode and the second electrode corresponding to an overlapping area of the first resin layer and the second resin layer,
A tactile sensor, wherein a slit is provided on the second substrate inside the fixing layer and at a position spaced apart from the second laminate, for reducing movement of the second substrate in the predetermined direction. Two of the first stacks and two of the second stacks,
a shear force in a first direction can be detected using one of the first stacks and one of the second stacks facing the first stack, and a shear force in a second direction perpendicular to the first direction can be detected using the other of the first stacks and the other of the second stack facing the first stack,
The tactile sensor according to claim 1 , wherein the second base material has four slits provided along each side of a rectangular region surrounding the two second laminates. Two of the first stacks and two of the second stacks,
a shear force in a first direction can be detected using one of the first stacks and one of the second stacks facing the first stack, and a shear force in a second direction perpendicular to the first direction can be detected using the other of the first stacks and the other of the second stack facing the first stack,
The tactile sensor according to claim 1 , wherein the second substrate is provided with a pair of slits extending in the second direction, sandwiching one side of the second laminate, and a pair of slits extending in the first direction, sandwiching the other side of the second laminate. a third laminate provided on one surface of the first base material, the third laminate having, in this order from the first base material side, a third electrode and a third resin layer having electrical conductivity;
a fourth laminate provided on a surface of the second base material facing the first base material at a position facing the third laminate, the fourth laminate having, in order from the second base material side, a fourth electrode and a fourth resin layer having electrical conductivity;
A tactile sensor according to any one of claims 1 to 3, capable of detecting pressure based on an electrical resistance value between the third electrode and the fourth electrode that corresponds to an overlapping area of the third resin layer and the fourth resin layer. The tactile sensor according to claim 4, wherein the contact rate between the first resin layer and the second resin layer when no external force is applied to the tactile sensor is 0.01 to 0.1 times the contact rate when the first resin layer and the second resin layer are in complete contact. The tactile sensor according to claim 4, wherein the first resin layer and the second resin layer have a higher modulus of elasticity than the first base material and the second base material. The tactile sensor according to claim 4 , wherein the fixing layer has an adhesive strength of 5 N/25 mm or more and a shear adhesive strength of 80 N/cm ² .

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