Sensor device and electronic instrument

Abstract

A sensor device according to one embodiment of the present technology is provided with a sensor sheet, a reference electrode layer, a deformation layer, a surface layer, and a control unit. The sensor sheet is configured to be capable of detecting a pressure distribution. The reference electrode layer is disposed so as to face one surface of the sensor sheet and is connected to a reference potential. The deformation layer is disposed between the sensor sheet and the reference electrode layer, and is composed of a flexible material. The surface layer has an input operation surface, is disposed on the other surface of the sensor sheet, and is composed of a non-conductive material that has a thickness larger than that of the deformation layer. The control unit sets a plurality of thresholds for determining the magnitude of a pressing force acting on the input operation surface in multiple stages on the basis of an output of the sensor sheet.

Description

Sensor device and electronic device

[0001] The present technology relates to a sensor device and an electronic device that can detect a touch operation and a pressing operation.

[0002] For example, Patent Document 1 discloses a capacitive sensor capable of detecting touch operations and pressing operations, which comprises a ground electrode, a first electrode provided on the ground electrode and consisting of a plurality of first sub-electrodes, a deformation layer provided between the installation electrode and the first electrode, a second electrode provided on the first electrode and consisting of a plurality of second sub-electrodes, and a surface layer provided on the second electrode and having an operation surface.

[0003] WO2018 / 025690 publication

[0004] In recent years, there has been a demand for this type of capacitive sensor to have a sensor structure that can separate the touch function and the pressure-sensing function, divide the pressure-sensing function into multiple stages, and assign different functions depending on the amount of pressure applied.To achieve this, it is necessary for the pressure sensitivity when a finger presses the operation surface to be sufficiently greater than the touch sensitivity when a finger touches the operation surface.

[0005] In view of the above circumstances, an object of the present technology is to provide a sensor device and an electronic device that can make pressure sensitivity sufficiently greater than touch sensitivity and divide the pressure-sensing function into multiple stages.

[0006] A sensor device according to one aspect of the present technology includes a sensor sheet, a reference electrode layer, a deformation layer, a surface layer, and a control unit. The sensor sheet is configured to detect a pressure distribution. The reference electrode layer is disposed facing one surface of the sensor sheet and connected to a reference potential. The deformation layer is disposed between the sensor sheet and the reference electrode layer and is made of a flexible material. The surface layer has an input operation surface, is disposed on the other surface of the sensor sheet, and is made of a non-conductive material that is thicker than the deformation layer. The control unit is capable of executing a first detection process to detect contact of a detection object with the input operation surface and a second detection process to detect a pressing force of the detection object on the input operation surface based on an output of the sensor sheet, and the second detection process sets multiple thresholds for determining the magnitude of the pressing force in multiple stages.

[0007] According to the present technology, since the surface layer is configured to have a thickness greater than that of the deformation layer, the pressure sensitivity can be made sufficiently greater than the touch sensitivity, and the pressure sensitivity function can be divided into multiple stages.

[0008] The surface layer typically has a thickness at least twice the thickness of the deformation layer.

[0009] The surface layer may be made of a material having a higher elastic modulus than the deformation layer.

[0010] The sensor sheet may have a sensor electrode layer having a flexible substrate and a plurality of capacitance elements arranged in a matrix on one surface of the substrate, and each of the plurality of capacitance elements may have a comb-like electrode pair facing each other in a direction parallel to the one surface of the substrate.

[0011] The sensor electrode layer may be disposed on a surface of the sensor sheet facing the reference electrode layer.

[0012] The sensor device may further include a support layer, which is arranged between the reference electrode layer and an installation surface on which the sensor device is installed, and is made of a flexible material.

[0013] The surface layer may have an outer layer portion that forms the input operation surface, and an inner layer portion that is disposed between the outer layer portion and the sensor sheet and has a different elastic modulus from that of the outer layer portion.

[0014] The deformation layer may include a first deformation layer arranged on one side of the sensor sheet, and a second deformation layer arranged between the first deformation layer and the reference electrode layer and having a different elastic modulus than the first deformation layer.

[0015] The surface layer may have a flat plate portion that forms the input operation surface, and legs that are provided on the periphery of the flat plate portion and supported on an installation surface on which the sensor device is installed.

[0016] The control unit may include a determination unit that determines to which of a plurality of sections defined by the plurality of threshold values ​​the pressure belongs, and the plurality of threshold values ​​may include a first pressure sensitivity that is at least twice as sensitive as a touch sensitivity that is a detection sensitivity of the sensor sheet measured when a detection object touches the input operation surface, and a second pressure sensitivity that is at least three times as sensitive as the touch sensitivity.

[0017] The plurality of thresholds may further include a third pressure sensitivity that is four or more times as sensitive as the touch sensitivity.

[0018] The control unit may further include a threshold setting section that is capable of individually adjusting the plurality of thresholds.

[0019] The threshold setting unit may correct the first pressure sensitivity and the second pressure sensitivity according to an operation area of ​​the detection target on the input operation surface.

[0020] According to one aspect of the present technology, an electronic device includes a sensor device. The sensor device includes a sensor sheet, a reference electrode layer, a deformation layer, a surface layer, and a control unit. The sensor sheet is configured to detect a pressure distribution. The reference electrode layer is disposed facing one surface of the sensor sheet and connected to a reference potential. The deformation layer is disposed between the sensor sheet and the reference electrode layer and is made of a flexible material. The surface layer has an input operation surface, is disposed on the other surface of the sensor sheet, and is made of a non-conductive material that is thicker than the deformation layer. The control unit is capable of executing a first detection process to detect contact of a detection object with the input operation surface and a second detection process to detect a pressing force of the detection object on the input operation surface based on an output from the sensor sheet, and sets multiple thresholds in the second detection process to determine the magnitude of the pressing force in multiple stages.

[0021] 1 is a schematic side cross-sectional view showing a configuration of a sensor device according to an embodiment of the present technology. FIG. 2 is a schematic plan view showing a configuration example of a sensor sheet in the sensor device. FIG. 3 is a schematic plan view showing a configuration example of a sensing unit in the sensor sheet. FIG. 4 is a schematic side cross-sectional view showing another configuration example of the sensor device. FIG. 5 is a schematic side cross-sectional view showing another configuration example of the sensor device. FIG. 6 is a schematic side cross-sectional view showing another configuration example of the sensor device. FIG. 7 is a functional block diagram of a control unit constituting the sensor device. FIG. 8 is an explanatory diagram showing an example of the relationship between touch sensitivity and pressure sensitivity. FIG. 9 is an explanatory diagram showing the relationship between touch sensitivity and pressure sensitivity set in the sensor device. FIG. 10 is an experimental result showing the dependency of the thickness of the surface layer on displacement sensitivity. FIG. 11 is an experimental result showing the dependency of the structure (thickness, flexibility) of the surface layer on load sensitivity. FIG. 11 is a load-displacement curve when the input operation surface of the sensor device is pressed. FIG. 22 is a diagram showing the relationship between the displacement amount and maximum sensitivity in the sensor device. FIG. 23 is a schematic diagram showing operation areas on the input operation surface. FIG. 24 is a diagram showing an example of a load-displacement curve in each of the operation areas. FIG. 24 is a look-up table showing the relationship between each of the operation areas and a correction coefficient. FIG. 25 is an explanatory diagram showing the thicknesses of the deformation layer and the surface layer of the sensor device shown in FIG. 10 is a simulation result showing the relationship between the ratio of the thickness of the deformation layer to the surface layer and the maximum deformation rate of the deformation layer.

[0022] Hereinafter, embodiments of the present technology will be described with reference to the drawings.

[0023] Fig. 1 is a schematic side cross-sectional view showing a configuration of a sensor device 100 according to an embodiment of the present technology. Fig. 2 is a schematic plan view showing a configuration example of a sensor sheet 10 in the sensor device 100.

[0024] 1 and 2, the X-axis direction and the Y-axis direction are parallel to the input operation surface S (hereinafter also referred to as in-plane directions), and the Z-axis direction is perpendicular to the input operation surface S (hereinafter also referred to as vertical direction). In addition, the upper side in Fig. 1 corresponds to the front side to which an external force is applied, and the lower side corresponds to the opposite back side.

[0025] [Overall Configuration of Sensor Device] The sensor device 100 has a flat plate structure with a substantially rectangular planar shape. The planar shape of the sensor device 100 is not particularly limited and may be set appropriately depending on the shape of the location where the sensor device 100 is to be installed. For example, the planar shape of the sensor device 100 may be a polygon other than a rectangle, a circle, an ellipse, or the like.

[0026] 1 , the sensor device 100 includes a pressure sensor 1 and a control unit 60. The pressure sensor 1 is configured as a laminate having a sensor sheet 10, a reference electrode layer 20, a deformation layer 30, and a surface layer 40.

[0027] The sensor device 100 is configured as an input device mounted on, for example, an electronic device. Examples of the electronic device include information processing devices such as tablet PCs, audio devices such as headphones and earphones, imaging devices such as digital still cameras and video cameras, and game devices.

[0028] (Sensor Sheet) The sensor sheet 10 is composed of a flexible printed wiring board or the like having a base material 11 and a sensor electrode layer 12. The sensor electrode layer 12 has a plurality of capacitance elements (sensing units 13) arranged in a matrix on the back surface of the base material 11 facing the reference electrode layer 20, and is configured to be able to detect the pressure distribution acting on the input operation surface S.

[0029] 2, the substrate 11 has a main body 111 having a rectangular planar shape and an extension 112 extending outward from a portion of the periphery of the main body 111. The planar shape of the substrate 11 is not limited to a rectangle, and any shape can be adopted. The material of the substrate 11 is not particularly limited as long as it is a flexible insulating material, and examples of the material that can be used include polymer resins such as polyethylene terephthalate, polyimide, polycarbonate, and acrylic resin.

[0030] The sensing units 13 correspond to nodes of the sensor sheet 10 and are regularly arranged in a matrix at predetermined intervals in both the vertical and horizontal directions (vertical: Y-axis direction, horizontal: X-axis direction). In the example shown in FIG. 2, the number of sensing units 13 (number of nodes) is 9 x 9 (vertical x horizontal), totaling 81. The number of sensing units 13 can be changed as appropriate. The sensing unit 13 is composed of a capacitance element (detection element) capable of detecting a change in distance from the reference electrode layer 20 as a change in capacitance.

[0031] 3 is a schematic plan view showing an example of the configuration of the sensing unit 13. The sensing unit 13 has an electrode pair including a comb-teeth-shaped pulse electrode 281 and a comb-teeth-shaped sense electrode 282 that face each other in a direction parallel to the rear surface of the substrate 11 (the Y-axis direction in FIG. 3). The pulse electrode 281 and the sense electrode 282 are arranged so that the teeth of each comb face each other, and each sensing unit 28 is composed of an area (node ​​area) where one comb tooth is arranged between the other comb tooth.

[0032] Each pulse electrode 281 is connected to a wiring portion 281a extending in the Y-axis direction, and each sense electrode 282 is connected to a wiring portion 282a extending in the X-axis direction. The wiring portions 281a are arranged in the X-axis direction on the back surface of the substrate 11, and the wiring portions 282a are arranged in the Y-axis direction on the front surface of the substrate 11. Each sense electrode 282 is electrically connected to the wiring portion 282a via a through-hole 283 provided in the substrate 29.

[0033] Alternatively, the wiring portion 281a and the wiring portion 282a may both be formed on the back surface of the substrate 11, and their intersections may be insulated from each other using, for example, jumper members. By forming the pulse electrode 281 (wiring portion 281a) and the sense electrode 282 (wiring portion 282a) on the back surface of the substrate 11 (the surface facing the reference electrode layer 20), the distance between each of these electrodes 281, 282 and the input operation surface S increases by the thickness of the substrate 11, so that the touch sensitivity can be kept low relative to the pressure sensitivity. Note that touch sensitivity and pressure sensitivity will be described later.

[0034] The sensor electrode layer 30 may have a ground line. The ground line is provided, for example, on the outer periphery of the sensor electrode layer 12 or in a portion where the wiring portions 281a and 282a run parallel to each other.

[0035] The structure of the sensing unit 13 is not limited to the above example, and any structure may be used. For example, the sensor electrode layer 12 may be formed of a laminate of a first electrode sheet having a lattice-shaped first electrode pattern extending in the X-axis direction and a second electrode sheet having a lattice-shaped second electrode pattern extending in the Y-axis direction. In this case, the sensing unit 13 is formed at the intersection of the first electrode pattern and the second electrode pattern.

[0036] (Reference Electrode Layer) The reference electrode layer 20 is disposed opposite one surface (rear surface) of the sensor sheet 10. The reference electrode layer 20 is connected to a reference potential. In this embodiment, the reference electrode layer 20 is a so-called ground electrode, and is connected to the ground potential as the reference potential. The reference electrode layer 20 is flexible, and its thickness is, for example, approximately 0.05 mm to 0.5 mm. Examples of materials that can be used for the reference electrode layer 20 include inorganic conductive materials, organic conductive materials, and conductive materials containing both inorganic and organic conductive materials.

[0037] Examples of inorganic conductive materials include metals such as aluminum, copper, and silver, alloys such as stainless steel, and metal oxides such as zinc oxide and indium oxide. Examples of organic conductive materials include carbon materials such as carbon black and carbon fiber, and conductive polymers such as substituted or unsubstituted polyaniline and polypyrrole. The reference electrode layer 20 may be composed of a thin metal plate such as stainless steel or aluminum, conductive fiber, or conductive nonwoven fabric. The reference electrode layer 20 may be formed on a plastic film by a method such as vapor deposition, sputtering, adhesion, or coating.

[0038] (Deformation Layer) The deformation layer 30 is disposed between the sensor sheet 10 and the reference electrode layer 20. The deformation layer 30 has a thickness of, for example, about 100 μm to 1000 μm, and in this embodiment, is 500 μm or less.

[0039] The lower limit of the thickness of deformation layer 30 is not particularly limited as long as it is greater than 100 μm, but may be, for example, 150 μm or more, 200 μm or more, 250 μm or more, 300 μm or more, etc. The upper limit of the thickness of deformation layer 30 is not particularly limited as long as it is 1000 μm or less, but may be, for example, 950 μm or more, 900 μm or less, 850 μm or less, 800 μm or less, etc.

[0040] The weight per unit area of ​​the deformation layer 30 is, for example, 50 mg / cm ２ By setting the thickness and basis weight of the deformation layer 30 within this range, the detection sensitivity of the pressure sensor 100 in the vertical direction can be improved.

[0041] The deformation layer 30 is made of a flexible material that is elastically deformable in response to an external force, such as a foam material (elastic foam), rubber, gel, nonwoven fabric, nanofiber, etc. When an external force is applied perpendicularly to the sensor sheet 10, the deformation layer 30 elastically deforms in response to the external force, and the reference electrode layer 20 approaches the sensor electrode layer 12. At this time, the capacitance between the pulse electrode 281 and the sense electrode 282 in the sensing unit 13 changes, and the sensing unit 13 can detect this change in capacitance as a pressure value.

[0042] To facilitate deformation in the Z-axis direction, the deformation layer 30 may be configured with a patterning structure including, for example, a columnar structure. This patterning structure can be a matrix, stripe, mesh, radial, geometric, or spiral structure.

[0043] The deformation layer 30 is bonded to the sensor sheet 10 and the reference electrode layer 20 via a bonding material. As the bonding material, for example, one or more adhesives selected from the group consisting of an acrylic adhesive, a silicone adhesive, and a urethane adhesive can be used.

[0044] The deformation layer 30 may be a laminated structure of multiple materials with different elastic moduli (hardness). Figure 4 is a schematic cross-sectional side view of a sensor device 101 including a deformation layer 30 configured as a laminated structure of a first deformation layer 31 and a second deformation layer 32.

[0045] The first deformation layer 31 is disposed on the rear surface of the sensor sheet 10. The second deformation layer 32 is disposed between the first deformation layer 31 and the reference electrode layer 20 and has a different elastic modulus from that of the first deformation layer 31. The first deformation layer 31 may be made of a material having a higher elastic modulus than the second deformation layer 32, or may be made of a material having a lower elastic modulus than the second deformation layer 32. The thicknesses of the first deformation layer 31 and the second deformation layer 32 are not particularly limited, and they may be formed to have the same thickness or different thicknesses.

[0046] By constructing the deformation layer 30 from a laminate of flexible materials of different hardness, it becomes possible to set a threshold value for pressure sensitivity by utilizing the difference between the amount of change in capacitance (load sensitivity) of the sensing unit 13 when the first deformation layer 31 is deformed and the amount of change in capacitance (load sensitivity) of the sensing unit 13 when the second deformation layer 32 is deformed.

[0047] (Surface Layer) The surface layer 40 functions as an outer layer of the sensor device 100 and has an input operation surface S that is operated by a user. The input operation surface S also functions as a detection surface that comes into contact with a detection target of the sensor device 100 (such as a user's finger) and detects touch operations and pressing operations on the sensor device 100 by the detection target.

[0048] The surface layer 40 is disposed on the other surface (front surface) of the sensor sheet 10. The surface layer 40 is made of a non-conductive material. Examples of non-conductive materials include electrically insulating materials such as synthetic resin, rubber, foam (elastic foam), and non-woven fabric. Note that, as long as the entire surface layer 40 is electrically insulating, a composite material in which conductive particles such as metal particles or metal flakes are mixed into a synthetic resin material may also be used.

[0049] The surface layer 40 is not particularly limited as long as it can detect a touch operation on the input operation surface S, and in this embodiment, the thickness of the surface layer 40 is set to be greater than that of the deformation layer 30 (for example, two to three times the thickness of the deformation layer 30). This makes it possible to increase the pressure sensitivity when the detection target presses the input operation surface S compared to the touch sensitivity when the detection target contacts the input operation surface S. Here, the touch sensitivity corresponds to the amount of change in capacitance of the sensing unit 13 when the detection target contacts the input operation surface S, and the pressure sensitivity corresponds to the amount of change in capacitance of the sensing unit 13 when the detection target contacts the input operation surface S.

[0050] The thickness of the surface layer 40 is preferably at least twice the thickness of the deformation layer 30. This makes it easier to divide the pressure-sensitive function into multiple stages by making the pressure-sensitive sensitivity sufficiently greater than the touch sensitivity, as will be described later.

[0051] The surface layer 40 may be made of a material with a higher elastic modulus than the deformation layer 30. In other words, by making the surface layer 40 of a material harder than the deformation layer 30, it becomes easier to separate the function of detecting touch operations from the function of detecting pressure operations, thereby making it possible to suppress malfunctions.

[0052] The surface layer 40 may be a laminated structure of multiple materials with different elastic moduli (hardness). Fig. 5 is a schematic side cross-sectional view of a sensor device 102 including a surface layer 40 having an outer layer portion 41 and an inner layer portion 42. The outer layer portion 41 forms the input operation surface S. The inner layer portion 42 is disposed between the outer layer portion 41 and the sensor sheet 10 and has a different elastic modulus from that of the outer layer portion 41.

[0053] The outer layer portion 41 may be made of a material with a higher or lower elastic modulus than the inner layer portion 42. For example, if the outer layer portion 41 is formed to a greater thickness than the inner layer portion 42, the thicker outer layer portion 41 is made of a material with a lower elastic modulus (softer material) than the inner layer portion 42. Conversely, if the outer layer portion 41 is formed to a smaller thickness than the inner portion, the thinner outer layer portion 41 is made of a material with a higher elastic modulus (harder material) than the inner layer portion 42. Examples of the soft material include flexible materials such as gel, rubber, elastomer, and elastic foam. Examples of the hard material include plastic materials such as acrylic.

[0054] The surface layer 40 may be a part of the housing of an electronic device in which the sensor device 100 is mounted. In this case, the sensor device 40 is installed inside the housing of the electronic device, and the surface of the housing functions as the input operation surface S. The housing is made of, for example, a translucent or non-translucent plastic material.

[0055] 6 is a schematic side cross-sectional view of a sensor device 103 in which a surface layer 40 is formed from part of the housing of an electronic device. As shown in the figure, in the sensor device 103, the surface layer 40 has a flat plate portion 401 that forms the input operation surface S, and legs 402 provided on the periphery of the flat plate portion 401. The flat plate portion 401 is a non-conductive layer provided so as to face the surface of the sensor sheet 10, and corresponds to the surface layer 40 in FIG. 1. The legs 402 hang down from the periphery of the flat plate portion 401 toward the installation surface T on which the sensor device 103 is installed, and their ends are supported by the installation surface T.

[0056] In the sensor device 103 configured as described above, the flat plate portion 401 elastically deforms with the legs 402 as fulcrums, so that a pressing operation on the input operation surface S is input to the sensor sheet 10. As a result, the pressing force is detected based on a change in capacitance of the sensing portion 13 accompanying the deformation of the deformation layer 30.

[0057] The pressure sensitivity of the sensor device 103 may be adjusted by the elastic modulus of the flat plate portion 401 or by the elastic modulus of the leg portion 402. In this case, the flat plate portion 401 and the leg portion 402 may be made of materials having different elastic moduli, or the leg portion 402 may be made of a laminate of non-conductive materials having different elastic moduli.

[0058] 1 , the sensor device 100 further includes a support layer 50. The support layer 50 is disposed between an installation surface T on which the sensor device 100 is installed and the reference electrode layer 20. The support layer 50 is made of an electrically insulating adhesive or pressure-sensitive adhesive material, and functions as a bonding layer that fixes the reference electrode layer 20 to the installation surface T.

[0059] The support layer 50 may be made of a flexible material. In this case, when the surface layer 40 is configured as part of the housing of an electronic device as shown in Fig. 4, it becomes easy to adjust the initial capacitance or touch sensitivity of the sensing unit 13 of the sensor device 101 installed on the installation surface T. In other words, the support layer 50 can absorb the dimensional tolerance of the distance between the flat plate portion 401 of the surface layer 40 and the installation surface T and the variation in the thickness dimension of the sensor device 101, making it possible to stably set the initial capacitance or touch sensitivity of the sensing unit 13 to a desired capacitance value.

[0060] The support layer 50 may be a laminated structure of a plurality of materials having different elastic moduli (hardness). Fig. 7 is a schematic cross-sectional side view of a sensor device 104 including a support layer 50 having a laminated structure of a first support layer 51 and a second support layer 52.

[0061] The first support layer 51 is disposed on the back surface of the reference electrode layer 20. The second support layer 52 is disposed between the first support layer 51 and the installation surface T, and has a different elastic modulus from that of the first support layer 31. The first support layer 51 may be made of a material having a higher elastic modulus than the second support layer 52, or may be made of a material having a lower elastic modulus than the second support layer 52. The thicknesses of the first support layer 51 and the second support layer 52 are not particularly limited, and they may be formed to have the same thickness or different thicknesses.

[0062] By constructing the support layer 50 from a laminate of flexible materials of different hardness, the same effects can be obtained as when the support layer 50 is a single layer, and the robustness of the pressure sensitivity when pressing the input operation surface S can be increased.

[0063] (Control Unit) The control unit 60 is typically a computer including a CPU (Central Processing Unit) and is configured with an integrated circuit such as an IC chip. The control unit 60 is mounted on the sensor sheet 10 (drawer section 112), drives the pressure sensor 1, and is configured to receive an output signal from the pressure sensor 1.

[0064] 8 is a functional block diagram of the control unit 60. The control unit 60 includes a calculation unit 61, a determination unit 62, and a threshold value setting unit 63.

[0065] The calculation unit 61 calculates the amount of change in capacitance of each sensing unit 13 on the sensor sheet 10 based on the output of the pressure sensor 1. The determination unit 62 determines to which of a plurality of divisions defined by a plurality of preset thresholds the pressure, which is the amount of change in capacitance calculated by the calculation unit 61, belongs, and outputs the determination result to a control device 71 of an electronic device 70 in which the sensor devices 100 to 104 are mounted. A threshold setting unit 63 sets the plurality of thresholds. The control unit 60 may be configured as a part of the control device 71 of the electronic device 70.

[0066] As described above, the electronic device 70 is configured as an input device mounted on an electronic device, such as an information processing device such as a tablet PC, audio devices such as headphones and earphones, imaging devices such as a digital still camera and a video camera, and game devices.

[0067] The control unit 60 is capable of executing a first detection process for detecting contact of a detection object with the input operation surface S, and a second detection process for detecting a pressing force of the detection object against the input operation surface S, based on the output of the pressure sensor 1 (sensor sheet 10). In the second detection process, the control unit 60 sets a plurality of threshold values ​​for determining the magnitude of the pressing force in multiple stages.

[0068] While a normal touch sensor is limited to one type of assignment for a tap operation, the sensor device of this embodiment, which has both a touch function and a pressure-sensitive function, allows four types of assignment, for example, divided into touch, low pressure, medium pressure, and high pressure. As a specific example of use, if the electronic device 70 is, for example, an audio device, while a touch sensor only allows the power to be turned on / off by tapping, in this embodiment, in addition to turning the power on / off, it is also possible to, for example, increase / decrease the volume softly, increase / decrease the volume normally, and increase / decrease the volume loudly.

[0069] Other examples of operations include song selection (fast forward, skip song, skip album), zoom amount in a camera, multi-stage detection of controller strength in a game console, and brightness adjustment of a display screen or light in a mobile information terminal.

[0070] In order to assign multi-level operations using the touch function and pressure-sensitive function, the pressure sensitivity when pressing the input operation surface S with a finger must be sufficiently large compared to the touch sensitivity when touching the input operation surface S with a finger. When assigning one operation each to touch sensitivity and pressure sensitivity (two operations in total), a threshold value Th1 is set for the touch sensitivity area and a threshold value Th2 is set for the pressure sensitivity area, as shown in Fig. 9. In Fig. 9, the horizontal axis represents the displacement of the finger, which is the detection target, the vertical axis represents the maximum sensitivity among all nodes, and "0" on the horizontal axis corresponds to the position where the detection target touches the input operation surface S.

[0071] The threshold values ​​Th1 and Th2 must be sufficiently far apart, and in order to prevent false detection (faulty operation), it is preferable that the threshold value Th2 be at least twice the threshold value Th1 (Th2≧2·Th1). Furthermore, when assigning multi-stage operations, it is necessary to set multiple threshold values ​​for the sensitivity area because only one threshold value can be set for the touch sensitivity area.

[0072] For example, when four operations are assigned, a threshold value Th1 (touch sensitivity) is set in the touch area, and three threshold values ​​Th2 (first pressure sensitivity), Th3 (second pressure sensitivity), and Th4 (third pressure sensitivity) are set in the pressure sensitive area, as shown in Fig. 10. In this case, it is preferable that Th2 ≥ 2·Th1, Th3 ≥ 3·Th1, and Th4 ≥ 4·Th1. When multiple threshold values ​​are set under such conditions, the sensor structure must be such that the pressure sensitivity is sufficiently greater than the touch sensitivity.

[0073] Here, displacement sensitivity will be explained. Displacement sensitivity refers to the relationship between the amount of displacement of a detection target (e.g., a user's finger) relative to the input operation surface S and detection sensitivity. Fig. 11 shows the results of an experiment showing the dependency of displacement sensitivity on the thickness of the surface layer 40. In the figure, the sensitivity at a displacement of 0 corresponds to touch sensitivity, and the area where the displacement is positive corresponds to pressure sensitivity. The material of the surface layer 40 was a single-layer acrylic plate.

[0074] 11 , A1 indicates the displacement sensitivity when the thickness of the surface layer 40 is the same as that of the deformation layer 30 (0.5 mm), and A2 indicates the displacement sensitivity when the thickness of the surface layer 40 is three times that of the deformation layer 30 (1.5 mm). In A1, the high touch sensitivity results in a high pressure sensitivity threshold, making it difficult to separate the touch function from the pressure sensitivity function. In contrast, in A2, the touch sensitivity can be lowered, and the pressure sensitivity threshold can be set sufficiently higher than the touch sensitivity threshold, making it easy to separate the touch function from the pressure sensitivity function and allowing multiple threshold levels to be set in the pressure sensitive area.

[0075] Next, load sensitivity will be described. Load sensitivity refers to the relationship between the vertical load acting on the input operation surface S and detection sensitivity. Fig. 12 shows the results of an experiment showing the dependency of load sensitivity on the structure (thickness, flexibility) of the surface layer 40.

[0076] In Figure 12, B1 shows the load sensitivity when the thickness of the surface layer 40 is the same (0.5 mm) as the thickness of the deformation layer 30. B2 shows the load sensitivity when the surface layer 40 has the laminated structure shown in Figure 5, the outer layer 41 is an acrylic plate with a thickness of 0.5 mm, and the inner layer 42 is a rubber plate with a thickness of 1.0 mm. The load sensitivity was the same when the outer layer 41 was a rubber plate with a thickness of 1.0 mm and the inner layer 42 was an acrylic plate with a thickness of 0.5 mm. And B3 shows the load sensitivity when the surface layer 40 was an acrylic plate with a thickness three times the thickness of the deformation layer 30 (1.5 mm).

[0077] As shown in Figure 12, the load sensitivity tends to decrease in the order of B1, B2, and B3. This is because the surface layer 40 becomes harder as its thickness increases. Therefore, in order to suppress the decrease in load sensitivity, the surface layer 40 needs to be soft. By making the surface layer 40 soft, it becomes easier to separate the touch function and the pressure-sensing function in terms of load sensitivity as well.

[0078] In the sensor device 100 of this embodiment, as described above, the surface layer 40 is formed to have a thickness greater than that of the deformation layer 30. Therefore, as described above, compared to when the surface layer 40 has the same thickness as the deformation layer 30, the pressure sensitivity can be made sufficiently greater than the touch sensitivity, and the pressure-sensitive function can be divided into multiple stages.

[0079] (Threshold Setting Method 1) Next, a specific example of a threshold setting method will be described. Here, a procedure for setting fixed thresholds (loads of 1.5 N and 3 N) in the threshold setting unit 63 using the sensor device 104 (see FIG. 7 ) that includes the surface layer 40 having the legs 402 will be described.

[0080] First, the load, displacement, and maximum sensitivity of all nodes of the pressure sensor 1 were measured when the input operation surface S of the sensor device 104 was pressed. The key was made of aluminum and had a diameter of 10 mm, which is close to the size of a finger. The deformation of the pressure sensor 1 in the Z-axis direction was measured from 5 mm above the center position of the input operation surface S on the top surface of the surface layer 40 until the load reached 5 N.

[0081] Fig. 13 shows the load-displacement curve when the input operation surface S is pressed, and Fig. 14 shows the relationship between the amount of displacement and the maximum sensitivity. In Fig. 14, the amount of displacement at the start position is -5 mm, and the amount of displacement at which the load begins to be detected is 0 mm.

[0082] Next, the displacement Z1 when the load is 1.5 N and the displacement Z2 when the load is 3 N are calculated (see FIG. 13). In addition, the maximum sensitivity (hereinafter simply referred to as sensitivity) when the displacement is 0, Z1, and Z2 is measured (see FIG. 14).

[0083] Next, the sensitivity (touch sensitivity) when the displacement is 0 is set as a threshold value Th1, the sensitivity when the load is 1.5 N as a threshold value Th2 (first pressure sensitivity), and the sensitivity when the load is 3 N as a threshold value Th3 (second pressure sensitivity) are set in the threshold value setting unit 63. From the viewpoint of suppressing erroneous detection, as described above, it is preferable that Th2 ≥ 2·Th1 and Th3 ≥ 3·Th1.

[0084] The determination unit 62 performs a determination process according to the sensitivity, for example, in the following manner: Operation 1: When the sensitivity becomes equal to or greater than Th1 and does not exceed Th2 for a certain period of time (for example, 0.5 seconds); Operation 2: When the sensitivity becomes equal to or greater than Th2 and does not exceed Th3 for a certain period of time (for example, 0.5 seconds); Operation 3: When the sensitivity becomes equal to or greater than Th3 and remains equal to or greater than Th3 for a certain period of time (for example, 0.5 seconds).

[0085] (Threshold Setting Method 2) The threshold set in the threshold setting unit 63 may be individually and variably adjusted by the user. This allows the threshold to be optimized for each user, thereby improving operability for that user. The setting procedure is, for example, as follows.

[0086] The maximum sensitivity of all nodes of the pressure sensor 1 is measured three times when the user touches the input operation surface S (touch operation), and the average value is set as threshold value Th1 in the threshold setting unit 63. Next, the sensitivity is measured three times when the user lightly presses the input operation surface S (small amount of pressure), and the average value is set as threshold value Th2 in the threshold setting unit 63. Subsequently, the sensitivity is measured three times when the user strongly presses the input operation surface S (large amount of pressure), and the average value is set as threshold value Th3 in the threshold setting unit 63.

[0087] In this case, too, from the viewpoint of suppressing erroneous detection, it is preferable to set the threshold values ​​Th2 and Th3 so that Th2 ≥ 2·Th1 and Th3 ≥ 3·Th1. If these conditions are not met, the same measurement (calibration) may be performed again.

[0088] The determination unit 62 performs a determination process according to the sensitivity in the same manner as described above, for example, in the following manner: Operation 1: When the sensitivity becomes equal to or greater than Th1 and does not exceed Th2 for a certain period of time (for example, 0.5 seconds) Operation 2: When the sensitivity becomes equal to or greater than Th2 and does not exceed Th3 for a certain period of time (for example, 0.5 seconds) Operation 3: When the sensitivity becomes equal to or greater than Th3 and remains equal to or greater than Th3 for a certain period of time (for example, 0.5 seconds)

[0089] (Threshold setting method 3) The magnitude of the load detected by the pressure sensor 1 may differ depending on the operation position on the input operation surface S. For example, in the sensor device 104 shown in Fig. 7, the legs 402 of the surface layer 40 are supported on the installation surface T, and therefore a difference in detection sensitivity is likely to occur between the central position on the input operation surface S and peripheral positions close to the legs 402 (see Figs. 15 and 16). Therefore, in this embodiment, the threshold setting unit 63 is configured to be able to correct the pressure sensitivity according to the operation area of ​​the detection target on the input operation surface S.

[0090] Fig. 15 is a schematic diagram showing operation areas on the input operation surface S, and Fig. 16 shows the load-displacement curves for each of the operation areas. As shown in Fig. 16, in the sensor device 104 in which the surface layer 40 has legs 402, even if the magnitude of the vertical load is the same, the amount of displacement in operation areas S2 and S3 on the periphery of the input operation surface S tends to be smaller than that in operation area S1 in the center of the input operation surface S, and therefore the detection sensitivity also tends to be lower. Therefore, in order to obtain uniform detection sensitivity in each of the operation areas S1 to S3, the threshold setting unit 63 sets the threshold in the following procedure.

[0091] First, the relationship between the load and the amount of displacement when pressing each of the operation areas S1 to S3 on the input operation surface S of the sensor device 104 is measured (FIG. 16). The keystrokes used are made of aluminum and have a diameter of 10 mm, which is similar to the size of a finger. Next, the slope of the measured load-displacement curve is calculated for each of the operation areas S1 to S3, and these slopes are used as correction coefficients. The threshold setting unit 63 corrects the first pressure sensitivity (Th2), the second pressure sensitivity (Th3), etc. based on the correction coefficients in accordance with the operation area to be detected on the input operation surface S.

[0092] The operation area is divided into nine regions, with operation area S1 corresponding to the central position of the input operation surface S, operation area S2 corresponding to the regions between the center of each side of the input operation surface S and operation area S1, and operation area S3 corresponding to the regions at the four corners of the input operation surface S. The calculated correction coefficients are managed for each of operation areas S1 to S3 using a lookup table such as that shown in Fig. 17. In the example shown in Fig. 17, each operation area is divided into nine area numbers, with the correction coefficient set to 0.5 for area numbers 1 and 3, 0.7 for area numbers 2 and 8, 0.8 for area numbers 4 and 6, 1 for area number 5, and 0.6 for area numbers 7 and 9.

[0093] The contact position of the detection target on the input operation surface S is calculated from the center of gravity of the pressure distribution acting on the pressure sensor 1 (sensor sheet 10), and the value obtained by multiplying the pre-correction pressure sensitivity (threshold) by the correction coefficient assigned to each area is used as the corrected pressure sensitivity (threshold). For example, when a pressing operation is detected in area number 1, the pressing force is determined using corrected thresholds (Th2', Th3') obtained by multiplying the pre-correction pressure sensitivity Th2, Th3 by 0.5. When a pressing operation is detected in area number 6, the pressing force is determined using corrected thresholds (Th2', Th3') obtained by multiplying the pre-correction thresholds (Th2, Th3) by 0.8. This ensures that input operations are consistent with the user's intentions without impairing the user's operational feel.

[0094] Note that even when the material or thickness of the surface layer 40 differs from region to region, the touch sensitivity Th1 may be corrected using a method similar to that described above. For example, when the correction coefficient for the region with the smallest thickness of the surface layer 40 is set to 1, the correction coefficients for the other regions with larger thicknesses are set to be smaller than 1. Furthermore, when the correction coefficient for the region with the largest thickness of the surface layer 40 is set to 1, the correction coefficients for the other regions with smaller thicknesses are set to be larger than 1.

[0095] (Relationship Between Touch Sensitivity and Pressure Sensitivity) Next, the reason why the pressure sensitivity Th2 is preferably set to at least twice the touch sensitivity Th1 will be described using the sensor device 100 shown in FIG. 1 as an example.

[0096] 18 , the thickness of the deformation layer 30 is d, and the thickness of the surface layer 40 is D. When the entire sensor sheet 10 is viewed as an electrode (sensor electrode layer 13), the touch sensitivity C1 when the detection target comes into contact with the input operation surface S is expressed by the following equation: C1=εA / D (1) Here, ε is the dielectric constant of the surface layer 40, and A is the contact area of ​​the detection target. Equation (1) corresponds to the change in capacitance between the detection target and the sensor sheet 10 when the detection target approaches the sensor sheet 10 from a point very far away to a distance D (the position of the input operation surface S).

[0097] The pressure sensitivity C2 when the deformation layer 30 is deformed by x %, assuming that the dielectric constant of the deformation layer 30 is the same as the dielectric constant (ε) of the surface layer 40, is expressed by the following equation: C2=εA / {d(1−x / 100)}−εA / d (2) Equation (2) corresponds to the change in capacitance when the sensor sheet 10 approaches the reference electrode layer 20 from a distance d to d(1−x / 100).

[0098] In order to set the threshold values ​​of touch sensitivity and pressure sensitivity, when touch sensitivity×2<maximum pressure sensitivity is set, (εA / D)×2<εA / {d(1−x / 100)}−εA / d 2 / D<1 / {d(1−x / 100)}−1 / d=x / d(100−x) ∴D / d>2(100−x) / x ... (3) The function expressed by equation (3) is shown in FIG. 19.

[0099] Because the deformation layer 30 does not deform 100%, there is a limit to the deformation rate of the deformation layer 30. For example, if a foam is used for the deformation layer 30, the volume ratio of the material that makes up the foam is generally 20% or more. Furthermore, since the thickness variation of typical materials is ±10%, it is necessary to allow for a maximum thickness variation of approximately 20% for the deformation layer 30. Furthermore, considering that the sensor device 100 will be incorporated into the housing of an electronic device, it is necessary to allow for a mechanical variation (tolerance) of the housing of approximately 10%.

[0100] Considering the above three factors, the maximum deformation rate of the deformation layer 30 within the practical usable range is 50% or less. Therefore, as shown in Figure 19, it is preferable that D / d (thickness D of the surface layer 40) ÷ (thickness d of the deformation layer 30) is 2 or more.

[0101] The present technology can also be configured as follows: (1) A sensor device comprising: a sensor sheet capable of detecting a pressure distribution; a reference electrode layer disposed opposite one surface of the sensor sheet and connected to a reference potential; a deformation layer disposed between the sensor sheet and the reference electrode layer and made of a flexible material; a surface layer having an input operation surface, disposed on the other surface of the sensor sheet and made of a non-conductive material and thicker than the deformation layer; and a control unit capable of executing a first detection process to detect contact of a detection object with the input operation surface based on an output from the sensor sheet and a second detection process to detect a pressing force of the detection object on the input operation surface, the control unit setting multiple thresholds in the second detection process to determine the magnitude of the pressing force in multiple stages. (2) The sensor device described in (1) above, wherein the surface layer has a thickness at least twice that of the deformation layer. (3) The sensor device described in (2) above, wherein the surface layer is made of a material having a higher elastic modulus than the deformation layer. (4) The sensor device according to (2) or (3), wherein the sensor sheet has a sensor electrode layer including a flexible substrate and a plurality of capacitance elements arranged in a matrix on one surface of the substrate, and each of the plurality of capacitance elements has a comb-shaped electrode pair facing each other in a direction parallel to the one surface of the substrate. (5) The sensor device according to (4), wherein the sensor electrode layer is disposed on a surface of the sensor sheet facing the reference electrode layer. (6) The sensor device according to any one of (1) to (5), further comprising a support layer made of a flexible material and disposed between the reference electrode layer and an installation surface on which the sensor device is installed. (7) The sensor device according to any one of (1) to (6), wherein the surface layer has an outer layer portion forming the input operation surface, and an inner layer portion disposed between the outer layer portion and the sensor sheet, and having a different elastic modulus from the outer layer portion.(8) The sensor device according to any one of (1) to (6) above, wherein the deformation layer includes: a first deformation layer disposed on one surface of the sensor sheet; and a second deformation layer disposed between the first deformation layer and the reference electrode layer and having a different elastic modulus from the first deformation layer. (9) The sensor device according to any one of (1) to (6) above, wherein the surface layer includes: a flat plate portion forming the input operation surface; and legs provided on the periphery of the flat plate portion and supported on an installation surface on which the sensor device is installed. (10) The sensor device according to any one of (1) to (9) above, wherein the control unit has a determination unit that determines to which of a plurality of divisions defined by the plurality of threshold values ​​the pressing force belongs, and the plurality of threshold values ​​include: a first pressure sensitivity that is at least twice the sensitivity of the touch sensitivity, which is the detection sensitivity of the sensor sheet measured when a detection object touches the input operation surface, and a second pressure sensitivity that is at least three times the sensitivity of the touch sensitivity. (11) The sensor device according to (10) above, wherein the plurality of thresholds further includes a third pressure sensitivity that is four times or more the sensitivity of the touch sensitivity. (12) The sensor device according to (10) or (11) above, wherein the control unit further has a threshold setting unit that can individually adjust the plurality of thresholds. (13) The sensor device according to (12) above, wherein the threshold setting unit corrects the first pressure sensitivity and the second pressure sensitivity according to an operation area of ​​the detection target on the input operation surface.(14) An electronic device comprising a sensor device including: a sensor sheet capable of detecting pressure distribution; a reference electrode layer disposed opposite one side of the sensor sheet and connected to a reference potential; a deformation layer disposed between the sensor sheet and the reference electrode layer and made of a flexible material; a surface layer having an input operation surface, disposed on the other side of the sensor sheet and made of a non-conductive material and thicker than the deformation layer; and a control unit capable of executing a first detection process to detect contact of a detection object with the input operation surface based on an output from the sensor sheet, and a second detection process to detect a pressing force of the detection object against the input operation surface, the second detection process setting multiple thresholds for determining the magnitude of the pressing force in multiple stages.

[0102] DESCRIPTION OF SYMBOLS 1...Pressure sensor 10...Sensor sheet 11...Substrate 12...Sensor electrode layer 13...Sensing section 20...Reference electrode layer 30...Deformation layer 31...First deformation layer 32...Second deformation layer 40...Surface layer 41...Outer layer section 42...Inner layer section 50...Support layer 60...Control unit 61...Calculation section 62...Determination section 63...Threshold setting section 70...Electronic device 71...Control device 101, 102, 103, 104...Sensor device 401...Flat plate section 402...Leg section S...Input operation surface

Claims

1. A sensor device comprising: a sensor sheet capable of detecting pressure distribution; a reference electrode layer disposed opposite one side of the sensor sheet and connected to a reference potential; a deformation layer disposed between the sensor sheet and the reference electrode layer and made of a flexible material; a surface layer having an input operation surface, disposed on the other side of the sensor sheet and made of a non-conductive material and having a greater thickness than the deformation layer; and a control unit capable of executing a first detection process for detecting contact of a detection object with the input operation surface based on an output from the sensor sheet, and a second detection process for detecting the pressing force of the detection object against the input operation surface, the second detection process setting multiple thresholds for determining the magnitude of the pressing force in multiple stages.

2. A sensor device according to claim 1, wherein the surface layer has a thickness at least twice as large as the thickness of the deformation layer.

3. A sensor device according to claim 2, wherein the surface layer is made of a material having a higher elastic modulus than the deformation layer.

4. A sensor device as described in claim 2, wherein the sensor sheet has a sensor electrode layer having a flexible base material and a plurality of capacitance elements arranged in a matrix on one surface of the base material, and each of the plurality of capacitance elements has a comb-shaped electrode pair facing each other in a direction parallel to the one surface of the base material.

5. A sensor device according to claim 4, wherein the sensor electrode layer is disposed on a surface of the sensor sheet facing the reference electrode layer.

6. A sensor device according to claim 1, further comprising a support layer made of a flexible material and disposed between the reference electrode layer and an installation surface on which the sensor device is installed.

7. A sensor device as described in claim 1, wherein the surface layer has an outer layer portion that forms the input operation surface, and an inner layer portion that is disposed between the outer layer portion and the sensor sheet and has a different elastic modulus than that of the outer layer portion.

8. A sensor device as described in claim 1, wherein the deformation layer comprises: a first deformation layer arranged on one side of the sensor sheet; and a second deformation layer arranged between the first deformation layer and the reference electrode layer, the second deformation layer having an elastic modulus different from that of the first deformation layer.

9. A sensor device as described in claim 1, wherein the surface layer has a flat plate portion that forms the input operation surface, and legs that are provided on the peripheral edge of the flat plate portion and supported on an installation surface on which the sensor device is installed.

10. A sensor device as described in claim 1, wherein the control unit has a judgment section which judges to which of a plurality of divisions defined by the plurality of threshold values ​​the pressing force belongs, and the plurality of threshold values ​​include: a first pressure sensitivity which is at least twice the sensitivity of the touch sensitivity, which is the detection sensitivity of the sensor sheet measured when a detection object contacts the input operation surface; and a second pressure sensitivity which is at least three times the sensitivity of the touch sensitivity.

11. The sensor device according to claim 10, wherein the plurality of threshold values ​​further includes a third pressure sensitivity that is four or more times the touch sensitivity.

12. The sensor device according to claim 10, wherein the control unit further comprises a threshold setting section capable of individually adjusting the plurality of thresholds.

13. A sensor device according to claim 12, wherein the threshold setting unit corrects the first pressure sensitivity and the second pressure sensitivity according to an operation area of ​​the detection target on the input operation surface.

14. Electronic equipment comprising a sensor device having: a sensor sheet capable of detecting pressure distribution; a reference electrode layer disposed opposite one side of the sensor sheet and connected to a reference potential; a deformation layer disposed between the sensor sheet and the reference electrode layer and made of a flexible material; a surface layer having an input operation surface, disposed on the other side of the sensor sheet and made of a non-conductive material and thicker than the deformation layer; and a control unit capable of executing a first detection process for detecting contact of a detection object with the input operation surface based on an output from the sensor sheet, and a second detection process for detecting the pressing force of the detection object against the input operation surface, the second detection process setting multiple thresholds for determining the magnitude of the pressing force in multiple stages.

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