JP2021103115A - Pressure detection device - Google Patents

Abstract

To provide a pressure detection device that can reduce the number of routing wiring, without using a switching element.SOLUTION: A first electrode pattern Ty or a second electrode pattern Tx extends between third electrodes Rx adjacent in a Y direction of a plurality of third electrodes Rx, and thereby the electrode patterns overlap only partially the adjacent third electrodes Rx in plane view. When a pressure is applied and a second insulator 13 deforms, shear force is calculated on the basis of change in electrostatic capacitance obtained by change in an overlapping area of the mutually overlapping third electrode Rx the plane view and the first electrode Ty or the second electrode Tx. A plurality of routing wiring 80 causes a short-circuit in two or more electrodes in neither the same row and adjacent rows nor the same column and adjacent columns of the plurality of third electrodes Rx from a rear surface, and is connected many to one.SELECTED DRAWING: Figure 12

Description

The present invention relates to a pressure detector, particularly a pressure detector capable of detecting shear stress as well as stress in the direction perpendicular to the input surface.

In recent years, sensor sheets capable of detecting the in-plane distribution of pressure have been developed and commercialized. For example, there are known ones that are laid under the body to measure the body pressure distribution and touchpads that can detect the pressure. However, all of these detect the in-plane distribution of stress acting only in the normal direction (Z direction) acting on the sheet surface.
On the other hand, there is a 3-component load cell or the like that can detect not only the stress in the Z direction but also the stress in the shear direction (X, Y direction). However, in order to detect the in-plane distribution, it is necessary to spread and arrange a large number of 3-component load cells, so that it is difficult to put the device into practical use.

Therefore, as a solution to these problems, the applicant has already proposed the following pressure detection device in Patent Document 1.

As shown in FIG. 21, the pressure detection device 101 of Patent Document 1 has a support substrate 11, a second insulator 13 which is less rigid than the support substrate 11 and elastically deforms when pressure is applied, and a first insulator 15. doing. Further, the pressure detection device 101 includes a plurality of third electrodes Rx, a plurality of first band-shaped electrodes Ty, a plurality of second band-shaped electrodes Tx, a capacitance measurement circuit, and a pressure detection circuit. ing.
The support substrate 11, the second insulator 13, and the first insulator 15 are laminated side by side in order from the side opposite to the side where the pressure is input.
The plurality of third electrodes Rx are provided so as to be completely spread between the second insulator 13 and the support substrate 11.

The plurality of first band-shaped electrodes Ty are provided so as to extend in the X direction as the first direction on the side opposite to the second insulator 13 of the first insulator 15. The plurality of first band-shaped electrodes Ty extend between the adjacent third electrodes Rx in the direction intersecting the first direction among the plurality of third electrodes, thereby forming a part of each of the adjacent third electrodes Rx. Only overlap in plan view.
The plurality of second strip-shaped electrodes Tx are provided extending in the Y direction as a second direction intersecting the first direction between the first insulator 15 and the second insulator 13. The plurality of second band-shaped electrodes Tx extend between the adjacent third electrodes Rx in the direction intersecting the second direction among the plurality of third electrodes Rx, and thus are a part of each of the adjacent third electrodes Rx. It overlaps only in the plan view.

The capacitance measuring circuit can detect the capacitance generated between the third electrode Rx and the first band-shaped electrode Ty that overlaps the third electrode Rx in a plan view. The capacitance measuring circuit can detect the capacitance generated between the third electrode Rx and the second band-shaped electrode Tx that overlaps the third electrode Rx in a plan view.
In the pressure calculation circuit, when the second insulator 13 is deformed by applying pressure, the third electrode Rx and the first band-shaped electrode Ty that overlap each other in the plan view overlap each other in the overlapping area and / or the plan view. The shearing force is calculated based on the change in capacitance obtained by the capacitance measurement circuit by changing the overlapping area of the third electrode Rx and the second band-shaped electrode Tx.

JP-A-2017-156126

By the way, in the pressure detection device 101 of Patent Document 1, when all the third electrodes Rx of the sensor unit 103 are individually routed to the control circuit 105 (hereinafter, referred to as “total route”), the number of wiring wires becomes too large. , It is considered impossible in reality.

Therefore, Patent Document 1 discloses that a switching element 21 is attached to each of the third electrode Rx to form an active matrix.
The switching element 21 is provided on the surface of the support substrate 11 opposite to the third electrode Rx (see FIG. 21). The third electrode Rx and the switching element 21 are connected by a connecting line 23 provided in the through hole.
Further, the switching element 21 is connected to the gate drive circuit 35 by control lines 53a to 53c in each row. The plurality of control lines 53a to 53c extend in a direction intersecting the alignment direction, and are connected to a plurality of switching elements 21 arranged in the direction (see FIG. 22).

Then, the third electrode Rx is connected to the input of the amplifier circuit 33 (see FIG. 22) via the switching element 21 in the active matrix. Specifically, one end of the switching element 21 is connected to each third electrode Rx, and the other end is connected to the amplifier circuit 33 by the readout lines 51a to 51c for each line. In other words, the plurality of readout lines 51a to 51c are connected to a plurality of switching elements 21 arranged in one direction among the plurality of switching elements 21. Further, the read lines 51a to 51c extend in the arrangement direction of the plurality of switching elements 21 and are connected to the amplifier circuit 33.

In the above configuration, the first electrode pattern is obtained by sequentially detecting the plurality of read lines 51a to 51c by the microcontroller 25 in a state where the gate drive circuit 35 turns on the plurality of switching elements 21 by one control line. The change in capacitance at the intersection of Ty or the second electrode pattern Tx and the third electrode pattern Rx is detected. That is, since the read lines 51a to 51c are connected to the plurality of third electrodes Rx via the plurality of switching elements 21, the number of read lines can be reduced.
At least, in the case of a matrix in which the third electrode Rx is 4 × 4 or more, the active matrix in which the switching element 21 is attached to each of the third electrode Rx is the routing wiring to the control circuit 105 rather than the “total routing”. The number will be less than half.

However, the active matrix to which the switching element 21 is attached is also unrealistic due to the problem of the capacitance (Coff) existing between the output terminals when the switching element 21 is turned off. That is, Coff needs to be sufficiently smaller than the capacitance to be measured generated by the overlap of the third electrode Rx and the first band-shaped electrode Ty or the overlap of the third electrode Rx and the second band-shaped electrode Tx. .. This is because if the Coff is large, even the signal from the third electrode Rx connected to the switching element 21 that is turned off is picked up. However, at present, such a design is not possible with commercially available relays.
Further, it is not realistic because of the problem of the space for providing the switching element 21. That is, since the size of the third electrode Rx is several mm square, it is difficult to attach one switching element 21 to each of these third electrodes Rx. Moreover, the thickness of the entire device becomes thick.

An object of the present invention is to reduce the number of routing wires without using a switching element.

Hereinafter, a plurality of aspects will be described as means for solving the problem. These aspects can be arbitrarily combined as needed.

The pressure detecting device according to the seemingly present invention has a support substrate, a second insulator having a lower rigidity than the support substrate and elastically deforming when pressure is applied, and a first insulator. The pressure detection device has a plurality of third electrodes, a plurality of first band-shaped electrodes, a plurality of second band-shaped electrodes, a capacitance measurement circuit, a pressure detection circuit, and a plurality of routing wires. There is.
The support substrate, the second insulator, and the first insulator are laminated side by side in order from the side opposite to the side where the pressure is input.
The plurality of third electrodes are provided so as to be spread in a grid pattern between the second insulator and the support substrate. The plurality of routing wires are provided on the opposite side of the second insulator of the support substrate, and are short-circuited to two or more electrodes that are not in the same row and adjacent rows and are not in the same row and adjacent rows among the plurality of electrodes. , Multiple to one is connected, and one end is connected to the capacitance measurement circuit.

The plurality of first strip-shaped electrodes are provided so as to extend in the first direction on the side opposite to the second insulator of the first insulator. The plurality of first band-shaped electrodes extend between the third electrodes adjacent to each other in the direction intersecting the first direction among the plurality of third electrodes, so that only a part of each of the adjacent third electrodes can be viewed in a plan view. It overlaps with.
The plurality of second strip-shaped electrodes are provided extending in the second direction intersecting the first direction between the first insulator and the second insulator. The plurality of second band-shaped electrodes extend between the third electrodes adjacent to each other in the direction intersecting the second direction among the plurality of third electrodes, so that only a part of each of the adjacent third electrodes can be viewed in a plan view. It overlaps with.

The capacitance measuring circuit can detect the capacitance generated between the third electrode and the first band-shaped electrode overlapping the third electrode in a plan view. The capacitance measuring circuit can detect the capacitance generated between the third electrode and the second band-shaped electrode overlapping the third electrode in a plan view.
In the pressure calculation circuit, when the second insulator is deformed by applying pressure, the overlapping area of the third electrode and the first band-shaped electrode that overlap each other in the plan view and / or the overlapping area in the plan view is the first. The shearing force is calculated based on the change in capacitance obtained by the capacitance measurement circuit by changing the overlapping area between the three electrodes and the second band-shaped electrode.

In this device, each first band-shaped electrode constitutes a large number of intersections by overlapping a plurality of pairs of third electrodes arranged adjacent to each other in the second direction in a plan view. Further, each second band-shaped electrode constitutes a large number of intersections by overlapping a plurality of pairs of third electrodes arranged adjacent to each other in the first direction in a plan view.
In this device, for example, when a shearing force in the second direction acts on the first insulator, at the portion where the shearing force acts on the first band-shaped electrode, each intersection of the first band-shaped electrode and the pair of adjacent third electrodes The area of (the portion where the first band-shaped electrode overlaps the corresponding pair of third electrodes in a plan view) is changed. As a result, the capacitance between the first band-shaped electrode and one third electrode increases, and the capacitance between the first band-shaped electrode and the other third electrode decreases. Then, the capacitance measuring circuit detects the change in capacitance of the portion, and the pressure calculation circuit further calculates the shearing force based on the change in capacitance.

In such a device, the present invention comprises short-circuiting a plurality of routing wires to two or more electrodes that are not in the same row and adjacent rows of the plurality of third electrodes and are not in the same row and adjacent rows. Since they are connected one-to-one, the number of routing wires can be reduced.
In the connection between the plurality of electrodes and the plurality of routing wires, all the electrodes can be connected through the through holes of the support substrate. Further, the connection between the plurality of electrodes and the plurality of routing wires may be connected through the through holes of the support substrate except for the peripheral electrodes among the electrodes laid out in a grid pattern.

Further, the plurality of routing wires may be provided on the second insulator side of the support substrate and covered with the insulating film, and the plurality of electrodes may be located on the second insulator side of the insulating film.
In this case, in the connection between the plurality of electrodes and the plurality of routing wires, all the electrodes can be connected through the through holes of the insulating film. Further, the plurality of electrodes and the plurality of routing wires may be connected via through holes of the insulating film except for the peripheral electrodes among the electrodes laid out in a grid pattern.

Further, the plurality of first band-shaped electrodes are short-circuited to two or more non-adjacent first band-shaped electrodes among the plurality of first band-shaped electrodes and connected in a plurality of to one-to-one manner, and one end thereof is connected to the capacitance measurement circuit. An additional routing wire may be provided. Further, a plurality of second band-shaped electrodes are short-circuited to two or more non-adjacent second band-shaped electrodes among the plurality of second band-shaped electrodes and connected in a plurality of to one-to-one manner, and one end thereof is connected to the capacitance measurement circuit. An additional routing wire may be provided. As a result, the number of routing wires can be further reduced.

In the pressure detection device according to the present invention, the number of routing wires can be reduced without using a switching element.

Block configuration diagram of the touch pad device. Top view of the first electrode pattern. Top view of the second electrode pattern. Top view of the third electrode pattern. The plan view which shows the overlapping state of an electrode pattern. The plan view which shows the change of the overlapping state of an electrode pattern when a shearing force acts. The plan view which shows the change of the overlapping state of an electrode pattern when a shearing force acts. Schematic cross-sectional view to show the relationship between mutual capacitance, shear stress, and stress in the normal direction. Schematic cross-sectional view to show the relationship between mutual capacitance, shear stress, and stress in the normal direction. Schematic cross-sectional view to show the relationship between mutual capacitance, shear stress, and stress in the normal direction. Schematic cross-sectional view to show the relationship between mutual capacitance, shear stress, and stress in the normal direction. The schematic diagram which shows the connection structure of the 3rd electrode and the routing wiring. The table which shows the combination of the 3rd electrode which short-circuited for every routing wiring in connection structure 1. The schematic diagram which shows another example of the 3rd electrode pattern. The table which shows the combination of the 3rd electrode which short-circuited for every routing wiring in connection structure 2. The table which shows the combination of the 3rd electrode which short-circuited for every routing wiring in connection structure 3. The table which shows the combination of the 3rd electrode which short-circuited for every routing wiring in connection structure 4. The table which shows the combination of the 1st electrode and the combination of the 2nd electrode which short-circuited for every routing wiring in connection structure 4. Pressure measurement control flowchart. The figure which shows another example of the touch pad device. The block block diagram of the touch pad device of the prior art. The schematic diagram which shows the active matrix of the 3rd electrode pattern in the prior art.

1. 1. First Embodiment (1) Overall Structure of Touch Pad Device The overall configuration of the touch pad device 1 (an example of a pressure detection device) will be described with reference to FIG. FIG. 1 is a block configuration diagram of a touch pad device.

The touch pad device 1 has a sensor unit 3 (touch pad) and a control circuit 5.
The sensor unit 3 has a function of detecting a position where pressure is applied and a function of detecting pressure.
The control circuit 5 controls the sensor unit 3 and performs various measurements based on the detection signal from the sensor unit 3.
The touch pad device 1 has a PC 7. The PC 7 is, for example, a personal computer. Various data and instructions can be input to the control circuit 5 by the PC 7, and information from the control circuit 5 can be displayed on the monitor screen. For example, the mutual capacity data, which is the measurement result described later, is displayed on the monitor of the PC 7.

(2) Basic Structure of Sensor Unit The sensor unit 3 has a support substrate 11, a second insulator 13, and a first insulator 15, which are in order from the side opposite to the side where pressure is input. They are stacked side by side. Specifically, the second insulator 13 is provided on the upper surface of the support substrate 11. The first insulator 15 is provided on the upper surface of the second insulator 13.
The support substrate 11 is, for example, a glass epoxy substrate and has a thickness of 1.6 mm. The material of the support substrate 11 is not particularly limited.

The second insulator 13 is a member that can be elastically deformed when a force is applied. The elastic modulus of the second insulator 13 is preferably in the range of 0.001 to 10 MPa, more preferably in the range of 0.001 to 0.01 MPa. The second insulator 13 has, for example, a polyurethane gel sheet and has a thickness of 1 mm. The polyurethane gel sheet preferably has a hardness of 0 and is sufficiently deformed even with a light load. Further, since the polyurethane gel sheet has adhesiveness, the support substrate 11 and the first insulator 15 can be adhered to each other without preparing a separate adhesive or the like. The material of the second insulator 13 is not particularly limited.
The thickness of the second insulator 13 is preferably in the range of 10 μm to 10000 μm, and more preferably in the range of 100 μm to 2000 μm.

The first insulator 15 is a layer for arranging the first electrode pattern Ty and the second electrode pattern Tx at a predetermined distance in the stacking direction while insulating each other.
The first insulator 15 is, for example, a urethane film and has a thickness of 0.07 mm.
The elastic modulus of the first insulator 15 is preferably in the range of 1 MPa to 4000 MPa, and more preferably in the range of 1 MPa to 10 MPa.
The material of the first insulator 15 is not particularly limited.
The thickness of the first insulator 15 is preferably in the range of 1 μm to 1000 μm, and more preferably in the range of 10 μm to 100 μm.

The first electrode pattern Ty and the second electrode pattern Tx are composed of a plurality of strip-shaped or strip-shaped second electrode Tx and first electrode Ty, respectively.
The first electrode pattern Ty is provided on the upper surface of the first insulator 15, that is, on the side opposite to the second insulator 13 of the first insulator 15. As shown in FIG. 2, the first electrode patterns Ty are arranged in the Y direction in the figure and extend in the X direction (an example of the first direction). The first electrode pattern Ty is a plurality of first electrodes Ty (1), Ty (2), Ty (3) ,,,, Ty (l-2), Ty (l-1), Ty extending in the X direction. It has (l). FIG. 2 is a plan view of the first electrode pattern.

The second electrode pattern Tx is provided on the lower surface of the first insulator 15, that is, between the first insulator 15 and the second insulator 13. As shown in FIG. 3, the second electrode patterns Tx are arranged in the X direction in the figure and extend in the Y direction (an example of the second direction). The second electrode pattern Tx is a plurality of second electrodes Tx (1), Tx (2), Tx (3) ,,,, Tx (m-2), Tx (m-1), Tx ( m). FIG. 3 is a plan view of the second electrode pattern.
With the above configuration, the second electrode pattern Tx is arranged so as to maintain insulation with the first electrode pattern Ty and intersect with the first electrode pattern Ty (orthogonally in this embodiment). The first electrode pattern Ty and the second electrode pattern Tx are drawn out to the connection terminal (not shown) by the lead-out wiring.

The third electrode pattern Rx (an example of a plurality of electrodes provided so as to be spread in a grid pattern between the second insulator and the support substrate) is provided between the second insulator 13 and the support substrate 11. Be done. As shown in FIG. 4, the third electrode pattern Rx is composed of a large number of island-shaped third electrodes Rx spread over the entire surface. FIG. 4 is a plan view of the third electrode pattern.

The third electrode pattern Rx constitutes a matrix of the third electrodes Rx (1,1) to Rx (n, o). In this embodiment, the shape of each third electrode Rx is square. As will be described later, the first electrode Ty and the second electrode Tx are arranged so as to cover the gap between the adjacent third electrodes Rx. That is, the width of the first electrode Ty and the second electrode Tx is larger than the gap between the third electrodes Rx. The shape of the third electrode Rx may be any other shape.

The materials of the first electrode pattern Ty, the second electrode pattern Tx, and the third electrode pattern Rx preferably show a surface resistance value (conductivity) of several mΩ to several hundred Ω, and for example, indium oxide, tin oxide, and the like. The film can be formed of a metal oxide such as indium tin oxide (ITO) or tin antimonic acid, or a metal such as gold, silver, copper, platinum, palladium, aluminum or rhodium. As a method for forming the first electrode pattern Ty and the second electrode pattern Tx made of these materials, a transparent conductive film is formed by a PVD method such as a sputtering method, a vacuum deposition method or an ion plating method, or a CVD method or a coating method. There are a method of patterning by etching after forming, a printing method, and the like.
In the above structure, the second insulator 13 as an elastic body that can be deformed according to the stress from the input surface is interposed between the second electrode pattern Tx and the third electrode pattern Rx. Therefore, the second electrode pattern Tx and the first electrode pattern Ty can be displaced with respect to the third electrode pattern Rx due to the stress from the input surface.
The second electrode Tx, the first electrode Ty, and the first insulator 15 also need to be soft to some extent. This is because if a highly rigid material such as a PET film is laminated, the rigidity of the PET film hinders the elastic deformation of the second insulator 13.

The sensor unit 3 has a protective layer 17. The upper surface of the protective layer 17 is an input surface that a finger touches. The protective layer 17 is a layer for protecting the electrode pattern described above, and has a function of preventing the finger and the electrode pattern from conducting each other and preventing damage to the electrode pattern. The protective layer 17 is, for example, a urethane film and has a thickness of 0.05 mm. The protective layer 17 is an arbitrary member and can be omitted.

A fourth electrode pattern Ta is provided on the lower surface of the protective layer 17. The fourth electrode pattern Ta is a solid pattern that covers all of the first electrode pattern Ty, the second electrode pattern Tx, and the third electrode pattern Rx. The fourth electrode pattern Ta is also an arbitrary member. Further, since the fourth electrode pattern Ta may cover the third electrode pattern Rx, it may be formed between the first electrode patterns Ty on the same plane as the first electrode pattern Ty. The fourth electrode pattern Ta is held at a constant potential and shuts out electrical noise from the outside.
The protective layer 17 and the first insulator 15 are fixed to each other by PSA 19 as an insulating layer.

The first insulator 15 is thinner than the second insulator 13. The thickness of the first insulator 15 is preferably in the range of 20% or less of the thickness of the second insulator 13, and more preferably in the range of 10% or less. For example, when the thickness of the second insulator 13 is 1 mm, the thickness of the first insulator 15 is 0.07 mm. In this device, the distance between the first electrode pattern Ty and the second electrode pattern Tx is set short by setting the second insulator 13 thin. Therefore, when the first electrode pattern Ty and the second electrode pattern Tx are displaced with respect to the third electrode Rx, the amount by which the first electrode pattern Ty is displaced with respect to the third electrode Rx and the second electrode pattern Tx are second. There is no large difference in the amount of displacement with respect to the three electrodes Rx.

(3) Shear Stress Detection Principle With reference to FIGS. 5 to 7, the change in electrode position when stress is applied to the input surface in the shear direction and the explanation of the detection principle will be qualitatively explained. FIG. 5 is a plan view showing an overlapping state of the electrode patterns. 6 and 7 are plan views showing changes in the overlapping state of the electrode patterns when a shearing force is applied.

The plurality of first electrodes Ty extend between the adjacent third electrodes Rx in the Y direction among the plurality of third electrodes Rx, so that they overlap only a part of each of the adjacent third electrodes Rx in a plan view. ing.
The plurality of second electrodes Tx extend between the third electrodes Rx adjacent to each other in the X direction among the plurality of third electrodes Rx, so that they overlap only a part of each of the adjacent third electrodes Rx in a plan view. ing.

As described above, each first electrode Ty constitutes a large number of intersections by overlapping a plurality of pairs of third electrodes Rx arranged adjacent to each other in the Y direction in a plan view. Further, each second electrode Tx constitutes a large number of intersections by overlapping a plurality of pairs of third electrodes Rx arranged adjacent to each other in the X direction in a plan view.

Using FIG. 5, among the third electrode patterns Rx, the third electrode Rx (a-1, b + 1) to the third electrode Rx (a + 1, b-1) (a and b are arbitrary natural numbers) and their overlaps. Consider the second electrode Tx (d), the second electrode Tx (d + 1), the first electrode Ty (c), and the first electrode Ty (c + 1). FIG. 5 shows the overlap of the first electrode Ty, the second electrode Tx, and the third electrode Rx in the state where there is no stress. Each of the second electrode Tx and the first electrode Ty has an overlap with the third electrode Rx and has a mutual capacitance substantially proportional to the area thereof.

Hereafter, the four hatched overlaps A to D will be examined.
Overlap A: Between Rx (a-1, b) / Tx (d) Overlap B: Between Rx (a, b) / Tx (d) Overlap C: Between Rx (a, b + 1) / Ty (c) Overlap D: Between Rx (a, b) / Ty (c)

Further, the mutual capacitance in the overlapping A to D will be represented by the following code representation.
Mutual capacitance of overlapping A: C [Rx (a-1, b) / Tx (d)]
Mutual capacitance of overlapping B: C [Rx (a, b) / Tx (d)]
Mutual capacitance of overlapping C: C [Rx (a, b + 1) / Ty (c)]
Mutual capacitance of overlapping D: C [Rx (a, b) / Ty (c)]

As shown in FIG. 6, when the input surface is stressed in the + X direction, the second electrode Tx and the first electrode Ty move in the + X direction with respect to the third electrode Rx, and the overlapping area changes accordingly. .. Specifically, the mutual capacitance C [Rx (a, b) / Tx (d)] of the overlap B increases, and the mutual capacitance C [Rx (a-1, b) / Tx (d)] of the overlap A increases. Decrease. On the other hand, the mutual capacitance C [Rx (a, b + 1) / Ty (c)] of the overlap C and the mutual capacitance C [Rx (a, b) / Ty (c)] of the overlap D do not change.
As shown in FIG. 7, when the input surface is stressed in the + Y direction, the second electrode Tx and the first electrode Ty move in the + Y direction with respect to the third electrode Rx, and the overlapping area changes accordingly. To do. Specifically, the mutual capacitance C [Rx (a, b + 1) / Ty (c)] of the overlap C increases, and the mutual capacitance C [Rx (a, b) / Ty (c)] of the overlap D decreases. ..

From the above, by measuring the capacitances of the four overlapping A to D, the movement in the X direction and the Y direction can be detected, and thus the shear stress can be detected.

(4) Relationship between mutual capacitance, shear stress, and normal stress Next, the mutual capacitance between the second electrode Tx, the first electrode Ty, and the third electrode Rx, the shear stress, and the normal direction (Z direction). Quantitatively analyze the relationship with the stress of. In order to consider the X direction, FIGS. 8 to 11 show the positional relationship between the second electrode Tx (d), the third electrode Rx (a-1, b), and the third electrode Rx (a, b) as a cross-sectional view. .. 8 to 11 are schematic cross-sectional views for showing the relationship between mutual capacitance, shear stress, and stress in the normal direction.
For the stress in the Y direction, the mutual capacitance C [Rx (a, b) / Ty (c)] of the overlap D and the mutual capacitance C [Rx (a, b + 1) / Ty (c)] of the overlap C are used. Since it can be detected in the same way, it is omitted here.

FIG. 8 shows a situation in which no stress is applied. In this situation, the distance between the second electrode Tx (d) and the third electrode Rx (a-1) or the third electrode Rx (a, b) in the normal direction of the plane is set to z0, and the mutual capacitances at this time are set to z0. Can be expressed as the following formula 1.

Here, K1 and K2 are proportional constants determined by the dielectric constant and thickness of the second insulator 13, the size of each electrode pattern, and the positions in the X and Y directions, respectively.
As shown in FIG. 9, when pressed in the −Z direction, the second electrode Tx (d) is the third electrode Rx (a-1, b) and the third electrode Rx (a, b) depending on the strength of the pressure. ) Approach. That is, the distance changes from z0 to z0-Δz. In this case, the mutual capacitance C [Rx (a, b) / Tx (d)] z of the overlap B and the mutual capacitance C [Rx (a-1, b) / Tx (d)] z of the overlap A are set to Δz. Correspondingly, it changes as shown in Equation 2 below.

When Equation 1 and Equation 2 are combined, Δz is expressed as Equation 3 below.

When the deformation of the elastic body is in the elastic region, Δz is proportional to the stress, so that the stress in the −Z direction can be detected by the change in capacitance according to the mathematical formula 3.

Next, as shown in FIG. 10, consider the case where pressure (shear stress) is generated in the + X direction. In that case, the second electrode Tx moves according to the strength of the pressure. In this case, the mutual capacitance C [Rx (a, b) / Tx (d)] x of the overlap B and the mutual capacitance C [Rx (a-1, b) / Tx (d)] x of the overlap A are set to Δx. Correspondingly, it changes as in the following formula 4.

Here, Kp is a value proportional to the length of the shaded portion shown in FIG. From Equation 1 and Equation 4, Δx can be expressed as Equation 5 below.

When the deformation of the second insulator 13 is in the elastic region, Δx is proportional to the stress, so that the stress in the + X direction can be detected by the change in capacitance according to the mathematical formula 5.

Finally, as shown in FIG. 11, consider the case where the pressing in the + X direction and the pressing in the −Z direction act at the same time. In this case, it is considered that the second electrode Tx (d) moves Δz in the Z direction and further moves Δx in the X direction. Since C [Rx (a, b) / Tx (d)] zx and C [Rx (a-1, b) / Tx (d)] zx can be calculated by replacing Z0 in Equation 4 with Z−Δz, It can be expressed as the following formula 6.

From Equation 6 and Equation 1, the following Equation 7 can be obtained.

From the above, Δz is proportional to the following mathematical formula 8.

Further, from the above, Δx is proportional to the following mathematical formula 9.

As described above, since the first electrode Ty and the second electrode Tx are arranged so as to form a large number of intersections with respect to the third electrode Rx in a plan view, the mutual capacitance of the intersections can be measured by measuring the fingers. The contact position and its pressure can be detected. That is, when the finger approaches the first electrode Ty and the second electrode Tx, the mutual capacitance of the intersection near the contact position changes, and if the second insulator 13 is deformed by further pressing, the first electrode Ty and the second electrode As Tx approaches the third electrode pattern Rx, the mutual capacitance at the intersection changes.
For example, when it acts on a point where there is a shearing force in the Y direction, at the portion where the shearing force acts on the first electrode Ty, each intersection of the first electrode Ty and the pair of adjacent third electrodes Rx (first electrode Ty). The area of the portion that overlaps the pair of third electrodes Rx corresponding to each other in a plan view) is changed. As a result, the capacitance between the first electrode Ty and one third electrode Rx increases, and the capacitance between the first electrode Ty and the other third electrode Rx decreases.

(6) Connection Structure of Routed Wiring The routed wiring 80 is provided on the opposite side of the support substrate 11 from the second insulator 13. The routing wiring 80 is short-circuited to two or more electrodes that are not in the same row and adjacent rows, and are not in the same column and adjacent columns among the plurality of third electrodes Rx, and are connected in a plurality of to one-to-one manner. It is connected to the capacitance measurement circuit. As shown in FIG. 1, the third electrode Rx and the routing wiring 80 are connected by a connection line provided in the through hole 81 of the support substrate 11.
The routing wiring 80 uses, for example, a metal paste such as silver or copper as a material, and can be made into an arbitrary pattern by a normal printing method such as screen printing, offset printing, gravure printing, flexographic printing, or inkjet printing. It is formed.

Hereinafter, with reference to FIGS. 12 to 18, the connection structure between the third electrode Rx and the routing wiring 80 will be described with reference to various specific examples.

[Connection structure 1]
For example, FIG. 12 is a schematic view showing a connection structure of the third electrode pattern with the routing wiring. In the example shown in FIG. 12, the third electrode pattern consists of 4 × 4 = 16 third electrodes Rx. In the figure, each third electrode Rx is numbered 0, 1, 2, ,,,, 14, 15 from the upper left. These third electrodes Rx are connected to the routing wiring 80 via a through hole 81 of a support substrate 11 (not shown).
In this connection structure, the elements of the first electrode Ty and the second electrode Tx for measuring the mutual capacitance with the third electrode Rx are Ty (1), Ty (2), Ty (3) and Tx ( 1), Tx (2), and Tx (3) are each three. In FIG. 12, since the drawing becomes difficult to see, the first electrode Ty and the second electrode Tx are not drawn, and only their formation positions and individual numbers are shown.

In the example shown in FIG. 12, each routing wiring 80 short-circuits two third electrodes Rx that are not in the same row and adjacent rows, and are not in the same row and adjacent rows, in the middle of routing. Therefore, the number of routing wires 80 is eight.
Numbers L0, L1, ,,,, L6, and L7 are assigned to these eight routing wires 80, respectively, and an example of which third electrode Rx each is connected to is shown in FIG. FIG. 13 is a table showing a combination of short-circuited third electrodes for each routing wiring in the connection structure 1.

As described above, the number of the routing wires 80 of the connection structure 1 is only eight, which is half of the 16 third electrodes Rx. Therefore, the number of routing wires can be sufficiently reduced without using a switching element.

[Connection structure 2]
Further, FIG. 14 is a schematic view showing another example of the third electrode pattern. In the example shown in FIG. 14, the third electrode pattern consists of 12 × 12 = 144 third electrodes Rx. In the figure, each third electrode Rx is numbered 0, 1, 2, ,,,, 140, 143 from the upper left. Similar to the connection structure 1, these third electrodes Rx are connected to the routing wiring 80 via a through hole 81 of a support substrate 11 (not shown).
In this connection structure, the elements of the first electrode Ty and the second electrode Tx for measuring the mutual capacitance with the third electrode Rx are Ty (1), Ty (2), Ty (3), ... ,, Ty (11) and Tx (1), Tx (2), Tx (3) ,,,,, Tx (11), 11 each. In FIG. 14, since the drawing becomes difficult to see, the first electrode Ty and the second electrode Tx are not drawn, and only their formation positions and individual numbers are shown.

In the connection structure 2, each routing wiring 80 (not shown) short-circuits six third electrodes Rx that are not in the same row and adjacent rows, and are not in the same row and adjacent rows, in the middle of routing. Therefore, the number of routing wires 80 is 24. It should be noted that the illustration of a specific example of the routing wiring 80 is omitted here because it is very difficult to see.
L0, L1, ,,,, L22, and L23 are assigned to these 24 routing wires 80, respectively, and an example of which third electrode Rx is connected to each of them is shown in FIG. FIG. 15 is a table showing a combination of short-circuited third electrodes for each routing wiring in the connection structure 2.

As described above, the number of the routing wires 80 of the connection structure 2 is only 24, which is one sixth of the 144 third electrodes Rx. Therefore, the number of routing wires can be sufficiently reduced without using a switching element.

[Connection structure 3]
In the connection structure 3, for the same third electrode pattern as the connection structure 2, six third electrodes Rx that are not in the same row and adjacent rows and are not in the same column and adjacent columns are short-circuited as in the connection structure 2. However, the combination of the third electrodes that are short-circuited for each routing wiring is different from that of the connection structure 2 (see FIG. 16).

[Connection structure 4]
Similar to the connection structure 1, the connection structure 4 has the same third electrode pattern as the connection structure 2, and the routing wiring 80 is not in the same row and adjacent rows, and the third electrode Rx is not in the same column and adjacent columns. Two are short-circuited. Therefore, the number of routing wires 80 is 72.
The 72 routing wires 80 are assigned numbers L0, L1, ,,,, L70, and L71, respectively, and an example of which third electrode Rx each is connected to is shown in FIG.

Further, in this connection structure, each of the routing wires for the first electrode Ty and the second electrode Tx short-circuits two or three non-adjacent first electrode Ty and the second electrode Tx in the middle of routing. As a result, the number of each routing wiring for the first electrode Ty and the second electrode Tx is four.
FIG. 18A shows an example in which the four first band-shaped electrode routing wires are numbered Ly0, Ly1, Ly3, and Ly4, respectively, and which first electrode Ty is connected to each of them. Further, FIG. 18B also shows an example in which the four second band-shaped electrode routing wires are numbered Lx0, Lx1, Lx3, and Lx4, respectively, and which second electrode Tx is connected to each of them. It was.

As described above, the number of routing wires of the connection structure 4 can be reduced not only for the third electrode Rx but also for the first electrode Ty and the second electrode Tx.

(7) Control Configuration of Touch Pad Device The control configuration of the touch pad device 1 will be described with reference to FIG.
The control circuit 5 has a microcontroller 25. The microcontroller 25 is a computer having a CPU, RAM, ROM, and the like.

The control circuit 5 has a signal generation circuit 27. The signal generation circuit 27 is connected to the first electrode pattern Ty or the second electrode pattern Tx and the microcontroller 25. The signal generation circuit 27 can apply a voltage pulse to the first electrode pattern Ty or the second electrode pattern Tx.
The control circuit 5 has an ADC (analog-to-digital converter) 29. The ADC 29 is connected to the microcontroller 25 so that a digital signal can be input.
The control circuit 5 has an amplifier circuit 33. The amplifier circuit 33 is connected to the third electrode pattern Rx and the ADC 29. The amplifier circuit 33 amplifies the analog signal from the third electrode pattern Rx and transmits it to the ADC 29.

The microcontroller 25 can detect the mutual capacitance of the overlapping portion (intersection) of the first electrode pattern Ty and the second electrode pattern Tx and the third electrode Rx. That is, the microcontroller 25 has a function as a capacitance measurement circuit. Specifically, the microcontroller 25 can detect the capacitance generated between the third electrode Rx and the first electrode Ty that overlaps the third electrode Rx in a plan view. The microcontroller 25 can detect the capacitance generated between the third electrode Rx and the second electrode pattern Tx that overlaps the third electrode Rx in a plan view.
More specifically, the microcontroller 25 sequentially applies a voltage pulse with the first electrode pattern Ty or the second electrode pattern Tx as the transmitting electrode via the signal generation circuit 27, and receives the plurality of third electrodes Rx as the receiving electrodes. By measuring the reception intensity as, the change in mutual capacitance at each electrode intersection is detected.

The microcontroller 25 calculates the pressure action position based on the change in mutual capacitance at each intersection. That is, the microcontroller 25 has a function of a pressure action position calculation circuit. Since the technique for calculating the pressure action position is known, the description thereof will be omitted.

The microcontroller 25 calculates the pressure based on the change in mutual capacitance at each intersection. That is, the microcontroller 25 has a function of a pressure calculation circuit.
In this device, for example, when a finger presses the protective layer 17, the microcontroller 25 sends a signal to the second electrode Tx or the first electrode Ty, and the signal received by the third electrode Rx is an ADC 29 as a signal amplified by the amplifier circuit 33. The microcontroller 25 can measure the mutual capacitance between the second electrode Tx or the first electrode Ty and the third electrode Rx. Then, the microcontroller 25 calculates the pressure action position, and further calculates the pressure (stress in the normal direction with respect to the input surface and shear stress).

(8) Pressure action position and pressure detection control The touch detection control operation of the touch pad device 1 by the microcontroller 25 will be described with reference to FIG. FIG. 19 is a control flowchart for pressure measurement.
First, the microcontroller 25 determines the presence / absence of touch input based on the level signal from the amplifier circuit 33 (step S1).

If it is determined that the touch has been made (Yes in step S1), the microcontroller 25 measures the capacitance at the intersection of the first electrode pattern Ty and the third electrode pattern Rx (step S2).
The microcontroller 25 measures the capacitance at the intersection of the second electrode pattern Tx and the third electrode pattern Rx (step S3).
The value of the capacitance at each intersection is stored in the memory of the microcontroller 25.

The order of steps S2 and S3 is not limited to the above embodiment.
Next, the microcontroller 25 determines the pressure action position and the pressure of the touch, respectively (step S4).

In the measurement of the capacitance at each intersection of steps S2 and S3, the microcontroller 25 reads the signals from the third electrode Rx in order from the routing wiring 80.
At this time, since the third electrodes Rx short-circuited in the respective routing wires 80 are not in the same row and adjacent rows, and are not in the same column and adjacent columns, the capacitance value is set to all the first. The combination of the electrode Ty, the second electrode Tx, and the third electrode Rx can be measured separately.

As a result of the above, the in-plane distribution of all the stresses in the X, Y, and Z directions applied to the sheet-shaped elastic body can be detected. As an application example of the above device, when touched by a plurality of fingers, the force of each finger in the XYZ direction can be detected. When applied as an input device such as a touch pad of a PC, stress in the rotational direction can be detected in a pseudo manner, so that new gestures such as "pinch" and "twist the surface" can be detected. It can also be a new input device for manipulating 3D images.

As an application example of this sensor, there is one that measures a body pressure distribution. For example, it is desired to measure the shear force when measuring the pressure distribution applied to the sole of the foot for walking or running measurement. In addition, if it is laid on a bed, the distribution of shearing force applied to the sleeping person can be measured, which is useful for research and prevention of bedsores.

2. Other Embodiments Although one or more embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. In particular, the plurality of embodiments and modifications described herein can be arbitrarily combined as needed.

For example, in the above embodiment, the signal generation circuit 27 is connected to the first electrode pattern Ty or the second electrode pattern Tx, and the amplifier circuit 33 is connected to the third electrode pattern Rx, but the present invention is not limited to this. That is, the signal generation circuit 27 may be connected to the third electrode pattern Rx, and the amplifier circuit 33 may be connected to the first electrode pattern Ty or the second electrode pattern Tx.

Further, in the above embodiment, the plurality of routing wires 80 are provided on the side opposite to the second insulator 13 of the support substrate 11, but the present invention is not limited to this. For example, as shown in FIG. 20, the plurality of routing wires 80 are provided on the second insulator 13 side of the support substrate 11, are covered with the insulating film 90, and are on the second insulator 13 side of the insulating film 90. A plurality of third electrodes Rx may be located at the same location.
In this case, in the connection between the plurality of third electrodes Rx and the plurality of routing wires 80, all the third electrodes Rx can be connected through the through holes 81 of the insulating film 90. Further, the connection between the plurality of third electrodes Rx and the plurality of routing wires 80 is made through the through holes 81 of the insulating film 90 except for the peripheral electrodes of the third electrodes Rx spread in a grid pattern. It may be connected.

Examples of the insulating film 90 include thermoplastic resins such as methacrylic acid ester resin, acrylic acid ester resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyamide resin and alkyd resin, melamine resin, urethane resin, epoxy resin, urea resin and poly. Some consist of heat-curable resins such as siloxane resins, melamine acrylate resins, urethane acrylate resins, epoxy acrylate resins, methacrylic acrylate resins, acrylate resins such as acrylic acrylate resins, and photocurable resins such as polyvinyl alcohol resins. .. The insulating film 90 uses a normal printing method such as screen printing, offset printing, gravure printing, flexographic printing, and the like. It is formed in an arbitrary pattern having a through hole 81 or the like. Further, the through hole 81 may be formed by a photo process.

The stacking order of each layer and the presence or absence of other layers are not limited to the above-described embodiment.

The material and thickness of each layer are not limited to the above-described embodiment.

The control configuration is not limited to the above embodiment.
The control flowchart is not limited to the above embodiment. Specifically, the order and presence / absence of the plurality of steps are not particularly limited. In particular, the steps described before and after may be performed all at the same time or partly at the same time.

The capacitance may be measured between the fourth electrode pattern Ta and the third electrode pattern Rx.
A weak pressure may be measured by measuring the capacitance of Ta of the fourth electrode pattern.

The support substrate 11 is made of an insulator having a two-layer structure, and a GND electrode pattern may be provided as an intermediate layer of these insulators.
The GND electrode pattern is an opening pattern that covers all but the third electrode pattern Rx. The GND electrode pattern is also an arbitrary member. Further, the GND electrode pattern is held at a constant potential, and a third electrode pattern is held so as not to have an unnecessary capacitance between the routing wiring 80 and the first electrode pattern Ty or the second electrode pattern Tx. The gap between the electrodes Rx is guarded.

Further, on the outer side of the outermost first electrode (Ty (1) and Ty (l) in FIG. 2) among the elements of the first electrode pattern Ty, the X direction (an example of the first direction) (not shown in FIG. 2). Electrodes TyGND (an example of a third band-shaped electrode) extending to the above may be provided respectively. The electrode TyGND overlaps only a part of each of the outer edges of the grid of the third electrode pattern Rx in a plan view and is held at a constant potential.
There is a difference in the hardness of the laminate of this device between the portion where the first electrode Ty is present and the portion where the first electrode Ty is not present. That is, since the easiness of deformation differs depending on the density of the electrodes, the sensitivity differs in the plane. By overlapping the first electrode Ty arranged in the Y direction not only with the gap between the third electrodes Rx but also with the side opposite to the gap at the outermost third electrode Rx in the Y direction as a dummy electrode, a hard part is felt. It is evenly distributed in the Y direction over the entire compression region. Therefore, since the densities of the electrodes are equal in the plane, the pressure sensitivity in the plane can be made equal, and the correction of the measured value is unnecessary.

For the same purpose, the outermost second electrode (Tx (1) and Tx (m) in FIG. 3) of the elements of the second electrode pattern Tx is further outside in the Y direction (second) (not shown in FIG. 3). Electrodes TxGND (an example of a fourth band-shaped electrode) extending in the direction (an example of a direction) may be provided respectively. The electrode TxGND overlaps only a part of each of the outer edges of the grid of the third electrode pattern Rx in a plan view, and is held at a constant potential.

The present invention is widely applicable to pressure detectors.

1,101: Touch pad device 3,103: Sensor unit 5,105: Control circuit 11: Support substrate 13: Second insulator 15: First insulator 25: Microcontroller 27: Signal generation circuit 33: Amplifier circuit 35: Gate drive circuit 80: Route wiring 81: Through hole 90: Insulation film Rx: Third electrode pattern Ta: Fourth electrode pattern Tx: Second electrode pattern Ty: First electrode pattern

Claims (8)

A support substrate, which is laminated in order from the side opposite to the side where pressure is input, a second insulator which has lower rigidity than the support substrate and elastically deforms when pressure is applied, and a first insulator.
A plurality of electrodes provided so as to be spread in a grid pattern between the second insulator and the support substrate, and
By extending in the first direction on the side of the first insulator opposite to the second insulator, and extending between the electrodes adjacent to each other in the direction intersecting the first direction among the plurality of electrodes. A plurality of first band-shaped electrodes overlapping only a part of each of the adjacent electrodes in a plan view,
An electrode that is provided between the first insulator and the second insulator in a second direction that intersects the first direction and is adjacent to the plurality of electrodes that intersect the second direction. A plurality of second band-shaped electrodes extending between each other and overlapping only a part of each of the adjacent electrodes in a plan view,
The capacitance generated between the electrode and the first band-shaped electrode overlapping the electrode in a plan view can be detected, and between the electrode and the second band-shaped electrode overlapping the electrode in a plan view. Capacitance measurement circuit that can detect the capacitance generated in
When pressure is applied to deform the second insulator, the overlapping area of the electrodes overlapping each other in the plan view and the first band-shaped electrode and / or the electrodes overlapping each other in the plan view and the second band-shaped electrode A pressure calculation circuit that calculates the shear force based on the capacitance measurement result obtained by the capacitance measurement circuit by changing the overlapping area of
A plurality of pairs are provided on the opposite side of the support substrate to the second insulator, and are short-circuited to two or more electrodes that are not in the same row and adjacent rows, and are not in the same row and adjacent rows among the plurality of electrodes. A plurality of routing wires that are connected by one and one end of which is connected to the capacitance measurement circuit.
Pressure detector with. The pressure detection device according to claim 1, wherein the connection between the plurality of electrodes and the plurality of routing wires is such that all the electrodes are connected through through holes in the support substrate. The first aspect of claim 1 is that the plurality of electrodes and the plurality of routing wires are connected via through holes in the support substrate, except for the peripheral electrodes among the electrodes laid out in a grid pattern. Pressure detector. A support substrate, which is laminated in order from the side opposite to the side where pressure is input, a second insulator which has lower rigidity than the support substrate and elastically deforms when pressure is applied, and a first insulator.
A plurality of electrodes provided so as to be spread in a grid pattern between the second insulator and the support substrate, and
By extending in the first direction on the side of the first insulator opposite to the second insulator, and extending between the electrodes adjacent to each other in the direction intersecting the first direction among the plurality of electrodes. A plurality of first band-shaped electrodes overlapping only a part of each of the adjacent electrodes in a plan view,
An electrode that is provided between the first insulator and the second insulator in a second direction that intersects the first direction and is adjacent to the plurality of electrodes that intersect the second direction. A plurality of second band-shaped electrodes extending between each other and overlapping only a part of each of the adjacent electrodes in a plan view,
The capacitance generated between the electrode and the first band-shaped electrode overlapping the electrode in a plan view can be detected, and between the electrode and the second band-shaped electrode overlapping the electrode in a plan view. Capacitance measurement circuit that can detect the capacitance generated in
When pressure is applied to deform the second insulator, the overlapping area of the electrodes overlapping each other in the plan view and the first band-shaped electrode and / or the electrodes overlapping each other in the plan view and the second band-shaped electrode A pressure calculation circuit that calculates the shear force based on the capacitance measurement result obtained by the capacitance measurement circuit by changing the overlapping area of
It is provided on the second insulator side of the support substrate, is covered with an insulating film, and is not in the same row and adjacent rows among the plurality of electrodes located on the second insulator side of the insulating film, and A plurality of routing wires that are short-circuited to two or more electrodes that are not in the same row or adjacent rows and are connected in a multiple-to-one manner and one end of which is connected to the capacitance measurement circuit
Pressure detector with. The pressure detection device according to claim 4, wherein the connection between the plurality of electrodes and the plurality of routing wires is such that all the electrodes are connected through through holes of the insulating film. The fourth aspect of claim 4 is that the plurality of electrodes and the plurality of routing wires are connected via through holes of the insulating film, except for the peripheral electrodes among the electrodes laid out in a grid pattern. Pressure detector. For a plurality of first band-shaped electrodes which are short-circuited to two or more non-adjacent first band-shaped electrodes among the plurality of first band-shaped electrodes and are connected in a plurality of to one-to-one manner, one end of which is connected to the capacitance measurement circuit. The pressure detection device according to claim 1 to 6, further comprising routing wiring. For a plurality of second band-shaped electrodes which are short-circuited to two or more non-adjacent second band-shaped electrodes among the plurality of second band-shaped electrodes and are connected in a plurality of to one-to-one manner, one end of which is connected to the capacitance measurement circuit. The pressure detection device according to claim 1 to 7, further comprising routing wiring.

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