Pressure sensor unit

Abstract

A pressure sensitive sensor unit (1A) comprises first pressure sensitive sensors (2A to 2D) having an output that changes in accordance with the magnitude of an applied load, a second pressure sensitive sensor (2E) having an output that changes in accordance with the magnitude of an applied load, a plate member (5) arranged so as to encompass the first and second pressure sensitive sensors as seen in a plan view, first load transmitting members (3A to 3D) interposed between the first pressure sensitive sensors and the plate member, and a second load transmitting member (4) interposed between the second pressure sensitive sensor and the plate member, wherein: the first load transmitting members transmit loads belonging to first load areas to the first pressure sensitive sensors; and the second load transmitting member transmits a load belonging to a second load area, larger than the first load areas, to the second pressure sensitive sensor.

Description

Technical Field

[0001] The present invention relates to a pressure-sensitive sensor unit including a pressure-sensitive sensor that detects the magnitude of an applied load. For designated countries where incorporation by reference is permitted, the contents described in Japanese Patent Application No. 2022-005182 filed in Japan on January 17, 2022 are incorporated herein by reference and made part of the description of this specification.

Background Art

[0002] Conventional pressure-sensitive sensors include an upper circuit board having a pair of comb-shaped electrodes that intermesh with each other, and a lower circuit board having a disk-shaped electrode facing the comb-shaped electrodes. In this pressure-sensitive sensor, at least one of the three electrodes described above serves as a pressure-sensitive resistor (see, for example, Patent Document 1 (paragraphs

[0002] to

[0005] , FIGS. 1(a) to 1(c))). Further, another conventional pressure-sensitive sensor includes an upper circuit board having a disk-shaped pressure-sensitive resistor, and a lower circuit board having a disk-shaped counter electrode facing the pressure-sensitive resistor (see, for example, Patent Document 1 (paragraphs

[0006] to

[0008] , FIGS. 2(a) to 2(c))).

[0003] In the above pressure-sensitive sensor, when a load is applied to the upper circuit board from above, the electrodes arranged below the applied portion come into direct contact with each other. Then, as this load further increases, the contact area between the electrodes increases and the resistance value decreases. In the above pressure-sensitive sensor, the magnitude of the load is detected by utilizing such a change in the resistance value.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The conventional pressure sensor as described above has a problem in that the detectable load range may be narrow.

[0006] The problem to be solved by the present invention is to provide a pressure sensor unit capable of detecting a wide load range.

Means for Solving the Problem

[0007] [1]Aspect 1 of the present invention includes a first pressure sensor whose output changes according to the magnitude of an applied load, a second pressure sensor whose output changes according to the magnitude of an applied load, a plate member arranged so as to include the first and second pressure sensors in a plan view, a first load transmission member interposed between the first pressure sensor and the plate member, and a second load transmission member interposed between the second pressure sensor and the plate member. The first load transmission member transmits a load belonging to a first load range to the first pressure sensor, and the second load transmission member transmits a load belonging to a second load range larger than the first load to the second pressure sensor. Domain This is a pressure sensor unit.

[0008] [2]Aspect 2 of the present invention may be a pressure sensor unit in the pressure sensor unit of Aspect 1, in which the second load transmission member does not transmit a load belonging to the first load range to the second pressure sensor.

[0009] [3]Aspect 3 of the present invention may be a pressure sensor unit in the pressure sensor unit of Aspect 1 or Aspect 2, in which the height of the first load transmission member is higher than the height of the second load transmission member, or the second load transmission member is softer than the first load transmission member.

[0010] [4]Aspect 4 of the present invention is a pressure-sensitive sensor unit according to any one of Aspects 1 to 3, wherein the first pressure-sensitive sensor includes first and second electrodes that are electrically connected to each other by applying a load, and the second pressure-sensitive sensor includes third and fourth electrodes that are electrically connected to each other by applying a load, and the pressure-sensitive sensor unit may be a pressure-sensitive sensor unit including a resistor electrically connected in series to the first or second electrode of the first pressure-sensitive sensor.

[0011] [5]Aspect 5 of the present invention is a pressure-sensitive sensor unit according to Aspect 4, wherein the resistance value of the resistor may be greater than the resistance value in the on-state of the second pressure-sensitive sensor.

[0012] [6]Aspect 6 of the present invention is a pressure-sensitive sensor unit according to Aspect 4 or Aspect 5, wherein the pressure-sensitive sensor unit includes a plurality of the first pressure-sensitive sensors, and the pressure-sensitive sensor unit includes a first electrode group composed of a plurality of the first electrodes electrically connected to each other, and a second electrode group composed of a plurality of the second electrodes electrically connected to each other, and the resistor may be a pressure-sensitive sensor unit electrically connected in series to the first or second electrode group.

[0013] [7]Aspect 7 of the present invention is a pressure-sensitive sensor unit according to any one of Aspects 4 to 6, wherein the pressure-sensitive sensor unit includes a first base material and a second base material facing the first base material, the first electrode is provided on the first base material, and the second electrode is provided on the first base material so as to face a first connector provided on the second base material so as to face the first electrode, or the second electrode may be provided on the second base material so as to face the first electrode.

[0014] [8]Aspect 8 of the present invention is that in any one of the pressure-sensitive sensor units of Aspects 4 to 6, the pressure-sensitive sensor unit includes a first base material and a second base material facing the first base material, the third electrode is provided on the first base material, and the fourth electrode is provided on the first base material so as to face a second connection body provided on the second base material so as to face the third electrode, or it may be a pressure-sensitive sensor unit provided on the second base material so as to face the third electrode.

[0015] [9]Aspect 9 of the present invention is that in the pressure-sensitive sensor unit of Aspect 7 or Aspect 8, the height of the first load transmission member is higher than the height of the second load transmission member, the first load transmission member is joined to either one of the first or second base materials and is also joined to the plate member, and the second load transmission member may be a pressure-sensitive sensor unit joined to only one of the first base material, the second base material, or the plate member.

[0016]

[10] Aspect 10 of the present invention is that in any one of the pressure-sensitive sensor units of Aspects 7 to 9, the pressure-sensitive sensor unit includes a spacer interposed between the first base material and the second base material, the spacer has a first opening for accommodating the first and second electrodes of the first pressure-sensitive sensor and a second opening for accommodating the third and fourth electrodes of the second pressure-sensitive sensor, and the width of the first opening may be larger than the width of the second opening.

[0017]

[11] Aspect 11 of the present invention is that in the pressure-sensitive sensor unit according to any one of Aspects 1 to 10, the pressure-sensitive sensor unit includes a plurality of the first pressure-sensitive sensors and a plurality of the first load transmission members, the plurality of the first pressure-sensitive sensors are arranged around the second pressure-sensitive sensor, and the plurality of the first load transmission members may be a pressure-sensitive sensor unit arranged around the second load transmission member.

Advantages of the Invention

[0018] The pressure-sensitive sensor unit according to the present invention includes a first load transmission member that transmits a load belonging to a first load range to a first pressure-sensitive sensor, and a second load transmission member that transmits a load belonging to a second load range having a larger load than the first load range to a second pressure-sensitive sensor. Therefore, the pressure-sensitive sensor unit according to the present invention can detect loads in both the first region and the second region, so that the detectable load range can be widened.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0021] FIG. 1 is a plan view showing an example of a pressure sensor unit according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. Note that FIG. 2 shows the pressure sensor unit when no load is applied (no-load state).

[0022] The pressure sensor unit 1A is a pressure sensor unit whose output changes according to the magnitude of the applied load. In this embodiment, a resistance value is used as this output. Note that this output is not limited to a resistance value, and may be, for example, a voltage value.

[0023] As shown in FIGS. 1 and 2, the pressure sensor unit 1A in this embodiment includes a pressure sensor sheet 2, a plurality (four in this example) of first load transmission members 3A to 3D, a second load transmission member 4, and a plate member 5.

[0024] The pressure sensor sheet 2 includes pressure sensors 2A to 2E whose resistance values change according to the magnitude of the applied load. The first pressure sensors 2A to 2D in this embodiment are used to detect loads (low loads) belonging to a first load range (low load range), and the second pressure sensor 2E is used to detect loads (high loads) belonging to a second load range (high load range) larger than the first load range.

[0025] Here, the load range is the range of the magnitude of the load. The first load range is not particularly limited, but for example, it may be 20 gf to 500 gf, and the second load range is not particularly limited, but for example, it may be 500 gf to 2000 gf.

[0026] As shown in FIGS. 1 and 2, the pressure-sensitive sensor sheet 2 of the present embodiment includes a lower membrane substrate 10, an upper membrane substrate 20, and a spacer 30.

[0027] As shown in FIGS. 1 and 2, the lower membrane substrate 10 includes a first base material 11, a first wiring pattern 12, a first electrode group 13 (13A to 13D), a second electrode group 14 (14A to 14D), a third electrode 13E, a fourth electrode 14E, a second wiring pattern 15, a resistor 16, and a third wiring pattern 17.

[0028] The first base material 11 of the lower membrane substrate 10 is a film-like member made of a material having flexibility and electrical insulation. Examples of the material constituting the first base material 11 include resin materials, and more specifically, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) can be exemplified. Note that the first base material 11 may not have flexibility.

[0029] As shown in FIG. 1, the first wiring pattern 12 is formed on the upper surface of the first base material 11. The first wiring pattern 12 of the present embodiment functions as a lead wiring for electrically connecting the first electrode group 13 and the third electrode 13E to a power source (not shown).

[0030] The first wiring pattern 12 has a first wiring portion 121a, a second wiring portion 121b, and a first external terminal portion 122. The first wiring portion 121a has a U-shaped wire form. One end of this first wiring portion 121a is connected to the second wiring portion 121b. The second wiring portion 121b has an L-shaped wire form, and one end of the second wiring portion 121b is connected to the first external terminal portion 122. This first external terminal portion 122 is a terminal portion electrically connected to a power source (not shown).

[0031] This first wiring pattern 12 is formed by printing a conductive paste on the upper surface of the first base material 11 and solidifying (curing) it. The conductive paste is composed of conductive particles, a binder resin, water or a solvent, and various additives. The conductive paste constituting the first wiring pattern 12 is a low-resistance conductive paste having a relatively small electrical resistance value. Note that the formation method of the first wiring pattern 12 is not particularly limited to the above. For example, instead of the conductive paste, the first wiring pattern 12 may be formed by etching a metal foil.

[0032] Specific examples of the conductive particles can include silver, copper, nickel, tin, bismuth, zinc, indium, palladium, and alloys thereof. Also, specific examples of the binder resin can include acrylic resin, polyester resin, epoxy resin, vinyl resin, urethane resin, phenol resin, polyimide resin, silicone resin, fluororesin, etc. Furthermore, examples of the solvent contained in the conductive paste can include α-terpineol, butyl carbitol acetate, butyl carbitol, 1-decanol, butyl cellosolve, diethylene glycol monoethyl ether acetate, tetradecane, etc.

[0033] Although not particularly limited, in the present embodiment, as the low-resistance conductive paste, a silver paste having silver as the main component of the conductive particles or a copper paste having copper as the main component of the conductive particles is used. Note that a metal salt may be used as the conductive particles contained in the conductive paste. Examples of the metal salt include salts of the above-described metals. Further, the binder resin may be omitted from the above-described conductive paste. Further, instead of the above-described conductive paste, a conductive ink may be used.

[0034] The method for applying the conductive paste is not particularly limited, and either a contact application method or a non-contact application method may be used. Specific examples of the contact application method include screen printing, gravure printing, offset printing, gravure offset printing, flexographic printing, and the like. On the other hand, specific examples of the non-contact application method include inkjet printing, spray coating method, dispense coating method, jet dispense method, and the like. Further, the heat source for curing the conductive paste is not particularly limited, and examples thereof include an electric heating oven, an infrared oven, a far-infrared furnace (IR), a near-infrared furnace (NIR), a laser irradiation device, and the like, and a heat treatment combining these may also be used.

[0035] The first electrode group 13 is connected to the first wiring portion 121a of the first wiring pattern 12. This first electrode group 13 includes a plurality (four in this example) of first electrodes 13A to 13D. In the first electrode group 13, the first electrodes 13A to 13D are arranged on the first wiring portion 121a so as to be electrically connected in parallel to each other. Further, in the present embodiment, the first electrodes 13A to 13D are arranged so as to surround the third electrode 13E and the fourth electrode 14E.

[0036] Since the first electrodes 13A to 13D in the present embodiment all have the same configuration, the configuration of the first electrode 13A will be described here as a representative.

[0037] The first electrode 13A is a comb-shaped electrode. The first electrode 13A has a connection wiring portion 131 and a plurality (three in this example) of comb teeth portions 132. The connection wiring portion 131 is a linear portion extending along the Y direction in the figure, and one end of the connection wiring portion 131 is connected to the first wiring portion 121a of the first wiring pattern 12.

[0038] A plurality of comb teeth portions 132 are connected to the other end side of this connection wiring portion 131. As shown in FIGS. 1 and 2, the plurality of comb teeth portions 132 are arranged in parallel along the Y direction in the figure and protrude from the connection wiring portion 131 toward the +X direction in the figure.

[0039] A second electrode group 14 is arranged on the first base material 11 so as to be adjacent to the first electrode group 13. This second electrode group 14 includes a plurality (four in this example) of second electrodes 14A to 14D.

[0040] The second electrodes 14A to 14D are respectively arranged so as to be adjacent to the first electrodes 13A to 13D. Further, the second electrodes 14A to 14D are arranged so as to be slightly separated from the first electrodes 13A to 13D so as to be electrically insulated from the first electrodes 13A to 13D. In the present embodiment, the second electrodes 14A to 14D are arranged so as to surround the third electrode 13E and the fourth electrode 14E, similarly to the first electrodes 13A to 13D.

[0041] In the present embodiment, a plurality of first pressure sensors 2A to 2D are arranged so as to surround the second pressure sensor 2E, but the present invention is not limited to this. For example, in the pressure sensor unit 1A, the first pressure sensor and the second pressure sensor may be arranged so as to be arranged alternately.

[0042] Since the second electrodes 14A to 14D in the present embodiment all have the same configuration, the configuration of the second electrode 14A will be described here as a representative.

[0043] The second electrode 14A has a plane shape that is point-symmetrical with respect to the first electrode 13A. The second electrode 14A has a connection wiring portion 141 and a plurality (three in this example) of comb teeth portions 142. The connection wiring portion 141 is a linear portion extending along the Y direction in the figure. A plurality of comb teeth portions 142 are connected to one end side of this connection wiring portion 141. The plurality of comb teeth portions 142 are arranged along the Y direction in the figure and project from the connection wiring portion 141 toward the -X direction in the figure. And this comb teeth portion 142 enters between the comb teeth portions 132 of the first electrode 13A and faces the comb teeth portions 132 of the first electrode 13A along the Y direction in the figure.

[0044] The first and second electrodes 13A to 13D, 14A to 14D as described above are formed by printing a conductive paste on the upper surface of the first base material 11 and solidifying (curing) it. The conductive paste is a high-resistance conductive paste having a relatively high electrical resistance value. Note that, instead of the conductive paste, a conductive ink may be used.

[0045] Examples of the conductive particles contained in the conductive paste include, for example, carbon. Specific examples of this carbon include, for example, graphite and carbon black. Also, specific examples of the binder resin and the solvent can be exemplified by the above materials. Note that the binder resin may be omitted from the conductive paste. The application method of the conductive paste is not particularly limited, and either the above contact application method or non-contact application method may be used.

[0046] A second wiring pattern 15 is connected to the other end of the connection wiring portion 141 of the second electrodes 14A to 14D. This second wiring pattern 15 electrically connects the second electrodes 14A to 14D and the resistor 16.

[0047] The second wiring pattern 15 is not particularly limited, but is composed of the same material as the first wiring pattern 12. Also, this second wiring pattern 15 is not particularly limited, but is formed by printing a conductive paste on the upper surface of the first base material 11 and solidifying (curing) it, similar to the first wiring pattern 12.

[0048] The second wiring pattern 15 has a third wiring portion 151 and a first resistor connection portion 153. The third wiring portion 151 has a linear shape, and on this third wiring portion 151, the second electrodes 14A to 14D are arranged so as to be electrically connected in parallel to each other.

[0049] The first resistor connection portion 153 is connected to the other end of this third wiring portion 151. The first resistor connection portion 153 of the present embodiment is not particularly limited, but is a land pattern wider than the third wiring portion 151.

[0050] A resistor 16 is connected to this first resistor connection portion 153. The resistor 16 in the present embodiment is arranged on the second wiring pattern 15 so as to be electrically connected in series to the second electrode group 14. This resistor 16 has a resistance value R1 (constant) larger than the resistance value R x2 in the on state of the second pressure sensor 2E. This resistor 16 is provided to make the combined resistance R0 (=R1 + R x1 ) of the resistor 16 and the resistance value R x1 in the on state of the first pressure sensors 2A to 2D larger than the resistance value R x2 in the on state of the second pressure sensor 2E (R0 > R x2 ).

[0051] Note that the "on state" of the first pressure sensors 2A to 2D means a state in which the first electrodes 13A to 13D and the second electrodes 14A to 14D are electrically connected via the connectors 22A to 22D. The "on state" of the second pressure sensor 2E means a state in which the third electrode 13E and the fourth electrode 14E are electrically connected via the connector 22E. Here, in the present embodiment, "electrically connecting" the connector and the electrode means a state in which the resistance value between the connector and the electrode is equal to or less than a predetermined threshold value, and does not include a state in which the connector and the electrode are merely in contact. Further, the resistance value R x1 ,R x2 is a variable that changes according to the magnitude of the load, as will be described later.

[0052] This resistor 16 is not particularly limited, but may be a resistor. Alternatively, the resistor 16 may be formed by printing a high-resistance conductive paste on the upper surface of the first base material 11 and solidifying (curing) it. Examples of the conductive particles contained in the conductive paste include the above-described carbon and the like. Specific examples of the binder resin and the solvent can be the above-described materials. Note that the binder resin may be omitted from the conductive paste. The method of applying the conductive paste is not particularly limited, and either the above-described contact coating method or non-contact coating method may be used.

[0053] In the present embodiment, the resistor 16 is electrically connected in series to the second electrode group 14 and is disposed on the power supply side with respect to the first pressure sensors 2A to 2D, but is not limited thereto. For example, the resistor 16 may be electrically connected in series to the first electrode group 13 and disposed on the power supply side with respect to the first pressure sensors 2A to 2D.

[0054] Although not specifically shown, specifically, in the first wiring pattern 12 shown in FIG. 1, by interposing the resistor 16 between the first wiring portion 121a and the second wiring portion 121b, all the first electrodes 13A to 13 included in the first electrode group 13 DOn the other hand, the resistors 16 can be electrically connected in series. Also in this case, the above-described combined resistance R0 (=R1 + R x1 ) can be made larger than the resistance value Rx2 in the ON state of the second pressure sensor 2E (R0 > R x2 ).

[0055] A comb-shaped third electrode 13E is connected to the other end of the second wiring portion 121b of the first wiring pattern 12. This third electrode 13E also has the same configuration as the first electrode 13A, and has a connection wiring portion 131 and a plurality of comb teeth portions 132. However, the connection wiring portion 131 of the third electrode 13E extends along the X direction in the figure. Also, the comb teeth portions 132 are arranged along the X direction in the figure and protrude from the connection wiring portion 131 toward the -Y direction in the figure.

[0056] A comb-shaped fourth electrode 14E is disposed on the first base material 11 so as to be adjacent to the third electrode 13E. The fourth electrode 14E is disposed so as to be slightly separated from the third electrode 13E so as to be electrically insulated from the third electrode 13E.

[0057] This fourth electrode 14E also has the same configuration as the second electrode 14A, and has a connection wiring portion 141 and a plurality of comb teeth portions 142. However, the connection wiring portion 141 of the fourth electrode 14E extends along the X direction in the figure. Also, the comb teeth portions 142 of the fourth electrode 14E are arranged along the X direction in the figure and protrude from the connection wiring portion 141 toward the +Y direction in the figure.

[0058] The third wiring pattern 17 is connected to the resistor 16 and the fourth electrode 14E. This third wiring pattern 17 functions as a lead wiring for electrically connecting the second electrode group 14 and the fourth electrode 14E to the ground (not shown).

[0059] The third wiring pattern 17 has a fourth wiring portion 171a, a fifth wiring portion 171b, a second external terminal portion 172, and a second resistor connection portion 173. The fourth wiring portion 171a has a linear shape extending in the Y direction in the figure, and one end of the fourth wiring portion 171a is connected to the second external terminal portion 172.

[0060] This second external terminal portion 172 is a terminal portion electrically connected to ground (not shown). In this embodiment, the first external terminal portion 122 of the first wiring pattern 12 is electrically connected to a power supply (not shown), and the second external terminal portion 172 of the third wiring pattern 17 is connected to ground (not shown), but it is not limited thereto. Conversely to this embodiment, the first external terminal portion 122 may be electrically connected to ground (not shown), and the second external terminal portion 172 may be connected to a power supply (not shown).

[0061] The other end of the fourth wiring portion 171a is connected to the second resistor connection portion 173. This second resistor connection portion 173 is not particularly limited, but is a land pattern wider than the fourth wiring portion 171a. A resistor 16 is connected to this second resistor connection portion 173, and the fourth wiring portion 171a is electrically connected to the second electrode group 14 via the resistor 16 and the third wiring pattern 17. Thereby, the second electrode group 14 is electrically connected to ground (not shown).

[0062] The fifth wiring portion 171b has a linear shape extending in the X direction in the figure, and one end of the fifth wiring portion 171b is connected to the fourth wiring portion 171a. On the other hand, the other end of the fifth wiring portion 171b is connected to the fourth electrode 14E. Therefore, the fourth electrode 1 4E is electrically connected to ground (not shown) via the third wiring pattern 17.

[0063] The resistance value output by the pressure-sensitive sensor unit 1A of the present embodiment is not particularly limited, but is the resistance value between the first external terminal portion 122 and the second external terminal portion 172. This resistance value can be obtained, for example, by a resistance measuring instrument such as a tester connected to the first external terminal portion 122 and the second external terminal portion 172.

[0064] As shown in FIGS. 1 and 2, the upper membrane substrate 20 is disposed above the lower membrane substrate 10. The upper membrane substrate 20 has a second base material 21 and a plurality (five in this example) of connectors 22A to 22E.

[0065] The second base material 21 of the upper membrane substrate 20 is a film-like member made of a material having flexibility and electrical insulation. Examples of the material constituting the second base material 21 include, for example, resin materials, and more specifically, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) can be exemplified. Note that a metal film may be used as the second base material 21, and in this case, the second base material 21 may have the functions of the connectors 22A to 22E, that is, the second base material 21 may also serve as the connectors 22A to 22E.

[0066] As shown in FIGS. 1 and 2, disk-shaped connectors 22A to 22E are formed on the lower surface of the second base material 21. The connectors 22A to 22D are members for contacting the first electrodes 13A to 13D and the second electrodes 14A to 14D and electrically connecting the first electrodes 13A to 13D and the second electrodes 14A to 14D. That is, the connector 22A contacts the first electrode 13A and the second electrode 14A and electrically connects the first electrode 13A and the second electrode 14A. The connector 22B contacts the first electrode 13B and the second electrode 14B and electrically connects the first electrode 13B and the second electrode 14B. The connector 22C contacts the first electrode 13C and the second electrode 14C and electrically connects the first electrode 13C and the second electrode 14C. The connector 22D contacts the first electrode 13D and the second electrode 14D and electrically connects the first electrode 13D and the second electrode 14D. Also, the connector 22E is also a member for contacting the third electrode 13E and the fourth electrode 14E and electrically connecting the third electrode 13E and the fourth electrode 14E.

[0067] These connectors 22A to 22E are all arranged so as to face a part of the connection wiring parts 131 and 141 and the comb teeth parts 132 and 142, and have a size that includes substantially the entire comb teeth parts 132 and 142 in a plan view.

[0068] The connectors 22A to 22E are formed by printing a low-resistance conductive paste on the lower surface of the second base material 21 and curing it, similar to the first wiring pattern 12 described above. That is, the connectors 22A to 22E are made of a material having an electrical resistivity lower than that of the materials constituting the first to fourth electrodes 13A to 13E and 14A to 14E.

[0069] Note that the connectors 22A to 22E may be provided with a protective layer that covers the above-described layer formed by printing and curing a high-resistance conductive paste. This protective layer is formed by printing and curing the above-described high-resistance conductive paste.

[0070] The spacer 30 is a film-like member made of a material having flexibility and electrical insulation, similar to the above-described first and second base materials 11 and 21. Examples of the material constituting the spacer 30 include resin materials, and more specifically, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) can be exemplified. Alternatively, a double-sided adhesive tape can also be exemplified as the spacer 30. As the double-sided adhesive tape, one having adhesive layers formed on both sides of the base material may be used, or one composed only of the adhesive layer may be used.

[0071] As shown in FIGS. 1 and 2, this spacer 30 is interposed between the first base material 11 and the second base material 21, and the lower membrane substrate 10 and the upper membrane substrate 20 are laminated via the spacer 30. Specifically, the upper surface of the base material 11 of the lower membrane substrate 10 and the lower surface of the spacer 30 are adhered to each other via an adhesive layer (not shown), and the upper surface of the spacer 30 and the lower surface of the base material 21 of the upper membrane substrate 20 are adhered to each other via an adhesive layer (not shown).

[0072] This spacer 30 has a plurality (four in this example) of first openings 31 and a second opening 32. The plurality of first openings 31 are arranged so as to surround the second opening 32 as shown in FIG. 1. In addition, when the first pressure-sensitive sensors and the second pressure-sensitive sensors are arranged alternately as described above, the first openings and the second openings are also arranged alternately.

[0073] Each of the first openings 31 has a circular planar shape. The first openings 31 house a part of the connection wiring portions 131 of the first electrodes 13A to 13D, the comb teeth portions 132 of the first electrodes 13A to 13D, a part of the connection wiring portions 141 of the second electrodes 14A to 14D, and the comb teeth portions 142 of the second electrodes 14A to 14D inside. In addition, each of the first openings 31 also houses the connectors 22A to 22D of the upper membrane substrate 20 inside. Note that the diameters of the connectors 22A to 22D may be larger than the inner diameter of the first openings 31.

[0074] When the membrane substrates 10 and 20 are stacked via the spacer 30, the comb teeth portions 132 and 142 of the first and second electrodes 13A to 13D and 14A to 14D face the connection bodies 22A to 22D through the first opening 31. Similarly, a part of the connection wiring portions 131 and 141 of the first and second electrodes 13A to 13D and 14A to 14D faces the connection bodies 22A to 22D.

[0075] The second opening 32 also has a circular planar shape and houses inside a part of the connection wiring portions 131 and 141 of the third and fourth electrodes 13E and 14E, and the comb teeth portions 132 and 142 of the third and fourth electrodes 13E and 14E. Further, the second opening 32 also houses the connection body 22E of the upper membrane substrate 20 inside. Note that the diameter of the connection body 22E may be larger than the inner diameter of the second opening 32.

[0076] When the membrane substrates 10 and 20 are stacked via the spacer 30, the comb teeth portions 132 and 142 of the third and fourth electrodes 13E and 14E face the connection body 22E through the second opening 32. Similarly, a part of the connection wiring portions 131 and 141 of the third and fourth electrodes 13E and 14E faces the connection body 22E.

[0077] As shown in FIGS. 1 and 2, the spacer 30 secures a gap between the comb teeth portions 132 and 142 of the first and second electrodes 13A to 13D and 14A to 14D and the connection bodies 22A to 22D. Also, the spacer 30 secures a gap between the comb teeth portions 132 and 142 of the third and fourth electrodes 13E and 14E and the connection body 22E.

[0078] Here, the second opening 32 of the present embodiment has the same width as the first opening 31. That is, as shown in FIG. 2, the diameter D2 of the second opening 32 is the same length as the diameter D1 of the first opening 31 (D1 = D2).

[0079] In this embodiment, the diameter D1 of the first opening 31 and the diameter D2 of the second opening 32 are the same length, but it is not limited thereto. The diameter D1 of the first opening 31 may be larger than the diameter D2 of the second opening 32 (D1>D2). In this way, since the width of the first opening 31 is larger than the width of the second opening 32, the second base material 21 is more likely to bend in the first opening 31. Therefore, the magnitude of the on-load of the first pressure-sensitive sensors 2A to 2D can be reduced, and the sensitivity of the first pressure-sensitive sensors 2A to 2D in the low-load range can be improved. Note that the "on-load" is the load required to switch the pressure-sensitive sensor from the off state to the on state.

[0080] Further, the planar shapes of the first and second openings 31 and 32 are not limited to circular shapes, and may be, for example, elliptical, oblong, rectangular, or polygonal shapes. Further, the shapes of the connectors 22A to 22E and the electrodes 13A to 13E and 14A to 14E are not particularly limited to the above, and may be, for example, shapes corresponding to the shapes of the first and second openings 31 and 32.

[0081] In this embodiment, the thickness of the spacer 30 is set so that the connectors 22A to 22E do not contact the comb teeth portions 132 and 142 when there is no load applied, but it is not particularly limited thereto. The thickness of the spacer 30 may be set so that the connectors 22A to 22E always contact the comb teeth portions 132 and 142. Similarly, the thickness of the spacer 30 may be set so that the connectors 22A to 22E always contact the connection wiring portions 131 and 141.

[0082] In this embodiment, the first pressure-sensitive sensors 2A to 2D and the second pressure-sensitive sensor 2E are all formed by the membrane substrates 10 and 20 and the spacer 30 of the pressure-sensitive sensor sheet 2, but it is not limited thereto. The first and second pressure-sensitive sensors 2A to 2E may be formed by separate membrane substrates and spacers, respectively. That is, the pressure-sensitive sensor unit may be a unitized combination of a plurality of pressure-sensitive sensor sheets.

[0083] Also, in this case, by reducing the thickness of the spacer of the pressure-sensitive sensor sheet on which the first pressure-sensitive sensor for low load use is formed, the electrodes formed on the base material become more flexible, so that the sensitivity of the sensor in the low load range can be improved. Alternatively, by reducing the thickness of the base material, the electrodes become more flexible, so that the sensitivity of the sensor in the low load range can be improved.

[0084] In the pressure-sensitive sensor sheet 2 of the present embodiment, the connectors 22A to 22D, and the first and second electrodes 13A to 13D, 14A to 14D, constitute the first pressure-sensitive sensors 2A to 2D and function as first detection units 135A to 135D for detecting the load applied to the first pressure-sensitive sensors 2A to 2D. That is, the connector 22A, the first electrode 13A, and the second electrode 14A constitute the first pressure-sensitive sensor 2A and function as the first detection unit 135A for detecting the load applied to the first pressure-sensitive sensor 2A. The connector 22B, the first electrode 13B, and the second electrode 14B constitute the first pressure-sensitive sensor 2B and function as the first detection unit 135B for detecting the load applied to the first pressure-sensitive sensor 2B. The connector 22C, the first electrode 13C, and the second electrode 14C constitute the first pressure-sensitive sensor 2C and function as the first detection unit 135C for detecting the load applied to the first pressure-sensitive sensor 2C. And the connector 22D, the first electrode 13D, and the second electrode 14D constitute the first pressure-sensitive sensor 2D and function as the first detection unit 135D for detecting the load applied to the first pressure-sensitive sensor 2D. On the other hand, the connector 22E, and the third and fourth electrodes 13E, 14E, constitute the second pressure-sensitive sensor 2E and function as the second detection unit 135E for detecting the load applied to the second pressure-sensitive sensor 2E.

[0085] Specifically, when a load is applied to the first detection units 135A to 135D of the first pressure sensors 2A to 2D, the second base material 21 bends downward at the first opening 31, and the connectors 22A to 22D come into contact with the first and second electrodes 13A to 13D, 14A to 14D. Here, the greater the magnitude of the load applied to the first detection units 135A to 135D, the greater the contact area between the connectors 22A to 22D and the first and second electrodes 13A to 13D, 14A to 14D. Therefore, the resistance value R x1 between the first and second electrodes 13A to 13D, 14A to 14D decreases. That is, in the first pressure sensors 2A to 2D, the greater the magnitude of the applied load, the smaller the output resistance value R x1 .

[0086] Similarly, when a load is applied to the second detection unit 135E of the second pressure sensor 2E, the second base material 21 bends downward at the second opening 32, and the connector 22E comes into contact with the third and fourth electrodes 13E, 14E. Also in this case, the greater the magnitude of the load applied to the second detection unit 135E, the greater the contact area between the connector 22E and the third and fourth electrodes 13E, 14E. Therefore, the resistance value R x2 between the third and fourth electrodes 13E, 14E decreases. That is, also in the second pressure sensor 2E, the greater the magnitude of the applied load, the smaller the output resistance value R x2 .

[0087] In this embodiment, since the first electrodes 13A to 13D and the third electrode 13E have the same configuration, and the second electrodes 14A to 14D and the fourth electrode 14E have the same configuration, the on-state resistance value R x1 of the first pressure sensors 2A to 2D is substantially the same as the on-state resistance value R x2 of the second pressure sensor 2E (R x1 =R x2 ).

[0088] In addition, in the present embodiment, the first pressure-sensitive sensors 2A to 2D are electrically connected in parallel to each other between the first wiring pattern 12 and the second wiring pattern 15. And the first pressure-sensitive sensor 2E is electrically connected in parallel to the first pressure-sensitive sensors 2A to 2D between the first wiring pattern 12 and the second wiring pattern 15.

[0089] On the upper surface of the second base material 21 of the pressure-sensitive sensor sheet 2, a plurality (four in this example) of first load transmission members 3A to 3D and a second load transmission member 4 are provided. The first load transmission members 3A to 3D are members (actuators) that transmit load to the first pressure-sensitive sensors 2A to 2D. On the other hand, the second load transmission member 4 is a member (actuator) that transmits load to the second pressure-sensitive sensor 2E.

[0090] The first load transmission members 3A to 3D and the second load transmission member 4 in the present embodiment have a circular planar shape and are composed of members having elasticity. That is, the first load transmission members 3A to 3D and the second load transmission member 4 contract when a load is applied, but return to the initial shape before the load is applied when the load is removed. Note that the planar shape of the first load transmission members 3A to 3D and the second load transmission member 4 is not limited to a circular shape. The planar shape is not limited to a circular shape, and may be, for example, an elliptical shape, an oblong shape, a rectangular shape, or a polygonal shape. Also, the first load transmission members 3A to 3D and the second load transmission member 4 may be composed of a rigid body.

[0091] Specific examples of the member having such elasticity include, for example, a resin member, a rubber member, and a spring member. Among these, in particular, it is preferable to use a sponge-like resin member containing fine bubbles.

[0092] As shown in FIG. 2, the first load transmission members 3A to 3D are interposed between the first detection portions 135A to 135D of the first pressure sensors 2A to 2D and the plate member 5. Specifically, the lower surfaces of the first load transmission members 3A to 3D are attached to the upper surface of the second base material 21 of the upper membrane substrate 20 via an adhesive layer (not shown), and the upper surfaces of the first load transmission members 3A to 3D are attached to the lower surface of the plate member 5 via an adhesive layer (not shown). That is, both the upper and lower surfaces of the first load transmission members 3A to 3D are fixed to the second base material 21 and the plate member 5.

[0093] Note that the first load transmission members 3A to 3D are joined to the second base material 21 and the plate member 5 via an adhesive layer, but are not limited thereto. For example, the first load transmission members 3A to 3D may be joined by being applied and formed on the second base material 21 or the plate member 5.

[0094] The second load transmission member 4 is interposed between the second detection portion 135E of the second pressure sensor 2E and the plate member 5. The lower surface of this second load transmission member 4 is attached to the upper surface of the second base material 21 of the upper membrane substrate 20 via an adhesive layer (not shown), but the upper surface of the second load transmission member 4 is separated from the plate member 5. That is, only the lower surface of the second load transmission member 4 is fixed to the second base material 21.

[0095] Note that the second load transmission member 4 is joined to the second base material 21 via an adhesive layer, but is not limited thereto. For example, the second load transmission member 4 may be joined by being applied and formed on the second base material 21. Also, although the lower surface of the second load transmission member 4 is fixed to the second base material 21, it is not limited thereto. The upper surface of the second load transmission member 4 may be joined to the plate member 5 and the lower surface of the second load transmission member 4 may be separated from the second base material 21.

[0096] The height T1 of the first load transmission members 3A to 3D is higher than the height T2 of the second load transmission member 4 (T1 > T2). By providing a difference between the height T1 of the first load transmission members 3A to 3D and the height T2 of the second load transmission member 4 in this way, a load can be transmitted to the first pressure sensors 2A to 2D before the second pressure sensor 2E. That is, when a low load is applied to the pressure sensor unit 1A, the load is transmitted to the first pressure sensors 2A to 2D by the first load transmission members 3A to 3D, but the load is not transmitted to the second pressure sensor 2E by the second load transmission member 4. On the other hand, when a high load is applied to the pressure sensor unit 1A, the load is also transmitted to the second pressure sensor 2E by the second load transmission member 4.

[0097] The plate member 5 is stacked on the pressure sensor sheet 2 via the first and second load transmission members 3A to 3D, and is arranged so as to include the first and second pressure sensors 2A to 2E in plan view. This plate member 5 is a plate-like member made of a material having a predetermined rigidity. By making the plate member 5 a member that is difficult to bend, a uniform pressing force can be generated on the lower surface of this plate member 5. Examples of the material constituting the plate member 5 include, for example, ABS (acrylonitrile butadiene styrene) resin, glass, or polycarbonate resin.

[0098] The load transmission by the first load transmission members 3A to 3D and the second load transmission member 4 will be specifically described with reference to FIGS. 3(a) and 3(b). FIG. 3(a) is a cross-sectional view showing a state in which a low load is applied to the pressure sensor unit 1A in FIG. 2, and FIG. 3(b) is a cross-sectional view showing a state in which a high load is applied to the pressure sensor unit 1A in FIG. 2.

[0099] As shown in Fig. 3(a), when a low load F1 is applied to the pressure sensor unit 1A from the plate member 5 side, the load is transmitted from the plate member 5 to the first load transmission members 3A to 3D joined to the lower surface of the plate member 5. That is, the first load transmission members 3A to 3D are pressed by the lower surface of the plate member 5 in the -Z direction in the figure.

[0100] Then, the second base material 21 is bent downward at the first opening 31 by the load transmitted from the first load transmission members 3A to 3D. That is, the first load transmission members 3A to 3D concentrate the load on the first pressure sensors 2A to 2D. As a result, at the first opening 31 of the spacer 30, the connectors 22A to 22D formed on the lower surface of the second base material 21 are pushed downward and electrically connected to the first and second electrode groups 13, 14 of the first pressure sensors 2A to 2D.

[0101] On the other hand, since the shrinkage amount of the first load transmission members 3A to 3D is small, the second load transmission member 4 is separated from the plate member 5 and no load is transmitted from the plate member 5. Therefore, the second load transmission member 4 does not press the second base material 21, and the connector 22E is not pushed downward either. That is, the third electrode 13E and the fourth electrode 14E of the first pressure sensor 2E are maintained in a mutually insulated state (off state).

[0102] As shown in Fig. 3(b), when a high load F2 is applied to the pressure sensor unit 1A from the plate member 5 side, the plate member 5 is further pushed downward and the first load transmission members 3A to 3D contract greatly. For this reason, the lower surface of the plate member 5 comes into contact with the second load transmission member 4. That is, in addition to the first load transmission members 3A to 3D, the second load transmission member 4 is also pressed by the lower surface of the plate member 5 in the -Z direction in the figure.

[0103] The second base material 21 bends downward due to the load transmitted from the second load transmission member 4 at the second opening 32. As a result, at the second opening 32 of the spacer 30, the connector 22E is pushed downward and electrically connected to the third and fourth electrodes 13E, 14E of the second pressure sensor 2E.

[0104] As described above, in the pressure sensor unit 1A of the present embodiment, when a low load is applied, only the first pressure sensors 2A to 2D are in the on state, while when a high load is applied, in addition to the first pressure sensors 2A to 2D, the second pressure sensor 2E is also in the on state.

[0105] Also, as shown in FIGS. 1 and 2, the first load transmission members 3A to 3D are respectively arranged on the upper surface of the second base material 21 、Article so as to surround the second load transmission member 4. That is, since the first pressure sensors 2A to 2D of the present embodiment are arranged around the second pressure sensor 2E, the first load transmission members 3A to 3D are also arranged around the second load transmission member 4. Thereby, when a load is applied to the pressure sensor unit 1A, while stably supporting the plate member 5 by the plurality of first load transmission members 3A to 3D arranged around the second load transmission member 4, the load can be uniformly transmitted from the lower surface of the plate member 5, so that the load can be accurately detected.

[0106] Regarding the change in the resistance value output from the pressure sensor unit 1A as described above, in addition to FIGS. 1, 2, 3(a), and 3(b), it will be described with reference to FIG. 4. FIG. 4 is a graph showing the relationship between the magnitude F of the load applied to the pressure sensor unit 1A in the present embodiment and the resistance value R output from the pressure sensor unit 1A. In the graph of FIG. 4, the solid line indicates the combined resistance R0 of the resistance value R of the first pressure sensors 2A to 2D x1 and the resistance value R1 of the resistor 16, and the broken line indicates the resistance value R of the second pressure sensor 2E x2is shown. Also, the dashed-dotted line indicates the resistance value R output from the pressure-sensitive sensor unit 1A. In the present embodiment, this resistance value R is the resistance value between the first external terminal portion 122 and the second external terminal portion 172.

[0107] First, as shown in FIG. 2, when there is no load, the electrodes 13A to 13E and 14A to 14E of all the pressure-sensitive sensors 2A to 2E are electrically insulated from each other, and all the pressure-sensitive sensors 2A to 2E are in the off state. In this case, as shown in FIG. 4, as the resistance value R, a resistance value R of several hundred MΩ d is output from the pressure-sensitive sensor unit 1A.

[0108] Next, as shown in FIG. 3(a), when a load F1 equal to or greater than a certain value is applied to the pressure-sensitive sensor unit 1A, the first pressure-sensitive sensors 2A to 2D are switched to the on state. In other words, when the load is less than or equal to a certain value F1, the resistance values between the connectors 22A to 22D and the first and second electrodes 13A to 13D and 14A to 14D exceed the threshold value, and the first pressure-sensitive sensors 2A to 2D are maintained in the off state. Also, the second pressure-sensitive sensor 2E is maintained in the off state in the low-load region.

[0109] At this time, as shown in FIG. 1, the first pressure-sensitive sensors 2A to 2D are electrically connected in parallel to each other, and a resistor 16 is electrically connected in series to the second electrode group 14 of the first pressure-sensitive sensors 2A to 2D. Therefore, the resistance value R output from the pressure-sensitive sensor unit 1A is the combined resistance R0 of the resistance value R x1 of the first pressure-sensitive sensors 2A to 2D and the resistance value R1 of the resistor 16.

[0110] In this case, as shown in FIG. 4, as the load increases in the low-load region, the resistance value R x1 of the first pressure-sensitive sensors 2A to 2D decreases, and finally, the resistance value R x1 reaches the minimum resistance value (breakdown resistance) R min and saturates. For this reason, as shown by the solid line in the graph of FIG. 4, the combined resistance R0 also decreases as the load increases, and finally, the resistance value R minSaturates in the vicinity of +R1.

[0111] Next, as shown in Fig. 3(b), when a high load F2 is applied to the pressure-sensitive sensor unit 1A, the second pressure-sensitive sensor 2E also switches to the on state. As shown by the broken line in the graph of Fig. 4, as the magnitude of the load increases in the high load region, the resistance value R of the second pressure-sensitive sensor 2E x2 decreases. No resistor is connected to this second pressure-sensitive sensor 2E, and the resistance value R1 of the above-described resistor 16 is greater than the resistance value R x2 so when the magnitude of the high load becomes greater than a certain value, the resistance value R x2 is lower than the value of the above-described combined resistor R0.

[0112] When the resistance value R x2 is lower than the value of the above-described combined resistor R0, the current flowing through the second pressure-sensitive sensor 2E becomes more dominant than the current flowing through the first pressure-sensitive sensors 2A to 2D. Therefore, the resistance value R output from the pressure-sensitive sensor unit 1A becomes the resistance value R of the second pressure-sensitive sensor 2E x2 . Thus, in this embodiment, by electrically connecting the resistor 16 in series to the second electrode group 14, it is possible to distinguish the range of the resistance value output in the low load region and the range of the resistance value output in the high load region and avoid duplication.

[0113] Then, as the magnitude of the load further increases, the resistance value R of the second pressure-sensitive sensor 2E x2 saturates in the vicinity of the cut-off resistance value R min , so the resistance value R output from the pressure-sensitive sensor unit 1A also saturates in the vicinity of the cut-off resistance value R min . Therefore, the resistance value R of the pressure-sensitive sensor unit 1A has an output as shown by the dashed-dotted line in Fig. 4.

[0114] In the case of the pressure-sensitive sensor unit 1A as described above, it includes first load transmission members 3A to 3D that transmit a low load to the first pressure-sensitive sensors 2A to 2D, and a second load transmission member 4 that transmits a high load to the second pressure-sensitive sensor 2E. Therefore, since the pressure-sensitive sensor unit 1A can obtain an output (resistance value R) in both the low load range and the high load range, the detectable load range can be widened.

[0115] In addition, in the above embodiment, the first load transmission members 3A to 3D, the second load transmission member 4, and the plate member 5 are arranged on the second base material 21 side of the upper membrane substrate 20, but it is not limited to this.

[0116] FIG. 5 is a cross-sectional view showing a first modification of the pressure-sensitive sensor unit in the present embodiment. Like the pressure-sensitive sensor unit 1B of this first modification, the first load transmission members 3A to 3D, the second load transmission member 4, and the plate member 5 may be arranged on the first base material 11 side of the lower membrane substrate 10.

[0117] In this case, when a low load is applied from the second base material 21 side, the load is transmitted to the first pressure-sensitive sensors 2A to 2B by the first load transmission members 3A to 3D in the same manner as in the above embodiment. And when a high load is applied from the second base material 21 side, the second load transmission member 4 comes into contact with the plate member 5 as the first load transmission members 3A to 3D contract, and the load is transmitted to the first pressure-sensitive sensors 2A to 2B. In this case, it is preferable that the second base material 21 is difficult to bend. Specifically, two or more second base materials 21 may be laminated on the spacer 30, or the thickness of the second base material 21 may be increased. Further, as the first base material 11 that receives the load from the first and second load transmission members 3A to 3D, 4, a flexible one is used.

[0118] In addition, in the above embodiment, the height T1 of the first load transmission members 3A to 3D is made higher than the height T2 of the second load transmission member 4 so that it is difficult for a load to be applied to the second pressure-sensitive sensor 2E in the low load range, but it is not limited to this.

[0119] FIG. 6 is a cross-sectional view showing a second modification of the pressure-sensitive sensor unit according to the present embodiment. As in the pressure-sensitive sensor unit 1C of this second modification, the second load transmission member 4b may be made softer than the first load transmission members 3A to 3D so that it is difficult for a load to be applied to the second pressure-sensitive sensor 2E in the low load range. As the material constituting such a second load transmission member 4b, among the sponge-like resin members, rubber members, or spring members as described above, a member having a low Young's modulus may be used.

[0120] Also, in this case, the height T1 of the first load transmission members 3A to 3D and the height T2 of the second load transmission member 4b are the same height (T1 = T2). Since the first load transmission members 3A to 3D are harder than the second load transmission member 4b, it is easier to transmit a load than the second load transmission member 4b in the low load range. Therefore, also in this second modification, as in the above-described embodiment, it is difficult for a load to be applied to the second pressure-sensitive sensor 2E in the low load range.

[0121] Also, in the above-described embodiment, as the first and second electrodes 13A to 13E and 14A to 14E of the first pressure-sensitive sensors 2A to 2E, comb-shaped electrodes that penetrate each other are used, but the shape of the electrodes is not limited to this. The shape of the electrodes may be the shape shown in the following third modification.

[0122] FIG. 7(a) is an enlarged plan view showing a pressure-sensitive sensor in a third modification of the pressure-sensitive sensor unit according to an embodiment of the present invention, FIG. 7(b) is an enlarged plan view showing a lower membrane of the pressure-sensitive sensor of FIG. 7(a), and FIG. 7(c) is an enlarged plan view showing an upper membrane of the pressure-sensitive sensor of FIG. 7(a).

[0123] As shown in FIGS. 7(a) and 7(b), the first pressure-sensitive sensor 2d of the pressure-sensitive sensor unit 1D in the third modification is a pressure-sensitive sensor in which the resistance value between the wiring patterns 62 and 66 changes according to the applied load. The first electrode 13d of this third modification has wiring patterns 62 and 63, a resistor 64, and comb patterns 65A to 65F.

[0124] As shown in FIG. 7(b), the wiring patterns 62 and 63 are formed by printing a low-resistance conductive paste as described above on the upper surface of the first base material 11 of the lower-side membrane substrate 10d and solidifying (curing) it. Note that instead of the conductive paste, the wiring patterns 62 and 63 may be formed by etching a metal foil.

[0125] As shown in FIG. 7(b), the wiring pattern 62 extends linearly along the X direction in the figure. The end portion 621 of this wiring pattern 62 is covered by the resistor 64, and a comb-tooth pattern 65A is connected to the end portion 621. Similarly, the wiring pattern 63 also extends linearly along the X direction in the figure. The end portion 631 of this wiring pattern 63 is covered by the resistor 64, and a comb-tooth pattern 65F is connected to the end portion 631. Although not particularly shown, one of the wiring patterns 62 is connected to a power source, while the other wiring pattern 63 is connected to a ground. Note that the planar shape of the wiring patterns 62 and 63 is not limited to the above linear shape as long as it is linear.

[0126] The end portion 621 of the wiring pattern 62 and the end portion 631 of the wiring pattern 63 are arranged apart from each other along the Y direction in the figure. The resistor 64 is provided along the Y direction in the figure. One end portion 641 of the resistor 64 covers the end portion 621 of the wiring pattern 62, and the other end portion 642 of the resistor 64 covers the end portion 631 of the wiring pattern 63. Therefore, one of the wiring patterns 62 and the other wiring pattern 63 are electrically connected via this resistor 64. This resistor 64 is formed by printing a high-resistance conductive paste on the upper surface of the base material 11 and curing it.

[0127] The plurality (six in this example) of comb-tooth patterns 65A to 65F are formed by printing a low-resistance conductive paste on the first base material 11 and curing it in the same manner as the above-described wiring patterns 62 and 63. Note that instead of the conductive paste, the comb-tooth patterns 65A to 65F may be formed by etching a metal foil.

[0128] The comb tooth patterns 65A to 65F are arranged substantially parallel to each other with a space therebetween in the facing region 611 of the first base material 11 facing the connector 22A. The comb tooth patterns 65A to 65F are arranged with a space therebetween from the inside to the outside in the facing region 611. Further, the comb tooth patterns 65A to 65F are arranged concentrically with respect to the center CP of the tip portion 661 of the wiring pattern 66 in the facing region 611.

[0129] The second electrode 14d of the third modification is the wiring pattern 66. This wiring pattern 66 is also formed by printing a low-resistance conductive paste on the upper surface of the base material 11 and curing it, similarly to the above-described wiring patterns 62 and 63. Note that instead of the conductive paste, the wiring pattern 66 may be formed by etching a metal foil.

[0130] As shown in FIG. 7(c), the configuration of the connector formed on the lower surface of the second base material 21 of the upper membrane substrate 20d 22A is the same as the configuration of the above-described embodiment.

[0131] In this first pressure sensor 2d, when a load is applied, first, the connector 22A contacts the center CP of the tip portion 661 of the wiring pattern 66 shown in FIG. 7(b). Then, as the deflection in the first opening 31 of the second base material 21 increases, the connector 22A contacts the comb tooth pattern 65F.

[0132] When the connector 22A is in contact with the wiring pattern 66 and the comb tooth pattern 65F, the wiring pattern 66 detects a voltage that is substantially the same potential as the ground, and a potential difference between the power supply voltage and the detected voltage of the wiring pattern 66 is output by a multimeter (not shown) or the like connected to the wiring patterns 62 and 66.

[0133] Then, as the applied load increases, the deflection of the second base material 21 spreads, and the connection target of the connector 22A spreads to the more outer comb tooth patterns 65E to 65A. As a result, the distance between one end 641 of the resistor 64 and the connection position of the connection target becomes shorter, and thus the resistance value between the wiring patterns 62 and 66 decreases. That is, in the first pressure-sensitive sensor 2d of the third modification, since the resistance length (resistance value) of the resistor 64 changes according to the magnitude of the applied load, the voltage detected by the wiring pattern 66 changes according to the magnitude of the load.

[0134] In the third modification, an example in which the first pressure-sensitive sensor 2d has the configuration shown in FIG. 7(a) has been described, but the present invention is not limited thereto, and the second pressure-sensitive sensor may also have the configuration shown in FIG. 7(a).

[0135] Also, although not particularly shown, the power supply and the ground may be connected to the wiring patterns 62 and 66 without providing the wiring pattern 63. Alternatively, instead of the wiring pattern 63, the wiring pattern 66 may cover the other end 642 of the resistor 64. Also in these cases, the resistance value between the wiring patterns 62 and 66 changes according to the magnitude of the load.

[0136] In the above-described embodiment, the first to fourth electrodes are all formed on the same base material, and the case where the first to fourth electrodes are electrically connected by a connector has been described, but the present invention is not limited thereto. As shown in the following fourth modification, the electrodes may be electrically connected by directly contacting the electrodes with each other.

[0137] FIG. 8(a) is an enlarged cross-sectional view showing a pressure-sensitive sensor in a fourth modification of the pressure-sensitive sensor unit in the present embodiment, FIG. 8(b) is an enlarged plan view showing the lower membrane of the pressure-sensitive sensor in FIG. 8(a), and FIG. 8(c) is an enlarged plan view showing the upper membrane of the pressure-sensitive sensor in FIG. 8(a).

[0138] As shown in FIGS. 8(a) to 8(c), the first pressure-sensitive sensor 2e of the pressure-sensitive sensor unit 1E in the fourth modification example has a disk-shaped first electrode 13e formed on the upper surface of the first base material 11 of the lower membrane substrate 10e, and a disk-shaped second electrode 14e formed on the lower surface of the second base material 21 of the upper membrane substrate 20e.

[0139] The first electrode 13e and the second electrode 14e face each other in the first opening 31 of the spacer 30. The first and second electrodes 13e, 14e can be formed, for example, by printing and curing a pressure-sensitive ink. Examples of this pressure-sensitive ink include, for example, a quantum tunneling composite material that utilizes the quantum tunneling effect. Further, as other specific examples of the pressure-sensitive ink, for example, those containing conductive particles such as metals and carbon, elastic particles such as organic elastic fillers or inorganic oxide fillers, and a binder can be exemplified. The surface of this pressure-sensitive ink is uneven due to the elastic particles. Note that the first and second electrodes 13e, 14e may be formed by plating or patterning processes.

[0140] When a load is applied to this first pressure-sensitive sensor 2e, the second base material 21 bends downward in the first opening 31, so that the first electrode 13e and the second electrode 14e come into contact with each other and are electrically connected.

[0141] In the fourth modification example, an example in which the first pressure-sensitive sensor 2e has the configuration shown in FIG. 8(a) has been described, but the present invention is not limited to this, and the second pressure-sensitive sensor may also have the configuration shown in FIG. 8(a).

[0142] Note that the embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

Description of Reference Numerals

[0143] 1A~1E... Pressure-sensitive sensor unit 2… Pressure-sensitive sensor sheet 2A~2D, 2d, 2e… First pressure-sensitive sensor 2E… Second pressure-sensitive sensor 10, 10d, 10e… Lower membrane substrate 11… Base material 12… First wiring pattern 121a, 121b… First and second wiring portions 122… First external terminal portion 13… First electrode group 13A~13D, 13d, 13e… First electrode 14… Second electrode group 14A~14D, 14d, 14e… Second electrode 13E… Third electrode 14E… Fourth electrode 131, 141… Connection wiring portion 132, 142… Comb teeth portion 135A~135D… First detection portion 135E… Second detection portion 15… Second wiring pattern 151… Third wiring portion 153… First resistor connection portion 16… Resistor 17… Third wiring pattern 171a, 171b… Fourth and fifth wiring portions 172… Second external terminal portion 173… Second resistor connection portion 62… Wiring pattern 621… End portion 63… Wiring pattern 631… End portion 64… Resistor 641, 642… End portions 65A~65F… Comb tooth pattern 655… Detection portion 66… Wiring pattern 661… Tip portion 20, 20e… Upper membrane substrate 21… Base material 22A~22E… Connector 30… Spacer 31… First opening 32…Second opening 3A to 3D…First load transmission member 4, 4b…Second load transmission member 5…Plate member

Claims

1. A pressure-sensitive sensor unit, comprising: a first pressure-sensitive sensor whose output changes according to the magnitude of an applied load; a second pressure-sensitive sensor whose output changes according to the magnitude of an applied load; a plate member arranged to include the first and second pressure-sensitive sensors in plan view; a first load transmission member interposed between the first pressure-sensitive sensor and the plate member; a second load transmission member interposed between the second pressure-sensitive sensor and the plate member, wherein the first load transmission member transmits a load belonging to a first load range to the first pressure-sensitive sensor, the second load transmission member transmits a load belonging to a second load range larger than the first load range to the second pressure-sensitive sensor, the first pressure-sensitive sensor includes first and second electrodes that are electrically connected to each other by the application of a load, the second pressure-sensitive sensor includes third and fourth electrodes that are electrically connected to each other by the application of a load, the pressure-sensitive sensor unit includes a resistor electrically connected in series to the first or second electrode of the first pressure-sensitive sensor, the pressure-sensitive sensor unit includes a first base material, and a second base material facing the first base material, wherein the first electrode is provided on the first base material, the second electrode is provided on the first base material so as to face a first connector provided on the second base material so as to face the first electrode, or is provided on the second base material so as to face the first electrode, the pressure-sensitive sensor unit includes a spacer interposed between the first base material and the second base material, the spacer has a first opening that houses the first and second electrodes of the first pressure-sensitive sensor, and a second opening that houses the third and fourth electrodes of the second pressure-sensitive sensor, and a width of the first opening is larger than a width of the second opening.

2. The pressure-sensitive sensor unit according to claim 1, wherein a height of the first load transmission member is higher than a height of the second load transmission member, or the second load transmission member is softer than the first load transmission member.

3. The pressure-sensitive sensor unit according to claim 1, wherein a resistance value of the resistor is larger than a resistance value in an on state of the second pressure-sensitive sensor.

4. The pressure-sensitive sensor unit according to claim 1, The pressure-sensitive sensor unit includes a plurality of the first pressure-sensitive sensors. The pressure-sensitive sensor unit includes a first electrode group composed of a plurality of the first electrodes electrically connected to each other, and a second electrode group composed of a plurality of the second electrodes electrically connected to each other. The resistor is a pressure-sensitive sensor unit electrically connected in series to the first or second electrode group.

5. The pressure-sensitive sensor unit according to claim 1, wherein the pressure-sensitive sensor unit includes a first base material, and a second base material facing the first base material. The third electrode is provided on the first base material. The fourth electrode is provided on the first base material so as to face a second connector provided on the second base material so as to face the third electrode, or is provided on the second base material so as to face the third electrode.

6. The pressure-sensitive sensor unit according to claim 1, wherein the height of the first load transmission member is higher than the height of the second load transmission member, the first load transmission member is joined to at least one of the first or second base materials and is also joined to the plate member, and the second load transmission member is joined to only one of the first base material, the second base material, or the plate member.

7. The pressure-sensitive sensor unit according to any one of claims 1 to 6, wherein the pressure-sensitive sensor unit includes a plurality of the first pressure-sensitive sensors, and a plurality of the first load transmission members. The plurality of the first pressure-sensitive sensors are arranged around the second pressure-sensitive sensor. The plurality of the first load transmission members are arranged around the second load transmission member.

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