JP2023152490A - Flexible touch sensor and touch sensor module - Google Patents

Abstract

To provide a flexible touch sensor having a probe point for inspecting electric characteristics while protecting a detection electrode sufficiently, and configured to suppress noise or false detection through the probe point, and a touch sensor module.SOLUTION: A flexible touch sensor 1 is equipped with a substrate sheet 10 made of resin, a detection electrode 20 arranged on a first surface 10a in a thickness direction of the substrate sheet 10, and circuit wiring 30 arranged on the first surface 10a of the substrate sheet 10 and electrically connected to the detection electrode 20, to detect a conductor which is in contact or close thereto. The flexible touch sensor includes a carbon layer 40 arranged on a surface of the detection electrode 20 opposite the substrate sheet 10, and covers, with an insulating protective layer 50, a portion of the substrate sheet 10 other than a part where the carbon layer 40 is arranged on the side where the detection electrode 20 is arranged.SELECTED DRAWING: Figure 2

Description

The present invention relates to a flexible touch sensor and a touch sensor module.

2. Description of the Related Art Capacitive touch sensors are widely used in in-vehicle electronic devices and the like to detect operations on operation surfaces. For example, a capacitive touch sensor made of a flexible printed circuit board is bonded to the circuit board side (back side) of a decorated operation panel, so that when a user touches the operation panel, the capacitance increases. Can be detected by change.

In a touch sensor, since a protective layer is generally provided on the detection electrode, it is not possible to test the electrical characteristics by directly contacting the sensor with a probe.
Patent Document 1 discloses, as a method for inspecting electrical characteristics, that a microcontroller (IC) for a capacitance sensor is used to calculate changes in capacitance.
Patent Document 2 discloses that an opening is provided in a part of a protective layer covering a detection electrode to serve as a probe point so that a probe can come into contact with the detection electrode.

Furthermore, in touch sensors, transparent conductive materials are sometimes used for detection electrodes. In that case, the probe point is provided near the detection electrode or at the outer edge so as not to impede light transmission. Patent Document 3 discloses that a carbon material or the like is used to provide a probe point adjacent to a detection electrode on the surface of a base sheet.

Japanese Patent Application Publication No. 2015-141685 Japanese Patent Application Publication No. 2012-174494 JP2021-036465A

However, the method using an IC such as that disclosed in Patent Document 1 requires time for inspection and also increases equipment cost. If an opening is provided in a part of the protective layer covering the detection electrode as in Patent Document 2, it becomes difficult to sufficiently protect the detection electrode. When a probe point is provided adjacent to a detection electrode as in Patent Document 3, noise due to parasitic capacitance is likely to occur, and false detection is likely to occur.

In view of the above circumstances, the present invention provides a flexible touch sensor and a touch sensor that can sufficiently protect detection electrodes, have a probe point for testing electrical characteristics, and suppress noise and false detection caused by the probe point. The purpose is to provide modules.

The present invention includes the following aspects.
[1] A base sheet made of resin, a detection electrode provided on one side of the base sheet in the thickness direction, and a detection electrode provided on the one side of the base sheet and electrically connected to the detection electrode. A flexible touch sensor that detects contact or proximity of a conductor to the detection electrode based on a change in capacitance of the detection electrode due to the contact or proximity of the conductor to the detection electrode. And,
A carbon layer provided on at least a part of the surface of the detection electrode opposite to the base sheet, and a carbon layer having a volume resistivity of 1 Ω·cm or less and a sheet resistance of 1000 Ω/□ or less, further comprising at least one carbon layer that also serves as
A flexible touch sensor, wherein a portion of the base sheet on the side where the detection electrode is provided other than the portion where the carbon layer is provided is covered with an insulating protective layer.
[2] The flexible touch sensor according to [1], wherein a carbon layer is provided on the entire surface of the detection electrode opposite to the base sheet.
[3] The detection electrode according to [1], when viewed from the thickness direction of the base sheet, has a mesh shape including an annular portion and a partition portion that partitions the inside of the annular portion into a plurality of regions. flexible touch sensor.
[4] The detection electrode according to [2], when viewed from the thickness direction of the base sheet, has a mesh shape including an annular portion and a partition portion that partitions the inside of the annular portion into a plurality of regions. flexible touch sensor.
[5] A touch sensor module comprising the flexible touch sensor according to any one of [1] to [4].

According to the present invention, there is provided a flexible touch sensor and a touch sensor module that can sufficiently protect a detection electrode, have a probe point for testing electrical characteristics, and can suppress noise and false detection caused by the probe point. Can be done.

It is a front view of a flexible touch sensor of an example of an embodiment seen from a base material sheet side. 2 is a sectional view taken along line AA of the flexible touch sensor in FIG. 1. FIG. FIG. 2 is a front view showing detection electrodes of the flexible touch sensor of FIG. 1. FIG. FIG. 7 is a front view showing another example of the detection electrode. FIG. 7 is a front view showing another example of the detection electrode. 2 is a cross-sectional view showing one step in manufacturing the flexible touch sensor of FIG. 1. FIG. 2 is a cross-sectional view showing one step in manufacturing the flexible touch sensor of FIG. 1. FIG. FIG. 7 is a cross-sectional view showing a flexible touch sensor according to another example of the embodiment. FIG. 2 is a cross-sectional view showing a touch sensor module according to an example of an embodiment.

[Flexible touch sensor]
Hereinafter, an example of the flexible touch sensor of the present invention will be described based on the drawings. Note that the dimensions of the figures illustrated in the following description are merely examples, and the present invention is not necessarily limited thereto, and can be practiced with appropriate changes within the scope of the gist thereof. .

As shown in FIGS. 1 and 2, the flexible touch sensor 1 of the embodiment is a capacitive touch sensor for detecting operations on an operation surface, and includes a base sheet 10 and three detection electrodes 20. , a circuit wiring 30 , a carbon layer 40 , and an insulating protective layer 50 .

Three detection electrodes 20 are provided on the first surface 10a in the thickness direction of the base sheet 10, and a carbon layer 40 is provided on the surface of each detection electrode 20 on the opposite side to the base sheet 10. Furthermore, circuit wiring 30 electrically connected to the detection electrode 20 is provided on the first surface 10a of the base sheet 10. An insulating protective layer 50 is provided on the side of the base sheet 10 on which the detection electrode 20, the circuit wiring 30, and the carbon layer 40 are provided so as to cover the portion other than the portion where the carbon layer 40 is provided.

The base sheet 10 is a resin sheet and has flexibility.
In the example shown in FIG. 1, the base sheet 10 includes a main body 11 that is rectangular in plan view, and a band-shaped portion 12 that extends so as to protrude from a part of one short side of the main body 11. ing.
Note that the shape of the base sheet 10 in plan view is not limited to the shape of this example, and can be set as appropriate depending on the application.

As the base sheet 10, a transparent resin insulating film can be used. However, "insulation" means that the electrical resistance value is 1 MΩ or more, preferably 10 MΩ or more. Moreover, "transparent" means that the light transmittance measured according to JIS K7136 is 50% or more.

Examples of the material constituting the base sheet 10 include polyester (such as polyethylene terephthalate (PET)), polycarbonate (PC), acrylic resin, cyclic polyolefin resin, and triacetyl cellulose. The number of materials constituting the base sheet 10 may be one, or two or more.

In terms of easily ensuring sufficient strength and rigidity, the average thickness of the base sheet 10 is preferably 10 μm or more, more preferably 25 μm or more. In terms of easily reducing the thickness of the flexible touch sensor 1, the average thickness of the base sheet 10 is preferably 250 μm or less, more preferably 188 μm or less. The lower limit and upper limit of the average thickness of the base sheet 10 can be arbitrarily combined, for example, preferably 10 to 250 μm, more preferably 25 to 188 μm.
The average thickness of the base sheet means the average value of thicknesses measured at ten arbitrary locations on the base sheet.

The detection electrode 20 is an electrode for detecting contact or proximity of a conductor. The detection electrode 20 may be of a self-capacitance type or a mutual capacitance type.
As shown in FIG. 3, the detection electrode 20 of this example includes a circular annular portion 21 and a linear three-dimensional portion that partitions the inside of the annular portion 21 into a plurality of regions when viewed from the thickness direction of the base sheet 10. It has a mesh shape with book partitions 22. All three partitions 22 pass through the center of the annular part 21 and partition the inside of the annular part 21 into six equal fan-shaped areas.

When the detection electrode 20 has a mesh shape, even if the carbon layer 40 is provided on the entire surface of the detection electrode 20, light can pass through an area not blocked by the partition part 22 inside the annular part 21. Therefore, with the flexible touch sensor 1 attached to the back surface of the operation panel, the portion of the operation panel where the detection electrode 20 is located can be illuminated from the side of the detection electrode 20 opposite to the operation panel.

Note that the shape of the detection electrode 20 is not particularly limited as long as it can ensure sufficient detection sensitivity and detection accuracy for operations on the operation surface. For example, as shown in FIG. 4, a detection electrode 20A may be provided in which a plurality of linear partitions 22 are provided in a grid pattern inside an annular portion 21. Alternatively, as shown in FIG. 5, the detection electrode 20B may be provided with a plurality of linear partitions 22 parallel to each other inside the annular portion 21. The annular portion 21 is not limited to an annular shape, but may have an annular shape such as a rectangle or a hexagon.
Further, the detection electrode 20 may be a transparent solid electrode having a circular, oval, or rectangular shape. In this case, by providing the carbon layer 40 only on a portion of the surface of the detection electrode 20, the operation panel can be illuminated through the portion where the carbon layer 40 is not provided.

The detection electrode 20 can be formed by printing conductive ink, and can be exemplified by a transparent conductive film. "Conductive" means that the electrical resistance value is less than 1 MΩ.
Examples of the conductive substance contained in the conductive ink include conductive polymers (polythiophene-based conductive polymer (PEDOT/PSS), indium-doped tin oxide (ITO), etc.), conductive nanowires (silver nanowires, gold nanowires, etc.), and conductive nanowires (silver nanowires, gold nanowires, etc.). etc.), metal particles (silver particles, copper particles, gold particles, etc.), and conductive metal oxide particles (ITO particles, etc.). Among them, silver ink is preferred. The number of conductive substances contained in the conductive ink may be one, or two or more.

In terms of easily suppressing disconnection, the average thickness of the detection electrode 20 is preferably 0.05 μm or more, more preferably 0.1 μm or more. In terms of easily reducing the thickness of the flexible touch sensor 1, the average thickness of the detection electrodes 20 is preferably 30 μm or less, more preferably 20 μm or less. The lower limit and upper limit of the average thickness of the detection electrode 20 can be arbitrarily combined, for example, preferably 0.05 to 30 μm, more preferably 0.1 to 20 μm.
Note that the average thickness of the detection electrode is the average value of the thicknesses measured at ten arbitrary locations on the detection electrode.

The number of detection electrodes 20 is not limited to three, and can be set as appropriate, and may be two or less, or four or more.
In the example shown in FIG. 1, the three detection electrodes 20 are electrically connected to the connection terminals 14 provided at the distal end portions of the band-shaped portions 12 of the base sheet 10 through circuit wiring 30, respectively. The connection terminal 14 can be electrically connected to the capacitance detection section of the circuit board. Thereby, the flexible touch sensor 1 can detect when a conductor comes into contact with or comes close to the detection electrode 20 from a change in the capacitance of the detection electrode 20.

The material of the circuit wiring 30 is not particularly limited, and examples thereof include the same material as the detection electrode 20, and silver ink is preferable.
Although the average thickness of the circuit wiring 30 is not limited, it can be, for example, approximately the same as the average thickness of the detection electrode 20.

The carbon layer 40 is provided on the surface of each of the three detection electrodes 20 on the side opposite to the base sheet 10. In the example shown in FIGS. 1 and 2, the carbon layer 40 is provided on the entire surface of each detection electrode 20 on the side opposite to the base sheet 10. Note that the carbon layer 40 is not limited to the embodiment in which the carbon layer 40 is provided on the entire surface of the detection electrode 20, and the carbon layer 40 may be provided only on a part of the surface of the detection electrode 20.

The carbon layer 40 is a film containing carbon, and can be formed from a carbon material. Examples of the carbon material include carbon ink containing carbon black, graphite, carbon nanotubes, and the like.
The carbon layer 40 provided on the surface of the detection electrode 20 can serve as a probe point with which a probe is brought into contact when testing electrical characteristics. That is, by bringing a probe into contact with the carbon layer 40, the electrical characteristics of the flexible touch sensor 1 can be inspected after manufacturing.

The carbon layer 40 made of carbon material has high strength and does not corrode. Therefore, the portion of the detection electrode 20 covered with the carbon layer 40 is sufficiently protected without providing a protective layer. Therefore, on the surface of the detection electrode 20 opposite to the base sheet 10, there is no restriction on the location where the carbon layer 40 is provided, and the carbon layer 40 can be provided freely.
When the detection electrode 20 has a pattern such as a grid or mesh, conventionally, it has been necessary to check whether the pattern is properly formed or not by visually checking whether the wire is thick, thin, blurred, or broken. . However, if the carbon layer 40 is provided on the entire surface of the detection electrode 20, or if the carbon layer 40 is provided at multiple locations to serve as probe points, it is possible to better determine whether the pattern is formed correctly by bringing the probe into contact with the carbon layer 40. It can be tested accurately and easily.
A carbon layer may be further formed on the connection terminal 14 portion of the circuit wiring 30. Thereby, the contacts of the circuit wiring 30 can also be protected.

The average thickness of the carbon layer 40 is preferably 0.1 μm or more, more preferably 1.0 μm or more, in that the detection electrode 20 is easily protected and is not easily damaged by contact with a probe during inspection. In terms of easily reducing the thickness of the flexible touch sensor 1, the average thickness of the carbon layer 40 is preferably 50 μm or less, more preferably 25 μm or less. The lower limit and upper limit of the average thickness of the carbon layer 40 can be arbitrarily combined, for example, preferably 0.1 to 50 μm, more preferably 1.0 to 25 μm.
Note that the average thickness of the carbon layer is the average value of thicknesses measured at ten arbitrary locations on the carbon layer.

The insulating protective layer 50 is a film made of an insulating material.
The insulating protective layer 50 is provided on the first surface 10a side of the base sheet 10 so as to cover all parts other than the part where the carbon layer 40 is provided.

The insulating material constituting the insulating protective layer 50 is not particularly limited, and resist ink is preferred. Examples of insulating resins included in the resist ink include acrylic resins, polyester resins, polystyrene resins, polyamide resins, chlorinated polyolefin resins, chlorinated ethylene-vinyl acetate copolymers, chlorinated vinyl-vinyl acetate copolymers, and cyclic resins. Examples include rubber compound and coumaron-indene resin. Among these, acrylic resin with good light transmittance is preferred in terms of being easy to bend and taking advantage of the advantages of a transparent film. The number of insulating resins that constitute the insulating protective layer 50 may be one type or two or more types.

In terms of ensuring sufficient strength and rigidity and easily protecting the circuit wiring 30, the average thickness of the insulating protective layer 50 is preferably 5 μm or more, more preferably 10 μm or more. In terms of easily reducing the thickness of the flexible touch sensor 1, the average thickness of the insulating protective layer 50 is preferably 250 μm or less, more preferably 100 μm or less. The lower and upper limits of the average thickness of the insulating protective layer 50 can be arbitrarily combined, for example, preferably 5 to 250 μm, more preferably 10 to 100 μm.
Note that the average thickness of the insulating protective layer is the average value of the thicknesses measured at arbitrary 10 locations on the insulating protective layer.

The method for manufacturing the flexible touch sensor 1 is not particularly limited, and any known method can be used. For example, as shown in FIG. 6, screen printing is performed on the first surface 10a of the base sheet 10 using silver ink or the like to form the detection electrodes 20 and the circuit wiring 30. Next, as shown in FIG. 7, screen printing is performed on the surface of the detection electrode 20 using carbon ink to form a carbon layer 40. Next, resist ink is printed on a portion of the first surface 10a of the base sheet 10 other than the portion where the carbon layer 40 is provided, to form an insulating protective layer 50. Thereby, a flexible touch sensor 1 is obtained.

As described above, in the flexible touch sensor 1, the carbon layer 40 is provided on the surface of the detection electrode 20 opposite to the base sheet 10, and the carbon layer 40 is provided on the surface of the base sheet 10 on the side where the detection electrode 20 is provided. The portion other than the portion provided with is covered with an insulating protective layer 50. Thereby, the electrical characteristics can be tested using the carbon layer 40 as a probe point while sufficiently protecting the detection electrode 20. In addition, in the flexible touch sensor 1, since the carbon layer 40 is laminated on the surface of the detection electrode 20, noise due to parasitic capacitance is less likely to occur, compared to when the probe point is provided close to the detection electrode. Detection can be suppressed.

Note that the flexible touch sensor of the present invention is not limited to the flexible touch sensor 1 described above.
For example, the flexible touch sensor 2 illustrated in FIG. 8 may be used. The same parts in FIG. 8 as those in FIG. 2 are given the same reference numerals, and the description thereof will be omitted. In the flexible touch sensor 2, a carbon layer 40 is provided on a part of the surface of the detection electrode 20 opposite to the base sheet 10, and the remaining part of the surface of the detection electrode 20 is covered with an insulating protective layer 50. The other aspects are the same as the flexible touch sensor 1.

[Touch sensor module]
The touch sensor module of the present invention is a touch sensor module equipped with the flexible touch sensor of the present invention. The touch sensor module of the present invention can employ any known aspect except that it includes the flexible touch sensor of the present invention. In the touch sensor module of the present invention, for example, the flexible touch sensor of the present invention is attached to the back of the operation panel. An example of the touch sensor module of the present invention will be described below.

As shown in FIG. 9, the touch sensor module 100 (hereinafter also referred to as "module 100") of the embodiment includes an operation panel 110 having an operation surface 112, a frame member 120, an internal light source 130, and a flexible touch sensor. 1.

The operation panel 110 and the frame member 120 are fixed by a spring 140 while being spaced apart from each other. Note that the operation panel 110 and the frame member 120 may be fixed with positioning pins, screws, etc., without being limited to the manner in which they are fixed using springs. The flexible touch sensor 1 is attached to the back surface of the operation panel 110 via an adhesive layer 60 provided on the second surface 10b of the base sheet 10. In the module 100, the surface of the operation panel 110 opposite to the flexible touch sensor 1 is an operation surface 112. A touch operation on the operation surface 112 of the operation panel 110 can be detected by a change in the capacitance of the detection electrode 20 of the flexible touch sensor 1.

The method of attaching the flexible touch sensor 1 to the operation panel 110 is not particularly limited, and examples include a diaphragm method and a roller method. Among these, the diaphragm method is preferable because it is easy to prevent air bubbles from entering between the flexible touch sensor 1 and the operation panel 110, and the flexible touch sensor 1 can be easily attached neatly.

The operation panel 110 is not particularly limited, and may include, for example, a panel body and a decoration layer formed on the surface of the panel body. Examples of the material constituting the panel body include PC, resin such as acrylic resin, and glass.

The decoration layer is a layer on which arbitrary decorations are given, such as decorations, letters, figures, symbols, patterns, combinations of these, or combinations of these and colors. The decorative layer can be formed, for example, by printing on the panel body. Note that the operation panel 110 may not have a decorative layer.

In order to easily obtain sufficient strength, the average thickness of the operation panel 110 is preferably 0.05 mm or more, more preferably 2 mm or more. In order to easily prevent the module 100 from becoming excessively thick, the average thickness of the operation panel 110 is preferably 10 mm or less, more preferably 5 mm or less. The lower and upper limits of the average thickness of the operation panel 110 can be arbitrarily combined, for example, preferably 0.05 to 10 mm, more preferably 2 to 5 mm.
Note that the average thickness of the operation panel is the average value of the thicknesses measured at ten arbitrary locations on the operation panel.

Examples of materials for forming the frame member 120 include resin, glass, and inorganic materials. Examples of the resin forming the frame member 120 include the same resins as those exemplified as the resin forming the panel body.

In the module 100, an internal light source 130 is arranged on the flexible touch sensor 1 side of the frame member 120 and on the opposite side of the carbon layer 40 from the operation panel 110. As a result, in the module 100, the light emitted from the internal light source 130 passes inside the detection electrode 20 and the annular portion of the carbon layer 40, and the characters and the like on the operation surface 112 of the operation panel 110 are illuminated.

Note that the technical scope of the present invention is not limited to the above embodiments.
For example, as long as the carbon layer has a sufficiently low resistance value, only the carbon layer 40 that also serves as the detection electrode 20 may be provided instead of providing the detection electrode 20 and the carbon layer 40 in a laminated manner. Similarly, when forming a carbon layer on the connection terminal 14 portion of the circuit wiring 30, instead of forming the circuit wiring 30 and the carbon layer in a laminated manner, only the carbon layer that also serves as the circuit wiring 30 may be formed. In such a case, a flexible touch sensor can be manufactured by simply forming a carbon layer without providing a protective layer, and probe points can also be set freely.
Note that "sufficiently low resistance value" refers to a volume resistivity of 1 Ω·cm or less and a sheet resistance of 1000 Ω/□ or less.

Further, a capacitance detection section (IC) may be provided on the surface of the frame member 120 on the flexible touch sensor 1 side, and the frame member 120 may be used as a control board. Furthermore, the control board may be connected to the flexible touch sensor 1 via a connector.
In addition, without departing from the spirit of the present invention, the components in the embodiments described above may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate.

DESCRIPTION OF SYMBOLS 1, 2... Flexible touch sensor, 10... Base material sheet, 10a... First surface, 10b... Second surface, 20... Detection electrode, 30... Circuit wiring, 40... Carbon layer, 50... Insulating protective layer, 60... Adhesion Layer, 100... touch sensor module, 110... operation panel, 120... frame member, 130... internal light source, 140... spring.

Claims (5)

a base sheet made of resin; a detection electrode provided on one side of the base sheet in the thickness direction; and a detection electrode provided on the one side of the base sheet and electrically connected to the detection electrode. A flexible touch sensor that detects contact or proximity of a conductor to the detection electrode from a change in capacitance of the detection electrode due to contact or proximity of the conductor to the detection electrode. ,
A carbon layer provided on at least a part of the surface of the detection electrode opposite to the base sheet, and a carbon layer having a volume resistivity of 1 Ω·cm or less and a sheet resistance of 1000 Ω/□ or less, further comprising at least one carbon layer that also serves as
A flexible touch sensor, wherein a portion of the base sheet on the side where the detection electrode is provided other than the portion where the carbon layer is provided is covered with an insulating protective layer. The flexible touch sensor according to claim 1, wherein a carbon layer is provided on the entire surface of the detection electrode opposite to the base sheet. The flexible touch according to claim 1, wherein the detection electrode has a mesh shape including an annular portion and a partition portion that partitions the inside of the annular portion into a plurality of regions when viewed from the thickness direction of the base sheet. sensor. The flexible touch according to claim 2, wherein the detection electrode has a mesh shape including an annular portion and a partition portion that partitions the inside of the annular portion into a plurality of regions when viewed from the thickness direction of the base sheet. sensor. A touch sensor module comprising the flexible touch sensor according to any one of claims 1 to 4.

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