Sensor and yarn for sensor

Abstract

To provide a sensor which does not require power supply from the outside, and a yarn for the sensor.SOLUTION: The sensor includes a probe (1) formed from a sensor yarn (12) which includes a conductive yarn formed by spinning conductive fibers and a non-conductive yarn formed by spinning non-conductive fibers and wound around the conductive yarn to cover the conductive yarn, and in which a potential of the conductive yarn changes when a conductor contacts the non-conductive yarn in an environment in which electromagnetic waves are present, and a detecting unit (2) which detects contact of the conductor with the probe (1) based on a potential difference between a preset reference potential and a potential generated in the conductive yarn.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sensor and a sensor thread. [Background technology]

[0002] A capacitance sensor has been proposed that includes a high-frequency power supply, a capacitance forming portion having two comb-shaped electrodes formed on one surface of a substrate with their comb teeth facing each other, a resistor, and a coil connected in series or parallel, a measurement portion that measures at least one parameter from a group of parameters including the impedance, resistance, reactance, admittance, conductance, and susceptance of the capacitance sensor, and a processing portion that determines whether or not a detection target action has been performed based on the amount of change in the measured value of the parameter measured by the measurement portion within a predetermined period (see, for example, Patent Document 1). In this type of capacitance sensor, when a human finger, which is a conductor, approaches the capacitance forming portion, the measured parameter changes, and touch can be detected based on the change in the parameter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-056570 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the sensor described in Patent Document 1 requires a high-frequency power source and can therefore only be used in environments where power is supplied to the sensor from an external source, which limits the environments in which the sensor can be used.

[0005] The present invention has been made in view of the above-mentioned circumstances, and has an object to provide a sensor and a thread for the sensor that do not require an external power supply. [Means for solving the problem]

[0006] The sensor according to the present invention comprises: a probe formed from a sensor thread, the probe having a conductive thread formed by spinning conductive fibers and a non-conductive thread formed by spinning non-conductive fibers and wound around the conductive thread to cover the conductive thread, the potential of the conductive thread changing when a conductor comes into contact with the non-conductive thread in an environment where electromagnetic waves are present; and a detection unit that detects contact of the conductor with the probe based on the potential difference between a preset reference potential and the potential generated in the conductive thread.

[0007] From another viewpoint, the sensor yarn according to the present invention comprises: A conductive thread formed by spinning conductive fibers; a non-conductive yarn formed by spinning non-conductive fibers and wound around the conductive yarn to cover the conductive yarn; When a conductor comes into contact with the non-conductive yarn in an environment where electromagnetic waves are present, the potential of the conductive yarn changes. [Effects of the Invention]

[0008] According to the present invention, the sensor thread includes a conductive thread and a non-conductive thread wound around the conductive thread to cover the conductive thread. When a conductor comes into contact with the non-conductive thread in an environment where electromagnetic waves are present, the potential of the conductive thread changes. The detection unit detects contact of a conductor with the sensor thread based on the potential difference between a preset reference potential and the potential generated in the conductive thread. This allows detection of contact of a conductor with the sensor thread without supplying power to the sensor thread, thereby expanding the variety of environments in which the sensor can be used. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a sensor according to an embodiment of the present invention. [Figure 2] FIG. 10 is a schematic diagram of a probe according to a modified example. [Figure 3]1 shows photographs of the sensor yarn according to Example 1 observed with an optical microscope, where (A) is a side photograph and (B) is a cross-sectional photograph. [Figure 4] 1 shows SEM photographs of the sensor yarn according to Example 1, where (A) is a side SEM photograph, (B) is a cross-sectional SEM photograph, and (C) is an enlarged cross-sectional SEM photograph of (B). [Figure 5] 1 shows photographs of the sensor yarn according to Example 2 observed with an optical microscope, where (A) is a side photograph and (B) is a cross-sectional photograph. [Figure 6] 1 shows SEM photographs of the sensor thread of Example 2, where (A) is a side SEM photograph, (B) is a cross-sectional SEM photograph, and (C) is an enlarged cross-sectional SEM photograph of the sensor thread on the left side of (B). [Figure 7] FIG. 10 is a diagram showing the relationship between the length of the sensor thread and the resistance value according to Examples 1 and 2. [Figure 8] FIG. 10 is a diagram showing the results of measuring the time transition of the potential difference between the conductive yarn and the ground level when a weight is in contact with the sensor yarns of Examples 1 and 2. [Figure 9] This figure shows the results of measuring the time course of the potential difference between the conductive thread and the ground level for the sensor threads of Examples 1 and 2, when a weight was in contact with the sensor thread and the sensor thread was wetted with water. [Figure 10] (A) is a diagram showing the average value of the amplitude of the AC output voltage of the potential difference between the potential of the conductive yarn of the sensor yarn and the ground potential when the load applied to the sensor yarn of Example 1 is changed, and (B) is a diagram showing the resistance value and capacitance of the sensor yarn when the load applied to the sensor yarn of Example 1 is changed. [Figure 11] FIG. 10 is a schematic diagram of a probe according to Example 3. [Figure 12] 1A is a diagram showing the results of measuring the output voltage waveform from the probe according to Example 3 when a person sits on a chair with the probe placed on it and then removes it, and FIG. 1B is a diagram showing the results of measuring the output voltage waveform from the probe according to Example 3 when a mannequin is placed on the chair with the probe placed on it and then removes it. [Figure 13]1A is a diagram showing the results of measuring the output voltage waveform from the probe according to Example 3 when a person sits on a car seat with the probe laid on it and then removes the probe, and FIG. 1B is a diagram showing the results of measuring the output voltage waveform from the probe according to Example 3 when a mannequin is placed on a car seat with the probe laid on it and then removes the probe. DETAILED DESCRIPTION OF THE INVENTION

[0010] A sensor and a sensor thread according to an embodiment of the present invention will be described in detail below with reference to the drawings. The sensor according to this embodiment includes a conductive thread formed by spinning conductive fibers and a non-conductive thread formed by spinning non-conductive fibers and wound around the conductive thread to cover it, a probe formed from the sensor thread in which the potential of the conductive thread changes when a conductor comes into contact with the non-conductive thread in an environment where electromagnetic waves are present, and a detection unit that detects contact of a conductor with the probe based on the potential difference between a preset reference potential and the potential generated in the conductive thread.

[0011] 1, the sensor according to this embodiment includes a probe 1 and a detection unit 2 connected to the probe 1 via signal lines L11 and L12. The probe 1 is a rectangular sheet of fabric 11 to which one sensor thread 12 is sewn, and the signal lines L11 and L12 are electrically connected to both ends of the sensor thread 12. When a conductor such as a human finger comes into contact with the non-conductive thread of this sensor thread 12 in an environment where electromagnetic waves are present, the potential of the conductive thread inside the sensor thread 12 changes.

[0012] The sensor thread 12 includes a conductive thread formed by spinning conductive fibers and a non-conductive thread formed by spinning non-conductive fibers and wound around the conductive thread to cover the conductive thread. Examples of the non-conductive fibers include cellulose fibers and polyester fibers. Fibers made of other polymers can also be used as the non-conductive fibers. Examples of other polymers include polystyrene, polypropylene, polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, acrylonitrile-styrene copolymer, polyvinyl chloride, polyacrylonitrile, polyvinylidene chloride-acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, methyl methacrylate-styrene copolymer, polyamide, aramid, polycarbonate, amorphous fluororesin, non-ferroelectric fluororesin, derivatives of non-ferroelectric fluororesin, copolymers of non-ferroelectric fluororesin, polyhydroxybutyrate, polyurethane, polyvinyl acetate, polybutylene succinate, and silane. The polymer may be selected from the group consisting of wool, natural rubber, polyetherketone, polyarylene ether ether ketone, polyacrylonitrile-methacrylate copolymer, polybenzimidazole, polyetherimide, polyethylene sulfide, polyesterurethane, polyvinyl alcohol, polyethylene oxide, polyvinylcarbazole, polyvinylpyrrolidone, collagen, polycaprolactone, polyhydroxyalkanoic acid, polyglycolic acid, polymethyl methacrylate, amorphous poly-DL-lactic acid (PDLLA), polylactic acid derivatives, polylactic acid-glycolic acid copolymer, cellulose acetate, cellulose derivatives, chitosan, chitin, polypeptides, and proteins. Examples of polyamides include nylon 12 (registered trademark), nylon 4,6 (registered trademark), nylon 6,6 (registered trademark), and nylon 6 (registered trademark). Examples of amorphous fluororesins, non-ferroelectric fluororesins, non-dielectric fluororesin derivatives, and non-ferroelectric fluororesin copolymers include Cytop (registered trademark), polytetrafluoroethylene (PTFE), and perfluoroalkoxyalkane (PFA). Furthermore, the other polymer may be a mixture of a plurality of these polymers.

[0013] The conductive fibers include metal-plated fibers such as silver-plated fibers, conductive polymer fibers and composite fibers thereof, metal-sputtered fibers, plasma-sputtered fibers, slit threads of metal-sputtered films, fibers in which a conductive substance has been formed inside the fibers by, for example, irradiating them with infrared rays, carbon nanotubes, carbon fibers, composite fibers containing carbon or metal, etc. Furthermore, single wires or twisted wires made of metal may also be used as the conductive fibers.

[0014] The detection unit 2 includes a detection circuit including, for example, a rectifier circuit having one of two input terminals connected to the signal line L11 or L12, a capacitor connected between the output terminals of the rectifier circuit, and a light-emitting diode connected in parallel with the capacitor. The reference potential of this detection unit 2 is set to the ground potential, and when a conductor comes into contact with the probe 1 and the potential difference between the ground potential and the potential generated at the conductive thread of the sensor thread becomes equal to or greater than a preset reference voltage, the light-emitting diode lights up, indicating that the conductor has come into contact with the probe 1.

[0015] Here, we will explain the mechanism by which the sensor according to this embodiment can detect contact of a human finger, which is a conductor, with the probe. When commercial powered electrical devices, wiring cords, outlets, etc. are present around a person, electromagnetic waves are emitted from these electrical devices, wiring cords, outlets, etc. into the environment, causing electrostatic induction at a frequency of 60 Hz or 50 Hz within the human body present in this environment. When a human finger approaches the probe, electrostatic induction occurs in the conductive thread of the probe due to electrostatic induction within the human body. It is believed that this electrostatic induction occurring in the conductive thread is observed as a change in the potential of the conductive thread.

[0016] As described above, in the sensor according to this embodiment, the sensor thread includes a conductive thread and a non-conductive thread wound around the conductive thread to cover the conductive thread. When a conductor comes into contact with the non-conductive thread in an environment where electromagnetic waves are present, the potential of the conductive thread changes. The detection unit then detects contact of a conductor with the sensor thread based on the potential difference between a preset reference potential and the potential generated in the conductive thread. This allows detection of contact of a conductor with the sensor thread without supplying power to the sensor thread, thereby expanding the variety of environments in which the sensor can be used.

[0017] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments. For example, in the embodiments, the probe may be a member formed by bundling a plurality of sensor threads. Furthermore, the probe may be, for example, a fabric woven with sensor threads, a knitted fabric knitted with sensor threads, or a braided fabric braided with sensor threads.

[0018] 2, the probe 201 may have a plurality of sensor threads 212 extending along the Y-axis direction of the fabric 11 and parallel to each other along the X-axis direction, and a plurality of sensor threads 213 extending along the X-axis direction of the fabric 11 and parallel to each other along the Y-axis direction. In this case, the position in the probe 201 where the conductor made contact can be identified based on the positions at which the sensor threads 212, 213 are sewn, at which a voltage is generated due to contact with the conductor.

[0019] Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to these. The present invention includes any combination of the embodiments and modifications, and any combination to which appropriate modifications have been made. [Example]

[0020] The sensor and sensor thread according to the present invention will be described based on examples.

[0021] A sensor thread including a conductive thread formed by spinning silver-plated nylon fibers and a non-conductive thread formed by spinning cotton fibers was prepared as a sensor thread according to Example 1. Also, a sensor thread including a conductive thread formed by spinning silver-plated nylon fibers and a non-conductive thread formed by spinning polyester fibers was prepared as a sensor thread according to Example 2.

[0022] When the sensor yarn according to Example 1 was observed under a microscope, it was confirmed that the entire side surface was covered with non-conductive yarn, as shown in FIG. 3(A). The microscope used was a long-distance high-definition microscope LRA200HD-2E (manufactured by Shodensha Co., Ltd.). Furthermore, when the cross section of the sensor yarn according to Example 1 was observed under a microscope, a so-called core-sheath structure was observed, as shown in FIG. 3(B). Furthermore, when the side surface of the sensor yarn according to Example 1 was observed under an SEM, it was observed that a non-conductive yarn formed by spinning multiple non-conductive fibers was wound helically around the conductive yarn at a substantially equal pitch, as shown in FIG. 4(A). Furthermore, when the cross section of the sensor yarn according to Example 1 was observed under an SEM, it was observed that a non-conductive fiber was wound around a conductive yarn formed by a bundle of multiple conductive fibers, as shown in FIGS. 4(B) and (C).

[0023] When the sensor yarn according to Example 2 was observed under a microscope, it was confirmed that the entire side surface was covered with non-conductive yarn, as shown in FIG. 5(A). Furthermore, when the cross section of the sensor yarn according to Example 2 was observed under a microscope, a so-called core-sheath structure was observed, as shown in FIG. 5(B). Furthermore, when the side surface of the sensor yarn according to Example 2 was observed under an SEM, it was observed that a non-conductive yarn made of a bundle of multiple non-conductive fibers was wound around the conductive yarn, as shown in FIG. 6(A). Furthermore, when the cross section of the sensor yarn according to Example 2 was observed under an SEM, it was observed that a non-conductive fiber was wound around the conductive yarn made of a bundle of multiple conductive fibers, as shown in FIGS. 6(B) and (C).

[0024] The resistance values ​​per unit length of the sensor yarns according to Examples 1 and 2 were evaluated. For this evaluation, sensor yarns according to Examples 50 mm, 100 mm, 150 mm, 200 mm, and 250 mm were prepared, and the resistance value between both ends of each length of sensor yarn was measured. The slopes of the approximated lines obtained by least-squares approximation of the measurement results were then compared. As shown in FIG. 7 , the slope of the approximated line corresponding to the sensor yarn according to Example 1 was larger than the slope of the approximated line corresponding to the sensor yarn according to Example 2. The slope of the approximated line corresponding to the sensor yarn according to Example 1 was 0.2023 Ω / mm, and the slope of the approximated line corresponding to the sensor yarn according to Example 2 was 0.2650 Ω / mm. This indicates that the resistance value per unit length of the sensor yarn according to Example 1 is higher than the resistance value per unit length of the sensor yarn according to Example 2.

[0025] In addition, the potential difference between the potential of the conductive yarn and the ground potential was measured for the sensor yarns of Examples 1 and 2. Here, the sensor yarns of Examples 1 and 2 were placed on a table, a weight was placed on a portion of the sensor yarn, and then a finger was touched to the weight. The potential difference between the potential of the conductive yarn of the sensor yarn and the ground potential was measured. The weight used here was approximately cylindrical, with a base diameter of 41.6 mm and a weight of 500 g. The measurement environment was at a temperature of 22.9°C and a humidity of 49.1%. An oscilloscope (GDS-3504, manufactured by Instec / Texio Technology) was used to measure the potential difference. As shown in FIG. 8, an AC voltage output with an amplitude of approximately 0.002 V was observed for the sensor yarn of Example 2. On the other hand, an AC voltage output with an amplitude of approximately 0.06 V was observed for the sensor yarn of Example 1. This demonstrates that cotton fiber yarn is more suitable as a non-conductive sensor yarn.

[0026] Furthermore, for Examples 1 and 2, the sensor thread was placed on a table, the sensor thread was wetted with water, a weight was placed on a portion of the sensor thread, and a finger was touched to the weight, and the potential difference between the potential of the conductive thread of the sensor thread and ground potential was measured. The weight and measurement environment were the same as described above. As shown in Figure 9, an AC voltage output with an amplitude of approximately 0.5 V was observed for both the sensor threads of Examples 1 and 2. This indicates that the AC voltage output increases significantly when the sensor thread is wet with water.

[0027] Furthermore, for the sensor yarn according to Example 1, the average amplitude of the AC output voltage representing the potential difference between the conductive yarn's potential and ground potential was measured when varying the load applied to the sensor yarn in a direction perpendicular to the extension direction of the sensor yarn. Here, the sensor yarn according to Example 1 was placed on a table, and a metal pressing terminal was used to press a portion of the sensor yarn while a finger was touching the metal pressing terminal. A small knurled knob (NOBC6-10-13, manufactured by MITSUMI) with a circular tip and a diameter of 12.0 mm was used as the metal pressing terminal. As shown in Figure 10(A), a tendency for the average amplitude of the AC output voltage representing the potential difference between the conductive yarn and ground potential to increase was observed as the load pressing the sensor yarn increased. This indicates that the sensor yarn may also be applicable to evaluating the magnitude of the load applied to it.

[0028] Furthermore, the resistance and capacitance of the sensor yarn according to Example 1 were measured when the load applied to the sensor yarn in a direction perpendicular to the extension direction of the sensor yarn was changed. Here, the sensor yarn according to Example 1 was placed on a table, and the resistance and capacitance of the sensor yarn were measured using an LCR meter (IM3536: manufactured by HIOKI Corporation) with a part of the sensor yarn pressed with a metal pressing terminal. As shown in Figure 10(B), a tendency was observed in which the resistance decreased and the capacitance increased as the load pressing the sensor yarn increased.

[0029] As a probe according to Example 3, a rectangular sheet-shaped fabric 11 with sensor thread 12 sewn onto it was prepared as shown in Fig. 11. Here, a fabric woven with non-conductive thread was used as fabric 11. Furthermore, as sensor thread 12, a conductive thread made of silver-plated nylon fiber was used, which was covered with a non-conductive thread made of cotton fiber.

[0030] The voltage waveforms output from the probe according to Example 3 were measured when a person sat on a chair and then removed the probe, and when a mannequin made of a non-conductive material was placed on the chair and then removed the probe. The person sitting on the chair weighed approximately 48 kg, and the feet of the person sitting on the chair were kept in a position where they did not touch the ground. The weight of the mannequin was adjusted so that a load of approximately 48 kg was applied to the chair when the mannequin was placed on it. The mannequin was hollow and made of ABS resin. The voltage waveforms were measured using an oscilloscope SDS1102 (manufactured by OWON). As shown in Figures 12(A) and 12(B), the amplitude of the voltage output from the probe was found to be greater when a person was sitting on the chair than when the mannequin was placed on it. This shows that a sensor equipped with the probe of Example 3 can be used to determine whether a person is sitting on a chair or the like on which the probe is placed, or whether an object made of a non-conductive material is placed on it.

[0031] The probe according to Example 3 was placed on a car seat, and the voltage waveforms output from the probe before and after a person sat in the seat were measured. Also, the voltage waveforms output from the probe before and after a mannequin made of a non-conductive material was placed on the seat. The person weighed approximately 48 kg, and the rear feet of the person sitting on the seat were kept in a position where they did not contact the floor of the car. The weight of the mannequin was adjusted so that a load of approximately 48 kg was applied to the seat when the mannequin was placed on the seat. The voltage waveforms were measured using an oscilloscope SDS1102 (manufactured by OWON). The oscilloscope's ground wire was electrically connected to the car frame. The car used was a Toyota Noah (registered trademark), and the seat where the person or mannequin was placed was the passenger seat. 13(A) and (B), it was found that the amplitude of the voltage output from the probe is larger when a person is seated on the chair than when a mannequin is placed on the chair. This shows that the sensor including the probe according to Example 3 can be used to determine whether a person is seated on the chair on which the probe is placed or whether an object made of a non-conductive material is placed. [Industrial Applicability]

[0032] The present invention is suitable as a contact sensor and a pressure sensor. [Explanation of symbols]

[0033] 1,201: probe, 2: detection unit, 11: fabric, 12,212,213: sensor thread, L11, L12: signal line

Claims

1. a probe formed from a sensor thread, the probe having a conductive thread formed by spinning conductive fibers and a non-conductive thread formed by spinning non-conductive fibers and wound around the conductive thread to cover the conductive thread, the potential of the conductive thread changing when a conductor comes into contact with the non-conductive thread in an environment where electromagnetic waves are present; and a detection unit that detects contact of the conductor with the probe based on a potential difference between a preset reference potential and a potential generated in the conductive thread. Sensor.

2. The non-conductive fibers are cellulose fibers or polyester fibers. The sensor of claim 1 .

3. The conductive fiber is a carbon fiber, a composite fiber containing carbon or metal, The sensor according to claim 1 or 2.

4. The probe includes a fabric and the sensor thread sewn to the fabric. The sensor according to claim 1 or 2.

5. A conductive thread formed by spinning conductive fibers; a non-conductive yarn formed by spinning non-conductive fibers and wound around the conductive yarn to cover the conductive yarn; When a conductor comes into contact with the non-conductive yarn in an environment where electromagnetic waves are present, the potential of the conductive yarn changes. Sensor thread.

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