JP7217060B2 - sensor wire - Google Patents

Description

The present invention relates to a sensor wire using piezoelectric material.

Conventionally, a sensor wire using a piezoelectric material is known (see, for example, Patent Document 1, etc.). When the sensor wire is deformed by force, a voltage is induced between the inner conductor and the outer conductor. This characteristic can be used for touch sensors, vibration sensors, and the like.

JP 2008-151638 A

The sensor wire disclosed in Patent Literature 1 is susceptible to external noise, which may reduce its reliability as a sensor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sensor wire that is less susceptible to external noise.

The sensor wire of the present invention that solves the above objects is
a first inner conductor having an outer periphery covered with a piezoelectric material;
a second internal conductor covering the outer periphery of the piezoelectric material;
an insulator covering the outer periphery of the second inner conductor;
an external shield conductor covering the outer periphery of the insulator;
A sensor wire comprising a sheath that covers the outer circumference of the outer shield conductor ,
At one end of the sensor wire, a first end face shield conductor surrounding the end face of the first inner conductor and conducting with the second inner conductor;
a second end shield conductor that surrounds the first end shield conductor and conducts with the outer shield conductor;
a cover member that covers up to the end of the second end face shield conductor and the sheath,
It is characterized by

According to this sensor wire, it is possible to make the end portion not used for connection with the outside less susceptible to noise.

According to the present invention, it is possible to provide a sensor wire that is less susceptible to external noise.

(A) is a cross-sectional view showing the structure of the sensor wire 10 of the first embodiment of the present invention, and (B) is a cross-sectional view showing the structure of the first inner conductor 101 of the sensor wire 10. FIG. FIG. 4 is a diagram showing an example of how to wind the first insulating coating 104; It is a figure which shows the sensor circuit 20 using the sensor electric wire 10 shown in FIG. FIG. 4 is a diagram showing an example in which an insulating member and a conductor member are applied to an end of the sensor wire 10 that is not connected to a circuit. FIG. 3 is a cross-sectional view showing the structure of a sensor wire 11 having two first inner conductors 101 covered with a first insulating coating 104; It is a figure which shows an example of the sensor circuit using the sensor electric wire 11 shown in FIG. It is a figure which shows an example of the sensor circuit using the sensor electric wire 11 shown in FIG. FIG. 2 is a cross-sectional view showing the structure of a sensor wire 12 provided with two combinations of a first insulating coating 104 covering a first inner conductor 101 and a second inner conductor 102 covering the outside thereof. 9 is a diagram showing an example of a sensor circuit using the sensor wire 12 shown in FIG. 8. FIG. (A) is a cross-sectional view showing the structure of the sensor wire 13 of the second embodiment of the present invention, (B) is a first inner conductor 201 covered with a first insulating coating 204 and a second FIG. 4 is a diagram showing a state in which the inner conductors 202 are twisted together; 11 is a diagram showing a sensor circuit 24 using the sensor wire 13 shown in FIG. 10; FIG. FIG. 4 is a diagram showing an example in which an insulating member and a conductor member are applied to an end of the sensor wire 13 that is not connected to a circuit. It is a sectional view showing a modification of a second embodiment. 14 is a diagram showing a sensor circuit 25 using the sensor wire 14 shown in FIG. 13. FIG. It is a sectional view showing a modification of a second embodiment. 16 is a diagram showing an example of a sensor circuit using the sensor wire 15 shown in FIG. 15; FIG. It is a sectional view showing a modification of a second embodiment. 18 is a diagram showing an example of a sensor circuit using the sensor wire 16 shown in FIG. 17; FIG. 18 is a diagram showing an example of a sensor circuit using the sensor wire 16 shown in FIG. 17; FIG. It is a sectional view showing a modification of a second embodiment. 21 is a diagram showing a sensor circuit 29 using the sensor wire 17 shown in FIG. 20; FIG. 4 is a diagram showing a sensor circuit 30 obtained by adding a switch 301 to part of the sensor circuit 20 shown in FIG. 3; FIG. 12 is a diagram showing a sensor circuit 31 obtained by adding a switch 301 to part of the sensor circuit 24 shown in FIG. 11; FIG. 4 shows a sensor circuit 32 in which a differential amplifier 151 for amplifying and outputting a potential difference between an external shield conductor 103 and a second internal conductor 102 is added to the sensor circuit 20 shown in FIG. 3. FIG. 12 shows a sensor circuit 33 in which a differential amplifier 251 that amplifies and outputs a potential difference between an outer shield conductor 203 and a second inner conductor 202 is added to the sensor circuit 24 shown in FIG. 11. FIG.

The sensor wire of the present invention is a wire-shaped sensor. An embodiment of this sensor wire will be described below.

[Sensor wire of the first embodiment]
FIG. 1(A) is a cross-sectional view showing the structure of the sensor wire 10 according to the first embodiment of the present invention. The sensor wire 10 has a first inner conductor 101 provided in the center, a second inner conductor 102 provided outside thereof, and an outer shield conductor 103 provided further outside thereof. A first insulating coating 104 is provided between the first inner conductor 101 and the second inner conductor 102 among them. That is, the first inner conductor 101 is covered with a first insulating coating 104 and thereby insulated from the second inner conductor 102 and the outer shield conductor 103 . A second insulating coating 105 is provided between the second inner conductor 102 and the outer shield conductor 103 . That is, the second inner conductor 102 is covered with the second insulating coating 105 and thereby insulated from the outer shield conductor 103 . Furthermore, a sheath 130 is provided outside the outer shield conductor 103 .

In FIG. 1A, the first internal conductor 101 is hatched with orthogonal oblique lines, and the second internal conductor 102 and the external shield conductor 103 are hatched with horizontal lines. The first insulating coating 104 is indicated by hatching with lines sloping to the right, and the second insulating coating 105 is indicated by hatching with lines sloping to the left.

The first internal conductor 101 is obtained by twisting seven conductor wires 1000 as shown in FIG. 1(B). Although not shown, the conductor wire 1000 shown in FIG. 1B is also formed by twisting seven thinner conductor wires (thickness of 10 μm in this embodiment). That is, the first internal conductor 101 is constructed by twisting 49 conductor wires divided into two stages.

The structure of the first inner conductor 101 is not limited to the structure of this embodiment, and the number of stages to be twisted may be different, the number of conductor lines to be twisted may be different, and the conductors to be twisted may be different. Line thickness may vary. At the time of twisting, conductor wires twisted in different directions may be combined, or the twisting direction may be changed according to the stage of twisting. Furthermore, the first inner conductor 101 may be composed of a single conductor wire. In addition, although these conductor wires are made of copper in this embodiment, the material is not particularly limited, and may be, for example, stainless steel, tungsten, titanium, magnesium, or alloys thereof. A combination of types of conductor lines may be used.

Both the second inner conductor 102 and the outer shield conductor 103 are composed of a combination of aluminum film and copper mesh, but these conductors are not limited to this configuration. Therefore, for example, it may be a metal film, a metal mesh, a helically wound metal wire, or a combination thereof. Also, the configurations and materials of the second inner conductor 102 and the outer shield conductor 103 do not need to be the same, and may be different. Also, for example, the outer shield conductor 103 may have a plurality of layers, such as a two-layer structure of a layer of metal mesh and a layer of PET film with a metal foil attached.

The first insulating coating 104 is made of a PVDF (polyvinylidene fluoride) film, which is a piezoelectric material, and is spirally wound around the first inner conductor 101 as shown in FIG. be. It should be noted that the first insulating coating 104 has piezoelectric properties due to the polarization treatment.

Although FIG. 2 shows an example in which the first insulating coating 104 is composed of two piezoelectric films, the number of piezoelectric films is not limited to this. It may be one or more. When the piezoelectric film is wound around the first internal conductor 101 , it is preferable that no gap is formed so that the first internal conductor 101 is less likely to be affected by noise. For this reason, in the first insulating coating 104 of this embodiment, as shown in FIG. 2, two strip-shaped piezoelectric films are wound in the same direction while being shifted by 180 degrees, so that the first inner conductor 101 is centered. The tension applied to the piezoelectric film is evened out to prevent gaps from being created due to bias in the film. Further, when the first internal conductor 101 is configured by twisting the conductor wire 1000 as shown in FIG. or you can wrap it in the opposite direction. Depending on this direction, the flexibility of the sensor wire 10 may be changed.

Although PVDF is used in this embodiment, the first insulating coating 104 may be made of a piezoelectric material, such as trifluoroethylene (TrEF) or a mixed crystal material of PVDF and TrEF. Alternatively, polymeric materials having a dipole moment such as polylactic acid, polyuric acid, and polyamino acid may be used. Further, the first insulating coating 104 is not limited to a configuration using a piezoelectric material film such as a PVDF film, and may be a configuration in which a piezoelectric material is applied. As such a method, it may be immersion (dripping) coating, spray coating by spraying or the like, impregnation coating, brush coating, or by a coater or the like. It may be applied by a coating device.

The second insulating coating 105 is a coating made of an insulating resin (for example, vinyl chloride, polyethylene, etc.), and unlike the first insulating coating 104 does not have piezoelectricity.

Next, a usage example of the sensor wire 10 described above will be described with reference to FIG. FIG. 3 shows a sensor circuit 20 using the sensor wire 10 shown in FIG. In this sensor circuit 20, the first internal conductor 101 and the second internal conductor 102 are connected to the differential amplifier 150, and the external shield conductor 103 is grounded. The differential amplifier 150 amplifies and outputs the potential difference between the first internal conductor 101 and the second internal conductor 102 .

When an external force is applied to the sensor wire 10 in the sensor circuit 20 described above, the first insulating coating 104 having piezoelectricity is deformed, and the piezoelectric effect causes the first internal conductor 101 and the second internal conductor 102 to form. The potential difference fluctuates. This potential difference is amplified by the differential amplifier 150 and output. That is, the sensor circuit 20 functions as a sensor that outputs a signal based on the external force applied to the sensor wire 10 .

Further, the sensor circuit 20 is configured to suppress the influence of external noise on the signal based on the external force. First, the first internal conductor 101 and the second internal conductor 102 are surrounded by an external shielding conductor 103 connected to the ground, so that the electric potential is less likely to fluctuate due to external noise. Furthermore, even if external noise passes through the external shield conductor 103, both the first internal conductor 101 and the second internal conductor 102 inside are affected by this noise, and these internal conductors are similarly affected. potential fluctuation occurs. The sensor circuit 20 is configured to amplify the potential difference between the first inner conductor 101 and the second inner conductor 102, thereby canceling out the fluctuation in potential due to the influence of external noise.

As described above, in the sensor circuit 20, when an external force is applied to the sensor wire 10, a potential difference occurs between the first inner conductor 101 and the second inner conductor 102. The potential difference between the inner conductor 101 and the second inner conductor 102 can be suppressed. With this configuration, it is possible to obtain a signal based on an external force while suppressing the influence of external noise.

The ground potential may fluctuate depending on how the outer shield conductor 103 is grounded. Since the potential difference is used, it is possible to suppress the influence of variations in the ground potential.

When using the sensor wire 10, if the first inner conductor 101, the second inner conductor 102, and the outer shield conductor 103 are exposed at the end of the side not connected to the circuit, these They may come into contact with each other, making it impossible to obtain an accurate signal based on the external force. Therefore, it is preferable to ensure the insulation of the first inner conductor 101, the second inner conductor 102, and the outer shield conductor 103 at the end on the side not connected to the circuit. Also, if there is a portion where the first inner conductor 101 and the second inner conductor 102 are not covered with the outer shield conductor 103 at the end on the side not connected to the circuit, it may be affected by external noise. There is Therefore, it is preferable to reliably shield the first internal conductor 101 and the second internal conductor 102 at the end portion not connected to the circuit.

FIG. 4 is a diagram showing an example in which an insulating member and a conductor member are applied to the end of the sensor wire 10 that is not connected to the circuit. In this figure, insulating members 171 and 173, conductor members 172 and 174, and a cover member 175 are applied to the ends. step by step.

FIG. 4A shows the exposed ends of the first inner conductor 101, the second inner conductor 102, and the outer shield conductor 103. FIG. FIG. 4B shows a state in which the insulating member 171 covers the first inner conductor 101 and the first insulating coating 104 shown in FIG. 4A. In this example, the insulating member 171 covers up to the first insulating coating 104, so that the first inner conductor 101 can be reliably insulated from other conductors without being exposed.

FIG. 4(C) shows a state in which the insulating member 171 and the second internal conductor 102 together with the insulating member 171 are covered with the conductor member 172 from the state shown in FIG. 4(B). In this example, the potentials of the second inner conductor 102 and the conductor member 172 are the same. This conductor member 172 can make the first inner conductor 101 less susceptible to external noise.

FIG. 4(D) shows a state in which the conductor member 172 and the second insulating coating 105 are covered with the insulating member 173 from the state shown in FIG. 4(C). In this example, the insulating member 173 covers up to the second insulating coating 105, so that the second inner conductor 102 can be reliably insulated from other conductors without being exposed.

FIG. 4(E) shows a state in which the insulation member 173 and the outer shield conductor 103 are covered with the conductor member 174 from the state shown in FIG. 4(D). In this example, the potentials of the outer shield conductor 103 and the conductor member 174 are the same. The conductor member 174 shields the first internal conductor 101 and the second internal conductor 102, making it less susceptible to external noise.

FIG. 4(F) shows a state in which the conductive member 174 and the sheath 130 together with the conductor member 174 are covered with a cover member 175 (same material as the sheath 130) from the state shown in FIG. 4(E). In this example, the ends provided with insulating members 171, 173 and conductive members 172, 174 can be protected. Alternatively, the cover member 175 may be made of a heat-shrinkable (or heat-sealable) material and heated while covering the end portion so that the cover member 175 is brought into close contact with the member.

Note that the insulating members 171 and 173 described in the above example may be made of an insulating material (for example, vinyl chloride, polyethylene, etc.). Also, the conductor members 172 and 174 may be made of a conductive material (for example, aluminum, copper, tin, or an alloy of multiple materials, etc.). Also, the shape of the conductor members 172 and 174 is not limited, and may be a film shape, a mesh shape, or a tubular bar terminal.

Note that the insulating members 171 and 173, the conductor members 172 and 174, and the cover member 175 described in the above example may not all be applied, such as using only the cover member 175 or excluding the conductor member 172. good. In addition, not limited to the above example, for example, when the end portion other than the sheath 130 is flat, the end portion other than the sheath 130 is covered with an insulating member, and the conductor is formed so as to contact the outer shield conductor 103 thereon. A configuration of covering with a member and further providing a cover member may be used. In addition, the first inner conductor 101, the first insulating coating 104, the second inner conductor 102, and the second insulating coating 105 are cut shorter than the outer shield conductor 103, and after insulating these, the outer shield A configuration in which the conductor 103 is wrapped and a cover member is further provided may be used. That is, the configuration is not limited as long as the configuration ensures insulation and shielding between conductors.

[Modification 1 of the first embodiment]
The sensor wire 10 described in FIG. 1 has a configuration in which the first inner conductor 101 covered with the first insulating coating 104 is one structure, but the first inner conductor covered with the first insulating coating 104 A configuration in which a plurality of 101 are provided may be employed. FIG. 5 is a cross-sectional view showing the structure of the sensor wire 11 provided with two first inner conductors 101 covered with the first insulating coating 104. As shown in FIG. In the sensor wire 11, the first inner conductors 101A and 101B constitute a plurality of (here, two) cores, and each of these cores outputs a signal based on an external force. Although there is a gap between the first insulating coatings 104A, 104B and the second inner conductor 102 in this cross-sectional view, this gap is filled with an inclusion. In providing a plurality of first inner conductors 101 covered with the first insulating coating 104, they may be twisted together in order to suppress the influence of external noise. Furthermore, the first inner conductors 101 are configured to have different potential fluctuations (sensor sensitivities) with respect to external forces, such as by making the thicknesses of the first insulating coatings 104A and 104B different, or by making the materials different. You may Further, the second inner conductor 102 may have the same structure as the sensor wire 10 in FIG. 1, or may have a structure using an interposition made of a conductive material.

6 and 7 are diagrams showing an example of a sensor circuit using the sensor wire 11 shown in FIG. The sensor circuit 21 shown in FIG. 6 employs a configuration in which the outputs of the plurality of first internal conductors 101A and 101B are combined and amplified, and sensitivity to external forces can be enhanced. On the other hand, the sensor circuit 22 shown in FIG. 7 is configured to amplify the potential difference between each of the plurality of first internal conductors 101A and 101B and the second internal conductor 102 and output a plurality of signals. When the first inner conductors 101A and 101B have different potential fluctuations (sensor sensitivities) with respect to external forces, and the structure of the sensor circuit 22 shown in FIG. A large dynamic range can be obtained.

[Modification 2 of the first embodiment]
The sensor wire 11 described in FIG. 5 is provided with a plurality of first inner conductors 101 covered with a first insulating coating 104, and these are covered together with one second inner conductor 102. However, this second internal conductor 102 may be provided for each of the first internal conductors 101 covered with the first insulating coating 104 . FIG. 8 is a cross-sectional view showing the structure of the sensor wire 12 provided with two combinations of the first insulating coating 104 covering the first inner conductor 101 and the second inner conductor 102 covering the outside thereof. In this sensor electric wire 12, a plurality of cores are formed by the first inner conductors 101A and 101B, and a signal based on an external force is output from each of these cores. In providing a plurality of first inner conductors 101 covered with the first insulating coating 104, these may be twisted to suppress the influence of external noise, or the first insulating coating 104A, It is the same as the sensor wire 11 in FIG. 5 in that the thickness of 104B is made different or the material is made different. Furthermore, when constructing a sensor circuit using this sensor wire 12, outputs of a plurality of first internal conductors 101A and 101B are combined to form a second internal conductor 102 ( 102A, 102B, or both), or as in the sensor circuit 22 of FIG. A configuration may be employed in which a potential difference with conductor 102 (either or both of 102A and 102B) is amplified to output a plurality of signals.

FIG. 9 is a diagram showing an example of a sensor circuit using the sensor wire 12 shown in FIG. In the sensor wire 12, the first inner conductor 101A and the second inner conductor 102A belong to one core, and the first inner conductor 101B and the second inner conductor 102B belong to the other core. . Here, the first insulating coatings 104A and 104B provided on these cores may have variations in thickness during manufacturing, and as a result, the amount of change in potential according to the external force varies depending on the part. may differ compared to Therefore, the sensor circuit 23 shown in FIG. 9 adopts a configuration that amplifies the potential difference between internal conductors belonging to different cores instead of the potential difference between internal conductors belonging to the same core. Specifically, the potential difference between the first internal conductor 101A and the second internal conductor 102B and the potential difference between the first internal conductor 101B and the second internal conductor 102A are amplified, and the potential difference between these outputs is amplified. It adopts an amplifying configuration. With this configuration, even if variations occur in the amount of change in the potential according to the external force, the output can be averaged and stabilized.

[Sensor wire of the second embodiment]
FIG. 10(A) is a cross-sectional view showing the structure of the sensor wire 13 of the second embodiment of the invention.

The sensor wire 13 has a first inner conductor 201 and a second inner conductor 202 covered with a first insulating coating 204, a second insulating coating 205 covering them, and a It has an outer shield conductor 203 . The first inner conductor 201, the second inner conductor 202, and the outer shield conductor 203 are insulated from each other. Furthermore, a sheath 230 is provided outside the outer shield conductor 203 . Although there is a gap between the first insulating coating 204, the second inner conductor 202, and the second insulating coating 205 in this cross-sectional view, this gap is filled with an inclusion. In the first embodiment described above, the second inner conductor 102 does not form a core different from the first inner conductor 101, whereas in this second embodiment, the second inner conductor 202 forms the second core. The difference is that a core different from the one internal conductor 201 is configured. In addition, the first inner conductor 201 and the second inner conductor 202 covered with the first insulating coating 204 are twisted to suppress the influence of external noise as shown in FIG. 10(B). It has become.

In FIG. 10, the first inner conductor 201 and the second inner conductor 202 are indicated by hatching with orthogonal oblique lines, and the outer shield conductor 203 is indicated by hatching with horizontal lines. The first insulating coating 204 is indicated by hatching with lines sloping to the right, and the second insulating coating 205 is indicated by hatching with lines sloping to the left.

The first internal conductor 201 and the second internal conductor 202 have the same configuration as the first internal conductor 101 in the first embodiment, and are made of the same material as the first internal conductor 101 in the first embodiment. A similar one can be adopted. The configuration and materials of the first internal conductor 201 and the second internal conductor 202 do not need to be the same, and may be different.

The outer shield conductor 203 is composed of a combination of aluminum film and copper mesh, but is not limited to this configuration. Therefore, for example, it may be a metal film, a metal mesh, a helically wound metal wire, or a combination thereof. Also, for example, the outer shield conductor 203 may have multiple layers, such as a two-layer structure of a layer of metal mesh and a layer of PET film coated with metal foil.

The first insulating coating 204 is configured using a PVDF (polyvinylidene fluoride) film, which is a piezoelectric material, similarly to the first insulating coating 104 in the first embodiment. It is spirally wound around the first inner conductor 201 in the same manner as the first insulating coating 104 in the form. This first insulating coating 204 has piezoelectric properties due to the polarization treatment. As for the material and configuration of the first insulating coating 204, the same materials as those of the first insulating coating 104 in the first embodiment can be adopted.

The second insulating coating 205 is a coating made of insulating resin (for example, vinyl chloride, polyethylene, etc.), and unlike the first insulating coating 204 does not have piezoelectricity.

Next, a usage example of the sensor wire 13 shown in FIG. 10 will be described with reference to FIG. FIG. 11 shows a sensor circuit 24 using the sensor wire 13 shown in FIG. In this sensor circuit 24, the first internal conductor 201 and the second internal conductor 202 are connected to the differential amplifier 250, and the external shield conductor 203 is grounded. The differential amplifier 250 amplifies and outputs the potential difference between the first internal conductor 201 and the second internal conductor 202 .

When an external force is applied to the sensor wire 13 in the sensor circuit 24, the first insulating coating 204 having piezoelectricity is deformed, and the piezoelectric effect causes the first inner conductor 201 and the second inner conductor 202 to become deformed. electric potential fluctuates between This potential difference is amplified by the differential amplifier 250 and output. That is, the sensor circuit 24 functions as a sensor that outputs a signal based on the external force applied to the sensor wire 13 .

Further, the sensor circuit 24 is configured to suppress the influence of external noise on the signal based on the external force. First, the first internal conductor 201 and the second internal conductor 202 are surrounded by an external shielding conductor 203 connected to the ground, so that their potentials are less likely to fluctuate due to external noise. Furthermore, even if the external noise passes through the external shield conductor 203, both the first internal conductor 201 and the second internal conductor 202 inside are affected by this noise, and the internal conductors are similarly affected. potential fluctuation occurs. The sensor circuit 24 is configured to amplify the potential difference between the first inner conductor 201 and the second inner conductor 202, thereby canceling out the fluctuation in potential due to the influence of external noise.

As described above, in the sensor circuit 24, when an external force is applied to the sensor wire 13, a potential difference is generated between the first inner conductor 201 and the second inner conductor 202. The potential difference between the inner conductor 201 and the second inner conductor 202 can be suppressed. With this configuration, it is possible to obtain a signal based on an external force while suppressing the influence of external noise.

The ground potential may fluctuate depending on how the outer shield conductor 203 is grounded. Since the potential difference is used, it is possible to suppress the influence of variations in the ground potential.

When using the sensor wire 13, if the first inner conductor 201, the second inner conductor 202, and the outer shield conductor 203 are exposed at the end of the side not connected to the circuit, these They may come into contact with each other, making it impossible to obtain an accurate signal based on the external force. Therefore, it is preferable to ensure the insulation of the first inner conductor 201, the second inner conductor 202, and the outer shield conductor 203 at the end on the side not connected to the circuit. Also, if there is a portion where the first inner conductor 201 and the second inner conductor 202 are not covered with the outer shield conductor 203 at the end on the side not connected to the circuit, it may be affected by external noise. There is Therefore, it is preferable to reliably shield the first internal conductor 201 and the second internal conductor 202 at the end on the side not connected to the circuit.

FIG. 12 is a diagram showing an example in which an insulating member and a conductor member are applied to the end of the sensor wire 10 that is not connected to the circuit. In this figure, the insulating members 271 and 273, the conductor member 274, and the cover member 275 are applied to the ends. shown in

FIG. 12A shows the exposed ends of the first inner conductor 201, the second inner conductor 202, and the outer shield conductor 203. FIG. FIG. 12(B) shows a state in which the insulating member 271 covers the first inner conductor 201 shown in FIG. 12(A) together with the first insulating coating 204 . In this example, the insulating member 271 covers up to the first insulating coating 204, so that the first inner conductor 201 can be reliably insulated from other conductors without being exposed.

FIG. 12(C) shows a state in which the insulating member 271 and the second inner conductor 202 as well as the second insulating covering 205 are covered with the insulating member 273 from the state shown in FIG. 12(B). . In this example, the insulating member 273 covers up to the second insulating coating 205, so that the second inner conductor 202 can be reliably insulated from other conductors without being exposed.

FIG. 12(D) shows a state in which the insulating member 273 and the outer shield conductor 203 together with the insulating member 273 are covered with the conductor member 274 from the state shown in FIG. 12(C). In this example, the potentials of the outer shield conductor 203 and the conductor member 274 are the same. The conductor member 274 shields the first inner conductor 201 and the second inner conductor 202, making it less susceptible to external noise.

FIG. 12(E) shows a state in which the conductive member 274 and the sheath 230 together with the conductor member 274 are covered with a cover member 275 (same material as the sheath 230) from the state shown in FIG. 12(D). In this example, the ends provided with insulating members 271, 273 and conductor member 274 can be protected. Alternatively, the cover member 275 may be made of a heat-shrinkable (or heat-sealable) material and heated while covering the end portion so as to adhere to the cover member 275 .

Note that the insulating members 271 and 273 described in the above example may be made of an insulating material (for example, vinyl chloride, polyethylene, etc.). Also, the conductor member 274 may be made of a conductive material (eg, aluminum, copper, tin, or an alloy of multiple materials, etc.). Also, the shape of the conductor member 274 is not limited, and a cylindrical bar terminal may be used in addition to a film shape or a mesh shape.

The insulating members 271 and 273, the conductor member 274, and the cover member 275 described in the above example may be replaced by the cover member 275 alone, or by using an insulation member that insulates only the conductor member 272 from other conductors. so they don't have to be the same configuration. Further, not limited to the above example, for example, when the end portion other than the sheath 230 is planar, the end portion other than the sheath 230 is covered with an insulating member, and the top thereof is in contact with the external shield conductor 203. It may be configured such that it is covered with a conductor member and further provided with a cover member. In addition, the first inner conductor 201, the first insulating coating 204, the second inner conductor 202, and the second insulating coating 205 are cut shorter than the outer shield conductor 203, and after insulating these, the outer shield A configuration in which the conductor 203 is wrapped and a cover member is further provided may be used. That is, the configuration is not limited as long as the configuration ensures insulation and shielding between conductors.

[Modification 1 of the second embodiment]
The sensor wire 13 illustrated in FIG. 10 employs a configuration in which the first inner conductor 201 and the second inner conductor 202 covered with the first insulating coating 204 are covered with the second insulating coating 205. , but not limited to this configuration, for example, a first internal conductor 201 covered with a first insulating coating 204 and a second internal conductor 202 covered with a second insulating coating 205 are provided, and further these may be covered with an external shield conductor 203 . FIG. 13 is a cross-sectional view showing the structure of the sensor wire 14 employing this configuration. This sensor wire 14 has a first inner conductor 201 covered with a first insulating coating 204 and a second inner conductor 202 covered with a second insulating coating 205, and further provided outside these It has an external shield conductor 203 . The first inner conductor 201, the second inner conductor 202, and the outer shield conductor 203 are insulated from each other. Furthermore, a sheath 230 is provided outside the outer shield conductor 203 . It should be noted that the position where the second insulating coating 205 is provided is different from that of the sensor wire 13 of FIG. Although there is a gap between the first insulating coating 204, the second insulating coating 205, and the outer shield conductor 203 in this cross-sectional view, this gap is filled with an inclusion. In the sensor wire 13 of FIG. 10, the first inner conductor 201 covered with the first insulating coating 204 and the second inner conductor 202 are twisted together in order to suppress the influence of external noise. The electric wire 14 has a structure in which a first inner conductor 201 covered with a first insulating coating 204 and a second inner conductor 202 covered with a second insulating coating 205 are twisted together.

The second insulating coating 205 is made of the same material and structure as the first insulating coating 204 and does not have piezoelectricity. That is, the second insulating coating 205 differs from the first insulating coating 204 in the presence or absence of piezoelectricity. Note that the material is not limited to the same material as the first insulating coating 204, and a material different from that of the first insulating coating 204, such as insulating resin (for example, vinyl chloride, polyethylene, etc.), may be used.

FIG. 14 shows a sensor circuit 25 using the sensor wire 14 shown in FIG. This sensor circuit 25 has the same configuration as the sensor circuit 24 shown in FIG. 11 except for the position of the second insulating coating 205 . When an external force is applied to the sensor wire 14 in the sensor circuit 25, the piezoelectric first insulating coating 204 is deformed, and the piezoelectric effect causes the potential of the first inner conductor 201 to fluctuate. On the other hand, since the second insulating coating 205 does not have piezoelectricity, the potential of the second internal conductor 202 does not fluctuate according to the external force. As a result, when an external force is applied to the sensor wire 14, the potential difference between the first inner conductor 201 and the second inner conductor 202 fluctuates, and this potential difference is amplified by the differential amplifier 250 and output. That is, the sensor circuit 25 functions as a sensor that outputs a signal based on the external force applied to the sensor wire 14 .

Further, the sensor circuit 25 is configured to suppress the influence of external noise on the signal based on the external force. First, the first internal conductor 201 and the second internal conductor 202 are surrounded by an external shielding conductor 203 connected to the ground, so that their potentials are less likely to fluctuate due to external noise. Furthermore, even if the external noise passes through the external shield conductor 203, both the first internal conductor 201 and the second internal conductor 202 inside are affected by this noise, and the internal conductors are similarly affected. potential fluctuation occurs. The sensor circuit 25 amplifies the potential difference between the first inner conductor 201 and the second inner conductor 202, thereby canceling out the fluctuation in potential due to the influence of external noise. In order to more effectively cancel out the potential fluctuation due to the influence of external noise, the first internal conductor 201 covered with the first insulating coating 204 and the second internal conductor 201 covered with the second insulating coating 205 It is preferable that the electrical and physical conditions such as the length and thickness of the internal conductor 202, capacitance (dielectric constant and thickness of the insulating coating), impedance, and degree of shielding are all the same.

As described above, in the sensor circuit 25, when an external force is applied to the sensor wire 14, a potential difference is generated between the first inner conductor 201 and the second inner conductor 202. The potential difference between the inner conductor 201 and the second inner conductor 202 can be suppressed. With this configuration, it is possible to obtain a signal based on an external force while suppressing the influence of external noise.

The ground potential may fluctuate depending on how the outer shield conductor 203 is grounded. Since the potential difference is used, it is possible to suppress the influence of variations in the ground potential.

[Modification 2 of the second embodiment]
In the sensor wire 14 described in FIG. 13, both the first inner conductor 201 covered with the first insulating coating 204 and the second inner conductor 202 covered with the second insulating coating 205 are externally shielded. It is configured to be housed in one space partitioned by the conductor 203 . However, the configuration of the sensor wire is not limited to this. , may be housed in separate spaces partitioned by the outer shield conductor 203 respectively. The sensor wire 15 shown in FIG. 15 is an example of such a configuration, and includes a first inner conductor 201 covered with a first insulating coating 204 and a second inner conductor covered with a second insulating coating 205. 202 are covered with separate external shield conductors 203A and 203B, respectively. Regarding the first inner conductor 201 covered with the outer shield conductor 203A and the first insulating coating 204, and the second inner conductor 202 covered with the outer shield conductor 203B and the second insulating coating 205, the outer In order to suppress the influence of noise, they may be twisted together.

FIG. 16 is a diagram showing an example of a sensor circuit using the sensor wire 15 shown in FIG. The sensor circuit 26 shown in FIG. 16 has the same configuration as the sensor circuit 25 shown in FIG. Effective. In the sensor wire 15 shown in FIG. 15, since the two outer shield conductors 203A and 203B are in contact with each other, one of them may be grounded. Alternatively, the two outer shield conductors 203A and 203B may be insulated. In this case, both outer shield conductors 203 may be grounded as shown in FIG.

[Modification 3 of Second Embodiment]
The sensor wire 13 explained with reference to FIG. 10 and the sensor wire 14 explained with reference to FIG. A plurality of first internal conductors 201 covered with . FIG. 17 is an example of such a configuration, and is a cross-sectional view showing the structure of the sensor wire 16 provided with two first inner conductors 201 covered with the first insulating coating 204 . In this sensor wire 16, a signal based on an external force is output from each of the first inner conductors 201A and 201B. Although there are gaps between the first insulating coatings 204A and 204B, the second insulating coating 205, and the outer shield conductor 203 in this cross-sectional view, these gaps are filled with inclusions. When providing a plurality of first inner conductors 201 covered with the first insulating coating 204, they may be twisted together in order to suppress the influence of external noise. A configuration in which the second inner conductor 202 and the second inner conductor 202 are separated may also be used. Furthermore, the first inner conductors 201 are configured to have different potential fluctuations (sensor sensitivities) with respect to external forces, such as by making the thicknesses of the first insulating coatings 204A and 204B different, or by making the materials different. You may Further, in the sensor wire 16 shown in FIG. 17, the first inner conductor 201 covered with the first insulating coating 204 and the second inner conductor 202 covered with the second insulating coating 205 are all external shield conductors. 203, but as described in the example of FIG. may

18 and 19 are diagrams showing an example of a sensor circuit using the sensor wire 16 shown in FIG. 17. FIG. The sensor circuit 27 shown in FIG. 18 employs a configuration in which the outputs of the plurality of first internal conductors 201A and 201B are combined and amplified, and sensitivity to external forces can be enhanced. On the other hand, the sensor circuit 28 shown in FIG. 19 is configured to amplify the potential difference between the plurality of first internal conductors 201A and 201B and the second internal conductor 102 and output a plurality of signals. When the first inner conductors 201A and 201B have different potential fluctuations (sensor sensitivities) with respect to external forces, and the structure of the sensor circuit 28 shown in FIG. A large dynamic range can be obtained.

[Modification 4 of Second Embodiment]
In the description of the sensor wire 14 in FIG. 13, the length, thickness, static As mentioned above, it is preferable that the electrical and physical conditions such as capacitance, impedance, and shielding are the same. The number is not limited to one, and a plurality may be provided. In this case, the potential variation (sensor sensitivity) of the first inner conductor 201 caused by the external force may be the same or different in each pair.

The sensor wire 17 shown in FIG. 20 is a sectional view showing an example in which two sets of the first internal conductor 201 and the second internal conductor 202 are provided. In FIG. 20, first internal conductors 201 covered with first insulating coatings 204 are arranged on the left and upper sides, respectively, and second internal conductors covered with second insulating coatings 205 are arranged on the right and lower sides, respectively. 202 are arranged. The two first internal conductors 201 have different thicknesses of the first insulating coatings 204 covering them. Specifically, the first insulating coating 204B located on the upper side is thicker than the first insulating coating 204A located on the left side of FIG. As a result, the first internal conductor 201B located on the upper side has a higher potential fluctuation (sensor sensitivity) caused by an external force than the first internal conductor 201A located on the left side. there is Although there are gaps between the first insulating coatings 204A and 204B, the second insulating coatings 205A and 205B, and the outer shield conductor 203 in this cross-sectional view, these gaps are filled with inclusions.

When providing a plurality of the first internal conductors 201 covered with the first insulating coating 204 and the second internal conductors 202 covered with the second insulating coating 205, these conductors are used in order to suppress the influence of external noise. may be twisted together. At this time, for example, after each of the first set and the second set to be described later are twisted, they may be twisted in stages, and the method of twisting is not limited. do not have. Moreover, in the sensor wire 17 shown in FIG. 20, the first inner conductor 201 covered with the first insulating coating 204 and the second inner conductor 202 covered with the second insulating coating 205 are all external shield conductors. 203, but as described in the example of FIG. may

Of the two second internal conductors 202, the second internal conductor 202A on the right side is provided to cancel the influence of external noise on the first internal conductor 201A on the left side. The first internal conductor 201A and the second internal conductor 202A have the same configuration. In addition, the first insulating coating 204A and the second insulating coating 205A have piezoelectricity (polarization treatment is applied) while the first insulating coating 204A has piezoelectricity. differ in that they do not have piezoelectricity (not subjected to polarization treatment), but they have the same material and thickness. That is, the first internal conductor 201A covered with the first insulating coating 204A and the second internal conductor 202A covered with the second insulating coating 205A are electrically and physically conditions are met. In the following description, the set of the first internal conductor 201A covered with the first insulating coating 204A and the second internal conductor 202A covered with the second insulating coating 205A will be referred to as the first group. called.

Of the two second internal conductors 202, the lower second internal conductor 202B is provided to cancel out the influence of external noise on the upper first internal conductor 201B. The first inner conductor 201B and the second inner conductor 202B have the same configuration. Further, the first insulating coating 204B and the second insulating coating 205B have piezoelectricity (polarization treatment is applied), whereas the second insulating coating 205B differ in that they do not have piezoelectricity (not subjected to polarization treatment), but they have the same material and thickness. That is, the first internal conductor 201B covered with the first insulating coating 204B and the second internal conductor 202B covered with the second insulating coating 205B are electrically and physically conditions are met. In the following description, the set of the first inner conductor 201B covered with the first insulating coating 204B and the second inner conductor 202B covered with the second insulating coating 205B is referred to as the second set. called.

FIG. 21 shows a sensor circuit 29 using the sensor wire 17 shown in FIG. In this sensor circuit 29, a first set of first inner conductors 201A and second inner conductors 202A are connected to a differential amplifier 250, and a second set of first inner conductors 201B and second inner conductors are connected. 202B is connected to differential amplifier 250, and external shield conductor 203 is connected to ground. The differential amplifier 250 amplifies and outputs the potential difference between the first inner conductor 201 and the second inner conductor 202 in each of the first set and the second set. This sensor circuit 29 can use an appropriate signal in accordance with the external force, and a large dynamic range can be secured.

[Configuration 1 as a noise sensor]
The sensor circuits 20 to 29 of the first and second embodiments and their modifications described above cannot be effectively used in a state where no external force is applied to the sensor wires. For example, when considering applications such as applying these sensor circuits to a bed or pillow to monitor the state of a sleeping patient, the sensor wires are not subject to external force while the patient is away from the bed. cannot be used effectively. Therefore, by switching the connection to the differential amplifier in the above sensor circuit so that it can be used as a noise sensor, it is possible to increase the opportunities for use. In the above example, external noise is detected when the patient approaches the bed, so it can be used as movement data around the bed. This configuration will be described below.

In the sensor circuits 20 to 29 of the first and second embodiments and their modifications described above, the first internal conductors 101, 201 and the second internal conductors 102, 202 are all connected to the differential amplifier 150. , 250 and the outer shield conductors 103, 203 are connected to ground (FIGS. 3, 5, 6, 8, 10, 12, 14, 16, 17, 19). The outer shield conductors 103, 203 surround the first inner conductors 101, 201 and the second inner conductors 102, 202 and are most affected by external noise among these conductors. Therefore, in these sensor circuits 20 to 29, by switching one of the inputs to the differential amplifiers 150 and 250 to the external shield conductors 103 and 203, external noise is reflected in the outputs of the differential amplifiers 150 and 250. can be used as a noise sensor. At this time, the other input to the differential amplifiers 150 and 250 may be left as is or connected to ground.

A sensor circuit 30 shown in FIG. 22 is an example of the configuration described above, and is obtained by adding a switch 301 to a part of the sensor circuit 20 shown in FIG. When the switch 301 is in the initial state (the state shown in FIG. 22), it has the same configuration as the sensor circuit 20 shown in FIG. An external shield conductor 103 is connected to a differential amplifier 150 and can be used as a noise sensor.

A sensor circuit 31 shown in FIG. 23 is an example of the configuration described above, and is obtained by adding a switch 301 to a part of the sensor circuit 24 shown in FIG. When the switch 301 is in the initial state (the state shown in FIG. 23), it has the same configuration as the sensor circuit 24 shown in FIG. An external shield conductor 203 is connected to a differential amplifier 250 and can be used as a noise sensor.

22 and 21, the sensor function may be switched by switching the state of the switch 301 using a timer, for example. Alternatively, a microcomputer or the like may be used to switch the switch 301 according to desired conditions.

[Configuration 2 as a noise sensor]
In the sensor circuit 30 of FIG. 22 and the sensor circuit 31 of FIG. 23, the switch 301 is used to perform the sensor function of outputting a signal based on the external force applied to the sensor wire and the sensor function of outputting a signal due to noise. I explained the configuration to switch. The former function can be realized by amplifying the potential difference between the first internal conductors 101 and 201 and the second internal conductors 102 and 202 by the differential amplifiers 150 and 250 . For the latter function, differential amplifiers 150 and 250 amplify the potential difference between either one of the first internal conductors 101 and 201 and the second internal conductors 102 and 202 and the external shield conductors 103 and 203. It can be realized by Here, both functions may be provided without switching between these functions.

A sensor circuit 32 shown in FIG. 24 is an example of the configuration described above, and a differential amplifier that amplifies and outputs the potential difference between the outer shield conductor 103 and the second inner conductor 102 with respect to the sensor circuit 20 shown in FIG. 151 is added. This sensor circuit 32 can simultaneously use both a signal corresponding to an external force and a signal corresponding to noise.

Further, the sensor circuit 33 shown in FIG. 25 is an example of the configuration described above, and in contrast to the sensor circuit 24 shown in FIG. A dynamic amplifier 251 is added. This sensor circuit 33 can simultaneously use both a signal corresponding to an external force and a signal corresponding to noise.

For example, in the sensor circuit 20 shown in FIG. 3 and the sensor circuit 24 shown in FIG. 11, when a signal corresponding to an external force is affected by external noise, it is determined whether the signal is caused by the external force or by the external noise. It may not be possible to determine whether In the sensor circuit 32 shown in FIG. 24 and the sensor circuit 33 shown in FIG. 25, the degree of influence of external noise can be determined by the outputs of separately added differential amplifiers 151 and 251, and whether the signal corresponds to the external force can be determined. can judge.

[others]
The configuration of the sensor wire and the sensor circuit described above is an example, and the configuration is not limited as long as the content of the processing is the same. For example, in the embodiment of the sensor wire described above, the inner conductors are twisted together, but if there are three or more objects to be twisted, they may be twisted by weaving, such as braiding. Moreover, when the conductor of the sensor wire is configured in a mesh shape, there is a problem that noise may easily enter inside depending on the size of the hole. In this case, it is possible to make it difficult for noise to enter by configuring the hole so that its size is half or less of the wavelength of the noise in question. In addition, in the embodiment of the sensor circuit described above, a configuration in which one differential amplifier is shared without using a plurality of differential amplifiers may be employed, or a notch filter or the like may be provided as appropriate. In addition, in the embodiment of the sensor circuit described above, a configuration in which a differential amplifier is connected to one end of the sensor wire has been described, but both ends of the sensor wire may be connected to the same differential amplifier.

10, 11, 12, 13, 14, 15, 16, 17 Sensor wire 101, 201 First inner conductor 102, 202 Second inner conductor 103, 203 Outer shield conductor 104, 204 First insulation coating 105, 205 Second insulating coating 130, 230 Sheath 171, 173, 271, 273 Insulating member 172, 174, 274 Conductive member 175, 275 Cover member 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 Sensor Circuits 30, 31, 32, 33 Sensor circuits 150, 151, 250, 251 Differential amplifiers

Claims (2)

a first inner conductor having an outer periphery covered with a piezoelectric material;
a second internal conductor covering the outer periphery of the piezoelectric material;
an insulator covering the outer periphery of the second inner conductor;
an external shield conductor covering the outer periphery of the insulator;
A sensor wire comprising a sheath that covers the outer circumference of the outer shield conductor ,
At one end of the sensor wire, a first end face shield conductor surrounding the end face of the first inner conductor and conducting with the second inner conductor;
a second end shield conductor that surrounds the first end shield conductor and conducts with the outer shield conductor;
a cover member that covers up to the end of the second end face shield conductor and the sheath,
A sensor wire characterized by: A sensor circuit using the sensor wire according to claim 1,
The outer shield conductor is connected to ground,
A sensor circuit characterized by:

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