JP2008232954A - External stimulus detection system - Google Patents

Abstract

An external stimulus detection system capable of reducing the amount of wiring connecting a conductive fiber and a measuring device is provided.
SOLUTION: A sheet-like sensor 1 configured by weaving conductive fibers 13 on fibers 12 and a pressure detection unit 2 for calculating the magnitude of an external stimulus applied to the sheet-like sensor 1 are provided. A pressure-sensitive part 13b whose impedance is changed by an external stimulus and a non-pressure-sensitive part 13a having a predetermined impedance whose impedance is not changed by an external stimulus are formed. On the other hand, when detecting the external stimulus, the pressure detection unit 2 supplies an input wave from the end of the conductive fiber 13, measures the reflected wave reflected in the conductive fiber 13, and determines the reflected wave as the reflected wave. Based on this, the impedance of the pressure sensitive part 13b is calculated, and the magnitude of the external stimulus in the pressure sensitive part 13b is measured.
[Selection] Figure 1

Description

  The present invention relates to an external stimulus detection system that measures the magnitude of an external stimulus applied to a sheet-like structure.

  Conventionally, a sheet-like sensor that detects an external stimulus such as pressure on a sheet surface is known. This sheet-like sensor is used in a pressure distribution detection device that measures a pressure distribution for each minute part to which pressure is applied. This pressure distribution detection device is used, for example, in an evaluation device that evaluates the sitting comfort of a vehicle seat and the sleeping comfort of a bed.

As a method for measuring the pressure distribution using the sheet-like sensor, for example, a method described in Patent Document 1 below is known. This patent document 1 describes that a plurality of conductive fibers (surface temperature resistance change conductive fibers) are arranged vertically and horizontally to constitute a sheet-like sensor. In this sheet-like sensor, a voltage is applied to one conductive fiber on one side of the buffer cloth, and one conductive fiber on the other side of the buffer cloth is grounded. And the electric current between these two conductive fibers is measured with a measuring device, and the pressure applied to the intersection of these two conductive fibers is estimated. This measurement is performed by sequentially scanning and selecting two conductive fibers by a measuring device. Thus, conventionally, the pressure distribution on the seat surface has been obtained by a measuring device.
JP 2003-33262 A

  However, when the pressure distribution in a certain region is measured using the pressure measurement method described above, there is a problem that the amount of wiring increases because it is necessary to connect to the measuring device main body for each conductive fiber.

  Then, this invention is proposed in view of the above-mentioned situation, and it aims at providing the external stimulus detection system which can reduce the wiring quantity which connects a conductive fiber and a measuring device.

  The external stimulus detection system according to the present invention includes a sheet-like sensor configured by weaving conductive fibers on non-conductive fibers, and a detection unit that calculates the magnitude of the external stimulus applied to the sheet-like sensor. In this external stimulus detection system, the conductive fiber is configured by forming a detection region in which the impedance is changed by the external stimulus and a non-detection region having a predetermined impedance in which the impedance is not changed by the external stimulus. On the other hand, when detecting an external stimulus, the detection unit supplies an input wave from the end of the conductive fiber, measures a reflected wave reflected by the input wave in the conductive fiber, and detects a detection region based on the reflected wave. The size of the external stimulus in the detection area is measured.

  Such an external stimulus detection system can measure the magnitude of the external stimulus in the detection region of the conductive fiber simply by connecting the end of the conductive fiber and the detection unit.

  According to the external stimulus detection system according to the present invention, the size of the external stimulus in the detection region of the conductive fiber can be measured simply by connecting the end of the conductive fiber and the detection unit. Since the amount of wiring to connect to each other can be reduced, the volume required for wiring is reduced, the weight is reduced, and the flexibility of the connection portion is increased, so that the mountability can be improved.

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

  The present invention is applied to, for example, a sheet-like sensor 1 of a pressure detection system configured as shown in FIG. In the following description, a case where pressure is detected as an external stimulus applied to the sheet sensor 1 will be described.

  The sheet-like sensor 1 includes a conductive fiber 13 including a non-pressure-sensitive portion (non-detection region) 13a and a pressure-sensitive portion (detection region) 13b on a fiber (non-conductive fiber) 12 constituting a fabric 11 such as cotton or nylon. It has a structure that incorporates. The conductive fiber 13 is woven over the entire surface of the fabric 11 so that pressure can be detected over the entire surface of the fabric 11. Although this sheet-like sensor 1 shows a case where only one conductive fiber 13 is woven into the fabric 11, it is needless to say that a plurality of conductive fibers 13 may be woven. The sheet sensor 1 is connected to a pressure detection unit (detection unit) 2.

  In the example shown in FIG. 1, since one conductive fiber 13 is woven into the fabric 11, there is only one connection line between the sheet-like sensor 1 and the pressure detection unit 2. Moreover, although the example shown in FIG. 1 shows the case where a plurality of pressure-sensitive parts 13b are formed on the sheet-like sensor 1, it may be one place. Further, the pressure-sensitive portion 13 b has an area smaller than the area where pressure is applied to the sheet-like sensor 1. For example, when the sheet sensor 1 is a vehicle seat, the area is smaller than the seating area of the occupant.

  The conductive fiber 13 of the sheet-like sensor 1 is configured as shown in FIGS. As shown in FIG. 2, the conductive fiber 13 is configured by covering the conductive fiber 13d and the conductive fiber 13f with a covering material 13c.

  The covering material 13c is a flexible and electrically insulating material. The covering material 13c codes the conductive fiber 13d and the conductive fiber 13f inside the conductive fiber 13 from the outside. Specific examples of the covering material 13c include polyamides such as nylon 6 and nylon 66, polyethylene terephthalate, polyethylene terephthalate containing a copolymer component, polybutylene terephthalate, and polyacrylonitrile. These materials can also adjust the hardness of the covering material 13c by changing the mixing ratio.

  The conductive fibers 13d and the conductive fibers 13f are made of conductive polymer fibers, carbon fibers, or the like. The conductive fiber 13d is provided at substantially the center of the inner diameter of the conductive fiber 13. One end of the conductive fiber 13d is connected to the pressure detection unit 2, and the other end of the conductive fiber 13d is a terminal end 13e. This end portion 13e is connected to the conductive fiber 13f. The conductive fiber 13f is provided outside the conductive fiber 13 inside diameter than the conductive fiber 13d.

  As shown in FIGS. 3 to 5, the central conductive fiber 13 d is made of one conductive fiber, and the surrounding conductive fiber 13 f is made of a plurality of conductive fibers. The conductive fiber 13f forms a mesh-shaped cylinder and surrounds the conductive fiber 13d.

  In the non-pressure-sensitive portion 13a, as shown in a sectional view of FIG. 4, the interior of the covering material 13c is a cavity 13g. On the other hand, in the pressure sensitive part 13b, as shown in FIG. 5, the cavity 13g is not provided, and the covering material 13c is also filled between the conductive fiber 13d and the conductive fiber 13f.

  In the cavity 13g of the pressure-sensitive portion 13b, a plurality of conductive fibers 13f are arranged in the vicinity of the inner wall. When there is no external stimulus of pressure to the non-pressure-sensitive portion 13a, the conductive fiber 13f and the conductive fiber 13d are not in contact with each other, and the cavity 13g is secured. On the other hand, when an external stimulus of pressure is applied to the non-pressure-sensitive portion 13a, the cavity 13g is deformed in a direction in which the conductive fiber 13f contacts the conductive fiber 13d.

  When the conductive fiber 13f and the conductive fiber 13d are in contact with each other, the resistance value of the resistor composed of the conductive fiber 13d and the conductive fiber 13f changes low. When a large pressure is applied to the non-pressure-sensitive portion 13a and the number of conductive fibers 13f in contact with the conductive fibers 13d increases, the resistance value of the resistor composed of the conductive fibers 13d and the conductive fibers 13f further decreases.

  As shown in FIG. 6, the higher the pressure (pressing force) [N] applied to the non-pressure-sensitive portion 13a, the lower the impedance [Ω] of the resistor composed of the conductive fibers 13d and 13f. That is, the pressure applied to the sheet sensor 1 and the impedance of the resistor composed of the conductive fibers 13d and the conductive fibers 13f are in an inversely proportional relationship. In the state where the coating reaction force N1 of the covering material 13c in which no pressure is applied to the non-pressure-sensitive portion 13a, the impedance of the resistor composed of the conductive fiber 13d and the conductive fiber 13f is a very high value. Become.

  The pressure detection unit 2 detects the pressure applied to the sheet sensor 1 for each pressure-sensitive portion 13 b of the conductive fiber 13. For example, when the pressure detection system is mounted on a vehicle and the sheet-like sensor 1 is woven into the vehicle seat, the pressure detection unit 2 changes depending on whether the passenger is seated on the vehicle seat, the posture of the passenger, and the like. Detect the pressure value. This pressure value is transmitted to other electrical equipment that performs various processes based on, for example, the presence or absence of an occupant.

  As shown in FIG. 2, the pressure detection unit 2 includes a pulse generation unit 21 that is connected to the conductive fiber 13d of the conductive fiber 13 and outputs pulses to the conductive fiber 13d and the conductive fiber 13f. The pulse output to the conductive fiber 13 by the pulse generator 21 is an input wave of the conductive fiber 13. The voltage of the input wave is measured by the voltage measuring unit 22 with the reflected wave voltage superimposed.

  The voltage measured by the voltage measurement unit 22 is stored in the storage unit 23. The voltage value stored in the storage unit 23 is read by the calculation unit 24. The calculating part 24 calculates the pressure applied to the pressure sensitive part 13b from the read voltage value. The calculated pressure value is transmitted to various devices that perform various calculations using a pressure value (not shown). As described above, the process of outputting the pulse from the pulse generation unit 21 to the conductive fiber 13, detecting the voltage by the voltage measurement unit 22, storing the voltage value by the storage unit 23, and calculating the pressure value by the calculation unit 24, It is controlled by the control unit 25.

  Next, the operation of the pressure detection system configured as described above will be described with reference to the timing chart of FIG.

  First, the controller 25 of the pressure detection system starts pulse output from the pulse generator 21 at time t1 (FIG. 7A). Thereby, from time t1 onward, the voltage supplied from the pressure detection unit 2 to the conductive fiber 13 starts to rise (FIG. 7A), and at the same time, the voltage measured by the voltage measuring unit 22 also starts to rise (FIG. 7B). )).

  The voltage measuring unit 22 measures the voltage every sampling interval Ts after the elapse of the period Tsf from the time t1. A method for determining the period Tsf and the sampling interval Ts will be described later. The sampled voltage value is stored in the storage unit 23 (FIG. 7D). The period during which the voltage measurement unit 22 samples the voltage is from time t1 to period Tp (FIG. 7C). After time t2 when the period Tp ends, the control unit 25 causes the pulse output from the pulse generation unit 21 to the conductive fiber 13 to be zero. Thereafter, the calculation unit 24 of the pressure detection unit 2 calculates the reflection coefficient and impedance of the conductive fiber 13 using the voltage value stored in the storage unit 23, calculates the pressure value, and outputs it. This impedance corresponds to the pressure applied to the sheet sensor 1 as shown in FIG.

  Such a process of outputting a pulse from the pulse generation unit 21, measuring a voltage value by the voltage measurement unit 22, storing the voltage value in the storage unit 23, a process of calculating the pressure value by the calculation unit 24, and a calculation The process of outputting the pressure value from the unit 24 is performed within a predetermined period Tc.

  In such an operation, when a step-like pulse generated by the pulse generator 21 is incident on the conductive fiber 13, the input wave, which is the pulse, has an impedance between the non-pressure-sensitive part 13a and the pressure-sensitive part 13b. Reflected by the changing part. The reflected wave that has been reflected returns to the tip of the conductive fiber 13. In addition, the reflected wave is reflected at the portion of the conductive fiber 13 where the impedance changes, and multiple reflection occurs.

  The voltage measured by the voltage measuring unit 22 has a waveform in which an incident wave and multiple reflected waves are superimposed, and is stored in the storage unit 23. The computing unit 24 computes the impedance of the pressure sensitive unit 13b from the superimposed waveform of the input wave and multiple reflections. The impedance of the pressure-sensing unit 13b is converted into a pressure value by the computing unit 24 based on data in which the relationship between the impedance and the applied pressure shown in FIG.

  At this time, the calculation unit 24 determines the impedance of the conductive fiber 13 according to the impedance distribution of the conductive fiber 13 as illustrated in FIG. 8A and the relationship between the incident wave and the reflected wave with respect to the impedance distribution illustrated in FIG. The impedance of the pressure sensitive part 13b is calculated. The model shown in FIG. 8A is a route model in which the line of the conductive fiber 13 is divided into sections of a certain length L, and impedance is set for each section. This fixed length L is the length of the pressure sensitive part 13b.

  As shown in FIG. 8A, the impedance of the conductive fiber 13 for each fixed length is determined from the tip of the conductive fiber 13 by Z (0), Z (1), Z (2),. ) In the route model of the conductive fiber 13, impedances Z (1) and Z (5) are portions corresponding to the pressure-sensitive portion 13b, and Z (0), Z (2) Z (3) Z (4), Z (6) is a portion corresponding to the non-pressure-sensitive portion 13a. Among the impedances Z (0) to Z (6), the impedances Z (1) and Z (5) are unknown impedance parts whose impedance changes due to the pressure applied to the sheet-like sensor 1, and the others are the pressures. Regardless of this, it is a constant known impedance Zs. The reflection coefficient at the connection point of each impedance is r (0), r (1), r (2),..., R (6), and the transmission coefficient at the connection point of each impedance is t (0), t. (1), t (2), ..., t (6).

When the wave is transmitted from the impedance Z (n-1) interval to the impedance Z (n) interval, the reflection coefficient r (n) is
r (n) = (Z (n) −Z (n−1)) / (Z (n) + Z (n−1)) (Formula 1)
Given in. Therefore, the reflection coefficients r (0), r (3), r (4) at the junctions in the section where the impedances are equal are 0, and no reflection occurs. That is, for example, no reflected wave is generated between the section of impedance Z (2) and the section of impedance Z (3).

Further, the impedances on both sides of the unknown impedance Z (1) section and the unknown impedance Z (5) section are equal to the impedance Zs. Therefore, from Equation 1 above,
r (2) =-r (1)
r (6) = − r (5)
It becomes.

  If the time required for the propagation wave in the conductive fiber 13 indicating both the input wave and the reflected wave to reciprocate the length L of one section in the conductive fiber 13 is Ts, the reflected wave in the route model is a period. It changes with Ts. As shown in FIG. 8B, the voltage change at the period Ts of the incident wave is Vi (n) (n = 0, 1, 2,...), And the voltage change at the period Ts of the reflected wave is Vo ( n) (n = 0, 1, 2,...), the wave incident from the left end of the conductive fiber 13 and the reflected wave are in the time axis direction (from top to bottom) at the left end of the conductive fiber 13. Described in

  The incident wave on the conductive fiber 13 travels through the conductive fiber 13 from left to right, but is reflected at a portion where the reflection coefficient r (n) is not 0 and travels from right to left. Where n is an index value of the section on the conductive fiber 13, m is an index value of time, an incident wave from left to right is f (n, m), and a reflected wave from right to left is b (n, m). Then, for the incident wave f (n, m) and the reflected wave b (n, m), the following formulas 2 and 3 hold at the impedance connection point.

b (n, m) = r (n + 1) * f (n, m) + t (n + 1) * b (n + 1, m-1) (Formula 2)
f (n, m) = t (n) * f (n-1, m) + r (n) * b (n, m-1) (Formula 3)
However, in the above formulas 2 and 3, when n <0 or m <0,
b (n, m) = f (n, m) = 0
f (0, m) = Vi (m), b (0, m) = Vo (m + 1)
It becomes.

Also, the reflection coefficient r (n) and the transmission coefficient t (n) are t (n) = 1 + r (n) (Formula 4)
There is a relationship.

  From the relationship of Equation 1, the unknown impedance Z (1) is obtained by obtaining the reflection coefficient r (1). Further, in Equation 2, when n = m = 0, Vo (1) = r (1) * Vi (0) is obtained, so that if the reflected wave Vo (0) of the incident wave Vi (0) is measured, the reflected wave is reflected. The coefficient r (1) can be calculated.

  However, the incident wave Vi (0) is an initial part of the rising edge of the pulse, and the S / N is low because the voltage value of the pulse is small. In addition, since there is a rapid voltage change due to the rise of the pulse, the measurement value of the voltage value varies greatly with respect to the sampling time. For this reason, when the input wave Vi (0) and the reflected wave Vo (0) immediately after the pulse is output from the pulse generator 21 to the conductive fiber 13, the calculation error of the impedance becomes large. Therefore, in order to reduce the impedance calculation error, the reflected wave is measured at the portion where the incident wave is stable, and the impedance is calculated.

  That is, as shown in FIG. 7A, the incident wave changes less as time passes. Therefore, it is desired to use a value with a larger time index value, but it is calculated when reflected waves of a plurality of unknown impedances are superimposed. Therefore, the reflected wave having the maximum time index value that does not overlap the reflected wave of the next unknown impedance is used.

When obtaining the reflection coefficient r (1), the last reflected wave on which the reflected wave from the unknown impedance Z (5) is not superimposed is Vo (4), and the incident wave Vi (0) changes to the input wave Vi (3). It is represented by the sum of values obtained by multiplying the transmission coefficient and the reflection coefficient at both ends of the unknown impedance. Since the transmission coefficient and the reflection coefficient have the relationship of Expression 4, the transmission coefficient and the reflection coefficient become a multidimensional expression of the reflection coefficient r (1). Since the order is the number of transmissions / reflections, the reflected wave Vo (4) is a seventh order expression of the reflection coefficient r (1). If the variation range of the unknown impedance is limited and the magnitude of the reflection coefficient is 0.3 or less, the magnitude of the fifth or higher order term (Vi (0), Vi (1) reflection) is 0 as a whole. Since it is 1% or less, it can be approximated by a cubic equation. Therefore, the reflected wave Vo (4) is expressed by the following formula 5,
Vo (4) =-r (1) ^ 3 * Vi (2) + (Vi (3) -Vi (2)) * r (1) (Formula 5)
It is expressed. The wave to be measured is Vi (4) + Vo (4), but since the incident waves Vi (2), Vi (3), Vi (4) can be measured in advance, the reflection coefficient r ( 1) can be calculated.

  If the reflection coefficient r (1) is calculated, an incident wave to the next unknown impedance Z (5) can be calculated. Therefore, the reflected wave Vo (8) is converted into a cubic expression of the reflection coefficient r (5) by the same method. The reflection coefficient r (5) can be calculated by measuring the reflected wave Vo (8).

  In the case of the route model shown in FIG. 8, the reflection coefficient Vo (4n) (n = 0, 1, 2,...) Is sampled by sampling the reflected wave Vo (4n) (n = 1, 2, 3,...). ) Is calculated, and the unknown impedance can be calculated by Equation (1).

  When the number of sections to the first unknown impedance is i and the section period of the unknown impedance is j, the reflected wave Vo (j * n + i−1) (n = 1, 2, 3,...) Is measured and reflected. The coefficient r (j * n + i) (n = 0, 1, 2,...) Can be calculated sequentially.

  Next, the time Tsf and the sampling period Ts for sampling the voltage in the voltage measuring unit 22 first shown in FIG. 7 will be described.

The initial sampling time Tsf from the rising start point of the incident wave and the sampling period Ts are defined as above, where i and j are defined as above, and the propagation velocity of the incident wave is v.
Tsf = 2 * (i + j−1) * Ls / v (Formula 6)
Ts = 2 * j * Ls / v (Formula 7)
There is a relationship.

The period Tp is Tp = 2 * u * Ls / v (Equation 8), where u is the total number of sections of the conductive fibers 13.
It becomes. These timings are controlled by the control unit 25, and the pulse generation unit 21, the voltage measurement unit 22, the storage unit 23, and the calculation unit 24 operate at timings as shown in FIG.

  Next, in the pressure detection system to which the present invention is applied, the case where the number of the conductive fibers 13 is increased and the magnitude of the pressure applied to the sheet-like sensor 1 will be described.

  In the pressure detection system described above, reflection occurs every time the incident wave passes through the pressure-sensitive portion 13b of the conductive fiber 13, and thus the energy propagated in the conductive fiber 13 is attenuated. Therefore, there is a limit to the number of pressure sensitive parts 13b that can be installed on one conductive fiber 13. For example, when the reflection coefficient of the pressure-sensitive part 13b is 0.3, when passing through one pressure-sensitive part 13b, the energy of the wave passing through the pressure-sensitive part 13b becomes about 80% of the energy of the incident wave. . For this reason, the energy of reflection at the last pressure-sensitive part 13b in the conductive fiber 13 is about 15% of the incident wave when five pressure-sensitive parts 13b are provided, and ten pressure-sensitive parts 13b are provided. In this case, it is about 2% of the incident wave. When the energy of the reflected wave detected by the voltage measurement unit 22 decreases, the measurement accuracy of the voltage measurement unit 22 is required, and the S / N deteriorates, leading to an increase in impedance calculation error.

  Therefore, in the pressure detection system to which the present invention is applied, when the number of the pressure sensitive parts 13b in the sheet sensor 1 is increased, it is desirable to increase the number of the conductive fibers 13 as shown in FIG. This pressure detection system weaves two conductive fibers 13 </ b> A and 13 </ b> B into the fabric 11.

  As shown in FIG. 10, the pressure detection unit 2 installs a switching unit 31 at a connection portion with the conductive fibers 13 </ b> A and 13 </ b> B. The switching unit 31 switches between a state where an input wave is input to the conductive fiber 13A and the voltage is measured by the voltage measurement unit 22, and a state where the input wave is input to the conductive fiber 13B and the voltage is measured by the voltage measurement unit 22. . As a result, the pressure sensing portion 13b can be arranged in the sheet-like sensor 1 with a small number of wires such as two conductive fibers 13A and 13B, and the pressure applied to the sheet-like sensor 1 can be obtained.

  As described above, according to the pressure detection system of the present invention, since the amount of wiring connecting the pressure detection unit 2 and the sheet-like sensor 1 can be reduced, the volume required for wiring is reduced and the weight is reduced. The mountability can be improved by increasing the flexibility of the connection part. That is, the pressure detection system is connected to the pressure detection unit 2 with a single wire for the sheet-like sensor 1 in which one conductive fiber 13 is woven into the fabric 11 and supplies an input wave to the conductive fiber 13. Then, the reflected wave reflected in the conductive fiber 13 by the input wave is measured, the impedance of the pressure-sensitive part 13b is calculated based on the reflected wave, and the external stimulus at the pressure-sensitive part 13b can be measured. .

  Further, according to the pressure detection system, the pressure can be measured for each pressure-sensitive portion 13 b formed on the conductive fiber 13, so that pressures at different positions in the sheet-like sensor 1 can be measured.

  Furthermore, according to the pressure detection system, a plurality of conductive fibers 13A and 13B are woven into the fiber 12, and the pressure detection unit 2 supplies an input wave from the end for each of the conductive fibers 13A and 13B. Since the pressure at the pressure-sensitive portion 13b of the conductive fibers 13A and 13B is measured, more pressure-sensitive portions 13b can be disposed in the sheet-like sensor 1, and more pressure values can be obtained.

  Furthermore, according to the pressure detection system, since the pressure-sensitive portion 13b of the sheet-like sensor 1 has an area smaller than the area where pressure is applied to the sheet-like sensor 1, external stimulation applied to the sheet-like sensor 1 is surely applied. It can be detected.

  Furthermore, according to the pressure detection system, the reflected wave is sampled at the timing when the reflected wave reflected by the pressure sensing unit 13b is attenuated, and the impedance of the pressure sensing unit 13b is calculated. The pressure value can be calculated at a location where the detectable voltage is stable. Thereby, the reflected wave generated by the change in impedance according to the magnitude of the external stimulus can be measured in a time with little fluctuation, and an accurate pressure amount can be detected.

  Furthermore, the pressure detection system includes a conductive fiber 13d, which is a first conductive fiber disposed in the center, and a second conductive fiber disposed in a cylindrical shape around the conductive fiber 13d. The non-pressure-sensitive portion 13a is formed of a conductive fiber 13f, and the non-pressure-sensitive portion 13a is a portion having a predetermined impedance in which the conductive fiber 13d and the conductive fiber 13f are insulated by a resin. The distance was changed by the pressure, and the impedance was changed by the contact resistance. Thereby, when an external stimulus is applied to the sheet-like sensor 1, the degree of contact between the conductive fiber 13f and the conductive fiber 13d varies depending on the magnitude of the external stimulus. Accordingly, the magnitude of the external stimulus can be obtained from the degree of change in impedance, and the pressure distribution can be accurately detected.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

It is a block diagram which shows the structure of the pressure detection system to which this invention is applied. It is a block diagram which shows the internal structure of the sheet-like sensor in the pressure detection system to which this invention is applied, and the internal structure of a pressure detection unit. It is a perspective view which shows the internal structure of the conductive fiber woven in a sheet-like sensor. It is sectional drawing of the pressure sensitive part of an electrically conductive fiber. It is sectional drawing of the non-pressure-sensitive part of a conductive fiber. It is a figure which shows the relationship between the applied pressure to a sheet-like sensor, and the impedance of a conductive fiber. It is a timing chart which shows operation | movement of the pressure detection system to which this invention is applied, (a) is a pulse output, (b) is a voltage input, (c) is a sampling interval, (d) is a processing content. In the pressure detection system to which this invention is applied, it is a figure which shows the multiple reflection in a conductive fiber, (a) is a route model of a conductive fiber, (b) is a figure which shows the model with which an input wave and a reflected wave overlap. . In the pressure detection system to which the present invention is applied, it is another block diagram in which a plurality of conductive fibers are provided. It is a block diagram which shows the internal structure of the sheet-like sensor in the pressure detection system to which this invention is applied, and the internal structure of a pressure detection unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sheet sensor 2 Pressure detection unit 11 Cloth 12 Fiber 13 Conductive fiber 13a Non-pressure-sensitive part 13b Pressure-sensitive part 13c Coating material 13d Conductive fiber 13e Termination part 13f Conductive fiber 13g Cavity 21 Pulse generation part 22 Voltage measurement part 23 Storage part 24 Calculation unit 25 Control unit 31 Switching unit

Claims (6)

A sheet-like sensor configured by weaving conductive fibers on non-conductive fibers;
A detection unit that calculates the magnitude of an external stimulus applied to the sheet-like sensor,
The conductive fiber is configured by forming a detection region in which the impedance is changed by an external stimulus and a non-detection region of a predetermined impedance in which the impedance is not changed by the external stimulus,
The detection unit, when detecting an external stimulus, supplies an input wave from the end of the conductive fiber, measures a reflected wave reflected in the conductive fiber, and based on the reflected wave An external stimulus detection system characterized by calculating an impedance of a detection region and measuring the magnitude of the external stimulus in the detection region. A plurality of the detection regions are formed in the conductive fiber,
2. The external unit according to claim 1, wherein the detection unit calculates an impedance of each detection region based on a reflected wave from the conductive fiber and measures the magnitude of an external stimulus in each detection region. Stimulus detection system. The sheet-like sensor is configured by weaving a plurality of the conductive fibers into the non-conductive fibers,
The detection unit is supplied with an input wave from the end of the conductive fiber for each conductive fiber, and the magnitude of the external stimulus in the detection region based on the reflected wave reflected in the conductive fiber. The external stimulus detection system according to claim 1, wherein:   2. The external stimulus detection system according to claim 1, wherein a detection area of the sheet-like sensor is an area smaller than an application area of the external stimulus to the sheet-like sensor. 5. The detection unit according to claim 1, wherein the detection unit samples the reflected wave at a timing when the reflected wave reflected by the detection area is attenuated, and calculates the impedance of the detection area. The external stimulus detection system according to one item. The conductive fiber includes a first conductive fiber disposed in the center and a second conductive fiber disposed in a cylindrical shape around the central conductive fiber,
The non-detection region is a portion having a predetermined impedance in which the first conductive fiber and the second conductive fiber are insulated by a resin.
The detection region is a portion where the distance between the first conductive fiber and the second conductive fiber changes depending on the magnitude of the external stimulus, and the impedance changes due to contact resistance. The external stimulus detection system according to any one of claims 5 to 6.

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