JP2020201186A - Seat type sensor - Google Patents

Abstract

To provide a seat type sensor that detects the presence of a detection object with high accuracy by reducing an effect of noise as much as possible.SOLUTION: A seat type sensor comprises: a first conductive yarn 17, whose both ends are connected to a first electrode 15, laid along a predetermined plane in an insulation state from a periphery; a second conductive yarn 18, whose both ends are connected to a second electrode 16, forming a capacitor as a pair with the first yarn 17 in a region other than a region surrounded by the first yarn 17 and laid along the predetermined plane in the insulation state from the periphery; and an arithmetic processing unit 12 for detecting the presence of a detection object on the predetermined plane based on frequency change during charging or discharging of the capacitor formed by the first yarn 17 and the second yarn 18.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sheet type sensor formed by using a conductive thread.

Pneumatic sensors are known as mat-type sensors, but they are very expensive, difficult to move, unable to wash, and easily become dirty. That is, the use of such mat-type sensors is limited to facilities that have introduced specific advanced systems. On the other hand, for example, labor shortages in nursing care and welfare facilities are serious, and a technique for managing facility users as efficiently as possible is desired.

In relation to such a problem, Patent Document 1 discloses a technique for detecting the presence or absence of a person or the like by utilizing a change in capacitance. In the technique shown in Patent Document 1, a thread containing conductive fibers is implanted as a pile thread of a carpet to make the carpet a three-dimensional conductor, and a dielectric potential generated when a person or an object approaches or comes into contact with the carpet is generated. , It is easy to detect as a change in capacitance on the carpet.

Japanese Unexamined Patent Publication No. 2009-244020

The technique shown in Patent Document 1 has a problem that it is very difficult to manufacture because it is necessary to embed conductive fibers in the pile yarn of the carpet, and the fiber structure is complicated and defects such as disconnection and short circuit are likely to occur. Have. Further, there is a problem that only a very small change can be detected only by a change in the capacitance between fibers, and it becomes difficult to detect when noise occurs. In particular, when measuring capacitance, there is a problem that it is important to remove noise due to the influence of moisture having a high dielectric constant (for example, moisture or sweat).

The present invention provides a sheet-type sensor that detects the presence or absence of a detection object with high accuracy while reducing the influence of noise as much as possible.

The sheet type sensor according to the present invention is composed of a first thread having conductivity in which both ends are connected to a first electrode and laid along a predetermined surface in an insulated state from the surroundings, and the first thread. In a region other than the enclosed region, a capacitor is formed in pairs with the first thread, both ends are connected to the second electrode, and the conductivity is laid along the predetermined surface in an insulated state from the surroundings. A detection means for detecting the presence or absence of a detection target object on the predetermined surface based on the frequency change of charging / discharging of the second thread having the capacitor and the capacitor formed by the first thread and the second thread. It is equipped with.

As described above, in the sheet type sensor according to the present invention, the first thread having conductivity, both ends of which are connected to the first electrode and laid along a predetermined surface in an insulated state from the surroundings, and the above. In a region other than the region surrounded by the first thread, a capacitor is formed in pairs with the first thread, both ends are connected to the second electrode, and the capacitor is laid along the predetermined surface in an insulated state from the surroundings. Presence or absence of an object to be detected on the predetermined surface based on the frequency change of charge / discharge of the capacitor formed by the second thread having conductivity and the first thread and the second thread. A capacitor is formed in which the area surrounded by the first thread is one electrode and the area surrounded by the second thread is the other electrode, and each area is used as a planar electrode. As a result, the capacitance component can be increased and the detection sensitivity can be improved.

Further, in order to detect the presence or absence of a detection target object on a predetermined surface based on the frequency change of charge / discharge of the capacitor formed in the region surrounded by the first thread and the region surrounded by the second thread, electrostatic voltage is used. Compared to the case of detecting a change in capacitance, it has the effect of being able to handle various processes by treating it as a signal having a frequency while suppressing the influence of noise.

The sheet-type sensor according to the present invention is one in which the first thread and the second thread are arranged in a state of being bent or curved a plurality of times, and are housed in an elastic coating body.

As described above, in the sheet type sensor according to the present invention, the first thread and the second thread are arranged in a state of being bent or curved a plurality of times, and are housed in an elastic coating body. Therefore, the first thread and the second thread can be expanded and contracted in response to the expansion and contraction of the covering body, and even when the covering body is expanded, the thread can be prevented from being broken. Play.

In the sheet type sensor according to the present invention, the first thread and the second thread are laid by crossing each other with each other.

As described above, in the sheet type sensor according to the present invention, since the first thread and the second thread are laid crossed with each other, the inductance component is higher than that in the case of not crossing each other. It has the effect of increasing the capacitance and increasing the detection sensitivity.

The sheet-type sensor according to the present invention has a pressure detecting means for measuring the pressure applied to the predetermined surface on the predetermined surface and the pressure detecting means correlating with the frequency waveform of charging / discharging of the capacitor. It is provided with a determination means for determining that the detection object is on the predetermined surface when the pressure waveform is detected.

As described above, in the sheet type sensor according to the present invention, the pressure detecting means for measuring the pressure applied to the predetermined surface on the predetermined surface and the frequency waveform of charging / discharging of the capacitor by the pressure detecting means. When a pressure waveform having a correlation with is detected, it is provided with a determination means for determining that the detection target is on the predetermined surface. Therefore, for example, even though there is no detection target, only the humidity is present. Even if the capacitance rises and the capacitance changes, there is no correlation with the pressure waveform, so it is possible to prevent erroneous detection. In addition, even when a pressure waveform is detected by applying pressure to the sheet type sensor such as a metal that is not the object to be detected, the capacitance does not change, so that it is possible to prevent erroneous detection. Play.

The sheet-type sensor according to the present invention has a multiplying means for multiplying the signal measured by the pressure detecting means and the frequency signal obtained by the detecting means, and peak detection for detecting the peak value of the multiplication result of the multiplying means. The output value of the frequency signal of the capacitor with the means, the SH means for sample-holding the output value of the frequency signal at the peak value detected by the peak detecting means, and the output value sample-held by the SH means as a threshold value. It is provided with a comparison means for comparison with.

As described above, in the sheet type sensor according to the present invention, the multiplying means for multiplying the signal measured by the pressure detecting means and the frequency signal obtained by the detecting means, and the peak value of the multiplication result of the multiplying means. The peak detecting means for detecting the above, the SH means for sample-holding the output value of the frequency signal at the peak value detected by the peak detecting means, and the output value sample-held by the SH means as a threshold value of the capacitor. Since it is equipped with a comparison means for comparing with the output value of the frequency signal, the threshold value for detecting the change in capacitance is set according to the environment and state of the place, so that false detection is reduced and high accuracy is achieved. It has the effect of being able to realize a sensor.

It is a functional block diagram which shows the structure of the sheet type sensor which concerns on 1st Embodiment. It is a perspective view which shows the structure of the capacitance measuring part in the sheet type sensor which concerns on 1st Embodiment. It is a figure which shows an example of the circuit structure which performs the detection process of the sheet-like sensor which concerns on 1st Embodiment. It is a figure which shows the frequency waveform at the time of repeating the charging / discharging of a capacitor in the sheet-shaped sensor which concerns on 1st Embodiment. It is a figure which shows the cycle when the charge and discharge of a capacitor are repeated in the sheet-shaped sensor which concerns on 1st Embodiment. It is a figure which shows an example of the arrangement pattern of the conductive thread in the sheet-like sensor which concerns on 1st Embodiment. It is a functional block diagram which shows the structure of the sheet type sensor which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the calculation processing part in the case of performing the calculation based on the measurement result of the capacitance measurement part and the pressure measurement part in the sheet type sensor which concerns on 2nd Embodiment. It is a figure which shows the simulation result of the sheet type sensor which concerns on 2nd Embodiment.

(First Embodiment of the present invention)
The sheet type sensor according to the present embodiment will be described with reference to FIGS. 1 to 6. The sheet-type sensor according to the present embodiment detects, for example, a sleeping state (away from bed) on a bed or a futon, or a sitting state on a chair or the like by using a change in the capacitance of a capacitor formed of a conductive thread. To do. By laying the seat type sensor according to this embodiment on a bed, a futon, a seat of a chair, etc., a change in capacitance due to a change in dielectric constant depending on whether a person is present or not is detected. To do. At this time, instead of directly detecting the value of the capacitance, the detection process is performed based on the frequency waveform of the charge / discharge of the capacitor formed of the thread on the sheet.

FIG. 1 is a functional block diagram showing a configuration of a sheet type sensor according to the present embodiment. In FIG. 1, the sheet type sensor 1 includes a capacitance measuring unit 10 for measuring the capacitance of a capacitor formed of a conductive thread, and an input unit 11 for inputting a change waveform of the measured capacitance. A calculation processing unit 12 for determining the presence or absence of a detection target object from a change in frequency based on an input waveform, and an output control unit 13 for outputting the calculation result to an output device such as a display are provided.

The capacitance measuring unit 10 and the other processing unit may be formed separately. In that case, the measurement result of the capacitance measuring unit 10 may be input to the input unit 11 via the communication interface by wired or wireless communication.

FIG. 2 is a perspective view showing the structure of the capacitance measuring unit in the sheet type sensor according to the present embodiment. The capacitance measuring unit 10 is formed as a sheet body in which a conductive thread is sewn on a sheet-like fabric and coated with a covering body, and the power supply unit 14 for supplying power and the power supply unit 14 are formed. A first thread 17 (to the first electrode 15) which is connected to the first electrode 15 and the second electrode 16 to be connected and the first electrode 15 and the second electrode 16 to be connected to form a capacitor in pairs. Support) and the second thread 18 (connected to the second electrode 16) and the first electrode 15, the second electrode 16, the first thread 17, and the second thread 18 are supported in the same plane. A body 19 and a covering body 20 that covers the support 19 are provided. In addition, although it is described in FIG. 2 that the covering body 20 covers a part of the support 19 in order to show the internal structure, it actually covers the whole of the support 19.

The first thread 17 and the second thread 18 have conductivity by being coated with or kneaded with a conductor such as silver, and both ends of the first thread 17 are first. The second thread 18 is sewn to the support 19 in a state of being electrically connected to the electrode 15 and having both ends thereof electrically connected to the second electrode 16. The support 19 has a predetermined surface (for example, a flat surface or a curved surface whose surface state changes depending on the usage state), and is preferably easily deformed according to the curve of the body and has elasticity. A fabric made of fibers is used. Further, the covering body 20 also covers the entire support 19 and preferably a cloth made of fibers which are easily deformed according to the curve of the body and have elasticity is used. At this time, each fabric is made of insulating fibers.

The first thread 17 and the second thread 18 flexibly expand and contract according to the deformation and expansion and contraction of the support 19 and the covering body 20 in order to prevent disconnection due to deformation and expansion and contraction of the support 19 and the covering body 20. It is sewn to the support 19 in a state of being bent a plurality of times so as to be possible. Specifically, for example, it is sewn in a zigzag pattern as shown in FIG. Further, in the present embodiment, since the maximum region surrounded by each thread is regarded as one electrode of the capacitor, the areas surrounded by each thread are sewn so as not to interfere with each other. Since a capacitor is formed in which the region surrounded by the first thread 17 is one electrode and the region surrounded by the second thread 18 is the other electrode, the dielectric constant on the sheet body changes (for example, what). It is possible to measure the presence or absence of an object to be detected on the sheet body (by changing to the permittivity of air when it is not present, or the permittivity of the human body when a hand is brought close to it).

The support 19 and the covering 20 may be made of, for example, a flexible resin or vinyl, in addition to the fabric shown above. Further, as described above, the first thread 17 and the second thread 18 may be bent a plurality of times and sewn, may be curved a plurality of times and sewn, or may be combined.

FIG. 3 is a diagram showing an example of a circuit configuration that performs detection processing of the sheet-shaped sensor according to the present embodiment. The signal from the capacitance measuring unit 10 is passed to the arithmetic processing unit 12 via the input unit 11. The arithmetic processing unit 12 determines the presence / absence of the detection target by using the circuit configuration as shown in FIG. In FIG. 3, a constant current source 32 is connected in series to a capacitor 31 composed of a first thread 17 and a second thread 18, and a comparator 33 for comparing with a predetermined threshold value is provided in parallel with the capacitor 31. It is connected and its output is input to the gate electrode of the inverter (FET circuit 34). The source / drain electrodes of the FET circuit 34 are connected to the capacitor 31 via a resistor 35.

In the circuit operation of FIG. 3, the capacitor 31 is first charged by the power supply from the constant current source 32. When charging progresses to some extent and the threshold value is exceeded, the output of the comparator 33 becomes Hi and the gate of the FET circuit 34 turns ON. When the gate is turned on, the electric charge charged in the capacitor 31 is released through the source / drain electrodes. When the electric charge of the capacitor 31 is released, the output of the comparator 33 becomes Lo, and the charging of the capacitor 31 is started again. The waveform when such a cycle is repeated is shown in FIG. 4 (A). In FIG. 4, the vertical axis is the voltage value of V1 in FIG. By charging and discharging the capacitor 31, the value of V1 becomes a saw waveform as shown in FIG. 4 (A). That is, the voltage rises little by little while charging the capacitor 31, and at the moment when a certain threshold value is exceeded, the charge of the capacitor 31 is discharged and the voltage drops at once. Since the period at this time depends on the capacitance of the capacitor 31, the period of the waveform shown in FIG. 4A changes when the dielectric constant of the capacitor 31 changes.

The saw waveform of FIG. 4 (A) is converted into a rectangular wave as shown in FIG. 4 (B), and the frequency of the rectangular wave of FIG. 4 (B) is measured with a frequency counter. When the capacitance increases, the time required for charging becomes long, that is, the time for the comparator 33 to output Lo becomes long, so that one cycle of FIG. 4B becomes long and the frequency decreases. On the other hand, when the capacitance is reduced, the time required for charging is shortened, that is, the time required for the comparator 33 to output Lo is shortened, so that one cycle in FIG. 4B is shortened and the frequency is increased.

An example is shown in FIG. When there is nothing (only air) on the sheet body of the capacitance measuring unit 10, it is assumed that the waveform as shown in FIG. 5 (A) is detected. When there is a human body, for example, which contains a large amount of water on the sheet body of the capacitance measuring unit 10, the capacitance increases due to the change in the dielectric constant, and one cycle of the waveform shown in FIG. 5 (A) becomes longer. As a result, the frequency drops (state in FIG. 5B). That is, by measuring the frequency of the waveform as shown in FIG. 5, it is possible to determine whether or not there is an object to be detected on the sheet body of the capacitance measuring unit 10. In addition, by determining the presence or absence of the object to be detected based on the frequency change, it is possible to handle various processes by treating it as a signal with frequency while suppressing the influence of noise compared to the case of detecting the change in capacitance. It becomes possible to do.

In the present embodiment, the length of the first thread 17 and the second thread 18 increases the resistance component (inductance). Therefore, as shown in FIGS. 6A to 6C, the respective threads are used. It is desirable that the region surrounded by the threads is made as wide as possible to increase the capacitance, and the points where the threads intersect with each other are increased to disperse the inductance. Further, in FIG. 6, the thread is macroscopically represented by a simple line, but microscopically, it is desirable that each line is bent or curved as described above.

As described above, in the sheet type sensor 1 according to the present embodiment, the first thread 17 having conductivity which is connected to the first electrode 15 and is laid along a predetermined surface in an insulated state from the surroundings, In a region other than the region surrounded by the first thread 17, a capacitor is formed in pairs with the first thread 17, is connected to the second electrode 16, and is laid along a predetermined surface in an insulated state from the surroundings. The presence or absence of a detection target on a predetermined surface is calculated based on the frequency change of charge / discharge of the capacitor formed by the second thread 18 having conductivity and the first thread 17 and the second thread 18. A capacitor is formed in which the region surrounded by the first thread 17 is one electrode and the region surrounded by the second thread 18 is the other electrode, and each region is a planar electrode. By doing so, the capacitance component can be increased and the detection sensitivity can be improved. Further, in order to detect the presence or absence of a detection target on a predetermined surface based on the frequency change of charge / discharge of the capacitor formed in the region surrounded by the first thread 17 and the region surrounded by the second thread 18. It is possible to deal with various processes by treating it as a signal having a frequency while suppressing the influence of noise as compared with the case of detecting a change in capacitance.

(Second Embodiment of the present invention)
The sheet type sensor according to the present embodiment will be described with reference to FIGS. 7 to 9. The sheet-type sensor according to the present embodiment is an extension of the function of the sheet-type sensor according to the first embodiment, and performs not only measurement based on capacitance but also detection based on pressure on the sheet body. Therefore, the object to be detected is detected with higher accuracy.

FIG. 7 is a functional block diagram showing the configuration of the sheet type sensor according to the present embodiment. The configuration different from that of FIG. 1 in the first embodiment is that the pressure measuring unit 71 is provided in addition to the capacitance measuring unit 10. The input unit 11 inputs the measurement results of the capacitance measuring unit 10 and the pressure measuring unit 71, and the arithmetic processing unit 12 performs arithmetic processing based on the measurement results. The pressure measuring unit 71 is, for example, a thin flat plate-shaped piezoelectric sensor. Since the technique of the piezoelectric sensor is general, detailed description thereof will be omitted, but the applied pressure is converted into an electric signal and output. The piezoelectric sensor as the pressure measuring unit 71 is housed in the covering body 20 together with the supporting body 19 in a state of being laminated on the supporting body 19 and used. That is, it is integrally incorporated in the sheet body of the capacitance measuring unit 10.

As another piezoelectric sensor, for example, a fibrous sensor may be used as a coaxial line, and a piezoelectric sensor using a piezoelectric element between the center line and the coated line may be used.

For example, when it is desired to detect a person with the sheet type sensor according to the first embodiment, since the human body contains a large amount of water, if there is a person on the sheet body, the dielectric constant on the sheet body changes. Along with this, the frequency changes as described in the first embodiment, and it becomes possible to determine the presence or absence of a person. However, since the change in capacitance is easily affected by noise, there is no problem in an environment that is not easily affected by noise, but in an environment that is easily affected by noise, for example, due to the influence of temperature, humidity, electromagnetic waves, etc. There is a possibility of false detection. In the present embodiment, it is possible to detect with higher accuracy by determining the presence or absence of the detection target in consideration of the correlation between the pressure waveform detected by the piezoelectric sensor and the capacitance waveform. ..

FIG. 8 is a block diagram showing a configuration of a calculation processing unit when a calculation is performed based on the measurement results of the capacitance measurement unit and the pressure measurement unit. First, the capacitance detection waveform (capacitance waveform) detected by the capacitor of the capacitance measurement unit 10 is multiplied by the pressure detection waveform (pressure waveform) detected by the piezoelectric sensor of the pressure measurement unit 71, and the multiplication result is obtained. The peak of the obtained waveform is detected. The value of the capacitance detected by the capacitor at the moment when the peak is detected is sample-held (S / H), and the value is input to the comparator as a threshold value. The input threshold value is compared with the capacitance measured by the capacitor, and when a capacitance exceeding the threshold value is detected, it is determined that the detection target is on the sheet body.

The result of the simulation with the configuration of FIG. 8 is shown in FIG. Here, the simulation result when determining the presence or absence of a person is shown. 9 (A) is the waveform of the capacitance detected by the capacitance measuring unit 10, FIG. 9 (B) is the waveform of the pressure detected by the pressure measuring unit 71, and FIG. 9 (C) is the product of the capacitance and the pressure waveform. The waveform, FIG. 9D, is a waveform showing the detection result. In FIG. 9, the waveform of the portion corresponding to R1 shows the waveform when the hand is placed on the sheet body and then released, and the waveform of the portion corresponding to R2 is the waveform when the moisture on the sheet body increases due to moisture. The waveform of the portion corresponding to R3 shows the waveform when an object other than the hand, such as metal, is placed on the sheet body.

In the simulation result of FIG. 9, the capacitance at the peak obtained by multiplication in FIG. 9 (C) is set as a threshold value, and the threshold value and the waveform of FIG. 9 (A) are compared and the waveform of FIG. 9 (D) is compared. It has become. For example, in the case of FIG. 9, the peak obtained by multiplication is at the middle timing of the rise of the capacitance in FIG. 9A, and the value of the capacitance at that timing is set as a threshold value.

As described above, since the capacitance and the pressure detection have a correlation and the detection process is performed based on the threshold value according to the environment at that time, it is possible to detect the object to be detected with extremely high accuracy.

In FIG. 9, the setting of the threshold value is described by the capacitance, but as described in the first embodiment, the capacitance may be converted into a frequency and the comparison process may be performed by the value of the frequency.

1 Sheet type sensor 10 Capacitance measurement unit 11 Input unit 12 Arithmetic processing unit 13 Output control unit 14 Power supply unit 15 First electrode 16 Second electrode 17 First thread 18 Second thread 19 Support 20 Cover 31 Capacitor 32 Constant current source 33 Comparator 34 FET circuit 35 Resistance 71 Pressure measuring unit

Claims (5)

A conductive first thread in which both ends are connected to the first electrode and laid along a predetermined surface in an insulated state from the surroundings.
In a region other than the region surrounded by the first thread, a capacitor is formed in pairs with the first thread, both ends thereof are connected to the second electrode, and the capacitor is insulated from the surroundings along the predetermined surface. The second thread with conductivity to be laid and
It is characterized by comprising a detecting means for detecting the presence or absence of a detection target object on the predetermined surface based on a frequency change of charge / discharge of a capacitor formed by the first thread and the second thread. Sheet type sensor. In the sheet type sensor according to claim 1,
A sheet-type sensor in which the first thread and the second thread are arranged in a state of being bent or curved a plurality of times, and are housed in an elastic coating body. In the sheet type sensor according to claim 1 or 2.
A sheet-type sensor in which the first thread and the second thread are laid by crossing each other with each other. In the sheet type sensor according to any one of claims 1 to 3.
A pressure detecting means for measuring the pressure applied to the predetermined surface on the predetermined surface,
A sheet type including a determination means for determining that the detection object is on the predetermined surface when a pressure waveform having a correlation with the frequency waveform of charging / discharging of the capacitor is detected by the pressure detecting means. Sensor. In the sheet type sensor according to claim 4,
A multiplication means for multiplying the signal measured by the pressure detecting means and the frequency signal obtained by the detecting means, and
A peak detection means that detects the peak value of the multiplication result of the multiplication means, and
SH means for sample-holding the output value of the frequency signal at the peak value detected by the peak detecting means, and
A sheet-type sensor including a comparison means for comparing the output value of the frequency signal of the capacitor with the output value sample-held by the SH means as a threshold value.

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