JP2007171073A - Pressure detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure detection device capable of detecting not only a dynamic pressure but also a static pressure. <P>SOLUTION: This pressure detection device is constituted of two cable-shaped pressure response means 9 for generating each voltage to a dynamic pressure, and a pressure calculation means 10 for performing measurement of each voltage and pressure calculation using each measured value. Each voltage generated in the two pressure response means 9 to application of the dynamic pressure is changed in dependence on the static pressure, and a constitution is applied, wherein the dependence is different between the two pressure response means 9, and consequently, the static pressure can be detected by comparing and calculating each voltage generated in the two pressure response means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pressure detection device that detects pressure from the outside using a flexible pressure sensitive body.

  Conventionally, there is such a pressure detection device as shown in FIG. As shown in the cross-sectional view of FIG. 12, the electrode 2 is formed on the upper and lower sides of the flexible pressure-sensitive body 1 and has a sheet-like laminated structure in which the protective layer 3 covers the surface. In FIG. 12, the direction of remanent polarization in the flexible pressure-sensitive body 1 is not shown. However, in order to form polarization by applying a high voltage between the electrodes 2, the direction is generally perpendicular to the surface of the electrode 2. Residual polarization is formed.

  As the flexible pressure-sensitive body 1, a composite in which a piezoelectric ceramic powder such as lead titanate or lead zirconate titanate is added to synthetic rubber or synthetic resin is used. The electrode 2 is configured by bonding a metal foil such as copper, aluminum, or gold to the flexible pressure-sensitive body 1 with an adhesive or the like, or depositing the above metal.

  When a dynamic pressure is applied from the outside to the pressure detection device, the flexible pressure-sensitive body 1 is distorted with acceleration, and at the same time, a voltage is generated due to the piezoelectric effect. This voltage is transmitted via the two electrodes 2. A dynamic pressure is detected by measuring.

  Moreover, there exists a cable-shaped thing as shown in FIG. 13 (for example, refer patent document 1) as a conventionally known pressure detection apparatus. 13A shows a cross section in the longitudinal direction of the cable, and FIG. 13B shows a cross section taken along the line AA in FIG. Specifically, the inner electrode 4 is formed at the center, the flexible pressure-sensitive body 1 is formed around the inner electrode 4, and the outer electrode 5 and the protective layer 3 are sequentially formed on the outer side. In FIG. 13, the direction of remanent polarization in the flexible pressure-sensitive body 1 is not shown, but normally, in order to form a polarization by applying a high voltage between the internal electrode 4 and the external electrode 5, the internal electrode 2 Thus, residual polarization is formed radially from the external electrode 5 to the external electrode 5.

  For the flexible pressure-sensitive body 1 in FIG. 13, a composite similar to the sheet-like flexible pressure-sensitive body is used. For the internal electrode 4, a linear conductive material in which a conductor such as metal is linear is used. Further, the external electrode 5 is formed by applying a conductive paint such as a silver-based rubber paint on the surface of the flexible pressure-sensitive body 1. The pressure is detected by measuring the voltage generated due to the strain accompanied by the acceleration due to the application of the dynamic pressure, as in the pressure detecting device using the sheet-like flexible pressure sensitive body.

  Here, the definition regarding the dynamic pressure used above and also a static pressure is demonstrated. In this specification, the pressure is divided into dynamic pressure and static pressure. Among these, the dynamic pressure is a pressure that is not balanced with the stress corresponding to the dynamic pressure, and as a result, is a pressure that causes acceleration to an object to which the dynamic pressure is applied.

On the other hand, the static pressure is a pressure that is completely balanced with the stress corresponding to the static pressure, and as a result, does not cause acceleration in an object to which the static pressure is applied. For this reason, the static pressure is a pressure that is not detected by the conventional technique of measuring a voltage change using the above-described flexible pressure-sensitive body pressure.
JP-A-62-230071

  However, when the conventional pressure detection device is used as a pressure sensor or a vibration sensor, it has a problem that it can detect a dynamic pressure but cannot detect a static pressure.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a pressure detection device capable of detecting a static pressure in addition to a dynamic pressure.

  In order to solve the above-described conventional problems, a pressure detection device according to the present invention includes a pressure-responsive unit including a flexible pressure-sensitive body having remanent polarization and a plurality of electrodes configured to sandwich the flexible pressure-sensitive body. Pressure calculating means for measuring a response voltage generated between the electrodes of the pressure response means and calculating a static pressure and a dynamic pressure applied to the pressure response means based on the measured response voltage. And a plurality of response voltages measured via the electrodes by the pressure calculation means have different dependencies on the static pressure applied to the pressure response means.

  With this configuration, by measuring a plurality of response voltages having different dependencies, it becomes possible to detect a static pressure in addition to a dynamic pressure applied by measurement according to the dependency.

  The pressure detection apparatus of the present invention enables detection of static pressure in addition to detection of dynamic pressure.

  According to a first aspect of the present invention, there is provided a pressure detection device comprising: a pressure response means having a flexible pressure sensitive body having remanent polarization; and a plurality of electrodes sandwiched between the flexible pressure sensitive bodies; and an electrode between the pressure response means Pressure calculating means for measuring a response voltage generated in the pressure and calculating a static pressure and a dynamic pressure applied to the pressure response means based on the measured response voltage. A plurality of response voltages measured through the electrodes have different dependencies on the static pressure applied to the pressure response means.

  Since response voltages independent from each other can be measured from a plurality of pressure detection means, an effect is obtained that enables detection of both dynamic pressure and static pressure based on this.

  The pressure detection device of the second invention has a configuration in which the pressure response means is in the form of a cable, particularly in the first invention. Because of the cable shape, the remanent polarization is usually formed radially from the center, and the pressure application direction and the polarization direction are different. For this reason, the initial distortion due to the application of static pressure is expanded, the dependence of the response voltage on the static pressure is increased, and the accuracy of detection of the static pressure is also increased. In addition, the cable shape facilitates manufacturing and increases the degree of freedom of arrangement.

  The pressure detection device according to the third invention is the pressure detection device according to the second invention, particularly in the second invention, wherein the cable-like pressure response means is in close contact with the internal electrode located at the approximate center of the cable-like pressure response means. A flexible pressure-sensitive body and an external electrode in close contact with the flexible pressure-sensitive body are included, and the internal electrode and the external electrode are used for measuring a response voltage. Since polarization is isotropically formed from the center in the cross section of the cable, the pressure detection sensitivity is also isotropic, and even if rotation or twist occurs during installation, the response voltage is stabilized and pressure detection accuracy is improved. An improving effect is obtained.

  A pressure detection device according to a fourth aspect of the invention has a configuration including a plurality of pressure response means, particularly in any one of the first to third aspects of the invention. This makes it possible to easily adjust the static pressure dependence of the response voltage by changing the polarization state for each pressure response means, making it easier to detect dynamic pressure and static pressure. The effect becomes.

  The pressure detection device according to a fifth aspect of the present invention is the pressure detection device according to any one of the first to fourth aspects, wherein the pressure response means has a plurality of internal electrodes in a state where they are not electrically connected. As a result, the pressure response means is a single body, and by combining a plurality of electrodes, the same measurement can be performed even if the number of pressure response means is reduced, and the manufacture and arrangement are facilitated. An effect is obtained.

  In the pressure detection device of the sixth invention, in particular, in any one of the first to fifth inventions, a static pressure at which at least one of the response voltages generated in the pressure response means starts rising is a static pressure at which another response voltage starts rising. It has a different configuration. As a result, the difference in magnitude between the response voltages is increased, and the effect of increasing the accuracy when calculating the static pressure can be obtained.

  In the pressure detection device of the seventh invention, in particular, in any one of the first to sixth inventions, the static pressure at which at least one of the response voltages generated in the pressure response means starts to saturate, and the static pressure at which other response voltages start to saturate. It has a configuration different from the dynamic pressure. As a result, the difference in magnitude between the response voltages is increased, and the effect of increasing the accuracy when calculating the static pressure can be obtained.

  In the pressure detection method according to the eighth invention, in particular, in any one of the first to fifth inventions, the pressure calculation means uses the intensity ratio between a plurality of response voltages, and the static pressure applied to the pressure response means and It has the structure which calculates with a dynamic pressure. This makes it possible to detect dynamic pressure and static pressure with a simple comparison.

  In the pressure detection method of the ninth invention, in particular, in any one of the first to eighth inventions, one of the plurality of response voltages measured by the pressure calculating means rises, and at least one other response voltage. In a static pressure range where the pressure does not rise, the pressure calculating means calculates the static pressure and the dynamic pressure applied to the pressure detecting means using the intensity ratio between the response voltages. As a result, the intensity ratio between the measured response voltages is increased, and the effect of increasing the accuracy in calculating the static pressure and the dynamic pressure can be obtained.

  In the pressure detection method of the tenth invention, in particular, in any one of the first to ninth inventions, one of the plurality of response voltages measured by the pressure calculating means is saturated, and at least one other response is obtained. In a static pressure range where the voltage is not saturated, the pressure calculation means calculates a static pressure and a dynamic pressure applied to the pressure detection means using the intensity ratio between the response voltages. Have. As a result, the intensity ratio between the measured response voltages is increased, and the effect of increasing the accuracy in calculating the static pressure and the dynamic pressure can be obtained.

(Embodiment 1)
FIG. 1 is a schematic diagram of a pressure detection device according to a first embodiment of the present invention. FIG. 1A is an overview of the pressure detection device according to Embodiment 1 of the present invention. It is sectional drawing of the BB line position in (a). First, the configuration and the outline of the operation will be described using this.

As shown in FIG. 1A, the pressure detection device 8 includes two pressure response means 9 and one pressure calculation unit 10. The two pressure response means 9 are installed adjacent to each other, and as shown in FIGS. 1 (a) and 1 (b), the static pressure and dynamic pressure application unit F straddling the two pressure response means 9 are provided. A static pressure is applied through the pressure transmission unit 6. When a dynamic pressure is applied in this state, a voltage change occurs in each pressure response means 9, and the pressure calculation means 10 independently measures the voltage change as a response voltage, and the dynamic pressure and the static pressure are measured. And calculate.
Below, although the case where the pressure response part 9 is comprised by the cable shape is demonstrated to an example, it can take a sheet-like form, for example, and is not specifically limited to the form.
However, the cable-like form is preferable for the following reasons.

  In the case of a cable, the remanent polarization is usually formed radially from the center in the cross-sectional shape, and the pressure application direction and the polarization direction are different. For this reason, the initial distortion due to the application of static pressure is expanded, the dependence of the response voltage on the static pressure is increased, and the accuracy of detection of the static pressure is also increased.

  In addition, since the polarization direction is formed radially from the center in the cross-sectional shape of the cable as described above, isotropic detection is possible in the same manner for pressure application from any direction. Therefore, even when the pressure response means rotates or twists during installation, the response voltage hardly changes. As a result, the degree of freedom of arrangement is increased, and stable static pressure and dynamic pressure can be detected.

  Furthermore, if it is in the form of a cable, it can be continuously produced by an extruder, and the effect of facilitating production and reducing the production cost can be obtained. Moreover, since a long thing is easy to obtain, the effect which is easy to implement pressure detection by arrange | positioning in a long distance and a wide area is also acquired.

  FIG. 2 is a cross-sectional view of the pressure detection device 8 according to the first embodiment of the present invention. 2 (a) is a diagram showing a connection relationship between the longitudinal direction of the pressure response means 9 configured in the shape of a cable and the pressure calculation means, and FIG. 2 (b) is a diagram of B in FIG. 2 (a). It is sectional drawing in the -B line position. In FIG. 2, for the sake of simplicity, only one of the two pressure response means 9 is shown, but the other cross section has the same structure.

  As shown in FIGS. 2 (a) and 2 (b), the pressure response means 9 is provided with a flexible pressure-sensitive body 11 around an internal electrode 14, an external electrode 12 on the outside thereof, and a protective layer on the outside thereof. 13 is provided. Further, a supporting and fixing portion 15 is provided at the lower portion to support and fix the whole. Of course, when sufficient strength is ensured, the protective layer 13 is not necessarily required. In the figure, Po represents a dynamic pressure from the outside, and Ps represents a static pressure. Pp represents the direction of remanent polarization formed in the flexible pressure sensitive body 11.

  The flexible pressure sensitive body 11 is configured by dispersing piezoelectric ceramic powder in synthetic rubber or synthetic resin. As the synthetic rubber or synthetic resin, a thermoplastic resin such as vinyl chloride, a thermoplastic elastomer such as chlorinated polyethylene, a vulcanized rubber such as EPDM, or the like is used. Ceramic piezoelectric materials include lead titanate, lead zirconate, lead zirconate titanate, barium titanate, bismuth sodium sodium titanate, alkali niobate and other compounds having a perovskite structure, compounds having a bismuth layer structure, tungsten A ceramic material that exhibits piezoelectricity such as a compound having a bronze structure is used.

  The protective layer 13 is made of a synthetic rubber or a synthetic resin used for the flexible pressure-sensitive body 11, and is made of at least one of a thermoplastic resin, a thermoplastic elastomer, and a vulcanized rubber, but wear and charge leakage are reduced. If it is, it is not particularly necessary.

  As the external electrode 12, a wire material such as C, Pt, Au, Pd, Ag, Cu, Al, Ni, stainless steel, or the like obtained by rolling a wire material into a flat tape shape or the like is used. Alternatively, if the tape-like polymer film laminated with the metal wire or the tape-like wire is used, a more flexible external electrode can be obtained.

  As the internal electrode 14, one or a plurality of fine metal wires used in the external electrode 12, a plurality of fibers such as polyester wound around the metal wire, or the like is used.

  Further, regarding the flexible pressure-sensitive body 11, the protective layer 13, and the external electrode 12, the same can be applied to the following embodiments.

  Next, a general example will be described regarding the manufacturing method of the cable-like pressure response means.

  First, a piezoelectric ceramic powder and a thermoplastic elastomer as a synthetic rubber or a synthetic resin are kneaded to form a composite. Next, this composite is extruded together with the internal electrode using an extruder, thereby obtaining a cable in which the flexible pressure-sensitive body 1 made of the composite is formed around the internal electrode 14. Further, a polarization electrode covering the periphery of the cable is prepared, and by applying a voltage between the external electrode and the internal electrode 14 in the cable, an electrode is formed radially from the internal electrode, and a ceramic piezoelectric element is formed in a corresponding direction. Residual polarization in the body is formed. Further, after removing the electrode for polarization, the external electrode 12 is formed by winding a tape-shaped metal wire, a tape-shaped metal, or a tape laminated with a tape-shaped metal and a tape-shaped polymer around the cable. To do. Next, a pressure responsive means is formed by extruding a thermoplastic resin, a thermoplastic elastomer, an unvulcanized rubber, etc. by an extruder, and forming a protective layer 13 for the cable, centering on the cable on which the external electrode 12 is formed. Is obtained. On the other hand, polarization can also be performed by applying a voltage between the external electrode 12 and the internal electrode 14 after the external electrode 12 is formed. Unvulcanized rubber can be vulcanized after extrusion.

About the pressure detection apparatus 8 comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.
First, a description will be given with reference to FIG. A static load Ps is applied to the flexible pressure sensitive body 11 via the pressure transmission unit 6, the protective layer 13, and the external electrode 12. As a result, the flexible pressure-sensitive body 11 is initially strained in the direction of the static pressure Ps, and when a dynamic pressure Po from the outside is further applied, a voltage is generated in the flexible pressure-sensitive body 11 due to the piezoelectric effect. To do. The response voltage generated at this time increases as the static pressure Ps increases, as will be described later. The mechanism for increasing the response voltage is not necessarily clear, but is considered to be due to the initial strain due to the static load Ps and the accompanying change in the direction and magnitude of the remanent polarization Pp and the dielectric constant.

  Next, the dependency of the response voltage generated in the pressure response means 9 on the dynamic pressure and the dependency on the static pressure will be described.

  The measurement of the dependence of the response voltage was performed using a vibrator. First, an indenter having a certain area is pressed against the surface of the pressure response means 9 to apply a static pressure Ps having a certain magnitude. Further, the dynamic pressure Po is applied by vibrating the indenter up and down at a constant frequency with the pressed position as a reference. At this time, the static pressure Ps is obtained by dividing the load applied to the indenter before vibration by the load cell by the indenter area. The dynamic pressure Po is obtained by measuring the maximum load during vibration with a load cell and dividing the load by the indenter area. FIG. 3 and FIG. 4 show the results qualitatively.

  First, a description will be given with reference to FIG. 3 showing the dynamic pressure dependence of the response voltage under a constant static pressure Ps. Specifically, by applying a constant static pressure Ps to the two pressure response means 9 in the first embodiment of the present invention shown in FIG. 3 is a diagram qualitatively showing a voltage generated in the sexual pressure sensitive body 11 as a response voltage measured by the pressure calculation means 10 via the internal electrode 14 and the external electrode 12. FIG. In FIG. 3, the response voltage of one pressure response means 9 is shown as a representative example.

  The response voltage increases in proportion to the dynamic pressure until the dynamic pressure reaches P ho, but the dynamic pressure is higher than the point ho in FIG. 3 where the dynamic pressure is P ho and the response voltage V ho. When it gets higher, it begins to saturate. This is considered to be because when the strain due to the dynamic pressure increases, the strain deviates from the elastic region, and the change in strain with respect to the dynamic pressure decreases.

  Thus, under the condition of a constant static pressure, the response voltage increases in proportion to the dynamic pressure, and the response voltage saturates above a certain pressure. Therefore, if the static pressure is known, the dynamic pressure can be calculated from the measured response voltage from the dynamic pressure dependence (for example, FIG. 3) of the response voltage under the static pressure.

  On the other hand, FIG. 4 shows the static pressure dependence of the response voltage under a constant dynamic pressure. Specifically, by applying a constant dynamic pressure to the two pressure response means 9 in the first embodiment of the present invention shown in FIG. 1 and further changing the static pressure Ps, a flexible feeling is obtained. FIG. 3 is a diagram qualitatively showing a voltage generated in the pressure body 11 as a response voltage measured by the pressure calculation means 10 via the internal electrode 14 and the external electrode 12. FIG. 4 also shows the response voltage of one pressure response means 9 as a representative example, as in FIG.

The static pressure Ps P _i smaller area in FIG. 4, the response voltage takes a value close to a constant value V _b is not zero. This is because the external electrode 12 and the protective layer 13 on the outside of the flexible pressure sensing body 11 disperse the static load Ps. It is thought that this is because the acting ratio is small.

Static pressure Ps, in the region of P b from P _i, substantially in proportion to the static load Ps applied thereto increases corresponding response voltage and the response voltage increases from V _b to V _b. Furthermore the static pressure Ps, increasing the response voltage increases than P _B will indicate a saturation tendency. This is considered to be because the linearity between the static load Ps and the initial strain generated in the flexible pressure-sensitive body 11 is lost.
Thus, the response voltage increases monotonously with respect to the static pressure under a certain dynamic pressure Po. Therefore, if the dynamic pressure Po is known, the static pressure Ps can be calculated from the response voltage.

  As described above, the static pressure and the dynamic pressure have a relationship in which one can be determined if one is known, but cannot be determined by only one response voltage. In the present embodiment, this is solved by measuring two response voltages having different static pressure dependencies using two pressure response means. This will be described below.

  FIG. 5 shows the static pressure Ps dependence of the response voltage V generated by applying the dynamic pressure Po to the two pressure response means 9 connected to the pressure calculation means 10 in FIG. . Here, assuming that the two pressure response means 9 are the pressure response means 1 and the pressure response means 2, respectively, and the response voltages corresponding to the pressure response means 1 and 2 are V1 and V2, respectively, as shown in FIG. The response means 1 and the pressure response means 2 are different in the dependence of the response voltage on the static pressure Ps. The pressure response means 1 rises with a small static pressure P and the pressure rises even after the response voltage rises. Compared with the response means 2, it can be seen that it increases with a large inclination.

  Further, as the static pressure increases from P A to P B, the response voltage ratio (V1 / V2) increases monotonously. Therefore, one (V1 / V2) corresponds to one static pressure. Therefore, the static pressure can be determined by determining (V1 / V2). As is clear from FIG. 3, each response voltage is proportional to the dynamic pressure unless the response voltage is saturated with respect to the dynamic pressure. Therefore, (V1 / V2) is the magnitude of the dynamic pressure. Regardless, it has a constant value. For this reason, the static pressure can be uniquely determined even if the absolute value of the dynamic pressure is not known.

  If the static pressure can be obtained from (V1 / V2) by the above procedure, the dynamic pressure dependence of the response voltage under a constant static pressure (FIG. 3) The pressure can be determined.

  Finally, the procedure for calculating the static pressure Ps and the dynamic pressure P0 from the outside by the pressure detection apparatus described with reference to FIG. 5 as described above will be described with reference to FIG.

  First, response voltages V1 (for example, V1a) and V2 (for example, V2a) corresponding to the two pressure response units 1 and 2 are measured by the pressure calculation unit (ST1). Next, the response voltage ratio V1 / V2 (for example, V1a / V2a) is calculated by the pressure calculating means (ST2). Subsequently, a static pressure Ps (for example, Psa) corresponding to the response voltage ratio V1 / V2 (for example, V1a / V2a) is read from the memory by using the pressure calculating means (ST3). Then, the static pressure Ps (for example, Psa) is output (ST4). Further, the dynamic pressure P0 (for example, P0a) corresponding to V1 (for example, V1a) or V2 (for example, V2a) at the time of the static pressure Ps (for example, Psa) is read from the memory using the pressure calculation means (ST5). Finally, the dynamic pressure P0 (for example, P0a) is output.

  However, the relationship between V1 / V2 and Ps, and the relationship between V1, V2, and P0 when the static pressure Ps = Psa can be obtained experimentally in advance and recorded in the memory.

  In ST5, when the corresponding dynamic pressure P0 is derived from the response voltage V1 or V2, the average value of the dynamic pressure derived from both can be used. It is possible to improve the accuracy of the dynamic pressure derived by using the average value.

  Further, when outputting the static pressure Ps and the dynamic pressure P0, a suitable output device such as a speaker or a monitor can be selected as necessary.

  As described above, in the present embodiment, the two pressure response means are used to measure the two response voltages having different static pressure dependencies, thereby detecting the static pressure in addition to the dynamic pressure. It becomes possible.

  By detecting the dynamic pressure and the static pressure at the same time, in addition to the presence or absence of a nursing bed, chair, vehicle seat, etc., the weight of the person who is there or the weight of the person being placed is detected. Is possible. Furthermore, it can be suitably used for a wide range of uses such as the detection of the number of persons based on the movement of a person who is in bed or sitting, the number of persons based on the state of heartbeat, psychology, health condition, and the presence or absence of sleep.

  In FIG. 1, a cable-like configuration is shown as the flexible pressure-sensitive body 11, the internal electrode 14, the external electrode 12, and the protective layer 13, but this cable-like configuration is as shown in FIG. The cross section perpendicular to the longitudinal direction is substantially elliptical, and the area when the static pressure Ps is applied is reduced. Therefore, it is easy to increase the size of the static pressure Ps converted per unit area. For this reason, the initial strain generated in the flexible pressure-sensitive body 11 is further enlarged, the response voltage when the dynamic pressure Po is applied from the outside is increased, and as a result, the effect of accurately detecting the pressure is obtained.

  In addition to the cable-like configuration, the same effect can be obtained as long as the area to which the static pressure Ps is applied is small.

  A cable-like configuration is preferable because mass production can be easily performed by an extruder or the like.

Further, when the flexible pressure-sensitive body 11, the internal electrode 14, the external electrode 12, and the protective layer 13 have a cable-like configuration, the initial polarization usually causes a high voltage between the internal electrode 14 and the external electrode 12. The direction is radial from the internal electrode 14 because it is applied. For radial remanent polarization, the static pressure Ps is usually applied in the vertical direction, and since these directions do not coincide, the change in the remanent polarization direction also increases. As a result, when the dynamic pressure Po is applied from the outside, the voltage generated in the flexible pressure sensitive body becomes high, and it is preferable because the pressure can be detected with high accuracy.

  Even if a cable-like configuration is not used, the same effect can be obtained when the direction of the remanent polarization formed initially is different from the direction of the static load Ps.

  In the present embodiment, the response voltages corresponding to the two pressure response means 9 need to exhibit different static load dependencies, which are adjusted by the strength of polarization, the elastic modulus of the outer skin, the shape, etc. Is possible. For example, by increasing the polarization, the inclination corresponding to FIG. 4 can be increased, and by increasing the elastic modulus of the protective layer 13, the inclination can be reduced and the static pressure at which the response voltage rises can be increased. Become.

  Further, in the present embodiment, the number of pressure response means 9 is two, but by increasing this number, an effect of improving the pressure detection accuracy and expanding the detected pressure range can be obtained.

  The materials used in this embodiment are also preferably used in the following embodiments.

(Embodiment 2)
FIG. 7 shows the dependence of the response voltage on the static pressure Ps under a certain dynamic pressure Po for the two pressure response means 9 of the pressure detection device 10 in the present embodiment. As shown in FIG. 1, the two pressure response means 9 are arranged adjacent to each other and connected to the pressure calculation means 10. In addition, the response voltage of FIG. 7 is obtained by the pressure calculation means 10 when the static pressure Ps and the dynamic pressure P0 are applied using the vibration exciter in such an arrangement as in the first embodiment. It shows the measured value qualitatively.

  As shown in FIG. 7, the pressure response means 1 and the pressure response means 2 are different in the static pressure Ps dependency of the response voltage V as in the first embodiment, but different from FIG. 5 in the first embodiment. The response voltage of the pressure response means 1 is saturated at a low static pressure P and the response voltage corresponding to the pressure response means 1 is wide in a range from when the response voltage corresponding to the pressure response means 2 rises to saturation. It is a point that is in a saturated state. Therefore, the response voltage ratio (V1 / V2) between the pressure response means 1 and the pressure response means 2 shown in FIG. 7 is compared with FIG. 5 while the static pressure Ps increases from P to P. And change greatly. This means that the accuracy of calculating the static pressure Ps from the response voltage ratio (V1 / V2) is increased.

  As described above, when the pressure detection device 8 includes two pressure response means 9 having different static pressure Ps dependencies, after one response voltage V is saturated and the other response voltage V rises. By calculating the pressure by the pressure calculation means 10 within the range of the static pressure Ps until the saturation starts, the static pressure Ps and the dynamic pressure P0 can be detected with high accuracy.

(Embodiment 3)
FIG. 8 shows the dependence of the response voltage V on the static pressure Ps with respect to a constant dynamic pressure Po for the two pressure response means 9 of the pressure detection device 8 in the present embodiment. As shown in FIG. 1, the two pressure response means 9 are arranged adjacent to each other and connected to the pressure calculation means 10. The response voltage shown in FIG. 8 is the value measured by the pressure calculating means when applying static pressure and dynamic pressure using a vibration exciter in such an arrangement, as in the first embodiment. It is a qualitative representation.

As shown in FIG. 8, in the pressure response means 1 and the pressure response means 2, the static pressure Ps of the response voltage V
Although the dependency is different, the difference from FIG. 5 of the first embodiment is that the response voltage V2 corresponding to the pressure response means 2 rises slowly and the response voltage V1 corresponding to the pressure response means 1 starts to be saturated. It is a point where it finally begins to rise at a static pressure P slightly lower than the pressure P.

  In this case, (V1 / V2) increases as the static pressure Ps increases. In particular, the static pressure Ps increases monotonously when the static pressure Ps is greater than or equal to Pa and less than or equal to P, and compared with the first embodiment. The change is great.

  As described above, the response voltage ratio (V1 / V2) between the pressure response means 1 and the pressure response means 2 shown in FIG. 6 is shown in FIG. 5 while the static pressure Ps increases from P to P. Compared to a large change. This means that the accuracy of calculating the static pressure from the response voltage ratio (V1 / V2) increases.

(Embodiment 4)
FIG. 9 is an external view of the pressure detection device 8 in the present embodiment. First, the configuration and the outline of the operation will be described using this.

  As shown in FIG. 9, unlike the first to third embodiments, the pressure detection device 8 includes one pressure response means 9 and one pressure calculation unit 10. The operations of the pressure response means 9 and the pressure calculation means 10 are basically the same as those of the first to third embodiments. However, in this embodiment, two types of response voltages V are included in one pressure response means 9. Different points occur. Hereinafter, the structure and operation will be described in more detail with reference to FIG.

  FIG. 10 is a cross-sectional view of the pressure detection device 8 in the present embodiment. 10 (a) is a diagram showing the connection relationship between the longitudinal direction of the pressure response means 9 configured in the shape of a cable and the pressure calculation means 10, and FIG. 10 (b) is a diagram of (a). It is sectional drawing in CC line position.

  As shown in FIGS. 10A and 10B, as in FIG. 2 of the first embodiment, the pressure response means 9 is provided with a flexible pressure-sensitive body 11 around the internal electrode 14, and on the outside thereof. And one cable-like pressure response means 9 provided with an external electrode 12. The difference from FIG. 1 is that there are two internal electrodes 14. The response voltage V generated between each of them and the external electrode 12 is independently measured by the pressure calculating means 10, and the static pressure Ps and the dynamic pressure P0 are calculated based on the measured values.

  Here, the static pressure Ps dependence of the response voltage in the present embodiment is expressed in FIG. 8 as in the first embodiment. Further, the response voltage V1 in FIG. 8 is a voltage generated between the left internal electrode 14 and the external electrode 12 in FIG. 10B, and the response voltage V2 is the right internal electrode in FIG. 10B. 14 and a voltage generated between the external electrode 12 and the external electrode 12.

  By the way, in this embodiment, in order to make a difference in the static pressure Ps dependence of the two response voltages V1 and V2, there are two structural features. One of them is that the remanent polarization Pp formed in the flexible pressure-sensitive body 11 is large in the vicinity of the left internal electrode 14 while it is small in the vicinity of the right internal electrode 14. is there. Another feature is that the thickness of the pressure transmission unit 16 formed on the protective layer 13 and transmitting the static pressure Ps and the dynamic pressure Po to the flexible pressure sensitive body 11 is thick on the left side and thin on the right side. It is a point. Further, the protective layer 13 is not an integral structure, but has a structure that is divided into two on the right side and the left side, as shown in FIG.

Because of the first feature, the response voltage V1 corresponding to the left internal electrode 14 increases, and the slope in FIG. 8 also increases. At the same time, the response voltage V2 corresponding to the right internal electrode 14 is reduced, and the inclination in FIG. 8 is also reduced. Further, due to the second feature, the static pressure Ps applied to the right internal electrode 14 is reduced. As a result, in the right internal electrode 14, the corresponding response voltage V2 rises with a larger static pressure Ps. In this way, the dependence of the response voltages V1 and V2 on the static pressure Ps as shown in FIG. 8 is realized.

  As described above, in the present embodiment, in addition to the detection of the dynamic pressure P0, in addition to the detection of the dynamic pressure P0, as in the first to third embodiments using a plurality of pressure response means 9, a single pressure response means 9 is used. The pressure Ps can be detected. Since the number of the pressure response means 9 is changed from a plurality to one, an effect of facilitating manufacture and arrangement can be obtained.

  Moreover, the pressure transmission part 16 can also be formed by adhering to the protective layer 13, or can be integrated with the protective layer and formed of the same material.

(Embodiment 5)
The external view of the pressure detection device 8 in the present embodiment is shown in FIG. 9 as in the fourth embodiment.

  As shown in FIG. 9, the pressure detection device 8 includes one pressure response means 9 and one pressure calculation unit 10 as in the fourth embodiment.

  FIG. 12 is a cross-sectional view of the pressure detection device in the present embodiment. 12A is a diagram showing a longitudinal sectional view of the pressure response means 9 configured in the shape of a cable and the connection relationship between the pressure calculation means 10 and FIG. It is sectional drawing in the DD line position of figure (a).

  The present embodiment is the same as the fourth embodiment in that there is only one pressure response means 9, but the fourth embodiment is different from the fourth embodiment in that one pressure response means 9 is a flexible pressure sensitive body. 11 is divided into two. For each of them, the internal electrode 14 and the external electrode 12 exist independently, and two response voltages generated between the electrodes are independently measured by the pressure calculating means, and based on the measured values. Static pressure and dynamic pressure are detected.

  Here, the static pressure Ps dependence of the response voltage V of the present embodiment is qualitatively expressed in FIG. 8 as in the fourth embodiment. The response voltage V1 in FIG. 8 is a voltage generated between the left internal electrode 14 and the external electrode 12 in FIG. 11B, and the response voltage V2 is the right internal electrode in FIG. 9B. 14 and a voltage generated between the external electrode 12 and the external electrode 12.

  By the way, in this embodiment, in order to make a difference in the dependency of the two response voltages on the static pressure Ps, there are the same two structural features as in the fourth embodiment. One of them is a difference in the magnitude of remanent polarization formed in the left and right flexible pressure-sensitive bodies 11, and another feature is a difference in thickness between the left and right of the pressure transmission unit 6. As in the fourth embodiment, the response voltage V1> V2 is satisfied due to the first feature. In addition, due to the second feature, the relationship P i <P is established for the static pressure at which the response voltage rises. Thus, as shown in FIG. 8 qualitatively, the response voltages V1 and V2 have different static pressure Ps dependencies. For this reason, the static pressure Ps and the dynamic pressure P0 can be detected by the same procedure as in the first embodiment.

  Thus, in this embodiment, the dynamic pressure P0 and the static pressure Ps are obtained by using one pressure response means 9 as in the first to third embodiments using a plurality of pressure response means 9. Detection is also possible. Further, since only one pressure response means 9 is required as in the fourth embodiment, an effect of facilitating manufacture and arrangement can be obtained.

  By the way, in particular, the external electrode 12 is formed separately for the two internal electrodes 14 and the flexible pressure-sensitive body 11, and after the polarization operation is performed separately, the common protective layer 13 is finally formed. I can do it. On the other hand, in Embodiment 4, since there is one external electrode 12 for two internal electrodes 14, the polarization operation around the two internal electrodes 14 cannot be performed completely independently. Therefore, in the present embodiment, it is possible to introduce the remanent polarization Pp with higher independence compared to the fourth embodiment. This means that V1 and V2 can be determined independently without affecting each other, and the difference between V1 and V2 can be increased and V1 / V2 can be increased. As a result, it is possible to obtain an effect that the static pressure Ps and the dynamic pressure P0 can be detected with higher accuracy.

  Moreover, the pressure transmission part 16 can also be formed by adhering to the protective layer 13, or can be integrated with the protective layer and formed of the same material.

  As described above, the pressure detection device according to the present invention enables detection of static pressure in addition to dynamic pressure with a simple configuration. For this reason, applications that detect and determine both static pressure applied when a person or object is placed and dynamic pressure generated when a person or object moves, such as a nursing bed, chair, or vehicle seat The present invention can be applied to a wide range of uses such as the presence / absence of seating or seating, the movement of a person sitting or sitting, and the number of people, the location and the state based on them.

(A) Overview of pressure detection device according to Embodiment 1 of the present invention (b) Cross-sectional view of the pressure detection device taken along line BB in (a) (A) The cross-sectional view in the longitudinal direction of the pressure response means of the pressure detection device according to Embodiment 1 of the present invention and the diagram showing the connection relationship between the pressure calculation means (b) The position of the pressure detection device BB line position Cross section The graph which expressed the dynamic pressure dependence of the response voltage in Embodiment 1 of this invention qualitatively A graph qualitatively showing the static pressure dependence of the response voltage in the first embodiment of the present invention The graph which expressed qualitatively the relationship of the static pressure dependence of two response voltages in Embodiment 1 of this invention The flowchart which showed the procedure of calculation of the static pressure and the dynamic pressure in Embodiment 1 of this invention The graph which expressed qualitatively the static pressure dependence of the two response voltages in Embodiment 2 of this invention Graph showing qualitatively the static pressure dependence of the two response voltages in Embodiments 3 and 4 of the present invention The schematic diagram showing the structure of the pressure detection apparatus of Embodiment 4 of this invention (A) Longitudinal sectional view of the pressure detection device in Embodiment 4 of the present invention (b) Cross sectional view of the pressure detection device CC line position (A) Longitudinal sectional view of the pressure detection device in Embodiment 5 of the present invention (b) Cross sectional view of the pressure detection device DD line position Sectional view of a conventional sheet-shaped pressure sensor (A) Sectional view of a conventional cable-shaped pressure sensing element (b) AA sectional view of the pressure sensing element

Explanation of symbols

DESCRIPTION OF SYMBOLS 6 Support fixing | fixed part 7 Pressure transmission part 8 Pressure detection apparatus 9 Pressure response means 10 Pressure calculation means 11 Flexible pressure sensitive body 12 External electrode 13 Protective layer 14 Internal electrode

Claims (10)

A pressure response means having a flexible pressure-sensitive body having remanent polarization and a plurality of electrodes sandwiched between the flexible pressure-sensitive bodies, and measuring a response voltage generated between the electrodes of the pressure response means, Pressure calculating means for calculating a static pressure and a dynamic pressure applied to the pressure response means based on the measured response voltage, and a plurality of responses measured via the electrodes by the pressure calculating means A pressure sensing device wherein the voltage has a different dependence on the static pressure applied to the pressure response means. The pressure detection device according to claim 1, wherein the pressure response means has a cable shape. The cable-like pressure response means includes an internal electrode located at a substantially central portion of the cable-like pressure response means, a flexible pressure sensitive body in close contact with the internal electrode, and an external electrode in close contact with the flexible pressure sensitive body. The pressure detection device according to claim 2, wherein the internal electrode and the external electrode are used for response voltage measurement. 4. The pressure detecting device according to claim 1, comprising a plurality of pressure response means. The pressure detection device according to any one of claims 1 to 4, wherein the pressure response means has a plurality of internal electrodes. 6. The pressure detection device according to claim 1, wherein a static pressure at which at least one of response voltages generated in the pressure response means starts rising is different from a static pressure at which other response voltages start rising. The pressure detection device according to claim 1, wherein a static pressure at which at least one of response voltages generated in the pressure response means starts to saturate is different from a static pressure at which other response voltages start to saturate. The pressure detection method according to any one of claims 1 to 7, wherein the pressure calculation means calculates a static pressure and a dynamic pressure applied to the pressure response means using an intensity ratio between a plurality of response voltages. . Among the plurality of response voltages measured by the pressure calculation means, in the static pressure range where one response voltage rises and at least the other response voltage does not rise, the pressure calculation means The pressure detection method according to any one of claims 1 to 8, wherein a static pressure and a dynamic pressure applied to the pressure detection means are calculated using the intensity ratio. In a static pressure range in which one response voltage is saturated and at least one other response voltage is not saturated among a plurality of response voltages measured by the pressure calculation unit, the pressure calculation unit includes the response voltage. The pressure detection method as described in any one of Claim 1 to 8 which calculates the static pressure and dynamic pressure which are applied to a pressure detection means using the intensity ratio between.

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