JP2005208043A - Pressure sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor device capable of contributing to miniaturization and improvement in productivity of pressure sensor devices by providing an acceleration detecting element on a piezoelectric substrate as an integrated unit with a pressure detection part. <P>SOLUTION: At least one end side of the piezoelectric substrate 10 is extended outwardly beyond a fixing position to a supporting substrate 30 with it separated from the upper surface of the supporting substrate 30, and the acceleration detecting element 21 is formed on the extension part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pressure sensor device that detects a change in pressure and transmits a predetermined electrical signal.

  2. Description of the Related Art Conventionally, pressure sensors that detect fluctuations in pressure applied to a sensor unit as changes in oscillation frequency are known as pressure sensors that detect fluctuations in pressure of gas or liquid.

  As such a conventional pressure sensor 100, for example, as shown in FIG. 12, a surface acoustic wave element 103 formed in a thin portion 102 of a piezoelectric substrate 101 and a surface acoustic wave element 103 are connected via a wiring portion 105. What is comprised with the oscillator 106 is known (for example, refer patent document 1).

  In such a pressure sensor 100, the surface acoustic wave element 103 constituting the sensor portion is formed in the thin portion 102 of the piezoelectric substrate 101. When the pressure is received, the thin portion is distorted, and the elastic constant of the portion is determined. The propagation speed of the surface acoustic wave is changed by the change, and the interval between the electrodes 104 of the surface acoustic wave element 103 is changed. The resonance frequency of the surface acoustic wave element 103 changes due to each action. Based on the change in the resonance frequency of the surface acoustic wave element 103, an electric signal is transmitted by an oscillation circuit incorporated in the oscillator 106. The pressure is detected by monitoring the electrical signal thus obtained.

  Further, when the above pressure sensor 100 is used as a tire pressure sensor for in-vehicle use, for example, power necessary for operating the oscillation circuit of the pressure sensor is supplied from a power supply means such as a battery built in the tire. It has come to be. In this case, if power is constantly supplied from the power source to the oscillation circuit, there is a problem that power consumption increases and the life of the battery becomes short.

  Therefore, in order to reduce power consumption, by detecting the acceleration generated by the rotation of the tire, power is supplied to the oscillation circuit only when the vehicle is traveling at a certain speed or more, There is known a pressure sensor device that suppresses power consumption of an oscillation circuit by turning off power supply to the oscillation circuit when the vehicle is stopped or when the vehicle speed is below a certain level. (For example, refer to Patent Document 2).

Such a pressure sensor device controls the power supply from the battery to the oscillation circuit based on an acceleration detection element including a piezoelectric substrate and electrodes attached to the piezoelectric substrate, and an electric signal from the acceleration detection element. It is formed by connecting an acceleration sensor provided with a power supply control circuit to the pressure sensor 100 through a wiring portion.
Japanese Patent Publication No. 5-82537 JP 2002-264618 A

  However, the conventional pressure sensor device described above has a problem that the pressure sensor 100 and the acceleration sensor are separately provided, so that the unit shape becomes large and it is difficult to incorporate the unit into the tire. .

  In addition, the above-described conventional pressure sensor device has a problem in that the assembly work of the pressure sensor 100 and the acceleration sensor is required, leading to a decrease in productivity.

  The present invention has been devised in view of the above-mentioned problems, and its purpose is to provide a pressure sensor device that is miniaturized and improved in productivity by integrating an acceleration detection element on a pressure detection unit and a piezoelectric substrate. An object of the present invention is to provide a pressure sensor device capable of

A pressure sensor device of the present invention includes a piezoelectric substrate that includes a pressure detection unit and detects pressure fluctuations by deformation of the pressure detection unit;
A support substrate on which the piezoelectric substrate is mounted / fixed, an oscillation circuit that transmits an electric signal of a predetermined frequency based on pressure variation information from the pressure detection unit, and acceleration variation detected by deformation due to application of acceleration An acceleration detection circuit for transmitting a predetermined electrical signal based on acceleration fluctuation information from the acceleration detection element, a power supply means for supplying power to the oscillation circuit, and an oscillation from the power supply means A power supply control circuit for controlling power supply to the circuit, wherein at least one end side of the piezoelectric substrate is separated from the upper surface of the support substrate from a fixed portion with respect to the support substrate. And the acceleration detecting element is formed in the extending portion.

  The pressure sensor device of the present invention is characterized in that both the pressure detection unit and the acceleration detection element are formed by surface acoustic wave elements including an interdigital transducer.

  Furthermore, the pressure sensor device of the present invention is characterized in that the piezoelectric substrate is placed on the support substrate via a spacer.

  In the pressure sensor device according to the present invention, preferably, an antenna element that is electrically connected to the oscillation circuit is provided on the upper surface of the support substrate and / or the lower surface of the pressure substrate. Is.

  Furthermore, in the pressure sensor device of the present invention, an amplifier that amplifies an electric signal from the transmission circuit is connected between the antenna element and the oscillation circuit, and power is supplied from the power feeding means to the amplifier. Control is performed by a power supply control circuit.

  According to the pressure sensor device of the present invention, at least one end side of the piezoelectric substrate is separated from the upper surface of the support substrate so as to extend outside the fixed portion with respect to the support substrate, and the acceleration detecting element is formed in the extension portion. Since the pressure detection unit and acceleration detection element are integrated on the piezoelectric substrate, there is no need to prepare a separate substrate for the acceleration detection element, reducing the number of parts and downsizing the pressure sensor device In addition, the weight can be reduced.

  In addition, according to the pressure sensor device of the present invention, both the pressure detection unit and the acceleration detection element are formed by surface acoustic wave elements including an interdigital transducer, so that the pressure detection unit and the acceleration detection element are manufactured in the same manufacturing process. Since both can be formed simultaneously, the manufacturing process can be shortened and the productivity can be improved.

  Furthermore, according to the pressure sensor device of the present invention, since the piezoelectric substrate is placed on the support substrate via the spacer, a predetermined interval is provided between the piezoelectric substrate and the support substrate. When the substrate is mounted on the support substrate, a predetermined interval can be provided between the acceleration detection unit and the upper surface of the support substrate.

  Furthermore, according to the pressure sensor device of the present invention, an oscillation signal output from the oscillation circuit is provided by providing an antenna element electrically connected to the oscillation circuit on the upper surface of the support substrate and / or the lower surface of the pressure substrate. Can be wirelessly transmitted to another device having a receiving circuit, and pressure information can be obtained even at a location distant from the pressure sensor device.

  Furthermore, according to the pressure sensor device of the present invention, an amplifier for amplifying an electric signal from the oscillation circuit is connected between the antenna element and the oscillation circuit, and power supply from the power supply means to the amplifier is a power supply control circuit. Therefore, it is possible to increase the output level of the oscillation signal output from the oscillation circuit so that it can be wirelessly transmitted to other devices having the reception circuit more reliably. Power consumption can be reduced and the power supply can be made longer.

  Hereinafter, a pressure sensor device of the present invention will be described in detail with reference to the drawings.

  1 is a cross-sectional view of a pressure sensor device according to a first embodiment of the present invention, FIG. 2 is a plan view showing a lower surface of a piezoelectric substrate used in the pressure sensor device of FIG. 1, and FIG. 5 is a pressure sensor device of FIG. FIG. 6 is a block circuit diagram of the pressure sensor device of FIG. 1.

  The pressure sensor device 1 shown in these drawings is generally composed of a piezoelectric substrate 10, a pressure detection unit 11, an acceleration detection element 21, and a support substrate 30.

  The piezoelectric substrate 10 includes a pressure detection unit 11 that detects a change in pressure applied to the piezoelectric substrate 10, and an acceleration detection element 21 that detects a change in acceleration applied to the piezoelectric substrate 10.

  The material of the piezoelectric substrate 10 is preferably one that can be deformed relatively easily when subjected to external pressure (pressure P from above in FIG. 1) and acceleration (acceleration G from above in FIG. 1). For example, piezoelectric materials such as quartz, lithium niobate, and lithium tantalate are preferably used.

  The pressure detection unit 11 formed on the piezoelectric substrate 10 includes a surface acoustic wave element 17 including, for example, a piezoelectric body 15 and an interdigital transducer (hereinafter abbreviated as IDT electrode) 16. The IDT electrode 16 is electrically connected to the electrode pad 12 through the extraction electrode 13.

  As a material of the piezoelectric body 15 forming the surface acoustic wave element 17, for example, a material similar to that of the piezoelectric substrate 10, that is, a piezoelectric material such as quartz, lithium niobate, lithium tantalate, or the like is used. The IDT electrode 16 is formed on the surface by patterning a metal material such as aluminum or gold using a conventionally well-known thin film forming technique such as sputtering or vapor deposition, a photolithography technique, etc., and having a thickness of about 2000 mm. The

  Similarly to the IDT electrode 16 described above, the electrode pad 12 and the extraction electrode 13 can be obtained by patterning a metal material such as aluminum or gold by a thin film forming technique or a photolithography technique. The electrode pad 12 is preferably formed with a large film thickness in order to improve the adhesion strength to the base.

  Around the pressure detection unit 11, the electrode pad 12, and the extraction electrode 13, a fixing region 14 is provided as a fixing portion for the piezoelectric substrate 10 to the support substrate 30.

  Such a piezoelectric substrate 10 is placed and fixed on the support substrate 30 via a spacer 50 bonded to the fixing region 14.

  As the characteristics required for the support substrate 30, it is important that the support substrate 30 is hardly deformed by an external pressure and has sufficient strength, and examples of the material thereof include a glass-ceramic material. A multilayer circuit board using the ceramic material is used.

  On the upper surface of the support substrate 30, an oscillation electronic component 40a, an acceleration detection electronic component 40b, a power feeding control electronic component 40c, an antenna element 95, an amplifier 91, and the like, which will be described later, are mounted.

  A connection pad 18 connected to the oscillation electronic component 40a is formed around the oscillation electronic component 40a. The connection pad 18 is electrically connected to the electrode pad 12 via the conductive bonding material 60. ing.

  Further, a fixing region 32 is provided around the oscillation electronic component 40a and the connection pad 18 so as to face the fixing region 14 described above, and the spacer 50 is joined to the fixing region 32. .

  Further, a plurality of external terminal electrodes 33 are formed on the lower surface of the support substrate 30, and these external terminal electrodes 33 are connected to the upper surface of the support substrate 30 via the internal wiring patterns 34, via-hole conductors 35, and the like. Are electrically connected to the oscillation electronic component 40a. In addition, when a power source such as a battery is provided separately from the pressure sensor device 1, power is supplied from the power source to the oscillation circuit by electrically connecting the power source and the external terminal electrode 33 via a wiring or the like. It has come to be. When the power source is provided separately from the pressure sensor device 1, the power feeding means in the present invention refers to the external terminal electrode 33 that is electrically connected to the power source.

  Such a support substrate 30 is, for example, a conventionally known green sheet laminating method, specifically, a plurality of green sheets on which a conductive paste to be used as the internal wiring pattern 34 or the via-hole conductor 35 is printed and applied. In addition, it is manufactured by integrally firing this.

  The oscillation electronic component 40a is composed of, for example, an active component such as an IC or a transistor, or a passive component such as a resistor or a capacitor, and oscillates an electric signal having a predetermined frequency by being electrically connected to the surface acoustic wave element 17. Constitutes an oscillation circuit. FIG. 7 is a circuit diagram showing an oscillation circuit using transistors. In such an oscillation circuit 80, resistors, coils, capacitors, and the like are appropriately arranged according to individual conditions such as the resonance frequency of the surface acoustic wave element 17. Is done. A predetermined oscillation frequency fosc is output by applying a predetermined power supply voltage to the oscillation circuit 80 from the control terminal Vcc.

  In addition, the spacer 50 interposed between the piezoelectric substrate 10 and the support substrate 30 described above is made of, for example, a resin or a metal material, thereby providing a predetermined interval between the piezoelectric substrate and the support substrate. Therefore, when mounting the piezoelectric substrate on the support substrate, a predetermined interval can be provided between the acceleration detection unit and the upper surface of the support substrate.

  If the spacer 50 is formed in a frame shape so as to surround the surface acoustic wave element 17 and the oscillation electronic component 40a, the inner side, specifically, the piezoelectric substrate 10, the support substrate 30, the spacer 50, In the region surrounded by (sealing region 51), the surface acoustic wave element 17, the oscillation electronic component 40a and the like can be hermetically sealed. As a result, oxidation corrosion or the like of the IDT electrode 16 or the oscillation electronic component 40a disposed in the sealing region 51 can be effectively prevented. Therefore, it is preferable that the spacer 50 has a frame shape. Further, if the spacer 50 is formed in a frame shape and is formed of a conductive material such as solder, the pressure sensor is connected to the ground terminal of the external terminal electrode 33 on the lower surface of the support substrate. Since the spacer 50 is held at the ground potential when the device 1 is used, unnecessary noise from the outside can be satisfactorily reduced by the spacer 50 due to the shielding effect of the spacer 50.

  In addition, it is preferable that an area surrounded by the piezoelectric substrate 10, the support substrate 30, and the spacer 50 is filled with an inert gas such as nitrogen gas or argon gas. As a result, it is possible to more effectively prevent oxidative corrosion of the IDT electrode 16 and the oscillation electronic component 40a.

  The conductive bonding material 19 is made of, for example, solder or conductive paste, and the IDT of the surface acoustic wave element 17 is connected by connecting the electrode pad 12 of the piezoelectric substrate 10 and the connection pad 18 of the support substrate 30. The electrode 16 and the oscillation electronic component 40a are electrically connected.

  On the other hand, one end side of the piezoelectric substrate 10 extends outward from the fixed region 14, and the acceleration detecting element 21 is formed on the lower surface of the extending portion 36. The acceleration detection element 21 is configured to detect acceleration by deformation of the acceleration detection element 21 by application of the acceleration G, and is formed of, for example, a surface acoustic wave element 27 including a piezoelectric body 25 and an IDT electrode 26. ing. The IDT electrode 26 is connected to the electrode pad 22 through the extraction electrode 23. Further, by providing the weight 70 at the tip of the acceleration detecting element 21, the detection sensitivity of the acceleration G can be improved.

  The material of the piezoelectric body 25 constituting the acceleration detecting element 21 is, for example, the same material as that of the piezoelectric body 15 constituting the pressure detecting unit 11 described above, that is, piezoelectric such as crystal, lithium niobate, lithium tantalate, or the like. A material is used, and a pattern of a metal material such as aluminum or gold is formed on the surface of the piezoelectric body 15 with a thickness of about 2000 mm using a conventionally known sputtering, thin film formation technique, photolithography technique, or the like. Thus, an IDT electrode is formed.

  In addition, the width | variety of the short side of the extension part 36 can be set arbitrarily. If the width of the short side of the extending portion 36 is made narrower than the width of the portion of the piezoelectric substrate 10 where the pressure detecting portion 11 is formed, the extending portion 36 is easily bent by application of acceleration, and the acceleration detection sensitivity. There is an advantage that can be improved. Further, if the width of the short side of the extending portion 36 is the same as the width of the portion of the piezoelectric substrate 10 where the pressure detecting portion 11 is formed, the piezoelectric substrate 10 is scraped when the extending portion 36 is formed. Such a process can be omitted, and the manufacturing process of the pressure detection device 1 can be simplified.

  As described above, by forming both the pressure detection unit 11 and the acceleration detection element 21 by the surface acoustic wave element 27 including the IDT electrode, the pressure detection unit 11 and the acceleration detection element 21 are formed by the same manufacturing process. Therefore, the productivity of the pressure sensor device 1 can be improved.

  The electrode pad 22 and the extraction electrode 23 are made of a metal material such as aluminum or gold as a thin film formation technique or a photolithography technique, similarly to the electrode pad 12 or the extraction electrode 13 formed around the pressure detection unit 11 described above. It is obtained by forming a pattern by, for example.

  The weight 70 is formed by, for example, joining a plate or a laminate made of metal, ceramic, or the like to the end portion of the extending portion 36 with an adhesive.

  When the acceleration detecting element 21 is formed by the surface acoustic wave element 27 as described above, it is preferable to provide the case 20 so that the surface acoustic wave element 27 is hermetically sealed. As a result, oxidative corrosion of the IDT electrode 26 can be prevented.

  In the surface acoustic wave element 27 constituting the acceleration detecting element 21, the electrode pad 22 is electrically connected to the connection pad 28 via the conductive bonding material 29. The connection pad 28 is electrically connected to the acceleration detecting electronic component 40b and the power supply controlling electronic component 40c described above. Therefore, the surface acoustic wave element 27, the acceleration detection electronic component 40b, and the power feeding control electronic component 40c are electrically connected. The acceleration detection electronic component 40b and the power supply control electronic component 40c are, for example, active components such as ICs and transistors, passive components such as resistors and capacitors, and the like, and by electrically connecting to the surface acoustic wave element 27, An acceleration detection circuit 86 and a power supply control circuit 87 as shown in FIG. 8 are configured.

  Meanwhile, in addition to the above-described oscillation electronic component 40a, acceleration detection electronic component 40b, and power feeding control electronic component 40c, an antenna element 95, an amplifier 91, and the like are mounted on the upper surface of the support substrate 30. This antenna element 95 is connected to the oscillation circuit 80 described above, whereby an electric signal of a predetermined frequency output from the oscillation circuit 80 can be wirelessly transmitted to another device having a reception circuit. Pressure information can be obtained even at a location distant from the pressure sensor device 1. As the antenna element 95, for example, a surface mount type chip antenna using a dielectric ceramic or the like is used, and is mounted on the support substrate 30 by soldering or the like.

  In addition, the amplifier 91 is connected to the antenna element 95 and the oscillation circuit 80, thereby increasing the output level of the oscillation signal output from the oscillation circuit, and more reliably wireless to other devices having the reception circuit. It becomes possible to transmit. Furthermore, the power supply control circuit described above is also connected to the amplifier 91 so that the power supply from the power supply means to the amplifier is controlled by the power supply control circuit, thereby suppressing the power consumption of the amplifier and extending the power supply. Will be able to.

  Next, operations when detecting acceleration and pressure using the pressure sensor device 1 described above will be described with reference to the circuit diagrams of FIGS. 6, 7, and 8. Here, the case where the pressure sensor device 1 is built in a tire of a vehicle will be described.

  First, the operation when detecting acceleration will be described. When the vehicle starts to travel, the number of rotations of the tire increases and an acceleration G due to the rotation is generated. When this acceleration G is applied to the acceleration detection element 21, a bending moment acts on the acceleration detection element 21 due to the force acting on the extension portion 36 and the weight 70, the acceleration detection element 21 is bent, and the surface acoustic wave element 27 is deformed. To do. As a result, the propagation speed of the surface acoustic wave changes due to the change in the elastic constant of the portion where the distortion of the piezoelectric body 25 occurs, and the electrode finger arrangement pitch d of the IDT electrodes 26 of the surface acoustic wave element 27 (shown in FIG. 9). ) Changes, and the resonance frequency of the surface acoustic wave element 27 changes due to both of these actions. Then, an electromotive force proportional to the amount of change is generated. Based on this electromotive force, acceleration is detected by the acceleration detection circuit 86, and a control signal proportional to a change in resonance frequency or an impedance change is obtained. When this control signal is input to the power supply control circuit 87, when the level of the control signal exceeds the set threshold value, power is supplied from the power supply means 85 such as a battery to the oscillation circuit 80, and the control signal When the level is less than or equal to the threshold value, power is not supplied from the power supply means 85 to the oscillation circuit 80. Therefore, since power can be supplied only when the vehicle is traveling at a certain speed or higher, the power consumption of the pressure sensor device 1 can be effectively suppressed. Note that the threshold value of the control signal can be arbitrarily set by appropriately selecting circuit elements constituting the power supply control circuit 87.

  The acceleration detection circuit 86 includes a surface acoustic wave element 27, a protection circuit including a diode, and an operational amplifier as shown in FIG. 8, and a power supply control circuit 87 includes a high-pass filter including a capacitor and a resistor as shown in FIG. A power source and an operational amplifier.

  On the other hand, the pressure in the tire is detected as follows. When the pressure in the tire changes due to, for example, air in the tire being removed, the pressure applied to the piezoelectric substrate 10 is changed, and the surface acoustic wave element 17 constituting the pressure detection unit 11 is deformed. As a result, the propagation speed of the surface acoustic wave changes due to the change in the elastic constant of the portion where the piezoelectric body 15 is distorted, and the electrode finger arrangement pitch d of the IDT electrodes 16 of the surface acoustic wave element 17 (shown in FIG. 9). ) Changes, and the resonance frequency of the surface acoustic wave element 17 changes due to both actions. Along with this, the oscillation frequency fosc of the oscillation circuit 80 shown in FIG. 7 also changes, so that the pressure fluctuation applied to the piezoelectric substrate 10 is finally detected as a change in the oscillation frequency fosc of the oscillation circuit 80. The power supply to the oscillation circuit 80 is controlled by the power supply control circuit 87 as described above.

  Thus, as shown in the block circuit diagram of FIG. 6, the pressure sensor device 1 according to the present embodiment monitors the control signal output from the acceleration detection circuit 86 by the power supply control circuit 87, and the control signal has a certain threshold value. Only in the above case, power is supplied from the power supply means 85 to the oscillation circuit 80 and the amplifier 91, and pressure information detected by the pressure detection unit is converted into an oscillation signal of a predetermined frequency by the oscillation circuit 80. Wirelessly transmitted from the antenna.

  In the pressure sensor device 1 as described above, at least one end side of the piezoelectric substrate 10 is separated from the upper surface of the support substrate 30 so as to extend outside the fixed portion with respect to the support substrate 30 and the extension portion 36 detects acceleration. Since the element 21 is formed and the pressure detection unit 11 and the acceleration detection element 21 are integrated on the piezoelectric substrate 10, it is not necessary to prepare a separate substrate for the acceleration detection element 21, and the number of parts can be reduced. Thus, the pressure sensor device 1 can be reduced in size and weight.

  Next, a pressure sensor device according to a second embodiment of the present invention will be described. 3 is a cross-sectional view of the pressure sensor device 1 according to the second embodiment of the present invention, FIG. 4A is a plan view showing the top surface of the piezoelectric substrate 10 used in the pressure sensor device of FIG. 3, and FIG. ) Is a plan view showing the lower surface of the piezoelectric substrate 10 used in the pressure sensor device of FIG. 3, and FIG. 5 is a plan view showing the upper surface of the support substrate 30 used in the pressure sensor device of FIG. In addition, the same code | symbol is attached | subjected about the same thing as 1st Embodiment shown in FIG. 1, and the description is abbreviate | omitted.

  In the pressure sensor device 1 shown in FIG. 3, the acceleration detecting element 21 of the pressure sensor device 1 in the first embodiment is configured by a bimorph element 37 instead of the surface acoustic wave element 27. The bimorph element 37 uses the bulk vibration of the piezoelectric substrate 10 and is formed by attaching the vibrating electrodes 31 to both the upper and lower surfaces of the extending portion 36 of the piezoelectric substrate 10.

  The vibrating electrode 31 is made of a metal material such as silver, and is formed by, for example, a conventionally known film forming technique such as sputtering or vapor deposition.

  Such a bimorph type acceleration detecting element 21 detects acceleration as follows. First, when the acceleration G is applied to the extension part 36 and the weight 70, the acceleration detection element 21 is bent, and the bimorph element 37 formed in the extension part 36 is deformed. At this time, tensile stress acts on one vibration electrode 31 of the bimorph element 37 and compressive stress acts on the other vibration electrode 31. As a result, an electromotive force proportional to the amount of change of both vibrating electrodes 31 is generated, and thereby acceleration can be detected.

  When the acceleration detecting element 21 is configured by the bimorph element 37 as described above, the pattern shape can be formed with a solid coating pattern, and since it is not necessary to be hermetically sealed, it can be formed relatively easily. The productivity of the piezoelectric sensor device 1 can be improved.

  Next, a pressure sensor device according to a third embodiment of the present invention will be described with reference to FIG. In the present embodiment, only differences from the above-described embodiment will be described, and the same components will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 10 is a plan view showing the lower surface of the sensor substrate 10 used in the pressure sensor device of the present embodiment.

  The first difference between the pressure sensor device of the present embodiment and the pressure sensor device described above is that the surface acoustic wave elements 47 constituting the pressure detection unit 11 are arranged on the lower surface of the piezoelectric substrate 10 with a space therebetween. This is a surface acoustic wave delay line composed of a pair of IDT electrodes 16 and a surface acoustic wave propagation path 38 therebetween. Damping materials 39 made of silicon resin or the like are formed on the lower surface of the piezoelectric substrate 10 on both sides of the surface acoustic wave element 47 in the propagation direction of the surface acoustic wave. The damping material 39 functions to attenuate surface acoustic waves and prevent reflection of surface acoustic waves at the end of the piezoelectric substrate 10 and leakage of surface acoustic waves to other regions.

  When such a surface acoustic wave delay line is connected to an oscillation electronic component 40a having an amplifier circuit, an oscillation circuit that oscillates at a frequency corresponding to the delay time of an electric signal generated by the surface acoustic wave delay line can be configured. . When external pressure is applied to the piezoelectric substrate 10 and stress is applied to the surface acoustic wave propagation path 38 of the surface acoustic wave element 47 to cause distortion, the propagation of the surface acoustic wave is caused by a change in the elastic constant of the portion. As the velocity changes, the length of the propagation path 38 of the surface acoustic wave changes. The delay time of the electric signal changes due to both of these actions, and as a result, the oscillation frequency of the oscillation circuit composed of the surface acoustic wave element 47 and the oscillation electronic component 40a having the amplification circuit connected thereto changes. To do. Therefore, the surface acoustic wave element 47 in the present embodiment also functions as a pressure detection element in the same manner as the surface acoustic wave element 17 in the above-described embodiment.

  The second difference of the pressure sensor device of the present embodiment from the pressure sensor device described above is that the surface acoustic wave element 57 constituting the acceleration detecting element 21 is also arranged on the lower surface of the piezoelectric substrate 10 with a gap. This is a surface acoustic wave delay line composed of a pair of IDT electrodes 26 and a surface acoustic wave propagation path 38 therebetween. Damping materials 39 made of silicon resin or the like are also formed on both sides of the surface acoustic wave element 57 in the propagation direction of the surface acoustic wave.

  When this surface acoustic wave delay line is connected to an oscillation electronic component 40a having an amplifier circuit, an oscillation circuit that oscillates at a frequency corresponding to the delay time of an electric signal generated by the surface acoustic wave delay line can be configured. When the acceleration G is applied to the acceleration detecting element 21, a bending moment acts on the acceleration detecting element 21 due to the force acting on the extension part 36 and the weight 70, the acceleration detecting element 21 is bent, and the surface acoustic wave element 57 is Deform. As a result, when a stress is applied to the surface acoustic wave propagation path 38 of the surface acoustic wave element 57 to cause distortion, the propagation speed of the surface acoustic wave changes due to the change in the elastic constant of the portion, and the propagation of the surface acoustic wave also occurs. The length of the path 38 changes. The delay time of the electric signal changes due to both of these actions, and as a result, the oscillation frequency of the oscillation circuit composed of the surface acoustic wave element 57 and the oscillation electronic component 40a having the amplification circuit connected thereto changes. To do. Therefore, the surface acoustic wave element 57 in the present embodiment also functions as an acceleration detection element in the same manner as the surface acoustic wave element 27 in the above-described embodiment.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change and improvement are possible in the range which does not deviate from the summary of this invention.

  For example, in the first embodiment of the present invention, the surface acoustic wave element 27 constituting the acceleration detecting element 21 is formed only on the lower surface of the extending portion 36. Instead, as shown in FIG. The surface acoustic wave element 27 may be formed on both the upper and lower surfaces of the extending portion 36. The measurement accuracy of the acceleration detecting element 21 is improved by using one of the two surface acoustic wave elements 27 formed on the upper and lower surfaces of the extending portion 36 as a correction sensor element that corrects the influence of a temperature change or the like. It becomes possible to make it.

  In the present embodiment, the pressure detection unit 11 is formed on the lower surface side of the piezoelectric substrate 10, but instead, the pressure detection unit 11 may be formed on the upper surface side of the piezoelectric substrate 10. I do not care.

  Furthermore, in this embodiment, a chip antenna is used as the antenna element 95, but instead of this, for example, an antenna pattern constituted by a meandering conductor pattern may be formed on the support substrate 30. . As a result, the number of parts can be reduced, and the outer dimensions can be reduced.

  In the second embodiment of the present invention, the vibration electrode 31 of the acceleration detecting element 21 is the bimorph element 37 formed on both the upper and lower surfaces of the extension portion 36. A unimorph element formed on either the upper or lower surface of the piezoelectric substrate 10 may be used.

  Furthermore, in the third embodiment of the present invention, both the surface acoustic wave element 47 constituting the pressure detection unit 11 and the surface acoustic wave element 57 constituting the acceleration detection element 21 are formed as surface acoustic wave delay lines. However, only one of them may be a surface acoustic wave delay line. In this case, the other surface acoustic wave device may be a surface acoustic wave resonator including an IDT electrode and a reflector electrode as in the first embodiment. The acceleration detecting element 21 may be a bimorph element as in the second embodiment or a unimorph element.

It is sectional drawing of the pressure sensor apparatus concerning the 1st Embodiment of this invention. It is a top view which shows the lower surface of the piezoelectric substrate used for the pressure sensor apparatus of FIG. It is sectional drawing of the pressure sensor apparatus concerning the 2nd Embodiment of this invention. (A) is a top view which shows the upper surface of the piezoelectric substrate used for the pressure sensor apparatus of FIG. 3, (b) is a top view which shows the lower surface of the piezoelectric substrate used for the pressure sensor apparatus of FIG. It is a top view of the support substrate used for the pressure sensor apparatus of FIG. 1, FIG. It is a block diagram of the pressure sensor device of the present invention. It is a circuit diagram which shows the oscillation circuit of the pressure detection part which is a part of pressure sensor apparatus of this invention. It is a circuit diagram which shows the circuit structure of the acceleration detection element which is a part of pressure sensor apparatus of this invention. It is an enlarged view of the IDT electrode formed in the piezoelectric substrate of the pressure sensor apparatus of this invention. It is a top view which shows the lower surface of the piezoelectric substrate used for the pressure sensor concerning the 3rd Embodiment of this invention. It is sectional drawing of the pressure sensor apparatus concerning other embodiment of this invention. It is explanatory drawing which shows the conventional pressure sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pressure sensor apparatus 10 ... Piezoelectric substrate 11 ... Pressure detection part 12, 22 ... Electrode pad 13, 23 ... Extraction electrode 14 ... ... Fixed area on the piezoelectric substrate side 15, 25 ... Piezoelectric body 16, 26 ... IDT electrodes 17, 27, 47, 57 ... Surface acoustic wave element 18,28 ... Connection pads 19,29 ... Conductive bonding material 21 ... Acceleration detection element 24 ... Through hole 20 ... Case 37 ... Bimorph element 30 ... Support substrate 31... Vibration electrode 32... Fixed region on the support substrate side 33... External terminal electrode 34.・ Via hole conductor 40 ・ ・ ・ ・ ・ ・ Electronic parts 50 ・ ・ ・ ・ ・ ・ Spacer 51 ・ ・... Sealing area 70 ... Weight 80 ... Oscillation circuit 85 ... Power feeding means 86 ... Acceleration detection circuit 87 ... Power feeding Control circuit 91 ... Amplifier 95 ... Antenna element

Claims (5)

A piezoelectric substrate having a pressure detector and detecting pressure fluctuations by deformation of the pressure detector;
A support substrate on which the piezoelectric substrate is placed and fixed;
An oscillation circuit for transmitting an electrical signal of a predetermined frequency based on pressure fluctuation information from the pressure detector;
An acceleration detection circuit that has an acceleration detection element that detects acceleration fluctuations by deformation caused by application of acceleration, and that transmits a predetermined electrical signal based on acceleration fluctuation information from the acceleration detection elements;
Power supply means for supplying power to the oscillation circuit;
A power supply control circuit for controlling power supply from the power supply means to the oscillation circuit, and a pressure sensor device comprising:
The piezoelectric substrate is extended outward from a fixed portion with respect to the support substrate in a state where at least one end side of the piezoelectric substrate is separated from the upper surface of the support substrate, and the acceleration detecting element is formed in the extension portion. Pressure sensor device. The pressure sensor device according to claim 1, wherein both the pressure detection unit and the acceleration detection element are formed by surface acoustic wave elements including an interdigital transducer. The pressure sensor device according to claim 1, wherein the piezoelectric substrate is placed on the support substrate via a spacer. The pressure sensor device according to any one of claims 1 to 3, wherein an antenna element electrically connected to the oscillation circuit is provided on the upper surface of the support substrate and / or the lower surface of the pressure substrate. . An amplifier for amplifying an electric signal from the oscillation circuit is connected between the antenna element and the oscillation circuit, and power supply from the power supply means to the amplifier is controlled by the power supply control circuit. The pressure sensor device according to claim 4.

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