JP2011160612A - Power generation sensor element and sensor node - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the size of a sensor node which operates on the electric power extracted out of vibration using a power generation element and detects own vibration with a vibrating element. <P>SOLUTION: A power generation sensor element 11 includes a power generation electrode 11C of a thin metal plate which is formed on a substrate 11F; a charged body 11B arranged on the power generation electrode 11C; a support part 11H which is secured on the substrate 11F at the periphery of the power generation electrode 11C; an elastic spring 11G, whose one end is secured to the upper end of the support part 11H; a movable body 11A of thin metal plate which is connected to the other end of the spring 11G and is supported at the position facing the charged body 11B horizontally for vibration over the charged body 11B; and two sensor electrodes 11D and 11E of thin metal plate which are provided upright; at positions that face each other across the movable body 11A, at the periphery of the power generation electrode 11C on the substrate 11F. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to sensor node technology, and more particularly to downsizing of a sensor node that operates with electric power extracted from vibration and detects its own vibration.

Research on sensor network technology for constructing high-performance sensor nodes by adding communication functions and data processing functions to sensors that detect various types of data, and further constructing a network with these sensor nodes is progressing.
In this sensor network technology, for the purpose of reducing the size and weight of a sensor node, a sensor node in which a circuit configuration for detecting data and transmitting it to a receiving device is realized with a semiconductor chip has attracted attention.

  By attaching such a sensor node to various objects such as an object or a person, it is possible to detect data indicating various states of the object and transmit the data to the receiving device by a wireless signal. Therefore, by collecting these detection data received by the receiving device via a network such as the Internet, various services can be realized, and so-called ubiquitous network services can be realized. For example, by detecting the vibration frequency and acceleration with a sensor node attached to the device, and collecting and providing these detection data with the receiving device, it is possible to grasp the operating state of the device at a remote location via a network. It is possible to provide a wide range of maintenance and maintenance services.

  FIG. 23 is a block diagram illustrating a configuration of a conventional sensor node system (see, for example, Patent Document 1 and Patent Document 2). The sensor node system 5 includes a sensor node 50 and a receiving device 60. Data detected by the sensor node 50 is transmitted to the receiving device 60 via a radio wave. A radio wave is a relatively weak radio signal and can communicate over a distance of several tens of centimeters to several tens of meters.

  The sensor node 50 includes a sensor element unit 51, a sensor circuit unit 52, an A / D conversion unit 53, a CPU 54, a memory unit 55, a radio unit 56, and a power supply unit 57. Power is supplied from the power supply unit 57 to each block. Has been. The power supply unit 57 includes, for example, a power generation mechanism that converts vibration energy into electric energy, a secondary battery, and the like, and is devised so that long-time operation can be realized.

  The differential voltage signal obtained from the sensor element unit 51 is amplified by the differential amplifier AMP of the sensor circuit unit 52 and then A / D converted by the A / D conversion unit 53 at the subsequent stage, and the memory unit 55 is processed by the CPU 54. Saved as detection data. Thereafter, the detection data is read from the memory unit 55 by the CPU 54 at a predetermined timing, and transmitted from the wireless unit 56 to the receiving device 60 by wireless radio waves.

  FIG. 24 is a circuit diagram showing a configuration of a conventional sensor element section and sensor circuit section. The sensor element unit 51 includes two vibration sensors 51A and 51B connected in parallel in opposite directions between the operating power supply VDD and the ground potential GND (hereinafter, the vibration sensor is also referred to as “vibration element”). The vibration sensor 51A is formed of a series connection of two variable capacitance elements CP1 and CN1 whose capacitance values change in opposite directions due to external vibration. The vibration sensor 51B includes two elements whose capacitance values change in opposite directions due to external vibration. It consists of variable capacitance elements CP2 and CN2.

  FIG. 25 is a configuration example of a conventional vibration sensor (see, for example, Patent Document 2). The vibration sensors 51A and 51B have a fine comb-tooth structure configured on a silicon chip by a MEMS (Micro Electro Mechanical System) process, and have a movable electrode 51M and two fixed electrodes 51P and 51N.

  In these vibration sensors 51A and 51B, when the movable electrode 51M vibrates due to external vibration, the distance between the fixed electrodes 51P and 51N changes, and the capacitances CP and CN between the movable electrode 51M and the fixed electrodes 51P and 51N change. The size changes. At this time, since the movable electrode 51M is arranged between the fixed electrode 51P and the fixed electrode 51N, the capacitors CP and CN change differentially.

  Therefore, when the operating power supply VDD is applied to the fixed electrode 51P via the node N1 and the ground potential GND is applied to the fixed electrode 51N via the node N2, the voltage is varied according to external vibration with the intermediate potential between VDD and GND as the center. Is output from the node N3 of the movable electrode 51M to the sensor circuit unit 52. At this time, since the vibration sensors 51A and 51B are connected in parallel in the opposite direction between the operating power supply VDD and the ground potential GND, voltage signals having opposite phases to the same external vibration are supplied to the sensor circuit unit 52. Is output.

On the other hand, a technology for storing vibration energy given from the outside in a small element (hereinafter referred to as “power generation element”) in electric charge and converting it into electric energy is known as PMPG (Piezoelectric Micro Power Generator) technology. In recent years, research has become active (see Non-Patent Document 1, etc.). FIG. 26 is a circuit unit showing a conventional example of PMPG.
The AC current generator 61 in FIG. 26, that is, the AC current generated when vibration is applied to the power generation element, is rectified by a rectifier circuit 62 made of a diode, and further smoothed by a capacitor 63 to become a DC current. This is supplied to the processing circuit 64 in the subsequent stage.

The power generation element can be used after changing the structure of the vibration sensor (vibration element) as shown in FIG. That is, both the vibration element that detects vibration and the power generation element that converts vibration energy into electrical energy change the electric capacity when the two electrode plates are directly or indirectly connected by a spring and relatively vibrate. In principle, they are identical in that they have a configuration with capacitors and as a result vibrations are converted into alternating current (or alternating voltage).
A technique has also been proposed in which power is supplied to a subsequent processing circuit after the capacitor stores a predetermined voltage (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 2004-024551 JP 2009-302632 A JP 2009-055769 A

Y.B.Jeon, et al., "MEMS power generator with transverse mode thin film PZT", ELSEVIER, Sensors and Actuators A 122 (2005) pp.16-22.

The vibration element that detects vibration and the power generation element that converts vibration energy into electrical energy have the same structure in principle, that is, two electrode plates are directly or indirectly connected by a spring and vibrate relatively. As described above, the configuration includes a capacitor whose electric capacity changes as a result.
Here, when vibration energy is supplied as electric energy to a sensor node that detects vibration, it is necessary to separately provide a capacitor for a vibration element and a capacitor for a power generation element. The reason is that the design parameters of the capacitor are different for the vibration element and the power generation element.

On the other hand, in order to ensure high sensitivity and high linearity for the vibration element, the capacity of the capacitor, the mass of the electrode, and the spring constant are set for the power generation element so that high output of current, voltage, and power is possible. Must be set. However, at this time, the optimum determination method of these parameters is unknown, so it must be determined empirically.
In addition, it is reasonable from the viewpoint of the quality of the obtained signal to optimally design the processing circuit for the vibration element and the power generation element in accordance with the output characteristics of each capacitor.

  Therefore, according to the above-described prior art, when vibration energy is supplied as electric energy to the sensor node that detects vibration, a power generation element that extracts vibration energy and vibration that detects vibration corresponding to the operation of a person or thing There is a problem that it is necessary to individually mount elements, and the sensor node cannot be reduced in size.

  The present invention is for solving such problems, and an object of the present invention is to provide a technology for downsizing a sensor node that operates with electric power extracted from vibration by a power generation element and detects its own vibration by the vibration element. It is said.

  In order to achieve such an object, a power generation sensor element according to the present invention includes a power generation electrode made of a thin metal plate formed on a substrate, a charged body disposed on the power generation electrode, and a substrate. A supporting portion fixed at a peripheral position of the power generation electrode; an elastic spring having one end fixed to the upper end of the supporting portion; and connected to the other end of the spring, above the charging body, And a movable body made of a thin metal supported so as to be able to vibrate at a position facing horizontally with the metal, and a thin metal that stands on the substrate at a position surrounding the power generation electrode and facing each other across the movable body When the vibrating element composed of the movable body and the electric sensor electrode is displaced in the X direction parallel to the substrate surface according to the vibration applied from the outside, the movable body and Two capacitances generated between the sensor electrodes The detection signals having opposite amplitudes, the amplitude of which changes according to the displacement, are output from the two sensor electrodes, respectively, and the power generation element composed of the movable body, the charging body, and the power generation electrode is subjected to vibration applied from the outside. Accordingly, when the movable body is displaced in the Z direction orthogonal to the substrate surface, the charge induced in the power generation electrode is changed, and a voltage signal whose amplitude is changed according to the displacement is output from the power generation electrode.

At this time, the spring may have a smaller width in the Z direction than the width in the X direction.
The movable body may be supported by a single spring.
Alternatively, the movable body may be supported by two springs that are connected to each other with the movable body interposed therebetween along the Y direction orthogonal to the X direction in parallel with the substrate surface.
Alternatively, the movable body may be supported by four springs that are connected two by two across the movable body along the Y direction orthogonal to the X direction in parallel with the substrate surface.
Alternatively, the movable body may be supported by four springs connected at positions that are symmetric with respect to the plane viewpoint with respect to the center of the movable body.

Moreover, you may use a crooked shape as a spring.
Moreover, you may arrange | position a spring in the notch part provided in the movable body.
Further, a weight for adjusting the resonance frequency of the displacement may be provided on the movable part.

  In addition, a wall-like edge higher than the thickness of the movable part is provided on the movable part at a position at least on the periphery of the upper surface or the lower surface and facing the sensor electrode, and the sensor electrode faces the edge. You may arrange in the position to do.

  Further, the movable part is provided with a wall-like edge part higher than the thickness of the movable part over the entire circumference of the lower surface, the sensor electrode is disposed at a position facing the edge part, and at least a part of the charged body May be disposed inside a recess formed on the lower surface of the movable portion by the edge.

  Further, the movable portion and the spring are integrally formed by processing a thin metal plate, and at least an edge portion facing the sensor electrode of the movable portion is bent to project the plate portion upward or downward. May be formed.

  In addition, a printed circuit board is used as a substrate, the power generation electrode is composed of a wiring pattern formed on the substrate, the sensor electrode is bent on a thin plate metal into an L shape, and is erected on the printed circuit board. Alternatively, a thin metal plate may be processed and formed integrally, and at least an end portion of the movable portion facing the sensor electrode may be bent to form an edge protruding upward or downward in a plate shape. .

  The sensor node according to the present invention includes any one of the above-described power generation sensor elements, a power storage circuit that generates an operating power supply by storing electric charges output from the power generation electrodes of the power generation sensor elements, and a power supply circuit that supplies the power supply circuit. The sensor output signal is generated by accumulating the electric charge output as the detection signal from the sensor electrode of the power generation sensor element, and the comparison result comparing this sensor output signal with the threshold value is output. A sensor element signal detection circuit that outputs a signal, and a wireless circuit that operates based on an operating power supplied from the power storage circuit in response to the output signal and transmits a radio wave.

  At this time, a rectifier circuit that rectifies the electric charge output from the power generation electrode, a capacitor element that accumulates the electric charge rectified by the rectifier circuit and generates an operating power supply, and an upper limit of voltage increase of the operating power supply are stored in the storage circuit. A voltage limiting circuit for limiting the voltage to a value, and voltage detection for supplying the operating power to the sensor element signal detecting circuit by turning on the first switch during the period when the voltage of the operating power is higher than the lower threshold A circuit and a second switch that is turned on in response to the output signal to supply operating power to the sensor element signal detection circuit may be provided.

  A sensor circuit that operates in response to the operating power supplied via the first switch in the sensor element signal detection circuit and generates a sensor output signal by accumulating the charge output as the detection signal; And a threshold circuit that operates according to the operating power supplied through one switch and outputs a comparison result obtained by comparing the sensor output signal with the threshold value as an output signal.

  According to the present invention, the power generation sensor element can detect vibration, that is, movement of a person or thing, and is generated on a floor or a wall by a displacement in the X direction caused by a large vibration caused by movement of a person or thing. Electric power used for operation of the sensor node can be generated by displacement in the Z direction due to relatively weak environmental vibration, and the sensor node can be downsized.

It is a block diagram which shows the structure of the sensor node concerning 1st Embodiment. It is a top view which shows the structure of the electric power generation sensor element concerning 1st Embodiment. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is an external view which shows a spring. It is a circuit diagram which shows the electrical storage circuit and sensor element signal detection circuit of a sensor node. It is a structural example of a diode. It is a structural example of a voltage limiting circuit. It is a structural example of a zero power sensor circuit. It is a structural example of a zero power sensor circuit. It is a signal waveform diagram which shows operation | movement of a sensor node. It is a signal waveform diagram which shows other operation | movement of a sensor node. It is explanatory drawing which shows operation | movement of a radio | wireless circuit. It is a top view which shows the electric power generation sensor element concerning 2nd Embodiment. It is a top view which shows the electric power generation sensor element concerning 3rd Embodiment. It is a top view which shows the electric power generation sensor element concerning 4th Embodiment. It is a top view which shows the spring concerning 5th Embodiment. It is a top view which shows the electric power generation sensor element concerning 6th Embodiment. It is a top view which shows the other electric power generation sensor element concerning 6th Embodiment. It is a top view which shows the other electric power generation sensor element concerning 6th Embodiment. It is a top view which shows the other electric power generation sensor element concerning 6th Embodiment. It is a top view which shows the electric power generation sensor element concerning 7th Embodiment. It is BB sectional drawing of FIG. 17A. It is a top view which shows the electric power generation sensor element concerning 8th Embodiment. It is AA sectional drawing of FIG. 18A. It is a top view which shows the electric power generation sensor element concerning 9th Embodiment. It is AA sectional drawing of FIG. 19A. It is a top view which shows the electric power generation sensor element concerning 10th Embodiment. It is AA sectional drawing of FIG. 20A. It is BB sectional drawing of FIG. 20A. It is sectional drawing which shows the electric power generation sensor element concerning 11th Embodiment. It is sectional drawing which shows the electric power generation sensor element concerning 12th Embodiment. It is a block diagram which shows the structure of the conventional sensor node system. It is a circuit diagram which shows the structure of the conventional sensor element part and a sensor circuit part. It is a structural example of a conventional vibration sensor It is a circuit part which shows the prior art example of PMPG.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a sensor node according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of a sensor node according to the first embodiment.

  The sensor node 10 is attached to various objects such as an object and a person, detects the state of the object, and transmits it to an external device by wireless radio waves. A radio wave is a relatively weak radio signal and can communicate over a distance of several tens of centimeters to several tens of meters. By configuring a communication network using a plurality of such sensor nodes 10, a sensor node system that collects data indicating the states of various objects is constructed.

  This embodiment is characterized in that a vibration element that detects vibration and a power generation element that extracts vibration energy and generates power required by the sensor node 10 are integrated into one power generation sensor element 11. .

[Sensor node]
With reference to FIG. 1, the structure of the sensor node 10 concerning this Embodiment is demonstrated.
The sensor node 10 is provided with a power generation sensor element 11, a power storage circuit 12, a sensor element signal detection circuit 13, and a radio circuit 14 as main functional units.

  The power generation sensor element 11 includes a vibration element 11X and a power generation element 11Z configured on a substrate based on a micromachining technique such as a MEMS (Micro Electro Mechanical System) process, and is added to the sensor node 10 as a power generation element. A function of generating electric power by extracting the vibration energy as a charge, and a function of detecting vibration applied to the sensor node 10 by the vibration element. Details of the power generation sensor element 11 will be described later.

  The power storage circuit 12 stores a charge output from the power generation element 11Z of the power generation sensor element 11 to generate the operation power supply VDD, a function to supply the obtained operation power supply VDD to the sensor element signal detection circuit 13, It has a function of supplying the operating power supply VDD to the wireless circuit 14 in response to the control signal OUT from the sensor element signal detection circuit 13.

The sensor element signal detection circuit 13 boosts and accumulates the antiphase detection signals BP and BN output from the vibration element 11X of the power generation sensor element 11, and outputs the sensor output signal SO as a sensor output signal SO. Has a function of outputting the control signal OUT to the power storage circuit 12 when the voltage reaches the threshold voltage Vth.
At this time, the sensor output signal SO changes its voltage increase speed according to the magnitude of vibration or acceleration of the object. Therefore, the time required for the sensor output signal SO to rise from the initial voltage to the threshold voltage, that is, the output interval of the control signal OUT changes in accordance with the magnitude of the target vibration or acceleration.

The radio circuit 14 is operated by the operation power supply VDD supplied from the power storage circuit 12 and has a function of transmitting a predetermined radio wave including data such as identification information of the sensor node 10, for example. For this reason, wireless radio waves are transmitted from the wireless circuit 14 at intervals according to the magnitude of vibration or acceleration detected by the power generation sensor element 11.
In this case, the wireless circuit 14 may use a method of modulating and transmitting a high-frequency pulse itself such as UWB (Ultra Wide Band), thereby enabling low-power wireless communication. The wireless system is not limited to UWB, and a wireless system capable of reducing the power equivalent to or lower than this may be used.

  As for the transmission period length of the radio wave, the sensor element signal detection circuit 13 terminates one detection period in response to the completion of the output of the control signal OUT and initializes the sensor output signal SO. An initialization operation for the above may be performed. Alternatively, the sensor element signal detection circuit 13 may perform the initialization operation in response to a radio wave transmission end notification notified from the radio circuit 14.

[Power generation sensor element]
Next, the configuration of the power generation sensor element according to the present embodiment will be described with reference to FIGS. 2, 3A, 3B, and 3C. FIG. 2 is a plan view showing the configuration of the power generation sensor element according to the first embodiment. 3A is a cross-sectional view taken along the line AA in FIG. 3B is a cross-sectional view taken along the line BB in FIG. FIG. 3C is an external view showing a spring.

  The power generation sensor element 11 includes a movable body 11A, a charging body 11B, a power generation electrode 11C, and sensor electrodes 11D and 11E disposed on the substrate 11F. Among these, the movable body 11A and the sensor electrodes 11D and 11E constitute the vibration element 11X, and the movable body 11A and the power generation electrode 11C constitute the power generation element 11Z. An actual structure example regarding the power generation sensor element 11 will be described in an embodiment described later.

The movable body 11A and the power generation electrode 11C are made of a thin metal plate having the same rectangular shape in plan view.
The power generation electrode 11C is formed on the substrate 11F, and the charged body 11B is formed on the power generation electrode 11C. Further, a support portion 11H is erected on the substrate 11F around the power generation electrode 11C, and has an elastic rod shape protruding from the upper end of the support portion 11H in the horizontal direction Y parallel to the substrate surface of the substrate 11F. One end of the spring 11G is fixed. The other end of the spring 11G is fixed to the side surface of the movable body 11A. Thus, the movable body 11A is supported by the spring 11G via the spring 11G so as to vibrate with a slight gap from the charging body 11B at a position horizontally opposite the charging body 11B. ing.

  The sensor electrodes 11D and 11E are made of a thin metal plate having a wall shape, and the substrate surfaces of the movable body 11A and the substrate 11F are formed on the substrate 11F around the power generation electrode 11C with a slight gap from the movable body 11A. In parallel with the horizontal direction Y, they are erected so as to face each other along the horizontal direction X orthogonal to the horizontal direction Y. In the example of FIG. 2, the sensor electrodes 11D and 11E are arranged at positions facing each other across the movable body 11A, and the movable body 11A extends along the horizontal direction Y where the sensor electrodes 11D and 11E face each other. It is supported in the air by the spring 11G.

When a vibration is applied from the outside to the power generation sensor element 11 having such a configuration and the movable body 11A shakes in the horizontal direction X, the distance between the movable body 11A and the sensor electrode 11D, and the movable body 11A The distance from the sensor electrode 11E changes differentially. At this time, the spring 11G and the support portion 11H are made of metal, and the movable body 11A is connected to the ground potential GND via the spring 11G and the support portion 11H.
Therefore, the capacitance CP generated between the movable body 11A and the sensor electrode 11D and the capacitance CN generated between the movable body 11A and the sensor electrode 11E also change differentially with respect to the ground potential GND. Therefore, a sensor output signal SO that changes in accordance with the magnitude of vibration can be obtained by rectifying the anti-phase detection signals obtained from the variable capacitors CP and CN and charging the capacitive element.

On the other hand, when the movable body 11A swings in the vertical direction Z perpendicular to the substrate surface of the substrate 11F, the distance between the movable body 11A, the charging body 11B, and the power generation electrode 11C changes. In particular, for the spring 11G, as shown in FIG. 3C, the width T in the vertical direction Z is set smaller than the width W in the horizontal direction X (W> T). Thereby, it becomes easier to vibrate in the vertical direction Z than in the horizontal direction X.
For this reason, charge is induced in the power generation electrode 11C, and the voltage signal BV generated between the movable body 11A and the power generation electrode 11C also changes. Therefore, by rectifying the AC voltage signal BV centered on the ground potential GND and storing it in the capacitive element, it is possible to obtain an operating power supply VDD that increases in response to vibration, and to generate power from vibration energy. Can do.

According to the power generation sensor element 11 according to the present embodiment, since the movable body 11A that requires a relatively large size is shared by the vibration element 11X and the power generation element 11Z, the power generation sensor element 11 is reduced in size. be able to.
Accordingly, vibration, that is, movement of a person or a thing can be detected by a displacement in the horizontal direction X caused by a large vibration caused by movement of a person or a thing with a single element, and relatively generated on a floor or a wall. The electric power used for the operation of the sensor node can be generated by the displacement in the vertical direction Z due to the weak environmental vibration.

[Storage circuit]
Next, the power storage circuit of the sensor node according to the present embodiment will be described in detail with reference to FIG. FIG. 4 is a circuit diagram showing the storage circuit of the sensor node and the sensor element signal detection circuit.
The storage circuit 12 is provided with a rectifier circuit 12A, a capacitive element CV, a voltage limiting circuit 12B, a voltage detection circuit 12C, a switch SW1 (first switch), and a switch SW2 (second switch) as main circuits. Yes.

  The rectifier circuit 12A includes diodes D1 and D2 connected in series in the forward direction, and a connection point between the anode terminal of the diode D1 and the cathode terminal of the diode D2 is connected to the power generation electrode 11C of the power generation sensor element 11, and the diode D2 Are connected to the ground potential GND. As a result, the voltage signal BV generated at the power generation electrode 11C is rectified by the diodes D1 and D2, and output from the cathode terminal of the diode D1.

  FIG. 5 is a configuration example of a diode. Here, by connecting the source terminal of the nMOS transistor to the source terminal of the pMOS transistor, connecting the gate terminal of the nMOS transistor to the drain terminal of the pMOS transistor, and connecting the gate terminal of the pMOS transistor to the drain terminal of the nMOS transistor, A diode is constructed in which the drain terminal of the nMOS transistor is the cathode terminal and the drain terminal of the pMOS transistor is the anode terminal. By using such a configuration as the diodes D1 and D2, the leakage current in the diodes D1 and D2 can be reduced.

  The capacitive element CV includes a capacitor connected between the cathode terminal of the diode D1 and the ground potential GND, and the voltage signal BV rectified by the diode D1 is stored in the capacitive element CV as the operation power supply VDD.

  The voltage limiting circuit 12B is a circuit that is connected between the operating power supply VDD and the ground potential GND and limits the voltage rise of the operating power supply VDD. FIG. 6 is a configuration example of the voltage limiting circuit. Here, the voltage detection circuit CMP connected between the operating power supply VDD and the ground potential GND monitors the operating power supply VDD and rises to an upper limit threshold value VH indicating a potential that can be supplied as operating power to each circuit. If it is, switch SW is turned on. As a result, the resistance element R is connected between the operating power supply VDD and the ground potential GND, and the operating power supply VDD is always discharged by the time constant of the capacitive element C and the resistance element R, and the voltage rise is limited.

  The voltage detection circuit 12C is connected between the operation power supply VDD and the ground potential GND, and detects whether or not the operation power supply VDD has reached a potential that can be supplied to the sensor element signal detection circuit 13 as the operation power supply. is there. As a result, when the operating power VDD rises above the lower threshold VL indicating the potential that can be supplied to the sensor element signal detection circuit 13 as the operating power, the switch SW1 is turned on according to the output of the voltage detection circuit 12C. Then, the operating power supply VDD is supplied to the sensor element signal detection circuit 13 via the switch SW1.

  The switch SW2 is a switch element that controls the supply of the operating power supply VDD to the wireless circuit 14 in accordance with the control signal OUT from the sensor element signal detection circuit 13. Thus, when vibration is detected by the sensor element signal detection circuit 13 based on the detection signals BP and BN having opposite phases output from the sensor electrodes 11D and 11E of the power generation sensor element 11, an output is output according to the vibration detection. The switch SW2 is turned on in response to the control signal OUT, and the operating power supply VDD is supplied to the wireless circuit 14 via the switch SW2.

[Sensor element signal detection circuit]
Next, the sensor element signal detection circuit of the sensor node according to the present embodiment will be described in detail with reference to FIG.
The sensor element signal detection circuit 13 is provided with a zero power sensor circuit 13A and a zero power threshold circuit 13B as main circuits.

  The zero power sensor circuit 13A accumulates charges of the detection signals BP and BN obtained by the sensor electrodes 11D and 11E of the power generation sensor element 11 in the capacitor element CS, thereby having a voltage corresponding to the vibration and acceleration of the target. It is a circuit that outputs an output signal SO.

  FIG. 7 is a configuration example of a zero power sensor circuit. Here, the detection signals BP and BN are input to the connection points of the diodes D11 to D13 connected in series in the forward direction, and the voltage signal output from the cathode terminal of the diode D13 is supplied to the capacitive element CS as the sensor output signal SO. Charged. In the example of FIG. 7, a diode is formed by a MOS transistor, but a PN diode may be used. The configuration of the zero power sensor circuit 13A is the same as that disclosed in Patent Document 2.

  The zero power threshold circuit 13B is a circuit that detects whether or not the sensor output signal SO has reached a threshold value Vth that is a potential indicating the presence of vibration. FIG. 8 is a configuration example of a zero power sensor circuit. Here, the source terminal of the transistor Q1 made of a PMOS transistor is connected to the operating power supply VDD, the drain terminal of the transistor Q1 is connected to the drain terminal of the transistor Q2 made of an NMOS transistor, and the source terminal of the transistor Q2 is connected to the ground potential GND. The capacitive element CO is connected between the drain terminal and the source terminal of the transistor Q2.

  Further, the sensor output signal SO from the zero power sensor circuit 13A is input to the gate terminal of the transistor Q1, and the resistance elements R11 and R12 connected between the operating power supply VDD and the ground potential GND are connected to the gate terminal of the transistor Q2. The threshold value Vth generated by the voltage divider circuit is input. Further, the voltage across the capacitive element CO is input to the inverter INV, and its inverted logic is output as the control signal OUT.

Therefore, at time T0, when the sensor output signal SO is at the ground potential GND that is the initial voltage, the transistor Q1 is in the on state, and the source-drain current of the transistor Q1 becomes larger than that of the transistor Q2. For this reason, the charge from the operating power supply VDD is charged in the capacitive element CV, and the low-level control signal OUT is output.
Thereafter, when the vibration continues and the voltage of the sensor output signal SO increases and the gate terminal voltage of the transistor Q1 of the zero power threshold circuit 13B increases, the transistor Q1 approaches the off state.

On the other hand, since the drain-source current of the transistor Q2 is set to about sub-microamperes, the source of the transistor Q1 is reached when the voltage of the sensor output signal SO, that is, the gate terminal voltage of the transistor Q1 reaches the threshold value Vth. The drain-to-drain current becomes smaller than that of the transistor Q2, and the charge charged in the capacitive element CV starts to flow to the transistor Q2.
As a result, the voltage across the capacitive element CV decreases, and after the discharge time determined by the capacitance value of the capacitive element CV and the drain-source current value of the transistor Q2, it becomes the ground potential GND, and the control signal output from the inverter INV OUT is inverted to High level.

  In this way, the threshold power operation using the differential voltage Vd as the logical threshold is performed in the zero power threshold circuit 13B. Therefore, when the voltage of the sensor output signal SO exceeds the differential voltage Vd, the control signal OUT is inverted from the Low level to the High level, the switch SW2 of the power storage circuit 12 is turned on, and the operating power supply VDD is the wireless circuit 14. Supplied to.

[Operation of First Embodiment]
Next, the operation of the sensor node according to the present embodiment will be described with reference to FIG. FIG. 9 is a signal waveform diagram showing the operation of the sensor node.

  When the movable body 11A of the power generation sensor element 11 is displaced in the vertical direction Z due to the external vibration applied to the sensor node 10, a charge is induced in the power generation electrode 11C, and the generated voltage signal BV is output to the power storage circuit 12. .

  The voltage signal BV is rectified by the rectifier circuit 12A of the power storage circuit 12 and charged to the capacitor element CV as the operation power supply VDD. Therefore, when the vibration continues and the operating power supply VDD rises to the lower limit threshold VL, the switch SW1 is turned on by the voltage detection circuit 12C, and the operating power supply VDD is supplied to the sensor element signal detection circuit 13. When the operating power supply VDD rises to the upper limit threshold value VH, the voltage limiting circuit 12B limits the operating power supply VDD to the upper limit threshold value VH, and the circuit is protected from a high voltage.

  On the other hand, when the movable body 11A of the power generation sensor element 11 is displaced in the horizontal direction X due to external vibration applied to the sensor node 10, detection signals BP and BN having opposite phases are generated in the sensor electrodes 11D and 11E.

  As shown in FIG. 9, it is assumed that the voltage of the capacitive element CS is equal to the ground potential GND at time T0, which is the start time of the detection period. Thereafter, when external vibration having a constant frequency is applied to the sensor node 10, the voltages of the detection signals BP and BN output from the power generation sensor element 11 change according to the external vibration. At this time, since the charges charged in the variable capacitance elements CP and CN of the power generation sensor element 11 by one vibration are constant, the capacitance C and the voltage V are calculated based on the relationship of charge Q = capacitance C × voltage V. Is inversely proportional.

  For this reason, when the distance between the movable body 11A and the sensor electrode 11D is increased by a single vibration and the capacitance C of the variable capacitance element CP is decreased, the voltage of the detection signal BP is increased, and the distance is decreased and the variable capacitance element is decreased. As the capacitance C of the CP increases, the voltage of the detection signal BP decreases. This also applies to the relationship between the variable capacitance element CN composed of the movable body 11A and the sensor electrode 11E and the detection signal BN.

  At this time, since the variable capacitance elements CP and CN have a target structure, the detection signals BP and BN are signals having opposite phases as shown in FIG. Note that the waveforms of the detection signals BP and BN are actually curved according to the state of the external vibration, but in order to facilitate the explanation of the circuit operation, the detection signals BP and BN are rectangular waveforms in FIG. It is shown.

The detection signals BP and BN thus generated are output from the power generation sensor element 11 to the sensor element signal detection circuit 13 and input to the zero power sensor circuit 13A.
The diodes D11 to D13 of the zero power sensor circuit 13A become conductive when the voltage difference between both ends becomes equal to or higher than the threshold voltage Vt. For this reason, the diode D11 becomes conductive when the voltage of the detection signal BP decreases by Vt or more from the operating power supply VDD, and the diode D12 becomes conductive when the voltage of the detection signal BN decreases by Vt or more than the voltage of the detection signal BP. The diode D13 is turned on when the voltage of the signal BN increases by Vt or more from the voltage of the fixed capacitor CS, that is, the voltage of the sensor output signal SO.

For this reason, the diodes D11, D13 and the diode D12 are alternately conducted in accordance with the repetition of the external vibration, so that charges from the operating power supply VDD are sequentially transmitted to the capacitive element CS via the diodes D11 to D13 and charged. Is done.
Therefore, in the period ΔT1 from time T0 to time T1, the voltage of the sensor output signal SO has not reached the threshold voltage Vth of the zero power threshold circuit 13B. A control signal OUT indicating an off state is output.

  On the other hand, at time T1, when the voltage of the sensor output signal SO reaches the threshold voltage Vth of the zero power threshold circuit 13B, the control signal OUT indicating the ON state of the switch SW2 from the zero power threshold circuit 13B. Is output. As a result, after the period ΔT1 has elapsed from the start of the operation at time T0, the supply of the operating power VDD to the wireless circuit 14 is started via the switch SW2, the wireless circuit 14 is activated, and the wireless radio wave 15 is transmitted. .

  Further, the voltage of the sensor output signal SO depends on the number of repetitions of the detection signals BP and BN. For this reason, the speed at which the voltage of the sensor output signal SO rises changes according to the repetition speed of the detection signals BP and BN, that is, the frequency of external vibration and the magnitude of acceleration.

  FIG. 10 is a signal waveform diagram showing another operation of the sensor node. FIG. 10 shows an example in which external vibration having a frequency lower than that in FIG. 9 is applied to the sensor node 10. In this case, since the frequency of the external vibration is lower than in FIG. 9, the speed at which the voltage of the sensor output signal SO rises is slow, and is longer than the period ΔT1 until the voltage of the sensor output signal SO reaches the threshold value Vth. The period ΔT2 is required.

As a result, the operating power supply VDD is supplied from the power storage circuit 12 to the wireless circuit 14 via the switch SW2 at intervals according to the frequency of external vibration or the magnitude of acceleration, and the radio wave 15 is transmitted according to the interval. It will be.
FIG. 11 is an explanatory diagram showing the operation of the radio circuit. The radio wave 15 is intermittently transmitted with the periods ΔT1 and ΔT2 obtained by the operations of FIGS. 9 and 10 described above as pulse intervals.

  The transmission period length of one radio wave 15 is desirably 1 ms or less, for example. As a result, the power can be reduced to an nW (nanowatt) level smaller than μW. At this time, the transmission period length of the radio wave 15 may be controlled by outputting the control signal OUT output from the zero power threshold circuit 13B only for the transmission period length of the radio wave 15.

  Further, in the zero power threshold circuit 13B, one detection period is ended in response to the completion of the output of the control signal OUT, and the sensor output voltage SO charged to the capacitive element CS of the zero power sensor circuit 13A is reduced to zero power. An initialization operation for the next detection period such as initialization of the control signal OUT charged in the capacitive element CV of the threshold circuit 13B to the ground potential GND may be performed. Note that the transmission period length of the radio wave 15 may be controlled by the radio circuit 14, and in this case, the zero power threshold circuit 13B responds to the notification of the end of transmission of the radio wave 15 from the radio circuit 14. The initialization operation may be performed.

[Effect of the first embodiment]
As described above, in this embodiment, the movable body 11A that requires a relatively large size is combined with the vibration element 11X and the power generation element 11Z so as to be integrated into one power generation sensor element 11. Therefore, the power generation sensor The element 11 can be reduced in size. Thereby, the power generation sensor element 11 can detect the vibration, that is, the movement of the person or the object by the displacement in the horizontal direction X caused by the large vibration generated by the movement of the person or the thing, and the comparison generated on the floor or the wall. The electric power used for the operation of the sensor node can be generated by the displacement in the vertical direction Z due to the weak environmental vibration, and the sensor node 10 can be downsized.

  Further, since the height H along the vertical direction Z is made smaller than the width W along the horizontal direction X for the rod-shaped spring 11G that supports the movable body 11A, the swing of the movable body 11A along the vertical direction Z is greatly increased. can do. Thereby, it is possible to generate electric power with the power generation element 11Z even from relatively weak vibration that causes environmental vibration of the floor or wall. Moreover, even if a large vibration generated by the movement of a person or an object is applied, the swing of the movable body 11A can be suppressed to some extent, and the vibration can be accurately detected.

[Second Embodiment]
Next, a power generation sensor element according to the second embodiment of the present invention will be described with reference to FIG. FIG. 12 is a plan view showing a power generation sensor element according to the second embodiment.
In the first embodiment, one end of the spring 11G is connected to one of the side surfaces of the movable body 11A not facing the sensor electrodes 11D and 11E, and the other end of the spring 11G is connected to the support portion. The case where the movable body 11A is supported by being fixed to 11H has been described as an example.

In the present embodiment, as shown in FIG. 12, one end of the spring 11G is connected to each of two side surfaces of the movable body 11A that are not opposed to the sensor electrodes 11D and 11E, and the other ends of these springs 11G are connected. Is fixed to the support portion 11H to support the movable body 11A.
Accordingly, the movable body 11A is supported from both sides along the horizontal direction Y by the two sets of support portions 11H and the springs 11G provided at positions facing each other across the movable body 11A. The displacement along the direction X can be stabilized.

[Third Embodiment]
Next, a power generation sensor element according to a third embodiment of the present invention will be described with reference to FIG. FIG. 13 is a plan view showing a power generation sensor element according to the third embodiment.
In the present embodiment, as shown in FIG. 13, one end of two sets of springs 11G is placed at a distance from each of two side surfaces of the movable body 11A that are not opposed to the sensor electrodes 11D and 11E. The movable body 11A is supported by connecting each other and fixing the other ends of these springs 11G to the respective support portions 11H.
Accordingly, the movable body 11A is supported from both sides along the horizontal direction Y by the four sets of support portions 11H and the springs 11G provided at positions facing each other across the movable body 11A. The displacement along the direction X can be further stabilized.

[Fourth Embodiment]
Next, a power generation sensor element according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a plan view showing a power generation sensor element according to the fourth embodiment.
In the present embodiment, as shown in FIG. 14, each of the four side surfaces of the movable body 11A is either one side away from the center of the side surface, and is plane view symmetrical with respect to the center of the movable body 11A. The movable body 11A is supported by connecting one end of each spring 11G to a position where the other ends of the spring 11G are fixed to the respective support portions 11H.

In addition, two sets of sensor electrodes 11D and 11E are respectively arranged on the side surfaces of the movable body 11A so as to face portions where the spring 11G is not connected, with the movable body 11A interposed therebetween. In addition, the four sensor electrodes 11 </ b> D and 11 </ b> E are connected in parallel to the sensor element signal detection circuit 20 in the two sensor electrodes that do not output the detection signal having the opposite phase.
Thereby, the displacement of the movable body 11A can be detected not only in the horizontal direction X but also in the horizontal direction Y, and the movement of a person or an object can be accurately detected.

[Fifth Embodiment]
Next, with reference to FIG. 15, a power generation sensor element according to the fifth embodiment of the present invention will be described. FIG. 15 is a plan view showing a spring according to the fifth embodiment.
In the first embodiment, the case where a rod-like spring is used as the spring 11G that supports the movable body 11A has been described as an example.
In the present embodiment, as shown in FIG. 15, a spiral spring 11 </ b> G that is bent along the horizontal direction X is used. Here, as a specific example of the twisted shape, a shape bent in a rectangular wave shape is shown as an example, but it may be bent in a curved wave shape or a triangular wave shape.
Thereby, necessary elasticity can be obtained with a small size, and the spring 11G and further the power generation sensor element 11 can be miniaturized.

[Sixth Embodiment]
Next, with reference to FIG. 16A-FIG. 16D, the electric power generation sensor element concerning the 6th Embodiment of this invention is demonstrated. FIG. 16A is a plan view showing a power generation sensor element according to the sixth embodiment. FIG. 16B is a plan view showing another power generation sensor element according to the sixth exemplary embodiment. FIG. 16C is a plan view showing another power generation sensor element according to the sixth exemplary embodiment. FIG. 16D is a plan view showing another power generation sensor element according to the sixth embodiment.

In the first embodiment, the case where the movable body 11A is supported by connecting one end of the rod-shaped spring 11G to the side surface of the movable body 11A and fixing the other end of the spring 11G to the support portion 11H will be described as an example. did.
In the present embodiment, as shown in FIGS. 16A to 16D, a spiral spring 11G is arranged in a notch portion 11I provided by notching the side surface of the movable body 11A, and the movable body 11A is moved by the spring 11G. I support it. Thereby, the spring 11G and also the power generation sensor element 11 can be reduced in size. The support portion 11H for fixing the spring 11G may be formed in a wall shape surrounding the outer side of the movable body 11A, for example, or may be a columnar shape standing only at a fixing position of the spring 11G.

  For example, in the case of FIG. 16A, the central portion is cut out in a rectangular shape from one side surface of the movable body 11A to form a U-shape in plan view, and the spring 11G is arranged in the cutout portion 11I formed thereby, This spring 11G is connected between the inner surface of the cutout portion 11I of the movable body 11A and the support portion 11H disposed outside the movable body 11A. In addition, sensor electrodes 11D and 11E are arranged at positions facing the two side surfaces of the movable body 11A that are not notched with the movable body 11A interposed therebetween. Thereby, the displacement of the movable body 11A can be increased, and the power generation performance and vibration detection performance can be improved.

  Further, in the case of FIG. 16B, a rectangular shape is cut out from two opposing side surfaces of the movable body 11A to form an H shape in plan view, and a spring 11G is provided in each of the two cutout portions 11I formed thereby. This spring 11G is connected between the inner surface of the cutout portion 11I of the movable body 11A and the support portion 11H disposed on the outer side of the movable body 11A. In addition, sensor electrodes 11D and 11E are arranged at positions facing the two side surfaces of the movable body 11A that are not notched with the movable body 11A interposed therebetween. Thereby, the displacement of the movable body 11A can be increased, the power generation performance and the vibration detection performance can be improved, and the displacement along the horizontal direction X of the movable body 11A can be stabilized by the two springs 11G. it can.

  Further, in the case of FIG. 16C, four portions from two opposing side surfaces of the movable body 11A are cut out in a rectangular shape to form a king-shaped shape in plan view, and a spring is formed in each of the four cutout portions 11I formed thereby. 11G is arranged, and this spring 11G is connected between the inner surface of the notch 11I of the movable body 11A and the support 11H disposed on the outer side of the movable body 11A. In addition, sensor electrodes 11D and 11E are arranged at positions facing the two side surfaces of the movable body 11A that are not notched with the movable body 11A interposed therebetween. Thereby, the displacement of the movable body 11A can be increased, the power generation performance and the vibration detection performance can be improved, and the displacement along the horizontal direction X of the movable body 11A can be further stabilized by the four springs 11G. Can do.

  In the case of FIG. 16D, the four corners of the movable body 11A are cut out in a rectangular shape to form a substantially cross shape in plan view, and springs 11G are respectively attached to the four cutout portions 11I formed thereby. The spring 11G is connected between the inner surface of the cutout portion 11I of the movable body 11A and the support portion 11H disposed on the outer side of the movable body 11A. In addition, sensor electrodes 11D and 11E are arranged at positions facing the two side surfaces of the movable body 11A that are not notched with the movable body 11A interposed therebetween. Thereby, the displacement of the movable body 11A can be increased, the power generation performance and the vibration detection performance can be improved, and the displacement of the movable body 11A can be detected not only in the horizontal direction X but also in the horizontal direction Y. It is possible to accurately detect the movement of people and things.

[Seventh Embodiment]
Next, a power generation sensor element according to a seventh embodiment of the present invention will be described with reference to FIGS. 17A and 17B. FIG. 17A is a plan view showing a power generation sensor element according to a seventh embodiment. 17B is a cross-sectional view taken along the line BB in FIG. 17A.

In the first embodiment, the case where the movable body 11A is supported by connecting one end of the rod-shaped spring 11G to the side surface of the movable body 11A and fixing the other end of the spring 11G to the support portion 11H will be described as an example. did.
In the present embodiment, a weight 11J is disposed on the upper surface of the movable body 11A. Thereby, the resonance frequency of the movable body 11A can be adjusted by the weight of the weight 11J, and the sensitivity of vibration detection suitable for the efficiency of power generation and the frequency of vibration to be detected can be adjusted.

[Eighth Embodiment]
Next, with reference to FIG. 18A and FIG. 18B, the electric power generation sensor element concerning the 8th Embodiment of this invention is demonstrated. FIG. 18A is a plan view showing a power generation sensor element according to the eighth embodiment. 18B is a cross-sectional view taken along the line AA in FIG. 18A.

In 1st Embodiment, the case where the plate-shaped rectangular parallelepiped movable body 11A was used as the movable body 11A was described as an example.
In the present embodiment, a wall-like edge portion 11K that is higher than the thickness of the movable body 11A is provided on the upper surface periphery of the movable body 11A. The edge portion 11K may be provided over the entire circumference of the upper surface peripheral portion of the movable body 11A, or may be provided only at a position facing at least the sensor electrodes 11D and 11E. Thereby, the area facing the sensor electrodes 11D and 11E on the side surface of the movable body 11A is increased, the capacity of the variable capacitors CP and CN can be increased, and the vibration detection sensitivity can be increased.

[Ninth Embodiment]
Next, with reference to FIG. 19A and FIG. 19B, the electric power generation sensor element concerning the 9th Embodiment of this invention is demonstrated. FIG. 19A is a plan view showing a power generation sensor element according to the ninth embodiment. 19B is a cross-sectional view taken along the line AA in FIG. 19A.

  In the present embodiment, a wall-like edge portion 11K that is higher than the thickness of the movable body 11A is provided on the peripheral surface of the lower surface of the movable body 11A. The edge portion 11K may be provided over the entire circumference of the lower surface periphery of the movable body 11A, or may be provided only at a position facing at least the sensor electrodes 11D and 11E. Thereby, the area facing the sensor electrodes 11D and 11E on the side surface of the movable body 11A is increased, the capacity of the variable capacitors CP and CN can be increased, and the vibration detection sensitivity can be increased. Further, the height of the power generation sensor element 11 can be made lower than that in FIG. 18, and the sensor node 10 can be downsized. Moreover, you may arrange | position the charging body 11B inside the recessed part formed in the lower surface of 11 A of movable bodies by the edge part 11K. Thereby, power generation efficiency can be improved.

[Tenth embodiment]
Next, with reference to FIG. 20A-FIG. 20C, the electric power generation sensor element concerning the 10th Embodiment of this invention is demonstrated. FIG. 20A is a plan view showing a power generation sensor element according to the tenth embodiment. 20B is a cross-sectional view taken along the line AA in FIG. 20A. 20C is a cross-sectional view taken along the line BB in FIG. 20A.

In the present embodiment, the power generation sensor element 11 is formed on a printed circuit board 11L as an implementation example of the first to ninth embodiments described above.
Glass, Teflon (registered trademark), ethylene tetrafluoroethylene (ETFE) film, acetate film (trade name: mending tape, etc.) as the charging body 11B on the power generation electrode 11C formed in the wiring pattern on the printed board 11L A dielectric such as polypropylene (OPP) film (trade name: Diahalo tape, etc.) is disposed, and a high voltage is applied by an electrostatic charging device.

  The sensor electrodes 11D and 11E are fixed on the printed circuit board 11L by bending a thin metal plate into an L shape, and connected to the wiring pattern 11M by soldering or the like. The movable body 11A and the spring 11G are integrally formed by etching or punching using a thin metal as a material, and then bending at least the end portions of the movable body 11A facing the sensor electrodes 11D and 11E. Thus, the edge portion 11K protruding downward in the shape of a wall is formed.

  In addition, the support portion 11H stands on a printed board 11L with a metal column and is connected to the wiring pattern 11M, and fixes one end of the spring 11G to the upper end thereof by soldering or the like. At this time, for the support portion 11H, a circuit component such as a thin battery in which the ground potential is exposed may be used. Further, the spring 11G may be formed in a folded shape that is bent along the horizontal direction X as in the fifth embodiment described above. Further, as in the second to fourth embodiments described above, the movable body 11A may be supported by forming a plurality of springs 11G integrally with the movable body 11A. Furthermore, as in the above-described sixth embodiment, the notch 11I may be provided in the movable body 11A, and the spring 11G may be formed in the notch 11I.

  As described above, in the present embodiment, the power generation sensor element 11 is assembled by disposing each component formed by processing a thin metal plate on the printed board 11L. The power generation sensor element 11 can be configured at a very low cost.

[Eleventh embodiment]
Next, a power generation sensor element according to the eleventh embodiment of the present invention will be described with reference to FIG. FIG. 21 is a sectional view showing a power generation sensor element according to the eleventh embodiment.
In the present embodiment, the power generation sensor element 11 is formed on the substrate 11U of the IC chip as an implementation example of the first to ninth embodiments described above.

  By laminating the metal plating film, the movable body 11A, the spring 11G (not shown), the support portion 11H (not shown), the sensor electrodes 11D and 11E, and the power generation electrode 11C are formed. The charged body 11B can be formed on the substrate 11U with the insulating film 11N interposed therebetween by forming silicon dioxide or Teflon by spin coating or the like, etching it, and then applying a high voltage with an electrostatic charging device. The sensor electrodes 11D and 11E and the power generation electrode 11C are connected to a wiring using a via 11O penetrating the insulating film 11N. Thereby, since the electric power generation sensor element 11 can be formed on the board | substrate 11U of an IC chip, a sensor node can be reduced in size significantly compared with the printed circuit board 11L.

[Twelfth embodiment]
Next, a power generation sensor element according to the twelfth embodiment of the present invention will be described with reference to FIG. FIG. 22 is a sectional view showing a power generation sensor element according to the twelfth embodiment.
In the present embodiment, the power generation sensor element 11 is formed on a support substrate 11P of an IC chip as an implementation example of the first to ninth embodiments described above.

A support substrate 11P different from the IC chip substrate 11U is provided, and a charged body 11B is formed on the support substrate 11P. At this time, the support portion 11R having a laminated structure of metal plating films formed on the substrate 11U with the insulating film 11N interposed therebetween and the support portion 11S formed on the support substrate 11P with the insulating film 11Q interposed therebetween are electrically conductive adhesives. 11T is connected.
In the eleventh embodiment, since it is necessary to form the charged body 11B in the process of forming the metal plating film, there is a problem that the charge amount is deteriorated depending on the material of the charged body 11B. According to the present embodiment, since the charged body 11B can be formed independently of the laminated structure of the metal plating film, the charge amount does not deteriorate and the power generation amount can be increased.

[Extended embodiment]
The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. In particular, the configurations of the power generation sensor elements 11 described in the second to thirteenth embodiments may be arbitrarily combined.

  DESCRIPTION OF SYMBOLS 10 ... Sensor node, 11 ... Power generation sensor element, 11A ... Movable body, 11B ... Charged body, 11C ... Power generation electrode, 11D, 11E ... Sensor electrode, 11F ... Substrate, 11G ... Spring, 11H ... Support part, 11I ... Notch 11J: Weight, 11K ... Edge, 11L ... Printed circuit board, 11M ... Wiring pattern, 11N ... Insulating film, 11O ... Via, 11P ... Supporting board, 11Q ... Insulating film, 11R ... Supporting part, 11S ... Supporting part, 11T ... conductive adhesive, 11U ... substrate, 11X ... vibrating element, 11Z ... electric power generating element, 12 ... electric storage circuit, 12A ... rectifier circuit, 12B ... voltage limiting circuit, 12C ... voltage detection circuit, 13 ... sensor element signal detection circuit , 13A ... Zero power sensor circuit, 13B ... Zero power threshold circuit, 14 ... Radio circuit, 15 ... Radio wave, CV, CP, CN ... Variable capacitance, D1, D2, 11, D12, D13 ... Diode, CV, CS, CO ... Capacitance element, SW, SW1, SW2 ... Switch, R, R1, R2 ... Resistance element, Q1 ... Transistor (PMOS), Q2 ... Transistor (NMOS), BV ... Voltage signal, BP, BN ... detection signal, VDD ... operating power supply, SO ... sensor output signal, OUT ... control signal.

Claims (16)

A power generation electrode made of a thin metal plate formed on a substrate;
A charged body disposed on the power generation electrode;
A support portion fixed on a peripheral position of the power generation electrode on the substrate;
An elastic spring having one end fixed to the upper end of the support;
A movable body made of a thin metal, connected to the other end of the spring, and supported above the charged body so as to vibrate at a position horizontally facing the charged body;
Two sensor electrodes made of a thin metal plate standing on the substrate at a position around the power generation electrode and facing each other across the movable body,
When the vibrating element composed of the movable body and the electric sensor electrode is displaced in the X direction parallel to the substrate surface in accordance with vibration applied from the outside, the movable element and the sensor electrode are disposed between the movable body and the sensor electrode. The two capacitances generated in the two are changed, and the detection signals having opposite phases to each other whose amplitude changes according to the displacement are output from the two sensor electrodes, respectively.
A power generation element composed of the movable body, the charged body, and the power generation electrode is induced in the power generation electrode when the movable body is displaced in the Z direction perpendicular to the substrate surface in response to externally applied vibration. The power generation sensor element, wherein the generated electric charge is changed and a voltage signal whose amplitude is changed according to the displacement is output from the power generation electrode. The power generation sensor element according to claim 1,
The power generation sensor element, wherein the spring has a width in the Z direction smaller than a width in the X direction. The power generation sensor element according to claim 1 or 2,
The power generation sensor element, wherein the movable body is supported by one spring. The power generation sensor element according to claim 1 or 2,
The power generation sensor element characterized in that the movable body is supported by two springs connected across the movable body along a Y direction perpendicular to the X direction in parallel with the substrate surface. . The power generation sensor element according to claim 1 or 2,
The movable body is supported by four springs that are connected two by two across the movable body along a Y direction orthogonal to the X direction in parallel with the substrate surface. Power generation sensor element. The power generation sensor element according to claim 1 or 2,
The power generation sensor element, wherein the movable body is supported by the four springs connected to a position that is symmetrical with respect to a plane view with respect to the center of the movable body. In the electric power generation sensor element as described in any one of Claims 1-6,
The power generation sensor element according to claim 1, wherein the spring has a folded shape. The power generation sensor element according to claim 7,
The power generation sensor element, wherein the spring is disposed in a notch provided in the movable body. In the electric power generation sensor element as described in any one of Claims 1-8,
The power generation sensor element, wherein the movable part has a weight for adjusting a resonance frequency of the displacement. In the electric power generation sensor element as described in any one of Claims 1-9,
The movable portion is a peripheral portion of the upper surface or the lower surface, and has a wall-shaped edge portion higher than the thickness of the movable portion at least at a position facing the sensor electrode,
The power generation sensor element, wherein the sensor electrode is disposed at a position facing the edge. In the electric power generation sensor element as described in any one of Claims 1-9,
The movable part has a wall-like edge that is higher than the thickness of the movable part over the entire circumference of the lower surface.
The sensor electrode is disposed at a position facing the edge,
At least a part of the charged body is disposed inside a concave portion formed on the lower surface of the movable portion by the edge portion. In the electric power generation sensor element as described in any one of Claims 1-9,
The movable portion and the spring are integrally formed by processing a thin plate metal, and projecting upward or downward in a plate shape by bending at least an end portion of the movable portion facing the sensor electrode. A power generation sensor element characterized in that an edge is formed. In the electric power generation sensor element as described in any one of Claims 1-9,
The substrate is a printed circuit board,
The power generation electrode consists of a wiring pattern formed on the substrate,
The sensor electrode is erected on the printed board by bending a sheet metal into an L shape,
The movable portion and the spring are integrally formed by processing a thin plate metal, and projecting upward or downward in a plate shape by bending at least an end portion of the movable portion facing the sensor electrode. A power generation sensor element characterized in that an edge is formed. The power generation sensor element according to any one of claims 1 to 13,
A power storage circuit that generates an operating power source by storing electric charges output from the power generation electrode of the power generation sensor element;
The sensor is activated by the operating power supplied from the power storage circuit, and a sensor output signal is generated by accumulating charges output as the detection signal from the sensor electrode of the power generation sensor element. A sensor element signal detection circuit that outputs a comparison result compared with a threshold value as an output signal;
A sensor node, comprising: a radio circuit that operates based on the operation power supplied from the power storage circuit according to the output signal and transmits radio waves. The sensor node according to claim 14, wherein
The storage circuit is
A rectifier circuit for rectifying the electric charge output from the power generation electrode;
A capacitor element that stores the electric charge rectified by the rectifier circuit and generates the operation power supply;
A voltage limiting circuit for limiting the voltage rise of the operating power supply to an upper threshold,
A voltage detection circuit that turns on a first switch and supplies the operation power supply to the sensor element signal detection circuit during a period in which the voltage of the operation power supply rises above a lower threshold;
A sensor node comprising: a second switch that supplies the operation power to the sensor element signal detection circuit by turning on in response to the output signal. The sensor node according to claim 14, wherein
The sensor element signal detection circuit includes:
A sensor circuit that operates according to the operating power supplied via the first switch and generates the sensor output signal by accumulating the charge output as the detection signal;
A threshold circuit that operates according to the operating power supplied via the first switch and outputs a comparison result obtained by comparing the sensor output signal with a threshold value as an output signal. Sensor node to perform.

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