JP2013079828A - Rainfall sensor and rainfall measuring method - Google Patents

Abstract

A rain sensor capable of reducing the overall size of the apparatus and improving the measurement accuracy of the rainfall is provided.
The pressure sensor includes a grid. A plurality of pressure sensitive elements are arranged on the grid. Each pressure sensitive element outputs an electrical signal at a level corresponding to the pressure received from the outside. One pressure sensitive element is smaller in size than the lower limit of the raindrop size. The pressure sensor detects the pressure distribution on the grid when a drop of raindrops collides with the grid. The signal processing unit identifies an area on the grid where a drop of raindrop collides from the pressure distribution. The signal processing unit further calculates the size of one drop of raindrops from the magnitude of the impact received in the area.
[Selection] Figure 2

Description

  The present invention relates to a technique for measuring rainfall.

  Some conventional rain gauges store rain water in a water storage tank such as a cylinder and measure the amount of stored water. In addition, a rain gauge that does not use a water tank, such as a precipitation sensor disclosed in Patent Document 1, is also known. The precipitation sensor measures the impact of raindrops and the like on the precipitation sensor by measuring the sound or vibration generated when the falling raindrops and the like collide. Furthermore, the amount of precipitation is identified from the magnitude of the impact.

JP-A-10-260269

  In a rain gauge of the type that uses a water tank, the water tank is bulky, so it is difficult to downsize the entire rain gauge. On the other hand, since Patent Document 1 does not specifically disclose the relationship between the impact of raindrops and precipitation and precipitation, Patent Document 1 does not know how to improve the measurement accuracy of precipitation.

  An object of the present invention is to provide a rainfall sensor capable of further downsizing the entire apparatus and further improving the measurement accuracy of rainfall.

  The rainfall sensor according to the present invention includes a pressure sensor and a signal processing unit. The pressure sensor includes a grid. A plurality of pressure sensitive elements are arranged on the grid. Each pressure sensitive element outputs an electrical signal at a level corresponding to the pressure received from the outside. One pressure sensitive element is smaller in size than the lower limit of the raindrop size. The pressure sensor detects the pressure distribution on the grid when a drop of raindrops collides with the grid. The signal processing unit identifies an area on the grid where a drop of raindrop collides from the pressure distribution. The signal processing unit further calculates the size of one drop of raindrops from the magnitude of the impact received in the area.

  The rain sensor according to the present invention uses a grid to calculate the amount of rain from the magnitude of the impact of a single drop of rain on the grid. Therefore, it is possible to further reduce the size of the entire apparatus and further improve the measurement accuracy of rainfall.

It is a block diagram of the rainfall sensor by embodiment of this invention. FIG. 2 is a schematic exploded view showing a specific structure of the rainfall sensor 100 shown in FIG. 1. (A) is one sectional drawing of the pressure sensitive element 110 shown by FIG. FIG. 3B is a circuit diagram of the pressure sensor 101 shown in FIG. (A) is a schematic diagram showing a state when raindrops RD1 and RD2 fall perpendicularly to the surface of the grid. (B) is a top view which represents typically the pressure distribution which arises on the surface of the grid shown by (a). (A) is a schematic diagram which shows a mode when raindrops RD3 and RD4 fall diagonally with respect to the surface of a grid. (B) is a top view which represents typically the pressure distribution which arises on the surface of the grid shown by (a). 6 is a table showing a relationship between a radius and a terminal velocity when a raindrop shape is approximated by a sphere, and a force received by the pressure sensor 101 when the raindrop collides with the pressure sensor 101. It is a flowchart of the rainfall measuring method using the rainfall sensor 100 shown by FIG. FIG. 3 is a block diagram of a rainfall measurement system using an umbrella 801 including the rainfall sensor 100 shown in FIG. 2. FIG. 3 is a block diagram of a rain monitoring system using the rainfall sensor 100 shown in FIG. 2. FIG. 3 is a block diagram of an inter-vehicle communication device using the rainfall sensor 100 shown in FIG. 2.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram of a rainfall sensor according to an embodiment of the present invention. Referring to FIG. 1, a rain sensor 100 includes a pressure sensor 101, a signal processing unit 102, a communication unit 103, a vibration power generation unit 104, a power control unit 105, and a micro battery 106 (hereinafter referred to as a μ battery). including.

  The pressure sensor 101 includes a two-dimensional array of a plurality of pressure sensitive elements, that is, a grid. The pressure sensor 101 receives raindrops RD at the grid. When raindrops RD collide with the grid, a pressure distribution is generated on the grid. The pressure sensor 101 generates an electric signal PD indicating the pressure distribution and sends it to the signal processing unit 102. First, the signal processing unit 102 analyzes the electrical signal PD, and identifies an area on the grid where a drop of raindrops collided from the pressure distribution. Next, the signal processing unit 102 calculates the size of one drop of raindrops from the magnitude of the impact received in the area. The signal processing unit 102 further sends information RI indicating the size of each raindrop colliding with the grid to the communication unit 103. The communication unit 103 includes a film antenna 131, and uses the film antenna 131 to wirelessly send information RI sent from the signal processing unit 102 to an external device such as a mobile phone or a personal computer. The external device calculates the rainfall from the size of the raindrops indicated by the information RI.

  The vibration power generation unit 104 includes a plate-like member that can vibrate up and down and an electret. An electrode is fixed to the plate member. The electret is installed at a predetermined distance from the electrode. The vibration power generation unit 104 receives raindrops RD with a plate-like member. When the raindrop RD collides with the plate member, the plate member vibrates up and down. Accordingly, the electrode fixed to the plate member vibrates with respect to the electret. At that time, an electromotive force PW is generated in the electrode. The electromotive force PW is transmitted to the power supply control unit 105. The power supply control unit 105 charges the μ battery 106 using the electromotive force PW. The μ battery 106 has a built-in lithium battery and stores the power PW generated by the vibration power generation unit 104. The μ battery 106 further supplies the accumulated power to the pressure sensor 101, the signal processing unit 102, and the communication unit 103. In FIG. 1, the signal flow is indicated by solid arrows, and the power flow is indicated by broken arrows.

  FIG. 2 is a schematic exploded view showing a specific structure of the rainfall sensor 100 shown in FIG. The rainfall sensor 100 is a 2 cm square rectangular chip. The pressure sensor 101, the signal processing unit 102, the communication unit 103, the vibration power generation unit 104, the power control unit 105, and the μ battery 106 are each mounted on one chip and stacked on each other.

  The pressure sensor 101 is installed horizontally on the uppermost layer of the rainfall sensor 100. As a result, the grid is exposed on the surface of the rain sensor 100. Each pressure-sensitive element 110 constituting the grid has a rectangular shape of 0.01 mm square, and its size is sufficiently smaller than the lower limit of 0.1 mm of the raindrop size. The pressure sensitive element 110 outputs an electrical signal at a level corresponding to the pressure received from the outside.

  FIG. 3A is a cross-sectional view of one pressure sensitive element 110. Referring to FIG. 3A, the pressure sensitive element 110 includes a substrate 111, a first electrode 112, a dielectric layer 113, a second electrode 114, and an insulating layer 115. The substrate 111 is a common substrate on which the entire pressure sensor 101 is mounted. The first electrode 112 is formed in a rectangular shape on the surface of the substrate 111. The first electrode 112 is grounded. The dielectric layer 113 covers the entire first electrode 112. The second electrode 114 is disposed in parallel with the first electrode 112 with the dielectric layer 113 interposed therebetween. The second electrode 114 is composed of an electret and holds a certain amount of charge. The insulating layer 115 covers the dielectric layer 113 and the second electrode 114. Raindrops collide with the insulating layer 115. The insulating layer 115 insulates the second electrode 114 from the outside and prevents rainwater from entering the pressure sensitive element 110. When raindrops collide with the insulating layer 115, the dielectric layer 113 is deformed by the impact, and the distance L between the first electrode 112 and the second electrode 114 is reduced. As a result, the capacitance between the first electrode 112 and the second electrode 114 increases. Since the charge held by the second electrode 114 is constant, the voltage between the first electrode 112 and the second electrode 114 decreases. By detecting this voltage drop as an electrical signal, the impact of raindrops can be detected. In particular, the change in the level of the electrical signal represents the magnitude of the raindrop impact.

  FIG. 3B is a schematic diagram illustrating a circuit configuration of the pressure sensor 101. Referring to FIG. 3B, the pressure sensor 101 includes an amplifier circuit 201, a row selector 202, and a column selector 203 in addition to the pressure sensitive element 110. The amplifier circuit 201 is connected to the pressure sensitive element 110 one by one. The amplifier circuit 201 amplifies a change in voltage between the first electrode 112 and the second electrode 114 in the pressure sensitive element 110. One row selector 202 is provided for each column of the pressure-sensitive elements 110, and is connected to the pressure-sensitive elements 110 arranged in that column through the amplifier circuit 201. The row selector 202 receives the row selection signal RSL from the signal processing unit 102, and receives a voltage between the first electrode 112 and the second electrode 114 in the pressure-sensitive element 110 in the row indicated by the signal RSL. The column selector 203 is connected to each row selector 202. The column selector 203 receives the column selection signal CSL from the signal processing unit 102, and receives from the row selector 202 the voltage received from the pressure sensitive element 110 by the row selector 202 of the column indicated by the signal. The column selector 203 further transmits the voltage to the signal processing unit 102 as an electric signal SGL.

  The signal processing unit 102 is disposed below the pressure sensor 101. The signal processing unit 102 scans all the pressure sensitive elements 110 in the pressure sensor 101 at a period of 1/30 second by periodically changing the row selection signal RSL and the column selection signal CSL. Thereby, the pressure distribution obtained by one scan can be considered to be due to raindrops that collided with the grid simultaneously. The shape of the pressure distribution caused by the impact of a drop of raindrops depends on the direction of the speed of the raindrops. The closer the direction of the raindrop velocity is to the normal direction of the grid surface, the closer the shape of the isobaric line is to a perfect circle. On the other hand, when the direction of the speed of raindrops is greatly inclined from the normal direction of the surface of the grid, the shape of the isobaric lines is greatly distorted from the perfect circle in the inclined direction.

  FIG. 4A is a schematic diagram showing a state when raindrops RD1 and RD2 fall perpendicularly to the surface of the grid. In FIG. 4A, the higher the detected pressure, the darker the location of the sensing element 110 that detected the pressure. As shown in FIG. 4A, the sensing element 110 that has collided with a portion close to the center of the raindrops RD1 and RD2 detects a higher pressure. FIG. 4B is a plan view schematically showing a pressure distribution generated on the surface of the grid shown in FIG. In FIG. 4B, as in FIG. 4A, the higher the detected pressure, the darker the location of the sensing element 110 that detected the pressure. As shown in FIG. 4B, the sensing elements S1 and S2 where the centers of the raindrops RD1 and RD2 collide detect the highest pressure, and the pressure is detected with the sensing elements S1 and S2 as the center. The sensing element spreads out in a substantially circular area. In FIG. 4B, the boundary of the region is indicated by broken lines C1 and C2.

  FIG. 5A is a schematic diagram showing a state when raindrops RD3 and RD4 fall obliquely with respect to the surface of the grid. In FIG. 5A, the higher the detected pressure, the darker the location of the sensing element that detected the pressure. As shown in FIG. 5A, the sensing element that collides with the raindrops RD3 and RD4 earlier in one scanning time (1/30 second) detects a higher pressure. FIG. 5B is a plan view schematically showing a pressure distribution generated on the surface of the grid shown in FIG. In FIG. 5 (b), as in FIG. 5 (a), the higher the detected pressure, the darker the location of the sensing element that detected the pressure. As shown in FIG. 5 (b), the sensing elements S3 and S4 that contact the raindrops RD1 and RD2 earliest in one scanning time (1/30 second) detect the highest pressure, The sensing element that has detected the pressure spreads in a teardrop-shaped region. In FIG. 5B, the boundary of the region is indicated by broken lines C3 and C4. As is clear from FIGS. 5A and 5B, the major axis directions D3 and D4 of the teardrop shapes C3 and C4 coincide with the horizontal component direction of the speed of the raindrops RD3 and RD4.

  From the pressure distribution detected by the pressure sensor 101, the signal processing unit 102 is a region C1 in which sensing elements that detect pressure are continuous, as shown in FIG. 4B or FIG. 5B. C2, C3 and C4 are detected. Each area C1-C4 is specified as an area where a drop of raindrops collided. Furthermore, when the identified area is a teardrop shape like the areas C3 and C4 shown in FIG. 5B, the signal processing unit 102 uses the horizontal component of the velocity of the raindrops in the major axis direction. Specify as the direction.

Subsequently, the signal processing unit 102 calculates the sum of the pressures detected by the pressure-sensitive element 110 in each specified region as the force applied to the grid by one drop of raindrops. Here, there is the following relationship between the force and the size of raindrops. FIG. 6 is a table showing the relationship between the radius and the terminal velocity when the raindrop shape is approximated by a sphere, and the force received by the pressure sensor 101 when the raindrop collides with the pressure sensor 101. The term “end speed” refers to the speed when the gravity acting on the raindrops falling in the air and the inertial resistance are balanced. The magnitude of the vertical component of the raindrop velocity may be considered equal to the terminal velocity vf. Terminal velocity vf is: raindrop mass m, gravitational acceleration g = 9.8 [m / s ² ], inertial resistance proportional constant K = 0.3, raindrop cross-sectional area A, and air density ρ = 1.3 [kg / m ³ ] Is represented by the following formula: vf = (mg / KAρ) ^1/2 . For example, when the raindrop radius is 0.5 mm, the density of water is 1.0 × 10 ³ [kg / m ³ ], so the terminal velocity vf is about 4 [m / s]. In the vertical direction, raindrops collide with the pressure sensor 101 at the terminal velocity vf. At this time, the collision time can be regarded as the time R / vf required to travel by the diameter R of the terminal velocity vf from the moment when the raindrop contacts the surface of the pressure sensor 101. Further, it can be considered that the vertical component of the velocity of raindrops decreases from the terminal velocity vf to 0 at the collision time R / vf. Therefore, the force Fs received by the pressure sensor 101 at the time of raindrop collision is expressed by the following equation: Fs = m × (vf−0) / (R / vf) = m × vf ² / R. For example, when the raindrop radius is 0.5 mm, the force Fs received by the pressure sensor 101 is 8.3 × 10 ⁻³ [N]. In this way, the relationship between the raindrop radius and the force Fs shown in the table of FIG. 6 is obtained by calculation. In addition, the relationship may be determined experimentally. The signal processing unit 102 stores the relationship in advance. Therefore, the size of the raindrop can be obtained from the force applied to the grid by a single drop of raindrop using the relationship.

  Furthermore, the value obtained by dividing the length of the major axis of the teardrop shapes C3 and C4 of the pressure distribution shown in FIG. 5B by the collision time R / vf can be regarded as a horizontal component of the velocity of raindrops. On the other hand, the vertical component of the raindrop velocity is the terminal velocity vf. Therefore, the signal processing unit 102 can calculate the angle at which raindrops collide with the grid from the ratio between the horizontal component and the vertical component.

  Referring back to FIG. 2, the vibration power generation unit 104 is disposed in the uppermost layer of the rainfall sensor 100 together with the pressure sensor 101. Thereby, a plate-like member that vibrates up and down is exposed on the surface of the rain sensor 100. The power supply control unit 105 is disposed below the vibration power generation unit 104. A μ battery 106 is disposed under the signal processing unit 102 and the power supply control unit 105. A communication unit 103 is arranged under the μ battery 106. Since the communication unit 103 is located at the lowest layer, the radio wave from the film antenna 104 is emitted to the outside without being disturbed by other layers.

  FIG. 7 is a flowchart of the rainfall measurement method using the rainfall sensor 100 shown in FIG. Processing by this method is started by the activation of the rainfall sensor 100.

  In step S701, the signal processing unit 102 scans the grid of the pressure sensor 101 at a predetermined period, for example, at a period of 1/30 seconds, for a predetermined time. Thereby, the signal processing unit 102 monitors whether or not the pressure sensor 101 newly detects a pressure distribution resulting from the collision of raindrops on the grid before the predetermined time elapses. If the pressure sensor 101 detects a new pressure distribution, the process proceeds to step S702. If not detected, the process ends.

  In step S702, the signal processing unit 102 examines the shape of the pressure distribution on the grid obtained by one scan. Thereby, the signal processing unit 102 detects a region where the sensing element that detects the pressure is continuous in a circular shape or a teardrop shape as a region where a single drop of raindrop collides. In general, a plurality of such areas are detected from the grid. Thereafter, the process proceeds to step S703.

  In step S703, the signal processing unit 102 selects one area detected in step S702, and identifies the direction of the speed of raindrops that collided with the area from the shape of the area. For example, when the boundary of the region is circular as indicated by broken lines C1 and C2 shown in FIG. 4B, the signal processing unit 102 has a vertical direction of the speed of raindrops that collide with the region. Identify the direction. On the other hand, when the boundary of the region has a teardrop shape as indicated by broken lines C3 and C4 shown in FIG. 5B, the signal processing unit 102 determines the major axis directions D3 and D4 of the region as follows. The direction of the horizontal component of the velocity of raindrops that collided with the area is specified. Thereafter, the process proceeds to step S704.

  In step S704, the signal processing unit 102 obtains the sum of the pressures detected by the pressure sensitive elements included in the region selected in step S703. The sum represents the magnitude of the force that the area received from a drop of raindrops. Thereafter, the process proceeds to step S705.

  In step S705, the signal processing unit 102 specifies the raindrop radius corresponding to the force determined in step S704 from the relationship between the raindrop radius and the force Fs shown in the table of FIG. The radius represents the size of the raindrop that has collided with the area selected in step S703. Thereafter, the process proceeds to step S706.

  In step S706, the signal processing unit 102 checks whether or not an area not selected in step S703 remains in the area detected in step S702. If so, the process is repeated from step S703. If not, the process proceeds to step S707.

  In step S707, the signal processing unit 102 notifies the communication unit 103 of the radius of raindrops obtained in step S705 for all the areas detected in step S702. Further, the communication unit 103 notifies the radius of these raindrops to an external device such as a personal computer by radio. Thereafter, the process is repeated from step S701. On the other hand, the external device accumulates the rain amount of each raindrop from the known raindrop radius. Specifically, the volume of a sphere having a known radius is regarded as the raindrop volume. In this way, the rain amount of the entire raindrop detected by the pressure sensor 101 in one scanning time by the signal processing unit 102, for example, 1/30 second is determined.

  FIG. 8 is a block diagram of a rainfall measurement system using the umbrella 801 including the rainfall sensor 100 shown in FIG. Referring to FIG. 8, the system includes an umbrella 801, a mobile phone 802, a network 803, and a server 804. One or more chips on which the rainfall sensor 100 shown in FIG. 2 is mounted are attached to the surface of the umbrella 801. Each time the rainfall sensor 100 scans the pressure sensor 101, the information INF indicating the size of the detected raindrop is transferred from the communication unit 103 to the mobile phone 802 of the person holding the umbrella 801. The cellular phone 802 sends the transferred information INF to the server 804 on the network 803. The server 804 accumulates rainfall from the transferred information INF. Unlike a rain gauge installed at a certain place, the rain sensor 100 can move to various places together with the umbrella 801. Further, the server 804 can simultaneously acquire the information INF from the rainfall sensor 100 attached to the plurality of umbrellas 801. As a result, the rainfall measurement system shown in FIG. 8 can measure the local rainfall distribution in more detail than the system using the existing rain gauge.

  When the rain sensor 100 is attached to the umbrella 801, the rain sensor 100 is generally inclined from the horizontal direction. Therefore, it is necessary to correct the magnitude of the force detected by the pressure sensor 101 according to the inclination. Moreover, since the umbrella 801 moves up and down as the person walks, the magnitude of the force that the pressure sensor 101 receives from the raindrops also varies as the person walks. Accordingly, the rain sensor 100 uses the gyro sensor mounted on the mobile phone 802 to measure the vertical acceleration caused by the walking of the person. The rain sensor 100 further corrects the magnitude of the force detected by the pressure sensor 101 based on the measured acceleration. The gyro sensor may be incorporated in the rain sensor 100.

  FIG. 9 is a block diagram of a rain monitoring system using the rainfall sensor 100 shown in FIG. Referring to FIG. 9, this rain monitoring system includes a rain sensor 100, a monitoring device 901, and a display device 902 such as a television receiver. The rain sensor 100 is installed outdoors, such as a roof of a house, and sends information INF indicating the falling direction and size of the raindrop RD from the communication unit 103 to the indoor monitoring device 901. In response to the acquisition of the information INF, the monitoring device 901 causes the display device 902 to display a message indicating rain. The monitoring device 901 further determines, for example, whether or not rain hits the laundry dried on the veranda from the raindrop falling direction, and determines whether or not rain damages potted flowers from the size of the raindrop. And the result of each determination is displayed on the display device 902.

  FIG. 10 is a block diagram of an inter-vehicle communication device using the rainfall sensor 100 shown in FIG. This inter-vehicle communication device is mounted on a vehicle, and performs communication with the inter-vehicle communication device mounted on another vehicle. Using this communication, a plurality of automobiles are connected via a network. As a result, information such as traffic congestion, weather, road surface conditions, traffic accidents, etc. encountered by a single vehicle is also transmitted to a distant vehicle. By sharing such information, it is possible to further ensure safety.

  Referring to FIG. 10, the inter-vehicle communication device includes a rainfall sensor 100, a monitoring unit 1001, a receiving unit 1002, a demodulating unit 1003, a control unit 1004, a modulating unit 1005, and a transmitting unit 1006. The rain sensor 100 is installed on the roof or bonnet of an automobile and sends information INF indicating the size of raindrops from the communication unit 103 to the monitoring unit 1001. The monitoring unit 1001 notifies the control unit 1004 of rain according to the information INF. The monitoring unit 1001 further notifies the modulation unit 1005 of the size of the raindrops. The receiving unit 1002 receives signals from other automobiles and passes them to the demodulating unit 1003. The demodulator 1003 decodes information from the signal received by the receiver 1002 and passes it to the controller 1004. The control unit 1004 processes the information decoded by the demodulation unit 1003. The control unit 1004 also generates information to be transmitted to other automobiles and passes it to the modulation unit 1005. In addition, when rain is notified from the monitoring unit 1001, the control unit 1004 closes the window and activates the wiper. The modulation unit 1005 modulates the carrier wave with the information generated by the control unit 1004. Here, since the frequency of the carrier wave belongs to the terahertz band and the wavelength of the carrier wave is close to the size of raindrops, rain attenuation tends to occur. “Rain attenuation” means that radio waves are absorbed by raindrops or reflected and attenuated. For the purpose of preventing rain attenuation, the modulation unit 1005 adjusts the frequency of the carrier wave according to the size of the raindrops notified from the monitoring unit 1001. The transmission unit 1006 transmits the carrier wave modulated by the modulation unit 1005.

  As shown in FIG. 2, the rainfall sensor 100 according to the embodiment of the present invention is integrated on one chip. Thereby, for example, as shown in FIG. 8, the rainfall sensor 100 can be carried by being attached to the umbrella 801. Thus, the rainfall sensor 100 is small. On the other hand, the rainfall sensor 100 measures the size of each raindrop that collides with the pressure sensor 101, as shown in FIGS. Thereby, the rainfall sensor 100 accumulates the rainfall in units of raindrops. Therefore, the measurement accuracy of the rainfall by the rainfall sensor 100 is high.

  <Modification>

  In the structure shown in FIG. 2, the rainfall sensor 100 is a three-dimensional integrated circuit in which a plurality of chips are stacked. In addition, a structure in which these chips are two-dimensionally arranged may be used.

  In the structure shown in FIG. 2, the rainfall sensor 100 uses the vibration power generation unit 104 to obtain power from the kinetic energy of raindrops. In addition, the rain sensor 100 may obtain power from sunlight using a solar cell. Further, the rainfall sensor 100 may obtain power from a battery or a commercial power source.

  The present invention relates to a technique for measuring rainfall, and as described above, measures the size of a drop of raindrops using a pressure sensor. Thus, the present invention is clearly industrially applicable.

100 Rain sensor
101 Pressure sensor
102 Signal processor
103 Communications department
104 Vibration generator
105 Power control unit
106 μ battery
110 Pressure sensitive element
131 Film antenna

Claims (7)

A pressure-sensitive element that outputs an electrical signal at a level corresponding to the pressure received from the outside, and includes a grid in which a plurality of pressure-sensitive elements having a size smaller than the lower limit of the size of raindrops are arranged, and a single drop is placed on the grid A pressure sensor for detecting a pressure distribution on the grid when raindrops collide; and
From the pressure distribution, a region on the grid where the drop of raindrops has collided is identified, and a signal processing unit that calculates the size of the drop of raindrops from the magnitude of impact received by the region,
Rain sensor equipped with.   The rainfall sensor according to claim 1, wherein the signal processing unit specifies a direction of a speed of the drop of raindrop when the drop of raindrop collides with the area from the shape of the area. A vibration power generation unit that includes a member that vibrates in response to raindrop impact, and converts the vibration of the member into electric power;
A power storage unit that includes a secondary battery and stores power using the secondary battery; and
A power supply control unit that charges the secondary battery using the power converted by the vibration power generation unit;
Further comprising
The signal processing unit is driven by electric power stored in the power storage unit,
The rainfall sensor according to claim 1. A communication unit that communicates with an external device wirelessly;
The signal processing unit acquires information on the inclination or speed of the grid from an external device through the communication unit, and corrects the pressure distribution using the information.
The rainfall sensor according to claim 1. A pressure-sensitive element that outputs an electrical signal at a level corresponding to the pressure received from the outside, and receives the raindrops in a grid in which a plurality of pressure-sensitive elements having a size smaller than the lower limit of the size of the raindrops are arranged. Detecting a pressure distribution on the grid when a drop of raindrops collides with
Identifying the area on the grid from which the drop of raindrops has collided from the pressure distribution;
Calculating the size of the drop of raindrops from the magnitude of impact received by the area; and
Calculating the amount of rain from the size of the drop of raindrops;
A method for measuring rainfall. Identifying the direction of velocity of the drop of raindrop when the drop of raindrop hits the region from the shape of the region;
The rainfall measurement method according to claim 5, further comprising: Obtaining information about the tilt or speed of the grid from an external device; and
Correcting the pressure distribution using the information;
The rainfall measurement method according to claim 5, further comprising:

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