Raindrop detection device, raindrop detection method, and raindrop detection program

Abstract

To provide a raindrop detection device, a raindrop detection method, and a raindrop detection program which can correctly detect even a small amount of rainfall from the beginning of rainfall.SOLUTION: A raindrop detection device 10 comprises: an LED 11; a photodiode 14; a microcomputer 20; and an LED flashing circuit 22. The LED 11 emits light in a prescribed direction. The photodiode 14 is arranged at a position that is opposed to the LED 11 and receives light emitted from the LED 11. The microcomputer 20 detects raindrops passing through a space between the LED 11 and the photodiode 14 according to a change in a reception amount of light received by the photodiode 14. The LED flashing circuit 22 controls turn-on and turn-off of the light emitted from the LED 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a raindrop detection device, a raindrop detection method, and a raindrop detection program. [Background technology]

[0002] Conventionally, to measure rainfall, a tipping bucket rain gauge has been used, which is equipped with a receiver that receives falling rainwater, a filter into which the rainwater received in the receiver drips, and a tipping bucket that tips over to collect the rainwater dripping from the filter. For example, Patent Document 1 discloses a tipping bucket rain gauge that can continuously and accurately measure rainwater even when the rainfall value increases, does not require regular maintenance work, and is easy to operate.The tipping bucket rain gauge is composed of a first filter that is inclined with respect to the falling direction of rainwater received from the receiver and is shaped like a gutter to change the flow direction of rainwater received from the receiver and to receive and channel the rainwater; and a second filter that is inclined with respect to the falling direction of rainwater received from the first filter and has a bottomless container-like portion with an opening at the outflow end that covers the periphery of the outflow end of the first filter and is formed with a receiving end, changing the flow direction of rainwater flowing from the first filter toward the tipping bucket and causing the rainwater flowing from the first filter to drip into the tipping bucket.

[0003] Patent document 2 also discloses a droplet sensor with a simple configuration that has a wide detection area and high sensitivity, in which an optical cover formed from part of a spheroid with the long axis of the spheroid as its vertical axis has an effective detection area between a light receiving and emitting unit and a reflecting unit, the effective detection area satisfies the total reflection condition at the interface with the gas but does not satisfy the total reflection condition at the interface with the liquid, and the reflecting unit reflects light that is totally reflected in the effective detection area to the light receiving surface of the light receiving and emitting unit, or reflects light that is directly incident on the reflecting unit from the light receiving and emitting unit to the effective detection area. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Application Publication No. 2019 / 216184 [Patent Document 2] Japanese Patent Publication No. 2020-8505 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-described conventional configuration has the following problems. That is, the tipping bucket rain gauge disclosed in the above-mentioned Patent Document 1 is a type that tips over when it detects a rainfall equivalent to 0.5 mm, so it is difficult to detect raindrops when the rainfall is less than 0.5 mm. Also, since it takes time for the tipping bucket to tip over after the rain starts to fall, there is also the problem that the timing for detecting the start of rain is delayed.

[0006] Furthermore, although the droplet sensor disclosed in Patent Document 2 can quickly detect rain from the start of a fall, it is difficult to measure the amount of rain accurately. An object of the present invention is to provide a raindrop detection device, a raindrop detection method, and a raindrop detection program that can accurately detect even a small amount of rain from the start of rainfall. [Means for solving the problem]

[0007] A raindrop detection device according to a first aspect of the present invention includes a light source unit, a light receiving unit, a raindrop detection unit, and a control unit. The light source unit emits light in a predetermined direction. The light receiving unit is positioned opposite the light source unit and receives the light emitted from the light source unit. The raindrop detection unit detects raindrops that pass between the light source unit and the light receiving unit in accordance with changes in the amount of light received by the light receiving unit. The control unit controls the turning on and off of the light emitted from the light source unit.

[0008] Here, the light source unit and the light receiving unit are positioned opposite each other, and when raindrops pass through the raindrop detection area formed between the light source unit and the light receiving unit, the amount of light received by the light receiving unit decreases, and raindrops are detected based on this reduced amount of light received. Here, the light source unit is, for example, an LED (Light Emitting Diode), and irradiates light in a predetermined direction onto the light receiving units that are arranged opposite each other with a predetermined distance therebetween.

[0009] The light receiving section is, for example, a photodiode, which receives light emitted from the light source section and outputs it as a voltage value. Detecting raindrops includes detecting, for example, the diameter of the raindrop, the volume of one raindrop, the amount of rainfall per unit time, and the speed of the raindrop. This makes it possible to detect raindrops one by one based on the amount of reduction in the amount of received light caused by light being blocked by raindrops that pass through the raindrop detection area. As a result, even a small amount of rain can be accurately detected from the beginning of rain.

[0010] A raindrop detection device according to a second aspect of the present invention is the raindrop detection device according to the first aspect of the present invention, wherein the control unit controls the light source unit to repeatedly turn on and off. Here, turning off the light source unit does not necessarily mean that it is completely turned off, but also includes a state where it is almost completely turned off. This allows the control unit to repeatedly turn the light emitted from the light source unit on and off while detecting changes in the amount of light received by the light receiving unit, and by subtracting the amount of light received when the light is off from the amount of light received when the light is on, for example, it is possible to detect raindrops while eliminating the effects of external light.

[0011] The raindrop detection device according to the third aspect of the present invention is the raindrop detection device according to the second aspect of the present invention, wherein the light receiving unit has a differential output unit that outputs the difference in the amount of light received when the light source unit is on and when it is off as a voltage. This makes it possible to suppress the influence of ambient light, for example, and to detect with high accuracy a decrease in the amount of received light due to the passage of raindrops.

[0012] A raindrop detection device according to a fourth aspect of the present invention is the raindrop detection device according to the third aspect of the present invention, wherein the control unit performs feedback control to change the output of the light source unit so that the difference remains constant. As a result, even if the amount of light received changes due to, for example, the temperature of the light source unit such as an LED, deterioration of the light source unit, or fogging of the lens, feedback control is performed to increase the output of the light source unit, thereby enabling stable detection of raindrops.

[0013] A raindrop detection device according to a fifth aspect of the present invention is the raindrop detection device according to the fourth aspect of the present invention, further comprising an averaging processor that averages the differences and transmits the averaged difference to the controller. This allows for more stable raindrop detection by performing averaging processing to avoid being affected by changes in the amount of received light that occur when raindrops are detected.

[0014] A raindrop detection device according to a sixth aspect of the present invention is a raindrop detection device according to any one of the first to fifth aspects of the present invention, in which the raindrop detection unit detects the diameter of a single raindrop based on the amount of decrease in the difference in the amount of light received when the light source unit is on and when it is off. This makes it possible to detect the diameter of a single raindrop by using the difference between the amount of light received when the light source is on and when it is off, which is reduced when a raindrop passes through the raindrop detection area.

[0015] A raindrop detection device according to a seventh aspect of the present invention is the raindrop detection device according to any one of the first to sixth aspects of the present invention, wherein the raindrop detection unit calculates the volume of a single raindrop based on the decrease in the amount of received light. This makes it possible to easily calculate the volume of a single raindrop from the decrease in the amount of received light detected by the light receiving unit.

[0016] A raindrop detection device according to an eighth aspect of the present invention is the raindrop detection device according to the sixth aspect of the present invention, wherein the raindrop detection unit calculates the volume of a single raindrop based on the diameter and the amount of reduction. This makes it possible to easily calculate the volume of a single raindrop using the diameter of the raindrop derived from the decrease in the amount of received light detected by the light receiving unit.

[0017] A raindrop detection device according to a ninth aspect of the present invention is the raindrop detection device according to the seventh or eighth aspect of the present invention, in which the raindrop detection unit calculates the volume of raindrops passing between the light source unit and the light receiving unit per predetermined unit time from the volume of a single raindrop, and divides the calculated value by the area of ​​the area where the raindrops are detected to calculate the amount of rainfall per unit time. This makes it easy to calculate the amount of rainfall per unit time simply by adding up the volume of one raindrop.

[0018] A raindrop detection device according to a tenth aspect of the present invention is a raindrop detection device according to any one of the first to ninth aspects of the present invention, further comprising a receiving unit that receives information related to wind speed conditions, and a correction unit that corrects the amount of rainfall per unit time detected by the raindrop detection unit according to the wind speed conditions received by the receiving unit. This allows, for example, when raindrops are falling at an angle on a windy day, to take into account that the amount of raindrops entering the raindrop detection area of ​​the raindrop detection device will change slightly depending on the wind, and by correcting the amount of rainfall per unit time according to information about the wind speed, the influence of wind can be minimized and the amount of rainfall can be calculated with high accuracy.

[0019] A raindrop detection device according to an eleventh aspect of the present invention is a raindrop detection device according to any one of the first to tenth aspects of the present invention, wherein when the raindrop detection unit detects the presence of raindrops based on a change in the amount of received light, it detects the pulse width of the light received by the light receiving unit when the raindrops are detected, and if a pulse width exceeding a predetermined threshold is detected, it does not determine that there are raindrops. For example, the larger the diameter of a raindrop, the faster it falls, resulting in a smaller pulse width. On the other hand, if the raindrop diameter is large and the pulse width is large, it is determined that there is a possibility of a foreign object other than a raindrop, such as a fallen leaf, or other malfunction. This allows the system to monitor the pulse width at the time of detection even when raindrops are detected, and if the pulse width exceeds a predetermined threshold, not count the detection as a raindrop, thereby preventing foreign objects from being mistakenly counted as raindrops and detecting malfunctions of the raindrop detection device.

[0020] A raindrop detection device according to a twelfth aspect of the present invention is the raindrop detection device according to the eleventh aspect of the present invention, wherein the raindrop detection unit determines whether or not to recognize a raindrop based on the pulse width and the amount of decrease in the amount of received light. This allows for a more accurate determination of whether or not the detected light is a raindrop by using the decrease in the amount of received light as a determination factor in addition to the above-described determination of the pulse width with the threshold value.

[0021] The raindrop detection device according to a thirteenth aspect of the present invention is the raindrop detection device according to any one of the first to twelfth aspects of the present invention, further comprising a raindrop speed calculation unit that calculates the speed of the raindrops based on the time that the raindrops block light passing between the light source unit and the light receiving unit. This makes it possible to detect not only the amount of rainfall per unit time but also the speed of the raindrops, thereby achieving effects such as recognizing false positives and detecting not only rainwater but also sleet, hail, snow, etc.

[0022] A raindrop detection device according to a fourteenth aspect of the present invention is the raindrop detection device according to any one of the first to thirteenth aspects of the present invention, wherein a plurality of light source units are provided. This allows raindrops that pass through the range of light emitted from multiple light source units to be detected based on changes in the amount of light received by the light receiving unit, thereby expanding the raindrop detection area.

[0023] The raindrop detection device according to a fifteenth aspect of the present invention is the raindrop detection device according to any one of the first to fourteenth aspects of the present invention, further comprising a first lens unit that converts light emitted from the light source unit into parallel light. This allows the light emitted from the light source unit to be collimated, so that raindrops can be detected stably in the raindrop detection area based on the amount of light received, which changes when raindrops pass through the collimated light.

[0024] A raindrop detection device according to a sixteenth aspect of the present invention is the raindrop detection device according to the fifteenth aspect of the present invention, further comprising a second lens unit that collects the light collimated by the lens unit and directs it to the light receiving unit. This allows the second lens portion to condense the collimated light so that all of the light can be received by the light receiving portion.

[0025] A raindrop detection device according to a seventeenth aspect of the present invention is the raindrop detection device according to any one of the first to sixteenth aspects of the present invention, wherein the light source unit emits infrared light. This allows raindrops to be detected using infrared light emitted from the light source unit.

[0026] The raindrop detection device according to an eighteenth aspect of the present invention is the raindrop detection device according to any one of the first to seventeenth aspects of the present invention, further comprising a shielding filter that is provided on the light receiving surface side of the light receiving unit and blocks visible light. This makes it possible to prevent ambient light (visible light) from mixing with the light received by the light receiving section, thereby preventing a decrease in the accuracy of detecting raindrops.

[0027] A raindrop detection method according to a 19th aspect of the present invention is a raindrop detection method using the raindrop detection device according to any one of the first to 18th aspects of the present invention, and includes an irradiation step of irradiating light from a light source unit in a predetermined direction, a light receiving step of receiving the light irradiated from the light source unit at a light receiving unit arranged at a position opposite the light source unit, and a raindrop detection step of detecting raindrops that have passed between the light source unit and the light receiving unit in accordance with a change in the amount of light received in the light receiving step. Here, the light source unit and the light receiving unit are positioned opposite each other, and when raindrops pass through the raindrop detection area formed between the light source unit and the light receiving unit, the amount of light received by the light receiving unit decreases, and raindrops are detected based on this reduced amount of light received. Here, the light source unit is, for example, an LED (Light Emitting Diode), and irradiates light in a predetermined direction onto the light receiving units that are arranged opposite each other with a predetermined distance therebetween.

[0028] The light receiving section is, for example, a photodiode, which receives light emitted from the light source section and outputs it as a voltage value. Detecting raindrops includes detecting, for example, the diameter of the raindrop, the volume of one raindrop, the amount of rainfall per unit time, and the speed of the raindrop. This makes it possible to detect raindrops one by one based on the amount of reduction in the amount of received light caused by light being blocked by raindrops that pass through the raindrop detection area. As a result, even a small amount of rain can be accurately detected from the beginning of rain.

[0029] The raindrop detection program according to the twentieth aspect of the present invention is a raindrop detection program that causes a computer to execute a raindrop detection method using the raindrop detection device according to any one of the first to eighteenth aspects of the present invention, and includes an irradiation step of irradiating light from a light source unit in a predetermined direction, a light receiving step of receiving the light irradiated from the light source unit at a light receiving unit positioned opposite the light source unit, and a raindrop detection step of detecting raindrops that have passed between the light source unit and the light receiving unit in accordance with changes in the amount of light received in the light receiving step.

[0030] Here, the light source unit and the light receiving unit are positioned opposite each other, and when raindrops pass through the raindrop detection area formed between the light source unit and the light receiving unit, the amount of light received by the light receiving unit decreases, and raindrops are detected based on this reduced amount of light received. Here, the light source unit is, for example, an LED (Light Emitting Diode), and irradiates light in a predetermined direction onto the light receiving units that are arranged opposite each other with a predetermined distance therebetween.

[0031] The light receiving section is, for example, a photodiode, which receives light emitted from the light source section and outputs it as a voltage value. Detecting raindrops includes detecting, for example, the diameter of the raindrop, the volume of one raindrop, the amount of rainfall per unit time, and the speed of the raindrop.

[0032] This makes it possible to detect raindrops one by one based on the amount of reduction in the amount of received light caused by light being blocked by raindrops that pass through the raindrop detection area. As a result, even a small amount of rain can be accurately detected from the beginning of rain. [Effects of the Invention]

[0033] The raindrop detection device according to the present invention can accurately detect even a small amount of rain from the beginning of rainfall. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a control block diagram showing the configuration of a raindrop detection device according to an embodiment of the present invention; [Figure 2] 2 is a conceptual diagram showing how light collimated by a collimating lens included in the raindrop detection device of FIG. 1 is collected by a collecting lens. [Figure 3] 2A, 2B, and 2C are graphs illustrating control for eliminating the influence of ambient light in the raindrop detection device of FIG. 1. [Figure 4] (a) is a graph showing the state where raindrops are detected by extracting the difference in the amount of light received when the light is on and off. (b) is a graph showing the detection result of (a) after inverting and amplifying it. [Figure 5] (a) is a table stored in memory containing the voltage value converted from the amount of received light and the measurement results of the diameter and volume of detected raindrops. (b) is a table containing the rainfall per unit time calculated from the total volume of the raindrops in (a). [Figure 6] 2A is a cross-sectional view showing the state in which raindrops are falling in a substantially vertical direction on the raindrop detection device of FIG. 1, and FIG. 2B is a cross-sectional view showing the state in which raindrops are falling obliquely on the raindrop detection device of FIG. 1. [Figure 7] 4 is a graph showing the relationship between wind speed and a correction coefficient value used to correct the amount of rainfall in the raindrop detection device of FIG. 1. [Figure 8] 4 is a graph illustrating a state in which the amount of light received by the photodiode is reduced due to fogging of the lens or the like in the raindrop detection device of FIG. 1; [Figure 9] 2 is a graph showing the relationship between raindrop diameter and pulse width in the raindrop detection device of FIG. 1, which monitors a pulse signal indicating the amount of light received by a photodiode and excludes the raindrop from being counted. [Figure 10] 4 is a flowchart showing the flow of processing in a raindrop detection method performed by the raindrop detection device of FIG. [Figure 11] FIG. 6 is a control block diagram showing the configuration of a raindrop detection device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] A raindrop detection device according to one embodiment of the present invention will be described below with reference to FIGS. In the present embodiment, more detailed explanation than necessary may be omitted. For example, detailed explanation of well-known matters or redundant explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art. Furthermore, the applicant provides the accompanying drawings and the following description to enable those skilled in the art to fully understand the present invention, and they are not intended to limit the subject matter described in the claims.

[0036] (1) Configuration of the raindrop detection device 10 The raindrop detection device 10 according to this embodiment is a raindrop sensor that detects raindrops that have passed through a predetermined raindrop detection area A1 (see FIG. 1). As shown in FIG. 1, the raindrop detection device 10 includes a plurality of LEDs (light source unit) 11, a collimating lens (first lens unit) 12, a condensing lens (second lens unit) 13, a photodiode (light receiving unit) 14, an amplifier 15, a difference detection circuit (difference output unit) 16, an averaging circuit (averaging processing unit) 17, a differential amplifier 18, an amplifier 19, a microcomputer (raindrop detection unit, raindrop velocity calculation unit) 20, an LED current adjustment circuit (control unit) 21, an LED flashing circuit (control unit) 22, a memory (storage unit) 23, and a receiving unit 24.

[0037] As shown in FIG. 1, multiple LEDs (light source units) 11 are arranged facing a photodiode 14 so as to sandwich a raindrop detection area A1 (described later). As shown in FIG. 2, each LED 11 emits infrared light toward the photodiode 14 via a collimating lens 12 and a condenser lens 13. An LED blinking circuit 22 controls the LEDs 11 to repeatedly turn on and off with a predetermined pulse width. An LED current adjustment circuit 21 adjusts the current flowing through the LEDs 11, thereby adjusting the output (light intensity) of the LEDs 11.

[0038] 1 etc., the collimating lens (first lens portion) 12 is a cylindrical lens having a convex shape facing the photodiode 14 side, and is disposed adjacent to the side irradiating the light from the LED 11. As shown in FIG. 2, the collimating lens 12 converts the light irradiated from the LED 11 into approximately parallel light. 1 etc., the condenser lens (second lens portion) 13 is a cylindrical lens having a convex shape facing the LED 11 side, and is disposed adjacent to the side that receives light from the photodiode 14. As shown in FIG. 2, the condenser lens 13 condenses the light converted into approximately parallel light toward the photodiode 14.

[0039] As shown in FIGS. 1 and 2, a raindrop detection area A1 is provided between the collimating lens 12 and the condenser lens 13. 1, the photodiode (light receiving section) 14 is disposed at a position facing the LED 11. The photodiode 14 receives light collected by the collecting lens 13, as shown in FIG.

[0040] 1, the raindrop detection area A1 is formed between the LED 11 and the photodiode 14, which are arranged facing each other. When raindrops pass through the raindrop detection area A1, part of the light emitted from the LED 11 is blocked, causing the amount of light received by the photodiode 14 to decrease, thereby enabling the presence or absence of raindrops to be detected. The amplifier 15 amplifies the voltage value that changes in accordance with the amount of light received and detected by the photodiode 14 , and outputs the amplified voltage to the difference detection circuit 16 .

[0041] In the control of repeatedly turning on and off the LED 11 described later, the difference detection circuit (difference output unit) 16 calculates the difference (see FIG. 3(c)) between the amount of light received when the LED 11 is on and the amount of light received when the LED 11 is off (see FIGS. 3(a) and 3(b)), and outputs the difference to the averaging circuit 17 and the differential amplifier 18. Here, the graph shown in FIG. 3(a) shows the relationship between the elapsed time and the amount of light received (voltage value) by the photodiode 14 in an environment where there is little disturbance light entering the raindrop detection area A1.

[0042] That is, in the graph of FIG. 3(a), the photodiode 14 receives light corresponding to 1.0 V when the LED 11 is turned off, and light corresponding to 2.5 V when the LED 11 is turned on. The graph shown in FIG. 3(b) shows the relationship between the elapsed time and the amount of light received (voltage value) by the photodiode 14 in an environment where the amount of ambient light entering the raindrop detection area A1 is greater than in the environment of FIG. 3(a).

[0043] In other words, in the graph of FIG. 3(b), because the environment is one with a lot of ambient light, the amount of light received by the photodiode 14 is greater overall than in the graph of FIG. 3(a), and when the LED 11 is off, it receives light equivalent to 2.5V, and when it is on, it receives light equivalent to 4.0V. 3(a) and 3(b), the raindrop detection device 10 of this embodiment controls the LED 11 so that the light emitted from the LED 11 is repeatedly turned on and off based on a predetermined pulse signal. The raindrop detection device 10 detects the difference in the amount of light received by the photodiode 14 when the light is on and when it is off, thereby preventing fluctuations in the amount of light received by the photodiode 14 due to the influence of ambient light.

[0044] Specifically, even in an environment with relatively little ambient light as shown in Figure 3(a), or in an environment with more ambient light than the environment in Figure 3(a) as shown in Figure 3(b), the influence of ambient light can be eliminated and a voltage value of 1.5 V (amount of received light) can be used as the reference value for raindrop detection, as shown in Figure 3(c). The averaging circuit (averaging processor) 17 averages the difference between when the LED 11 is on and when it is off, detected by the difference detection circuit 16, and outputs the averaged result to the differential amplifier 18 and the LED current adjustment circuit 21.

[0045] This prevents the raindrop detection reference value (1.5 V in Figure 3(c)) from fluctuating due to temporary fluctuations in the amount of received light, such as when raindrops are detected, even if the difference temporarily changes due to the detection of raindrops, etc. The differential amplifier 18 amplifies the difference between the reference value (1.5 V in FIG. 3( c )) averaged by the averaging circuit 17 and the detection result by the difference detection circuit 16 , and outputs the amplified difference to the amplifier 19 .

[0046] The amplifier 19 amplifies the output from the differential amplifier 18 by inverting the plus and minus of the signal, and outputs the amplified signal to the microcomputer 20 . That is, when the amount of light received by the photodiode 14 decreases from the reference value (1.5 V) due to raindrops passing through the raindrop detection area A1 as shown in FIG. 4(a), the amplifier 19 converts the change in voltage value from negative to positive, amplifies it, and outputs it as shown in FIG. 4(b).

[0047] Based on the output amplified by the amplifier 19, the microcomputer (raindrop detector, raindrop speed calculator, corrector) 20 detects whether or not raindrops have passed through the raindrop detection area A1. That is, the microcomputer 20 detects the presence or absence of raindrops based on the fact that raindrops passing through the raindrop detection area A1 block part of the light emitted from the LED 11 and approximately collimated by the collimating lens 12, causing a change (decrease) in the amount of light received by the photodiode 14.

[0048] Specifically, when the decrease in the amount of light received by the photodiode 14 exceeds a predetermined threshold (for example, 1.0 V in FIG. 4(b)), the microcomputer 20 determines that raindrops are present based on the decrease in the amount of light received. Furthermore, the microcomputer 20 calculates the diameter of each raindrop based on the presence or absence of raindrops passing through the raindrop detection area A1 and the amount of received light (voltage value) reduced by the raindrops.The microcomputer 20 then calculates the volume of each raindrop from the calculated diameter, and calculates the amount of precipitation per unit time (1 minute or 1 hour) by integrating the volumes of raindrops passing through the raindrop detection area A1 per unit time and dividing the total by the area of ​​the raindrop detection area A1.

[0049] The diameter of the raindrop is calculated based on the voltage value output from the photodiode 14, using, for example, the following relational expression (1). D=3.1544E 0.6007 ·····(1) (where D = diameter of the raindrop, E = detected voltage) For example, Figure 5(a) shows the detection time (ms), voltage (V), diameter (mm), and volume (mm) of raindrops detected between 16:47:00 and 16:47:59 on the date of the month and year. 3 ) is shown in the table.

[0050] As described above, when a raindrop is detected, the diameter of the raindrop is calculated according to the voltage value output from the amplifier 19. Then, the volume of the raindrop is calculated based on the diameter r of the raindrop using the following relational expression (2). Volume of a raindrop = (4 / 3)π(r / 2) 3 ·····(2) As shown in FIG. 5(b), the microcomputer 20 calculates the total volume (5.621 mm) of raindrops that passed through the raindrop detection area A1 during the 59 seconds from 16:47:00 to 16:47:59 on the date of the month and year. 3 ), the rainfall per minute (0.0057 mm / min) is calculated, and the rainfall per hour (0.3407 mm / hr) (=rainfall per minute × 60) is calculated and stored in memory 23 as a table.

[0051] Furthermore, the microcomputer 20 calculates the speed of the raindrops based on the detection time (ms) of the raindrops passing through the raindrop detection area A1, which is included in the leftmost column of the table shown in FIG. 5(a). For example, if the raindrops to be detected are water, the falling speed is the fastest among the above, sleet has a falling speed between water and snow, and snow has the slowest falling speed. It should be noted that the detection time range (0.4 to 1.1) shown in FIG. 5(a) all indicates the case where the raindrops are water.

[0052] This makes it possible to determine whether the raindrops passing through the raindrop detection area A1 are water, sleet, or snow by detecting the speed of the detected raindrops. Furthermore, the microcomputer 20 corrects the amount of rainfall per unit time calculated by the microcomputer 20 based on the wind speed received from the anemometer 40 via the receiving unit 24. Specifically, as shown in FIG. 6(a), the raindrop detection device 10 is configured to include an approximately cylindrical cover 30, an approximately cylindrical base 31, and an approximately disk-shaped substrate 32, and a raindrop detection area A1 is provided in the cylindrical portion formed at the center of the cover 30 and the base 31.

[0053] An LED 11 and a photodiode 14 are arranged on both sides of the raindrop detection area A1 on a substrate 32, sandwiching the raindrop detection area A1. A collimating lens 12 is arranged adjacent to the light-emitting side of the LED 11 on the substrate 32. A condensing lens 13 is arranged adjacent to the light-receiving side of the photodiode 14 on the substrate 32.

[0054] In this configuration, when raindrops R1 fall in a substantially vertical direction, most of the raindrops R1 pass through the raindrop detection area A1 relative to the area of ​​the raindrop detection area A1, as shown in FIG. 6(a). On the other hand, when raindrops R2 fall obliquely relative to the approximately vertical direction, as shown in Figure 6(b), there is a risk that some of the raindrops R2 will not pass through the raindrop detection area A1 and will hit the cover 30 or the like and not pass through the raindrop detection area A1.

[0055] The amount of raindrops R2 that do not pass through the raindrop detection area A1 varies depending on the wind speed in the environment where the raindrop detection device 10 is installed. Therefore, the raindrop detection device 10 of this embodiment refers to the table shown in FIG. 7 and corrects the amount of rain detected by the raindrop detection device 10 in accordance with the wind speed. More specifically, for example, if the wind speed is 2.0 m / h, the rainfall is corrected by multiplying the rainfall by a correction coefficient of 1.05, as shown in Figure 7. As shown in Figure 7, the correction coefficient increases as the wind speed increases, becoming approximately 1.13 at a wind speed of 4.0 m / h, approximately 1.21 at a wind speed of 6.0 m / h, approximately 1.31 at a wind speed of 8.0 m / h, and approximately 1.42 at a wind speed of 10.0 m / h.

[0056] This avoids the situation where fewer raindrops than the actual amount of rain are detected due to a high wind speed, and makes it possible to detect the amount of rain with higher accuracy. The LED current adjustment circuit (control unit) 21 receives a reference value (1.5 V in the example of FIG. 3(c)) obtained by averaging the output from the difference detection circuit 16 output from the averaging circuit 17, and controls the value of the current flowing through the LED 11 so that the reference value becomes approximately constant.

[0057] That is, for example, when the reference value detected by the photodiode 14 and amplified by the amplifier 15 drops from 1.5 V (see FIG. 3(a)) to 1.0 V (the difference between 1.0 V and 2.0 V) shown in FIG. 8, the LED current adjustment circuit 21 increases the current flowing through the LED 11 and performs feedback control so that the reference value becomes 1.5 V. Such a decrease in the reference value occurs due to, for example, deterioration of the LED 11 over time, clouding of the collimating lens 12 or the condenser lens 13, deterioration of the photodiode 14 over time, and the like.

[0058] This makes it possible to prevent a decrease in the accuracy of raindrop detection due to a decrease in the amount of light received caused by deterioration of the LED 11, lenses 12 and 13, photodiode 14, etc., rather than the influence of raindrops passing through the raindrop detection area A1, by using the above feedback control. The LED flashing circuit (controller) 22 controls the LED 11 by a predetermined pulse signal so that the light emitted from the LED 11 repeatedly turns on and off. Specifically, as shown in Fig. 3(a) and other figures, the LED flashing circuit 22 controls the LED 11 to turn on for a certain period of time and turn off for a certain period of time.

[0059] As a result, as described above, the LED 11 is controlled to repeatedly turn on and off, and the difference between these values ​​is used as a reference value to detect raindrops, thereby suppressing the influence of external light and enabling highly accurate detection of raindrops. The memory (storage unit) 23 stores a table including the relationship between the voltage when raindrops are detected and the diameter, volume, and amount of rainfall per unit time of the raindrops, as shown in Figures 5(a) and 5(b) described above, as well as a correction table shown in Figure 7.

[0060] As described above, the receiving unit 24 receives wind speed data from the anemometer 40 installed in the environment where the raindrop detection device 10 is installed, and transmits the data to the microcomputer 20. Furthermore, as shown in FIG. 9, when the microcomputer 20 of the raindrop detection device 10 of this embodiment detects the presence of raindrops based on a change in the amount of received light, it detects the pulse width of the light received by the photodiode 14 when the raindrops are detected, and if the pulse width detected exceeds a predetermined threshold value (e.g., 6.0 ms), it does not determine that the raindrops are present.

[0061] That is, the larger the diameter of a raindrop, the faster it falls, resulting in a smaller pulse width. On the other hand, if the raindrop diameter is large and the pulse width is large, it can be determined that there is a possibility of a foreign object other than a raindrop, such as a fallen leaf, or that there is some other malfunction. As a result, even if raindrops are detected, the pulse width at the time of detection is monitored, and if the pulse width exceeds a predetermined threshold, the detection is not counted as a raindrop, thereby preventing foreign objects from being erroneously counted as raindrops and detecting malfunctions of the raindrop detection device 10.

[0062] <Raindrop detection method using raindrop detection device 10> The raindrop detection device 10 of this embodiment detects raindrops that have passed through the raindrop detection area A1 according to the flowchart shown in FIG. That is, in step S11, the LED flashing circuit 22 controls the LED 11 so that it repeatedly turns on and off at predetermined time intervals based on the pulse signal.

[0063] Next, in step S12, the photodiode 14 receives the light emitted from the LED 11 and detects the amount of the received light. Next, in step S13, the difference between the detection results of the photodiode 14 when the LED 11 is turned on and when it is turned off is calculated. Next, in step S14, the difference value calculated in step S13 is set as a reference value for detecting raindrops.

[0064] Next, in step S15, it is determined whether the difference between the reference value set in step S14 and the amount of change (decrease) in the amount of received light actually detected by the photodiode 14 is equal to or greater than a predetermined threshold value. If the difference is equal to or greater than the predetermined threshold value, the process proceeds to step S16, and if the difference is less than the predetermined threshold value, the process returns to step S12. Next, in step S16, since it is determined in step S15 that the difference is equal to or greater than the predetermined threshold, it is determined that raindrops are present from the detection value corresponding to that difference.

[0065] Next, in step S17, it is determined whether the pulse width when raindrops are detected is less than a predetermined value. If it is less than the predetermined value, the process proceeds to step S18, and if it is greater than or equal to the predetermined value, the process proceeds to step S19. Next, in step S18, since it was determined in step S17 that the pulse width when raindrops were detected was less than the predetermined value, it is determined that the objects are not foreign objects other than raindrops (fallen leaves, etc.), and are counted as raindrops.

[0066] On the other hand, in step S19, since it was determined in step S17 that the pulse width when the raindrop was detected was greater than or equal to the predetermined value, it is determined that there is a high possibility that the object is a foreign object other than a raindrop (such as a fallen leaf), so it is not counted as a raindrop and the process returns to step S12. Next, in step S20, the diameter, volume, and amount of rainfall per unit time of the raindrops counted as raindrops are calculated from the voltage values ​​at which the raindrops are detected.

[0067] Next, in step S21, the receiver 24 receives wind speed data from the anemometer 40 and determines whether the wind speed at the time when raindrops were detected is equal to or greater than a predetermined value. If the wind speed is equal to or greater than the predetermined value, the process proceeds to step S22; if the wind speed is less than the predetermined value, the process skips step S22 and proceeds to step S23. Next, in step S22, since it was determined in step S21 that the wind speed was equal to or greater than a predetermined value, the rainfall calculated in step S20 is corrected according to the wind speed in order to eliminate variations in rainfall caused by the influence of wind speed. Next, in step S23, since it was determined in step S21 that the wind speed was less than a predetermined value, or the rainfall amount was corrected according to the wind speed in step S22, the diameter, volume, velocity, and rainfall amount per unit time of the raindrops are stored in memory 23, and the process ends.

[0068] <Main features> The raindrop detection device 10 of this embodiment includes an LED 11, a photodiode 14, a microcomputer 20, and an LED flashing circuit 22. The LED 11 emits light in a predetermined direction. The photodiode 14 is positioned opposite the LED 11 and receives the light emitted from the LED 11. The microcomputer 20 detects raindrops that pass between the LED 11 and the photodiode 14 in accordance with changes in the amount of light received by the photodiode 14. The LED flashing circuit 22 controls the turning on and off of the light emitted from the LED 11.

[0069] As a result, the LED flashing circuit 22 detects changes in the amount of light received by the photodiode 14 while repeatedly turning the light emitted from the LED 11 on and off. For example, by subtracting the amount of light received when the LED is off from the amount of light received when the LED is on, it is possible to detect raindrops while eliminating the effects of ambient light.

[0070] [Other embodiments] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. (A) In the above embodiment, the raindrop detection device and method are described as examples of realizing the present invention, but the present invention is not limited to this. For example, the present invention may be realized as a raindrop detection program that causes a computer to execute the method of the raindrop detection device described above.

[0071] This raindrop detection program is stored in a memory (storage unit) installed in the raindrop detection device, and the CPU loads the raindrop detection program stored in the memory and causes the hardware to execute each step. More specifically, the CPU loads the raindrop detection program and executes the above-mentioned irradiation step, light receiving step, and raindrop detection step, thereby achieving the same effects as those described above. The present invention may also be realized as a recording medium storing a raindrop detection program.

[0072] (B) 1 and 2, the light emitted from the LED 11 is collimated by the collimating lens 12, and the collimated light that passes through the raindrop detection area A1 is collected by the collecting lens 13 and received by the photodiode 14. However, the present invention is not limited to this.

[0073] For example, as shown in FIG. 11, a configuration may be adopted in which a shielding filter 25 that blocks visible light is disposed between the focusing lens 13 and the photodiode 14, upstream of the photodiode 14, in the direction in which the light emitted from the LED 11 travels. This prevents visible light from entering the photodiode 14, eliminating the influence of ambient light and enabling more accurate detection of raindrops.

[0074] (C) In the above embodiment, the microcomputer 20 detects raindrops by outputting the difference between the amount of light received by the photodiode 14 when the LED 11 is turned on and the amount of light received by the photodiode 14 when the LED 11 is turned off. However, the present invention is not limited to this. For example, raindrop detection may be performed by detecting changes in the amount of light received by the photodiode while the LED is constantly lit. However, as described above, raindrop detection is performed using the difference in the amount of light received when the light is turned on and when the light is turned off, thereby eliminating the influence of ambient light. It is preferable to perform raindrop detection by control such as in the above embodiment.

[0075] (D) In the above embodiment, an example has been described in which feedback control is performed to adjust the output of the LED 11 so that the difference between the amount of light received by the photodiode 14 when the LED 11 is turned on and the amount of light received by the photodiode 14 when the LED 11 is turned off is kept substantially constant. However, the present invention is not limited to this. For example, raindrop detection may be performed without implementing feedback control.

[0076] (E) In the above embodiment, an example was described in which the LED 11 was used as the light source unit, but the present invention is not limited to this. For example, the above-described raindrop detection may be performed using a light source unit other than an LED.

[0077] (F) In the above embodiment, an example has been described in which the photodiode 14 is used as the light receiving section, but the present invention is not limited to this. For example, the above-described raindrop detection may be performed using a light receiving unit other than a photodiode.

[0078] (G) In the above embodiment, the LED 11 that emits infrared light has been described as an example of the light source unit, but the present invention is not limited to this. For example, in an environment where visible light such as sunlight can be blocked, the raindrop detection device may be provided with a light source unit such as an LED that emits visible light.

[0079] (H) In the above embodiment, an example has been described in which the wind speed in the environment in which the raindrop detection device 10 is installed is received in real time from the anemometer 40, and the detected rainfall amount is corrected according to the wind speed. However, the present invention is not limited to this. For example, if the raindrop detection device is installed in an environment that is not affected by wind, there is no need to receive wind speed from an anemometer and correct the detected rainfall. Therefore, as shown in Figure 11, the raindrop detection device may not have a receiving unit that receives wind speed from an anemometer in real time. [Industrial Applicability]

[0080] The raindrop detection device of the present invention has the effect of being able to accurately detect even a small amount of rain from the beginning of rainfall, and is therefore widely applicable as a rainfall sensor, a rain sensor, and a weather sensor. [Explanation of symbols]

[0081] 10 Raindrop detector 11 LED (light source) 12. Collimating lens (first lens part) 13 Condenser lens (second lens part) 14 Photodiode (light receiving part) 15 Amplifier 16 Differential detection circuit (differential output section) 17 Averaging circuit (averaging processing section) 18 Differential Amplifier 19 Amplifier 20 Microcomputer (raindrop detection section, raindrop speed calculation section, correction section) 21 LED current adjustment circuit (control section) 22 LED flashing circuit (control unit) 23 Memory (storage section) 24 Receiving unit 25 Shielding Filter 30 Cover 31 Base 32 PCB 40 Anemometer A1 Raindrop detection area R1,R2 Raindrops

Claims

1. a light source unit that emits light in a predetermined direction; a light receiving unit disposed opposite the light source unit and configured to receive light emitted from the light source unit; A raindrop detection unit that detects raindrops that have passed between the light source unit and the light receiving unit according to a change in the amount of light received by the light receiving unit; a control unit that controls turning on and off the light emitted from the light source unit; Equipped with the control unit controls the light source unit to repeatedly turn on and off; the light receiving unit has a difference output unit that outputs a difference in the amount of light received when the light source unit is turned on and when it is turned off as a voltage; The control unit performs feedback control to eliminate the influence of ambient light using the difference and change the output of the light source unit so that the reference value for raindrop detection is constant. Raindrop detection device.

2. The apparatus further includes an averaging processing unit that averages the difference and transmits the averaged difference to the control unit. The raindrop detection device of claim 1 .

3. The raindrop detection unit detects the diameter of one raindrop based on a decrease in the difference between the amount of received light when the light source unit is turned on and when it is turned off.

3. The raindrop detection device according to claim 1 or 2.

4. The raindrop detection unit calculates the volume of one raindrop based on the decrease in the amount of received light. The raindrop detection device according to any one of claims 1 to 3.

5. The raindrop detection unit calculates the volume of one of the raindrops based on the diameter.

4. The raindrop detection device of claim 3.

6. The raindrop detection unit calculates the volume of the raindrops passing between the light source unit and the light receiving unit per predetermined unit time from the volume of one raindrop, and divides the calculated value by the area of ​​the area where the raindrops are detected to calculate the amount of rain per unit time.

6. A raindrop detection device according to claim 4 or 5.

7. a receiving unit for receiving information regarding wind speed conditions; a correction unit that corrects the rainfall amount per unit time detected by the raindrop detection unit according to the wind speed condition received by the receiving unit; It further comprises: The raindrop detection device according to any one of claims 1 to 6.

8. A light source unit that irradiates light in a predetermined direction; a light receiving unit disposed opposite the light source unit and configured to receive light emitted from the light source unit; A raindrop detection unit that detects raindrops that have passed between the light source unit and the light receiving unit according to a change in the amount of light received by the light receiving unit; a control unit that controls turning on and off the light emitted from the light source unit; Equipped with When the raindrop detection unit detects that there are raindrops based on a change in the amount of received light, it detects the pulse width of the light received by the light receiving unit when the raindrops are detected. If a pulse width exceeding a predetermined threshold is detected, it is not determined to be a raindrop. Raindrop detection device.

9. The raindrop detection unit determines whether to determine the raindrop based on the pulse width and the decrease in the amount of received light.

9. The raindrop detection device of claim 8.

10. Further provided is a raindrop speed calculation unit that calculates the speed of the raindrop based on the light blocking time by the raindrop passing between the light source unit and the light receiving unit, 10. A raindrop detection device according to any one of claims 1 to 9.

11. The light source unit is provided in plurality. A raindrop detection device according to any one of claims 1 to 10.

12. The optical system further includes a first lens unit that converts light emitted from the light source unit into parallel light.

12. A raindrop detection device according to any one of claims 1 to 11.

13. The optical fiber further includes a second lens unit that collects the light that has been collimated by the first lens unit and guides the light to the light receiving unit.

13. The raindrop detection device of claim 12.

14. The light source unit irradiates infrared light.

14. A raindrop detection device according to any one of claims 1 to 13.

15. The optical fiber further includes a shielding filter that is provided on the light receiving surface side of the light receiving unit and that blocks visible light.

15. A raindrop detection device according to any one of claims 1 to 14.

16. A raindrop detection method using the raindrop detection device according to any one of claims 1 to 15, an irradiation step of irradiating light from the light source unit in a predetermined direction; a light receiving step of receiving light irradiated from the light source unit at the light receiving unit disposed at a position facing the light source unit; A raindrop detection step of detecting raindrops that have passed between the light source unit and the light receiving unit according to a change in the amount of light received in the light receiving step; A raindrop detection method comprising:

17. A raindrop detection program that causes a computer to execute a raindrop detection method using the raindrop detection device according to any one of claims 1 to 15, an irradiation step of irradiating light from the light source unit in a predetermined direction; a light receiving step of receiving light irradiated from the light source unit at the light receiving unit disposed at a position facing the light source unit; A raindrop detection step of detecting raindrops that have passed between the light source unit and the light receiving unit according to a change in the amount of light received in the light receiving step; A raindrop detection program that includes:

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