JP2009192433A - Raindrop detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a raindrop detector for certainly detecting dripping water. <P>SOLUTION: When the continuously lasting time of a state that a raindrop amount gradient R is more than a raindrop amount gradient threshold value Rs reaches a threshold time Ts, the occurrence of dripping water is determined. Then, a drive signal is output to a wiper motor in order to perform wiping-off operation due to a wiper blade simultaneously with determining the occurrence of dripping water. By this method, the occurrence of dripping water is discriminated from a rainfall to be detected accurately. Then, since the wiping-off operation of the wiper blade is performed simultaneously with the detection, a front window shield is wiped away from above even if the dripping water occurs to well keep the front visual field of a driver. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a raindrop detection device that controls the operation of a wiper device based on the detection result of a raindrop sensor that detects raindrops and the like.

  .

  When the vehicle decelerates during or after rain, rainwater collected on the vehicle roof may flow down to the front windshield (hereinafter referred to as dripping water). Since the conventional raindrop detection device is configured to control the wiping operation of the wiper device based only on the amount of raindrop, it is mistakenly recognized that the amount of raindrop has increased when this dripping water is generated, and the wiping mode of the wiper device is increased ( Wiping operation interval time is shifted to a shorter mode). As a result, the wiper blade performs an excessively high-speed wiping operation with respect to the actual rainfall state, which makes the driver feel uncomfortable.

  In order to solve such a problem, it is desired that the raindrop detection device detects the occurrence of dripping water and appropriately wipes and removes dripping water without performing an excessive wiping operation.

  As a conventional raindrop detection device proposed to meet this demand, for example, a speed change sensor that detects the speed change amount of a vehicle is provided, and the speed change amount detected by the speed change sensor generates dripping water. If the amount of change is equal to or greater than the lower limit change amount, there is a configuration in which the wiper device performs a wiping operation (see Patent Document 1).

In addition, as another conventional raindrop detection device proposed to meet the above-mentioned requirements, the vehicle behavior detection means is provided, and the vehicle speed change amount grasped from the vehicle behavior signal from the vehicle behavior detection means exceeds a predetermined amount. And when a raindrop detection signal of a predetermined value or more is input, the wiper device is configured to be wiped only a few times, or a raindrop detection signal of a predetermined value or more is obtained until a certain time elapses after the vehicle speed becomes zero. When input, there is a configuration in which the wiper device is configured to perform a wiping operation only a few times (see Patent Document 2).
JP 2000-85537 A JP 2003-246259 A

  In the case of the raindrop detection device described in the above-mentioned Patent Document 1, even if the speed change amount is equal to or greater than the lower limit change amount of dripping water generation, dripping water is not necessarily generated depending on the rain condition or the traveling conditions up to that time. Since there is no dripping water, the wiper device may perform a wiping operation.

  In the case of the raindrop detection device described in Patent Document 2, it is determined as dripping water when the amount of change in the vehicle speed exceeds a predetermined amount and a raindrop detection signal greater than a predetermined value is input. In order to distinguish from the amount of raindrops detected during rainfall, it is necessary to set the value when a large amount of raindrops are attached. Therefore, a small amount of dripping water cannot be detected. However, even if the amount of dripping water is small, it hinders the driver's view. In such a case, dripping water cannot be wiped off.

  The present invention has been made in view of the above problems, and an object thereof is to provide a raindrop detection device capable of reliably detecting dripping water.

  In order to achieve the above object, the present invention employs the following technical means.

  The raindrop detection device according to claim 1 of the present invention is attached to a wiper device that moves a wiper blade to wipe off water droplets adhering to the windshield, and a detection region set within a wiper blade wiping range on the windshield. A raindrop sensor that outputs a raindrop signal according to the amount of waterdrop that has been received, and a controller that calculates the raindrop amount when the raindrop signal is input from the raindrop sensor and outputs a drive signal to the wiper device based on the calculated raindrop amount A raindrop detection device, wherein the controller detects the amount of water droplets attached at predetermined intervals within the wiping cycle of the wiper device, and changes in the amount of water droplets attached during each predetermined period detected by the waterdrop detectors An adhesion amount gradient calculating means for calculating an adhesion amount gradient as a rate, and a windshield based on the calculated adhesion amount gradient Determining means for determining the water droplet adhesion state of the water, and whether the dripping water phenomenon occurs when rain water or the like staying on the roof of the vehicle flows down to the windshield based on the transition state of the calculated deposition amount gradient value When it is determined that the dripping water state has occurred, the wiper device drive control that has been executed by the controller is interrupted, and the dripping water removal operation, which is a continuous wiping operation for the wiper device, is performed. A drive signal is output so as to be executed, and after the dripping water removal operation is completed, the wiper device drive control that has been interrupted is resumed.

  First, a raindrop detection operation in a conventional raindrop detection apparatus will be described. The detection of the amount of raindrops in the conventional raindrop detection apparatus is the time from when the wiper blade passes the detection area of the raindrop sensor until the next time the wiper blade reaches the detection area of the raindrop sensor during the wiper blade wiping operation. It is performed within the time when the amount of attached water droplets can be detected. The raindrop amount detection is performed a plurality of times, and every time the raindrop amount is detected a predetermined number of times, the average value of the detected data is calculated and used as the attached raindrop amount. That is, the raindrop amount detection is performed every sampling cycle, and an average raindrop amount obtained by averaging a predetermined number of times is represented as a calculated value of the raindrop amount. According to such a detection method, it is difficult to accurately identify whether the water adhering to the detection area of the raindrop sensor is the amount of raindrops or dripping water from the amount of adhering waterdrops.

  Therefore, in the raindrop detection apparatus according to claim 1 of the present invention, the determination of the presence or absence of dripping water is not the absolute amount of raindrops adhering to the windshield, but the value of the adhesion amount gradient which is the deposition rate of raindrops. Judgment is made based on the transition state. This adhesion amount gradient is calculated as the rate of change of the adhesion amount between two successive raindrop amount sampling cycles.

  Below, the dripping water generation | occurrence | production determination operation | movement in the raindrop detection apparatus of Claim 1 of this invention is demonstrated.

  First, raindrops adhere to the windshield intermittently during normal rain conditions. When raindrops adhere to the detection area of the windshield raindrop sensor, the value of the deposition amount gradient increases suddenly from the moment the raindrops are attached, and the time during which the raindrops spread along the front windshield surface. It is maintained, but the rate of change becomes zero as soon as it has expanded. When another raindrop adheres, similarly, the value of the adhesion amount gradient increases abruptly from the moment when the raindrop adheres, and the value is maintained for a while, but the rate of change immediately becomes zero. In this way, during normal rain, the value of the adhesion amount gradient suddenly increases in synchronization with raindrop adhesion, but immediately returns to zero.

  On the other hand, the time for dripping water to flow through the detection area of the raindrop sensor of the windshield is longer in each stage than the time for raindrops to adhere and spread. For this reason, when dripping water occurs, the value of the adhesion amount gradient increases rapidly, and the value is maintained while dripping water travels through the detection region. That is, when dripping water is generated, the value of the adhesion amount gradient increases rapidly, and the state lasts for a much longer time than in the case of raindrop adhesion. Therefore, for example, if a threshold time, which is a time during which a state in which the threshold value of the adhesion amount gradient and the value of the adhesion amount gradient are equal to or greater than the respective threshold values, is continuously set, is set, When the duration of the time exceeds the threshold time, it is possible to accurately detect the occurrence of dripping water by determining that dripping water has occurred. When the occurrence of dripping water is detected in this manner, in the raindrop detection device according to claim 1 of the present invention, the wiper device drive control that has been executed by the controller is interrupted and continuous with respect to the wiper device. A drive signal is output so as to execute the dripping water elimination operation that is a plurality of wiping operations, and after the dripping water elimination operation ends, the interrupted wiper device drive control is resumed. Accordingly, by performing the wiping operation so as to accurately detect the occurrence of dripping water and immediately eliminate it, the driver's field of view can be reliably ensured. Furthermore, since the wiping operation is returned to the original wiping operation, that is, the wiping operation adapted to the rainy state after the dripping water removal operation is completed, the wiping operation control can be continuously executed without causing the driver to feel uncomfortable.

  In this case, as in the raindrop detection device according to claim 2 of the present invention, the determination means has a drooping water when the calculated adhesion amount gradient value exceeds a predetermined value and the state continuously reaches a predetermined time. If it is determined that the state has occurred, dripping water can be reliably detected.

  Further, as in the raindrop detection device according to claim 3 of the present invention, the predetermined time is more reliably than the time during which the value of the adhesion amount gradient that can be developed under normal rain conditions continuously exceeds the predetermined value. If the configuration is set as a long time, it is possible to accurately determine the heavy rain state and the dripping water generation, and the dripping water generation can be reliably detected.

  Hereinafter, an embodiment of a raindrop detection apparatus according to the present invention will be described with reference to FIGS. 1 to 5 by taking as an example a case where the raindrop detection apparatus is applied to a raindrop detection apparatus 1 mounted on an automobile.

  The raindrop detection device 1 is mounted on the automobile 100 and controls the operation of the wiper device 10 for wiping raindrops attached to the front windshield 101 that is a windshield in front of the driver's seat according to the operation position of the wiper control switch 30. Is. In particular, when the automatic control (AUTO mode) position is selected in the wiper control switch 30, the amount of raindrops attached to the front windshield 101 is detected by the raindrop sensor 20, and the operation control of the wiper device 10 is performed based on the determination result. Do.

  First, the overall configuration of the raindrop detection apparatus 1 will be described.

  As shown in FIG. 1, the raindrop detection device 1 is a controller that drives the wiper device 10 based on a raindrop sensor 20, a wiper device 10, a wiper control switch 30, a signal from the wiper control switch 30, and a signal from the raindrop sensor 20. 50 or the like. The raindrop detection apparatus 1 is supplied with electric power from a battery (not shown) of the automobile 100 via an ignition switch (not shown) of the automobile 100.

  The wiper device 10 includes a wiper motor 11, a wiper blade 13 that performs a reciprocating wiping operation on the front windshield 101, and a driving torque generated by the wiper motor 11 is converted into a reciprocating motion and transmitted to the wiper blade 13 to be transmitted to the wiper blade 13. 13 is provided with a link mechanism 12 for reciprocating the same. The reciprocating wiping operation of the wiper blade 13 is executed by outputting a drive instruction signal to the wiper motor 11 from the wiping mode determination unit 51 provided in the controller 50. Although FIG. 1 shows a state in which the controller 50 and the wiper motor 11 are directly connected, there may be a drive device for the wiper motor 11 in the middle.

  The wiper control switch 30 is installed at the driver's seat in the automobile 100 and stops the reciprocating wiping operation of the wiper blade 13 (OFF mode), automatic control (AUTO mode), low speed operation (LO mode), and high speed operation (HI mode). ) Is switched by a driver's manual operation or the like. The wiper control switch 30 is rotated to any one of four operating positions, for example, so that one of these operation modes is selected. When one of the four operation modes described above is selected, the wiper control switch 30 outputs information about the selected operation mode to the controller 50 (wiping mode determination unit 51) described later.

  As shown in FIG. 3, the raindrop sensor 20 basically includes a light emitting element 21 such as a light emitting diode that emits infrared light toward the detection region Ad of the front windshield 101, and the light emitting element 21. And a light receiving element 22 such as a photodiode that outputs an output value corresponding to the amount of light received and reflected by the front windshield 101. As shown in FIG. 3, a prism 23 is installed between the light emitting element 21 and the light receiving element 22 and the front windshield 101. The light emitted from the light emitting element 21 travels through the prism 23 as shown by an arrow in FIG. 3 and reaches the outer surface of the front windshield 101, and the reflected light travels through the prism 23 and travels through the prism 23. 22 is incident. Moreover, the light emitting element 21, the light receiving element 22, and the prism 23 are accommodated in a casing 24 as shown in FIG. The light emitting element 21 is connected to the controller 50 via a light emitting element driving circuit (not shown), and the controller 50 controls the turning on / off of the light emitting element 21. The light receiving element 22 is connected to the controller 50 via a detection amplification circuit (not shown), and outputs a detection signal corresponding to the detected amount of raindrops to the controller 50. When no raindrops are attached to the detection area Ad, the infrared light emitted from the light emitting element 21 travels as shown by the solid line arrow in FIG. And is received by the light receiving element 22. However, when the raindrop D is attached to the detection area Ad, a part of the infrared light emitted from the light emitting element 21 is broken by the broken line in FIG. 3 via the raindrop D attached to the detection area Ad. Since it progresses as indicated by the arrow and exits from the front windshield 101, the amount of light received by the light receiving element 22 is reduced. As the amount of raindrops D attached to the detection area Ad increases, the amount of light emitted to the outside of the front windshield 101 increases, and the amount of light received by the light receiving element 22 decreases. Thereby, the amount of raindrops adhering to the detection area Ad can be detected based on the amount of light received by the light receiving element 22. In the raindrop detection apparatus 1 according to the embodiment of the present invention, the detection signal of the raindrop sensor 20 decreases as the amount of raindrops adhering to the detection area Ad increases, and the raindrop sensor 20 decreases as the amount of raindrops adhering to the detection area Ad decreases. The detection signal becomes large.

  The controller 50, which is a control device, is configured as an electric circuit including, for example, a microcomputer. Actually, a CPU that performs control processing and arithmetic processing, a read-only memory (ROM) for storing various programs and data, and writing are possible. It includes functions such as a storage device including a memory such as a random access memory (RAM), an input circuit such as an AD converter, an output circuit, and a power supply circuit.

  The controller 50 includes a wiping mode determination unit 51, a raindrop amount determination unit 52, and a dripping water determination unit 53 from a functional viewpoint. The raindrop amount determination unit 52 determines the amount of raindrops attached to the front windshield 101 based on the detection signal output from the raindrop sensor 20. The wiping mode determination unit 51 determines a wiping mode related to the wiping operation of the wiper blade 13 based on a signal from the wiper control switch 30 or a signal from the raindrop amount determination unit 52, and based on the determination result, the wiper A drive signal is output to the motor 11. That is, when the wiper control switch 30 is operated to a position other than automatic control (AUTO mode), the wiping mode determination unit 51 determines the wiping mode corresponding to the operated position, and executes the wiping mode. A drive signal is output to the wiper motor 11. On the other hand, when the wiper control switch 30 is operated to the automatic control (AUTO mode) position, the wiping mode determination unit 51 switches the wiping mode related to the wiping operation of the wiper blade 13 based on the signal from the raindrop amount determination unit 52. A determination is made and a drive signal is output to the wiper motor 11 to execute the wiping mode. The dripping water determination unit 53 determines the occurrence of dripping water based on the detection signal output from the raindrop sensor 20. Further, when the dripping water determination unit 53 determines that dripping water is generated, the dripping water determination unit 51 interrupts driving signal output to the wiper motor 11 being executed by the wiping mode determination unit 51, and the wiper motor 11 performs driving related to dripping water removal operation. A signal is output to cause the wiper blade 13 to perform a dripping water wiping operation. And the dripping water determination part 53 will restart the drive signal output with respect to the wiper motor 11 by the wiping mode determination part 51, if dripping water removal operation is completed.

  Here, dripping water refers to a phenomenon in which water different from raindrops, that is, a larger amount of water flows to the front windshield 101 than raindrops. Specifically, when the automobile decelerates, rainwater collected on the roof of the automobile 100 flows down to the front windshield, or accumulated water on the road splashed by the wheels of the oncoming vehicle falls into the front windshield 101. It is a phenomenon such as coming. The dripping water determination unit 53 provided in the controller 50 in the raindrop detection apparatus 1 according to the embodiment of the present invention is for detecting the occurrence of the dripping water phenomenon described above.

  In the raindrop detection device 1 according to an embodiment of the present invention, when the wiper control switch 30 is operated to automatic control (AUTO mode), the controller 50 has two types of operations, an automatic control operation of the wiper device 10 and a dripping water determination operation. Start control operations simultaneously in parallel.

  The automatic control operation of the wiper device 10 is generally performed when the AUTO mode is selected. This is because the wiping mode determination unit 51 performs the wiping mode by the wiper blade 13 based on the raindrop amount determined by the raindrop amount determination unit 52 based on the detection signal from the raindrop sensor 20, that is, the reciprocal wiping operation interval time by the wiper blade 13. And a drive instruction signal corresponding to the determined wiping mode is output to the wiper motor 11 to perform the wiping operation. At this time, the wiping mode determined by the wiping mode determination unit 51 includes a stop mode, a stop standby mode, a plurality of intermittent modes in which the reciprocal wiping operation interval time by the wiper blade 13 is sequentially shortened, a low speed mode, and a high speed mode. Yes. Here, in the raindrop detection apparatus 1 according to the embodiment of the present invention, the plurality of intermittent modes are, for example, 7.0 seconds, 3.3 seconds, 1.5 seconds, in order from the longer reciprocating wiping operation interval time. 0.6 seconds. The low speed mode and the high speed mode are the same as the low speed operation (LO mode) position and the high speed operation (HI mode) position set in the wiper control switch 30.

  On the other hand, in the dripping water determination operation, the dripping water determination unit 53 determines whether dripping water is generated based on the detection signal from the raindrop sensor 20, and when dripping water is generated, the dripping water determination unit 53 is in the wiping mode. The automatic control operation of the wiper device 10 by the determination unit 51 is interrupted, and a drive signal is directly output to the wiper motor 11 to cause the wiper blade 13 to perform a wiping operation. Thereafter, the automatic determination of the wiper device 10 by the mode determination unit 51 is performed. The operation is resumed.

  Next, the dripping water determination operation, which is a feature of the raindrop detection device 1 according to the embodiment of the present invention, will be described.

First, the dripping water determination principle in the raindrop detection apparatus 1 according to an embodiment of the present invention will be described. In the raindrop detection apparatus 1 according to the embodiment of the present invention, the sampling cycle, which is the detection signal capture cycle from the raindrop sensor 20 in the dripping water determination unit 53, is several msec, similar to the detection signal capture in the raindrop amount determination unit 52. . It is. The dripping water determination unit 53 calculates a raindrop amount gradient R, which is a change rate of the raindrop amount, using the raindrop amount S calculated based on the detection signal from the raindrop sensor 20. Here, a method of calculating the raindrop amount gradient R will be described. The raindrop amount gradient Rn at the n-th sampling is calculated by (Equation 1) using the raindrop amount S (n−1) and the n-th raindrop amount Sn at the (n−1) th sampling. Is done.
(Equation 1)
Rn = {Sn−S (n−1)} / sampling period The drooping water detection unit 53 calculates the raindrop amount gradient R in the manner described above for each detection signal sampling from the raindrop sensor 20. Immediately after the raindrop collides with the detection area Ad of the raindrop sensor 20 on the front windshield 101, the raindrop spreads along the front windshield surface, so that the value of the raindrop amount gradient R rises rapidly, and the sampling is performed several times thereafter. The state continues continuously. Eventually, the raindrop amount gradient R becomes zero. Next, when raindrops adhere again, the raindrop amount gradient R rises rapidly in the same manner as the previous time and continues during a plurality of samplings in which this state continues, and then returns to zero. During normal rain, the raindrop amount gradient R rises from 0 to a step shape, and the value continues during sampling a plurality of times and returns to 0 in a step shape. The time during which the large value of the raindrop amount gradient R is maintained corresponds to the size of the attached raindrop. Here, the raindrop amount gradient threshold Rs is set. Assuming that the maximum value of the raindrop amount gradient R that can appear in a normal rainfall state is the maximum raindrop amount gradient Rmax, the raindrop amount gradient threshold Rs is 0 <Rs <Rmax. In a normal rainfall state, the time during which the value of the raindrop amount gradient R continues to exceed the raindrop amount gradient threshold value Rs, that is, the number of times of sampling N becomes longer as the attached raindrop droplets become larger, and the longest time in a heavy rain state Is the maximum number of samplings Nmax. In other words, in the normal rainfall state, the number of sampling times N for which the value of the raindrop amount gradient R continues to exceed the raindrop amount gradient threshold value Rs is equal to or less than the sampling number Nmax. On the other hand, when dripping water is generated, the value of the raindrop amount gradient R rises from 0 in a stepped manner, and the value continues during a plurality of samplings. By the way, the amount of water per dripping water is much larger than the amount of water per raindrop. Therefore, when dripping water occurs, the time during which the value of the raindrop amount gradient R continues to exceed the raindrop amount gradient threshold value Rs, that is, the number of times of sampling N is much greater than the maximum number of times of sampling Nmax during normal rain. . Therefore, in the raindrop detection apparatus 1 according to the embodiment of the present invention, the sampling frequency threshold value Ns that is a sampling frequency larger than the maximum sampling frequency Nmax is set, and the value of the raindrop amount gradient R is continuously set to the raindrop amount gradient threshold value Rs. If the sampling count N that continues to exceed the threshold reaches the sampling count threshold Ns, it is determined that dripping water has occurred. The magnitude of the sampling frequency threshold Ns means the amount of water at the time when it is determined that dripping water is generated. Therefore, the smaller the sampling number threshold Ns, the faster the drooping water generation can be determined. Furthermore, a smaller amount of dripping water can be detected as the sampling frequency threshold Ns is smaller.

  As described above, in the raindrop detection apparatus 1 according to the embodiment of the present invention, the raindrop amount gradient R is calculated based on the detection signal from the raindrop sensor 20, and the occurrence of dripping water is determined based on the raindrop amount gradient R. Thereby, dripping water generation | occurrence | production can be determined correctly, distinguishing normal rain and dripping water clearly.

  Next, in the raindrop detection apparatus 1 according to one embodiment of the present invention, the dripping water determination process executed by the dripping water determination unit 53 will be described based on the flowchart of FIG.

  When automatic control (AUTO mode) is selected through manual operation of the wiper control switch 30 by the driver of the automobile 100, the controller 50 detects it and the operation of the raindrop detection device 1 is started. The dripping water detection process is started.

  First, in step 301, initialization is performed, and the raindrop amount S, the raindrop gradient R, and the detection signal capture counter N of the raindrop sensor 20 are reset.

  Subsequently, at step 302, the detection signal capture counter N of the raindrop sensor 20 is set to zero.

  Subsequently, in step 303, the raindrop amount S is detected based on the detection signal from the raindrop sensor 20. Subsequently, in step 304, the raindrop amount gradient R is calculated based on the raindrop amount S detected this time and the previous raindrop amount Sf which is the last detected raindrop amount.

  Subsequently, in step 305, it is determined whether or not the raindrop amount gradient R is equal to or greater than the raindrop amount gradient threshold Rs. As a result of the determination in step 305, if the raindrop amount gradient R ≧ raindrop amount gradient threshold value Rs is not satisfied, that is, the raindrop amount gradient R <raindrop amount gradient threshold value Rs, the processing is repeated from step 302. If the result of determination in step 305 is raindrop amount gradient R ≧ raindrop amount gradient threshold value Rs, the routine proceeds to the subsequent step 306, where 1 is added to the counter N for detecting the detection signal of the raindrop sensor 20.

  Subsequently, at step 307, it is determined whether or not the detection signal capture counter N of the raindrop sensor 20 has reached the number-of-times threshold Ns. If the result of determination in step 307 is that the counter N has not reached the number of times threshold Ns, the processing is repeated from step 303. If the result of determination in step 307 is that the counter N has reached the number-of-times threshold Ns, the state in which the raindrop amount gradient R is equal to or greater than the raindrop amount gradient threshold Rs is the number of times that the detection signal capture counter of the raindrop sensor 20 counts. That is, the drooping water determination unit 53 determines that dripping water is generated. Then, the process proceeds to step 308. In step 308, the wiper motor 11 drive signal is output, and the wiper motor 11 is driven to perform the wiping operation by the wiper blade 13 a predetermined number of times. When the wiper blade 13 completes the wiping operation of a predetermined number of times, for example, two or three reciprocations, the dripping water detection process is ended.

  Thereafter, the process starts from step 301.

  Next, the dripping water determination operation by the dripping water determination unit 53 of the raindrop detection device 1 according to the first embodiment of the present invention described above is based on the timing chart based on the actual running state under rain as shown in FIG. To summarize. In FIG. 5, (a) shows the time transition of the traveling speed of the automobile 100, and (b) shows the time transition of the amount of raindrops S attached to the detection area Ad calculated based on the detection signal from the raindrop sensor 20. (C) is a timing chart showing the time transition of the raindrop amount gradient R calculated based on the detected raindrop amount S, and (d) is a timing chart showing the time transition of the wiping operation state of the wiper blade 13.

  The automobile is traveling at a speed V1 as shown in FIG. It is assumed that the raining state is so-called light rain, and the wiping mode determination unit 51 of the controller 50 selects the intermittent mode. Under such circumstances, raindrops adhered to the detection area Ad of the front windshield 101 at times t1, t2, t3, and t4, and correspondingly calculated based on the detection signal from the raindrop sensor 20. The raindrop amount S increases stepwise as shown in FIG. That is, the raindrop amount detectable time Ta is from time t1 to time t5. Further, the raindrop amount gradient R, which is the rate of change of the raindrop amount S, exceeds the raindrop amount gradient threshold Rs at times t1, t2, t3, and t4, which are the timings when the raindrops are attached, as shown in FIG. The value increases for a moment, but immediately returns to zero. That is, the time Te during which the raindrop amount gradient R exceeds the raindrop amount gradient threshold Rs is much shorter than the threshold time Ts corresponding to the counter frequency threshold Ns. Therefore, the dripping water determination unit 53 determines that no dripping water is generated. The wiping operation of the wiper blade 13 is started at time t5 and is finished at time t6. In the raindrop amount detectable time Ta from the time t6 to the time t7, as in the case from the time t1 to the time t5, the raindrops adhere to the detection area Ad of the front windshield 101, the raindrop amount S, and the raindrop amount gradient. R is calculated as before.

  At the time t8 when the wiping operation of the wiper blade 13 is finished, the automobile starts to decelerate from the speed V1. When the car reaches the speed V2 at the time t9, the vehicle continues to travel at the speed V2 after the time t9. When the automobile starts to decelerate at time t8, almost simultaneously, rainwater staying on the roof of the automobile 100 is moved toward the front of the automobile 100 by the action of acceleration due to the deceleration and flows down to the front windshield 101. That is, after time t8, raindrops adhere to the detection area Ad of the front windshield 101 and dripping water flows in at the same time. Therefore, as shown in FIG. 5 (b), the raindrop amount S is the sum of raindrops (shown by a solid line in FIG. 5 (b)) and drooping water (one point in FIG. 5 (b)). (Shown with a chain line). On the other hand, the raindrop amount gradient R continues to exceed the raindrop amount gradient threshold Rs as shown in FIG. 5C because the raindrop amount S due to dripping water is large. That is, the raindrop amount gradient R is a combination of a substantially flat region that continues to exceed the raindrop amount gradient threshold value Rs, which is the amount caused by dripping water, and a portion that rises like a short-time spike caused by raindrop adhesion. When the time during which the raindrop amount gradient R continuously exceeds the raindrop amount gradient threshold value Rs reaches the threshold time Ts, that is, the time corresponding to the counter frequency threshold value Ns, at time t10, the dripping water determination unit 53 generates dripping water. Is determined. When the dripping water determination unit 53 determines that dripping water is generated, the driving signal is directly output to the wiper motor 11 at time 10 to cause the wiper blade 13 to perform a wiping operation. When the wiping operation of the wiper blade 13 is completed at time t11, the dripping water determination process by the dripping water determination means 53 is once ended, and the counter N is reset and restarted.

  As described above, according to the raindrop detection apparatus 1 according to the embodiment of the present invention, when the time during which the raindrop amount gradient R is continuously greater than or equal to the raindrop amount gradient threshold Rs reaches the threshold time Ts. It is determined that dripping water is generated. And simultaneously with determining that dripping water is generated, a drive signal is output to the wiper motor 11 so that the wiper blade 13 can perform the wiping operation. Then, the length of the threshold time Ts is set to be longer than the longest time of the time Te, which is the time during which the raindrop amount gradient R continuously exceeds the raindrop amount gradient threshold Rs in a normal rain condition. Thereby, dripping water generation | occurrence | production can be detected correctly distinguishing from rainfall. Since the wiper blade 13 is wiped at the same time as the detection, even if dripping water is generated, the wiper blade 13 can be wiped and removed immediately from the front windshield 101, and the driver's front view can be maintained well.

  Moreover, according to the raindrop detection apparatus 1 according to the embodiment of the present invention described above, dripping water is detected based only on the detection signal from the raindrop sensor 20. For this reason, since the speed signal or acceleration signal of the automobile 100 used for the drooping water detection process in the conventional raindrop detection device is unnecessary, the electrical circuit configuration of the raindrop detection device 1 can be simplified and simplified.

  In addition, although the case where the raindrop detection apparatus 1 according to the embodiment of the present invention described above is applied to the front windshield 101 has been described as an example, the target to which the raindrop detection apparatus 1 is applied is limited to the front windshield 101. It is not necessary, and may be applied to, for example, a rear windshield. Furthermore, the target to which the raindrop detection device 1 is attached may not be an automobile. For example, when applied to a windshield in front of a driver's seat of a railway vehicle, ship, aircraft, etc., as in the case of the above-described embodiment, dripping water can be reliably detected and removed immediately, so that a good visibility Can be secured

1 is a schematic diagram showing a state in which a raindrop detection device 1 according to an embodiment of the present invention is mounted on an automobile 100. FIG. 1 is a block diagram illustrating an overall configuration of a raindrop detection apparatus 1 according to an embodiment of the present invention. It is sectional drawing explaining the structure of the raindrop sensor 20, and is the III-III sectional view taken on the line in FIG. It is the flowchart which showed the specific process sequence of the dripping water determination process performed in the dripping water determination part 53 of the raindrop detection apparatus 1 by one Embodiment of this invention. (A) shows the time transition of the raindrop adhesion amount to the detection area Ad of the raindrop sensor, and (b) shows the time transition of the wiping mode determined from the raindrop amount calculated based on the detection signal from the raindrop sensor. (C) is a timing chart which shows the time transition of the wiping operation state of a wiper blade, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raindrop detection apparatus 10 Wiper apparatus 11 Wiper motor 12 Transmission mechanism 13 Wiper blade 20 Raindrop sensor 21 Light emitting element 22 Light receiving element 23 Prism 24 Casing 30 Wiper control switch 50 Controller 51 Wiping mode determination part 52 Raindrop amount determination part 53 Dripping water determination part 100 automobile 101 front windshield (windshield)
A wiping area Ad detection area N counter Ns counter threshold (threshold)
R Raindrop gradient (attachment gradient)
Rs Raindrop amount gradient threshold (threshold)
S amount of raindrop T time Ts threshold time (threshold)
t1-t13 Time V1, V2 Traveling speed

Claims (3)

A wiper device that moves the wiper blade to wipe off water droplets adhering to the windshield, and a raindrop that outputs a raindrop signal corresponding to the amount of water droplets adhering to the detection area set within the wiper blade wiping range on the windshield A raindrop detection apparatus comprising: a sensor; and a controller that calculates a raindrop amount by inputting the raindrop signal from the raindrop sensor and outputs a drive signal to the wiper device based on the calculated raindrop amount;
The controller is a water droplet detection means for detecting the amount of attached water droplets at predetermined intervals within the wiping cycle of the wiper device, and a rate of change of the amount of attached water droplets during each predetermined period detected by the water droplet detection means. An adhesion amount gradient calculating unit for calculating an adhesion amount gradient; and a determination unit for determining a water droplet adhesion state on the windshield based on the calculated adhesion amount gradient;
The determination means determines whether or not a dripping water phenomenon occurs when rainwater or the like that has accumulated on the roof of the vehicle flows down to a windshield based on the calculated transition state of the adhesion amount gradient, and determines that the dripping water state has occurred When this is done, the wiper device drive control that has been executed by the controller is interrupted, and the drive signal is output to cause the wiper device to execute a dripping water elimination operation that is a plurality of continuous wiping operations. Then, after the dripping water removal operation is completed, the suspended wiper device drive control is resumed.   The said determination means determines the said dripping water state generation | occurrence | production when the value of the calculated said adhesion amount gradient exceeds predetermined value and the state reaches | attains predetermined time continuously. Raindrop detection device.   3. The predetermined time is set as a time that is surely longer than a time during which the value of the adhesion amount gradient that can appear under normal rain conditions continues to exceed the predetermined value. The raindrop detection device described in 1.

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