JP2004237868A - Wiper control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately perform wiper control even if water repellency of the outside plate surface of a wind shield changes due to application of the water repellent agent and affects a sensor output, in a wiper control device which illuminates light on the outside plate surface through the wind shield, has a sensor outputting a signal according to intensity of the light reflected on the plate surface, calculates a raindrop amount adhered to the plate surface based on the sensor output, and controls a wiper based on the calculated result. <P>SOLUTION: The control device calculates the return amount of the output of a rain sensor 11 due to the water repellency after the output of the rain sensor 11 changes into the direction where the raindrop drops on the plate surface and the reflected light from the plate surface weakens, and reflects degree of the water repellency on the calculation of the raindrop amount by determining that the water repellency is high as return amount is large. The appropriate control of the wiper 2 is realized by avoiding the separation between the calculated raindrop amount in the case of the plate surface having high water repellency and an actual visibility. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiper control device for automatically wiping raindrops attached to a window glass of a vehicle, a ship, an aircraft, or the like, and more particularly to a control according to a raindrop amount.
[0002]
[Prior art]
As a basic equipment of an automobile, there is a wiper for wiping raindrops attached to an outer surface of a windshield. The wiper speed and the intermittent time are adjusted by the wiper control device, and the wiper is set to an operation state according to the intensity of rain. In order to automatically adjust the wiper speed and intermittent time of the wiper, a rain sensor for detecting raindrops is provided on the surface of the windshield on the passenger compartment side, and the amount of raindrops is calculated based on the detection signal of the rain sensor, There is one that feeds back to the wiping speed and intermittent time of the wiper (see Patent Document 1). The rain sensor has a light-emitting element and a light-receiving element, and receives light from the light-emitting element transmitted through the windshield and reflected by a plate surface outside the windshield with the light-receiving element, and outputs a signal corresponding to the received light intensity. It has become. This is based on the fact that the raindrops are thicker on the outer plate surface of the windshield and the intensity of the light reflected on the outer plate surface of the windshield decreases as the raindrop becomes wider.
[0003]
As a method of calculating the amount of raindrops based on the output of the rain sensor, there is the following method. FIG. 9 shows the change over time of the rain sensor output in a sunny state or immediately after wiping with a wiper. When raindrops drop, the reflected light on the outer plate surface of the windshield decreases, and the rain sensor output as raindrop detection output is obtained. Decreases. The rain sensor output decreases stepwise each time a raindrop drops. The reason why the lowered rain sensor output slightly returns is due to the water repellency of the windshield outer plate surface. The amount of raindrop is calculated each time the rain sensor output changes in the direction in which the raindrop drops on the outer plate surface of the windshield and the reflected light weakens (in the figure, *), and the integrated value of the change is calculated. Is the amount of raindrop. This is because the raindrop does not drop continuously at the windshield outer plate surface position to which the rain sensor responds, but drops intermittently. Therefore, the change amount corresponding to each drop of the raindrop is integrated. Thus, even with a rain sensor that is sensitive only to raindrops falling within a very narrow range, the amount of raindrops can be known with high accuracy.
[0004]
[Patent Document 1]
JP-A-58-89430
[0005]
[Problems to be solved by the invention]
By the way, in recent years, a water-repellent agent that imparts water repellency to an outer plate surface of a windshield by applying the plate to the outer plate surface has been widely used. Normally, when raindrops drip on the windshield outer plate surface, they spread in the surface direction and cover the entire windshield outer plate surface, obstructing visibility.However, in a windshield coated with a water repellent, immediately after dripping Even if they try to spread in the plane direction, they are immediately gathered in the form of a large number of islands by the action of the water repellent to suppress a decrease in visibility. Particularly, it has the effect of improving the visibility ahead of the vehicle through the windshield in a high-speed range of vehicle speed.
[0006]
However, when a water repellent is used, the return of the rain sensor output becomes large, and the raindrop amount is excessively calculated by the wiper control device even though the water repellent actually makes it easy to see. There is a possibility that the wiping speed and the intermittent time may become inconsistent with the actual visual recognition state.
[0007]
Further, the water repellent is gradually removed even after being applied, and some automobile users do not use the water repellent. For this reason, a certain amount of error must be allowed for both the windshield coated with the water repellent and the windshield coated with no water repellent, and a compromise must be made.
[0008]
The present invention has been made in view of the above circumstances, and provides a wiper control device that can appropriately control a wiper regardless of whether a water repellent is applied to a windshield to which a rain sensor is attached. The purpose is to:
[0009]
[Means for Solving the Problems]
In the invention according to claim 1, raindrop detection means for transmitting light through the windshield and irradiating light toward the outer plate surface of the windshield, and detecting raindrop by receiving reflected light reflected on the plate surface, Raindrop amount calculating means for calculating the amount of raindrops attached to the outer plate surface of the windshield based on the raindrop detection output from the raindrop detecting means, and calculating the amount of raindrops based on the calculated amount of raindrops. In a wiper control device that controls a wiper to be wiped,
Calculate the return amount of the raindrop detection output after the raindrop detection output changes in the direction in which the raindrop drops and the reflected light is weakened on the outer plate surface of the windshield, and the larger the return amount, the more the windshield Water repellency detecting means for determining that the water repellency of the outer plate surface is high,
The raindrop amount calculating means is set such that, when calculating the raindrop amount, the error caused by the return amount of the raindrop detection output is reduced as the water repellency is higher.
[0010]
The higher the water repellency of the windshield outer plate surface, the sooner the raindrops are dropped, the sooner it will spread in the surface direction of the windshield, the sooner it collects in a number of islands due to the water repellency. The raindrop detection output changes in the direction in which the reflected light is weakened by the dropping of the raindrop, but returns to the direction in which the reflected light is strengthened by gathering in an island shape as described above. This return amount corresponds well to the water repellency of the windshield outer plate surface, and the higher the water repellency, the larger the return amount. Therefore, the water repellency can be determined based on the return amount of the raindrop detection output.
[0011]
Therefore, by calculating the amount of raindrops reflecting the water repellency, it is possible to avoid the occurrence of mismatch such as wiping the wiper at a high speed even though the water repellency is high and the forward visibility is not so bad.
[0012]
According to a second aspect of the present invention, in the configuration of the first aspect, the water repellency detecting means compares the current raindrop detection output with the previous raindrop detection output to detect raindrops in a direction in which the reflected light is weakened. It is determined whether or not the output has changed, and a reference value setting means that sets a previous raindrop detection output as a reference value at the time of the determination when the determination is negative, and a threshold value or more that is set in advance from the reference value, When the raindrop detection output returns in the direction in which the reflected light increases, the windshield outer plate surface has high water repellency, and a determination means for binary-determining the water repellency is provided.
[0013]
The reference value is a value at the time when the raindrop detection output starts to return due to the water repellency of the windshield outer plate surface, and the amount of change in the return amount therefrom corresponds well to the water repellency of the windshield outer plate surface. Become. Implementation is easy because it can be realized only by arithmetic processing.
[0014]
According to a third aspect of the present invention, in the configuration of the first or second aspect, the water repellency detecting means is set so that the water repellency of the windshield outer plate surface is binary-determined.
On the side where the water repellency is low, the raindrop amount calculating means integrates the amount of change every time the raindrop detection output changes in a direction in which raindrops drop on the windshield outer plate surface and the reflected light weakens during a predetermined period. The value is set as the amount of raindrop, and on the side where the water repellency is higher, the amount of change in the raindrop detection output from the beginning to the end of the predetermined period is set as the amount of raindrop.
[0015]
When the water repellency of the outer surface of the windshield is low, the amount of raindrop can be known with high accuracy even if the raindrop intermittently drops, by integrating the amount of change in the raindrop detection output. When the water repellency is high, it is possible to avoid the influence of the error due to the integration of the return of the raindrop detection output for each raindrop caused by the water repellency.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an overall configuration of a wiper control device to which the present invention is applied. It comprises a rain sensor 11 and a switch 12 as a raindrop detecting means, and a control circuit 13 which receives signals from these, and the control circuit 13 outputs a control signal to a drive circuit 14 for driving a drive motor of the wiper 2. . As shown in FIG. 2, the rain sensor 11 has a general configuration, and a bracket (not shown) or the like is provided in a fan-shaped range where the wiper 2 of the automobile wipes out raindrops and at a position that is not conspicuous such as behind a rearview mirror. It is attached to the plate surface Wb inside the windshield W via the same. The lens 4 and the printed circuit board 5 are housed in a housing 31 having a shape opened on the windshield W side such that the lens 4 is on the windshield W side.
[0017]
The lens 4 has an elongated block shape, and the elongated bottom surface 4a is opposed to the inner surface Wb of the windshield W with the silicon sheet 32 interposed therebetween. The upper surface 4b of the lens 4 has a smooth convex surface connected to the end surfaces 4c and 4d in the longitudinal direction of the lens 4, and the two lens portions 41 and 42 where the main optical axis intersects above the lens 4. Is formed.
[0018]
On the printed circuit board 5, a light emitting diode (hereinafter, appropriately referred to as an LED) 61 is mounted on the main optical axis of one lens unit 41, and a photodiode (hereinafter, appropriately referred to) is mounted on the main optical axis of the other lens unit 41. 62). Circuits for driving the LED 61 and processing the output signal of the PD 62 are also formed on the printed circuit board 5. The light emitted from the LED 61 passes through one of the lens portions 41, is reflected by the lens end surface 4c, the plate surface Wa outside the windshield W, and the lens end surface 4d, and enters the PD 62. The intensity of light incident on the PD 62 is highest when raindrops are not attached to the windshield outer plate surface Wa, that is, when it is sunny, and when raindrops R are attached, the reflectivity at the windshield outer plate surface Wa decreases, The scattered light from the windshield W to the outside increases and decreases according to the amount of raindrops attached. A signal corresponding to the intensity of the light incident on the PD 62 is input to the control circuit 13 as a sensor output. The sensor output is a raindrop detection output corresponding to the amount of raindrops deposited, and the wiper 2 is controlled based on this output.
[0019]
The switch 12 is for switching the control mode of the wiper 2 by the driver, and is attached to the tip of the turn signal switch or the like. The control mode switched by the switch 12 includes a mode for controlling the wiper 2 based on the sensor output from the rain sensor 11, an off mode for forcibly prohibiting the operation of the wiper 2, and a mode for forcibly operating the wiper 2. There are several manual modes for running.
[0020]
The control circuit 13 is mainly configured by a microcomputer, for example, and a control signal output from the control circuit 13 switches on and off a relay and the like constituting the drive circuit 14. 3 and 4 show the contents of the control program executed by the microcomputer of the control circuit 13. This flow starts with the ignition on. In step S101, variables and the like used in this flow are initialized.
[0021]
In step S102, a sensor output reduction rate is calculated. In this method, the current sensor output value is subtracted from the sensor output value (reference sensor output value) in a state where the sensor output is not substantially reduced by raindrops, and this is used as the sensor output reduction rate. As described above, the sensor output decreases as the amount of raindrops attached increases, so that the sensor output reduction rate indicates the attachment rate of raindrops as is known from the content of the calculation, and is referred to as the raindrop attachment rate as appropriate in the following description. Note that the reference sensor output value is given by the output value immediately after the wiper 2 first crosses the front of the rain sensor 11 after the start of the operation of the wiper 2. This is because the sensor output value when there is no raindrop fluctuates depending on the specification of the windshield W and the like, and if a fixed value is set, the versatility is reduced.
[0022]
In step S103, it is determined whether or not the wiper stop mode is set. The wiper stop mode is a state in which the rain sensor 2 can regard raindrops as insensitive and clear, and the wiper 2 is stopped. Other operation modes of the wiper 2 include an “intermittent wiping mode” in which the wiper 2 is controlled so that the wiper 2 operates at predetermined intervals, and the wiper 2 reciprocates continuously without an operation interval. There is a “continuous wiping mode” for controlling the wiper 2. In the “continuous wiping mode”, a plurality of types (for example, high speed (HI) and low speed (LO)) are prepared depending on the operation speed of the wiper 2.
[0023]
In step S104, it is determined whether the raindrop has adhered to the windshield outer plate surface Wa. This is determined to be affirmative when the sensor output falls below a preset threshold. Here, the threshold value is, for example, a value at which the intensity of the reflected light received by the PD 62 can be regarded as 2% or less of the intensity of the light emitted from the LED 61. If a negative determination is made, the process returns to step S102, and steps S102 to S104 are repeated until it is determined that there is a raindrop in step S104.
[0024]
When step S104 is affirmatively determined, processing for controlling the wiper 2 based on the sensor output is executed after step S105. First, in step S105, the initial raindrop amount is set as the average raindrop amount. Here, the average raindrop amount is a representative value of the raindrop amount, and is basically calculated by a moving average as described later. In step S106, it is determined whether or not the average raindrop amount is equal to or greater than a preset high-speed wiping raindrop amount. If an affirmative determination is made, the average raindrop amount is set to the value of the high-speed wiping raindrop amount in step S107, and the process proceeds to step S108. If a negative determination is made, the process skips step S107 and proceeds to step S108.
[0025]
In step S108, the wiping speed is determined based on the average raindrop amount. FIG. 5 shows the contents of the wiping speed determination processing (step S108). In step S201, it is determined whether or not the wiping has been performed by the wiper 2 without affirmatively determining the raindrop determination (step S104). This is because the wiping is started when the raindrop determination (step S104) is affirmative, but since the detection range of the rain sensor 11 is limited, if the rainfall is not so large, the raindrop determination is performed in the second and subsequent wiping operations (step S104). A negative determination is made in step S104). Step S201 is processing for detecting this. If an affirmative determination is made in step S201, the number of times of idle wiping is incremented in step S202, and the process proceeds to step S204. If a negative determination is made in step S201, the number of times of wiping is reset in step S203, and the process proceeds to step S204. Therefore, the number of times of empty wiping continues to increase only when the raindrop determination (step S104) is continuously affirmed, and it is possible to know with high accuracy that the rainfall is not so large even with the rain sensor 11 having a narrow detection range. It has become.
[0026]
In step S204, it is determined whether or not the average raindrop amount is the high-speed wiping raindrop amount (S107). If an affirmative determination is made, in step S205, the high-side wiping speed (HI wiping) of the two high-low wiping speeds is determined. Speed), and the wiping speed determination process ends. If a negative determination is made in step S204, the low-side wiping speed (LO wiping speed) is set in step S206, and the wiping speed determination process ends. As described above, when the amount of raindrops is large, the wiping speed is stopped following the amount of raindrops.
[0027]
In step S109 following the wiping speed determination process (step S108), an intermittent time setting process for setting an intermittent time is executed. FIG. 6 shows the contents of the intermittent time setting process (step S109). In step S301, it is determined whether or not the number of idle wiping operations (steps S202 and S203) is 5 or more. In step S302, an interval (intermittent time) is calculated. In step S303, it is determined whether or not the calculated intermittent time is equal to or greater than a preset upper limit value (for example, 12 seconds, which will be the same in the following description).
[0028]
If the intermittent time is set to 12 seconds or less and a negative determination is made in step S303, it is determined in step S304 whether or not the stopped state of the wiper has reached the calculated intermittent time. Step S304 is repeated until the calculated intermittent time elapses. If the calculated intermittent time elapses and step S304 is affirmed, the intermittent time setting process (step S109) ends.
[0029]
In addition, the determination of wiping without rain determination (S201) is successively affirmed five times or more, and the number of times of wiping is five or more (step S301), or the calculated intermittent time (step S302) is 12 seconds. If it is longer than this (step S303), it is determined that wiping of raindrops by the wiper 2 is unnecessary, a request to stop wiping of the wiper 2 is made in step S305, and the intermittent time setting process (step S109) ends.
[0030]
In step S110 following the intermittent time setting process (step S109), it is determined whether or not to stop wiping based on the presence or absence of the wiping stop request (step S305). If the determination is affirmative, the process returns to step S102. If the determination is negative, the wiper 2 wipes the raindrops in step S111, and the process returns to step S102.
[0031]
When a negative determination is made in step S103, that is, in the mode in which the wiper 2 operates, the process proceeds to step S112. Step S112 is a process as a water repellency detecting means for determining whether the windshield W is water repellent glass, and this is shown in FIG.
[0032]
In step S401, it is determined whether or not the water-repellent glass determination is ON. If the determination is affirmative, the processing after step S402 is skipped, and the present flow ends.
[0033]
If a negative determination is made in step S401, the process proceeds to step S402. Steps S402 and S403 are processing as reference value setting means, and determine whether the current reduction rate calculated in step 102 is larger than the previous reduction rate. If an affirmative determination is made, that is, if the sensor output decrease rate has increased from the previous time to the present, the process skips step S403 and proceeds to step S404. If a negative determination is made in step S402, that is, if the sensor output reduction rate has decreased from the previous time to the current time, in step S403, the previous value of the sensor output reduction rate is set as the reference value, the maximum reduction rate. Proceed to S404.
[0034]
The processing in step S403 has the following meaning. That is, the sensor output reduction rate increases due to the dropping of raindrops, but in this case, the determination in step S403 is affirmative. Then, when the sensor output reduction rate returns due to the water repellency of the windshield outer surface Wa, a negative determination is made in step S402, and the maximum reduction rate is set as the previous value of the sensor output reduction rate (step S403). This is because it is possible to determine that the sensor output decrease rate has become the maximum the previous time because the sensor output decrease rate has returned. That is, the maximum reduction rate is a maximum value at which the sensor output reduction rate reaches by one drop of raindrop. Then, in the present and subsequent processes, the sensor output reduction rate gradually decreases from the maximum reduction rate. The reduction width increases as the water repellency of the windshield outer surface Wa increases.
[0035]
In step S404, it is determined whether or not a water-repellent determination counter described below is 3 or more. The water-repellent determination counter indicates the number of times that the possibility that the windshield W is water-repellent glass is affirmed in step S406 described below. If the counter is three or more, the windshield W is determined to be water-repellent glass. That is, if a positive determination is made in step S404, the water-repellent glass determination is turned on in step S405, and the flow ends.
[0036]
If a negative determination is made in step S404, the process proceeds to step S406. Step S406 is processing as determination means, in which the current sensor output decrease rate is subtracted from the maximum decrease rate, this is compared with a preset threshold T, and the current sensor output decrease rate is subtracted from the maximum decrease rate. It is determined whether it is larger than the threshold value T.
[0037]
8 (A) and 8 (B) show the change over time of the sensor output reduction rate. FIG. 8 (A) shows the case of a normal windshield (hereinafter, appropriately referred to as a case of not water-repellent glass). FIG. 8B shows a case where the water repellency is high by applying a water repellent to the windshield outer plate surface Wa (hereinafter, appropriately referred to as a water repellent glass). Accordingly, a case where step S406 is determined to be affirmative and a case where step S406 is determined to be negative will be described. When rainfall occurs and raindrops drop onto the windshield outer plate surface Wa, the sensor output decreases as described above.However, since the raindrops once become a very thin film at the time of falling and then slightly rise due to surface tension, the reflectance is low. It recovers slightly, and the sensor output recovers slightly. That is, the sensor output reduction rate increased by the drop of the raindrop returns. This behavior appears regardless of whether the glass is water-repellent. However, the higher the water repellency, the more remarkable the swelling of raindrops. Therefore, when the windshield W is water-repellent glass, the sensor output reduction rate is lower. The return amount is large. That is, the sensor output decrease rate drops significantly from the maximum decrease rate. Therefore, if the threshold value T is appropriately selected, it is possible to distinguish between a case where the windshield W is made of water-repellent glass and a case where it is not. That is, if the value obtained by subtracting the current sensor output reduction rate from the maximum reduction rate is greater than the threshold value T, the possibility of water-repellent glass is high, and if the value is smaller than the threshold value T, the possibility of non-water-repellent glass is high. become.
[0038]
If (maximum decrease rate-current sensor output decrease rate) is larger than the threshold value T and the determination in step S406 is affirmative, the water-repellent counter is incremented by "1" in step S407, and this flow ends. If a negative determination is made in step S406, the water-repellent counter is set to "0" in step S408, the water-repellent glass determination is turned off in step S409, and the flow ends.
[0039]
As a result, the water-repellent glass determination is not turned on unless step S406 for determining whether (maximum reduction rate-current sensor output reduction rate) is greater than the threshold value T is repeated three times in succession. In addition, erroneous determination due to noise or the like is prevented, and the accuracy of determination as to whether or not the glass is water-repellent is increased.
[0040]
Steps S113 to S117 following the water-repellent glass determination processing (step S112) are processing as raindrop amount calculating means. In step S113, whether the windshield W is water-repellent glass based on the water-repellent glass determination result in step S112. If a negative determination is made, it is determined in step S114 whether or not the previous sensor output reduction rate is smaller than the current sensor output reduction rate. The previous sensor output decrease rate is subtracted, and this is added to the accumulated raindrop amount. After execution of step S115, the process proceeds to step S116. If a negative determination is made in step S114, the process skips step S115 and proceeds to step S116. That is, only when the sensor output decrease rate increases, the value obtained by subtracting the previous value from the current value is integrated.
[0041]
Steps S114 and S115 have the following meanings. That is, during the period when the sensor output decrease rate is increasing, the raindrop drops on the windshield outer plate surface Wa and the sensor output decrease ratio starts to increase, and then the sensor output decrease ratio is based on the water repellency of the windshield outer plate surface Wa. This is a period until the sensor output decrease rate turns to the decreasing direction. Therefore, when the (current value-previous value) is integrated in this period, a value obtained by integrating only the increasing width of the sensor output reduction rate due to the drop of the raindrop is obtained.
[0042]
On the other hand, if step S113 for determining whether or not the windshield W is water-repellent glass is negative, it is determined in step S118 whether or not the previous sensor output reduction rate is smaller than the current sensor output reduction rate. If it is determined, the current value is set as the maximum decrease rate in step S119. Step S119 is performed, and the process proceeds to Step S116. If a negative determination is made in step S118, the process skips step S119 and proceeds to step S116. That is, the maximum reduction rate is updated to the maximum sensor output reduction rate up to this time.
[0043]
In step S116, it is determined whether or not it is during a rain determination period which is a predetermined period. This is determined based on whether or not the timing at which the wiper 2 crosses the position facing the rain sensor 11 (the position of the sensor 11) with the windshield W interposed therebetween. . The operating state of the wiper 2 is known based on a control signal to the drive circuit 14.
[0044]
If a positive determination is made, the process returns to step S102.
[0045]
If a negative determination is made in step S1116, an average raindrop amount is calculated in step S117 based on the integrated raindrop amount or the maximum reduction rate obtained in step S115 or S119. The accumulated amount of raindrops adheres to the windshield Wa while the step S116 is negatively determined during the rain determination period, that is, after the wiper 2 wipes the raindrops until the wiper 2 next wipes the raindrops. This is an integrated amount during a period in which the front view through the windshield W is blocked by the raindrops. The maximum decrease rate is the maximum value of the sensor output decrease rate finally reached during the period, but can also be referred to as a change amount of the sensor output decrease rate from the beginning to the end of the period.
[0046]
The average is a moving average of the accumulated raindrop amount or the maximum reduction rate for 16 times including the latest accumulated raindrop amount or the maximum reduction rate for the latest 15 times calculated in the past, in addition to the accumulated raindrop amount or the maximum reduction rate. After the calculation of the average value, the oldest one of the stored accumulated raindrop amounts or maximum reduction rates is rewritten with the current accumulated raindrop amount or maximum reduction rate. Note that the accumulated raindrop amount as a variable used in the calculation of the accumulated raindrop amount in step S115 is reset to an initial value after the execution of this process, and becomes the accumulated raindrop amount during the rain determination period as described above. When step S117 is performed, the process proceeds to step S106.
[0047]
According to the present invention, when it is determined that the glass is water-repellent, the average amount of raindrop is calculated based on the maximum drop rate, so that the return of the sensor output drop rate that occurs every drop of raindrop becomes an error and does not accumulate. This prevents the amount of raindrops from being excessively recognized, and prevents the wiper 2 from wiping at a high speed when a low wiping speed is sufficient.
[0048]
In addition, every time there is rain after the ignition is turned on, it is determined whether the user is a water-repellent glass and the method of calculating the amount of raindrops is switched each time. Irrespective of the absence, even if the water repellency changes according to the elapsed time after the application of the water repellent, the amount of raindrops is appropriately determined, so that the practicality is high.
[0049]
In the present embodiment, the integrated raindrop amount is obtained when the glass is not the water-repellent glass, and the maximum reduction rate is calculated when the glass is the water-repellent glass. However, the present invention is not necessarily limited to this. Raindrops are transmitted through the windshield and radiated toward the outer plate surface of the windshield, and raindrops are detected using raindrop detection means that receives reflected light reflected from the plate surface and outputs a signal corresponding to the intensity of the reflected light. If the amount is to be obtained, if the water repellency on the windshield outer plate surface is high, the reflected light will be affected and the measurement error of the raindrop amount will increase, so determine the level of water repellency and according to the water repellency By determining the amount of raindrops, the wiper can be properly controlled.
[0050]
In the present embodiment, the wiper control device 1 has a configuration in which the rain sensor 11, the switch 12, the control circuit 13, and the drive circuit 14 are independently provided as shown in FIG. The same effect can be obtained with a configuration in which at least two or more of them are combined. For example, by forming the control circuit 13 on the substrate 5 of FIG. 2, the rain sensor 11 and the control circuit 13 are integrated.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a wiper control device according to the present invention.
FIG. 2 is a sectional view of a rain sensor included in the wiper control device.
FIG. 3 is a first flowchart showing control contents executed by a control circuit constituting the wiper control device.
FIG. 4 is a second flowchart showing control contents executed by a control circuit constituting the wiper control device.
FIG. 5 is a third flowchart showing control contents executed by a control circuit constituting the wiper control device.
FIG. 6 is a fourth flowchart showing control contents executed by a control circuit constituting the wiper control device.
FIG. 7 is a fifth flowchart showing control contents executed by a control circuit constituting the wiper control device.
FIGS. 8A and 8B are graphs illustrating the change over time of the output decrease rate of the rain sensor for explaining the operation of the wiper control device.
FIG. 9 is a graph showing the change over time of the output of the rain sensor.
[Explanation of symbols]
1 controller
11 Rain sensor
12 switches
13 control circuit (raindrop amount calculation means, water repellency detection means, reference value setting means, determination means)
14 Drive circuit
2 Wipers
W windshield
Wa Outside plate surface

Claims (3)

A raindrop detecting means for transmitting light through the windshield to a plate surface outside the windshield and receiving reflected light reflected from the plate surface to detect raindrops; and detecting raindrops from the raindrop detecting means. Raindrop amount calculating means for calculating the amount of raindrops attached to the outer plate surface of the windshield based on the output, and a wiper control for controlling a wiper for wiping the raindrops based on the calculated raindrop amount. In the device,
Calculate the return amount of the raindrop detection output after the raindrop detection output changes in the direction in which the raindrop drops and the reflected light is weakened on the outer plate surface of the windshield, and the larger the return amount, the more the windshield Water repellency detecting means for determining that the water repellency of the outer plate surface is high,
A wiper control device, wherein the raindrop amount calculation means is set such that, when calculating the raindrop amount, the error caused by the return amount of the raindrop detection output is reduced as the water repellency is higher. 2. The wiper control device according to claim 1, wherein the water repellency detecting means compares a current raindrop detection output with a previous raindrop detection output, and determines whether the raindrop detection output changes in a direction in which the reflected light is weakened. And a reference value setting unit that uses the previous raindrop detection output at the time of the determination as a reference value when the determination is negative, and a raindrop in a direction in which the reflected light increases from the reference value by a predetermined threshold or more. When the detection output is returned, a wiper control device comprising: a windshield outer plate surface having high water repellency; The wiper control device according to any one of claims 1 and 2, wherein the water repellency detecting means is set to perform a binary determination of the water repellency of the windshield outer plate surface,
On the side where the water repellency is low, the raindrop amount calculating means integrates the amount of change every time the raindrop detection output changes in a direction in which raindrops drop on the windshield outer plate surface and the reflected light weakens during a predetermined period. A wiper control device in which a value is defined as a raindrop amount, and a change amount of a raindrop detection output from the beginning to the end of a predetermined period is set as a raindrop amount on the side where the water repellency is high.

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