JP4371076B2 - Rain sensor - Google Patents

Description

  The present invention relates to a rain sensor that detects the presence or absence of rain, for example, for wiper drive control of an automobile.

  Conventionally, as this type of rain sensor, for example, a sensor described in Patent Document 1 is known. FIG. 11 and FIG. 12 show an outline of an example of such a rain sensor based on the sensor (attachment sensor) described in Patent Document 1.

  As shown in FIG. 11, this sensor is an image signal obtained through the imaging device 20 including the imaging device 20 provided in the room mirror 11 to image a predetermined area from the interior of the automobile through the front window 10. Is basically provided with an image processing unit 140 for performing required image processing. The image processing result by the image processing unit 140 is given to the determination / control unit 150, and the driving of the wiper 70 via the drive unit 60 is controlled through the determination / control unit 150. On the other hand, the sensor includes an emblem 180 on a hood outside the passenger compartment. The emblem 180 is a part that receives an emission command from the determination / control unit 150 and emits infrared light toward the imaging device 20 shown as an optical path L in FIG.

  FIG. 12 is a block diagram showing the electrical configuration of such a sensor and a portion for controlling driving of the wiper. Next, referring to FIG. The operation of the portion that performs drive control will be briefly described.

In such a sensor, first, when a light emission command is output from the determination / control unit 150 to the emblem 180, infrared light is emitted from the emblem 180 toward the imaging device 20, and the emitted infrared light is transmitted. The outer shape of the emblem 180 is imaged on the imaging device 20 via a lens in the imaging device 20. The formed image of the emblem 180 is output from the imaging device 20 to the image processing unit 140 as an image signal. The image processing unit 140 checks whether or not the outer shape of the emblem 180 is imaged as an image signal based on the luminance of the image signal acquired by the imaging device 20, and then uses the emblem for the image signal. 180 is output to the determination / control unit 150 as an actual pattern indicating the respective outer shape. That is, the actual pattern is image information of the emblem 180 at the time when the image is captured by the imaging device 20. On the other hand, the determination / control unit 150 stores and holds a basic pattern which is image information when there is no deposit such as raindrops on the front window 10 and the outer shape of the emblem 180 is accurately imaged on the imaging device 20. The basic pattern is read from the storage unit 30 as the actual pattern is acquired. Then, the judgment / control unit 150 calculates the number of pixels of the actual pattern in which the pixel states match, that is, the number of matching pixels S based on the comparison between the actual pattern and the basic pattern. When S is larger than a predetermined threshold, it is determined that no raindrops or the like are attached to the front window 10. That is, in this case, the wiper 70 is not driven through the drive unit (motor) 60. On the other hand, when the number of matching pixels S is smaller than a predetermined threshold value, it is determined that raindrops or the like are attached to the front window 10 through the determination / control unit 150. In this case, the wiper 70 through the drive unit 60 is determined. Driving is executed.
JP-A-9-189533

  As described above, in the conventional rain sensor, when the actual pattern of the emblem 180 provided on the hood obtained through the imaging device 20 is compared with the basic pattern stored and held in the storage unit 30, the coincidence is obtained. Based on the value of the number of pixels S, the presence or absence of raindrops adhering to the front window 10 and the amount of raindrops are determined. Therefore, it is possible to easily automate the wiper drive control in accordance with the presence / absence of raindrops and the amount of raindrops to be determined (detected).

  However, in the sensor, as described above, the actual pattern is obtained by emitting infrared light from the emblem 180 toward the imaging device 20 under the light emission command from the determination / control unit 150. Therefore, it is essential that the emblem 180 and the imaging device 20 are connected by a straight line, and there should be no obstacle between them. This also applies to a configuration in which an image is captured as an actual pattern by the imaging device 20 without necessarily generating infrared light from the emblem 180, and the emblem 180 and the imaging device 20 are also directly connected. , It must be in a relationship connected by a straight line. Therefore, for example, for a vehicle in which the emblem 180 is not mounted, or a vehicle in which the emblem 180 cannot be directly captured by the imaging device 20 even if the emblem 180 is mounted, because the bonnet has a large gradient. It is difficult to apply such a sensor.

  The present invention has been made in view of such circumstances, and while using an imaging device, relaxes the positional restriction with respect to the imaging target, and whether or not there is rainfall without being limited to the vehicle type or vehicle structure It is an object of the present invention to provide a rain sensor that can accurately detect the above.

  In order to achieve such an object, the invention described in claim 1 includes an imaging device that captures an image from the passenger compartment of the vehicle through the front window, and whether there is rainfall based on image information of the image captured through the imaging device. As a rain sensor for detecting the image, a virtual image of an image of a specific element reflected in the vehicle interior reflected in the front window is captured by the imaging device, and the presence or absence of the rain is determined based on the transition of image information of the captured virtual image. Judgment means for judging is provided.

  Regardless of the type of vehicle and the structure of the vehicle, the reflection of elements in the passenger compartment on the front window, that is, the virtual image of the image of the elements in the passenger compartment inevitably exists as a physical phenomenon. Further, in view of the fact that such a virtual image appears as a reflection on the front window of the vehicle, the image information thereof naturally changes depending on the state of the front window surface, that is, the presence or absence of raindrops, the amount of rain, or the like. Therefore, according to the above-described configuration as a rain sensor, it is possible to accurately detect the presence or absence of rainfall regardless of the vehicle type or the vehicle structure by tracking the transition of such virtual image information through the determination means. Will be able to.

  In the rain sensor according to claim 1, in the invention according to claim 2, the determination unit determines in advance whether or not there is rain based on the transition of the image information of the captured virtual image in a state without rain. The determination is made based on a comparison between image information of the captured virtual image or image information corresponding thereto and image information of the virtual image captured each time through the imaging device.

  Usually, when the image information is acquired through the imaging device, if the front window is actually in a state without rain, the image information of the virtual image captured in advance without rain and the image information through the imaging device each time. There is no difference between the image information of the virtual image to be captured. Therefore, in this case, it can be determined that no raindrops are attached to the surface of the front window, that is, there is no rain. On the contrary, when the image information is acquired through the imaging device, if the front window is in a rainy state, the image information of the virtual image captured in advance without raining and the like are taken through the imaging device each time. A difference occurs between the image information of the same virtual image. Therefore, in this case, it can be determined that raindrops are attached to the surface of the front window, that is, there is rain. In this regard, according to the above-described configuration as the rain sensor, it is possible to preferably determine the presence or absence of rainfall based on the comparison of the image information.

As such a determination means, for example, according to the invention described in claim 3,
(A1) Every time the virtual image image information is captured through the imaging device, the storage unit stores and holds the virtual image image information or the corresponding image information captured in advance without rain as a basic pattern. The presence or absence of the rain is determined by comparing this with a basic pattern stored and held in the storage means as an actual pattern.
Alternatively, as in the invention according to claim 4,
(A2) Image information of the virtual image captured in advance without rain or image information corresponding thereto, and image information of the virtual image captured stepwise according to the amount of rainfall or image information corresponding thereto A storage means for storing and holding a plurality of patterns as basic patterns is provided, and each time the image information of the virtual image is imaged through the imaging device, this is compared with each basic pattern stored and held in the storage means as a real pattern. Thus, the presence / absence of rainfall and the amount of rainfall are also determined.
Such an arrangement is also effective in accurately recognizing the difference between the image information.

  Incidentally, according to the configuration of the above (A1), the image comparison of the virtual image captured in advance without the rain is adopted as the basic pattern and the pattern comparison is performed. Therefore, it is determined whether there is rain or no rain. That is, it becomes possible to make a relatively easy determination regarding the presence or absence of rainfall. Further, according to the configuration of (A2), a plurality of information such as the image information of the virtual image captured in advance without the rain and the image information of the virtual image captured stepwise according to the amount of rainfall are basically used. Since it is adopted as a pattern and the above-described pattern comparison is performed, in addition to the determination regarding the presence or absence of rainfall, the determination regarding the amount of rainfall can be made relatively easily.

Further, as the determination means, for example, according to the invention described in claim 5,
(B1) Each time the virtual image information is captured through the imaging device, the storage unit stores and holds, as a basic pattern, image information of the virtual image captured in advance without rain or image information corresponding thereto. Then, a difference image from the basic pattern stored in the storage means is obtained as an actual pattern, and the presence or absence of the rain is determined based on the number of pixels constituting the difference image.
Alternatively, as in the invention according to claim 6,
(B2) Each time the virtual image information is captured through the imaging device, the storage unit stores and holds, as a basic pattern, image information of the virtual image captured in advance without rain or image information corresponding to the virtual image. Then, a difference image from the basic pattern stored in the storage means is obtained as an actual pattern, and the presence / absence of rainfall and the amount of rainfall are determined based on the number of pixels constituting the difference image. .
Such a configuration is also effective in accurately recognizing the difference between the image information.

  Incidentally, although the number of pixels constituting the difference image between the actual pattern and the basic pattern is obtained through a simple calculation process called difference calculation, it is an index that accurately represents the degree of similarity between these two patterns. One. That is, the greater the difference between the actual pattern and the basic pattern, the greater the number of pixels constituting the difference image. Conversely, the smaller the difference between the actual pattern and the basic pattern, the greater the difference image. The number of pixels to be reduced is reduced. Therefore, according to the configuration of (B1), since the image information of the virtual image captured in advance without the rain is used as a basic pattern, an increase in load on the arithmetic processing is suppressed to a minimum. In addition, it is possible to execute a determination regarding the presence or absence of rainfall based on the number of pixels constituting the difference image. Further, according to the configuration of (B2), in addition to determining whether there is rainfall or not based on the amount of pixels constituting the difference image, while appropriately suppressing an increase in the load on the arithmetic processing, it is also possible to Judgment on the amount can also be made.

  On the other hand, in the rain sensor according to claim 1, as in the invention according to claim 7, for example, a real image of an image of a specific element in the vehicle interior is captured through the imaging device, and as the determination unit Based on the comparison between the real image image information of the image of the specific element in the vehicle interior imaged through the imaging device and the image information of the virtual image of the image of the specific element imaged in the vehicle interior each time through the imaging device If the presence or absence of the rain is determined, the determination on the presence or absence of the rain can be suitably performed while simplifying the configuration.

In this case, as the determination means, specifically, for example, according to the invention described in claim 8,
(C1) The real image information of the image of the specific element in the vehicle interior imaged through the imaging device is used as a reference image, and each time the virtual image image information is captured through the imaging device, the reference is made as a real pattern. A difference image with respect to the image is obtained, and the presence or absence of the rain is determined based on the number of pixels constituting the difference image.
Alternatively, as in the invention according to claim 9,
(C2) The real image information of the image of the specific element in the vehicle interior imaged through the imaging device is used as a reference image, and each time the virtual image image information is captured through the imaging device, the reference is made as a real pattern. A difference image from the image is obtained, and the presence / absence of rainfall and the amount of rainfall are determined based on the amount of pixels constituting the difference image.
Such an arrangement is also effective in accurately recognizing the difference between the image information.

  By the way, according to the configuration of (C1) above, the above-mentioned storage means and the like are used in order to adopt a real image of a specific element image in the vehicle interior imaged through the imaging device as a reference image for comparing with a real pattern. Even if it is not used, it is possible to suitably make a determination regarding the presence or absence of rainfall based on the number of pixels constituting the difference image. Further, according to the configuration of (C2), it is possible to make a determination regarding the amount of rainfall in addition to the determination regarding the presence / absence of rainfall based on the amount of pixels constituting the difference image. .

  The rain sensor according to any one of claims 1 to 9 may further include an illumination source for illuminating a specific element in the vehicle interior, for example, according to the invention according to claim 10. The image of the specific element in the passenger compartment reflected in the front window becomes clear, and the image information of the virtual image can be acquired with higher contrast. As a result, the presence or absence of rainfall can be more accurately determined based on the transition of the image information of the captured virtual image.

  Further, in the rain sensor according to any one of claims 1 to 10, in the invention according to claim 11, the specific element in the vehicle interior is an air vent arranged on a dashboard.

  Usually, the vent holes arranged on the dashboard are formed by periodically repeating holes and partitions. On the other hand, raindrops adhering to the front window act as a so-called convex lens, and thus scatter light that enters the vehicle interior from outside the vehicle interior. Therefore, if there is a slight rain, that is, even if a small amount of raindrops are attached to the front window, the linearity of the image information of the ventilation port reflected on the front window, that is, the image information of the virtual image obtained through the imaging device is greatly disturbed. It will be. Further, when the amount of rainfall increases, that is, when more raindrops adhere to the front window, the flatness of the front window decreases. For this reason, the image of the ventilation port reflected in the front window, that is, the image information of the virtual image obtained through the imaging device is also greatly distorted. In this regard, according to the above-described configuration as a rain sensor, it is possible to detect the presence / absence and amount of raindrops adhering to the front window with high sensitivity.

  On the other hand, in order to achieve the above object, the invention according to claim 12 includes a line sensor that detects a line of an image from a vehicle interior through a front window, and includes image information of the line detected through the line sensor. As a rain sensor for detecting the presence or absence of rainfall based on the above, the line sensor detects a virtual image line of an image of a specific element reflected in the front window, and changes the image information of the detected virtual image line. Based on this, it is provided with a judging means for judging the presence or absence of the rain.

  Even in such a configuration, it is possible to detect the minimum rainfall as a rain sensor by tracking the transition of the image information of the virtual image of the specific element through the determination means.

(First embodiment)
Hereinafter, a rain sensor according to a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6, including wiper drive control.

  In this embodiment, as will be described in detail below, first, a virtual image of the image of the air vents arranged on the dashboard in the vehicle interior reflected in the front window is previously captured in the absence of rain through the imaging device. Then, the image information of the virtual image is stored and held in the storage unit as a basic pattern. Further, every time the image information of the virtual image is imaged through the imaging apparatus, a difference image from the previous basic pattern stored and held in the storage unit as an actual pattern is obtained. Then, by determining the presence or absence of rainfall and the amount of rainfall based on the amount of pixels constituting the difference image, the positional restriction with respect to the imaging target is relaxed and limited to the vehicle type or vehicle structure. It is designed to accurately detect the presence or absence of rainfall.

  FIG. 1 is a side view schematically showing the configuration of the rain sensor according to this embodiment, and FIG. 2 is a block diagram showing the flow of signals between the elements constituting the sensor. First, the configuration and function of this embodiment will be described in detail with reference to FIG. 1 and FIG.

As shown in FIGS. 1 and 2, the rain sensor of this embodiment is largely
A virtual image Vimg of the image of the air vent 80 arranged on the dashboard 12 in the vehicle interior that is provided on the support portion of the room mirror 11 in the vehicle interior and reflected on the front window 10 is displayed from the vehicle interior to the front window 10. An imaging device 20 that captures images through
A storage unit (storage unit) 30 that stores and holds, as a basic pattern, image information of the virtual image Vimg captured in advance through the imaging device 20 in the absence of rain.
Each time image information of the virtual image Vimg is captured through the imaging device 20, a difference image with the basic pattern stored and held in the storage unit 30 is obtained as a real pattern, and the number of pixels S constituting the difference image An image processing unit 40 for obtaining (amount of the number of pixels).
A pixel number S is input from the image processing unit 40, and the presence / absence of rainfall and the amount of rainfall are determined based on the pixel number S, and a wiper driving signal corresponding to the determination result is output to a driving unit (motor) 60. A determination / control unit (determination means) 50 for driving the wiper 70 by outputting to
And so on.

  Incidentally, in this embodiment, for example, a CCD (Charge Coupled Device) camera is employed as the imaging device 20. The imaging device 20 is provided with a lens, a CCD, and the like, and the depth of focus is arranged on the dashboard 12 in the passenger compartment without imaging the scenery in front of the front window 10 (outside the vehicle). The distance from which the light image from the vent 80 is reflected on the surface of the front window 10 and is formed on the CCD as a virtual image is set. That is, as shown in FIG. 1 as a virtual image Vimg, and in FIG. 3, the relationship between the imaging device 20, the front window 10, and the virtual image Vimg of the ventilation opening 80 is schematically shown from the side direction. In this CCD, the virtual image Vimg is formed on the CCD as if the ventilation opening 80 exists outside the vehicle. The imaging device 20 outputs the image information of the formed virtual image to the image processing unit 40 as a real pattern every time it captures the image information. Note that the image information obtained in this way is imaged with sufficient resolution to enable the required image processing in the determination / control unit 50.

  FIG. 4 and FIG. 5 are diagrams illustrating an example of an image used for calculation according to the following equation (1) performed by the image processing unit 40. Next, the processing performed by the image processing unit 40 will be described in detail with reference to FIGS. 4 and 5 together.

  The image processing unit 40 first determines the actual pattern image information f (x, y) obtained by the imaging device 20 when the determination / control unit 50 determines the presence or absence of rainfall, the amount of rainfall, and the drive control of the wiper 70. And the image information h (x, y) of the difference image between the basic pattern image information g (x, y) stored and held in the storage unit 30 according to the following equation (1).

h (x, y) = | f (x, y) −g (x, y) | (1)

That is, the image information h (x, y) of the difference image is the absolute value of the difference in luminance value at the same position coordinates of the image information f (x, y) of the real pattern and the image information g (x, y) of the basic pattern. When the luminance values at the same position coordinates are the same, “0” is obtained, and when the luminance values at the same position coordinates are different, “1” is obtained. In other words, an image in which different portions of these patterns are emphasized in black is obtained as the image information h (x, y) of the difference image.

  Here, FIG. 4A is an example of the basic pattern Rimg stored and held in the storage unit 30, and as described above, a virtual image of the ventilation port 80 imaged in advance through the imaging device 20 in a state without rain as described above. This is image information f (x, y). Therefore, as shown in FIG. 4A, the basic pattern Rimg is an image in which the hole portion and the partition portion are periodically repeated while the linearity is maintained.

  FIG. 4B is an example of the actual pattern IMG1 obtained each time through the imaging device 20, and there is a slight rainfall, that is, the imaging device 20 in a state where raindrops are slightly attached to the front window 10. The image information g (x, y) of the virtual image of the ventilation opening 80 imaged through. The raindrops adhering to the front window 10 act as a so-called convex lens, and thus scatter light that enters the vehicle interior from the outside of the vehicle interior. Therefore, the actual pattern IMG1 is a binary image in which a portion corresponding to a raindrop is relatively brighter than the other portions, and the raindrop is captured in a circular shape.

  FIG. 4C shows the difference image Dimg1 obtained by calculating the difference in accordance with the above expression (1) in the image processing unit 40. This difference image Dimg1 corresponds to the raindrop imaged as a circular shape in the actual pattern IMG1. The image is emphasized in black (the luminance value is small).

  On the other hand, FIG. 5 (a) is an example of the basic pattern Rimg stored and held in the storage unit 30 as in FIG. 4 (a), and the image pickup apparatus in advance without rain as described above. 20 is image information f (x, y) of a virtual image of the ventilation opening 80 imaged through 20. Therefore, as shown in FIG. 5A, the basic pattern Rimg is an image in which holes and partitions are periodically repeated while the linearity is maintained.

  FIG. 5B is an example of an actual pattern IMG2 obtained each time through the imaging device 20, and images are taken through the imaging device 20 in a state where there is a large amount of rainfall, that is, there are many raindrops attached to the front window 10. This is image information g (x, y) of the virtual image of the ventilation opening 80. Since the raindrops adhering to the front window 10 act as a so-called convex lens, the light incident on the vehicle interior from the outside of the vehicle interior is scattered as described above. However, when there are many raindrops, the raindrops cover the entire front window 10, so that the flatness of the front window 10 is further reduced. Therefore, the actual pattern IMG2 is a straight-line-distorted binary image corresponding to the partition part.

  FIG. 5C shows the difference image Dimg2 obtained by performing the difference calculation according to the above equation (1) in the image processing unit 40. FIG. 5C shows a portion imaged as a distorted straight line in the actual pattern IMG2. The portion corresponding to is emphasized in black (the luminance value is small).

  Therefore, the image processing unit 40 next calculates the number of pixels (the number of pixels) S constituting the difference images Dimg1 and Dimg2 shown in FIGS. 4 (c) and 5 (c). As can be seen from the comparison between FIG. 4A to FIG. 4C and FIG. 5A to FIG. 5C, the actual pattern IMG obtained through the imaging device 20 is stored in the storage unit 30 as the basic pattern Rimg. The farther it is from, the larger the area occupied by black spots in the difference image Dimg. Therefore, the number S of pixels constituting the difference image Dimg2 is larger than the number S of pixels constituting the difference image Dimg1. That is, the number S of pixels is one index that accurately represents the degree of similarity between the actual pattern and the basic pattern, and by extension, is one index that accurately represents the presence or absence of rainfall and the amount of rainfall.

  In addition, the determination / control unit 50 receives the number of pixels S from the image processing unit 40, and first determines the presence / absence of rainfall and the amount of rainfall based on the number of pixels S. As described above, the number of pixels S is one of the indexes that accurately represent the presence or absence of rainfall and the amount of rainfall. If it is determined that the pixel number S is larger than the predetermined first threshold value Sth1, it is determined that there is heavy rain. On the other hand, if it is determined that the value is smaller than the predetermined second threshold value Sth2 that is smaller than the first threshold value Sth1, it is determined that there is light rain. And when it is judged that it is neither of these, it is judged as rainy.

  Further, the determination / control unit 50 outputs a wiper drive signal corresponding to the determination result (that is, the number of pixels S) to the drive unit (motor) 60. That is, when the rain is determined to be a time when it is necessary to quickly wipe off the rain adhering to the front window 10, the wiper 70 is continuously driven in a short cycle. When it is determined that there is light rain, since there are not so many raindrops adhering to the front window 10, the intermittent wiper driving interval is set long. When it is determined that the rain is normal, the wiper intermittent drive interval is set to be short because the wiper does not need to be continuously driven but must be wiped in a timely manner. Note that the predetermined threshold values Sth1 and Sth2 are values obtained in advance by experiments or empirically.

  FIG. 6 shows a processing procedure of detection processing including wiper drive control executed through such a determination / control unit 50. Hereinafter, detection of this embodiment will be described with reference to FIG. The processing will be described in detail.

  In the rain sensor of this embodiment, a real pattern (virtual image) is first processed as a process in step 101 under the condition that the wiper 70 is driven by a wiper switch (not shown). ). That is, a virtual image of the ventilation openings 80 arranged on the dashboard 12 in the vehicle interior is captured as a real pattern IMG through the imaging device 20, and the image information f (x, y) is captured by the image processing unit 40.

  Then, as the processing of step S102, the image processing unit 40, the image information f (x, y) of the actual pattern IMG obtained by the processing of the previous step S101 and the image of the basic pattern Rimg stored and held in the storage unit 30. A difference image Dimg with the information g (x, y) is obtained according to the above equation (1). In the subsequent process of step S103, the image processing unit 40 obtains the number S of pixels constituting the difference image Dimg obtained by the process of step S102. As described above, the number of pixels S is one of the indexes that accurately represent the presence or absence of rainfall and the amount of rainfall.

  The pixel number S thus obtained is output from the image processing unit 40 to the determination / control unit 50, and the determination / control unit 50 sets the pixel number S to a predetermined first threshold value Sth1 as a process of step S104. It is judged whether it is larger. When it is determined that the number S of pixels is larger than the predetermined threshold value Sth1, the determination / control unit 50 determines “heavy rain” as the process of step S105, and then performs the process of step S106 with respect to the drive unit 60. A wiper drive signal corresponding to “wiper continuous drive” is output. As a result, the drive unit 60 continuously drives the wiper 70 in a manner designated by the wiper drive signal.

  On the other hand, when it is determined that the number of pixels S is smaller than the predetermined first threshold value Sth1 in the process of the previous step S104, the determination / control unit 50 performs the process of step S107 as the pixel number S and the previous threshold value. The magnitude is compared with a predetermined second threshold value Sth2 smaller than Sth1. When it is determined that the number S of pixels is larger than the predetermined second threshold value Sth2, it is determined that “normal rain” is performed in the subsequent step S108. In this case, “wiper intermittent drive interval = short” is set as the process of step S109, and a wiper drive signal corresponding to this “wiper intermittent drive interval = short” is output to the drive unit 60. As a result, the drive unit 60 is intermittently driven at an intermittent drive interval specified by the wiper drive signal, for example, an interval of “0.5 seconds”.

  If it is determined that the number of pixels S is smaller than the predetermined second threshold value Sth2 in the process of the previous step S107, the determination / control unit 50 determines “light rain” as the subsequent process of step S110. In this case, “wiper intermittent drive interval = long” is set as the process of step S111, and a wiper drive signal corresponding to this “wiper intermittent drive interval = long” is output to the drive unit 60. As a result, the drive unit 60 is intermittently driven at an intermittent drive interval designated by the wiper drive signal, for example, “2.0 seconds”.

As described above, according to the rain sensor of this embodiment, the following excellent effects can be obtained.
(1) The imaging device 20 captures a virtual image Vimg of the image of the ventilation opening 80 in the passenger compartment reflected in the front window 10. Thereby, the positional restriction with respect to the imaging target is relaxed, and it is possible to accurately detect the presence or absence of rainfall without being limited to the vehicle type or the vehicle structure.

  (2) Each time image information of the virtual image Vimg is captured through the imaging device 20, a difference image Dimg from the basic pattern Rimg stored and held in the storage unit 30 is obtained as a real pattern, and the difference image Dimg is obtained. The presence / absence of rainfall, the rainfall amount, and the wiper 70 are driven based on the number of pixels S to be configured. As a result, it is possible to perform wiping of the front window 10 and to determine whether there is rainfall or the like while suitably suppressing an increase in load on the arithmetic processing.

  (3) Further, the image information of the virtual image Vimg captured in advance without rain is stored and held in the storage unit 30 as the basic pattern Rimg. As a result, the image information of the basic pattern Rimg can be reliably output to the image processing unit 40.

(4) In addition, the ventilation openings 80 arranged on the dashboard 12 are adopted as specific elements in the passenger compartment reflected in the front window 10. As described above, this image pattern is a pattern in which holes and partitions are periodically repeated in a state where linearity is originally maintained. For this reason, through the tracking of the deformation mode of the same pattern, it is possible to suitably improve the sensitivity to the detection of the presence or absence of raindrops adhering to the front window 10 or the amount of raindrops.
(Second Embodiment)
Next, a second embodiment of the rain sensor according to the present invention will be described with reference to FIG. FIG. 7 is a front view schematically showing the configuration of the rain sensor according to this embodiment. In FIG. 7, the same elements as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant descriptions of these elements are omitted.

  The rain sensor of this embodiment is basically configured in accordance with the rain sensor shown in FIGS. However, in this embodiment, as shown in FIG. 7, an illumination source 90 for illuminating the ventilation openings 80 arranged on the dashboard 12 in the vehicle interior on the support portion of the room mirror 11 in the vehicle interior. Is further provided.

  In the rain sensor configured as described above, when acquiring an actual pattern through the imaging device 20, first, infrared light is emitted from the illumination source 90, and the emitted infrared light is shown in FIG. To the front window 10 in the form shown as the optical path L. In the state where the image of the air vent 80 in the vehicle interior reflected in the front window 10, more precisely, the density of the image in which the hole portion and the partition portion constituting the air vent 80 are periodically repeated is clear. The actual pattern IMG is acquired through the previous imaging device 20.

For this reason, according to the rain sensor of the second embodiment described above, in addition to the effects (1) to (4) of the first embodiment, the following effects can be newly obtained. become.
(5) The illumination source 90 for illuminating the ventilation openings 80 arranged on the dashboard 12 in the vehicle interior is provided on the support portion of the room mirror 11 in the vehicle interior. As a result, the image of the air vent 80 in the passenger compartment reflected in the front window 10 is acquired as the actual pattern IMG in a state in which the shade is clear. That is, the image information of the virtual image Vimg can be acquired with higher contrast. As a result, the presence / absence of rainfall and the amount of rainfall can be determined more accurately.
(Third embodiment)
Next, a rain sensor according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a front view schematically showing the configuration of the rain sensor according to this embodiment, and FIG. 9 is a block diagram showing the flow of signals between the elements constituting the sensor. Further, in FIGS. 8 and 9, the same elements as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and overlapping descriptions of these elements are omitted. .

  The rain sensor of this embodiment is basically configured in accordance with the rain sensor shown in FIGS. However, in this embodiment, instead of the storage unit that stores and holds the basic pattern, image information of a real image of the image of the air vent on the dashboard in the vehicle interior is used as a reference image. Then, every time the image information of the virtual image is imaged through the imaging device, a difference image from the reference image is obtained using this as a real pattern, and based on the number of pixels constituting the difference image (the amount of pixels), The presence / absence and rainfall are also judged.

  That is, in this case, when acquiring the difference image through the image processing unit 40a, first, the image information of the real image of the image of the ventilation port 80 is imaged through the imaging device 20 and acquired. Next, the image information of the virtual image of the ventilation opening 80 in the passenger compartment reflected in the front window 10, that is, the real pattern (virtual image) is captured through the imaging device 20 each time, and this is acquired. Then, the above-described difference image is obtained by calculating a difference between the reference image and the actual pattern in accordance with the equation (1).

According to the rain sensor of the third embodiment described above, in addition to the effects (1) to (4) of the first embodiment, the following effects can be newly obtained. become.
(6) Instead of the storage unit 30 that stores and holds the basic pattern, the image information of the real image of the image of the air vent 80 is adopted as the reference image on the dashboard 12 in the passenger compartment. As a result, it is possible to compare the reference image with the actual pattern without providing the previous storage unit and the like, and it is possible to simplify the configuration while maintaining the function as the rain sensor.
(Other embodiments)
Note that the rain sensor according to the present invention is not limited to the configuration exemplified in the above embodiment, and can be implemented as, for example, the following embodiment in which the embodiment is appropriately changed.

  In the first embodiment, the ventilation openings 80 arranged on the dashboard 12 are adopted as the specific elements in the vehicle interior reflected in the front window 10, but the present invention is not limited to this. In short, it is only necessary to be a specific element in the passenger compartment whose outline or the like is clear, and the effect of (4) above can be obtained even if, for example, a vehicle audio speaker or the like is employed in addition to the vent 80. .

  -In the said 2nd Embodiment, the illumination for illuminating the specific element in vehicle interiors, such as the said ventilation opening 80 currently arranged on the dashboard 12 in a vehicle interior, in the support part of the vehicle interior mirror 11 Although the light source 90 is provided to irradiate infrared light, the light emitted from the illumination source 90 is not limited to infrared light. In short, if the density of the virtual image of the specific element reflected on the front window 10 becomes clearer, the effect (5) can be obtained, and the type of irradiation light is arbitrary.

  In the third embodiment, the image information of the real image of the specific element image such as the vent 80 on the dashboard 12 in the passenger compartment is adopted as the reference image, but the specific element using the real image as the reference image Are not limited to the vent 80 and are optional. In addition, for example, a sticker or sticker 81 as shown in FIG. 8 may be attached to a dashboard or the like, and this real image may be used as a reference image and compared with the virtual image.

  In the first and second embodiments, image information of a virtual image captured in advance without rain is stored and held in the storage unit 30 as a basic pattern. The image information obtained empirically or estimated may be stored and held in the storage unit 30. Also by this, the effect (3) can be obtained.

  In each of the above embodiments, the actual pattern is acquired through the imaging device 20, but the present invention is not limited to this. The effect of the above (1) can also be obtained by adopting a line sensor instead of the imaging device 20 and acquiring an actual pattern through the line sensor.

  In each of the above embodiments, when the image information f (x, y) of the actual pattern, the image information g (x, y) of the basic pattern, and the image information h (x, y) of the difference image, The difference image is obtained using the equation (1). The acquisition of the difference image may be obtained according to the following equation (2) instead of the above equation (1). In short, it is only necessary to obtain a difference image between the actual pattern and the basic pattern, and the arithmetic expression to be followed can be appropriately changed depending on the definition of the image information.

h (x, y) = f (x, y) −g (x, y) (2)

In each of the above embodiments, as shown in FIG. 6, the threshold value is set in two stages with respect to the number of pixels (the number of pixels) S output from the image processing unit 40 or the image processing unit 40a. Was used to judge rainfall. However, as shown in steps S204 to S207 in FIG. 10 as processing corresponding to the processing in steps S104 to S111 in FIG. 6, a threshold value Sth for the number S of pixels output from the image processing unit 40 or the image processing unit 40a. It is good also as setting only one. That is, when it is determined that the pixel number S exceeds the threshold value Sth, it is determined as “rainfall that requires driving the wiper”, and when it is determined that the pixel number S is less than the threshold value Sth, “wiper driving” It may be determined whether or not there is rainfall so that it is determined that “no need”. In FIG. 10, the processes other than steps S204 to S207 are the same as the processes shown in FIG. 6 described above, and redundant description here is omitted.

  In the first and second embodiments, every time image information of a virtual image is imaged through the imaging device 20, a difference image from the basic pattern stored in the storage unit 30 is obtained as a real pattern, and The presence / absence of rainfall and the amount of rainfall are determined based on the number of pixels constituting the difference image. However, regarding the comparison between the real pattern and the basic pattern, it may be determined whether or not there is rainfall by a so-called pattern comparison technique every time virtual image information is captured through the imaging device 20. Further, the image information of the virtual image captured in advance without rain, the image information of the virtual image captured stepwise according to the amount of rainfall, or a plurality of image information according to them is stored in the storage unit 30 as a basic pattern. It is also possible to determine the presence / absence of rainfall and the amount of rainfall through pattern comparison with these basic patterns. As described above, the method for comparing the actual pattern and the basic pattern is not limited to the pattern comparison, and other methods may be used. In short, in this case, it suffices if the presence or absence of the difference between the basic pattern stored in the storage unit 30 and the actual pattern obtained through the imaging device 20 or the degree of difference can be acquired.

  In each of the above embodiments, only the comparison between the basic pattern or the reference image and the actual pattern is mentioned, but the present invention is not limited to this. In short, it is possible to detect the presence of rainfall and the amount of rainfall according to the above by tracking the transition of the actual pattern.

The side view which shows the outline | summary about 1st Embodiment of the rain sensor concerning this invention. The block diagram which shows the electrical connection aspect between each component, and the flow of a signal about the embodiment. The side view which shows typically the relationship between the imaging device employ | adopted in the embodiment, a front window, and the virtual image of a ventilation opening. In the embodiment, (a) is a figure which shows an example of the basic pattern memorize | stored and hold | maintained at a memory | storage part. (B) is a figure which shows an example of the real pattern imaged through an imaging device, when there is slight rainfall. (C) is a figure which shows an example of the difference image calculated | required based on (a) and (b). In the embodiment, (a) is a figure which shows an example of the basic pattern memorize | stored and hold | maintained at a memory | storage part. (B) is a figure which shows an example of the real pattern imaged through an imaging device, when there is much rainfall. (C) is a figure which shows an example of the difference image calculated | required based on (a) and (b). The flowchart which shows the process sequence of the detection process of rainfall including the drive control of a wiper about the embodiment. The front view which shows typically the structure about 2nd Embodiment of the rain sensor concerning this invention. The front view which shows typically the structure about 3rd Embodiment of the rain sensor concerning this invention. The block diagram which shows the electrical connection aspect between each component, and the flow of a signal about the 3rd Embodiment. The flowchart which shows the process sequence of the detection process about the presence or absence of the rain including the drive control of a wiper as a modification of each said embodiment. The side view which shows the outline | summary about an example of the conventional rain sensor. The block diagram which shows the electrical connection aspect between each component including the part which carries out drive control of the wiper, and the flow of a signal about an example of the conventional rain sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Front window, 11 ... Room mirror, 12 ... Dashboard, 20 ... Imaging device, 30 ... Memory | storage part, 40, 40a, 140 ... Image processing part, 50, 150 ... Judgment / control part, 60 ... Drive part (motor) ), 70 ... wiper, 80 ... vent, 81 ... seal or sticker, 90 ... illumination source, 180 ... emblem.

Claims (12)

A rain sensor that includes an imaging device that captures an image from a passenger compartment of a vehicle through a front window, and that detects the presence or absence of rainfall based on image information of an image captured through the imaging device,
A virtual image of a specific element image in the passenger compartment reflected in the front window is captured by the imaging device, and determination means is configured to determine whether there is rainfall based on a transition of image information of the captured virtual image. A rain sensor characterized by The determination means captures the presence or absence of rain based on the transition of the image information of the virtual image to be captured each time through the image information of the virtual image captured in advance without rain or the corresponding image information and the imaging device. The rain sensor according to claim 1, wherein the determination is made based on a comparison with image information of the same virtual image. The determination means includes storage means for storing and holding, as a basic pattern, image information of the virtual image captured in advance without rain or image information corresponding to the virtual image, and the image information of the virtual image is captured through the imaging device. The rain sensor according to claim 2, wherein the presence or absence of the rain is determined by comparing a pattern with a basic pattern stored and held in the storage unit as an actual pattern each time. The determination means includes image information of the virtual image captured in advance without the rain or image information corresponding thereto, and image information of the virtual image captured stepwise according to the amount of rainfall or an image corresponding thereto. A storage means for storing and holding a plurality of pieces of information as basic patterns is provided, and each time the virtual image image information is captured through the imaging device, this is compared with each basic pattern stored in the storage means as a real pattern. The rain sensor according to claim 2, wherein the presence / absence of rainfall and the amount of rainfall are determined together. The determination means includes storage means for storing and holding, as a basic pattern, image information of the virtual image captured in advance without rain or image information corresponding to the virtual image, and the image information of the virtual image is captured through the imaging device. 3. A difference image from the basic pattern stored in the storage means as an actual pattern is obtained each time, and the presence or absence of the rain is determined based on the number of pixels constituting the difference image. The rain sensor described. The determination means includes storage means for storing and holding, as a basic pattern, image information of the virtual image captured in advance without rain or image information corresponding to the virtual image, and the image information of the virtual image is captured through the imaging device. Each time, a difference image from the basic pattern stored in the storage means is obtained as an actual pattern, and the presence / absence of rainfall and the amount of rainfall are combined based on the number of pixels constituting the difference image. The rain sensor according to claim 2. The imaging device captures a real image of the image of the specific element in the vehicle interior, and the determination means includes image information of a real image of the image of the specific element in the vehicle interior that is imaged through the imaging device. The rain sensor according to claim 1, wherein the presence or absence of the rain is determined based on a comparison with image information of a virtual image of an image of a specific element in the vehicle interior that is captured each time through the imaging device. The determination means uses the real image information of the image of the specific element in the vehicle interior imaged through the imaging device as a reference image, and each time the virtual image image information is imaged through the imaging device as a real pattern. The rain sensor according to claim 7, wherein a difference image with respect to the reference image is obtained, and the presence or absence of the rain is determined based on the number of pixels constituting the difference image. The determination means uses the real image information of the image of the specific element in the vehicle interior imaged through the imaging device as a reference image, and each time the virtual image image information is imaged through the imaging device as a real pattern. The rain sensor according to claim 7, wherein a difference image with respect to the reference image is obtained, and the presence / absence of rainfall and the rainfall amount are determined based on the amount of pixels constituting the difference image. In the rain sensor according to any one of claims 1 to 9,
The rain sensor further comprising an illumination source for illuminating a specific element in the vehicle interior. The rain sensor according to any one of claims 1 to 10, wherein the specific element in the vehicle interior is an air vent arranged on a dashboard. A rain sensor that includes a line sensor that detects a line of an image from a passenger compartment of a vehicle through a front window, and that detects the presence or absence of rain based on image information of the line detected through the line sensor,
Judgment means for detecting a virtual image line of an image of a specific element in the vehicle interior reflected in the front window by the line sensor and determining the presence or absence of the rain based on a transition of image information of the detected virtual image line A rain sensor comprising:

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