JP2004198214A - Raindrop and light detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a raindrop and light detecting device having a detecting function for horizontal light in addition to a detecting function for a raindrop and peripheral light. <P>SOLUTION: A lens 2, which guides light for detecting a raindrop to a light detecting means 7, and a lens 3, which guides light for detecting peripheral light to the light detecting means 7, are used as lenses having band-pass characteristics of a wavelength band centering around a first wavelength while a lens 4 for guiding light for detecting horizontal light to the light detecting means 7 is used as a lens having band-pass characteristics of a wavelength band centering around a second wavelength. The light detecting means 7 is set as a light detecting means for outputting intensity at every wavelength band corresponding to a plurality of wavelength bands transmitting through the lenses 2-4 in a 1 : 1 relation. By this constitution, even in such a case that the light for detecting the raindrop or the light for detecting the peripheral light and the light for detecting the horizontal light are detected at the same position by the light detecting means 7, they do not interfere with each other. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a raindrop and light detection device used for controlling wipers and lights of an automobile, and the like.
[0002]
[Prior art]
As basic equipment of a car, there are a wiper for wiping raindrops attached to the surface of a windshield and a light that lights up at night. The wiper adjusts the wiping speed and intermittent time according to the intensity of rain. The light is turned on when the area around the vehicle becomes dark. In order to perform these operations automatically, some windshields are provided with raindrops and light detectors for detecting raindrops and light on the inner surface of the windshield. As such an apparatus, there is an apparatus that includes a raindrop detecting unit that detects raindrops and a light detecting unit that detects light, and is integrally provided in a housing (see Patent Document 1).
[0003]
As another raindrop and light detection device, a light-emitting element and a light-receiving element are provided inside the windshield so as to face the windshield, and the raindrop is emitted from the light-emitting element and an interface between the windshield and the raindrop is provided. By receiving the light reflected by the light receiving element, the brightness around the device which can be regarded as the brightness around the vehicle is detected by receiving the light passing through the windshield and entering at a wide solid angle by the light receiving element. (See Patent Document 2). In this case, the light receiving element is shared for raindrop detection and light detection.
[0004]
In such an apparatus configuration in which the output of the light receiving element includes an output corresponding to the raindrop and an output corresponding to the surrounding brightness, it is necessary to enhance the distinction between the raindrop and the light. Therefore, the light emitting element is driven by a signal whose amplitude is modulated at a predetermined frequency, emits amplitude modulated light, and detects a detection signal from the light receiving element with a detector as a circuit for detecting raindrops. It detects raindrops (see Patent Document 3).
[0005]
[Patent Document 1]
German patent invention 19827044
[Patent Document 2]
JP-A-11-295214 [Patent Document 3]
JP-A-58-89430
[Problems to be solved by the invention]
By the way, according to the raindrop and light detection device, the headlights are turned on when the vehicle enters the tunnel, but even when passing not under the tunnel but under an elevated track or an elevated road, solar radiation is blocked. The headlight may be turned on temporarily. In this case, it is recognized that the occupant of the preceding vehicle has passed through the headlights from the following vehicle, which causes discomfort to the occupant of the preceding vehicle. Also, the headlights can usually be switched to a mode in which the optical axis is slightly upward, so that the visibility ahead can be improved at night, but this is dazzling for oncoming passengers, and there are some oncoming vehicles. For example, it is a manner to lower the optical axis. Therefore, in addition to the function of turning on / off the light according to the brightness of the surroundings of the device, horizontal light from the front of the vehicle is detected. It is determined that the vehicle has just passed under an elevated track or elevated road even if it has fallen, prohibiting the lighting of headlights, or determining the light indicating the certain level as headlight light from an oncoming vehicle. It is conceivable to add a function of lowering the optical axis.
[0007]
In this case, a light receiving element for detecting horizontal light incident on the device from the horizontal direction is provided. The newly provided light receiving element is provided for raindrops and light that changes according to the brightness of the surrounding area. The light receiving elements must be arranged apart from each other so as not to be insensitive. For this reason, the addition of the horizontal light detection function increases the size of the raindrop and light detection device, and may be conspicuous in the mounted state.
[0008]
The present invention has been made in view of the above circumstances, and has as its object to provide a small raindrop and light detection device having a function of detecting light from a predetermined direction such as horizontal light.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a light receiving means for detecting light, wherein the first light emitted from the light emitting means and reflected by the windshield and incident thereon, the second light incident at a wide solid angle, Light receiving means for receiving third light incident from the direction; detecting raindrops from the first light; detecting brightness around the device from the second light; and detecting light in a predetermined direction from the third light. Raindrop and light detection device for detecting the brightness of
A conversion means for converting the first, second and third lights into light of a predetermined wavelength band before entering the light receiving means is provided, and at least the wavelength band of the second light and the third Unlike the wavelength band of light,
The light receiving means is constituted by a light receiving means for outputting the intensity for each wavelength band in one-to-one correspondence with the wavelength bands of the plurality of lights converted by the conversion means.
[0010]
The first, second and third lights are converted into light of a predetermined wavelength band before entering the light receiving means, and the wavelength band of the second light is different from the wavelength band of the third light. The output of the second light wavelength band is an output corresponding to the brightness of the surroundings under the influence of the brightness in a predetermined direction, for example, the horizontal direction, and the output of the third light wavelength band. Is an output corresponding to the brightness in a predetermined direction under the influence of the surrounding brightness. Therefore, even if the light receiving means receives the first to third lights at, for example, the same position, the brightness in the predetermined direction and the brightness in the surroundings can be distinguished. Thereby, the device can be downsized.
[0011]
According to a second aspect of the present invention, in the configuration of the first aspect of the present invention, the conversion means is constituted by an optical filter having a band-pass filter characteristic.
[0012]
The optical filter can be realized by mixing a pigment with an optical member such as an interference film filter or a lens that guides light to the light receiving unit, so that conversion to light in a predetermined wavelength band is easy.
[0013]
According to a third aspect of the present invention, in the configuration of the first or second aspect, the light receiving means is constituted by a sensor formed into one chip.
[0014]
As described above, the light receiving means may receive the first to third lights at the same position. Therefore, the use of a one-chip sensor as the light receiving means can further reduce the size of the device. .
[0015]
According to a fourth aspect of the present invention, in the configuration according to the third aspect of the present invention, a first lens serving as a guide path for guiding the first light from the light emitting unit to the light receiving unit via the windshield is provided, A second lens serving as a guide path for guiding the second light to the light receiving means, and a third lens serving as a guide path for guiding the third light to the light receiving means;
The second lens and the third lens are disposed so as to sandwich the first lens in a direction orthogonal to a direction connecting a light incident surface and a light exit surface of the first lens.
[0016]
The first lens is likely to be longer in the guiding direction, that is, in the direction from the entrance surface to the exit surface. Therefore, by disposing the second lens and the third lens as described above, the first lens tends to be longer. The device can be further miniaturized in the direction from the entrance surface to the exit surface.
[0017]
In the fifth aspect of the present invention, in the configuration of the first to fourth aspects, the wavelength band is set such that either the second light or the third light is the same as the first light. I do.
[0018]
The first light is light from the light emitting means, and by modulating the drive signal thereto, even if the wavelength band is the same, the first light can be distinguished from the second light or the third light. Therefore, by making either the second light or the third light have the same wavelength band as the first light, the light receiving unit outputs the intensity for each wavelength band for the two wavelength bands. That is all you need to do. Thus, the light receiving means can be simplified, and the size of the device can be further reduced.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
1, 2 and 3 show the configuration of a raindrop and light detection device to which the present invention is applied. The raindrop and light detection device is mounted on the inner surface of the windshield W within a fan-shaped area where the wiper of the automobile wipes the raindrop and at a position that is not conspicuous such as behind a rearview mirror. The attachment is performed via a light-transmitting tape 8 described later, a bracket (not shown), or the like. The housing 1 of the raindrop and light detection device S has a shape in which the windshield W side is open, and the lenses 2, 3, and 4 and the printed circuit board 5 are inside the housing 1, and the lenses 2 to 4 have the windshield W side. And is fixed to the housing 1.
[0020]
Three types of lenses 2 to 4 having different shapes are provided (hereinafter, the first lens 2 is referred to as a raindrop detecting lens 2, the second lens 2 is referred to as an ambient light detecting lens 2, and The lens 3 is referred to as a horizontal light detecting lens 3). The raindrop detecting lens 1 is in the form of an elongated block, and is disposed so that its longitudinal direction is in the left-right direction of the vehicle when attached to the windshield W, and the elongated bottom surface 2a sandwiches the light transmitting tape 8 and the windshield. It faces the inner surface 2b of W. Both end surfaces 2b and 2c in the longitudinal direction of the raindrop detecting lens 2 form an acute angle with the bottom surface 2a. The end surfaces 2b and 2c are smooth convex surfaces, respectively. A lens portion 21 having a light condensing function is formed by the end surface 2b which is an incident surface, and a lens portion having a light condensing effect is formed by the end surface 2c which is an emission surface. 22 are formed.
[0021]
A light-transmitting tape 8 having a shape substantially covering the opening of the housing 1 is inserted between the raindrop detecting lens bottom surface 2a and the windshield inner side surface Wb. As the light transmissive tape 8, an adhesive layer formed on both surfaces of a silicon sheet or an acrylic plate is used. The adhesiveness with the raindrop detecting lens 2 and the windshield W is ensured, and unnecessary light reflection is reduced. . The transmittance of the light transmitting tape 8 is the sensitivity required for raindrop and light detection for light in a wavelength band centered on a first wavelength (λ1) and a wavelength band centered on a second wavelength (λ2) described later. , But basically the same one inserted in the conventional device between the lens and the windshield can be used.
[0022]
The peripheral light detecting lens 3 is a flat plate member positioned substantially parallel to the windshield W, has no light condensing action, and allows light to enter a photodiode 7 described later at a wide solid angle. Alternatively, a lens having a slight light collecting action may be used.
[0023]
The horizontal light detection lens 4 is a block-shaped member smaller than the raindrop detection lens 2. It has a substantially triangular shape having two inclined surfaces connected to the bottom surface 4a. One inclined surface 4b is a smooth convex surface, and the inclined surface 4b forms a lens portion 41 having a light condensing function. The horizontal light detecting lens 4 is disposed such that the bottom surface 4a thereof faces the windshield inner side surface Wb with the light transmitting tape 8 interposed therebetween.
[0024]
On the printed circuit board 5, a light emitting diode (hereinafter, appropriately referred to as LED) 6 as a light emitting means and a photodiode (hereinafter, appropriately referred to as PD) 7 as a light receiving means are mounted on a plate surface facing the lenses 2 to 4. At the same time, a circuit for driving the LED 6 and a circuit for processing the output signal of the PD 7 are formed.
[0025]
The LED 6 is disposed at the front position of one lens unit 21 of the raindrop detecting lens 2, that is, on the main optical axis of the lens unit 21, and the PD 7 is disposed at the front position of the other lens unit 22, that is, on the main optical axis of the lens unit 22. Placed in The light emitted from the LED 6 is guided in a direction from the end surface 2b, which is the incident surface of the raindrop detecting lens 2, to the end surface 2c, which is the emitting surface, that is, substantially in the longitudinal direction of the raindrop detecting lens 2, and emitted from the end surface 2c. I do. Here, the light from the LED 6 is reflected by the outer surface Wa of the windshield W via the one lens portion 21, is condensed by the other lens portion 22, and is incident on the PD 7. The length of the lens 2 and the inclination angles of the end faces 2b and 2c are set.
[0026]
The positional relationship between the ambient light detecting lens 3, the horizontal light detecting lens 4, and the raindrop detecting lens 2 will be described. As is known from FIG. 3, the peripheral light detecting lens 3 and the horizontal light detecting lens 4 are positioned close to the other lens portion 22 of the raindrop detecting lens 2, that is, close to the PD 7. The raindrop detecting lens 2 is disposed in a direction connecting the end faces 2b and 2c, that is, a direction orthogonal to the longitudinal direction of the raindrop detecting lens 2. Further, the inclination angle of the inclined surface 4b and the raindrop detection lens of the horizontal light detection lens 4 so that the PD 7 is located in front of the lens unit 41 of the horizontal light detection lens 4, that is, on the main optical axis of the lens unit 41. 2 is set in the longitudinal direction, and the light transmitted through the windshield W and incident on the horizontal light detection lens 4 is focused on the PD 7.
[0027]
The position of the raindrop detecting lens 2 in the orthogonal direction together with the inclination angle of the inclined surface 4b of the horizontal light detecting lens 4 is determined by the main optical axis of the lens portion 41 when the raindrop and light detecting device S is mounted on the windshield. Are set to be substantially horizontal.
[0028]
Due to the arrangement of the lenses 2 to 4 and the like, the PD 7 has the first light from the raindrop detecting lens 2, the second light from the ambient light detecting lens 3, and the third light from the horizontal light detecting lens 4. Will all be incident. The second light is incident at a wide solid angle and indicates the brightness around the device (ambient light), and the third light is incident in the horizontal direction and has a predetermined brightness in the horizontal direction. (Horizontal light).
[0029]
Each of the lenses 2 to 4 has bandpass filter characteristics. FIGS. 4A and 4B show the spectral characteristics of the lenses 2 to 4. As shown in FIG. 4A, the raindrop detecting lens 2 and the ambient light detecting lens 3 are the first lens. It has band-pass filter characteristics in a predetermined range of wavelength band centered on the wavelength (λ1). Further, as shown in FIG. 4B, the horizontal light detecting lens 4 has a band-pass filter characteristic in a predetermined range of wavelength band centered on the second wavelength (λ2). Here, the first wavelength (λ1) can be 660 nm (red), and the second wavelength (λ2) can be 460 nm (blue), for example. Such bandpass filter characteristics can be easily obtained by using a resin material mixed with a blue or red pigment as a lens material. Alternatively, it can be obtained by coating the surface of the lens unit with an interference film.
[0030]
Further, as the PD 7, a sensor in which a plurality of PD units such as a color sensor are integrated into one chip is used. FIG. 5 shows the spectral characteristics of the PD 7. The PD section includes one having the first wavelength (λ1) as the maximum sensitivity wavelength and one having the second wavelength (λ2) as the maximum sensitivity wavelength. At first, the first PD section outputs the intensity of light in a wavelength band having the first wavelength (λ1) as the center wavelength, and the second PD section has the second wavelength (λ2) as the center wavelength. Outputs the intensity of light in the wavelength band.
[0031]
The detection circuit formed on the printed circuit board 5 includes a drive circuit for the LED 6 and a signal processing circuit for an output signal of the PD 7. The signal processing circuit is configured to receive an output signal of each PD unit as an input. The amount of raindrops and the intensity of ambient light can be obtained based on the output signal of the PD unit having the wavelength (λ1) as the maximum sensitivity wavelength. In addition, the intensity of horizontal light can be obtained based on the output signal of the PD unit having the second wavelength (λ2) as the maximum sensitivity wavelength. The signal component based on the amount of raindrops and the signal component based on ambient light are separated from each other by using a modulation circuit that modulates the amplitude of the drive signal at a predetermined frequency in a drive circuit of the LED 6 as described in Patent Document 3 and the like. By providing an output signal detection circuit in the signal processing circuit for the output signal of the PD 7, it is possible to distinguish between a change in light emitted from the LED 6 and passing through the raindrop detection lens 2 and a change in ambient light. .
[0032]
The operation of the raindrop and light detection device S will be described. The raindrops adhere to the windshield W and reflectivity at the boundary between the windshield W and the raindrops changes. The intensity of light of the first wavelength (λ1) from the LED 6 through the raindrop detection lens 2 and incident on the PD 7. Changes. When the brightness of the surroundings changes, the intensity of the surrounding light of the first wavelength (λ1) which enters the PD through the surrounding light detecting lens 3 changes.
[0033]
Since the raindrop detecting lens 2 and the ambient light detecting lens 3 have a band-pass filter characteristic with the first wavelength (λ1) as the center wavelength, the light from the raindrop detecting lens 2 has the first wavelength. The PD section having (λ1) as the maximum sensitivity wavelength is strongly sensitive, and the PD section having the second wavelength as the maximum sensitivity wavelength is almost insensitive. Therefore, even if the PD section having the first wavelength (λ1) as the maximum sensitivity wavelength and the PD section having the second wavelength (λ2) as the maximum sensitivity wavelength are substantially at the same position, the second wavelength ( The light from the LED 6 does not affect the PD section having the maximum sensitivity wavelength of .lambda.2).
[0034]
On the other hand, when the brightness in the horizontal direction changes, the intensity of the horizontal light of the second wavelength (λ2) passing through the horizontal light detecting lens 4 and input to the PD 7 changes. Since the horizontal light detecting lens 4 has a bandpass filter characteristic at the second wavelength (λ2), the light from the horizontal light detecting lens 4 has the second wavelength (λ2) as the maximum sensitivity wavelength. The PD section is strongly sensitive, and the PD section having the first wavelength (λ1) as the maximum sensitivity wavelength is almost insensitive. Therefore, even if the PD section having the second wavelength (λ2) as the maximum sensitivity wavelength and the PD section having the first wavelength (λ1) as the maximum sensitivity wavelength are at substantially the same position, the first wavelength ( Horizontal light does not affect the PD section having the maximum sensitivity wavelength of λ1).
[0035]
As described above, according to the present raindrop and light detecting device S, even if the function of detecting horizontal light is added, the light receiving means for receiving light for detecting raindrops and ambient light, and the light receiving means for receiving light for detecting horizontal light are provided. The means and the means can be arranged at substantially the same position, and the size of the device can be reduced. Note that it is preferable that the gap between the lenses is sufficiently light-blocked so that unnecessary light that does not pass through the lenses does not enter each PD unit. For example, a black film is provided over the light-transmitting tape so as to cover a portion not facing the lens.
[0036]
In addition, since the peripheral light detecting lens 3 and the horizontal light detecting lens 4 are disposed so as to sandwich the raindrop detecting lens 2 in a direction perpendicular to the longitudinal direction of the raindrop detecting lens 2, the raindrop detecting lens is provided. 2, the device can be further miniaturized in the longitudinal direction.
[0037]
In the present embodiment, the bandpass filter characteristic of the raindrop detecting lens 2 is the same as the bandpass filter characteristic of the ambient light detecting lens 3, but the same as the bandpass filter characteristic of the horizontal light detecting lens. You may. In this case, the light transmitted through the raindrop detecting lens 2 and the horizontal light detecting lens have sensitivity in the common PD section. In addition, the band-pass filter characteristics of the lenses for raindrop detection, ambient light detection, and horizontal light detection may have different center wavelengths among all the lenses. For example, the band-pass filter characteristic has a center wavelength of 460 nm (red), the band-pass filter characteristic of 540 nm (green), and the band-pass filter characteristic of 660 nm (blue). In this case, the PD has a configuration in which the PD section has three PD sections having a maximum sensitivity wavelength of 460 nm, 540 nm, and 660 nm.
[0038]
Further, the PD 7 has a configuration in which a plurality of PD units are integrated into one chip. However, the present invention is not limited to this, and a plurality of PDs having a single signal output may be arranged close to each other on a printed circuit board. Of course.
[0039]
Each of the first, second and third lights is constituted by a lens having an optical filter function as a converting means for converting the first, second and third lights into light of a predetermined wavelength band before entering the light receiving means, but is not necessarily limited thereto. Not something.
[Brief description of the drawings]
FIG. 1 is a sectional view of a raindrop and light detection device of the present invention.
FIG. 2 is a sectional view taken along line II-II in FIG.
FIG. 3 is a sectional view taken along line III-III in FIG. 2;
4A is a graph showing spectral characteristics of a raindrop detecting lens and a peripheral light detecting lens, and FIG. 4B is a graph showing spectral characteristics of a horizontal light detecting lens.
FIG. 5 is a graph showing spectral characteristics of the photodiode.
[Explanation of symbols]
S Raindrop and light detection device 1 Housing 2 Raindrop detection lens (first lens)
2b End surface (incident surface)
2c End face (outgoing face)
3. Ambient light detection lens (second lens)
4 Horizontal light detection lens (third lens)
5 Printed circuit board 6 LED (light emitting means)
7 PD (light receiving means)
8 Light transmissive tape W Windshield Wa Outside surface Wb Inside surface

Claims (5)

A light receiving means for detecting light, wherein the first light is emitted from the light emitting means and reflected by the windshield to be incident, the second light is incident at a wide solid angle, and the third light is incident from a predetermined direction. A raindrop detecting means for detecting raindrops from the first light, detecting brightness around the device from the second light, and detecting brightness in a predetermined direction from the third light; In the photodetector,
A conversion means for converting the first, second and third lights into light of a predetermined wavelength band before entering the light receiving means is provided, and at least the wavelength band of the second light and the third Unlike the wavelength band of light,
Wherein said light receiving means comprises light receiving means for outputting the intensity for each wavelength band in one-to-one correspondence with a plurality of wavelength bands of light converted by said converting means. apparatus. 2. The raindrop and light detection device according to claim 1, wherein said conversion means is constituted by an optical filter having bandpass filter characteristics. 3. The raindrop and light detecting device according to claim 1, wherein said light receiving means is constituted by a sensor integrated into one chip. 4. The raindrop and light detection device according to claim 3, wherein a first lens serving as a guide path for guiding the first light from the light emitting means to the light receiving means via the windshield is provided, and the second light is provided. A second lens serving as a guide path for guiding the light receiving means, and a third lens serving as a guide path for guiding the third light to the light receiving means;
Raindrops and light, wherein the second lens and the third lens are disposed with the first lens interposed therebetween in a direction orthogonal to a direction connecting a light incident surface and a light exit surface of the first lens. Detection device. The raindrop and light detection device according to any one of claims 1 to 4, wherein the wavelength band is such that either the second light or the third light is the same as the first light.

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