JPH0339746Y2 - - Google Patents

Description

[Detailed description of the invention] [Summary] The present invention has a configuration in which the light that has passed through the detection area is transmitted to the light receiving element via an optical fiber, which makes the device smaller, the detection part simpler, and the noise resistance improved. This is intended to improve the quality of life.

[Industrial application field]

The present invention relates to an improvement of an on-vehicle raindrop detection device that optically detects raindrops.

[Conventional technology]

FIG. 5 is a configuration diagram of a conventional example, illustrating a vehicle-mounted raindrop detection device. In the same figure, 51
52 is a light receiving element such as a photodiode, 53 is a signal processing circuit, 54 is a housing, 55 is an output surface, 56 is an incident surface, 57 is a wiper controller, and 58 is a wiper operating device. This is a motor that allows Incidentally, the casing 54 is attached to, for example, a radiator grill, and its exit surface 55 and entrance surface 56 are both made of a transparent material.

The signal processing circuit 53 drives the light emitting element 51 and detects the presence or absence of raindrops based on the electrical signal from the light receiving element 52. That is, when raindrops pass between the output surface 55 and the entrance surface 56 (detection area), the light emitted from the light emitting element 51 is blocked by the raindrop, and the amount of light incident on the light receiving element 52 is reduced. It becomes possible to detect the presence or absence of raindrops based on the output signal of the element 52. When the signal processing circuit 53 detects raindrops, it applies a detection signal to the wiper controller 57, and upon receiving the detection signal, the wiper controller 57 starts the motor 58 to operate the wiper.

The conventional device shown in FIG. 5 detects raindrops as described above, but because the signal processing circuit 53 is housed in the housing 54, the following problems arise.

The casing 54 needs to be highly waterproof, which causes the problem that the device becomes expensive.

The casing 54 becomes large.

Susceptible to electrical noise.

[Problem that the invention attempts to solve]

The present invention solves the above-mentioned problems, and its purpose is to provide an on-vehicle raindrop detection device that has an economical structure and is less susceptible to electrical noise.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention includes a sensor housing having a detection area and mounted on the outside of the vehicle, a light emitting element and a light receiving element, at least one of which is provided inside the vehicle, and a light emitting element that emits light from the light emitting element. an optical fiber that emits light to the detection area or guides light that has passed through the detection area to the light receiving element, a lens provided at the light receiving end or the light emitting end of the optical fiber, and the light receiving element provided inside the vehicle interior. The device is characterized by comprising a signal processing circuit that detects the presence or absence of raindrops based on the output signal of the device.

[Effect]

Since the light that has passed through the detection area is made incident on the light receiving element via the optical fiber, it can be made less susceptible to electrical noise. Further, since only the optical element is provided in the sensor housing exposed to the outside of the vehicle, there is no need to make the housing highly waterproof, and therefore a compact device can be constructed economically. Furthermore, the lens provided at the light emitting end or the light receiving end of the optical fiber can reduce coupling loss and improve raindrop detection ability.

〔Example〕

FIG. 1 is a configuration diagram of an embodiment of the present invention, and 1
is a light emitting element such as a light emitting diode, 2, 4, and 9 are ball lenses, 3 and 8 are optical fibers, 5 is a housing, and 6
1 is an exit surface, 7 is an entrance surface, 10 is a light receiving element such as a photodiode, 11 is a signal processing circuit, 12 is a wiper controller, and 13 is a motor for operating the wiper. Incidentally, the housing 5 is attached to a radiator grill, etc., and its exit surface 6 and entrance surface 7
is made of transparent material. Further, the signal processing circuit 11 is placed in a part of the vehicle that is not easily affected by electrical noise.

FIG. 2 is a block diagram showing an example of the configuration of a signal processing circuit, in which 21 is an oscillation circuit, 22 is a drive circuit, 23 and 26 are bandpass filters, 24 is an amplifier, 25 is a detection circuit, and 27 is an integration circuit. circuit, 28
is a comparison circuit, and the same reference numerals as in FIG. 1 represent the same parts.

A pulse-modulated optical signal is emitted from the light emitting element 1 by the oscillation circuit 21, and this optical signal is sent to the light receiving element 1 along the path of ball lens 2 → optical fiber 3 → ball lens 4 → optical fiber 8 → ball lens 9.
0 and is converted into an electrical signal by the light receiving element 10. Here, when a raindrop passes between the output surface 6 and the input surface 7 (detection area), the light receiving element 1
The amount of light incident on the light receiving element 10 decreases, and the level of the electrical signal output from the light receiving element 10 decreases. The bandpass filter 23 extracts only the pulse-modulated frequency component from the output signal of the light receiving element 10,
The signal is applied to the detection circuit 25 via the amplifier 24. The detection circuit 25 performs envelope detection of the output signal of the amplifier 24, and as mentioned above, since the level of the output signal of the light receiving element 10 decreases when a raindrop passes, the output signal of the detection circuit 25 also detects the output signal when a raindrop passes. Sometimes the level will drop.

The bandpass filter 26 removes ripple components due to pulse modulation from the output signal of the detection circuit 25, and passes the signal through an inverting amplifier to apply a variation in the detection output to the integration circuit 27 as a raindrop pulse signal.
Since the integrating circuit 27 integrates this, its output signal increases each time the raindrop passes between the exit surface 6 and the entrance surface 7. The comparison circuit 28 compares the output of the integration circuit 27 with a predetermined threshold value, and sets the output signal to "H" when the output signal of the integration circuit 28 becomes larger than the threshold value. Thereby, the wiper controller 12 starts the motor 13 and operates the wiper.

In this way, in this embodiment, the signal processing circuit 11 is placed inside the vehicle, and only the optical element is housed in the housing 5, which is placed outside the vehicle. It is not necessary to make the casing expensive, so it is possible to use an inexpensive casing. The signal processing circuit 11 also exchanges signals with the detection section (casing 5) through optical fibers 3 and 8.
Since this is carried out using the ball lenses 2, 4, and 9, it is possible to be less susceptible to the influence of electrical noise compared to the conventional example. Furthermore, since only the optical elements are housed within the housing 5, the housing 5 can be made smaller compared to the conventional example. Further, in this embodiment, ball lenses 2 and 9 are provided between the light emitting element 1 and the optical fiber 3, and between the optical fiber 8 and the light receiving element 10, respectively.
, it is possible to reduce the coupling loss between them. Incidentally, the measured value of the coupling loss was approximately -6 dB. Further, in this embodiment, the light emitted from the optical fiber 3 is made to enter the optical fiber 8 via the ball lens 4, and the spread angle of the light beam during this time can be suppressed to 1 degree or less. Therefore, it is possible to reduce coupling loss compared to a directly opposed type having a spread angle of 7 degrees or more.

FIG. 3 is a configuration diagram of another embodiment of the present invention,
The difference from the embodiment shown in FIG.
This is because the light is made incident on the light receiving element 10 via the optical fiber 33. In this figure, the same reference numerals as in FIG. 1 represent the same parts.

FIG. 4 is a block diagram of another embodiment of the present invention, which differs from the embodiment shown in FIG. This is the point where the light emitting element 41 is electrically connected using a signal line. When the signal processing circuit 11 and the light emitting element 41 are connected using a signal line, the light emitting element 41 is more susceptible to electrical noise than the embodiments shown in FIGS. Since it generally has low impedance, it is sufficient for practical use.

In addition, in the above-mentioned embodiment, as a lens,
Although a ball lens is used, the type thereof is not limited to this.

[Effect of idea]

As explained above, the present invention has the advantage of being less susceptible to electrical noise than the conventional example. In addition, unlike the conventional example, the present invention does not house a signal processing circuit in the housing, so there is no need for the housing to be highly waterproof as in the conventional example. Another advantage is that the device can be constructed economically. Furthermore, since the lens is disposed at the light emitting end or the light receiving end of the optical fiber, coupling loss between the optical fibers or between the optical fiber and the light receiving/emitting element can be reduced.
Improves raindrop detection ability.

[Brief explanation of the drawing]

1, 3, and 4 are block diagrams of different embodiments of the present invention, FIG. 2 is a block diagram showing an example of the structure of a signal processing circuit, and FIG. 5 is a block diagram of a conventional example. . 1, 41, 51 are light emitting elements, 2, 4, 9, 3
2, 42 are ball lenses, 3, 8, 33 are optical fibers, 5, 54 are housings, 6, 55 are output surfaces, 7,
56 is an incident surface, 10, 52 is a light receiving element, 11, 5
3 is a signal processing circuit, 12, 57 is a wiper controller, 13, 58 is a motor that operates the wiper,
21 is an oscillation circuit, 22 is a drive circuit, 23 and 26 are band pass filters, 24 is an amplifier, 25 is a detection circuit, 27 is an integration circuit, and 28 is a comparison circuit.

Claims (1)

[Scope of Claim for Utility Model Registration] A sensor housing having a detection area and installed outside the vehicle; a light emitting element and a light receiving element, at least one of which is provided inside the vehicle; and a method for detecting the light emitted from the light emitting element. an optical fiber that guides light emitted to the area or passed through the detection area to the light receiving element; a lens provided at the light receiving end or the light emitting end of the optical fiber; and a lens provided in the vehicle interior based on the output signal of the light receiving element. A vehicle-mounted raindrop detection device comprising: a signal processing circuit for detecting the presence or absence of raindrops.