JPH0682549U - Rain detector - Google Patents

Abstract

(57) [Abstract] [Purpose] The amount of light received by the light receiving means can be stabilized,
(EN) Provided is a rain detection device capable of detecting raindrops attached to a transparent body such as a windshield with high responsiveness without sensitivity adjustment and with high sensitivity. A second capacitor 9 which is connected to a first capacitor 7 through an inverting amplifier means 8 and which determines the voltage of the light emitting means 3 in accordance with the output of the first capacitor 7 which has been inverted and amplified, is also inverted and amplified. The comparison means 11 is provided for comparing the output of the first capacitor 7 and the output of the second capacitor 9 to generate a signal.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rain detection device for detecting rainfall by detecting the presence of raindrops, and for example, relates to a rain detection device mounted on an automobile and used for automatically operating a wiper during rainfall. Is.

[0002]

[Prior art]

 Conventionally, as an automatic wiper device using the rain detecting device as described above, there is one disclosed in, for example, Japanese Utility Model Laid-Open No. 63-69661.

That is, FIG. 4A shows a structure of a raindrop sensing section of the rain detection device described in the above publication, wherein the raindrop sensing section 100 shown in the figure is composed of an infrared light emitting diode 101 and a front side. The infrared light emitted from the infrared light emitting diode 101, which is composed of the glass 102 and the phototransistor 103, enters the windshield 102 and is reflected by the outer surface 102a of the front glass 102. The infrared light is received at the center of the phototransistor 103. The phototransistor 103 is arranged so as to output according to the amount of received light.

When the raindrop D adheres to the outer surface 102a of the windshield 102, the infrared rays that enter the front glass 102 are the infrared rays that enter the raindrop D at the boundary surface between the windshield 102 and the raindrop D. The infrared light reflected in the windshield 102 and the infrared light incident on the raindrop D are further separated on the outer surface of the raindrop D into infrared light incident on the air and infrared light reflected on the raindrop D. The infrared light reflected in the raindrop D is partially reflected by the boundary surface between the windshield 102 and the raindrop D and the inner surface 102b of the front glass 102 to reduce the amount of light, and is reflected in the air as shown by the broken line in the figure. Incident. At this time, the infrared light reflected in the windshield 102 at the boundary surface between the windshield 102 and the raindrops D has a smaller amount of light than before the raindrops D are attached due to the difference in density between the air and the raindrops D. The amount of infrared light received by the transistor 103 is reduced, and the deposition of the raindrop D reduces the output of the phototransistor 103.

As shown in FIG. 4B, the raindrop sensing unit 100 having such a configuration includes a CPU 114a, a ROM 114b, and a RAM 114c via a filter 110, an amplifier 111, a waveform shaping circuit 112, and an A / D converter 113. The output from the phototransistor 103 is connected to a one-chip microcomputer 114 that has a built-in device. When the output value from the transistor 103 becomes lower than the value obtained by subtracting the value set by the variable resistor (not shown) from the reference data value stored in the RAM 114c of the one-chip microcomputer 114, the one-chip microcomputer From the microcomputer 114 to the wiper device 11 A wiper drive signal is output to 5, and the wiper blade reciprocates once based on this signal.

[0006]

[Problems to be solved by the device]

 However, in the above-mentioned conventional automatic wiper device, as described above, the wiper blade is operated when the output from the phototransistor 103 becomes lower than the reference value immediately after wiping by the initial operation by the set value or more. Since the amount of infrared light emitted from the infrared light emitting diode 101 is always constant, when the vehicle is mounted on a vehicle, sensitivity adjustment according to different infrared transmittance and reflectance for each windshield 102 (initial (Setting) is required, and even if such an initial setting is performed, the amount of light received by the phototransistor 103 is not stable due to the condition of the windshield 102 such as dirt and scratches, and the detection sensitivity of raindrops varies. However, there was a problem in solving this kind of problem in this type of rain detection device.

[0007]

[The purpose of the device]

 The present invention has been made by paying attention to the above-mentioned problems in the conventional rain detection device, which can stabilize the amount of light received by the light receiving means, and can be applied to a transparent body such as front glass without any particular sensitivity adjustment. It is an object of the present invention to provide a rain detection device that can detect attached raindrops with high responsiveness and high sensitivity.

[0008]

[Means for Solving the Problems]

 The rain detection device according to the present invention comprises a light emitting means for emitting light (not limited to visible light), a transparent body for reflecting a part of the light from the light emitting means, and a light emitting means reflected by the transparent body. Light receiving means for receiving light of the above-mentioned type and outputting according to the amount of received light, a first capacitor connected to the light receiving means for averaging the output from the light receiving means, and connected to the first capacitor described above. Inversion amplification means for inverting and amplifying the output from the first capacitor, and the luminescence amplification power supply to the light emitting means connected to the first capacitor via the inverting and amplification means, and in accordance with the output of the first capacitor inverting and amplified. The second capacitor that determines the applied voltage is compared with the output of the first capacitor that has been inverted and amplified by the inverting amplification means and the output of the second capacitor, and a signal is output based on the comparison result. In a preferred embodiment, a connecting / disconnecting means for connecting / disconnecting the output of the second capacitor according to an oscillator is provided between the second capacitor and the light emitting power source. The feature is that the configuration is provided, and such a configuration of the rain detection device is used as a means for solving the above-mentioned conventional problems.

[0009]

[Function of the device]

 In the rain detecting apparatus according to the present invention, noise is removed by averaging the output from the light receiving means by the first capacitor connected to the light receiving means, and the first capacitor connected to the first capacitor via the inverting amplifying means. The second capacitor determines the voltage of the light emitting means according to the output from the first capacitor which has been inverted and amplified. That is, when the output from the light receiving means decreases, the voltage applied to the light emitting means is increased to increase the amount of light emitted by the light emitting means so that the output from the light receiving means is always constant, in other words, the light receiving means. The feedback control is performed so that the amount of received light is always constant, so the light transmittance and reflectance may be changed by changing the material of the transparent body that reflects the light from the light emitting means to the light receiving means or by contaminating it. Even if it changes, there is no change in the amount of light received by the light-receiving means, eliminating the need for sensitivity adjustment.

Since the output of the first capacitor that has been inverted and amplified and the output delayed by the second capacitor are compared by the comparison means, the change in the rate of change of the light quantity is detected. Raindrops adhering to the surface of the transparent body can be detected with high responsiveness and high sensitivity.

[0011]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a rain detecting device according to an embodiment of the present invention. In this embodiment, the rain detecting device is connected to a wiper device of an automobile to collect raindrops. This shows an example in which the wiper is automatically activated intermittently by detection.

A rain detecting device 1 shown in the figure receives an infrared light emitting diode 3 as a light emitting means and an infrared light from the light emitting diode 3 reflected by a windshield 4 used as a transparent body in this embodiment, The raindrop detecting section 2 having an infrared photodiode 5 as a light receiving means for performing an output according to the amount of received light, and an infrared photodiode 5 of the raindrop detecting section 2 are connected to output from the photodiode 5. It is connected to the amplifying circuit 6 that amplifies, the first capacitor 7 that is connected to the infrared photodiode 5 through the amplifying circuit 6 and that averages the amplified output from the photodiode 5, and the first capacitor 7. And an inverting amplification circuit 8 (inversion amplification means) for inverting and amplifying the output from the first capacitor 7, and the inverting amplification circuit 8 connected to the inverting amplification circuit 8 for inverting amplification. A second capacitor 9 that determines the voltage applied to the infrared light emitting diode 3 of the raindrop sensing unit 2 via the light emission power source 10 according to the output from the capacitor 7, and the first capacitor that is inverted and amplified by the inverting amplifier circuit 8. 7 and the output of the second capacitor 9 are compared, and when the output from the first capacitor 7 which is inverted and amplified is larger than the output from the second capacitor 9, the wiper device W is driven by the wiper. A comparison circuit 11 (comparison means) for outputting a signal is provided, and in this embodiment, an interruption circuit 12 (interruption means) is connected between the second capacitor 9 and the light emission power source 10. A pulse voltage is applied from the light emitting power source 10 to the infrared light emitting diode 3 by intermittently outputting the second capacitor 9 based on a pulse of a predetermined frequency from the oscillator 13. The light emitting diode 3 and so as to fast blink, have become earthenware pots by the light from the infrared light emitting diode 3 is distinguished from the ambient light such as sunlight by Re this Te.

As shown in FIG. 2, the raindrop sensing unit 2 is provided with an infrared light emitting diode 3 and an infrared photodiode 5 inside the vehicle compartment immediately below a windshield 4, and in this embodiment, A convex lens 3a is arranged between the light emitting diode 3 and the windshield 4 so that the infrared light from the infrared light emitting diode 3 is condensed.

As shown in FIG. 2, the infrared light emitting diode 3 and the infrared photodiode 5 emit infrared light emitted from the infrared light emitting diode 3 and reflected by the outer surface 4a of the windshield 4 while being converged by the convex lens 3a. It is arranged so that it enters the passenger compartment and is focused on the center of the infrared photodiode 5, and in this state where no raindrops are attached to the outer surface 4a of the front glass 4, the photodiode 5 The output is maximized.

The output from the infrared photodiode 5 is amplified by the amplifier circuit 6 shown in FIG. 1, averaged by the first capacitor 7, and then inverted and amplified by the inverting amplifier circuit 8 to obtain the inverting amplifier circuit 8. The output from is input to the comparison circuit 11 and the second capacitor 9 and is compared with the output from the delayed second capacitor 9 in the comparison circuit 11, but raindrops are formed on the outer surface 4a of the windshield 4. In the state in which is not attached, there is no change in the output from the photodiode 5 and there is no difference between the output value from the inverting amplifier circuit 8 and the output value from the second capacitor 9, so There is no signal output.

In this state, if the raindrop D adheres to the outer surface 4a of the windshield 4, as shown in FIG. 3, the amount of infrared rays incident on the raindrop D increases at the boundary surface between the windshield 4 and the raindrop D. At the boundary surface, the amount of infrared rays reflected by the windshield 4 and entering the passenger compartment is reduced, and the output from the infrared photodiode 5 is reduced. When the output from the infrared photodiode 5 decreases, the output from the first capacitor 7 decreases, and the output from the inverting amplifier circuit 8 that has inverted the output increases, so that the output value of the inverting amplifier circuit 8 is Since the output value from the delayed second capacitor 9 is larger than the delayed output value, the wiper drive signal is output from the comparison circuit 11, and the wiper device W is actuated based on this output signal to cause the wiper blade to make one round trip.

When the output of the second capacitor 9 increases, the voltage applied from the light emitting power source 10 to the infrared light emitting diode 3 increases, so that the amount of infrared light emitted from the light emitting diode 3 increases and the infrared photo diode The amount of light received by the diode 5 returns to the same level as before the deposition of the raindrop D. At this time, the output from the infrared photodiode 5 increases, and there is a difference between the output value from the inverting amplifier circuit 8 and the output value from the second capacitor 9, but the output value from the second capacitor 9 Since it becomes larger, the wiper drive signal is not output from the comparison circuit 11.

In this embodiment, the rain detection device is connected to the wiper device of the automobile, and the windshield of the automobile is used as a transparent body that receives raindrops and reflects light. It can also be placed on the roof or hood of a car by using a glass or acrylic plate that is separate from the. Further, the rain detection device can be used not only as an automatic wiper device for automobiles but also for automatically closing a skylight of a house or a greenhouse when it rains.

[0020]

As described above, the rain detecting apparatus according to the present invention is connected to the first capacitor through the above-mentioned configuration, particularly the inverting amplification means, and responds to the output of the inverting-amplified first capacitor. And a second capacitor for determining the voltage of the light emitting means, and comparing the output of the first capacitor, which has been inverted and increased, with the output of the second capacitor, and generating a signal based on the comparison result. Since the amount of light emitted by the light emitting means is controlled so that the amount of light received by the light receiving means is always constant, it is possible to change the material of the transparent body such as the windshield or the transparent body becomes dirty. However, there is no need to adjust the sensitivity, and since the change in the rate of change of the light quantity is detected by the first condenser and the second condenser, raindrops adhering to the surface of the transparent body have good responsiveness and high sensitivity. It has an excellent effect that it can be detected every time.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a rain detection apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic explanatory diagram showing a structure and an optical path of a raindrop sensing unit of the rain detection device shown in FIG.

FIG. 3 is a schematic explanatory diagram showing an optical path when raindrops adhere to the raindrop sensor shown in FIG.

FIG. 4 (a) is a schematic explanatory view showing a structure and an optical path of a raindrop sensor in a conventional rain detection device. (B) It is a block diagram which shows the structure of the conventional rain detection apparatus.

[Explanation of symbols]

 1 Rain Detection Device 3 Infrared Light Emitting Diode (Light Emitting Means) 4 Wind Glass (Transparent Body) 5 Infrared Photodiode (Light Receiving Means) 7 First Capacitor 8 Inversion Amplification Circuit (Inversion Amplification Means) 9 Second Capacitor 10 Light Emission Power Supply 11 Comparison Circuit (comparing means) 12 Intermittent circuit (intermitting means) 13 Oscillator

Claims (2)

[Scope of utility model registration request] 1. A light emitting means for emitting light, a transparent body for reflecting a part of the light from said light emitting means, and an output according to the amount of light received by receiving the light from said light emitting means reflected by said transparent body. A light receiving means for performing, a first capacitor connected to the light receiving means for averaging the output from the light receiving means, and an inverting amplification means connected to the first capacitor for inverting and amplifying the output from the first capacitor. Connected to the first capacitor through the inverting amplification means,
A second determining a voltage applied from the light emitting power source to the light emitting means according to the output of the first capacitor which has been inverted and amplified;
A rain characterized by comprising a capacitor and a comparing means for comparing the output of the first capacitor and the output of the second capacitor which are inverted and amplified by the inverting amplifying means and outputting a signal based on the comparison result. Detection device. 2. The rain detecting apparatus according to claim 1, further comprising an interrupting device provided between the second capacitor and the light emitting power source for interrupting an output of the second capacitor according to an oscillator.