JP2008275390A - Raindrop detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a raindrop detection device capable of suppressing wrong determination as raindrop adhesion, of a measuring light course distortion element existing on an optical path from a light emitting element to a light receiving element via a windshield. <P>SOLUTION: This device is equipped with the light emitting element for emitting measuring light, the first light receiving element for receiving the measuring light reflected by the windshield, the second light receiving element for receiving the measuring light introduced along an optical path bypassing the windshield, and a raindrop amount determination means for determining the raindrop amount based on the light receiving amount by the first light receiving element. When the light receiving amount by the second light receiving element is less than a prescribed value, raindrop amount determination by the raindrop amount determination means is suspended. Hereby, the device can suppress wrong determination as raindrop adhesion, of the measuring light course distortion element existing on the measuring light route from the light emitting element in the raindrop detection device to the first light receiving element via the windshield. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a raindrop detection device that detects raindrops and the like attached to a windshield of an automobile.

Conventionally, as a raindrop detection apparatus, a device that reflects light from a light emitting element by a windshield and guides the light to a light receiving element and detects the amount of light received by the light receiving element is known (see Patent Document 1). In such a raindrop detection device, attention is paid to the fact that the amount of light received by the light receiving element changes according to the state of attachment of the raindrop to the windshield, and attachment of raindrops is determined from the result of detection of the amount of light received by the light receiving element. In other words, when no raindrops are attached to the windshield, the amount of light received by the light receiving element is maximized. When raindrops are attached to the windshield, part of the light from the light emitting element is emitted outside the windshield through the raindrops. The amount of light received by the light receiving element is reduced. The adhesion of raindrops is determined based on the change in the amount of light received by the light receiving element.
JP 2006-112814 A

  By the way, in the raindrop detection apparatus described in Patent Document 1, if there are measurement light path distortion elements such as moisture and smoke on the optical path from the light emitting element through the windshield to the light receiving element, light is emitted by these measurement light path distortion elements. The light from the element is diffusely reflected or refracted, and the amount of light received by the light receiving element is reduced. Here, the measurement light path distorting element is specifically water vapor, frost or water droplets on which the water vapor condenses and adheres to the indoor surface of the windshield, cigarette smoke, or the like. For example, when the engine is started and the air conditioner is operated in the heating mode when the windshield is cold in winter, moisture in the air condenses and adheres to the surface of each part in the raindrop detector. Further, when the air conditioner is operated in the cooling mode when the temperature of the windshield is high in summer, moisture in the air condenses and adheres to the surface of each part in the raindrop detector. In addition, when a passenger smokes, the smoke may enter the raindrop detection device. In the conventional raindrop detection apparatus, there is a possibility that a change in the amount of received light due to the presence of these measurement light path distortion elements is erroneously determined as raindrop adhesion.

  The present invention has been made in view of the above-described problems, and its purpose is that when a measurement light path distortion element exists on the optical path from the light emitting element to the light receiving element through the windshield, it is regarded as raindrop adhesion. It is providing the raindrop detection apparatus which can suppress making a misjudgment.

  In order to achieve the above object, the present invention employs the following technical means.

  A raindrop detection apparatus according to claim 1 of the present invention is a raindrop detection apparatus that detects raindrops adhering to a windshield, and is a first that receives a light emitting element that emits measurement light and measurement light reflected by the windshield. A second light receiving element comprising: a light receiving element; a second light receiving element that receives measurement light guided by an optical path that does not pass through the windshield; and a raindrop amount determination unit that determines a raindrop amount based on the amount of light received by the first light receiving element. When the amount of light received by the element is smaller than a predetermined value, the raindrop amount determination by the raindrop amount determination means is stopped.

  In the above-described configuration, the amount of light received by the first light receiving element is reduced by raindrop adhesion on the windshield. On the other hand, the amount of light received by the second light receiving element is not affected at all even if raindrops adhere to the windshield because there is no windshield in the optical path from the light emitting element to the second light receiving element.

  In addition, if there is something in the raindrop detection device that acts to change the course of the ongoing measurement light, for example, water vapor, water droplets, smoke, etc., the course of the measurement light changes due to these. However, the amount of light received by the first light receiving element and the amount of light received by the second light receiving element are reduced.

  Accordingly, the amount of light received by the first light receiving element is reduced due to both the factors of raindrops adhering to the windshield and the presence of various measurement light path distortion elements described above, whereas the amount of light received by the second light receiving element is detected by raindrop detection. It is reduced only by the presence of various measuring light path distortion elements in the device. For this reason, since the amount of light received by the second light receiving element has decreased, there is an element in the raindrop detection device that acts to change the course of the measurement light in progress, in other words, the first light receiving element. It can be detected that the raindrop amount determination accuracy by the raindrop amount determination means based on the received light amount is in a state of being lowered. By suspending the raindrop amount determination by the raindrop amount determination means based on the detection result, the measurement light path distortion existing on the measurement light path from the light emitting element in the raindrop detecting device to the first light receiving element through the windshield. It is possible to suppress erroneous determination of an element as raindrop adhesion.

  By the way, the second light receiving element does not directly detect a measurement light path distortion element existing in the measurement light path from the light emitting element to the first light receiving element. However, in general, the first light receiving element and the second light receiving element are arranged close to each other in the raindrop detection apparatus. Furthermore, water vapor, water droplets, smoke, etc., which are the measurement light path distortion elements, are present uniformly throughout the raindrop detection device, or if they enter the raindrop detection device from the outside, they are quickly distributed throughout the raindrop detection device. To do. Therefore, when the amount of light received by the second light receiving element decreases, water vapor, water droplets, smoke, etc., which are measurement light path distortion elements, are also present in the middle of the path from the light emitting element through the windshield to the first light receiving element. Naturally exists.

  The raindrop detection apparatus according to claim 2 of the present invention is a raindrop detection apparatus that detects raindrops adhering to a windshield, and is a first that receives a light emitting element that emits measurement light and measurement light reflected by the windshield. A light receiving element, a second light receiving element that receives the measurement light guided by an optical path that does not pass through the windshield, and a raindrop amount that determines a raindrop amount based on a light receiving amount of the first light receiving element and a light receiving amount of the second light receiving element And a determination unit, and when the amount of light received by the second light receiving element is smaller than a predetermined value, the raindrop amount determination by the raindrop amount determination unit is stopped.

  In this configuration, in the raindrop detection apparatus according to claim 1 of the present invention described above, the second light receiving element is added to the light receiving amount of the first light receiving element in the raindrop amount determination executed by the raindrop amount determining means. The difference is that the amount of received light is used. That is, the amount of light received by the first light receiving element whose size changes in accordance with the state of raindrops adhering to the windshield and the amount of light received by the second light receiving element that is always constant regardless of whether the raindrops adhere to the windshield. The raindrop amount is judged with reference to both. In this case, even if the light emission characteristic of the light emitting element changes, the influence thereof simultaneously affects both the amount of light received by the first light receiving element and the amount of received light by the second light receiving element. It can suppress being influenced. As a result, it is possible to suppress erroneous determination of the measurement light path distortion element existing on the measurement light path from the light emitting element in the raindrop detection device through the windshield to the first light receiving element as raindrop adhesion. At the same time as the effect is obtained, the raindrop amount detection accuracy can be increased.

  According to a third aspect of the present invention, the raindrop detection apparatus includes a reflective surface disposed on the measurement light emitting side of the light emitting element so as to face the light emitting element, and the measurement light is reflected by the reflective surface and directly reflected by the second light receiving element. It is characterized by being incident on.

  With such a configuration, the presence of the measurement light path distortion element in the space between the light emitting element and the reflecting surface and between the reflecting surface and the second light receiving element is detected based on the amount of light received by the light receiving element. The detection accuracy of the measurement light path distortion element by the second light receiving element can be widened to increase the detection accuracy.

  According to a fourth aspect of the present invention, in the raindrop detection device according to the present invention, during the period when the raindrop amount determination by the raindrop amount determination unit is stopped, the determination result by the raindrop amount determination unit immediately before the raindrop amount determination is stopped is the raindrop amount determination. It is characterized by being maintained as a result.

  According to the above configuration, when the raindrop amount determination result by the raindrop detection device is applied to another control, the raindrop amount detection is performed even during the period when the raindrop amount determination of the raindrop amount determination unit is stopped by the control unit. Since the result is output, inconveniences such as interruption of another control to which the raindrop amount determination result by the raindrop detection apparatus is applied can be prevented.

  According to a fifth aspect of the present invention, there is provided a raindrop detecting device comprising a temperature raising means for raising the temperature of air forming the path of the measuring light, and when the amount of light received by the second light receiving element is smaller than a predetermined value, the temperature raising means. To increase the temperature of the air forming the path of the measurement light.

  According to such a configuration, by operating the temperature raising means, the air temperature in the raindrop detection device is raised to lower the relative humidity, and water vapor and condensed water are removed, that is, the light path distortion element is removed. be able to. Therefore, it is possible to remove the optical path distortion element from the raindrop detection device in a short time and restart the raindrop amount determination by the raindrop amount determination means.

  In this case, as in the raindrop detection device according to claim 6 of the present invention, the temperature raising means is operated for a predetermined time from when the amount of light received by the second light receiving element is less than the predetermined value. Thus, it is possible to remove foreign matter from the raindrop detection device and restart the raindrop amount determination by the raindrop amount determination means.

  The raindrop detection apparatus according to claim 7 of the present invention is a raindrop detection apparatus that detects raindrops adhering to the windshield, and includes a first light emitting element that emits first light and a second light emitting element that emits second light. And a light receiving element arranged to be able to receive the first light and the second light, and a raindrop amount determining means for determining a raindrop amount based on the amount of the first light received by the light receiving element, wherein the first light is a windshield. The second light is received by the light receiving element along the optical path not passing through the windshield, and the second light emitting element is turned off and the second light emitting element is turned on when the first light emitting element is turned on. Sometimes, the first light emitting element is turned off, and when the amount of the second light received by the light receiving element is smaller than a predetermined value, the raindrop amount determination by the raindrop amount determination means is stopped.

  In the above-described configuration, the amount of the first light received by the light receiving element is reduced by raindrop adhesion on the windshield. On the other hand, the amount of the second light received by the light receiving element is not affected at all even if raindrops adhere to the windshield because there is no windshield in the middle of the optical path from the light emitting element to the second light receiving element. Absent.

  Also, if there are light path distortion elements, such as water vapor, water drops, smoke, etc., that act to change the path for each ongoing light in the raindrop detection device, The path of each light changes, and the amount of received light of the first light and the amount of received light of the second light in the light receiving element decreases.

  Therefore, the amount of the first light received by the light receiving element decreases due to the influences of both the raindrop adhering to the windshield and the presence of the various optical path distortion elements described above, whereas The amount of light received by two lights is reduced only by the presence of various light path distortion elements in the raindrop detection device. For this reason, since the light receiving amount of the second light in the light receiving element is reduced, there is an element in the raindrop detection device that acts to change the course of each ongoing light, in other words, the light receiving element. It can be detected that the raindrop amount determination accuracy by the raindrop amount determination means based on the received light amount of the first light is reduced. By canceling the raindrop amount determination by the raindrop amount determination means based on the detection result, the light path distortion element existing on the measurement light path from the light emitting element in the raindrop detecting device through the windshield to the first light receiving element. Can be prevented from being erroneously determined as raindrop adhesion.

  Here, the light receiving element is arranged so as to be able to receive both the first light emitted from the first light emitting element and the second light emitted from the second light emitting element. However, according to the above-described configuration, the second light emitting element is turned off when the first light emitting element is turned on, and the first light emitting element is turned off when the second light emitting element is turned on. Only one of the lights is received. As a result, it is possible to prevent the first light and the second light from entering the light receiving element at the same time. Therefore, when there is an optical path distortion element on the optical path from the light emitting element to the light receiving element through the windshield, It can be detected reliably.

  By the way, the optical path from the first light emitting element to the light receiving element is different from the optical path from the second light emitting element to the light receiving element. However, in general, the first light emitting element and the second light emitting element are arranged close to each other in the raindrop detection apparatus. Furthermore, water vapor, water droplets, smoke, etc., which are light path distortion elements, are uniformly present throughout the raindrop detection device, or if they enter the raindrop detection device from the outside, they are quickly distributed throughout the raindrop detection device. . Therefore, the environmental conditions of the optical path from the first light emitting element to the light receiving element and the optical path from the second light emitting element to the light receiving element, that is, the existence conditions of water vapor, water droplets, smoke and the like that are optical path distortion elements are the same. It can be assumed that there is. Therefore, it is possible to determine the presence of a light path distortion element in the optical path from the first light emitting element to the light receiving element based on the amount of the second light received by the light receiving element.

  The raindrop detection apparatus according to claim 8 of the present invention is a raindrop detection apparatus that detects raindrops adhering to the windshield, and includes a first light emitting element that emits first light and a second light emitting element that emits second light. And a light receiving element arranged so as to be able to receive the first light and the second light, and a raindrop amount determining means for determining a raindrop amount based on a light receiving amount of the first light in the light receiving element and a light receiving amount of the second light in the light receiving element The first light is received by the light receiving element as reflected light reflected by the windshield, the second light is received by the light receiving element along an optical path not passing through the windshield, and the second light is turned on when the first light emitting element is turned on. The light emitting element is turned off, the first light emitting element is turned off when the second light emitting element is turned on, and the raindrop amount determination by the raindrop amount determining means is stopped when the amount of the second light received by the light receiving element is less than a predetermined value. It is characterized in.

  In this configuration, in the raindrop detection device according to claim 7 of the present invention described above, in addition to the received light amount of the first light in the light receiving element, the light receiving element performs the raindrop amount determination executed by the raindrop amount determining means. The difference is that the received light amount of the second light is used. That is, the amount of the first light received by the light receiving element whose size changes corresponding to the raindrop adhesion state on the windshield and the second light receiving element that is always a constant size regardless of whether the raindrop adheres to the windshield. The amount of raindrops is determined with reference to both the amount of received light. In this case, even if the light receiving characteristic of the light receiving element changes, the influence of the light receiving element simultaneously affects both the amount of the first light received by the light receiving element and the amount of the second light received by the light receiving element. It is possible to suppress the amount determination accuracy from being affected. As a result, it is possible to prevent erroneous determination of the measurement light path distortion element existing on the optical path from the first light emitting element in the raindrop detection device through the windshield to the light receiving element as raindrop adhesion. At the same time, the raindrop detection accuracy can be improved.

  According to a ninth aspect of the present invention, the raindrop detection apparatus includes a reflecting surface disposed on the second light emitting side of the second light emitting element so as to face the second light emitting element, and the second light is reflected by the reflecting surface. The light is directly incident on the light receiving element.

  With such a configuration, the presence of the optical path distortion element in the space between the second light emitting element and the reflecting surface and between the reflecting surface and the light receiving element is detected based on the amount of the second light received by the light receiving element. Therefore, it is possible to increase the detection accuracy by expanding the detection area of the optical path distortion element by the light receiving element.

  According to a tenth aspect of the present invention, in the raindrop detection apparatus according to the tenth aspect of the present invention, during the period when the raindrop amount determination by the raindrop amount determination unit is stopped, the determination result by the raindrop amount determination unit immediately before the raindrop amount determination is stopped is It is characterized by being maintained as a result.

  According to the above configuration, when the raindrop amount determination result by the raindrop detection device is applied to another control, the raindrop amount detection is performed even during the period when the raindrop amount determination of the raindrop amount determination unit is stopped by the control unit. Since the result is output, inconveniences such as interruption of another control to which the raindrop amount determination result by the raindrop detection apparatus is applied can be prevented.

  According to an eleventh aspect of the present invention, there is provided a raindrop detection apparatus comprising a temperature raising means for raising the temperature of air forming the path of the first light and the second light, and the amount of the second light received by the light receiving element is a predetermined value. When the temperature is lower, the temperature raising means is operated to raise the temperature of the air that forms the paths of the first light and the second light.

  According to such a configuration, by operating the temperature raising means, the air temperature in the raindrop detection device is raised to lower the relative humidity, and water vapor and condensed water are removed, that is, the light path distortion element is removed. be able to. Therefore, it is possible to remove the optical path distortion element from the raindrop detection device in a short time and restart the raindrop amount determination by the raindrop amount determination means.

  In this case, as in the raindrop detection device according to claim 12 of the present invention, the temperature raising means may be operated for a predetermined time from the time when the amount of the second light received by the light receiving element is less than the predetermined value. It is possible to remove the optical path distortion element from the raindrop detection device in a short time and restart the raindrop amount determination by the raindrop amount determination means.

  Hereinafter, an embodiment of a raindrop detection apparatus according to the present invention will be described with reference to FIGS. 1 to 5 by taking as an example a case where the raindrop detection apparatus is applied to a raindrop detection apparatus 1 mounted on an automobile.

(First embodiment)
The raindrop detection device 1 detects the amount of raindrops mounted on the vehicle 100 by the raindrop sensor 20 and attached to the front windshield 101 of the vehicle 100, and controls the operation of the wiper device 10 for wiping the raindrops based on the determination result. ing.

  First, the overall configuration of the raindrop detection apparatus 1 will be described.

  The raindrop detection apparatus 1 includes a raindrop detection sensor 20, a wiper apparatus 10, a microcomputer 40 that is a control unit that determines the amount of raindrops based on signals from the raindrop sensor 20, and drives and controls the wiper apparatus 10 based on the determination result. It is composed of The raindrop detection device 1 is supplied with electric power from a vehicle battery via an ignition switch of the vehicle.

  The wiper device 10 includes a wiper blade 13 that is driven through a link mechanism 12 by a driving torque generated by a wiper motor 11 to perform a reciprocating wiping operation on the front windshield 101, and a wiper switch 14 that is operated by a driver of an automobile. I have. The wiper switch 14 is installed in the driver's seat of the passenger compartment, and has a switch function for switching the wiping operation of the wiper blade 13 to stop, low speed operation, high speed operation, and automatic control by manual operation of the driver. The wiper switch 14 is rotated to any one of four operating positions, for example, so that one of these operation modes is selected. The wiper switch 14 outputs information about the selected operation mode to the microcomputer 40. The reciprocating wiping operation of the wiper blade 13 is executed by outputting a drive instruction signal to the wiper motor 13 from the wiper control unit 41 provided in the microcomputer 40.

  The raindrop sensor 20 is disposed on the vehicle interior side of the front windshield 101. As shown in FIG. 1, the raindrop sensor 20 is disposed in the wiping area A of the wiper blade 13 on the outer surface of the front windshield 101 and on the upper side of the automobile. In the embodiment of the raindrop detection apparatus according to the present invention, as shown in FIG. 1, two wiper blades 13 are provided, and the wiping area A of each wiper blade 13 partially overlaps. The raindrop sensor 20 is disposed in the wiping area A of one of the wiper blades 13. The raindrop sensor 20 detects the amount of raindrops adhering in the detection area Ad, and the raindrop sensor 20 is attached so that the detection area Ad is in the wiping area A of the wiper blade 13. The raindrop sensor 20 is electrically connected to a microcomputer 40 described later.

  As shown in FIG. 3, the raindrop sensor 20 includes a light emitting diode 21 that is a light emitting element that emits measurement light, a photodiode 22 that is a first light receiving element that receives the measurement light reflected by the front windshield 101, and a photodiode 23. A photodiode 24, which is a second light receiving element that receives measurement light guided by an optical path that does not pass through the front windshield 101, a lens 25 made of a translucent material, and diodes 21, 22, and 23 are mounted. The printed circuit board 26 that forms the electric circuit portion of the raindrop sensor 20 and the casing 27 that houses and holds each of the above components are included. The casing 27 is formed from a resin material or a metal material.

  The lens 25 is formed of a material that can transmit the measurement light emitted from the light emitting diode 21, for example, a resin material. When the raindrop sensor 20 is fixed to the front windshield 101, the lens 25 is in close contact with the front windshield 101 via the silicon sheet 28 as shown in FIG. That is, the surface of the lens 25 on the front windshield 101 side, the silicon sheet 28, and the front windshield 101 are in close contact with each other so that there is no air layer over the entire boundary. Thereby, the light emitted from the light emitting diode 21 can be used for raindrop detection with high efficiency. The lens 25 has a reflection surface 25a described later. As shown in FIG. 3, the reflection surface 25 a is formed on the light emitting side of the light emitting diode 21 so as to face the light emitting diode 21 and face the photodiode 22.

  Here, a path until the measurement light emitted from the light emitting diode 21 reaches each photodiode 22, 23, 24 will be described.

  First, the raindrop detection optical paths L1 and L2 will be described. The raindrop detection optical path L1 is incident on the lens 25, reflected on the side surface 25b of the lens 25 and the surface 101a of the front windshield 101, and incident on the photodiode 22, as indicated by the solid arrow L1 in FIG. It is. The raindrop detection optical path L2 is a path that enters the lens 25, reflects off the surface 101a of the front windshield 101, and enters the photodiode 23, as indicated by a solid arrow L2 in FIG.

  Next, the measurement light path distortion element detection optical path L3 that is an optical path that does not pass through the front windshield 101 will be described. The measurement light path distortion element detection optical path L3 is a path that is reflected by the reflection surface 25a of the lens 25 and enters the photodiode 24, as indicated by a solid arrow L3 in FIG. That is, the measurement light path distortion element detection optical path L3 does not pass through the front windshield 101 as shown in FIG.

  As shown in FIG. 3, the light emitting diode 21 and the photodiodes 22, 23, and 24 are mounted on a common printed circuit board 26. A light emitting element driving circuit (not shown) and a detection amplifier circuit (not shown) are also mounted on the printed board 26. The light emitting diode 21 is connected to the microcomputer 40 via a light emitting element driving circuit (not shown), and the microcomputer 40 controls the turning on / off of the light emitting diode 21. On the other hand, each of the photodiodes 22, 23, 24 is connected to the microcomputer 40 via a detection amplification circuit (not shown), and a detection signal corresponding to the detected raindrop amount or measured light path distortion element amount is sent to the microcomputer 40. Output.

  When no raindrop is attached to the detection area Ad on the front windshield 101, the measurement light emitted from the light emitting diode 21 travels as indicated by solid line arrows L1 and L2 in FIG. Most of the light is reflected by the front windshield 101 and received by the photodiodes 23 and 24. However, when the raindrop D is attached to the detection area Ad, a part of the measurement light emitted from the light emitting diode 21 passes through the raindrop D attached to the detection area Ad in FIG. It proceeds as shown by and exits from the front windshield 101. Therefore, the amount of light received by the photodiodes 23 and 24 is reduced. As described above, the amount of raindrops adhering to the detection region Ad is optically detected based on the amount of raindrops adhering to the detection region Ad and the amount of light received by the photodiodes 23 and 24. In the raindrop detection apparatus 1 according to the first embodiment of the present invention, the detection signal of the raindrop sensor 20 decreases as the amount of raindrops adhering to the detection area Ad increases, and the raindrop sensor 20 decreases as the amount of raindrops adhering to the detection area Ad decreases. The detection signal becomes larger.

  Incidentally, there may be a measurement light path distortion element that is an element for distorting the path of measurement light emitted from the light emitting diode 21 inside the raindrop detection sensor 20. Specifically, the measurement light path distortion element includes water vapor contained in the space in the raindrop sensor 20, the water vapor on the inner surface of the raindrop detection sensor 20 of the lens 25, the light emitting surface of the light emitting diode 21, and the photodiodes 22 and 23. , 24 frost and water droplets condensed on the light receiving surface, cigarette smoke entering the raindrop sensor 20 and the like. For example, when the engine is started and the air conditioner is operated in the heating mode when the windshield is cold in winter, moisture in the air condenses and adheres to the surface of each part in the raindrop detector. In addition, when the air conditioner is operated in the cooling mode when the room temperature is high in summer, moisture in the air condenses and adheres to the surface of each part in the raindrop detector. Further, when the occupant smokes, the smoke enters the raindrop detection device. When these measurement light path distortion elements are present on the above-described raindrop detection optical paths L1 and L2, the path of the measurement light from the light emitting diode 21 is deviated by the action of the measurement light path distortion elements and received by the photodiodes 23 and 24. The amount decreases. That is, the magnitude of the output signal from the raindrop amount detection photodiodes 23 and 24 is reduced by both the raindrop adhesion to the detection region Ad of the front windshield 101 and the presence of the measurement light path distortion element in the raindrop sensor 20. To do. On the other hand, the magnitude of the output signal from the measurement light path distortion element detection photodiode 22 is such that the measurement light path distortion element detection optical path L3 does not pass through the front windshield 101, so that the detection region of the front windshield 101 is detected. It does not change depending on the adhesion of raindrops to Ad, and decreases only due to the presence of a measurement light path distortion element in the raindrop sensor 20. Accordingly, the presence of the measurement light path distortion element in the raindrop sensor 20 can be determined based on the decrease in the magnitude of the output signal from the measurement light path distortion element detection photodiode 22.

  The microcomputer 40 actually includes a CPU that performs control processing and arithmetic processing, a storage device including a memory such as a read-only memory (ROM) and a writable memory (RAM) for storing various programs and data, A It is configured to include functions of an input circuit such as a / D converter, an output circuit, and a power supply circuit. However, here, a wiper control unit 41 related to the drive control of the wiper motor 11 and a raindrop amount determination unit 42 that determines the amount of raindrops attached to the front windshield 101 based on output signals from the photodiodes 23 and 24 of the raindrop sensor 20. A conceptual description will be given focusing on the measurement light path distortion element amount determination unit 43 that determines the presence of the measurement light path distortion element in the raindrop sensor 20 based on the output signal from the photodiode 22 of the raindrop sensor 20.

  The wiper control unit 41 takes in information on the current rainfall situation from the raindrop amount determination unit 42 and information on the wiping mode from the wiper switch 14 and drives and controls the wiper motor 13 based on these information. That is, when the wiper switch 14 is operated to stop the wiping operation (OFF mode), to operate at a low speed (LO mode), and to operate at a high speed (HI mode), the wiper control unit 41 receives the predetermined drive instruction signal. Is output to the wiper motor 11. On the other hand, when the wiper switch 14 is operated in automatic control (AUTO mode), the wiper control unit 41 drives according to the raindrop amount determined by the raindrop amount determination unit 42 based on the first signal from the raindrop sensor 20. A signal is output to the wiper motor 11.

  By the way, when the foreign matter exists in the raindrop sensor 20 when the wiper switch 14 is operated in the automatic control (AUTO mode), for example, the water vapor in the raindrop sensor 20 condenses due to a rapid temperature change and the lens 25. Condensation may occur on the surface. As a result, the amount of light incident on the photodiodes 23 and 24 via the raindrop detection optical paths L1 and L2 described above decreases, and the magnitude of the output signal from the raindrop amount detection photodiodes 23 and 24 decreases. Based on this, the raindrop amount determination unit 42 determines that there is raindrop adhesion or that the rainfall amount has increased. That is, when there is no raindrop adhesion, it is determined that there is raindrop adhesion and the wiper motor 11 is driven to wipe the wiper blade 13, or if it is raining, it is determined that the amount of rainfall has increased and the wiper blade The wiping operation speed of 13 is switched, and a state appears as if the wiper blade 13 malfunctioned.

  Therefore, in the embodiment of the raindrop detection apparatus according to the present invention, when the wiper switch 14 is operated to automatic control (AUTO mode), first, the measurement light from the raindrop sensor 20 is measured in the measurement light path distortion element amount determination unit 43. Based on the output signal from the photodiode 22 for detecting the path distortion element, the measurement light path distortion element amount determination process in the raindrop sensor 20 is executed. As a result, when it is determined that there is no measurement light path distorting element, the wiper control unit 41 outputs a drive instruction signal corresponding to the raindrop amount determined by the raindrop amount determination unit 42 to the wiper motor 11, and the wiper blade The wiping operation by 13 is performed. On the other hand, if it is determined that there is a measurement light path distortion element amount as a result of the measurement light path distortion element amount determination process by the measurement light path distortion element amount determination unit 43, the wiper control unit 41 determines the raindrop amount in the raindrop amount determination unit 42. The detection processing is stopped, and a drive instruction signal based on the raindrop amount determined by the raindrop amount determination unit 42 is wiped immediately before the measurement light path distortion element amount determination unit 43 determines that the measurement light path distortion element is present. Output to the motor 11. Accordingly, when the wiper switch 14 is operated in automatic control (AUTO mode) in the raindrop detection device 1, even if condensation occurs in the raindrop sensor 20, the reciprocating wiping operation condition of the wiper blade 13, for example, The reciprocating wiping operation interval, that is, the stop time of the warper blade 13, the wiping operation speed, and the like can be prevented from fluctuating due to erroneous determination of foreign matter as raindrops.

  After the measurement light path distortion element is detected in the raindrop sensor 20, for example, when water droplets on the surface of the lens 25 evaporate and disappear, the measurement light path distortion element amount determination unit 43 determines that there is no measurement light path distortion element. Therefore, the wiper control unit 41 restarts the raindrop amount detection processing in the raindrop amount determination unit 42 and outputs a drive instruction signal corresponding to the raindrop amount determined by the raindrop amount determination unit 42 to the wiper motor 11 again. Then, the wiping operation by the wiper blade 13 is performed.

  Next, the wiper automatic control process executed in the microcomputer 40 of the raindrop detection apparatus 1 configured as described above will be described with reference to FIG. FIG. 4 is a flowchart showing a specific processing procedure of motor control processing mainly executed by the wiper control unit 41.

  When the automatic control (AUTO mode) is selected through manual operation of the wiper switch 14 by the driver of the automobile, the wiper automatic control process shown in FIG. 4 is started. When the process is started, the wiper control unit 41 first executes an initialization process in step S1.

  Subsequently, the wiper control unit 41 performs a measurement light path distortion element amount determination process in step S2. The measurement light path distortion element amount determination processing is executed by the measurement light path distortion element amount determination unit 43. As a result of the measurement light path distortion element amount determination process, when it is determined that there is no measurement light path distortion element, the wiper control unit 41 executes a raindrop amount determination process as the process of the subsequent step S3. This raindrop amount determination process is executed by the raindrop amount determination unit 42.

  Subsequently, the wiper control unit 41 sets the reciprocating wiping operation specification of the wiper blade 13 based on the raindrop amount determined in the raindrop amount determination process in step S3 as the processing of the subsequent step S4, and instructs the wiper motor 11 to drive. Output a signal.

  On the other hand, if it is determined that the measurement light path distortion element amount is present as a result of the measurement light path distortion element amount determination process in step S2, the wiper control unit 41 performs the raindrop amount determination process by the rain droplet amount determination unit 42 as the process in step S5. To cancel.

  Subsequently, the wiper control unit 41 sets the raindrop amount as the raindrop amount by the raindrop amount determination process immediately before the measurement light path distortion element amount determination process of step S2 as the process of step S6, and the wiper blade 13 reciprocating wiping operation based on the raindrop amount. The specification is set and a drive instruction signal is output to the wiper motor 11.

  Next, the operation of the present embodiment will be summarized with reference to the timing charts shown in FIGS. 5 (a) to 5 (e). 5A shows the time transition of the amount of condensation on the surface of the lens 25 in the raindrop sensor 20, and FIG. 5B shows the time transition of the output signals of the photodiodes 23 and 24 in the raindrop sensor 20. FIG. FIG. 5C shows the time transition of the output signal of the photodiode 22 in the raindrop sensor 20, FIG. 5D shows the determination processing state by the raindrop amount determination unit, and FIG. 5E shows the drive output from the wiper control unit 41. It is a timing chart which shows the output time of an instruction signal, respectively.

  In the description of this figure, the AUTO mode is selected through manual operation of the wiper switch 14 by the driver of the automobile, and the measurement light path distortion element amount determination process and the raindrop amount determination process are already started. To do. The output signals of the photodiodes 23 and 24 shown in FIG. 5A are, for example, the average value of the output signal of the photodiode 23 and the output signal of the photodiode 24, or the sum of both output signals.

  Under such a premise, raindrops adhere to the detection area Ad of the raindrop sensor 20, and the wiper blade 13 is reciprocally wiped from the raindrop amount determined by the raindrop amount determination unit 42 based on the output signals of the photodiodes 23 and 24. When it is determined through the wiper control unit 41 that it is necessary to wipe the wiping area A of the front windshield 101, first, as shown in FIG. 5D, for example, at the time t10, the wiper control unit 41 A pulsed drive instruction signal is output to the wiper motor 11. Then, based on the wiping level (wiping speed, intermittent time) of the wiper blade 13 corresponding to the determined raindrop amount at this time point, a pulse-shaped drive instruction signal from the wiper control unit 41 to the wiper motor 11 also at time t11. Is output.

  As the amount of rainfall increases, as shown in FIG. 5A, the output signals of the photodiodes 23 and 24 decrease from time t12 to time t13, and the amount of raindrop determined by the raindrop amount determination unit 42 also increases. In response to this, the wiper control unit 41 sets the intermittent time of the wiping operation of the wiper blade 13 as the intermittent time T2 (t14 to t15) shorter than the intermittent time T1 (t10 to t11) before the increase in rainfall, at time t14. Then, a pulsed drive instruction signal is output from the wiper control unit 41 to the wiper motor 11. Subsequently, a drive instruction signal is similarly output at time t15 and time t16 every intermittent time T2.

  At this time, the output signal of the photodiode 22 in the raindrop sensor 20 does not change as shown in FIG.

  At time t <b> 17, as shown in FIG. 5A, condensation occurs on the surface of the lens 25 due to condensation of water vapor, which is a measurement light path distortion element, inside the raindrop sensor 20, and the amount of condensation on the lens surface 25. Will increase. At time t20, the amount of condensation on the lens 25 surface stops increasing, and the amount of condensation on the lens 25 surface does not change until time t24. Further, at time t24, condensation on the surface of the lens 25 begins to evaporate, and at time t27, condensation on the surface of the lens 25 completely disappears.

  In the period (t17 to t27) from dew condensation adhering to the surface of the lens 25 to dew condensation, the detection signals of the photodiodes 23 and 24 of the raindrop sensor 20 and the detection signal of the photodiode 22 of the raindrop sensor 20 are shown in FIG. As shown in FIG. 5B and FIG. 5C, the detection signal level is constant during a period (t20 to t24) in which the amount of condensation adheres to the surface of the lens 25 decreases as the amount of condensation adheres to the lens 25 increases. In the period (t24 to t27) from which the state is maintained and the attached condensation starts to evaporate and disappears completely, it increases in conjunction with the decrease in the amount of condensation on the lens 25 surface.

  The measurement light path distortion element amount determination unit 43 of the microcomputer 40 compares the output signal of the photodiode 22 with the threshold value K as a measurement light path distortion element amount determination process, and determines whether there is a measurement light path distortion element. Judgment is being made. In the period (t17 to t27) from dew adherence to dew condensation on the surface of the lens 25 described above, first, at time t18, the output signal of the photodiode 22 becomes smaller than the threshold value K, and the measured light path distortion element amount. The determination unit 43 determines that there is a measurement light path distortion element. During the period from time t18 to time t26, a determination result that there is a measurement light path distortion element is output. Next, at time t26, the output signal of the photodiode 22 becomes larger than the threshold value K, and the measurement light path distortion element amount determination unit 43 determines that there is no measurement light path distortion element.

  During the period (t18 to t26) in which the measurement light path distortion element amount determination unit 43 outputs the determination result that the measurement light path distortion element is present, the wiper control unit 41 determines that the measurement light path distortion element is present. In response, as shown in FIG. 5D, the raindrop amount determination processing by the raindrop amount determination unit 42 is stopped. At the same time, the wiper control unit 41 sends a pulse-shaped drive instruction signal to the wiper motor 11 based on the wiping level of the wiper blade 13 calculated based on the raindrop amount just before the determination result that the measurement light path distortion element is present. Output. That is, in the case of this embodiment, at the wiping level of the wiper blade 13 calculated based on the raindrop amount immediately before the determination result that the measurement light path distortion element is present, the interval between the wiping operations of the wiper blade 13 is the intermittent time T2. Therefore, even during a period (t18 to t26) in which the measurement light path distortion element amount determination unit 43 outputs a determination result indicating that there is a measurement light path distortion element, the wiper control unit 41 performs an interval time T2. A pulsed drive instruction signal is output.

  At time t26, the measurement light path distortion element amount determination unit 43 outputs a determination result that there is no measurement light path distortion element, and the wiper control unit 41 receives the raindrop as shown in FIG. The raindrop amount determination process by the amount determination unit 42 is executed again. The wiper control unit 41 outputs to the wiper motor 11 a pulsed drive instruction signal based on the wiping level of the wiper blade 13 calculated based on the raindrop amount determination result by the raindrop amount determination unit 42.

(Second Embodiment)
The raindrop detection device 1 according to the second embodiment of the present invention is different in the configuration of the raindrop sensor 20 from the raindrop detection device 1 according to the first embodiment of the present invention. That is, the ceramic heater 29 which is a temperature raising means is mounted on the printed circuit board 26 as shown in FIG. The ceramic heater 29 is made of a conductive ceramic material and generates heat when energized.

  In the second embodiment, when condensation, which is a measurement light path distortion element, occurs in the raindrop sensor 20, a voltage is applied to the ceramic heater 29 to generate heat, and the raindrop sensor 20, specifically, the lens 25 in FIG. The air temperature in the space surrounded by the printed circuit board 26 is raised, thereby aiming to quickly evaporate the dew on the lens 25 surface. The voltage application control to the ceramic heater 29 is performed, for example, as shown in a timing chart showing the time transition of the voltage applied to the ceramic heater 29 in FIG. This is performed during a period (t18 to t26) in which a determination result indicating that there is a distortion element is output.

  According to the second embodiment, condensation can be eliminated in a short time. In other words, the period for which the wiper motor 11 is operated at the wiping level of the wiper blade 13 calculated based on the raindrop amount immediately before the determination result that the measurement light path distortion element is present is obtained instead of the actual raindrop amount. In addition, automatic wiper control in accordance with actual rain conditions can be performed.

  Further, since the heating operation can be electrically controlled by using the ceramic heater 29 as the temperature raising means, the temperature in the raindrop sensor 20 can be easily set to a desired temperature, that is, a temperature at which condensation can be effectively eliminated. Can be controlled.

  In addition, in the raindrop detection apparatus 1 according to the second embodiment of the present invention described above, the measurement light path distortion element amount determination unit 43 determines that the measurement light path distortion element is present during the voltage application period to the ceramic heater 29. Although it is the same as the output period (t18 to t26), it is not necessary to limit to this. For example, a configuration may be adopted in which a voltage is applied only for a preset period from time t18 when the determination result that the measurement light path distortion element is present is first output. Alternatively, in addition to the voltage application control based on the determination result that the measurement light path distortion element amount is present by the measurement light path distortion element amount determination unit 43, the occurrence of condensation is predicted based on information such as the outside temperature and the room temperature, and the prediction result If the voltage application control is performed based on the above, it is possible to prevent the deposition of condensation.

  Moreover, in the raindrop detection apparatus 1 according to the second embodiment of the present invention described above, the ceramic heater 29 is used as the temperature raising means and is installed inside the raindrop sensor 20. The parts need not be limited to such combinations, and may be other types of temperature raising means and installation parts. Further, the temperature raising means may be provided outside the raindrop sensor 20 instead of being directly installed on the raindrop sensor 20. For example, it is good also as a structure which utilizes the air conditioner with which a motor vehicle is provided as a temperature rising means.

(Third embodiment)
The raindrop detection device 1 according to the third embodiment of the present invention is obtained by changing the configuration of the raindrop sensor 20 with respect to the raindrop detection device 1 according to the first embodiment of the present invention. In the raindrop sensor 20 according to the first embodiment of the present invention, one light emitting diode 21 that is a light emitting element, two photodiodes 23 and 24 that are first light receiving elements, and one photodiode that is a second light receiving element. 22 is provided. In other words, light emitted from one common light source travels on a plurality of optical paths, and a plurality of light receiving elements provided corresponding to the respective optical paths measure the amount of light that follows each optical path. Yes. That is, the raindrop sensor 20 according to the first embodiment of the present invention is composed of one light emitting element and a plurality of light receiving elements. In contrast, in the raindrop detection apparatus 1 according to the third embodiment of the present invention, the raindrop sensor 20 is composed of a plurality of light emitting elements and one light receiving element. The configuration of the raindrop sensor 20 according to the third embodiment of the present invention will be described below. Note that, in the raindrop sensor 20 according to the third embodiment of the present invention, the configuration other than the light-emitting diode that is a light-emitting element and the photodiode that is a light-receiving element is the same as that of the raindrop sensor 20 according to the first embodiment. To do.

  As shown in FIG. 8, the raindrop sensor 20 according to the third embodiment of the present invention includes a photodiode 51 as a light receiving element, two light emitting diodes 52 and 53 as a first light emitting element, and a light emitting diode as a second light emitting element. 54.

  Here, the path | route until the light which each light emitting diode 52, 53, 54 emits reaches each photodiode 51 is demonstrated.

  First, the raindrop detection optical paths L4 and L5 as optical paths passing through the front windshield 101, which is an optical path followed by the first light emitted from the light emitting diodes 52 and 53 as the first light emitting elements, will be described. As shown by a solid line arrow L4 in FIG. 8, the raindrop detection optical path L4 is emitted from the light emitting diode 52 and is incident on the lens 25, and further reflected by the surface 101a of the front windshield 101, and again inside the lens 25. This is an optical path incident on the photodiode 51. As shown by a solid line arrow L5 in FIG. 8, the raindrop detection optical path L5 is emitted from the light emitting diode 53 and enters the lens 25, and is further reflected by the surface 101a of the front windshield 101 and again into the lens 25. This is an optical path that is incident, reflected by the side surface 25 b of the lens 25, and incident on the photodiode 51.

  Next, a measurement light path distortion element detection optical path L6 as an optical path that does not pass through the front windshield 101, which is an optical path followed by the second light emitted from the light emitting diode 54 as the second light emitting element, will be described. The measurement light path distortion element detection optical path L6 is an optical path that is emitted from the light emitting diode 54, reflected by the reflecting surface 25a of the lens 25, and incident on the photodiode 51, as indicated by a solid arrow L6 in FIG.

  The photodiode 51 and the light emitting diodes 52, 53, and 54 are mounted on a common printed circuit board 26 as shown in FIG. A light emitting element driving circuit (not shown) and a detection amplifier circuit (not shown) are also mounted on the printed board 26. The light emitting diodes 52, 53, and 54 are connected to the microcomputer 40 via a light emitting element driving circuit (not shown), and the microcomputer 40 controls the turning on and off of the light emitting diodes 52, 53, and 54. On the other hand, the photodiode 51 is connected to the microcomputer 40 via a detection amplification circuit (not shown), and outputs a detection signal corresponding to the detected raindrop amount or the measured light path distortion element amount to the microcomputer 40.

  Here, the operation of the raindrop sensor 20 in the raindrop detection apparatus 1 according to the third embodiment of the present invention, particularly the lighting drive method of each of the light emitting diodes 52, 53, and 54, and the detection signal processing method of the photodiode 51 will be described.

  In the raindrop detection apparatus 1 according to the third embodiment of the present invention, the photodiode 51 receives the amount of light emitted from the light emitting diodes 52 and 53, that is, the amount of light received for determining the amount of raindrops, and the light received from the light emitting diode 54. It is necessary to individually detect the amount, that is, the received light amount related to the determination of the measured light path distortion element amount. For example, when the light emitting diodes 52, 53, and 54 are driven to light simultaneously, the amount of light received by the photodiode 51 is the sum of the amount of light received by the light emitting diodes 52 and 53 and the amount of light received by the light emitting diode 54. Both cannot be identified. Therefore, in the raindrop detection apparatus 1 according to the third embodiment of the present invention, the light emitting diodes 52 and 53 and the light emitting diode 54 are controlled to be turned on and off differently. That is, when the light emitting diodes 52 and 53 are turned on, the light emitting diodes 54 are turned off, and when the light emitting diodes 54 are turned on, the light emitting diodes 52 and 53 are turned off. Here, the light emitting diodes 52 and 53 are simultaneously turned on and off, and are driven as if they were one light emitting diode. Furthermore, the detection signal of the photodiode 51 when the light emitting diodes 52 and 53 are lit is input to the raindrop amount determination unit 42 of the microcomputer 40, and the detection signal of the photodiode 51 when the light emitting diode 54 is lit is input to the microcomputer 40. The measurement light path distortion element amount determination unit 43 is inputted. For example, the rising timing of the lighting drive signals of the light emitting diodes 52 and 53 is matched with the detection signal capturing timing of the raindrop amount determination unit 42 from the photodiode 51, and the rising timing of the lighting drive signal of the light emitting diode 54 is measured. The detection timing of the detection signal from the photodiode 51 in the optical path distortion element amount determination unit 43 is matched. Such control is executed in a control unit (not shown) in the microcomputer 40.

  Next, in the raindrop detection apparatus 1 according to the third embodiment of the present invention, the light emitting diodes 52, 53, 54 are turned on / off, the output signal level of the photodiode 51, the raindrop amount determination unit 42, and the measurement light path distortion element amount A specific example of capturing the output signal of the photodiode 51 in the determination unit 43 will be described based on the timing chart shown in FIG. 9A shows the time transition of turning on / off the light emitting diodes 52 and 53, FIG. 9B shows the time transition of turning on / off the light emitting diode 54, and FIG. 9C shows the photodiode 51. 9D shows the time transition of the output signal level of the photodiode 51 in the raindrop amount determination unit 42, and FIG. 9E shows the measurement light path distortion element amount determination unit 43. The time transition of the output signal capture of the photodiode 51 in FIG.

  As shown in FIG. 9A and FIG. 9B, the light emitting diodes 52 and 53 and the light emitting diode 54 are turned on and off at the opposite timings. Thereby, as the output signal of the photodiode 51, an output signal corresponding only to the light emitting diodes 52 and 53 and an output signal corresponding to only the light emitting diode 54 appear alternately. The raindrop amount determination unit 42 has a photodiode 51 output signal corresponding only to the light emitting diodes 52 and 53, and the measurement light path distortion element amount determination unit 43 has a photodiode 51 output signal only corresponding to the light emitting diode 54. Are selectively incorporated.

  The raindrop amount determination operation in the raindrop amount determination unit 42, the measurement light path distortion element amount determination operation in the measurement light path distortion element amount determination unit 43, and the raindrop amount erroneous determination avoidance measure when it is determined that the measurement light path distortion element is present are: This is the same as in the case of the raindrop detection apparatus 1 according to the first embodiment of the present invention, and a description thereof will be omitted.

  In the raindrop detection apparatus 1 according to the third embodiment of the present invention described above, the wiper switch 14 is automatically controlled in the raindrop detection apparatus 1 in the same manner as the raindrop detection apparatus 1 according to the first embodiment of the present invention ( Even if condensation occurs in the raindrop sensor 20 when operated in the AUTO mode), the reciprocating wiping operation condition of the wiper blade 13, for example, the reciprocating wiping operation interval, that is, the stop time of the warper blade 13 or the wiping operation It is possible to prevent a problem that the speed or the like fluctuates due to a foreign object being erroneously determined as a raindrop.

  In the raindrop detection device 1 according to the third embodiment of the present invention, a ceramic heater 29 as a temperature raising means is installed in the raindrop sensor 20 as in the raindrop detection device 1 according to the second embodiment of the present invention. When dew condensation, which is a measurement light path distorting element, occurs, a voltage is applied to the ceramic heater 29 to generate heat, and the air temperature in the raindrop sensor 20, specifically, the space surrounded by the lens 25 and the printed circuit board 26 is increased. Thereby, it may be configured to quickly evaporate the dew condensation adhering to the surface of the lens 25.

  The raindrop amount detection device according to the present invention is not limited to the configuration exemplified in the first to third embodiments, and can be implemented by appropriately changing each of the above embodiments.

  In the first embodiment and the second embodiment of the present invention, the raindrop amount determination unit 42 performs the raindrop amount determination processing based on the output signals from the photodiodes 23 and 24. That is, the determination is based on only the light reflected from the front windshield 101 out of the measurement light from the light emitting diode 21. On the other hand, in addition to the output signals from the photodiodes 23 and 24, the output signal from the photodiode 22, that is, the output signal based on the amount of received light guided by the optical path not passing through the front windshield 101 is used. May be. In this case, in the raindrop amount determination process, for example, the ratio of the output signals from the photodiodes 23 and 24 and the output signal from the photodiode 22 can be calculated, and the raindrop amount can be determined based on this ratio. In this way, even if the light emission amount of the light emitting diode 21 changes for some reason, the raindrop amount determination can be performed with high accuracy.

  In the third embodiment of the present invention, the raindrop amount determination unit 42 performs raindrop amount determination processing based on the output signal from the photodiode 51 when the first light that is light from the light emitting diodes 52 and 53 is received. Has been implemented. That is, the determination is based on only the light reflected by the front windshield 101. On the other hand, in addition to the output signal of the photodiode 51 described above, the output signal from the photodiode 51 when the second light that is the light from the light emitting diode 54 is received, that is, not through the front windshield 101. Raindrop amount determination processing may be performed using an output signal based on the amount of received light guided by the optical path. In this case, in the raindrop amount determination processing, for example, an output signal of the photodiode 51 when receiving light from the light emitting diodes 52 and 53 and an output signal of the photodiode 51 when receiving light from the light emitting diode 54 are used. A ratio can be calculated, and the amount of raindrops can be determined based on this ratio. In this way, even if the light receiving characteristics of the photodiode 51 change due to some cause, the raindrop amount can be determined with high accuracy.

  In each of the above embodiments, the windshield on which the raindrop detection device 1 is installed has been described as the front windshield 101 in front of the driver's seat. However, the windshield need not be limited to the front windshield 101, and other windows, for example, rear windows. You may apply to a shield.

  Moreover, in each said embodiment, although the example which mounted the said raindrop amount detection apparatus in the motor vehicle was mentioned, the mounting place is not restricted to a motor vehicle. In addition, it is useful to be widely mounted on mobile objects such as airplanes, railway vehicles, and ships.

1 is a schematic diagram showing a state in which a raindrop detection device 1 according to a first embodiment of the present invention is mounted on an automobile 100. FIG. 1 is a block diagram showing an overall configuration of a raindrop detection apparatus 1 according to a first embodiment of the present invention. It is sectional drawing explaining the structure of the raindrop sensor 20, and is the III-III sectional view taken on the line in FIG. It is the flowchart which showed the specific process sequence of the wiper automatic control process performed in the raindrop detection apparatus by 1st Embodiment of this invention. In the raindrop detection apparatus 1 according to the first embodiment of the present invention, (a) shows the time transition of the amount of condensation on the surface of the lens 25 in the raindrop sensor 20, and (b) shows the photodiodes 23 and 24 in the raindrop sensor 20. (C) is a time transition of the output signal of the photodiode 22 in the raindrop sensor 20, (d) is a determination processing state by the raindrop amount determination unit, and (e) is from the wiper control unit 41. It is a timing chart which shows the output time of the drive instruction | indication signal output, respectively. It is sectional drawing explaining the structure of the raindrop sensor 20 of the raindrop detection apparatus 1 by 2nd Embodiment of this invention. In the raindrop detection apparatus 1 according to the second embodiment of the present invention, (a) shows the time transition of the amount of condensation on the surface of the lens 25 in the raindrop sensor 20, and (b) shows the photodiodes 23 and 24 in the raindrop sensor 20. (C) is a time transition of the output signal of the photodiode 22 in the raindrop sensor 20, (d) is a determination processing state by the raindrop amount determination section, and (e) is a wiper control section. (F) is a timing chart showing the time transition of the voltage applied to the ceramic heater 29. FIG. It is sectional drawing explaining the structure of the raindrop sensor 20 of the raindrop detection apparatus 1 by 3rd Embodiment of this invention. In the raindrop detection apparatus 1 according to the third embodiment of the present invention, (a) shows the time transition of lighting / extinguishing of the light emitting diodes 52 and 53, and (b) shows the time transition of lighting / extinguishing of the light emitting diode 54, (C) shows the time transition of the output signal level of the photodiode 51, (d) shows the time transition of the output signal capture of the photodiode 51 in the raindrop amount determination unit 42, and (e) shows the measurement light path distortion element. 4 is a timing chart showing each time transition of the output signal capture of the photodiode 51 in the quantity determination unit 43;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raindrop detection apparatus 10 Wiper apparatus 11 Wiper motor 12 Transmission mechanism 13 Wiper blade 14 Wiper switch 20 Raindrop sensor 21 Light emitting diode (light emitting element)
22 Photodiode (second light receiving element)
23, 24 Photodiode (first light receiving element)
25 Lens 26 Printed circuit board 27 Casing 28 Silicon sheet 29 Ceramic heater (temperature raising means)
40 Microcomputer (control means)
41 Wiper control unit 42 Raindrop amount determination unit 43 Measurement light path distortion element amount determination unit 51 Photodiode (light receiving element)
52 Light Emitting Diode (First Light Emitting Element)
53 Light Emitting Diode (First Light Emitting Element)
54 Light Emitting Diode (Second Light Emitting Element)
DESCRIPTION OF SYMBOLS 100 Automobile 101 Front windshield A Wiping area Ad Detection area D Raindrop K Threshold L1, L2 Raindrop detection optical path L3 Measurement optical path distortion element detection optical path L4, L5 Raindrop detection optical path L6 Measurement optical path distortion element detection optical path T1, T2 Intermittent time

Claims (12)

A raindrop detection device for detecting raindrops adhering to a windshield,
A light emitting element that emits measurement light;
A first light receiving element that receives the measurement light reflected by the windshield;
A second light receiving element that receives the measurement light guided by an optical path that does not pass through the windshield;
Raindrop amount determination means for determining the amount of raindrops based on the amount of light received by the first light receiving element,
A raindrop detection means for stopping the raindrop amount determination by the raindrop amount determination means when the amount of light received by the second light receiving element is smaller than a predetermined value. A raindrop detection device for detecting raindrops adhering to a windshield,
A light emitting element that emits measurement light;
A first light receiving element that receives the measurement light reflected by the windshield;
A second light receiving element that receives the measurement light guided by an optical path that does not pass through the windshield;
A raindrop amount determination means for determining a raindrop amount based on the received light amount of the first light receiving element and the received light amount of the second light receiving element;
A raindrop detection means for stopping the raindrop amount determination by the raindrop amount determination means when the amount of light received by the second light receiving element is smaller than a predetermined value. A reflective surface disposed opposite to the light emitting element on the measurement light emitting side of the light emitting element;
The raindrop detection apparatus according to claim 1, wherein the measurement light is reflected by the reflecting surface and directly enters the second light receiving element.   The determination result by the raindrop amount determination unit immediately before the raindrop amount determination is stopped is maintained as the raindrop amount determination result during the period when the raindrop amount determination of the raindrop amount determination unit is stopped. The raindrop detection device according to any one of claims 1 to 3. A temperature raising means for raising the temperature of the air forming the path of the measuring light,
5. The temperature of air forming the path of the measurement light is increased by operating the temperature raising means when the amount of light received by the second light receiving element is less than a predetermined value. The raindrop detection means according to any one of the above.   6. The raindrop detecting means according to claim 5, wherein the temperature raising means is operated for a predetermined time from the time when the amount of light received by the second light receiving element becomes smaller than a predetermined value. A raindrop detection device for detecting raindrops adhering to a windshield,
A first light emitting element emitting first light;
A second light emitting element that emits second light; a light receiving element that is arranged to receive the first light and the second light; and
A raindrop amount determination means for determining a raindrop amount based on the amount of received light of the first light in the light receiving element;
The first light is received by the light receiving element as reflected light reflected by the windshield,
The second light is received by the light receiving element along an optical path not passing through the windshield,
When the first light emitting element is turned on, the second light emitting element is turned off, and when the second light emitting element is turned on, the first light emitting element is turned off.
The raindrop detection device, wherein when the amount of the second light received by the light receiving element is smaller than a predetermined value, the raindrop amount determination by the raindrop amount determination means is stopped. A raindrop detection device for detecting raindrops adhering to a windshield,
A first light emitting element emitting first light;
A second light emitting element that emits second light; a light receiving element that is arranged to receive the first light and the second light; and
A raindrop amount determination means for determining a raindrop amount based on a received light amount of the first light in the light receiving element and a received light amount of the second light in the light receiving element;
The first light is received by the light receiving element as reflected light reflected by the windshield,
The second light is received by the light receiving element along an optical path not passing through the windshield,
When the first light emitting element is turned on, the second light emitting element is turned off, and when the second light emitting element is turned on, the first light emitting element is turned off.
The raindrop detection device, wherein when the amount of the second light received by the light receiving element is smaller than a predetermined value, the raindrop amount determination by the raindrop amount determination means is stopped. A reflective surface disposed on the second light emitting side of the second light emitting element so as to face the second light emitting element;
The raindrop detection apparatus according to claim 7, wherein the second light is reflected by the reflecting surface and directly enters the light receiving element.   The determination result by the raindrop amount determination unit immediately before the raindrop amount determination is stopped is maintained as the raindrop amount determination result during the period when the raindrop amount determination of the raindrop amount determination unit is stopped. The raindrop detection device according to any one of claims 7 to 9. A temperature raising means for raising the temperature of the air forming the path of the first light and the second light;
When the light receiving amount of the second light in the light receiving element is smaller than a predetermined value, the temperature raising means is operated to raise the temperature of air forming the path of the first light and the second light. The raindrop detection means according to any one of claims 7 to 10.   12. The raindrop detecting means according to claim 11, wherein the temperature raising means is operated for a predetermined time from the time when the amount of the second light received by the light receiving element is less than a predetermined value.

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