JP2009109518A - Raindrop detector and wiper automatic control unit having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a raindrop detector capable of making detection accuracy of raindrops and cost effectiveness compatible. <P>SOLUTION: Initial rain determination is performed, based on a ratio r<SB>2</SB>/r<SB>1</SB>, by canceling the dependence of ambient temperature inherent in the quantities of light received r<SB>1</SB>, r<SB>1</SB>, r<SB>2</SB>in a first light-receiving element 110 and a second light-receiving element 28 each, as in the case of the ratio R<SB>3</SB>/(R<SB>1</SB>+R<SB>2</SB>), thus high determination accuracy is obtained, even immediately after the turning on of an ignition switch 6 and selection operation of "automatic" in a wiper switch 12. Also, for acquiring the ratio r<SB>2</SB>/r<SB>1</SB>at reference, without adherence of raindrops to the windshield 4, the quantities of received light r<SB>1</SB>, r<SB>1</SB>, r<SB>2</SB>in the first light-receiving element 110 and the second light-receiving element 28 each, may be measured for the quantity of emitted light, at least for one point. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a raindrop detection device that detects raindrops adhering to a windshield, and a wiper automatic control device including the raindrop detection device.

In a wiper automatic control device that automatically controls a wiper that wipes raindrops attached to a windshield, a raindrop detection device is used.
Conventionally, as a raindrop detection device, a device that detects the amount of light received by a light receiving element by guiding light of the light emitting element reflected by a windshield to the light receiving element is known (see, for example, Patent Documents 1 and 2). . In such a raindrop detection apparatus, attention is paid to the fact that the amount of light guided to the light receiving element changes according to the state of raindrop attachment to the windshield, and the attachment of raindrops is determined from the detection result of the light receiving element.

  By the way, in the conventional raindrop detection apparatus described above, since the light emission amount emitted from the light emitting element and the light reception amount of the light receiving element change, the output of the light receiving element varies according to the ambient temperature. Therefore, it is important to avoid a decrease in detection accuracy due to such temperature characteristics. Therefore, in the raindrop detection apparatus of Patent Document 1, correlation data representing the correlation between the output of the light receiving element and the ambient temperature is acquired in advance, and the detection accuracy is improved by correcting the output of the light receiving element based on the correlation data. We are trying to improve.

  In addition, in a conventional raindrop detection device mounted on a windshield of an automobile or the like, since the driver's field of view is blocked when the size increases, the ratio of the raindrop detection area to the projection area on the windshield, that is, It is desired to improve the size efficiency. Therefore, in the raindrop detection device of Patent Document 2, the light emitting element and the light receiving element are arranged at the vertices of the virtual triangle or the virtual parallelogram so that light emitted by one light emitting element is received simultaneously by the two light receiving elements. By doing so, size efficiency is improved.

JP 2001-349961 A US Pat. No. 6,433,501

  However, in the raindrop detection device of Patent Document 1, it is necessary to measure the output of the light receiving element at a wide range of temperatures before shipment from the factory in order to obtain the correlation data described above. Such measurement over a wide range of temperatures is time consuming and time consuming, and causes an increase in cost. Further, since the correlation data obtained by such measurement is large in size, a storage means for storing the correlation data requires a large storage capacity, which increases the price.

  Further, in the raindrop detection apparatus of Patent Document 2, a portion surrounded by each side of the virtual triangle or the virtual parallelogram is a raindrop non-detection region. That is, the raindrop detection device of Patent Document 2 inevitably has a large dead space that is not involved in the detection of raindrops, so that there is a limit in improving the size efficiency.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a raindrop detection device that achieves both raindrop detection accuracy and cost effectiveness.
Another object of the present invention is to provide a raindrop detection device that improves size efficiency.

  According to the first aspect of the present invention, the light receiving portion is guided to the windshield by the first optical path emitted from the light emitting element and passing through the reflecting portion, and then receives the reference light reflected by the windshield. At the same time, the light receiving unit receives the reference light reflected from the windshield after being guided to the windshield by the second optical path that is emitted from the light emitting element and does not pass through the reflecting unit. According to the first aspect of the present invention, the determination means determines the attachment of raindrops based on the amount of light received by such a light receiving section. In the windshield, the region of the windshield that reflects the reference light of each optical path substantially matches the raindrop detection region. . Here, the region of the first optical path that reflects the reference light can be freely set by adjusting the position of the reflecting portion through which the first optical path passes. Therefore, by setting the position of the area reflecting the reference light in the first optical path so as to cover the outside of the area reflecting the reference light in the second optical path, the raindrop from the projection area on the windshield of the raindrop detection device The non-detection area is reduced. As a result, the dead space not involved in the detection of raindrops is reduced, so that the size efficiency can be improved.

  According to the second aspect of the present invention, the light receiving unit receives the first optical path light receiving element that receives the reference light of the first optical path reflected by the windshield, and the second optical path that receives the reference light of the second optical path reflected by the windshield. And a two-light path light receiving element. In this way, by receiving the reference light of the first optical path and the reference light of the second optical path by the respective light receiving elements, it is possible to know the light quantity more accurately for the reference light of each of the optical paths. Therefore, the determination accuracy of raindrop adhesion by the determination means, in other words, the accuracy of raindrop detection is improved.

In the third aspect of the present invention, the reflecting portion is formed on the optical body that makes the reference light incident on the windshield from the inner wall side of the windshield. Assemblability can be improved.
According to the fourth and fifth aspects of the present invention, the reflecting portion is provided between the substrate portion on which the light emitting element, the first optical path light receiving element and the second optical path light receiving element are mounted, and the windshield substantially parallel thereto. The physique of the raindrop detection device can be made compact.

  According to the sixth aspect of the present invention, the light receiving element of the light receiving section is emitted from the light emitting element and guided to the windshield by the first optical path passing through the first reflecting section, and then the reference light reflected by the windshield. Receive. The light receiving element also receives reference light that is emitted from the light emitting element and guided to the windshield by a second optical path that does not pass through the reflecting portion, and then sequentially reflected by the windshield and the second reflecting portion. According to such a configuration, since the light receiving element that receives the reference light in the first optical path and the light receiving element that receives the reference light in the second optical path are shared, the number of components can be reduced and the cost can be improved. it can.

In the invention according to claim 7, since the first and second reflecting portions are formed in the optical body that makes the reference light incident on the windshield from the inner wall side of the windshield, the optical body that has existed so far is inexpensive. In addition, the assemblability of the raindrop detection device can be improved.
According to the eighth and ninth aspects of the present invention, the first and second reflecting portions are provided between the substrate portion on which the light emitting element and the light receiving element are mounted and the windshield substantially parallel thereto. The physique can be made compact.

  The invention according to claim 10 drives the wiper when the raindrop detection device according to any one of claims 1 to 9 and the determination means of the raindrop detection device determine that raindrops are attached. And a wiper automatic control device provided with a driving means. According to this wiper automatic control device, it is possible to receive the same effects as the invention according to any one of claims 1 to 9 provided as a raindrop detection device.

It is a side view which shows the raindrop detection apparatus by 1st embodiment. It is a block diagram which shows the wiper automatic control apparatus by 1st embodiment. FIG. 3 is a sectional view taken along line III-III in FIG. 1. It is a schematic diagram which shows the detection area | region of the raindrop detection apparatus by 1st embodiment. It is a flowchart which shows the flow of the wiper automatic control process by 1st embodiment. It is a flowchart which shows the flow of the initial rain determination by 1st embodiment. It is a characteristic view for demonstrating the principle of the initial rain determination by 1st embodiment. It is a flowchart which shows the flow of the normal rain determination by 1st embodiment. It is a flowchart which shows the flow of the normal rain determination by 2nd embodiment. It is a flowchart which shows the flow of the normal rain determination by 3rd embodiment. It is a flowchart which shows the flow of the initial rain determination by 4th embodiment. It is a characteristic view for demonstrating the principle of the initial rain determination by 4th embodiment. It is a side view which shows the raindrop detection apparatus by 5th embodiment. It is XIV-XIV sectional drawing of FIG. It is a block diagram which shows the wiper automatic control apparatus by 5th embodiment. It is a schematic diagram which shows the detection area | region of the raindrop detection apparatus by 5th embodiment. It is a flowchart which shows the flow of the initial rain determination by 5th embodiment. It is a flowchart which shows the flow of the normal rain determination by 5th embodiment. It is a side view which shows the raindrop detection apparatus by the modification of 5th embodiment. It is XX-XX sectional drawing of FIG.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
A wiper automatic control apparatus according to a first embodiment of the present invention is shown in FIG. The wiper automatic control device 2 is mounted on the vehicle and automatically controls the wiper 5 that wipes raindrops attached to the windshield 4 on the front surface of the passenger compartment.

First, the overall configuration of the wiper automatic control device 2 will be described.
The wiper automatic control device 2 includes a wiper drive device 10, a raindrop detection device 20, and the like. The wiper drive device 10 and the raindrop detection device 20 are supplied with electric power from the vehicle battery 7 via the vehicle ignition switch 6.

  A wiper drive device 10 that drives the wiper 5 includes a wiper switch 12, a wiper motor drive circuit 14, and a wiper motor 16. The wiper switch 12 is installed in the driver's seat of the passenger compartment, and has a plurality of operating positions such as auto, low / medium / high speed, and stop. The wiper switch 12 outputs a signal indicating the operating position to the wiper motor drive circuit 14 and the CPU 32 of the raindrop detection device 20. The wiper motor drive circuit 14 switches the drive state of the wiper motor 16 according to signals received from the wiper switch 12 and the CPU 32 of the raindrop detection device 20. Specifically, the wiper motor drive circuit 14 drives the wiper motor 16 in accordance with a control signal received from the CPU 32 when receiving a signal representing auto as the operation position of the wiper switch 12. Further, when the wiper motor drive circuit 14 receives a signal representing either low, medium, or high speed as the operation position of the wiper switch 12, the wiper motor drive circuit 14 drives the wiper motor 16 so as to realize any one of the operation speeds. Furthermore, the wiper motor drive circuit 14 stops the wiper motor 16 when receiving a signal indicating the stop as the operation position of the wiper switch 12. The wiper motor 16 swings the wiper 5 when driven by the wiper motor drive circuit 14 and positions the wiper 5 above the cowl top panel of the vehicle when stopped by the wiper motor drive circuit 14.

As shown in FIG. 1, the raindrop detection device 20 is mounted on the inner wall 8 side of the windshield 4 and detects raindrops adhering to the outer wall 9 side of the windshield 4. The raindrop detection device 20 is arranged in such a manner that the projection area of the device 20 onto the windshield 4 is within the area wiped by the wiper 5 in the windshield 4.
As shown in FIG. 2, the raindrop detection apparatus 20 includes a light emission control circuit 22, a light emitting element 24, first to third optical path light receiving elements 26 to 28, detection / amplification circuits 29 to 31, a CPU 32, and a storage unit 34. .

The light emission control circuit 22 adjusts the magnitude of the current supplied to the light emitting element 24 according to a control signal received from the CPU 32.
The light emitting element 24 is composed of a light emitting diode, and emits reference light so as to have a light emission amount according to a current supplied from the light emission control circuit 22. Here, as the reference light emitted from the light emitting element 24, for example, infrared light or the like is used.

Each of the first to third optical path light receiving elements 26 to 28 is composed of a photodiode and receives reference light guided by different optical paths. Each of the light receiving elements 26 to 28 is connected to a corresponding detection / amplification circuit 29 to 31, and outputs detection signals representing the received light amounts R ₁ , R ₂ and R ₃ of the reference light to the detection / amplification circuits 29 to 31. To do.

  The detection / amplification circuits 29 to 31 linearly amplify the detection signals of the corresponding light receiving elements 26 to 28 and output them to the CPU 32. Here, signal amplification processing in each of the detection / amplification circuits 29 to 31 is performed substantially in synchronization with reception of the detection signal. Further, the signal amplification factor in each of the detection / amplification circuits 29 to 31 is adjusted according to a control signal received from the CPU 32.

  The CPU 32 executes a control program stored in the ROM 35 of the storage unit 34 to generate control signals to be output to the wiper motor drive circuit 14, the light emission control circuit 22, and the detection / amplification circuits 29 to 31. Control all 10 operations. During this control, the RAM 36 of the storage unit 34 temporarily stores various data obtained by the calculation of the CPU 32.

Next, the structure of the raindrop detection device 20 will be described. In the following description, the horizontal direction and the vertical direction in FIG. 3 are defined as an X direction and a Y direction, respectively.
The raindrop detection apparatus 20 includes a substrate section 40 and an optical body 50 as shown in FIGS. 1 and 3 in addition to the elements 22, 24, 26 to 32, 34.

  The board part 40 is fixed to the inner wall 8 of the windshield 4 via a member such as a case (not shown). The substrate part 40 is formed in a flat plate shape and has a plate surface 42 substantially parallel to the inner wall 8 of the windshield 4. The light emitting element 24 and the first to third optical path light receiving elements 26 to 28 are mounted on the plate surface 42 of the substrate unit 40. Here, when a virtual plane O passing through the center of the substrate unit 40 in the Y direction and orthogonal to the plate surface 42 is defined, one light emitting element 24 is arranged on each side of the virtual plane O. The first to third optical path light receiving elements 26 to 28 are arranged one by one on the virtual plane O, respectively. In the X direction from the one end 44 side to the other end 45 side of the substrate portion 40, the light emitting element 24, the third optical path light receiving element 28, the first optical path light receiving element 26, and the second optical path light receiving element 27 are arranged in this order.

  The optical body 50 is made of resin and has first and second collimating lenses 52 and 53, a reflecting surface 54, a prism 56, first and second converging lenses 58 and 59, and a reflecting light guide surface 60. The prism 56 is attached to the inner wall 8 of the windshield 4 via a light-transmitting silicon sheet 62, and other elements 52 to 54, optical elements 50 on the side opposite to the inner wall 8 of the prism 56. 58-60 are integrally formed. Thereby, substantially the entire optical body 50 is disposed between the substrate portion 40 and the windshield 4.

  One first collimating lens 52 is provided on each side of the virtual plane O, and one reflecting surface 54 is provided on each side of the virtual plane O. The first collimating lens 52 is a plano-convex lens in which the light emitting element 24 and the reflecting surface 54 on the same side with respect to the virtual plane O are located on the optical axis, and the reference light incident from the light emitting element 24 is used as its optical axis. To the reflecting surface 54. Here, in the X direction, the first collimating lens 52 is positioned closer to the one end 44 of the substrate than the light emitting element 24, and the optical axis of the first collimating lens 52 is about 45 with respect to the outer wall 9 of the windshield 4. -Inclined. The reflection surface 54 is substantially perpendicular to the outer wall 9 of the windshield 4 and the plate surface 42 of the substrate portion 40, and is closer to the one end 44 side of the substrate portion 40 than the light emitting element 24 and the first collimating lens 52 in the X direction. positioned. The reflecting surface 54 reflects the reference light guided from the first collimating lens 52 on the same side with respect to the virtual plane O and guides it to the prism 56.

One second collimating lens 53 is provided on each side of the virtual plane O. The second collimating lens 53 is a plano-convex lens in which the light emitting element 24 on the same side with respect to the virtual plane O is positioned on the optical axis, and the reference light incident from the light emitting element 24 is converted into a prism along its own optical axis. Lead to 56. Here, the optical axis of the second collimating lens 53 is inclined by about 45 ° with respect to the outer wall 9 of the windshield 4 and about 90 ° with respect to the optical axis of the first collimating lens 52 on the same side with respect to the virtual plane O. It is inclined. As a result, the second collimating lens 53 is located closer to the other end 45 of the substrate portion 40 than the light emitting element 24 in the X direction.
The prism 56 windshields the reference light guided by the first optical path L ₁ passing through the first collimating lens 52 and the reflecting surface 54 and the second optical path L ₂ passing through the second collimating lens 53 from the inner wall 8 side. 4 and is reflected by the outer wall 9 of the windshield 4.

The first converging lens 58 is provided in a form straddling both sides of the virtual plane O. The first converging lens 58 is a plano-convex lens in which the first optical path light receiving element 26 is located on the optical axis. In the X direction, the first converging lens 58 is located on the other end 45 side of the substrate portion 40 with respect to the light emitting element 24 and the second collimating lens 53, and the optical axis of the first converging lens 58 is the outer wall 9 of the windshield 4. It is inclined about 45-. The reference light of the first optical path L ₁ reflected by the outer wall 9 of the windshield 4 is incident on the first converging lens 58 through the prism 56. The first converging lens 58 guides the reference light of the first optical path L ₁ thus incident to the first optical path light receiving element 26 along its own optical axis. Here, an elliptical region D ₁ schematically shown in FIG. 4 is a region in which the reference light of the first optical path L ₁ can be reflected on the outer wall 9 of the windshield 4 and guided to the first optical path light receiving element 26. It is. When raindrops adhere to this region D ₁ , the amount of reference light reflected by the windshield 4 decreases, and the amount of received light R _{1 of} the first optical path light receiving element 26 changes. That is, the area D ₁ is an area where the first optical path light receiving element 26 detects the attachment of raindrops using the reference light of the first optical path L ₁ , and is hereinafter referred to as a detection area D ₁ . In FIG. 4, a rectangular area S schematically shows a projection area of the raindrop detection device 20 onto the windshield 4.

As shown in FIGS. 1 and 3, the second converging lens 59 is provided in a form straddling both sides of the virtual plane O. The second converging lens 59 is formed by combining two plano-convex lenses 64 and 65 in which the second optical path light receiving element 27 is arranged on the respective optical axes in the X direction. In the X direction, the second converging lens 59 is located on the other end 45 side of the substrate portion 40 with respect to the light emitting element 24 and the first converging lens 58, and each light of the plano-convex lenses 64 and 65 constituting the second converging lens 59. The axis is inclined about 45 ° with respect to the outer wall 9 of the windshield 4. The reference light of the second optical path L ₂ reflected by the outer wall 9 of the windshield 4 is incident on the second converging lens 59 through the prism 56. The second converging lens 59 guides the reference light in the second optical path L ₂ thus incident to the second optical path light receiving element 27 along the optical axes of the plano-convex lenses 64 and 65. Here, an elliptical region D ₂ schematically shown in FIG. 4 is a region in which the reference light of the second optical path L ₂ can be reflected on the outer wall 9 of the windshield 4 and guided to the second optical path light receiving element 27. , and the in the present embodiment is configured so as not to overlap with the region D _1. When raindrops in this region D ₂ is attached, since the reflection amount of the reference light due to the outer wall 9 is reduced, the received light amount R ₂ of the second optical path the light receiving element 27 is changed. That is, the region D ₂ is a region where the second optical path light receiving element 27 detects the attachment of raindrops using the reference light of the second optical path L ₂ , and is hereinafter referred to as a detection region D ₂ .

As shown in FIGS. 1 and 3, the reflective light guide surface 60 is provided in a form straddling both sides of the virtual plane O. The reflective light guide surface 60 is substantially parallel to the outer wall 9 of the windshield 4 and the plate surface 42 of the substrate portion 40, and is disposed between the light emitting element 24 and the third optical path light receiving element 28 in the X direction and the first collimating lens. 52 and the second collimating lens 53. The reflective light guide surface 60 reflects the reference light guided from each light emitting element 24 and guides it to the same third optical path light receiving element 28. In other words, the third optical path L ₃ that guides the reference light to the third optical path light receiving element 28 without passing through the windshield 4 is formed by using the reflecting action of the reflective light guide surface 60.

  Next, the wiper automatic control process performed by the CPU 34 according to the control program will be described with reference to the flowchart of FIG. The automatic control process is started when the ignition switch 6 is turned on and auto is selected as the operation position of the wiper switch 12, and when the ignition switch 6 is turned off or the operation position of the wiper switch 12 is set as auto. It ends when other than is selected.

  In step S1 of the wiper automatic control process, the RAM 36 is initialized. In the subsequent step S2, initial rain determination for determining the attachment of raindrops to the windshield 4 is performed. As a result, if it is determined that raindrops are attached, a control signal for driving the wiper 6 only once is given to the wiper motor drive circuit 14 in step S3, and then the process proceeds to step S4. On the other hand, if it is determined that no raindrops are attached, the process proceeds directly to step S4.

  In step S4, the RAM 36 is initialized. In the subsequent step S5, normal rain determination for determining the attachment of raindrops to the windshield 4 is performed. As a result, when it is determined that raindrops are attached, in step S6, a control signal for driving the wiper 6 at a predetermined speed a predetermined number of times is given to the wiper motor drive circuit 14, and then the process returns to step S4. On the other hand, if it is determined that no raindrops are attached, the process directly returns to step S4.

Here, the initial rain determination in step S2 and the normal rain determination in step S5 will be described in detail.
First, the initial rain determination will be described with reference to the flowchart of FIG.
In step S11 of the initial rain determination, the light emitting elements 24 are caused to emit light sequentially, and the received light amounts R ₁ , R ₂ and R ₃ of the first to third optical path light receiving elements 26 to 28 are detected. At this time, the light emission control circuit 22 is supplied with a control signal for setting the sum of the light emission amounts of the respective light emitting elements 24 as a set value, and each of the detection / amplifier circuits 29 to 31 has a signal amplification factor as a set value. Gives a control signal for. As a result, when the detection signals of the respective light receiving elements 26 to 28 are received from the detection / amplification circuits 29 to 31, the received light amounts R ₁ , R ₂ and R ₃ represented by these detection signals are extracted and stored in the RAM 36.

In FIG. 7, “◯” indicates the sum R ₁ + R ₂ of the received light amounts R ₁ and R ₂ of the first and second optical path light receiving elements 26 and 27 extracted in step S11. As can be seen from FIG. 7, the received light amount sum R ₁ + R ₂ decreases when raindrops are attached (B) compared to when raindrops are not attached to the windshield 4 (A). This is because the amount of reflection by the regions D ₁ and D ₂ of the windshield 4 decreases due to the attachment of raindrops.

In FIG. 7, “●” indicates the received light amount R ₃ of the third optical path light receiving element 28 extracted in step S11. As can be seen from FIG. 7, the received light amount R ₃ does not substantially change between when the raindrops are not attached to the windshield 4 (A) and when the raindrops are attached (B). This is because the reference light is directly guided to the third optical path light receiving element 28 without passing through the windshield 4.

As described above, since the received light amount sum R ₁ + R ₂ changes depending on whether or not raindrops are attached to the windshield 4, it is possible to determine whether or not raindrops are attached by monitoring the sum R ₁ + R _2. Expected to be. However, since the received light amounts R ₁ and R ₂ represented by the outputs of the first and second optical path light receiving elements 26 and 27, that is, the detection signals of the respective elements 26 and 27 vary depending on the ambient temperature, the received light amount sum R ₁ + R ₂ is obtained. It is not possible to accurately determine the adhesion of raindrops simply by monitoring. Therefore, the present inventors have found that the coefficients of variation with respect to the ambient temperature are substantially equal with respect to the amounts of received light R ₁ , R ₂ , and R ₃ represented by the outputs of the light receiving elements 26 to 28, that is, the detection signals of the elements 26 to 28. It was discovered and monitored by taking the ratio R ₃ / (R ₁ + R ₂ ) between the received light amount sum R ₁ + R ₂ and the received light amount R ₃ . This is the ratio _{R 3 / (R 1 + R} 2) by taking, is canceled coefficient of variation for each value R _1, R _2, R ₃ for ambient temperature, yet the value R ₃ is theoretically, adhesion of raindrops This is because the value of the ratio R ₃ / (R ₁ + R ₂ ) is not affected.

In more, step S12 above, reads the received light amount R _1, R _2, R ₃ of the light receiving elements 26 to 28 stored in the RAM36 in step S11, the values R _1, R _2, R ₃ to a ratio R ₃ / (R ₁ + R ₂ ) is calculated as the current ratio C _R. Further, read out at step S13, before factory shipment or the like, the storage ratio C _m is R ₃ / ratio set during a reference no adhesion of raindrops to the windshield 4 (R ₁ + R ₂₎ the ROM 35. The storage ratio C _m is set by performing the same processing as in steps S11 and S12 at the time of the reference, and storing the ratio R ₃ / (R ₁ + R ₂ ) calculated thereby in the ROM 35 as the storage ratio C _m. This is realized.

In step S14, the ratio C _R / C _m between the storage ratio C _m read in step S13 and the current ratio C _R calculated in step S12 is calculated as the reduction rate F. If raindrops adhere to the windshield 4 during the execution of step S11, the rate of decrease F is a value greater than one.

In step S15, it is determined whether or not the decrease rate F calculated in step S14 is equal to or greater than a threshold value _Fth . When the decrease rate F is equal to or greater than the threshold value F _th, it is determined that raindrops are attached to the windshield 4, while when the decrease rate F is less than the threshold value F _th, it is determined that no raindrops are attached. To do. Note that the threshold value F _th in the initial rain determination is set to a value larger than 1 while taking into account an error that occurs in the drop rate F due to disturbance or the like.

Next, normal rain determination will be described with reference to the flowchart of FIG.
In step S21 for normal rain determination, the light emission control circuit 22 and the detection / amplification circuits 29 and 30 are controlled at a timing when no raindrops are attached, such as immediately after passing through the wiper. The signal amplification factors of the detection / amplification circuits 29 and 30 are adjusted. In the present embodiment, step S21 is executed after the determination that there is no raindrop adhesion in step S2 or when the wiper 6 is driven by the execution of step S3 or S6. Therefore, the detection signals output from the detection / amplification circuits 29 and 30 during the adjustment may be assumed to represent the received light amounts R ₁ and R ₂ at the reference time when raindrops are not attached to the windshield 4. it can. Therefore, in step S21 of this embodiment, the above adjustment is performed so that the received light amounts R ₁ and R ₂ represented by the detection signals of the first and second optical path light receiving elements 26 and 27 become the reference values R _b1 and R _b2 , respectively. The reference values R _b1 and R _b2 are set as the received light amount at the reference time.

In step S22, the light emitting elements 24 are caused to emit light sequentially after a predetermined time delay or the like, and the received light amounts R ₁ and R ₂ of the first and second optical path light receiving elements 26 and 27 are detected. At this time, the light emission amount (sum) of the light emitting elements 24 and the signal amplification factors of the detection / amplification circuits 29 and 30 are respectively held at the values adjusted in step S21. As a result, when the detection signals of the first and second optical path light receiving elements 26 and 27 are received from the detection / amplification circuits 29 and 30, respectively, the received light amounts R ₁ and R ₂ represented by the detection signals are extracted and stored in the RAM 36. .

In step S23, the ratio {100-100 · (R) obtained from the sum of the received light amounts R ₁ and R ₂ stored in the RAM 36 in step S22 and the sum of the reference values R _b1 and R _b2 determined in step S21. ₁ + R ₂ ) / (R _b1 + R _b2 )}% is calculated as the reduction rate F. If raindrops adhere to the windshield 4 at the time of execution of step S22, the reduction rate F is a value greater than 0%.

In step S24, it is determined whether or not the reduction rate F calculated in step S23 is equal to or greater than a threshold value _Fth . When the decrease rate F is equal to or greater than the threshold value F _th, it is determined that raindrops are attached to the windshield 4, while when the decrease rate F is less than the threshold value F _th, it is determined that no raindrops are attached. To do. Note that the threshold value F _th in the normal rain determination is set to a value larger than 0% while taking into account an error that occurs in the decrease rate F due to disturbance or the like.

As described above, in the first embodiment, in the initial rain determination of the wiper automatic control process, the ratio obtained by canceling the dependency on the ambient temperature inherent in the received light amounts R ₁ , R ₂ , R ₃ of the light receiving elements 26 to 28. Since the raindrop adhesion determination is performed based on R ₃ / (R ₁ + R ₂ ), the determination is accurate. Therefore, high determination accuracy can be achieved even immediately after the ignition switch 6 is turned on and the auto selection operation is performed at the wiper switch 12. In addition, in order to obtain the ratio R ₃ / (R ₁ + R ₂ ) at a reference time when no raindrops are attached to the windshield 4, at least the received light amounts R ₁ , R ₂ , R ₃ of the respective light receiving elements 26 to 28 are set. It is only necessary to measure the light emission amount at one point. Therefore, not only the time required for measuring each received light amount R ₁ , R ₂ , R ₃ at the reference time is shortened, but also the storage capacity of the RAM 36 can be reduced, so that the cost can be reduced.
In the first embodiment, the normal rain determination following the initial rain determination of the wiper automatic control process can be realized with a smaller calculation processing amount than in the case of the initial rain determination, so that the determination time is shortened.

Further in the first embodiment, the outer wall 9 of the windshield 4 of the first optical path L ₁ of the reference light detection region D ₁ and the second optical path L ₂ of the reference light detection region D ₂ and is raindrop detection so as not to overlap each other The apparatus 20 is comprised. Thereby, in the projection area S of the raindrop detection device 20 onto the windshield 4, the dead space that is not involved in the detection of raindrops is reduced. Therefore, the ratio of the detection areas D ₁ and D _{2 in} the projection area S, That is, the size efficiency is improved. Moreover, since the raindrop detection device 20 is provided with a light receiving element whose detection target is the region D ₁ and a light receiving element whose detection target is the region D ₂ , the first and second optical paths L ₁ and L ₂ are provided separately. Each light quantity can be known more accurately with respect to the reference light.

  Furthermore, in the first embodiment, the raindrop detector 20 uses the optical body 50 in which the reflection surface 54 and the reflection light guide surface 60 are integrated with the prism 56 and the various lenses 52, 53, 58, 59. Therefore, the assemblability of the raindrop detection device 20 is improved as compared with the case where the reflective surface 54 and the reflective light guide surface 60 are formed separately from the other elements of the optical body 50.

  In addition, in the first embodiment, the reflection surface 54 and the reflection light guide surface 60 are provided between the board portion 40 on which the various elements 24 and 26 to 28 are mounted in the raindrop detection apparatus 20 and the windshield 4 substantially parallel thereto. The optical body 50 including it is arranged. Thereby, since the physique of the raindrop detection apparatus 20 becomes small in the opposing direction of the board | substrate part 40 and the windshield 4, the improvement of size efficiency can be achieved, without deteriorating the visual field of the driver | operator of a vehicle.

(Second embodiment)
In the wiper automatic control process according to the second embodiment of the present invention, as shown in FIG. 9, normal rain determination steps S31 to S35 are performed in the same manner as the initial rain determination steps S11 to S15. According to the second embodiment, the raindrop adhesion determination can be accurately performed based on the ratio R ₃ / (R ₁ + R ₂ ) even in the normal rain determination. Therefore, the wiper switch 12 selects auto. While it is being performed, a highly accurate determination is continuously realized.

(Third embodiment)
In the wiper automatic control process according to the third embodiment of the present invention, the normal rain determination is performed according to the flowchart shown in FIG.
Specifically, in the normal rain determination of the third embodiment, first, in step S41, processing similar to that in step S11 of initial rain determination is performed.

In the subsequent step S42, fail-safe determination is performed. In this fail-safe determination, when at least one of the following conditions (1) to (3) is not satisfied, it is determined as normal and the process proceeds to step S43. On the other hand, when all of the conditions (1) to (3) are satisfied, it is determined that there is an abnormality, and the process proceeds to step S47.
(1) The received light amounts R ₁ and R _{2 of} the first and second optical path light receiving elements 26 and 27 stored in the RAM 36 in step S41 are not zero.
(2) The received light amount R _{3 of} the third optical path light receiving element 28 stored in the RAM 36 in step S41 is zero.
(3) The output of the control signal to the light emission control circuit 22 is not zero.

  In steps S43 to S46 after being determined to be normal, processing similar to that in steps S12 to S15 for initial rain determination is performed. On the other hand, in steps S47 to S50 after being determined to be abnormal, the same processing as in steps S21 to S24 of the normal rain determination according to the first embodiment is performed.

According to the third embodiment, when at least one of the conditions (1) to (3) is normal, the operation continues while the auto is selected by the wiper switch 12 as in the second embodiment. Thus, accurate normal rain determination based on the ratio R ₃ / (R ₁ + R ₂ ) can be realized. On the other hand, since it is possible to carry out the normal rain determination without using the ratio R ₃ / (R ₁ + R ₂ ) in the initial rain determination when the conditions (1) to (3) are all satisfied, A situation in which the wiper 5 cannot be automatically controlled due to the abnormality is avoided.

(Fourth embodiment)
In the automatic control process according to the fourth embodiment of the present invention, the initial rain determination is performed according to the flowchart shown in FIG.
Specifically, in the initial rain determination of the fourth embodiment, in step S51, the light emitting elements 24 are caused to emit light sequentially, and the received light amounts R ₁ , R ₂ , R ₃ of the first to third optical path light receiving elements 26 to 28 are determined. Detect each. At this time, the light emission control circuit 22 is given a control signal for setting the sum of the light emission amounts of the light emitting elements 24 to the set value T _1, and the signal amplification factor is set to each of the detector / amplifier circuits 29 to 31. A control signal for setting A ₁ , A ₂ , and A ₃ is given. As a result, when the detection signals of the respective light receiving elements 26 to 28 are received from the detection / amplification circuits 29 to 31, the received light amounts R ₁ , R ₂ and R ₃ represented by these detection signals are extracted and stored in the RAM 36.

In step S52, the light emission of each light-emitting element 24 and the step S51 are performed by changing the light emission amount, the detected amount of first to third optical path receiving element _{26~28 R 1, R 2, R} 3 , respectively . At this time, the light emission control circuit 22 is supplied with a control signal for setting the sum of the light emission amounts of the respective light emitting elements 24 to a set value T ₂ different from the set value T _1, and the detection / amplifier circuits 29 to 31 are supplied to Control signals for setting the signal amplification factors to the set values A ₁ , A ₂ and A ₃ are given. As a result, when the detection signals of the respective light receiving elements 26 to 28 are received from the detection / amplification circuits 29 to 31, the received light amounts R ₁ , R ₂ and R ₃ represented by these detection signals are extracted and stored in the RAM 36.

In FIG. 12, “◯” indicates the sum R ₁ + R ₂ of the received light amounts R ₁ and R ₂ of the first and second optical path light receiving elements 26 and 27 extracted in steps S51 and S52. In FIG. 12, “G” is the ratio of the difference between the received light amount R ₁ + R ₂ in each step S51, S52 and the difference between the light emission amounts T ₁ , T ₂ in each step S51, S52, ie, the unit light emission amount. The rate of change of the received light amount sum R ₁ + R ₂ is shown. As can be seen from FIG. 12, the change rate of the received light amount sum R ₁ + R ₂ with respect to the emitted light amount (hereinafter simply referred to as the change rate of the received light amount sum R ₁ + R ₂ ) does not cause raindrops to adhere to the windshield 4. Compared to time (A), it decreases in (B) when raindrops are attached. This is because the amount of reflection by the regions D ₁ and D ₂ of the windshield 4 decreases due to the attachment of raindrops.

In FIG. 12, “●” indicates the received light amount R ₃ of the third optical path light receiving element 28 extracted in steps S51 and S52. In FIG. 12, “艟” indicates the ratio of the difference between the received light amounts R ₃ in steps S51 and S52 and the difference between the emitted light amounts T ₁ and T ₂ in steps S51 and S52, that is, the received light amount ₃ relative to the unit emitted light amount. Shows the rate of change. As can be seen from FIG. 12, the change rate 受 光 of the received light amount R ₃ with respect to the emitted light amount (hereinafter, simply referred to as the change rate of the received light amount R ₃ ) is as follows when there is no raindrops attached to the windshield 4 (A). There is no substantial change between (B) when raindrops are attached. This is because the reference light is directly guided to the third optical path light receiving element 28 without passing through the windshield 4.

As described above, the rate of change of the received light amount sum R ₁ + R ₂ varies depending on whether or not raindrops are attached to the windshield 4. Expected to be possible. However, since the rate of change of the received light amounts R ₁ and R ₂ represented by the detection signals of the first and second optical path light receiving elements 26 and 27 with respect to the emitted light amount varies depending on the ambient temperature, the change rate of the received light amount sum R ₁ + R ₂ It is not possible to accurately determine the attachment of raindrops simply by monitoring the data (here, equal to the sum of the rate of change of each of the received light amounts R ₁ and R ₂ with respect to the light emission amount). Accordingly, the inventors of the present invention are that the variation coefficients of the received light amounts R ₁ , R ₂ , and R ₃ represented by the detection signals of the light receiving elements 26 to 28 with respect to the ambient light temperature are substantially equal to each other. Then, the ratio of the change rate of the received light amount sum R ₁ + R ₂ and the change rate 受 光 of the received light amount R ₃ is taken and monitored. By taking a specific ratio / g, the coefficient of variation with respect to the ambient temperature of the rate of change with respect to the light emission amount for each value R ₁ , R ₂ , R ₃ is canceled, and the value 艟This is because the value of the specific ratio / g is not affected.

As described above, in step S53, the received light amounts R ₁ , R ₂ , and R ₃ stored in the RAM 36 in steps S51 and S52 are read, and the change rate of the received light amount sum R ₁ + R _{2 and} the received light amount R are read from these values. Calculate the change rate 艟 of ₃ . And further calculated change rate bets, and the current ratio C _R by calculating the ratio艟/ retrieved from艟. In step S54, it reads the stored ratio C _m as there is no reference set ratio艟/ DOO during deposition of raindrops to the windshield 4 from the ROM 35. The setting of the storage ratio C _m was performed the same processing as steps S51~S53 when the reference is thereby realized by storing in the ROM35 the calculated ratio艟/ DOO as a storage ratio C _m.

  Thereafter, in steps S55 and S56, the initial rain determination is completed by performing the same processing as in steps S14 and S15 of the initial rain determination according to the first embodiment.

According to the fourth embodiment as described above, in the initial rain determination, the ratio of changes in the received light amount sum R ₁ + R ₂ and the received light amount R ₃ and the dependence on the ambient temperature inherent in the trap are canceled. Since the raindrop adhesion determination is made based on /, the determination is accurate. Therefore, high determination accuracy can be achieved even immediately after the ignition switch 6 is turned on and the auto selection operation is performed at the wiper switch 12. Moreover, to obtain the ratio艟/ DOO upon reference attachment is not raindrops to the windshield 4, a light-emitting amount of the received light amount R _1, R _2, R ₃ of the light receiving elements 26 to 28 at least two points Just measure. Therefore, not only the time required for measuring each received light amount R ₁ , R ₂ , R ₃ at the reference time is shortened, but also the storage capacity of the RAM 36 can be reduced, so that the cost can be reduced.
The initial rain determination of the fourth embodiment described above corresponds to the initial rain determination of the first embodiment in the normal rain determination of the second embodiment and the initial rain determination and normal rain determination of the third embodiment. It is also possible to apply to.

(Fifth embodiment)
The raindrop detection device of the wiper automatic control device according to the fifth embodiment of the present invention has a structure as shown in FIGS.
In the raindrop detection apparatus 100 of the fifth embodiment, the first and second optical path light receiving elements 26 and 27 of the first embodiment are not mounted on the plate surface 42 of the substrate unit 40. Instead, the light receiving elements 110 arranged on the both sides of the virtual plane O are mounted on the plate surface 42. Therefore, hereinafter, the light receiving element 110 is referred to as a first light receiving element 110, and a light receiving element having the same configuration as the third optical path light receiving element 28 in the first embodiment is referred to as a second light receiving element 28. In the X direction from the one end 44 side to the other end 45 side of the substrate unit 40, the reflecting surface 54, the first collimating lens 52, the light emitting element 24, the second light receiving element 28, the second collimating lens 53, and the first light receiving element 110. Are in this order. As shown in FIG. 15, in the present embodiment, one first light receiving element 110 is connected to the detection / amplification circuit 29, and the other first light reception element 110 is connected to the detection / amplification circuit 30.

  As shown in FIGS. 13 and 14, the optical body 120 of the raindrop detection apparatus 100 includes first and second converging lenses 122 and 123 having configurations different from those of the first and second converging lenses 58 and 59 of the first embodiment. And a new reflecting surface 126 is provided. Therefore, in the following, the reflecting surface having the same configuration as the reflecting surface 54 of the first embodiment is referred to as the first reflecting surface 54, and the reflecting surface 126 is referred to as the second reflecting surface 126.

One first converging lens 122 is provided on each side of the virtual plane O. The first convergent lens 122 is a plano-convex lens in which the first light receiving element 110 on the same side with respect to the virtual plane O is located on the optical axis. The first converging lens 122 is located between the second collimating lens 53 and the first light receiving element 110 in the X direction, and the optical axis of the first converging lens 122 is about 45 with respect to the outer wall 9 of the windshield 4. -Inclined. The first condenser lens 122, after passing through sequentially the first collimator lens 52 and the first reflecting surface 54 of the same side of the virtual plane O, the first optical path L ₁ reflected by the outer wall 9 of the windshield 4 Of the reference light is incident through the prism 56. The first converging lens 122 guides the reference light of the first optical path L ₁ thus incident along the optical axis of the first converging lens 122 toward the first light receiving element 110 on the same side with respect to the virtual plane O. Here, the elliptical region D ₁ schematically shown in FIG. 16 is a region where the reference light in the first optical path L ₁ can be reflected on the outer wall 9 of the windshield 4 and guided to the first light receiving element 110. is there. When raindrops in this region D ₁ is attached, since the reflection amount of the reference light by the windshield 4 is decreased, the light receiving amount r ₁ of the first light receiving element 110 is changed. That is, the region D ₁ is a region where the first light receiving element 110 detects the attachment of raindrops using the reference light in the first optical path L ₁ , and is hereinafter referred to as a detection region D ₁ . In FIG. 16, a rectangular area S schematically shows a projection area of the raindrop detection device 100 onto the windshield 4.

One second converging lens 123 is provided on each side of the virtual plane O, and one second reflecting surface 126 is provided on both sides of the virtual plane O. The second reflecting surface 126 is substantially perpendicular to the outer wall 9 of the windshield 4 and the plate surface 42 of the substrate portion 40, and is positioned closer to the other end 45 side of the substrate portion 40 than the first light receiving element 110 in the X direction. is doing. The second reflecting surface 126 passes through the second collimating lens 53 on the same side with respect to the virtual plane O, and then the reference light of the second optical path L ₂ reflected by the outer wall 9 of the windshield 4 passes through the prism 56. Led. The second reflecting surface 126 reflects the reference light of the second optical path L ₂ thus guided toward the second converging lens 123 on the same side with respect to the virtual plane O.

The second converging lens 123 is a plano-convex lens in which the first light receiving element 110 and the second reflecting surface 126 on the same side with respect to the virtual plane O are located on the optical axis. The second converging lens 123 is positioned between the first light receiving element 110 and the second reflecting surface 126 in the X direction, and the optical axis of the first converging lens 122 is about 45 with respect to the outer wall 9 of the windshield 4. Inclined and inclined about 90 ° with respect to the optical axis of the first converging lens 122 on the same side with respect to the virtual plane O. Reference light of the second optical path L ₂ reflected by the second reflecting surface 126 on the same side with respect to the virtual plane O is incident on the second converging lens 123. The second converging lens 123 guides the reference light of the second optical path L ₂ thus incident along the optical axis of the second converging lens 123 toward the first light receiving element 110 on the same side with respect to the virtual plane O. Here, the oval region D ₂ schematically shown in FIG. 16 is a region where the reference light of the second optical path L ₂ can be reflected on the outer wall 9 of the windshield 4 and guided to the first light receiving element 110. There, in the present embodiment is configured so as not to overlap with the region D _1. When raindrops in this region D ₂ is attached, since the reflection amount of the reference light by the windshield 4 is decreased, the light receiving amount r ₁ of the first light receiving element 110 is changed. That is, the region D ₂ is a region where the first light receiving element 110 detects the attachment of raindrops using the reference light in the second optical path L ₂ , and is hereinafter referred to as a detection region D ₂ .

In such a wiper automatic control process of the fifth embodiment, the initial rain determination and the normal rain determination are performed according to the flowcharts shown in FIGS. 17 and 18, respectively.
First, in the initial rain determination of the fifth embodiment shown in FIG. 17, the light emitting elements 24 are caused to emit light sequentially in step S <b> 61, and the received light amounts r ₁ and r _{1 of} the first light receiving elements 110 and the second light receiving elements 28. The received light amount r ₂ is detected. At this time, the light emission control circuit 22 is supplied with a control signal for setting the sum of the light emission amounts of the respective light emitting elements 24 as a set value, and each of the detection / amplifier circuits 29 to 31 has a signal amplification factor as a set value. Gives a control signal for. As a result, when the detection signals of the first light receiving element 110 and the second light receiving element 28 are received from the detection / amplification circuits 29 to 31, the received light amounts r ₁ , r ₁ , r ₂ represented by the detection signals are extracted. Store in the RAM 36.

In steps S62 and S63 of the present embodiment, the sum of the received light amounts r ₁ and r ₁ of each first light receiving element 110 is based on the same principle as in the case of the ratio R ₃ / (R ₁ + R ₂ ) of the first embodiment. the ratio r ₂ / Mo r ₁ between the light-receiving amount r ₂ of r ₁ and the second light receiving element 28 is monitored. Specifically, in step S62, the received light amounts r ₁ , r ₁ , r ₂ of the first light receiving elements 110 and the second light receiving elements 28 stored in the RAM 36 in step S61 are read, and their values r ₁ , r ₁ , the current ratio C _R from r ₂ to calculate the ratio r ₂ / Mo r _1. In step S 63, the storage ratio C _m as the ratio r ₂ / _m r ₁ set at the reference time when no raindrops adhere to the windshield 4 is read from the ROM 35. The setting of the storage ratio C _m is realized by the reference implement the same processing as step S61, S62 during, stored in ROM35 of by ratio r ₂ / Mo r ₁ calculated by it as a storage ratio C _m Is done.
In steps S64 and S65, processing similar to that in steps S14 and S15 of the initial rain determination according to the first embodiment is performed.

In contrast to such initial rain determination, in the normal rain determination of the fifth embodiment shown in FIG. 18, the light emission control circuit 22 and the detection / amplification circuits 29 and 30 are controlled in step S <b> 71, whereby each of the light emitting elements 24. The light emission amount (sum) and the signal amplification factors of the detection / amplification circuits 29 and 30 are adjusted. In addition, step S71 of this embodiment is performed at the timing when there is no raindrop adhesion, such as immediately after a wiper passage, similarly to step S21 of the initial rain determination according to the first embodiment. Therefore, in step S71 of the present embodiment, the above adjustment is performed so that the received light amounts r ₁ and r ₁ represented by the detection signals of the first light receiving elements 110 become the reference values r _b1 and r _b1 , respectively. _b1 and _rb1 are set as the received light amount of each first light receiving element 110 at the reference time.

In step S72, the light emitting elements 24 are caused to emit light sequentially after a predetermined time delay or the like, and the received light amounts r ₁ and r ₁ of the first light receiving elements 110 are detected. At this time, the light emission amount (sum) of each light emitting element 24 and the signal amplification factors of the detection / amplification circuits 29 and 30 are respectively held at the values adjusted in step S71. As a result, when the detection signals of the first light receiving elements 110 are received from the detection / amplification circuits 29 and 30, respectively, the received light amounts r ₁ and r ₁ represented by the detection signals are extracted and stored in the RAM 36.

In step S73, a reference value r for the received light amount r _1, and Kazumo r ₁ of r _1, the first light receiving element 110 defined in step S71 in the first light receiving element 110 stored in Step S72 RAM 36 _The ratio {100−100 · (mo r ₁ ) / (mo r _b1 )}% obtained from the sum of _b1 and r _b1 is calculated as a reduction rate F.
In step S74, the same process as step S24 of the normal rain determination according to the first embodiment is performed.

As described above, each first light receiving element 110 corresponds to a “light receiving element” recited in the claims, and a set of the first light receiving elements 110 corresponds to a “light receiving portion” recited in the claims. The first reflecting surface 54 corresponds to the “reflecting portion” and “first reflecting portion” recited in the claims, and the second reflecting surface 126 corresponds to the “second reflecting portion” recited in the claims. Equivalent to. Furthermore, the storage ratio C _m read in the initial rain determination step S63 corresponds to the “reference ratio at reference time” recited in the claims, and the current ratio C _R calculated in the initial rain determination step S62 is This corresponds to the “attention ratio when detecting raindrops” described in the claims.

As described above, in the fifth embodiment, the dependency of the ambient temperature inherent in the received light amounts r ₁ , r ₁ , r ₂ of the first light receiving element 110 and the second light receiving element 28 is set to the ratio R ₃ / Similar to the case of (R ₁ + R ₂ ), the initial rain determination is performed based on the ratio r ₂ / m r ₁ that is canceled. Therefore, high determination accuracy can be achieved even immediately after the ignition switch 6 is turned on and the auto selection operation is performed at the wiper switch 12. Moreover, in order to obtain the ratio r ₂ / m r ₁ at a reference time when no raindrops are attached to the windshield 4, the received light amounts r ₁ , r ₁ , r of each of the first light receiving elements 110 and the second light receiving elements 28. _It is only necessary to measure ₂ for the amount of luminescence at least at one point. Therefore, cost can be reduced.
Also in the fifth embodiment, the normal rain determination following the initial rain determination of the wiper automatic control process can be realized with a smaller calculation processing amount than in the case of the initial rain determination, so that the determination time is shortened.

Further in the fifth embodiment, the outer wall 9 of the windshield 4 of the first optical path L ₁ of the reference light detection region D ₁ and the second optical path L ₂ of the reference light detection region D ₂ and is raindrop detection so as not to overlap each other Since the apparatus 100 is configured, high size efficiency can be realized. In addition, the raindrop detection apparatus 100 realizes the light receiving element whose detection target is the region D ₁ and the light receiving element whose detection target is the region D ₂ by the single light receiving element 110, thereby reducing the number of parts and the cost. Is done.

  Furthermore, in the fifth embodiment, in the raindrop detection apparatus 100, the optical body 120 formed by integrating the first and second reflecting surfaces 54, 126 and the reflecting light guide surface 60 with the prism 56 and the various lenses 52, 53, 122, 123 is provided. Is used. Therefore, the assemblability of the raindrop detection device 100 is improved as compared with the case where the first and second reflection surfaces 54 and 126 and the reflection light guide surface 60 are formed separately from the other elements of the optical body 120.

  In addition, in the fifth embodiment, the first and second reflecting surfaces 54 and 126 are disposed between the board portion 40 on which the various elements 24, 110 and 28 are mounted in the raindrop detection apparatus 100 and the windshield 4 substantially parallel thereto. The optical body 50 including the reflective light guide surface 60 is disposed. Thereby, since the physique of the raindrop detection apparatus 100 becomes small in the opposing direction of the board | substrate part 40 and the windshield 4, an improvement in size efficiency can be achieved without deteriorating a driver | operator's visual field.

19 and 20 show a modification of the fifth embodiment. In this modified example, only one first light receiving element 110 is disposed on the virtual plane O, and the first and second converging lenses 122 and 123 are configured by a single plano-convex lens straddling both sides of the virtual plane O. The two reflecting surfaces 126 are formed so as to straddle both sides of the virtual plane O. In such a fifth embodiment, in the initial rain determination and the normal rain determination of the wiper automatic control process, the contents regarding the received light amounts r ₁ and r ₁ of each first light receiving element 110 are set as the received light amount of one first light receiving element 110. By changing to the contents related to r ₁ , the same effect as that of the fifth embodiment can be enjoyed.

Further, in the fifth embodiment (including the above modification), the normal rain determination may be changed to the same processing content as the initial rain determination in accordance with the second embodiment, or the normal according to the third embodiment. The rain determination may be performed instead of the normal rain determination.
Furthermore, in the fifth embodiment (including the above-described modification), the initial rain determination according to the fourth embodiment may be performed instead of the initial rain determination. In this case, the change rate with respect to the unit light emission amount of the sum of the received light amounts r ₁ and r ₁ of the first light receiving elements 110 is used as the change rate.

In addition, in the first to fifth embodiments, at least one of the reflective light guide surface 60, the (first) reflective surface 54, and the second reflective surface 126 is formed separately from the optical bodies 50 and 120. It may be. In the first to fifth embodiments, the light receiving element 28 is disposed at the position where the reflective light guide surface 60 is disposed, and the reference light in the third optical path L ₃ is directly transmitted from the light emitting element 24 by the light receiving element 28. You may make it receive.

2 Wiper automatic control device, 4 Windshield, 5 Wiper, 6 Ignition switch, 8 Inner wall, 9 Outer wall, 10 Wiper drive device (drive means), 12 Wiper switch, 14 Wiper motor drive circuit, 16 Wiper motor, 20, 100 Raindrop detection device , 22 Light emission control circuit, 24 Light emitting element, 26 First optical path light receiving element, 27 Second optical path light receiving element, 28 Third optical path light receiving element, Second light receiving element, 29, 30, 31 Each detection / amplification circuit, 32 CPU, 34 storage unit, 35 ROM, 36 RAM, 40 substrate unit, 44 one end, 45 other end, 50, 120 optical body, 52 first collimating lens, 53 second collimating lens, 54 reflecting surface / first reflecting surface, 56 prism 58, 122 First convergent lens, 59, 123 Second convergent lens, 60 Reflective light guide surface, 10 1st light receiving element, 126 2nd reflective surface

Claims (10)

A raindrop detection device for detecting raindrops adhering to a windshield,
A light emitting element that emits reference light;
A reflecting portion that reflects the reference light toward the windshield;
After being guided to the windshield by the first optical path passing through the reflecting portion, and after being guided to the windshield by the second light path not passing through the reflecting portion, the reference light reflected by the windshield, A light receiving unit that receives the reference light reflected by the windshield;
Determination means for determining the attachment of raindrops to the windshield based on the amount of light received by the light receiving unit;
A raindrop detection apparatus comprising:   The light receiving unit receives a first optical path light receiving element that receives the reference light of the first optical path reflected by the windshield, and a second optical path light reception that receives the reference light of the second optical path reflected by the windshield. The raindrop detection device according to claim 1, further comprising an element. An optical body for allowing the reference light to enter the windshield from the inner wall side of the windshield;
The raindrop detection apparatus according to claim 2, wherein the reflection unit is formed on the optical body. Provided substantially parallel to the windshield, comprising a substrate portion on which the light emitting element, the first optical path light receiving element and the second optical path light receiving element are mounted;
The raindrop detection device according to claim 2, wherein the reflection portion is provided between the substrate portion and the windshield.   The reflection part, the light emitting element, the first optical path light receiving element, and the second optical path light receiving element are arranged in this order in a direction from one end side to the other end side of the substrate part. Item 5. The raindrop detection device according to Item 4. The second reflection unit that includes the reflection unit as the first reflection unit and reflects the reference light of the second optical path reflected by the windshield,
The light receiving unit includes a light receiving element that receives the reference light of the first optical path reflected by the windshield and the reference light of the second optical path sequentially reflected by the windshield and the second reflecting part. The raindrop detection device according to claim 1, further comprising: An optical body for allowing the reference light to enter the windshield from the inner wall side of the windshield;
The raindrop detection apparatus according to claim 6, wherein the first reflection part and the second reflection part are formed on the optical body. Provided substantially parallel to the windshield, comprising a substrate portion on which the light emitting element and the light receiving element are mounted;
The raindrop detection device according to claim 6, wherein the first reflecting portion and the second reflecting portion are provided between the substrate portion and the windshield.   16. The first reflecting portion, the light emitting element, the light receiving element, and the second reflecting portion are arranged in this order in a direction from one end side to the other end side of the substrate portion. The raindrop detection device described in 1. The raindrop detection device according to any one of claims 1 to 9,
Drive means for driving a wiper for wiping the windshield when the determination means determines that raindrops are attached;
A wiper automatic control device comprising:

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