JPH10318912A - Liquid drop detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid drop detector capable of improving detection sensitivity at the time of e.g. detecting rain drops in contact with the surface of the windshield of a vehicle and detecting fogging which occurs on its back surface. SOLUTION: For detecting liquid drops in contact with the surface 12 and back surface 13 of the windshield 11, a liquid drop detector 10 comprises a light emitting part 30, a surface light-guiding part 50 to reflect detection light to a surface detection part A, a back surface light-guiding part 60 to reflect detection light to a back surface detection part B, and a light receiving part 40 to receive detection light oncoming from the surface light-guiding part A and back surface light-guiding part B and to output signals based on the intensity of the received light. Here, the light emitting part 30 and light receiving part 40 are integrally rotated about a line along the width of the windshield 11 so that the surface light-guiding part A and back surface light-guiding part B may move along arcs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid drop detecting device, and more particularly to a liquid drop detecting device capable of detecting raindrops attached to the surface of a windshield of an automobile and detecting cloudiness generated on the rear surface.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a raindrop detecting device for detecting the presence or absence of raindrops adhering to a windshield in order to automatically start / stop a windshield wiper of an automobile or adjust intermittent operation. ing. The raindrop detecting device includes, for example, a light emitting unit that emits predetermined detection light, a light receiving unit that receives the detection light and outputs a signal based on the light receiving intensity, and a light guide plate that can guide the detection light. There is known a raindrop detecting device arranged on the back surface side (vehicle compartment side) of a shield.

The light emitting section has a light emitting element such as a near infrared light emitting diode, and the light receiving section has a light receiving element such as a near infrared photodiode. On the other hand, the light guide plate is capable of transmitting the detection light, is arranged so as to be in surface contact with the back surface of the window shield, and guides the detection light to a point-like surface detection unit set on the surface of the window shield. The light is guided so as to be totally reflected, and then to emit the detection light toward the light receiving unit. According to such a raindrop detecting device, when raindrops adhere to the surface detecting portion of the windshield, the detection light is not totally reflected by the surface detecting portion, so that the output signal of the light receiving portion changes. , The start / stop or intermittent operation adjustment can be automated.

In this raindrop detecting device, the detection light is reflected by a point-like back surface detecting portion set on the back surface of the window shield and is received by the light receiving portion to detect cloudiness generated on the back surface of the window shield. It can be applied as a fogging detection device. Accordingly, a light guide plate attached to the back surface of the window shield is formed with a front light guide portion capable of guiding the detection light to the front surface detection portion and a back light guide portion capable of guiding the detection light to the back surface detection portion. In addition, a droplet detecting device capable of individually detecting raindrops adhering to the surface of the window shield and clouding generated on the back surface of the window shield can be considered.

[0005]

By the way, in the above-mentioned liquid drop detecting device, since the front surface detecting portion and the back surface detecting portion are extremely narrow and fixed point-like, it is necessary to keep raindrops or cloudy over the wide area of the window shield. There is a problem that the light receiving intensity of the light receiving unit does not change and the detection sensitivity is low.
The present invention has been made in view of the above-mentioned problems, and its object is to detect the raindrops attached to the surface of a windshield of an automobile and to detect the cloudiness generated on the back side, for example, to increase the detection sensitivity. An object of the present invention is to provide a droplet detecting device that can be improved.

[0006]

According to a first aspect of the present invention, there is provided a method for detecting droplets attached to a front surface and a rear surface of a transparent body formed in a plate shape. A light emitting unit that emits detection light at a predetermined crossing angle, a surface light guide unit that emits the detection light from the back surface after reflecting the detection light to a surface detection unit set on the front surface, and the detection light A back surface light guide that reflects to a back surface detection unit set on the back surface; and a light receiving device that receives the detection light emitted from the front surface light guide and the back surface light guide and outputs a signal based on the intensity of the received light. The light emitting unit and the light receiving unit are integrally rotatable about a line along the thickness direction of the transparent body so that the front surface detecting unit and the back surface detecting unit draw an arc-shaped locus. Droplet detection device characterized by the following: More it can be solved.

Here, a structure having a light emitting element such as a near-infrared light emitting diode can be adopted as the light emitting section, and a structure having a light receiving element such as a near infrared photodiode can be adopted as the light receiving section. The light emitting unit and the light receiving unit may be arranged so that the light emitting axis of the light emitting element and the light receiving axis of the light receiving element intersect at a predetermined angle with respect to the back surface of the transparent body such as a window shield. If the light emitting axis or the light receiving axis can be bent by bending means such as an optical fiber or a reflecting mirror disposed at a predetermined position, the arrangement of the light emitting element and the light receiving element is arbitrary.

The surface light guide may be any light guide capable of guiding detection light to the surface detector and light guide to the light detector reflected by the surface detector. A light guide plate having a shape can be adopted. When such a light guide plate is provided with a plurality of surface detectors on the surface of the transparent body, an incident contact surface for allowing the detection light to enter the transparent body so that the detection light can be repeatedly reflected inside the transparent body. ,
What is necessary is just to provide a step part separated from the see-through body between the see-through body and the emission contact surface for emitting the detection light. The step includes a depression and a through hole provided in the light guide plate. Therefore, the light guide plate of the front light guide section may be formed in a ring shape or a substantially concave cross section. In addition, the surface light guide includes, for example, a groove having a substantially V-shaped cross section formed in a ring shape along the back surface of the transparent body.

On the other hand, in the case where the back surface light guiding portion has only one back surface detecting portion, the light emitting portion can directly project the detecting light to the back surface detecting portion and the light receiving portion detects the detecting light reflected from the back surface detecting portion. If light can be directly received, there is no need to use a separate light guide plate or the like. However, in the case where a plurality of back surface detection units are set as the back surface light guide unit in the present invention, a flat surface that is separated in parallel with the back surface of the transparent body is provided, and the detection light is repeatedly reflected on the back surface and the flat surface. Structure can be adopted. Such a flat surface may be connected to the above-described surface light guide. When a lid-like light guide plate that partially covers the rear surface of the transparent body is used to provide a flat surface in the rear light guide unit, it is desirable that the inside and outside of the light guide plate can be ventilated.

In the present invention, the rotating shaft of the driving means such as a motor may be arranged along the thickness direction of the transparent body, and the light emitting unit and the light receiving unit may be fixed to the driving shaft. The rotation axis may be arranged at the center between the light emitting unit and the light receiving unit, or may be arranged at a position eccentric to the light emitting unit and the light receiving unit. In these cases, the front surface light guide portion and the rear surface light guide portion may move by drawing a continuous circular locus, or may move by drawing a circular locus at a predetermined interval as shown by a broken line. Then, the front surface light guide portion and the rear surface light guide portion may have the same locus radius, or may have different locus radii.

[0011] In the liquid drop detecting device configured as described above, for example, raindrops adhered to the front surface of the windshield and generated on the rear surface by the front surface detecting unit and the rear surface detecting unit respectively set on the front surface and the rear surface of the transparent body. Cloudiness can be detected at the same time. In this droplet detecting device, the light emitting unit and the light receiving unit rotate integrally about a line along the thickness direction of the transparent body so that the front surface detecting unit and the back surface detecting unit draw an arc-shaped locus. Therefore, the detection sensitivity of the droplet can be improved as compared with the case where the front surface detection unit and the back surface detection unit are fixed dot-shaped.

Further, according to the present invention, a substantially disk-shaped light guide plate attached along the back surface is provided, and the front surface light guide portion and the back surface light guide portion are provided with the light guide plate. The light emitting unit and the light receiving unit are provided on the light plate, and the light emitting unit and the light receiving unit are symmetrically arranged on the outer peripheral side along the radial direction of the light guide plate, and the rotation center of the light emitting unit and the light receiving unit is along the axis of the light guide plate. May be arranged.

Here, as the light guide plate, a ring-shaped contact portion capable of making surface contact with the back surface of the transparent body, and a flat surface which covers the hollow portion of the contact portion and is spaced apart in parallel with the back surface of the transparent body. It may be formed in a substantially concave cross section having a surface. This light guide plate may be colored or not, as long as it is an appropriate material that can transmit the detection light. In such a light guide plate, the front surface light guide unit guides the detection light to the surface detection unit via the contact unit, and emits the detection light to the outside via the contact unit, and the back surface light guide unit includes The detection light is repeatedly reflected on the flat surface and the back surface of the transparent body.

The front surface light guide portion and the back surface light guide portion are configured such that the front surface detection portion and the back surface detection portion move alternately at predetermined intervals in an arc-shaped locus, in other words, a dashed circular locus. Are alternately drawn along the radial direction of the light guide plate so as to move alternately, and the incident position and the emission position with respect to the light guide plate are set on the same circle along the peripheral surface of the light guide plate. May be.

The front surface light guide and the back surface light guide are stacked and arranged along the axis of the light guide plate so that the surface detector and the back surface detector move along a concentric trajectory. Alternatively, the incident position and the outgoing position with respect to the light guide plate may be set on parallel lines along the peripheral surface of the light guide plate. In this case, one set of the light emitting unit and one set of the light receiving unit are required for the front light guide unit and the back light guide unit. In this case, the rotation speeds of the light emitting unit and the light receiving unit of the front surface light guiding unit and the rotation speeds of the light emitting unit and the light receiving unit of the rear surface light guiding unit may be the same or different from each other. You may.

In the thus configured liquid drop detecting device, the light emitting portion and the light receiving portion are symmetrically arranged on the outer peripheral side along the radial direction of the light guide plate, and are rotatable about the axis of the light guide plate. Therefore, the overall shape can be reduced in size, the load on the driving means such as a motor can be reduced, and vibrations due to rotation can be reduced.

Further, according to the present invention, the front light guide portion and the rear light guide portion are provided so as to extend along the radial direction of the light guide plate and intersect with each other. The incident position and the output position of the detection light may be set on the same circle along the peripheral surface of the light guide plate. Therefore, the front surface detection unit and the back surface detection unit alternately draw arc-shaped trajectories at predetermined intervals, in other words, alternately draw dashed circular trajectories and move.

In the liquid drop detecting device thus configured, since the incident position and the output position of the detection light with respect to the light guide plate are set on the same circle along the peripheral surface, the light emitting portion of the surface light guide portion, The light receiving section, the light emitting section and the light receiving section of the rear light guide section can be shared. Therefore, in this droplet detecting device, the number of components can be reduced as compared with a case where the light emitting unit and the light receiving unit for detecting the liquid droplets attached to the front surface and the rear surface of the transparent body are separately prepared. The cost of parts can be reduced, the rotating mass can be reduced, and the load on driving means such as a motor can be further reduced.

Further, in the present invention, as set forth in claim 4, the front surface light guiding portion may have a plate-like silicon gel, and the silicon gel may be in surface contact with the back surface.
Here, as the silicone gel, it is only necessary that the silicon gel can transmit the detection light and that it can be brought into surface contact with the contact surface and the back surface of the see-through member so that air bubbles and the like are not mixed. You can choose any. In the liquid droplet detection device configured as described above, since the surface light guide section has the silicon gel, the detection light can be reliably guided toward the surface detection section, and the detection light reflected by the surface detection section can be detected. Light can be reliably emitted to the outside of the light guide plate.

According to a fifth aspect of the present invention, in order to repeatedly reflect the detection light on the front surface, the surface light guide has a stepped portion separated from the rear surface. For example, a depression, a through hole, or the like may be provided between the incident contact surface and the outgoing contact surface. Here, for example, if a pair of surface detection units is set and the rotation centers of the light emitting unit and the light receiving unit are set at the center between the surface detection units, each surface detection unit moves along the same circle. On the other hand, if the rotation centers of the light emitting unit and the light receiving unit are set at positions eccentric with respect to each surface detecting unit, each surface detecting unit moves while drawing a concentric double circular locus.

That is, in the liquid droplet detecting device having such a configuration, since a plurality of surface detecting portions are set, compared to the case where only one surface detecting portion is provided, the liquid droplets adhering to the surface of the transparent body are compared. Detection sensitivity can be improved. In addition, in this droplet detection device, since a plurality of surface detection units are set, at least one surface detection unit can move along an arc-shaped trajectory regardless of the position of the rotation center of the light emitting unit and the light receiving unit. Becomes That is, in this droplet detecting device, the rotation center of the light emitting unit and the light receiving unit can be arbitrarily selected, so that the degree of freedom in design increases.

Further, according to the present invention, in order to repeatedly reflect the detection light with respect to the back surface, the back surface light guide portion is spaced apart from the back surface and is parallel to the back surface. It may have a surface. In such a droplet detection device, since a plurality of back surface detection units are set,
As compared with the case where the number of the back surface detection unit is one, the detection sensitivity of the droplet attached to the back surface of the transparent body can be improved. In addition, in this droplet detection device, since a plurality of back surface detection units are set, at least one back surface detection unit can move along an arc-shaped locus regardless of the position of the rotation center of the light emitting unit and the light receiving unit. Becomes That is, in this droplet detection device, since the rotation center of the light emitting unit and the light receiving unit can be arbitrarily selected,
The degree of freedom in design increases.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an exploded perspective view showing a first embodiment of a droplet detecting device according to the present invention, FIG. 2 is a cross-sectional view showing the operation of a front light guide section and a rear light guide section, and FIG. It is an exploded perspective view showing a shape and a relative position.

As shown in FIGS. 1 and 2, the droplet detecting device 10 in this embodiment detects raindrops adhering to a surface 12 (outside surface of the vehicle: upper surface in the figure) of a windshield 11 constituting an automobile. At the same time, it is for detecting cloudiness generated on the back surface 13 (the surface on the vehicle compartment side: the lower surface in the figure).
The droplet detecting device 10 includes a substantially disc-shaped light guide plate 20 attached to the back surface 13 of the window shield 11, and a light emitting unit 30 and a light receiving unit symmetrically arranged on the outer peripheral side along the radial direction of the light guide plate 20. 40 and has. And this droplet detecting device 10
The front light guide section 50 and the rear light guide section 60 are arranged crosswise along the radial direction of the light guide plate 20, and the light emitting section 30 and the light receiving section 40 rotate integrally about the axis of the light guide plate 20. It is possible.

The light guide plate 20 is made of a suitable synthetic resin having a light-transmitting property, has a smooth spherical surface along one edge 21, and has a flange 22 along the other edge. It is integrally molded. Such a light guide plate 20 is provided on the back surface of the window shield 11 through a translucent silicone gel 23.
The cover 13 is attached so as to be in partial surface contact with the cover 13 and is shielded by a cover 70 connected to the periphery of the flange portion 22 so that light from the vehicle compartment side does not enter.
The cover 70 is formed in a cylindrical shape with a bottom, and a plurality of through holes 71 are provided on the peripheral surface thereof at predetermined intervals along the circumferential direction. Inside the cover 70, the light emitting unit 30 and the light receiving unit 40
There is provided a driving means 80 for integrally rotating the motors.

The driving means 80 includes a disk-shaped support member 81 disposed parallel to the bottom of the cover 70, a motor 82 fixed to the support member 81 (shown only in FIG. 2), and a diameter of the support member 81. And a substantially prismatic rotating member 84 that is arranged along the direction and connected to the rotating shaft 83 of the motor 82. As shown in FIG. 2, the driving means 80
Printed wiring provided concentrically along the support member 81
81A to 81D and terminals 84 provided on the rotating member 84 so as to individually contact the printed wirings 81A to 81D.
A to 84D. Here, the rotating member 84 is a terminal
84A and 84B contact the printed wirings 81A and 81B, respectively, and the terminals 84C and 84D respectively correspond to the printed wirings 81C and 81C.
It is rotatable while in contact with 81D.

In the light emitting section 30, a light emitting element 31 such as a near-infrared light emitting diode provided at one longitudinal end of the frame 63 is always supplied with power by terminals 64A and 64B. On the other hand, the light receiving section 40 is configured such that a light receiving element 41 such as a near-infrared photodiode provided at the other end in the longitudinal direction of the frame 63 is always supplied with power by terminals 64C and 64D, and outputs a signal based on the light receiving intensity of the light receiving element 41. It is supposed to.

The light emitting section 30 and the light receiving section 40 are oriented such that the light emitting axis of the light emitting element 31 and the light receiving axis of the light receiving element 41 intersect at an equal angle on an extension of the rotating shaft 63 of the motor 62. . Further, the light emitting unit 30 and the light receiving unit 40
Is an incident position where the detection light 14 is incident on the light guide plate 20 or an emission position where the detection light 14 is emitted from the light guide plate 20 is spherical.
It is set on the same circle along 21.

As shown in FIG. 2A, the surface light guide 50
Are a pair of contact surfaces 51 that are in surface contact with the back surface 13 of the window shield 11 via the silicon gel 23, and these contact surfaces 51
And a step 52 provided therebetween. The contact surface 51 allows the detection light 14 transmitted through the light guide plate 20 to be incident from the back surface 13 of the window shield 11 to guide the detection light 14 to the surface detection unit A set on the front surface 12 and to detect the detection light reflected by the surface detection unit A. 14 through the light guide plate 20 and the light receiving element 41 of the light receiving section 40 from the edge 21.
The light is emitted toward. On the other hand, step 52
Is provided at the center of the light guide plate 20 and is separated from the back surface 13 of the window shield 11 by a predetermined distance so that the detection light 14 is not emitted from the back surface 13 of the window shield 11 corresponding to the portion. .

In such a surface light guide section 50, if no raindrops adhere to the surface detection section A, the detection light 14 transmitted through the light guide plate 20 and incident from the back surface 13 of the window shield 11
Is a windshield after total reflection on the surface detection section A.
The light is totally reflected by the back surface 13 of the light guide 11, is totally reflected again by the surface detecting portion A, passes through the light guide plate 20, exits from the edge 21, and is received by the light receiving element 41.

The front light guide 50 is provided on the back surface of the window shield 11 as shown by a two-dot chain line in FIG.
Aluminum plate 53 at the position where detection light 14 is reflected in 13
May be arranged. That is, even though raindrops are not attached to the front surface 12 of the windshield 11, if the rear surface 13 of the windshield 11 becomes cloudy, a part of the detection light 14 is caused by the cloudiness, And the light receiving intensity of the light receiving unit 40 may change. Here, if the aluminum plate 53 is arranged at the position, the light receiving intensity of the light receiving unit 40 is increased only by the raindrops purely attached to the surface detection unit A, regardless of whether it is generated on the back surface 13 of the windshield 11. Therefore, the accuracy of raindrop detection can be improved.

As shown in FIG. 2B, the back surface light guide section 60 includes a flat surface 61 spaced from and parallel to the back surface 13 of the window shield 11 and a transmission surface adjacent to the flat surface 61. 62. The flat surface 61 is a part of the step 52 described above, and is provided with a plurality of communication holes 63 communicating between the inside and the outside of the light guide plate 20 (see FIG. 2A). Therefore, the humidity between the back surface 13 and the flat surface 61 of the window shield 11 is maintained equal to the humidity in the vehicle compartment through the communication holes 63 and the through holes 71 provided in the cover 70. The transmission surface 62
Means that the detection light 14 transmitted through the light guide plate 20 is
11 can be emitted between the back surface 13 of the window shield 11 and the flat surface 61, and the detection light 14
It is appropriately arranged at an angle such that light can enter the light guide plate 20 from between the light guide plate 61 and the light guide plate 61.

In such a back surface light guide section 60, if no clouding occurs in the back surface detection section B, the detection 14 transmitted through the light guide plate 20 and emitted from the transmission surface 62 becomes the back surface detection section B and the flat surface 61. The light is reflected repeatedly and alternately with respect to
Light entering the light guide plate 20 from 62, exiting from the edge 21 and receiving light
Received at 41.

As shown in FIG. 3, these surface light guides
A plurality of the light guide portions 50 and the rear surface light guide portion 60 are provided so as to cross each other at an angle of 45 degrees along the radial direction of the light guide plate 20. The silicon gel 23 is also provided with a substantially spline-shaped hollow portion 24 corresponding to the light guide plate 20. Therefore, as shown in FIG. 2B, the front surface detection unit A and the back surface detection unit B are arranged such that the light emitting unit 30 and the light receiving unit 40 are arranged in the thickness direction of the window shield 11 around the axis of the light guide plate 20. By rotating integrally along the line along the line, the rotating movement is performed by alternately drawing arc-shaped concentric trajectories at 45-degree intervals.

According to the above-described droplet detecting device 10, the raindrop and the back surface attached to the front surface 12 of the windshield 11 are
The cloudiness generated in 13 can be detected at the same time. In the droplet detecting device 10, the light emitting unit 30 and the light receiving unit 40 rotate integrally about a line along the thickness direction of the window shield 11, so that the front surface detecting unit A and the back surface detecting unit B are rotated. Because it rotates and moves so as to draw an arc-shaped trajectory,
Compared to the case where the front surface detection unit A and the back surface detection unit B are fixed dot shapes, the detection sensitivity of raindrops or cloudiness can be improved.

Further, according to the droplet detecting device 10, the light emitting unit 30 and the light receiving unit 40 are symmetrically arranged on the outer peripheral side along the radial direction of the light guide plate 20 and rotate about the axis of the light guide plate 20. Accordingly, the overall shape can be reduced in size, the load on the driving means such as a motor can be reduced, and vibrations due to rotation can be reduced.

Further, in the above-described embodiment, since the front surface detecting unit A and the back surface detecting unit B rotate while alternately drawing arc-shaped concentric trajectories, the respective light emitting units 30 and light receiving units
40 can be standardized. Therefore, according to the droplet detecting device 10, in order to detect raindrops attached to the front surface 12 of the windshield 11 and cloudiness generated on the rear surface 13, the light emitting unit and the light receiving unit are separately prepared compared to the case where the light emitting unit and the light receiving unit are separately prepared The number of parts can be reduced, which reduces the cost of parts and
The rotating mass can be reduced, and the load on driving means such as a motor can be further reduced.

Further, since the light guide plate 20 is attached to the window shield 11 via the silicon gel 23, the surface light guide unit 50 can guide the detection light 14 toward the surface detection unit A without fail. The detection light 14 reflected by the detection unit A can be reliably emitted to the outside of the light guide plate 20.

According to the droplet detecting device 10, since a plurality of surface detecting portions A are set, the surface detecting portions A adhere to the surface 12 of the window shield 11 as compared with the case where only one surface detecting portion A is provided. The detection sensitivity of raindrops can be improved. Moreover,
Since a plurality of surface detection units A are set, at least one surface detection unit A moves along an arc-shaped trajectory regardless of the position of the rotation center of the light emitting unit 30 and the light receiving unit 40. Therefore, in this droplet detecting device 10, the light emitting section 30
In addition, since the rotation center of the light receiving unit 40 can be arbitrarily selected, there is also an effect that there are few restrictions on design.

Further, according to such a droplet detecting device 10, since a plurality of back surface detecting portions B are also set, as described above, the windshield 11 is compared with the case where only one back surface detecting portion is provided. In addition to improving the sensitivity of detecting cloudiness that occurs on the back surface 13 of the first embodiment, the effect of reducing design restrictions can be obtained.

It should be noted that the droplet detecting device of the present invention is not limited to the embodiment described above, but can be appropriately modified and improved. For example, the droplet detection device of the present invention includes:
In the above-described embodiment, the vehicle is mounted on the window shield of the vehicle, but may be mounted on the rear window, side window, glass roof, or the like of the vehicle. Further, the droplet detecting device of the present invention is not only applicable to automobiles, but also applicable to ships, railways, various flying objects, houses, and the like, and is also assumed to be applied to various experimental facilities.

[0042]

As described above, according to the first aspect of the present invention, the front surface detection unit and the back surface detection unit move so as to draw an arc-shaped trajectory. The detection sensitivity of the droplet can be improved as compared with the case where the detection unit has a fixed point shape. According to the droplet detecting device of the second aspect, the light emitting portion and the light receiving portion symmetrically arranged on the outer peripheral side along the radial direction of the light guide plate rotate about the axis of the light guide plate, so that the overall shape is increased. Can be reduced in size, the load on driving means such as a motor can be reduced, and vibrations and the like due to rotation can be reduced.

Furthermore, according to the droplet detecting device of the third aspect, the number of components can be reduced as compared with a case where a light emitting unit and a light receiving unit for detecting the front and back of the transparent body are separately prepared. This can reduce component costs,
The rotating mass can be reduced, and the load on driving means such as a motor can be further reduced. According to the droplet detecting device described in claim 4, since the light guide plate is attached to the transparent body via the silicone gel, the detection light can be surely guided toward the surface detection unit, and The detection light reflected by the detection unit can be reliably emitted to the outside of the light guide plate.

According to the fifth aspect of the present invention, since the front surface light guide has the step portion separated from the back surface, a plurality of front surface detection portions can be set, and the front surface detection portion can be set. Compared with the case where there is only one part, the detection sensitivity of the droplet adhering to the surface of the transparent body can be improved, and the degree of freedom in design increases. According to the droplet detecting device described in claim 6, since the back surface light guide has a flat surface parallel to and spaced from the back surface, a plurality of back surface detection units can be set, and the transparent body can be set. The detection sensitivity of the liquid droplets attached to the back surface can be improved, and the degree of freedom in design increases.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a droplet detecting device according to the present invention.

FIG. 2 is a cross-sectional view showing the operation of a front light guide and a rear light guide.

FIG. 3 is an exploded perspective view showing an embodiment of a droplet detecting device according to the present invention.

[Explanation of symbols]

 10 Droplet detector 11 Windshield (transparent body) 12 Front surface 13 Back surface 14 Detection light 20 Light guide plate 23 Silicon gel 30 Light emitting unit 40 Light receiving unit 50 Front light guide unit 52 Step unit 60 Back light guide unit 61 Flat surface A Surface detection Part B Back side detection part

Claims (6)

[Claims] 1. A light emitting unit which emits detection light at a predetermined intersection angle toward the back surface to detect droplets attached to the front and back surfaces of a plate-shaped transparent body, and the detection light After reflecting on the surface detection unit set on the surface,
A front surface light guide that emits from the back surface, a back surface light guide that reflects the detection light to a back surface detection unit set on the back surface, and the detection light that emits from the front surface light guide and the back surface light guide. And a light-receiving unit that outputs a signal based on the light-receiving intensity thereof, and the light-emitting unit and the light-receiving unit are arranged so that the front-surface detection unit and the back-surface detection unit draw an arc-shaped locus. A droplet detecting device, which is integrally rotatable about a line along a thickness direction of a body. 2. A light guide plate having a substantially disk shape attached along the back surface, wherein the front surface light guide portion and the back surface light guide portion are provided on the light guide plate, and the light emitting portion and the light guide portion are provided. 2. A light receiving unit is symmetrically arranged on an outer peripheral side along a radial direction of the light guide plate, and a rotation center of the light emitting unit and the light receiving unit is arranged along an axis of the light guide plate. 2. A droplet detection device according to item 1. 3. The light guide plate according to claim 1, wherein the front light guide portion and the rear light guide portion are provided along the radial direction of the light guide plate and intersect with each other, and the incident position and the emission position of the detection light are respectively set to the light guide plate. 3. The droplet detecting device according to claim 2, wherein the droplet detecting device is set on the same circle along a peripheral surface of the droplet detecting device. 4. The droplet detecting device according to claim 2, wherein the front light guide has a plate-like silicon gel, and the silicon gel is capable of making surface contact with the back surface. 5. The light guide according to claim 4, wherein the front surface light guide has a step portion separated from the back surface so as to repeatedly reflect the detection light on the front surface. Droplet detection device. 6. The light guide section according to claim 1, wherein the light guide section has a flat surface that is separated from and parallel to the rear surface so that the detection light is reflected repeatedly on the rear surface. 2. The droplet detection device according to 2.