JPS59132337A - Liquid detector for automatic wind shield wiper control device - Google Patents

Abstract

PURPOSE:To make a detector compact, by receiving the light emitted from a wind shield by one of a plurality of light receiving elements, and making the result to be a detected signal required for the automatic control of wind shield wipers. CONSTITUTION:A single light emitting element 22 and a plurality of light receiving elements 23 and 24 are provided. When liquid such as rain drops is not attached to the outer surface of a wind shield (hereinafter called shield) 10, the light from the light emitting element 22 is inputted into the shield 10 so that the light is totally reflected in the shield 10. When the liquid is attached, the amount of light reflected in the shield 10 is reduced. The emitted light after the reflection in the shield 10 is received by at least one of a plurality of the light receiving elements 23 and 24. Based on the result of light receiving, a detected signal required for the automatic control of wind shield wipers 11 and 12 is generated.

Description

[Detailed Description of the Invention] The present invention relates to a windshield wiper automatic control device,
In particular, a windshield wiper automatic control device suitable for being provided on a part of the inner surface of the windshield corresponding to the sliding area on the outer surface of the windshield of a wiper blade constituting the windshield wiper of a vehicle, aircraft, ship, etc. Regarding liquid detectors.

Conventionally, this type of liquid detector has, for example, a single light-emitting element and a single light-receiving element, and when there is no liquid such as raindrops attached to the outer surface of the windshield, the light-emitting element The generated light is incident on the windshield so as to be totally reflected within the windshield, and the amount of light reflected within the windshield is reduced when the amount of liquid is present, and the windshield There is a device in which the light emitted from the windshield wiper after reflection is received by the light receiving element, and the result of this light reception is generated as a detection signal necessary for automatic control of the windshield wiper.

However, in such a configuration, a detection area on the outer surface of the windshield for the attached liquid is limited to a reflection point on the outer surface of the windshield of light passing through the optical path between the light emitting element and the light receiving element. As a result, even though the adhered liquid is present, it cannot be detected, resulting in a problem that accurate automatic control of the windshield wiper cannot be performed. As a countermeasure to the problem of bending, it is possible to increase the number of reflections of light within the windshield, but in this case, as the distance between the light emitting element and the light receiving element becomes longer, the light inside the windshield increases. The S/N of the detection signal is extremely reduced due to the absorption of . It is also possible to configure the liquid detector to have multiple pairs of each single light emitting element and light receiving element, but in this case, the size and shape of the liquid detector will increase and the cost will increase. becomes.

The present invention was made in response to these problems, and its purpose is to provide a liquid detector for an automatic windshield wiper control device, which is provided with a single light emitting element and a plurality of light receiving elements. It is about providing.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.
In the figure, numeral 10 indicates a windshield of a vehicle, ship, aircraft, etc., and both numerals 11 and 12 indicate wiper blades of an electric parallel interlocking type windshield wiper.
is the wiper motor 16 of the windshield wiper (
4), it slides repeatedly on the fan-shaped wiping areas 11a and 12a on the outer surface 10a of the windshield 10, and each of these wiping areas 1i"i
Windshield outer surface 10 at z, i'2 a
Wipe off any adhering liquid such as raindrops that have adhered to a.

A liquid sensor 20 is attached to the center portion of the lower edge of the inner surface 10b (see FIG. 2) of the windshield 10, corresponding to a part of the wiping area 12.2. As shown in FIGS. 2 and 6, it includes a support member 21, a single light emitting element 22, a pair of light receiving elements 23 and 24, and a cover 25. The support member 21 is formed by an integral molding method using a material (for example, acrylic resin, polycarbonate, or glass) that has substantially the same refractive index for light as the windshield 10. At 21fl, the inner surface of the windshield io
The support member 21 is bonded to the center portion of the lower edge of the support member 21 with an appropriate transparent adhesive (having the same refractive index as the support member 21).

On the left side of the support member 21 in FIGS. 2 and 6,
A stepped hole 21b is formed in the inclined shape shown in FIG. 2 when molding the support member 21 9, and a light emitting element 22 is inserted into this stepped hole 21b, and the stepped hole 21b is formed at the base of the stepped hole 21b with epoxy resin. It is fixed to the stepped part. In such a case, the central axis of the stepped hole 21b, that is, the light emitting axis of the light emitting element 22, is aligned with the stepped hole 2.
The angle formed by the light emitting axis of the light emitting element 22 and the normal to the windshield outer surface 10a found at the intersection 10c of the light emitting axis with the windshield outer surface 1'Del is perpendicular to the bottom surface of the light emitting element 22. The critical angle is between the critical angle of the shield 10 with respect to air and the critical angle of the windshield 16 with respect to liquid such as rain. This means that the wind yield outer surface t
When no liquid is attached to aa, light emitted from the light emitting element 22 along its light emitting axis passes straight through the support member 21 into the windshield 10, is totally reflected at the outer surface 10a, and is reflected by the outer surface 10a of the windshield. This means that when liquid adheres to the area including the intersection 10C, the amount of light reflected in the area decreases.

In this embodiment, the light emitting element 22 has a near-infrared light emitting diode arranged on the optical axis of a convex lens, and the light generated from the light emitting diode through its conduction is transmitted through the convex lens about the light emitting axis. It is designed to convert into a beam of light that is generated radially within a solid angle of ±1.5°.

A thin plate 26 made of aluminum is attached to the center of the lower surface 2112 of the support member 21 by a stamping method so as to be in close contact with the inner surface 1 of the windshield.
Intersection 10 of the outer surface 10a of the windshield 1o
It functions to totally reflect the light reflected in the area including c. Further, on the right side of the support member 21 in FIGS. 2 and 3, a stepped elongated hole 21C is located at a position symmetrical to the stepped hole 211) with respect to the incident area of the beam light to the thin plate 26. A pair of light-receiving elements 25 and 24 are respectively inserted into the stepped elongated hole 21c, and a step is formed at the base of the supporting member 21 in the inclined shape shown in FIG. 2 by epoxy resin. It is fixed to the stepped portion of the elongated hole 21c. In such a case, the light receiving axis of each light receiving element 26°240 is perpendicular to the bottom surface of the stepped elongated hole 21C, and the thin plate 26 and the windshield outer surface 1 are perpendicular to each other within the windshield 1o.
The light receiving axis of each light receiving element 26 and 24 coincides with the direction of the light beam that travels straight into the support member 21 after being reflected at a region including the point 10d on 0a, and the light receiving axis of each light receiving element 26 and 24 corresponds to the direction of travel of the light beam. Located within the cross section. Note that the light receiving element 23.2
4 each have a built-in near-infrared photodiode, and when the light is received, each conducts to generate a light-receiving current.

The cover 25 is formed by a molding method using a light-resistant material such as rubber that does not transmit light, and covers the surface portion of the support member 21 except for the lower surface 21a together with the light emitting element 22 and the light receiving elements 26° and 24. Additionally, this shields the light receiving element 23 from ambient light and improves the appearance of the liquid detector 20 itself. In addition, the base 25 of the cover 25
In a, a lead wire 22a extends from the input terminal of the light emitting element 22 through a groove 21d provided on the upper surface of the support member 21.
The connector 27 is inserted together with the lead wires 23a and 24a extending from the output terminals of both light receiving elements 25 and 24, respectively.
It is connected to the.

The light emission control circuit 30, as shown in FIG.
The oscillation circuit 61 generates a series of oscillation pulses, and the drive circuit 32 sequentially generates drive pulses in response to each oscillation pulse from the oscillation circuit 31. This means that the light emitting element 22 is
This means that the light beam is repeatedly turned on in response to each drive pulse from 2 and intermittently emits a beam of light. The signal processing circuit 40 receives the light receiving currents from both the light receiving elements 25 and 2'4 to drive the wiper motor 16, and includes a current-voltage conversion circuit 41 which converts each light receiving current from both the light receiving elements 2324 into a light receiving voltage. .42, a differential amplification circuit 46 that differentially amplifies each light-receiving voltage from these surface current-voltage conversion circuits 41 and 42 and generates it as a differential amplification signal, and a difference from this differential amplification circuit 46. The dynamic amplified signal is converted to a reference voltage generator 44.
Reference voltage from d (point 1 on the windshield outer surface 10a
．． a comparator circuit 44 that generates a comparison signal only when the value of the differential amplification signal is higher than a reference voltage;
A drive circuit 45 generates a drive signal necessary for driving the wiper motor 13 in response to the comparison signal from the comparison circuit 44.
It is composed of. The light emission control circuit 3o and the signal processing circuit 4o are each connected to the connector 27 through lead wires and connectors (not shown).

In this embodiment configured as described above, when there are no liquids such as raindrops attached to the windshield outer surface 10<2, the light emitting element is intermittently activated in response to each drive pulse from the light emission control circuit 6o. A beam of light generated from the thin plate 22 travels straight through the support member 21 along its light emitting axis into the windshield 1o, is totally reflected in an area including the intersection 10c of the outer surface 10a, is totally reflected by the thin plate 26, and is completely reflected inside the windshield 1o. The light is totally reflected in a region including point ioa on the outer surface 10f2, and then passes through the support member 21 and enters the p light receiving elements 25 and 24.

Then, both of these light-receiving elements 23 and 24 generate the same light-receiving current in response to the human error, and the signal processing circuit 40
granted to. Next, the surface current-voltage conversion circuit 41.42
converts the light-receiving currents from both light-receiving elements 23 and 24 into the same light-receiving voltage, and a differential amplifier circuit 46 differentially amplifies these two light-receiving voltages and generates this as a differential amplification signal 11@. However, at this stage, the current-voltage conversion circuit 41
．． Since the respective light receiving voltages from the differential amplifier circuit 46 are the same, the value of the differential amplification signal from the differential amplifier circuit 46 is zero.

Therefore, the comparison circuit 44 does not generate a comparison signal, and the wiper motor 16 remains stopped.

In this state, the light emitting element 22 and the light receiving element 26 (or 2
4) on the optical path connecting the windshield outer surface 10.
When liquid such as raindrops adheres to the area including the intersection 10c or 10d of fl+ (see FIG. 4), the light receiving current from the light receiving element 26 (or 24) increases the amount of light incident on the light receiving element 26 (or 24). decrease due to decrease, current-voltage conversion circuit 4
1 (or 42) decreases, and the value of the differential amplification signal from the differential amplifier circuit 46 changes from both current-voltage conversion circuits 4
The value corresponds to the difference in received light voltage from 1°42. Therefore, the comparison circuit 44 generates a comparison signal based on the fact that the value of the differential amplified signal from the differential amplifier circuit 43 is higher than the reference voltage from the reference voltage generator 44a, and the wiper motor 16 generates a comparison signal based on the value of the differential amplified signal from the differential amplifier circuit 43. The wiper blades 11, 12 are caused to slide in cooperation with a drive circuit 45 responsive to the signals.

In addition, if liquid such as raindrops adheres to the area including the intersection 1, DC, or 10d of the windshield outer surface 102 on the optical path connecting the light emitting element 22 and each of the light receiving elements 26 and 24, respectively, , since there is a difference in the amount of light incident on both light receiving elements 25.24 due to the difference in shape, size, etc. of these two attached liquids, both light receiving elements 25.2
4, the wiper blade 11.1'2 is slid by the wiper motor 16 in substantially the same manner as described above. In such a case, even if the temperature characteristics of the light emitting element 22, fluctuations in the amount of light emitted due to changes over time, or disturbance light affect the light receiving currents of both light receiving elements 23 and 24, such influence will not affect the differential output of the signal processing circuit 40. The difference can be removed by the differential amplification function of the amplifier circuit 46.

Next, another embodiment of the present invention will be explained with reference to FIGS.
0 is attached to a part of the windshield inner surface 10b instead of the liquid detector 20 in the previous embodiment. The liquid detector 50 has a disc-shaped support member 51 (see FIG. 6), and this support member 51 has a recess 51a with a V-shaped cross section in the center of its upper surface. 6th on the outer periphery
The support member 5 has an inclined peripheral surface 51b shown in the figure.
The windshield inner surface 10b is made of the same material as the support member 21 at its lower surface 51c.
It is glued to the center of the lower edge.

The liquid detector 50 also includes a support member 52 that integrally supports a light emitting element 56 and a plurality of light receiving elements 54a to 541 (see FIGS. 5 to 7). For example, it is formed of a synthetic resin material by an integral molding method so as to have the cross section shown in FIG. 6, and its lower surface is attached to the upper surface of the support member 51 by adhesive.

In this case, since the outer peripheral edge hanging portion 52a of the support member 52 is joined to the inclined peripheral surface 51111 of the support member 51, the assembly position of the support member 52 with respect to the support member 51 is uniquely determined. A through hole 52b is formed in the center of the support member 52 so as to face the recess P9T51a of the support member 51.
2, and this through hole 52b has a
A light emitting element 56 is inserted, and at its base, a support member 52 is inserted.
It is bonded to the center of the lower surface of the wiring board 55 fixed to the upper surface. In such a case, the light emitted from the light emitting element 56 is transmitted to the recess 5.
The angle formed by the optical path perpendicular to the inner surface of the windshield 1a in a circular shape and the plane perpendicular to the windshield outer surface 10a determined by the circular intersection line 10θ of this optical path with the windshield outer surface 10a is the relationship between the windshield 10 and the air. The critical angle is between the critical angle in relation to the windshield 10 and a liquid such as rain. This means that when there is no liquid attached to the windshield outer surface iQa, the light that is perpendicularly incident on the inner surface of the recess 51.2 along the optical path from the light emitting element 56 in a circular shape advances by Ktm inside the windshield 10. When the liquid is totally reflected at the circular intersection line 10e of the outer surface 10a and the liquid adheres to the portion including the circular intersection line IDe, the amount of light reflected at the circular intersection line 10e decreases. The light emitting element 56 has a structure in which the convex lens is omitted from the light emitting element 22 in the above embodiment, and when it is electrically connected in the evening, it emits light uniformly from its light emitting surface toward the entire recess 51a of the support member 51. .

Twelve through holes 52C (only two through holes 52c in the same cross section are shown in FIG. 6) are formed on the inclined peripheral surface 511 of the support member 51 in the outer peripheral edge hanging portion 52a of the support member 52.
) on the same circumference in an inclined manner so as to face the support member 5.
Twelve light receiving elements 54a to 541 are inserted into each of these through holes 52C, and their bases are fixed to the lower surface of the outer peripheral edge of the wiring board 55. In such a case, the central axis of each through hole 52c, that is, each light receiving element 54a to 54-! The light receiving axis of t is perpendicular to the inclined peripheral surface 51b of the support member 51, and
This coincides with the optical path of the light that is reflected at the circular intersection line 10e on the outer surface 10a of the inside of the support member 51 and travels straight into the support member 51. Note that each of the light receiving elements 54a to 541 has the same configuration and function as the light receiving element 26 or 24 in the above embodiment.

The cover 56 is made of the same material as the cover 25 in the embodiment described above and is formed by a molding method to have the shape shown in FIGS. The exposed portion of the peripheral hanging portion 52a from the wiring board 55 is covered, and this! The appearance of the 11g single body detector 50 itself is enhanced. Further, a cylindrical base 55.2 formed in the center of the cover 56 includes a light emitting element 5.
A lead wire 53a extends from the input terminal of No. 6 through the center of the wiring board 55, and a lead wire LL2-L extends from the output terminal of each of the light receiving elements 54.2 to 541 through the outer peripheral edge of the wiring board 55. 4 and the connector 5
7 is connected.

Further, in this embodiment, the light emission control circuit 60 in the previous embodiment is employed as a driving means for the light emitting element 56, and a pair of light receiving elements 54a.

Each light receiving current from 54b, a pair of light receiving elements 54C254
Each light receiving current from d..., a pair of light receiving elements 54k
, 541, each signal processing circuit 40A has the same configuration function as the signal processing circuit 40 in the embodiment described above.

40B, . . . , 40F are adopted, and a drive signal generated from at least one of these signal processing circuits 40A, 40B, . ing. Note that the light emission control circuit 3o and each signal processing circuit 40A~
4[]F is connected to the connector 57 via a lead wire and a connector (not shown).

In this embodiment configured as described above, when there is no liquid such as raindrops attached to the windshield outer surface 1 (zz), the light emitting element 56 intermittently emits light in response to each drive pulse from the light emission control circuit 6o. When the light generated in the light spreads over the entire recess 51a of the support portion 51, the light emitted from the light emitting element 56
．． Light traveling perpendicularly in a circular shape toward the inner surface of the windshield 10 passes through the support member 5"1, and is totally reflected on the circular intersection line 1Qθ of the outer surface 1oa, after which it is supported again. Each light receiving element 54.2 to 54ffi passes through part 51
Separate people. Then, each of these light receiving elements 540-54.
M generates the same light receiving current in response to the incident light and applies it to signal processing circuits 40A to 40F corresponding to each light receiving element. However, at this stage, each pair of light receiving elements 54
a, 54b; 54c, 54a;...; 54
Furthermore, since the respective light receiving currents generated from 542 are the same, no drive signal is generated from any of the signal processing circuits 40A to 40F, and the wiper motor 16 remains stopped.

In this state, the light emitting element 56 and the light receiving element 54a.

At least one of 54c, 54e, 54#, 54i, 54 (or 54b, 54d, 54f, 54
h.

54j, 542), when liquid such as raindrops adheres to the circular intersection line 10e of the windshield outer surface 10a, the light receiving element is driven from the signal processing circuit corresponding to at least one of the light receiving elements. A signal is generated in the same manner as in the previous embodiment and applied to wiper motor 16 via OR gate 1-46 to drive it. Further, the light emitting element 56 and each pair of light receiving elements 54a, 54b: 54c, 54
d: ...; 54k, 54.1 on each optical path connecting at least one pair of windshield outer surface 1
When liquid such as raindrops adheres to the circular intersection line 10e of 0a, a drive signal is generated from the signal processing circuit corresponding to at least one pair of the light receiving elements in the same manner as in the embodiment described above.
It is applied to the wiper motor 16 via the gate 46 to drive it.

In addition, in each of the above embodiments, an example was described in which the light receiving elements 26.24 or 5472 to 54-M were adopted as the light receiving means, but the number of light receiving elements may be changed as appropriate. Good too.

As explained above, the liquid detector for the windshield wiper automatic control device according to the present invention has a single light emitting element and a plurality of light receiving elements, as exemplified in each of the above embodiments. When liquid such as raindrops adheres to the outer surface of the windshield and is not removed, the light emitted from the light emitting element is incident on the windshield so as to be totally reflected within the windshield, and the adhering liquid is present. At this time, the amount of light reflected within the windshield is reduced, and the light emitted from the windshield after reflection within the windshield is received by at least one of the plurality of light receiving elements, and the light reception result is received. , the structural feature is that it is generated as a detection signal necessary for automatic control of the windshield wiper, and thereby, each light emitting element and the plurality of light receiving elements are connected to each other. When liquid such as raindrops adheres to the outer surface of the windshield on the optical path, it can be detected. As a result, by using only a single light emitting element for multiple light receiving elements, multiple light receiving elements can be used. On the other hand, a wide detection area equivalent to that obtained when using the same number of light emitting elements can be obtained without reducing the S/N of the detection signal. In such a case, since only a single light emitting element is required, the cost can be reduced and the liquid detector can be made smaller than in the case where the same number of light receiving elements and light emitting elements are used (Fig. f).

[Brief explanation of drawings]

1 is a diagram showing an embodiment of a liquid detector according to the present invention attached to a windshield, FIG. 2 is a cross-sectional view of the liquid detector along line A-A in FIG. 6, and FIG. 6 is a partially cutaway plan view of the same liquid detector, FIG. 4 is a block circuit diagram for the same liquid detector, and FIG. 5 is a partially cutaway diagram of another embodiment of the liquid detector according to the present invention. The plan view, Figure 6, is
A cross-sectional view of the liquid detector and FIG. 7 are block circuit diagrams for the liquid detector. Explanation of symbols 10...Windshield, 11.12...Wiper blade, 20.50...Liquid detector, 22°56.
...Light emitting element, 23.24.54a-541... Light receiving element. Applicant Nippondenso Co., Ltd. Agent Patent Attorney Teru Hase − 11ε

Claims (1)

[Claims] A liquid detector for a windshield wiper automatic control device provided on a part of the inner surface of the windshield corresponding to the sliding area on the outer surface of the windshield of the wiper blade constituting the windshield wiper, This windshield has a light emitting element and a plurality of light receiving elements, and is configured to completely reflect light generated from the light emitting element within the windshield when no liquid such as raindrops is attached to the outer surface of the windshield. In addition, when the adhered liquid is present, the amount of light deflection within the windshield is reduced, and the light emitted from the windshield after reflection within the windshield is transmitted to one of the plurality of light receiving elements. A liquid detector for an automatic windshield wiper control device, characterized in that the liquid detector receives light from at least one of them and generates the result of the light reception as a detection signal necessary for automatic control of the windshield wiper.