JPH0249565Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a raindrop sensor that detects the presence or amount of raindrops and is suitable for use, for example, in automatic operation of a car using wipers, and its purpose is to:
To provide a raindrop sensor capable of accurately detecting the presence or absence of raindrops and the amount thereof with a simple configuration.

The following is an example of the present invention shown in Figures 1 to 4.
This will be explained with reference to the figures. 1 has an opening 2 on the top surface
It is a flat rectangular container-shaped cover having a protective net 3 disposed at an opening 2 and a bottom opening closed by a bottom plate 4. 5, for example, a stainless steel plate is punched with a large number of strip-shaped holes 5a in parallel, and a large number of first electrode bodies 6 having a rectangular cross section are arranged in parallel between two opposing sides of a rectangular frame portion 5b. The spacing between the first electrode bodies 6 is set to be large in the left ⅓ part and small in the remaining part.
The sensor member 5 has a first
Terminals 7 that are electrically connected to all of the electrode bodies 6 are provided. Reference numeral 8 denotes a dielectric material made of, for example, a resin film with a thickness of 0.1 mm or less attached to cover the outer surface of the first electrode body 6, and this material covers the entire surface of the sensor member 5 except for the terminal portion 7. That's what I do. 9 is dielectric 8
A plurality of second electrode bodies are formed by covering the outer surface of, for example, with chrome plating, and these are formed only on the part of the sensor member 5 that faces each first electrode body 6. Each of them is electrically independent, and therefore, a plurality of capacitors 10 are formed in the sensor member 5 by the cooperation of the first electrode body 6, the inductor 8, and the second electrode body 9. . On the other hand, reference numeral 11 denotes a water absorbent body formed of, for example, a porous material, which is disposed on the top surface of the bottom plate 4, and a stepped portion 11 is provided on the top surface of this body.
1a and groove portions 11b, 11c, and 11d are provided, and metal is further deposited on the entire upper surface of the water absorbing body 11 to form a third electrode body 12. Further, 13 is a terminal electrically connected to the third electrode body 11. A sensor member 5 is disposed on the third electrode body 12 on the upper surface of this water absorbing body 11 via a rectangular frame-shaped spacer 14, and a rectangular presser frame is further provided on the upper surface of the sensor member 5. 15 is provided, and the upper surface of the presser frame 15 is in contact with the inner surface of the cover 1.
In this state, the left side 1/3 of the first and second electrode bodies 6 and 9 where the spacing between rows is large is opposite to the step 11a, and the second electrode body 9 and the third electrode body 12 has a detection interval d ₁ , and the remaining first electrode bodies 6 have a small spacing between the second electrode bodies 9 and the second electrode bodies 9 facing the part other than the stepped portion 11a. The three electrode bodies 11 have a detection distance _d2 . Reference numeral 16 denotes a printed circuit board on which the sensor member 5 is arranged perpendicularly within the cover 1, to which the terminal 7 provided on the sensor member 5 and the terminal 13 conductive to the third electrode body 12 are electrically connected, respectively. An oscillation circuit (not shown) whose output wave number changes due to a change in capacitance, for example, is disposed on the printed circuit board 16.

Next, the operation of the above configuration will be explained. Now, in a state where no raindrops are attached to the upper surface of the third electrode body 12, the second electrode body 9 and the third electrode body 12
Terminals 7 and 13 are in a non-conducting state.
The capacitance between the two is only stray capacitance. In this state, for example, as shown in FIG. 4, a single raindrop 17 adheres to the second electrode body 9 and the third electrode body 12, which are separated by a detection interval d ₂ so as to straddle the pair. Then, one capacitor 10 is connected between the terminals 7 and 13 because the raindrops 17 bring the two electrode bodies 9 and 12 into a conductive state, and therefore, the capacitance between them is equal to the capacitance of the capacitor 10. To increase. The capacitance between the first electrode body 6 and the third electrode body 12, that is, the capacitance between the terminals 7 and 13, is transferred from the opening 2 of the cover 1 through the protective net 3 to the third electrode body 12. This increases as the number of raindrops 17 falling on the upper surface increases and as the multiple pairs of second and third electrode bodies 9 and 12 facing each other with the detection distance d ₂ in between become conductive due to the raindrops 17, Printed circuit board 16 depending on the capacitance change between terminals 7 and 13.
The oscillation frequency of the oscillation circuit provided in the oscillation circuit is changed. Since the raindrops 17 falling on the upper surface of the third electrode body 12 are absorbed by the water absorption action of the water absorbing body 11, the shape shrinks over time and the raindrops 17 fall on the top surface of the second electrode body 9. The second and third electrode bodies 9 and 12 are separated, and the conduction between the second and third electrode bodies 9 and 12 returns to the initial state. When it is continuously raining, new raindrops 17 fall one after another on the upper surface of the third electrode body 12, so that the plurality of pairs of second and third electrode bodies 9 and 12 become electrically conductive depending on the amount of rain. Terminal 7 repeatedly becomes non-conductive
The capacitance between and 13 increases and decreases in a pulse manner. Therefore, when the rainfall is more intense than the water absorption capacity of the water absorbing body 11, all the second and third electrode bodies 9 and 12 facing each other with the detection interval _d2 in between are in a conductive state; A large raindrop ₁ is formed between the second and third electrode bodies 9 and 12 which face each other with a distance d 1 between them.
7 and terminals 7 and 13 are now electrically connected.
The capacitance between the raindrops 17 increases and decreases in a pulsed manner, so that the amount of raindrops 17 can be detected even when it is raining heavily.

Incidentally, although the raindrops 17 have a predetermined resistance value, for example, a few raindrops may adhere between the second electrode body 9 and the third electrode body 12, which face each other with the detection distance d ₁ , d ₂ in between. Then, even if more raindrops adhere, there will be almost no change in the resistance value, and therefore 1 raindrop
It is difficult to accurately detect the amount of raindrops 17 (precipitation amount) with a sensor that outputs the change in the resistance value of raindrop 7 as is. However, in the above configuration, the raindrop 1
As the amount of 7 increases, the number of capacitors 1
0 is connected in parallel between terminals 7 and 13, and the number and amount of capacitance changes between these terminals 7 and 13 become approximately proportional to the amount of raindrops 17. Changes in the amount of can be detected accurately over a wide range.

In the above configuration, since the second electrode body 9 covers one first electrode body 6 via the dielectric 8 so as to cover substantially the entire length of the first electrode body 6, for example, one electrode body 6 Raindrops 1 adhering so as to straddle between the second electrode body 9 and the third electrode body 13 corresponding to the body 6
Whether one drop or several drops of 7 is present, only one capacitor 10 is connected between terminals 7 and 13, and there is almost no change in capacitance, but the second electrode formed for one first electrode body 6 If the body 9 is divided into three pieces as shown in FIG. 5, each second electrode body 9 and first electrode body 6
The capacitance of the capacitor 10 formed by is approximately 1/3,
Capacitor 10 corresponding to one first electrode body 6
Therefore, in this way, the raindrops 1 that adhere so as to span between the second electrode body 9 and the third electrode body 12 corresponding to one electrode body 6.
The number of capacitors 10 connected between the terminals 7 and 13 changes depending on whether there is one drop of 7 or three drops, so that changes in capacitance between the terminals can be detected more minutely.

Furthermore, in the above configuration, the second electrode body 9 covers the entire circumference of the first electrode body 6 with the dielectric body 8 in between, but as shown in FIG. A part of the outer surface of the first electrode body 6 may be covered through the body 8. In this way, the second electrode body 9 can be easily coated with the conductive material from one side. can be formed.

Further, the third electrode body 12 is formed in a planar shape on the upper surface of the water absorbing body 11, but the water absorbing body 11 is omitted by forming an independent shaped third electrode body facing each second electrode body 9. Furthermore, the step portion 11a and the groove portions 11b, 11c, and 11d provided on the water absorbing body 11 may also be provided as necessary.

As is clear from the above description, the present invention provides a plurality of capacitors that cooperate with the outer surface of a plurality of rod-shaped first electrode bodies arranged in a row through a thin dielectric material. A third electrode body is provided with a predetermined detection interval from the second electrode body, and a detection interval between the second and third electrode bodies is provided. When raindrops conduct, it is output as a change in capacitance between the first and third electrode bodies, so the capacitance increases or decreases depending on the amount of raindrops, making it possible to use a simple configuration. The presence and amount of raindrops can be accurately detected.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the present invention, with Figure 1 being a longitudinal sectional view, Figure 2 being an exploded perspective view, and Figure 3 being an enlarged perspective view showing the main parts broken away. ,
Fig. 4 is an enlarged sectional view for explaining the operation, Fig. 5 is a view equivalent to Fig. 3 showing another embodiment of the present invention, and Fig. 6 is an enlarged sectional view of main parts showing a different embodiment of the invention. be. In the drawings, 1 is a cover, 5 is a sensor member, 6 is a first electrode body, 8 is a dielectric body, 9 is a second electrode body, 1
0 is a capacitor, 11 is a water absorbing body, 12 is a third electrode body, and 17 is a raindrop.

Claims (1)

[Scope of utility model registration request] A plurality of rod-shaped first electrode bodies arranged in a row, a thin dielectric body attached to cover the outer surface of the first electrode body, and a first electrode body attached to the outer surface of the dielectric body. A plurality of second electrode bodies which form a plurality of capacitors by cooperation with the electrode bodies are disposed with a predetermined detection interval between the plurality of second electrode bodies. a third electrode body, and when a raindrop conducts the detection interval between the second and third electrode bodies, the raindrop is connected to the first electrode body and the third electrode body. A raindrop sensor characterized by outputting as a capacitance change.