JPH0648455Y2 - Raindrop sensor - Google Patents

Description

[Detailed description of the device] [The purpose of the device]

(Industrial application field) This device detects the amount of rainfall by the intensity and frequency of raindrops,
The present invention relates to a raindrop sensor used in a raindrop-sensitive wiper device that operates a wiper device in response to this. (Prior Art) Conventionally, as the raindrop sensor described above, for example, there is one shown in FIG. The raindrop sensor 101 shown in the figure is a piezoelectric element 103 that integrally has a vibration plate 102 that vibrates when raindrops collide.
An amplifying section 104 for amplifying an electric signal obtained from the piezoelectric element 103, and protecting the electric signal from a disturbing current 2
Electrolytic capacitors (protective elements) 105 and 106 and amplifier 104
Further, a shield case 107 for protecting the electrolytic capacitors 105 and 106 from disturbance is provided, and these are all housed in a case 108 made of synthetic resin. The piezoelectric element 103 is attached to the bottom portion 108a of the case 108, and the amplification unit 104 and the electrolytic capacitors 105 and 106 are
Connect the terminals 104a and 105a, 106a to the opening 108b of the case 108.
The shield case 107 is connected to the wiring pattern 109a of the printed circuit board 109 fixed to the printed circuit board 109, and the shield case 107 covers the amplifier section 104 and the electrolytic capacitors 105 and 106.
It is fixed to. The raindrop sensor 101 is provided in a state in which the bottom portion 108a of the case 108 is projected from the hood hood 110 of the vehicle body to the outside. (Problems to be solved by the invention) However, in the conventional raindrop sensor 101 described above,
Since the terminals 104a and 105a, 106a of the amplifier 104 and the electrolytic capacitors 105, 106 were connected on the wiring pattern 109a of the printed circuit board 109, when connecting the amplifier 104 to the piezoelectric element 103 and the drive control system side of the wiper device, It is necessary to increase the number of wiring patterns 109a on the printed circuit board 109, and as a result, this wiring pattern 109a serves as an antenna to cause radio wave interference, which may cause a malfunction of the wiper device. In addition, since the printed circuit board 109 has to be set to have a large area, there is a problem that the shape becomes large, and it has been a conventional problem to solve these problems. (Purpose of the Invention) The present invention has been made by paying attention to the above-mentioned conventional problems, and it is possible to almost completely prevent the wiper device from malfunctioning due to the radio wave interference, and to realize the miniaturization. It is an object of the present invention to provide a raindrop sensor that can be used.

[Constitution of device]

(Means for Solving the Problems) The present invention is directed to an amplifier that amplifies an electric signal generated in a piezoelectric element due to collision of raindrops and outputs the amplified electric signal to a wiper drive control system, and a protection that protects the electric signal from a disturbing current. In a raindrop sensor including an element and a shield case that protects the amplification section and the protection element from disturbance, the amplification section and the protection element are provided on the same integrated circuit board, and the input terminal and the output terminal of the integrated circuit board are A piezoelectric element output printed board having the output side wiring pattern of the piezoelectric element respectively arranged at the opposite ends of the integrated circuit board and having the input side and the output terminal respectively, and the input side wiring pattern of the wiper drive control system. The drive control system input printed circuit board is connected, and each of the piezoelectric element output printed circuit board and the drive control system input printed circuit board is provided. It is characterized in that the ground sides are connected by the shield case, and the structure of this raindrop sensor is a means for solving the above-mentioned conventional problems. (Advantage of the Invention) In the raindrop sensor according to the present invention, since the printed circuit board, which is conventionally one, is divided into the piezoelectric element output printed circuit board and the drive control system input printed circuit board, there are few wiring patterns. Therefore, radio interference due to disturbance is unlikely to occur. Further, since the piezoelectric element output printed board and the drive control system input printed board are respectively connected to the input terminal and the output terminal which are respectively wired at the opposite ends of the integrated circuit board, the raindrop sensor can be miniaturized. Will contribute. (Example) Hereinafter, this invention is demonstrated based on drawing. 1 to 3 show an embodiment of a raindrop sensor according to the present invention. The raindrop sensor 1 shown in the figure has a piezoelectric element 3 integrally including a vibration plate 2 that vibrates when raindrops collide, and an electric signal obtained from the piezoelectric element 3 is amplified to control the drive of a wiper device (not shown). Amplifying unit 4 for outputting to the system, two electrolytic capacitors 5 and 6 which are protection elements for protecting the electric signal from interfering current, amplifying unit 4 and electrolytic capacitor
A shield case 7 is provided to protect 5, 6 from disturbances, and each of them has a substantially rectangular tube-shaped case body 21 and an outward flange 21a formed in one opening (upper side in FIG. 1) of the case body 21. The piezoelectric element 3 is housed inside a synthetic resin case 20 composed of a cap 22 that fits into the case and a cover 23 that closes the other opening (lower side in FIG. 1) of the case body 21. It is attached to the inside of the cap 22 almost at the center. The amplifying section 4 and the two electrolytic capacitors 5 and 6 are integrally provided on a thin film integrated circuit board 8. The input terminal 8a and the output terminal 8b of the integrated circuit board 8 are integrated circuit board 8 Are arranged at opposite ends of the. In this case, the integrated circuit board 8 is provided in the case body 21 with its longitudinal direction aligned with the longitudinal direction of the case body 21 and with the input terminals 8a positioned on the cap 22 side. This input terminal
A piezoelectric element output printed board 9 having an output side wiring pattern 9a (shown only in FIG. 3) of the piezoelectric element 3 connected to the piezoelectric element 3 via a lead wire 15 is connected to 8a, and The output terminal 8b has a wiper drive control system and a harness 16
Input side wiring pattern 10a of the drive control system connected via
A drive control system input printed circuit board 10 (shown only in FIG. 3) is connected, and both printed circuit boards 9 and 10 are substantially perpendicular to the integrated circuit board 8. The integrated circuit board 8 is provided between the step portion 21b formed on the other opening side of the case body 21 and the wall portion 23a of the cover 23 fitted in the other opening of the case body portion 21. By sandwiching the drive control system input printed circuit board 10,
It is designed to be fixed inside the case body 21, and the cover 23
Is fixed to the case body 21 by locking projections 21c, 21c formed at the front and rear edges (left and right edges in FIG. 1) of the other opening of the case body 21, respectively. The shield case 7 is in the shape of a rectangular tube, and a pair of protrusions 7a, 7a and 7b that are opposed to each other and extend in the longitudinal direction at the front and rear edges (left and right edges in FIG. 1) of the one opening and the other opening. ,
7b are formed respectively. And this shield case 7
Is a pair of protrusions 7a, 7 having one opening (upper side in FIG. 1).
a is fitted in locking recesses 9b, 9b formed on the front and rear sides of the piezoelectric element output printed circuit board 9 and bent and locked inward, and a pair of projections 7b provided in the other (lower side in FIG. 1) opening. , 7
By inserting b into the locking holes 10b, 10b formed in the front and rear sides of the drive control system input printed circuit board 10 and bendingly locking the inside, both printed circuit boards 9, 10 are covered with the integrated circuit board 8. It is fixed between them. In this case, the protrusions 7a, 7a on one opening side are connected to the piezoelectric element output printed board 9
Is connected to the ground side of the output side wiring pattern 9a by soldering, and the protrusions 7b, 7b on the other opening side are connected to the ground side of the input side wiring pattern 10a of the drive control system input printed circuit board 10 by soldering. As a result, each circuit of both printed circuit boards 9 and 10 can be made an equivalent circuit. And this raindrop sensor 1 is the hood of the vehicle.
The cap 22 is attached to the sensor mounting hole 25a formed in the cover 25 through the packing 26 in a state of protruding to the outside. At this time, as shown in FIG. The tips of the projecting arms 23b, 23b are brought into contact with the inward slopes 26a, 26a formed on both sides of the packing 26, and the packing 26 is brought into close contact with the sensor mounting hole 25a. It can be installed without. Reference numeral 17 is a grommet. Therefore, in this raindrop sensor 1, the piezoelectric element output printed circuit board 9 and the drive control system input printed circuit board 10 are divided, and the ground sides of both printed circuit boards 9 and 10 are connected by the shield case 7. The wiring patterns 9a and 10a on both the printed boards 9 and 10 are smaller than in the conventional case, and it is less likely to receive a radio interference, and the both printed boards 9 and 10 can be made small. Further, in this embodiment, inside the case body 21,
Since the integrated circuit board 8 is provided with its longitudinal direction aligned with the longitudinal direction of the case body 21, the cross sectional area of the case body 21 should be approximately the same size as the area of both printed boards 9 and 10. As a result, the area of the cap 22 that fits into this case body 21 is reduced, and the hood
It is possible to contribute to the improvement of the appearance design of the 25. The detailed configuration of the raindrop sensor according to the present invention is not limited to the above-mentioned embodiment.

[Effect of device]

As described above, the present invention has an amplifying unit that amplifies an electric signal generated in a piezoelectric element due to collision of raindrops and outputs the amplified electric signal to a wiper drive control system, and a protection element that protects the electric signal from an interfering current. A raindrop sensor having a shield case for protecting the amplification section and the protection element from disturbance, wherein the amplification section and the protection element are provided on the same integrated circuit board, and the integrated circuit has an input terminal and an output terminal of the integrated circuit board. A piezoelectric element output printed circuit board having the output side wiring patterns of the piezoelectric element respectively disposed at the opposite ends of the board and having the input terminal and the output terminal respectively, and the input side wiring pattern of the wiper drive control system. A drive control system input printed circuit board is connected and each of the piezoelectric element output printed circuit board and the drive control system input printed circuit board is connected. Since the sides are connected to each other by the shield case, it is less likely to be disturbed, and it is possible to almost eliminate the occurrence of malfunction of the wiper device due to radio interference, and it is possible to realize a compact shape. It has a very good effect that it can.

[Brief description of drawings]

1 and 2 are sectional side views and sectional front views, respectively, showing an embodiment of a raindrop sensor according to the present invention, and FIG. 3 is an exploded view of the raindrop sensor shown in FIG. FIG. 4 is a perspective explanatory view, and FIG. 4 is a sectional explanatory view from the side direction showing a conventional raindrop sensor. 1 ... Raindrop sensor, 2 ... Vibration plate, 3 ... Piezoelectric element, 4 ... Amplifying section, 5,6 ... Electrolytic capacitor (protective element), 7 ... Shield case, 8 ... Integrated circuit board, 8a ... Input terminal, 8b ... Output Terminals, 9 ... Piezoelectric element output printed circuit board, 9a ... Output side wiring pattern, 10 ... Drive control system input printed circuit board, 10a ... Input side wiring pattern.

Claims (1)

[Scope of utility model registration request] 1. An amplifying unit for amplifying an electric signal generated in a piezoelectric element due to a collision of raindrops and outputting the amplified electric signal to a wiper drive control system, a protective element for protecting the electric signal from an interfering current, the amplifying unit and the protecting unit. In a raindrop sensor having a shield case for protecting an element from disturbance, the amplifying section and the protection element are provided on the same integrated circuit board, and an input terminal and an output terminal of the integrated circuit board are opposite ends of the integrated circuit board. And a drive control system input print having an input side wiring pattern of the wiper drive control system, and a piezoelectric element output printed circuit board having the output side wiring pattern of the piezoelectric element respectively at the input terminal and the output terminal. While connecting the boards, connect the grounding sides of the piezoelectric element output printed board and the drive control system input printed board to the shield case. A raindrop sensor characterized by being connected with a base.