JPS62118246A - Control system for window shield wiper - Google Patents

Abstract

PURPOSE:To secure a wiping operation of a window shield wiper irrespective of the quantity of a rainfall, by providing an auxiliary raindrop detecting signal. CONSTITUTION:When a raindrop has adhered to a window shield, a raindrop detecting means 30 and 40 detect an impedance variation between a pair of counter electrodes, respectively, corresponding to each wiper 10 and generate a raindrop detecting signal, and in response to this signal, a driving signal of the wiper 10 is outputted from a driving signal generating means Ec. The detecting means 40 is provided with an auxiliary raindrop detecting means for detecting a variation of an impedance between auxiliary electrodes, which is generated only when a raindrop at the time of a heavy rain has adhered to the opposed auxiliary electrodes, and outputting it as an auxiliary raindrop detecting signal. The driving signal generating means Ec responds to this auxiliary raindrop detecting signal, to, outputs a driving signal, and operates the wiper.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control system for a windshield wiper employed in a vehicle, a ship, an aircraft, etc., and in particular, in wiping the windshield wiper. The present invention relates to a control system that employs an electrode facing raindrop detector.

[Prior art]

Conventionally, as a raindrop detector in a control system for this type of windshield wiper, for example,
As disclosed in Japanese Patent No. 9-189148, it is conceivable to employ a raindrop detector in which a water-repellent insulator is provided between a pair of opposing electrodes.

[Problem that the invention seeks to solve]

However, in such a configuration, if the surface of the counter electrode is dirty with dust, mud, etc., and raindrops adhere to the counter electrode, the raindrops will be caused by the dust, mud, etc. Forms a water film. For this reason, when raindrops adhere to the opposing electrode again, the change in impedance between the opposing electrodes due to this decreases due to the water film, resulting in a situation where raindrops cannot be detected. Moreover, such a phenomenon becomes more significant as the water film becomes thicker, that is, as the amount of rainfall increases (for example, during heavy rain).

Therefore, in order to cope with this problem, the present invention employs, in addition to the raindrop detector, a raindrop detector that has been used to detect raindrops during heavy rain in a control system for a windshield wiper. In this way, the windshield wiper is controlled to ensure the wiping operation of the windshield wiper by accurately detecting raindrops regardless of the amount of rainfall.

[Means for solving problems]

In solving this problem, the structural features of the present invention are as follows:
This is applied to a windshield wiper that operates to wipe away raindrops when they adhere to the windshield, and has a pair of opposing electrodes that are arranged opposite to each other. The windshield comprises a raindrop detection means for detecting a change in impedance between the opposite electrodes and generating the detected change as a raindrop detection signal, and a drive signal generation means for generating a drive signal in response to the raindrop detection signal. In a control system in which the wiper performs a wiping operation in response to the drive signal, the wiper has a pair of auxiliary electrodes arranged opposite to each other, and only when raindrops during heavy rain adhere to both auxiliary electrodes. Auxiliary raindrop detection means is provided for detecting a change in impedance between the auxiliary electrodes and generates the same as an auxiliary raindrop detection signal, and the drive signal generation means generates the drive signal in response to the auxiliary raindrop detection signal as well. That's what I did.

(Operation and Effect) With the present invention configured as described above, if heavy rain falls, this heavy rain will fall on both the raindrop detection means and the auxiliary raindrop detection means.

At this time, if mud, dust, etc. are attached to each surface of both opposing electrodes of the raindrop detection means, if raindrops due to heavy rain adhere to both opposing electrodes, it will be caused by the mud, dust, etc. mentioned above. As a result, a water film is formed over both opposing electrodes. Therefore, even if raindrops from heavy rain repeatedly adhere to both the opposing electrodes in such a state, 1. The impedance change between the two opposing electrodes is reduced, and the rain? Raindrop detection by the Fa detection means becomes impossible.

However, the auxiliary raindrop detection means is configured to detect a change in impedance between both auxiliary electrodes that occurs only when raindrops adhere to both auxiliary electrodes during heavy rain, and generate an auxiliary raindrop detection signal. Therefore, the windshield wiper operates based on a drive signal generated from the drive signal generation means in response to the auxiliary raindrop detection signal, so that the raindrop detection means cannot detect raindrops during heavy rain as described above. Regardless, raindrop removal from the windshield by the windshield wiper can be ensured based on the accurate raindrop detection action of the auxiliary raindrop detection means.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
2 and 2 are overall configuration diagrams showing an example in which the control system according to the present invention is applied to a vehicle windshield wiper 10, and the windshield wiper 10 has, as shown in FIGS. 2 and 3, The wiper blade 11 is caused to reciprocate and slide along the front windshield of the vehicle over its wiping area under the deceleration rotation of the speed reducer accompanying the rotation of the DC motor M. Further, in the windshield wiper 10, when the notch of the cam that rotates in conjunction with the output shaft of the speed reducer is at a predetermined rotational position corresponding to the lower edge position of the wiping area of the wiper blade 11, the cam contact 12 is grounded. When the notch of the cam is at a position other than the predetermined rotational position, the cam contact 12 is connected to the fixed contact 14. Note that the portion of the windshield wiper 10 excluding the wiper blade 11 is disposed directly below the lower edge of the front windshield (see FIG. 2).

As shown in FIGS. 1 to 4, the control system includes a wiper switch 20 and a pair of electrode facing raindrop detectors 30.
40 and 1. It is composed of an electric control circuit Ec.

The wiper switch 20 is connected at its connection terminal 21 to the positive terminal of the battery B together with the fixed contact 14 via the vehicle's ibnirasilane switch IG, and in its operating state, the wiper switch 20 connects both connection terminals. 21.
22 is connected, and the connection between both connection terminals 21 and 22 is cut off when the operation is released.

The raindrop detectors 30 and 40 are both integrally arranged on the upper surface of the substantially horizontal part of the bonnet of the vehicle, as shown in FIG. As shown in FIG. 5, an insulating base 31 having a trapezoidal cross-sectional shape;
It is composed of a pair of comb-teeth electrodes 32 and 33. The insulating base 31 is fixed at its lower surface to the upper surface of the substantially horizontal portion of the bonnet, and on the slanted upper surface 31a of the insulating base 31, both horizontal toothed electrodes 32 and 33 are spaced apart from each other. They are placed facing each other.

In this case, the longitudinal direction of each comb-teeth electrode 32 , 33 coincides with the direction of inclination of the inclined upper surface 31 a of the insulating base 31 .

In addition, the capacitance between the two side toothed electrodes 32,33 has a predetermined value (selected to be a small value) when no raindrops are attached to both side toothed electrodes 32,33, and Decreases upon deposition of raindrops over the tooth electrodes 32,33. This means that the raindrop detector 30 generates a detection voltage based on the capacitance between the two toothed electrodes 32,33. However, the comb-teeth electrode 32 receives a DC voltage + from a DC power supply (not shown).
(1/2) of cc is given (see Figure 3). Note that the DC power supply is connected to the wiper switch 2.
In the operating state of 0, power is supplied from battery B and DC voltage +
Generates Vcc.

The raindrop detector 40 is composed of an insulating base 41 and a pair of longitudinal electrodes 42 and 43, as shown in FIGS. 4 to 6. As shown in the figure, the electrode 42 is formed integrally extending into a rectangular parallelepiped shape from the rear part of the insulating base 31.The electrode 42 is placed on the upper surface 41a of the insulating base 41 with its longitudinal direction facing the left and right direction of the insulating base 41. On the other hand, the electrode 43 is provided on the electrode 42
It is provided on the rear surface 41b of the insulating base 41 so as to be parallel to the rear surface 41b of the insulating base 41. In such a case, the spacing between the electrodes 42, 43 is determined so that only raindrops during heavy rain can adhere across the electrodes 42, 43.

Further, the capacitance between both electrodes 42, 43 has a predetermined value (selected to be larger than in the case of raindrop detector 30) when no raindrops are attached across these electrodes 42, 43, It decreases when raindrops adhere to both types wA of 42.43. This means that the raindrop detector 40 generates a detection voltage based on the capacitance between the two electrodes 42,43. However, the electrode 42 is connected to the DC voltage (+Vc) from the DC power source.
c/2) is now given (see Figure 4).
. In this case, since both the raindrop detectors 30 and 40 are integrally formed, the structure of both raindrop detectors can be made compact.

The electric control circuit Ec is as shown in FIGS. 3 and 4.
Both signal processing circuits 50 and 60, and both signal processing circuits 5
0.60, and a comparison drive circuit 70 connected to 0.60. The signal processing circuit 50 includes a timer oscillator 51, a voltage divider 52 connected to the timer oscillator 51, a current-voltage conversion circuit 53 connected to the voltage divider 52 and the raindrop detector 30, and a current-voltage conversion circuit 53. The timer oscillator 51 includes an operational amplifier 51a, a capacitor 51b, a variable resistor 51C, and both resistors 51d and 51e. ing. The operational amplifier 51a has its inverting input terminal grounded via a capacitor 51b, and the non-inverting input terminal of the operational amplifier 51a receives a DC voltage (+Vcc/2) from the DC power supply via a resistor 51e. connected to the same DC power source as possible. The variable resistor 51c is connected between the inverting input terminal and the output terminal of the operational amplifier 51a to form a first variable time constant together with the capacitor 51b.

In the timer oscillator 51 configured in this manner, the operational amplifier 51a, in cooperation with the variable resistor 51c and the capacitor 51b, receives power from the DC power supply with a first variable period determined by the first variable time constant. A rectangular wave timer signal is generated using the DC voltage (+Vcc/2) as the central reference level. In such a case, the rectangular wave timer signal increases the DC voltage (+V c c
/2) becomes a rectangular wave signal with a higher level, and in the second half of the period, becomes a rectangular wave signal with a lower level than the DC voltage (+Vcc/2). Further, in this embodiment, the first variable period is set to 20 seconds, for example.
A variable time constant (that is, a variable resistance value of the variable resistor 51c) is set. Note that the electric control circuit EC is attached to a part of the cowl panel in the cabin of the vehicle.

The voltage divider 52 has a resistor 52a, and this resistor 52
a has a DC voltage (+V) from the DC power supply at one end.
cc/2) is connected to the same DC power supply, while at the other end, an operational amplifier 51a is connected through a resistor 52b.
is connected to the output terminal of However, this voltage divider 5
2 is a resistor 52a that measures the difference (in this embodiment, 0.2V or less) between the level of the rectangular wave timer signal from the timer oscillator 51 and the DC voltage (+Vcc/2) from the DC power supply.

52b, and use this as a divided voltage, and set the DC voltage (+Vcc/2) to the center reference level, and connect both resistors 52.
It is generated from the common terminal (ie, output terminal) of a and 52b.

The current-voltage conversion circuit 53 has an operational amplifier 53a, which is connected at its non-inverting input terminal to the output terminal of the voltage divider 52, while at its inverting input terminal, It is connected to the comb-teeth electrode 33 of the raindrop detector 30 and to the output terminal of the operational amplifier 53a via a resistor 53b. Therefore, in this current-voltage conversion circuit 53, the operational amplifier 53a is connected to the voltage divider 52.
The current flowing into the resistor 53b that makes the difference between the divided voltage from the raindrop detector 30 and the detected voltage from the raindrop detector 30 zero is converted into a voltage and generated as a converted voltage. In such a case, the converted voltage from the current-voltage conversion circuit 53 is equal to the rise (or fall) of the detection voltage from the -1 raindrop detector 30 at its rise (or fall).
A positive (or negative) first peak value is formed under the differential action of the capacitance between the drawing tooth electrodes 32 and 33 and the resistance value of the resistor 53b in response to the voltage (or falling), and the converted voltage This decrease in capacitance and resistance 53b occurs when the capacitance between the drawing tooth electrodes 32 and 33 decreases after the rise (or fall) of
A positive (or negative) second peak value (smaller than the first peak value) is formed under the differential action of the resistance value.

The filter circuit 54 filters unnecessary frequency components included in the converted voltage from the operational amplifier 53a using a resistor 54a and a capacitor 54b, and cuts off the DC component from the remaining components using a capacitor 54c and a resistor 54d, thereby detecting raindrops. drawing tooth electrode 3 defined by the detected voltage from the device 30;
Only a component corresponding to an impedance change of 2.33 is generated as a filter voltage using the DC voltage (+Vcc/2) from the DC power supply as the central reference level.

Note that the capacitor 54b and the resistor 54d are connected at one end to the DC power source so as to be supplied with a DC voltage (+Vcc/2) from the DC power source.

The amplifier circuit 55 has an operational amplifier 55a, and the operational amplifier 55a has its non-inverting input terminal connected to the common terminal of the capacitor 54c and the resistor 54d of the filter circuit 54, and its inverting input terminal It is connected to the DC power supply through a resistor 55b to receive a DC voltage (+Vcc/2) from the DC power supply. The operational amplifier 55a also receives a DC voltage (+Vcc/2
), and a parallel circuit of a capacitor 55e and a resistor 55f is connected between the inverting input terminal and the output terminal of the operational amplifier 55a. Therefore, the amplifier circuit 5 configured in this way
5, the operational amplifier 55a amplifies the filter voltage from the filter circuit 54 in cooperation with the resistors 55b and 55f and the capacitor 55e. Based on the amplification result, the capacitor 55c and the resistor 55d block the DC component, and the remaining component from the DC voltage (+Vcc/
2) is set as the center reference level and is generated as an amplified voltage.

As shown in FIG. 4, the signal processing circuit 60 includes a timer oscillator 61 and a voltage divider 62 connected to the timer oscillator 61.
The timer oscillator 61 includes an operational amplifier 61a, a current-voltage conversion circuit 63 connected to the voltage divider 62 and the raindrop detector 40, and a filter circuit 64 connected to the current-voltage conversion circuit 63. , a capacitor 61b,
It is composed of a variable resistor 61c and both resistors 61d and 61e. The operational amplifier 61a has its inverting input terminal grounded via a capacitor 61b, and the non-inverting input terminal of the operational amplifier 1161a is supplied with a DC voltage (+Vcc/2) from the DC power supply via a resistor 61e. connected to the same DC power source as possible. The variable resistor 61c is connected between the inverting input terminal and the output terminal of the operational amplifier 61a to form a second variable time constant together with the capacitor 61b.

In the timer oscillator 61 configured in this manner, the operational amplifier 61a, in cooperation with the variable resistor 61C and the capacitor 61b, generates a signal from the DC power source with a second variable period determined by the second variable time constant. A rectangular wave timer signal is generated with the DC voltage (+Vcc/2>) as the center reference level. In this case, the rectangular wave timer signal has the DC voltage (+Vcc/2) in its first half period.
It becomes a higher level square wave signal, and in the second half of the period,
This becomes a rectangular wave signal with a lower level than the DC voltage (+Vcc/2). Further, in this embodiment, the second variable time constant (that is, the variable resistance value of the variable resistor 61c) is set small so that the second variable cycle is a value that allows the windshield wiper 10 to perform a continuous wiping operation. ing.

The voltage divider 62 has a resistor 62a, and this resistor 62
a has a DC voltage (+V) from the DC power supply at one end.
cc/2) is connected to the same DC power supply, while the other end is connected to the operational amplifier 61a through the resistor 62b.
is connected to the output terminal of However, this voltage divider 6
2 is the difference between the level of the rectangular wave timer signal from the timer oscillator 61 and the DC voltage (+Vcc/2) from the DC power supply (in this embodiment, 0.2V or less) between both resistors 62a and 6.
2b, and use this as the divided voltage, and set the DC voltage (+Vcc/2) as the central reference level, and connect both resistors 62a.
, 62b (i.e., the output terminal).

The current-voltage conversion circuit 63 has an operational amplifier 63a, which is connected at its non-inverting input terminal to the output terminal of the voltage divider 62, while at its inverting input terminal, It is connected to the electrode 43 of the raindrop detector 40 and to the output terminal of the operational amplifier 63a via a resistor 63b. Therefore, in this current-voltage conversion circuit 63, the operational amplifier 63a inputs a current flowing into the resistor 63b such that the difference between the divided voltage from the voltage divider 62 and the detected voltage from the raindrop detector 40 becomes zero. is converted to voltage and generated as a converted voltage. In such a case, the converted voltage from the current-voltage conversion circuit 63 is applied to both electrodes 42 of the raindrop detector 40.
．． When there are no raindrops attached over the period of 43, it has a rectangular wave. In addition, the converted voltage reaches a positive (or negative) peak at its rise (or fall) due to the differential effect due to the reduced capacitance between the two electrodes 42 and 43 and the resistance value of the resistor 63b. form a value. The filter circuit 64 removes the DC component from the converted voltage of the current-voltage conversion circuit 63 using a resistor 64a and a capacitor 64b, and generates the remaining component as a filter voltage.

The comparison drive circuit 70 includes both voltage dividers 71 as shown in FIG.
．． 72, and a comparison circuit 73 connected to the amplifier circuit 55, filter circuit 64, and both voltage dividers 71 and 72.

The voltage divider 71 has a resistor 7ia, and this resistor 71
A is grounded at one end, and connected to the DC power source via a resistor 71b at the other end so as to receive a DC voltage (+Vcc) from the DC power source. Therefore, the voltage divider 71 divides the DC voltage (+VCC) between the resistors 7 and 7.
1a and 71b, and the divided voltage is generated from the common terminal (ie, output terminal) of both resistors 71a and 71b. In such a case, the divided voltage from the voltage divider 71 is applied to both side toothed electrodes 32, 33 of the raindrop detector 30 or the raindrop detector 40.
The voltage is set to be higher than the DC voltage (+Vcc/2) by a predetermined level to the extent that raindrops adhering to both electrodes 42 and 43 can be distinguished from various noises.

The voltage divider 72 has a resistor 72a, and this resistor 72a
is grounded at one end, while resistor 7 is connected at the other end.
It is connected to the DC power supply via 2b to receive DC voltage (+Vcc) from the DC power supply. However,
The voltage divider 72 connects the DC voltage (+Vcc) to both resistances. 2
A and 72b divide the voltage and use this as the divided voltage to connect both resistors 7.
2a.

It is generated from the common terminal (ie, output terminal) of 72b. In such a case, the divided voltage from the voltage divider 72 is applied to the raindrop detector 3.
The voltage is lower than the DC voltage (+Vcc/2) by a predetermined level to the extent that raindrops adhering to both lateral toothed electrodes 32, 33 of 0 or both electrodes 42, 43 of raindrop detector 40 can be distinguished from various noises. There is.

The comparison circuit 73 includes a pair of comparators 73a573b, a pair of diodes 73c and 73d, and a resistor 73e.The comparator 73a has its non-inverting input terminal connected to the output terminal of the amplifier circuit 45 and the filter circuit 64 It is connected to the output terminal of the voltage divider 71, while its inverting input terminal is connected to the output terminal of the voltage divider 71. Therefore, the comparator 73a detects that the amplified voltage from the amplifier circuit 55 or the filter voltage from the filter circuit 64 is connected to the voltage divider 71.
The first comparison signal is generated at a high level (or low level) when the voltage is higher (or lower) than the divided voltage from the first comparison signal. The comparator 73b connects the amplifier circuit 5 at its inverting input terminal.
5 and the output terminal of the filter circuit 64, and the non-inverting input terminal of the comparator 73b is connected to the output terminal of the voltage divider 72. Therefore, the comparator 73b performs the second comparison at a high level (or low level) when the amplified voltage from the amplifier circuit 55 or the filter voltage from the filter circuit 64 is lower (or higher) than the divided voltage from the voltage divider 72. (Generates No. 8.

Diode 73c connects comparator 7 at its t node.
This diode 73 is connected to the output terminal of 3a.
The cathode of C is connected to the DC power supply through a resistor 73e so as to be supplied with a DC voltage (+Vcc) from the DC power supply. Thus, the diode 73c becomes conductive (or non-conductive) in response to the low level (or high level) of the first comparison signal from the comparator 73a, and outputs the first comparison signal from the comparator 73a to its cathode side. . The anode of the diode 73d is connected to the output terminal of the comparator 73b, and the cathode of the diode 73d is connected to the DC power supply through a resistor T3e so as to receive a DC voltage (+Vcc) from the DC power supply. . Thus, the diode 73d becomes conductive (or non-conductive) in response to the low level (or high level) of the first comparison signal from the comparator 73b, and outputs the second comparison signal from the comparator 73b to its cathode side. .

The monostable multi-bi break 74 responds to the fall of the first (or second) comparison signal from the comparison circuit 73 and generates a pulse signal at a high level. The drive circuit 75 has a transistor Tr and a relay R7, and the transistor Tr is connected to the output terminal of the monostable multi-bi break 74 via both resistors 75a, 75a, and has a collector thereof. , electromagnetic coil 75b of relay Ry
It is connected to the connection terminal 22 of the wiper switch 20 via. Thus, the transistor Tr becomes conductive under the bias action of both resistors 75a, 75a in response to the generation of the pulse signal from the monostable multi-bibreak 74, and becomes non-conductive in response to the disappearance of the pulse signal.

The relay Ry includes an electromagnetic coil 75b and a pair of fixed contacts'
75c, 75d, and a double-throw contact 75e that is connected to the fixed contact 75C (or 75d) by demagnetizing (or excitation) the electromagnetic coil 75b, and the fixed contact 75c
is connected to the cam contact 12 of the windshield wiper 10. Furthermore, the fixed contact 75d is connected to the wiper switch 2.
The double-throw contact 75e is connected to the grounding fixed contact 13 via the DC motor M.

In this embodiment configured in this way, if the wiper switch 20 is in its operation released state, the connection terminal 22 of this wiper switch 20 is in a state of being cut off from the connection terminal 21, and the windshield wiper 10 is in a state of being disconnected from the connection terminal 21. The cam contact 12 is inserted into the ground fixed contact 13, and the wiper blade 11 is located at the lower edge of the wiping area. In such a state, if a light rain starts to fall and the wiper switch 20 is put into its operating state with the ignition switch IC closed, the connection terminal 22 of the wiper switch 20 is connected to the connection terminal 21 and the battery is disconnected. Allows power to be supplied from B to the electric control circuit EC.

Then, the timer oscillator 51.61 generates the DC voltage (+
Vcc/2) as the center reference level, and the first
and generates a square wave timer signal at a second variable period, and the voltage divider 52 sequentially divides the divided voltages (see symbol a in FIG. 7) with the DC voltage (+Vcc/2) as the central reference level. - The bone pressure device 62 generates the DC voltage (+Vcc/
2) is set as the central reference level, and a divided voltage is generated. At this time, if there are no raindrops adhering to the dual tooth electrodes 32.33 of the raindrop detector 30 and both electrodes 42.43 of the raindrop detector 40, the current-voltage conversion circuit 53 In relation to the maximum capacitance between 32.33,
Converted voltages (see symbol C in FIG. 7) are sequentially generated so that the detected voltage from the raindrop detector 30 matches the divided voltage from the voltage divider 52, while the current-voltage conversion circuit 63
In relation to the maximum capacitance between the two electrodes 42 and 43, the converted voltage (see reference numeral in FIG. )
occur sequentially.

In such a case, each converted voltage from the current-voltage conversion circuit 53 is applied to the bipolar tooth electrode 32 at the time of its rise (or fall).
．． Under the differential action based on the maximum capacitance between 33 and the resistance value of resistor 53b, a positive (or negative) first peak value is formed as shown by symbol C1 (or C2) in FIG. However, each converted voltage from the current-voltage conversion circuit 63 remains a rectangular wave. Further, as described above, the current-voltage conversion circuit 53 converts the detected voltage from the raindrop detector 30 into the voltage divider 5
2, the detected voltage, that is, the voltage of the comb-teeth electrode 33, responds to the level change of the divided voltage from the voltage divider 52, and the voltage of the comb-teeth electrode 32 changes. (+Vcc/2) is set as the central reference level and is inverted higher or lower than this level. On the other hand, as described above, since the current-voltage conversion circuit 63 acts to match the detected voltage from the raindrop detector 40 with the divided voltage from the voltage divider 62, the voltage at the electrode 43 is changed from the voltage from the voltage divider 62. In response to a change in the level of the divided voltage of the electrode 42
The voltage (+Vcc/2) is taken as the center reference level and is inverted higher or lower than this.

In this way, the polarity of the voltage applied between the two toothed electrodes 32, 33 is repeatedly reversed in relation to the first variable period in the timer oscillator 51, and the polarity of the voltage applied between the two electrodes 42, 43 is reversed repeatedly in relation to the first variable period of the timer oscillator 51. Since the reversal is repeated in relation to the second variable period at 61, each of these comb-teeth electrodes 32, 33 and each electrode 42, 43 can be reliably prevented from so-called DC galvanic corrosion that tends to occur due to, for example, salt damage.

When the converted voltages are sequentially generated from the current-voltage conversion circuits 53.63 as described above, each filter circuit 54.6
4 sequentially generate filter voltages. Next, the amplifier circuit 55 sequentially generates amplified voltages (refer to symbols di and d2 in FIG. 7) based on the filter voltage from the filter circuit 54. In such a case, each amplified voltage d1 corresponds to each first peak value C1 of the converted voltage from the current-voltage conversion circuit 53, and each amplified voltage d2 corresponds to each first peak value C1 of the converted voltage from the current-voltage conversion circuit 53. Each corresponds to the peak value C2. However, each amplified voltage d1 from the amplifier circuit 55 is higher than the divided voltage from the voltage divider 71 (see symbol e in FIG. 7), and each amplified voltage d2 from the amplifier circuit 55 is higher than the divided voltage from the voltage divider 71 (see symbol e in FIG. 7). Since it is lower than the divided voltage (see symbol f in FIG. 7), the comparator circuit 73 outputs the first and second comparison signals (
(See each code g1 and g2 in FIG. 7) are generated alternately,
A monostable multivibrator 74 is connected to each of these first and second
The pulse signal is generated in response to the comparison signals of In addition,
The filter voltage from the filter circuit 64 is applied to both voltage dividers 71
．． 72 between each divided voltage.

Therefore, in the drive circuit 75, the transistor Tr
is intermittently conductive in response to each pulse signal from the monostable multipipe lake 74, and the double-throw contact 75e is intermittently turned on under the intermittent excitation of the electromagnetic coil 75b in response to the intermittent conduction of the transistor Tr. is intermittently applied to the fixed contact 75d.

Then, the DC motor M is connected to the fixed contact 75 of the double throw contact 75e.
d, power is intermittently supplied from the battery B through the connection terminals 21 and 22 of the ignition switch IG and the wiper switch 20, and the wiper blade 11 rotates under the decelerated rotation of the speed reducer. It is intermittently slid back and forth across the wiping area.

As explained above, even if there are no raindrops that adhere to both lateral toothed electrodes 32 and 33 of the raindrop detector 30 in light rain, the first square wave timer signal generated over time from the timer oscillator 51 Since the intermittent wiping action of the windshield wiper 10 can be ensured as described above in conjunction with the variable period, it is possible to remove adhering raindrops due to light rain from the wiping area of the front windshield.

In addition, in the above-described operation, both lateral toothed electrodes 32 and 33 of the raindrop detector 30 are activated at the times indicated by the respective symbols in FIG.
If it is assumed that raindrops repeatedly adhere over the period of time, the capacitance between the two horizontal toothed electrodes 32 and 33 decreases temporarily each time the raindrops adhere, and each converted voltage from the current-voltage conversion circuit 53 becomes
At the high level (or at the low level), as shown by symbol C3 (or C4) in FIG. 7, a positive (
or negative), and the amplification circuit 55 sequentially generates amplified voltages (see respective symbols d3 and d4 in FIG. 7). In this case, each amplified voltage d3 corresponds to each second peak value C3 of the converted voltage from the electric-voltage conversion circuit 53, and each amplified voltage d4 corresponds to each second peak value C3 of the converted voltage from the current-voltage conversion circuit 53. 2 correspond to the peak value C4, respectively.

However, each amplified voltage d3 from the amplifier circuit 55 is applied to the voltage divider 7.
1 and each amplified voltage d4 from the amplifier circuit 55 is lower than the divided voltage from the voltage divider 72, the comparator circuit 73
3. d4, the first and second comparison signals (seventh
In the figure, each symbol g3. (see g4). This means that the comparison circuit 73 receives the first and second comparison signals gl and C2.
This means that in addition to the first and second comparison signals g3 and C4 are also generated.

Therefore, the monostable multi-bi break 74 is the comparator circuit 73.
In order to intermittently conduct the transistor Tr by sequentially generating pulse signals in response to not only the first and second comparison signals g1 and C2 but also the first and second comparison signals g3 and C4, the relay Fixed contact 7 of double throw contact 75e of Ry
The number of intermittent wiping operations performed by the windshield wiper 5d increases by an amount corresponding to the first and second comparison signals g3 and C4, and the number of intermittent wiping operations performed by the windshield wiper 10 also increases accordingly. In other words, even if the number of raindrops adhering to both lateral toothed electrodes 32 and 33 is small due to light rain, at a time determined by the number of adhering raindrops and at a frequency corresponding to the sum of the first variable period of the timer oscillator 51. Since the number of times of intermittent wiping of the windshield wiper 10 can be ensured, raindrops adhering to the front windshield can be appropriately removed from the front windshield without causing the front windshield to be wiped insufficiently even during light rain.

After that, if heavy rain falls, this heavy rain will fall on both the droplet detectors 30 and 40. At this time,
Mud on each surface of both side toothed electrodes 32 and 33 of the raindrop detector 30.
If dust or the like is attached, if raindrops from heavy rain adhere to the double tooth electrodes 32, 33, a water film will be formed over the double tooth electrodes 32, 33 due to the mud, dust, etc. mentioned above. It will be done.

Therefore, even if raindrops during heavy rain repeatedly adhere to the double-side toothed electrodes 32.33 in such a state, the double-side toothed electrodes 32.
The capacitance change between 33 is reduced, and the raindrop detector 3
Detection of raindrops by 0 becomes impossible.

However, in the raindrop detector 40, both electrodes 42 and 43
However, since they are arranged at intervals somewhat narrower than the diameter of raindrops during heavy rain, each raindrop that adheres to both electrodes 42° and 43 The water adheres to both electrodes 42 and 43 and simultaneously scatters without forming a water film. Therefore, in response to the temporary adhesion of each raindrop, the capacitance between the electrodes 42 and 43 repeatedly and temporarily decreases, and each converted voltage from the current-voltage conversion circuit 63 becomes or at the time of falling), as shown by the symbol if (or i2) in FIG. 8, positive ( or negative) to form a peak value.

Therefore, when each converted voltage from the current-voltage conversion circuit 63 having such a peak value is generated as a filter voltage by the filter circuit 64, the positive peak value of this filter voltage becomes the divided voltage from the voltage divider 71. voltage, and the negative peak value of the same filter voltage is lower than the divided voltage from the voltage divider 72, so the comparator circuit 73
4 in response to the level reversal of the filter voltage from the first
as well as! 2 comparison signals are alternately generated, and in response to each of these first and second comparison signals, the monostable multi-bi break 7
4 sequentially generate pulse signals. In such a case, the generation interval of the first and second comparison signals from the comparison circuit 73, that is, the generation interval of the pulse signal from the monostable multivibrator 74, becomes very narrow in relation to the second variable period of the timer oscillator 61. There is. In this way, when a pulse signal is generated from the monostable multivibrator 74 over time, the transistor Tr is intermittently conductive at the generation interval of the pulse signal, thereby intermittently closing the double-throw contact 75e of the relay Ry to the fixed contact 75d. In response to each of these inputs, the windshield wiper 10 intermittently performs a wiping operation.

In other words, even if the raindrop detector 30 is unable to detect raindrops as described above due to heavy rain, the raindrop detector 40 that replaces the raindrop detector 30 can detect raindrops accurately during heavy rain. Since the intermittent wiping action of the windshield wiper 10 can be ensured in conjunction with the second variable cycle of the timer oscillator 61, raindrops attached to the front windshield can be reliably removed even during heavy rain. In such a case, since the second variable period is selected to be short, the wiping action of the windshield wiper 10 becomes almost continuous.

Next, a modification of the embodiment described above will be explained with reference to FIG. It has the characteristics of The signal processing circuit 80 has both voltage dividers 81 and 82, and the voltage divider 81 is constituted by the raindrop detector 40 described in the previous embodiment and a resistor 81a. The raindrop detector 40 is grounded at its electrode 42, and the electrode 43 of the raindrop detector 40 receives a DC voltage (+Vcc) from the DC power supply via a resistor 81a.
It is connected to the same DC power supply in order to be given the same power. Therefore, the voltage divider 81 divides the DC voltage (+Vcc) by the capacitance between the two electrodes 42 and 43 of the raindrop detector 40 and the resistance value of the resistor 81a, and uses this as the divided voltage for the electrode 43 (
That is, it is generated from the output terminal).

The voltage divider 82 has a resistor 82a, and this resistor 82
a is grounded at one end and connected to a resistor 82 at the other end.
It is connected to the DC power supply via b to receive a DC voltage (+Vcε) from the DC power supply. Therefore, the voltage divider 82 divides the DC voltage (+Vcc) between the resistors 82a and 82a.
, 82b, and this divided voltage is applied to both resistors 82a, 82b.
2b is generated from the common terminal (ie, the output terminal). In such a case, the divided voltage from the voltage divider 882 is
The voltage is selected to be lower than the divided voltage from the voltage divider 81 when no raindrops are attached to the electrodes 42 and 43, and higher than the divided voltage from the voltage divider 81 when raindrops are attached to both the electrodes 42 and 43.

The comparator 83 generates a comparison signal at a low level (or high level) when the divided voltage from the voltage divider 81 is higher (or lower) than the divided voltage from the voltage divider 82. The output terminal of 83 is connected to the DC power supply through a resistor 83a so as to be supplied with a DC voltage (+Vcc) from the DC power supply. The multivibrator 84 repeatedly generates a pulse signal at short intervals every time the comparison signal from the comparator 83 rises. The transistor 85 receives each pulse signal from the multivibrator 84 through both resistors 85a, 85a, and is intermittently turned on to connect both diodes 73 of the comparator circuit 73 in the previous embodiment.
The anodes a and 73b (ie, the input terminals of the monostable multipipe lake 74) are intermittently grounded. This means that the monostable multipipe rake 70 has both diodes 73a
.

73b is meant to generate a pulse signal in response to the intermittent grounding of each anode of 73b. Note that the short period corresponds to the second variable period described in the embodiment.

In this modified example configured as above, if heavy rain falls, even if the raindrop detector 30 is unable to detect raindrops as in the case described in the previous embodiment, the raindrop detector 40 The capacitance between the electrodes 42, 43 decreases repeatedly and temporarily as each raindrop temporarily attaches to the electrodes 42, 43 as in the previous embodiment, and the divided voltage from the voltage divider 81 is divided. The voltage is repeatedly temporarily lowered than the divided voltage from the voltage generator 82, and the comparison signal generated from the comparator 83 rises repeatedly.

Then, the multipipe rake 84 sequentially generates a pulse signal every time the comparison signal from the comparator 83 rises, and in response to each of these pulse signals, the transistor 85 is intermittently turned on and the input terminal of the monostable multivibrator 70 is intermittently turned on. The monostable multi-pipe rake 70 sequentially generates pulse signals. In this way, when a pulse signal is generated from the monostable multivibrator 74 over time, the transistor Tr is intermittently conductive at the generation interval of the pulse signal, so that the double-throw contact 75e of the relay R)F is connected to the fixed contact 7.
5d is intermittently turned on, and the windshield wiper 10 intermittently performs a wiping operation in response to each turn-on.

In other words, even if the raindrop detector 30 is unable to detect raindrops as described above due to heavy rain, the raindrop detector 40 that replaces the raindrop detector 30 can accurately detect raindrops during heavy rain. Since the intermittent wiping action of the windshield wiper 10 can be ensured in relation to the period of each pulse signal from the multivibrator 84, raindrops attached to the front windshield can be reliably removed even during heavy rain. In this case, since the period of the pulse signal from the multi-pipe rake 84 is selected to be short, the wiping action of the windshield wiper 10 becomes almost continuous.

Next, referring to FIG. 10, another modification of the above embodiment will be explained. In this modification, a signal processing circuit 90 is adopted in place of the signal processing circuit 60 in the above embodiment. There are structural characteristics. The signal processing circuit 90 has both voltage dividers 91 and 92.
is the raindrop detector 40 and the resistor 91 described in the above embodiment.
It is composed of a. The raindrop detector 40 is grounded at its electrode 42;
3 receives a DC voltage (+V) from the DC power supply via a resistor 91a.
cc) is connected to the same DC power supply.

Thus, the voltage divider 91 connects both electrodes 42 .
The DC voltage (+Vcc) is divided by the capacitance between the electrodes 43 and the resistance value of the resistor 91a, and this is generated from the electrode 43 (ie, the output terminal) as a divided voltage.

The voltage divider 92 has a resistor 92a, and this resistor 92
a is grounded at one end and connected to a resistor 92 at the other end.
It is connected to the DC power supply via b to receive a DC voltage (+Vcc) from the DC power supply. Therefore, the voltage divider 92 divides the DC voltage (+Vcc) into both resistors 92a.
, 92b, and this divided voltage is applied to both resistors 92a, 9.
2b is generated from the common terminal (ie, the output terminal). In such a case, the divided voltage from voltage divider 92 is
The voltage is selected to be lower than the divided voltage from the voltage divider 91 when no raindrops are attached to electrodes 42 and 43, and higher than the divided voltage from the voltage divider 91 when raindrops are attached to both electrodes 42 and 43. Comparator 93 generates a comparison signal at low level (or high level) when the divided voltage from voltage divider 91 is higher (or lower) than the divided voltage from voltage divider 92.

Transistor 94 receives a comparison signal from comparator 93 via both resistors 94a, 94a, and is intermittently conductive every time this comparison signal rises, intermittently turning on electromagnetic coil 75b of relay Ry, regardless of transistor Tr in the embodiment described above. Excite to.

In this modified example configured as above, if heavy rain falls, even if the raindrop detector 30 is unable to detect raindrops as in the case described in the previous embodiment, the raindrop detector 40 The capacitance between the two electrodes 42, 43 decreases repeatedly and temporarily as each raindrop temporarily attaches to the electrodes 42, 43 as in the previous embodiment, and the divided voltage from the voltage divider 91 is divided. The voltage is repeatedly temporarily lowered than the divided voltage from the voltage generator 82, and the comparison signal generated from the comparator 83 rises repeatedly.

Then, the transistor 85 connects both resistors 85a.

In cooperation with 85a, conduction occurs intermittently every time the comparison signal from comparator 93 rises, and in response, relay R
y connects the double-throw contact 758 to the fixed contact 7 by intermittent excitation of the electromagnetic coil 75b, regardless of the transistor Tr.
5d intermittently to bring about intermittent wiping operation of the windshield wiper 10.

In other words, even if the raindrop detector 30 is unable to detect raindrops as described above due to heavy rain, the raindrop detector 40 that replaces the raindrop detector 30 will detect raindrops based on its accurate raindrop detection function during heavy rain. The intermittent wiping action of the windshield wiper 10 can be ensured in conjunction with the intervals of intermittent reduction in capacitance between the two electrodes 42 and 43 of the detector 40, so that even during heavy rain, raindrops adhering to the front windshield can be removed. can be reliably removed. In this case, the interval at which the capacitance decreases between the electrodes 42 and 43 becomes shorter due to the interval between each raindrop during heavy rain, so that the wiping action of the windshield wiper 10 becomes almost continuous.

In addition, in the above embodiment, both the droplet detectors 30 and 40
Although an example has been described in which the raindrop detector 30 is integrally formed, a well-known electrode facing type raindrop detector is adopted as the raindrop detector 30, and the raindrop detector 40 is formed as shown in FIG. The seed electrodes 32 and 33 may be omitted.In such a case, when configuring the raindrop detector 40 as a separate body, as shown in FIG. 12 or 13, the raindrop detector 40A Alternatively, it may be configured and implemented as 40B.

The raindrop detector 40A includes a pair of rectangular parallelepiped insulating bases 44a, 44b that are arranged side by side on the upper surface of the substantially horizontal portion of the bonnet with a space between them, and each of these insulating bases 44a, 44.
It is composed of a pair of elongated electrodes 45a and 45b provided opposite to each other on the upper surface of the upper surface of the electrode b.
b and the height of both box edge substrates 44a, 44b are such that raindrops during light rain can adhere across both electrodes 45a, 45b, and raindrops during heavy rain can adhere across both electrodes 45a, 45b. The electrodes 45a and 455 are selected so that they immediately fall into the space between the electrodes 45a and 455. The raindrop detector 40B includes a clear water insulating base 46 disposed on the upper surface of the substantially horizontal portion of the bonnet, and an inclined upper surface 46a provided on the insulating base 46, mutually disposed along the inclination direction of the upper surface 46a. It is composed of a pair of longitudinal electrodes 472 and 47b arranged in parallel to face each other, and the interval between these electrodes 47a and 47b is selected in the same manner as in the case of both electrodes 45a and 45b.

In the raindrop detector 40A, each raindrop during heavy rain adheres to both electrodes 45a and 45b and simultaneously falls between both box edge bases 44a and 44b, so that each raindrop during heavy rain can be reliably detected. obtain.

On the other hand, in the raindrop detector 40B, each raindrop during heavy rain adheres to both electrodes 47a and 47b, and at the same time, along the upper surface portion of the insulating base 46 between the two electrodes 47a and 47b, due to the flood control action of the insulating base 46. (Thus, as described above, each raindrop can be reliably detected during heavy rain. In addition, in the above embodiment, the present invention is applied to the windshield wiper 10 for a vehicle. Although an example has been described, the present invention is not limited to this, and the present invention may be applied to windshield wipers for ships, aircraft, etc.

[Brief explanation of drawings]

1 and 2 are overall configuration diagrams of a control system according to the present invention applied to a vehicle windshield wiper, and FIG.
Figures 4 and 4 are detailed circuit diagrams of the electric control circuit in Figure 1, Figure 5 is an enlarged perspective view of the dual-use drop detector seen from the front in Figure 2, and Figure 6 is an enlarged view of the same from the rear. Perspective view,
7 and 8 are input/output waveform diagrams of each electric element in FIGS. 3 and 4, FIG. 9 is a detailed circuit diagram showing a modification of the signal processing circuit in FIG. 4, and FIG. 10 is the same. A detailed circuit diagram showing a modified example of the raindrop detector, and FIGS. 11 to 13 are perspective views showing each modified example of the raindrop detector. Explanation of symbols 10...Windshield wiper, 30, 40°40
A, 40B... Raindrop detector, 32.33... Comb tooth electrode, 41.42, 45a, 45b, 47a, 47b...
・Electrode, EC...Electric control circuit.

Claims (1)

[Claims] This is applied to windshield wipers that operate to wipe away raindrops when they adhere to the windshield, and has a pair of opposing electrodes that are arranged opposite to each other. The windshield comprises a raindrop detection means for detecting a change in impedance between the opposite electrodes and generating the detected change as a raindrop detection signal, and a drive signal generation means for generating a drive signal in response to the raindrop detection signal. In a control system in which the wiper performs a wiping operation in response to the drive signal, the wiper has a pair of auxiliary electrodes arranged opposite to each other, and only when raindrops during heavy rain adhere to both auxiliary electrodes. Auxiliary raindrop detection means is provided for detecting a change in impedance between the auxiliary electrodes and generates the same as an auxiliary raindrop detection signal, and the drive signal generation means generates the drive signal in response to the auxiliary raindrop detection signal as well. A control system for a windshield wiper, characterized in that: