JPH0533187B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a wiper drive device that automatically changes the wiper drive cycle according to the amount of rainfall, and particularly to a wiper drive device that automatically changes the wiper operating speed. It is something to do.

[Conventional technology]

Detects rainfall using a raindrop sensor and integrator,
A wiper drive device that automatically changes the operating cycle of the wiper according to the amount of rainfall generally keeps the wiper operating speed constant. An example is shown in FIG. In the figure, numeral 1 is a raindrop sensor that has a light emitting element and a light receiving element facing each other and converts the change in light intensity when a raindrop passes through the optical path between them into an electrical signal (raindrop pulse), and the output is integrated by an integrator 2. Ru.
The output voltage of the integrator 2 rises stepwise each time a raindrop pulse is input, and the rate of rise becomes faster as the frequency of raindrop pulses is higher or the diameter of the raindrop is larger, that is, the amount of rainfall is larger. 3 is a coparator, and when the integral output reaches a certain value ref1, switch _S1 is set to the a side, and the wiper motor M is switched from the power supply PS to the wiper motor M.
energize. As a result, when the wiper motor M starts rotating, the switch _S3 is switched from 0 to 1 by a cam (not shown), and the integrator 2 is reset (RST).
be done. As a result, when the output of comparator 3 is reversed, switch _S1 returns from a to b, but motor M
Since it is energized through switch _S3 , it continues to rotate, and when the wiper moves back and forth once and switch _S3 is turned off, motor M stops. Since the integrator 2 restarts integration immediately after being reset, the above-described operation is repeated. Therefore, the wiper operation interval changes depending on the rate of increase in the integral output (the amount of rainfall).

[Problem that the invention seeks to solve]

By the way, the operating speed of the wiper (the speed of one reciprocation) can be switched between high and low speeds by switching the excitation force of the wiper motor M. S ₂ is the switch for this purpose, and conventionally this has been operated manually. Here, we will consider a system in which a speed switching comparator 3' is added in order to automatically switch the switch _S2 according to the amount of rainfall. The reference value ref2 of the comparator 3' is set higher than the reference value ref1 of the comparator 3, and when the integral output exceeds ref2, the switch _S2 is switched from the low speed side to the high speed side. In this case, since there is a time delay until the integral output reaches re2 from ref1 at the time of switching the switch _S2 , if this continues, there will be an inconvenience that the wiper will switch from low speed to restraint in the middle of one wiper operation period. This is the first problem. The second problem is that the time from when the integrator 2 is reset until the wiper motor M stops varies depending on the difference in operating speed between the low-speed mode and the high-speed mode. This is the point where the integral output cannot reach ref2 when the mode is set, and as a result, it reaches ref2 when the mode returns to low speed mode, causing a kind of detection sensitivity fluctuation.

The present invention aims to provide an automatic cycle variable wiper drive device that does not have these problems and can automatically change the wiper operating speed depending on the amount of rainfall.

[Means for solving problems]

In the present invention, the output of a raindrop sensor is input to an integrating means, the integrated output is compared by a first comparing means, and when the integrated output reaches a reference value of the first comparing means, an operating speed switching type In a wiper drive device of an intermittent operation period variable type, when a wiper device is started and the wiper device starts operating, the integrating means is reset once and then restarts the integrating operation, and the output of the integrating means is set as a second reference. a second comparing means for comparing the output of the second comparing means after a predetermined period of time after the integrating means is reset; The wiper device is characterized by comprising a control means for switching the operating speed of the wiper device based on the stored contents.

[Effect]

The output of the second comparator does not directly switch the operating speed of the wiper, but passes it through the first and second latch circuits. The first latch circuit is used to determine the output of the second comparator at a fixed time after the start of integration, regardless of the wiper operating speed. The second latch circuit is for switching the operating speed after the wiper operation is completed. As a result, as shown in FIG. 3, a wiper drive device of an automatic variable operating period and automatic operating speed switching type can be realized without any inconvenience. This will be explained in detail below with reference to illustrated embodiments.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a time chart showing signal waveforms of various parts thereof. The configuration of FIG. 1 is the same as that of FIG. 3 with the addition of an integrator 2', a wideshot multi 4, D-type flip-flops (D-FF) 5 and 6, and an inverter 7. The raindrop sensor 1 generates a raindrop pulse A having an amplitude corresponding to the diameter of each raindrop. Integrators 2, 2' integrate this and increase the output voltages B, D in steps. Comparator 3,
3' is the reference value ref1 for the integral outputs B and D, respectively.
Compare with ref2, when the integral output is small, set the output to L,
When it is large, the output is set to H. C and E are respective outputs of comparators 3 and 3'. The one-shot multi 4 is activated at the same time as the signal F that resets the integrators 2 and 2' rises, and the output G is set to L for a certain period of time t. The rise of this signal G becomes the clock of D-FF5, and latches the output E of the comparator 3'. The inverter 7 inverts the reset signal F, and uses the rising edge of the inverted signal (the falling edge of F) as the clock for the D-FF6. This D-FF6 latches the output K of the previous stage D-FF5, and switches S ₂
A switching signal I is created.

Explain the operation. When the output B of the integrator 2 reaches ref1, the output of the comparator 3 becomes H (),
Switch _S1 is switched to side a. This result PS−S ₁
(a) Current flows through the motor M through the path −S ₂ −M, and the wiper operation starts. At this time, the output I of D-FF6
is L, and switch _S2 is connected to the low speed side. When the motor M rotates for a while, the cam switch _S3 changes from 0 to 1 and a reset signal F is sent.
becomes H, and at the rising edge, the integrators 2, 2' are reset, and at the same time, the one-shot multi 4 is activated. Thereafter, when the output D of the integrator 2' reaches ref2, the output E of the comparator 3' becomes H. However, at this point, the switch _S2 is not switched to the high speed side, and the motor M continues to rotate at a low speed. Then, when the one-shot multi 4 inverts its output G from L to H after a predetermined time t has elapsed, the output E of the comparator 3' is latched by the D-FF 5 at the rising edge. After that, when the wiper completes one reciprocating operation and the cam switch _S3 switches from 1 to 0, the reset signal F falls (), and the output of the inverter 7 which inverts it causes the output K of the D-FF5 to become D-. Latched to FF6. As a result, the output I of the D-FF6 becomes H, and the switch _S2 is switched from the low speed side to the high speed side. Note that when the rise of signal E is slower than the rise of signal G, the low speed mode remains.

Above mentioned ~ is one reciprocating operation period of the wiper, but in this example, due to heavy rainfall, the comparator 3 output C becomes H again at time ○a, which is earlier than the end time, so the next wiper operation is stopped. It starts without a period (if ○i is later, there will be a rest period). Next wiper operation period ~
Since is a high-speed mode, it completes in a shorter time than the low-speed mode of ~. However, in both modes, the timing to judge the output E of comparator 3' is
Since the timing is unified to ``at the time of reset'' and ``or'' after a certain period of time t, it is possible to avoid the inconvenience of sensitivity fluctuations caused by differences in integration times. In addition, since the mode switching timing (change point of signal I) is set to the completion of the previous wiper operation,
The inconvenience of switching the operating speed during the wiper operation does not occur. However, the time t of the one-shot multiplier 4 must be set to a value shorter than the wiper operating time in the high-speed mode. Further, when two integrators 2 and 2' are provided, flexibility is provided in that the rising edges of the signals C and E can be set not only by ref1 and ref2 but also by the integral constant. However, this is the same even if one unit is shared and its output is divided into voltages.

〔Effect of the invention〕

As described above, according to the present invention, a wiper drive device that automatically varies the intermittent operating cycle of the wiper according to the amount of rainfall is added with a function that automatically switches the wiper operating speed at a predetermined amount of rainfall. There are advantages to being able to do so.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a time chart showing signal waveforms of various parts thereof, and FIG. 3 is a block diagram showing an example of a conventional wiper driving device. In the figure, 1 is a raindrop sensor, 2, 2' are integrators, 3,
3' is a comparator, 4 is a one-shot multi,
5 and 6 are D type flip-flops (latch circuits), 7 is an inverter, M is a wiper motor, PS is a power supply, _S1 is a wiper start switch, _S2 is a wiper speed selection switch, _S3 is a cam switch (M to _S3 are each part of the wiper device).

Claims (1)

[Claims] 1. The output of the raindrop sensor is input to the integrating means, the integrated output is compared by the first comparing means, and when the integrated output reaches the reference value of the first comparing means, the operating speed switching type wiper device is activated. In an intermittent operation period variable wiper drive device, when the wiper device starts operating, the integrating device is reset once and then resumes the integrating operation, and the output of the integrating device is compared with a second reference value. a second comparing means for storing the output of the second comparing means a predetermined time after the integrating means is reset; A wiper drive device comprising: control means for switching the operating speed of the wiper device based on the operating speed of the wiper device.