JPH0457533B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a raindrop sensing type automatic wiper drive device, and is particularly intended to impose a time limit on the accumulation operation of raindrop pulses.

[Conventional technology]

The conventional raindrop sensing type automatic wiper drive device is
As shown in the figure, the raindrop pulses from the raindrop sensor 1 are integrated by the integrating circuit 2, and the integrated value is calculated by the comparing circuit 3.
In many cases, the integrated value is compared with a predetermined threshold value, and when the integrated value exceeds the threshold value, the relay 4 is turned on and the wiper motor 5 is operated. Although the mechanical part of the wiper is not shown, after one reciprocating operation due to the rotation of the motor 5, a reset (RST) is applied to the integral circuit 2 by an operation completion detection switch called a cam switch.
The output of comparison circuit 3 is inverted and relay 4 is turned off. Since the integrating circuit 2 restarts the integrating operation from this point, the operating waveforms of each part become as shown in FIG. In other words, the wiper operation cycle is from one RST to the next RST, and this period becomes shorter as the amount of rainfall increases.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned method, since the value in the middle of integration is always held, the wiper operates even if the integrated value exceeds the threshold value for a long time (for example, one minute or more) or even if the integrated value exceeds the threshold value. Further, even if noise is integrated, malfunctions occur. However, in such a case, since the amount of rain is small, the wiper not only operates unnaturally, but also wipes the dry windshield, causing damage to the wiper blade.

The present invention attempts to eliminate the above-mentioned drawbacks by placing a time limit on the raindrop pulse accumulation operation.

[Means for solving problems]

The present invention provides an automatic wiper drive device that integrates raindrop pulses from a raindrop sensor, and each time the integrated value exceeds a predetermined threshold, the wiper is moved back and forth once and the integrated value is reset. The present invention is characterized in that when the integrated value does not exceed the threshold value even after a certain period of time has elapsed since the start of integration, the integrated value is controlled to be reset.

[Effect]

If you put a time limit on the raindrop pulse integration operation,
When the amount of rainfall is small, a reset occurs before the integrated value reaches the threshold value, making it possible to avoid unnecessary wiper operations.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, and numeral 10 is an electronic control unit (ECU) using a microcomputer that performs integration of raindrop pulses, comparison of the integrated values, counting of integrated time, resetting when time is over, etc. , 20 is a wiper motor,
This is a wiper device that includes a cam switch, wiper blade, etc.

FIG. 3 is a flowchart of wiper control by the ECU 10, in which processing corresponding to the integrating circuit 2 and comparing circuit 3 in FIG. 4 is performed by software. Also, a timer that counts the accumulated time is realized by a software counter or the like. In addition to the reset RST performed when the integrated value exceeds the threshold value, the reset RST' is also performed when the integrated time exceeds a certain value T. In the former case, the process moves to wiper operation processing, but in the latter case, the process enters a waiting loop in order to avoid repeating the reset RST' needlessly.

FIG. 2 is an operational waveform diagram, showing in order the reset RST due to exceeding the threshold value, the reset RST' due to time over, and the RST due to exceeding the threshold value. The value of the fixed time T is set to 60 seconds, for example.

The purpose of the taillight signal input to the ECU 10 is to change the threshold value between night and daytime, and the purpose of the vehicle speed signal is to change the threshold value depending on the speed. The present invention can also be applied to an analog circuit as shown in FIG.

〔Effect of the invention〕

As described above, according to the present invention, the accumulated value of raindrop pulses is reset at regular intervals, so that if the accumulated value exceeds a predetermined value for a long time, the wiper may operate, or noise may be accumulated. Unnatural or malfunctioning operations such as wiper activation can be prevented, and damage to wiper blades and window glass can also be prevented.

[Brief explanation of the drawing]

1 to 3 are block diagrams, operational waveform diagrams, and flowcharts showing one embodiment of the present invention;
1 and 5 are a block diagram and an operating waveform diagram of a conventional automatic wiper drive device. In the figure, 1 is a raindrop sensor, 2 is an integrating circuit, 3 is a comparison circuit, 10 is an electronic control unit, and 20 is a wiper device.

Claims (1)

[Claims] 1 The raindrop pulses from the raindrop sensor are integrated, and each time the integrated value exceeds a predetermined threshold, the wiper is activated.
In an automatic wiper drive device that operates reciprocally and resets the integrated value, the integrated value is reset if the integrated value does not exceed the threshold even after a certain period of time has elapsed from the start of integrating the raindrop pulses. An automatic wiper drive device characterized by controlling.