JPH04310453A - Car speed judgement device and wiper control device provided with the same speed judgement device - Google Patents

Abstract

PURPOSE:To enable judgement of car speed at the time of rain without taking a car speed signal from a car in, and to compensate the intermittent time of wiper operation to match with feeling according to the car speed judged in this way. CONSTITUTION:Light receiving amount of light receiving units 2, 3 varies due to raindrops which passed detection beam B between the elements 2, 3, and a raindrop pulse is extracted from an oscillation modulation signal outputted according thereto. The pulse width of of raindrop pulse becomes small as the speed of car becomes high, and thus the car speed is judged by detecting the pulse width by means of a car speed judgement device. In a raindrop signal processor connected to the output side of a pulse elongation circuit 7, the intermittent time of wiper operation is compensated according to the judged car speed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed determination device based on raindrop pulses detected by a rain sensor, and a wiper control device equipped with the determination device.

0002

2. Description of the Related Art Generally, a rain sensor, for example an optical rain sensor, detects a raindrop pulse using a signal whose amplitude is modulated in accordance with changes in the amount of light received by raindrops. A so-called automatic wiper system has been proposed in which the intermittent period of wiper operation is controlled according to the magnitude and number of raindrop pulses detected in this manner.

[0003] Even if the amount of rain is constant, the number of raindrops detected per unit time increases as the vehicle speed increases. Since the wiper operation intermittent time is controlled to be shortened as the number of raindrops increases, the auto wiper system can be said to be a vehicle speed sensitive system.

However, from the point of view of movement feeling,
For example, if we improve the operating feeling at medium and low speeds of around 60 km/h, the problem of unfinished driving at low speeds and over-driving at high speeds will remain, and it will match the driver's feeling at all vehicle speeds. In order to perform the wiper operation, it is preferable to further correct the wiper operation time based on the vehicle speed. Conventionally, in order to perform such vehicle speed correction, a vehicle speed signal is taken in from the vehicle, which requires harness wiring, which poses problems such as poor installation performance.

[0005]

[Problems to be Solved by the Invention] The present invention has been made based on the above technical background, and is capable of capturing a vehicle speed signal from the vehicle by using the raindrop pulse detected by the rain sensor. This system allows the vehicle speed to be determined when it is raining. Further, based on the vehicle speed determined in this way, the intermittent time of wiper operation can be corrected to match the driver's feeling.

[0006]

[Means for Solving the Problems] In order to solve the problems, according to one embodiment of the present invention, vehicle speed determination is characterized in that the vehicle speed is determined according to the pulse width of a raindrop pulse detected by a rain sensor. Equipment is provided.

According to another aspect of the present invention, a wiper control device includes a vehicle speed determining device configured as described above, and corrects the intermittent time of wiper operation in accordance with the determined vehicle speed. is provided.

[0008]

According to the above structure, the pulse width of the raindrop pulse detected by the rain sensor becomes smaller as the vehicle speed increases, so that changes in the vehicle speed during rain can be determined from changes in the pulse width. Furthermore, by correcting the intermittent time of the wiper operation according to the vehicle speed determined in this way, it becomes possible to correct the feeling of the wiper operation based on the vehicle speed without particularly taking in a vehicle speed signal from the vehicle.

[0009]

[Embodiment] FIG. 1 shows the configuration of a wiper control device equipped with a vehicle speed determination device as an embodiment of the present invention.
The light emitting element 2 is pulse-lit by the D driver 1, and the amount of light received by the light receiving element 3 changes due to raindrops passing through the detection beam B between the light emitting element 2 and the light receiving element 3.

As a result, the preamplifier 4 connected to the output side of the light receiving element 3 outputs a signal whose amplitude is modulated according to the size of the raindrop, as shown in FIG. 5, the amplitude modulated signal is detected and a raindrop pulse signal as shown in FIG. 1(b) is extracted. Note that this raindrop pulse signal is continuously formed according to the number of raindrops passing through the detection beam B. The raindrop pulse signal is then inverted and amplified by the pulse amplifier 6, and its peak value (proportional to the diameter of the raindrop) is set to H, for example, as shown in FIG. 1(c).

The pulse width of the raindrop pulse signal (shown in FIG. 1(c) above) thus outputted from the rain sensor is relatively short (usually consisting of high frequency components of 500 Hz to 20 kHz); There may be cases where it is not possible to distinguish the noise from the noise generated by a car. Therefore, the raindrop pulse signal is then input to the pulse extension circuit 7, and the pulse extension circuit (including the charging/discharging circuit) is then inputted as shown in FIG. 1(d).
As shown in , the change in the peak value H is expanded into a low frequency pulse signal that corresponds to the change in the pulse width W,
Thereby, even if the noise as described above is superimposed, it becomes easy to distinguish it from the noise. Note that when the diameter of the raindrop is large and the peak value H increases, the output waveform of the pulse expansion circuit becomes as shown by the dotted line in FIG. The pulse width W begins to increase.

The raindrop signal pulse-stretched as described above is then input to a raindrop signal processor, in which it is converted into a predetermined (for example, low level) square wave pulse by a comparator having, for example, a predetermined threshold value. The input level is then read by a microcomputer or the like every millisecond, and for example, if the read level is low, it is determined that there is a raindrop pulse; on the other hand, if the read level is high, it is determined that there is a raindrop pulse. In this case, it is determined that there is no raindrop pulse. Each time it is determined that the raindrop pulse is present, a counter is sequentially counted up, and each time the integrated value reaches a predetermined threshold, the wiper is operated.

Further, in FIG. 1, reference numeral 8 denotes a vehicle speed determining device according to the present invention, and the output of the pulse amplifier 6 (that is, the raindrop pulse signal shown in FIG. 1(c)) is input to the vehicle speed determining device 8. be done. Here, the speed at which the raindrops pass through the detection beam B increases when the vehicle is moving at high speed, so the pulse width of the raindrop pulse signal is inversely proportional to the vehicle speed, and the higher the vehicle speed, the smaller the pulse width becomes. Therefore, in the present invention, the vehicle speed during rain is determined by detecting the pulse width.

In order to detect the pulse width of the raindrop pulse signal, the vehicle speed determination device 8 shown in FIG. 1 is provided with, for example, a comparator 81, a frequency multiplying circuit 82, and a counter circuit 83. . As a result, the raindrop pulse signal inputted from the pulse amplifier 6 is first shaped into a square wave pulse of a predetermined level by the comparator 81 having a predetermined threshold value. Here, when the vehicle speed changes from, for example, 0 to 100 km/hour, the pulse width of the raindrop pulse changes from, for example, 2 msec to 50 μs.
It changes up to ec. Therefore, the square wave pulse outputted from the comparator 81 is converted into the frequency multiplier circuit 8, for example.
2, the pulse width is multiplied as appropriate, and the thus multiplied pulse width is counted by a counter circuit 83.

[0015] Then, the count value corresponding to the pulse width counted in this manner is compared with a predetermined threshold value (for example, two types of threshold values are set as the threshold value), and thereby the count value , Therefore, if the pulse width is smaller than a predetermined threshold, the vehicle speed is determined to be in a high speed state, whereas if the count value, and therefore, the pulse width is larger than a predetermined threshold, the vehicle speed is determined to be in a low speed state. It will be judged. Note that instead of providing the counter circuit 83 as the hardware described above, the multiplied pulse width may be counted by, for example, the microcomputer provided in the raindrop signal processor described above.

FIG. 2 is a flowchart showing the operation procedure of the raindrop signal processor when correcting the wiper operation intermittent time according to the vehicle speed determined by the vehicle speed determination device 8. First, step 1 is performed. As described above, in order to determine the presence or absence of a raindrop pulse, for example, every 1 msec, it is determined whether the 1 msec has elapsed. If YES, the presence or absence of a raindrop pulse is determined in step 2 (for example, as described above, this is determined based on the level read at that time). If YES, the count value (integrated value) K of the counter is incremented by 1 in step 3.

Next, in step 4, it is determined whether the vehicle speed determination device determines that the vehicle speed is high. If YES, proceed to step 5 and add a correction coefficient X1 (however, X1<1, for example 0.8) to the integrated value K of the counter.
It is determined whether the product K.X1 multiplied by . That is, in the case of the above-mentioned high speed, by multiplying the integrated value of the counter by a correction coefficient X1 smaller than 1 as described above, the intermittent time of the wiper operation is increased (the number of times the wiper is operated is thinned out),
Corrects the above-mentioned overpayment at high speed. Note that the correction coefficient X1
Instead of multiplying by , the control threshold R may be increased as appropriate.

If the determination in step 4 is negative, the process proceeds to step 6, where it is determined whether or not the vehicle speed is determined to be low. If the result is NO, the process proceeds to step 7, where the integrated value K of the counter is directly compared with the control threshold value R, and when K becomes greater than R, the process proceeds to step 9, where the wiper is activated. Activate once.

On the other hand, if the answer is YES in step 6, the process proceeds to step 8, where the product K×X2 is obtained by multiplying the integrated value K of the counter by a correction coefficient X2 (where X2>1, for example, 1.2). It is determined whether or not has become larger than a predetermined control threshold value R. If the answer is yes, the process proceeds to step 9 and the wiper is operated once. That is, in the case of the above-mentioned low speed, the intermittent time of the wiper operation is shortened (increasing the number of wiper operations) by multiplying the integrated value of the counter by a correction coefficient X2 larger than 1 as described above, and Correct the unpaid balance. In this case as well, the correction coefficient
Instead of multiplying by 2, the control threshold R may be lowered as appropriate. Then, in step 9 above, the wiper is set to 1.
Each time the counter is operated, the integrated value K of the counter is cleared in step 10.

[0020]

According to the present invention, the vehicle speed during rain can be determined without deteriorating the ease of installation due to taking in the vehicle speed signal from the vehicle. Furthermore, by simply adding one signal line from the rain sensor, the intermittent wiper operation time can be corrected to match the driver's feeling in accordance with the vehicle speed determined as described above.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of the device of the present invention and an output waveform diagram of each part.

FIG. 2 is a flow chart showing the operation procedure of the raindrop signal processor.

[Explanation of symbols]

1...LED driver 2...Light emitting element 3... Light receiving element 4...Preamplifier 5...Detection circuit 6...Pulse amplifier 7...Pulse expansion circuit 8...Vehicle speed determination device

Claims (2)

[Claims] 1. A vehicle speed determination device that determines vehicle speed according to the pulse width of a raindrop pulse detected by a rain sensor. 2. A wiper control device comprising the vehicle speed determining device according to claim 1, and correcting the intermittent time of wiper operation according to the determined vehicle speed.