Rainfall sensor and control method

Abstract

The invention provides a rainfall sensor and a control method. The control method comprises the following steps that: when a power supply of a system is switched on, the light emitted by a light-emitting element, after reflected by a windscreen of a vehicle, is received by a receiving element and then is converted into an electrical signal through a photoelectric conversion circuit; a control unit performs analog-to-digital conversion on the electrical signal acquired at the first time to acquire the corresponding digital signal, judges whether the digital signal is in the preset reference range or not to determine whether to transmit the corresponding control signal to one or both of the controlled photoelectric conversion circuit and a controlled power adjusting circuit or not so as to determine a standard value; the control unit compares the acquired digital signal with the standard value to determine to perform fine adjustment on the standard value or to send out a control signal for adjusting a windscreen wiper; and when the standard value after the fine adjustment excesses the preset reference range, the control unit transmits a power control signal to the controlled power adjusting circuit again, so that the standard value can be corrected at any time according to the actual condition and a manual calibrating process is saved.

Description

technical field [0001] The invention relates to a rain sensor and a control method. Background technique [0002] In the process of driving a vehicle in rainy days, the driver often needs to manually adjust the running speed of the wiper according to the current amount of rain, so it is easy to cause traffic accidents due to reduced attention to road conditions. In order to avoid this situation, in modern automotive electronic systems, rain sensors are often used to collect rainfall signals, and based on this, calculate and determine the current appropriate wiper speed gear, and communicate with the wiper actuator through CAN or LIN bus. Communication, so that the wiper actuator can automatically adjust the wiper speed output according to the amount of rain, so that the driver can concentrate on driving the vehicle. For example, the Chinese patent document with application number: 200620076000 provides a car wiper control device . [0003] Commonly used rain sensor such as...

AI Technical Summary

Problems solved by technology

[0005] First: Because there is a difference in the optical path lens of the rain sensor between different rain sensors of the same model, and there is a difference in the light reflectivity of the front windshield of the car between different car glasses of the same model, so that even In the same situation where no raindrops are attached, the reflected luminous flux obtained by the light sensor is also different, and finally the analog signal value obtained by the microprocessor is also different.

Therefore, after the rain sensor is installed on the car, it must pass the detection equipment so that the rain sensor can learn the value of the analog signal given by the receiver without raindrops attached. This process is carried out by the car factory or 4S shop. The process of "calibrating the initial value of the sensor" will increase the workload of the car factory or 4S shop, that is, increase the production cost

[0006] Second: When the rain sensor has been used for a certain period of time, because the components of the transmitter and receiver are aging, so that there are no raindrops attached to the reflection area of ​​the front windshield, the output value of the receiver collected by the microprocessor, It will also be different from the initial value of the calibrated sensor, which will eventually lead to the "sensor initial value calibration" after the rain sensor has been working for a certain period of time. This process increases the workload and labor costs of the 4S shop.

Therefore, after working continuously for a period of time, the microprocessor cannot determine whether the change in the analog output of the receiver is caused by the change of the ambient temperature or the raindrops attached to the reflective area of ​​the front windshield.

Finally, it is difficult for the microprocessor (MCU) to calculate the accurate raindrop size, and then it is difficult to determine the appropriate wiper speed

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