| 摘要 |
A control circuit for a windshield wiper motor is disclosed in which the wiper motor is made automatically responsive to the presence of moisture droplets on the windshield causing the wiper blades to sweep back and forth at a rate dependent upon the level of precipitation encountered. By using a set of sample-and-hold circuits, bandpass filtering and a differential amplifier under microprocessor control, disturbances to the system due to changes in ambient light are linearly rejected and the system becomes immune to such disturbances. The system utilizes an intentional-retrigger algorithm enabling the system to detect water droplets that miss the sensor yet fall within the area of the windshield which is swept by the wiper blades. The system automatically adapts to windshields of differing transmittance and is not falsely set into action by electromagnetic disturbances.
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