WINDSHIELD WIPER CONTROL SYSTEM

摘要

In an intermittent windshield wiper system in which the time between wiping cycles depends upon the degree of dryness of the windshield and upon the speed of the wiper blades on the downstroke of the wiping cycle toward the dwell position of the wiper blades, a circuit is provided to regulate the speed of the motor on the downstroke making use of the same transistor device (20) that is used in controlling the energization of the motor to achieve intermittent operation. The motor is a three-brush motor (10) and speed regulation is achieved by deriving signals from one or two of the brushes and applying it to the input electrode (60) of the transistor device. The regulated speed of the motor can be manually controlled (31) to provide a manual adjustment to the sensitivity of the system to the degree of dryness of the windshield. The motor may be electrodynamically braked at the end of each wiping cycle and the electrodynamic braking circuit (90, 100) is also used to apply reverse current to the motor when the windshield wiper system is turned off to drive the windshield wiper blades to a depressed park position.