Control circuit for a windshield wiper system
First Claim
1. A control circuit for a vehicle windshield wiper system, comprising:
- means for producing an ON signal of a certain duration;
a relay having a moveable contact, a normally open contact, a normally closed contact, and a coil for actuating said moveable contact, said contacts being adapted to activate a wiper motor when said coil is energized;
a relay drive transistor for energizing said coil when said ON signal is produced from said ON signal producing means;
auto stop switch means coupled to an output shaft of said wiper motor and having a drive position and a brake position for maintaining supply of electric current to said wiper motor immediately after said coil of said relay is de-energized until said auto stop switch means takes said drive position; and
a relay energization retaining circuit which maintains supply of electric current to said wiper motor when the ON signal for the relay drive transistor is terminated as long as said auto stop switch means is at said brake position until said auto stop switch means subsequently moves on to said drive position.
1 Assignment
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Accused Products
Abstract
In a control circuit for a vehicle windshield wiper system, a relay energization retaining circuit forms a self-sustaining circuit jointly with a relay drive transistor for driving a wiper relay, and maintains supply of electric current to the wiper motor when the ON signal for the relay drive transistor is terminated as long as the auto stop switch is at the brake position until the auto stop switch subsequently moves on to the drive position. Therefore, when the signal which normally turns on the relay drive transistor is terminated during the time the auto stop switch is at the brake position, because the relay energization retaining circuit keeps the wiper motor running until the auto stop switch changes over from the brake position to the drive position, and the auto stop switch then takes over the task of keeping the wiper motor running until the auto stop switch changes over from the drive position to the brake position, the termination of electric current to the wiper motor always occurs at the time when the auto stop switch changes over from the drive position to the brake position so that the distance or the angular range of the overrunning of the wiper motor is fixed without regard to the timing of terminating the ON signal. Thus, according to the present invention, the rest position of the wiper blade is fixed under all operating conditions.
10 Citations
6 Claims
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1. A control circuit for a vehicle windshield wiper system, comprising:
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means for producing an ON signal of a certain duration; a relay having a moveable contact, a normally open contact, a normally closed contact, and a coil for actuating said moveable contact, said contacts being adapted to activate a wiper motor when said coil is energized; a relay drive transistor for energizing said coil when said ON signal is produced from said ON signal producing means; auto stop switch means coupled to an output shaft of said wiper motor and having a drive position and a brake position for maintaining supply of electric current to said wiper motor immediately after said coil of said relay is de-energized until said auto stop switch means takes said drive position; and a relay energization retaining circuit which maintains supply of electric current to said wiper motor when the ON signal for the relay drive transistor is terminated as long as said auto stop switch means is at said brake position until said auto stop switch means subsequently moves on to said drive position. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification