Automatic wiper actuator for a vehicle window

• US 4,567,412 A
• Filed: 11/29/1984
• Issued: 01/28/1986
• Est. Priority Date: 11/29/1984
• Status: Expired due to Term

• Current Assignee: ITT Automotive Electrical Systems, Inc. (ITT, Inc.)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Graham, Donald E.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ro, Bentsu
• Application Number:
  US06/676,385
• Time in Patent Office: 425 Days
• Field of Search: 318/443, 318/444, 318/445, 318/449, 318/450, 318/483, 318/484, 318/DIG. 2, 15/250 C
• US Class Current: 318/483
• CPC Class Codes: B60S 1/0818 including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
• CPC Class Codes: B60S 1/0829 Oscillator-resonator rain sensor
• CPC Class Codes: Y10S 15/15 Moisture responsive
• CPC Class Codes: Y10S 318/02 Windshield wiper controls

Abstract

A control system for a motor driven wiper on a vehicle window comprises a voltage generator effective to generate a first rectangular voltage wave having a substantially constant frequency and duty cycle and apparatus effective to derive two additional rectangular voltage waves from the first: a second delayed from the first by a first delay and a third delayed from the first by a second delay dependent upon the capacitance of a capacitor affected by moisture on the vehicle window. One of the second and third rectangular voltage waves may also be inverted. The three rectangular voltage waves are provided to the inputs of an AND gate having an output effective to trigger a retriggerable monostable multivibrator having an energized output period longer in duration than a cycle of the rectangular voltage wave to drive the wiper motor when the level of moisture on the window in the vicinity of the capacitor is sufficiently high. The first delay may be adjustable by the vehicle operator to vary the moisture sensitivity of the system. If the capacitor is placed within the wipe pattern just above the inner wipe postion, a fully automatic control may be provided.

Claims

1. A control system for a motor driven wiper on a vehicle window comprising, in combination:

an oscillator effective to generate a rectangular voltage wave of supply and ground voltage levels having a substantially constant frequency and duty cycle;

an AND gate with three inputs and an output;

an inverter effective to invert the rectangular voltage wave and apply the inverted rectangular voltage wave to the first AND gate input;

first wave transformation means comprising a series diode and inverter with a first capacitor and first resistor connected from the junction of the diode and inverter to ground, the resistance of the first resistor being variably controllable by an operator of the vehicle, the first wave transformation means being connected from the oscillator to the second AND gate input, whereby it applies to said input the rectangular voltage inverted and delayed by a first time period;

second wave transformation means comprising a diode followed by two series inverters with a parallel second capacitor and second resistor connected from the junction of the diode and one of the series inverters to ground, the second wave transformation means being connected from the oscillator to the third AND gate input, the second capacitor being located adjacent the lower edge of the wiped portion of the vehicle window and responsive in capacitance to the presence of moisture on said wiped portion, whereby the second wave transfomation means applies to the third AND gate input the rectangular wave delayed by a second time period varying with said capacitance and thus with the moisture on the window;

a retriggerable monostable multivibrator connected to the output of the AND gate and effective, when triggered by common supply voltage levels on all three inputs, to generate an energized output of period longer than a cycle of the rectangular voltage wave; and

means responsive to the energized output of the retriggerable monostable multivibrator to activate the motor driven wiper to perform a wipe cycle, whereby the wiper system is automatically activated in response to moisture on the windshield and is further adjustable by the vehicle operator in sensitivity to moisture.