Abstract: A compact rain sensor for mounting on the inner surface of a windshield includes collimator lenses and a detachable prismatic coupler to facilitate the mounting of emitters and detectors on a circuit board which is positioned parallel to the inner surface of the windshield. A thin optical coupler is adhesively secured to the windshield. A sensor housing is detachably secured about the outer edges of the coupler. Within the sensor housing, surface-mounted infrared emitters and detectors, as well as signal processing circuitry, are all mounted on a single printed circuit board secured in the housing. When the sensor housing is mounted on the coupler, the printed circuit board is parallel to the inner surface of the windshield and in close proximity thereto.

Abstract: Disclosed is an automatic windshield wiper control system which responds to sensed moisture in a manner which is responsive to changes in conditions, yet subjectively smooth. Moisture and noise sensitive signals from a sensor are digitized, and a functional block detects the reversals of the moisture sensing signal towards a quiescent level. These reversals are considered rain events and a method is disclosed for producing an ongoing measure of the frequency of these events. The resulting signal is representative of the flow rate of the raindrops impinging upon the moisture sensor. Another functional block with a logarithmic characteristic converts this quantity into an intensity value, in a manner which mimics human perception. A multiple time-constant averaging means maintains a value representative of the long-range prevailing conditions under which the device is operating.

Abstract: A device to facilitate the mounting of an optical sensor on a windshield glass using a clear adhesive tape is disclosed. The device holds the sensor, with tape exposed, in a vacuum chamber which is sealed against the glass. The chamber is evacuated, and the sensor is then pressed against the glass by the longitudinal movement of a drive shaft. The sensor may be installed with consistent force and with no trapped air pockets or air bubbles. Air pockets are a special concern because air pockets adversely effect the optical performance of the sensor. The vacuum chamber device may be controlled by a computer, and features a latching mechanism which prevents the sensor from making contact with the glass until the chamber is evacuated.

Abstract: Mounting of a sensing unit upon the interior surface of a vehicle windshield for detecting the presence of moisture upon the exterior surface and controlling operation of windshield wipers in response thereto is disclosed. The sensing unit comprises a block in which angularly oriented bores are disposed. Light pipes in a first set of the bores communicate with light sources for transmitting light to the outer surface of the windshield, and light pipes in a second set of the bores transmit light reflected from the outer surface to photo-detectors. The lower ends of the light pipes are coplaner with or raised slightly above the surface of the block which is to be secured to the windshield. The block is affixed to the interior surface of the windshield by a double faced adhesive interlayer which both securely adheres the block to the windshield surface and optically couples the light pipes to the windshield.

Abstract: A combination manual and automatic vehicle windshield wiper control system is provided which integrates a windshield moisture-sensing based wiper control system into an existing design of original equipment wiper system with minimum impact on manufacture and retrofit by using the existing vehicle wiring harness and existing connectors. The invention provides easy integration of a moisture-sensitive wiper control system into a class of vehicles in a manner which does not interfere with the operation of the standard or pulse-wipe systems already existing in the manual mode even if the moisture-sensitive system should fail for any reason. The moisture-sensing mode of operation replaces the delay or pulse mode.

Abstract: 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.

Abstract: A capacitive accelerometer system for detecting changes in G-forces and for producing a digital count value proportional to such changes. An oscillator-driven capacitive transducer of a unique design produces a voltage variation whose amplitude and frequency characteristics are a function of the direction and magnitude of the applied G-forces. The transducer itself comprises a pair of spaced-apart parallel plates disposed on opposite sides of a beam-supported movable plate which responds to changes in acceleration forces. The modulated signal is then demodulated and applied by a semiconductor switch actuated by a pulse from a microprocessor to a voltage-controlled current source. The current source varies the discharge rate of a precision capacitor.

Abstract: An electronic control system for windshield wipers on motor vehicles for initiating wiping action in response to the occurrence and level of precipitation on the windshield. A sensor unit comprising a block containing an array of photo-sensors arranged in a bridge configuration and a corresponding array of light sources is mounted on the inside surface of the windshield at a location traversed by the path of the vehicle's windshield wiper blades. The photo-sensor elements are oriented to normally receive light reflected back from the glass/air interface at the outside windshield surface from the photo-emitters, but when rain is present on the windshield, the light rays are scattered to create an unbalanced condition. The unbalancing of the bridge creates a signal which is demodulated in a synchronous demodulator and then applied via an automatic gain control (AGC) circuit to a window comparator.