Embedded self-test for rain sensors
AssigneeKelsey-Hayes Company
InventorGerard J. Zettler
Life of this patent
Estimating the term…
Abstract
A sensor for detecting moisture on an outside surface of a windshield is disclosed. The sensor includes an emitter circuit for emitting light energy, and a detector circuit for receiving light energy. A processor controls the emitter circuit and processes signals received from the detector circuit. A self test circuit is connected between the processor and the emitter circuit, the self test circuit is operably associated with the emitter circuit for generating a test signal for simulating the presence of moisture on the outside surface of the windshield.
Claims20
A sensor for detecting moisture on an outside surface of a windshield, said sensor comprising:
- an emitter circuit for emitting light energy;
- a detector circuit for receiving light energy;
- a processor for controlling the emitter circuit and processing signals received from the detector circuit;
- and
- a self test circuit connected between the processor and the emitter circuit, the self test circuit being operably associated with the emitter circuit for generating a test signal for simulating the presence of moisture on the outside surface of the windshield.
A rain sensor for detecting moisture on an outside surface of a windshield, said rain sensor comprising:
- a photoemitter circuit for transmitting infrared light energy into the windshield;
- a photodetector circuit for receiving light energy which is internally reflected from the outside surface of the windshield;
- a processor for controlling the photoemitter circuit and processing signals received from the photodetector circuit;
- a windshield wiper circuit connected to the processor for receiving control signals from the processor;
- and
- a self test circuit connected between the processor and the photoemitter circuit, the self test circuit including a resistor connected to ground via a transistor, the processor being connected to the transistor for biasing the transistor between an on state and an off state for generating a test signal for simulating the presence of moisture on the outside surface of the windshield.
A method for testing a rain sensor circuit for detecting moisture on the outside surface of a windshield comprising:
- providing an emitter circuit for transmitting light energy, said emitter circuit including a photoemitter in series with a first resistor for conducting current through the photoemitter;
- providing a detector circuit for receiving light energy;
- providing a processor for controlling the emitter circuit and processing signals received from the detector circuit;
- providing a self test circuit connected between the processor and the emitter circuit, the self test circuit including a second resistor in parallel with the first resistor, the second resistor being connected to ground via a transistor;
- generating a pulse signal for biasing the transistor;
- and
- switching the transistor between an on state and an off state, the transistor changing the current through the photoemitter.
Dependencies are inferred from the claim text.