OPTICAL HIGHWAY LINE DETECTOR
First Claim
1. A detector for detecting light reflected from a light area on a surface, comprising:
- a photodetector positioned to receive light from a portion of the surface; and
a dynamic impedance element connected electrically in series with the photodetector to maintain the photodetector in condition to detect light reflected from a light area on the surface regardless of the ambient illumination of the surface.
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Accused Products
Abstract
A highway lane position detector including a photodetector for determining the existence of highway lines, wherein the detection circuitry maintains its detection ability over a wide range of ambient light conditions from bright sunlight to dim artificial light in ambient darkness, by providing a dynamic resistance element in series with the photodetector wherein the dynamic resistance element compensates for changes in the photodetector due to changes in ambient light conditions to maintain the photodetector in a detection condition (avoiding saturation) regardless of the ambient light condition. In the preferred embodiment of the detector, the dynamic resistance element is at least one reversed biased zener diode. In currently preferred circuitry of the invention, the detector detects the presence of intermittent lane dividing lines and provides an alarm when such lines are no longer detected.
17 Citations
28 Claims
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1. A detector for detecting light reflected from a light area on a surface, comprising:
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a photodetector positioned to receive light from a portion of the surface; and
a dynamic impedance element connected electrically in series with the photodetector to maintain the photodetector in condition to detect light reflected from a light area on the surface regardless of the ambient illumination of the surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A detector for detecting light reflected from lines on a highway surface from a moving motor vehicle, comprising:
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a photodetector mounted to receive light reflected from the lines in a predetermined manner when the vehicle is properly within a lane but not otherwise;
an alarm to, once enabled, provide an indication when light is received by the photodetector in other than the predetermined manner; and
a dynamic impedance element electrically connected in series with the photodetector to maintain the photodetector in condition to detect light reflected from a line regardless of ambient illumination of the highway and line. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27)
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23. A detector for detecting light reflected from discontinuous lane dividing lines on a highway surface from a moving motor vehicle, comprising:
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a photodetector mounted to receive light reflected from the discontinuous lane dividing lines when the vehicle is properly within a lane but not otherwise;
circuitry to produce a pulse for each lane dividing line sensed;
logic circuitry to determine if a pulse is produced, indicating a line sensed within successive fixed periods of time in which it is expected that a line should be sensed; and
an alarm to, once enabled, provide an alarm indication if the logic circuitry determines an alarm condition exists.
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28. A method for detecting whether a vehicle is maintaining position in a highway lane marked by at least one set of discontinuous lane dividing lines on the highway surface, comprising the steps of:
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detecting, using a photodetector, discontinuous lane dividing lines marking the lane in which the vehicle is traveling;
determining through logic circuitry if a line is detected in each of a succession of time periods in which it would be expected lines would be detected if the vehicle stayed in the lane and detected such lines; and
giving an alarm if such lines are not detected in each of the expected successive time periods, such lines not being detected indicating the lines are not being sensed and possible drift of the vehicle out of the lane.
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Specification