Obstacle detector for a vehicle
First Claim
1. An obstacle detector for a vehicle comprising:
- means for producing a first pulse signal having pulse with a width substantially equal to twice the travel time required for light to travel a braking distance;
means responsive to the first pulse signal for transmitting a light signal of duration substantially equal to the pulse width of the first pulse signal so as to cover a detection area which extends to include the braking distance away from the vehicle;
means for receiving a light signal reflected by an obstacle present in the detection area and for converting the received light signal to a second corresponding electric pulse signal;
means for determining whether the time width of a pulse of the first signal is larger than the time interval taken from the time when the light signal is transmitted to the time when the light signal is received by said receiving means after reflection by the obstacle; and
said first pulse signal producing means including means for generating a clock signal, means for generating a ramp function starting each time a pulse of the clock signal is inputted thereto, means for creating the sum of a braking distance signal and a signal indicative of the distance which the vehicle travels during the driver'"'"'s response time, depending on the vehicle speed, and means for defining the width of a pulse of the first signal as the time interval from the time when each ramp function starts to the time when the value of the ramp function exceeds the sum.
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Accused Products
Abstract
A pulse signal generator produces a first pulse signal having a pulse width substantially equal to twice the travel time required for light to travel a braking distance. A light transmitter radiates a light beam signal representing the first pulse signal so as to cover a detection area in which the braking distance is contained. A photoreceptor receives the light signal reflected by an obstacle present in the detection area and converts the received light beam signal to a second corresponding electric pulse signal. A determination device determines whether the time width of a pulse of the first signal is larger than the time interval taken from the time when the corresponding pulse of the light signal is transmitted to the time when the pulse of the light signal is received by the receptor after reflection by the obstacle.
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Citations
12 Claims
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1. An obstacle detector for a vehicle comprising:
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means for producing a first pulse signal having pulse with a width substantially equal to twice the travel time required for light to travel a braking distance; means responsive to the first pulse signal for transmitting a light signal of duration substantially equal to the pulse width of the first pulse signal so as to cover a detection area which extends to include the braking distance away from the vehicle; means for receiving a light signal reflected by an obstacle present in the detection area and for converting the received light signal to a second corresponding electric pulse signal; means for determining whether the time width of a pulse of the first signal is larger than the time interval taken from the time when the light signal is transmitted to the time when the light signal is received by said receiving means after reflection by the obstacle; and said first pulse signal producing means including means for generating a clock signal, means for generating a ramp function starting each time a pulse of the clock signal is inputted thereto, means for creating the sum of a braking distance signal and a signal indicative of the distance which the vehicle travels during the driver'"'"'s response time, depending on the vehicle speed, and means for defining the width of a pulse of the first signal as the time interval from the time when each ramp function starts to the time when the value of the ramp function exceeds the sum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification