Apparatus for measuring the distance between two moving vehicles using light waves.

摘要

To measure a distance between two running vehicles, a measurement signal (S1) is first generated by irradiating light beam toward an article to be measured and then receiving the reflected light beam from the article. An apparatus for determining the foregoing distance therebetween using light wave operates such that a reference signal (S2) and the measurement signal (S1) generated in that way are input a digital mix-down circuit (1) composed of two-stage flip-flop circuits (U1,U2) to determine a phase difference between the reference signal (S2) and the measurement. The apparatus includes as essential components a clock delay circuit (10) for delaying the going-high edge of the measurement signal (S1) while the reference signal (S2) is going high at an output terminal of a flip-flop circuit (U1) on the input side of the digital mix-down circuit (1) and a data delay circuit (20) for delaying the going-down edge of the reference signal input into a data terminal of the flip-flop circuit (U1). Usually, the clock delay circuit (10) is electrically connected to the digital mix-down circuit (1) via the data delay circuit (20), while the data delay circuit (20) is electrically connected directly to the digital mix-down circuit (1). Alternatively, both the clock delay circuit (10) and the data delay circuit (20) may electrically be connected directly to the digital mix-down circuit (1). <IMAGE>