Abstract

A rangefinder device includes means for projecting a beam of light to illuminate a spot on an object in a scene. A linear image sensor views the scene and produces a series of photosignals representing the brightness of the scene. Signal processing electronics responsive to the photosignals from the linear image sensor detect the location of the illuminated spot in the scene and produce a distance signal representing the distance to the object. The signal processing electronics include:a counter that is advanced each time a photosignal is received from the image sensor;a latch connected to the counter and responsive to a control signal for temporarily storing the current count of the counter; anda peak detector responsive to the photosignals for producing an output signal each time a new greater photosignal is received.The output signal of the peak detector is supplied to the latch as the control signal. After the series of photosignals has been produced by the image sensor, the count remaining in the latch represents the location of the illuminated spot in the scene. The peak detector includes means for setting a threshold peak value below which no peak is detected.