Curve reading method and apparatus

Abstract

Method and apparatus for reading a curve line present on a recording medium and providing a digital or analog output indicative of the path of such curve line, wherein an optically visible curve line present on a recording material is caused to move relatively to an electronic camera tube; the electronic camera tube photoelectronically scans an optical image with a narrow scanning beam moving across the medium along a locus extending transversely of the recording direction and generates a video output signal containing for each scanning period a voltage train varying in accordance with the optical intensity of the segment of the medium being scanned and which contains at least one pulse produced when the scanning beam crosses the curve line image; the voltage train for each such scanning period is inverted in polarity and combined additively with the voltage train produced during a prior scanning period to give when the variations in such two signal trains are out of synchronism an output signal having a magnitude according to the magnitude of the individual pulses and the extent of their nonsynchronization; the thus generated output signal is compared with a reference signal of fixed magnitude to detect when the same exceeds the reference signal magnitude and in that event to deliver an output pulse; and the output pulse actuates a digital counter driven in synchronism with the scanning rate of the tube scanning beam to read out the instantaneous count in said counter. The voltage train of the prior scanning period can be stored in a memory device controlled by the output pulse so that the memory device repeats a given signal train until signaled by such pulse to erase that chain and store the next train therein.

Dependencies are inferred from the claim text.