Scanning apparatus and method

摘要

An automatic scanning and control apparatus determines the location of a predetermined segment of an image field being scanned. The predetermined segment presents an image which is optically differentiatable from the surrounding area of the image field. The apparatus includes a beam device for selectively scanning the image field and producing an output signal thereof. The beam device includes means for modulating the output signal in accordance with variations in the image field. The predetermined segment of the image field causes modulation of the output signal of the beam device by providing an inflection therein when the beam scans across the segment. An analyzing circuit is adapted to accept the output signal from the beam device. Means generate a locating signal in predetermined time relation to the scanning. Comparator means compare the inflection in the output signal with the locating signal so that the location of the predetermined segment of the image field can be determined. A method compares an image field to be inspected with a standard image field. A standard image field is scanned with a beam and a video signal is modulated in accordance with intensity variations in the standard field. The video signal is recorded on a recording member. The field to be inspected is then scanned by the beam and a second video signal is generated. Both the video signals are reproduced and passed to a comparator means. A point to point comparison is made between the inflections and variations in each signal resulting from the scanning image areas of contrasting intensity by generating pulse signals during the intervals that the areas do not coincide. The pulse signals are then automatically analyzed.