GB1526375A - Method of identifying streaks on a web - Google Patents

Abstract

1526375 Detecting streaks on a web CIBAGEIGY AG 23 March 1977 [31 March 1976] 12902/76 Heading G1A A method of identifying streaks on a web comprises creating relative movement in a first direction between the web and an inspection station, scanning the web in a second direction and deriving from the signal thus produced a succession of digital signals each corresponding to a different element of web, feeding each digital signal into a different arithmetic register in a computer, repeating the scan during or after relative movement in the first direction, feeding each digital signal from an element to the corresponding arithmetic register of the earlier scan(s) and, after a predetermined number of scans, making the computer compare the contents of each register and of one or more of the other registers to see if the differences exceed a predetermined amount thereby indicating a streak. A first source of a frequency determined by scan requirements, web speed and resolution controls the scan rate, the digital signals being fed into register 112 and then transferred through register 13 into the arithmetic registers at a rate determined by a second frequency source. The digital signals may be obtained from a combination of the inspection signals with a noise signal.