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 | Welcome to the "History of CCTV" Section | ||||||||||||||||||||||||||||||
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At about the same time, manufacturers were also experimenting with two new imaging chips, the Charge Injection Device (CID) and the Charge Coupled Device (CCD); no prizes for guessing which type eventually won through! ... o.k. it was the CCD!!. From the outset. their were essentially two main types of CCD imager, the Interline Transfer (IT) and Frame Transfer (FT) devices. Both provided subtly different characteristics, and both at that time, had a place in the ‘armoury’. In recent years, special hybrid Frame Interline Transfer (FIT) chips have been developed for cameras used in broadcast television, as Electronic News Gathering (ENG) and Electronic Film Production (EFP) models, although this very high performance technology has yet to make any inroads into the CCTV sector. Whilst these imagers are capable of breathtaking levels of resolution (1000+ lines are not uncommon), their relative lack of sensitivity and equally impressive price tag, means that the likelyhood of any of this quality rubbing off on the humble CCTV camera, is about the same as Doktor Jons chances of winning the national lottery (looks like I'll be working for a few years yet). Almost all modern CCTV surveillance cameras are now built around CCD imagers, and whilst the design principles are basically the same as for the earliest CCD’s, the actual levels of sophistication, and resultant improvements in performance, are barely comparable. Interesting to note though, that the early and long since redundant MOS type imagers, may yet have something of a renaissance with new models due to enter the marketplace during 2004. In the last fifteen or so years, CCD cameras have gone from poor quality relatively insensitive Black and White units, through to complete high resolution and sensitivity colour packages mounted on a single 25 or 30 mm square, printed circuit board. Whilst there have in the past been a few examples of complete 'cameras on a chip', being manufactured and marketed, particularly for ‘Visual Verification’ as part of an elaborate intruder alarm system, these have yet to take off in a big way .... but they will!! | |||||||||||||||||||||||||||||||
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