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Analog cameras still play a role.

Article Excerpt
By Ann R. Thryft, Contributing Technical Editor

Many engineers designing machine-vision systems for semiconductor inspection applications continue to specify analog cameras because they are widely available and cost less than digital cameras. Although digital cameras continue to make inroads in machine vision, the use of analog cameras is not declining as quickly as some predicted when digital technology first became available.

"Designers of machine-vision systems have continued to use analog TV cameras wherever they could because of their low cost and high availability," said Steve Kinney, director of technical pre-sales and support for JAI. "These have been the highest performing cameras for the lowest dollar cost for a long time, because of their standard formats. Eight to 10 years ago, three quarters of the cameras used in machine vision, by unit volumes, were analog cameras."

The analog cameras used in electronics inspection output signals in either NTSC or PAL TV formats for color, and either the RS-170 or the CCIR 601 standard for monochrome, said Kinney. Most cameras used in machine vision are progressive scan, rather than interlaced, since the progressive-scan image-transfer method doesn't suffer from the problems interlaced cameras have with creating sharp images of moving...