Importance

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Abstract

A video image compensator for inspection apparatus is presented for utilization in a system of the type in which an image of a workpiece is digitized and compared against stored data representing a workpiece of known acceptable quality. The invention compensates for instability, drift, and distortion inherently present in vidicons by providing a test pattern for periodic viewing by the vidicon, and providing therefrom data from which scale factors and image shift data can be generated. Subsequent live images of workpieces can then be scaled and shifted prior to correlation with the stored reference to compensate for instability, drift, and distortion of the vidicon. A mirror is used to alternately direct the field of view of the vidicon to either the test pattern or the workpiece target. In one embodiment, the mirror is made selectively transparent to allow the workpiece to be viewed, while in an alternate embodiment, the mirror is physically deflected from the vidicon's field of view.

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First Claim