ADAPTIVE LIGHTING SYSTEM AND METHOD FOR MACHINE VISION APPARATUS

A variable intensity lighting system for use with a machine vision apparatus for capturing high contrast images of articles to be inspected, such as semiconductor packages, includes an LED or optical fiber element and flash lamp array configured in multiple segments which are operable to be controlled as to light output intensity by a programmable intensity control circuit operably connected to a microprocessor. The intensity control circuit includes multiple digital potentiometers operable to control selected segments of the lighting array. The control circuit is adapted to control up to 64 segments of the lighting array individually at 64 incremental intensity levels, respectively. The control circuit may include a light failure module to detect a segment failure or a reversed connection. A processor is programmed to calculate a median gray value from a predetermined number of camera pixel intensity values of the article being viewed under the lighting array to readjust the intensity of the lighting until a setting with suitable contrast is reached. Each article being viewed may have a suitable identifier, such as a dimple or notch which is viewed by the camera to determine the optimum intensity level.