Abstract: In a machine vision system capable of capturing an optical image of a semiconductor electronic component part and digitizing the optical image, a method for locating, inspecting and placing parts known as large leaded devices, by estimating a part's location; estimating the approximate location of a group of leads; computing the center and angle of a lead scan search rectangle within which the leads in a group of leads must be located; scanning a lead scan search rectangle to locate lead edges and compile a list of edges; extracting lead positions; updating the part location estimate; and repeating these steps for each lead set to find all leads and lead centerlines; then calculating an optimal part position estimate by matching found lead positions with expected lead centerlines; and finally, inspecting the leads. A statistical lead rejection procedure is included during lead extraction.

Abstract: The invention provides methods and apparatus for inspecting a surface mounted device to estimate its position. The methods and apparatus provide for storing a description of the component to be inspected; devising a plan for inspecting features of the surface mounted device to determine their characteristics arid, from them, to estimate a position of the device itself; generating an image of at least a portion of the component being inspected; and estimating the component's position by inspecting successive features in accord with the plan. A resulting output signal provides that estimate, for example, to placement equipment which can make final adjustments in placement. According to one aspect of the invention, that plan is intended to reduce with inspection of each successive feature any uncertainty in the estimation of the position of the component.