Automatic filter changer for use on surface mounter inspection camera

Abstract

A printed circuit board assembly machine inspects circuit boards and parts to be mounted on those circuit boards prior to assembly. This assembly machine may visualize and recognize physical features of the circuit boards and parts as part of this inspection. A filter may be deployed while visualizing certain types of circuit boards or parts to remove characteristic defects found in images of those types of parts. When several types of circuit boards or parts inspected by the assembly machine exhibit different characteristic visualization problems, the assembly machine may deploy a different filter for each type of circuit board or part.

What is claimed is:  
     
         1 . In an automated printed circuit board assembly machine, a method for visualizing an item having physical features on a background, comprising the steps of: 
 illuminating the item with electromagnetic radiation, including the physical features and the background, using an illumination source;    forming an image of electromagnetic radiation reflected from the item, said image containing a characteristic defect depending on the type of item; and    automatically filtering said reflected electromagnetic radiation to remove said characteristic defects from said image,    whereby in said filtered image said characteristic defect is reduced and an improved contrast between the physical features and the background is produced.    
     
     
         2 . The method as claimed in  claim 1 , further comprising recognizing the physical features in the filtered image.  
     
     
         3 . The method as claimed in  claim 1 , wherein said electromagnetic radiation is light and said filtered image is formed by a camera.  
     
     
         4 . The method as claimed in  claim 2 , wherein said electromagnetic radiation is light, said filtered image is formed by a camera of a computer vision system, and said recognizing is performed by said computer vision system.  
     
     
         5 . The method as claimed in  claim 1 , wherein the item is a printed circuit board.  
     
     
         6 . The method as claimed in  claim 2 , wherein the item is a printed circuit board.  
     
     
         7 . The method as claimed in  claim 1 , wherein the item is a part to be mounted on a printed circuit board.  
     
     
         8 . The method as claimed in  claim 2 , wherein the item is a part to be mounted on a printed circuit board.  
     
     
         9 . In an automated printed circuit board assembly machine, an apparatus for visualizing an item having physical features on a background, comprising: 
 one or more sources for illuminating the item with electromagnetic radiation;    an image forming device for forming an image of electromagnetic radiation reflected from the item, said image having a characteristic defect depending on the type of item;    a filter; and    an actuator positioning said filter, such that said image is formed of electromagnetic radiation passing through the filter,    whereby said filter reduces said characteristic defect in said filtered image and an improved contrast between the physical features and the background is produced.    
     
     
         10 . The apparatus as claimed in  claim 9 , further comprising a computer vision system for recognizing the physical features in the filtered image.  
     
     
         11 . The apparatus as claimed in  claim 9 , wherein said electromagnetic radiation is light and said image forming device is a camera.  
     
     
         12 . The apparatus as claimed in  claim 10 , wherein said electromagnetic radiation is light and said image forming device is a camera of said computer vision system.  
     
     
         13 . The apparatus as claimed in  claim 9 , wherein the item is a printed circuit board.  
     
     
         14 . The apparatus as claimed in  claim 10 , wherein the item is a printed circuit board.  
     
     
         15 . The apparatus as claimed in  claim 9 , wherein the item is a part to be mounted on a printed circuit board.  
     
     
         16 . The apparatus as claimed in  claim 10 , wherein the item is a part to be mounted on a printed circuit board.  
     
     
         17 . The apparatus as claimed in  claim 16 , further comprising a manipulator for positioning the part on a circuit board or card with recognized physical features of the part in registration with contact pads of the board or card.  
     
     
         18 . A circuit board or card on which is surface mounted a part that has been recognized in accordance  18  with the method of  claim 8 , such surface mounting being with recognized physical features of the part in registration with contact pads of the board or card.