Automated system and method for detecting defective edges of printed circuit boards and other objects using multiple sensors

A method for automatically inspecting edges of one or more objects for possible defects, the method comprising:

• scanning opposing, first and second objects edges of one or more objects using at least four electronic sensors, wherein a first and a second of the at least four electronic sensors are positioned on a first side of an inspection line along which the one or more objects are placed to inspect the first object edge for defects and a third and a fourth of the at least four electronic sensors are positioned on a second side of the inspection line substantially opposite the first and second electronic sensors, respectively, to inspect the second object edge on an opposite side of the first object edge for defects;
• wherein the first and third electronic sensors are maintained in substantial alignment with each other and the second and fourth electronic sensors are maintained in substantial alignment with each other, and wherein the opposing edges of the object are scanned for inspection by the electronic sensors as the opposing edges pass in proximity to the electronic sensors;
• periodically obtaining, by a controller, a set of substantially simultaneous measurements from the at least four electronic sensors as the first and second objects edges of a particular object are scanned by the electronic sensors;
• summing, by the controller, the periodically obtained set of measurements from the first, second, third and fourth electronic sensors, to calculate a sum E=|(A+B)−(C+D)|, where A, C, B and D correspond to substantially simultaneous sensor measurements of the first, second, third and fourth electronic sensors, respectively;
• and
• comparing the sum E to a threshold value;
• wherein, when the sum E remains less than or equal to the threshold value, the controller continues to obtain sets of substantially simultaneous sensor measurements of the first, second, third and fourth sensors until the scanning of the first and second object edges of the particular object is completed but, if the sum E exceeds the threshold value when scanning the first and second object edges of the particular object, the controller determines that the particular object has a defective edge.

An automated system for inspecting edges of one or more objects for possible defects, the system comprising:

• a plurality of at least two electronic sensors to detect positions of opposing edges of one or more objects, wherein a first of the at least two electronic sensors is positioned on a first side of an inspection line along which the one or more objects are placed to inspect a first object edge for defects and a second of the at least two electronic sensors is positioned on a second side of the inspection line substantially opposite and in substantial alignment with the first electronic sensor to inspect a second object edge on an opposite side of the first object edge for defects;
• a memory to store measurements taken by the plurality of electronic sensors;
• and
• a controller programmed to obtain two or more sets of substantially simultaneous sensor measurements of the first and second electronic sensors as the opposing edges of a particular object are scanned by the electronic sensors, to store in the memory at least one of the sets of substantially simultaneous sensor measurements that is obtained to calculate a sum E=|(A+B)−(C+D)|, and to compare the sum E to a threshold value, where values A and B correspond to a first of the two or more sets of sensor measurements of the first and second electronic sensors obtained at a first time t1 and values C and D correspond to a second of the two or more sets of sensor measurement of the first and second electronic sensors obtained at a second time t2 separated from the first time by a time interval;
• wherein, when the sum E remains less than or equal to the threshold value, the controller is further programmed to periodically obtain additional sets of substantially simultaneous sensor measurements of the first and second electronic sensors until the scanning of the first and second object edges of the particular object is completed but, if the sum E is larger than the threshold value when scanning the first and second object edges of the particular object, the controller determines that the particular object has a defective edge.

A method for automatically inspecting edges of one or more objects for possible defects, the method comprising:

• scanning opposing, first and second edges of one or more objects with at least two electronic sensors, wherein a first of the at least two electronic sensors is positioned on a first side of an inspection line along which the one or more objects are placed to inspect the first object edge for defects and a second of the at least two electronic sensors is positioned on a second side of the inspection line substantially opposite and in substantial alignment with the first electronic sensor to inspect a second object edge on an opposite side of the first object edge for defects, wherein the opposing edges of the object are scanned for inspection by the electronic sensors as the opposing edges pass in proximity to the electronic sensors;
• obtaining, by a controller, two or more sets of substantially simultaneous measurements of the first and second electronic sensors as the first and second edges of a particular object are scanned by the electronic sensors;
• summing, by the controller, the periodically obtained set of measurements from the first and second electronic sensors, to calculate a sum E=|(A+B)−(C+D)|, where values A and B correspond to a first of the one or more sets of sensor measurements of the first and second electronic sensors obtained at a first time t1 and values C and D correspond to a second of the one or more sets of sensor measurement of the first and second electronic sensors obtained at a second time t2 separated from the first time by a time interval;
• and
• comparing the sum E to a threshold value;
• wherein, when the sum E remains less than or equal to the threshold value, the controller continues to periodically obtain sets of substantially simultaneous sensor measurements of the first and second electronic sensors until the scanning of the first and second edges of the particular object is completed but, if the sum E exceeds the threshold value, the controller determines that the object has a defective edge.