Method of and apparatus for electrical short testing and the like
AssigneeGenRad, Inc.
InventorDavid W. Thiel
Life of this patent
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Abstract
This disclosure is concerned with a process for connecting a short detector to electrical nodes in such apparatus as backplanes, cables and circuit boards before components are assembled thereto, to identify shorted node pairs in a substantially smaller number of tests than required by previously known methods, through a novel binary screening and then binary searching technique; the invention being especially efficient in the case where no shorts are present.
Claims20
Apparatus for detecting shorts and the like between the nodes of a system under test, the system having a plurality of such nodes, and for identifying shorted nodes, comprising short detection means provided with a pair of leads across which a short is to be detected;
- a pair of switch-connecting means, one associated with each of the leads and adapted, respectively, to connect a group of nodes together and to connect an associated lead to said group of said nodes;
- and means for operating the pair of switch-connecting means to connect one lead to a first group of nodes, the first group having up to and including half of said nodes while simultaneously connecting the other lead to a second group of nodes, the second group including the remaining nodes;
- said operating means including means for successively varying the population of nodes in each group to connect different populations of said nodes to the leads in accordance with a predetermined pattern to enable successive screening tests for detecting shorts between said different populations, said predetermined pattern varying the population of the group of nodes connected to each lead such that each node is tested against every other node at least once in substantially fewer tests than are required to test each node individually against every other node, and means operable in the event that a short is detected for successively reducing the number of nodes connected to each lead until each lead is connected to only one shorted node, to search for and identify a shorted node pair.
A method of reducing the number of tests required to detect shorts and the like between nodes of a system under test, the system having a plurality of such nodes, and to identify shorted nodes, the method including screening tests to detect whether a short exists between any of the nodes and, in the event that a short is detected, searching tests to identify the shorted nodes, the method comprising the steps of connecting together a first group of nodes and connecting together a second group of nodes, the first group containing up to and including half of the nodes of said plurality and the second group containing the remaining nodes of said plurality;
- successively testing for a short between the first and second groups of nodes;
- varying, in the course of said testing, the populations of nodes contained in the first and second groups in accordance with a predetermined pattern to perform successive screening tests for shorts between different populations of nodes, said predetermined pattern varying the populations of the groups such that each node is tested against every other node at least once in substantially fewer tests than are required to test each node individually against every other node;
- and, in the event that a short is detected in said screening tests, performing searching tests, in the course of said testing, by successively eliminating nodes from the first group until that group contains only one shorted node, and successively eliminating nodes from the second group until that group contains only one shorted node, thereby permitting the identification of a shorted node pair.
A method of reducing the number of tests required to detect shorts and the like between the nodes of a system under test, the system having a plurality of such nodes, and to identify shorted nodes, the method including screening tests to detect whether a short exists between any of the nodes and, in the event that a short is detected, searching tests to identify the shorted nodes, the method comprising the steps of grouping the plurality of nodes into first and second groups;
- connecting together the nodes in each group;
- testing for a short between the first group and the second group;
- successively varying, in the course of said testing, the populations of nodes included within the two groups in accordance with a predetermined pattern to perform successively said screening tests, said predetermined pattern varying the populations of the groups such that each node is tested against every other node at least once in substantially fewer tests than are required to test each node individually against every other node;
- and, upon detecting that a short exists, performing said searching tests by successively reducing, in the course of said testing, the number of nodes included within each group to search for a shorted node pair.
Dependencies are inferred from the claim text.