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Optical Card Position Sensing

IP.com Disclosure Number: IPCOM000040740D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Mulholland, PJ: AUTHOR

Abstract

An optical technique is described for finding accurately the positions of holes in a printed circuit card when using a robot to insert or place components on the card. A light source is under the card, and a sensor with four light detectors placed above the card with positions slightly offset from the four holes to be sensed. The robot initially positions the sensor at the card design position and then moves the sensor until the outputs from the four detectors are equal. The movement from the initial position gives the offsets to be applied in subsequent assembly on that card. The technique enables the determination of X and Y co-ordinate offsets which it is necessary to apply to the robot position data in order to compensate for errors in the placement of the workpiece and errors in the robots own gripper system.

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Optical Card Position Sensing

An optical technique is described for finding accurately the positions of holes in a printed circuit card when using a robot to insert or place components on the card. A light source is under the card, and a sensor with four light detectors placed above the card with positions slightly offset from the four holes to be sensed. The robot initially positions the sensor at the card design position and then moves the sensor until the outputs from the four detectors are equal. The movement from the initial position gives the offsets to be applied in subsequent assembly on that card. The technique enables the determination of X and Y co- ordinate offsets which it is necessary to apply to the robot position data in order to compensate for errors in the placement of the workpiece and errors in the robots own gripper system. Elimination of this positioning mismatch results in improved yields, faster throughput, and fewer damaged components. For each card to be populated on a robot assembly cell it is necessary to establish the relationship between the card land pattern and the robot measurement datums. The technique consists of using the robot to position a sensor, similar in form to one of the components to be used, over the appropriate hole positions using the position data derived from the card physical design data sets. The sensor (see Figs. 1 and 2) provides four analog outputs which will be equal within predefined limits when the sensor...