Optical Card Position Sensing
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
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.