Browse Prior Art Database

Defects Detection by Spacial Correlation of Images

IP.com Disclosure Number: IPCOM000046020D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Begnoche, N: AUTHOR

Abstract

A system is disclosed for converting visual information pertaining to a product into digital data for processing with suitable hardware in order to detect defects in the product.

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Defects Detection by Spacial Correlation of Images

A system is disclosed for converting visual information pertaining to a product into digital data for processing with suitable hardware in order to detect defects in the product.

The product used in the illustrated system is an integrated circuit module which could have up to 72 pins, each having a preferred diameter of .020 inch. For these modules to be satisfactorily inserted into a printed circuit, the pins must be straight, must not be oversized as from solder buildup, and they must not be missing or broken off. The disclosed system will identify if any of these defects exist in the module.

With reference to Fig. 1, a vidicon camera views the top of the pins of the product module. A signal representing the light shining from the pins is detected by a video slicer which provides threshold level detection. The video slicer produces a logic signal for each pin (1 in Figs. 1, 2 and 3), which is synchronized with the camera. The camera is synchronized by a cathode ray tube controller (CRTC). The CRTC also acts as a character generator and generates a signal pattern corresponding to the maximum deviation allowable for the pins on the circuit board under test (2 in Figs. 1, 2 and 3). Both signals 1 and 2 are correlated and chopped into picture elements and totalized by counters (Fig. 2). After a full video frame is loaded into random-- access memory (RAM), the missing pin and oversized pin tests are performed by the...