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Browse Prior Art Database

Visual Verification of Circuit Module Placement

IP.com Disclosure Number: IPCOM000050015D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Grossman, DD: AUTHOR [+2]

Abstract

A system for determining the position and orientation of square circuit modules by means of a computer-controlled image device is described herein.

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Visual Verification of Circuit Module Placement

A system for determining the position and orientation of square circuit modules by means of a computer-controlled image device is described herein.

Since circuit modules may be misplaced on a printed wiring board, it is desirable to have a means to determine their position and orientation after placement.

Fig. 1 shows an automatic, computer-controlled system for performing this task.

The printed wiring board (PWB) to be inspected is moved around, in the field of view of an imaging device connected to a computer, by means of a computer- controlled XY positioning table.

At each position 4 images are produced, using one of the four lights (NORTH, SOUTH, EAST, WEST) shown in Fig. 1. By virtue of the fact that the circuit modules have one beveled top edge, all edges which face the lighted lamp will appear as bright regions in the image. Since the circuit packages have a specular reflectance characteristic, this effect is quite selective (Fig. 2), and only the light-facing beveled edges will appear.

Since circuits face in one of the four cardinal directions, their beveled edge will appear in one of the four images. Which image (NORTH, SOUTH, EAST or WEST) a beveled edge appears in indicates the orientation of its module. In addition, as shown in Fig. 3, the position of the bevel indicates the position of the module (X,Y coordinates).

The proposed device uses hardware means to reduce the four images to binary form, setting...