US 4,556,903 A · Inspection scanning system

Abstract

A system for generating a substantially-continuous stream of binary signals representative of the presence of copper on the surface of a fluorescent substrate of a board. A beam is swept by mirror facets of a rotating mirror drum along a path on the board. When the beam strikes copper it is merely relected. When the beam strikes the substrate, a fluorescence is produced. The resultant light is gathered by cylindrical lenses and fiber optic bundles. The color of the light is blocked by filters and the fluorescence color energizes photomultiplier tubes. A threshold setting and sensing circuit senses the output of the photomultiplier tubes and controls their bias voltage to produce a constant level of output from fluorescence and then produces a stream of binary signals that are representative of the presence/absence of copper on the surface of the board. The swept beam is split to send a portion of its energy through an optical grating. The intermittent light passing through the optical grating is gathered by a fiber optic bundle and is sensed by a photomultiplier tube. The output of the photomultiplier tube is doubled in frequency and used to sample and store the binary signals in the memory of a scanning converter. The binary signals arrive in short bursts of higher-frequency signals separated by periods of absence of binary data. The binary signals stored in the scanning converter are then read out substantially continously for subsequent processing at a lower frequency.

Claims9

Dependent claims

An apparatus for generating a binary signal representative of the presence/absence of conductive material having physical dimensions of size and spacing in a pattern on the surface of a fluorescent substrate, comprising:

a helium-cadmium laser generating a spot of blue light, said spot having a diameter smaller than the smallest physical dimension of the pattern of conductive material;
means for relatively scanning the spot of laser light in a raster pattern across a field to be examined on the surface of the substrate;
means for sensing fluorescent light resulting from the impingement of the scanned laser light over the areas of the substrate that are not covered with conductive material and for disregarding the light resulting from impingement of the scanned light over the areas of the substrate that are covered with conductive material;
means for generating a stream of sensing sampling signals representative of the instantaneous scanning location of the spot of blue laser light;
means for controlling the sensitivity of the sensing means based upon the level of fluorescence of the surface of the substrate to maintain a substantially constant signal level indicative of fluorescence at the surface of the substrate;
means for generating a stream of binary video signals based upon the combination of the ratio of the instantaneous sensed signal and the signal representative of the level of fluorescence of the substrate and the sensing scanning signals;
and
means for converting an intermittant stream of binary video signals at a higher frequency of the sensing sampling signals to a substantially continuous stream of binary video signals at a lower frequency.

5 more elements

A system for inspecting a product, comprising:

means for optically scanning the product and, in response to the optical signals thus produced, generating electronic data output video signals;
means synchronized with the optical scanning of the product for producing timing output signals in spaced synchronism with the scanning of the product;
means for maintaining a constant magnitude of the video signals;
means for converting the video signals into a binary representation of the nature of the surface of the product;
and
means for changing the speed and timing efficiency of the converted video signals to permit substantially continuous processing thereof.

3 more elements

Dependencies are inferred from the claim text.

Inspection scanning system

Life of this patent

Inspection scanning system

Life of this patent

Abstract

Claims9