US 5,414,268 AGranted

Light scanner with interlaced camera fields and parallel light beams

AssigneeThe Coe Manufacturing Company

InventorArthur L. McGee

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Abstract

A light scanner for determining the configuration of elongated objects, such as logs or lumber, is described. The object is moved laterally through the scanner past a plurality of laser light sources and a plurality of photo-detector cameras spaced along the object. The coherent laser light beams are parallel to each other and to the lens axis centerline of the cameras for easier alignment and to prevent the laser light spot on the object from moving relative to such axis centerline for objects of different thickness. The cameras have a photo-detector target which may be a linear diode aray CCD semiconductor device for producing scan data signals in response to reflected light beams which are processed by a computer system giving preference to the data produced by the beams in the outer portions of the camera viewing field to determine the thickness of the object at points spaced along the object. Non-coherent polychromatic light is also reflected from the object to the cameras to detect the ends of the object and to determine its length. Reference targets are provided along one side of the object to sense the leading end and the trailing edge of the object as it is moved laterally to block light reflected from or emitted by such targets to the cameras on the opposite side of the object.

Claims20

Dependent claims

Light scanner apparatus for determining the configuration of an elongated object, comprising:

a plurality of photo-detectors spaced apart across a scanning zone through which the elongated object is moved to scan the object, each photo-detector having an optical axis and a viewing field divided by said optical axis into a right field and a left field, and each of said right and left fields having a first field portion adjacent the optical axis and a second field portion separated from the optical axis by said first field portion;
a plurality of laser light sources positioned between said photo-detectors and supported so that at least some of the laser light beams emitted by said laser light sources are located in the viewing fields of a pair of adjacent photo-detectors and the light beams extend substantially parallel to each other and to the optical axis of each of the photo-detectors;
mounting means for mounting the photo-detectors to cause the viewing fields of each pair of adjacent photo-detectors to overlap sufficiently so that the first field portion of one photo-detector overlaps the second field portion of the other photo-detector of said pair;
scan signal selection means for selecting portions of a scanning output signal produced by each photo-detector when the elongated object is moved through the scanning zone, giving preference to those scanning signal portions which correspond to the second field portions of its viewing field while rejecting portions of the scanning output signal which correspond to the first field portions of said viewing field unless there is no usable signal portion corresponding to the second field portion which overlaps the first field portion;
and
signal processor means for producing an object configuration signal from the selected portions of the scanning signals of the photo-detectors which is of greater accuracy.

3 more elements

A method for scanning an elongated object, such as a log, to determine the configuration of said elongated object, comprising the steps of:

positioning a plurality of photo-detectors spaced apart across a scanning zone, said photo-detectors each having an optical axis and a viewing field divided by the optical axis into a right field and a left field which each have a first field portion adjacent the optical axis and a second field portion separated from the optical axis by the first field portion;
aligning said photo-detectors to cause the viewing fields of each pair of adjacent photo-detectors to overlap so that the first field portion of one photo-detector overlaps the second field portion of the other photo-detector of said pair;
positioning a plurality of laser light sources between said photo-detectors so that the laser light beams emitted by said laser light sources each has its beam axis located in the viewing fields of a pair of adjacent photo-detectors and the beam axes extend substantially parallel to each other and to the optical axis of the other laser light beams;
moving the elongated object relative to the laser light sources and the photo-detector through said scanning zone to scan said elongated object and produce a scanning output signal at the output of each photo-detector;
selecting those portions of the scanning output signals which correspond to the second field portions of the viewing fields of the photo-detectors, and rejecting those portions of the scanning output signals which correspond to the first field portions of said viewing fields unless there is no usable signal portion corresponding to the second field portion which overlaps the first field portion;
and
combining the selected portions of the scanning output signals to produce an object configuration signal.

4 more elements

Dependencies are inferred from the claim text.