Apparatus and method for detection of overlapping objects

An overlapped object detector comprising:

• means for transporting objects along a defined path;
• a station including a plurality of detection means aligned substantially perpendicular to the direction of movement of said objects, each detection means including first and second radiation sources oriented to direct radiation against said objects as they pass said station and also including first and second radiation sensing means, each sensing means paired respectively with its corresponding radiation source to receive radiation therefrom which has been reflected from an object passing said station, said sensing means being able to detect a decrease in reflectivity of an object caused by the edge of one object overlapping another object, or by a mark on an object;
• and
• logic means coupled to said detection means for signifying when an overlap has taken place, said overlap being indicated by a detection of a decrease in reflectivity by one or the other, but not both, of the radiation sensing means of all of said detection means.

An overlapped object detector comprising:

• means for transporting objects along a defined path;
• detection means including first and second radiation sources oriented to direct radiation against said objects as they pass said station and also including first and second radiation sensing means, each sensing means paired respectively with its corresponding radiation source to receive radiation therefrom which has been reflected from an object passing said station, said sensing means being able to detect a decrease in reflectivity of an object caused by the edge of one object overlapping another object, or by a mark on an object;
• and
• logic means coupled to said detection means for signifying when an overlap has taken place, said overlap being indicated by a detection of a decrease in reflectivity by one or the other, but not both, of the radiation sensing means of said detection means.

An overlapped object detector comprising:

• means for transporting objects along a defined path;
• a station including a plurality of detection means aligned substantially perpendicular to the direction of movement of said objects, each detection means including a radiation source oriented to direct radiation against said objects as they pass said station and also including first and second spaced apart radiation sensing means, each sensing means directed to a different point on said defined path and positioned to receive radiation from said radiation source which has been reflected from an object passing said station, said sensing means being able to detect a decrease in reflectivity of an object caused by the edge of one object overlapping another object, or by a mark on an object;
• and
• logic means coupled to said detection means for signifying when an overlap has taken place, said overlap being indicated by a detection of a decrease in reflectivity by one or the other, but not both, of the radiation sensing means of all of said detection means.

An overlapped object detector comprising:

• means for transporting objects along a defined path;
• detection means including a radiation source oriented to direct radiation against said objects as they pass said station and also including first and second spaced apart radiation sensing means, each sensing means directed to a different point on said defined path and positioned to receive radiation from said radiation source which has been reflected from an object passing said station, said sensing means being able to detect a decrease in reflectivity of an object caused by an edge of one object overlapping another object, or by a mark on an object;
• and
• logic means coupled to said detection means for signifying when an overlap has taken place, said overlap being indicated by a detection of a decrease in reflectivity by one or the other, but not both, of the radiation sensing means of said radiation means.

An overlapped object detector comprising:

• means for transporting objects along a defined path;
• a station including a plurality of detection means aligned substantially perpendicular to the direction of movement of said objects, each detection means including first and second alternately operable radiation sources oriented to direct radiation obliquely against said objects as they pass said station and also including radiation sensing means positioned to receive radiation alternately from said first and second radiation sources, said radiation being reflected from an object passing said station, said sensing means being able to detect a decrease in reflectivity of an object caused by the edge of one object overlapping another object, or by a mark on an object;
• and
• logic means coupled to said detection means for signifying when an overlap has taken place, said overlap being indicated by a detection of a decrease in reflectivity by the sensing means of all of said detection means during one or the other, but not both, of two consecutive times of operation of said first and second radiation means.

An overlapped object detector comprising:

• means for transporting objects along a defined path;
• detection means including first and second alternately operable radiation sources oriented to direct radiation obliquely against said objects as they pass said station and also including radiation sensing means positioned to receive radiation alternately from said first and second radiation sources, said radiation being reflected from an object passing said station, said sensing means being able to detect a decrease in reflectivity of an object caused by the edge of one object overlapping another object, or by a mark on an object;
• and
• logic means coupled to said detection means for signifying when an overlap has taken place, said overlap being indicated by a detection of a decrease in reflectivity by said sensing means during one or the other, but not both, of two consecutive times of operation of said first and second radiation sources.

A method for the detection of overlaps of objects which are being transported along a path of movement comprising the steps of:

• A. directing radiation on to the surfaces of objects in said path to produce a shadow along the edge of any first object which overlaps a second object in a first direction;
• B. detecting any decrease in radiation reflected from said surfaces resulting from the shadow caused by said overlap in said first direction or from markings on one or more of said objects in a first sampling;
• C. directing radiation on to the surfaces of objects in said path to produce a shadow along the edge of any first object which overlaps a second object in a second direction opposite to said first direction;
• D. detecting any decrease in radiation reflected from said surfaces resulting from the shadow caused by said overlap in said second direction or from markings on one or more of said objects in a second sampling;
• and
• E. providing an overlap detection signal in response to the detection of a decrease in radiation in either of said first and second samplings, with no such signal being provided in response to the detection of a decrease in radiation by either both or neither of said two samplings.

A method for the detection of overlaps of objects which are being transported along a path of movement comprising the steps of:

• A. directing radiation on to he surfaces of objects in said path to produce shadows along the edge of any first object which overlaps a second object in a first direction;
• B. detecting any decrease in radiation reflected from said surfaces resulting from the shadow caused by said overlap in said first direction or from markings on one or more of said objects in a first plurality of samplings;
• C. directing radiation on to the surfaces of objects in said path to produce shadows along the edge of any first object which overlaps a second object in a second direction opposite to said first direction;
• D. detecting any decrease in radiation reflected from said surfaces resulting from the shadows caused by said overlap in said second direction or from markings on one or more of said objects in a second plurality of samplings;
• and
• E. providing an overlap detection signal in response to the detection of a decrease in radiation in either all of said first plurality of samplings or all of said second plurality of samplings, with no such signal being provided in response to any other combination of radiation decrease detections.