Method and apparatus for utilizing a shadow effect for counting newspapers, magazines, books, printed products, signatures and other like printed matter

A method for identifying and counting printed products conveyed in a stream past a monitoring station in imbricated fashion with folded edges facing in a downstream direction, comprising:

• (a) generating pulses related to a linear speed of the printed products being conveyed;
• (b) illuminating the printed products with light directed at an angle so as to cause a leading folded edge of a printed product to form a shadow on a surface of a printed product upon which the leading folded edge is placed;
• (c) during illumination of the light source, capturing an image of an intermediate region of the printed products passing through the monitoring station responsive to each pulse generated during step (a);
• and
• (d) comparing the captured image with predetermined criteria to determine a presence of a leading edge to prevent disturbances from being erroneously identified as a leading edge.

Apparatus for identifying and counting printed products conveyed in a stream past a monitoring station in imbricated fashion with folded edges facing in a downstream direction, comprising:

• a pulse generator for generating pulses at a rate related to a rate of movement of the printed products being conveyed;
• a light source being triggered responsive to pulses from the pulse generator whereby folded edges of printed products conveyed through a region of a light beam from the light source cause a shadow to form on a surface of a downstream printed product upon which the folded edge of the upstream printed product is placed;
• a normally inactive sensor activated substantially activated simultaneously with triggering of the light source, capturing an image of a given region containing the shadow created on the printed products passing through the monitoring station responsive to each pulse generated by said pulse generator;
• and
• means for comparing the captured image with predetermined criteria to determine a presence of a leading edge and thereby prevent disturbances from being erroneously identified as a leading edge.

Apparatus for identifying and counting printed products conveyed along a given path in a stream past a monitoring station in imbricated fashion with folded edges facing in a downstream direction, comprising:

• a light source being triggered at a rate which is related to a linear speed of the printed products being conveyed whereby folded edges of printed products conveyed through a region of an illuminating light berm from the light source which is aligned at an angle of less than 90° to said given path to cause a shadow to form on a surface of only a downstream printed product upon which the folded edge of the upstream printed product is placed;
• a normally inactive sensor activated substantially simultaneously with triggering of the light source, capturing an image of a given region of the printed products passing through the monitoring station;
• and
• means for comparing the captured image with predetermined criteria to determine a presence of a leading edge and thereby prevent disturbances from being erroneously identified as a leading edge.

Apparatus for identifying and counting printed products conveyed in a stream past a monitoring station in imbricated fashion with folded edges facing in a downstream direction, comprising:

• a pulse generator for generating pulses at a rate related to a linear speed of movement of the printed products being conveyed;
• a light source for illuminating the printed products with light directed at an angle so as to cause a leading folded edge of a printed product to form a shadow on a surface of a printed product upon which the leading folded edge is placed;
• a sensor, substantially simultaneously with illumination of the light source, capturing an image of an intermediate region of the printed products passing through the monitoring station responsive to each pulse generated;
• and
• means for comparing the captured image with predetermined criteria to determine a presence of a leading edge and thereby prevent disturbances from being erroneously identified as a leading edge.