Detecting a leading edge of a sheet in a paper handling system of a document reproduction device

Abstract

What is disclosed is a system for detecting a leading edge of a sheet in a paper handling system of a document reproduction device. An illuminator continuously projects a beam of light into a first end of a light transmissive medium. The projected light propagates through the medium and exits an opposite end thereof. The first end is offset from the illuminator to form a first gap. The light is continuously detected by a detector as the light exits the light transmissive medium. The opposite end of the medium is offset from the detector to form a second gap. A paper sheet is transported along the paper path such that it traverses the area defined by the first and second gaps. If the detector no longer detects the light exiting the opposite end of the medium, a signal is given that a leading edge of the sheet has been detected.

What is claimed is: 
     
         1 . A method for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device, the method comprising:
 projecting, continuously by at least one illuminator, light into a first end of a light transmissive tubular medium with a high internal reflectance and a substantially arcuate longitudinal axis, the projected light propagating through the tubular medium and exiting a second end of the tubular medium an opposite end thereof, the first end being offset from the illuminator by a first distance to form a first gap;   detecting, continuously by at least one detector, the light exiting the second end of the tubular medium, the second end being offset from the detector by a second distance to form a second gap, the illuminator is positioned at first position and the detector is positioned at a second position along a same side of a paper path along which a sheet travels in a document reproduction device and a distance between the illuminator and the detector corresponds to a distance between the first end of the tubular medium and the second end of the tubular medium so as to provide an offset therebetween along the paper path, and the tubular medium is positioned on an opposite side of the paper path from the illuminator and the detector;   transporting, by a paper handling system of the document reproduction device, the sheet along the paper path such that the transported sheet traverses the first gap and the second gap; and   signaling, in response to the detector no longer detecting the projected light exiting the tubular medium, that a leading edge of the transported sheet has been detected.   
     
     
         2 - 7 . (canceled) 
     
     
         8 . The method of  claim 1 , wherein a wavelength of the projected light is any of:
 visible and infrared.   
     
     
         9 . The method of  claim 1 , further comprising at least one optical lens. 
     
     
         10 . A system for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device, the system comprising:
 a light transmissive tubular medium with a high internal reflectance and a substantially arcuate longitudinal axis comprising such that light propagates through the tubular medium and exits an opposite end thereof;   at least one illuminator for continuously projecting light of a pre-defined wavelength into a first end of the light transmissive tubular medium, the first end being offset from the illuminator by a first distance to form a first gap;   at least one detector for continuously detecting the projected light exiting the opposite end of the tubular medium, the opposite end being offset from the detector by a second distance to form a second gap, the illuminator is positioned at first position and the detector to is positioned at a second position along a same side of a paper path along which a sheet travels in a document reproduction device and a distance between the illuminator and the detector corresponds to a distance between the first end of the tubular medium and the second end of the tubular medium so as to provide an offset therebetween along the paper path, and the tubular medium is positioned on an opposite side of the paper path from the illuminator and the detector; and   a signal generator for signaling, in response to the detector no longer detecting the projected light exiting the tubular medium, that a leading edge of the transported sheet has been detected.   
     
     
         11 - 16 . (canceled) 
     
     
         17 . The system of  claim 10 , wherein a wavelength of the projected light is any of:
 visible and infrared.   
     
     
         18 . The system of  claim 10 , further comprising a user interface for turning the leading edge detection system ON/OFF. 
     
     
         19 . The system of  claim 10 , further comprising a user interface for adjusting an intensity of the light being projected by the illuminator. 
     
     
         20 . (canceled)