Apparatus for detecting sheet-formed support material

Apparatus for detecting a sheet-formed article passing along a predetermined path, said apparatus comprising:

• a light source provided with a first polarizing means and a photoresponsive element provided with a second polarizing means, said light source and said photoresponsive element positioned adjacent said path of said sheet-formed article passing therebetween, the relative spacing relationship between a first plane of polarization of said first polarizing means and a second plane of polarization of said second polarizing means so arranged that the amount of light received by said photoresponsive element is increased when a transparent sheet-formed article is passed across a light path originating from said light source;
• said apparatus further comprising another photoresponsive element, said another photoresponsive element disposed with respect to said light source such that the amount of light received by said another photoresponsive element is increased when light passing through said first polarizing means is reflected by a non-transparent sheet-formed article when said non-transparent sheet-formed article is passed across said light path originating from said light source;
• wherein said photoresponsive element and said another photoresponsive element are connected to a first electric circuit means for the detection of the passage of said sheet-formed article and connected to a second electric circuit means for the detection of the transparency of said sheet-formed article.

In an electrographic copying apparatus of powder image transfer type, an apparatus for detecting a copy sheet passing along a predetermined transporting path comprising:

• a light source provided with a first polarizing means and a photoresponsive element provided with a second polarizing means, said light source and said photoresponsive element positioned adjacent said predetermined transporting path of said copy sheet passing therebetween, the relative spacing relationship between a first plane of polarization of said first polarizing means and a second plane of polarization of said second polarizing means arranged such that the amount of light received by said photoresponsive element is increased when a transparent copy sheet is passed across a light path originating from said light source;
• said apparatus further comprising another photoresponsive element, said another photoresponsive element disposed such that the amount of light received by said another photoresponsive element is increased when light passing through said first polarizing means is reflected by a non-transparent copy sheet when said non-transparent copy sheet is passed across said light path originating from said light source;
• wherein said photoresponsive element and said another photoresponsive element are connected to a first electric circuit means for the detection of the passage of said copy sheet and connected to a second electric circuit means for the detection of the transparency of said copy sheet.

In an electrographic copying apparatus of powder image transfer type, an apparatus for detecting a copy sheet passing along a predetermined transporting path comprising:

• a light source provided with a first polarizing means and a photoresponsive element provided with a second polarizing means, said light source and said photoresponsive element positioned adjacent said predetermined transporting path of said copy sheet passing therebetween, the relative spacing relationship between a first plane of polarization of said first polarizing means and a second plane of polarization of said second polarizing means arranged such that the amount of light received by said photoresponsive element in increased when a transparent copy sheet is passed across a light path originating from said light source;
• said apparatus further comprising another photoresponsive element disposed on the side opposite said light source with respect to said predetermined path, said another photoresponsive element disposed with respect to said light source such that the amount of light received by said another photoresponsive element is decreased when a non-transparent copy sheet is passed across said light path originating from said light source;
• wherein said photoresponsive element and said another photoresponsive element are connected to a first electric circuit means for the detection of the passage of said copy sheet and connected to a second electric circuit means for the detection of the transparency of said copy sheet.