Patent ID: 7339675
Filing Date: 2008-03-04
Classification: B65H,G01N,G03B

Abstract:
1. An apparatus for measuring a dimension of a sheet member, comprising: a light source for applying light in a wavelength range which prevents the sheet member from being fogged; a plurality of photodetectors, having respective optical axes directed toward a feed path of the sheet member, for directly or indirectly detecting said light from said light source; and a data processor for detecting positions of a first end and a second end of said sheet member based on a luminance of said light detected by said photodetectors, and measuring a dimension of said sheet member from the detected positions of said first end and said second end of said sheet member, wherein a portion of said light which is detected penetrates through said sheet member and another portion of said light which is detected passes by said end of said sheet member, such that image data is obtained which represents a combination of: a) a luminance level of light which has penetrated through a portion of said sheet member at said first end of said sheet member and which is detected by a first of said photodetectors; and b) a luminance level of light which has been received by said first of said photodetectors directly from said light source by passing by said first end; and c) a luminance level of light which has penetrated through a portion of said sheet member at said second end of said sheet member opposite said first end and which is detected by a second of said photodetectors; and d) a luminance level of light which has been received by said second of said photodetectors directly from said light source by passing by said second end, wherein a position of said first end of said sheet member is determined in relation to a position of said second end of said sheet member based on said combination of luminance levels.