Method of reading pattern containing a material capable of radiating infrared light

Abstract

Disclosed is a method of reading a pattern comprising steps of heating or irradiating with infrared light a substrate on which a transparent pattern is formed, the pattern containing a material capable of absorbing infrared light of specific wavelength such as polyacrylonitrile, and detecting infrared light which is radiated or reflected from the pattern.

1 . A method of reading a pattern comprising steps of: 
 heating or irradiating with infrared light a substrate on which a transparent pattern is formed, said pattern containing a material capable of absorbing infrared light of specific wavelength; and    detecting infrared light from said pattern.    
     
     
         2 . The method according to    claim 1   , wherein said pattern constitutes a symbol.  
     
     
         3 . The method according to    claim 1   , wherein said material capable of absorbing infrared light of specific wavelength is a polymer or a low molecular-weight compound having a cyano group.  
     
     
         4 . The method according to    claim 3   , wherein said polymer having cyano groups is polyacrylonitrile or a acrylonitrile-based copolymer.  
     
     
         5 . The method according to    claim 1   , wherein said substrate is made of cloth, and said pattern is formed by sewing a thread made of fibers of polyacrylonitrile or a acrylonitrile-based copolymer.  
     
     
         6 . The method according to    claim 1   , wherein said material constituting said pattern has a higher thermal conductivity than that of said substrate.  
     
     
         7 . The method according to    claim 1   , wherein a colored mark is formed in the vicinity of the pattern region on said substrate.  
     
     
         8 . The method according to    claim 1   , wherein a mark comprising a fluorescent material capable of emitting visible light upon absorption of ultraviolet light is formed in the vicinity of the pattern region on said substrate.  
     
     
         9 . An optical signal reader comprising: 
 a means for conveying a substrate on which a transparent pattern is formed, said pattern containing a material capable of absorbing infrared light of specific wavelength;    a means for heating or irradiating with infrared light a region of said pattern formed on said substrate; and    a means for detecting infrared light from said pattern.    
     
     
         10 . The optical signal reader according to    claim 9   , wherein at least either one of said means for irradiating with infrared light and said means for detecting infrared light is provided with a filter capable of selecting infrared light of specific wavelength.  
     
     
         11 . A method of preventing counterfeiting of a certification document on which visible information for certification is formed comprising steps of: 
 forming a transparent pattern corresponding to said visible information on said document, said pattern containing a material capable of absorbing infrared light of specific wavelength;    heating or irradiating with infrared light a region of said pattern on said substrate;    detecting infrared light from said pattern; and    comparing information detected from said pattern with said visible information.    
     
     
         12 . The method according to    claim 11   , wherein said pattern region is covered with a transparent film.  
     
     
         13 . A method of preventing counterfeiting of a prepaid card in which magnetic information is recorded comprising steps of: 
 forming a plurality of transparent patterns corresponding to remaining sums on said prepaid card;    punching a hole in one of said patterns corresponding to a remaining sum available for use at the time when said prepaid card is used;    heating or irradiating infrared light a region of said patterns on said prepaid card;    detecting infrared light from said patterns; and    comparing information detected from said patterns with the magnetic information recorded in said prepaid card.