Sensing of original size

Abstract

An original size sensing method for an apparatus which includes a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, determines the presence/absence of incidence of ambient light on the basis of an output from the photoelectric converter while the light source is kept off. When ambient light is found to be incident, the method determines the size of an original placed on the platen on the basis of that output from the photoelectric converter, which falls outside the range in which the ambient light is incident, while the light source is kept on.

1 . An original size sensing apparatus incorporated into an apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, comprising: 
 an ambient light determination unit for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination unit for determining, when said ambient light determination unit determines that ambient light is incident, the size of    an original placed on said platen on the basis of output from said photoelectric converter except a pixel range in which the ambient light is incident, while said light source is kept on.    
     
     
         2 . The apparatus according to  claim 1 , wherein said ambient light determination unit comprises a binarization processor for comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light, and said original size determination unit determines the pixel range in which the ambient light is incident on the basis of the binary signal.  
     
     
         3 . The apparatus according to  claim 1 , further comprising at least one original size sensor for sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination unit determines the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensor.  
     
     
         4 . The apparatus according to  claim 1 , wherein said original size sensing apparatus is applicable to original size sensing in an image reading apparatus, original size sensing in a copying apparatus, and original size sensing in a facsimile apparatus.  
     
     
         5 . The apparatus according to  claim 1 , wherein said original size determination unit determines, when said ambient light determination unit determines that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         6 . An original size sensing apparatus incorporated into an apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen having an original size index plate indicating placement position references of various fixed-form originals, and a light source for irradiating the original with light, comprising: 
 an ambient light determination unit for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off, and    an original size determination unit for determining, when said ambient light determination unit determines that ambient light is incident, the size of an original placed on said platen on the basis of output from a pixel range, of said photoelectric converter, from a boundary between a region in which the ambient light is not incident and a region in which the ambient light is incident to a predetermined position, while said light source is kept on, wherein the boundary is the one closest to the predetermined position if a plurality of boundaries exist.    
     
     
         7 . The apparatus according to  claim 6 , wherein said ambient light determination unit comprises a binarization processor for comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light, and said original size determination unit determines the boundary on the basis of the binary signal.  
     
     
         8 . The apparatus according to  claim 6 , further comprising at least one original size sensor for sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination unit determines the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensor.  
     
     
         9 . The apparatus according to  claim 6 , wherein said original size sensing apparatus is applicable to original size sensing in an image reading apparatus, original size sensing in a copying apparatus, and original size sensing in a facsimile apparatus.  
     
     
         10 . The apparatus according to  claim 6 , wherein said original size determination unit determines, when said ambient light determination unit determines that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         11 . An image reading apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, comprising: 
 an ambient light determination unit for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination unit for determining, when said ambient light determination unit determines that ambient light is incident, the size of an original placed on said platen on the basis of output from said photoelectric converter except a pixel range in which the ambient light is incident, while said light source is kept on.    
     
     
         12 . The apparatus according to  claim 11 , wherein said ambient light determination unit comprises a binarization processor for comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light, and said original size determination unit determines the pixel range in which the ambient light is incident on the basis of the binary signal.  
     
     
         13 . The apparatus according to  claim 11 , further comprising at least one original size sensor for sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination unit determines the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensor.  
     
     
         14 . The apparatus according to  claim 11 , wherein said original size determination unit determines, when said ambient light determination unit determines that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         15 . An image reading apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen having an original size index plate indicating placement position references of various fixed-form originals, and a light source for irradiating the original with light, comprising: 
 an ambient light determination unit for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination unit for determining, when said ambient light determination unit determines that ambient light is incident, the size of an original placed on said platen on the basis of output from a pixel range, of said photoelectric converter, from a boundary between a region in which the ambient light is not incident and a region in which the ambient light is incident to a predetermined position, while said light source is kept on, wherein the boundary is the one closest to the Predetermined position if a plurality of boundaries exist.    
     
     
         16 . The apparatus according to  claim 15 , wherein said ambient light determination unit comprises a binarization processor for comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light, and said original size determination unit determines the boundary on the basis of the binary signal.  
     
     
         17 . The apparatus according to  claim 15 , further comprising at least one original size sensor for sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination unit determines the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensor.  
     
     
         18 . The apparatus according to  claim 15 , wherein said original size determination unit determines, when said ambient light determination unit determines that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         19 . A copying apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, comprising: 
 an ambient light determination unit for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination unit for determining, when said ambient light determination unit determines that ambient light is incident, the size of an original placed on said platen on the basis of output from said photoelectric converter except a pixel range in which the ambient light is incident, while said light source is kept on.    
     
     
         20 . The apparatus according to  claim 19 , wherein said ambient light determination unit comprises a binarization processor for comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light and said original size determination unit determines the pixel range in which the ambient light is incident on the basis of the binary signal.  
     
     
         21 . The apparatus according to  claim 19 , further comprising at least one original size sensor for sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination unit determines the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensor.  
     
     
         22 . The apparatus according to  claim 19 , wherein said original size determination unit determines, when said ambient light determination unit determines that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         23 . A copying apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen having an original size index plate indicating placement position references of various fixed-form originals, and a light source for irradiating the original with light, comprising: 
 an ambient light determination unit for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination unit for determining, when said ambient light determination unit determines that ambient light is incident, the size of an original placed on said platen on the basis of output from a pixel range, of said photoelectric converter, from a boundary between a region in which the ambient light is not incident and a region in which the ambient light is incident to a predetermined position, while said light source is kept on, wherein the boundary is the one closest to the predetermined position if a plurality of boundaries exist.    
     
     
         24 . The apparatus according to  claim 23 , wherein said ambient light determination unit comprises a binarization processor for comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light, and said original size determination unit determines the boundary on the basis of the binary signal.  
     
     
         25 . The apparatus according to  claim 23 , further comprising at least one original size sensor for sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination unit determines the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensor.  
     
     
         26 . The apparatus according to  claim 23 , wherein said original size determination unit determines, when said ambient light determination unit determines that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         27 . A facsimile apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, comprising: 
 an ambient light determination unit for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination unit for determining, when said ambient light determination unit determines that ambient light is incident, the size of an original placed on said platen on the basis of output from said photoelectric converter except a pixel range in which the ambient light is incident, while said light source is kept on.    
     
     
         28 . The apparatus according to  claim 27 , wherein said ambient light determination unit comprises a binarization processor for comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light, and said original size determination unit determines the pixel range in which the ambient light is incident on the basis of the binary signal.  
     
     
         29 . The apparatus according to  claim 27 , further comprising at least one original size sensor for sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination unit determines the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensor.  
     
     
         30 . The apparatus according to  claim 27 , wherein said original size determination unit determines, when said ambient light determination unit determines that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         31 . A facsimile apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen having an original size index plate indicating placement position references of various fixed-form originals, and a light source for irradiating the original with light, comprising: 
 an ambient light determination unit for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination unit for determining, when said ambient light determination unit determines that ambient light is incident, the size of an original placed on said platen on the basis of output from a pixel range, of said photoelectric converter, from a boundary between a region in which the ambient light is not incident and a region in which the ambient light is incident to a predetermined position, while said light source is kept on, wherein the boundary is the one closest to the predetermined position if a plurality of boundaries exist.    
     
     
         32 . The apparatus according to  claim 31 , wherein said ambient light determination unit comprises a binarization processor for comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light, and said original size determination unit determines the boundary on the basis of the binary signal.  
     
     
         33 . The apparatus according to  claim 31 , further comprising at least one original size sensor for sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination unit determines the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensor.  
     
     
         34 . The apparatus according to  claim 31 , wherein said original size determination unit determines, when said ambient light determination unit determines that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         35 . An original size sensing method for an apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, comprising: 
 an ambient light determination step of determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination step of determining, when it is determined in said ambient light determination step that ambient light is incident, the size of an original placed on said platen on the basis of output from said photoelectric converter except a pixel range in which the ambient light is incident, while said light source is kept on.    
     
     
         36 . The method according to  claim 35 , wherein said ambient light determination step comprises a binarization processing step of comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and outputting a binary signal indicating the presence/absence of ambient light, and in said original size determination step, the pixel range in which the ambient light is incident is determined on the basis of the binary  
     
     
         37 . The method according to  claim 35 , further comprising an original size sensing step of sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination step comprises determining the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from said original size sensing step.  
     
     
         38 . The method according to  claim 35 , wherein said original size sensing method is applicable to original size sensing in an image reading apparatus, original size sensing in a copying apparatus, and original size sensing in a facsimile apparatus.  
     
     
         39 . The method according to  claim 35 , wherein, in said original size determination step, when it is determined in said ambient light determination step that ambient light is not incident, the size of an original placed on said platen is determined on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         40 . An original size sensing method for an apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen having an original size index plate indicating placement position references of various fixed-form originals, and a light source for irradiating the original with light, comprising: 
 an ambient light determination step of determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    an original size determination step of determining, when it is determined in said ambient light determination step that ambient light is incident, the size of an original placed on said platen on the basis of output from a pixel range, of said photoelectric converter, from a boundary between a region in which the ambient light is not incident and a region in which the ambient light is incident to a predetermined position, while said light source is kept on, wherein the boundary is the one closest to the predetermined position if a plurality of boundaries exist.    
     
     
         41 . The method according to  claim 40 , wherein said ambient light determination step comprises a binarization processing step of comparing a preset threshold value with the output from said photoelectric converter obtained when reading is performed with said light source OFF, arid outputting a binary signal indicating the presence/absence of ambient light, and in said original size determination step, the boundary is determined on the basis of the binary signal.  
     
     
         42 . The method according to  claim 40 , further comprising an original size sensing step of sensing the size in a sub-scan direction of an original placed on said platen, wherein said original size determination step comprises determining the size of an original placed on said platen on the basis of the output result from said photoelectric converter and the sensing result from the original size sensing step.  
     
     
         43 . The method according to  claim 40 , wherein said original size sensing method is applicable to original size sensing in an image reading apparatus, original size sensing in a copying apparatus, and original size sensing in a facsimile apparatus.  
     
     
         44 . The method according to  claim 40 , wherein, in said original size determination step, when it is determined in said ambient light determination step that ambient light is not incident, the size of an original placed on said platen is determined on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         45 . A computer program having computer executable program code means for original size sensing in an apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen, and a light source for irradiating the original with light, said program including: 
 first computer readable program code means for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off; and    second computer readable program code means for determining, when ambient light is found to be incident, the size of an original placed on said platen on the basis of output from said photoelectric converter except a pixel range in which the ambient light is incident, while said light source is kept on.    
     
     
         46 . The program according to  claim 45 , wherein said first computer readable program code means comprises third computer readable program code means for performing control such that a preset threshold value is compared with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and a binary signal indicating the presence/absence of ambient light is output, and the pixel range in which the ambient light is incident is determined on the basis of the binary signal.  
     
     
         47 . The program according to  claim 45 , wherein said second computer readable program code means comprises fourth computer readable program code means for performing control such that the size in a sub-scan direction of an original placed on said platen is sensed, and said second computer readable program code means performs control such that the size of an original placed on said platen is determined on the basis of the output result from said photoelectric converter and the size in the sub-scan direction.  
     
     
         48 . The program according to  claim 45 , wherein said computer program is applicable to original size sensing in an image reading apparatus, original size sensing in a copying apparatus, and original size sensing in a facsimile apparatus.  
     
     
         49 . The program according to  claim 45 , wherein said second computer readable program code means determines, when it is determined that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.  
     
     
         50 . A computer program having computer executable program code means for original size sensing in an apparatus which comprises a photoelectric converter for reading an image of an original placed on a platen having an original size index plate indicating placement position references of various fixed-form originals, and a light source for irradiating the original with light, said program including: 
 first computer readable code means for determining the presence/absence of incidence of ambient light on the basis of an output from said photoelectric converter while said light source is kept off, and    second computer readable code means for determining, when ambient light is found to be incident, the size of an original placed on said platen on the basis of output from a pixel range, of said photoelectric converter, from a boundary between a region in which the ambient light is not incident and a region in which the ambient light is incident to a predetermined position, while said light source is kept on, wherein the boundary is the one closest to the predetermined position if a plurality of boundaries exist.    
     
     
         51 . The program according to  claim 50 , wherein said first computer readable program code means comprises third computer readable program code means for performing control such that a preset threshold value is compared with the output from said photoelectric converter obtained when reading is performed with said light source OFF, and a binary signal indicating the presence/absence of ambient light is output, and the boundary is determined on the basis of the binary signal.  
     
     
         52 . The program according to  claim 50 , wherein said second computer readable program code means comprises fourth computer readable program code means for performing control such that the size in a sub-scan direction of an original placed on said platen is sensed, and said second computer readable program code means performs control such that the size of an original placed on said platen is determined on the basis of the output result from said photoelectric converter and the size in the sub-scan direction.  
     
     
         53 . The program according to  claim 50 , wherein said computer program is applicable to original size sensing in an image reading apparatus, original size sensing in a copying apparatus, and original size sensing in a facsimile apparatus.  
     
     
         54 . The program according to  claim 50 , wherein said second computer readable program code means determines, when it is determined that ambient light is not incident, the size of an original placed on said platen on the basis of all the output from said photoelectric converter while said light source is kept on.