wherein {HEAD ~ the first condition} that requires {TAIL ~ a larger storage capacity} of the storage unit in the document reading is a reading condition where a difference is larger than an enough storage capacity to implement the functions other than the image reading function, which difference is a storage capacity difference between: 
requires
wherein { HEAD ~ the first condition } that requires { TAIL ~ a larger storage capacity } of the storage unit in the document reading is a reading condition where a difference is larger than an enough storage capacity to implement the functions other than the image reading function , which difference is a storage capacity difference between :
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH