Patent ID: 6868620

Claim:
A hand-held digital measuring instrument comprising: a housing containing a measuring line; a rotatable measuring drum in engagement with said measuring line so that movement of said measuring line causes rotation of said measuring drum; a storage spool mounted in said housing for storing said measuring line; a crank assembly having a crank handle coupled with said storage spool for rotating said storage spool for winding said measuring line about said storage spool; a rotatable disc coupled with said measuring drum for rotating simultaneously with said measuring drum; an optical sensor in communication with said disk for compiling data related to rotation of said disk; electronic circuitry in communication with said optical sensor for processing the compiled data so as to calculate a length of said measuring line drawn from said housing; said housing including a well adapted to receive said storage spool; and a removable side cover attachable to said housing over said well, said side cover including a slideable lock for selectively detaching said side cover from said housing for uncovering said well, wherein said storage spool is rotatable for winding and unwinding said measuring line from said storage spool.