supply reel การใช้

EIAJ-2 used a cartridge that contained a supply reel, but not the take-up reel.
Historically, movie projectors prior to modern automation would include a bell, activated by centrifugal force when the supply reel reached an appropriate speed.
The control electronics kept the curve of the tape loop between the two inner sensors, cueing the supply reel to feed more or the take-up reel to take more as necessary.
EIAJ-2 used a cartridge that contained a supply reel; the take-up reel was part of the recorder, and the tape had to be fully rewound before removing the cartridge, a slow procedure.
This was necessary because the supply reel is always decreasing in effective diameter while the take up reel is increasing in effective diameter as the tape moves from one reel to the other during encoding, and again when backspacing or rewinding.