| 摘要 |
A magnetic tape cassette is designed for use in a magnetic recording and/or reproducing apparatus. The ends of the magnetic tape within the cassette are detected by a combination of a single light-emitting source and first and second light-receiving photocells mounted on the apparatus and disposed opposite each other. The magnetic tape is opaque and has first and second transparent leader tapes connected to its opposite ends. The cassette case receives and accommodates first and second reels with the tape extending therebetween and across the face of the cassette case. The cassette face extends between first and second side or end walls which have first and second windows formed therein. The bottom of the cassette has a hole for receiving the light-emitting source at a point where the light will pass through both windows if the opaque tape does not bar the way. A lid is pivotally mounted on the side or end walls to swing to either a closed position where the lid covers both the front face and the first and second windows, or an opened position where the lid exposes both the front face and the first and second windows. The first window is formed at a position where the light passes from the light-emitting source through the leader tape to the first light-receiving photocell when the lid is in the opened position. The second window is formed at a position where the light passes from the light-emitting source through the second leader tape to the second light-receiving photocell when the lid is in the opened position.
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