| 摘要 |
A tape cassette housing having a mouth extending across its front portion and opening downwardly and forwardly is further provided with a laterally centered hole in back of the mouth and a recess in the bottom surface of the cassette housing through which the lower portion of the hole communicates with the mouth, so that, when the cassette housing is operatively positioned on a deck, a light-emitting element on the deck extends into the mouth and directs a light beam parallel to the deck into a lower portion of a prism also mounted on the deck to extend into the recess and hole of the cassette housing. The prism has a reflecting surface which reflects the received light beam upwardly to a radiating portion of the prism in the hole by which the upwardly reflected beam is split into two oppositely directed lateral beams for detecting opposite ends of a recording tape in the cassette housing.
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