| 摘要 |
<p>PROBLEM TO BE SOLVED: To make it possible to judge the presence or absence of an erroneous recording preventive lug of a cassette without allocating a switch to be exclusively used thereto. SOLUTION: This detector has an LED 21 and phototransistor 22 which are normally used as tape end sensors. A moving piece 30 is arranged in the moving route of the accidental recording preventive lug at the time of a loading operation of the cassette in such a manner that this piece shuts off a photodetecting route by a light shielding bar 33 at the other end while energizing the round-shaped projection of an arm part 31 to the lug side or is retreatable. Consequently, the moving piece moves relatively along a recess in the case of a lug breakage state and makes rectilinear relative motion along the rear surface of the cassette in the case of a lug presence state. While the presence or absence of the erroneous recording preventive lug of the loaded cassette is judged in accordance with the output of the phototransistor 22 at the time of the cassette loading action, the result of the judgment is stored. As a result, the need for discretely and previously preparing a lug breakage detecting sensor having a lower utilization frequency is eliminated.</p> |
