MAGNETIC RECORDING AND REPRODUCING DEVICE

摘要

PURPOSE:To detect the tape remaining quantity by providing an angle follow-up type reflecting plate which has an angle change equal to the surface of a magnetic tape between a light source and the magnetic tape and then irradiating the reflected light sent from the reflecting plate to a photodetecting sensor. CONSTITUTION:The light ejected from a light source 1 is converted into parallel beams through a collimator lens 2, and these beams are made incident to a reflecting surface 11a of a mobile reflecting plate 11 and reflected to be made incident to a focusing lens 3. The beams of the lens 3 are focused on a photodetecting sensor 4. Here the surface 11a is always set parallel to the surface of a magnetic tape 8 by means of a contact 13, and therefore the condensing position of the reflected light condensed on the sensor 4 is varied linearly in accordance with the wind radius of a take-up reel 7. Then the tape remaining quantity of a supply reel 6 is detected from the position of the reflected light condensed to the sensor 4. Thus it is possible to detect the tape remaining quantity for both pure iron group tape and iron oxide tape with use of the plate 11 containing the contact 13 which has a contact with the surface of the tape 8.