GB1127090A - Cartridge type tape player - Google Patents

Abstract

1,127,090. Magnetic-head positioning. MOTOROLA Inc. 4 May, 1967 [18 July, 1966], No. 20777/67. Heading G5R. A cam, for raising and lowering a magnetic head on a tape-player into correspondence with different tracks on a tape in a cartridge, is rotated by two pawl members acting on a ratchet wheel coupled to the cam, the pawl members being resiliently biased together and being coupled to the armature of a solenoid which is automatically first energized on completion of play of a track on the tape, and then de-energized, so that the head is automatically positioned to play another track. As shown in Fig. 2, a stereo tape-player 10 has a capstan shaft 20 mounted in a housing 22 and a tape-head 12 mounted in a head bracket 14 having integral with it a cam follower 16. The bracket 14 is secured to a pantograph linkage including pivot rods 17, 18 and a spring (not shown) which serves to urge cam follower 16 into contact with a cam 19. The cam 19 has a plurality of different surfaces each associated with different tracks on the tape. When the end of a set of tracks is reached on the tape, an aluminium strip moves across a set of contacts (not detailed) to energize a solenoid 39, whose armature 37, Figs. 3 and 4, is linked to two pawls which engage a ratchet connected to cam 19. Action of pawl-and-ratchet mechanism.-The position of the parts before movement is shown in Fig. 3. When the solenoid is energized, the armature is withdrawn to the left, whereupon actuating projection 44 on the upper pawl 32 moves tooth 50 on ratchet 42 to the left by an angular distance of one half tooth; at the same time locking portions 45, 48, on pawls 32, 33 respectively, engage teeth 52, 54 respectively to prevent counter rotation of the ratchet: this is the position of Fig. 4. When the solenoid is de-energized, a spring (56, Fig. 2), urges the armature to the right once more, whereupon actuating projection 47 on lower pawl 33 moves tooth 58 to the right by an angular distance of one half tooth until a position equivalent to that of Fig. 3 is reached but with the ratchet rotated by one tooth angle. The pawls are biased towards each other by a spring 40; the ratchet rotation is counter-clockwise. Vertical adjustment of cam 19 and pawl 42 may be effected by movement of their shaft 64, Fig. 2, by an adjusting screw 65.