Patent GB-1138397-A (GB)
Title: Tape drive control mechanisms for magnetic tape recorders
IPC: G11B15/22
Filed: 1966-03-02
Abstract: 1,138,397. Tape recorder. AKAI ELECTRIC CO. Ltd. 2 March, 1966 [3 March, 1965; 24 May, 1965], No. 9152/66. Heading G5R. A magnetic tape recorder of the type where drive control is effected by a set of pushbuttons B, R, S, P, F, incorporates a tension arm 43 between the drive capstans and wind up reel for sensing the end of, or considerable slackening in, the tape to control a switch 309, which in turn controls a relay 72. The relay plunger controls a lock bar 152, which holds down any selected button during operation of the recorder in play or record modes so as to automatically release the button when the end of the tape is detected. In the recorder, the push-buttons are linked with a brake mechanism incorporating pivoting arms 14, 24, 28, 18 co-operating with the feed and wind up turn discs by the arms 62, 49, 55. A pivotable arm 88 carrying a guide pin 89 is mounted on the chassis panel of the recorder and is normally biased away from the tape by a spring. The arm 88 is mechanically linked with the push-button controls through an arm 201 and the arms 62, 49, 55 so that when the controls are operated to release the brakes the pin moves to an operating position adjacent the tape. This arm 88 evens out jerks and fluctuations in the travel of the tape past the tension arm 43 so that this will not respond incorr ectly. The linkages of the braking system are so designed that when play/record P, fast wind F or rewind B buttons are operated, the brake on the wind up reel is first released and then that on the supply reel. The movement of the member 62 or 49 or 55 actuates related switches in the motor control circuit of the recorder, to apply appropriate forward or reverse currents to the reel motors. These are arranged to drive the feed reel in reverse to maintain the tape tension during play. During fast wind and rewind, the tape is not pressed against the capstan 39 by the pinch roller 40, and the tension arm 43 does not respond to the passage of the tape. When play or record operations are switched to, however, the tension arm detects the tape and operates the switch 309, to bring it to the dashed position in Fig. 11. This causes a relay 96 to be energized, resulting in energization of the relay 72, to change the position of the switch 303 and release the lock bar 152 so that this may operate to lock any depressed push-button. The switch 303 forms together with switch 302, operated when the brake is released, a by-pass circuit which prevents the recorder being turned off by the main manual switch when tape is being wound, so that the motors cannot be cut off. When the end of the tape, or a broken part, is reached, the switch 309 returns to its original position, but the CR circuit 125, 126 is such as to delay the fall out of the relay 96 for 1-2 seconds, to eliminate the possibility of minor fluctuations stopping the tape, and to allow the tape,when the end is reached, to be fully wound up on the take up reel. The relay 72 is linked to the lock bar 152 by a spring biased pivoting arm 76. When the relay is not energized the arm is biased to hold the lock bar, which pivots at 79, 80 (Fig. 1) depressed so that it cannot engage the push-buttons. When the relay is operated the bar is released to adopt a position as shown in Fig. 6 relative to the play button, and a similar position relative to other buttons. When the button P is depressed, the arm 47 presses down and then lodges behind the bar 152.