Patent GB-1509992-A (GB)
Title: Record medium transport apparatus
IPC: G09B5/04
Filed: 1975-04-10
Abstract: 1509992 Tape transports L R DeBELL and D D PRICE 10 April 1975 9901/75 Heading G5R Rotation of a tape drive motor 60, Fig. 6, produces voltage transients in the electric power supply energizing the motor, a circuit 264 responds to the transients to provide a varying output signal proportional to the rotational speed of motor 60, and a control circuit 260 de-energizes the motor 60 if said output signal is below a threshold value. The invention may be applied to open-reel, endless-loop cartridge, or, as shown, twin-reel magnetic tape cassette apparatus having a capstan 68, Fig. 1, supply 34 and take-up 36 drive hubs driven by respective motors 72, 48, 60, Fig. 6, a motor (114) Fig. 3 (not shown) being operable to rotate a star wheel (108) acting on a follower (116) to cause pivoting of a bar 74 about pins 82, 84 to an operative position. Bar 74 carries a pinch roller 96, replay head 32 and, optionally, a record head 28, and its position is sensed by a microswitch 102. Head 32 replays audio signals via a playback circuit, Fig. 4 (not shown), and control tone signals, useful in teaching machine applications and recorded on the same or a different track to the audio signals, are also replayed by head 32 via a circuit, Fig. 5 (not shown), which filter out signals at a first frequency, such as 1500 or 60 Hz, to supply a corresponding control signal to an input 252, 316 of a tape transport control circuit, Fig. 6. The control tone replay circuit may have a second section (460), Fig. 5, to distinguish control tones at a second frequency, e.g. 200 Hz, to provide an output on line (462) for actuation of auxiliary equipment such as associated visual equipment or tutoring tally equipment. The transport control circuit, Fig. 6, has a logic section with four modules each having four NAND gates, modules 266, 268, 270 controlling rewind motor 48, forward motor 60 and capstan motor 72 respectively and module 272 being a STOP latch. When a power switch 295 is turned ON, motor 114 is energized to pivot bar 74, head 32 and pinch roller 68 to the operative position. To effect playback a RESTART switch 312 is operated to cause modules 268, 270 to energize motors 60, 72. Take-up motor 60 is a D.C. type and causes negative-going voltage spikes or the brushes cross gaps between armature segments, these spikes being sensed by tape motion sense circuit 264 comprising transistors 390, 406 and R-C integrator 404, 388 and giving a control signal on line 360 to module 272. Circuit 264 acts to de-energize motors 60, 72 on sensing any end of tape, failure of motor 60 and/or of drive hub 36, tape snagging or windup at capstan 68, and any condition in which motor 60 ceases to turn. Rewind and fast forward modes are selected by push-buttons 446, 442 respectively. Operation of a REPEAT switch 294 enables repeated replay of a specifically tined section by energizing rewind motor 48 for a period determined by capacitor 290 and time-setting adjustable resistor 288. When the control tone replay circuit gives an input at 252, 316, modules 266, 268, 270 act to stop the tape by de-energizing motors 60, 72. A light 450 indicates the STOP mode. Terminals such as 314, 444, 448 allow remote control operation.