Plural motor tape drive including information searching and tension control

摘要

912,779. Record tape apparatus ; digital data storage apparatus. CREED & CO. Ltd. July 27, 1961, No. 27288/61. Class 106 (1). Record tape apparatus consists of means for feeding tape having a plurality of sections from one reel to another, means for detecting a selected section, means operative on detection of the selected section to cause the tape to be fed in a reverse direction to permit information to be stored in and withdrawn from the selected section. The tape may be a punched tape having eight channels, six for the data, one for sprocket holes and one for section perforations. A section perforation is placed in the middle of each section so that a desired section may be formed by counting pulses derived from these perforations by photo-cells P1 or P2. The reels 2, 3 are driven by motors 6 and 7 and each has an electromagnetic brake 8, 9. The motors themselves can be connected to act as brakes, the arrangement being that when one is driving, the other is acting as a brake and if the drive is switched off, both act as brakes to slow the tape down before the brakes 8, 9 are applied. Near each reel is a capstan C1, C2 which comprises driven rollers 11, 12 which in the operative position engage the tape, as shown in Fig. 3. Stops 20 and 21 limit the movement of the arm of the capstan in the two positions. Initially the capstans are in the inoperative position. Switches controlled by each capstan indicate which condition it is in. The sensing station consists of a sprocket-wheel 34, Fig. 4, and blocks 35, 36 housing the sensing pins 37. The sprocket wheel is driven step-by-step to bring the rows in turn over the sensing pins. The tape is normally held out of contact with the sprocket wheel by spring-loaded guide-plate 38, but when the desired section is found a pressureplate 44 is lowered to press the tape against the sprocket wheel. To ensure that the holes engage with the pins of the sprocket wheel the tape is oscillated lengthwise by a mechanism T1 having jaws 29, 31 to grip the tape and a cam 27 to oscillate the jaw mounting-plate 25. The pressure applied by plate 44 is so light that, unless the holes in the tape register with the sprocket wheel pins, the tape holds the plate up. When the tape is properly engaged with the pins it is pressed down on to the sprocket pins and is ready for sensing. In the initial condition the tape is disposed half on each side of the sensing station. If the section selected is in reel 2, photo-cell P1 is operative and motor 7 is energized to move the tape to the right and the armature of motor 6 is short-circuited through a resistance so that it acts as the brake. The tape then runs at high speed (80 feet per second) the section hole signals from photo-cell P1 entering a counter. During this motion the capstan units are both out of operation, as shown in Fig. 1. When the counter reaches a predetermined first count the tape is slowed down by inserting a resistance in series with motor 7 and another across it and by shorting motor 6. Both motors therefore act as brakes until a slow speed of 5 feet per second is reached. The tape continues at the slow speed until a predetermined second count is reached. The tape is then stopped by brakes 8 and 9, the desired section now being to the right of the sensing station. The capstans are now rotated into contact with the tape (Fig. 3), the tape oscillating unit T1 comes into operation and the pressure-plate 44 descends to engage the tape with the sprocket wheel. The motor controls are reversed so that motor 6 applies a slight tension to the tape and motor 7 acts as a brake, capstan C1 draws the tape from reel 3 and capstan C2 rotating in the opposite direction relieves the tension to the tape in the sensing station. The tape steps through the sensing station moving in a leftwise direction until the selected section is read. When the sensing is finished the tape returns to its initial position, the counter counting back to zero to slow and then stop the tape at the appropriate position. A punch unit may replace the sensing station to enable information to be entered in the selected station. Instead of being a punched tape the tape may be magnetic, the sections being indicated by magnetic marks which are sensed and counted in the same way.