Method and device for the determination and display of the spent playing time or length of tape and/or the remaining running time of cassettes or reels for tape record carriers

摘要

1. Process for determining and displaying the elapsed playing time or tape length and/or the remaining playing time of cassettes or reel-to-reel tape-like information media in video magnetic tape recording and playback equipment, in which the speeds or the pulses derived therefrom of two drive shafts are set in relation and, from this, the elapsed playing time (tP ) and/or the remaining playing time (tPO -tP ) is determined by arithmetic operations in a computer unit (1) and displayed in a display unit (2), the values being determined during a brief measuring operation at any desired tape speed and the specific data, for the reel or cassette, stored in the computer unit (1), in particular the stored overall playing time (tPO ) being evaluated by the computer unit (1), characterised by the combination of the following features : - after loading of the reel or cassette, its specific data are scanned via a scanning device - a measuring operation for determining the tape position is carried out, the stored specific data and the measured data for the reel or cassette being processed successively in the computer unit in accordance with the following regulations tp /tPO = 1+ CT (1 -OMEGA 1-2 )/1+OMEGA 1-2 for n1 n2 with OMEGA 1 = n1 /n2 and tp /tPO = 1- 1+CT (1-OMEGA 2-2 )/1+ OMEGA 2-2 for n1 n2 with OMEGA 2 = n2 /n1 = 1/OMEGA 1 , where n1 = speed of the take-up reel and n2 = speed of the supply reel and tp is the elapsed playing time, tPO is the overall playing time and CT is the tape constant (tape winding information), which is obtained from : CT = pi . dO-2 /4 . tT . 1T , where dO is the diameter of the unrecorded wound tape, tT is the tape thickness and 1T is the tape length, and finally being displayed in the display unit (2) as elapsed playing time (tp and/or remaining playing time (tPO -tP ), - for driving the motors (M1; M2 ) for the adjustment of tape tensions, the output signals of the computer unit (1) are then converted into pulse-duration modulated signals, integrated and subsequently converted from voltage to current, the output signals being formed in each case by a linear equation for each motor (M1; M2 ) according to the following mathematical relationship : YM1 = C1 . tP+b1 YM2 = C2 .tP +b2 where the motor control constants C1 , C2 , b1 , b2 are stored in the computer unit (1).