Tape transport control apparatus

Claim 1

In a magnetic recording and playback system having a tape supply reel and a takeup reel separated by a stationary magnetic head, a tape transport control apparatus comprising: An idler roller rotatably disposed between said supply and takeup reels in close proximity to said recording head; a magnetic recording tape extending between said reels and having a portion thereof trained about the periphery of said idler roller in frictional driving relationship therewith for sensing tape speed whereby said tape is supplied from said supply reel to said recording head for storage on said takeup reel; torque clutches operatively coupled to each of said reels for controlling the rotation thereof; a continuously operating drive motor; a pulley arrangement operably connecting said motor to said reels via said torque clutches for driving said reels; a tape speed control means operably driven by said idler roller and electrically coupled between said idler roller and at least one of said torque clutches for translating tape velocity into control signals adapted to adjust the torque of said torque clutches whereby tape movement is controlled thereby; each of said torque means comprising an eddy current clutch; said control means including a control drum rotationally coupled to said idler roller and having a plurality of parallel tracks carried thereon wherein each track includes reference signals prerecorded thereon at a frequency different from said reference signals on an adjacent track; said control means further including an electrical network coupling said control drum to said torque clutch associated with said takeup reel for converting a selected track of reference signals to a control current for regulating the torque of said takeup reel clutch; said electrical network including: a sensing head for deriving said selected reference signals; an amplifier and square wave network coupled to said sensing head for amplifying and shaping said sensed reference signals; a frequency-to-voltage converter connected to said last mentioned network; a voltage comparator coupled to said converter; amplifier means coupled bEtween said comparator and said torque clutch of said takeup reel; a feedback loop interconnected between said comparator and said amplifier means; a second electrical network for regulating the current applied to said torque clutch of said supply reel; and a differential voltage divider interconnecting said second electrical network with said first mentioned electrical network whereby both of said clutches are controlled by said selected reference signals.