An analog data recording and playback system for controlling movement in a path direction defined by X and Y coordinates in a rectangular coordinate plane, comprising, in combination:
- a. a table mounted for movement in said plane;
- b. an X-servo motor coupled to said table to move said table in the direction of the X-coordinate axis in said plane when energized;
- c. a Y-servo motor coupled to said table to move said table in the direction of the Y-coordinate axis in said plane when energized;
- d. an X-drum mechanically geared to movements of said table to rotate at a rate proportional to the speed of movement of said table in the X-axis direction;
- e. a Y-drum mechanically geared to movements of said table to rotate at a rate proportional to the speed of movement of said table in the Y-axis direction, said X-drum and Y-drum each including at least one circumferential row of peripheral slots parallel to the axis of the associated drum, the drums being spaced one ahead of the other and having their axes parallel and laterally displaced by a given distance;
- f. a negative photographic film of given width greater than said given distance;
- g. film drive means for moving said film in the axial directions of said drums adjacent to their exterior peripheries;
- h. resolver means responsive to the vector sum of the speeds of movement of said table in the X and Y axes directions connected to said film drive means to move said film at a speed directly proportional to the speed of said table in said plane;
- i. a recording source of light directed radially from the interior of each drum towards said film so that bars of light images are successively exposed on said film along parallel X and Y film tracks separated by said given distance of lateral displacement of the axes of said X drum and Y drum as said drum rotate and said film moves, the successive bars of light images of the X and Y tracks being skewed relative to the direction of movement of the film in accordance, respectively, with the relative rates of rotation of the drums and speed of movement of said film whereby there is simultaneously optically recorded on said X and Y tracks of the film patterns of bars of light images defining, respectively, given movements of said table in the X and Y directions of said coordinate plane;
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- j. playback means including photo-cell means and switch means for connecting said photo-cell means to the X and Y servo motors, said X and Y drums each having a second row of circumferential peripheral slots spaced apart the same direction as the slots in the first row and circumferentially displaced by the width dimension of one slot;
- two light sources for each drum, said photo-cell means being responsive to light from the sources passing through said X and Y film tracks respectively and the second rows of slots respectively to cause the table to execute said given movements in accordance with the patterns of bars of light images in said tracks by means of signals developed in said photo-cell means responsive to any tendency for the X and Y drums to rotate out of synchronism with the X and Y track patterns on said film, said photo-cell means including for each drum a pair of photo cells positioned to receive light passing through the film track and associated second row of slots in the drum, the pair of photo cells being positioned such that when the relative intensity of light from each of the two light sources differs, the associated drum and table are driven by the associated servo motor to vary the rate of rotation of the drum relative to the speed of film movement in the playback operation to minimize such difference, whereby the table will be moved along a path in the X and Y coordinate plane defined by the originally optically recorded program of given movements on said film.