Tape tension and velocity control system

Claim 2

<Apparatus for controlling a web member such as a magnetic tape comprising: pickup and supply reels for said tape; means for guiding said tape along a predetermined path including a tape head from one to the other of said reels; tape drive means for frictionally engaging the tape to drive it along the path; reel drive means for driving said reels; at least one main vacuum chamber for developing at least one buffering loop in said tape along said path; means for developing a control signal proportional to the extent of the loop in said chamber, said means comprising a transducer responsive to a selected parameter which varies within limits as the length of the tape loop is varied and a wall portion of said chamber having a predetermined non-linear configuration selected to linearize the relationship between the selected parameter and the length of the tape loop; means for controlling the reel drive means in response to said control signal; and means defining a plenum chamber adjacent the vacuum chamber, the wall portion including means for controlling the pressure in the plenum chamber in accordance with the extent of the tape loop in the vacuum chamber.

Claim 3

Apparatus in accordance with claim 1 further comprising: a piston responsive to the pressure in the plenum chamber; a cantilever beam coupled to the piston for movement in response thereto; and means responsive to movement of the cantilever beam for developing a proportional control signal.

Claim 4

Apparatus in accordance with claim 1 wherein the wall portion comprises an apertured member having a predetermined arrangement of apertures varying in size and juxtaposition for communicating between the vacuum chamber and the plenum chamber.

Claim 5

Apparatus in accordance with claim 1 wherein the wall portion comprises an elongated bar mounted along the wall of the vacuum chamber and having a plurality of variably spaced and sized apertures extending transversely between the face of the bar adjacent the vacuum chamber and the plenum chamber.

Claim 6

Apparatus in accordance with claim 4 wherein the plenum chamber comprises a slot extending along the face of the bar remote from the vacuum chamber and communicating with said apertures.

Claim 7

Apparatus in accordance with claim 5 wherein said slot is semi-circular in cross-section with a radius approximately three times the depth of the apertures communicating therewith.

Claim 8

Apparatus in accordance with claim 4 wherein said apertures comprise circular holes aligned side by side in a single row and arranged in three different size categories.

Claim 9

Apparatus in accordance with claim 7 wherein the bar contains 39 holes communicating with the plenum chamber, the seven holes nearest the opening of the vacuum chamber being largest in diameter, the 20 holes farthest from the opening of the vacuum chamber being intermediate in diameter, and the remaining 12 holes positioned along an intermediate section of the bar being smallest in diameter.

Claim 10

Apparatus in accordance with claim 8 wherein the largest holes are approximately 0.026 inches in diameter, the intermediate size holes are approximately 0.024 inches in diameter, and the smallest size holes are approximately 0.0225 inches in diameter.

Claim 11

Apparatus in accordance with claim 7 wherein the holes are arranged in four groups according to spacing.

Claim 12

Apparatus in accordance with claim 10 wherein the first four holes nearest the opening of the vacuum chamber are equally spaced at approximately 0.3 inches on centers, the spacing on centers to the next 26 holes is approximately 0.45 inches, the spacing on centers to the next five holes is approximately 0.3 inches, and the spacing on centers to the next four holes in approximtaly 0.15 inches.

Claim 13

Apparatus in accordance with claim 1 comprising: a pair of main vacuum chambers positioned in side-by-side relationship and having respective open ends at opposite sides of the tape head and tape drive means for developing respective buffering loops at opposite sides of said head and tape drive means; and independent control signal developing means associated with respective ones of the main vacuum chambers.

Claim 14

Apparatus in accordance with claim 12 further including an auxiliary vacuum chamber adjacent the head on the side thereof remote from the tape drive means and positioned along the tape path between the opening of the main vacuum chamber on said side of the head and the head itself.

Claim 15

Apparatus in accordance with claim 13 wherein said auxiliary vacuum chamber includes a variable impedance orifice for controlling the vacuum within the auxiliary chamber.

Claim 16

Apparatus for controlling a web member such as a magnetic tape comprising: pickup and supply reels for said tape; means for guiding said tape along a predetermined path including a tape head from one to the other of said reels; tape drive means for frictionally engaging the tape to drive it along the path; reel drive means for driving said reels; at least one main vacuum chamber for developing at least one buffering loop in said tape along said path; means for developing a control signal proportional to the extent of the loop in said chamber, said means comprising a photocell and associated light source mounted along the web member path within the vacuum chamber such that an adjacent segment of the web member loop acts as a light shield which varies the amount of radiant energy incident on the photocell in accordance with the angle of the loop segment, and a wall portion of said chamber having a predetermined non-linear configuration selected to linearize the relationship between the amount of radiant energy icident on the photocell and the length of the tape loop, said wall portion comprising a non-planar side wall shaped to change the angle of said loop segment relative to the photocell in accordance with variations in extent of the loop in the chamber; and means for controlling the reel drive means in response to said control signal.

Claim 17

Apparatus for controlling a web member such as a magnetic tape comprising: pickup and supply reels for said tape; means for guiding said tape along a predetermined path including a tape head from one to the other of said reels; tape drive means for frictionally engaging the tape to drive it along the path; reel drive means for driving said reels; at least one main vacuum chamber for developing at least one buffering loop in said tape along said path; means for developing a control signal proportional to the extent of the loop in said chamber, said means comprising a photocell and associated light source mounted along the web member path within the vacuum chamber such that an adjacent segment of the web member loop acts as a light shield which varies the amount of radiant energy incident on the photocell in accordance with the angle of the loop segment, and a wall portion of said chamber having a predetermined non-linear configuration selected to linearize the relationship between the amount of radiant energy icident on the photocell and the length of the tape loop, said wall portion comprising a non-planar side wall shaped to change the angle of said loop segment relative to the photocell in accordance with variations in extent of the loop in the chamber; and means for controlling the reel drive means in response to said control signal.

Claim 18

Apparatus in accordance with claim 15 wherein the non-planar side wall comprises a concave arcuate surface extending generally along one side of the loop and developing different angles of tangency for said one side of the loop in accordance with the position of the loop within the chamber.

Claim 19

Apparatus in accordance with claim 15 wherein said non-planar side wall is arranged to vary the area of the photocell receiving light from the light source in proportion to the extent of the loop within the chamber.

Claim 22

The method of claim 18 further comprising the step of applying a selected portion of the vacuum established in the vacuum chamber to a pressure responsive member connected to the free end of the cantilevered member.