Ribbon drive arrangement for a printer

Claim 2

Tape drive apparatus for advancing a tape from a supply, said tape drive apparatus comprising: a tape reel mounted for rotation about a reel axis, said reel defining a wrap plane for tape accumulation as a cylinder of overlaid convolutions having an outer circumference; an elongate drive blade, mounted to move generally in said wrap plane, and having a drive edge that is asymmetrically textured to have a higher tendency to slip in a first longitudinal direction than in the opposite longitudinal direction; means for urging said drive edge against said outer circumference of said tape cylinder; means for oscillating said drive blade whereby said drive edge imparts increments of motion to said tape reel in the direction corresponding to the lower tendency for drive edge slippage.

Claim 3

A tape drive apparatus according to claim 1 wherein said tape reel has first and second spaced flanges perpendicular to said reel axis between which said tape cylinder is accumulated.

Claim 4

A tape drive apparatus according to claim 2 wherein said blade is mounted to move in a plane intermediate said first and second flanges.

Claim 5

A tape drive apparatus according to claims 1 or 3 wherein said drive blade is pivoted to rotate about a blade pivot axis parallel to said reel axis and said drive edge has the shape of an involute for a generating circle centered at said blade pivot axis, whereby said drive edge strikes said outer tape circumference tangentially over a range of tape cylinder diameters.

Claim 6

A tape drive apparatus according to claim 1 wherein said drive edge is textured with sawtooth-like serrations.

Claim 7

A tape drive apparatus according to claim 4 wherein said drive edge is textured with sawtooth-like serrations.

Claim 8

A tape drive apparatus according to claim 1 wherein said oscillating means includes a drive member, to which said drive blade is pivotally mounted, which drive member is mounted to pivot about an axis that is generally perpendicular to said wrap plane, and means for vibrating said drive member over a narrow arc whereby a back-and-forth motion is transmitted to said drive blade.

Claim 9

A tape drive apparatus according to claim 4 wherein a brake acts on said tape reel to prevent motion opposite the forward direction.

Claim 10

A tape drive apparatus for advancing a tape from a supply, said tape drive apparatus comprising: a tape reel removeably mounted for rotation about a reel axis to accumulate tape as a cylinder of overlaid convolutions having an outer circumference; an elongate drive blade, mounted to move in a wrap plane generally perpendicular to said reel axis and intersecting said cylinder, said drive blade having a drive edge that is asymmetrically serrated to have a higher tendency to slip in a first longitudinal direction than in the opposite longitudinal direction, said drive edge having the contour of an involute for a generating circle; means for urging said drive edge against said outer circumference of said tape cylinder; means for reciprocating said drive blade in said wrap plane whereby said drive edge imparts increments of motion of said tape reel in a forward direction corresponding to the lower tendency for drive edge slippage.

Claim 11

A tape drive apparatus for advancing a tape from a supply, said tape drive apparatus comprising: a tape reel removeably mounted for rotation about a reel axis to accumulate tape as a cylinder of overlaid convolutions having an outer circumference; an elongate drive blade, mounted to move in a wrap plane generally perpendicular to said reel axis and intersecting said cylinder, said drive blade having a drive edge that is asymmetrically serrated to have a higher tendency to slip in a first longitudinal direction than in the opposite longitudinal direction, said drive edge having the contour of an involute for a generating circle; means for urging said drive edge against said outer circumference of said tape cylinder; means for reciprocating said drive blade in said wrap plane whereby said drive edge imparts increments of motion of said tape reel in a forward direction corresponding to the lower tendency for drive edge slippage.

Claim 12

A tape drive apparatus according to claim 9 wherein said drive blade is mounted to pivot about an axis corresponding to the center of said generating circle and said reciprocating means moves said drive blade in directions generally perpendicular to a line extending from said reel axis to be tangent to said generating circle.

Claim 13

A tape drive apparatus according to claim 9 or 10 wherein a displaceable latch is provided for holding said drive blade away from said tape reel to facilitate replacement of said reel.

Claim 14

A tape drive apparatus according to claim 11 wherein said latch is positioned to be released by mounting of a tape reel.

Claim 15

For use in a printer, a ribbon advancing mechanism comprising: a reel for receiving said ribbon; means for releasably mounting said reel for rotation about a reel axis; a drive blade mounted on a drive bar to rotate about a blade pivot axis generally parallel to said reel axis, said drive blade having a drive edge in the shape of an involute for a generating circle centered at said blade pivot axis, said drive bar being mounted to rotate about an axis parallel to and spaced from said blade pivot axis; biasing means for urging said drive blade about said blade pivot axis with said drive edge forward to engage the outer periphery of ribbon accumulated at said reel, said drive edge having serrations establishing a gripping direction and an opposite slip direction; means for oscillating said drive bar whereby motion is transmitted to said reel through said drive blade during portions of oscillations corresponding to motion of said drive edge in said gripping direction.

Claim 16

For use in a printer, a ribbon advancing mechanism comprising: a reel for receiving said ribbon; means for releasably mounting said reel for rotation about a reel axis; a drive blade mounted on a drive bar to rotate about a blade pivot axis generally parallel to said reel axis, said drive blade having a drive edge in the shape of an involute for a generating circle centered at said blade pivot axis, said drive bar being mounted to rotate about an axis parallel to and spaced from said blade pivot axis; biasing means for urging said drive blade about said blade pivot axis with said drive edge forward to engage the outer periphery of ribbon accumulated at said reel, said drive edge having serrations establishing a gripping direction and an opposite slip direction; means for oscillating said drive bar whereby motion is transmitted to said reel through said drive blade during portions of oscillations corresponding to motion of said drive edge in said gripping direction.

Claim 17

A ribbon advancing mechanism according to claim 13 wherein said reel includes flanges perpendicular to said reel axis for confining accumulated ribbon.

Claim 18

A ribbon advancing mechanism according to claim 13 wherein said serrations are asymmetrical teeth on said drive edge.