Typewriting machines – Means auxiliary to typewriting function – Frame – casing – or support for typewriter
Reexamination Certificate
1999-11-01
2001-07-31
Colilla, Daniel J. (Department: 2854)
Typewriting machines
Means auxiliary to typewriting function
Frame, casing, or support for typewriter
C400S693000, C400S120010, C347S222000
Reexamination Certificate
active
06267521
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to printers, e.g., computer-driven, which imprint patterns from a print head through a ribbon to a print medium, e.g., paper, and in particular to printers of the type which can utilize thermal transfer ribbons. Prior art printers suitable for printing bar code labels and the like are typically comprised of 1) a thermal print head, 2) a drive roller mounted opposite to the print head, 3) a print medium subsystem including a supply reel for guiding a print medium along a path extending between the print head and the drive roller, 4) a ribbon subsystem including a supply reel and a takeup reel for guiding a ribbon along a path extending between the print head and the print medium path, 5) a spring for urging the print head toward the drive roller to pinch the print medium and the ribbon therebetween and 6) a motor mechanism for causing the drive roller to move the print medium and the ribbon in either a forward or a reverse direction.
SUMMARY OF THE INVENTION
The present invention is directed to a printer apparatus particularly configured to maintain tension on a ribbon to prevent ribbon wrinkling regardless of the direction the ribbon is moved.
In accordance with the invention, torque accumulation devices are coupled to the ribbon supply and ribbon takeup reels to maintain the ribbon tension. More particularly, the ribbon takeup reel torque accumulation device is configured to drive the takeup reel (e.g., clockwise) when the print medium and ribbon are moved in a forward direction and the ribbon supply reel torque accumulation device is configured to drive the supply reel (e.g., counter-clockwise) when the print medium and ribbon are moved in a reverse direction. When the takeup reel is being driven, the supply reel produces a drag to maintain ribbon tension. When the supply reel is being driven, the takeup reel produces drag to maintain ribbon tension.
In a preferred embodiment, a drive motor coupled to a drive roller for moving the print medium and the ribbon is also coupled to the takeup reel torque accumulation device to accumulate torque, i.e., store energy. When the drive motor (via the drive roller) moves the print medium in a forward direction, it is this accumulated torque that urges rotation of the takeup reel. As the ribbon moves forward, the supply reel torque accumulation device accumulates torque which acts as a drag on supply reel. However, when the drive motor reverses direction, the accunmated torque in the supply reel accumulation device urges rotation of the supply reel that is resisted by the takeup reel accumulation device. These two opposing torques maintain the ribbon in tension, independent of its movement.
In accordance with a further aspect of the invention, a preferred printer facilitates loading of a print medium, e.g., paper, and a ribbon which both pass between a print head and platen. To facilitate loading, a preferred printer apparatus is formed using a clam shell housing comprised of two assemblies that are rotatably coupled at a first end and are latchable at a second end. The first assembly includes the platen and the second assembly includes the print head such that when the two assemblies are unlatched and rotated apart, feed paths for the print medium and the ribbon are accessible to an operator.
In accordance with a still further aspect of the invention, a preferred printer automatically centrally orients a roll of print medium, e.g., paper, before it passes an area between,a print head and platen, i.e., a print surface. Such embodiments are preferably comprised of a non-rotatable axle which supports a roll of print medium wound around a hollow core. This axle has an upper concave surface which tends to automatically center the hollow core within the concave surface as print medium is withdrawn and thus automatically centers the print medium as it approaches the print surface.
The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.
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Bryer Philip Stuart
Harb Douglas LeRoy
Lodwig Dean H.
Colilla Daniel J.
Eltron International, Inc.
Fulbright & Jaworski L.L.P.
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