Typewriting machines – Including interposed inking device for record-medium – Endless ribbon or cartridge therefor
Patent
1984-10-10
1987-02-24
Wright, Jr., Ernest T.
Typewriting machines
Including interposed inking device for record-medium
Endless ribbon or cartridge therefor
400234, 400248, B41J 3502
Patent
active
046453636
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to an arrangement in typewriters and the like, where a printing ribbon is led over at least three guide means having cylindrical guide surfaces, for eliminating stresses in the transverse direction of the ribbon when the ribbon is displaced transversely of its direction of travel at the printing location.
BACKGROUND
Typewriters, line printers and similar printing apparatus are usually provided with ribbons which, by the action of the printing means, apply pigment to the medium on which the pigment is to be printed. Ribbons with black and red pigment have been used for a long time. Demands for the availability of printing with several colors has led to wider ribbons, where the pigments are disposed as bands along the ribbon. For printing is a given color, the ribbon is raised or lowered in relation to the printing means at the printing location. The ribbon is led from a storage region to the printing location and from there back again to the storage region with the aid of guide means for keeping the ribbon in position at right angles to its direction of travel, and guiding means for changing the direction of the ribbon. To avoid shear stresses in the transverse direction of the ribbon, the cylindrical surfaces of the guiding means engaging the ribbon must be oriented at rightangles to the plane in which the ribbon is advanced.
A known method of solving the problem mentioned is to turn the ribbon magazine with its guide and guiding means about an axis in the plane of the magazine for printing at different ribbon levels. Other ways are to guide the ribbon over a plurality of guiding rollers mounted on pivotable arms, or to form the guiding means with concave or convex contours. All these solutions result in mechanically complicated arrangements.
SUMMARY OF THE INVENTION
The present invention solves the mentioned difficulties by pivotally mounting the guiding means, with the aid of which the direction of the ribbon is changed, such that forces in the transverse direction of the ribbon are eliminated.
In accordance with the invention, there is provided a pivotally mounted guide means in an endless ribbon cassette which has a ribbon magazine with opposite cover plates and an end wall between the cover plates. The guide means is pivotally mounted in the cassette between the cover plates in a space in the end wall and the guide means comprises a substantially cylindrical body having a longitudinal axis and a longitudinal slot therein for receiving an edge portion of the end wall which bounds the space therein. The cylindrical body has an outer cylindrical surface on which the ribbon passes during ribbon travel. The body has a surface at the bottom of the slot with a portion in pivotal contact with the edge portion of the end wall and wherein one of said portions includes two sloped surfaces which intersect along a line midway between end surfaces of the cylindrical body. The line of intersection of the two sloped surfaces, constitutes a pivot axis for said cylindrical body on said edge portion of said end wall. The end surfaces of the cylindrical body are confined between the cover plates for limiting longitudinal movement of the body between the cover plates. The edge portion of the end wall is fitted in said slot and prevents turning of the guide body around the longitudinal axis thereof.
BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING
The invention will be described in detail in conjunction with the accompanying drawings, wherein
FIG. 1 schematically illustrates the parts of a typewriter which are of interest for explaining the invention;
FIG. 2 is a side view of the ribbon path;
FIG. 3A is a front elevational view of a guide roller according to a first embodiment of the invention;
FIG. 3B is a transverse sectional view of the guide roller;
FIG. 3C shows the guide roller in operation;
FIG. 3D is an end view of the guide roller;
FIG. 4A is a front elevational view of another embodiment of the guide roller;
FIG. 4B is a transverse sectional view of the guide
REFERENCES:
patent: 2685357 (1954-08-01), Koreska
patent: 3900099 (1975-08-01), Hengelhaupt
patent: 3977512 (1976-08-01), Teagarden et al.
patent: 4003460 (1977-01-01), Gray et al.
patent: 4084683 (1978-04-01), Moss
patent: 4247209 (1981-01-01), Carlson et al.
IBM Technical Disclosure Bulletin, "Adjustable Ribbon Tracking Device", Lentz, vol. 16, No. 6, Nov. 1973, pp. 1751-1752.
IBM Technical Disclosure Bulletin," Compressible Ribbon Roller for Constant Tension," Craft, vol. 23, No. 10, Mar. 1981, pp. 4553-4554.
Xerox Disclosure Journal, "Uniform Ribbon Tension for Impact Printer Ribbon", Kockler et al, vol. 4, No. 2, Mar./Apr. 1979, pp. 181-182.
Xerox Disclosure Journal, "Multi-Track Ribbon Lift Control", Plaza, vol. 4, No. 3, May/Jun. 1979, p. 417.
Telefonaktiebolaget LM Ericsson
Wright, Jr. Ernest T.
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