Typewriting machines – Including interposed inking device for record-medium – Ribbon-feeding mechanism
Patent
1996-11-26
1998-10-13
Burr, Edgar S.
Typewriting machines
Including interposed inking device for record-medium
Ribbon-feeding mechanism
4001961, B41J 3328, B41J 3314
Patent
active
058202781
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a.sctn. 371 of PCT/IT95/00086 filed on May 22,1995.
FIELD OF THE INVENTION
The present invention relates to a device for feeding a printing ribbon, comprising a pair of gears formed by a first gear and a second gear mutually meshed, wherein the printing ribbon is interposed between the engaged teeth of said pair of gears, so as to assume a first configuration having a corresponding first plurality of windings which follow the profile of the engaged teeth of the pair of gears.
BACKGROUND OF THE INVENTION
From the European Patent Application No. 313 245, a device of this type is known, which is mounted within a cartridge and which is particularly suitable to allow the printing ribbon to advance towards a magazine, within which the same ribbon is randomly arranged in the form of turns. This device is not capable, in all the conditions, of supplying the printing ribbon with a constant and sufficient traction force, necessary to allow the ribbon to advance in a regular and uniform way, for overcoming all the frictions that the same ribbon meets in its path. Consequently in this device the ribbon may slide with respect to the ribbon driving gears. This inconvenience may mainly happen in the so-called high capacity cartridges, in which either the printing ribbon length to draw, or the friction force opposing to the feeding of the same ribbon, are higher than the usual.
SUMMARY OF THE INVENTION
The technical problem that the present invention aims to solve is that of realizing a printing ribbon feeding device for generating a feeding force which allows the printing ribbon to advance in a regular way and without slidings, even when the feeding force has to assume high values during very critical operating conditions.
This technical problem is solved by the feeding device according to the present invention, comprising a third gear having a diameter equal to the diameter of the first gear and meshed with the latter to form a second pair of gears, wherein the printing ribbon is interposed also between the meshed teeth of the second pair of gears, so as to assume, in addition to the first configuration, a second configuration having a second plurality of windings which correspond to the profile of the engaged teeth of the second pair of gears, the development of the second plurality of windings being greater than the development of the first plurality of windings; resilient means which constantly urge with a predetermined force, one against the other, the gears of at least one of the pair of gears, whereby said printing ribbon is constantly pressed between the gears of such one pair of gears and is fed with a predetermined feeding force proportional to the above predetermined force; and a driving shaft connected with one of the gears for driving the three gears in such a way to advance the ribbon from the first pair to the second pair of gears, whereby the portion of the printing ribbon comprised between the first and second configurations is constantly kept under tension.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the present invention will be clear by the following disclosure, given by way of non-limiting example, with reference to the accompanying drawings, in which:
FIG. 1 is a perspective view of a device for the feeding of a printing ribbon according to the invention; and
FIG. 2 is a partial plan view of the device of FIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2 a feeding device 11 for a printing ribbon 12, according to the present invention, comprises a pair of gears 13 and 14 with a plurality of teeth 15, and respectively 16, mutually meshed and a driving shaft 17 fixed to the gear 14 and suitable to receive , in a known manner, the rotary motion from a motor member, for example from a printing carriage, not shown in the drawings.
The printing ribbon 12, of a known type, for example made by inked web, is interposed between the gears 13 and 14 and is obliged, in a portion 18 thereof
REFERENCES:
patent: 4091914 (1978-05-01), Stipanuk
patent: 4343556 (1982-08-01), Kobayashi
patent: 5030022 (1991-07-01), Casey
patent: 5083878 (1992-01-01), Surti
patent: 5114254 (1992-05-01), Sato et al.
patent: 5354138 (1994-10-01), Daggs
Burr Edgar S.
Olivetti Lexikon S.p.A.
Sandusky Amanda B.
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