Typewriting machines – Including interposed inking device for record-medium – Means auxiliary to ribbon mechanism
Patent
1996-10-09
1997-12-09
Yan, Ren
Typewriting machines
Including interposed inking device for record-medium
Means auxiliary to ribbon mechanism
4002081, B41J 3500
Patent
active
056952929
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to thermal transfer printing, and in particular to means for holding the thermal transfer ribbons during storage and during use in thermal transfer printers.
BACKGROUND OF THE INVENTION
Thermal transfer printing is a process for generating printed images by transferring thermally transferable colorant from a thermal transfer ribbon to a receiver. The ribbon usually comprises a base sheet coated on one side with a transfer coat comprising a non-transferable binder containing one or more thermally transferable dyes, or a fusible ink which is all transferable. Printing is effected while the transfer coat is held against the surface of the receiver, by heating selected areas of the ribbon so as to transfer the dyes or inks from those selected areas to corresponding areas of the receiver. This generates an image according to the areas selected. By repeating the transfer process with each of the three primary colours, full colour images can be obtained. Black may also be used.
Thermal transfer printers using a thermal head with a plurality of tiny heaters to heat the selected areas, have been gaining widespread attention in recent years, mainly because of its ease of operation in which the areas to be heated can be selected by electronic control of the heaters (e.g. according to a video or computer-generated signal), and because of the clear, high resolution images which can be obtained in this manner. Alternative thermal energy sources, such as addressable laser systems, are also being developed.
Transfer sheets for such primers are normally in the form of long ribbons, having repeated sequences of print size panels of each primary colour and any other materials to be transferred (e.g. black dyes or ink), such sequence being repeated along the ribbon to enable it to be used for as many prints as there are repeats of the sequence. The ribbons are rolled up and stored in a cassette. These consist essentially of supply and take-up spools, the thermal transfer ribbon extending between the spools with one end loaded onto the supply spool and the other onto the take-up spool, and a casing having spool-locating means to locate and retain the spools spaced apart, parallel and rotatable during printing with the spacing between the spools being predetermined to fit the printer. The cassettes may also be supplied with a small anti-rotation member which is plugged into the ends of the spools to prevent their rotation during transit to the consumer.
Cassette casings typically comprise two parallel spool-housings having end portions interconnected by bridge members such that the housings and bridge members together define an open access port through which the transfer ribbon is exposed as it extends from one spool to the other. However, there is at present no overall industry standard for thermal transfer printers and cassettes, and the specific configurations of the latter are largely determined by the printers with which they are to be used, both in respect of the overall shape and size (e.g. they must fit correctly into the space provided), and also in respect of the functional requirements (e.g. they must meet the requirements of various sensors normally built into the printer). There may also be differences between cassettes for printers using thermal heads to effect transfer and those which are laser driven.
Such casings can represent a substantial proportion of the cost of the cassette, but after all the transfer ribbon has been used up, they are usually discarded. However, some known cassettes do have an open configuration which leaves the spools and their spent transfer ribbons accessible for replacement. Such replacement may be facilitated by permitting longitudinal movement of the spools in the casing from a free to a retained position, and some form of spring, e.g. leaf springs or coil springs around the spool ends, provided to bias the spools into their retained positions.
Unfortunately, ribbon replacement is not without its difficulties. The colorants used in the
REFERENCES:
patent: 5248208 (1993-09-01), Yoshida et al.
patent: 5399035 (1995-03-01), Nakae
patent: 5433540 (1995-07-01), Alday
patent: 5605403 (1997-02-01), Vegeais et al.
Imperial Chemical Industries plc
Yan Ren
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