This invention relates generally to ink jet apparatus, and more particularly to ink jet apparatus wherein the ink employed within the jet is of the phase change type which may also be referred to as hot melt ink.
A phase change or hot melt ink of the type utilized in an ink jet apparatus is characteristically solid at room temperature. When heated, the ink will melt to a consistency so as to be jettable. Examples of hot melt inks suitable for use in ink jet apparatus are disclosed in U.S. Pat. Nos. 4,390,369, 4,484,948, and U.S. Pat. No. 4,659,383, each of which are assigned to the assignee of the present invention, and are incorporated herein by reference. A hot melt ink jet apparatus and method of operation, suitable for use with the above-referenced hot melt inks, is also disclosed in U.S. Ser. No. 610,627, filed May 16, 1984, now abandoned in favor of its continuation U.S. Ser. No. 938,334, filed Dec. 4, 1986, which in turn was abandoned in favor of U.S. Ser. No. 093,151, filed Sept. 2, 1987, each of which is also assigned to the assignee of the present invention, and is incorporated herein by reference.
When employing ink in a liquid state, the delivery of the ink is, of course, dictated by the liquid state. Typically, the ink is contained within a closed vessel of some sort prior to its delivery to the ink jet. The delivery of ink when employing hot melt ink, however, requires a different approach in order to provide a reliable supply of ink while at the same time minimize operator intervention. The hot melt inks described herein above may be conveniently carried by a cartridge. One hot melt cartridge carrying a single block of hot melt ink is disclosed in U.S. Pat. No. 4,631,557, which is assigned to the assignee of the present invention, and is incorporated herein by reference. In that cartridge, the hot melt ink is melted while in the cartridge so as to supply the ink jet apparatus. Another cartridge, comprising a plurality of blocks which are advanced while in the cartridge to a position where they are released into a hopper or reservoir of the ink jet apparatus in the solid state form, is disclosed in U.S. Pat. No. 4,667,206, which is also assigned to the assignee of the present invention, and is incorporated herein by reference.
Still other versions of a cartridge and method of using the cartridge for phase change or hot melt ink in an ink jet apparatus are disclosed in co-pending U.S. Ser. No. 829,572, to which the present application is a continuation-in-part. As is taught therein, a cartridge for hot melt or phase change ink is tubular, having a cover at one end and an opening at the other end. Upon engagement and cooperation between the cartridge and a reservoir of the ink jet apparatus, solid ink is dropped under the influence of gravity through the opening in the cartridge into the ink jet apparatus. Otherwise, the solid ink is retained in the cartridge until such cooperation is achieved, the cooperation including a keying of the cartridge to the reservoir and forming a seal of an inlet to the reservoir between the cartridge and the reservoir.
One problem that is evident in the design of each of the above described cartridges is their relative complexity. That is, in order to provide a cartridge which is both capable of storing a supply of hot melt or phase change ink and of insuring that the ink jet apparatus within which the cartridge is used operates in an effective manner without undue operator intervention, the cartridges disclosed in the above described patents and co-pending applications are difficult to manufacture, thereby leading to an increased cost of production. It would, therefore, be desirable to provide a simplified cartridge which would be produced at a low cost.
Another problem associated with each of the above described cartridges is that they fail to provide for a reasonable means to prevent tampering with or contamination of the hot melt or phase change ink contained therein. That is, with the exception of the cartridge embodiment that is illustrated by Fig. 1 of the above referenced U.S. Ser. No. 829,572, none of the cartridges described above seal their open ends. A snap-fit cover is shown in FIG. 1 of U.S. Ser. No. 829,572, but such design necessitates the removal of the cover by the operator prior to the loading of the cartridge in the ink jet apparatus. Accordingly, it would also be desirable to provide a cartridge for containing hot melt or phase change ink, protected against contamination, which would further reduce operator intervention during the loading thereof in an ink jet apparatus.