Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Patent
1994-10-24
1997-01-28
Barlow, Jr., John E.
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
347 92, B41J 2175
Patent
active
055981992
DESCRIPTION:
BRIEF SUMMARY
The subject invention concerns a printer designed to apply droplets of hot melt ink onto a substrate in order to generate characters or symbols thereon.
In one prior-art device incorporating a printer for the purposes mentioned, an external reservoir is immersed in a hot water bath or the like and is connected via a comparatively long hose or tube to the printer proper, the latter having a print-head including one or several discharge nozzles.
Hot melt ink in solid form is supplied to the reservoir in which the hot melt ink melts when affected by the hot water bath and from whence the molten hot melt ink is transferred via the hose or the pipe to the printer itself to be applied on the substrate.
In order to prevent the molten hot melt ink from returning to the solid phase while being advanced inside the hose or the pipe or inside the printer, the hose or pipe as well as the printer must be kept heated, which may be effected by means of infra-red radiation or other heating arrangements.
A serious drawback found in this prior-art device is that it is composed of several spaced apart, separate components which in addition must be maintained in a heated condition along the entire and comparatively long path of travel of the molten hot melt ink from the reservoir to the print-head. The heating causes problem also because the heat energy input must be comparatively high in view of the heat losses to the environment.
The purpose of the subject invention is to avoid the disadvantages and the problems inherent in the prior-art device and to provide a printer which is complete in itself while at the same time it is compact and efficient.
The purpose is achieved in a manner which is as simple as it is ingenious in that the printer has a housing in which are provided a reservoir having an inlet for supply of the hot melt ink in solid state and an outlet, a feeder adjacent the reservoir outlet, said feeder having an inlet for reception of the hot melt ink in solid state from the receiver and an outlet, a heater, and a print-head having an inlet which is connected to the feeder outlet and at least one discharge nozzle, said feeder supplying the hot melt ink, preferably by positive displacement, to the print-head while the ink is being melted with the aid of the heater, said print-head receiving said molten hot melt ink from the feeder and discharging it in the shape of droplets from the discharge nozzle for application of said droplets on the substrate.
The invention will be described in closer detail in the following with reference to the accompanying drawing, which in a longitudinal sectional view schematically. illustrates a presently particularly preferred embodiment of the printer, the rear end of which, appearing to the right-hand side of the drawing, being cut away.
The printer designed generally on the drawing figure by reference numeral 1, is designed for application of molten hot melt ink 2 in the form of droplets 3 onto a substrate 4, such as e.g. paper, cardboard or the like which may be used to form packages of various kinds, primarily for foodstuff, in order to generate symbols or characters on said substrate 4. When the droplets 3 hit the substrate 4 they solidify as they are cooled on impact.
When the substrate 4 has an external protective plastic film, which often is the case in connection with foodstuff packages, the droplets are etched to the film as the latter softens or melts when hit by the droplets. The characters or symbols thus produced become forgery-proof in that if one tries to remove them from the substrate, they leave behind an identifiable impression in the subjacent plastic film or even on the packaging material itself.
In accordance with the embodiment illustrated, the printer 1 comprises a housing 5 of an essentially circular cylindrical shape, and a cover 7 positioned at a distance 6 from and around the housing.
The housing 5 has a tubular jacket 8 of a suitable material, such as aluminium, and at its rear (right-hand side in the drawing figure) the tubular jacket 8 is connected to an
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Patent Abtracts of Japan, vol. 8, No. 197, M-324, abstract of JP,A,59-87162 (Hitachi Seisakusho K.K.), 19 May 1984.
Barlow Jr. John E.
Jetline AB
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