INK-JET PRINTING METHOD AND AN INK-JET PRINTING HEAD

Abstract: A method of ink-jet printing is implemented by focusing a laser light beam on an ink disposed in capillaries of a head and producing shock pulses therein resulting in ejection of drops of said ink onto an information carrier. An ink-jet printing head has a light beam laser having devices for focusing and deflecting the light beam across the nozzles bases for carrying out ejection of ink drops therefrom according to a predetermined program.

Description: The invention concerns a method for ink-jet printing according to the preamble of claim 1 and an ink-jet printing head according to the preamble of claim 2. Known is an ink-jet printing method that comprises steps of positioning of an information carrier opposite to jet nozzles filled with a liquid expendable printing material, and excitation of pressure pulses in these nozzles for a dispensed supply of the printing material onto the information carrier (US-A-4 410 899) . In the known method a pressure pulse in nozzles is produced owing to a pulse heating of a liquid printing material resulting in producing a vapour in the heating area, rapid expansion of a liquid and ejection of its drop from a nozzle. A drawback of this method consists in that a source that provides a thermal action effected on an ink is positioned immediately in each nozzle and controlled externally, which makes realisation of this method difficult when there is great a number of nozzles. For implementation of the known ink-jet printing method, various ink-jet printing heads are used, e.g. such that are described in US-A-4 580 148 . This patent describes an ink-jet printing head comprising as many resistors for ink heating as there are nozzles therein. Each resistor has a current supply arrangement connecting it to a power supply. For ejection of a drop from a nozzle, the supply circuit of corresponding resistor is closed. When a current pulse flows through a resistor, the latter is heated and heats the ink located in the area where such resistor is disposed to the vaporous state, whereby the liquid, while expanding, creates a shock pulse which ejects a drop thereof through a nozzle. Thereafter, when the liquid is cooled off, the process may be repeated. A drawback of such heads is their structural complexity, for such head must have as many resistors as there are nozzles positioned at a little spacing and provided with a current supply system; a low reliability, as the mode of resistor multiple pulse heating to a sufficiently high temperature determines their limited service life. From JP-A-02-147 346 a method and an apparatus for inkjet printing is known wherein an information carrier is positioned opposite to jet nozzles filled with a liquid printing material and a laser beam is focussed on this material. The laser beam is focussed by an objective lense to an absorbing layer. The absorbing layer is separated from the printing material in a liquid chamber by a protection layer. The objective tense is moved by an actuator drive circuit whereby the focal position in the absorbing layer is varied. The basic purpose of the invention consists in providing such method and a head for ink-jet printing that will exclude positioning of a source of shock pulses for ink drops ejection from head nozzles immediately in a head, simplify the head structure and improve reliability and durability of its operation. Thus, the invention concerns a method for ink-jet printing as defined in claim 1. In such method a source of a shock action effected on an ink is located outside the nozzles or cavities with an ink adjacent to them, which allows to improve quality of printing owing to diminishing of the nozzles diameter and a spacing therebetween, and simplifies possibility of realisation of said source when there is a great number of nozzles. Additionally, the invention concerns an ink-jet printing head as defined in claim 2. Such arrangement of an ink-jet printing head simplifies its design, because in the head nozzles there are no elements producing the action of a shock action effected on a liquid, and a head itself has no system for supplying current to said elements; reliability of its operation is enhanced owing to simplification of the design and exclusion therefrom of any parts operating in the sharp temperature drop mode. The nozzle bases are preferably open and nozzles, over the bases level upward, communicate with channels for procuring an expendable printing material for them. The nozzle bases are also preferably covered with a material which is transparent to a wavelength emitted by a laser. Such arrangement of a head permits that a laser light beam will act efficiently on an ink disposed in a nozzle and produce shock pulses therein to eject drops thereof onto an information carrier. Hereinafter the invention will be explained by its particular but not limiting embodiments, and accompanied drawings wherein: Fig. 1 illustrates the proposed method of the ink-jet printing, Fig. 2 - general view of the proposed ink-jet printing head for embodying an ink-jet printing method with open nozzle bases, Fig. 3 - ditto, as Fig. 2 , with closed nozzle bases, Fig. 4 - section along II-II line of Fig. 2 . The proposed method of an ink-jet printing is implemented as follows: An information carrier C (Fig. 1 ) is positioned opposite to nozzles B filled with a liquid expendable printing material. Thereafter a light beam emitted from laser E is focused on the liquid printing material. In accordance with the discovery named as "Lighthydraulic Effect" (diploma N°65, A.M. PROKHORON G.A. ASKAR'YAN, G.P. SHIPULO, BULLETIN of INVENTIONS. No. 19, 1969), when a laser light beam is absorbed within a liquid, a shock pulse is produced. With this effect a shock pulse is created within nozzle B itself which is filled with a liquid printing material, whereby a drop of the liquid is ejected from the nozzle and hits an information carrier. From the above-cited description of the proposed method it is obvious that a source that effects a shock action on an ink is located outside the nozzles or cavities with the ink adjacent to them, which allows to improve quality of printing owing to the provided possibility to diminish the drops diameter and increase density of their positioning on an information carrier. For realisation of the proposed ink-jet printing method it is necessary that a laser light beam sweep will be provided across the bases of nozzles filled with an ink. This is done by an ink-jet printing head shown in Fig. 2 . The proposed ink-jet printing head comprises a number of nozzles 1 in the form of capillary openings filled with a liquid expendable printing material supplied into the nozzles 1 from channel 2 . Information carrier 3 is positioned perpendicularly to the axes of the nozzles 1 . Opposite ends of the nozzles 1 , their bases, face laser 4 of light beam 5 having devices for focusing 6 of the beam and deflection 7 thereof across bases of nozzles 1 . Nozzles 1 bases are arranged to be either open, or covered by material 8 that is transparent to a wavelength emitted by laser 4 . The proposed ink-jet printing head operates as follows: Beam 5 of laser 4 according to a predetermined program is focused using device 6 and directed using device 7 for its deflection onto a liquid disposed in a given nozzle 1 . As light beam 5 is absorbed within the liquid, the lighthydraulic effect is produced whereby in the liquid disposed in a capillary a shock pulse is produced, due to action of which pulse a drop of the ink is ejected from nozzle 1 and hits information carrier 3 . Then the action effected by beam 5 on the given nozzle 1 is terminated such that the ink for compensation of the ejected drop is supplied to the nozzle from channel 2 . By deflecting beam 5 of laser 4 across bases of nozzles 1 according to a predetermined program, a set of dots representing a text or an image on information carrier 3 can be obtained.

Claims: A method for ink-jet printing wherein an information carrier (3) is positioned opposite to jet nozzles (1) filled with a liquid expendable printing material and a laser beam (5) is focussed on this material, characterized in that the laser beam (5) produces a lighthydraulic effect in the liquid material and causes shock pulses to eject drops of liquid on the information carrier (3). An ink-jet printing head comprising a number of nozzles (1) in the form of capillary openings filled with a liquid expendable printing material and means for acting on the material including a quantum generator (4) of a laser beam (5) having a device (6) for focusing this laser beam (5) to a size smaller than the capillary diameter and a device (7) for deflecting the laser beam (5) across the nozzle bases from the side opposite to an information carrier (3), characterized in that the quantum generator (4) of the laser beam (5) is configured to produce a lighthydraulic effect in the liquid material in the nozzles (1) causing shock pulses in the liquid material and ejection of drops to the information carrier (3). The ink-jet printing head of claim 2, characterized in that the nozzles (1) are in communication with channels (2) for sypplying the printing material to them. The ink-jet printing head of claim 2 or 3, characterized in that the nozzles (1) are open at opposite ends, one of which being directed to the information carrier (3). The ink-jet printing head of claim 2 or 3, characterized in that the nozzles (1) are open at one end directed to the information carrier (3) and covered by a material (8) transparent to a wavelength emitted by the quantum generator (4) at the other end.

Inventors: MAXIMOVSKY SERGEI NICOLAEVICH, RADUTSKY GRIGORY AVRAMOVICH, MAXIMOVSKY, SERGEI NICOLAEVICH, RADUTSKY, GRIGORY AVRAMOVICH
Applicants: MAXIMOVSKY SERGEI NICOLAEVICH, RADUTSKY GRIGORY A, MAXIMOVSKY, SERGEI NICOLAEVICH, RADUTSKY, GRIGORY AVRAMOVICH
Application year: 1995
Main classification: B41J2
IPC codes: B41J2, B41J5, G01D15