Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-07-10
2001-07-10
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S020000, C347S044000, C347S047000, C347S085000
Reexamination Certificate
active
06257704
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
The present invention relates to ink jet printing and in particular discloses a planar swing grill electromagnetic ink jet printer.
The present invention further relates to the field of drop on demand ink jet printing.
BACKGROUND OF THE INVENTION
Many different types of printing have been invented, a large number of which are presently in use. The known forms of print have a variety of methods for marking the print media with a relevant marking media. Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc.
In recent years, the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nozzles has become increasingly popular primarily due to its inexpensive and versatile nature.
Many different techniques on ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, “Non-Impact Printing: Introduction and Historical Perspective”, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).
Ink Jet printers themselves come in many different types. The use of a continuous stream ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electrostatic ink jet printing.
U.S. Pat. No. 3,596,275 by Sweet also discloses a process of a continuous ink jet printing including the step wherein the ink jet stream is modulated by a high frequency electro-static field so as to cause drop separation. This technique is still used by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al)
Piezoelectric ink jet printers are also one form of commonly used ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which uses a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 discloses a piezoelectric push mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element.
Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclosed ink jet printing techniques rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices using the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.
As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction operation, durability and consumables.
SUMMARY OF THE INVENTION
The present invention provides an alternative form of ink jet printer which using a magnetic coil as part of its actuation process.
In accordance with the first aspect of the present invention there is provided an ink jet nozzle comprising an ink reservoir containing an ink supply under an oscillating pressure, a nozzle chamber having an ink ejection port for the ejection of ink drops onto a print media, and a shutter means interconnecting the reservoir and the nozzle chamber, which is operable by means of electromagnetic actuation so as to control the ejection of ink from the ejection port.
Further the electromagnetic actuation comprises activating an electromagnet so as to move an arm interconnected to at least one end of the shutter means, thereby opening a channel for the flow of ink, followed by maintaining a lower keeper current so as to maintain the channel in an open state, followed by deactivation of the electromagnet, and the subsequent returning of the shutter to a closed position. Preferably the electromagnet includes a first and second end, wherein each of the ends are positioned closely adjacent to the arm and the electromagnetic actuation include movement of the arm closer to both of the ends. Further, the arm is pivoted between the first and second end of the electromagnet, wherein the electromagnet has a spiral shape.
Advantageously, the ink jet print nozzle comprises a resilient means connected to the shutter means which is elastically deformed by the electromagnetic actuation and operates to return to an initial state upon deactivation of the shutter means so as to restrict the further flow of fluid from the ink reservoir to the nozzle chamber.
Preferably the resilient means comprises a coiled spring. The ink jet print nozzle is formed utilising semi-conductor fabrication techniques from a copper coil surrounding a soft metal core. The copper coil is formed using a damascene process. Preferably the shutter means comprises a series of moveable slats, moveable over an aperture in the wall of the nozzle chamber.
In accordance with a second aspect of the present invention, there is provided a method of ejecting ink from an ink jet print nozzle comprising using an electromagnetically activated shutter to control the flow of ink into a nozzle chamber such that ink is ejected from the nozzle chamber when the shutter is open using a first high pressure cycle of a pressurized ink supply for the ejection of the ink, a low pressure cycle for the separation of the ejected drop from the ink in the nozzle chamber and a second high pressure cycle of the pressurized ink supply for refilling the nozzle chamber with ink.
REFERENCES:
patent: 5612723 (1997-03-01), Shimura et al.
patent: 403153359 (1991-07-01), None
Barlow John
Do An H.
Silverbrook Research Pty Ltd
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