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
Reexamination Certificate
active
06257705
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 two plate reverse firing 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 utilisation 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 electro-static 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. 3,863,212 (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 result in the creation of 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
It is an object of the present invention to provide an alternative form of ink jet printing including an ink jet nozzle from which the ejection of ink is activated through the use of a static and movable plate.
In accordance with a first aspect of the present invention there is provided an ink jet nozzle comprising a nozzle chamber having an ink injection port at one wall of the chamber, a fixed electric coil located within the chamber or within a wall of the chamber and a movable plate, in which embedded is an electric coil, located close to the fixed electric coil such that when the amount of current passing through set coils are altered, the movable plunger plate undergoes corresponding movement towards or away from the fixed electric coil and wherein the movement is utilised to inject ink from the nozzle chamber via the ink injection port.
Further, the ink jet nozzle comprises spring means connected to the movable plate wherein the movable plate goes from a quiescent position to a spring loaded position upon activation of the coils and upon deactivation of the coils the spring means causes the movable coil to return to its quiescent position and to thereby eject ink from the ink ejection port. Preferably, the fixed electric coil of the movable plunger plate comprises a stacked multi level spiral of conductive material and the stacked conductive material is interconnected at a central axial point of the spiral. The coils are electrically connected together to form a combined circuit. Further, the spring means comprises torsional springs attached to the movable coil and a conductive stripe contact to the coils is located within the torsional springs. Advantageously, the coil comprises substantially copper and is formed from use of a damascene construction. The nozzle is constructed using a sacrificial etch to release the structure of the moveable coil. Preferably, the nozzle chamber includes a series of slots within the walls of the nozzle chamber so as to allow the supply of ink to the nozzle chamber and an outer surface of the nozzle chamber includes a series of small etched holes for the etching of any sacrificial layer used in the construction of the ink jet print nozzle.
In accordance with a second aspect of the present invention there is provided a means of ejecting ink from a nozzle chamber using the electro-magnetic forces between two coils embedded into place to cause movement of at least one of the plates, the movement further causing the consequential ejection of ink from the nozzle chamber. Further, the utilisation of electro-magnetic forces comprises using the electro-magnetic forces between coils embedded into a movable and a fixed plate so that the movable plate moves closer to the fixed plate, the movable plate further being connected to a spring which upon the movement, stores energy within the spring such as that upon deactivation of a current through the coil, the spring releases its stored energy to thereby cause the movement of the movable plate so as to cause the ejection of ink from the nozzle.
REFERENCES:
patent: 6027205 (2000-02-01), Herbert
Barlow John
Do An H.
Silverbrook Research Pty Ltd
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