Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-07-10
2001-09-04
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S020000, C347S044000, C347S047000
Reexamination Certificate
active
06283581
ABSTRACT:
S
TATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not applicable.
FIELD OF THE INVENTION
The present invention relates to the field of inkjet printing and fluid pumping systems and, in particular, discloses a radial back-curling thermoelastic inkjet printer.
BACKGROUND OF THE INVENTION
Many different types of printing mechanisms have been invented, a large number of which are presently in use. The known forms of printers 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 of 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 forms. The utilization of a continuous stream of 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 a 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 utilized 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 utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes 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) which discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 which 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 disclose ink jet printing techniques which 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 utilizing 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.
In accordance with a first aspect of the present invention, there is provided nozzle arrangement for use with an ink jet printhead, the arrangement comprising: a nozzle chamber for the storage of ink to be ejected; an ink ejection port having a rim formed on one wall of the chamber; and a series of actuators attached to the nozzle rim, and forming a portion of the wall of the nozzle chamber adjacent the rim, the actuators further being actuated in unison to eject ink from the nozzle chamber via the ink ejection port.
The actutators can each include a surface which bends inwards towards the centre of the nozzle chamber upon actuation. The actuators are preferably actuated by means of a thermal actuators device. The thermal actuator device can comprise a conductive resistive heating element encased within a second material having a high coefficient of thermal expansion. The element can be serpentine shaped to allow for substantially unhindered expansion of the second material. The actuators are preferably arranged radially around the nozzle rim.
The actuators can form a membrane between the nozzle chamber and an external atmosphere of the arrangement. The actuators can bend away from the external atmosphere to cause an increase in pressure within the nozzle chamber thereby initiating a consequential ejection of ink from the nozzle chamber. The actuators can bend towards a central axis of the ejection nozzle.
The ink jet nozzle arrangement can be formed on a wafer utilizing micro-electro mechanical techniques and further can comprise an ink supply channel interconnected to the nozzle chamber. The ink supply channel may be etched through the wafer. The ink jet nozzle arrangement can include the ink ejection nozzle supported by a series of struts and the actuators are preferably further interconnected to the nozzle rim and the struts can include a conductive power rail for supplying electrical power to the actuators.
The arrangement can be formed adjacent to neighbouring arrangements so as to form a pagewidth printhead.
REFERENCES:
patent: 4855567 (1989-08-01), Meuller
patent: 5812159 (1998-09-01), Anagnostopoulos et al.
patent: 5896155 (1999-04-01), Lebens et al.
patent: 6007187 (1999-12-01), Kashino et al.
Barlow John
Do An H.
Silverbrook Research Pty Ltd
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