Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-07-10
2001-05-22
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S020000, C347S044000, C347S047000, C347S084000
Reexamination Certificate
active
06234611
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 curling calyx thermoelastic 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 utilised ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilises 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 utilising 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 printer and in particular an alternative form of nozzle construction for the ejection of ink from a nozzle port.
In accordance with a first aspect of the present invention there is provided an ink jet nozzle comprising a nozzle chamber having an ink ejection port in one wall of the chamber and a thermal actuator unit activated to eject ink from the nozzle chamber via the ink ejection port, the thermal actuator unit comprises a plurality of the thermal actuator petal devices arranged around a central stem so that upon activation of the thermal actuator petal devices, the devices bend in unison, thereby initiating the ejection of ink from the nozzle chamber. Preferably the thermal actuator unit is located opposite the ink ejection port and the petal devices bent generally in the direction of the ink ejection port. The thermal actuator petal devices can comprise a first material having a high coefficient of thermal expansion surrounding a second material which conducts resistively so as to provide for heating of the first material. Further the second material can be constructed so as to form a concertina upon expansion of the first material. Advantageously an air bubble forms under the thermal actuator during operation. The first material of the thermal actuator petal can comprise substantially polytetrafluoroethylene, and the second material can comprise substantially copper. Upon activation of the thermal actuator unit, the space between adjacent petal devices is reduced. Advantageously the actuator petal devices are attached to a substrate and the heating of the petal devices is primarily near the attached end of the device. Further, the outer surface of the ink chamber can include a plurality of etchant holes provided so as to allow a more rapid etching of sacrificial layers during construction.
REFERENCES:
patent: 5812159 (1998-09-01), Anagnostopoulos et al.
Barlow John
Do An H.
Silverbrook Research Pty Ltd
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