Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-07-10
2001-02-13
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S044000, C347S020000
Reexamination Certificate
active
06188415
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
The present invention relates to the field ink jet printers and in particular, discloses an ink jet printer having a thermal actuator comprising an external coil spring of a unique construction.
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 utilization 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 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) 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 sheer 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 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.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide for an inkjet printing device having a unique form of actuator suitably used for use in the ejection of ink.
In accordance with a first aspect of the present invention, there is provided a thermal actuator activated by means of conductive heating of an electrically conductive material, the actuator comprising: a first non-conductive strip of material attached to a substrate at a first end of the strip and adapted to apply a force to a load at a second end of the strip; a second conductive strip of material formed along one side of the first strip, the second conductive strip including a first wire strip running from substantially the first end to the second end and a second wire strip running from substantially the second end to the first end, the wire strips being joined together at the second end so as to form a circuit, the wire strips being further connected to a controlled power supply at the first end such that activation of the controlled power supply causes heating of the conductive material so as to actuate the thermal actuator thereby applying a force to the load.
Preferably, the first strip is in the form of a coil and the second conductive material is formed along a radially inner surface of the strip. The first wire and the second wire can be electrically insulated from one another by a layer of the first non-conductive material. Preferably, the second conductive material comprises a material having a high Young's modulus and the first non-conductive strip is substantially thicker than the second conductive material. The substrate can comprise an electronic circuitry layer of a silicon wafer, the second conductive material can comprise substantially titanium diboride and the first non-conductive material can comprise substantially glass.
The actuator can be interconnected through a slot in a nozzle chamber to a paddle type device, the nozzle chamber being filled with ink and the actuator being activated to eject ink from a port defined in one wall of the nozzle chamber.
In accordance with a second aspect of the present invention, there is provided an ink jet printer having a series of ink ejection nozzle chambers each containing: an ink ejection port defined in one wall of the chamber for the ejection of ink therefrom; a paddle within the chamber, actuated by an actuator for the ejection of ink from the nozzle chamber via the ink ejection port; a slot defined in a second wall thereof for the communication with the paddle of an actuator device; a thermal actuator activated by means of conductive heating of an electrically conductive material, the actuator comprising a first non-conductive strip of material attached to a substrate at a first end of the strip and adapted to apply a force to a load at a second end of the strip; a second conductive strip of material formed along one side of the first strip, the second conductive strip including a first wire strip running from substantially the first end to the second end and a second wire strip running from substantially the second end to the first end, the wire strips being joined together at the second end so as to form a circuit, the wire strips being further connected to a controlled power supply at the first end such that activation of the controlled power supply causes heating of the conductive material so as to actuate the thermal actuator thereby applying a force to the load.
The nozzle chambers can be formed on a silicon wafer and include a series of ink supply channels etched through the wafer for the supply of ink to the nozzle chamber.
REFERENCES:
patent: 404001051 (1992-01-01), None
Barlow John
Do An H.
Silverbrook Research Pty Ltd
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