Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-11-03
2001-08-07
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S065000, C347S093000
Reexamination Certificate
active
06270198
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for MICRO INJECTING DEVICE earlier filed in the Russian Patent Office on the Nov. 3, 1998 and there duly assigned Ser. No. 98119889.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of micro-injecting devices and ink jet print heads, particularly to membrane-type micro-injecting devices, and more particularly to the channel arrays for supplying working fluid in the devices.
2. Description of the Prior Art
Micro-injecting devices are able to discharge liquids of a variety of colors by using cartridges. Among the advantages of these devices is low noise. Also, there is an advantage when used in an ink-jet printer that letters printed on paper are fine and clear. As a result, the use of the ink-jet printers has been increasing.
A printer head is mounted in the ink-jet printer. The printer head sprays ink outward after transforming and expanding the ink in a bubble according to electric signals from outside of the printer, thereby carrying out the operation of printing letters on a paper.
Examples of the construction and operation of several ink jet print heads of the conventional art are seen in the following U.S. Patents. U.S. Pat. No. 4,490,728, to Vaught et al., entitled Thermal Ink Jet Printer, describes a basic print head. U.S. Pat. No. 4,809,428, to Aden et al., entitled Thin Film Device For An Ink Jet Printhead and Process For Manufacturing Same and U.S. Pat. No. 5,140,345, to Komuro, entitled Method Of Manufacturing a Substrate For A Liquid Jet Recording Head And Substrate Manufactured By The Method, describe manufacturing methods for ink-jet printheads. U.S. Pat. No. 5,274,400, to Johnson et al., entitled Ink Path Geometry For High Temperature Operation Of Ink-Jet Printheads, describes altering the dimensions of the ink-jet feed channel to provide fluidic drag. U.S. Pat. No. 5,420,627, to Keefe et al, entitled Ink Jet Printhead, shows a particular printhead design.
Generally, these micro injecting devices use high temperature of heat generated by a heating layer within the device to spray the ink on the paper. Accordingly, the high temperature which is generated by the heating layer has an effect on ink contained in an ink chamber for a long time. As a result, the ink is thermally transformed and this causes the durability of the apparatus containing the ink to decrease rapidly.
Recently, to overcome this problem, there has been proposed a new method for smoothly spraying ink from the ink chamber toward the outside by disposing a plate membrane between the heating layer and the ink chamber and inducing a dynamic deformation of the membrane under a pressure of a working fluid, for example, heptane. Since the membrane is disposed between the ink chamber and the heating layer, preventing the ink from contacting directly to the heating layer, the ink itself is subjected to little thermal transformation. An example of this type of printhead is seen in U.S. Pat. No. 4,480,259, to Kruger et al., entitled Ink Jet Printer With Bubble Driven Flexible Membrane.
In ink-jet printer heads of the conventional art using this method, the working fluid, which is supplied into an inlet of the printer head, flows along the main channel for supplying the working fluid, which is defined by means of barrier layers of the heating chamber. Then, the working fluid branches out from the main channel for supplying the working fluid and flows along a feeder channel for supplying the working fluid. At the end of the channel, the working fluid fills up the heating chamber.
The main channel and feeder channel for supplying the working fluid are formed by etching the barrier layer while the heating chamber is formed from the barrier layer. However, when the barrier layer is not etched sufficiently, such that the channel for supplying the working fluid is blocked by the barrier layer of the heating chamber, the working fluid which is introduced into the inlet of the print head cannot flow toward the heating chamber. As a result, the heating chamber is not filled with the working fluid.
Furthermore, when a foreign substance, such as dust or other particle, is introduced into the channel for supplying the working fluid during the process of the etching, thus obstructing a pathway of the working fluid, the working fluid cannot flow toward the heating chamber, as described above. As a result, the heating chamber is not filled with the working fluid.
When the heating chamber is not sufficiently supplied with working fluid because the barrier layer obstructs the pathway of the working fluid, the membrane which is operated by relying on the pressure of the working fluid cannot carry out its function. Accordingly, the printer head does not operate properly.
As described above, the working fluid which is supplied through the inlet of the printer head fills the heating chamber through each channel for supplying the working fluid. As the pressure in the heating chamber is increased by heating from the heating layer, the working fluid introduced into the heating chamber backs up under the pressure and flows along the feeder channel in reverse direction, this backwash resulting in the working fluid being introduced into the adjacent heating chambers. In the case described above, the working fluid is oversupplied for the adjacent heating chambers, while the heating chamber from which the working fluid backwash occurs is subjected to a lack of the working fluid. Therefore, the heating chamber in which the working fluid is oversupplied has a working fluid pressure higher than the desired pressure, while the heating chamber with a lack of the working fluid due to the backwash has a working fluid pressure lower than the desired pressure.
Accordingly, the membranes, which are activated by relying on the pressure of the working fluid, cannot be operated uniformly in their respective heating chambers. The net effect of this phenomenon is that the amount of the ink which is finally sprayed from a respective nozzle is not regular, thereby markedly degrading the quality of printing.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved micro-injecting device or ink-jet print head.
It is a further object of the invention to provide an ink-jet print head which has improved reliability.
It is a yet further object of the invention to provide an ink-jet print head with improved quality of printing.
It is a still further object of the present invention to provide an ink-jet print head with improved uniformity of ink spraying.
It is a still yet further object to provide a membrane-type ink-jet print head which is less susceptible to manufacturing defects in the working fluid supply channels or to particles in the working fluid.
It is another object to provide a membrane-type ink-jet print head in which the working fluid is provided to the heating chambers even if a pathway for the working fluid is obstructed.
It is yet another object to provide a membrane-type ink-jet print head in which the pressure loss due to backwash of the working fluid out of the heating chamber is reduced.
It is still another object to provide a membrane-type ink-jet print head in which backwash of the working fluid from one heating chamber into another is reduced.
The present invention has been made to overcome the above-described problems of the prior art. To accomplish the objects of the present invention, there is provided a printer head having two main channels for supplying working fluid which are communicated with an inlet thereof for introducing the working fluid therein, wherein one of main channels for supplying the working fluid is branched in order to dispose a plurality of feeder channels for supplying the working fluid which are connected to heating chambers.
The main channels for supplying the working fluid communicate with each other through a plurality of connecting channels. Even if one of the t
Ahn Byung-Sun
Chetrovich Lavrishev Vadim
Nikolaevich Dunaev Boris
Barlow John
Bushnell , Esq. Robert E.
Samsung Electronics Co,. Ltd.
Stephens Juanita
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