Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-01-11
2004-05-11
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S061000
Reexamination Certificate
active
06733111
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an inkjet head for performing recording operation by jetting ink droplets onto a recording medium.
Nowadays, inkjet printers for performing recording operation by ejecting ink droplets have come into widespread use. In such circumstances, it is desired to provide an inkjet head having ink ejection nozzles disposed thereon at a high density in a large scale and capable of ejecting ink droplets of a small size so as to output an image and the like with high precision like a photograph by ejecting the ink droplets at a high density.
This inkjet printer employs a piezoelectric system, a heating system, and so on as an ink droplet ejecting system. In the piezoelectric system, an ink droplet is ejected by a piezoelectric device such as a piezoelectric element, a piezoelectric ceramic, and the like the volume of which is varied by a predetermined voltage applied thereto. In the heating system, an ink droplet is ejected using a bubble of ink which is produced by partially boiling ink by a heat generation element which generates heat when a voltage is applied thereto.
In the heating system, there have been proposed various types of inkjet heads which can eject ink droplets from ink ejection nozzles arranged at a high density in a large scale, as disclosed in, for example, JP 6-297714 A.
According to the publication, an inkjet printer is arranged such that heat generation resistors, each of which a heat generation element has and which do not need a protective layer, individual ink paths for ejecting ink droplets from ink ejection nozzles, and ink supply paths for supplying inks to the individual ink paths are formed on a silicon substrate using a semiconductor processing technology as well as an LSI drive circuit is disposed on the same silicon substrate. With this arrangement, it is possible to eject ink through the ink ejection nozzles arranged at the high density in the large-scale.
In particular, when the ink is ejected through the ink ejection nozzles arranged at a high density in a large-scale, it is desired to form the shape of ink ejection nozzles with a high accuracy so that ink droplets can be ejected in desired directions accurately.
However, when the inkjet head is driven for a long time, it is heated by the heat generated by the heat generation resistors. As a result, there is a possibility that ink droplets are ejected unstably and that the directions in which they jet are made also unstable.
When ink droplets are ejected from ink ejection nozzles by, for example, the expansion of bubbles in ink which have been boiled by the heat generated by the heat generation resistors, a plate including the ink ejection nozzles is bent or warped by being excessively heated. As a result, the shape of the ink ejection nozzles is deformed, which makes it impossible for ink droplets to jet in desired directions and makes it impossible for ink droplets to jet at the worst because the plate through which the ink ejection nozzles are formed is exfoliated.
In the inkjet head, a partition layer, by which individual ink paths and ink supply paths are formed, is disposed on a silicon substrate, and the plate, through which the ink ejection nozzles are formed in correspondence to the ink individual paths, is disposed on the partition layer. In this arrangement, the partition layer is bonded to the plate at a high solidifying temperature to improve a production efficiency by shortening a solidifying time. Accordingly, there is a possibility that the plate is bent or warped as well as the shape of the ink ejection nozzles is deformed by the high solidifying temperature, which makes it difficult to obtain an inkjet head having ink ejection nozzles formed in a desired shape, and thereby the yield of the inkjet head is reduced.
These problems arise not only in the heating system using the heat generation element but also in the piezoelectric system using the piezoelectric device such as the piezoelectric element, and the like.
In contrast, JP 9-57964 A proposes to form a nozzle plate, which is joined to an actuator member composed of PZT, of aramid resin having a linear expansion coefficient similar to that of lead zirconate titanate (PZT) in an inkjet head employing a piezoelectric system. However, since the actuator member is joined to the nozzle plate using a heat curing type adhesive in the publication, bending and warping are caused to the nozzle plate, through which nozzles are arranged at a high density, in such a degree as to deform the shape of the nozzles by the difference between the linear expansion coefficients of the actuator member and the nozzle plate. Moreover, the heating type curing adhesive, which has fluidity and is interposed between the nozzle plate and the actuator member, flows into grooves, which are formed in the actuator member composed of PZT at a high accuracy, before the adhesive cures. Thus, the adhesive disperses the volumes of the grooves which affect the ejection of ink droplets. Accordingly, a problem also arises in that the ejection speeds and the sizes of ink droplets ejected from the nozzles are dispersed among the nozzles.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention, which was made to solve the above problems, is to provide an inkjet head suitable for mass-production which has highly integrated ink ejection nozzles disposed at a high density, can eject ink droplets stably even if the inkjet head is driven for a long time, and further does not reduce a yield in production.
The present invention provides an inkjet head, comprising: an ink ejection unit disposed on a silicon substrate and a plate including an ink ejection nozzle disposed in correspondence to the ink ejection unit so that an ink droplet is ejected from the ink ejection nozzle using the ink ejection unit, wherein the plate is formed of a film composed of aramid.
Then, the plate including the ink ejection nozzle is preferably disposed along a surface of the silicon substrate.
The ink ejection unit preferably comprises a heat generation element for boiling ink and ejecting an ink droplet from the ink ejection nozzle.
The plate preferably has a thickness of 15 &mgr;m or less.
The present invention also provides an inkjet head, comprising: an ink ejection unit disposed on a silicon substrate; and a plate including an ink ejection nozzle disposed in correspondence to the ink ejection unit so that an ink droplet is ejected from the ink ejection nozzle using the ink ejection unit, wherein the plate is formed of a film having a linear expansion coefficient of 50% or more to 200% or less of a linear expansion coefficient of the silicon substrate.
Then, the plate including the ink ejection nozzle is preferably disposed along a surface of the silicon substrate.
The ink ejection unit preferably comprises a heat generation element for boiling ink and ejecting an ink droplet from the ink ejection nozzle.
The plate preferably has a thickness of 15 &mgr;m or less.
The present invention still also provides an inkjet head, comprising: an ink ejection unit disposed on a substrate; and a transparent plate including an ink ejection nozzle disposed in correspondence to the ink ejection unit so that an ink droplet is ejected from the ink ejection nozzle using the ink ejection unit, wherein the plate is bonded to an upper layer formed on the substrate using an ultraviolet curing adhesive.
Then, the upper layer is preferably a partition layer, which forms an ink path linking with the ink ejection nozzle.
The ink ejection unit preferably comprises a heat generation element for boiling ink and ejecting an ink droplet from the ink ejection nozzle.
The plate preferably has a thickness of 50 &mgr;m or less.
REFERENCES:
patent: 5870121 (1999-02-01), Chan
patent: 6113221 (2000-09-01), Weber
patent: 6309055 (2001-10-01), Sakai et al.
patent: 06-297714 (1994-10-01), None
patent: 09-57964 (1997-03-01), None
Detailed English Translation of provided document JP 09-57964.*
English Abstract of 06-297714.
English Abstract of 09/57964.
Fuji Photo Film Co. , Ltd.
Meier Stephen D.
Whitham Curtis & Christofferson, P.C.
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