Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-02-20
2004-01-13
Nguyen, Thinh (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S063000, C347S093000
Reexamination Certificate
active
06676241
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet head for forming an image by discharging ink (liquid) for deposition onto a recording medium, and more particularly to an ink jet head provided with a substrate bearing a discharge pressure generating element for generating a pressure for discharging ink, a flow path forming member adhered to the substrate for constituting an ink flow path, and a jointing layer for increasing the adhesion force between the substrate and the flow path forming member.
2. Related Background Art
Among the recording method employed in the printer or the like, the ink jet recording method of discharging ink from a discharge port onto a recording medium for forming a character or an image is recently employed widely as it is a non-impact recording system of low noise level capable of high-speed recording operation at a high density.
In general, the ink jet recording apparatus is provided with an ink jet head, a carriage for supporting such ink jet head, drive means for such carriage, conveying means for conveying a recording medium, and control means for controlling these components. The apparatus executing the recording operation under the movement of the carriage is called serial type. On the other hand, the apparatus executing the recording operation by the conveying operation of the recording medium, without the movement of the ink jet head, is called line type. In the ink jet recording apparatus of line type, the ink jet head is provided with a plurality of nozzles arranged over the entire width of the recording medium.
In the ink jet head, for the ink discharge pressure generating element for generating the pressure for discharging the ink droplet from the discharge port, there are known an electromechanical converting element such as a piezo element, an electrothermal converting element such as a heat generating resistor, or an electromagnetic wave-mechanical converting element or an electromagnetic wave-thermal converting element utilizing electric wave or laser light. Among these, the ink jet head of so-called bubble jet method utilizing a heat generating resistor for the ink discharge pressure generating element and inducing film boiling in the ink for generating a bubble thereby discharging ink, is effective for high-definition recording because the pressure generating elements can be arranged at a high density. Such ink jet head is generally provided with plural discharge ports, plural discharge pressure generating elements, and flow paths for guiding the ink, supplied from an ink supply system, through the discharge pressure generating elements to the discharge ports.
For forming an ink jet head by adjoining a flow path forming member for forming an ink flow path to a substrate bearing the discharge pressure generating element, there have conventionally been proposed various methods. For example, the Japanese Patent Application Laid-open No. 61-154947 discloses a method of forming a flow path pattern with soluble resin on a substrate bearing a discharge pressure generating element, then forming thereon and hardening a resin layer such as of epoxy resin so as to cover the flow path pattern, and, after the cutting of the substrate, dissolving out the soluble resin. Also the Japanese Patent Application Laid-open No. 3-184868 discloses that it is effective to employ a cationic polymerized and hardened substance of an aromatic epoxy compound as the covering resin for the flow path pattern.
In these producing methods, the adjoining of the substrate bearing the discharge pressure generating element and the flow path forming member is by the adhesion force of the resin constituting the flow path forming member.
In the ink jet head, the flow path is constantly filled with the ink in the normal state of use, so that the periphery of the adjoining portion between the substrate bearing the ink discharge pressure generating element and the flow path forming member is in contact with the ink. Therefore, if the adjoining is achieved by the adhesion force only of the resinous material constituting the flow path forming member, the adhesion of the adjoining portion may be deteriorated in time by the influence of the ink.
Also in the ink jet recording apparatus, it is recently required to execute recording on recording media of various materials and to provide the recorded image with water resistance, and weakly alkaline ink may be employed for meeting such requirements. Particularly in case of such weakly alkaline ink, it may become difficult to maintain the adhesion force between the substrate bearing the ink discharge pressure generating element and the flow path forming member over a prolonged period.
Also in so-called bubble jet head, in order to suppress damage in the heat generating resistor etc. by electroerosion caused by the ink or by cavitation at the extinction of the bubble, it is common to form an inorganic insulation layer composed for example of SiN or SiO
2
and an anticavitation layer composed for example of Ta particularly on the heat generating resistor. Such Ta layer has a lower adhesion force than the SiN layer to the resinous material constituting the flow path forming member. For this reason, the flow path forming member may be peeled off from the Ta layer under severe conditions.
Such peeling of the flow path forming member from the substrate changes the shape of the flow path, thereby changing the ink discharge characteristics and detrimentally affecting the image formation. In order to prevent such phenomenon, according to the Japanese Patent Application Laid-open No. 11-348290 discloses it is effective to form an adhesion layer composed of polyetheramide resin between the substrate and the flow path forming member. According to the above-mentioned patent application, excellent adhesion can be maintained over a long period both in case of using the alkaline ink or in case of adjoining the flow path forming member on a Ta layer.
A conventional ink jet head having such adhesion layer is shown in
FIGS. 20A and 20B
which are respectively a horizontal cross-sectional view partly showing the vicinity of the flow path of such ink jet head and a cross-sectional view along a line
20
B—
20
B in FIG.
20
A.
Such ink jet head is provided, on a substrate
51
, with a flow path wall
61
and a ceiling portion (not shown) formed thereon and having a discharge port
59
, by the aforementioned flow path forming member
58
of a resinous material. The discharge ports
59
are opened in opposed relationship to plural ink discharge pressure generating elements (not shown) provided on the substrate
51
. The flow path wall
61
is formed in plural units in comb-tooth shape, and, between the adjacent flow path walls, there is formed a flow path for guiding the ink from the lower side of
FIG. 20A
onto each ink discharge pressure generating element. At the entrance of each flow path, there are formed vertically extending two pillars
62
with a predetermined gap therebetween, for example in order to prevent dust intrusion into the flow path.
The flow path forming member
58
is adjoined to the substrate
51
across an adhesion layer
56
. Stated differently, the adhesion layer
56
is formed between the flow path forming member
58
and the substrate
51
. In such configuration, if the adhesion layer
56
is formed over a planar area wider than the flow path forming member
58
, there is formed, in the flow path, a step difference at the boundary between an area bearing the adhesion layer
56
and an area lacking the adhesion layer
56
. Such step difference may complicate the flowability of the ink in the flow path and render it unstable, thereby hindering the desired stable ink flow. Also if the adhesion layer
56
is provided on the ink discharge pressure generating element, loss in the transmission of the discharge energy to the ink becomes large since the discharge energy from the ink discharge pressure generating element has to be transmitted to the ink through the adhesion layer
56
. Also the
Nguyen Thinh
Stephens Juanita
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