Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-01-22
2001-10-30
Yockey, David F. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06309057
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink-jet type recording head for generating pressure in pressure generating chambers substantially instantaneously by expansion/-contraction of piezoelectric vibrators or by heat elements to thereby jet ink droplets from nozzle openings in response to the change in pressure.
In an ink-jet type recording head in which dots on a recording medium are formed from ink droplets, printing with very high resolution can be made by reducing the ink droplet size, but it is necessary to increase the number of nozzle openings for the purpose of performing printing efficiently. Particularly in the case of an ink-jet recording head using piezoelectric vibrators as ink droplet jetting sources, it is necessary to increase the size of pressure generating chambers as to use the energy of the piezoelectric vibrators efficiently. However, this is contrary to the requirement of reducing the size of the recording head.
To resolve the aforementioned problems, there is generally used a method of setting walls which partition adjacent pressure chambers in such a manner as to be as thin as possible and of making the shape of the pressure generating chambers larger in the direction of the length thereof to thereby increase the volume thereof.
Such pressure generating chambers or reservoirs are formed by making through-holes in a spacer, i.e., a member for keeping the distance between a plate member and a nozzle plate at a predetermined value. So as to form through-holes coincident with pressure generating chambers having the required very small and complex shape, an etching technique is used generally.
A laminate of photosensitive resin films is used generally as a material constituting the aforementioned spacer. When such a photosensitive resin film laminate is used, there arises an advantage in that a desired pattern can be formed extremely accurately due to the fact that such materials are well suitable for photolithography, and due to the fact that the adhesive property thereof can be used so that no adhesive agent is required for fixing the laminate to the plate member and the nozzle plate. On the other hand, there is a disadvantage in that crosstalk, distortion, etc., can occur because of the low mechanical strength of the material, so that the quality in printing is lowered when this material is applied to a recording head with high resolution.
Moreover, since a plurality of resin films are laminated, there is a risk of separation, so that the thickness of the spacer is limited by the characteristics of the material. There also arises a problem in that it is difficult to make the volume of each of the pressure generating chambers suitable for an ink-jet type recording head.
To solve the aforementioned problems, a proposal has been made in which a silicon single crystal substrate of crystal orientation (
110
) is used, and pressure generating chambers in the form of through-holes and ink supply ports and nozzle openings in the form of grooves of a depth providing a fluid resistance required for these openings are formed by anisotropic etching of a silicon single crystal substrate (see U.S. Pat. No. 4,312,008).
There, however, arises a problem in that not only is controlling of the manufacturing, process complicated because it is necessary to precisely control the etching depth, but it is difficult to control the volume in positions necessary for securing fluid resistance to a precise degree, for instance in the ink supply ports, because the etched sectional shape is inherently a V-shape or a trapezoidal shape.
SUMMARY OF THE INVENTION
The present invention is based on such circumstances, and an object thereof is to provide a novel ink-jet type recording head in which pressure generating chambers, ink supply ports and reservoirs can be formed with a high accuracy by etching of a crystalline substrate.
To solve the aforementioned problems, according to the present invention, there is provided an ink-jet type recording head comprising: a nozzle plate provided with nozzle openings for jetting ink droplets; a spacer provided with partitions for partitioning pressure generating chambers, ink supply ports and reservoirs; a plate member fixed to the other surface of the spacer so as to be opposite to the nozzle plate, the nozzle plate, the spacer and the plate member being sandwiched and fixed to each other; and pressure generating means for exerting a change of pressure suitable for forming ink droplets on the pressure generating chambers; characterized in that the spacer is formed by etching a silicon crystalline substrate or a silicon oxide crystalline substrate from its opposite surfaces so that the pressure generating chambers, the ink supply ports and the reservoirs are formed in the form of through-holes communicated with each other; and the spacer is formed in the form of a cantilever so that the partitions for partitioning the pressure generating chambers and the ink supply ports are connected to a body on the nozzle opening side, and the partitions form free ends on the reservoir side.
Because the reservoirs, the pressure generating chambers and the ink supply ports partitioned by the spacer are formed in the form of through-holes from one surface to the other surface, accuracy is provided simply and without the necessity of controlling the etching depth strictly.
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Furuta Tatsuo
Hosokawa Hiroshi
Kanai Fumiyuki
Kobayashi Atsushi
Sakai Shinri
Seiko Epson Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
Yockey David F.
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