Incremental printing of symbolic information – Ink jet – Ejector mechanism
Utility Patent
1998-10-27
2001-01-02
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Utility Patent
active
06168263
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet head in which an electrostatic actuator is used as a means for generating pressure to eject an ink droplet, and relates more particularly to sealing the electrostatic actuator.
2. Description of the Related Art
One common type of ink jet head uses the electrostatically induced attraction force generated by an electrostatic actuator as described, for example, in Japanese Unexamined Patent Publication (kokai) Hei2-289351. This type of ink jet head has a nozzle, an ink path communicating with a nozzle, a diaphragm formed in part of the ink path, and an electrode formed in opposition to the diaphragm with an air gap therebetween. When an electrical pulse is applied between a diaphragm and electrode, the resulting electrostatic force deforms the diaphragm, causing an ink droplet to be ejected from the nozzle.
In the aforementioned ink jet head, however, the actuator contains a vibration chamber, which comprises a diaphragm and electrode as taught in the above-noted publication, and is exposed to the open air. As a result, dust and other airborne particulate can be pulled in when the actuator is driven. An apparent solution to this problem is sealing the actuator. However, when this is done, the air sealed inside the ejection chamber works as a resistance to the electrostatic attraction of the diaphragm, thus inhibiting normal operation by preventing sufficient electrostatic attraction. When the electrostatic attraction of the vibration chamber drops, pressure sufficient for ink droplet ejection cannot be generated, resulting in a severe drop in print quality and reliability. This problem can be addressed by, for example, increasing the drive voltage applied to the actuator, but it is difficult to generate sufficient electrostatic attraction within the common power supply voltage range generally used with such printers.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an ink jet head which overcomes the aforementioned problems.
It is another object of the present invention to provide an ink jet recording apparatus whereby sufficient electrostatic attraction can be obtained even with a sealed actuator.
SUMMARY OF THE INVENTION
To meet the above described need, an ink jet recording apparatus for printing to a recording medium by ejecting ink droplets from a nozzle comprises, according to the present invention: a diaphragm for applying pressure to a nozzle for ejecting an ink droplet; a capacitor formed by the diaphragm and an electrode opposing the diaphragm with a specific gap therebetween; a drive circuit for charging and discharging the capacitor to deform a diaphragm by means of electrostatic force and thereby eject an ink droplet from a nozzle; a lead for connecting the drive circuit and electrode; a vibration chamber containing a wall surface formed by the diaphragm and a wall surface to which the electrode is disposed; and a first cavity for communicating with the vibration chamber, and containing the wall surface to which the electrode is disposed; wherein the vibration chamber comprises a second cavity which is sealed airtight, and communicates with the vibration chamber or the first cavity.
The actuator in an ink jet recording apparatus according to the present invention thus has an airtight structure, thereby solving the problem of dust and other airborne particulate being sucked into the ink jet head when the diaphragm is driven.
Furthermore, by providing a second cavity communicating with the vibration chamber or the first cavity, the volume of the airtight sealed part of the actuator is made sufficiently large relative to the volume displaced by the diaphragm when the diaphragm is driven. The pressure rise inside the actuator is therefore small when the actuator is driven, the ejection force required for ink ejection can be sufficiently assured, and an ink jet head achieving outstanding print quality and reliability can be provided.
In an ink jet recording apparatus according to another version of the present invention in which the diaphragm is formed in a first substrate, the electrode is formed in a second substrate which is bonded to the first substrate, and a vibration chamber is formed between the first and second substrates when the second substrate is bonded to the first substrate, a cavity communicating with the vibration chamber and increasing the volume of the airtight sealed part is preferably formed in the first substrate. Because a relatively large volume cavity can be formed with this configuration, the actuator volume can be increased effectively without increasing the size of the ink jet head.
The first substrate is also preferably made of silicon. In this case, the cavity for increasing the volume of the airtight sealed part can be formed simultaneously to diaphragm formation by means of anisotropic etching of silicon. It is therefore also possible to suppress an increase in manufacturing steps and cost.
Yet further preferably, the wall surfaces forming the cavity for increasing the volume of the airtight sealed part are the (111) face of silicon. Using the (111) face where the etching rate is extremely slow enables yet higher precision processing of the cavity, and has the further benefit of enabling yet higher density pattern formation.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated, by referring to the following description and claims taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4153836 (1979-05-01), Simm
patent: 4203128 (1980-05-01), Guckel et al.
patent: 4234361 (1980-11-01), Guckel et al.
patent: 4312008 (1982-01-01), Taub et al.
patent: 4384899 (1983-05-01), Myers
patent: 4429321 (1984-01-01), Matsumoto
patent: 4459601 (1984-07-01), Howkins
patent: 4471363 (1984-09-01), Hanaoka
patent: 4520375 (1985-05-01), Kroll
patent: 4588998 (1986-05-01), Yamamuro et al.
patent: 4611219 (1986-09-01), Sugitani et al.
patent: 4719477 (1988-01-01), Hess
patent: 4725851 (1988-02-01), Sutera et al.
patent: 4733447 (1988-03-01), Ageishi
patent: 4766666 (1988-08-01), Sugiyama et al.
patent: 4777497 (1988-10-01), Nozu et al.
patent: 4879568 (1989-11-01), Bartky et al.
patent: 5116457 (1992-05-01), Jerman
patent: 5144342 (1992-09-01), Kubota
patent: 5163177 (1992-11-01), Komura
patent: 5371529 (1994-12-01), Eguchi et al.
patent: 5376231 (1994-12-01), Matsumoto et al.
patent: 5446485 (1995-08-01), Usui et al.
patent: 5513431 (1996-05-01), Ohno et al.
patent: 5534900 (1996-07-01), Ohno et al.
patent: 5563634 (1996-10-01), Fujii et al.
patent: 5644341 (1997-07-01), Fujii et al.
patent: 0 479 441 (1992-04-01), None
patent: 488 113 A1 (1992-06-01), None
patent: 2 146 566 (1985-04-01), None
patent: 55-79171 (1980-06-01), None
patent: 56-142071 (1981-11-01), None
patent: 58-224760 (1983-12-01), None
patent: 59-115860 (1984-04-01), None
patent: 60-97860 (1985-05-01), None
patent: 61-59911 (1986-12-01), None
patent: 1-246850 (1989-02-01), None
patent: 2-012218 (1990-01-01), None
patent: 2-080252 (1990-03-01), None
patent: 2-274552 (1990-08-01), None
patent: 2-266943 (1990-10-01), None
patent: 2-89351 (1990-11-01), None
patent: 2-51734 (1990-11-01), None
patent: 2-289351 (1990-11-01), None
patent: 3-67659 (1991-03-01), None
patent: 3-288649 (1991-12-01), None
patent: 3-297653 (1991-12-01), None
patent: 3-253346 (1991-12-01), None
patent: 3-295654 (1991-12-01), None
Fujii Masahiro
Ishikawa Hiroyuki
Nojima Shigeo
Takekoshi Taro
Nguyen Thinh
Seiko Epson Corporation
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