Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-06-28
2003-10-21
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06634734
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing an ink jet recording head for flying an ink droplet to adhere it onto a recording medium, an ink jet recording head manufactured by such a method, and a laser working method.
2. Related Background Art
In ink jet printing, print quality greatly depends upon a property of a nozzle portion for discharging, ink, and the property of the nozzle portion is determined by dispersion in nozzle diameters and shapes of nozzles. As methods for forming the nozzles, generally two methods, i.e., electrical discharge machining utilizing electroforming using a metallic plate, and, ultraviolet laser working method in which organic polymer resin material is subjected to sublimation by high energy laser such as excimer laser have been proposed. Presently, the latter method, i.e., ultraviolet laser working method has mainly been used for micro working.
In the past, when the organic polymer resin material is subjected to sublimation by the ultraviolet laser, a taper shaped working property in which worked area is gradually decreased from a laser input side to a laser output side by illuminating a laser onto the material has been achieved. By the way, in the ink jet recording head, in order to improve print quality, since a nozzle plate including nozzles tapered toward ink discharge side is required as a nozzle plate having discharge ports, when the nozzle plate is manufactured, the above-mentioned laser working method is used, and, in this case, after the nozzles are formed by illuminating the laser onto the nozzle plate from the ink supplying side, the nozzle plate is connected to an ink supplying member.
However, a length of the nozzle is required to be within a range from several tends of &mgr;m to about 100 &mgr;m to improve the print quality, add, thus, a thickness of the nozzle plate has the same dimension. Therefore, since the nozzle plate is very deformable and since the nozzle plate must be laser-worked from the ink supplying side as mentioned above and since the nozzle plate must be connected to the ink supplying member after nozzles were formed in the plate, after the connection, the nozzle plate is deformed by stress. Due to the stress deformation, the ink discharge nozzles which are aligned with each other in the same direction cannot be formed, with the result that ink discharging directions do not become the same, thereby deteriorating the print quality.
In order to solve such a problem, as a method for forming the ink discharge nozzles after the ink jet recording head is assembled, the following methods have been proposed.
One method is disclosed in National Publication of International Patent Application No. 6-510958. In this method, light beams regulated by mask patterns are obliquely incident on a discharge port forming plate so that the plate is worked along the light beam advancing directions due to the oblique incidence, with the result that a nozzle plate including tapered nozzles each having a wider inside width than an outside width is formed.
Another method is disclosed in Japanese Patent Publication No. 6-24874. In this method, a light beam is illuminated in a condition that a mask plate having a nozzle pattern is closely contacted with an ink discharge port forming plate. In this case, the mask plate and the ink discharge port forming plate which are closely contacted with each other are rocked or pivoted so that the light beam is obliquely incident on the plates, with the result that nozzles tapered toward outside are formed in the ink discharge port forming plate by advancing the working along the beam incident direction.
However, in the method disclosed in the National Publication of International Patent Application No. 6-510958, because of two-directional beam working, although the nozzles tapered toward outside are formed in the nozzle plate in the beam incident directions, regarding directions perpendicular to the beam incident directions, since nozzles flared toward outside are formed and cone-shaped tapers symmetrical with respect to the ink discharging direction are not formed, in the direction of the taper flared toward outside, ink discharging fluid resistance is generated to delay period of ink discharge, thereby making high speed printing impossible, and, further, in case of the flared nozzles, mist is generated during the ink discharging.
Further, also in the method disclosed in the Japanese Patent Publication No. 6-24874, since the mask plate and the ink discharge port forming plate are inclined with respect to the light beam in a time-lapse manner, in a working start condition and a working finish condition, i.e., in a time-lapse working process, it becomes difficult to form the tapers symmetrical with respect to the ink discharging direction, with the result that it is difficult to fly ink droplets stably in the given direction in the respective ink jet recording heads.
In the past, as a laser working method for micro-working a structure requiring minute construction and high accuracy, an ultraviolet laser working method has been used.
An example of such micro-working include formation of ink paths and ink discharge ports of an ink jet head.
In Japanese Patent Application Laid-Open No. 2-121842 or Japanese Patent Application Laid-Open No. 2-121845, a technique in which ink paths and ink discharge ports are formed with high accuracy by using an excimer laser which is typical as the ultraviolet laser is disclosed.
That is to say, the excimer laser is a laser in which an ultraviolet light (radiation) having short pulse (15 to 35 ns) is generated by discharge-exciting mixed gas of rare gas and halogen gas, and oscillation energy of the laser is several hundreds mJ/pulse and pulse repeating frequency is 10 to 500 Hz. When short pulse ultraviolet light having high luminance such as excimer laser light is illuminated onto a surface of polymer resin, ablative photodecomposition (APD) phenomenon in which the illuminated portion is instantaneously decomposed and scattered with plasma flash and shock noise is generated, thereby permitting so-called laser abrasion working of polymer resin.
In a YAG laser which was previously used in the laser working, although a hole can be formed, there is a disadvantage that an edge face is made rough. Further, in a CO
2
laser, there is a disadvantage that craters are formed around a hole. Since such laser working is laser heat working in which working is effected by converting optical energy into thermal energy, worked configuration is apt to be destroyed and it is difficult to effect micro-working. To the contrary, in the laser abrasion working using the excimer laser, since sublimation etching is effected by photo-chemical reaction for breaking covalent bond of carbon atoms, the worked configuration is hard to be destroyed and high accurate working can be achieved.
The laser abrasion working means a method for effecting sublimation working by the laser without liquid-state condition.
Particularly in the ink jet technical field, remarkable progress is achieved by utilizing the laser abrasion working using the excimer laser.
As the laser working techniques using the excimer laser have been put to practical use, the following facts are recognized.
That is to say, the oscillation pulse time of the illumination laser is about several tends ns (nano-seconds) regarding the excimer laser as the ultraviolet laser and from about 100 pico-seconds to several ns regarding ultraviolet ray of high harmonic oscillation of YAG laser, and, it was found that optical energy of the laser light illuminated onto the workpiece is not totally used for breaking of the covalent bond of atoms.
And, by the presence of optical energy which is not used for breaking of the covalent bond of atoms, the laser-worked portion of the workpiece is scattered before it is completely decomposed, with the result that by-product is generated around the worked portion.
Further, a part of the optical energy which is not used for breaking of the covalent bond o
Koide Jun
Suzuki Yoshiaki
Canon Kabushiki Kaisha
Feggins K.
Fitzpatrick ,Cella, Harper & Scinto
Nguyen Lamson
LandOfFree
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