Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-12-07
2002-11-26
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06485132
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge head used for a printer, a video printer, and the like adopted as the output terminal of a copying machine, a facsimile equipment, a word processor, a host computer, and the like. The invention also relates to a method for manufacturing liquid discharge heads, and to a recording apparatus. More particularly, the invention relates to the liquid discharge head provided with the substrate having heat generating members (electrothermal converting elements) formed on it to generate thermal energy as the liquid discharge energy, and to discharge recording liquid (ink or the like) from the discharge ports (discharge openings) as flying droplets which are caused to adhere to a recording medium. The invention also relates to the recording apparatus using such head.
Here, the term “recording” referred to in the specification hereof not only means the formation of meaningful images, such as characters and graphics, recorded on a recording medium, but also, means the formation of images, such as patterns, which do not present any particular meaning.
2. Related Background Art
Conventionally, the so-called ink jet recording method performs recording by use of a liquid discharge head is of non-impact type, which generates less noise, while making a highly densified printing possible at higher speeds. Besides, it is comparatively easy to maintain such recording method. There is also a good possibility that this method is executable maintenance-free. For such advantages and reasons as described above, the ink jet recording method has been widely adopted in recent years.
Of the ink jet recording methods, there has been known the bubble jet recording method, in which ink is caused to foam by the application of heat to discharge ink from the discharge ports (discharge openings), hence forming images on a recording medium with the adhesion of ink to it. For the recording apparatus that executes this bubble jet recording method, there are provided discharge ports (discharge openings) that discharge ink; liquid flow paths communicated with the discharge ports; heat generating members (electrothermal converting members or the like) that generate energy for causing ink in the liquid flow paths to be discharged as has been disclosed in the specification of U.S. Pat. No. 4,723,129. With a recording apparatus of the kind, it becomes possible to record high-quality images at higher speeds, with less noise as described above. At the same time, it is possible to arrange the discharge ports in higher density. Therefore, this kind of recording apparatus has an advantage, among many others, that images can be recorded in high resolution with a smaller apparatus, and images are easily obtainable in colors. As a result, the bubble jet recording method is utilized for office equipment, such as a printer, a copying machine, and facsimile equipment. Further, it is widely utilized for the industrial use, such as textile printing system, among others.
The general structure of the liquid discharge head used for a recording apparatus of this kind is to arrange the substrate having a plurality of liquid flow paths formed on it, and the other substrate having a plurality of heat generating members on it, hence enabling the groove formation surface and the arrangement surface of the heat generating members to be positioned to face each other and fix them in a laminated state. Each of the heat generating members is then allowed to fit with each of the liquid flow paths, respectively. Further, on the end faces of the substrates arranged in the laminated state, the discharge port plate (discharge port formation member) is fixed. Then, a plurality of discharge ports arranged for the discharge port plate are communicated with the leading end of the liquid flow paths, respectively.
Also, there is a case where the end face of the substrate is arranged integrally as one body so it may be drilled for the provision of the discharge ports without preparing the discharge port formation member separately.
In recent years, it has been required that a liquid discharge head of the kind should be able to print highly precise images at higher speeds. To meet such a requirement, the applicant hereof has proposed the structure that provides a movable member that controls bubbles in each of the liquid flow paths to guide bubbles to the discharge port side, as disclosed in Japanese Patent Application Laid-Open No. 6-31918. With the formation of this structure, it is anticipated that the discharge efficiency and the refilling characteristics are enhanced significantly.
Now, for the structure disclosed in the specification of the above mentioned Laid-Open Application, which has a movable member in each liquid flow path, it is extremely important to secure the close contact and the accuracy of the relative positions between a pair of substrates and each of the movable members, as well as the walls of the liquid flow paths. In other words, since the arrangement density of the liquid flow paths becomes very high in order to obtain highly precise images in recent years, the clearance obtainable for each of the movable members and the walls of liquid flow paths becomes smaller still, and in the worst case, the operation of the movable members may become imperfect if the positional precision is not good enough. Also, if the close contact and the accuracy of the relative positions are unfavorable, ink leakage may take place that stains the interior of the apparatus. As a result, there is a fear that such ink leakage even causes a short circuit between electric conductors in some cases. Also, the ink supply to the discharge ports may become insecure, which causes a shortage of ink to be discharged in some cases.
For the conventional structure described above, if the pair of substrates, the movable members, and the walls of the liquid flow paths are formed by different materials, there is a fear that the positional deviation takes place or the close contactness is affected due to the difference in the expansion coefficients of materials along with the temperature changes in operation that may cause the thermal expansion of the substrates and discharge port formation member even though the assembly is made with case in good precision when the head is manufactured.
For the head having the movable members in the liquid flow paths as described above, the warping and positional deviation of substrates, as brought about by the difference in the thermal expansion coefficient, may impede the normal operation of the movable members. Therefore, it is required for such a head to secure the higher positional precision than the conventional ink jet head, which is not provided with the movable members.
The inventors hereof, therefore, have devised the prevention of the defective operation of the movable members by reducing the difference in the thermal expansion coefficient of each of the members with the provision of the one and the same element to be contained in the movable members and the walls of the liquid flow paths, and the members that fix the movable members, as well as in the members that fix the walls of the liquid flow paths.
In this respect, meanwhile, there is the U.S. Patent of the Xerox application for such a technology as described above. However, in accordance with the Xerox application, the walls of liquid flow paths are provided by the performance of the anisotropic etching of the ceiling plate whose surface has the (100) plane of silicon crystal axes. However, with the structure thus disclosed, it is impossible to enhance the density of arrangement as required, because the section of each liquid flow path is made in the triangular form.
Further, if the silicon substrate whose surface has the (110) plane of crystal axes should be anisotropically etched, there is a problem that the resistance to ink of the walls of the liquid flow paths is lowered as compared with the (100) plane of the crystal axes, even if the section of each liquid flow pat
Hiroki Tomoyuki
Ikeda Masami
Imanaka Yoshiyuki
Ishinaga Hiroyuki
Kubota Masahiko
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