Metal working – Method of mechanical manufacture – Fluid pattern dispersing device making – e.g. – ink jet
Reexamination Certificate
1998-06-02
2001-07-17
Young, Lee (Department: 3729)
Metal working
Method of mechanical manufacture
Fluid pattern dispersing device making, e.g., ink jet
C347S045000, C347S047000, C451S008000
Reexamination Certificate
active
06260272
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inkjet printer head, a nozzle plate of an inkjet printer head and a method of manufacturing a nozzle plate of an inkiest printer head.
2. Description of the Related Art
An actuator having a plurality of ink chambers in the inside and a piezoelectric element mounted on each of the ink chambers is used as an actuator of a head installed in an inkjet printer. In such an actuator, expansion and reduction of the volume of each ink chamber by the piezoelectric element applies pressure to ink in the ink chamber, and therefore, the ink is ejected to the external through an nozzle passage connected with the ink chamber.
This kind of actuator is typically constructed of a cavity plate and a nozzle plate. The cavity plate has ink chambers and ink channels to supply ink to the ink chambers. The nozzle plate has very small nozzle passages. Namely, the diameter of each nozzle passage is very small.
As the cavity plate is a member that is attached to a piezoelectric element through a diaphragm, it is necessary for the cavity plate to have a predetermined stiffness and a sufficient thickness. Furthermore, it is required that cavities each having a relatively large volume, which serves as ink chambers, ink channels, and so on, are formed in the cavity plate.
Accordingly, in fabrication of the cavity plate, it is difficult to form nozzle passages each having very small diameter on the cavity plate, together with the cavities having a relatively large stiffness and a relatively large thickness.
Therefore, the actuator has a thin nozzle plate that is a member independent of the cavity plate, and the nozzle passages are formed on the nozzle plate. Thus, it is possible to make the diameter of the nozzle passage very small. Furthermore, one end part of the ink ejection surface side of the nozzle portion, hereinafter referred to as straight conduit portion, can be shaped into straight. Accordingly, it is possible to enhance a performance to eject ink straight in the ejecting direction.
However, each of the cavity plate and the nozzle plate is a member formed by injection-molding ceramic, such as alumina, and thereafter sintering it. For this reason, in fabrication of the cavity plate and the nozzle plate by the injection molding, there is a case that burrs or flashes are formed and some nozzle passages are closed due to no good molding.
Therefore, after fabrication of the cavity plate and the nozzle plate by the injection molding, the ink ejection surface of the nozzle plate is ground in a grinding process in order to remove burrs or flashes and in order to form the nozzle passage each having a correct diameter and keep a predetermined setting length of each straight conduit portions.
However, the diameter of the nozzle passage is very small, and the length of the straight conduit portion is very short. For these reasons, there is no method of measuring the diameter of the nozzle passage and the length of the straight conduit portion, so that it is impossible to determine whether or not the diameter or the length is accurately equal to a predetermined setting value. As a result, there is a case that dispersion of the diameter or the length for each nozzle occurs.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an inkjet printer head, a nozzle plate of an inkjet printer head and a method of manufacturing a nozzle plate of an inkjet printer head, which can easily form a straight conduit portion having a predetermined setting length.
According to the present invention, the above mentioned object can be achieved by an inkjet printer head having: a head body having an ink chamber; a nozzle plate attached on the head body and having a nozzle passage therethrough, a straight conduit portion being formed at one end portion of the nozzle passage located near an ink ejection surface of the nozzle plate and extending straight to an opening of the nozzle passage located on the ink ejection surface in order to eject an ink straight, another end portion of the nozzle passage being connected with the ink chamber, a recess being formed on the ink ejection surface, an area of an opening of the recess being greater than an area of the opening of the nozzle passage; and a piezoelectric element member attached on the head body for changing volume of the ink chamber.
Namely, when the nozzle plate is fabricated in manufacture of the inkjet printer head, at first, a member having at least the ink ejection surface and the nozzle passage is formed, and the inkjet ejection surface of the nozzle plate is next ground by the grinding process so as to remove burrs and flashes and to set a length of the straight conduit portion at a predetermined setting length.
In order to set a length of the straight conduit portion at the setting length correctly, it is necessary to control a grinding amount, i.e., a thickness of a part that is removed by grinding the ink ejection surface, accurately.
For this purpose, a recess is formed on the ink ejection surface. In the ink ejection surface of the nozzle plate, the area of the opening of the recess is greater than the area of the opening of the nozzle plate. Therefore, it is possible to measure a depth of the recess, and further control the thickness of the part that is removed by grinding the ink ejection surface accurately, on the basis of the measured value of the depth of the recess. For example, if the measured value of the depth of the recess after grinding is compared to the measure value of the initial depth of the recess before grinding, the thickness of the removed part can be recognized. Thus, it is possible to set the thickness of the removed part at the predetermined thickness. Consequently, it is possible to set the length of the straight conduit portion at the setting length easily and accurately.
According to the present invention, the above mentioned object can be also achieved by a nozzle plate to be used in an inkjet printer head and having a nozzle passage therethrough, a straight conduit portion being formed at one end portion of the nozzle passage located near an ink ejection surface of the nozzle plate and extending straight to an opening of the nozzle passage located on the ink ejection surface in order to eject an ink straight, a first recess being formed on the ink ejection surface, an area of an opening of the first recess being greater than an area of the opening of the nozzle passage.
Namely, when the nozzle plate is fabricated, at first, a member having at least the ink ejection surface and the nozzle passage is formed, and the inkjet ejection surface of the nozzle plate is next ground by the grinding process so as to remove burrs or flashes and to set a length of the straight conduit portion at a setting length. In order to set a length of the straight conduit portion at the setting length correctly, it is necessary to control the grinding amount, i.e., a thickness of a part that is removed by grinding the ink ejection surface, accurately.
For this purpose, a first recess is formed on the ink ejection surface. In the ink ejection surface of the nozzle plate, the area of the opening of the first recess is greater than the area of the opening of the nozzle plate. Therefore, it is possible to measure a depth of the first recess, and further control the thickness of the part that is removed by grinding the ink ejection surface accurately, on the basis of the measured value of depth of the recess. Thus, it is possible to set the thickness of the removed part at the predetermined thickness. Consequently, it is possible to set the length of the straight conduit portion at the setting length easily and accurately.
Furthermore, before the ink ejection surface is ground in the fabrication of the nozzle plate, a depth of the first recess is greater than the predetermined thickness of a part that is removed when the ink ejection surface is ground. Therefore, the first recess remains, after the ink ejection surface is ground such that the length
Inose Toshio
Isono Jun
Brother Kogyo Kabushiki Kaisha
Oliff & Berridg,e PLC
Tugbang A. Dexter
Young Lee
LandOfFree
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