Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-07-13
2002-09-03
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S094000
Reexamination Certificate
active
06443565
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an inkjet recording head and a manufacturing method thereof, and an inkjet recording apparatus in which ink droplets are ejected according to image information onto a recording medium for recording.
2. Description of the Related Art
Recently, the inkjet recording apparatus has attracted attentions as the low-cost high image quality color recording apparatus. There have been, for example, a piezo-type ink jet recording head that ejects ink from a nozzle with pressure generated by mechanically deforming a pressure chamber by use of piezoelectric material and a thermal type inkjet recording head that ejects ink from a nozzle with pressure generated by supplying a current to a heating element disposed on individual flow passage to thereby evaporate and expand ink.
In the case of these inkjet recording heads, a head chip on which an ink discharge mechanism for discharging ink droplets is mounted is jointed to the tip end of an ink supply member. In detail, ink is supplied from a tubular passage of the ink supply member to an ink supply opening of a head chip, and the ink is discharged from a nozzle.
In the case of the above-mentioned thermal type inkjet recording head, ink droplets are ejected onto a medium from a nozzle correspondingly to an image signal for recording. The driving force for ejecting ink droplets from a nozzle is generated by applying an electric pulse to an electric-heat conversion element (heat generator) to generate heat from the heat generator to thereby generate bubbles, and the bubbles causes pressure and the pressure functions to eject the ink droplets.
The schematic exemplary structure of an inkjet recording head is described herein.
The inkjet recording head is provided with a head chip having an ink discharge mechanism, for example, as shown in FIG.
4
. As shown in
FIG. 5
, the head chip includes an ink discharge mechanism having at least a nozzle (discharge opening)
18
for ejecting ink droplets, an individual flow passage (ink flow passage)
20
for supplying ink toward the nozzle
18
that has the nozzle
18
at the one end, a pressure generation;.section
24
disposed on individual flow passage
20
having the pressure generation plane positioned in parallel to the ink flow that flows in the nozzle direction in the flow passage, and a common liquid chamber
22
disposed commonly to plural individual flow passages
20
for supplying ink to the individual flow passage, and additionally having an ink supply opening
26
for supplying ink from the external to the common liquid chamber
22
as required in some cases. In this case, the common liquid chamber
22
temporarily holds ink supplied from an external ink tank. The common liquid chamber is also served as a part of the liquid tank, and the tank is commonly connected directly to plural individual flow passages
20
so that ink is supplied to the individual flow passages
20
.
In such an inkjet recording head, the pressure generation surface of the pressure generation section
24
is disposed in parallel to the ink flow that flows in the flow passage, and ink droplets are ejected from the nozzle into the direction perpendicular to the normal line of the pressure generation surface (side direction) (side ejecting type head).
A side ejecting type inkjet recording head as described hereinabove is manufactured from a substrate formed by joining an element substrate (equivalent to the above-mentioned pressure generation side broad) and a liquid flow passage substrate (equivalent to the above-mentioned flow passage substrate) as described in the Japanese Published Unexamined Patent Application No. Hei 11-227208.
The manufacturing process will be described in detail hereunder. An ink supply opening and an ink chamber (common liquid chamber) that are served for supplying ink from the external ink tank to an ink jet recording head are formed on a liquid flow passage substrate by means of wet anisotropic etching, and an individually formed ink flow passage (individual flow passage) is formed with high accuracy by means of reactive ion etching. In the case where a recess (recess
43
shown in
FIG. 9
of the Japanese Published Unexamined Patent Application No. Hei 11-227208) is formed on a heating resistor, it is formed by means of wet anisotropic etching. On the other hand, a heating resistor (pressure generation section), an electrode, and a driving element are formed on the element substrate. The above-mentioned liquid flow passage substrate and element substrate are positioned fittingly and joined, and cut (diced) and separated into individual inkjet recording heads by use of, for example, a dicer. At that time, a nozzle (discharge opening) for ejecting ink droplets is formed by cutting at a predetermined dicing position by means of dicing.
However, in the case of the recording apparatus that ejects liquid from a nozzle, the configuration of ink droplet to be ejected and the ejecting performance depend on the flow passage length if the cross-sectional area of the ink flow passage (individual flow passage) having a nozzle at the one end is constant, the fluid resistance depends on the length. of the flow passage, and as the result it is impossible to keep the drop quantity (drop volume) of a ink droplet constant if the flow passage length is not constant.
In other words, if the cutting position deviates from the dicing position when a nozzle (discharge opening) is formed by dicing as described hereinabove, the drop volume changes and the liquid drop size changes irregularly, and as the result the high quality image cannot be obtained.
However, it is difficult to position the cutting position more accurately because the cutting involves a process of several &mgr;m order range, therefore the cutting process is involved in a problem with stabilization of high quality and obtaining high quality image. On the other hand, because the positional deviation as described hereinabove affects adversely on the image quality significantly, a process for checking the dicing position after cutting process is required and many inspection processes are required, and furthermore only the head chips that have passed the inspection for rejection of off-specification product are used, as the result the rejection results in the high cost of the accepted products.
Japanese Published Unexamined Patent Application No. Hei 7-156411 discloses an inkjet printing head for ejecting ink droplets in the normal line direction of the heating surface of a heater served as a heating body having the structure in which the cross-sectional area of the circular cross section of the nozzle part is curved outward in a curved surface from the center of the circular cross section of the flow passage increasingly from the minimum inside diameter part of the flow passage through which ink flows toward the nozzle discharge side direction. In the Patent Application, the suppression of printing quality due to meniscus vibration after refilling is described, but the length of the nozzle part of the inkjet printing head described herein is determined by the plate thickness, and the relation between the length and the drop volume of a ink droplet is not described. In other words, in the case of the curved structure in which the flow passage is curved from the center toward the outside, it is difficult to reduce the change of the drop volume of ink droplets corresponding to the flow passage length difference and to keep the drop volume of ejected ink constant. As the result, it is impossible to resolve the problem in the manufacturing process and the problem of high cost due to the deviation of the cutting position as described hereinabove.
In the case where plural nozzles for ejecting ink droplets are formed by use of a dicer or the like as in the case of the above-mentioned side ejecting type inkjet recording head, it is quite difficult to cut without any deviation of the cutting position. A method has not been known that is used for forming nozzles stably so that the length of
Barlow John
Fuji 'Xerox Co., Ltd.
Morgan & Lewis & Bockius, LLP
Stephen Juanita
LandOfFree
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