Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-07-30
2002-11-05
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06474792
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge head in which desired liquid is discharged by generation of a bubble created by acting thermal energy on liquid, a method for manufacturing such a liquid discharge head, a head cartridge on which such a liquid discharge head is mounted, and a liquid discharge apparatus. More particularly, the present invention relates to a liquid discharge head having a movable member displaced by utilizing generation of a bubble, a method for manufacturing such a liquid discharge head, a head cartridge on which such a liquid discharge head is mounted, and a liquid discharge apparatus.
Incidentally, a term (“recording” in the specification means that not only an image such as a character or a figure having a special meaning but also a meaningless image such as a pattern are formed on a recording medium.
2. Related Background Art
In the past, it is known to propose an ink jet recording method, i.e., so-called bubble jet recording method in which change in state of ink including abrupt volume change (generation of a bubble) is caused by applying energy such as heat to ink, and the ink is discharged from a discharge port by an acting force based on such change of state, thereby effecting recording by adhering the ink onto a recording medium. As disclosed in Japanese Patent Publication No. 61-59911, Japanese Patent Publication No. 61-59914 and U.S. Pat. No. 4,723,129, a recording apparatus using such a bubble jet recording method generally includes discharge ports from which the ink is discharged, ink flow paths communicated with the discharge ports, and heat generating bodies (electrical/thermal converters) as energy generating means disposed within the ink flow paths and adapted to generate energy for discharging the ink.
According to such a recording method, a high quality image can be recorded with low noise and at a high speed. Further, in a head for effecting the recording by using such a recording method, since the discharge ports for discharging the ink can be arranged with high density relatively easily, it is relatively easy to permit formation of an image having high resolving power and a color image by using a compact recording apparatus. As such, the bubble jet recording method has various excellent advantages. Thus, recently, the bubble jet recording method has been applied to various office equipments such as printers, copying machines and facsimiles and also has been applied to industrial equipments such as print apparatuses.
As the bubble jet technique has been utilized in various fields in this way, the following various requests have been increased.
In order to obtain a high quality image, there has been proposed a driving condition for providing a liquid discharging method capable of discharging the ink effectively on the basis of stable bubble generation and high speed ink discharging, or, in the viewpoint of high speed recording, there has been proposed an improved flow path arrangement for providing a liquid discharge head in which a speed of filling (re-fill) of liquid into the flow path to compensate for the discharged liquid is increased.
Other than such a head, in consideration of a back wave (pressure directing toward a direction opposite to a direction toward the discharge port) caused by generation of the bubble, Japanese Patent Application Laid-Open No. 6-31918 discloses a structure in which the back wave giving energy loss in the discharging is prevented. In this structure, a triangular portion of a triangular plate member is disposed in a confronting relationship to a heater for generating the bubble. In this structure, the back wave can slightly be suppressed temporarily by the plate member. However, since there is no teaching and no consideration regarding a relationship between growth of the bubble and the triangular portion, the above-mentioned structure arises the following problem.
That is to say, in the above-mentioned structure, since the heater is disposed on a bottom of a recessed portion not to be linearly communicated with the discharge port, a shape of a liquid droplet cannot be stabilized, and, since the growth of the bubble is permitted from periphery of an apex of the triangle, the bubble is grown throughout from one side of the triangular plate member to the other side thereof, with the result that the growth of the normal bubble is completed as if there is no plate member. Accordingly, the grown bubble does not relates to the presence of the plate member. Rather, since the entire plate member is surrounded by the bubble, during contraction of the bubble, the re-fill to the heater disposed in the recessed portion causes a turbulent flow, which may accumulates small bubbles in the recessed portion, thereby deteriorating the principle itself for discharging the ink based on the growth of the bubble.
Further, European Patent Publication No. 0 436 047 A1 proposes the invention in which a first valve disposed between an area near a discharge port and a bubble generating area and adapted to block these areas and a second valve disposed between the bubble generating area and an ink supplying area and adapted to completely block these areas are alternately opened and closed (refer to
FIGS. 4
to
9
of this document). However, in this invention, since three chambers are divided into groups (two chambers), in the discharging, the ink following to a liquid droplet has a long tail, with the result that many satellite dots are created in comparison with the normal discharging system including growth, contraction and disappearance of the bubble (It is guessed that effect of retraction of meniscus due to disappearance of the bubble cannot be utilized). Further, in the re-fill, although the liquid is supplied to the bubble generating area as the disappearance of the bubble, since the liquid cannot be supplied to the area near the discharge port until the next bubble is generated, not only there is great dispersion in discharged liquid droplets, but also discharge response frequency becomes very small, and, thus, this invention cannot be put to a practical use.
In consideration of the fundamental liquid discharging principle, the inventors investigated to provide a new liquid discharging method utilizing a bubble and a head used therewith, which were not obtained in the past, and proposed the invention using a movable member (plate member having a free end positioned near a discharge port with respect to a fulcrum) effectively contributing to the discharging of liquid, which is different from the conventional techniques (for example, refer to Japanese Patent Application Laid-Open No. 9-201966).
Now, the liquid discharging method and the head used therewith, as disclosed in the Japanese Patent Application Laid-Open No. 9-201966 will be described with reference to
FIGS. 29A
to
29
D and FIG.
30
.
FIGS. 29A
to
29
D are sectional views of a liquid discharge head, taken along a liquid flow path, explaining the discharging principle.
FIG. 30
is a partial sectional perspective view of the liquid discharge head shown in
FIGS. 29A
to
29
D. The liquid discharge head shown in
FIGS. 29A
to
29
D and
FIG. 30
has a most fundamental arrangement for realizing the liquid discharging method disclosed in the Japanese Patent Application Laid-Open No. 9-201966 to improve a discharging force and discharging efficiency by controlling a growing direction of a bubble and a propagating direction of pressure created by generation of the bubble in the liquid discharging.
Incidentally, in this specification, terms “upstream” and “downstream” are used with respect to a direction of the liquid flowing from a liquid supplying source through above a bubble generating area (or movable member) toward a discharge port.
The term “downstream side” regarding the bubble itself means a discharge port side portion of the bubble mainly relating to the discharging of a liquid droplet directly. More specifically, “downstream side” means a downstream side of the center of the bubble or a
Iri Junichiro
Ishinaga Hiroyuki
Kasamoto Masami
Mihara Hiroaki
Misumi Yoshinori
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Stephens Juanita
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