Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-07-26
2002-08-27
Nguyen, Thinh (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06439701
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge head for applying thermal energy to liquid for generating a bubble therein thereby discharging the liquid, and a head cartridge and a liquid discharge apparatus having such liquid discharge head, and more particularly a liquid discharge head provided with a movable member capable of movement utilizing the bubble generation, and a head cartridge and a liquid discharge apparatus having such liquid discharge head.
In the present invention, “recording” means providing a recording medium not only with a meaningful image such as a character or graphic but also with a meaningless image such as a pattern.
2. Related Background Art
In the recording apparatus such as a printer, there is already known so-called bubble jet recording method, or an ink jet recording method in which for example thermal energy is given to liquid ink contained in a flow path to generate a bubble therein, and the ink is discharged from a discharge port by an action force based on a rapid volume change resulting from such bubble generation and is deposited on a recording medium to form an image. The recording apparatus utilizing such bubble jet recording method is generally provided, as disclosed in the U.S. Pat. No. 4,723,129, with a discharge port for discharging ink, a flow path communicating with the discharge port, and an electrothermal converting member constituting energy generation means for discharging ink contained in the flow path.
Such recording method, being capable of recording a high quality image at a high speed with a low noise level and also of arranging the discharge ports for ink discharge at a high density in the recording head for executing such recording method, has various advantages such as ability to recording an image of a high definition with a compact apparatus and to record a color image easily. Such bubble jet recording method is recently employed in various office equipment such as a printer, a copying apparatus, a facsimile apparatus etc. and even to industrial systems such as a print dyeing apparatus.
With such spreading of application of the bubble jet technology, there are being generated various requirements as explained in the following.
For obtaining an image of high quality, there are proposed a driving condition for realizing a liquid discharge method capable of providing a high ink discharge speed and achieving satisfactory ink discharge based on stable bubble generation, and an improved shape of the flow path for obtaining a liquid discharge head with a high liquid refiling speed into the flow path, in view of the high speed recording.
In addition to such head structures, the Japanese Patent Application Laid-Open No. 6-31918 takes into consideration a backward wave (pressure generated in a direction opposite to the direction toward the discharge port) and discloses a liquid discharge head of a structure capable of preventing the backward wave causing an energy loss at the ink discharge. In the liquid discharge head disclosed in the above-mentioned patent application, a triangular portion of a triangular plate-shaped member is positioned opposed to the heater for generating the bubble. In such liquid discharge head, the backward wave is temporarily and slightly suppressed by the plate-shaped member, but the relationship between the bubble growth and the triangular portion of the plate-shaped member is not at all disclosed nor considered, so that the above-mentioned liquid discharge head has the following drawbacks.
In the above-mentioned patent application, the shape of the liquid droplet cannot be stabilized since the heater is positioned in the bottom of a recess and is not in linear communication with the discharge port and the bubble growth from a side of the triangular plate-shaped member to the entire other side since the bubble growth is permitted from the vicinity of the apex of the triangular portion, whereby the bubble executes ordinary growth in the liquid as if the plate-shaped member is not present. Consequently the presence of the plate-shaped member does not affect at all the growth bubble. Inversely, since the plate-shaped member is entirely surrounded by the bubble, the liquid refill to the heater position at the bottom of the recess generates a random flow at the contraction of the bubble, thereby resulting in accumulation of small bubbles in the recess and disturbing the liquid discharge principle itself based on the bubble growth.
On the other hand, the EP laid-open No. 436047A1 discloses an invention of alternately opening a first valve for intercepting a path between an area in the vicinity of the discharge port and a bubble generating portion and a second valve for intercepting a path between the bubble generating portion and an ink supply portion (cf. FIGS. 4 to 9 in the EP laid-open No. 436047A1). In such invention, however, since only two of the three chambers are separated at a time, the ink discharged following the ink droplet forms a large trailing, whereby a satellite dots considerably increase in comparison with the ordinary liquid discharge method executing the bubble growth, bubble contraction and bubble vanishing. This is presumably because the effect of meniscus retraction by the vanishing of bubble cannot be utilized. Also at the liquid refilling, the liquid is supplied to the bubble generating portion by the bubble vanishing, but cannot be supplied to the area in the vicinity of the discharge port until a next bubble is generated, so that such liquid discharge head not only shows a large fluctuation in the discharged liquid droplet but also has a very low response frequency of liquid discharge, thus being not in the practical level.
The present applicant has made various proposals on a liquid discharge head different completely from the aforementioned liquid discharge head and having a movable member capable of effectively contributing to the liquid discharge droplet (for example a plate-shaped member of which a free end is positioned closer than the fulcrum thereof to the discharge port). Among such proposals, the Japanese Patent Application Laid-Open No. 9-48127 discloses a liquid discharge head capable of limiting the upper limit of displacement of the aforementioned movable member, in order to prevent a slight aberration in the behavior of such movable member. Also the Japanese Patent Application Laid-Open No. 9-323420 discloses a liquid discharge head in which the position of a common liquid chamber, formed at the upstream side of the aforementioned movable member, is shifted to the free end side thereof, namely to the downstream side, utilizing the advantage of the movable member, thereby improving the refilling ability.
As a liquid discharge head in which the displacement of the movable member is limited as disclosed in the aforementioned Japanese Patent Application Laid-Open No. 9-48127, the present applicant proposed a configuration in which a stopper, positioned close to the movable member displaced by the bubble generation, is provided so as to protrude from a position on an internal wall of the flow path and opposed to the free end side portion of the movable member, wherein the displacement of the movable member is limited by such stopper. In such liquid discharge head, however, when the movable member is displaced upward by the bubble generation in the liquid on the heater and approaches a contact plane with the movable member, the approaching speed of the movable member to the stopper is lowered by the presence of a liquid layer therebetween, thereby causing a liquid movement toward the upstream side in the flow path and deteriorating the response speed of the movable member.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a liquid discharge head having a stopper as a limiting portion on the internal wall of a liquid flow path for limiting the displacement of a movable member, provided in the flow path, within a desired range, the liquid discharge head being capable of suppressing the mov
Ishinaga Hiroyuki
Mori Masao
Sugama Sadayuki
Taneya Yoichi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Mouttet Blaise
Nguyen Thinh
LandOfFree
Liquid discharge head, head cartridge and liquid discharge... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid discharge head, head cartridge and liquid discharge..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid discharge head, head cartridge and liquid discharge... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2879783