Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-07-27
2002-12-10
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S094000
Reexamination Certificate
active
06491382
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge head and a liquid discharge apparatus that discharge a desired liquid by generation of a bubble due to thermal energy or the like, and more particularly, to a liquid discharge head and a liquid discharge apparatus having a movable member which is displaced by the use of generation of the bubble.
The term “recording” in the present invention means to attach not only an image such as a character and a figure having a meaning but also an image such as a pattern to a recording medium.
2. Description of the Related Art
Conventionally, in a recording apparatus such as a printer, an ink-jet recording method, a so-called bubble-jet recording method, has been known, in which energy such as heat is given to a liquid ink in a flow path to generate a bubble, ink is discharged from discharge part by an effort based on a steep volume change with the generation of the bubble, and the ink is adhered to the recording medium to form an image. In the recording apparatus using the bubble-jet recording method, a discharge part for discharging ink, a flow path communicating with the discharge part, and an electro-thermal converter as energy generation means for discharging ink provided in the flow path are generally provided, as disclosed in the U.S. Pat. No. 4,723,129.
According to such a recording method, a high-resolution image can be recorded in a high-speed and with a low noise, and the discharge part for discharging ink can be arranged in a high density in a head performing the recording method. Therefore, the recording method has many superior aspects that a recorded image or a color image of a high-resolution can be easily obtained by a small apparatus. Thus, the bubble-jet recording method has been used in various office appliances such as a printer, a copier and a facsimile, and furthermore, it has also been used in an industrial system such as a textile printing apparatus.
As bubble-jet technology has been used in products of various directions, the followings have been requested in recent years.
To obtain a high image quality, drive conditions are suggested by which a liquid discharge method and the like having a high discharge speed of ink and capable of performing good ink discharge based on stable bubble generation has been provided. In addition, from the viewpoint of high-speed recording, a recording method has been suggested in which the shape of the flow path is improved to obtain a liquid discharge head having a high filling (refilling) speed of a discharged liquid into the liquid flow path.
Other than the head described above, an invention having a construction to prevent a back wave being loss energy during discharge is disclosed in Japanese Patent Application Laid-Open No 6-31918, which pays attention to the back wave (a pressure directed to a direction opposite to the direction toward the discharge part) generated with generation of the bubble. The invention described in the gazette is one that a triangular portion of a triangular plate member is arranged opposing to a heater that generates the bubble. In the invention, the back wave is temporarily controlled by a little amount by the plate member. However, since the invention does not mention a relative relation between the growth of the bubble and the triangular portion nor has such conception, the invention has the following problem.
Specifically, in the invention described in the gazette, an ink droplet shape cannot be stable because the heater is positioned at the bottom of a concave portion and cannot have a communication state in-line with the discharge part. Moreover, since the growth of the bubble is permitted from the periphery of the apex portion of a triangle, the bubble grows from one side of the triangular plate member entirely to the opposite side. Accordingly, normal growth of the bubble in the liquid completes as if the plate member does not exist. Therefore, existence of the plate member is not effective to the bubble that has grown. On the contrary, refill to the heater being positioned at the concave portion causes a turbulent flow in a contraction step of the bubble because the entire plate member is surrounded by the bubble, which causes micro bubbles to accumulate in the concave portion and breaks the principle where discharge is performed based on a growing bubble.
Moreover, the European Patent Publication No. 436047A1 suggests an invention that alternately opens/closes a first valve and a second valve, the first valve blocking the vicinity of the discharge part and a bubble generation section between them and the second valve completely blocking the bubble generation section and an ink supply section between them (refer to
FIG. 4
to
FIG. 9
of the gazette). However, in the invention, the three chambers are severally divided in two divisions, ink following the liquid droplet tails long during discharge, and thus considerably more satellite dots are produced compared to a normal discharge method where bubble growth, contraction, and bubble disappearance are performed (thus, it is presumed that effect of meniscus withdrawal due to the bubble disappearance cannot be used). Further, although the liquid is supplied to the bubble generation section with the bubble disappearance during refilling, the liquid cannot be supplied to the vicinity of the discharge part until the next bubble growth begins. Accordingly, not only dispersion of the discharged liquid droplets is large, but also discharge response frequency is extremely small, which are not in practical levels.
On the other hand, a number of inventions using a movable member (a plate member or the like having a free end closer to the discharge part side from a fulcrum) that effectively contributes to liquid droplet discharge are suggested by the inventors, which are totally different from the prior art. Among others, Japanese Patent Application Laid-Open 9-48127 discloses an invention that defines an upper limit of a displacement of the movable member in order to prevent the action of the foregoing movable member from being troubled. In addition, Japanese Patent Laid-Open No. 9-323420 discloses an invention in which the position of a common liquid chamber in an upstream to the above-described movable member is shifted closer to the free end side of the movable member, that is, to a downstream side utilizing the advantage of the movable member. As a presumption for creating the inventions, the inventors adopted a mode that the growth of the bubble is suddenly released to the discharge part side from a state of temporarily wrapping the bubble by the movable member. Accordingly, no attention is paid to individual element of the whole bubble regarding the formation of the liquid droplet and the relative relation thereof.
As the next step, the inventors disclose an invention in Japanese Patent Application Laid-Open 10-24588 that a portion of a bubble generation region is released from the above-described movable member, which is an invention (an acoustic wave) where its attention is paid to the bubble growth by pressure wave propagation as an element regarding the liquid discharge. However, since the invention also pays attention only to the growth of the bubble during the liquid discharge, no attention is paid to individual element of the whole bubble regarding the formation of the liquid droplet and the relative relation thereof.
Despite that the front portion (an edge shooter type) of a bubble by a film boiling, which has been conventionally known, greatly influences the discharge, no invention has paid attention to this conventionally for contributing to the formation of the discharged liquid droplet more effectively. The inventors have researched this with much effort for technical resolution.
Furthermore, the inventors have obtained the following effective finding when they paid attention to the displacement of the movable member and the generated bubble.
The finding is that the displacement of the free end of the movable member to the growth of
Ishinaga Hiroyuki
Misumi Yoshinori
Sugiyama Hiroyuki
Taneya Yoichi
Gordon Raquel Yvette
Stephens Juanita
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