Pumps – Expansion and contraction of pump fluid
Reexamination Certificate
1999-07-28
2002-05-14
Thorpe, Timothy S. (Department: 3746)
Pumps
Expansion and contraction of pump fluid
Reexamination Certificate
active
06386832
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge head that discharges a desired liquid by the bubbles created by the application of thermal energy acting upon the liquid, and also, relates to the head cartridge and the liquid discharge apparatus using such liquid discharge head. More particularly, the invention relates to a liquid discharge head provided with the movable member which is displaceable by the utilization of the creation of bubbles, as well as to a head cartridge and a liquid discharge apparatus using such liquid discharge head.
Also, the present invention is applicable to a printer capable of recording on a recording medium, such as paper, thread, textile, cloth, leather, metal, plastic, glass, wood, and ceramics, among some others. the invention is also applicable to a copying machine, a facsimile equipment having communication systems, and an apparatus, such as a wordprocessor, which is provided with a printer. The invention is also applicable to a recording system for industrial use arranged complexly in combination with various processing apparatuses.
Here, in the specification of the present invention, the term “record” means not only the provision of characters, graphics, and other meaningful images, but also, it means the provision of patterns or other images which do not present any particular meaning.
2. Related Background Art
There has been known the ink jet recording method, that is, the so-called bubble jet recording method in which the energy, such as heat, is given to ink to cause the change of states of ink which is accompanied by the abrupt voluminal changes (creation of bubbles), and ink is discharged from the discharge ports by the acting force based on this change of states, and then, the discharged ink is allowed to adhere to a recording medium for the formation of images. The recording apparatus using this bubble jet recording method is generally provided with the discharge ports for discharging ink; the ink flow paths communicated with the discharge ports; and the electrothermal transducing devices (elements) each arranged in each of the ink flow paths, serving as means for generating energy used for discharging ink as disclosed in the specifications of U.S. Pat. No. 4,723,129, and others.
In accordance with a recording method of the kind, it is possible to record high quality images at higher speeds in a lesser amount of noises. At the same time, with the head whereby to execute this recording method, it becomes possible to arrange the discharge ports for discharging ink in higher density, among many other advantages, hence obtaining recorded images in higher resolution with a smaller apparatus, and obtaining images in colors with ease as well. In recent years, therefore, the bubble jet recording method is widely utilized for many kinds of office equipment, such as printer, copying machine, facsimile equipment, and further, utilized for the textile printing system and others for the industrial use.
Now, along with the wider utilization of the bubble jet technologies and techniques for the products currently in use in many fields, there have been various demands increasingly more in recent years as given below.
In order to obtain images in higher quality, the driving condition is proposed anew so that the liquid discharge method or the like should be arranged to perform good ink discharges on the basis of the stabilized creation of bubbles that enables ink to be discharged at higher speeds. Also, from the viewpoint of the higher recording, there has been proposed the improved configuration of flow paths so as to obtain the liquid discharge head which is capable of performing in the liquid flow paths the higher refilling for the liquid that has been discharged.
Besides a head of the kind, an invention is disclosed in the specification of Japanese Patent Application Laid-Open No. 6-31918 (particularly, FIG. 3) in which attention is given to the back waves (the pressure directed in the direction opposite to the one toward the discharge ports) which are generated along with the creation of bubbles, and then, the structure is arranged to prevent such back waves because the back waves result in the energy loss in performing discharges. In accordance with the invention disclosed in the specification thereof, the triangle portion of a triangular plate member is arranged to face each heater that creates bubbles. The invention can suppress the back waves temporarily and slightly by means of such plate member thus arranged. However, there is no reference at all as to the correlations between the development of bubbles and the triangular portion nor any idea is disclosed as to dealing with such correlations. Therefore, this invention still present the problems as given below.
In other words, the invention thus disclosed is designed to locate the heaters on the bottom of a recessed portion, thus making it difficult to provide the condition where the heaters can be communicated with the discharge ports on the straight line. As a result, each liquid droplet is not stabilized in keeping its shape uniformly. At the same time, since the development of each bubble is allowed to take place beginning with the circumference of each apex of the triangular portions, the bubble is developed from one side of the triangular plate member to the opposite side entirely. Consequently, the development of each bubble is completed in the liquid as has been usually effectuated as if there were no presence of the triangular plate members. Here, as to the bubble development, therefore, the presence of the plate members has no bearing at all. On the contrary, the entire body of each plate member is embraced by each bubble, and in the stage where the bubble is contracted, this condition may bring about the disturbance in the refilling flow to each of the heaters located in the recessed portion. As a result, fine bubbles are accumulated in the recessed portion, which may disturb the principle itself with which to perform discharges on the basis of the development of bubbles.
Meanwhile, in accordance with the EP-A 436047, an invention has been proposed to alternately open and close a first shut off valve arranged between the area in the vicinity of discharge ports and the bubble generating portion, and a second valve which is arranged between the bubble generating portion and the ink supply portion in order to shut them off completely (as shown in
FIGS. 4
to
9
of the EP-A 436047). However, this invention inevitably partitions each of the three chambers into two, respectively. As a result, the ink that follows the liquid droplet presents a great trailing at the time of discharge, which creates a considerable amount of satellite dots as compared with the usual discharge method where the development, contraction, and extinction are performed for each of bubbles (presumably, there is no way to effectively utilize the resultant retraction of meniscus in the process of the bubble disappearing). Also, at the time of refilling, liquid should be supplied to the bubble generating portion following the disappearing of each bubble. However, since it is impossible to supply liquid to the vicinity of the discharge ports until the next bubbling takes place, not only each size of discharge liquid droplets varies greatly, but also, the frequency of discharge responses becomes extremely smaller. Therefore, this proposed invention is far from being practical.
On the other hand, the applicant hereof has proposed a number of inventions that may contribute to the performance of effective discharges of liquid droplets, which use the movable member (the plate member or the like that has its free end on the discharge port side of its fulcrum unlike the conventional art). Of the inventions thus proposed, the one disclosed in the specification of Japanese Patent Application Laid-Open No. 9-48127 is such as to regulate the upper limit of the displacement of the movable member in order to prevent even a slight disturbance of the behavior of the mova
Ishinaga Hiroyuki
Shimazu Satoshi
Sugama Sadayuki
Sugiyama Hiroyuki
Taneya Yoichi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Rodriguez William
Thorpe Timothy S.
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