Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-07-24
2004-07-13
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S057000
Reexamination Certificate
active
06761434
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharging head, a liquid dicharging apparatus and a liquid discharging method for discharging desired liquid by applying thermal energy to the liquid, and more particularly to a liquid discharging head, an element substrate, a liquid charging apparatus and a liquid discharging method capable of discharging two or more liquid droplets in succession from a discharge port.
The present invention is applicable to various apparatus such as a printer for recording on media such as paper, yarn, fiber, textile, leather, metal, plastics, glass, wood, ceramics etc. a copying machine, a facsimile having a communication system, or a word processor having a printer unit, or to industrial recording apparatus coupled in complex manner to various processing apparatus.
In the present invention, “recording” means not only providing a recording medium with a meaningful image such as a character or an image but also providing with a meaningless image such as a pattern.
2. Related Background Art
There is already known a liquid jet recording method, so-called bubble jet recording method, in which energy such as heat is given to ink (liquid) to generate a rapid state change therein and the liquid is discharged from a discharge port by an action force resulting from such state change for deposition on a recording medium thereby forming 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, a discharge port for discharging the liquid, a liquid flow path communicating with the discharge port, and an electrothermal converting member constituting energy generating means for discharging the liquid present in the liquid flow path.
Such recording method has various advantages such as ability of recording high quality image with a high speed and with a low noise level, and ability for recording the image of a high resolution or even a color image with a compact apparatus, since discharge ports for discharging liquid can be arranged with a high density in the head for executing such recording method. For this reason, the bubble jet recording method is recently employed in various office equipment such as a printer, a copying machine, a facsimile etc. and is being adopted also in industrial system such as a text printing apparatus.
FIG. 23
is a schematic cross-sectional view around the electrothermal converting member of a conventional liquid discharge head for executing the recording by such recording method. In the illustrated example, the electrothermal converting member is composed of a resistance layer
100
and electrodes
101
a
,
101
b
laminated thereon and mutually spaced as a pair. Thus a heat generating portion
105
, for generating heat by voltage application, is formed between the electrodes
101
a
and
101
b
, and such portion constitutes a bubble generating area where a bubble is generated by film boiling. On the resistance layer
100
and the electrodes
101
a
,
101
b
, there are formed two protective layers
102
,
103
for protecting these components.
A discharge oppening for discharging liquid by the generation of a bubble
104
by the heat from the heat generating portion
105
may be provided, as in a case of opening S, in a position opposed to the heat generating portion
105
(so-called side shooter), or in a lateral position as in a case of opening E (so-called edge shooter). In either case, the bubble
104
in such configuration of the liquid discharge head grows larger toward a liquid chamber X with a relatively smaller liquid flow resistance, so that a bubble vanishing position
106
is in the central part of the heat generating portion
105
or is somewhat displaced toward the liquid chamber.
Thus, in the liquid discharge head as shown in
FIG. 23
, the liquid is relatively strongly pushed back toward the liquid chamber X together with the growth of the bubble
104
. Consequently a meniscus, formed at the discharge port and constituting an interface between the liquid and the external atmosphere, shows a relatively large retraction and a relatively large vibration by the bubble extinction after the liquid discharge. Also in the bubble vanishing process, there are generated a liquid flow from the liquid chamber toward the heat generating portion
105
and a liquid flow from the discharge port toward the heat generating portion
105
in an approximately same magnitude whereby the practical start timing of liquid refilling toward the discharge port becomes after the liquid flow from the discharge port is almost finished and is relatively late, so that a relatively long time is required until the meniscus returns to the normal state and becomes stabilized. For this reason, for discharging liquid in succession, there is required a relative long interval between the discharges and the drive frequency capable of satisfactorily discharging the liquid is inevitably limited.
For increasing the drive frequency in the liquid discharge head, the present applicant already proposes a configuration provided with a movable member provided in the bubble generating area and adapted to displace along with the growth of the bubble and a limiting portion for limiting the displacement of the movable member within a desired range, wherein the limiting portion is provided opposed to the bubble generating area in the liquid flow path and, by the substantial contact between the displaced movable member and the limiting portion, the liquid flow path including the bubble generating area becomes a substantially closed space except for the discharge port. In such liquid discharge head, at the growth of the bubble, the movable member so displaces as to substantially close the liquid flow path at the upstream side of the bubble generating area, so that the liquid pushed back toward the upstream side at the bubble growth is relatively limited. At the bubble vanishing, the movable member so displaces as to reduce the liquid flow resistance at the upstream side, so that the bubble vanishing at the upstream side of the bubble generating area is accelerated and proceeds faster than in the downstream side. Therefore, the meniscus shows a smaller retraction and the liquid refilling is executed efficiently.
Also in the liquid discharge head, gas dissolved in the liquid may be released at the bubble generation to form a microbubble which may remain in the liquid flow path. In order to prevent defective discharging operation resulting from a large amount of such remaining microbubbles, there is periodically executed a recovery operation of sucking out the liquid in the vicinity of the discharge port thereby removing the microbubbles. On the other hand, in the liquid discharge head provided with the movable member, since the liquid is pushed back little to the upstream side, the microbubbles are emitted from the discharge port before they increase to a level hindering the liquid discharging operation and remains little in the liquid flow path. For this reason the recording operation can be executed continuously for a relatively long period, in excess of 100 sheets at maximum.
As explained in the foregoing, the liquid discharge head with the movable member, capable of rapid liquid refilling without a large retraction of the meniscus, has advantages of executing the liquid discharge with a relatively short interval and enabling drive with a relatively high frequency.
In order to enable drive with a higher frequency, it is conventionally conceived that a faster extinction of the bubble, generated for the preceding liquid discharge, is practically effective. This is because, in order to achieve the succeeding discharge in satisfactory manner, it is conceived that the succeeding discharge has to be executed after the meniscus returns to the stationary state and is stabilized after the vibration process and after the liquid refilling is completed, and because such completion of refilling and stabilization of the meniscus are achieved by the co
Ishinaga Hiroyuki
Misumi Yoshinori
Sugiyama Hiroyuki
Taneya Yoichi
Canon Kabushiki Kaisha
Do An
Fitzpatrick ,Cella, Harper & Scinto
Meier Stephen D.
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