Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-07-28
2002-04-23
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S057000
Reexamination Certificate
active
06375309
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge method and a liquid discharge apparatus.
In this respect, the term “recording” in the description of the present invention means not only the provision of images having characters, graphics, or other meaningful representation, but also, the provision of those images that do not present any particular meaning, such as patterns.
2. Related Background Art
There has been known the so-called bubble jet recording method, which is an ink jet recording method whereby to form images on a recording medium by discharging ink from discharge ports using acting force exerted by the change of states of ink accompanied by the abrupt voluminal changes (creation of bubbles), and to form images on a recording medium by the discharged ink that adheres to it. For the recording apparatus that uses the bubble jet recording method, it is generally practiced to provide, as disclosed in the specifications of Japanese Patent Publication No. 61-59911 and Japanese Patent Publication No. 61-59914, the discharge ports that discharge ink, the ink paths conductively connected to the discharge ports, and heat generating members (electrothermal converting members) arranged in each of the ink paths as means for generating energy for discharging ink.
In accordance with such recording method, it is possible to record high quality images at high speeds with a lesser amount of noises. At the same time, the head that executes this recording method makes it possible to arrange the discharge ports for discharging ink in high density, with the excellent advantage, among many others, that images are made recordable in high resolution, and that color images are easily obtainable by use of a smaller apparatus.
Further, in the specifications of Japanese Patent Laid-Open Application No. 62-48585 and Japanese Patent Laid-Open Application No. 8-169116, there is disclosed a liquid jet recording head provided with energy generating members formed by a plurality of electrothermal converting members arranged in the respective ink flow paths to make it possible to present gradational representation. Also, in the specification of Japanese Patent Laid-Open Application No. 8-183180, a method is disclosed for giving pulses in order to modulate the discharge amounts stably.
However, if it is intended to increase the discharge amount by driving plural electrothermal converting members which are provided together in one ink flow path as in the above conventional example, the discharge speed is also increased at the same time eventually, or if it is intended to decrease the discharge amount, the discharge speed-is decreased simultaneously. Here, the relationship between the discharge amount and the discharge speed is almost proportional. Therefore, when the discharge amount should be decreased, the discharge instability may take place due to the slowdown of the discharge speed. This tendency is more conspicuous under the low temperature environment in particular. In the worst case, there is a fear that the disabled discharge occurs inevitably.
On the other hand, when the discharge amount should be made larger, the discharge speed becomes extremely faster. As a result, the dot configuration is disturbed on an image or the dot dispersion phenomenon may take place due to the satellite dots to cause the image degradation or the rebounding phenomenon of ink occurs when it is impacted on the surface of a recording sheet. The rebounded ink adheres to the surface of the recording head, hence affecting the stability of liquid discharges in some cases.
SUMMARY OF THE INVENTION
The present invention is designed in consideration of the problems of the conventional techniques of the method for forming discharge liquid droplets by driving a plurality of electrothermal converting members at a time. It is an object of the invention to materialize a discharge method capable of obtaining desired images recorded in higher quality.
It is another object of the invention to provide excellent techniques to overcome the difficulty lying in the technical background to make it possible to specify and obtain the amount of a larger droplet two to three times the amount of a smaller (discharged) droplet even when the smaller droplet is formed by use of one electrothermal converting member, while the larger droplet is formed by use of plural electrothermal converting members for the provision of images in good quality with the droplets having different discharge amounts, larger and smaller as required, respectively.
It is still another object of the invention to provide a discharge method and a recording method capable of forming high quality images by a desired stability of shooting accuracy with the uniform discharge speeds of the methods whereby to make formations different by driving plural electrothermal converting members altogether.
The present inventors hereof have ardently studied every aspect related to the development of an ink jet recording apparatus capable of printing images in higher quality. As a result, giving attention to the flow directivities of liquid (or gas) flow in the directions outgoing and ingoing from the ink flow paths at the liquid discharge ports along with the development and contraction of bubbles by the function of electrothermal converting members, the inventors hereof have made theoretical analyses and found that discharge amounts are made greatly changeable without causing the discharge speeds to vary too much by making the arrangement so that the components formed by the plural electrothermal converting members in the direction (discharging direction) outgoing from the ink flow paths do not intervene to change the discharge speeds themselves, while the components in the direction opposite to the flow direction are allowed to intervene. On the basis of such finding, the inventors hereof have conducted experiments and confirmed that the timing of a first driving pulse and that of a second driving pulse are deviated up to the level of 10 &mgr;sec order which has never been expected in the conventional art. As a result, it has been found that there exists an area where the discharge amount is made changeable, while the ink droplet discharging velocity is substantially constant (a range of timing deviation of 10 &mgr;sec to 20 &mgr;sec, for example).
Hence, the liquid discharge method of the present invention is designed to use a driving condition in a range where the discharge speed of droplets is made substantially constant, while the amount of droplet is made changeable with the timing difference of driving when droplets are discharged by driving a plurality of the electrothermal converting members one after another. These features are shared by the liquid discharge method of the invention that makes the discharge amount changeable.
Also, such timing difference is in a range where the discharge speed of droplets is made substantially constant, and also, the discharge amount is allowed to take the minimum value to the maximum value thereof.
Also, the timing difference is in a range to enable the discharged droplet to be formed as one dot on the surface of the recording medium.
Also, the timing difference is in a range where a second liquid droplet discharged by a second pulse catches up and collides with a first liquid droplet discharged by a first pulse before arriving at the surface of a recording medium, and these droplets are allowed to impact on the surface of the recording medium as one droplet.
Also, such timing difference is characterized in that while the meniscus formed on the discharge port by a first liquid droplet discharged by a first driving pulse is retracted, a second driving pulse is applied.
Also, the waveforms of pulses are different for the first and second pulses.
Also, the energy generating members are arranged in series in the direction of liquid flow in each of the liquid flow paths.
Also, the energy generating members are arranged in parallel with the flow direction of liquid in each of the liquid flow p
Ishinaga Hiroyuki
Koitabashi Noribumi
Sugiyama Hiroyuki
Tajika Hiroshi
Taneya Yoichi
Barlow John
Stephens Juanita
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