Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1997-09-04
2001-10-02
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
C347S011000, C347S060000
Reexamination Certificate
active
06296340
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to an ink jet recording method and apparatus in which ink is ejected from a recording head to a recording material to effect the recording.
In a recording apparatus such as a printer, copying machine, facsimile machine or the like, an image constituted by a dot pattern is recorded on a recording material such as paper or a thin sheet of plastic material in accordance with image information. The recording apparatus is classified depending on the recording system into an ink jet type, a wire dot type, a thermal type, a laser beam type and the like. Among them, the ink jet type (ink jet recording apparatus) is such that ink (recording liquid) droplets are ejected through ejection outlets of a recording head, to effect the recording by deposition of the ink on the recording material.
Recently, various types of recording apparatuses are used, and high speed recording, high resolution, high image quality, low noise or the like are desired for these recording apparatuses. To meet the requirement, the ink jet recording apparatus is suitable. Non-contact printing is possible because of ejecting the ink from the recording head, and therefore, very stabilized images can be printed.
However, it uses ink which is liquid, and therefore, if the recording head is driven at or near a critical printing speed, various hydromechanism inconveniences arise. In addition, since the ink is liquid, the physical states thereof such as viscosity or surface tension or the like change due to ambient temperature or the time period in which it is not used. For example, even if the printing is possible in an initial state, the printing may become difficult due to the increase of the vacuum due to the decrease of the ambient temperature and/or the decrease of the remaining quantity of the ink in the container, or the like.
In many prior art printers, a plurality of nozzles are all driven in as short of a period as possible so as to record a vertical line as a straight line. In most cases, several tens nozzles are grouped into blocks each containing several-16 nozzles approximately, and they are simultaneously driven to accomplish high speed operation. In this case, if the apparatus is driven near a critical ejection period, the refilling of the ink to the nozzle is not quick enough with the result that the next ejection starts before the ink is sufficiently refilled. If this occurs, improper ejection or extreme reduction of the ejected quantity, occur. Particularly when, a great number of nozzles are driven in short period of time (including simultaneous drive), a vacuum level in a common liquid chamber temporarily increases too much, with the result that the refilling is not quick enough. For example, the next ejection starts when the ink bulges out of the nozzle surface as a result of large vibration and the ink is splashed. Generally, this tends to occur near the maximum acceleration speed of the ink meniscus.
As a measure, as disclosed in U.S. Pat. Nos. 5,173,717, 5,280,310 or U.S. Ser. No. 859,332, the ink is prevented from simultaneously ejecting through adjacent ejection outlets by control. By doing so, the flexibility of the ink supply direction from the common chamber to the nozzles is increased so that the ink supply quantity to the nozzle inlets is simultaneously increased.
By the phase difference of the vibration in the adjacent nozzles, the refilling speed can be increased by the damping of vibration and the refilling speed can be increased by pulsewise motion. Particularly, the improvement in refilling the other nozzles by the ejection reaction pressure wave is significant.
As regards the improvements provided by the ejection reaction pressure wave, there are two significant factors. One of them is that the ink in the nozzle with which the ejection is going to complete, that is, the nozzle with which the ink therein is ejected but the maximum meniscus retraction has not been reached, is given a reaction pressure wave by driving another nozzle, preferably an adjacent nozzle, by which the inertia of retraction of the meniscus is attenuated before the maximum meniscus retraction is reached. By doing so, the required refilling distance is reduced, thus reducing the refilling time.
Another effect is that multiple ejection reaction pulses are imparted to the nozzle with which the refilling is in the process after the maximum meniscus retraction is reached, by which the refilling speed itself is increased. Hereinafter, this driving system is called offset drive.
As for the means for the offset drive, the drive timings are offset for every other dot, so that the even number nozzles and odd number nozzles are driven separately. Alternatively, the drive timings may be offset for every other two dots or another multiple of dots.
In the case of a printer for printing monochromatic or color images, various stabilities such as dot reproducibility, density stability, tone reproducibility, color reproducibility or the like, are desired, and are met by a drive control method.
Particularly in the case of a heating type ink jet recording apparatus, the ink ejection property (ejection quantity, ejection speed, bubble formation, refilling state or the like) varies due to the ambient temperature or due to the self-rise by the printing action. For the purpose of maintaining the stability or stabilities, an ejection amount control method using multiple pulses is proposed. In addition, an apparatus using a combination of the offset control and the ejection amount control, has been developed.
However, the conventional offset drive involves the following problems.
1. If the nozzle number N (block number (i) x segment number (j)) is increased, the number of nozzles J simultaneously driven is increased with the result of the influence of the voltage drop Vdrop or the influence of hydraulic cross-talk, are increased, such that a block open period Tb (open time period per 1 block) is reduced due to the increase of the number of groups (block number i). If the offset drive is simply carried out, the block open period becomes one half with the result of difficulty in assuring the control width of the ejection quantity.
2. By increasing further the drive frequency, the block open period monotonely decreases.
Therefore, if the above 1 and 2 are combined, the block open period extremely decreases with the result of difficulty in assuring the optimum control time period for the purpose of measurement against the hydraulic stroke. In addition, by the increase of the energy per unit type, the flexibility for the ejection amount control for absorbing temperature rise of the head by accumulation of generated heat is not maintained. More particularly, since the open period of the multiple pulses for each group of ejections becomes shorter, and therefore, the ejection amount variation (ejection amount control range) by the multiple pulse control is not assured.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the present invention to provide an ink jet recording method and apparatus in which ejection amount control by the multiple pulse is assured to accomplish high speed and high quality image recording.
It is another object of the present invention to provide an ink jet recording method and apparatus in which multi-nozzle structure and high frequency drive are simultaneously accomplished.
It is a further object of the present invention to provide an ink jet recording method and apparatus capable of efficiently using an electric power source.
According to an aspect of the present invention, there is provided an ink jet recording method comprising: supplying a driving signal of a phase, wherein the driving signal comprising at least first and second signal periods with a rest period therebetween; and supplying a driving signal of a phase which is different to provide the first or second signal overlapping with the rest period of the driving signal having the first mentioned phase.
According to another aspect of the present invention, there is provided a
Akiyama Yuji
Hirabayashi Hiromitsu
Ikeda Masami
Izumida Masaaki
Kashino Toshio
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hallacher Craig A.
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