Incremental printing of symbolic information – Ink jet – Ejector mechanism
Utility Patent
1999-03-24
2001-01-02
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S037000, C347S014000
Utility Patent
active
06168261
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording apparatus for forming an image in accordance with an image signal or an original image, and particularly to an ink jet recording apparatus and a recording method.
2. Related Background Art
Conventionally, recording apparatuses using a variety of image forming means have been practically used. Among them, an ink jet recording apparatus in particular has gained wide acceptance because it is favorable in the respects of constitution and running costs. The ink jet recording apparatus performs the dot recording by discharging ink droplets through the nozzles of a recording head onto a recording medium. Exemplary of this recording apparatus is a constitution in which a recording head having a row of nozzles with a predetermined width is sequentially scanned for recording in the longitudinal and horizontal directions relative to the recording medium.
The ink jet recording method forms an image by jetting ink droplets directly onto the recording medium in the above way. Unlike the electrophotographic recording method, it has a feature of being able to form an intended image stably because of its smaller number of processes to form the image.
However, there is some instability with the recording of discharging fine ink droplets through the minute nozzles, for example, non-discharge caused by the clogging of ink discharge orifice in the nozzle with contaminants, dusts or thickened ink, non-discharge caused by the disconnection of the heater for heating the ink in the nozzle, non-discharge caused by ink droplets enclosing capriciously ink discharge orifice of the nozzle, etc., so that white streaks are likely to occur along the main scan (serial scan) direction, whereby there is a risk that a non-detective image can not be produced.
With such a problem, when the number of nozzles is increased up to several hundreds or thousands to speed up the recording, the probability of occurrence of an abnormal nozzle will increase proportionally thereto, and in the current state of the art, the non-defective image is difficult to obtain.
From the standpoint of fabrication of the recording head, it is conventionally requisite that all the nozzles be normal in non-defective heads in order to obtain the non-defective image. But if the number of nozzles is increased up to several hundreds or thousands, the probability of occurrence of defects during fabrication will increase in proportion thereto, resulting in decreased yield of fabrication, whereby it was difficult to manufacture economically in the practicable basis.
Also, even if the non-defective recording head is fabricated, the whole of the recording head will fail in service when one nozzle causes a trouble during use. Hence, there was a problem that if an abnormal nozzle occurs with a recording apparatus having six to eight multi-nozzles, defective printed matter may be produced every time of printing, whereby it is necessary to stop the apparatus to exchange the recording head.
To cope with such problem, it is conceived as a measure that the prevention against the clogging of nozzles is made, a recovery device for effecting the recovery is activated if a nozzle clogging is detected visually, or a recovery operation is incorporated into the print sequence, supposing that the clogging of nozzles may occur.
Also, one solution has been proposed that when the clogging of nozzles occurs during the printing, the overprint is made on the defective part of the image to reduce the influence of clogging (see for example U.S. Pat. No. 4,963,882 and U.S. Pat. No. 4,967,203).
However, with such a solution taken, the probability of occurrence of the clogging of nozzles will decrease, but is not totally reduced to zero, or further no measure has been made in the state of the art against irreversible undischarge, which will occur when contaminants passing through the ink filter at a certain probability may accumulate to clog some nozzles, or when the disconnection of discharge heater for heating the ink happens accidentally or due to the expiration of its span of life.
Also, by executing the recovery operation with a method as disclosed in the above-described U.S. patents, white streaks may be relieved to some extent, but not completely eliminated, whereby it is difficult to say that all the problems have been resolved.
On the other hand, with an image processing technique such as an error diffusion method, and further in a combination with a multi-valued print technique (which adjusts the size of a dot by forming one pixel with the overprint of a few ink droplets of smaller size and depending on the multiplicity of prints), the gradient representation is allowed, and further the provision of some specific color print heads beyond conventional four colors is easy, whereby the multicolor print such as the printing with six to ten colors is possible, with the color reproduction range broadly extended, so that the image representation ability itself with the ink jet print technique has reached a level closer to that of the offset printing.
However, at the practical level, the above problems have not been completely resolved, and the ink jet print technique has not been applied widely although it has many features such as the instant output of computer publishing, no impression creating process, no need of ink mixing, and the wider color reproduction range.
Accordingly, the requirements of offering the non-defective printed matter along with the productivity (speed, continuous operation) and profitability having industrial meanings to the ink jet print technique have not been realized with any of the conventional techniques.
SUMMARY OF THE INVENTION
The present invention is devised in view of the aforementioned problems, and its object is to provide a recording apparatus which is capable of providing a desired image without image defects even when a trouble of causing an image failure occurs in a recording element of a recording head.
It is another object of the present invention to provide a recording apparatus characterized by comprising:
main scan means for scanning recording means having a recording element row consisting of a plurality of recording elements for applying the ink onto a recording medium in a different direction from that of said recording element row, relatively to the recording medium,
sub-scanning means for sub-scanning said recording means and said recording medium relatively in a direction of said recording element row by a smaller amount than the total length of said recording element row every time of said main scan,
recording control means for subdividing all the recording elements of said recording element row in the direction of said recording element row into a plurality of blocks, and scanning different blocks in the same region of the recording medium by multiple times to record on the same region of the recording medium with recording elements in different blocks every time of different main scan,
image data supply means for subdividing a predetermined image data into pieces of image data in a complemental relation to each other, and supplying said piece of image data subdivided to said subdivided direction block in each main scan to thereby record said predetermined image data with recording elements in different blocks,
detection means for detecting abnormal recording elements of said recording means, and
image data moving means for removing image data corresponding to an abnormal recording element detected by said detection means from a piece of image data to be supplied to a block to which said abnormal recording element belongs, and moving said abnormal image data to another piece of image data to be supplied to another block for recording on the same region of the recording medium to superimpose said image data thereon.
Note that in this specification “print” includes “textile printing” or “recording”, and means that the image is applied on the print medium in a wider sense without limiting the objective of print.
Also, examples
Miyake Hiroyuki
Takahashi Kazuyoshi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Le N.
Nguyen Thinh
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