Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
1999-09-07
2001-07-17
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06260937
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention is related to an ink jet printing apparatus and an adjustable driving method for the ink jet printing apparatus.
2. Description of Related Art
There has been an ink jetting device having an ink jet head formed with piezoelectric ceramics as an ink jetting device used for an ink jet printer. A plurality of ink channels spaced by the piezoelectric ceramics are provided in this type of ink jet head. An ink cartridge storing ink is connected to one end of each ink channel and the ink stored in the ink cartridge is supplied to the ink channel. A nozzle for ejecting the ink in the ink channel is provided to the other end of each ink channel.
When ink droplets are ejected from the ink channel, a voltage corresponding to a driving signal is applied to the piezoelectric ceramics to deform the piezoelectric ceramics. The capacity of the ink channel is changed by the deformation. When the capacity of the ink channel is decreased, the ink in the ink channel is ejected from the nozzle, and when the capacity of the ink channel is increased, the ink in the ink cartridge is introduced to the ink channel. The ink ejected from the nozzle is printed on the paper as a character or a figure.
Although the ink jet head is made with very high accuracy, it is impossible to completely prevent variation in the size of the ink channel or the nozzle for each ink jet head. Therefore, the size of the ink channel or the nozzle is different for each ink jet head. If the size of the ink channel is different for each ink jet head, the deformation amount of the ink channel becomes different when the same driving voltage is applied to the piezoelectric ceramics. If the deformation amount of the ink channel is changed, the voltage applied to the ink in the ink channel at the time of change of the capacity of the ink channel is changed, therefore, the ejecting speed of the ink is changed. Further, if the size of the nozzle is different, the amount of the ejected ink or the ejecting speed is changed.
If the ejecting speed is changed as described above, the following problem is caused. When the ink jet head moves along the paper reciprocately to eject ink droplets, the adhering position of the ink droplet on the paper becomes different when the ink jet head moves forward and when the ink jet head moves back. Especially, in a multi-color ink jet printer provided with a plurality of ink jet heads corresponding to each color, the adhering position of the ink droplets of each color becomes different and therefore, printing with high quality cannot be performed.
Thus, the manufacturing error of all ink jet heads must be within a range of the predetermined tolerance to maintain predetermined printing quality in any ink jet head, and it has been necessary to manage the size of the ink channel or nozzle with strict tolerance in the manufacturing process of the ink jet head.
SUMMARY OF THE INVENTION
The invention concerns maintaining fixed printing quality in any ink jet head without management of the strict tolerance. The ink jet printing apparatus of the invention includes a memory for storing any one of data relating to the ejection speed of ink droplets, data relating to the ejection speed difference between each of the ink jet heads, and data relating to the ejection timing difference based on the ejection speed, and a controller that applies an ejection signal to the ink jet head at a predetermined ejection timing based on the data stored in the memory.
Thus, even if the ink channels or the nozzles of the ink jet head have a different size because of the manufacturing error, the effect of the size difference upon the ink jet head can be cancelled by the data stored in the memory. Therefore, the adhering position of the ink droplets ejected from the ink jet head becomes the same and high quality printing becomes possible.
The memory can be uniformly provided to the ink jet head and detachable uniformly with the ink jet head from the printing apparatus. Thus, when the ink jet head is exchanged, the ejection signal is applied to the exchanged ink jet head at a predetermined ejection timing based on the data stored in the memory provided uniformly to the exchanged ink jet head. Therefore, after the ink jet head is exchanged, the printing quality can be maintained.
The following method can be considered as a method for determining the ejection timing of the ink droplets. A first step for detecting data of ejection speed of the ink droplets for each ink jet head is carried out. Next, a second step for determining ejection timing for each ink jet head based on the data of the ejection speed is carried out. Then, the difference of the ejection speed of the ink droplets caused by the size difference of the ink channels or the nozzles of the ink jet head is eliminated and the adhering position of the ink droplets on the paper becomes identical so that the printing quality is unified.
In the above-described first step, printing is performed by moving the ink jet head along the paper maintaining a predetermined space therebetween to measure the ejection speed of the ink droplets by the difference of the printing position.
At this time, the position of dots printed on the paper by the printing operation is determined by the movement speed of the ink jet head and the ejection speed of the ink droplets. The ejection speed of the ink droplets can be obtained by measuring difference between the position of the printed dots and the theoretical printing position.
That is, because the movement speed of the ink jet head is fixed, if the ejection speed of the ink droplets is almost same in all ink jet heads, printing is made at a predetermined position. On the other hand, if the ejection speed of the ink droplets in a selected ink jet head is different from the ejection speed of the ink droplets in other ink jet heads, the printing position is different from the predetermined position in one direction that the ink jet head moves or in its opposite direction when the ink jet head moves back. Therefore, by determining a reference ink jet head in advance, when the difference between the printing position of the droplets ejected from the selected ink jet head and the printing position of the droplets ejected from the reference ink jet head becomes large, the speed difference between the ejection speed of the ink droplets of the selected ink jet head and the ejection speed of the ink droplets of other ink jet heads becomes large. The ejection speed of the ink droplets ejected from the selected ink jet head can be obtained by obtaining the speed difference.
In a third step following the second step, data corresponding to the ejection timing determined in the second step is stored in the memory uniformly provided to the ink jet head. The driving voltage is applied to the ink jet head at the ejection timing stored in the memory so as to eject ink at an ejection timing which is different for each ink jet head. As a result, the printing quality is not different for each ink jet head and fixed printing quality can be obtained in any one of the ink jet heads.
REFERENCES:
patent: 5138344 (1992-08-01), Ujita
patent: 5812156 (1998-09-01), Bullock et al.
patent: 5956052 (1999-09-01), Udagawa et al.
patent: 6019449 (2000-01-01), Bullock et al.
Brother Kogyo Kabushiki Kaisha
Oliff & Berridg,e PLC
Tran Huan
LandOfFree
Ink jet printing apparatus and adjustable driving method for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink jet printing apparatus and adjustable driving method for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink jet printing apparatus and adjustable driving method for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2490511