The invention relates to print devices and more particularly to a printhead with an alignment compensation method and system.
In ink jet printers, ink is fed to an array of digitally controlled nozzles on a printhead. As the printhead passes over the media, ink is ejected from the array of nozzles to print on the media. Current design combines the printhead with a print cartridge. The print cartridge is then installed in the carriage of a printer, likely incurring undesirable rotation of the print cartridge which can normally skew printed lines. Correction of misalignment is thus required.
A conventional alignment method first supplies printing instructions to a printhead to energize printing elements in various groups (primitives). The printed pattern is then detected by optical sensors in the printer. Based on the detection, a position offset error for each primitive is determined. These errors generate a separate time correction for each of the primitives such that, when the printing is executed, the time period for printing a dot is advanced or delayed for each primitive so as to align the dots.
The conventional method, as described above utilizing software, can reduce print speed and require additional costs for optical sensors and other elements.
The present invention is generally directed to a print alignment method. According to one aspect of the invention, a method comprises detecting a skew direction of the printhead, receiving column data, corresponding to columns of printhead nozzles, dividing column data into N sections, selecting individual N column data, when the skew is to the right, the printhead receives the first section of first column data, the second section of second column data, the third section of third column data and so on; and when the skew direction is to the left, the printhead receives the Nth section of the first column data, the (N-1)th section of the second column data, the (N-2)th section of the third column data, and so on.
The invention further provides a print alignment method comprising detecting a skew direction of the printhead, receiving column data, corresponding to columns of printhead nozzles, dividing column data into N sections, when the skew direction is to the right, the printhead receives the first section of the column data to print and then receives the second section of the column data to print and so on in a print period (tp), and when the skew direction is the right, the printhead receives the Nth section of the column data to print and then receives the (N-1) th section of the column data to print and so on in a print period (tp).
The invention further provides a print alignment system for a printhead comprising a print module, a compensation module and a compensation print module. The print module receives print data and translates it into column data, corresponding to a plurality of columns of printhead nozzles. The compensation module receives a test pattern and outputs compensation data, comprising a skew direction and displacement offset. The compensation print module executes an alignment procedure, in accordance with the column data and the compensation data, comprising dividing column data into N sections, and selecting specific N column data, such that when the skew is to the right, the printhead receives the first section of first column data, the second section of second column data, the third section of third column and so on to print, and when the skew direction is to the left, the printhead receives the Nth section of first column, the (N-1)th section of the second column data, the (N-2)th section of third column data and so on to print.
The invention further provides a print alignment system for a printhead comprising a print module, a compensation module and a compensation print module. The print module receives print data and translates it into column data, corresponding to a plurality of columns of printhead nozzles. The compensation module receives a test pattern and outputs compensation data, comprising a skew direction and displacement offset. The compensation print module executes an alignment procedure, in accordance with the column data and the compensation data, comprising dividing column data into N sections, when the skew direction is to the right, the printhead receives and prints the first section of the column data and then receives and prints the second section of the column data and so on in a print period (tp), and when the skew direction is the right, the printhead receives and prints the Nth section of the column data and then receives and prints the (N-1)th section of the column data and so on in a print period (tp).
a is a schematic diagram of printhead skew detection.
b is a diagram of printhead nozzle arrangement.
c shows printing when a printhead is perpendicular to a moving direction.
a is a schematic diagram of printhead skew detection. Area 10a shows printing when a printhead is perpendicular to a print bar and area lob shows printing when a printhead is not perpendicular to a print bar. Area I shows printing without any displacement offset and area II shows printing with displacement offset. In the present disclosure, the printhead receives one, two and three dpi to the right (marked as +1, +2 and +3), one, two and three dpi to the left (marked as −1, −2 and −3) and the line marked 0 represents zero displacement offset. In area 10a, the printhead is perpendicular to the print bar when lines 0 in area I and area II connect. In area lob, the printhead has one dpi displacement to the left when lines +1 in area I and area II connect. The method demonstrates skew of the printhead and displacement offset.
b is a diagram of printhead nozzle arrangement. 0˜3F represent nozzles. The printhead has two columns of nozzles driven by address signals A1˜A8 and primitive select signals PS1˜PS8, where the first column of nozzles is driven by address signals A1˜A8 and primitive select signals PS1, PS3, PS5 and PS7, and the second column of nozzles is driven by address signals A1˜A8 and primitive select signals PS2, PS4, PS6 and PS8. In addition, the two columns of nozzles are further divided into banks of nozzles driven by address signals A1˜A8 and primitive a select signal. When the printhead starts to print, address signals A1˜A8 are sequentially asserted and the nozzle outputs ink if the corresponding primitive select signal is asserted.
c shows printing when a printhead is perpendicular to a moving direction. When each nozzle outputs ink in a position pulse, the printing is a straight line, and each time period of one position pulse is t_p. The following embodiments illustrate printhead 11 using two columns of nozzles 12.
Compared with
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications.
Number | Date | Country | Kind |
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93140054 | Dec 2004 | TW | national |