JP2006168047A - Printing position correcting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an effective printing position correcting method in inkjet recording accompanying the speeding up of large-sized printers and the diversification of printing objective media. <P>SOLUTION: A recording device having a means which can automatically measure and judge a distance between the head and a printing paper can automatically correct the printing position which can be acquired by an operation from the discharging speed of ink. Also, when the discharging speed is changed depending on the head, the printing position correction is performed by the distance between one head and the printing paper. In the case of a distance between different heads and the printing paper, a correction value is acquired by the operation, and the correction can be performed by one printing position correction only. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing apparatus that forms an image by ejecting ink called ink jet and landing on a paper surface, in particular, ejecting ink and reciprocating a carriage having a head, and ejecting ink during both reciprocating movements. The present invention relates to a printing position correction method that corrects deviation of ink landing positions between forward and backward during reciprocal printing.

  An example of a printer using an ink jet printing method is shown in FIG. 3, and this example is a printer called a large-size printer that performs printing of A2 size or larger, which is particularly required for high-speed printing.

  As will be described with reference to this figure, since roll paper becomes difficult to handle with cut paper especially when it is A0 size or larger, roll paper is usually used. In the printing operation, the roll paper 301 is transported by a feed roller 302 and fed onto a platen 303. Next, a carriage 304 having an ink ejection function such as an inkjet head is perpendicular to the paper transport as indicated by an arrow. By repeating this operation, the ink corresponding to the print data is ejected while moving in the direction, and then the paper is conveyed by the width of the ink ejected by the feed roller.

  One that performs the ink ejection only in the forward direction or the backward direction is called one-way printing, and one that performs both reciprocation is called bidirectional printing. Bidirectional printing is twice as fast as unidirectional printing, but it is difficult to improve print quality because forward printing and backward printing differ in printing conditions such as ink landing positions. However, in particular, large-format printers require several minutes of printing time, and thus there has been a demand for improved printing quality in reciprocating printing.

  Therefore, conventionally, as a method of correcting the reciprocating ink landing position, an image called a registration pattern as shown in FIG. 4 is printed and corrected. Explaining this method, the pattern in FIG. 4 is a pattern by forward printing 401 to 405 and a pattern by backward printing 406 to 410, and 406 to 410 are printed by shifting the printing timing for one nozzle, respectively. is doing. According to this pattern, correction is performed by selecting a user in which the print position is matched between 401 to 405 and 406 to 410 and feeding back to the printer. Some of these are performed automatically by placing an optical sensor on the carriage.

  In particular, large-size printers have a wide range of thicknesses, from thin paper for CAD to cloth, so many printers have a function that can change the distance between the platen and the carriage. In this case, it is necessary to perform the correction again when the distance between the platen and the carriage is changed.

  In a dot line printer printing position adjustment method, for example, in Japanese Patent Laid-Open No. 8-244282, the same printing is performed in a dot line printer that performs printing by reciprocating a hammer bank having a plurality of printing hammers with respect to a printing cow by a shuttle mechanism. In some cases, the printing timing signals 1 and 2 in the forward and backward directions are moved and adjusted at the same time in order to eliminate lateral printing misalignment between the forward printing and the backward printing.

  In a reciprocating printing type serial printer, in order to eliminate the adjustment of the printing position in the forward path, for example, Japanese Patent Application Laid-Open No. 9-30047 discloses a spike near the left end of the reciprocating movement range of a wire dot printer type electric check writer. Place the sensor. The print control unit finishes the upper printing from the right end, starts the head carriage feed pulse count at the ts point SL, and stops the count when reaching the spike and the sensor. Next, when the printer head reverses the running direction and reaches the photo sensor again, the head carriage feed amount pulse count is started, and when the count number matches the number of pulses measured at the sale, the cut-off printing is started. There is a thing of the structure to do.

For example, Japanese Patent Application Laid-Open No. 10-250170 provides a controller with print timing signals in the forward and backward directions in order to reduce the displacement of the print position even when the traveling speeds of the print head in the forward direction and the bag direction are different. Some have a function of generating (PTS) uniquely and outputting it to the print head. Specifically, the PTS determined according to the traveling direction and the scheduled printing position is held in the memory, and when the traveling direction is detected, the corresponding PTS is read out, and this is detected as a relative printing position shift caused by the traveling speed difference. There is a configuration in which the print head is supplied at a timing to reduce the above.
JP-A-8-244282 JP-A-9-30047 JP-A-10-250170

  In recent years, with the increase in speed of large-sized printers and the diversification of print target media, the thickness of the media has also diversified, and the distance between the print head and the paper has been required to be variable. When the distance between the print head and the paper is changed, it is necessary to correct the print position again, and the print position correction is frequently required in order to cope with various media. For this reason, the necessity to reduce the number of times of the printing position correction as much as possible has increased.

  When the ink ejection speed is known by an apparatus having a function capable of automatically measuring and discriminating the distance between the head and the paper, it can be automatically corrected by obtaining it by calculation. If the ejection speed changes depending on the head, the above-mentioned print position correction is performed using the distance between one head sheet, and if the distance is between different head sheets, the correction value is obtained by calculation. Correction can be performed only by position correction.

  As described above, when the ink discharge speed and the distance between the head and the paper are known, the print position is corrected by pattern printing as in the prior art by performing the print position correction by the calculation of the first embodiment. May be.

  If the ink discharge speed is not yet determined, the print position correction by pattern printing is performed once at the distance between the representative head and the paper as shown in the second embodiment. The print position can be corrected.

  As a result, it is possible to quickly start printing on various print target media.

(First Embodiment of the Invention)
FIG. 1 is a diagram showing an explanation of the present invention. During printing, the ink ejection head 101 in FIG. 1 ejects ink droplets at a speed of Vi while moving at a speed of Vh. At this time, if the distance between the ink ejection head and the printing paper 102 is a, the arrival time t to the paper is
t ＝ a / Vh
Therefore, if c is the deviation from the position where the head ejected the ink droplet, c = a × Vi / Vh
It is represented by

In the case of reciprocal printing, the deviation between forward and backward printing is doubled, so the deviation g is g = 2a x Vi / Vh
For this reason, the value of the reciprocal print position adjustment may be set to the value of g obtained.

  Here, the head moving speed Vh is a value required in the apparatus design, and the ink ejection speed Vi is a value specific to the head and is usually a value that can be known in advance. In addition, the distance a between the head sheets is a value required in the design of the apparatus, and there are many apparatuses in which a can be varied by a lever or the like. However, if the lever position can be detected, it can be obtained. .

  In recent years, there is a sensor called a distance sensor that can measure optically. Even if such a sensor is used, the distance a between the head sheets can be obtained, and more accurate correction can be performed.

(Second Embodiment of the Invention)
In the first embodiment, the ink discharge speed Vi is known, but the ink discharge speed of each head may differ due to manufacturing variations depending on the head. In this case, if the second form is used, the print position correction is performed by the print pattern described in the conventional example at the distance between the representative head and the paper, and the distance between the different head and the paper is calculated using this correction value. Corrections can be made.

  A description of the second embodiment is shown in FIG. As in the first embodiment, 101 is an ink ejection head, and 102 is printing paper.

  FIG. 2A shows the state of the head, paper, and ink droplets when the print position correction is performed using the print pattern first. Here, the distance a between the head and the paper is known. The ink displacement distance c, which is the value, is half of the value obtained from the pattern, and c = g / 2 when the obtained correction value is g.

FIG. 2A depicts a state when the height of the head is changed. Here, the distance b between the head and the paper is required in the device design. Here, since the distance d by which the landing position of the ink droplet necessary for the print position correction is shifted is a ratio of a and b,
d = c × b / a
The correction value that can be obtained by the equation is double of d. If c = g / 2 is substituted, the correction value is g × b / a
Is required.

The figure explaining 1st Embodiment of invention The figure explaining the 2nd Embodiment of invention Example of printer using inkjet printing method Cash register pattern example

Explanation of symbols

101 Ink Discharge Head 102 Printing Paper Vi Ink Discharge Speed Vh Head Movement Speed and a Distance between Head and Paper

Claims (2)

In an apparatus for forming a print image on a sheet by linearly reciprocating a head for ejecting ink droplets while ejecting ink;
If the ink ejection speed, head moving speed, and head-to-paper distance are known and set to Vi, Vh, and a, respectively, the correction value for printing misalignment between forward and backward printing should be 2a x Vi / Vh. Characteristic print position correction method. In an apparatus for forming a print image on a sheet by linearly reciprocating a head for ejecting ink droplets while ejecting ink;
The moving speed of the head is known and Vh, the distance between the head and the paper is variable, the value can be detected and the value is b, and the actual printing is performed at an arbitrary distance a within the variable range of the head and the paper. When the correction value determined by the means is g, the correction value when the distance between the head and the paper is b is g × b / a.

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