JPH0243729Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet printer, and more particularly to an inkjet printer in which a print head is mounted so that the nozzle array is oblique to the direction of carriage movement.

On-demand inkjet printers have recently been in the spotlight as color printers and kanji printers because the printing device can be made smaller and the nozzle density can be easily increased. In particular, in color printers, color printing heads have been developed in which a plurality of nozzles for ejecting ink of different colors are mounted on the same printing head. For such color printing heads,
Traditionally, the nozzles were arranged perpendicular to the scanning direction of the print head, that is, the direction of movement of the carriage on which the print head was mounted.
It has become clear that the ink located on the upper side drips to the lower side, causing color mixing of the ink colors and at the same time having a very serious effect on the jetting characteristics of the ink.

The present invention was developed in view of the above, and its purpose is to provide an inkjet printer that avoids ink color mixing, stabilizes the jetting characteristics of ink particles, and facilitates printing control. It is about providing.

The feature of the present invention is that the print head is mounted so that the direction of the nozzle row is oblique to the scanning direction of the print head, and the mounting angle and the interval between each nozzle of the nozzle row are The scanning direction component of the interval is an integral multiple of the pixel pitch of the printed pixels in the scanning direction, and the component of the interval between the nozzles in the direction perpendicular to the scanning direction is the pixel pitch of the printed pixels in the perpendicular direction. It is determined that the ink droplet from each nozzle transmits an image signal to an electromechanical transducer corresponding to each nozzle of the printing head during the scanning of the printing paper while the printing head is scanning the image signal. The point is that means is provided for sequentially delaying the signals so that they are lined up in a line perpendicular to the direction.

The present invention will be explained in detail below with reference to the embodiments shown in FIGS. 1, 2, and 4, and FIG. 3.

FIG. 1 is a principle explanatory diagram showing an embodiment of the mounting state of the printing head of the inkjet printer of the present invention. In FIG. 1, 1 is a printing head, and the printing head 1 is constructed by pasting together a thin plate 3 with grooves formed by etching or the like to form a plurality of nozzles 2 and another thin plate 4. There are a plurality of ink chambers 5 shown in broken lines in the central part of the ink chamber 5, and an electromechanical transducer 6 is placed on the diaphragm portion of the thin plate 4 in a portion corresponding to each ink chamber 5.
is pasted. By the way, the print head 1 is arranged so that the nozzle row consisting of a plurality of nozzles 2 of the print head 1 forms a constant angle θ with respect to the arrow 7 indicating the scanning direction of the print head 1 (the direction of carriage movement). It is attached to the carriage.

FIG. 2 is an explanatory diagram showing an example of the relationship between nozzle arrangement specifications and pixels printed on printing paper.
The plurality of nozzles 2 are arranged in a line forming an angle θ with a line segment 8 indicating the scanning direction of the print head.
The pitch between each nozzle 2 is expressed as P _N. Note that the horizontal direction of P _N (scanning direction, that is, the horizontal direction of the printing paper)
The component is P _NX , the vertical component (in the direction perpendicular to the scanning direction, that is, the vertical direction of the printing paper, which coincides with the feeding direction of the printing paper) is P _N y , and the component in the 8-direction line segment of the printed pixel is P _x , and the component perpendicular to it is
When P _y , the pitch between each nozzle 2 is adjusted so as to satisfy the relationship P{ _N x=nPx (1) P _N y=2Py}
P _N and angle θ are determined.

Therefore, the pitch P _N between the nozzles 2 is √( _P ) ² + (2 _P ) ² for the conventional printing head in which the nozzle rows are arranged horizontally.
It's getting wider.

Fig. 3 is a principle explanatory diagram for explaining the procedure for controlling the feed of printing paper in the case of printing using the above-mentioned diagonal nozzle array, and Fig. 3a shows the movement traces of the nozzles in the fine recording mode. ing. Among the plurality of nozzles 2, the same ink is supplied to each of the m nozzles 2, and FIG. 3A shows the case where m=2. This print head has eight nozzles ₂₁ to ₂₈ , and yellow (Y), magenta (M), cyan (C), and black (BK) inks are supplied to each of them in order from the top. It is assumed that The nozzle array is scanned back and forth in the horizontal direction, and the vertical pitch P _N y between each nozzle 2 ₁ to 2 ₈ is twice the vertical pitch P _y of the pixels. The solid line 11 shows the movement of the printing head, which is representatively shown by the movement of the top nozzle ₂₁ . Also,
A broken line 12 indicates the movement of the second nozzle 2 ₂ from the top. The print head moves from left to right in the diagram to print the first yellow pixel line 11 with nozzle 2 ₁ .
a is printed, and at the same time, a third yellow pixel line 12a is printed by the nozzle ₂₂ . The same applies to the nozzles 2 ₃ to 2 ₈ below. When the print head reaches the right edge of the diagram, the printing paper is advanced by one pixel, and the print head now moves from the right to the left of the diagram until the second yellow pixel is picked up by nozzle ₂₁ . Line 11b is printed, and nozzle 2 ₂ prints line 12b of the fourth pixel in yellow. The same applies to the nozzles 2 ₃ to 2 ₈ below. As a result, the nozzles 2 ₁ and 2 ₂ also print lines for 4 pixels in yellow, and similarly, lines for 4 pixels in other colors are printed.

Next, when the paper is fed by three pixels, the yellow nozzles 2 ₁ and 2 ₂ reach positions corresponding to the macenda color (M) pixel lines, respectively. Here, also
Printing proceeds by moving the print head to the right, then feeding the paper by one pixel, moving the print head to the left, and then feeding the paper by three pixels. If you need a red pixel line, first print a magenta pixel line, then feed the paper and when the yellow nozzle comes over that pixel line, Yellow ink is ejected from the nozzle and overlapped to create a line of red pixels.

When fine printing is performed in this manner, and four color inks are supplied to every two nozzles, the image is formed by feeding the paper in the order of 1→3→1→3, etc. in units of image line pitches. Generally, when m nozzles of the same color are mounted, the image pitch unit is 1→(2m−1).
→1→(2m-1)...The paper is fed to form an image.

FIG. 3b shows the movement trace of the nozzle when forming an image in high speed mode. In the high-speed mode, the printing density, especially the vertical pixel pitch, is skipped coarsely and printed at high speed. 4 in the first scan
Two lines of color, a total of 8 pixel lines are printed, but when the print head returns, the paper is fed by 4 pixels, and when the print head returns, the yellow nozzle 2 ₁ ,
2 ₂ prints on the magenta pixel line, and magenta nozzles 2 ₃ and 2 ₄ print on the cyan pixel line, and so on. Therefore, in the fine recording mode, the number of pixels in the vertical direction is such that the printed pixel lines 11b and 12b are omitted, resulting in a coarse image of every other pixel, but in the fine screen, Prints at twice the printing speed. Generally, when m nozzles of the same color are mounted, the image pitch unit is 2m → 2m → 2m...
and feed the paper to form an image.

FIG. 4 is a block diagram showing one embodiment of the control electric circuit for the inkjet printer of the present invention. In FIG. 4, 16 is a display tube, and 17 is a central processing unit (CPU) of the computer. . On the other hand, the above four signals pass through a serial-to-parallel converter 22 and are stored in an image memory 23 installed inside or outside the printer. A clock pulse (PCL) 24 representing the position of the print head of the printer is input to the image memory 23, and information can be retrieved from a predetermined address in the image memory 23 corresponding to the clock pulse 24. The output signals 25 ₁ , 25 ₂ , _.
27 ₂ ,..., 27n', and amplifiers 27 ₁ to 27
The outputs of n' are applied to respective electromechanical transducer elements 6 ₁ , 6 ₂ , . . . , 6n' of the print head.

As is clear from the above explanation, the n' nozzles 2 corresponding to the electromechanical transducers 6 ₁ to 6n' are arranged every n dots in the scanning direction of the print head as shown in equation (1). Therefore, in order for the ink droplets emitted from each nozzle 2 to line up in a line in the vertical direction (paper feeding direction) on the printing paper, the output signal 25 ₂ is n smaller than the output signal 25 ₁ .
It is necessary to delay the signal by the amount of the dot. Therefore, one n-pulse delay element 25 ₂₁ is installed on the signal line for the output signal 25 ₂ , and for the same reason, two n-pulse delay elements 25 ₃₁ are installed on the signal line for the output signal 25 ₃ . (n'-1) n-pulse delay elements 25n' are connected to each signal line for the output signal 25n'.

Note that the above explanation is for when the print head moves from left to right, but if the print head moves from right to left, the above delay relationship needs to be reversed. . Therefore, when moving the print head from right to left, among the left scan output signals 28 ₁ , 28 ₂ , ..., 28n', the output signal 28n' is outputted earliest, ,…
. . , 28 ₂ , 28 ₁ , the number of n pulse delay circuit elements is increased one by one, and the delay is sequentially delayed by n dots.

The switch 26 is controlled in response to left-to-right scanning and right-to-left scanning of the print head, and is controlled so that it can be applied to the appropriate print head.

The present invention is characterized in that the pitch P _N between each nozzle 2 of the print head is set to be n times P _X in the scanning direction. The n-pulse delay element only needs to be digitally delayed by n pulses, and can be configured with a latch circuit or the like, resulting in an extremely simple circuit configuration.

Also, with recent technology, it goes without saying that microcomputers are involved in these controls.

As described above, according to the embodiment of the present invention, the print head is installed so that the nozzle array is diagonal to the direction of travel, and each nozzle is spaced sufficiently apart, so that color printing is possible. In this case, the probability that adjacent colors will be mixed and printed can be greatly reduced. Furthermore, the probability that ink accumulates around the nozzle 2 and that the accumulated ink adversely affects ink particles ejected from nozzles adjacent to the nozzle can be extremely reduced. In addition, since the vertical pitch P _N y between each nozzle 2 is set as an integral multiple of the vertical pixel pitch P _y , you can select a mode in which printing is performed in fine pixel units as needed, and the vertical pixel is printed every other pixel. The inkjet printer can be used by switching to a high-speed printing mode, thereby increasing the applicability of the inkjet printer. In addition, since the horizontal pixel pitch P _N x between each nozzle 2 is an integral multiple of the horizontal pixel pitch P _x , when information is read from the image memory 23 and electrical signals are added to the electromechanical transducer 6 for printing. can be controlled using only digital delays, making the control circuit extremely simple.

In the above-mentioned embodiment, the image signal is delayed by hardware, but in keeping with the spirit of the present invention, the delay is not limited to hardware, but may be delayed by software. Needless to say, this is a good thing.

Furthermore, although the above-described embodiments have been described as color printers, the present invention is not limited to color printers, and sufficient effects can be obtained even in monochromatic printing. That is,
In monochromatic printing, there is no problem of color mixing of color inks, but if ink accumulates on the end face of nozzle 2, this ink accumulation may affect the ejection of adjacent ink below. Needless to say, this can be significantly reduced by arranging it obliquely to the direction.

As described above, the present invention has the advantage of avoiding color mixing of inks, stabilizing the jetting characteristics of ink particles, and facilitating printing control.

[Brief explanation of the drawing]

Fig. 1 is a principle explanatory diagram showing an embodiment of the installation state of the print head of the inkjet printer of the present invention, and Fig. 2 shows an embodiment of the relationship between nozzle arrangement specifications and pixels printed on printing paper. Explanatory diagram showing, 3rd
The figure is a principle explanatory diagram for explaining the procedure for controlling the feeding of printing paper in the case of printing using an oblique nozzle array.
The figure is a block diagram showing one embodiment of the control electric circuit for the inkjet printer of the present invention. 1... Printing head, 2 _{, 21} to ₂₈ ... Nozzle,
6,6 ₁ to 6n'...electromechanical conversion element, 17...
CPU, 22...Serial-parallel converter, 2
3... Image memory, 25 ₂₁ , 25 ₃₁ ,..., 25n' ₁
...n pulse delay element, 26...switch, 27
₁ to 27n'...Amplifier.

Claims (1)

[Claims for Utility Model Registration] A printing head having a nozzle row consisting of a plurality of nozzles arranged in a straight line is reciprocated and scanned along the width direction of the printing paper, and in the process of reciprocating scanning, the nozzles are An inkjet printer that prints by jetting ink particles, wherein the print head is installed so that the direction of the nozzle row is oblique to the scanning direction of the print head, and the print head scan direction between each nozzle is and the interval along the direction perpendicular to the scanning direction are respectively an integral multiple of the pixel pitch of the printed pixels in the scanning direction and twice the pixel pitch of the printed pixels in the direction perpendicular to the scanning direction. When performing high-definition printing by setting the interval and the mounting angle of the print head, and arranging the nozzles so that ink particles of the same color are ejected every m adjacent nozzles (m is an integer of 2 or more). The minimum pixel pitch that can be printed is 1 and (2m-
1) An inkjet printer characterized in that it is equipped with a paper feeding means that alternately feeds the paper and feeds the paper 2 m when high-speed printing is performed.