JP4055361B2 - Printing using a print head with a staggered arrangement - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for printing an image on a print medium while performing main scanning.
[0002]
[Prior art]
In recent years, color jet printers that eject ink droplets from a head have become widespread as output devices for computers. For color ink jet printers, there have been two demands for high image quality and high speed for many years, and various technologies have been developed to pursue these demands.
[0003]
[Problems to be solved by the invention]
High image quality can be achieved, for example, by increasing the number of ink colors. However, when the number of ink colors is increased, the number of nozzle rows provided in the print head increases, so the size of the print head increases. As a result, there arises a problem that the size of the entire printing apparatus increases. For this reason, there has been a demand for a technique that can keep the print head size small even when the total number of nozzles increases. In addition, a technique for performing high-speed and high-quality printing using such a print head has been desired.
[0004]
The present invention has been made to solve the above-described conventional problems, and provides a technique capable of achieving high-speed printing and high image quality using a print head with a small size. With the goal.
[0005]
[Means for solving the problems and their functions and effects]
In order to achieve at least a part of the above object, a printing apparatus according to the present invention is a printing apparatus that prints an image on a printing medium while performing main scanning, the printing head having a plurality of nozzle arrays, and the printing A main scanning drive mechanism that performs main scanning by moving at least one of a head and the printing medium; and a sub-scanning driving mechanism that performs sub-scanning by moving at least one of the print head and the printing medium; A print data memory for storing print data and a control unit for controlling the operation of the printing apparatus are provided. In the print head, (1) each nozzle row has a plurality of nozzles arranged along the sub-scanning direction and ejecting the same ink, (2) The light cyan nozzle row and the light magenta nozzle row are arranged in a staggered manner, and the dark cyan nozzle row and the dark magenta nozzle row are also arranged in a staggered manner, respectively. (3) The dark cyan nozzle row and the dark cyan nozzle row A pair of ink passages for the magenta nozzle row is formed in a staggered pattern in the first ink passage formation body, and a pair of ink passages for the light cyan nozzle row and the light magenta nozzle row is the first ink passage. Are formed in a staggered pattern on the second ink passage forming body different from the ink passage forming body of (4) The staggered nozzle pair is composed of a preceding nozzle row that reaches the leading edge of the print medium relatively early and a subsequent nozzle row that arrives relatively late when the sub-scan is performed. Further, the control unit (a) records a plurality of main scan lines in which each nozzle row is separated from each other in one main scan, and performs a plurality of main scans including at least one sub-scan feed. (B) In the interlace recording, the full width in the sub-scanning direction of the nozzle row pairs arranged in a staggered manner before one main scan is performed. The print data corresponding to a plurality of main scan lines is referred to from the print data memory, and the one main scan is executed in accordance with the referred print data.
[0006]
In such a printing apparatus, since at least a pair of nozzle rows that discharge different inks are arranged in a staggered manner, the interval between the pair of nozzle rows can be made smaller than in a case where they are not arranged in a staggered manner. it can. As a result, it is possible to reduce the size of the print head. Further, print data for a plurality of main scanning lines corresponding to the full width in the sub-scanning direction of the nozzle row pairs arranged in a staggered pattern before one main scanning is referred to from the print data memory. If necessary, printing can be performed using all the nozzles of the nozzle row pair in one main scan. As a result, it is possible to increase the printing speed.
[0007]
In the interlace recording, the control unit further records different nozzle numbers without recording the same main scanning line between the nozzles of the same nozzle number in the nozzle array pair arranged in a staggered manner. The sub-scan feed may be performed so that the same main scan line is recorded between the nozzles.
[0008]
With this configuration, the print image quality can be improved. In interlaced recording using a pair of nozzle rows arranged in a staggered manner, the same main scanning line can be recorded by nozzles having the same nozzle number only in a few recording methods. However, if the same main scanning line is recorded by nozzles having different nozzle numbers, it is possible to select a recording method with good image quality from among a large number of recording methods. Therefore, high-quality printing can be performed using a print head with a small size.
[0009]
(D) In the interlace recording, the control unit further performs printing according to a first recording method in an intermediate portion of the recording execution area on the printing medium, and near the leading end of the recording execution area. Printing is performed in accordance with a second recording method having a smaller sub-scan feed amount than that of the recording method, and (e) sub-scanning in which the preceding nozzle row can record in printing in the vicinity of the leading edge according to the second recording method. You may make it determine the front-end | tip of the said recording execution area | region according to the range of a direction.
[0010]
With this configuration, it is possible to easily determine the leading edge of the recording execution area in the vicinity of the leading edge of the print medium while reducing the number of useless main scans as much as possible.
[0011]
(F) In the interlaced recording, the control unit further performs printing according to a third recording method in which the sub-scan feed amount is smaller in the vicinity of the rear end of the recording execution area than the first recording method in the intermediate portion. (G) In printing in the vicinity of the trailing edge in the third printing method, the trailing edge of the printing execution area is determined in accordance with the range in the sub-scanning direction in which the trailing nozzle row can be printed. It may be.
[0012]
With this configuration, it is possible to easily determine the trailing edge of the recording execution area in the vicinity of the trailing edge of the print medium while reducing the number of useless main scans as much as possible.
[0013]
It is further assumed that the control unit further performs (h) sub-scan feed according to the second recording method when shifting from printing by the second recording method to printing by the third recording method. Sometimes, when the nozzle at the front end of the preceding nozzle row exceeds the scheduled rear end of the recording execution area, the printing by the second recording method is shifted to the printing by the third recording method. Good.
[0014]
According to this configuration, it is possible to shift from the second recording method to the third recording method while reducing the number of useless main scans as much as possible.
[0015]
The staggered nozzle row pairs are connected to a pair of ink passages for supplying ink to the nozzle row pairs, and the pair of ink passages is a single ink passage forming body. It is preferable that it is provided in the inside.
[0016]
If a pair of ink passages are provided in one ink passage formation body, a pair of nozzle rows arranged in a staggered manner can be densely arranged. Therefore, the size of the print head can be further reduced.
[0017]
The pair of ink passages may be formed so as to protrude so that the passage portions in the vicinity of the nozzles face each other.
[0018]
In this configuration, since the interval between the pair of ink passages can be narrowed by taking a staggered arrangement, the size of the print head can be further reduced.
[0019]
Moreover, it is preferable that more than half of the plurality of nozzle rows is configured as a pair of nozzle rows arranged in a staggered manner.
[0020]
According to this configuration, since more than half of the nozzle rows are arranged in a staggered manner, the size of the print head can be further reduced.
[0021]
The plurality of nozzle arrays include four basic color nozzle arrays for ejecting four basic color inks of black, cyan, magenta, and yellow, respectively. The four basic color nozzle arrays are related to the sub-scanning direction. May be arranged at the same position.
[0022]
With such a configuration, it is possible to improve the image quality because the ejection order of the basic color inks can be made constant during unidirectional printing.
[0023]
Note that the present invention can be realized in various modes, for example, in a mode such as a printing apparatus or a print head.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment of the print head:
B. Second embodiment of the print head:
C. Third embodiment of the print head:
D. Example of printing operation:
E. Variation:
[0025]
A. First embodiment:
FIG. 1 is a schematic configuration diagram of a printing system including an inkjet printer 20 as a first embodiment of the present invention. The printer 20 includes a sub-scan feed mechanism that transports the printing paper P in the sub-scan direction by the paper feed motor 22 and a main scan feed that reciprocates the carriage 30 in the axial direction (main scan direction) of the platen 26 by the carriage motor 24. A mechanism, a head drive mechanism that drives a print head unit 60 mounted on the carriage 30 to control ink ejection and dot formation, and these paper feed motor 22, carriage motor 24, print head unit 60, and operation panel 32 And a control circuit 40 that controls the exchange of signals with the. The control circuit 40 is connected to the computer 88 via the connector 56.
[0026]
The sub-scan feed mechanism that transports the printing paper P includes a gear train (not shown) that transmits the rotation of the paper feed motor 22 to the platen 26 and a paper transport roller (not shown). Further, the main scanning feed mechanism for reciprocating the carriage 30 has an endless drive belt 36 between the carriage motor 24 and a slide shaft 34 that is installed in parallel with the axis of the platen 26 and slidably holds the carriage 30. And a position sensor 39 for detecting the origin position of the carriage 30.
[0027]
FIG. 2 is a block diagram showing a circuit configuration of the printer 20 with the control circuit 40 as the center. The control circuit 40 is configured as an arithmetic and logic circuit including a CPU 41, a programmable ROM (PROM) 43, a RAM 44, and a character generator (CG) 45 that stores a dot matrix of characters. The control circuit 40 further includes an I / F dedicated circuit 50 dedicated to interface with an external motor and the like, and a head that is connected to the I / F dedicated circuit 50 and drives the print head unit 60 to eject ink. A drive circuit 52 and a motor drive circuit 54 for driving the paper feed motor 22 and the carriage motor 24 are provided. The I / F dedicated circuit 50 incorporates a parallel interface circuit and can receive a print signal PS supplied from the computer 88 via the connector 56. A print head 28 is provided at the bottom of the print head unit 60.
[0028]
FIG. 3 is an explanatory diagram showing a main part of the print head 28. When the ink cartridge is attached to the print head unit 60, the ink in the ink cartridge is guided to the print head 28 via the introduction pipes 71 to 76.
[0029]
The print head 28 includes a plurality of nozzles n provided in a row for each ink color, and an actuator circuit 90 that operates the piezoelectric element PE provided in each nozzle n. The actuator circuit 90 is a part of the head drive circuit 52 (FIG. 2), and controls on / off of a drive signal supplied from a drive signal generation circuit (not shown) in the head drive circuit 52. That is, the actuator circuit 90 latches data indicating ON (discharges ink) or OFF (does not discharge ink) for each nozzle in accordance with the print signal PS supplied from the computer 88, and drives only the ON nozzle. A signal is applied to the piezo element PE.
[0030]
FIG. 4 is an explanatory diagram showing the driving principle of the nozzle n by the piezo element PE. The piezo element PE is installed at a position in contact with the ink passage 80 that guides ink to the nozzle n. In this embodiment, by applying a voltage having a predetermined time width between the electrodes provided at both ends of the piezo element PE, the piezo element PE rapidly expands as shown in FIG. The one side wall is deformed. As a result, the volume of the ink passage 80 contracts according to the expansion of the piezo element PE, and the ink corresponding to the contraction becomes particles Ip and is ejected from the tip of the nozzle n at high speed. Printing is performed by the ink particles Ip soaking into the paper P mounted on the platen 26.
[0031]
FIG. 5 is an explanatory diagram showing an arrangement of the plurality of nozzle rows provided on the bottom surface of the print head 28 as viewed from above. The print head 28 includes six nozzle arrays for ink of six colors of yellow (Y), dark magenta (M), light magenta (LM), light cyan (LC), dark cyan (C), and black (K). Are arranged in order along the main scanning direction. The broken line in the figure is an imaginary line for indicating the section of the nozzle row. Note that dark cyan and light cyan are cyan inks having substantially the same hue and different densities. The same applies to dark magenta and light magenta.
[0032]
In the present specification, the four inks C, M, Y, and K other than the light ink are referred to as “four basic color inks”. More specifically, “four basic color inks” means cyan ink, magenta ink, and yellow ink that can reproduce black by mixing almost equal amounts, and black ink that is not gray. ing. In the present specification, the four nozzle rows Y, M, C, and K for ejecting these four basic color inks are referred to as “basic color nozzle rows”.
[0033]
The actuator circuit 90 is provided with first to third actuator chips 91 to 93. In the first actuator chip 91, a yellow nozzle row Y and a dark magenta nozzle row M are arranged. In the second actuator chip 92, a light magenta nozzle array LM and a light cyan nozzle array LC are arranged. A dark cyan nozzle row C and a black nozzle row K are arranged on the third actuator chip 93.
[0034]
A pair of nozzle rows on one actuator chip are arranged in a staggered manner. Further, the nozzle row for one color is arranged at a constant nozzle pitch k along the sub-scanning direction (paper feeding method). In this example, the nozzle pitch k is a value corresponding to a printing resolution of 180 dpi (that is, about 141 μm). The nozzle rows arranged in a staggered pattern are shifted from each other in the sub-scanning direction by 1/2 of the nozzle pitch k. The advantages of such a staggered arrangement will be described later.
[0035]
FIG. 6 is an exploded perspective view of the actuator circuit 90. The three actuator chips 91 to 93 are adhered to the laminated body of the nozzle plate 110 and the reservoir plate 112 with an adhesive. Further, the connection terminal plate 120 is fixed on the actuator chips 91 to 93. At one end of the connection terminal plate 120, an external connection terminal 124 for electrical connection with an external circuit (specifically, the I / F dedicated circuit 50 in FIG. 2) is formed. In addition, an internal connection terminal 122 for electrical connection with the actuator chips 91 to 93 is provided on the lower surface of the connection terminal plate 120. Further, a driver IC 126 is provided on the connection terminal plate 120. In the driver IC 126, a circuit for latching a print signal given from the computer 88, an analog switch for turning on / off a drive signal in accordance with the print signal, and the like are provided. The wiring between the driver IC 126 and the connection terminals 122 and 124 is not shown.
[0036]
FIG. 7 is a partial cross-sectional view of the actuator circuit 90. Here, only the cross section of the first actuator chip 91 and the connection terminal plate 120 on the first actuator chip 91 is shown, but the other actuator chips 92 and 93 have the same structure as the first actuator chip 91.
[0037]
In the nozzle plate 110, nozzle openings for each ink are formed. The reservoir plate 112 is a plate-like body for forming an ink storage part (reservoir). The actuator chip 91 includes a ceramic sintered body 130 that forms the ink passage 80 (FIG. 4), a piezoelectric element PE disposed above the ceramic passage 130 via a wall surface, and a terminal electrode 132. When the connection terminal plate 120 is fixed on the actuator chip 91, the connection terminal 122 provided on the lower surface of the connection terminal plate 120 and the terminal electrode 132 provided on the upper surface of the actuator chip 91 are electrically connected. Is done. The wiring between the terminal electrode 132 and the piezo element PE is not shown.
[0038]
As can be understood from the above description, a pair of nozzle rows on one actuator chip 91 is simultaneously manufactured as a unit by bonding the nozzle plate 110, the reservoir plate 112, and the ceramic sintered body 130 together. . Therefore, the accuracy of the mutual positional relationship is improved as compared with the case where the pair of nozzle rows are arranged on different actuator chips. The ceramic sintered body 130 forms an ink passage 80 for a pair of nozzle rows, and therefore can be referred to as an “ink passage forming body”.
[0039]
FIG. 8 is an explanatory diagram showing the arrangement of the ink passages in the print head 28 of the first embodiment. The first actuator chip 91 is provided with an ink passage 80a for the yellow nozzle row Y and an ink passage 80b for the dark magenta nozzle row M. The same applies to the other actuator chips 92 and 93. The pair of ink passages 80a and 80b are formed so as to protrude so that the passage portions in the vicinity of the respective nozzles face each other. That is, the ink passage 80a for the yellow nozzle row has a shape in which an ink passage portion in the vicinity of the yellow nozzle protrudes toward the dark magenta nozzle row. Similarly, the ink passage 80b for the dark magenta nozzle row has a shape in which an ink passage portion in the vicinity of the dark magenta nozzle protrudes toward the yellow nozzle row side. Such a pair of ink passages 80a and 80b is formed in the ceramic sintered body 130 (FIG. 7).
[0040]
Thus, the two ink passages 80a and 80b of one actuator chip are formed so as to face each other. However, since the nozzle rows are arranged in a staggered manner, a large gap g (FIG. 8) between the ink passages can be secured. The gap g is required to be secured to a certain value or more due to the strength of the actuator chip and manufacturing requirements. If the pair of nozzle rows are arranged in a staggered pattern, there is an advantage that the required value of the gap g can be easily satisfied.
[0041]
However, when the same ink is ejected from a pair of nozzle rows, it may be desired to connect the ink passages 80a and 80b by narrowing the gap g. However, when different inks are ejected from a pair of nozzle rows as in this embodiment, it is necessary to isolate the ink passages 80a and 80b from each other, and therefore it is preferable to ensure the gap g at a sufficiently large value. .
[0042]
FIG. 9 is an explanatory diagram showing the arrangement of ink passages in the print head 280 of the comparative example. The print head 280 has three actuator chips 901 to 903, and a pair of nozzle rows is arranged on each actuator chip. This comparative example is different from the first embodiment shown in FIG. 8 in that the pair of nozzle rows on each actuator chip are not arranged in a staggered manner and are arranged at the same position in the sub-scanning direction. ing.
[0043]
In the print head 280 of the comparative example, since the pair of nozzle rows are not arranged in a staggered manner, in order to ensure the gap g between the ink passages above a certain value, the first embodiment shown in FIG. In comparison, it is necessary to increase the distance between the nozzle rows. Therefore, the width W280 of the print head 280 of the comparative example in the main scanning direction is considerably larger than the width W28 of the print head 28 of the first embodiment shown in FIG.
[0044]
As can be understood from the above description, in the first embodiment, since the pairs of nozzle rows are arranged in a staggered manner, the interval between the nozzle row pairs can be made narrower than in the comparative example. As a result, the width of the print head 28 in the main scanning direction can be reduced. Such an advantage becomes more remarkable as the number of nozzle rows increases.
[0045]
B. Second embodiment:
FIG. 10 is an explanatory diagram showing an arrangement of the plurality of nozzle rows provided on the bottom surface of the print head according to the second embodiment of the present invention as viewed from above. The print head 28a is provided with four actuator chips 91a, 92a, 93a, 94. The first three actuator chips 91a, 92a, 93a have two nozzle rows arranged in a staggered manner, as in the first embodiment shown in FIG. The fourth actuator chip 94 has only one nozzle row.
[0046]
A dark yellow nozzle row DY and a yellow nozzle row Y are arranged on the first actuator chip 91a. In the second actuator chip 92, a light magenta nozzle array LM and a light cyan nozzle array LC are arranged. In the third actuator chip 93, a dark magenta nozzle row M and a dark cyan nozzle row C are arranged. A black nozzle row K is arranged on the fourth actuator chip 94.
[0047]
Dark yellow (DY) is ink in which yellow ink is mixed with color materials for other inks (for example, dark cyan and dark magenta). When using dark yellow ink containing a dark cyan component and a dark magenta component, the amount of ink (especially the amount of solvent) ejected onto the print medium compared to when yellow, dark cyan, and dark magenta ink droplets are ejected separately. ) Is less.
[0048]
In the three nozzle rows DY, LM, and M, the end nozzles reach the leading edge of the printing paper earlier than the other four nozzle rows Y, LC, C, and K. Therefore, in the following, the nozzle rows DY, LM, M in which the end nozzles reach the front end of the printing paper earlier are referred to as “preceding nozzle rows”. In addition, the nozzle rows Y, LC, C, and K in which the nozzles at the end reach later than the leading edge of the printing paper are referred to as “following nozzle rows”.
[0049]
The print head 28a of the second embodiment also has three nozzle row pairs arranged in a staggered manner. Therefore, there is an advantage that the width of the print head in the main scanning direction can be kept small.
[0050]
The light cyan nozzle row LC and the light magenta nozzle row LM are arranged in a staggered manner, and this has the following advantages. That is, since light cyan ink and light magenta ink are ejected on different main scanning lines in one main scanning, the time interval until both are ejected to the same pixel position is smaller than that in the comparative example (FIG. 9). become longer. As a result, the previously ejected ink is easy to dry, and color reproduction can be stabilized. Further, the staggered arrangement of the light ink nozzle arrays LC and LM has the following advantages.
[0051]
FIG. 11A shows a pair of nozzle rows LC and LM arranged in a staggered manner, and FIG. 11B shows the equivalent nozzle rows. The pair of nozzle rows provided in the actuator chip 92a is composed of a light cyan nozzle row LC and a light magenta nozzle row LM. The light cyan nozzle row LC has seven nozzles LC1 to LC7. The light magenta nozzle row LM also includes seven nozzle rows LM1 to LM7. Numbers 1 to 7 after the letters LC and LM given to each nozzle indicate nozzle numbers counted from the rear end of the print head. That is, the nozzles LC1 and LM1 are the nozzles located at the most rear end, and the nozzles LC7 and LM7 are the nozzles located at the most tip.
[0052]
The equivalent nozzle row shown in FIG. 11B is an equivalent nozzle that can record a plurality of main scan lines that can be recorded by one main scan by the pair of nozzle rows LC and LM in the same main scan. Shows the column. In other words, printing performed using the pair of nozzle arrays LC and LM is substantially equivalent to printing performed using this one equivalent nozzle array.
[0053]
FIG. 12 is an explanatory diagram showing an example of bidirectional printing using the print head 28a of the second embodiment using an equivalent nozzle array. The characters “pass 1” and “pass 2” described above the equivalent nozzle row indicate the main scanning number. That is, “pass 1” is the first main scan, and “pass 2” is the second main scan. In the recording method shown in FIG. 12, every time one main scan is performed, sub-scan feed is executed with a constant feed amount L (= 7 dots). Here, the unit [dot] of the sub-scan feed amount L means a dot pitch (that is, a main scan line pitch) corresponding to the print resolution in the sub-scan direction. The nozzle pitch k in the same nozzle row is 180 dpi, and this nozzle pitch k corresponds to four main scanning lines (also called raster lines). Accordingly, the print resolution in the sub-scanning direction in the example of FIG. 12 is 720 dpi.
[0054]
A white arrow written on the right side of each pass number indicates whether printing (ink ejection) is performed in the forward path or printing is performed in the backward path. That is, printing is performed in the forward path in the odd-numbered pass, and printing is performed in the backward path in the even-numbered pass.
[0055]
In the lower right of FIG. 12, the ink ejection order in each main scanning line of each band is shown. Here, the “band” means a region (print front end region) where ink is first ejected at the front end portion of the nozzle row in one main scan after the sub-scan feed is performed. The symbol “B1-1” means the first main scanning line of the band 1, and “B1-2” means the second main scanning line of the band 1. Similarly, “B2-1” means the first main scanning line of band 2.
[0056]
Two columns are provided on the right side of the main scanning line of each band. The first column indicates in which order the light inks LC and LM are ejected in the main scan line to be recorded in the first main scan in each band. For example, the four main scan lines B1-1, B1-3, B1-5, and B1-7 are to be recorded in the first main scan (that is, pass 2) executed in the band 1. Among these, the light cyan ink LC is first ejected on the two main scanning lines B1-1 and B1-5, and the light magenta ink LM is ejected in the subsequent pass (specifically, pass 4). Is done. On the other hand, on the other two main scanning lines B1-3 and B1-7, on the contrary, the light magenta ink LM is first ejected, and then the light cyan ink LC is ejected in the subsequent pass 4. The The second column indicates in which order the light inks LC and LM are ejected in the main scanning line which is not a recording target in the first main scanning of each band.
[0057]
Such a discharge order is common to band 1 and band 2. In other words, in the example of FIG. 12, it can be understood that a constant order is maintained with respect to the ink ejection order in each band (print leading edge region).
[0058]
FIG. 13 shows an example of bidirectional printing using the print head 280 of the comparative example shown in FIG. The sub-scan feed amount L is the same as that shown in FIG. The lower right part of FIG. 13 also shows the ink ejection order in each main scanning line of each band, as in FIG. However, in the main scanning line labeled “LC *” in the first column, the light cyan ink LC is ejected before the light magenta ink LM on the adjacent main scanning line. It means that you are affected by the bleeding. On the other hand, the symbol “LM *” means that it is affected by the bleeding of the light magenta ink LM previously ejected on the adjacent main scanning line.
[0059]
Here, “influence of ink bleeding” means the following phenomenon. In a normal ink jet printer, the line width recorded by one scan is thicker than the theoretical width determined by the printing resolution. As a result, since the lines adjacent to each other are recorded so as to overlap each other, it is possible to prevent solid white stripes (which may occur due to the characteristics of the print head and the sub-scan feed accuracy of the print medium). In color printing, color reproducibility (appearance color) varies depending on the ink ejection order and different ink ejection intervals (that is, the drying time of the previously ejected ink). In particular, the ink that is first ejected in a region where no ink is ejected tends to greatly affect the color in the adjacent main scan line.
[0060]
In band 1 in FIG. 13, the light magenta ink LM first ejected on the main scanning lines B1-3 and B1-7 may bleed to the surroundings and may significantly affect the color of the adjacent main scanning lines. is there. In band 2, the light cyan ink LC first ejected on the main scanning lines B2-3 and B2-7 oozes out to the surroundings, and there is a possibility of significantly affecting the color of the adjacent main scanning lines. . As a result, there arises a problem that the apparent color (that is, color reproduction) is considerably different between the band 1 and the band 2.
[0061]
On the other hand, in the example of FIG. 12, unlike the case of FIG. 13, since a constant order is maintained in the ejection order of ink in each band, the phenomenon that the influence of ink bleeding differs for each band does not occur. That is, by arranging the light ink nozzle arrays LC and LM in a staggered manner, it is possible to stabilize color reproduction in each band (print leading edge region). As a result, there is an advantage that the image quality can be improved.
[0062]
In the example of FIG. 12, sub-scan feed (referred to as “regular feed”) in which the feed amount L is constant is adopted, but sub-scan feed (“regular feed”) using a plurality of different feed amounts. It is also possible to adopt. However, when the sub-scan feed amount L is constant, the above-described effects described with reference to FIGS. 12 and 13 are particularly remarkable.
[0063]
The above-described advantages of the staggered arrangement of the light ink nozzle arrays LC and LM are similarly achieved by the staggered arrangement of the dark ink nozzle arrays C and M. That is, since a large amount of light ink is ejected in an image region having a relatively low image density, the advantage of the staggered arrangement of light inks is great. Further, since a large amount of dark ink is ejected in an image region having a relatively high image density, the advantage of the staggered arrangement of dark ink is great.
[0064]
The advantages of the staggered arrangement described above can also be achieved by arrangements other than the staggered arrangement. For example, even if the light cyan nozzle row LC and the light magenta nozzle row LM are not adjacent, the nozzle rows LC and LM have the same positional relationship as the nozzle row pairs arranged in a staggered manner with respect to the position in the sub-scanning direction. If arranged so as to take, effects similar to those described above can be achieved.
[0065]
C. Third embodiment:
FIG. 14 is an explanatory diagram showing a plurality of nozzle rows provided on the bottom surface of the print head in the third embodiment of the present invention. The print head 28b is provided with three actuator chips 91b, 92b, 93b. The first two actuator chips 91b and 92b are similar to those of the first embodiment shown in FIG. 5, except that the preceding nozzle row and the following nozzle row are reversed. That is, in the actuator chips 91b and 92b of the third embodiment, the dark magenta nozzle row M and the light cyan nozzle row LC are the preceding nozzle rows, and the yellow nozzle row Y and the light magenta nozzle row LM are the succeeding nozzle rows. . In the third actuator chip 93b, the dark cyan nozzle row C and the black nozzle row K are not arranged in a staggered manner, but are arranged at the same position in the sub-scanning direction. The dark cyan nozzle row C and the black nozzle row K are also subsequent nozzle rows.
[0066]
In the print head 28b of the third embodiment, the light ink nozzle arrays LC and LM are arranged in a staggered manner as in the second embodiment. Further, the dark cyan nozzle row C and the dark magenta nozzle row M are not arranged in a staggered manner, but their positions in the sub-scanning direction are shifted from each other. Accordingly, as in the second embodiment, there is an advantage that the image quality is improved.
[0067]
The width of the print head 28b of the third embodiment in the main scanning direction is slightly larger than the print head 28 of the first embodiment, but is considerably smaller than the print head 280 of the comparative example shown in FIG. Therefore, also in the third embodiment, the width of the print head in the main scanning direction can be reduced as compared with the prior art.
[0068]
As can be understood from the second and third embodiments described above, in the present invention, it is not necessary that all nozzle rows in the print head form a staggered arrangement, and at least a pair of nozzles that eject different inks. It suffices if the columns form a staggered arrangement. However, the more nozzle rows that form a staggered arrangement, the smaller the width of the print head in the main scanning direction. In this sense, it is preferable that more than half of the nozzle rows form a staggered arrangement. Furthermore, it is most preferable that as many nozzle rows as possible be arranged in a staggered manner so that the number of nozzle rows that do not constitute the staggered arrangement is 0 or 1.
[0069]
D. Example of printing operation:
FIG. 15 is an explanatory diagram showing the concept of applying a recording method on printing paper. A print execution area PA where printing is actually executed is set on the printing paper P. A recording method with a relatively large sub-scan feed amount is applied to the central area of the print execution area PA. On the other hand, a recording method with a relatively small sub-scan feed amount is applied in the vicinity of the upper end and the lower end of the print execution area PA. “Recording method” and “printing method” are synonymous.
[0070]
In this specification, printing processing in the vicinity of the upper end of the printing paper is referred to as “upper end processing”, and printing processing in the vicinity of the lower end of the printing paper is referred to as “lower end processing”. Also, the printing process in these intermediate areas is called “intermediate area processing”. In the upper end process and the lower end process, a recording method using a value in which the sub-scan feed amount is smaller than that in the intermediate region process is applied, and thereby the print execution area PA is expanded. This point will be further described later. When performing borderless printing without margins, the print execution area PA is set to be an area wider than the printing paper P.
[0071]
In the following, first, the recording method of the intermediate area process applied in the embodiment will be described, and then the recording method of the upper end process and the lower end process will be described.
[0072]
FIG. 16 is an explanatory diagram showing a first embodiment of the recording method in the intermediate area. Here, a state in which a pair of nozzle rows (for example, Y and LM) in the print head 28b of the third embodiment shown in FIG. 14 is sub-scanned is shown. The pair of nozzle rows includes a preceding nozzle row FN and a subsequent nozzle row RN. The preceding nozzle row FN has seven nozzles F1 to F7. The subsequent nozzle row RN also has seven nozzle rows R1 to R7. The letters F and R given to each nozzle indicate whether it is the preceding nozzle row FN or the succeeding nozzle row RN, and the numbers 1 to 7 after the letters are the nozzles counted from the rear end of the print head 28b. Numbers are shown.
[0073]
In the various recording methods described below, the print head 28b shown in FIG. 14 is used. However, when using the other print heads described above, these recording methods can be similarly applied. .
[0074]
In the recording system shown in FIG. 16, every time one main scan is performed, sub-scan feed is executed with a constant feed amount L (= 7 dots). The nozzle pitch k in the same nozzle row is 180 dpi, and this nozzle pitch k corresponds to four main scanning lines (raster lines).
[0075]
As shown at the right end of FIG. 16, when one main scan is performed, the CPU 41 (FIG. 2) uses the preceding nozzle in the print data stored in the RAM 44 which is a print data memory. Reference is made to print data for a plurality of main scanning lines corresponding to the full width of the row FN and the succeeding nozzle row RN in the sub-scanning direction. Then, the CPU 41 executes one main scan according to the print data corresponding to these nozzle rows FN and RN. As described above, in the present embodiment, when printing is performed, the print data for the plurality of main scanning lines corresponding to the full width in the sub-scanning direction of the nozzle row pairs arranged in a staggered manner is referred to, and the print data referred to Therefore, if necessary, printing can be performed using all the nozzles of the nozzle row pair in one main scan. As a result, it is possible to increase the printing speed.
[0076]
FIG. 17 is an explanatory diagram showing the recording method shown in FIG. 16 separately for the subsequent nozzle row RN and the preceding nozzle row FN. The succeeding nozzle row RN is sub-scan fed with a constant feed amount L, whereby all the continuous main scan lines (raster lines) within the effective recording range are made of the same ink by the succeeding nozzle row RN. To be recorded. The same applies to the preceding nozzle row FN. The “effective recording range” means a range in which continuous main scanning lines can be recorded without a gap by each nozzle row provided in the print head 28b. In the example of FIG. 17, in the main scanning line whose raster number is −1, printing is not performed by the preceding nozzle row FN. Therefore, the effective recording range is a range below the main scanning line in which the raster number is written as 0. A range that is not an effective recording range is referred to as a “non-recordable range”. The effective recording range can also be called “effective printing range”, “print execution area”, or “record execution area”. Note that FIG. 17 is an example when the upper end processing described later is not performed.
[0077]
The recording system as shown in FIG. 17 is generally called an “interlace recording system”. In the “interlace recording method”, one nozzle row only records a plurality of main scan lines that are separated from each other in one main scan, and includes a plurality of main scans including at least one sub-scan feed. This means a recording method in which one nozzle row records a continuous main scanning line by scanning.
[0078]
In the interlace recording method shown in FIG. 17, the same main scanning line is not recorded between the nozzles of the same nozzle number in the nozzle row pairs FN and RN arranged in a staggered pattern, and the same nozzles of the different nozzle numbers are used. Sub-scan feed is performed so as to record the main scan line. Specifically, in the main scan line with the raster number 0, the second nozzle F2 in the preceding nozzle row FN and the sixth nozzle R6 in the succeeding nozzle row RN execute printing. On the main scan line with the raster number 1, the fourth nozzle F4 in the preceding nozzle row FN and the first nozzle R1 in the succeeding nozzle row RN execute printing. The advantages of such a recording method will become clear by comparison with the second embodiment described below.
[0079]
FIG. 18 is an explanatory diagram showing a second embodiment of intermediate area processing. In this recording method, after the sub-scan feed with the feed amount L of 1 dot is performed three times, the sub-scan feed with the feed amount L of 25 dots is performed once. By repeating the combination of the four sub-scan feeds and the four main scans executed once for each sub-scan feed, all the continuous main scan lines in the effective recording range are recorded. Is done.
[0080]
In the second embodiment, on the two main scanning lines with the raster numbers 0 and 1, the first nozzle F1 in the preceding nozzle row FN and the first nozzle R1 in the succeeding nozzle row RN execute printing. To do. In the two main scanning lines with raster numbers 4 and 5, the second nozzle F2 in the preceding nozzle row FN and the second nozzle R2 in the succeeding nozzle row RN execute printing. As described above, the recording method in which the same main scanning line is recorded by the nozzles having the same nozzle number in the preceding nozzle row FN and the succeeding nozzle row RN is extremely limited. On the other hand, various recording methods other than those shown in FIG. 17 are conceivable for recording the same main scanning line between nozzles having different nozzle numbers. For example, in the first embodiment of FIG. 17, the sub-scan feed amount L is a constant value of 7 dots. However, if a combination of a plurality of different values is used as the feed amount L, a large number of recording methods can be used. It is possible to configure. Therefore, it is possible to improve the print image quality by selecting a recording method with good image quality from among such a large number of recording methods.
[0081]
In the second embodiment of FIG. 18, four continuous main scanning lines are recorded by the same nozzle. Therefore, if the ejection direction of the ink from the nozzle R1 is deviated from the normal direction due to a manufacturing error of a certain nozzle (for example, the nozzle R1), the dots formed on the print medium May be misaligned. If such dot misalignment continues over a continuous main scanning line, image quality deterioration becomes conspicuous. On the other hand, in the first embodiment shown in FIG. 17, since continuous main scanning lines are not recorded by the same nozzle, there is an advantage that the possibility of such image quality deterioration is low.
[0082]
On the other hand, the second embodiment shown in FIG. 18 has the advantage that the recordable range can be greatly reduced and the effective recording range can be greatly expanded compared to the first embodiment.
[0083]
FIG. 19 is an explanatory diagram showing an example of the upper end process. In this example, four main scans from pass 1 to pass 4 belong to the upper end process, and the fifth and subsequent passes belong to the intermediate area process. The sub-scan feed amount L in the upper end process is a constant value of 3 dots. It is to be noted that a nozzle in which the x mark is overwritten on the nozzle number means that it is not used in that pass.
[0084]
When the recording method for intermediate region processing shown in FIG. 17 is applied from the leading edge of the printing paper, as shown in FIG. 17, there is a non-recordable range for 20 main scanning lines above the effective recording range. Exists. On the other hand, in the example of FIG. 19, the non-recordable range is reduced to 8 main scanning lines. As described above, the effective recording range can be extended by performing the upper end processing using the feed amount L smaller than the recording method of the intermediate area processing.
[0085]
In FIG. 19, it can be understood that the upper end line of the effective recording range is determined according to the main scanning line in which the preceding nozzle row FN can be recorded. That is, the CPU 41 determines the upper end line of the effective recording range according to the sub-scanning direction range in which the preceding nozzle row FN can be recorded. In other words, in the upper end process, it can be understood that the sub-scan feed amount and the number of main scans may be determined so that the preceding nozzle row FN can record as much as possible to the upper main scan line. By doing so, it is possible to easily determine the leading end of the effective recording range while reducing the number of useless main scans as much as possible near the leading end of the printing paper.
[0086]
FIG. 20 is an explanatory diagram illustrating an example of the lower end process. In this example, two passes of pass-1 and pass 0 belong to the intermediate area process, and three passes from pass + 1 to pass + 3 belong to the lower end process. The sub-scan feed amount L in the lower end process is a constant value of 3 dots.
[0087]
When shifting from the intermediate area process to the lower end process, the CPU 41 assumes that the sub-scan feed (L = 7) according to the recording method of the intermediate area process is performed. Then, it is determined whether or not the planned lower end line of the effective recording range is exceeded. When it is determined that the front end nozzle F7 exceeds the scheduled lower end line of the effective recording range, the process proceeds to the lower end process. In the example of FIG. 20, if it is assumed that the sub-scan feed is executed with the feed amount L of 7 dots after pass 0, the front end nozzle F7 of the preceding nozzle FN exceeds the planned lower end line. At this time, the effective recording range can be expanded by performing the lower end processing with a smaller feed amount L without continuing the recording method of the intermediate area processing. Therefore, the CPU 41 sets the sub-scan feed amount L before pass + 1 to 3 dots, and proceeds to the lower end process. In this way, it is possible to shift to the lower end processing while reducing the number of useless main scans as much as possible.
[0088]
Also by the lower end process of FIG. 20, the effective recording range is extended as in the upper end process shown in FIG. In addition, the lower end line of the effective recording range is determined according to the main scanning line on which the subsequent nozzle row RN can record. That is, the CPU 41 determines the lower end line of the effective recording range according to the sub-scanning direction range in which the subsequent nozzle row RN can record. By doing this, it is possible to easily determine the rear end of the effective recording range while reducing the number of useless main scans as much as possible near the rear end of the printing paper.
[0089]
E. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0090]
E1. Modification 1:
Various arrangements other than the various embodiments described above can be adopted as the arrangement of the nozzle array of the print head. For example, it is possible to generate a print head that is long in the sub-scanning direction and narrow in the main scanning direction by arranging all or part of the nozzle row pairs arranged in a staggered pattern along the sub-scanning direction.
[0091]
Further, as the light ink, inks other than light cyan and light magenta can be used. When there are three or more light ink nozzle rows, at least two of them are arranged to have the same positional relationship as the staggered nozzle row pairs with respect to at least the position in the sub-scanning direction. Is preferred.
[0092]
E2. Modification 2:
In each of the above embodiments, the ink jet printer has been described. However, the present invention is not limited to the ink jet printer, and is generally applicable to various printing apparatuses that perform printing using a print head. Further, the present invention is not limited to a method and apparatus for ejecting ink droplets, but can also be applied to a method and apparatus for recording dots by other means.
[0093]
E3. Modification 3:
The intermediate area processing in the above embodiment employs sub-scan feed (“regular feed”) in which the feed amount L is constant, but sub-scan feed (“regular feed”) using a plurality of different feed amounts. It is also possible to adopt. Also, irregular feeding can be adopted in the upper end processing and the lower end processing. In these cases, the average value of the sub-scan feed amount in the upper end process is set to a value smaller than the average value of the sub-scan feed amount in the intermediate area process. The same applies to the lower end processing. The phrase “sub-scan feed amount is small” has a broad meaning including such a case.
[0094]
E4. Modification 4:
In the above embodiment, one nozzle can record all the pixels on one main scanning line in one main scanning. However, the present invention can also be applied to a recording method in which one nozzle intermittently records only some pixels on one main scan line in one main scan. In such a recording method, in a plurality of main scans, all pixels on one main scan line are recorded by a plurality of nozzles.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a printing system including an inkjet printer 20 as a first embodiment of the present invention.
FIG. 2 is a block diagram illustrating a circuit configuration of the printer 20 with a control circuit 40 as a center.
FIG. 3 is an explanatory diagram showing a main part of a print head.
FIG. 4 is an explanatory diagram showing the principle of driving a nozzle n by a piezo element PE.
FIG. 5 is an explanatory diagram showing the arrangement of nozzle rows in the first embodiment.
6 is an exploded perspective view of an actuator circuit 90. FIG.
7 is a partial cross-sectional view of an actuator circuit 90. FIG.
FIG. 8 is an explanatory diagram showing the arrangement of ink passages in the print head of the first embodiment.
FIG. 9 is an explanatory diagram showing an arrangement of ink passages in a print head 280 of a comparative example.
FIG. 10 is an explanatory diagram showing the arrangement of nozzle rows in a second embodiment.
FIG. 11 is an explanatory diagram illustrating an equivalent nozzle row of a print head according to a second embodiment.
FIG. 12 is an explanatory diagram illustrating an example of bidirectional printing using the print head according to the second embodiment.
FIG. 13 is an explanatory diagram illustrating an example of bidirectional printing using a print head of a comparative example.
FIG. 14 is an explanatory diagram showing the arrangement of nozzle rows in a third embodiment.
FIG. 15 is an explanatory diagram showing the concept of applying a recording method on printing paper.
FIG. 16 is an explanatory diagram showing a first embodiment of a recording method in an intermediate area.
FIG. 17 is an explanatory diagram showing the recording method shown in FIG. 16 separately for the trailing nozzle row RN and the preceding nozzle row FN.
FIG. 18 is an explanatory diagram showing a second embodiment of the recording method in the intermediate area.
FIG. 19 is an explanatory diagram showing an example of upper end processing.
FIG. 20 is an explanatory diagram showing an example of lower end processing.
[Explanation of symbols]
20 ... Inkjet printer
22 ... Paper feed motor
24 ... Carriage motor
26 ... Platen
28 ... Print head
30 ... carriage
32 ... Control panel
34 ... Sliding shaft
36 ... Drive belt
38 ... pulley
39 ... Position sensor
40 ... Control circuit
41 ... CPU
44 ... RAM
50 ... I / F dedicated circuit
52. Head drive circuit
54 ... Motor drive circuit
56 ... Connector
60 ... print head unit
71-76 ... introduction pipe
80: Ink passage
88 ... Computer
90 ... Actuator circuit
91-93 ... Actuator chip
110 ... Nozzle plate
112 ... Reservoir plate
120 ... Connection terminal plate
122 ... Internal connection terminal
124: External connection terminal
126 ... Driver IC
130: Ceramic sintered body
132: Terminal electrode
280 ... print head
901-903 ... Actuator chip

Claims (9)

A printing apparatus that prints an image on a print medium while performing main scanning,
A print head having a plurality of nozzle rows;
A main scanning drive mechanism that performs main scanning by moving at least one of the print head and the print medium;
A sub-scanning drive mechanism that performs sub-scanning by moving at least one of the print head and the print medium;
A print data memory for storing print data;
A control unit for controlling the operation of the printing apparatus;
With
In the print head,
(1) Each nozzle row has a plurality of nozzles arranged along the sub-scanning direction and ejecting the same ink,
(2) The light cyan nozzle row and the light magenta nozzle row are arranged in a staggered manner, and the dark cyan nozzle row and the dark magenta nozzle row are also arranged in a staggered manner,
(3) A pair of ink passages for the dark cyan nozzle row and the dark magenta nozzle row are formed in a staggered pattern in the first ink passage forming body, and the light cyan nozzle row and the light magenta nozzle row A pair of ink passages are formed in a staggered pattern on a second ink passage formation body different from the first ink passage formation body,
(4) The staggered nozzle pairs are composed of a preceding nozzle row that reaches the leading edge of the print medium relatively early and a subsequent nozzle row that arrives relatively late when the sub-scan is performed. And
The controller is
(A) A single main scan records a plurality of main scan lines in which each nozzle row is separated from each other, and each nozzle row is continuous by a plurality of main scans including at least one sub-scan feed. Perform interlaced recording to record the scan line,
(B) In the interlace recording, print data for a plurality of main scanning lines corresponding to the full width in the sub-scanning direction of the nozzle row pairs arranged in a staggered manner before one main scanning is obtained from the print data memory. A printing apparatus that refers to and executes the one main scanning according to the referred print data. The printing apparatus according to claim 1, wherein the control unit further includes:
(C) In the interlaced recording, the same main scanning line is not recorded between the nozzles of the same nozzle number of the nozzle array pairs arranged in a staggered pattern, but the nozzles of the different nozzle numbers are not recorded. A printing apparatus that performs sub-scan feed to record lines. The printing apparatus according to claim 1, wherein the control unit further includes:
(D) In the interlaced recording, printing is executed according to the first recording method in an intermediate portion of the recording execution area on the print medium, and the sub-recording is performed near the tip of the recording execution area as compared with the first recording method. Printing according to the second recording method with a small scanning feed amount;
(E) In printing near the leading edge according to the second recording method, a printing apparatus that determines the leading edge of the recording execution area according to a range in the sub-scanning direction in which the preceding nozzle row can record. The printing apparatus according to claim 3, wherein the control unit further includes:
(F) In the interlace recording, printing is performed in the vicinity of the rear end of the recording execution area in accordance with a third recording method in which the sub-scan feed amount is smaller than that in the first recording method in the intermediate portion;
(G) In printing in the vicinity of the trailing edge according to the third recording method, a printing apparatus that determines the trailing edge of the recording execution area in accordance with a range in the sub-scanning direction in which the trailing nozzle row can record. The printing apparatus according to claim 4, wherein the control unit further includes:
(H) When it is assumed that the sub-scan feed according to the second recording method is performed when shifting from the printing by the second recording method to the printing by the third recording method, A printing apparatus that shifts from printing by the second recording method to printing by the third recording method when a nozzle at the front end exceeds a scheduled rear end of the recording execution area. The printing apparatus according to any one of claims 1 to 5,
The nozzle array pairs arranged in a staggered pattern are connected to a pair of ink passages for supplying ink to the nozzle array pairs,
The pair of ink passages is a printing apparatus provided in an ink passage forming body. The printing apparatus according to claim 6,
The pair of ink passages is a printing apparatus formed so as to protrude so that passage portions in the vicinity of each nozzle face each other. The printing apparatus according to any one of claims 1 to 7,
A printing apparatus in which more than half of the plurality of nozzle rows are configured as a pair of nozzle rows arranged in a staggered manner. The printing apparatus according to any one of claims 1 to 8,
The plurality of nozzle arrays include four basic color nozzle arrays for ejecting four basic color inks of black, cyan, magenta, and yellow, respectively.
The four basic color nozzle rows are arranged in the same position with respect to the sub-scanning direction.

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