JP2000318218A - Color printer using vertically arranged head, printing method, recording medium, and print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve image quality by controlling a relationship of a generating position of an accumulated error in a transporting quantity in a sub-scanning direction with respect to a dot of different ink. SOLUTION: An actuator 40 of a print head comprises a color nozzle array and a black nozzle array which are arranged in parallel in a sub-scanning direction. The color nozzle array has three nozzle groups. Each interval between the nozzle groups is two times of a nozzle pitch (k). An interval in each nozzle groups with respect to the nozzles used in each nozzle group is selected to be M ('M' is an integer number not less than 2) times of (k), i.e., a value of M×(k). The integer number M is preferably set to be a value except a value of (N×n+1) ('n' is an integer number not less than 1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for performing color printing using a print head for forming dots of a plurality of colors.

[0002]

2. Description of the Related Art There are a serial scan type printer, a drum scan type printer and the like as a printing apparatus for printing dots while a print head scans in a main scanning direction and a sub scanning direction. U.S. Pat. No. 4,198,642 and Japanese Patent Application Laid-Open No. 53-2040 describe techniques for improving the image quality of this type of printer, particularly an ink jet printer.
There is a technique called “interlace method” disclosed in Japanese Patent Application Laid-Open Publication No. H10-15095.

FIG. 25 is an explanatory diagram showing an example of the interlace system. In this specification, the following parameters are used as parameters defining the printing method.

N: Number of nozzles [number], k: Nozzle pitch [dot], s: number of scan repetitions, D: nozzle density [number / inch], L: sub-scan feed amount [dot] or [inch], w : Dot pitch [inch].

[0005] The number N of nozzles is the number of nozzles used for forming dots. In the example of FIG. 25, N = 3. The nozzle pitch k [dot] indicates how many nozzle pitches in the print head are equal to the pitch (dot pitch w) of the print image. In the example of FIG. 25, k = 2. The number of scan repetitions s [times] is
This is the number of times that the main scanning line is filled with dots by the main scanning. Hereinafter, the main scanning line is referred to as “raster”. In the example of FIG. 25, s = 1 since each raster is filled in one main scan. As described later, when s is 2 or more, dots are formed intermittently along the main scanning direction. The nozzle density D [pieces / inch] indicates how many nozzles are arranged per inch in the nozzle array of the print head.
The sub-scan feed amount L [dot] or [inch] indicates the distance moved in one sub-scan. Dot pitch w
[Inch] is the dot pitch in the print image. Generally, w = 1 / (D · k) and k = 1 / (D
・ W) is established.

In FIG. 25, a circle including a two-digit number is
Each of the dot recording positions is shown. As shown in the legend at the lower left of FIG. 25, of the two-digit number in the circle, the left-side number indicates the nozzle number, and the right-side number indicates the recording order (recording number in the main scan). Has been shown).

The interlace method shown in FIG. 25 is characterized by the configuration of the nozzle array of the print head and the sub-scanning method. That is, in the conventional interlace method, the nozzle pitch k indicating the center point interval between adjacent nozzles is set to an integer of 2 or more, and the number of nozzles N and the nozzle pitch k
Are selected as integers having a relatively prime relationship. The sub-scan feed amount L is set to a constant value given by N / (D · k).

The interlacing method has an advantage that variations in nozzle pitch, ink ejection characteristics, and the like can be dispersed on a printed image. Therefore, even if there is a variation in the nozzle pitch and the ejection characteristics, these effects can be reduced and the image quality can be improved.

Another technique aimed at improving the image quality of a color ink jet printer is disclosed in Japanese Patent Application Laid-Open No. Hei 3-2076.
No. 65, Japanese Patent Publication No. Hei 4-19030, etc., "overlap method" or "multi-scan method"
There is a technology called.

FIG. 26 is an explanatory diagram showing an example of the overlap system. In the overlap method, eight nozzles are classified into two nozzle groups. The first set of nozzle groups consists of four nozzles with even nozzle numbers (the number on the left side of the circle), and the second set of nozzle groups has four odd nozzle numbers. It is composed of nozzles. In one main scan, dots are formed at every (s−1) dots in the main scan direction by driving each set of nozzle groups at intermittent timing. In the example of FIG. 26, since s = 2, dots are formed every other dot. The drive timing of each nozzle group is controlled so that dots are formed at different positions in the main scanning direction. That is, as shown in FIG. 26, the nozzles of the first nozzle group (nozzle numbers 8, 6, 4,
2) and the nozzles of the second nozzle group (nozzle numbers 7, 5,
3, 3), the recording position is shifted by one dot pitch in the main scanning direction. Then, such main scanning is performed a plurality of times, and the drive timing of each nozzle group is shifted each time, thereby completing the formation of all dots on the raster.

In the overlap mode, the nozzle pitch k is set to an integer of 2 or more, similarly to the interlace mode. However, the number of nozzles N and the nozzle pitch k do not have a relatively prime relationship. Instead, a value N / s obtained by dividing the number of nozzles N by the number of scan repetitions s and the nozzle pitch k have a relatively prime relationship. Selected as an integer. Further, the sub-scan feed amount L is set to a constant value given by N / (sDk). Note that “the integers A and B are relatively prime” means that the integers A and B have no common divisor other than 1.

In the overlap method, dots on each raster are not recorded by the same nozzle, but are recorded by using a plurality of nozzles. Therefore, even when the characteristics (pitch, ejection characteristics, etc.) of the nozzles vary, it is possible to prevent the influence of the characteristics of a specific nozzle from affecting the entirety of one raster, thereby improving the image quality. .

[0013]

By the way, a mechanical error occurs in the sub-scan feed, and this error tends to be accumulated when the sub-scan feed is repeated. In the interlace method, while two adjacent raster lines are recorded,
A plurality of sub-scan feeds may be performed. At this time,
Due to the accumulated error in the sub-scan feed, a slight variation (wide and narrow) occurs in the interval between the two raster lines. Such a portion having a large variation is observed as so-called banding (a streak-like image degradation portion extending in the main scanning direction).

In recent years, in order to alleviate the occurrence of such banding, various dot recording methods have been proposed in which the sub-scan feed amount is devised. However, conventionally, little consideration has been given to the relationship between the occurrence positions of banding with respect to dots of different inks, that is, the relationship between the occurrence positions of cumulative errors in the sub-scan feed amount with respect to dots of different inks. For this reason, the banding positions of dots of different inks may overlap with each other, degrading the image quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and improves the image quality by appropriately adjusting the relationship between the positions of occurrence of accumulated errors in the sub-scan feed amount for dots of different inks. The purpose of the present invention is to provide a technology that can be used.

[0016]

In order to solve at least part of the above problems, the present invention uses a print head having the following three features i) to iii). i) a plurality of sets of dot forming element arrays for forming dots using mutually different inks,
It has a plurality of sets of dot forming element arrays arranged in a straight line along the sub-scanning direction. ii) The plurality of dot forming elements included in each set of dot forming element arrays are provided such that the pitch k of the dot forming elements measured along the sub-scanning direction is equal to each other. iii) The pitch k of the dot forming elements is set to a value that is an integral multiple of twice or more the pitch of the dots on the print medium in the sub-scanning direction.

Further, for each set of dot forming element arrays, dots are formed on the print medium by using an equal number of N dot forming elements continuously arranged at intervals of the pitch k. Further, the N dot-forming elements used in each set are such that the interval between each pair of the N dot-forming elements is M times the pitch k of the dot-forming elements (M is an integer of 2 or more). ) Is selected.

In the present invention, the interval between each set of dot forming elements used in each set is M times the pitch k (M is 2).
Is set to the value M × k of the above integer)
The positions where the accumulated errors of the sub-scan feed amounts for the dots of different inks do not always coincide. Therefore, the occurrence of banding can be reduced, and the image quality can be improved.

In the printing head, the interval between the dot forming elements existing at the end of each set of dot forming element arrays is m times the pitch k of the dot forming elements (m is an integer of 2 or more). It is preferable to form them so as to have a value of m × k.

Here, "the dot forming element existing at the end of each set of dot forming element arrays" means the end of the array of each set among all the dot forming elements including those not used. Means a dot-forming element existing in. If the print head as described above is used, even if almost all the dot forming elements provided in the print head are used, the interval between each pair of the dot forming elements used in each set is set to the pitch k. The value can be set to be M × k (M is an integer of 2 or more).

It is preferable that the integer M is set to a value other than (N × n + 1) (n is any integer of 1 or more). In this case, it is possible to more reliably prevent the occurrence positions of the accumulated errors of the sub-scanning feed amounts related to the dots of different inks from always matching.

The sub-scanning is performed in accordance with an interlace method in which a plurality of sub-scan feeds are performed between two main scans for executing dot recording on two adjacent main scanning lines. Can be performed. In such an interlace method, the accumulated error of the sub-scan feed amount in two adjacent main scan lines tends to be large. Therefore, in such an interlaced system,
The effect that "the positions where the accumulated errors of the sub-scan feed amounts for the dots of different inks do not always coincide, the occurrence of banding can be reduced and the image quality can be improved" becomes more remarkable.

As specific embodiments of the present invention, various embodiments such as a printing apparatus, a printing method, a print head, and a recording medium can be adopted.

[0024]

DETAILED DESCRIPTION OF THE INVENTION Next, an embodiment of the present invention will be described based on examples. FIG. 1 is a schematic perspective view showing a main configuration of a color inkjet printer 20 as one embodiment of the present invention. The printer 20 includes a paper stacker 22, a paper feed roller 24 driven by a step motor (not shown), and a platen plate 26.
, A carriage 28, a step motor 30, a traction belt 32 driven by the step motor 30, and a guide rail 34 for the carriage 28. A print head 36 having a number of nozzles is mounted on the carriage 28.

The printing paper P is taken up from the paper stacker 22 by the paper feed roller 24, and is fed on the surface of the platen plate 26 in the sub-scanning direction. The carriage 28 is pulled by a pulling belt 32 driven by a step motor 30 and moves along a guide rail 34 in the main scanning direction. The main scanning direction is perpendicular to the sub-scanning direction.

FIG. 2 is a block diagram showing the electrical configuration of the printer 20. The printer 20 includes a reception buffer memory 50 that receives a signal supplied from the host computer 100, an image buffer 52 that stores print data, and a system controller 54 that controls the operation of the entire printer 20. The system controller 54 is connected to a main scanning driver 61 for driving the carriage motor 30, a sub-scanning driver 62 for driving the paper feed motor 31, and a head driver 63 for driving the print head 36.

A printer driver (not shown) of the host computer 100 determines various parameter values that define a printing operation based on a printing method (described later) specified by the user. The printer driver further generates print data for performing printing in the printing method based on these parameter values, and transfers the print data to the printer 20. The transferred print data is temporarily stored in the reception buffer memory 50. In the printer 20, the system controller 54 reads necessary information from the print data from the reception buffer memory 50, and based on the read information,
A control signal is sent to each of the drivers 61, 62, 63.

The image buffer 52 stores image data of a plurality of color components obtained by decomposing the print data received by the reception buffer memory 50 for each color component. The head drive driver 63 reads out image data of each color component from the image buffer 52 in accordance with a control signal from the system controller 54, and drives a nozzle array of each color provided in the print head 36 in accordance with the readout.

B. Configuration of Print Head: FIG. 3 is an explanatory view showing the arrangement of nozzles formed on the bottom surface of the actuator 40 provided below the print head 36. On the bottom surface of the actuator 40, there are formed a color nozzle row and a black nozzle row which are respectively arranged in a straight line along the sub-scanning direction. In addition, "actuator"
It means an ink ejection mechanism including a nozzle and a piezo element. In this specification, the “nozzle row” is also referred to as a “nozzle array”.

The black nozzle row has 48 nozzles #K
1 to # K48. These nozzles # K1- #
K48 is arranged at a constant nozzle pitch k along the sub-scanning direction. This nozzle pitch k is 6 dots. However, the nozzle pitch k can be set to a value obtained by multiplying the dot pitch on the print medium P by an arbitrary integer of 2 or more.

The color nozzle row is a nozzle group 4 for yellow.
0Y, a magenta nozzle group 40M, and a cyan nozzle group 40C. In this specification, the nozzle group for the chromatic ink is also referred to as a “chromatic nozzle group”.
The yellow nozzle group 40Y includes 15 nozzles # Y1 to # Y1.
# Y15, and the pitch of these 15 nozzles is the same as the nozzle pitch k of the black nozzle row. This is the same for the magenta nozzle group 40M and the cyan nozzle group 40C. The nozzle group 4 for yellow
Nozzle # Y15 at the lower end of 0Y and magenta nozzle group 4
An “x” mark between the nozzle # M1 at the upper end of 0M indicates that no nozzle is formed at that position. Accordingly, the interval between the nozzle # Y15 at the lower end of the yellow nozzle group 40Y and the nozzle # M1 at the upper end of the magenta nozzle group 40M is twice the nozzle pitch k. This is the nozzle # M15 at the lower end of the magenta nozzle group 40M.
The same applies to the distance between the nozzle # C1 at the upper end of the cyan nozzle group 40C. In other words, the interval between the nozzle groups for yellow, magenta, and cyan is set to twice the nozzle pitch k.

The nozzles of the color nozzle groups 40Y, 40M, and 40C are arranged at the same sub-scanning positions as the nozzles of the black nozzle row 40K. However, the black nozzle row 40
Among the 48 nozzles # K1 to # K48 of K, the 16th, 32nd, and 48th nozzles # K16, # K32, #
No nozzle for chromatic ink is provided at the corresponding position for K48.

During printing, while the print head 36 moves in the main scanning direction together with the carriage 28 (FIG. 1),
Ink droplets are ejected from each nozzle. However, depending on the printing method, not all nozzles are always used, and only some nozzles may be used.

C. Basic conditions of general printing method: Before describing a printing method in the embodiment of the present invention, first, basic conditions required for a general printing method will be described. In the following description, the “printing method” is referred to as a “dot recording method”.

FIG. 4 is an explanatory diagram showing the basic conditions of a general dot recording system when the number of scan repetitions s is one. FIG. 4A shows an example of sub-scan feed when four nozzles are used, and FIG. 4B shows parameters of the dot recording method. In FIG. 4A, solid-line circles including numbers indicate the positions in the sub-scanning direction of the four nozzles after each sub-scan feed. Numbers 0 to 3 in the circles indicate nozzle numbers. The positions of the four nozzles are sent in the sub-scanning direction each time one main scan is completed. However, actually, the feed in the sub-scanning direction is realized by moving the paper by the paper feed motor 31 (FIG. 2).

As shown at the left end of FIG. 4A, in this example, the sub-scan feed amount L is a constant value of 4 dots. Therefore,
Each time the sub-scan feed is performed, the positions of the four nozzles shift by four dots in the sub-scan direction. When the number of scan repetitions s is 1, each nozzle can record all dots (also referred to as “pixels”) on each raster. At the right end of FIG. 4A, the numbers of nozzles that record dots on each raster are shown. Note that in a raster drawn by a broken line extending rightward (main scanning direction) from a circle indicating the position of the nozzle in the sub-scanning direction, at least one of the rasters above and below the raster cannot be printed, so that dot printing is actually prohibited. Is done. On the other hand, a raster drawn by a solid line extending in the main scanning direction is a range in which both the rasters before and after the raster can be recorded by dots. The range in which recording can be actually performed in this manner is hereinafter referred to as an effective recording range (effective printing range) or a “printable area”.

FIG. 4B shows various parameters relating to the dot recording method. The parameters of the dot recording method include the nozzle pitch k [dot], the number of used nozzles N [number], the number of scan repetitions s, the effective number of nozzles Neff [number], and the sub-scan feed amount L [dot].
And are included.

In the example of FIG. 4, the nozzle pitch k is 3 dots. The number N of used nozzles is four. The number of used nozzles N is the number of nozzles actually used among a plurality of mounted nozzles. The number of scan repetitions s means that dots are formed intermittently every (s−1) dots in one main scan. Therefore, the number of scan repetitions s is also equal to the number of nozzles used to record all dots on each raster. In the case of FIG. 4, the number of scan repetitions s is one. The effective nozzle number Neff is a value obtained by dividing the used nozzle number N by the number of scan repetitions s. This effective nozzle number Neff can be considered to indicate the net number of rasters that can be recorded in one main scan. The meaning of the effective nozzle number Neff will be further described later.

FIG. 4B shows a table for each sub-scan feed.
The sub-scan feed amount L, its cumulative value ΔL, and the nozzle offset F after each sub-scan feed are shown. Here, the offset F refers to the periodic position of the first nozzle where the sub-scan feed is not performed (in FIG. 4, a position every four dots) as the reference position of the offset 0, and This value indicates how many dots the nozzle position is apart from the reference position in the sub-scanning direction. For example, as shown in FIG. 4A, the nozzle position moves in the sub-scanning direction by the sub-scanning feed amount L (4 dots) by the first sub-scan feed. On the other hand, the nozzle pitch k is 3 dots. Therefore,
The nozzle offset F after the first sub-scan feed is 1 (see FIG. 4A). Similarly, the nozzle position after the second sub-scan feed has moved by ΔL = 8 dots from the initial position, and its offset F is 2. The nozzle position after the third sub-scan feed is ΔL = 12 from the initial position.
The dot has moved, and its offset F is 0. 3
Since the nozzle offset F returns to 0 by two sub-scan feeds, all the dots on the raster in the effective recording range can be printed by repeating this cycle with three sub-scans as one cycle.

As can be seen from the above example, the offset F is zero when the position of the nozzle is located at an integer multiple of the nozzle pitch k from the initial position. The offset F is given by the remainder (ΔL)% k obtained by dividing the total value ΔL of the sub-scan feed amount L by the nozzle pitch k. here,
“%” Is an operator indicating that the remainder of the division is taken.
If the initial position of the nozzle is considered to be a periodic position, the offset F can be considered to indicate the amount of phase shift from the initial position of the nozzle.

When the number of scan repetitions s is 1, it is necessary to satisfy the following conditions in order to prevent raster omission or overlap in the effective recording range.

Condition c1: The number of sub-scan feeds per cycle is equal to the nozzle pitch k.

Condition c2: The nozzle offset F after each sub-scan feed in one cycle is a different value in the range of 0 to (k-1).

Condition c3: Average feed amount of sub-scan (ΣL /
k) is equal to the number N of used nozzles. In other words, the total value ΔL of the sub-scan feed amount L per cycle is equal to a value (N × k) obtained by multiplying the number of used nozzles N by the nozzle pitch k.

The above conditions can be understood by considering the following. (K-1) between adjacent nozzles
Since one raster exists, these (k−
1) In order to perform printing on one raster and return to the nozzle reference position (the position where the offset F is zero), the number of sub-scan feeds in one cycle is k. If the number of sub-scan feeds in one cycle is less than k, the recorded raster will be missing, while if the number of sub-scan feeds in one cycle is more than k, the recorded raster will overlap. Therefore, the above first condition c1 is satisfied.

When the number of sub-scan feeds per cycle is k,
The value of the offset F after each sub-scan feed is 0 to (k−
Only when the values are different from each other in the range of 1), the recorded raster does not have any omission or overlap. Therefore, the above second condition c2 is satisfied.

If the above first and second conditions are satisfied, 1
During the cycle, each of the N nozzles records k rasters. Therefore, in one cycle, N
× k rasters are recorded. On the other hand, if the above third condition c3 is satisfied, as shown in FIG. 4A, the position of the nozzle after one cycle (after k times of sub-scan feed) becomes N × k from the initial nozzle position. Comes away from raster. Therefore, by satisfying the first to third conditions c1 to c3, it is possible to eliminate omissions and duplications in the rasters to be recorded in the range of these N × k rasters.

FIG. 5 is an explanatory diagram showing basic conditions of a general dot recording system when the number of scan repetitions s is 2 or more. When the number of scan repetitions s is 2 or more, the same raster is printed by s different nozzles. Hereinafter, a dot recording method in which the number of scan repetitions s is 2 or more is referred to as an “overlap method”.

The dot recording method shown in FIG.
In the parameters of the dot recording method shown in FIG. 5, the number of scan repetitions s and the sub-scan feed amount L are changed.
As can be seen from FIG. 5A, the sub-scan feed amount L in the dot recording method of FIG. 5 is a constant value of 2 dots. However, in FIG. 5A, the positions of the nozzles after the odd-numbered sub-scan feeds are indicated by diamonds. As shown in the right end of FIG. 5A, the pixel positions recorded after the odd-numbered sub-scan feeds are the same as the pixel positions recorded after the even-numbered sub-scan feeds, and only one dot in the main scanning direction. It is out of alignment.
Therefore, a plurality of dots on the same raster are recorded intermittently by two different nozzles. For example, the uppermost raster in the effective recording range is intermittently printed every other dot by the second nozzle after the first sub-scan feed, and then is output by the 0th nozzle after the fourth sub-scan feed. It is recorded intermittently every dot. In general, in the overlap method, the nozzles are driven at intermittent timings so that (s-1) dot printing is prohibited after printing one dot during one main scan.

In the overlap method, since the positions of a plurality of nozzles for recording the same raster in the main scanning direction need only be shifted from each other, the actual shift amount in the main scanning direction at each main scanning is shown in FIG. Various things other than those shown in (A) are conceivable. For example, after the first sub-scan feed, the dot at the position indicated by the circle is recorded without shifting in the main scanning direction, and after the fourth sub-scan feed, the dot is shifted in the main scan direction to indicate the position indicated by the diamond. Can be recorded.

At the bottom of the table in FIG. 5B, the value of the offset F after each sub-scan in one cycle is shown. One cycle includes six sub-scan feeds, and the offset F after each of the first to sixth sub-scan feeds includes a value in the range of 0 to 2 twice. Also,
The change of the offset F after the first to third sub-scan feeds is equal to the change of the offset F after the fourth to sixth sub-scan feeds. As shown in the left end of FIG. 5A, six sub-scan feeds in one cycle are performed by:
It can be divided into two sets of three small cycles.
At this time, one cycle of the sub-scan feed includes a small cycle of s.
Complete by repeating it.

In general, when the number of scan repetitions s is an integer of 2 or more, the first to third conditions c1 to c3 described above are used.
c3 is rewritten as the following conditions c1 ′ to c3 ′.

Condition c1 ′: The number of sub-scan feeds in one cycle is equal to the value (k × s) obtained by multiplying the nozzle pitch k by the number of scan repetitions s.

Condition c2 ': The nozzle offset F after each sub-scan feed in one cycle is a value in the range of 0 to (k-1), and each value is repeated s times.

Condition c3 ′: average feed amount of sub-scan ΔL /
(K × s)} is equal to the effective nozzle number Neff (= N / s). In other words, the sub-scan feed amount L per cycle
Is equal to the value {Neff × (k × s)} obtained by multiplying the number of effective nozzles Neff by the number of sub-scan feeds (k × s).

The above conditions c1 'to c3' hold even when the number of scan repetitions s is one. Therefore, condition c
The conditions 1 ′ to c3 ′ are generally satisfied for the dot recording method regardless of the value of the scan repetition number s. That is, if the above three conditions c1 'to c3' are satisfied, it is possible to prevent dots to be recorded from missing or overlapping in the effective recording range. However, the overlap method (when the number of scan repetitions s is 2 or more)
Is required, it is necessary to shift the recording positions of the nozzles that record the same raster in the main scanning direction.

Note that, depending on the recording method, partial overlap may occur. “Partial overlap” refers to a recording method in which raster data recorded by one nozzle and raster data recorded by a plurality of nozzles are mixed. Even in the printing method using such partial overlap, the effective nozzle number Neff
Can be defined. For example, of the four nozzles, two nozzles cooperate to print the same raster, and the remaining two nozzles each print one raster, in a partially overlapped manner, Effective nozzle number N
eff is three. Also in the case of such a partial overlap method, the above three conditions c1 'to c3' are satisfied.

Note that the effective nozzle number Neff can be considered to indicate the net number of rasters that can be recorded in one main scan. For example, the number of scan repetitions s
Is 2, the number of rasters equal to the number of used nozzles N can be recorded in two main scans. Therefore, the net number of rasters that can be recorded in one main scan is N
/ S (ie, Neff).

D. First Embodiment FIG. 6 is an explanatory diagram showing scanning parameters in a printing method according to a first embodiment of the present invention. In the first embodiment, the nozzle pitch k is 6 dots, the number of scan repetitions s is 1, the number N of used nozzles is 13, and the number Neff of effective nozzles is 13.

The lower table of FIG. 6 shows parameters relating to the first to seventh passes. In addition,
In this specification, one main scan is also called a “pass”. In this table, for each pass, the feed amount L of the sub-scan executed immediately before the pass, the accumulated value ΣL,
The offset F is shown. Sub-scan feed amount L is 1
This is a fixed value of 3 dots. Thus, the sub-scan feed amount L
The printing method (scanning method) in which is a constant value is called “regular feed”. The scanning parameters of the first embodiment satisfy the above-described conditions c1 ′ to c3 ′.

FIG. 7 is an explanatory diagram showing nozzles used in the first embodiment. The actuator 40 in FIG. 7 is the same as that shown in FIG. 3, but in the first embodiment, only some of the nozzles are used. In FIG. 7, nozzles used in the first embodiment are indicated by white circles, while nozzles not used are indicated by black circles. That is, for the chromatic ink, the first 13 nozzles of the 15 nozzles of each color are used. For black ink, the nozzles # C1 to #C
Only 13 nozzles at the same sub-scanning position as C13 are used. As described above, by using the same number of nozzles for each of the four inks, by performing scanning in accordance with the scanning parameters common to the nozzles for each ink, it is possible to form dots of each ink without omission or duplication. it can.

In the present specification, the nozzle group for each ink constituted by the nozzles to be used is also referred to as “used nozzle group”. Further, the nozzle group for each ink provided in the actuator 40 is also referred to as “mounting nozzle group”.

As the nozzles to be used for each ink, those continuously arranged at the nozzle pitch k are selected. Also,
A nozzle # Y13 at the lower end of the used nozzle group for yellow;
The interval between the nozzle # M1 at the upper end of the used nozzle group for magenta is 4k (that is, 24 dots). Similarly, the interval between the nozzle # M13 at the lower end of the used nozzle group for magenta and the nozzle # C1 at the upper end of the used nozzle group for cyan is also 4k.

FIG. 8 is an explanatory diagram showing nozzles for recording each raster line within the effective recording range in each pass of the first embodiment. In pass 1, three nozzles #C for cyan
11 to # C13 execute dot recording on the first, seventh, and thirteenth effective raster lines, respectively. In addition,
“Effective raster line” means a raster line within the effective recording range. In FIG. 8, the leading symbol “#” of the nozzle number is omitted. In addition, the hatched nozzles indicate unused nozzles. The symbol “x” indicates a position where there is no intermediate nozzle between adjacent mounting nozzle groups.

In pass 2, the recording target position of the actuator 40 on the printing paper moves by 13 dots in the sub-scanning direction from pass 1. In this embodiment, since the nozzle pitch k is 6, the offset F of the nozzle position after the sub-scan feed (the remainder obtained by dividing the accumulated value ΔL of the feed amount L by k) is one dot. Therefore, in pass 2, it appears that the raster line immediately below the raster line to be recorded in pass 1 is to be recorded. Of course, 13 raster lines below are actually recorded. In the first embodiment, the sub-scan feed amount L is a fixed value of 13 dots. Therefore, each time the sub-scan feed is performed once, the position of the raster line to be recorded is moved downward by one line. appear.

For the cyan ink, the position Cmi between the sixth and seventh raster lines will be described below.
In s, the cumulative value of the sub-scan feed error is the largest.
The sixth raster line is recorded in pass 6, while the seventh raster line is recorded in pass 1. Therefore, pass 1 for recording the seventh raster line
And the pass 6 for printing the sixth raster line, the sub-scan feed is performed five times. Therefore, five sub-scan feed errors are accumulated between the sixth and seventh raster lines. Similarly, between the twelfth and thirteenth raster lines, five sub-scan feed errors are accumulated for cyan ink.

From the same considerations as described above, it is understood that the accumulated value of the sub-scan feed error becomes relatively large at the position Mmis between the seventh and eighth raster lines for magenta ink. For the yellow ink,
At the position Ymis between the ninth and tenth raster lines, the accumulated value of the sub-scan feed error becomes relatively large. In the following, a position where the cumulative value of the sub-scan feed error is relatively large is referred to as an “error cumulative position”.

As can be understood from the above description, in the first embodiment, the error accumulation position differs for each chromatic color ink.
No match. At the error accumulation position, banding (a streak-like image degradation part extending in the main scanning direction) tends to occur. However, according to the present embodiment, since the error accumulation position differs for each chromatic color ink, banding at these positions can be made inconspicuous.

FIG. 9 is an explanatory diagram showing an actuator used in the first comparative example. The actuator 40 'includes chromatic nozzle groups 40Y', 40M ', 40
C ′ is composed of 13 nozzles each. Also,
The interval between the nozzles at the ends of the chromatic nozzle groups 40Y ', 40M', and 40C 'is equal to the nozzle pitch k. That is, in the actuator 40 'of FIG. 9, the thirteen nozzles for each chromatic ink used in the first embodiment are:
They are arranged continuously at a nozzle pitch k. The black nozzle group 40 'also includes 39 nozzles arranged at a nozzle pitch k. In the first comparative example, printing is executed according to the same scanning parameters as those of the first embodiment shown in FIG.

FIG. 10 is an explanatory diagram showing nozzles for recording each raster line within the effective recording range in each pass of the first comparative example. In the first comparative example, the error accumulation positions Cmis, Mmis, and Ymis for the three chromatic inks are the positions between the sixth and seventh raster lines and the positions between the twelfth and thirteenth raster lines. Matches.
In such a case, the banding is conspicuous and the image quality is likely to deteriorate.

As can be seen by comparing the used nozzles shown in FIGS. 7 and 9, the only difference between the first embodiment and the first comparative example is the interval between the used nozzle groups. That is, in the first embodiment, the interval between the used color nozzle groups is set to 4 times the nozzle pitch k.
The double value is set to 4k, while in the first comparative example, the interval between the used nozzle groups is set to the same value as the nozzle pitch k. Such a difference in the interval between the used nozzle groups is caused by the error accumulation positions Cmis, Cmis, as shown in FIGS.
It can be understood that it appears as a difference between the occurrence positions of Mmis and Ymis.

In order to minimize the error accumulation positions of the nozzle groups adjacent in the sub-scanning direction, the interval between the adjacent nozzle groups is generally set to M times the nozzle pitch k (M is It is preferable to select the nozzles to be used so as to be an integer of 2 or more).

However, it is preferable that the interval between the nozzle groups used adjacent in the sub-scanning direction is further set as follows. FIG. 11 is an explanatory diagram showing equivalent nozzle positions in the printing method shown in FIG. As described in FIG. 4, when the number of scan repetitions s is 1, one cycle of scanning includes k sub-scan feeds. Therefore, the moving amount of the nozzle group in the sub-scan feed for one cycle is N ×
This is a k raster. FIG. 11 shows the initial position of the nozzle group in each cycle from the first cycle to the third cycle. Since the same printing operation is performed from these three nozzle group positions, these positions are equivalent to each other. The interval between the lower end nozzle at the initial position of the first cycle and the upper end nozzle at the initial position of the second cycle is k dots. The interval between the lower end nozzle at the initial position of the first cycle and the upper end nozzle at the initial position of the third cycle is (N × k + k) dots. Although not shown, the interval between the lower end nozzle at the initial position of the first cycle and the upper end nozzle at the initial position of the fourth cycle is (2 × N × k +
k) It turns out that it is a dot. In general, the interval between the lower end nozzle of the nozzle group at the initial position in the first cycle and the upper end nozzle of another equivalent nozzle group is (N × n + 1).
It can be expressed as k dot. Here, n is an arbitrary integer of 0 or more.

If nozzle groups using different inks are arranged at equivalent nozzle group positions as shown in FIG.
The error accumulation positions for those inks coincide with each other. In order to avoid such a case, the interval between the adjacent used nozzle groups is set to a value other than (N × n + 1) k dots (N is the number of used nozzles, and n is an arbitrary integer of 1 or more). Is preferred. Here, the reason why n is set to 1 or more instead of 0 or more is that the interval between adjacent used nozzle groups is M times the nozzle pitch k (M is an integer of 2 or more) as described above.
This is because if n = 0, the case of n = 0 is excluded.

E. FIG. 12 shows a second embodiment of the present invention.
FIG. 4 is an explanatory diagram illustrating scanning parameters in a printing method according to the embodiment. In the second embodiment, the nozzle pitch k is 6 dots,
The number of scan repetitions s is 1, the number N of used nozzles is 15,
The effective nozzle number Neff is 15.

The table at the bottom of FIG. 12 shows the parameters for each of the first to seventh passes. As the sub-scan feed amount L, an array of three different values of 14, 15, and 16 dots is used. A printing method (scanning method) using an array of a plurality of different values as the sub-scan feed amount L in this manner is referred to as “irregular feed”. The scanning parameters of the second embodiment also satisfy the above-mentioned conditions c1 'to c3'.

FIG. 13 is an explanatory diagram showing nozzles used in the second embodiment. Actuator 4 of FIG.
0 is the same as that shown in FIG. For chromatic inks, all 15 nozzles of each color are used. For black ink, only 15 nozzles at the same position in the sub-scanning direction as the cyan nozzles # C1 to # C15 are used. Therefore, the interval between the nozzle # Y15 at the lower end of the used nozzle group for yellow and the nozzle # M1 at the upper end of the used nozzle group for magenta is 2k.
Similarly, nozzle #M at the lower end of the used nozzle group for magenta
No. 15 and nozzle # C1 at the upper end of the nozzle group for cyan
Is also 2k.

FIG. 14 is an explanatory diagram showing nozzles for recording each raster line within the effective recording range in each pass of the second embodiment. In the second embodiment, since the irregular feeding is used, the positions of the nozzle groups for each pass are not as regular as in the first embodiment. Therefore, there is an advantage that the sub-scan feed accumulated error is smaller than that of the first embodiment.

As will be described further below, the second embodiment also has the advantage that the accumulated error position of the sub-scan feed does not always coincide between the nozzle groups used.
For cyan, the largest difference in the number of sub-scan feeds is between the second and third raster lines, and the difference in the number of sub-scan feeds is four. That is, for cyan, the error accumulation position Cmis exists between the second and third raster lines. Also for magenta and yellow, error accumulated positions Mmis and Ymis exist between the second and third raster lines. By the way, for cyan and magenta, the next accumulated error positions Cmis and Mmis
Exists between the eighth and ninth raster lines. On the other hand, for yellow, the next accumulated error position Ymis
Exists between the seventh and eighth raster lines.

As described above, in the second embodiment, the accumulated error positions Cmis, Mmis, and Ymis for the three nozzle groups are used.
However, they do not always match. For this reason, the occurrence of banding due to the accumulated error in the sub-scan feed can be reduced as compared with the case where the accumulated error positions Cmis, Mmis, and Ymis for the three used nozzle groups always coincide.

FIG. 15 is an explanatory view showing an actuator used in the second comparative example. The actuator 40 ″ in FIG. 15 includes each chromatic nozzle group 40Y ″, 40
M "and 40C" are each composed of 15 nozzles. Also, each chromatic nozzle group 40Y ", 40M", 40
The distance between the nozzles at the end of C "is equal to the nozzle pitch k. The black nozzle group 40" is composed of 45 nozzles. In the second comparative example, printing is executed according to the same scanning parameters as those of the second embodiment shown in FIG. 12 using such an actuator 40 ″.

FIG. 10 is an explanatory diagram showing nozzles for recording each raster line within the effective recording range in each pass of the first comparative example. In the second comparative example, the error accumulation positions Cmis, Mmis, and Ymis for the three chromatic inks are between the second and third raster lines, between the eighth and ninth raster lines, and at the fourteenth. It exists between and between the fifteenth raster lines. That is, in the second embodiment, the error accumulation positions Cmis, Mmis, and Ymis for the three color inks.
Always coincide with each other, and at an interval of 6 dots (that is, at an interval of the nozzle pitch k), the error accumulation positions Cmis, Mmis,
Ymis appears repeatedly. As described above, if the error accumulation positions Cmis, Mmis, and Ymis of the respective chromatic color nozzle groups always coincide, banding is easily noticeable.

As can be seen by comparing FIGS. 13 and 15, the only difference between the second embodiment and the second comparative example is the interval between the nozzle groups used. That is, in the second embodiment, the interval between the used nozzle groups is set to a value 2k which is twice the nozzle pitch k, while in the second comparative example, the interval between the used nozzle groups is set to the nozzle pitch k. They are set to the same value. FIG. 1 shows the difference in the interval between the used nozzle groups.
3 and error accumulation positions Cmis, Mmis,
This appears as a difference in the position where Ymis occurs.

As will be understood from the above description, in the second embodiment, similarly to the first embodiment, the interval between the adjacent nozzle groups is M times the nozzle pitch k (M is an integer of 2 or more).
The nozzle to be used has been selected. Further, the interval between the adjacent used nozzle groups is set to a value other than (N × n + 1) k dots (N is the number of used nozzles, and n is an arbitrary integer of 1 or more).

As can be understood from FIG.
In the embodiment, all the chromatic ink nozzles provided in the actuator 40 are used. In the actuator 40 used in the present embodiment, the interval between the mounting nozzle groups for each ink is set to a value twice the nozzle pitch k. Therefore, even if all the chromatic ink nozzles are used, The error accumulation position does not always coincide between the chromatic nozzle groups. Therefore, there is an advantage that high-quality printing can be performed using as many chromatic ink nozzles as possible among the nozzles provided in the actuator 40.

Generally, the interval between the mounting nozzle groups arranged along the sub-scanning direction (that is, the interval between the nozzles at the end of the mounting nozzle group for each ink) is m of the nozzle pitch k. It is preferable that the number is set to be twice (m is an integer of 2 or more). This makes it possible to perform high-quality printing using as many nozzles as possible for the reasons described above.

The interval between the mounting nozzle groups arranged along the sub-scanning direction may be set equal to the nozzle pitch k. In this case, if some of the nozzles in each mounting nozzle group are not used, it is possible to configure the same nozzle group as that used in the first and second embodiments.

F. Modification Example of Actuator: FIG.
It is an explanatory view showing a first modification of the actuator. The nozzle row on the left side of the actuator 41 is the same as the nozzle row on the left side of the actuator 40 of the embodiment shown in FIG. The nozzle row on the right side of the actuator 41 in FIG. 17 includes a light magenta nozzle group 40LM, a light cyan nozzle group 40LC, and a black nozzle group 40K. Each ink mounting nozzle group includes 15 nozzles. In addition, the spacing between the mounting nozzle groups for three colors arranged in a straight line in the sub-scanning direction is 2
k.

The light magenta ink has substantially the same hue as the normal magenta ink and has a higher density than the normal magenta ink. The same applies to light cyan ink. Note that the normal magenta ink and the normal cyan ink may be referred to as “dark magenta ink” and “dark cyan ink”.

When the actuator 41 shown in FIG. 17 is used, color printing can be executed according to the same scanning parameters as when the actuator 40 shown in FIG. 3 is used. Further, if the same printing method as in the first embodiment and the second embodiment is adopted, the three nozzle groups 40 on the right side of FIG.
Also for LM, 40LC, and 40K, an effect is obtained that the error accumulation positions of the respective nozzle groups do not substantially match.

When the actuator 41 shown in FIG. 17 is used, six colors can be printed using light-colored ink. Therefore, there is an advantage that the image quality of a color image can be improved as compared with the actuator 40 shown in FIG. is there. On the other hand, when the actuator 40 shown in FIG.
At the time of monochrome printing, the actuator 41 shown in FIG.
Since about three times the number of nozzles for black ink can be used, monochrome printing can be speeded up.

FIG. 18 is an explanatory diagram showing a second modification of the actuator. This actuator 42 is the same as that shown in FIG.
7, the dark magenta nozzle group 40M and the light magenta nozzle group 40LM of the actuator 41 of the first modified example shown in FIG.
Are exchanged, and the positions of the dark cyan nozzle group 40C and the light cyan nozzle group 40LC are exchanged. This actuator 42 also has substantially the same advantages as the actuator 41 shown in FIG.

FIG. 19 is an explanatory view showing a third modification of the actuator. This actuator 43 is shown in FIG.
In this embodiment, the color nozzle row and the black nozzle row 40K of the actuator 40 of the embodiment shown in FIG. For example, black nozzle row 40K
., # K47 are arranged in the left column, and even-numbered nozzles # K2, # K4,.
# K48 is arranged in the right column. Similarly, in the three chromatic nozzle groups 40Y, 40M, and 40C, the nozzles are arranged in a staggered manner. Thus, even when the nozzles are arranged in a staggered manner, the three chromatic nozzle groups 40Y, 40M, and 40C are still arranged in a straight line along the sub-scanning direction. That is, in this specification, the phrase "a plurality of nozzle groups are arranged in a straight line along the sub-scanning direction"
The nozzle groups only need to be arranged along a straight line as a whole, and a plurality of nozzles constituting each nozzle group need not necessarily be arranged on a straight line.

In the actuators shown in the above-described various embodiments and modifications, the nozzles for four colors or six colors are arranged in two rows. However, these may be arranged in one row. Alternatively, the arrangement may be made in three or more rows. For example, below the color nozzle group in FIG.
By providing 15 black nozzles at intervals, nozzle groups for four colors may be arranged in one row.

It is also possible to use a print head in which the interval between the nozzle groups of each color is set to the same value as the nozzle pitch k. In this case, when printing, by selecting some nozzles as unused nozzles, the interval between the nozzle groups of each color used is M × k dots (M is 2
(The integer above).

FIG. 20 is an explanatory view showing a fourth modification of the actuator. In the fourth modified example, a first actuator 44a including only a color nozzle row and a second actuator 44b including only a black nozzle row 40K
And two actuators are used. The nozzle groups of each color are arranged in a zigzag like in FIG. The only difference from FIG. 19 is that the color ink nozzle groups each have 16 nozzles, and the interval between the color ink nozzle groups is equal to the nozzle pitch k. In FIG. 20, the nozzle pitch k is set to four dots. "X" for color printing
Are not used, and 15 nozzles of each color ink nozzle group are used. For the black nozzle row, the nozzles used for cyan # C1 to #C
Fifteen nozzles # K33 to # 15 at the same sub-scanning position as
# K47 is used. As a result, the interval between the nozzle groups is substantially set to 2k.

FIG. 21 is an explanatory view showing a fifth modification of the actuator. This actuator 45 includes three color nozzle rows and one black nozzle row. The first color nozzle row is a nozzle group 4 for yellow.
0Y and a magenta nozzle group 40M.
The second color nozzle row is a light magenta nozzle group 40L.
M and a cyan nozzle group 40C. Third
Is composed of a light cyan nozzle group 40LC and a light black nozzle group 40LK. Note that “light black” means gray instead of black.

Although the nozzle groups are arranged in a straight line along the sub-scanning direction, they may be arranged in a staggered pattern as shown in FIGS. Black nozzle row 40K
Has 48 nozzles. Further, each nozzle group other than the black nozzle row 40K has 24 nozzles. At the time of color printing, the nozzles marked with “x” are not used, and the nozzles of each color ink nozzle group are not used.
Three nozzles are used. For the black nozzle row, the nozzles # LK1 to #LK used for light black are used.
23 nozzles # K25- at the same sub-scanning position as 23
# K47 is used. As a result, the interval between the nozzle groups is substantially set to 2k.

FIG. 22 is an explanatory view showing a sixth modification of the actuator. The actuator 46 also includes three color nozzle rows and one black nozzle row. The difference between the actuator 46 and the actuator 45 shown in FIG. 21 is only the positions of the nozzle groups other than the black nozzle row 40K and the yellow nozzle group 40Y, and therefore detailed description is omitted.

FIG. 23 is an explanatory view showing a seventh modification of the actuator. This actuator 47 has three nozzle rows. The first nozzle row includes a yellow nozzle group 40Y and a magenta nozzle group 40M. The second nozzle row includes a light magenta nozzle group 40LM and a cyan nozzle group 40C. The third nozzle row is a light cyan nozzle group 40LC.
And a black nozzle group 40K. Each nozzle group has 24 nozzles. At the time of color printing, the nozzles marked with “x” are not used, and 23 nozzles of each nozzle group are used. As a result, the interval between the nozzle groups is substantially set to 2k.

FIG. 24 is an explanatory diagram showing an eighth modification of the actuator. The actuator 48 is configured by arranging nozzle groups for six colors in a line in the sub-scanning direction.
Each nozzle group has eight nozzles. It is also possible to arrange the nozzle groups for each ink in a zigzag pattern. At the time of color printing, the nozzles marked with “x” are not used, and seven nozzles of each nozzle group are used. As a result, the interval between the nozzle groups is substantially set to 2k.

In the fourth to eighth modifications described above, one unused nozzle is set for each nozzle group. However, two or more unused nozzles may be set for each nozzle group. Good. As can be understood from these modifications, even when the interval between the nozzle groups is equal to the nozzle pitch k, by appropriately selecting the unused nozzles, the interval between the nozzle groups to be used can be reduced by M × k dots. Can be set to

The present invention is not limited to the above-described examples and embodiments, but can be implemented in various modes without departing from the scope of the invention.
For example, the following modifications are possible.

(1) In the above embodiment, only the case where the number of scan repetitions s is 1 has been described. However, the present invention can be applied to the case where the number of scan repetitions s exceeds 1. is there.

(2) In some printing apparatuses, the dot pitch in the main scanning direction (recording resolution) and the dot pitch in the sub-scanning direction can be set to different values. In this case, the parameters related to the main scanning direction (for example, the pixel pitch on the raster line) are defined by the dot pitch in the main scanning direction, while the parameters related to the sub-scanning direction (for example, the nozzle pitch k and the sub-scanning). The feed amount L) is defined by the dot pitch in the sub-scanning direction.

(3) The present invention is also applicable to a drum scan printer. In a drum scan printer, the drum rotation direction is the main scanning direction, and the carriage traveling direction is the sub scanning direction. In addition, the present invention can be applied not only to an ink jet printer but also to a printing apparatus that generally performs recording on the surface of a print medium using a print head having a plurality of dot forming element arrays. here,
“Dot forming element” means a component for forming dots, such as an ink nozzle in an ink jet printer. Such printing devices include, for example, facsimile machines and copy machines.

(4) In the various embodiments and modifications described above, only one actuator is arranged in the sub-scanning direction. However, by arranging a plurality of actuators in the sub-scanning direction, the various It is also possible to realize the embodiment and the same nozzle arrangement as the embodiment. For example, the arrangement of the three chromatic nozzle groups 40Y, 40M, and 40C in the first embodiment shown in FIG. 3 is realized by arranging three actuators each including a nozzle group for one color in the sub-scanning direction. It is possible. At this time, the black nozzle group may be realized by one actuator, or may be realized by three actuators arranged in the sub-scanning direction. The arrangement of the eighth modification shown in FIG. 24 includes six nozzle groups each including one color nozzle group.
This can be realized by arranging one actuator in the sub-scanning direction. At this time, the nozzles marked with “x” in FIG. 24 are not formed in any of the actuators, and as a result, the interval between the ends of each nozzle group is 2k.

(5) In the above embodiment, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware. You may do so. For example, the system controller 5
4 (FIG. 2) may be partly executed by the host computer 100.

A computer program for realizing such a function is provided in a form recorded on a computer-readable recording medium such as a floppy disk or a CD-ROM. The host computer 100 reads the computer program from the recording medium and transfers it to an internal storage device or an external storage device. Alternatively, from the program supply device to the host computer 1 via a communication path.
00 may be supplied with a computer program. When implementing the functions of the computer program, the computer program stored in the internal storage device is executed by the microprocessor of the host computer 100. Further, the host computer 100 may directly execute a computer program recorded on a recording medium.

In this specification, the host computer 100 is a concept including a hardware device and an operation system, and means a hardware device that operates under the control of the operation system. The computer program causes the host computer 100 to realize the functions of the above-described units. Some of the above functions are not application programs,
It may be realized by an operation system.

In the present invention, the “computer-readable recording medium” is not limited to a portable recording medium such as a flexible disk or a CD-ROM, but may be an internal storage such as various RAMs and ROMs. It also includes a device and an external storage device fixed to the computer such as a hard disk.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a main configuration of a color inkjet printer 20 as one embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of the printer 20.

FIG. 3 is an explanatory diagram showing an arrangement of nozzles formed on a bottom surface of an actuator 40.

FIG. 4 is an explanatory diagram showing basic conditions of a general dot recording method when the number of scan repetitions s is 1;

FIG. 5 is an explanatory diagram showing basic conditions of a general dot recording method when the number of scan repetitions s is 2 or more.

FIG. 6 is an explanatory diagram showing scanning parameters in the printing method according to the first embodiment of the present invention.

FIG. 7 is an explanatory view showing nozzles used in the first embodiment.

FIG. 8 is an explanatory diagram showing nozzles that print each raster line within an effective printing range in each pass of the first embodiment.

FIG. 9 is an explanatory diagram showing nozzles used in a first comparative example.

FIG. 10 is an explanatory diagram showing nozzles that print each raster line within an effective print range in each pass of the first comparative example.

FIG. 11 is an explanatory diagram showing equivalent nozzle positions.

FIG. 12 is an explanatory diagram showing scanning parameters in a printing method according to a second embodiment of the present invention.

FIG. 13 is an explanatory diagram showing nozzles used in the second embodiment.

FIG. 14 is an explanatory diagram showing nozzles that print each raster line within an effective printing range in each pass of the second embodiment.

FIG. 15 is an explanatory diagram showing nozzles used in a second comparative example.

FIG. 16 is an explanatory diagram showing nozzles that print each raster line within an effective print range in each pass of the second comparative example.

FIG. 17 is an explanatory view showing a first modification of the actuator.

FIG. 18 is an explanatory view showing a second modified example of the actuator.

FIG. 19 is an explanatory view showing a third modified example of the actuator.

FIG. 20 is an explanatory view showing a fourth modification of the actuator.

FIG. 21 is an explanatory view showing a fifth modification of the actuator.

FIG. 22 is an explanatory view showing a sixth modification of the actuator.

FIG. 23 is an explanatory view showing a seventh modification of the actuator.

FIG. 24 is an explanatory view showing an eighth modification of the actuator.

FIG. 25 is an explanatory diagram showing an example of an interlace recording method.

FIG. 26 is an explanatory diagram showing an example of an overlap recording method.

[Explanation of symbols]

 Reference Signs List 20 color ink jet printer 22 paper stacker 24 paper feed roller 26 platen plate 28 carriage 30 carriage motor 31 paper feed motor 32 traction belt 34 guide rail 36 print head 40 actuator 50 reception buffer memory 52 image buffer 54 system controller 61 main scanning driver 62 sub-scan driver 63 head driver 100 host computer

Claims (10)

[Claims] 1. A printing apparatus for printing an image by recording dots on a surface of a print medium, comprising: a print head including a plurality of dot forming elements for forming dots on the print medium; A main scanning drive unit for performing main scanning by driving at least one of a head and the printing medium; and forming dots by driving at least a part of the plurality of dot forming elements during the main scanning. A head drive unit that drives at least one of the print head and the print medium to perform sub-scan each time the main scan is completed; and a control unit that controls the respective units. The print head includes a plurality of dot forming element groups for forming dots using mutually different inks, and the plurality of dot forming element groups are arranged in a predetermined order along the sub-scanning direction. The plurality of dot forming elements included in each dot forming element group are provided so that the pitch k of the dot forming elements measured along the sub-scanning direction is equal to each other. The element pitch k is set to a value that is an integral multiple of twice or more the pitch of the dots on the print medium in the sub-scanning direction. The control unit controls the interval of the pitch k for each dot forming element group. N (N is an integer of 2 or more) of the same number consecutively arranged in
Forming dots on the print medium using the respective dot forming elements, and the N dot forming elements used in each dot forming element group are located between each group relating to the N dot forming elements. Is M times the pitch k of the dot forming elements (M is 2
A printing apparatus selected so as to obtain a value M × k of the above integer. 2. The printing apparatus according to claim 1, wherein the print head is configured such that an interval between dot forming elements existing at an end of each dot forming element group is m times the pitch k of the dot forming elements (m). a printing apparatus formed so as to have a value m × k of (m is an integer of 2 or more). 3. The printing apparatus according to claim 1, wherein the integer M is set to a value other than (N × n + 1) (n is an integer of 1 or more). 4. The printing apparatus according to claim 1, wherein the sub-scanning drive unit performs two-time printing of dots on two adjacent main scanning lines. A printing apparatus that performs sub-scanning in accordance with an interlace method in which sub-scanning is performed a plurality of times during main scanning. 5. A printing method for printing an image by recording dots on the surface of a printing medium, comprising: (a) a printing head comprising: i) a plurality of dots for forming dots using mutually different inks; A plurality of dot forming elements arranged in a predetermined order along the sub-scanning direction, and ii) a plurality of dot forming elements included in each dot forming element group are arranged in the sub-scanning direction. And iii) the pitch k of the dot forming elements is equal to or more than twice the pitch of the dots on the print medium in the sub-scanning direction. Preparing a print head, which is set to an integer multiple, and (b) for each dot forming element group, an equal number of N dots continuously arranged at the pitch k. Forming a dot on the print medium using each of the dot forming elements. The N dot forming elements used in each dot forming element group in the step (b) are the N Printing, wherein an interval between each group of dot forming elements is selected to be a value M × k which is M times (M is an integer of 2 or more) the pitch k of the dot forming elements. Method. 6. The printing method according to claim 5, wherein in the print head, the interval between the dot forming elements existing at the end of each dot forming element group is m times the pitch k of the dot forming elements. (m is an integer of 2 or more). 7. The printing method according to claim 5, wherein the integer M is set to a value other than (N × n + 1) (n is any integer of 1 or more). 8. The printing method according to claim 5, wherein the sub-scanning drive unit performs two-time printing of dots on two adjacent main scanning lines. A printing method for performing sub-scanning in accordance with an interlacing method in which sub-scanning is performed a plurality of times during main scanning. 9. A computer-readable recording recording a computer program for causing a computer including a printing device that prints an image by recording dots on the surface of a print medium using a print head to execute color printing. A print medium comprising: i) a plurality of dot forming elements for forming dots using mutually different inks, the plurality of dot forming elements being arranged in a predetermined order along the sub-scanning direction; Ii) a plurality of dot forming elements included in each dot forming element group are provided such that pitches k of the dot forming elements measured along the sub-scanning direction are equal to each other; and iii. The pitch k of the dot forming elements is set to a value that is an integral multiple of twice or more the pitch of the dots on the print medium in the sub-scanning direction. Wherein the recording medium forms dots on the print medium using an equal number of N dot forming elements that are continuously arranged at intervals of the pitch k for each dot forming element group. The function and the N dot forming elements used in each dot forming element group are selected, and the interval between each group relating to the N dot forming elements is determined by the pitch k of the dot forming element.
A computer program for causing a computer to execute the selection so as to have a value M × k (M is an integer of 2 or more) times M. Recording medium. 10. A print head for a printing apparatus for printing an image by recording dots on a surface of a print medium, comprising: a plurality of dot forming element groups for forming dots using mutually different inks. The plurality of dot forming element groups are arranged in a predetermined order along the sub-scanning direction, and the plurality of dot forming elements included in each dot forming element group are measured along the sub-scanning direction. The pitch k of the dot forming elements is provided so as to be equal to each other, and the interval between the dot forming elements existing at the end of each dot forming element group is m times the pitch k of the dot forming elements (m
Is an integer greater than or equal to 2) m × k.