JP3740918B2 - Color printing apparatus and printing method using vertical array head, and recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for performing color printing using a print head that forms dots of a plurality of colors.
[0002]
[Prior art]
Examples of the printing apparatus that records dots while the print head scans in the main scanning direction and the sub-scanning direction include a serial scan printer and a drum scan printer. As one of techniques for improving image quality in this type of printer, particularly an ink jet printer, an “interlace method” disclosed in US Pat. No. 4,198,642, Japanese Patent Application Laid-Open No. 53-2040, and the like. There is a technology called.
[0003]
FIG. 25 is an explanatory diagram illustrating an example of an interlace method. In this specification, the following parameters are used as parameters for defining the printing method.
[0004]
N: Number of nozzles [pieces]
k: Nozzle pitch [dot],
s: number of scan repetitions,
D: Nozzle density [piece / 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 (dot pitch w) the center point interval of the nozzles in the print head is. In the example of FIG. 25, k = 2. The number of scan repetitions s [times] is a number indicating how many main scans each main scan line is filled with dots. Hereinafter, the main scanning line is referred to as “raster”. In the example of FIG. 25, since each raster is filled in by one main scan, s = 1. As will be described later, when s is 2 or more, dots are intermittently formed 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 by one sub-scan. The dot pitch w [inch] is the dot pitch in the printed image. In general, w = 1 / (D · k) and k = 1 / (D · w) are established.
[0006]
In FIG. 25, circles including two-digit numbers indicate dot recording positions. As shown in the legend at the lower left of FIG. 25, among the two-digit numbers in the circle, the number on the left side indicates the nozzle number, and the number on the right side indicates the printing order (how many main scans are recorded). ).
[0007]
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 interval between the center points of adjacent nozzles is set to an integer of 2 or more, and the number of nozzles N and the nozzle pitch k are selected to be an integer that is relatively prime. . The sub-scan feed amount L is set to a constant value given by N / (D · k).
[0008]
This interlace 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 are variations in the nozzle pitch and ejection characteristics, it is possible to alleviate these effects and improve the image quality.
[0009]
As another technique aiming at image quality improvement in a color inkjet printer, there is a technique called “overlap method” or “multi-scan method” disclosed in Japanese Patent Laid-Open No. 3-207665, Japanese Patent Publication No. 4-19030, and the like. .
[0010]
FIG. 26 is an explanatory diagram showing an example of the overlap method. In this overlap method, eight nozzles are classified into two sets of nozzle groups. The first group of nozzles is composed of four nozzles having an even number of nozzle numbers (the number on the left side in the circle), and the second group of nozzles is composed of four nozzles having an odd number of nozzles. It consists of a nozzle. In one main scan, dots are formed 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 group of nozzle groups 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, 1) are The recording position is shifted by one dot pitch in the main scanning direction. 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.
[0011]
Also in the overlap method, the nozzle pitch k is set to an integer of 2 or more, as in the interlace method. However, the number of nozzles N and the nozzle pitch k are not relatively prime. Instead, the value N / s obtained by dividing the number of nozzles N by the number of scan repetitions s and the nozzle pitch k are relatively prime. It is chosen as an integer. The sub-scan feed amount L is set to a constant value given by N / (s · D · k). Note that “integers A and B are relatively prime” means that the integers A and B have no common divisor other than 1.
[0012]
In this overlap method, dots on each raster are not recorded by the same nozzle, but are recorded using a plurality of nozzles. Therefore, even when there are variations in nozzle characteristics (pitch, ejection characteristics, etc.), it is possible to prevent the influence of specific nozzle characteristics from affecting one entire raster, and as a result, image quality can be improved. .
[0013]
[Problems to be solved by the invention]
By the way, a mechanical error occurs in the sub-scan feed, and this error tends to accumulate as the sub-scan feed is repeated. In the interlace method, a plurality of sub-scan feeds may be performed while two adjacent raster lines are recorded. At this time, due to the accumulated error of the sub-scan feed, there is a slight variation (wide or narrow) between the two raster lines. Such a large variation portion is observed as so-called banding (a striped image quality degradation portion extending in the main scanning direction).
[0014]
In recent years, in order to alleviate the occurrence of such banding, various dot recording methods in which the sub-scan feed amount is devised have been proposed. However, conventionally, little consideration has been given to the relationship between the occurrence positions of banding relating to different ink dots, that is, the relation between the occurrence positions of accumulated errors in the sub-scan feed amount relating to different ink dots. For this reason, the occurrence positions of banding between dots of different inks may overlap, and the image quality may be deteriorated.
[0015]
The present invention has been made to solve the above-described problems in the prior art, and it is possible to improve the image quality by well adjusting the relationship between the occurrence positions of accumulated errors in the sub-scan feed amount for different ink dots. The purpose is to provide technology that can be used.
[0016]
[Means for solving the problems and their functions and effects]
  In order to solve at least a part of the above-described problems, the present invention uses a print head having the following three characteristics i) to iii). i) A plurality of sets of dot forming element arrays for forming dots using different inks, the plurality of sets of dot forming element arrays being 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 is the pitch k of the dot forming elements measured along the sub-scanning direction.・ W (k is an integer, w is a dot pitch)Are provided to be equal to each other. iii) Pitch k of the dot forming element・ WIs the pitch of the dots on the printing medium in the sub-scanning direction.wIs set to an integer multiple of 2 or more.
[0017]
  Further, for each set of dot forming element arrays, dots are formed on the print medium using N dot forming elements having the same number arranged in succession at intervals of the pitch k. Further, in the N dot forming elements used in each set, an interval between each set of the N dot forming elements is M times the pitch k of the dot forming elements (M is 2 or more ( An integer other than N × n + 1), where n is an arbitrary integer equal to or greater than 1) is selected to be a value M × k.Further, regarding the dot formation of each ink, the main scanning and the sub scanning are controlled so as to satisfy the following three conditions (i) to (iii):
(I) The number of sub-scan feeds for one cycle repeatedly executed at the time of printing is multiplied by an integer k indicating the pitch k · w of dot forming elements and the number of main scans s performed on each main scan line. Equal to (k × s);
(Ii) When the remainder obtained by dividing the accumulated value of the sub-scan feed amount L in each cycle by the integer k indicating the dot forming element pitch is defined as an offset F, in one cycle, the offset F is A value in the range of 0 to (k−1), each value being repeated s times;
(Iii) The cumulative value ΣL of (k × s) sub-scan feed amounts L in one cycle is a value obtained by multiplying the number N of dot formation elements by an integer k indicating the dot formation element pitch (N × k). )be equivalent to.
[0018]
  In the present invention, the interval between each pair of dot forming elements used in each pair is M times the pitch k (M is 2 or more).And an integer other than (N × n + 1), where n is any integer greater than or equal to 1) Value M × k, the sub-scan feed amount cumulative error occurrence positions for different ink dots do not always coincide. Therefore, the occurrence of banding can be alleviated and the image quality can be improved.
[0019]
  The print head is attached to the end of each set of dot forming element arrays.ImplementedThe interval between the dot forming elements is m times the pitch k of the dot forming elements (m is 2 or more).Less than MIt is preferable to be formed so as to have a value m × k).
[0020]
  Here, "at the end of each set of dot forming element arraysImplementedThe “dot forming element” means a dot forming element existing at the end of each set of arrays among all dot forming elements including those not used. If the print head as described above is used, even if almost all dot forming elements provided in the print head are used, the interval between each set of dot forming elements used in each set is set to a pitch k. M times (M is 2 or more)Less than MIt is possible to set the value to be M × k.
[0022]
Further, the sub-scan is performed according to an interlace method in which a plurality of sub-scan feeds may be performed between two main scans for executing dot recording on two adjacent main scan lines. Can do. In such an interlace method, the accumulated error of the sub-scan feed amount tends to be large in two adjacent main scan lines. Therefore, with such an interlace method, “the occurrence position of the cumulative error of the sub-scan feed amount regarding the dots of different inks does not always coincide, and the occurrence of banding can be reduced and the image quality can be improved.” The effect becomes more remarkable.
[0023]
As specific modes of the present invention, various modes such as a printing apparatus, a printing method, a print head, and a recording medium can be taken.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A. Overall configuration of the device:
Next, embodiments 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 an 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), a platen plate 26, a carriage 28, a step motor 30, and 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 large number of nozzles is mounted on the carriage 28.
[0025]
The printing paper P is taken up by the paper feed roller 24 from the paper stacker 22 and 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 in the main scanning direction along the guide rail 34. The main scanning direction is perpendicular to the sub-scanning direction.
[0026]
FIG. 2 is a block diagram showing an 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 drive driver 61 that drives the carriage motor 30, a sub-scanning drive driver 62 that drives the paper feed motor 31, and a head drive driver 63 that drives the print head 36.
[0027]
A printer driver (not shown) of the host computer 100 determines various parameter values that define the printing operation based on a printing method (described later) designated 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 print data from the reception buffer memory 50, and sends control signals to the drivers 61, 62, and 63 based on the information.
[0028]
The image buffer 52 stores image data of a plurality of color components obtained by separating the print data received by the reception buffer memory 50 for each color component. The head drive driver 63 reads the image data of each color component from the image buffer 52 in accordance with a control signal from the system controller 54 and drives the nozzle array of each color provided in the print head 36 in accordance with this.
[0029]
B. Print head configuration:
FIG. 3 is an explanatory diagram 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, a color nozzle row and a black nozzle row arranged on a straight line along the sub-scanning direction are formed. The “actuator” means an ink discharge mechanism including a nozzle and a piezo element. In the present specification, the “nozzle row” is also referred to as a “nozzle array”.
[0030]
The black nozzle row has 48 nozzles # K1 to # K48. These nozzles # K1 to # K48 are 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.
[0031]
The color nozzle row includes a yellow nozzle group 40Y, a magenta nozzle group 40M, and a cyan nozzle group 40C. In this specification, the nozzle group for chromatic ink is also referred to as a “chromatic nozzle group”. The yellow nozzle group 40Y has fifteen nozzles # Y1 to # Y15, and the pitch of these fifteen nozzles is the same as the nozzle pitch k of the black nozzle row. The same applies to the magenta nozzle group 40M and the cyan nozzle group 40C. The “x” mark 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 indicates that no nozzle is formed at that position. ing. 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. The same applies to the interval between the nozzle # M15 at the lower end of the magenta nozzle group 40M and the nozzle # C1 at the upper end of the cyan nozzle group 40C. In other words, the intervals between the yellow, magenta, and cyan nozzle groups are set to a value twice the nozzle pitch k.
[0032]
The nozzles of the color nozzle groups 40Y, 40M, and 40C are arranged at the same sub-scanning position as the nozzles of the black nozzle row 40K. However, among the 48 nozzles # K1 to # K48 in the black nozzle row 40K, the chromatic ink is located at the corresponding position for the 16th, 32nd and 48th nozzles # K16, # K32, and # K48. No nozzle is provided.
[0033]
During printing, ink droplets are ejected from each nozzle while the print head 36 is moving in the main scanning direction together with the carriage 28 (FIG. 1). However, depending on the printing method, not all nozzles are always used, and only some nozzles may be used.
[0034]
C. Basic conditions for general printing methods:
Before describing the printing method in the embodiment of the present invention, first, basic conditions required for a general printing method will be described first. In the following description, “printing method” is referred to as “dot recording method”.
[0035]
FIG. 4 is an explanatory diagram for illustrating basic conditions of a general dot recording method when the scan repetition number s is one. FIG. 4A shows an example of sub-scan feed when four nozzles are used, and FIG. 4B shows the parameters of the dot recording method. In FIG. 4A, solid line circles including numerals 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 every time one main scanning is completed. In practice, however, feeding in the sub-scanning direction is realized by moving the paper by the paper feed motor 31 (FIG. 2).
[0036]
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. Accordingly, every time the sub-scan feed is performed, the positions of the four nozzles are shifted in the sub-scanning direction by 4 dots. When the scan repetition number s is 1, each nozzle can record all the dots (also referred to as “pixels”) on the respective raster. At the right end of FIG. 4A, the number of the nozzle that records dots on each raster is shown. Note that in the raster drawn with a broken line extending in the right direction (main scanning direction) from the circle indicating the position of the nozzle in the sub-scanning direction, at least one of the upper and lower rasters cannot be recorded. Is done. On the other hand, the raster drawn with a solid line extending in the main scanning direction is a range in which the previous and subsequent rasters can be recorded as dots. The range in which recording can actually be performed in this way is hereinafter referred to as an effective recording range (effective printing range) or a “printable region”.
[0037]
FIG. 4B shows various parameters relating to this dot recording method. The parameters of the dot recording method include nozzle pitch k [dots], number of used nozzles N [pieces], number of scan repetitions s, number of effective nozzles Neff [pieces], and sub-scan feed amount L [dots]. include.
[0038]
In the example of FIG. 4, the nozzle pitch k is 3 dots. The number of used nozzles N is four. The number N of used nozzles is the number of nozzles actually used among the plurality of mounted nozzles. The number of scan repetitions s means that dots are intermittently formed every (s-1) dots in one main scan. Therefore, the scan repetition number s is also equal to the number of nozzles used to record all dots on each raster. In the case of FIG. 4, the scan repetition number s is 1. The effective nozzle number Neff is a value obtained by dividing the used nozzle number N by the scan repetition number 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.
[0039]
The table in FIG. 4B shows the sub-scan feed amount L, the cumulative value ΣL, and the nozzle offset F after each sub-scan feed for each sub-scan feed. Here, the offset F refers to the position after the sub-scan feed when the periodic position of the first nozzle that is not subjected to the sub-scan feed (positions every 4 dots in FIG. 4) is the reference position of the offset 0. This is a value indicating how many dots the nozzle position is away from the reference position in the sub-scanning direction. For example, as shown in FIG. 4A, the first sub-scan feed moves the nozzle position in the sub-scan direction by the sub-scan feed amount L (4 dots). 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 is moved by ΣL = 8 dots from the initial position, and the offset F is 2. The nozzle position after the third sub-scan feed is moved by ΣL = 12 dots from the initial position, and the offset F is zero. Since the nozzle offset F returns to 0 by three sub-scan feeds, all the dots on the raster in the effective recording range can be recorded by repeating this cycle with three sub-scans as one cycle. .
[0040]
As can be seen from the above example, when the position of the nozzle is away from the initial position by an integral multiple of the nozzle pitch k, the offset F is zero. The offset F is given by the remainder (ΣL)% k obtained by dividing the cumulative value ΣL of the sub-scan feed amount L by the nozzle pitch k. Here, “%” is an operator indicating that the remainder of division is taken. If the initial position of the nozzle is considered as a periodic position, the offset F can be considered to indicate a phase shift amount from the initial position of the nozzle.
[0041]
When the number of scan repetitions s is 1, the following conditions must be satisfied in order to prevent missing or overlapping rasters in the effective recording range.
[0042]
Condition c1: The number of sub-scan feeds in one cycle is equal to the nozzle pitch k.
[0043]
Condition c2: Nozzle offset F after each sub-scan feed in one cycle is a different value in the range of 0 to (k−1).
[0044]
Condition c3: The sub-scan average feed amount (ΣL / k) is equal to the number N of used nozzles. In other words, the cumulative value ΣL 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 and the nozzle pitch k.
[0045]
Each of the above conditions can be understood by thinking as follows. Since there are (k-1) rasters between adjacent nozzles, recording is performed on these (k-1) rasters in one cycle, and the nozzle reference position (position where the offset F is zero). In order to return to, the number of sub-scan feeds in one cycle is k times. If the number of sub-scan feeds in one cycle is less than k times, the recorded raster will be lost. On the other hand, if the number of sub-scan feeds in one cycle is greater than k times, the recorded rasters will overlap. Therefore, the first condition c1 is satisfied.
[0046]
When the number of sub-scan feeds in one cycle is k times, only when the offset F value after each sub-scan feed is a different value in the range of 0 to (k-1), missing or overlapping rasters are recorded. Disappears. Therefore, the second condition c2 is satisfied.
[0047]
If the first and second conditions are satisfied, each of the N nozzles records k rasters in one cycle. Therefore, N × k rasters are recorded in one cycle. On the other hand, if the third condition c3 is satisfied, as shown in FIG. 4A, the nozzle position after one cycle (after k sub-scan feeds) is N × k from the initial nozzle position. Comes to a raster away position. Therefore, by satisfying the first to third conditions c1 to c3, it is possible to eliminate omissions and overlaps in the recorded raster in the range of these N × k rasters.
[0048]
FIG. 5 is an explanatory diagram for illustrating basic conditions of a general dot recording method when the scan repetition number s is 2 or more. When the scan repetition number s is 2 or more, the same raster is recorded by s different nozzles. Hereinafter, a dot recording method in which the scan repetition number s is 2 or more is referred to as an “overlap method”.
[0049]
The dot recording method shown in FIG. 5 is obtained by changing the scan repetition number s and the sub-scan feed amount L among the parameters of the dot recording method shown in FIG. 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 feed are indicated by diamonds. As shown at the right end of FIG. 5A, the pixel positions recorded after the odd-numbered sub-scan feed are the same as the pixel positions recorded after the even-numbered sub-scan feed and one dot in the main scanning direction. It's off. Therefore, a plurality of dots on the same raster are intermittently recorded by two different nozzles. For example, the uppermost raster in the effective recording range is intermittently recorded every other dot by the second nozzle after the first sub-scan feed, and then 1 by the 0th nozzle after the fourth sub-scan feed. Recorded intermittently every other dot. In general, in the overlap method, each nozzle is driven at an intermittent timing so that (s-1) dot recording is prohibited after one dot is recorded during one main scan.
[0050]
In the overlap method, since the positions in the main scanning direction of a plurality of nozzles that record the same raster 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 FIG. For example, after the first sub-scan feed, a dot at a position indicated by a circle is recorded without performing a shift in the main scan direction, and after a fourth sub-scan feed, a shift in the main scan direction is performed and a position indicated by a rhombus It is also possible to record the dots.
[0051]
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 sub-scan feed from the first to sixth times includes a value in the range of 0 to 2 twice. Further, the change in the offset F after the third sub-scan feed from the first time to the third time is equal to the change in the offset F after the third sub-scan feed from the fourth time to the sixth time. As shown at the left end of FIG. 5A, six sub-scan feeds in one cycle can be divided into two sets of small cycles of three times. At this time, one cycle of the sub-scan feed is completed by repeating the small cycle s times.
[0052]
In general, when the scan repetition number s is an integer of 2 or more, the first to third conditions c1 to c3 described above are rewritten as the following conditions c1 'to c3'.
[0053]
Condition c1 ′: The number of sub-scan feeds in one cycle is equal to a value (k × s) obtained by multiplying the nozzle pitch k and the scan repetition number s.
[0054]
Condition c2 ': 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.
[0055]
Condition c3 ′: The sub-scan average feed amount {ΣL / (k × s)} is equal to the effective nozzle number Neff (= N / s). In other words, the cumulative value ΣL of the sub-scan feed amount L per cycle is equal to a value {Neff × (k × s)} obtained by multiplying the effective nozzle number Neff and the sub-scan feed number (k × s).
[0056]
The above conditions c1 'to c3' are satisfied even when the scan repetition number s is 1. Accordingly, the conditions c1 'to c3' are conditions that 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 the dots to be recorded from being missing or overlapping in the effective recording range. However, in the case of employing the overlap method (when the scan repetition number s is 2 or more), it is also necessary to have a condition that the recording positions of the nozzles that record the same raster are shifted in the main scanning direction.
[0057]
Depending on the recording method, partial overlap may be performed. “Partial overlap” refers to a recording method in which a raster recorded by one nozzle and a raster recorded by a plurality of nozzles are mixed. Even in such a recording method using partial overlap, the effective nozzle number Neff can be defined. For example, in a partial overlap method in which two nozzles of four nozzles cooperate to record the same raster, and the remaining two nozzles each record one raster, The effective nozzle number Neff is three. Also in the case of such a partial overlap method, the above three conditions c1 'to c3' are satisfied.
[0058]
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, when the number of scan repetitions s is 2, a number of rasters equal to the number of used nozzles N can be recorded in two main scans, so the net of rasters that can be recorded in one main scan Is equal to N / s (ie, Neff).
[0059]
D. First embodiment:
FIG. 6 is an explanatory diagram showing scanning parameters in the printing method according to the first embodiment of the present invention. In the first embodiment, the nozzle pitch k is 6 dots, the scan repetition number s is 1, the number of used nozzles N is 13, and the effective nozzle number Neff is 13.
[0060]
In the table at the bottom of FIG. 6, parameters relating to the first to seventh passes are shown. In the present specification, one main scan is also referred to as “pass”. In this table, for each pass, the sub-scan feed amount L executed immediately before the pass, the accumulated value ΣL, and the offset F are shown. The sub-scan feed amount L is a constant value of 13 dots. A printing method (scanning method) in which the sub-scan feed amount L is constant is called “regular feed”. Note that the scanning parameters of the first embodiment satisfy the above-described conditions c1 'to c3'.
[0061]
FIG. 7 is an explanatory diagram showing nozzles used in the first embodiment. The actuator 40 of FIG. 7 is the same as that shown in FIG. 3, but only some of the nozzles are used in the first embodiment. In FIG. 7, the nozzles used in the first embodiment are indicated by white circles, while the 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, only 13 nozzles at the same sub-scanning position as the cyan use nozzles # C1 to # C13 are used. Thus, if the same number of nozzles are used for each of the four inks, the dots of each ink can be formed without omission or duplication by performing scanning according to the scanning parameters common to the nozzles for each. it can.
[0062]
In the present specification, the nozzle group for each ink composed of the nozzles used is also referred to as a “used nozzle group”. Further, the nozzle group for each ink provided in the actuator 40 is also referred to as a “mounting nozzle group”.
[0063]
As the use nozzles of the respective inks, those that are continuously arranged at the nozzle pitch k are selected. The interval between the lower nozzle # Y13 of the yellow nozzle group and the upper nozzle # M1 of the magenta nozzle group is 4k (ie, 24 dots). Similarly, the interval between the nozzle # M13 at the lower end of the magenta use nozzle group and the nozzle # C1 at the upper end of the cyan use nozzle group is also 4k.
[0064]
FIG. 8 is an explanatory diagram illustrating nozzles that record each raster line within the effective recording range in each pass of the first embodiment. In pass 1, the three nozzles # C11 to # C13 for cyan execute dot recording on the first, seventh, and thirteenth effective raster lines, respectively. The “effective raster line” means a raster line within the effective recording range. In FIG. 8, the leading sign “#” 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.
[0065]
In pass 2, the recording target position of the actuator 40 on the printing paper is moved from pass 1 by 13 dots in the sub-scanning direction. 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 cumulative value ΣL of the feed amount L by k) is 1 dot. Therefore, in pass 2, it appears that the raster line one line lower than the raster line that was recorded in pass 1 appears to be recorded. Of course, in reality, the lower 13 raster lines are to be recorded. In the first embodiment, since the sub-scan feed amount L is a constant value of 13 dots, each time a sub-scan feed is performed, the position of the raster line to be recorded moves downward one by one. appear.
[0066]
For cyan ink, as will be described below, the cumulative value of the sub-scan feed error is the largest at the position Cmis between the sixth and seventh raster lines. The sixth raster line is recorded in pass 6, while the seventh raster line is recorded in pass 1. Accordingly, the sub-scan feed is performed five times between the pass 1 for recording the seventh raster line and the pass 6 for recording the sixth raster line. Accordingly, five sub-scan feed errors are accumulated between the sixth and seventh raster lines. Similarly, five sub-scan feed errors are accumulated for cyan ink between the 12th and 13th raster lines.
[0067]
From the same consideration as described above, it is understood that the accumulated value of the sub-scan feed error is relatively large for the magenta ink at the position Mmis between the seventh and eighth raster lines. For yellow ink, the accumulated value of the sub-scan feed error is relatively large at the position Ymis between the ninth and tenth raster lines. Hereinafter, a position where the accumulated value of the sub-scan feed error is relatively large is referred to as an “error accumulated position”.
[0068]
As can be understood from the above description, in the first embodiment, the error accumulation position differs for each chromatic color ink and does not match. At the error accumulation position, banding (striped image quality degradation portion extending in the main scanning direction) tends to occur. However, according to the present embodiment, since the error accumulation position is different for each chromatic ink, banding at these positions can be made inconspicuous.
[0069]
FIG. 9 is an explanatory view showing an actuator used in the first comparative example. In the actuator 40 ', each chromatic nozzle group 40Y', 40M ', 40C' is composed of 13 nozzles. Further, the interval between the nozzles at the end of each chromatic color nozzle group 40Y ', 40M', 40C 'is equal to the nozzle pitch k. That is, in the actuator 40 ′ of FIG. 9, 13 nozzles for each chromatic color ink used in the first embodiment are continuously arranged at the nozzle pitch k. The black nozzle group 40 'is also composed of 39 nozzles arranged at the nozzle pitch k. In the first comparative example, such an actuator 40 'is used, and printing is executed according to the same scanning parameters as the scanning parameters of the first embodiment shown in FIG.
[0070]
FIG. 10 is an explanatory diagram illustrating nozzles that record 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 positions between the sixth and seventh raster lines and positions between the twelfth and thirteenth raster lines. Match. In such a case, banding is conspicuous and image quality is likely to deteriorate.
[0071]
As can be seen by comparing the used nozzles shown in FIGS. 7 and 9, the difference between the first embodiment and the first comparative example is only the interval between the used nozzle groups. That is, in the first embodiment, the interval between the used color nozzle groups is set to a value 4k that is four times the nozzle pitch k, whereas in the first comparative example, the interval between the used nozzle groups is set to the nozzle. The same value as the pitch k is set. It can be understood that such a difference in the interval between the used nozzle groups appears as a difference in the generation positions of error accumulation positions Cmis, Mmis, and Ymis as shown in FIGS.
[0072]
In order to prevent the error accumulation positions of the adjacent nozzle groups along the sub-scanning direction as much as possible, in general, the interval between adjacent used nozzle groups is M times the nozzle pitch k (M is 2 or more). It is preferable to select the nozzle to be used so as to be an integer).
[0073]
However, it is preferable that the interval between the nozzle groups used along the sub-scanning direction is set as follows. FIG. 11 is an explanatory diagram showing equivalent nozzle positions in the printing method shown in FIG. As described with reference to FIG. 4, when the number of scan repetitions s is 1, one cycle of scanning includes k sub-scan feeds. Accordingly, the movement amount of the nozzle group in the sub-scan feed for one cycle is N × 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 recording operation is executed 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, it can be seen that 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) dots. In general, the interval between the lower end nozzle of the nozzle group at the initial position of the first cycle and the upper end nozzle of another equivalent nozzle group can be expressed as (N × n + 1) k dots. Here, n is an arbitrary integer of 0 or more.
[0074]
If the used nozzle groups of different inks are arranged at equivalent nozzle group positions as shown in FIG. 11, the error accumulation positions for these inks coincide with each other. In order to avoid such a case, the interval between adjacent used nozzle groups should be set to a value other than (N × n + 1) k dots (N is the number of used nozzles, and n is an arbitrary integer greater than or equal to 1). Is preferred. Here, n is set to 1 or more instead of 0 or more, as described above, when the interval between adjacent used nozzle groups is set to M times the nozzle pitch k (M is an integer of 2 or more), n = This is because the case of 0 is excluded.
[0075]
E. Second embodiment:
FIG. 12 is an explanatory diagram showing scanning parameters in the printing method of the second embodiment of the present invention. In the second embodiment, the nozzle pitch k is 6 dots, the scan repetition number s is 1, the number of used nozzles N is 15, and the effective nozzle number Neff is 15.
[0076]
The table at the bottom of FIG. 12 shows parameters for each pass from the first time to the seventh time. As the sub-scan feed amount L, an array of three different values of 14, 15, and 16 dots is used. In this way, a printing method (scanning method) using an array of a plurality of different values as the sub-scan feed amount L is called “anomalous feed”. Note that the scanning parameters of the second embodiment also satisfy the above-described conditions c1 'to c3'.
[0077]
FIG. 13 is an explanatory diagram showing nozzles used in the second embodiment. The actuator 40 in FIG. 13 is the same as that shown in FIG. For chromatic ink, 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 use nozzles # C1 to # C15 are used. Therefore, the interval between the lower nozzle # Y15 of the yellow nozzle group and the upper nozzle # M1 of the magenta nozzle group is 2k. Similarly, the distance between the nozzle # M15 at the lower end of the magenta use nozzle group and the nozzle # C1 at the upper end of the cyan use nozzle group is also 2k.
[0078]
FIG. 14 is an explanatory diagram illustrating nozzles that record each raster line within the effective recording range in each pass of the second embodiment. Since irregular feed is used in the second embodiment, the position of the nozzle group for each pass is not as regular as in the first embodiment. Therefore, there is an advantage that the accumulated sub-scan feed error is smaller than that in the first embodiment.
[0079]
The second embodiment also has an advantage that the accumulated error position of the sub-scan feed does not always coincide between the used nozzle groups, as will be described below. For cyan, the difference in the number of sub-scan feeds is the largest between the second and third raster lines, and the difference in the number of sub-scan feeds is 4. That is, for cyan, there is an error accumulation position Cmis between the second and third raster lines. Also for magenta and yellow, error accumulation 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 exist 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.
[0080]
Thus, in the second embodiment, the accumulated error positions Cmis, Mmis, and Ymis for the three used nozzle groups do not always coincide. For this reason, compared to the case where the accumulated error positions Cmis, Mmis, and Ymis for the three used nozzle groups always coincide, the occurrence of banding due to the accumulated error of the sub-scan feed can be reduced.
[0081]
FIG. 15 is an explanatory diagram showing an actuator used in the second comparative example. In the actuator 40 ″ of FIG. 15, each of the chromatic nozzle groups 40Y ″, 40M ″, and 40C ″ is composed of 15 nozzles. Further, the interval between the nozzles at the ends of the chromatic nozzle groups 40Y ″, 40M ″, 40C ″ is equal to the nozzle pitch k. The black nozzle group 40 ″ is composed of 45 nozzles. . In the second comparative example, such an actuator 40 ″ is used, and printing is executed in accordance with the same scanning parameters as the scanning parameters of the second embodiment shown in FIG.
[0082]
FIG. 10 is an explanatory diagram illustrating nozzles that record each raster line within the effective recording range in each pass of the first comparative example. In the second comparative example, 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 the fourteenth. Between the 15th raster line. In other words, in the second embodiment, the error accumulation positions Cmis, Mmis, and Ymis for the three color inks always coincide with each other, and the error accumulation positions Cmis, Mmis, Ymis appears repeatedly. Thus, if the error accumulation positions Cmis, Mmis, and Ymis for each chromatic nozzle group are always matched, banding is easily noticeable.
[0083]
As can be seen by comparing FIG. 13 and FIG. 15, the difference between the second embodiment and the second comparative example is only the interval between the used nozzle groups. That is, in the second embodiment, the interval between the used nozzle groups is set to a value 2k that is twice the nozzle pitch k, whereas in the second comparative example, the interval between the used nozzle groups is set to the nozzle pitch k. It is set to the same value. Such a difference in the interval between the used nozzle groups appears as a difference in the generation positions of the error accumulation positions Cmis, Mmis, and Ymis as shown in FIGS.
[0084]
As will be understood from this, in the second embodiment, similarly to the first embodiment, the used nozzles are arranged so that the interval between adjacent used nozzle groups is M times the nozzle pitch k (M is an integer of 2 or more). Is selected. The interval between 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 equal to or greater than 1).
[0085]
As can be understood from FIG. 13, in the second embodiment, all chromatic ink nozzles provided in the actuator 40 are used. In the actuator 40 used in this embodiment, the interval between the mounting nozzle groups of each ink is set to a value twice the nozzle pitch k. Therefore, even if all the chromatic color nozzles are used, the sub-scan feed is performed. The error accumulation position does not always coincide between the chromatic color nozzle groups. Therefore, there is an advantage that high-quality printing can be performed by using as many chromatic ink nozzles as possible among the nozzles provided in the actuator 40.
[0086]
In general, 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 times the nozzle pitch k (m Is preferably set to be an integer of 2 or more. By doing so, it is possible to perform high-quality printing using as many nozzles as possible for the reasons described above.
[0087]
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 used nozzle group as in the first and second embodiments.
[0088]
F. Actuator variations:
FIG. 17 is an explanatory diagram illustrating a first modification of the actuator. The left nozzle row of the actuator 41 is the same as the left nozzle row of the actuator 40 of the embodiment shown in FIG. The right nozzle row 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. The intervals between the mounting nozzle groups for the three colors arranged on a straight line in the sub-scanning direction are 2k.
[0089]
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. The normal magenta ink and the normal cyan ink may be referred to as “dark magenta ink” and “dark cyan ink”.
[0090]
Even 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, when the same printing method as that in the first and second embodiments is employed, the error accumulation positions of the three nozzle groups 40LM, 40LC, and 40K on the right side of FIG. can get.
[0091]
It should be noted that the use of the actuator 41 shown in FIG. 17 has the advantage that the color image quality can be improved compared to the actuator 40 shown in FIG. 3 because six colors can be printed using light ink. On the other hand, when the actuator 40 shown in FIG. 3 is used, black printing can be performed at a high speed since black ink nozzles about three times as many as the actuator 41 shown in FIG. 17 can be used during monochrome printing. There is an advantage that can be made.
[0092]
FIG. 18 is an explanatory diagram illustrating a second modification of the actuator. The actuator 42 exchanges the positions of the dark magenta nozzle group 40M and the light magenta nozzle group 40LM of the actuator 41 of the first modification shown in FIG. 17, and the dark cyan nozzle group 40C and the light cyan nozzle group 40LM. The position of the nozzle group 40LC is exchanged. This actuator 42 also has substantially the same advantages as the actuator 41 shown in FIG.
[0093]
FIG. 19 is an explanatory diagram showing a third modification of the actuator. In this actuator 43, the color nozzle rows and the black nozzle rows 40K of the actuator 40 of the embodiment shown in FIG. 3 are arranged in two rows in a staggered manner. For example, in the black nozzle row 40K, the odd-numbered nozzles # K1, # K3,... # K47 are arranged in the left column, and the even-numbered nozzles # K2, # K4,. 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 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” is only necessary that the nozzle groups are arranged in a straight line as a whole. The plurality of nozzles constituting the nozzle group are not necessarily arranged in a straight line.
[0094]
In the actuators shown in the various embodiments and modifications described above, the nozzles for four colors or six colors are arranged in two rows. However, these nozzles may be arranged in one row. It may be arranged in a plurality of rows more than the row. For example, a group of four colors of nozzles may be arranged in a row by providing 15 black nozzles with an interval of 2k below the color nozzle group of FIG.
[0095]
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 performing printing, by selecting some nozzles as unused nozzles, the interval between the nozzle groups of each color used is M × k dots (M is an integer of 2 or more). Is set as follows.
[0096]
FIG. 20 is an explanatory diagram illustrating a fourth modification of the actuator. In the fourth modification example, two actuators are used: a first actuator 44a including only the color nozzle row and a second actuator 44b including only the black nozzle row 40K. The nozzle groups for each color are arranged in a staggered manner as 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 4 dots. In color printing, the nozzles with “x” are not used, and 15 nozzles of each color ink nozzle group are used. For the black nozzle row, fifteen nozzles # K33 to # K47 at the same sub-scanning position as the cyan use nozzles # C1 to # C15 are used. As a result, the interval between the nozzle groups is substantially set to 2k.
[0097]
FIG. 21 is an explanatory diagram showing a fifth modification of the actuator. The actuator 45 includes three color nozzle rows and one black nozzle row. The first color nozzle row is composed of a yellow nozzle group 40Y and a magenta nozzle group 40M. The second color nozzle row is composed of a light magenta nozzle group 40LM and a cyan nozzle group 40C. The third color nozzle row is composed of a light cyan nozzle group 40LC and a light black nozzle group 40LK. “Light black” means gray instead of black.
[0098]
The nozzle groups are arranged in a straight line along the sub-scanning direction, but can also be arranged in a staggered manner as shown in FIGS. The black nozzle row 40K has 48 nozzles. Each nozzle group other than the black nozzle row 40K has 24 nozzles. In color printing, the nozzles marked with “x” are not used, and 23 nozzles of each color ink nozzle group are used. For the black nozzle row, 23 nozzles # K25 to # K47 at the same sub-scanning position as the used nozzles # LK1 to # LK23 for light black are used. As a result, the interval between the nozzle groups is substantially set to 2k.
[0099]
FIG. 22 is an explanatory diagram showing a sixth modification of the actuator. The actuator 46 also includes three color nozzle rows and one black nozzle row. Since the difference between the actuator 46 and the actuator 45 shown in FIG. 21 is only the position of the nozzle group other than the black nozzle row 40K and the yellow nozzle group 40Y, detailed description thereof is omitted.
[0100]
FIG. 23 is an explanatory diagram showing a seventh modification of the actuator. The actuator 47 has three nozzle rows. The first nozzle row is composed of 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 composed of a light cyan nozzle group 40LC and a black nozzle group 40K. Each nozzle group has 24 nozzles. In 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.
[0101]
FIG. 24 is an explanatory diagram showing an eighth modification of the actuator. The actuator 48 is a group of nozzles for six colors arranged 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 staggered manner. In 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.
[0102]
In the fourth to eighth modifications described above, one unused nozzle is set for each nozzle group, but two or more unused nozzles may be set for each nozzle group. As can be understood from these modified examples, even when the interval between the nozzle groups is equal to the nozzle pitch k, the interval between the used nozzle groups is set to M × k dots by appropriately selecting the unused nozzles. Can be set.
[0103]
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.
[0104]
(1) In the above embodiment, only the case where the scan repetition number s is 1 has been described, but the present invention can also be applied to the case where the scan repetition number s exceeds 1.
[0105]
(2) Some printing apparatuses can set the dot pitch (recording resolution) in the main scanning direction and the dot pitch in the sub-scanning direction to different values. In this case, parameters related to the main scanning direction (for example, pixel pitch on the raster line) are defined by dot pitches in the main scanning direction, while parameters related to the sub scanning direction (for example, nozzle pitch k and sub scanning). The feed amount L) is defined by the dot pitch in the sub-scanning direction.
[0106]
(3) The present invention can also be applied to a drum scan printer. In the drum scan printer, the drum rotation direction is the main scanning direction, and the carriage traveling direction is the sub-scanning direction. The present invention can be applied not only to an ink jet printer but also to a printing apparatus that records 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. Examples of such a printing apparatus include a facsimile machine and a copying machine.
[0107]
(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 embodiments described above. It is also possible to realize the same nozzle arrangement as in 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 can be realized by arranging six actuators each including a nozzle group for one color in the sub-scanning direction. At this time, the nozzles marked with “x” in FIG. 24 are not formed in any of the actuators. As a result, the interval between the end portions of each nozzle group is 2k.
[0108]
(5) In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced with hardware. Also good. For example, the host computer 100 can execute part of the functions of the system controller 54 (FIG. 2).
[0109]
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, the computer program may be supplied from the program supply device to the host computer 100 via a communication path. When realizing the function 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 the computer program recorded on the recording medium.
[0110]
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. Note that some of the functions described above may be realized by an operation system instead of an application program.
[0111]
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 an internal storage device in a computer such as various RAMs and ROMs, An external storage device fixed to a computer such as a hard disk is also included.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a main configuration of a color inkjet printer 20 as an 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 the bottom surface of the actuator 40;
FIG. 4 is an explanatory diagram for illustrating basic conditions of a general dot recording method when the scan repetition number s is 1. FIG.
FIG. 5 is an explanatory diagram for illustrating 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 diagram showing nozzles used in the first embodiment.
FIG. 8 is an explanatory diagram illustrating nozzles that record each raster line within an effective recording range in each pass of the first embodiment.
FIG. 9 is an explanatory diagram showing nozzles used in the first comparative example.
FIG. 10 is an explanatory diagram illustrating nozzles that record each raster line within an effective recording 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 the printing method according to the 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 illustrating nozzles that record each raster line within an effective recording 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 illustrating nozzles that record each raster line within an effective recording range in each pass of a second comparative example.
FIG. 17 is an explanatory diagram showing a first modification of the actuator.
FIG. 18 is an explanatory view showing a second modification of the actuator.
FIG. 19 is an explanatory view showing a third modification 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 diagram showing a sixth modification of the actuator.
FIG. 23 is an explanatory diagram showing a seventh modification of the actuator.
FIG. 24 is an explanatory diagram 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 illustrating an example of an overlap recording method.
[Explanation of symbols]
20 ... Color inkjet 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: Receive buffer memory
52 ... Image buffer
54 ... System controller
61 ... Main scanning driver
62 ... Sub-scanning driver
63: Head drive driver
100: Host computer

Claims (9)

A printing apparatus for printing an image by recording dots on the surface of a print medium,
A print head including a plurality of dot forming elements for forming dots on the print medium;
A main scanning drive unit that performs main scanning by driving at least one of the print head and the print medium;
A head driving unit that drives at least some of the plurality of dot forming elements during the main scanning to form dots; and
A sub-scan driving unit that performs sub-scanning by driving at least one of the print head and the print medium every time the main scanning is completed;
A control unit for controlling the respective units,
The print head is
A plurality of dot forming element groups for forming dots using different inks,
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 pitches k · w (k is an integer, w is the dot pitch) of the dot forming elements measured along the sub-scanning direction are equal to each other. And
The pitch k · w of the dot forming elements is set to a value that is an integer multiple of at least twice the pitch w of the dots in the sub-scanning direction on the print medium,
The controller is
For each dot-forming element group, dots are formed on the print medium using N dot-forming elements of the same number (N is an integer of 2 or more) arranged in succession at intervals of the pitch k .
In the N number of dot forming elements used in each dot formation element groups, the spacing between the groups relating to the N number of dot forming elements, M times (M pitch k of the dot-forming elements is 2 or more An integer other than (N × n + 1), where n is an arbitrary integer greater than or equal to 1) is selected to be a value M × k ,
With respect to dot formation for each ink, main scanning and sub-scanning control is executed so as to satisfy the following three conditions (i) to (iii):
(I) The number of sub-scan feeds for one cycle repeatedly executed at the time of printing is multiplied by an integer k indicating the pitch k · w of dot forming elements and the number of main scans s performed on each main scan line. Equal to (k × s);
(Ii) When the remainder obtained by dividing the accumulated value of the sub-scan feed amount L in each cycle by the integer k indicating the dot forming element pitch is defined as an offset F, in one cycle, the offset F is A value in the range of 0 to (k−1), each value being repeated s times;
(Iii) The cumulative value ΣL of (k × s) sub-scan feed amounts L in one cycle is a value obtained by multiplying the number N of dot formation elements by an integer k indicating the dot formation element pitch (N × k). )be equivalent to;
Printing device. The printing apparatus according to claim 1,
The print head has a value m in which the interval between the dot forming elements mounted at the end of each dot forming element group is m times the pitch k of the dot forming elements (m is an integer not less than 2 and not more than M ). A printing apparatus formed so as to be × k. The printing apparatus according to claim 1 or 2 ,
The sub-scan driving unit performs sub-scanning according to an interlace method in which a plurality of sub-scan feeds may be performed between two main scans for executing dot recording on two adjacent main scan lines. Run the printing device. A printing method for printing an image by recording dots on the surface of a print medium,
(A) As a print head,
i) a plurality of dot forming elements for forming dots using different inks, each having a plurality of dot forming element groups arranged in a predetermined order along the sub-scanning direction;
ii) The plurality of dot forming elements included in each dot forming element group are provided so that the pitches k · w (k is an integer, w is the dot pitch) of the dot forming elements measured along the sub-scanning direction are equal to each other. As well as
iii) preparing a print head in which the pitch k · w of the dot forming elements is set to a value that is an integer multiple of twice or more the pitch w of the dots in the sub-scanning direction on the print medium;
(B) For each dot forming element group, forming a dot on the print medium using an equal number of N dot forming elements that are continuously arranged at intervals of the pitch k;
With
The N dot forming elements used in each dot forming element group in the step (b) are such that the interval between the groups related to the N dot forming elements is M times the pitch k of the dot forming elements. (M is 2 or more (n × n + 1) other than an integer, n represents any integer of 1 or more) are selected so that the value M × k of Rutotomoni,
Regarding dot formation for each ink, main scanning and sub-scanning are executed so as to satisfy the following three conditions (i) to (iii):
(I) The number of sub-scan feeds for one cycle repeatedly executed at the time of printing is multiplied by an integer k indicating the pitch k · w of dot forming elements and the number of main scans s performed on each main scan line. Equal to (k × s);
(Ii) When the remainder obtained by dividing the accumulated value of the sub-scan feed amount L in each cycle by the integer k indicating the dot forming element pitch is defined as an offset F, in one cycle, the offset F is A value in the range of 0 to (k−1), each value being repeated s times;
(Iii) The cumulative value ΣL of (k × s) sub-scan feed amounts L in one cycle is a value obtained by multiplying the number N of dot formation elements by an integer k indicating the dot formation element pitch (N × k). )be equivalent to;
Printing method. The printing method according to claim 4 , comprising:
The print head has a value m in which the interval between the dot forming elements mounted at the end of each dot forming element group is m times the pitch k of the dot forming elements (m is an integer not less than 2 and not more than M ). A printing method formed so as to be × k. The printing method according to claim 4 or 5 , wherein
The step (b)
Driving at least one of the print head and the printing medium to perform main scanning, and driving at least some of the plurality of dot forming elements during the main scanning to form dots; and ,
A step of performing sub-scanning by driving at least one of the print head and the print medium each time the main scanning is completed;
Including
The sub-scan is performed according to an interlace method in which a plurality of sub-scan feeds may be performed between two main scans for executing dot recording on two adjacent main scan lines. Printing method. A computer-readable recording medium that records a computer program for causing a computer equipped with a printing apparatus that prints an image by printing dots on the surface of the printing medium using a print head,
The print head is
i) a plurality of dot forming elements for forming dots using different inks, each having a plurality of dot forming element groups arranged in a predetermined order along the sub-scanning direction;
ii) The plurality of dot forming elements included in each dot forming element group are provided so that the pitches k · w (k is an integer, w is the dot pitch) of the dot forming elements measured along the sub-scanning direction are equal to each other. As well as
iii) The pitch k · w of the dot forming elements is set to a value that is an integer multiple of two or more times the pitch w of the dots on the print medium in the sub-scanning direction,
The recording medium is
For each dot forming element group, a function of forming dots on the print medium using an equal number of N dot forming elements successively arranged at intervals of the pitch k;
The N dot forming elements used in each dot forming element group are selected. At this time, the interval between the groups related to the N dot forming elements is M times the pitch k of the dot forming elements ( A function for executing selection such that M is 2 or more and an integer other than (N × n + 1), and n is an arbitrary integer of 1 or more, M × k;
A function of executing main scanning and sub-scanning so as to satisfy the following three conditions (i) to (iii) regarding dot formation for each ink:
(I) The number of sub-scan feeds for one cycle repeatedly executed at the time of printing is multiplied by an integer k indicating the pitch k · w of dot forming elements and the number of main scans s performed on each main scan line. Equal to (k × s);
(Ii) When the remainder obtained by dividing the accumulated value of the sub-scan feed amount L in each cycle by the integer k indicating the dot forming element pitch is defined as an offset F, in one cycle, the offset F is A value in the range of 0 to (k−1), each value being repeated s times;
(Iii) The cumulative value ΣL of (k × s) sub-scan feed amounts L in one cycle is a value obtained by multiplying the number N of dot formation elements by an integer k indicating the dot formation element pitch (N × k). )be equivalent to;
A computer-readable recording medium characterized by recording a computer program for causing a computer to realize the above. The recording medium according to claim 7,
The print head has a value m in which the interval between the dot forming elements mounted at the end of each dot forming element group is m times the pitch k of the dot forming elements (m is an integer not less than 2 and not more than M). A recording medium formed to be xk. The recording medium according to claim 7 or 8,
The function of forming the dots is
A function of driving at least one of the print head and the printing medium to perform main scanning, and driving at least a part of the plurality of dot forming elements during the main scanning to form dots; ,
  A function of performing sub-scanning by driving at least one of the print head and the print medium each time the main scanning is completed;
Including
  The sub-scan is executed according to an interlace method in which a plurality of sub-scan feeds may be performed between two main scans for executing dot recording on two adjacent main scan lines. recoding media.

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