Patent Application
20110175958
1. Technical Field
The present invention relates to a fluid ejecting apparatus and a fluid ejecting method.
2. Related Art
An ink jet printer (hereinafter, referred to as a printer) that ejects ink (fluid) from a head (nozzles) while moving the head in a movement direction to form an image has been known as one of fluid ejecting devices. In the printer, the timing for ejecting the ink from the nozzles is set to form dots at a target position on a medium.
However, when the solvent component (e.g., water) of the ink infiltrates the medium, a phenomenon of undulations in the medium (cockling phenomenon) occurs. Since the distance from the nozzles to the medium fluctuates, dots are formed deviating from the target position when ink is ejected from the nozzles at the set timing.
Thus, a printer that corrects the timing for ejecting ink from the nozzles according to the distance between the medium with the cockling phenomenon and the nozzles is proposed.
JP-A-11-240146 is an example of the related art.
Since a medium with the cockling phenomenon has a ridge portion and a valley portion, the distance between the medium and the nozzles is different according to the position of the medium. For example, it is assumed that the timing for ejecting the ink from the nozzles is corrected according to the distance from the nozzles to the ridge portion of the medium such that the position where a target dot is formed and the actual position a dot is formed coincide with each other. Then, in the valley portion of the medium, the difference between the target dot formation position and the actual dot formation position becomes larger. Particularly, in a printer in which the head moves in two movement directions, the difference of forward and backward dot formation positions becomes larger in the valley portion of the medium.
An advantage of some aspects of the invention is to reduce deterioration in image quality caused by the misalignment of forward and backward dot formation positions.
According to an advantage of the invention, there is provided a fluid ejecting apparatus including: a head that is provided with a first nozzle row in which nozzles ejecting fluid are arranged in a predetermined direction, and a second nozzle row in which nozzles ejecting the fluid are arranged in the predetermined direction, the first nozzle row and the second nozzle row being arranged in a movement direction crossing the predetermined direction; a platen that supports a medium opposed to the head and is provided with a plurality of convex portions arranged in the movement direction on the side opposed to the medium; and a control unit that repeatedly performs an ejection operation of ejecting fluid from the nozzles moving in two directions of a forward path and a backward path while moving the head forward and backward and an operation of relatively moving relative positions of the head and the medium in one direction of the predetermined direction. The control unit performs an adjustment process of adjusting the ejection time of the fluid from the first nozzle row and the second nozzle row such that, at parts of the medium corresponding to the convex portions, an amount of deviation in the movement direction of the dots formed on the forward path by the first nozzle row and the dots formed on the backward path by the first nozzle row is less than the amount of deviation in the movement direction of the dots formed on the forward path by the second nozzle row and the dots formed on the backward path by the second nozzle row, and such that, in the ejection operation, the position in the movement direction of the dots formed by the second nozzle row is a position opposite to the side on which the head moves in the movement direction with respect to the position in the movement direction of the dots formed by the first nozzle row.
Other aspects of the invention will be clearly described in the specification and accompanying drawings.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
The following will be clarified by description of the specification and description of the accompanying drawings.
A fluid ejecting apparatus includes: a head that is provided with a first nozzle row in which nozzles ejecting fluid are arranged in a predetermined direction, and a second nozzle row in which nozzles ejecting the fluid are arranged in the predetermined direction, the first nozzle row and the second nozzle row being arranged in a movement direction crossing the predetermined direction; a platen that supports a medium opposed to the head and is provided with a plurality of convex portions arranged in the movement direction on the side opposed to the medium; and a control unit that repeatedly performs an ejection operation of ejecting fluid from the nozzles moving in two directions of a forward path and a backward path while moving the head forward and backward and an operation of relatively moving relative positions of the head and the medium in one direction of the predetermined direction, wherein the control unit performs an adjustment process of adjusting the ejection time for the fluid from the first nozzle row and the second nozzle row such that, at parts of the medium corresponding to the convex portions, the amount of deviation in the movement direction of the dots formed on the forward path by the first nozzle row and the dots formed on the backward path by the first nozzle row is less than the amount of deviation in the movement direction of the dots formed on the forward path by the second nozzle row and the dots formed on the backward path by the second nozzle row, and such that, in the ejection operation, the position in the movement direction of the dots formed by the second nozzle row is a position opposite to the side on which the head moves in the movement direction with respect to the position in the movement direction of the dots formed by the first nozzle row.
According to the fluid ejecting apparatus, it is possible to reduce deterioration in image quality caused by misalignment of the forward and backward dot formation positions.
In the fluid ejecting apparatus, in the ejection operation, a difference between the position in the movement direction of the dots formed by the first nozzle row and the position in the movement direction of the dots formed by the second nozzle row is a half of the amount of deviation in the movement direction of the dots formed on the forward path and the backward path by the first nozzle row at the parts of the medium positioned between the convex portions arranged in the movement direction.
According to the fluid ejecting apparatus, it is possible to reduce the amount of forward and backward deviation of the dot formation positions of the second nozzle row at the parts of the medium positioned between the convex portions.
In the fluid ejecting apparatus, at parts of the medium corresponding to the convex portions, the ejection time for the fluid from the first nozzle row is adjusted such that the positions in the movement direction of the dots formed on the forward path and the backward path by the first nozzle row coincide with each other.
According to the fluid ejecting apparatus, it is possible to reduce deterioration in image quality caused by misalignment of forward and backward dot formation positions.
In the fluid ejecting apparatus, the ejection time for the fluid from the first nozzle row is an average value of the ejection time of the first nozzle row adjusted such that the amount of deviation in the movement direction of the dots formed on the forward path and the backward path by the first nozzle row is less than the amount of deviation in the movement direction of the dots formed on the forward path and the backward path by the second nozzle row, at the parts of the medium corresponding to the plurality of convex portions.
According to the fluid ejecting apparatus, it is possible to further reduce deterioration in image quality caused by misalignment of forward and backward dot formation positions with high precision.
In the fluid ejecting apparatus, the control unit performs the adjustment process when an amount of the fluid ejected onto the vicinity of a unit area on the medium is equal to or more than a threshold value.
According to the fluid ejecting apparatus, it is possible to perform an adjustment process when a cockling phenomenon occurs on the medium.
In the fluid ejecting apparatus, the control unit changes the ejection time for the fluid from the first nozzle row and the second nozzle row in the adjustment process, according to the amount of the fluid ejected onto the vicinity of the unit area on the medium.
According to the fluid ejecting apparatus, it is possible to adjust the ejection time from the nozzle rows according to the cockling state (amount of change in paper gap) of the medium.
A fluid ejecting apparatus includes: a head that is provided with a first nozzle row in which nozzles ejecting fluid are arranged in a predetermined direction, and a second nozzle row in which nozzles ejecting the fluid are arranged in the predetermined direction, the first nozzle row and the second nozzle row being arranged in a movement direction crossing the predetermined direction; a platen that supports a medium opposed to the head and is provided with a plurality of convex portions arranged in the movement direction on the side opposed to the medium; and a control unit that repeatedly performs an ejection operation of ejecting fluid from the nozzles moving in two directions of a forward path and a backward path while moving the head forward and backward and an operation of relatively moving relative positions of the head and the medium in one direction of the predetermined direction, wherein the control unit adjusts ejection time for the fluid from the first nozzle row and the second nozzle row such that, at parts of the medium corresponding to intermediate portions of the convex portions arranged in the movement direction, an amount of deviation in the movement direction of the dots formed on the forward path by the first nozzle row and the dots formed on the backward path by the first nozzle row is less than the amount of deviation in the movement direction of the dots formed on the forward path by the second nozzle row and the dots formed on the backward path by the second nozzle row, and such that, in the ejection operation, the position in the movement direction of the dots formed by the second nozzle row is a position of the side on which the head moves in the movement direction with respect to the position in the movement direction of the dots formed by the first nozzle row.
According to the fluid ejecting apparatus, it is possible to reduce deterioration in image quality caused by misalignment of forward and backward dot formation positions.
There is provided a fluid ejecting method of a fluid ejecting apparatus including: a head that is provided with a first nozzle row in which nozzles ejecting fluid are arranged in a predetermined direction, and a second nozzle row in which nozzles ejecting the fluid are arranged in the predetermined direction, the first nozzle row and the second nozzle row being arranged in a movement direction crossing the predetermined direction, and a platen that supports a medium opposed to the head and is provided with a plurality of convex portions arranged in the movement direction on the side opposed to the medium, in which an ejection operation of ejecting fluid from the nozzles moving in two directions of a forward path and a backward path while moving the head forward and backward and an operation of relatively moving relative positions of the head and the medium in one direction of the predetermined direction are repeatedly performed, wherein ejection time for the fluid from the first nozzle row and the second nozzle row is adjusted such that, at parts of the medium corresponding to the convex portions, an amount of deviation in the movement direction of the dots formed on the forward path by the first nozzle row and the dots formed on the backward path by the first nozzle row is less than the amount of deviation in the movement direction of the dots formed on the forward path by the second nozzle row and the dots formed on the backward path by the second nozzle row, and such that, in the ejection operation, the position in the movement direction of the dots formed by the second nozzle row is a position opposite to the side on which the head moves in the movement direction with respect to the position in the movement direction of the dots formed by the first nozzle row.
According to the fluid ejecting method, it is possible to reduce deterioration in image quality caused by misalignment of forward and backward dot formation positions.
Hereinafter, an embodiment of a printing system in which a printer and a computer are connected to each other will be described by exemplifying an ink jet printer (hereinafter, referred to as a printer) as the fluid ejecting apparatus.
The controller 10 is a control unit for controlling the printer 1. An interface unit 11 is to transmit and receive data between the computer 60 that is the external device and the printer 1. A CPU 12 is an operation processing device for overall controlling the printer 1. A memory 13 is to secure an area for storing programs of the CPU 12 or a work area. The CPU 12 controls the units by a unit control circuit 14 according to the programs stored in the memory 13.
The transport unit 20 transports the medium S to a printable position, and transports the medium S at a predetermined transport rate in a transport direction (a predetermined direction) at the printing time.
The carriage unit 30 is to move a head 41 in a direction (a movement direction) crossing the transport direction, and has a carriage 31 and a guide shaft 32.
The head unit 40 has the head 41 for ejecting ink to the medium S. A plurality of nozzles that are ink ejecting units are provided on the lower face of the head 41, and each nozzle is provided with an ink chamber (not shown) storing ink. The method of ejecting fluid from the nozzles may be a piezoelectric method of applying voltage to a driving element (a piezoelectric element) to swell and contract a pressure chamber, thereby ejecting the fluid, and may be a thermal method of generating bubbles in the nozzles using a heat generating element to eject liquid by the bubbles.
One nozzle row is formed of 180 nozzles, and the nozzle spacing is “180 dpi”. One nozzle row (e.g., K1) of the nozzle rows ejecting the same color of ink has a “360 dpi” deviation with respect to the other nozzle row (e.g., K2) to the downstream side in the transport direction. For this reason, the number of nozzles ejecting one color of ink is 360, and the nozzles ejecting one color of ink are arranged in the transport direction at a spacing of 360 dpi in the head 41. For description, odd numbers (#1, #3, #5, . . . ) are given in order from the nozzles on the downstream side belonging to the nozzle row (e.g., K1) deviating to the downstream side between the nozzle rows ejecting the same color of ink, and even numbers (#2, #4, #6, . . . ) are given in order from the nozzles on the downstream side belonging to the nozzle row (e.g., K2) deviating to the upstream side.
In the head 41 shown in
The printer 1 repeats a dot forming process of discontinuously ejecting ink droplets from the head 41 moving along the movement direction to form dots on the medium, and a transport process of transporting the medium in the transport direction with respect to the head 41. Accordingly, at a position on the medium different from the position of the dots formed by the former dot forming process, dots can be formed in the later dot forming process, and thus it is possible to print a 2-dimension image on the medium. An operation (one dot forming process) of moving the head 41 once in the movement direction while ejecting the ink droplets is called a “pass”.
In the printer 1 of the embodiment, since the ink droplets are ejected from the head 41 moving in the movement direction, as shown in
On the forward path and the backward path, when the movement velocity (Vc) of the head 41, the ejection velocity Vm of ink, and a distance (hereinafter, also referred to as paper gap PG) from the nozzles to the medium are regular (designed values), the flying direction and the landing time of ink at the forward path time and the flying direction and the landing time of ink at the backward path time are regular. In this case, to arrange the dot formation positions of the forward path and the backward path at the target position, it is preferable to eject ink from the nozzles at the same time before the head 41 of the forward path and the backward path reaches the target position. In other words, the ink is ejected from the nozzles when the head 41 is positioned on the left side in the movement direction from the target position by a distance X1 at the forward path time, and the ink is ejected from the nozzles when the head 41 is positioned on the right side in the movement direction from the target position by the distance X1 at the backward path time. Accordingly, it is possible to arrange the forward and backward dot formation positions at the target position.
However, in the actual printer 1, there is a mechanical error in the carriage 31, a difference in characteristics of the head 41, or a difference in characteristics of the forward path and the backward path. For this reason, since the movement velocity Vc of the head 41, the ink ejection velocity Vm, or the paper gap PG is changed or the flying direction of the ink droplets deviates, the dots may not be formed at the target position at the designed ejection time. For example, when the ejection velocity from the nozzles is higher than the designed ejection velocity Vm (not shown), the ink droplets land onto a position (the opposite position of the head movement direction) ahead of the target position. In this case, particularly, when the two-direction printing is performed, the dots land deviated to the left side in the movement direction from the target position at the forward path time, and land deviated to the right side in the movement direction from the target position at the backward path time. That is, the dot formation position of the forward path and the dot formation position of the backward path greatly deviate in the movement direction of the head 41. When the forward and backward dot formation positions deviate, joint of the image formed on the forward path and the image formed on the backward path is not satisfactory, and image quality of the printed image deteriorates.
In the printer 1 of the embodiment, “Bid adjustment value” for adjusting the ink ejection time of the forward path and the backward path from the designed ejection time is calculated according to individual characteristics of the printer 1 in a mass-production process (or maintenance, etc.). Thus, the dot formation position of the forward path and the dot formation position of the backward path in the head movement direction are arranged to suppress the image deterioration. For example, when the ink ejection velocity Vm is higher than the designed value as described above, it is preferable that the ejection time of the forward path and the backward path is delayed later than the designed ejection time. In such a manner, the dot formation position of the forward path is corrected to the right side and the dot formation position of the backward path is corrected to the left side. Accordingly, it is possible to arrange the forward and backward dot formation positions in the head movement direction.
The printer 1 may perform non-edge printing of forming an image even at the edge of the medium such that there is no margin at the periphery of the medium S. However, the image formation position on the medium may deviate by a transport error of the medium or deviation of the dot formation position. For this reason, at the time of the non-edge printing, ink is ejected in the range wider than the medium. In the case, since the platen 21 is provided with the convex portions 211, it is possible to eject ink, which does not land onto the medium S, into concave portions between the convex portions 211. In such a manner, it is possible to prevent the ink from being attached to the part of the platen coming in contact with the medium S, and thus it is possible to prevent the medium S from being stained.
As described above, the paper gap PG that is the distance from the nozzle face to the medium has an influence on the time when the ink droplets are ejected from the nozzles and then land onto the medium. For this reason, the paper gap PG is considered to determine the ink ejection time from the nozzles in the production process (design process or mass-production process). Accordingly, when the paper gap PG is changed, the dot formation position is changed. Thus, it is possible to keep the paper gap PG regular by supporting the medium S from the lower part by the convex portions 211 of the platen 21 when the medium surface is regular (horizontal) as shown at the upper part of
However, in a medium absorbing a solvent component of ink (e.g., water) such as normal paper, the part of the medium absorbing ink swells. For this reason, as a result of forming an image on the medium S, as shown in
In
In
In the production process of the printer 1, when the paper gap is the designed value PG, the ejection time is set such that the dot formation positions in the movement direction of the forward path and the backward path of the nozzle rows K1 and K2 coincide with each other (the Bid adjustment value is set). For this reason, as shown in
That is, when the cockling phenomenon occurs on the medium S and the actual paper gap deviates from the paper gap (designed paper gap PG) at the time of arranging the dot formation positions in the movement direction of the forward path and the backward path, the dot formation positions in the movement direction of the forward path and the backward path deviates. As described above, when the image formed on the forward path and the image formed on the backward path deviate in the movement direction, joint of the image is not satisfactory, and the printed image deteriorates. Particularly, as shown in
As a result, as shown in
At the valley portion of the medium S, since the platen gap PG2 is larger than that of the intermediate portion, the dots are formed at a position (the head movement direction side) proceeding ahead of the target position. Specifically, the forward path line deviates from the target position to the right side in the movement direction, and the backward path line deviates from the target position to the left side. For this reason, the line formed at the valley portion of the medium S, in which the forward path line and the backward path line deviate in the movement direction, is also not a straight line along the transport direction as compared with the line formed at the intermediate portion of the medium S. However, the deviation in the movement direction of the forward path line and the backward path line of the valley portion formed by the adjustment method of the comparative example is small as compared with the forward path line and the backward path line formed at the valley portion of the medium S shown in
The reason is, in the paper gap, because the deviation of the dot formation positions in the movement direction of the forward path and the backward path gets larger as the amount of deviation from the platen gap (PG3 of the intermediate portion in the comparative example) at the time of adjusting the dot formation positions in the movement direction of the forward path and the backward path becomes larger. For this reason, as shown in
In the adjustment method of the comparative example, the forward and backward ejection time is adjusted according to the middle platen gap PG3 between the minimum value (PG1 of the ridge portion) and the maximum value (PG2 of the valley portion) of the platen gap at the time when the cockling phenomenon occurs on the medium. For this reason, the difference between the platen gap (PG3 of the intermediate portion) with the adjusted forward and backward ejecting time and the platen gap (e.g., PG1 of the ridge portion or PG2 of the valley portion) of various positions of the medium S can be decreased as small as possible. As a result, the deviation of the dot formation positions in the movement direction of the forward path and the backward path can be suppressed as much as possible.
However, even when the deviation of the dot formation positions in the forward and backward movement direction is suppressed as much as possible by the adjustment method of the comparative example, joint of the image is not satisfactory, and the image quality deteriorates when the image formed on the forward path and the image formed on the backward path deviate in the movement direction. Particularly, as shown in the example of
In the adjustment method of the embodiment, at the ridge portion of the medium S, the ejection time of the forward path and the backward path of the K1 row is adjusted such that the dot formation positions (o) in the movement direction of the forward path and the backward path of one K1 row (reference row corresponding to the first nozzle row) of two nozzle rows (K1 and K2) ejecting the same color of ink coincide with each other, that is, according to the paper gap PG1. For this reason, at the ridge portion of the medium S, the dots (o) of the K1 row are arranged in a straight line in the transport direction irrespective of the forward path and the backward path.
The ink ejection time of the K2 row is adjusted such that the dots of the K2 row (adjustment row corresponding to the second nozzle row) is formed on the front side (the side opposite to the movement side of the head) in the movement direction with respect to the dots of the K1 row (reference row). For this reason, as shown in
When the ink ejection time is adjusted in such a manner to form an image on the medium S on which the cockling phenomenon occurs, first, at the ridge portion of the medium S, the dots (o) of the K1 row that is the reference row are arranged in a straight line in the transport direction. For this reason, the boundary line of the forward path line and the backward path line may not be visible. Paying attention to only the dots (•) of the K2 row that is the adjustment row, the dots of the K2 row of the forward path and the dots of the K2 row of the backward path deviate in the movement direction. However, since the dots of the K1 row are positioned between the dots of the K2 row of the forward path and the dots of the K2 row of the backward path, the deviation of the forward and backward dot formation positions of the K2 row is invisible.
That is, in the adjustment method of the embodiment, the dot formation positions of two nozzle rows (K1 and K2) ejecting the same color of ink are shifted in the movement direction, thereby forming a relatively thick line. At the ridge portion of the medium S, the line at the backward path time deviates to the right side in the movement direction with respect to the line at the forward path time. However, the line is thick, and thus the joint can be hardly visible since the position in the movement direction of the forward path line is partially overlapped with the position in the movement direction of the backward path line. That is, the forward path line and the backward path line are made thick, and the whole line is made vague, such that the joint of the forward path line and the backward path line is made invisible. The embodiment is not limited to the case of forming the line. According to the adjustment method of the embodiment, it is possible to reduce the dissatisfaction of the joint of the image formed on the forward path and the image formed on the backward path.
At the intermediate portion of the medium S, the paper gap PG3 becomes larger than that of the ridge portion. Since the forward and backward ejection time is adjusted such that the dot formation positions of the forward path and the backward path of the K1 row (reference row) at the ridge portion coincide with each other, the dots of the K1 row of the forward path deviate to the right side in the movement direction and the dots of the K1 row of the backward path deviate to the left side in the movement direction, at the intermediate portion. However, since the dots of the K2 row are shifted on the side opposite to the head movement direction with respect to the dots of the K1 row, deviation in the movement direction of the dots (o) of the K1 row of the forward path and the dots (•) of the K2 row of the backward path is small, and deviation in the movement direction of the dots (•) of the K2 row of the forward path and the dots (o) of the K1 row of the backward path is small, as shown in
Since the paper gap PG2 gets larger at the valley portion of the medium S, the dots of the K1 row (reference row) in which the forward and backward dot formation positions are adjusted at the ridge portion deviate to the right side in the movement direction at the forward path time, and deviate to the left side in the movement direction at the backward path time. However, the dots of the K2 row (adjustment row) are formed at a position of the front side (the opposite side of the head movement direction) with respect to the dots of the K1 row. For this reason, position deviation in the movement direction of the dots of the K2 row of the forward path and the dots of the K2 row of the backward path is small, and the joint of the forward path and the backward path is hardly visible. In the whole line, the position in the movement direction of the thick line of the forward path is partially overlapped with the position in the movement direction of the thick line of the backward path, and the joint can be made hardly visible.
For this reason, in
Similarly, at the intermediate portion of the medium S, deviation in the movement direction of the thick line of the forward path and the thick line of the backward path is small, and the joint of the forward path and the backward path is hardly visible. At the ridge portion of the medium S, deviation in the movement direction of the dot formation positions of the forward path and the backward path of the K2 row (adjustment row) is small, and the thick line of the backward line deviates to the right side in the movement direction with respect to the thick line of the forward path. However, since the positions in the movement direction of two lines are partially overlapped with each other, the joint can be made hardly visible.
As described above, in the adjustment method of the embodiment, at the ridge portion or the valley portion of the medium S, the forward and backward dot formation positions of one reference row of two nozzle rows (K1 and K2) ejecting the same color of ink are arranged. The dot formation position of the other adjustment row is shifted with respect to the dot formation position of the reference row. However, the forward and backward dot formation positions of the reference row at the intermediate portion of the medium S may not be arranged. For example, it is assumed that the dot formation positions of the K1 row are arranged at the intermediate portion and the dot formation positions of the K2 row are adjusted to the front side (the opposite side of the head movement direction) with respect to the dot formation positions of the K1 row as shown in
Herein, the K1 row of two nozzle rows (K1 row and K2 row) ejecting the same color of ink is the reference row, the dot formation positions in the movement direction of the forward path and the backward path are arranged at the ridge portion or the valley portion of the medium S, but the invention is not limited thereto. At the ridge portion or the valley portion of the medium S considering the K2 row as the reference row, the dot formed portions in the movement direction of the forward path and the backward path may be arranged, and the dot formation position of the K1 row (adjustment row) may be shifted in the movement direction with reference to the dot formation position of the K2 row. The invention is not limited to alternately forming the dots of the K1 row and the K2 row in the transport direction, and the dots of the same nozzle row may be continuously printed at a plurality of distances.
In the design process, as shown in
The amount of ink ejected to the medium varies according to a printed image, and a method of occurrence of the cockling phenomenon is different. When the amount of ink ejected to the medium is small, no cockling phenomenon occurs. Thus, in the adjustment method of the embodiment, it is determined whether or not to perform the printing using the cockling adjustment value R according to the amount of ink ejected to the medium. As the amount of ink ejected to the medium gets larger, the medium S positioned between the convex portions 211 of the platen 21 is more easily bent downward, and a difference of the platen gap PG at the valley portion and the ridge portion of the medium S gets larger. Thus, in the adjustment method of the embodiment, the cockling adjustment value R is changed according to the amount of ink ejected to the medium (according to the change amount of the platen gap PG). Herein, it is determined whether or not to use the cockling adjustment value R according to an “ink duty”, and the used cockling adjustment R is determined. The ink duty is the ratio of the number of dots actually ejected to a unit area with respect to the number of dots capable of being ejected to the unit area of the medium S (the ratio of the number of actually ejected dots in one pass to the number of dots capable of being ejected in one pass).
In the embodiment, when the ink duty is 50% or higher, it is assumed that the cockling phenomenon shown at the lower part of
The platen 21 is provided with the plurality of convex portions 211 at a predetermined distance in the movement direction. For this reason, the K1 row forms the forward path line and the backward path line at the parts of the medium supported by the plurality of convex portions 211 (in
In the embodiment, as shown in
The tester confirms the pattern (
In the embodiment, as shown in
In the pattern shown in
The cockling adjustment value R corresponds to a value indicating a difference (time) between the designed ink ejection time from the nozzles and the time when actually ejecting ink from the nozzles. Specifically, the cockling adjustment value R is a value indicating “the number of pixels”. To print an image on the medium S, pixels are virtually determined on the medium S, and the image is presented on the medium S according to whether or not dots are formed at the pixels. The printer 1 prints the image on the medium S on the basis of printing data indicating whether or not dots are formed at the pixels. For this reason, the printing data corresponding to the pixels are shifted in the movement direction for a pixel unit, and thus the dot formation positions can be shifted in the movement direction. Therefore, when the printing data corresponding to the pixels are shifted, the ink ejection time is adjusted, and the cockling adjustment value corresponds to “the number of pixels” when the dot formation positions are shifted in the movement direction.
However, the invention is not limited thereto. To eject ink from the nozzles, it is preferable to apply a driving wave form to a driving element (e.g., piezoelectric element) corresponding to the nozzles. To put the dot formation positions aside, (to adjust the ink ejection time) the time of applying the driving waveform to the driving element may be adjusted. In this case, specifically, the cockling adjustment value R is a value indicating “a difference (time) between the application timing of the designed driving waveform and the timing of actually applying the driving waveform”.
Since the plurality of convex portions 211 of the platen 21 are arranged in the movement direction, there is a plurality of valley portions of the medium S. Thus, as shown in
The tester calculates the cockling adjustment value R2 of the K2 row such that the dot formation position of the K2 row that is the adjustment row is positioned on the front side (the opposite side to the head movement direction) by a distance “L/2” with respect to the dot formation position of the K1 row that is the reference row (S005). That is, the dot formation position of the K2 row is positioned on the front side with respect to the dot formation position of the K1 row by a half of the length “L/2” of the amount of deviation L of the forward and backward dot formation positions of the K1 row at the valley portions of the medium S.
As shown in
The dots (•) of the K2 row are shifted by “L/2” with respect to the dots (o) of the K1 row, and thus the forward and backward dot formation positions in the movement direction of the K2 row can be arranged at the valley portions of the medium S. In such a manner, at the valley portions of the medium S, the dots of the forward path and the dots of the backward path of the K1 row deviate most in the movement direction, but the dots of the K2 row are arranged in a straight line in the transport direction. Accordingly, the joint of the forward path line and the backward path line can be hardly visible.
The tester causes the printer 1 to print a pattern (not shown) to calculate the cockling adjustment value R2 for positioning the dot formation position of the K2 row on the front side (the opposite side to the head movement direction) by the distance “L/2” with respect to the dot formation position of the K1 row. For example, it is preferable that the ejection time of the K1 row is adjusted with the cockling adjustment value R1, the ejection time of the K2 row is variously changed, the line of the K1 row (the forward path or the backward path) is formed and the line of the K2 row (the forward path or the backward path) is formed. The medium S printing the pattern may be the medium S on which the cockling phenomenon is reproduced and the other medium on which the cockling phenomenon is not reproduced. The tester determines the ejection time when the line of the K2 row deviates at the position on the front side (the side opposite to the side where the head moves) in the movement direction by the distance “L/2” with respect to the line of the K1 row. A value corresponding to a difference between the determined ejecting time of the K2 row and the designed ejection time of the K2 row is calculated as the cockling adjustment value R2. The cockling adjustment values R2 of the K2 row corresponding to two cockling adjustment values R1 of the K1 row according to the ink duty is calculated. In such a manner, the cockling adjustment values R1 and R2 calculated in the mass-production process are stored in the memories 13 of the printers 1, and then the printers 1 are shipped.
Herein, the dot formation position of the K2 row is shifted by the distance “L/2” at the position opposite to the side where the head 41 moves with respect to the dot formation position of the K1 row, but the invention is not limited thereto. When the dot formation positions of the forward path and the backward path of the K1 row are aligned at the ridge portions, the amount of deviation L of the dot formation positions of the forward path and the backward path of the K1 row is largest at the valley portions of the medium S. For this reason, it is preferable that the dot formation position of the K2 row is shifted at the position opposite to the side the head 41 moves by at least a length of L or less with respect to the dot formation position of the K1 row. In such a manner, at the valley portions of the medium S, the dots of the K2 row can be positioned between the dots of the K1 row of the forward path and the dots of the K1 row of the backward path, and the joint of the forward path line and the backward path line can be made hardly visible.
In the adjustment example (
In the embodiment, when the cockling phenomenon does not occur (when the ink duty is lower than 50%), the dot formation positions of the reference row (K1 row) and the adjustment row (K2 row) are arranged, but the invention is not limited thereto. Even when the cockling phenomenon does not occur, the dot formation position of the adjustment row (K2 row) may be shifted in the movement direction with respect to the dot formation position of the reference row (K1 row) similarly to the case where the cockling phenomenon occurs.
When the printer 1 receives a printing instruction and printing data from a printer driver installed in the computer 60, the controller 10 (control unit) of the printer 1 determines whether or not two-direction printing is set. When the two-direction printing is performed and the cockling phenomenon occurs on the medium S, the dots are formed as shown in
The ink duty is calculated for each color of ink (YMCK), the ink ejection time may be adjusted for each nozzle row, and the ink ejection time may be adjusted on the basis of the maximum value in the ink duty of each ink. The invention is not limited to the “maximum ink duty” of the image printed on the medium S, and the cockling adjustment value R may be determined by determining whether or not the cockling phenomenon occurs on the medium S on the basis of the average ink duty.
As described above, when it is determined whether or not to use the cockling adjustment value on the basis of the ink duty (the maximum value or the average value) in the whole image printed on the medium S, the printing control is relatively easy. However, there is a case where the cockling phenomenon does not occur according to the position of the medium S. However, the paper gap (i.e., the designed paper gap PG) when the cockling phenomenon does not occur becomes a value between the paper gap (PG1 in
In Printing Example 2, the controller 10 calculates the ink duty (the maximum value or the average value) for each image printed in each pass, and determines whether or not to use the cockling adjustment R in the pass. In such a manner, for example, even on the same medium, the image is printed using the Bid adjustment value without using the cockling adjustment R in the medium area where an image (text image) of a low ink duty is printed, and an image is printed using the cockling adjustment value R in the medium area where an image of a high ink duty is printed. As a result, in the image of the low ink duty, the dot formation positions of two nozzle rows (e.g., K1 and K2) ejecting the same color of ink do not deviate in the movement direction. In addition, in the image of the high ink duty, it is possible to reduce the dissatisfactory of the joint of the forward path image and the backward path image even when the cockling phenomenon occurs.
In the example described in
For this reason, the controller 10 of the printer 1 determines whether or not data for printing the line along the transport direction on the forward path and the backward path is within the received printing data. When there is data for printing the line along the transport direction on the forward path and the backward path, the controller 10 determines whether or not the line is printed in the medium area on which the cockling phenomenon occurs. For example, it is determined whether or not the line is formed on the image with the ink duty of 50% or higher or around the image with the ink duty of 50% or higher. When the line is printed in the medium area on which the cockling phenomenon occurs, the controller 10 prints the line at the ejecting time adjusted with the cockling adjustment value R.
In the embodiments, the printing system having the ink jet printer has been mainly described, but the invention includes disclosure such as the method of suppressing the deviation of the dot formation positions. The embodiments are to make the invention easily understood, and are not to restrictively analyze the invention. The invention can be modified and improved within the concept thereof, and obviously includes equivalent materials thereof. Particularly, the invention includes the following embodiments.
In the embodiments, the printer ejecting three colors of ink YMC and the black ink K is exemplified, but the invention is not limited thereto. There is a printer ejecting white ink W in addition to such ink (YMCK). In such a printer 1, there is a case where a monochromatic image or a color image is repeatedly printed on the background image formed by the white ink to improve the chromatic property of the image. When such printing is performed, it is assumed that the cockling phenomenon occurs on the medium S by printing the background image. Accordingly, the ink ejection time may be adjusted using the cockling adjustment value R to print the color image or the monochromatic image without determining the ink duty.
In the embodiments, as shown in
In the embodiments, the cockling adjustment value R varies according to the ink duty or the kind of the medium, but the invention is not limited thereto. For example, there is a case where the method of occurrence of the cockling phenomenon may also vary according to the kind of ink ejected onto the medium. For this reason, the cockling adjustment value R may vary according to the kind of the ink.
In the embodiments, the printer repeating the operation of forming the image on one paper surface while moving the head in the movement direction and the operation of transporting the paper in the transport direction crossing the movement direction with respect to the head is exemplified, but the invention is not limited thereto. For example, there may be a printer repeating an operation of forming an image while moving a head unit having (a plurality of) heads in the medium transport direction and an operation of moving the head unit in the paper width direction to form an image on continuous paper sheets transported to the printing area, and transporting the part of the medium which has been not printed yet to the printing area.
In the embodiments, the ink jet printer has been exemplified as the fluid ejecting apparatus, but the invention is not limited thereto. The fluid ejecting apparatus can be applied to various industrial apparatuses other than printer (printing device). For example, the invention can be applied to a printing apparatus for attaching a pattern to cloth, a display producing apparatus such as a color filter producing apparatus and an organic EL display, and a DNA chip producing apparatus for producing a DNA chip by applying a solution with dissolved DNA to the chip.
The entire disclosure of Japanese Patent Application No. 2010-009398, filed Jan. 19, 2010 is expressly incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-009398 | Jan 2010 | JP | national |
