1. Technical Field
The present invention relates to fluid ejecting apparatuses and fluid ejecting methods.
2. Related Art
Printing apparatuses have been developed that perform printing on a medium by repeating an ink ejection operation a plurality of times, in which a head is moved in a direction that intersects with a nozzle row (main scan direction) while ink is ejected onto the medium. In such a printing apparatus, the head is moved in a direction in which the nozzle row extends (sub-scan direction) during printing between each of the ink ejection operations. Such a printing apparatus performs an interlace printing in which the head is moved in the sub-scan direction at a constant pitch in order to reduce the occurrence of so-called banding, which may be caused by different properties of the respective nozzles. JP-A-11-34398 is an example of related art.
During movement of the head in the sub-scan direction, a paper sheet may sometimes expand and/or contract due to an effect of the ink that has landed on the paper sheet. If the ink ejection operation is performed in order to form dots on the paper sheet which has undergone such an expansion and/or contraction, the positions of lines which are formed by the dots may deviate from intended positions due to an effect of the expansion and/or contraction of the paper sheet. This degrades the quality of the resultant image. Therefore, it is desirable to reduce misalignment of the dot-lines.
An advantage of some aspects of the invention is that misalignment of the dot-lines formed by the ejected fluid is reduced.
According to an aspect of the invention, a fluid ejecting apparatus includes a nozzle row in which a plurality of nozzles that eject fluid onto a medium are arranged, a first movement unit that displaces a relative position between the medium and the nozzle row in a cross direction that intersects with a direction in which the nozzle row extends, a second movement unit that displaces the relative position between the medium and the nozzle row in a nozzle row direction in which the nozzle row extends, and a control unit that forms a plurality of dot-lines by alternately repeating a fluid ejection operation in which the relative position in the cross direction is displaced while fluid is ejected so as to form a dot-line and a displacement operation in which the relative position in the nozzle row direction is displaced, the control unit controlling the fluid ejection operation and the displacement operation to be performed to form adjacent dot-lines in the plurality of dot-lines such that a maximum time between when one of the adjacent dot-lines is formed to when the other of the adjacent dot-lines is formed is smaller than that in the case where one of the adjacent dot-lines is formed by a first fluid ejection operation and then the other of the adjacent dot-lines is formed at a position between the dot-lines formed by the first fluid ejection operation in sequence from one end of the nozzle row.
The other characteristics of the invention will be apparent from the description herein taken in conjunction with the accompanying drawings.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
The description herein and the accompanying drawings will describe at least the following:
a fluid ejecting apparatus including a nozzle row in which a plurality of nozzles that eject fluid onto a medium are arranged, a first movement unit that displaces a relative position between the medium and the nozzle row in a cross direction that intersects with a direction in which the nozzle row extends, a second movement unit that displaces the relative position between the medium and the nozzle row in a nozzle row direction in which the nozzle row extends, and a control unit that forms a plurality of dot-lines by alternately repeating a fluid ejection operation in which the relative position in the cross direction is displaced while fluid is ejected so as to form a dot-line and a displacement operation in which the relative position in the nozzle row direction is displaced, the control unit controlling the fluid ejection operation and the displacement operation to be performed to form adjacent dot-lines in the plurality of dot-lines such that a maximum time between when one of the adjacent dot-lines is formed to when the other of the adjacent dot-lines is formed is smaller than that in the case where one of the adjacent dot-lines is formed by a first fluid ejection operation and then the other of the adjacent dot-lines is formed at a position between the dot-lines formed by the first fluid ejection operation in sequence from one end of the nozzle row. With this configuration, misalignment of the dot-lines formed by the ejected fluid can be reduced.
In the fluid ejecting apparatus according to the above aspect, the control unit may be configured to control the fluid ejection operation and the displacement operation to be performed such that, after a certain dot-line is formed, the next two dot-lines are alternately formed on both sides of the previously formed dot-line, which is taken as a center dot-line. With this configuration, misalignment of positions of dots can be reduced while the dot-lines are formed in a regular manner.
In the fluid ejecting apparatus according to the above aspect, a displacement amount in the nozzle row direction is preferably larger than a nozzle pitch of the nozzles. With this configuration, the dot-lines can be formed in an order dispersed in the nozzle row direction. Accordingly, misalignment of positions of dots formed by the ejected fluid can be reduced.
Further, the fluid ejecting apparatus according to the above aspect preferably include a head unit having a plurality of the nozzle rows, and a length of the head unit in the nozzle row direction is preferably larger than a width of the medium in the nozzle row direction. Further, a distance between the nozzles on the head unit at both ends in the nozzle row direction is preferably larger than the width of the medium in the nozzle row direction. Accordingly, since the width of the head unit is longer than the width of the medium, fluid can be ejected onto a wide area on the medium with a single fluid ejection operation, so that misalignment of positions of dots medium can be reduced even in a circumstance that the medium is subject to expansion and/or contraction.
Further, the first movement unit preferably moves the nozzle row in the cross direction. With this configuration, the fluid ejection operation can be performed with the medium being fixed in position.
Further, the fluid ejecting apparatus according to the above aspect preferably include a third movement unit that transports the medium in the cross direction after all the dot-lines are formed on the medium. With this configuration, after fluid ejection is performed across the entire surface on a predetermined area of the medium, fluid can be performed on another area of the medium.
The description herein and the accompanying drawings will further describe:
A fluid ejecting method for use in a fluid ejecting apparatus including a nozzle row in which a plurality of nozzles that eject fluid onto a medium are arranged, a first movement unit that displaces a relative position between the medium and the nozzle row in a cross direction that intersects with a direction in which the nozzle row extends, and a second movement unit that displaces the relative position between the medium and the nozzle row in a nozzle row direction in which the nozzle row extends, wherein a plurality of dot-lines are formed by alternately repeating a fluid ejection operation in which the relative position in the cross direction is displaced while fluid is ejected so as to form a dot-line and a displacement operation in which the relative position in the nozzle row direction is displaced, the fluid ejecting method including performing the fluid ejection operation and the displacement operation so as to form adjacent dot-lines in the plurality of dot-lines such that a maximum time between when one of the adjacent dot-lines is formed to when the other of the adjacent dot-lines is formed is smaller than that in the case where one of the adjacent dot-lines is formed by a first fluid ejection operation and then the other of the adjacent dot-lines is formed at a position between the dot-lines formed by the first fluid ejection operation in sequence from one end of the nozzle row. With this configuration, misalignment of the dot-lines formed by the ejected fluid can be reduced.
A printing system in which a printer and a computer are connected to each other will be explained as an example of the invention. In the following description, an ink jet printer (hereinafter referred to as “printer”) is taken as an example of a fluid ejecting apparatus.
A controller 10 is a control unit that controls the printer 1. An interface 11 is provided for transmitting and/or receiving data between the computer 60 and the printer 1. A CPU 12 is a processing unit that controls the overall printer 1. A memory 13 is provided for ensuring a program storage area and a working area of the CPU 12. The CPU 12 controls each of the units through a unit control circuit 14. Further, a group of detectors 50 is provided for monitoring the situation in the printer 1 so that the controller 10 controls each of the units based on the detection results.
A transportation unit 20 is provided for sequentially transporting media S in an upstream to downstream direction (hereinafter, referred to as “transportation direction”). Transportation rollers 21 driven by a motor are provided so as to supply a medium S in a roll form prior to printing into a printing area. Then, a wind-up mechanism winds the printed medium S into a roll form. Moreover, when fed into the printing area, the medium S can be retained in a predetermined position by applying vacuum suction to the underside.
A drive unit 30 is configured to freely move a head unit 40 in an X direction which corresponds to the transportation direction of the medium S and in a Y direction which corresponds to a sheet width direction of the medium S. The drive unit 30 is composed of an X axis stage 31 on which the head unit 40 is moved in the X direction, a Y axis stage 32 on which the head unit 40 is moved in the Y direction, and a motor (not shown) which drives those stages.
The head unit 40 is provided for forming images and includes a plurality of heads 41. The underside of the head 41 is provided with a plurality of nozzles through which ink is ejected. The respective nozzles communicate with a pressure chamber which is filled with ink. The ejection of ink may be carried out using the piezoelectric technique in which a voltage is applied to piezoelectric elements (drive elements) so as to expand and/or contract the pressure chamber to expel ink through the nozzles, or alternatively, the thermal technique in which bubbles are generated within the nozzles by heat generating elements (drive elements) so that the bubbles expel ink through the nozzles.
Each head 41 has a nozzle surface on which eight nozzle rows are arranged as shown in
Further, in two heads adjacent in the Y direction (for example, heads 41(1) and 41(2)), four nozzles from the lowest (nozzle #177, nozzle #178, nozzle #179 and nozzle #180) of the upper head (head 41(1)) and four nozzles from the highest (nozzle #1, nozzle #2, nozzle #3 and nozzle #4) of the lower head (head 41(2)) are aligned in the Y direction. Accordingly, the head 41(1) to the head 41(15) are arranged to establish the above relationship. With this arrangement, the head unit 40 can be regarded as a large single head which is capable of ejecting ink onto the area covered by the head 41(1) to head 41(15) when the head unit 40 is moved in the X direction. In this large integrated head unit 40, the nozzle #1 of the head 41(2) serves as the nozzle #177, the nozzle #2 serves as the nozzle #178, the nozzle #3 serves as the nozzle #179, and the nozzle #4 serves as the nozzle #180.
When nozzles are arranged in the above-mentioned manner in which two groups of nozzles overlap when viewed in the X direction, ink is ejected from one of the overlapping nozzle groups. For example, when ink is ejected from the nozzle #177 to the nozzle #180 of the head 41(1), ink is not ejected from the nozzle #1 to the nozzle #4 of the head 41(2). Similarly, when ink is ejected from the nozzle #1 to the nozzle #4 of the head 41(2), ink is not ejected from the nozzle #177 to the nozzle #180 of the head 41(1).
Further, the width of the head unit 40 in the sheet width direction is longer than the width of the paper sheet in the Y direction in the first embodiment. More specifically, the distance from the nozzle #1 of the head 41(1) to the nozzle #180 of the head 41(15) is longer than the width of the paper sheet in the Y direction. With this configuration, ink can be ejected so as to land on a wide area on the paper sheet with a single ink ejection operation (the ink ejection operation will be described later in detail).
Printing processes are as follows. First, the medium S is supplied to the printing area by the transportation unit 20. Then, the ink ejection operation (which corresponds to a fluid ejection operation), in which the head unit 40 is moved in the X direction (transportation direction of the medium) by using the X axis stage 31 while ink is ejected through the nozzles, and a transportation operation (which corresponds to a displacement operation), in which the head unit 40 is moved toward the lower end in the Y direction (sheet width direction) by using the Y axis stage 32 via the X axis stage 31, are alternately repeated. As a result, dots can be formed during each ink ejection operation with the positions of dots being offset from the previous positions, such that a 2D image can be printed. When printing on the medium S in the printing area is completed, the unprinted part of the medium S is fed to the printing area by means of the transportation unit 20 so that an image is printed on the part of the medium S which is newly fed to the printing area. A single ink ejection operation is hereinafter also referred to as a “pass”.
Consequently, when printing is performed under the condition that the paper sheet does not expand and/or contract during printing, the dot-lines formed during the pass 1 to pass 4 are appropriately disposed at intervals of 720 dpi in the Y direction.
A description of how to dispose dot-lines at appropriate intervals in the Y direction in the case where the paper sheet expands and/or contracts as mentioned above follows.
Each numeral enclosed in the rectangle corresponds to the nozzle number. To facilitate explanation, only the nozzle #1 to nozzle #3 are shown in
In
Next, the head is moved in the Y direction by 720 dpi. Then, ink is ejected in the pass 2, for example, the nozzle #1 forms the second raster line, while the nozzle #2 forms the 10th raster line. Similarly, nozzles of other nozzle numbers form the corresponding raster lines. Accordingly, the respective raster lines are formed by repeating such operations.
During printing performed by the above-mentioned operations, the quality of the resultant image is affected by a time difference that exists between passes in which adjacent raster lines are formed. Here, the difference that exists between passes in which adjacent raster lines are formed is referred to as “time difference between the passes of adjacent raster lines” and defined as follows:
Absolute value (pass number of the pass in which the ith raster line is formed−pass number of the pass in which the (i+1)th raster line is formed)
For example, in the above reference example, the time difference between the passes of the first raster line and the second raster line is expressed by the absolute value (pass number of the pass in which the first raster line is formed−pass number of the pass in which the second raster line is formed), that is, the absolute value of (1−2), which results in the time difference between the passes being “1”. Further, for example, the time difference between the passes of the eighth raster line and the ninth raster line is expressed by the absolute value (pass number of the pass in which the eighth raster line is formed−pass number of the pass in which the ninth raster line is formed), that is, the absolute value of (8−1), which results in the time difference between the passes being “7”.
The larger the time difference between the passes of raster lines is, the larger the degree of expansion and/or contraction of the paper sheet that occurs between the successive passes. That is, positions of dots of the raster lines in the Y direction are less appropriately aligned. Specifically, when the time difference between the passes of raster lines significantly varies, the degree of expansion and/or contraction of the paper sheet that occurs between the successive passes also becomes large, resulting in the positions of dots in the Y direction being significantly misaligned. For example, in the case of
As described above, when the time difference between the raster lines significantly varies, the quality of the resultant image decreases. Accordingly, it is desirable that the time difference between the passes varies to a lesser extent. That is, it is desirable that the head moves during printing so that a maximum time difference between the passes becomes smaller than a maximum time difference between the passes which is shown in
In
Next, the head is moved in the Y direction by 363×1440 dpi. Then, ink is ejected in the pass 2, for example, the nozzle #270 forms the fifth raster line, while the nozzle #271 forms the 13th raster line. Accordingly, as far as shown in
The head unit 40 is moved in the Y direction by an amount which corresponds to the “feeding distance” during printing such that dots are formed in the subsequent passes. As a result, printing is performed in the printable area with a resolution of 1440 dpi.
In
The following explains operations of the fluid ejecting apparatus according to a second embodiment. In the second embodiment, printing with a printing resolution of 720 dpi will be explained. Although the fluid ejecting apparatus of the second embodiment operates in a manner different from that of the first embodiment, the apparatus itself has the same configuration as that of the first embodiment, and the configuration of the fluid ejecting apparatus will not be explained further.
Also in
Further, in
In the foregoing embodiments, the printer 1 has been described as an example of fluid ejecting apparatus. However, the invention is not limited to the above description, and can be implemented as liquid ejecting apparatuses that eject or discharge fluid other than ink (e.g., liquid, liquid-like material in which particles of functional material are dispersed, and fluid-like material such as gel). For example, the similar technique to that described in the foregoing embodiments can be applied to various apparatuses in which ink jet technique is employed, such as color filter manufacturing apparatuses, dyeing machines, micro processing machines, semiconductor manufacturing apparatuses, surface processing machines, 3D forming machines, gas vaporizers, organic EL manufacturing apparatuses (especially, polymer EL manufacturing apparatuses), display manufacturing apparatuses, film deposition apparatuses, and DNA chip manufacturing apparatuses. Further, the methods and manufacturing methods used in the above apparatuses are intended to be within the scope of the invention.
The foregoing embodiments are described to facilitate understanding of the invention and are not intended to limit the interpretation of the invention. Various modifications and improvements can be made to the invention without departing from the spirit of the invention, and needless to say, the equivalents are included within the scope of the invention.
The entire disclosure of Japanese Patent Application No. 2010-200178, filed Sep. 7, 2010 is expressly incorporated by reference herein.
Number | Date | Country | Kind |
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2010-200178 | Sep 2010 | JP | national |