WO2015053103A1

WO2015053103A1 - Printing device and printing method

Info

Publication number: WO2015053103A1
Application number: PCT/JP2014/075779
Authority: WO
Inventors: 大西　勝
Original assignee: 株式会社ミマキエンジニアリング
Priority date: 2013-10-07
Filing date: 2014-09-29
Publication date: 2015-04-16
Also published as: JP2015074112A

Abstract

　The problem addressed by the present invention is to appropriately reduce the number of passes required for printing.　The means of solving the problem is a printing device (10) that performs inkjet printing, comprising: a plurality of inkjet heads (12) positioned in the first scan direction, each of the plurality of inkjet heads respectively discharging droplets of the same color ink; a first scan drive unit (14); and a second scan drive unit (16). The plurality of inkjet heads (12), by means of the first scan operation, forms rows of dots of ink formed by ink droplets landing on a medium, the rows of dots being rows in which dots of ink in the first scan direction are lined up by aligning the position in the second scan direction, and forms rows of dots of ink adjoining one another in the first scan direction by means of different inkjet heads (12).

Description

Printing apparatus and printing method

The present invention relates to a printing apparatus and a printing method.

Conventionally, ink jet printers that perform printing by an ink jet method have been widely used (for example, see Non-Patent Document 1). An ink jet printer performs printing on a medium by ejecting ink droplets from nozzles formed on an ink jet head.

In addition, in an inkjet printer, a serial inkjet printer that causes an inkjet head to perform a main scanning operation is widely used. Also, serial-type inkjet printers are widely used for multi-pass printing. In this case, printing in the multi-pass method is to perform printing by performing a plurality of main scanning operations on the same area on the medium. The main scanning operation is an operation in which the ink jet head ejects ink droplets while moving in a predetermined main scanning direction.

Serial ink jet printers print on media by performing multiple main scanning operations. In each main scanning operation, the stopped inkjet head is accelerated in the main scanning direction, and then the inkjet head is moved in the main scanning direction at a constant speed. Further, at the end of each main scanning operation, the speed of the inkjet head is reduced until the inkjet head stops.

However, in this operation, ink droplets are ejected onto the medium only while the inkjet head is moved in the main scanning direction at a constant speed. For this reason, the time required for acceleration and deceleration of the inkjet head during the main scanning operation is wasted time (loss time) other than the time during which ink droplets are actually ejected. Therefore, it is desirable to reduce the time required for acceleration and deceleration of the ink jet head as much as possible.

However, when printing by the multi-pass method, if the number of passes increases, the number of main scanning operations also increases according to the number of passes. As a result, the number of times the inkjet head is accelerated and decelerated increases. Therefore, when printing is performed by the multi-pass method, if the number of passes increases, the time required for printing increases due to the effect of the loss time, and the printing speed may be significantly reduced. Accordingly, an object of the present invention is to provide a printing apparatus and a printing method that can solve the above-described problems.

In serial type inkjet printers, multi-pass printing is usually performed for the purpose of averaging the ejection characteristics of the nozzles of the inkjet head and increasing the resolution. Averaging of nozzle ejection characteristics means, for example, by performing a sub-scanning operation between each main scanning operation to eject ink droplets to that region in a plurality of main scanning operations performed on the same region on the medium. Different nozzles are used to average the discharge characteristics of the nozzles that discharge ink droplets to the region. The sub-scanning operation is an operation for moving the inkjet head relative to the medium in the sub-scanning direction orthogonal to the main scanning direction.

Further, high resolution by the multi-pass method means printing by a multi-pass method, so that the resolution in the sub-scanning direction is a dot density (dpi) resolution narrower than the nozzle pitch in the inkjet head. It is. In this case, the pitch of the nozzles in the inkjet head is the interval between the nozzles in a nozzle row in which a plurality of nozzles are arranged in the sub-scanning direction in the inkjet head. The high resolution by the multi-pass method is not an integer multiple of the nozzle pitch, but an integer of the nozzle pitch, for example, in setting the amount of movement for moving the inkjet head relative to the medium in one sub-scanning operation. This can be done by setting the distance shifted from the double by the 1 / n pitch (n is an integer of 2 or more). More specifically, for example, by setting the amount of movement of the inkjet head in one sub-scanning operation to a distance shifted by 1/2 pitch from an integral multiple of the nozzle pitch, it is ½ of the nozzle pitch. Printing can be performed with a resolution of dot density corresponding to the distance.

On the other hand, the inventor of the present application has conducted intensive research and arranged a plurality of inkjet heads in a predetermined arrangement without averaging the ejection characteristics of the nozzles of the inkjet heads, even if printing is not performed in a multi-pass method. I found out that it can be realized. In this case, for example, if printing is performed with only the number of passes necessary for the purpose of increasing the resolution, printing at a high resolution can be performed appropriately. This also makes it possible to appropriately reduce the number of passes required for printing. In addition, when it is not necessary to increase the resolution by the multi-pass method, it is possible to appropriately perform high-quality printing without performing the multi-pass method. In order to solve the above problems, the present invention has the following configuration.

(Configuration 1) A printing apparatus that performs printing by an inkjet method, and is a plurality of inkjet heads that respectively eject ink droplets of the same color ink, and a plurality of inkjets arranged side by side in a preset main scanning direction A main scanning drive unit that causes a plurality of inkjet heads to perform a main scanning operation of ejecting ink droplets while moving in the main scanning direction, and a plurality of relative to the medium in a sub-scanning direction orthogonal to the main scanning direction. And a sub-scan driving unit that changes a position where the main scanning operation is performed on the medium by moving the ink-jet head, and the plurality of ink-jet heads cause ink droplets to land on the medium by the main scanning operation. This is a line where the ink dots to be formed are aligned, and the ink dots are aligned in the main scanning direction at the same position in the sub-scanning direction. Forming a preparative column, and so as to form a dot of ink adjacent in the main scanning direction at different ink jet head, to form a dot row.

In such a configuration, the ink dots constituting the dot row formed by each main scanning operation are formed by a plurality of inkjet heads. Therefore, with this configuration, for example, the ejection characteristics of the nozzles can be appropriately averaged in each main scanning operation.

Also, in this case, for example, it is not necessary to perform printing with a plurality of passes for the purpose of averaging the discharge characteristics of the nozzles, so that the number of passes required for printing can be appropriately reduced. For example, when printing is performed with a resolution of dot density corresponding to a half of the nozzle pitch in the inkjet head with respect to the resolution in the sub-scanning direction, the number of printing passes can be reduced to twice. In addition, for example, when it is not necessary to make the resolution higher than the pitch of the nozzles, it is possible to perform only one main scanning operation on each area on the medium without performing the multi-pass printing. It is done.

Therefore, with this configuration, for example, the number of printing passes can be appropriately reduced. This also shortens the loss time required for acceleration and deceleration of the inkjet head during the main scanning operation, and can appropriately improve the printing speed.

(Configuration 2) The ink tank further includes an ink tank that stores ink at positions separated from the plurality of inkjet heads, and an ink supply path that supplies ink from the ink tank to the plurality of inkjet heads.

A configuration using an ink tank provided at a position separated from the ink jet head is often used in, for example, a large ink jet printer. In a large inkjet printer, it is desired to increase the moving speed of the inkjet head during the main scanning operation in order to perform printing on a large medium.

However, when the moving speed of the ink jet head during the main scanning operation is increased, the time required for acceleration and deceleration also increases. For this reason, for example, when the number of printing passes is large, the loss time may increase and the printing speed may decrease. On the other hand, when configured as in configuration 2, the number of printing passes can be appropriately reduced. This also makes it possible to more appropriately realize high-speed printing, for example, when the moving speed of the inkjet head during the main scanning operation is increased.

(Structure 3) The ink supply path is configured to change the pressure applied to the inkjet head from the ink supply path during acceleration when the inkjet head accelerates in the main scanning direction and during deceleration when the inkjet head decelerates in the main scanning direction. It is configured to suppress.

The fluctuation in pressure applied to the inkjet head from the ink supply path is, for example, fluctuation in pressure applied to the ink in the inkjet head. The pressure fluctuation is caused by, for example, a fluctuation in the difference between the pressure in the ink supply path and the pressure in the inkjet head.

When accelerating or decelerating the ink jet head, the ink in the ink jet head and the ink included in the portion that moves with the ink jet head in the ink supply path are affected by the acceleration. As a result, the ink moves and pressure fluctuation may occur in the ink jet head, the ink supply path, or the like. As a result, there may be a problem in the state of the inkjet head.

More specifically, for example, when the ink supply path is not configured so as to suppress the pressure fluctuation as described above, if the acceleration is large when the inkjet head is accelerated, air is drawn from the nozzle, so-called dough removal. May occur. In addition, when the inkjet head is decelerated, if the acceleration (absolute value of acceleration) is large, the ink may spill out from the nozzles, which may cause a problem of so-called dropping. On the other hand, if it comprises like the structure 3, the problem which arises by the pressure fluctuation at the time of the acceleration of an inkjet head and deceleration can be suppressed appropriately.

This also makes it possible to accelerate and decelerate in a shorter time by increasing the absolute value of acceleration during acceleration and deceleration, for example. Therefore, with this configuration, for example, the loss time required for acceleration and deceleration of the inkjet head during the main scanning operation can be appropriately reduced.

(Configuration 4) The ink supply path includes an annular tube that is deformed in accordance with the movement of the inkjet head during the main scanning operation, and the annular tube forms at least a part of the ink flow path from the ink tank to the inkjet head. And has an ink introduction part for introducing ink from the ink tank side and an ink discharge part for discharging ink to the ink jet head side, and has such a length that the ink jet head can move over the entire printing range in the main scanning direction. Is formed.

In such a configuration, for example, when the ink jet head is accelerated and decelerated, even if the ink in the ink supply path moves due to the acceleration, the ink circulates in the annular tube, so that the ink jet head is affected. Hateful. Therefore, if comprised in this way, the fluctuation | variation of the pressure added to an inkjet head from an ink supply path can be suppressed appropriately at the time of acceleration and deceleration of an inkjet head, for example. In addition, for example, it is possible to appropriately prevent the occurrence of problems such as so-called “missing missing” and “missing”.

(Configuration 5) The ink supply path includes a flow path blocking section that blocks a flow path of ink from the ink tank to the inkjet head, and the flow path blocking section is configured to accelerate the inkjet head in the main scanning direction, and The flow path is shut off at each deceleration when the inkjet head decelerates in the main scanning direction.

When configured in this manner, for example, the ink flow path can be appropriately blocked when the inkjet head is accelerated and decelerated. Therefore, if comprised in this way, the fluctuation | variation of the pressure added to an inkjet head from an ink supply path can be suppressed appropriately at the time of acceleration and deceleration of an inkjet head, for example. In addition, for example, it is possible to appropriately prevent the occurrence of problems such as so-called “missing missing” and “missing”.

(Configuration 6) During the main scanning operation, the flow path blocking unit moves in the main scanning direction together with the ink jet head, and the flow path blocking unit generates inertia in the ink flow path during acceleration and deceleration, respectively. A moving member that moves along the ink flow path in response to the force, and a hollow body that accommodates the moving member therein, and is provided at a position in the middle of the ink flow path so that a part of the ink flow path is A storage portion that is formed, and the storage portion has an opening for flowing ink along the ink flow path on each of one side and the other side of the ink flow path, and the moving member is configured to flow the ink. It is possible to move the hollow portion of the container along the path, and has a size that does not pass through the opening on one side and the other side of the ink flow path. Block any opening in the housing It allows to block the flow path of the ink.

If configured in this manner, for example, the ink flow path can be appropriately blocked during acceleration and deceleration of the inkjet head. Note that the movement of the moving member according to the inertial force may be, for example, a movement according to the pressure of the ink moving due to the inertial force.

(Configuration 7) As a plurality of inkjet heads that respectively eject ink droplets of the same color ink, N (N is an integer of 3 or more) inkjet heads are provided, and in each main scanning operation, continuous in the main scanning direction. K of the N ink jet heads to form the ink dots to be formed (k is an integer of 2 or more and N-1 or less), and the main scanning direction is selected. The ink jet head to be selected is changed every time the k dots of the ink arranged in succession are formed.

Even in such a configuration, for example, in each main scanning operation, the ejection characteristics of the nozzles can be appropriately averaged by a plurality of inkjet heads. In this case, since printing is performed by selecting a smaller number of inkjet heads than the total number at each timing of the main scanning operation, for example, when there is an abnormality in the ejection characteristics of any inkjet head, It is possible to continue printing using the inkjet head. Therefore, if constituted in this way, for example, a high-performance printing apparatus having high resistance to failure or the like can be provided.

(Configuration 8) As a plurality of inkjet heads that eject ink droplets of the same color ink, N (N is an integer of 3 or more) inkjet heads are provided, and each inkjet head is a nozzle that ejects ink droplets. In any of the nozzles of any of the inkjet heads, an abnormality in the ejection characteristics of the ink droplets occurred in the N inkjet heads in each main scanning operation. A dot row is formed by (N−1) or less inkjet heads not including an inkjet head having nozzles.

With this configuration, for example, even when an abnormality occurs in the ejection characteristics of any nozzle of the inkjet head, printing can be performed appropriately without using the inkjet head in which the ejection characteristics are abnormal. Can do. Thereby, for example, it is possible to provide a high-performance printing apparatus that is highly resistant to failure or the like.

(Configuration 9) Each inkjet head has a nozzle for ejecting ink droplets, and if any of the nozzles in any of the inkjet heads has an abnormality in the ejection characteristics of the ink droplets, the ejection characteristics are abnormal. Ink dots to be formed by an abnormal nozzle that is an abnormal nozzle are formed by nozzles of an ink jet head other than the ink jet head having the abnormal nozzle, and the other ink jet heads select an abnormal nozzle from a plurality of ink jet heads. The inkjet head is selected from other than the inkjet head adjacent to the inkjet head in the main scanning direction. The ink dot to be formed by the abnormal nozzle is, for example, an ink dot that should be originally formed by the nozzle if the ejection characteristic of the nozzle that has become an abnormal nozzle is not abnormal.

With this configuration, for example, even when an abnormality occurs in the ejection characteristics of any nozzle of an inkjet head, the influence of the ejection abnormality can be suppressed and printing can be performed appropriately. Further, for example, even when an abnormal nozzle is generated in two or more inkjet heads, it is possible to appropriately suppress the influence of the ejection abnormality. Thereby, for example, it is possible to provide a high-performance printing apparatus that is highly resistant to failure or the like.

(Configuration 10) The printing apparatus performs printing using a plurality of colors of ink, and includes a plurality of inkjet heads arranged side by side in the main scanning direction for each of the plurality of colors. If comprised in this way, color printing can be performed appropriately, for example by printing using the ink of several colors. In addition, the ejection characteristics of the nozzles can be appropriately averaged for a plurality of inkjet heads of each color.

(Configuration 11) A printing method for performing printing by an inkjet method, which is a plurality of inkjet heads that respectively eject ink droplets of the same color ink, and a plurality of inkjets arranged side by side in a preset main scanning direction A plurality of ink jet heads that perform a main scanning operation of ejecting ink droplets while moving in the main scanning direction using the head and a plurality of ink jets relative to the medium in the sub scanning direction orthogonal to the main scanning direction The position at which the main scanning operation is performed on the medium is changed by moving the head, and a plurality of ink jet heads are arranged in a row of ink dots formed by ink droplets landing on the medium by the main scanning operation. Forming a dot row in which the ink dots are aligned in the main scanning direction with the positions in the sub-scanning direction aligned, and So as to form a dot of ink which are adjacent in the scanning direction at different ink jet head, to form a dot row. If comprised in this way, the effect similar to the structure 1 can be acquired, for example.

According to the present invention, for example, the number of passes required for printing can be appropriately reduced.

1A and 1B are diagrams illustrating an example of a configuration of a printing apparatus 10 according to an embodiment of the present invention. FIG. 1A shows an example of a configuration of a main part of the printing apparatus 10. FIG. 1B shows an example of a detailed configuration of the inkjet head 12 in the printing apparatus 10. 2A and 2B are diagrams illustrating an example of a specific configuration of the ink supply path 20. FIG. 2A shows an example of the configuration of the ink supply path 20. FIG. 2B shows an example of the state of the ink supply path 20 during the main scanning operation. 3A, FIG. 3B, and FIG. 3C are diagrams illustrating an example of a more specific configuration and operation of the flow path blocking unit 306. FIG. FIG. 3A is a cross-sectional view of the flow path blocking unit 306 in a state where the acceleration of the inkjet head 12 in the main scanning direction is zero. 3B and 3C are cross-sectional views of the flow path blocking unit 306 when the inkjet head 12 is accelerated or decelerated. 4A and 4B are diagrams for explaining an example of the main scanning operation performed by the plurality of inkjet heads 12. FIG. 4A shows an example of the configuration of the plurality of inkjet heads 12-1, 12-2, 12-3, and 12-4. FIG. 4B is a diagram illustrating an example of the main scanning operation in this example. It is a figure which shows an example of the speed change of the inkjet head 12 at the time of main scanning operation | movement. 6A and 6B are diagrams for describing a modification of the configuration of the printing apparatus 10. FIG. 6A shows an example of the configuration of a plurality of inkjet heads 12 in this modification. FIG. 6B shows an example of the main scanning operation in this modification. 7A and 7B are diagrams illustrating a first example of nozzle recovery processing. FIG. 7A is a diagram illustrating an example of the position of a nozzle in which a discharge abnormality has occurred when a discharge abnormality has occurred in only one inkjet head 12 nozzle. FIG. 7B shows an example of the main scanning operation performed in this case. 8A and 8B are diagrams illustrating a second example of nozzle recovery processing. FIG. 8A is a diagram illustrating an example of the position of a nozzle in which a discharge abnormality has occurred when a discharge abnormality has occurred in the nozzles of the plurality of inkjet heads 12. FIG. 8B shows an example of the main scanning operation performed in this case. 9A and 9B are diagrams illustrating an example of a configuration when printing is performed using a plurality of colors of ink. FIG. 9A shows a first example of a configuration in which printing is performed using a plurality of colors of ink. FIG. 9B shows a second example of a configuration in which printing is performed using a plurality of colors of ink.

Embodiments according to the present invention will be described below with reference to the drawings. 1A and 1B show an example of the configuration of a printing apparatus 10 according to an embodiment of the present invention. FIG. 1A shows an example of a configuration of a main part of the printing apparatus 10. FIG. 1B shows an example of a detailed configuration of the inkjet head 12 in the printing apparatus 10. In this example, the printing apparatus 10 is an ink jet printer that performs printing by an ink jet method, and includes a plurality of ink jet heads 12 (12-1, 12-2, 12-3, 12-4), a main scanning drive unit 14, and a sub scanning unit. A scanning drive unit 16, an ink tank 18, an ink supply path 20, and a control unit 22 are provided.

In the following, for simplification of description, an example of a configuration in which printing is performed using only one color ink is shown. When printing is performed using a plurality of color inks (for example, CMYK inks), the printing apparatus 10 includes a plurality of inkjet heads for each color, for example. A more specific configuration when printing using a plurality of colors of ink will be described in more detail later. Except as described below, the printing apparatus 10 may have the same or similar configuration as a known inkjet printer. For example, in addition to the main part shown in FIG. 1A, various configurations that are the same as or similar to those of a known inkjet printer may be further provided.

The plurality of inkjet heads 12-1, 12-2, 12-3, and 12-4 are inkjet heads that respectively eject ink droplets of the same color ink, and are set in a main scanning direction set in advance (Y direction in the figure). ) Are arranged side by side. Each inkjet head 12 has a nozzle row in which a plurality of nozzles 202 are arranged in the sub-scanning direction (X direction in the drawing) orthogonal to the main scanning direction, as shown in FIG. 1B. Further, the plurality of inkjet heads 12 are arranged side by side in the main scanning direction so that the positions of the nozzles 202 in the nozzle row are aligned in the sub scanning direction.

In this example, the inkjet head is a configuration corresponding to a portion including one nozzle row in which nozzles are arranged in the sub-scanning direction, for example. Therefore, for example, when using an inkjet head or the like in which a plurality of nozzle rows are formed on one nozzle plate, the inkjet head can be regarded as a plurality of inkjet heads that are distinguished for each nozzle row. .

In addition, as the ink used in the inkjet head 12, various known inks can be used. For example, a UV ink that is cured by irradiation with ultraviolet rays, a solvent UV ink obtained by diluting a UV ink with an organic solvent, or the like can be preferably used. Moreover, solvent ink, latex ink, etc. can be used suitably. The printing apparatus 10 further includes a configuration for fixing the ink on the medium according to the type of ink to be used, for example. For example, when UV ink or solvent UV ink is used, the printing apparatus 10 further includes an ultraviolet irradiation device. In addition, when ink that needs to be dried (solvent UV ink, solvent ink, latex ink, or the like) is used, the printing apparatus 10 further includes a heater, for example.

The main scanning driving unit 14 is a driving unit that causes the plurality of inkjet heads 12 to perform a main scanning operation of ejecting ink droplets while moving in the main scanning direction. In this example, the main scanning drive unit 14 includes a guide rail 102 and a carriage 104. The guide rail 102 is a rail-like member extending in the main scanning direction, and holds the carriage 104 so as to be able to travel in the main scanning direction. The carriage 104 is a holding unit that holds a plurality of inkjet heads 12 so as to face a medium 50 to be printed. The carriage 104 moves along the guide rail 102 in accordance with an instruction from the control unit 22 to move the plurality of inkjet heads 12 in the main scanning direction. The main scanning drive unit 14 causes the plurality of inkjet heads 12 to eject ink droplets by, for example, transmitting an instruction from the control unit 22 to the plurality of inkjet heads 12. Thereby, the main scanning drive unit 14 causes the plurality of inkjet heads 12 to perform a main scanning operation. The main scanning operation performed by the plurality of inkjet heads 12 will be described in more detail later.

The sub-scanning driving unit 16 is a driving unit that causes the plurality of inkjet heads 12 to perform a sub-scanning operation for changing the position at which the main scanning operation is performed on the medium 50, and is relative to the medium 50 in the sub-scanning direction. A plurality of inkjet heads 12 are moved to Further, in this example, the sub-scanning drive unit 16 is a roller that conveys the medium 50, and causes the plurality of inkjet heads 12 to perform a sub-scanning operation by moving the medium 50 side. In a modified example of the configuration of the printing apparatus 10, for example, the plurality of inkjet heads 12 may be caused to perform a sub-scanning operation by moving the plurality of inkjet heads 12 side.

Further, the sub-scanning drive unit 16 sequentially changes the area where the next main-scanning operation is performed on the medium 50 by causing the plurality of inkjet heads 12 to perform the sub-scanning operation between the main-scanning operations, for example. Accordingly, the printing apparatus 10 repeats the main scanning operation to perform printing on each position on the medium 50. Therefore, according to this example, it is possible to appropriately perform printing on the medium 50 by the serial method in which the inkjet head 12 is scanned.

The ink tank 18 is an ink storage unit that stores ink at positions separated from the plurality of inkjet heads 12. In this example, the ink tank 18 is installed at a position higher than the plurality of inkjet heads 12 in the direction of gravity, and supplies ink to the plurality of inkjet heads 12 via the ink supply path 20. The ink supply path 20 is an ink path for supplying ink from the ink tank 18 to the plurality of inkjet heads 12. A more specific configuration of the ink supply path 20 will also be described in more detail later. The control unit 22 is a CPU of the printing apparatus 10, for example, and controls the operation of each unit of the printing apparatus 10 to cause the printing apparatus 10 to perform printing.

Subsequently, a more specific configuration of the ink supply path 20 will be described in more detail. 2A and 2B show an example of a specific configuration of the ink supply path 20. FIG. 2A shows an example of the configuration of the ink supply path 20. FIG. 2B shows an example of the state of the ink supply path 20 during the main scanning operation. In this example, the ink supply path 20 includes an annular tube 302, a tubing pump 304, a flow path blocking unit 306, and a pressure damper 308 between the ink tank 18 and the plurality of inkjet heads 12.

The annular tube 302 is an annular tube having an ink introduction portion 402 into which ink is introduced from the ink tank 18 side, and an ink discharge portion 404 that discharges ink to the plurality of inkjet heads 12 side. At least a part of the ink flow path to the inkjet head 12 is formed. The annular tube 302 is formed of a flexible material so as to be deformed according to the movement of the plurality of inkjet heads 12 during the main scanning operation. Furthermore, in this example, the annular tube 302 is formed to a length that allows the plurality of inkjet heads 12 to move over the entire printing range in the main scanning direction. Thus, for example, as shown in FIG. 2B, during the main scanning operation, the ink supply path 20 supplies ink to the inkjet head 12 at each position in the main scanning direction.

As shown in FIG. 2A, in this example, the annular tube 302 includes a tube constituting one half of the ring and a tube constituting the other half of the positions of the ink introduction part 402 and the ink discharge part 404. It has a shape connected by. Further, the tubes on one side and the other side of the ring swell in a direction away from the ink introduction unit 402 and the ink discharge unit 404 in the main scanning direction. The lengths of the tubes on one side and the other side of the ring are preferably substantially the same.

The tubing pump 304 is a pump that circulates ink in the annular tube 302, and is disposed between the ink introduction part 402 and the ink discharge part 404 in the annular tube 302, so that the ink tank together with the annular tube 302 and the like. An ink flow path from 18 to the plurality of inkjet heads 12 is formed. Further, in this example, the tubing pump 304 opens a flow path when the plurality of inkjet heads 12 move in the main scanning direction in the main scanning operation, and allows the ink to pass through the tubing pump 304 along the annular tube 302. To. Accordingly, for example, when the ink in the annular tube 302 receives an inertial force due to acceleration or deceleration of the plurality of inkjet heads 12, the ink is circulated along the annular tube 302 according to the inertial force.

The flow path blocking unit 306 is a blocking unit that blocks the ink flow path from the ink tank 18 to the plurality of inkjet heads 12 according to a predetermined condition. In this example, the flow path blocking unit 306 blocks the ink flow path when the plurality of inkjet heads 12 are accelerated and decelerated. In this case, the time of acceleration of the plurality of inkjet heads 12 is, for example, the timing at which the plurality of inkjet heads 12 accelerate in the main scanning direction in each of the forward path and the return path of the main scanning operation. The time of deceleration of the plurality of inkjet heads 12 is, for example, the timing at which the plurality of inkjet heads 12 decelerate in the main scanning direction at the end of each main scanning operation.

Further, in this example, the flow path blocking unit 306 is an acceleration damper that closes the ink flow path in accordance with the acceleration, and is mounted on the carriage 104 between the ink discharge unit 404 of the annular tube 302 and the inkjet head 12. It is arranged. As a result, during the main scanning operation, the flow path blocking unit 306 moves in the main scanning direction together with the inkjet head 12. A more specific configuration of the flow path blocking unit 306 will be described in detail later.

The pressure damper 308 is a pressure regulator that adjusts the pressure of the ink supplied from the annular tube 302 to the plurality of inkjet heads 12 to a negative pressure within a certain range, and by generating a negative pressure in the plurality of inkjet heads 12, Ink is prevented from continuously leaking from the nozzles of the inkjet head 12. The pressure damper 308 preferably generates a negative pressure of about −4 kPa to 0 kPa with respect to the atmospheric pressure, for example, in each of the plurality of inkjet heads 12 as the negative pressure.

In this example, the pressure damper 308 is disposed between the flow path blocking unit 306 and the inkjet head 12 in the ink flow path. According to this example, ink can be appropriately supplied to the inkjet head 12. In the modified example of the configuration of the ink supply path 20, the pressure damper 308 may be disposed between the ink discharge unit 404 and the flow path blocking unit 306, for example.

In addition, in order to simplify illustration, in FIG. 2A and FIG. 2B, only one inkjet head 12 is shown among the plurality of inkjet heads 12. However, in the actual configuration of the printing apparatus 10, for example, ink may be supplied to the plurality of inkjet heads 12 through one ink supply path 20. In this case, the ink supply path 20 may include, for example, a flow path blocking unit 306 and a pressure damper 308 for each inkjet head 12. As a result, the ink supply path 20 supplies ink to each of the plurality of inkjet heads 12 via the flow path blocking unit 306 and the pressure damper 308 provided individually for each inkjet head 12. Further, the ink supply path 20 may supply ink to the plurality of inkjet heads 12 via a set of flow path blocking units 306 and a pressure damper 308.

Subsequently, a more specific configuration of the flow path blocking unit 306 will be described in more detail. 3A, FIG. 3B, and FIG. 3C show an example of a more specific configuration and operation of the flow path blocking unit 306. FIG. 3A is a cross-sectional view of the flow path blocking unit 306 in a state where the acceleration of the inkjet head 12 in the main scanning direction is zero. 3B and 3C are cross-sectional views of the flow path blocking unit 306 when the inkjet head 12 is accelerated or decelerated.

In this example, the flow path blocking unit 306 includes a storage unit 412,

connection portions

416a and 416b, and a spherical body 414. The accommodating portion 412 is a hollow body that accommodates the spherical body 414 therein. In this example, the storage portion 412 has a shape in which the central portion in the direction along the ink flow path swells up and down in the direction of gravity. The accommodating portion 412 has an opening 502 through which ink flows along the ink flow path on one side and the other side of the ink flow path, and is provided at a position in the middle of the ink flow path. Thus, a part of the ink flow path is formed. More specifically, in this example, the opening 502 on one side in the ink flow path is connected to the annular tube 302 via the connection portion 416a. Further, the opening 502 on the other side is connected to the inkjet head 12 via a connection portion 416b and a pressure damper 308 (see FIGS. 2A and 2B).

The

connection portions

416a and 416b are portions that connect the flow path blocking unit 306 to the ink flow paths. In this example, the connection portion 416a is a connection portion on the annular tube 302 side in the ink flow path. The connection portion 416b is a connection portion on the ink jet head 12 side in the ink flow path.

The spherical body 414 is an example of a moving member, and can move through the hollow portion of the storage portion 412 along the ink flow path, and does not pass through the openings 502 on one side and the other side of the storage portion 412. Have With this configuration, the spherical body 414 moves along the ink flow path according to the inertial force generated in the ink flow path when the inkjet head 12 is accelerated and decelerated during the main scanning operation. In this case, the movement of the spherical body 414 according to the inertial force may be, for example, a movement according to the pressure of the ink that moves due to the inertial force. In addition, due to this movement, the spherical body 414 closes any opening of the storage portion 412 and blocks the ink flow path.

Subsequently, the operation of the flow path blocking unit 306 will be described in more detail. As described above, the accommodating portion 412 of this example has a shape in which the central portion swells up and down in the direction of gravity. Therefore, in a state where the inertial force is not received, the spherical body 414 is positioned at the center of the accommodating portion 412 as shown in FIG. 3A due to its own weight. As a result, the flow path blocking unit 306 does not block the ink flow path.

Here, the state in which the spherical body 414 does not receive the inertial force is a state in which the acceleration of the inkjet head 12 is zero, and more specifically, for example, when the inkjet head 12 is stationary, or This is the case when the head 12 is moving at a constant speed. Therefore, according to this example, for example, when the inkjet head 12 is stationary or while the inkjet head 12 is moving at a constant speed in the main scanning operation, the flow path blocking unit 306 opens the ink flow path. Let

On the other hand, when the inkjet head 12 is accelerated and decelerated, the spherical body 414 moves in accordance with the inertial force and closes one of the openings 502 as shown in FIGS. 3B and 3C. Accordingly, the flow path blocking unit 306 blocks the ink flow path during acceleration and deceleration in the main scanning operation.

For example, FIG. 3B shows a cross-sectional view of the flow path blocking unit 306 in a state where the spherical body 414 receives the inertial force in the direction of the arrow 504. This state is, for example, a state where the inkjet head 12 is decelerated while moving in the direction of the arrow 504, or a state where the inkjet head 12 is accelerating while moving in the direction opposite to the arrow 504. In these cases, the spherical body 414 moves to the left in the figure in accordance with the inertial force, and closes the opening 502 on one side. Accordingly, the flow path blocking unit 306 blocks the ink flow path.

FIG. 3B shows a cross-sectional view of the flow path blocking unit 306 in a state where the spherical body 414 receives the inertial force in the direction of the arrow 506. This state is, for example, a state where the inkjet head 12 is decelerating while moving in the direction of the arrow 506, or a state where the inkjet head 12 is accelerating while moving in the direction opposite to the arrow 506. In these cases, the spherical body 414 moves to the right side in the figure according to the inertial force, and closes the opening 502 on the other side. Accordingly, the flow path blocking unit 306 blocks the ink flow path.

Therefore, according to the present example, for example, the ink flow path can be appropriately blocked at each of acceleration and deceleration of the inkjet head 12 in the main scanning operation. Thereby, for example, fluctuations in pressure applied to the inkjet head 12 from the ink supply path 20 (see FIGS. 2A and 2B) can be appropriately suppressed.

It should be noted that blocking the ink flow path during acceleration and deceleration refers to, for example, the absolute value of acceleration during acceleration and deceleration from a predetermined value depending on the sensitivity determined according to the shape of the flow path blocking section 306 and the like. May also be to block the flow path. Moreover, about the sensitivity of interruption | blocking, it can change suitably by changing the shape of the accommodating part 412 etc., for example.

Here, in the ink jet printer, when the ink jet head 12 is accelerated or decelerated, the ink in the ink jet head 12 and the ink contained in the portion that moves together with the ink jet head 12 in the ink supply path 20 are affected by the acceleration. . For this reason, when a configuration that appropriately suppresses pressure fluctuations is not used, the ink moves, and pressure fluctuations may occur in the inkjet head 12, the ink supply path 20, or the like. As a result, there may be a problem in the state of the inkjet head 12.

More specifically, for example, when the ink supply path 20 is not configured so as to suppress pressure fluctuation, if the acceleration is large when the inkjet head 12 is accelerated, air is drawn from the nozzle, so-called “missing out”. Problems may arise. In addition, when the inkjet head 12 is decelerated, if the acceleration (absolute value of acceleration) is large, the ink may spill out from the nozzles, which may cause a problem of so-called dropping.

On the other hand, according to this example, for example, by blocking the ink flow path by the flow path blocking unit 306 at the time of acceleration and deceleration of the inkjet head 12, problems caused by pressure fluctuations can be appropriately suppressed. Can do. This also makes it possible to increase the absolute value of acceleration during acceleration and deceleration, for example, and to accelerate and decelerate in a shorter time. Therefore, according to this example, for example, the loss time required for acceleration and deceleration of the inkjet head during the main scanning operation can be appropriately reduced.

In this example, the ink supply path 20 further includes an annular tube 302 in addition to the flow path blocking section 306 as a configuration for suppressing pressure fluctuation due to inertial force during acceleration and deceleration. When the annular tube 302 is used, for example, when the ink jet head 12 is accelerated and decelerated, even if the ink in the ink supply path moves due to the acceleration, the ink circulates in the annular tube 302. Is unlikely to occur. Therefore, according to the present example, for example, when the inkjet head 12 is accelerated and decelerated, fluctuations in pressure applied from the ink supply path 20 to the inkjet head 12 can be more appropriately suppressed. In addition, for example, it is possible to more appropriately prevent problems such as missing and dropping.

In the modified example of the configuration of the ink supply path 20, for example, only one of the annular tube 302 and the flow path blocking unit 306 may be used. Even in such a configuration, it is possible to appropriately suppress the fluctuation of the pressure applied from the ink supply path 20 to the inkjet head 12.

Subsequently, the main scanning operation performed by the plurality of inkjet heads 12 will be described in more detail. 4A and 4B are diagrams for explaining an example of the main scanning operation performed by the plurality of inkjet heads 12. In the following description, a case where four inkjet heads 12-1, 12-2, 12-3, and 12-4 are used as the plurality of inkjet heads 12 will be described. Further, for simplification of explanation, the number of nozzles arranged in each nozzle row of the inkjet heads 12-1, 12-2, 12-3, 12-4 is assumed to be eight.

FIG. 4A shows an example of the configuration of a plurality of inkjet heads 12-1, 12-2, 12-3, and 12-4. In the figure, numerals i-1, i-2, i-3, i-4, i-5, drawn in the inkjet head 12-i (i is any one of 1, 2, 3, 4), i-6, i-7, and i-8 indicate the 1st to 8th nozzles in the nozzle row of the inkjet head 12-i.

As described with reference to FIGS. 1A, 1B, etc., in this example, the plurality of inkjet heads 12-1, 12-2, 12-3, 12-4 are sub-scanned in the nozzle row in the nozzle row. The positions are aligned so as to be aligned in the direction, and are arranged in the main scanning direction. Therefore, as shown in the figure, the first nozzles 1-1, 2-1, 3-1, 4-1 in each of the inkjet heads 12-1, 12-2, 12-3, 12-4 are The positions in the sub-scanning direction are aligned and aligned in the main scanning direction. Similarly, the j-th nozzle 1 (j is any one of 2, 3, 4, 5, 6, 7, 8) in each of the inkjet heads 12-1, 12-2, 12-3, 12-4. j, 2-j, 3-j, and 4-j are aligned in the main scanning direction with their positions in the sub-scanning direction aligned.

FIG. 4B is a diagram showing an example of the main scanning operation in this example, and relates to an example of an arrangement of ink dots formed on the medium by the inkjet heads 12-1, 12-2, 12-3, and 12-4. For each position on the medium, a nozzle that forms an ink dot at that position is shown. For convenience of illustration, in FIG. 4B, when only one main scanning operation is performed on each area on the medium (when printing is performed in one pass), the sub-scanning operation is sandwiched 2 The nozzles for forming ink dots at each position are shown for the number of main scanning operations.

In this example, the plurality of inkjet heads 12-1, 12-2, 12-3, 12-4 are arranged in a row of dots in which ink dots are aligned in the main scanning direction with the positions in the sub scanning direction aligned by the main scanning operation. Form. A dot row is a row in which ink dots are formed by ink droplets landing on a medium. Further, as can be seen from the figure, the ink dots constituting the dot row formed by each main scanning operation are formed by a plurality of inkjet heads 12-1, 12-2, 12-3, 12-4. . Accordingly, a dot row in which ink dots are arranged in the main scanning direction is formed by a plurality of nozzles of the same color.

Furthermore, in this example, the plurality of inkjet heads 12-1, 12-2, 12-3, 12-4 form dot rows so that adjacent ink dots are formed by different inkjet heads in the main scanning direction. To do. With this configuration, for example, by forming adjacent ink dots in the main scanning direction with different nozzles, it is possible to appropriately prevent adjacent ink dots formed in the same nozzle in the main scanning direction. be able to. Therefore, according to this example, for example, regarding the ejection characteristics of the nozzles, it is not possible to use the multi-pass method. In addition, a method (pseudo multi-pass scanning) that obtains the same effect as the multi-pass method can be realized.
Thereby, for example, occurrence of banding can be appropriately suppressed. In addition, it is preferable that the ink dots formed by the same nozzle are not adjacent not only in the main scanning direction but also in the sub-scanning direction and the oblique direction. If comprised in this way, the discharge characteristic of a nozzle can be averaged more appropriately, for example.

In this example, it is not necessary to perform printing with a plurality of passes for the purpose of averaging the ejection characteristics of the nozzles. The number of passes can be appropriately reduced. Thereby, the loss time required for acceleration and deceleration of the inkjet head during the main scanning operation can be shortened. Therefore, according to this example, the printing speed can be appropriately improved.

Further, for example, when the nozzle discharge characteristics are averaged by the multi-pass method, it is necessary to perform a sub-scanning operation between a plurality of main scanning operations performed on the same region. However, in this case, the position of the ink dot formed in each main scanning operation may be shifted due to an error in the amount of movement during the sub-scanning operation. On the other hand, according to this example, such a shift does not occur. Therefore, according to this example, for example, high-precision printing can be performed more appropriately.

In addition, as described above, the multi-pass printing is performed for the purpose of increasing the resolution in addition to averaging the discharge characteristics of the nozzles. Therefore, in the printing apparatus 10 of this example, printing in the multipass method may be performed for the purpose of increasing the resolution. In this case as well, since the ejection characteristics of the nozzles can be averaged by the pseudo multi-pass method, the necessary number of passes can be appropriately reduced. For example, when printing is performed at a resolution with a dot density corresponding to half the nozzle pitch in the inkjet head, the number of printing passes can be reduced to two.

More specifically, for example, when printing using UV ink, in a conventional inkjet printer, the number of printing passes is usually set to 8 or more in order to perform printing with sufficient quality. is required. On the other hand, according to this example, for example, even when printing is performed at a dot density resolution corresponding to a half of the nozzle pitch in the inkjet head, printing can be appropriately performed with two passes. it can.

In addition, as described with reference to FIGS. 2A and 2B, FIGS. 3A, 3B, and 3C, in this example, the ink supply path for supplying ink to the inkjet head 12 is an annular tube 302 (see FIGS. 2A and 2C). 2B) and the flow path blocking unit 306 (see FIGS. 2A and 2B), the pressure applied to the inkjet head 12 from the ink supply path during acceleration and deceleration of the inkjet head in the main scanning direction. It is configured to suppress fluctuations. Therefore, in each main scanning operation, useless time during acceleration and deceleration can be shortened, and the moving speed of the inkjet head 12 during the main scanning operation can be increased.

Therefore, next, the moving speed of the inkjet head 12 during the main scanning operation will be described in detail. FIG. 5 shows an example of a change in speed of the inkjet head 12 during the main scanning operation.

In an ink jet printer, ink droplets are usually ejected by supplying a drive signal having a predetermined waveform to each nozzle. Each nozzle ejects ink droplets by vibrating the ink meniscus in accordance with the drive signal. Therefore, when ink droplets are continuously ejected from one nozzle during the main scanning operation, it is necessary to match the ejection cycle with the cycle for appropriately vibrating the meniscus. As a result, the moving speed of the ink-jet head during the main scanning operation needs to be determined according to the printing resolution and the cycle for appropriately vibrating the meniscus (hereinafter referred to as the drive signal cycle). Become.

More specifically, for example, in an inkjet printer having a configuration different from that of the printing apparatus 10 in this example, the main scanning operation is performed using only one inkjet head, and each of the components on the medium is used without using the multi-pass method. When only one main scanning operation is performed on a region, all the dots in the dot row in which ink dots are arranged in the main scanning direction are formed by one main scanning operation using one nozzle. Therefore, in this case, it is necessary for the nozzles of the inkjet head to eject ink droplets to respective positions arranged at dot intervals according to the printing resolution while moving in the main scanning direction. Accordingly, in this case, it is necessary to slow down the moving speed of the ink jet head so that the time during which the ink jet head moves at least as much as between adjacent dots is longer than the cycle of the drive signal.

In FIG. 5, the waveform shown by the broken line shows an example of the moving speed of the inkjet head in such a case. In this case, the inkjet head performs the main scanning operation while moving at a constant speed v1. The time required to accelerate from the stop state to the speed v1 is t1. Further, the time required to decelerate from the speed v1 to the stop state is also t1.

On the other hand, when a plurality of inkjet heads 12 are used as in this example, the moving speed during the main scanning operation can be increased. For example, as described with reference to FIGS. 1A and 1B, FIGS. 2A and 2B, FIGS. 3A, 3B and 3C, FIGS. 4A and 4B, four inkjet heads 12-1, 12-2, 12 When -3 and 12-4 are used, the dots in the dot row in which the ink dots are arranged in the main scanning direction are formed by being shared by the four nozzles. In this case, with one nozzle of one inkjet head, ink dots may be formed at a rate of one dot for every four dots in the dot row. That is, in this case, it can be said that the interval in the main scanning direction of the ink dots formed by one nozzle can be four times that when only one ink jet head is used. Therefore, when four inkjet heads 12-1, 12-2, 12-3, and 12-4 are used, for example, regarding the moving speed of the inkjet head, the time for which the inkjet head moves by 4 dots is longer than the cycle of the drive signal. May be set to be longer.

In FIG. 5, the waveform indicated by the solid line shows an example of the moving speed of each inkjet head when four inkjet heads 12-1, 12-2, 12-3, and 12-4 are used. In this case, each of the inkjet heads 12-1, 12-2, 12-3, and 12-4 performs the main scanning operation while moving at a speed v2 = 4v1 that is four times that shown by the broken line. Therefore, according to this example, for example, the moving speed of the inkjet head 12 during the main scanning operation can be appropriately increased.

Here, as described above, according to this example, the moving speed of the inkjet head 12 during the main scanning operation can be appropriately increased. However, even if the moving speed of the inkjet head 12 during the main scanning operation is increased, the loss time required for acceleration and deceleration also increases if the acceleration during acceleration / deceleration does not change. As a result, the printing speed may not be sufficiently increased.

For example, in the configuration of this example, when the acceleration at the time of acceleration / deceleration is the same as when only one inkjet head is used, the time required for acceleration / deceleration is one as indicated by a dashed line in the figure. T2 = 4t1, which is four times that when only the inkjet head is used. Therefore, in this case, the influence of the loss time on the printing speed is increased, and there is a possibility that the printing speed cannot be sufficiently increased.

On the other hand, in this example, the pressure applied to the inkjet head 12 from the ink supply path by using the ink supply path having the configuration described with reference to FIGS. 2A and 2B, FIGS. 3A, 3B, and 3C. Fluctuations can be suppressed. This also makes it possible to increase the absolute value of acceleration during acceleration / deceleration and shorten the time required for acceleration / deceleration. For example, in the configuration of this example, more specifically, the time required for acceleration / deceleration can be suppressed to the same level as the time t1 when only one ink jet head is used. Therefore, according to this example, even when the moving speed of the inkjet head 12 during the main scanning operation is increased, an increase in time required for acceleration / deceleration can be appropriately suppressed. In addition, this makes it possible to suppress the influence of the loss time and increase the printing speed more appropriately.

Note that, as described with reference to FIGS. 1A and 1B, in this example, ink is supplied to the inkjet head 12 using an ink tank provided at a position separated from the inkjet head 12. Such a configuration is often used in, for example, a large ink jet printer. In a large inkjet printer, it is desired to increase the moving speed of the inkjet head during the main scanning operation in order to perform printing on a large medium.

However, for example, in the case of the configuration of a conventional inkjet printer, if the moving speed of the inkjet head during the main scanning operation is increased, the time required for acceleration and deceleration increases. In particular, for example, when the number of printing passes is large, the loss time increases according to the number of passes, and the influence on the printing speed is increased.

On the other hand, according to this example, even when the moving speed of the inkjet head is increased, the loss time can be appropriately reduced. Also, the number of printing passes can be appropriately reduced. Therefore, according to this example, for example, even in a large-scale ink jet printer, the moving speed of the ink jet head during the main scanning operation can be appropriately increased, and high-speed printing can be more appropriately realized.

Subsequently, a modified example of the configuration of the printing apparatus 10 will be described. 6A and 6B are diagrams for describing a modification of the configuration of the printing apparatus 10 and show an example of the configuration and operation in the case where a larger number of inkjet heads 12 are used. Except as described below, the configuration and operation of this modification are as shown in FIGS. 1A and 1B, FIGS. 2A and 2B, FIGS. 3A, 3B and 3C, FIGS. 4A and 4B, and FIGS. This is the same as or similar to the printing apparatus 10 described with reference to FIG.

FIG. 6A shows an example of the configuration of a plurality of inkjet heads 12 (12-1, 12-2, 12-3, 12-4, 12-5) in this modification. FIG. 6B shows an example of the main scanning operation in this modification.

In this modification, in each main scanning operation, a pseudo multi-pass that obtains the same effect as the multi-pass method with the number of passes of (N−1) or less by N (N is an integer of 3 or more) inkjet heads. This is an example of a configuration that performs scanning, and includes N inkjet heads as a plurality of inkjet heads that respectively eject ink droplets of the same color ink. In each main scanning operation, as an inkjet head to form k dots (k is an integer of 2 or more and N−1 or less) that are continuously arranged in the main scanning direction, Select k inkjet heads. In addition, the ink jet head to be selected is changed every time k k dots of the ink arranged in the main scanning direction are formed.

More specifically, in this modification, the printing apparatus 10 includes five inkjet heads 12-1, 12-2, 12-3, 12-4, and 12-5, as shown in FIG. 6A. In each main scanning operation, among the five inkjet heads 12-1, 12-2, 12-3, 12-4, and 12-5, the inkjet heads that form four consecutive dots are used. Select four. Further, every time four dots arranged in the main scanning direction are formed, the four inkjet heads 12 to be selected are changed.

As a result, in the present modification, four prints in a pseudo multi-pass method are performed by one printing pass by the five inkjet heads 12-1, 12-2, 12-3, 12-4, and 12-5. The same printing as for the pass is performed. According to this modification, for example, by using more inkjet heads 12, it is possible to more appropriately average the ejection characteristics of the nozzles in each main scanning operation. Thereby, the image quality of the printed image can be improved more appropriately.

Further, in the operation of this modification, as described above, the inkjet heads 12 to be used are sequentially changed during the main scanning operation. Thereby, for example, nozzles that eject ink droplets can be uniformly distributed. Further, it is possible to make it difficult for nozzle clogging and the like to occur due to suspension of discharge.

Furthermore, in this modification, printing is performed by selecting a smaller number of inkjet heads than the total number at each timing of the main scanning operation. For example, an abnormality occurs in the ejection characteristics of any nozzle of the inkjet head 12. In some cases, for example, printing can be continued by performing printing only with the inkjet head 12 other than the inkjet head 12 having the nozzle. Therefore, according to this modification, for example, it is possible to provide a high-performance printing apparatus that is highly resistant to failures and the like.

For example, even when the inkjet head 12 having a failed nozzle is not used, the number of inkjet heads 12 used at each timing of the main scanning operation does not change. Therefore, it is not necessary to reduce the moving speed of the inkjet head 12 during the main scanning operation. Accordingly, according to the present modification, for example, nozzle recovery processing that avoids the use of a failed nozzle can be appropriately performed without reducing the printing speed.

For the nozzle recovery process, various methods are possible depending on, for example, the position of the nozzle where the ejection abnormality has occurred. Therefore, an example of nozzle recovery processing will be described below.

FIGS. 7A and 7B are diagrams for explaining a first example of the nozzle recovery process, and shows an example of the nozzle recovery process when an ejection abnormality occurs in the nozzle of only one inkjet head 12. FIG. 7A is a diagram illustrating an example of the position of the nozzle in which the ejection abnormality has occurred in the case where ejection abnormality has occurred in the nozzle of only one inkjet head 12, and the first and fifth positions in the nozzle row of the inkjet head 12-2. This shows a state in which a discharge abnormality has occurred in the second nozzle (2-1, 2-5). FIG. 7B shows an example of the main scanning operation performed in this case.

As shown in FIG. 7A, when a discharge abnormality occurs in the nozzle of only one inkjet head 12-2, the printing apparatus 10 causes the other inkjet heads 12-1, 12-3, 12-4, 12-5 to be used. Is used to perform the main scanning operation. With this configuration, for example, even when an abnormality occurs in the ejection characteristics of the nozzles of any of the inkjet heads 12, the inkjet head 12 having the nozzles where the ejection characteristics are abnormal can be used appropriately without using them. Can be printed. As a result, it is possible to avoid the use of abnormally discharged nozzles and appropriately perform nozzle recovery processing. In addition, by appropriately performing the nozzle recovery process, for example, it is possible to appropriately provide a high-performance printing apparatus 10 that is highly resistant to failure or the like.

Here, more generally, when it is assumed that the number of inkjet heads 12 included in the printing apparatus 10 is N, for example, in any nozzle of any inkjet head 12, When an abnormality occurs in the ejection characteristics of the ink droplets, (N−1) or less inkjet heads 12 that do not include the inkjet heads 12 having the nozzles in which the ejection characteristics are abnormal among the N inkjet heads 12 It can be said that this is a process of forming a dot row. With this configuration, for example, it is possible to appropriately perform nozzle recovery processing while avoiding the use of abnormally discharged nozzles.

The nozzle recovery process can also be performed when, for example, a discharge abnormality has occurred in the nozzles of the plurality of inkjet heads 12. Therefore, hereinafter, the nozzle recovery process will be described as a second example of the nozzle recovery process.

FIGS. 8A and 8B are diagrams for explaining a second example of the nozzle recovery process, and shows an example of the nozzle recovery process when ejection abnormality occurs in the nozzles of the plurality of inkjet heads 12. FIG. 8A is a diagram illustrating an example of the position of the nozzle where the ejection abnormality has occurred when ejection abnormality occurs in the nozzles of the plurality of inkjet heads 12, and the first and sixth positions in the nozzle row of the inkjet head 12-1. Nozzles (1-1, 1-6), the third nozzle (2-3) in the nozzle row of the inkjet head 12-2, and the sixth nozzle (3-6 in the nozzle row of the inkjet head 12-3) ) And the eighth nozzle (4-8) in the nozzle row of the ink jet head 12-4. FIG. 8B shows an example of the main scanning operation performed in this case.

As shown in FIG. 8A, when an abnormality occurs in the ejection characteristics of ink droplets in any of the nozzles in any of the inkjet heads 12, as shown in FIG. The nozzles of the inkjet head 12 other than the inkjet head 12 having the abnormal nozzle are formed. The other inkjet heads 12 are selected from a plurality of inkjet heads 12 other than the inkjet heads 12 adjacent to the inkjet head 12 having abnormal nozzles in the main scanning direction.

The abnormal nozzle is, for example, a nozzle in which an abnormality has occurred in the ejection characteristics. Further, the ink dots to be formed by the abnormal nozzle are, for example, ink dots that should be originally formed by the nozzle when the ejection characteristics of the nozzle that has become the abnormal nozzle are not abnormal. The nozzles of the other inkjet heads 12 are selected from, for example, nozzles that have the same positions in the sub-scanning direction as the corresponding abnormal nozzles.

More specifically, for example, in the case shown in FIG. 8B, the ink dots to be formed by the nozzle 1-1, which is an abnormal nozzle in the inkjet head 12-1, are replaced with the normal nozzles 4 in the other inkjet heads 12-4. -1. In addition, ink dots to be formed by other abnormal nozzles are also formed by normal nozzles in the other inkjet heads 12, respectively.

Here, in FIG. 8B, among the dots of the ink to be formed by the abnormal nozzles, the codes (1-1, etc.) indicating the corresponding abnormal nozzles are erased by strike-through lines for the positions of some of the dots. Is shown. Further, the reference numeral (4-1) or the like indicating a nozzle to be used instead is also written for the position. However, for convenience of illustration, only the corresponding abnormal nozzle codes are shown for the positions of the dots except for some of the ink dots to be formed by the abnormal nozzles.

With this configuration, for example, even when an abnormality occurs in the discharge characteristics of any nozzle, the influence of the discharge abnormality can be suppressed and printing can be performed appropriately. Further, for example, even when abnormal nozzles are generated in two or more ink jet heads 12, the influence of ejection abnormality can be appropriately suppressed. Thereby, for example, it is possible to provide a high-performance printing apparatus that is highly resistant to failure or the like.

Subsequently, regarding a modified example of the configuration of the printing apparatus 10, a more specific configuration in the case where printing is performed using a plurality of colors of ink will be described. Except as described below, the configuration and operation in this modification are as shown in FIGS. 1A and 1B, FIGS. 2A and 2B, FIGS. 3A, 3B and 3C, FIGS. 4A and 4B, and FIGS. This is the same as or similar to the printing apparatus 10 described with reference to FIGS. 6A and 6B, FIGS. 7A and 7B, FIGS. 8A and 8B.

FIG. 9A and FIG. 9B show examples of configurations when printing is performed using a plurality of colors of ink. FIG. 9A shows a first example of a configuration in which printing is performed using a plurality of colors of ink. FIG. 9B shows a second example of a configuration in which printing is performed using a plurality of colors of ink.

When printing using a plurality of colors of ink, the printing apparatus 10 includes a plurality of inkjet heads 12 arranged in the main scanning direction for each of the plurality of colors. For example, in the configuration shown in FIGS. 9A and 9B, the printing apparatus 10 includes a plurality of Y (yellow) color inkjet heads 12y, a plurality of M (magenta) color inkjet heads 12m, and C (cyan). A plurality of inkjet heads 12c for color and a plurality of inkjet heads 12k for K (black) color are provided.

Further, in the configuration shown in FIG. 9A, the ink jet heads 12 of these colors are arranged side by side in the main scanning direction. In the configuration shown in FIG. 9B, the inkjet heads 12 of these colors are arranged side by side in the sub-scanning direction. As shown in FIG. 9B, when the inkjet heads 12 of the respective colors are arranged side by side in the sub-scanning direction, the position in the main scanning direction may also be shifted for each color.

With such a configuration, for example, color printing can be performed appropriately by performing printing using inks of a plurality of colors. Further, the discharge characteristics of the nozzles can be appropriately averaged for the plurality of inkjet heads 12 of each color in the same manner as the printing apparatus 10 described with reference to FIGS. 1A and 1B and the like. Therefore, also in this modification, for example, the number of passes required for printing can be appropriately reduced. In addition, regarding the other points, the same effects as those of the printing apparatus 10 described with reference to FIGS. 1A and 1B and the like can be obtained for printing with ink of each color.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

The present invention can be suitably used for a printing apparatus, for example.

DESCRIPTION OF SYMBOLS 10 ... Printing apparatus, 12 ... Inkjet head, 14 ... Main scanning drive part, 16 ... Sub-scanning drive part, 18 ... Ink tank, 20 ... Ink supply path, 22 ...・ Control unit 50 ... medium 102 ... guide rail 104 ... carriage 202 ... nozzle 302 ... annular tube 304 ... tubing pump 306 ... flow path blocking 308 ... Pressure damper 402 ... Ink introduction part 404 ... Ink discharge part 412 ... Storage part 414 ... Spherical body 416 ... Connection part 502 ... Opening, 504 ... arrow, 506 ... arrow

Claims

A printing apparatus that performs printing by an inkjet method,
A plurality of inkjet heads that respectively eject ink droplets of the same color ink, and a plurality of inkjet heads arranged side by side in a preset main scanning direction;
A main scanning drive unit that causes the plurality of inkjet heads to perform a main scanning operation of ejecting ink droplets while moving in the main scanning direction;
A sub-scanning drive unit that changes a position at which the main scanning operation is performed on the medium by moving the plurality of inkjet heads relative to the medium in a sub-scanning direction orthogonal to the main scanning direction; Prepared,
The plurality of inkjet heads are
A line of ink dots formed by ink droplets landing on a medium by the main scanning operation, and a line of dots in which the ink dots are aligned in the main scanning direction with the positions in the sub-scanning direction being aligned. Forming,
In addition, the dot row is formed so that the ink dots adjacent to each other in the main scanning direction are formed by different ink jet heads.
An ink tank for storing ink at positions separated from the plurality of inkjet heads;
The printing apparatus according to claim 1, further comprising an ink supply path that supplies ink from the ink tank to the plurality of inkjet heads.
The ink supply path is a pressure applied to the inkjet head from the ink supply path during acceleration when the inkjet head accelerates in the main scanning direction and during deceleration when the inkjet head decelerates in the main scanning direction. The printing apparatus according to claim 2, wherein the printing apparatus is configured to suppress fluctuations of the printing apparatus.
The ink supply path includes an annular tube that deforms according to the movement of the inkjet head during the main scanning operation,
The annular tube forms at least a part of an ink flow path from the ink tank to the ink jet head, and an ink introducing portion into which ink is introduced from the ink tank side, and ink to the ink jet head side. 4. The printing apparatus according to claim 2, further comprising an ink discharge unit that discharges the ink, and is formed to have a length that allows the inkjet head to move over the entire printing range in the main scanning direction.
The ink supply path includes a flow path blocking unit that blocks a flow path of ink from the ink tank to the inkjet head,
The flow path blocking unit blocks the flow path during acceleration when the inkjet head accelerates in the main scanning direction and during deceleration when the inkjet head decelerates in the main scanning direction. The printing apparatus according to claim 2 or 3.
During the main scanning operation, the flow path blocking unit moves in the main scanning direction together with the inkjet head,
And the flow path blocking part is
A moving member that moves along the ink flow path in accordance with an inertial force generated in the ink flow path at each of the acceleration time and the deceleration time;
A hollow body that accommodates the moving member therein, and a housing portion that forms a part of the ink flow path by being provided at a position in the middle of the ink flow path,
The container has an opening for flowing ink along the ink flow path on one side and the other side of the ink flow path,
The moving member is capable of moving in the hollow portion of the containing portion along the ink flow path and has a size that does not pass through the openings on one side and the other side of the ink flow path. 6. The printing apparatus according to claim 5, wherein the ink flow path is blocked by closing any of the openings of the housing portion at each of the acceleration time and the deceleration time.
As the plurality of inkjet heads that respectively eject ink droplets of the same color ink, N (N is an integer of 3 or more) inkjet heads are provided,
In each of the main scanning operations, k inkjet heads (k is an integer of 2 or more and N-1 or less) that are continuously arranged in the main scanning direction, The selected inkjet head is changed every time the k ink-jet heads are selected and the k dots of the ink arranged continuously in the main scanning direction are formed. The printing apparatus according to any one of 1 to 3.
As the plurality of inkjet heads that respectively eject ink droplets of the same color ink, N (N is an integer of 3 or more) inkjet heads are provided,
Each of the inkjet heads has a nozzle for ejecting ink droplets,
If any of the nozzles in any of the inkjet heads has an abnormality in the ejection characteristics of the ink droplets, an abnormality in the ejection characteristics has occurred in the N inkjet heads in each main scanning operation. 4. The printing apparatus according to claim 1, wherein the dot row is formed by the (N−1) or less inkjet heads not including the inkjet head having a nozzle. 5.
Each of the inkjet heads has a nozzle for ejecting ink droplets,
If any of the nozzles in any of the inkjet heads has an abnormality in the ejection characteristics of the ink droplet, the ink dots to be formed by the abnormal nozzle, which is the nozzle in which the ejection characteristics are abnormal, Formed by the nozzle of the inkjet head other than the inkjet head having a nozzle,
The said other inkjet head is chosen from other than the said inkjet head which adjoins the said inkjet head which has the said abnormal nozzle in the said main scanning direction among these inkjet heads. A printing apparatus according to claim 1.
The printing apparatus performs printing using a plurality of colors of ink,
The printing apparatus according to claim 1, further comprising: the plurality of inkjet heads arranged side by side in the main scanning direction for each of the plurality of colors.
A printing method for performing printing by an inkjet method,
A plurality of inkjet heads that respectively eject ink droplets of the same color ink, using a plurality of inkjet heads arranged side by side in a preset main scanning direction,
Causing the plurality of inkjet heads to perform a main scanning operation of ejecting ink droplets while moving in the main scanning direction;
And,
Changing the position at which the main scanning operation is performed on the medium by moving the plurality of inkjet heads relative to the medium in a sub-scanning direction orthogonal to the main scanning direction;
The plurality of inkjet heads are
A line of ink dots formed by ink droplets landing on a medium by the main scanning operation, and a line of dots in which the ink dots are aligned in the main scanning direction with the positions in the sub-scanning direction being aligned. Forming,
In addition, the dot row is formed so that the ink dots adjacent in the main scanning direction are formed by different ink jet heads.