JP2005103843A - Inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus which can reduce a displacement of an ink arrival position. <P>SOLUTION: This inkjet printer 1 is equipped with: serial recording heads 7-10 for ejecting ink toward a recording medium K from a plurality of ejection ports 13...; a control device 15 for controlling the control heads 7-10; a carrier device 18 for carrying the recording medium K in a carrying direction A; a carriage 6 for moving the recording heads 7-10 relatively to the recording medium K along a scanning direction B; and a moving-movement speed detector 14 for detecting a scanning-movement speed of the carriage 6. The control device 15 changes the ejection timing of at least some of the plurality of ejection ports 13... in accordance with the scanning-movement speeds and scanning-movement directions of the recording heads 7-10. In the control device 15, the higher the scanning-movement speed is, the greater the variation of the ejection timing is made with respect to the variation of the scanning-movement speed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus that forms an image on the surface of a recording medium by ejecting ink.

  2. Description of the Related Art Conventionally, a recording head of an ink jet recording apparatus that records an image on the surface of a recording medium by discharging ink is provided with a plurality of discharge ports for the purpose of speeding up recording or recording in color. The ink jet recording apparatus performs recording by controlling these discharge ports.

Incidentally, if there is a manufacturing error in the direction of the ejection port, the ink ejected from each ejection port is shown in FIGS. 4A and 4B even when the recording head and the recording medium are not moved relative to each other. As described above, landing is made at a position shifted by the angle shift amount δθ along the image recording direction. In the case where the recording head and the recording medium are moved relative to each other, the landing position deviation amount δ is changed when at least one of the scanning speed and the scanning direction of the recording head changes in the serial type ink jet recording apparatus. In the ink jet recording apparatus of the type, when at least one of the conveyance speed and the conveyance direction of the recording medium changes, the velocity deviation amount δ _v changes along the image recording direction. Furthermore, in a photo-curable ink jet recording apparatus, since ink is not absorbed by the recording medium, if the landing position is deviated, dots are attracted and combined by intermolecular force before the ink is cured. May also deteriorate.

In recent years, as a method for solving such a problem, a method of correcting variation in the ejection amount for each ejection port by changing the pulse width of the voltage applied to each ejection port (for example, see Patent Document 1), There is a method for detecting the unevenness of the recording medium and controlling the position of the recording head (for example, see Patent Document 2).
Japanese Patent No. 2961855 JP 2001-310454 A

However, although the method disclosed in Patent Document 1 can reduce the density unevenness, it cannot reduce the deviation of the ink landing position.
Further, in the method disclosed in Patent Document 2, even if it is possible to correct the deviation of the landing position caused by the unevenness of the recording medium, the deviation of the landing position caused by the speed deviation amount δ _v is reduced. It is not possible.

  The subject of this invention is providing the inkjet recording device which can reduce the shift | offset | difference of a landing position.

The invention according to claim 1 is an ink jet recording apparatus,
A serial type recording head that discharges ink from a plurality of ejection openings toward a recording medium;
A control device for controlling the recording head;
A transport device for transporting the recording medium in the transport direction;
A scanning device that moves the recording head relative to the recording medium along a scanning direction substantially orthogonal to the transport direction;
The control device may change the discharge timing of at least some of the plurality of discharge ports based on the scanning speed of the recording head.

  According to the first aspect of the present invention, since the ejection timing of at least some of the plurality of ejection ports is changed based on the scanning speed of the recording head, this speed change can be achieved even when the scanning speed of the recording head changes. It is possible to suppress the deviation of the ink landing position along the image recording direction, that is, the scanning direction. Therefore, unlike the prior art, it is possible to record an image with a constant image quality regardless of the scanning speed of the recording head.

As a method of changing the ejection timing based on the scanning speed of the recording head, there are a method of increasing the ejection timing as the scanning speed increases, and a method of delaying the ejection timing as the scanning speed decreases. Then, the former is preferable.
In addition, as a method of acquiring the scanning speed, there are a method of acquiring from the control condition of the scanning device and a method of providing a speed detector for detecting the scanning speed and detecting by this speed detector. The latter is preferred for acquisition.

The invention described in claim 2 is the ink jet recording apparatus according to claim 1,
The control device includes:
The larger the scanning speed, the larger the amount of change in the ejection timing with respect to the amount of change in the scanning speed.

  According to the second aspect of the present invention, the amount of change in the ejection timing with respect to the amount of change in the scanning speed is increased as the scanning speed is increased. Therefore, the deviation amount of the ink landing position that increases as the scanning speed increases is reduced. be able to. Therefore, it is possible to reliably align the ink landing positions for the respective ejection openings regardless of the scanning speed of the recording head, and to record an image with a constant image quality.

The invention described in claim 3 is the ink jet recording apparatus according to claim 1 or 2,
A scanning speed detecting device for detecting the scanning speed is provided.

According to the third aspect of the present invention, since the scanning speed detecting device for detecting the scanning speed is provided, the deviation of the landing position can be reduced even when the scanning speed changes during image recording.
Unlike the case where the scanning speed is detected from the control conditions of the scanning device, the actual scanning speed can be reliably acquired regardless of an error or failure during driving.

Invention of Claim 4 is an inkjet recording device as described in any one of Claims 1-3,
A first storage device that stores a relative shift amount of the ink landing position on the recording medium in the scanning direction in association with each ejection port;
The control device may change the discharge timing of at least some of the plurality of discharge ports based on the shift amount and the scanning speed.

  According to the fourth aspect of the invention, since the ejection timing is changed based on the deviation amount and the scanning speed, it is possible to reduce the deviation of the landing position for each ejection port, that is, to ensure that the landing positions are aligned. Can do.

The invention according to claim 5 is an ink jet recording apparatus,
A serial type recording head that discharges ink from a plurality of ejection openings toward a recording medium;
A control device for controlling the recording head;
A transport device for transporting the recording medium in the transport direction;
A scanning device that moves the recording head relative to the recording medium along a scanning direction substantially orthogonal to the transport direction;
The control device may change the discharge timing of at least some of the plurality of discharge ports based on the scanning direction of the recording head.

  According to the fifth aspect of the present invention, since the ejection timing of at least a part of the plurality of ejection ports is changed based on the scanning direction of the recording head, this change is caused even when the scanning direction of the recording head changes. As a result, it is possible to suppress the deviation of the ink landing position along the image recording direction, that is, the scanning direction. Therefore, unlike the prior art, it is possible to record an image with a constant image quality regardless of the scanning direction of the recording head.

The invention according to claim 6 is the ink jet recording apparatus according to claim 5,
A first storage device that stores a relative shift amount of the ink landing position on the recording medium in the scanning direction in association with each ejection port;
The control device may change the discharge timing of at least some of the plurality of discharge ports based on the shift amount and the scanning direction.

  According to the sixth aspect of the invention, since the discharge timing is changed based on the shift amount and the scanning direction, it is possible to reduce the shift of the landing position for each discharge port, that is, to ensure that the landing positions are aligned. Can do.

The invention according to claim 7 is the ink jet recording apparatus according to claim 4 or 6,
The first storage device
The shift amount is stored while being changed relative to the flying speed of the ink ejected from each ejection port.

  According to the seventh aspect of the invention, the ejection timing can be controlled in accordance with the variation in the ink flying speed for each ejection port. Accordingly, the landing positions can be more reliably aligned with respect to the image recording direction.

The invention according to claim 8 is an ink jet recording apparatus,
A line-type recording head that discharges ink from a plurality of ejection openings toward a recording medium;
A control device for controlling the recording head;
A transport device for transporting the recording medium in the transport direction;
The control device may change the discharge timing of at least some of the plurality of discharge ports based on the conveyance speed of the recording medium.

  According to the eighth aspect of the invention, since the ejection timing of at least a part of the plurality of ejection ports is changed based on the conveyance speed of the recording medium, this change in speed is also achieved when the conveyance speed of the recording medium changes. It is possible to prevent the ink landing position from deviating along the image recording direction, that is, the direction opposite to the conveying direction. Therefore, unlike the prior art, it is possible to record an image with a constant image quality regardless of the conveyance speed of the recording medium.

As a method of changing the discharge timing based on the conveyance speed of the recording medium, there are a method of increasing the discharge timing as the conveyance speed increases, and a method of delaying the discharge timing as the conveyance speed decreases. Then, the former is preferable.
In addition, as a method of acquiring the transport speed, there are a method of acquiring from the control conditions of the transport device, and a method of providing a speed detector for detecting the transport speed and detecting by this speed detector. The latter is preferred for acquisition.

The invention according to claim 9 is the ink jet recording apparatus according to claim 8,
The control device includes:
The larger the conveyance speed, the larger the change amount of the discharge timing with respect to the change amount of the conveyance speed.

  According to the ninth aspect of the present invention, the amount of change in the ejection timing with respect to the amount of change in the conveyance speed is increased as the conveyance speed is increased. be able to. Therefore, it is possible to reliably align the ink landing positions for the respective ejection openings regardless of the conveyance speed of the recording medium, and to record an image with a constant image quality.

The invention according to claim 10 is the inkjet recording apparatus according to claim 8 or 9, wherein
A transport speed detecting device for detecting the transport speed is provided.

According to the tenth aspect of the present invention, since the transport speed detecting device for detecting the transport speed is provided, the deviation of the landing position can be reduced even when the transport speed changes during image recording.
Further, unlike the case where the conveyance speed is detected from the control conditions of the conveyance apparatus, the actual conveyance speed can be reliably acquired regardless of an error or failure during driving.

The invention according to claim 11 is the ink jet recording apparatus according to any one of claims 8 to 10, wherein
A second storage device that stores a relative shift amount of the ink landing position on the recording medium in the transport direction in association with each ejection port;
The controller is characterized in that the discharge timing of at least some of the plurality of discharge ports is changed based on the deviation amount and the transport speed.

  According to the eleventh aspect of the present invention, since the discharge timing is changed based on the shift amount and the conveyance speed, it is possible to reduce the shift of the landing position for each discharge port, that is, to ensure that the landing positions are aligned. Can do.

The invention according to claim 12 is an ink jet recording apparatus,
A line-type recording head that discharges ink from a plurality of ejection openings toward a recording medium;
A control device for controlling the recording head;
A transport device for transporting the recording medium in the transport direction;
The control device may change the discharge timing of at least some of the plurality of discharge ports based on the conveyance direction of the recording medium.

According to the twelfth aspect of the invention, since the ejection timing of at least a part of the plurality of ejection ports is changed based on the conveyance direction of the recording medium, this change is also caused when the conveyance direction of the recording medium changes. As a result, it is possible to suppress the deviation of the ink landing position along the image recording direction, that is, the direction opposite to the transport direction. Therefore, unlike the conventional case, it is possible to record an image with a constant image quality regardless of the conveyance direction of the recording medium.
Note that the case where the conveyance direction of the recording medium changes includes the case where the conveyance direction is reversed only when recording is performed on the end of the recording medium.

A thirteenth aspect of the present invention is the ink jet recording apparatus according to the twelfth aspect,
A second storage device that stores a relative shift amount of the ink landing position on the recording medium in the transport direction in association with each ejection port;
The control device is characterized in that the discharge timing of at least some of the plurality of discharge ports is changed based on the shift amount and the transport direction.

  According to the thirteenth aspect of the invention, since the ejection timing is changed based on the deviation amount and the transport direction, the deviation of the landing position for each ejection port can be reduced, that is, the landing positions are more reliably aligned. be able to.

The invention according to claim 14 is the ink jet recording apparatus according to claim 11 or 13,
The second storage device
The shift amount is stored while being changed relative to the flying speed of the ink ejected from each ejection port.

  According to the fourteenth aspect of the invention, it is possible to control the ejection timing in accordance with the variation in the ink flying speed for each ejection port. Accordingly, the landing positions can be more reliably aligned with respect to the image recording direction.

The invention according to claim 15 is the ink jet recording apparatus according to any one of claims 1 to 14,
An irradiation device for irradiating the ink landed on the recording medium with light;
The ink is a photocurable ink.

  According to the fifteenth aspect of the present invention, even when using a photo-curing ink that has a remarkable deterioration in image quality due to a shift in the landing position, the same as in the first aspect of the present invention. The effect of can be obtained.

  According to the first aspect of the invention, unlike the prior art, it is possible to record an image with a constant image quality regardless of the scanning speed of the recording head.

  According to the second aspect of the present invention, the effects of the first aspect of the invention can be obtained, and the ink landing positions for the respective ejection ports are surely aligned and fixed regardless of the scanning speed of the recording head. It is possible to record high quality images.

  According to the third aspect of the invention, the effect of the first or second aspect can be obtained, and even if the scanning speed changes during image recording, the landing position shifts. Can be reduced.

  According to the invention described in claim 4, the effects of the invention described in any one of claims 1 to 3 can be obtained, and the landing positions can be surely aligned.

  According to the fifth aspect of the invention, unlike the prior art, it is possible to record an image with a constant image quality regardless of the scanning direction of the recording head.

  According to the sixth aspect of the invention, not only the effect of the fifth aspect of the invention can be obtained, but also the landing positions can be reliably aligned.

  According to the seventh aspect of the invention, not only can the effect of the fourth or sixth aspect of the invention be obtained, but also the landing positions can be more reliably aligned with respect to the image recording direction.

  According to the eighth aspect of the invention, unlike the prior art, it is possible to record an image with a constant image quality regardless of the conveyance speed of the recording medium.

  According to the ninth aspect of the invention, the effect of the eighth aspect of the invention can be obtained, and the ink landing position for each ejection port is surely aligned and fixed regardless of the conveyance speed of the recording medium. It is possible to record high quality images.

  According to the tenth aspect of the present invention, it is possible to obtain the effects of the eighth or ninth aspect of the invention, and even if the conveyance speed changes during image recording, the landing position shifts. Can be reduced.

  According to the eleventh aspect of the present invention, it is possible to obtain the effects of the invention according to any one of the eighth to tenth aspects as well as the landing positions with certainty.

  According to the twelfth aspect of the invention, unlike the prior art, it is possible to record an image with a constant image quality regardless of the conveyance direction of the recording medium.

  According to the thirteenth aspect of the invention, it is possible to obtain the effects of the twelfth aspect of the invention, and of course, the landing positions can be more reliably aligned.

  According to the fourteenth aspect of the present invention, the effects of the eleventh or thirteenth aspect of the invention can be obtained, and the landing positions can be more reliably aligned with respect to the image recording direction.

  According to the invention of the fifteenth aspect, the same effect as that of the invention according to any one of the first to fourteenth aspects can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, the ink jet recording apparatus will be described as an ink jet printer. This ink jet printer is a device that records a desired image with a photo-curable ink on a continuously conveyed recording medium.

<First Embodiment>
As shown in FIG. 1A, the ink jet printer 1 according to the present embodiment is provided with an image recording apparatus 2 on which various apparatuses for recording an image are mounted so as to face the platen 4.

  The platen 4 supports the recording medium K from the back side. The recording medium K supported by the platen 4 is intermittently conveyed along the conveyance direction A by a conveyance device 18 such as a roller.

  Above the platen 4, a guide member 5 extending along a scanning direction (image recording direction) B substantially orthogonal to the transport direction A is disposed. A carriage (first moving device) 6 is supported on the guide member 5. The carriage 6 can reciprocate along the scanning direction B on the recording medium K while being guided by the guide member 5. That is, the carriage 6 is movable relative to the recording medium K along the scanning direction B.

Mounted on the carriage 6 are four recording heads 7 to 10 that eject inks of process colors of yellow (Y), magenta (M), cyan (C), and black (K).
These recording heads 7 to 10 are arranged along the scanning direction B, and as shown in FIG. 1B, are provided with a plurality of ejection ports 13,.

  Further, irradiation devices 11 and 12 for irradiating ultraviolet rays toward the lower recording medium K are mounted on both ends of the carriage 6. The irradiation devices 11 and 12 include an ultraviolet light source 110 that irradiates ultraviolet rays. As the ultraviolet light source 110, a fluorescent tube, a laser, an LED, an electron beam irradiation device, or the like can be used.

  The carriage 6 is provided with a scanning speed detection device 14 (see FIG. 2) that detects the scanning speed and the scanning direction of the carriage 6. As the scanning speed detection device 14, a known speed detection device such as an encoder can be used.

  In addition, as shown in Table 1 below, for example, the inkjet printer 1 includes a storage device (first storage device) that stores, as a table, correction amounts of the discharge timings of the discharge ports 13 according to the scanning speed and the scanning direction. FIG. 2) 16 is provided.

  In the table, “scanning speed 1” and “scanning speed 2” are scanning speeds of the recording heads 7 to 10. “Direction 1” and “Direction 2” are scanning directions of the recording heads 7 to 10. In this embodiment, the scanning direction from the left side to the right side in FIG. The scanning direction is “direction 2”.

  The “reference correction amount” is a value used to calculate the correction amount of the discharge ports 13,... And is stored in association with each discharge port 13. This “reference correction amount” is calculated on the basis of the deviation amount δ (see FIGS. 4A and 4B) of the ink landing position in the scanning direction B, and the ink landing positions of the respective ejection ports 13. Represents the relative amount of deviation. In the present embodiment, “reference correction amount” = deviation amount δ. Further, the deviation amount δ is larger as the ejection port has a lower flying speed of ejected ink.

  Each correction amount indicates the discharge timing of each discharge port 13 with respect to the reference discharge timing when the reference discharge timing is “100”. The smaller the value, the earlier the discharge timing. I mean. These correction amounts are calculated by adding an integral multiple of the “reference correction amount” to the reference ejection timing “100”. Specifically, in the case of “scanning speed 1 / direction 1”, (100+ “Reference correction amount” × 2), “scanning speed 1 / direction 2” (100+ “reference correction amount” × 3), and “scanning speed 2 / direction 1” (100+ “reference correction amount”) ”× (−2)) and“ scanning speed 2 / direction 2 ”are calculated from (100+“ reference correction amount ”× (−3)). The correction amount is set such that the larger the scanning speed, the larger the change amount of the ejection timing with respect to the change amount of the scanning speed. In Table 1, the discharge timing of the discharge ports 13 having the discharge port numbers “1”, “7”, and “8” is constant regardless of the scanning speed and the scanning direction.

Connected to the storage device 16 is a control device 15 that controls the carriage 6, the transport device 18, the irradiation devices 11 and 12, the recording heads 7 to 10, and the like.
The control device 15 uses the detection result of the scanning speed detection device 14 to scan the carriage 6 at a predetermined scanning speed.
The control device 15 controls the transport device 18 to transport the recording medium K in the transport direction A.
The control device 15 controls the irradiation of ultraviolet rays by the irradiation devices 11 and 12.

  Further, the control device 15 changes the ejection timing of the ejection ports 13 in the recording heads 7 to 10 based on the detection result by the scanning speed detection device 14 and the table stored in the storage device 16. It has become.

Next, “ink” used in the present embodiment will be described.
The ink used in the present embodiment is a high-viscosity ink having a viscosity of about 10 to 500 [mpas] at 30 ° C. In addition, this ink is not cured by contact with air (air in the atmosphere) but is cured by a system that is open to contact with air. Specifically, the ink used in the present embodiment is a photocurable ink having a property of being cured by irradiation with ultraviolet rays as light, and includes a polymerizable compound (a known polymerizable compound) as a main component. ), A photoinitiator, and a coloring material, and further has a viscosity of 10 to 500 m · Pa at 30 ° C.

  The above-mentioned photocurable ink is roughly classified into a radical polymerization type ink containing a radical polymerizable compound and a cationic polymerization type ink containing a cationic polymerizable compound as the polymerizable compound. As the ink used in the present embodiment, a hybrid ink in which a radical polymerization ink and a cation polymerization ink are combined may be used as the ink used in the present embodiment. In the present embodiment, a cationic polymerization ink is used among the photocurable inks.

Next, the “recording medium K” used in the present embodiment will be described.
As the recording medium K used in the present embodiment, recording made of various papers such as plain paper, recycled paper, glossy paper, etc., various fabrics, various non-woven fabrics, resin, metal, glass and the like applied to a normal inkjet printer. The medium is applicable. As the form of the recording medium K, a roll shape, a cut sheet shape, a plate shape, or the like is applicable.

  In particular, as the recording medium K used in the present embodiment, a transparent or opaque non-absorbent resin film used for so-called soft packaging can be applied. Specific resin types of resin film include polyethylene terephthalate, polyester, polyolefin, polyamide, polyesteramide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, poly-ρ-phenylene sulfide, polyether ester, polyvinyl chloride , Poly (meth) acrylic acid ester, polyethylene, polypropylene, nylon and the like are applicable, and further, copolymers of these resins, mixtures of these resins, and those obtained by crosslinking these resins are also applicable. Above all, as the type of resin of the resin film, one of stretched polyethylene terephthalate, polystyrene, polypropylene, and nylon is selected because of the transparency, dimensional stability, rigidity, environmental load, cost, etc. of the resin film. It is preferable to use a resin film having a thickness of 2 to 100 μm (preferably 6 to 50 μm). Moreover, you may perform surface treatments, such as a corona discharge process and an easily bonding process, on the surface of the support body of resin films.

  Further, as the recording medium K used in the present embodiment, known opaque recording media such as various papers whose surfaces are coated with a resin, a film containing a pigment, and a foamed film are also applicable.

Next, the operation of the inkjet printer 1 during image recording will be described.
First, the carriage 6 scans immediately above the recording medium K along the scanning direction B once in a state where the conveyance of the recording medium K by the conveying device 18 is stopped.

  As a result, the recording heads 7 to 10 and the irradiation devices 11 and 12 follow the carriage 6 to scan, and the ejection ports 13 of the recording heads 7 to 10 apply ink to the recording medium K during the scanning. Discharge. At this time, the scanning speed detection device 14 detects the scanning speed of the carriage 6. From this detection result, the control device 15 calculates the correction amount of the discharge timing of each discharge port 13,... Based on the table created using the deviation amount δ of the ink landing position, and based on each correction amount. The discharge timing of each discharge port 13 is controlled. In this way, the control device 15 controls the ejection timing of each ejection port 13,... Based on the scanning speed of the carriage 6 and the amount of deviation δ of the ink landing position of each ejection port 13. Even when at least one of the scanning direction changes, the ink landing positions of the respective ejection openings 13 in the image recording direction, that is, the scanning direction B are constant.

  Further, during the scanning, the irradiation device 11 (or 12) behind the recording heads 7 to 10 with respect to the moving direction of the carriage 6 is turned on to irradiate the surface of the recording medium K with ultraviolet rays. As a result, the ink ejected from each of the recording heads 7 to 10 is immediately cured by the ultraviolet rays immediately after landing on the recording medium K, and is fixed on the surface of the recording medium K.

Next, the recording medium K is transported in the transport direction A by a predetermined length by the transport device 18.
Thereafter, the inkjet printer 1 repeats the above operations, and a desired image composed of a plurality of dots of each process color is sequentially recorded on the surface of the recording medium K.

  According to the ink jet printer 1 as described above, the ink landing positions of the respective ejection ports 13 with respect to the scanning direction B can be made constant even when at least one of the scanning speed and the scanning direction changes. Unlike the prior art, it is possible to record an image with a constant image quality.

  In addition, since the correction amount is set so that the amount of change in the ejection timing with respect to the amount of change in the scanning speed increases as the scanning speed increases, the amount of deviation in the ink landing position that increases as the scanning speed increases is reduced. can do.

In addition, since the scanning speed is measured in real time by the scanning speed detector 14, even if the scanning speed changes during image recording, the change in the ink landing position due to this change can be reduced. Further, unlike the case where the scanning speed is detected from the control conditions of the carriage 6, the actual scanning speed can be reliably acquired regardless of an error or failure during driving.
Further, since the ejection timing is changed by the correction amount calculated based on the ink flying speed of each ejection port 13,..., Variations in ink landing positions due to variations in ink flying speed can be reduced.

<Second Embodiment>
Next, the ink jet printer 1A in the second embodiment will be described. In addition, the same code | symbol is attached | subjected to the component same as the said 1st Embodiment, and the description is abbreviate | omitted.

As shown in FIG. 3A, the ink jet printer 1B in the present embodiment is a line type, and the recording heads 7 to 10 and the irradiation devices 11 and 12 extend over both ends of the recording medium K.
A plurality of ejection ports 13,... Are arranged along the width direction Y of the recording medium K on the lower surface of the recording heads 7 to 10.

  The transport device 18A can transport the recording medium K in both directions along the transport direction A. The transport device 18A is provided with a transport speed detection device 14A (see FIG. 3B) that detects the transport speed and the transport direction of the recording medium K.

  Further, as shown in FIG. 3B, the inkjet printer 1A stores the correction amount of the discharge timing of each discharge port 13,... According to the transport speed and the transport direction as a table similar to Table 1 above. A storage device (second storage device) 16A is provided. This correction amount is set such that the greater the conveyance speed, the greater the variation in the discharge timing with respect to the variation in the conveyance speed.

The storage device 16A is connected to a control device 15A that controls the transport device 18A, the irradiation devices 11 and 12, the recording heads 7 to 10, and the like.
The control device 15 controls the transport device 18A to transport the recording medium K at a predetermined transport speed.
The control device 15 controls the irradiation of ultraviolet rays by the irradiation devices 11 and 12.

  Further, the control device 15 changes the ejection timing of the ejection ports 13 in the recording heads 7 to 10 based on the detection result by the transport speed detection device 14A and the table stored in the storage device 16A. It has become.

Next, the operation of the inkjet printer 1A during image recording will be described.
In the ink jet printer 1A, the ejection ports 13,... Of the recording heads 7 to 10 eject ink to the recording medium K in a state where the recording medium K is conveyed by the conveying device 18A. At this time, the conveyance speed detection device 14A detects the conveyance speed of the recording medium K. From this detection result, the control device 15A calculates the correction amount of the ejection timing of each ejection port 13,... Based on the table created using the deviation amount of the ink landing position of each ejection port 13,. The discharge timing of each discharge port 13 is controlled based on each correction amount. In this way, the control device 15 controls the ejection timing of each ejection port 13,... Based on the conveyance speed of the recording medium K and the amount of deviation of the ink landing position of each ejection port 13. Even when at least one of the transport directions changes, the ink landing positions of the respective ejection ports 13 in the image recording direction, that is, the transport direction A are constant.

  During the conveyance, the irradiation device 11 (or 12) behind the recording heads 7 to 10 is turned on with respect to the conveyance direction A of the recording medium K, and ultraviolet rays are irradiated toward the surface of the recording medium K. To do. As a result, the ink ejected from each of the recording heads 7 to 10 is immediately cured by the ultraviolet rays immediately after landing on the recording medium K, and is fixed on the surface of the recording medium K. Thereby, a desired image composed of a plurality of dots of each process color is sequentially recorded on the surface of the recording medium K.

  According to the ink jet printer 1A as described above, even when at least one of the transport speed and the transport direction changes, the ink landing positions of the respective ejection ports 13 with respect to the transport direction A can be made constant. Unlike the prior art, it is possible to record an image with a constant image quality.

  In addition, since the correction amount is set so that the amount of change in the ejection timing with respect to the amount of change in the transport speed increases as the transport speed increases, the amount of deviation in the ink landing position that increases as the transport speed increases is reduced. can do.

Further, since the transport speed is measured in real time by the transport speed detection device 14A, even if the transport speed changes during image recording, the change in the ink landing position due to this change can be reduced. Further, unlike the case where the conveyance speed is detected from the control conditions of the carriage 6, the actual conveyance speed can be reliably acquired regardless of an error or failure during driving.
Further, since the ejection timing is changed by the correction amount calculated based on the ink flying speed of each ejection port 13,..., Variations in ink landing positions due to variations in ink flying speed can be reduced.

  In the first and second embodiments, the number of recording heads has been described as four. However, the number may be three or less, or may be five or more.

  Further, in the first embodiment, it has been described that the ejection timing of the ejection ports 13 is changed when at least one of the scanning speed and the scanning direction changes, but one of the scanning speed or the scanning direction is changed. The discharge timing may be changed when only the pressure changes.

  In the second embodiment, it has been described that the discharge timing of the discharge ports 13,... Is changed when at least one of the transport speed and the transport direction changes. The discharge timing may be changed when only the pressure changes.

(A) is a top view which shows schematic structure of an inkjet printer, (b) is a bottom view of a carriage. It is a block diagram which shows schematic structure of an inkjet printer. It is a figure which shows schematic structure of the inkjet printer in other embodiment, (a) is a top view, (b) is a block diagram. It is a figure for demonstrating the deviation | shift amount of an ink landing position.

Explanation of symbols

1 Inkjet printer (inkjet recording device)
6 Carriage (moving device)
7 to 10 Recording heads 11 and 12 Irradiation device 13 Discharge port 14 Scanning speed detection device 14A Transport speed detection devices 15 and 15A Control device 16 Storage device (first storage device)
16A storage device (second storage device)
18, 18A Conveying device K Recording medium

Claims (15)

A serial type recording head that discharges ink from a plurality of ejection openings toward a recording medium;
A control device for controlling the recording head;
A transport device for transporting the recording medium in the transport direction;
A scanning device that moves the recording head relative to the recording medium along a scanning direction substantially orthogonal to the transport direction;
The control apparatus changes an ejection timing of at least some of the plurality of ejection ports based on a scanning speed of the recording head. The inkjet recording apparatus according to claim 1, wherein
The control device includes:
The inkjet recording apparatus, wherein the amount of change in ejection timing with respect to the amount of change in scanning speed is increased as the scanning speed is increased. The inkjet recording apparatus according to claim 1 or 2,
An ink jet recording apparatus comprising: a scanning speed detecting device for detecting the scanning speed. In the ink jet recording apparatus according to any one of claims 1 to 3,
A first storage device that stores a relative shift amount of the ink landing position on the recording medium in the scanning direction in association with each ejection port;
The control apparatus changes an ejection timing of at least some of the plurality of ejection ports based on the shift amount and the scanning speed. A serial type recording head that discharges ink from a plurality of ejection openings toward a recording medium;
A control device for controlling the recording head;
A transport device for transporting the recording medium in the transport direction;
A scanning device that moves the recording head relative to the recording medium along a scanning direction substantially orthogonal to the transport direction;
The control apparatus changes an ejection timing of at least some of the plurality of ejection ports based on a scanning direction of the recording head. The inkjet recording apparatus according to claim 5.
A first storage device that stores a relative shift amount of the ink landing position on the recording medium in the scanning direction in association with each ejection port;
The control apparatus changes an ejection timing of at least some of the plurality of ejection openings based on the shift amount and the scanning direction. The inkjet recording apparatus according to claim 4 or 6,
The first storage device
An ink jet recording apparatus, wherein the shift amount is stored while being changed relative to the flying speed of the ink discharged from each discharge port. A line-type recording head that discharges ink from a plurality of ejection openings toward a recording medium;
A control device for controlling the recording head;
A transport device for transporting the recording medium in the transport direction;
The control apparatus changes an ejection timing of at least some of the plurality of ejection ports based on a conveyance speed of the recording medium. The ink jet recording apparatus according to claim 8.
The control device includes:
The ink jet recording apparatus, wherein the amount of change in ejection timing with respect to the amount of change in transport speed is increased as the transport speed is increased. The ink jet recording apparatus according to claim 8 or 9,
An ink jet recording apparatus comprising a transport speed detecting device for detecting the transport speed. In the ink jet recording apparatus according to any one of claims 8 to 10,
A second storage device that stores a relative shift amount of the ink landing position on the recording medium in the transport direction in association with each ejection port;
The control apparatus changes an ejection timing of at least some of the plurality of ejection ports based on the shift amount and the conveyance speed. A line-type recording head that discharges ink from a plurality of ejection openings toward a recording medium;
A control device for controlling the recording head;
A transport device for transporting the recording medium in the transport direction;
The control apparatus changes an ejection timing of at least some of the plurality of ejection openings based on a conveyance direction of the recording medium. The inkjet recording apparatus according to claim 12, wherein
A second storage device that stores a relative shift amount of the ink landing position on the recording medium in the transport direction in association with each ejection port;
The control apparatus changes an ejection timing of at least some of the plurality of ejection ports based on the shift amount and the transport direction. The inkjet recording apparatus according to claim 11 or 13,
The second storage device
An ink jet recording apparatus, wherein the shift amount is stored while being changed relative to the flying speed of the ink discharged from each discharge port. In the ink jet recording apparatus according to any one of claims 1 to 14,
An irradiation device for irradiating the ink landed on the recording medium with light;
An ink jet recording apparatus, wherein the ink is a photocurable ink.

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