JP2006150788A - Image recording method and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder which can carry out high-definition image recording by preventing generation of differences of a color tone and an impression of gloss at every band in a main scanning direction. <P>SOLUTION: The inkjet recorder is equipped with a recording head 6 which ejects onto a recording medium P a photo-curing type ink that is cured by irradiation of light, an ultraviolet irradiator which applies ultraviolet rays to the ejected ink, a carriage driving mechanism 11 which scans the recording head 6 back and forth in a direction orthogonal to a transfer direction X of the recording medium P, and a control part 8 which controls the carriage driving mechanism 11 to form one band by scanning the recording head 7 back and forth by a plurality of the number of times, and at the same time which controls the recording head 6 to lessen an ink ejection amount ejected from the recording head 6 in the final scan of the reciprocative scanning necessary for forming one band. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image recording method and an ink jet recording apparatus, and more particularly to an ink jet recording apparatus that performs image recording by a serial printing method.

  In general, an ink jet recording apparatus (hereinafter, referred to as “ink jet recording apparatus”) is known as an ink jet recording apparatus that can flexibly meet the demand for a small variety of products. An ink jet recording apparatus records an image on a recording medium by ejecting ink from a nozzle provided on the surface of the recording head facing the recording medium, and landing and fixing on the recording medium. Conventional gravure printing Unlike the image recording means based on the system or flexographic printing system, it does not require a plate making process, and therefore can easily and quickly respond to a small amount of demand. In addition, there is an advantage that color image recording can be easily performed by using multi-color ink with less noise.

  Further, in recent years, an ink jet recording apparatus using a photocurable ink is known as an ink jet recording apparatus compatible with various recording media (see, for example, Patent Document 1). This is because a photocurable ink containing a photoinitiator having a predetermined sensitivity to light such as ultraviolet rays is used, and the ink is cured by irradiating the ink landed on the recording medium with light. It is to fix on top. An ink jet recording apparatus using such a photocurable ink, after ink landing, the ink is cured instantaneously by irradiating light, so that there is little ink penetration or bleeding into the recording medium, not only plain paper, It is possible to record an image on a recording medium such as plastic or metal that does not have an ink receiving layer and has no ink absorbability.

  By the way, in such an ink jet recording apparatus, the recording head is reciprocated in the main scanning direction, and ink is ejected from each recording head while intermittently transporting the recording medium in the transport direction orthogonal to the main scanning direction. In a serial printing type ink jet recording apparatus for forming an image, there is a problem that a color tone and glossiness of a recorded image differ in the main scanning direction between the forward path and the backward path of the recording head.

  This is because the order of the color of the ink ejected to the recording medium differs between the forward path and the backward path of the recording head, so that the degree of ink penetration, ink wettability, and degree of curing previously landed on the recording medium This is because, for example, the dot diameter of the ink that has landed later varies in the degree of dot diameter and the degree of dot connection. The extent of the dot diameter of the ink, the degree of dot connection, and the like depend on the difference in curing timing due to light irradiation, the intensity of the irradiated light, and the like.

  In order to eliminate such differences in the color tone and glossiness of the recorded image in the main scanning direction, conventionally, two sets of recording heads that eject ink of a plurality of colors are arranged symmetrically with respect to the main scanning direction. A technique is known in which there is no difference in the degree of ink overlap in both forward and backward passes in the scanning direction (see, for example, Patent Document 2).

In addition, a technique for adjusting the amount of ink discharged in an ink jet recording apparatus that performs image recording using water-based ink is also known (see, for example, Patent Document 3).
JP 2001-310454 A Japanese Patent No. 3248704 Japanese Patent Laid-Open No. 2003-25613

  However, the technique described in Patent Document 2 requires the recording head to be mounted twice as much as the conventional one, which leads to an increase in size and weight of the apparatus.

  The technique described in Patent Document 3 adjusts the ink discharge amount in accordance with the degree of ink penetration when using water-based ink that penetrates the recording medium, and hardly penetrates the recording medium. In addition, it does not correspond to the photo-curing ink in which the ink dot diameter expansion condition, the dot connection condition, and the like depend on the difference in the curing timing by light irradiation, the intensity of the irradiated light, and the like.

  Accordingly, the present invention has been made to solve the above-described problems, and can prevent high-definition image recording by preventing occurrence of a difference in color tone and glossiness for each band in the main scanning direction. It is an object of the present invention to provide an ink jet recording apparatus that can be used.

  In order to solve the above-mentioned problem, the invention described in claim 1 is characterized in that the recording head is reciprocally scanned a plurality of times, photocurable ink is ejected from the recording head onto a recording medium, and light is emitted from a light source irradiation device. In the image recording method in which one band is formed by curing and fixing the ink, the ink is ejected at random from the recording head at the last scanning of the reciprocating scanning for forming the one band. Features.

  According to the first aspect of the present invention, the photocurable ink is ejected from the recording head while the recording head is reciprocally scanned in the direction orthogonal to the conveyance direction of the recording medium, and the ejected ink is irradiated with light by the light irradiation device. In this method, an image is recorded and a recording head is reciprocated a plurality of times to form one band. The reciprocating scanning required to form a single band is the recording head in the last scanning. The ink ejected from the ink is thinned out randomly.

  According to a second aspect of the present invention, in the image recording method according to the first aspect, at the second scanning from the end of the reciprocating scanning for forming the one band, ink is ejected at random from the recording head. It is characterized by that.

  Therefore, in the second aspect of the invention, among the reciprocating scans necessary for forming one band, the ink ejected from the print head is randomly thinned out in the second scan from the last. .

According to a third aspect of the present invention, there is provided a recording head that discharges a photocurable ink that is cured by irradiation of light onto a recording medium;
A light irradiation device comprising a light source for irradiating the ejected ink with light;
Head scanning means for reciprocatingly scanning the recording head in a direction orthogonal to the conveyance direction of the recording medium;
In the last scan of the reciprocating scan necessary for forming one band when scanning and recording the head scanning means so as to form one band by reciprocating the recording head a plurality of times, And a control unit for controlling the recording head so as to thin out ink ejected from the recording head at random.

  In the invention according to claim 3 having such a configuration, photocurable ink is ejected from the recording head while the recording head is reciprocally scanned in a direction orthogonal to the conveyance direction of the recording medium, and the ejected ink is discharged. Image recording is performed by irradiating light with a light irradiation device, and one band is formed by reciprocally scanning the recording head a plurality of times. The control unit is necessary to form one band. Of these reciprocating scans, the ink ejected from the recording head is randomly thinned out in the last scan.

  According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the third aspect, the control unit performs the recording head in the second scan from the end of the reciprocating scan necessary for forming one band. The recording head is controlled so that ink ejected from the ink is thinned out randomly.

  Therefore, in the invention according to the fourth aspect, among the reciprocating scans necessary to form one band, the ink ejected from the recording head is randomly thinned out in the second scan from the last. .

  Further, according to a fifth aspect of the present invention, in the ink jet recording apparatus according to the third aspect, the control unit is ejected from the recording head in the last scanning of the reciprocating scanning necessary for forming one band. The ink ejection amount is characterized in that the recording head is controlled so that the dot diameter when landed on the recording medium is equal to or greater than the inter-dot distance between the ink dots that land adjacently.

  As described above, the invention according to claim 5 is the dot diameter when the ink discharge amount discharged from the recording head in the last scanning of the reciprocating scanning necessary for forming one band lands on the recording medium. Since the control unit controls the recording head so that the distance between the adjacent ink dots is equal to or greater than the inter-dot distance, the ink dots are coupled to each other on the recording medium.

Furthermore, the invention according to claim 6 is the ink jet recording apparatus according to claim 3 or 5, wherein a plurality of the recording heads are arranged,
The control unit determines a thinning rate of ink ejected from the recording head in the last scanning of the reciprocating scanning necessary for forming one band according to the distance between the recording head and the light irradiation device. It is characterized by doing.

  Therefore, according to the sixth aspect of the present invention, when a plurality of recording heads are arranged, the reciprocating scanning required for forming one band is formed according to the distance between the recording head and the light irradiation device. The controller determines a thinning rate of ink ejected from the recording head in the last scan.

The invention according to claim 7 is the ink jet recording apparatus according to any one of claim 3, claim 5 or claim 6, wherein a plurality of the recording heads are arranged for each color ink,
The controller determines a thinning-out rate of ink ejected from the recording head in the last scan of the reciprocating scan necessary for forming one band according to the type of ink.

  Thus, according to the seventh aspect of the present invention, when a plurality of recording heads are arranged for each color of ink, the reciprocating scanning required to form one band according to the type of ink. The controller determines the thinning rate of ink ejected from the recording head in the last scan.

  Furthermore, an invention according to an eighth aspect is the ink jet recording apparatus according to any one of the third and fifth to seventh aspects, wherein the control unit is configured according to a type of the recording medium. It is characterized in that the thinning-out rate of the ink ejected from the recording head is determined in the last scanning of the reciprocating scanning necessary for forming one band.

  As described above, according to the eighth aspect of the present invention, the thinning rate of the ink ejected from the recording head in the final scanning of the reciprocating scanning necessary for forming one band is determined according to the type of the recording medium. The control unit is determined.

  Furthermore, the invention according to claim 9 is the ink jet recording apparatus according to any one of claims 3 and 5 to 8, wherein the control unit is responsive to an image recording speed during image recording. It is characterized in that the thinning-out rate of ink ejected from the recording head is determined in the last scanning of the reciprocating scanning necessary for forming one band.

  As described above, according to the ninth aspect of the present invention, the thinning-out rate of the ink ejected from the recording head in the last scanning of the reciprocating scanning necessary for forming one band is set as the image recording speed at the time of image recording. The control unit is determined according to the above.

The invention described in claim 10 is the inkjet recording apparatus according to any one of claims 3, 5 to 9, and measures the irradiation intensity of the light irradiated from the light irradiation device. With irradiation intensity measuring means,
The control unit determines a thinning rate of ink ejected from the recording head in the last scan of the reciprocating scan necessary for forming one band according to the irradiation intensity measured by the irradiation intensity measuring unit. It is characterized by deciding.

  In the invention according to claim 10 having such a configuration, the ink is ejected from the recording head in the last scanning of the reciprocating scanning necessary for forming the one band by measuring the irradiation intensity by the irradiation intensity measuring means. The thinning rate is determined by the control unit according to the measurement result.

The invention described in claim 11 is the ink jet recording apparatus according to any one of claims 3, 5 to 10, wherein at least one of temperature and humidity around the recording head is used. Temperature and humidity measuring means to measure
In the last scan of the reciprocating scan necessary for forming one band according to at least one of the temperature and humidity around the recording head measured by the temperature and humidity measuring means, A thinning rate of ink ejected from the recording head is determined.

  The invention according to claim 11 having such a configuration is a reciprocating scan required for measuring at least one of the temperature and humidity around the recording head by the temperature / humidity measuring means to form one band. The controller determines the thinning-out rate of the ink ejected from the recording head in the last scan according to the measurement result by the temperature and humidity measuring means.

  According to a twelfth aspect of the present invention, in the ink jet recording apparatus according to any one of the third and fifth to eleventh aspects, the control unit is responsive to a desired image quality of an image to be recorded. Thus, the thinning-out rate of the ink ejected from the recording head is determined in the final scanning of the reciprocating scanning necessary for forming one band.

  The invention according to claim 12 having such a configuration selects a thinning-out rate of ink ejected from the recording head in the last scan among the reciprocating scans necessary for forming one band. The control unit determines the desired image quality selected by the setting means.

  Furthermore, the invention according to claim 13 is the ink jet recording apparatus according to claim 4, wherein the control unit performs the last scan of the reciprocating scan and the second scan from the last necessary for forming one band. The amount of ink ejected from the recording head in at least one of the scanning operations is such that the dot diameter when landed on the recording medium is equal to or greater than the inter-dot distance between the ink dots that land adjacently. It is characterized by controlling the head.

  In this way, the invention according to claim 13 is ejected from the recording head in at least one of the last scan and the second scan from the last of the reciprocating scans necessary to form one band. Since the control unit controls the recording head so that the ink discharge amount is equal to or larger than the dot-to-dot distance between the adjacent ink dots that have landed on the recording medium, the ink dots on the recording medium They are designed to be joined together.

Furthermore, the invention according to claim 14 is the inkjet recording apparatus according to claim 4 or claim 13, wherein a plurality of the recording heads are arranged,
The control unit includes at least one of a last scan and a second scan from the last in a reciprocating scan necessary for forming one band according to a distance between the recording head and the light irradiation device. It is characterized in that a thinning rate of ink ejected from the recording head is determined in scanning.

  Therefore, according to the fourteenth aspect of the present invention, when a plurality of recording heads are arranged, the reciprocating scanning necessary for forming one band is formed according to the distance between the recording head and the light irradiation device. The control unit determines a thinning rate of ink ejected from the recording head in at least one of the last scan and the second to last scan.

The invention according to claim 15 is the ink jet recording apparatus according to any one of claims 4, 13, or 14, wherein a plurality of the recording heads are arranged for each color ink,
The control unit is ejected from the recording head in at least one of the last scanning and the second scanning from the last of the reciprocating scanning necessary to form one band according to the type of ink. It is characterized by determining a thinning rate of ink.

  Thus, according to the fifteenth aspect of the present invention, when a plurality of recording heads are arranged for each color ink, the reciprocating scanning necessary for forming one band according to the type of ink is performed. The controller determines the thinning-out rate of the ink ejected from the recording head in at least one of the last scan and the second scan from the last.

  Furthermore, the invention described in claim 16 is the ink jet recording apparatus according to any one of claims 4, 13 to 15, wherein the control unit is 1 according to the type of the recording medium. It is characterized in that the thinning-out rate of ink ejected from the recording head is determined in at least one of the last scan and the second scan from the last of the reciprocating scans necessary for forming one band. .

  In this way, the invention described in claim 16 is ejected from the recording head in at least one of the last scan and the second scan from the last of the reciprocating scans necessary for forming one band. The control unit determines the ink thinning rate according to the type of the recording medium.

  Furthermore, the invention according to claim 17 is the ink jet recording apparatus according to any one of claims 4 and 13 to 16, wherein the control unit is responsive to an image recording speed during image recording. Determining a thinning-out rate of ink ejected from the recording head in at least one of the last scan and the second-to-last scan required for forming one band; It is a feature.

  As described above, in the invention described in claim 17, the ejection is performed from the recording head in at least one of the last scanning and the second scanning from the last of the reciprocating scanning necessary for forming one band. The control unit determines the thinning rate of the ink to be performed according to the image recording speed at the time of image recording.

The invention described in claim 18 is the inkjet recording apparatus according to any one of claims 4, 13 to 17, wherein the irradiation intensity of the light irradiated from the light irradiation device is measured. With irradiation intensity measuring means,
The control unit is at least one of a last scan and a second scan from the last required for forming one band according to the irradiation intensity measured by the irradiation intensity measuring unit. In this scanning, the thinning rate of ink ejected from the recording head is determined.

  In the invention according to claim 18 having such a configuration, the irradiation intensity is measured by the irradiation intensity measuring means, and the last and second scans of the reciprocating scan necessary for forming one band are measured. The controller determines the thinning-out rate of the ink ejected from the print head in at least one of the scans according to the measurement result.

According to a nineteenth aspect of the present invention, in the ink jet recording apparatus according to any one of the fourth, thirteenth to eighteenth aspects, at least one of a temperature and a humidity around the recording head. Temperature and humidity measuring means to measure
The control unit includes a last scan of a reciprocating scan necessary for forming one band according to at least one of a temperature and a humidity around the recording head measured by the temperature / humidity measuring unit, and It is characterized in that a thinning rate of ink ejected from the recording head is determined in at least one of the second scan from the last.

  According to the nineteenth aspect of the present invention having such a configuration, the temperature and humidity measuring means measures at least one of the temperature and the humidity around the recording head and performs reciprocating scanning necessary to form one band. The controller determines the thinning-out rate of the ink ejected from the recording head in at least one of the last scan and the second scan from the last according to the measurement result by the temperature and humidity measuring means. It has become.

  According to a twentieth aspect of the present invention, in the ink jet recording apparatus according to any one of the fourth and thirteenth to nineteenth aspects, the control unit is responsive to a desired image quality of an image to be recorded. Determining a thinning rate of ink ejected from the recording head in at least one of the last scan and the second scan from the last of the reciprocating scans necessary to form one band. It is a feature.

  The invention according to claim 20 having such a configuration is characterized in that the recording is performed in at least one of the last scan and the second-to-last scan among the reciprocating scans necessary to form one band. The control unit determines the thinning rate of the ink ejected from the head according to the desired image quality selected by the selection setting means.

  The ejection amount of ink ejected in the last scan of each band has the most influence on the image quality when the recorded image is viewed. According to the first aspect of the invention, in the last scan, The ink to be ejected is randomly thinned out. For this reason, the ejected ink is randomly combined on the recording medium to prevent differences in the color tone and glossiness of the recorded image between the forward path and the backward path of the recording head moving in the main scanning direction. Thus, there is an effect that high-definition image recording can be performed.

  Further, since only the ink ejected in the last scan is thinned out, the ink amount of the entire image is not greatly reduced, and the density of the recorded image is not reduced. For this reason, it becomes possible to perform high-definition image recording by preventing only the difference in color tone and glossiness of the recorded image for each band.

  When performing many scans to form one band, most of the pixels are filled by the first few scans, so that the ink ejected in the second scan from the last as well as the last scan is randomly selected. Even if it is thinned out, the image quality is hardly affected. Then, after the pixels are almost filled, it is possible to prevent ink dots from being ejected as much as possible, thereby randomly connecting the ink dots and preventing differences in the color tone and glossiness of the recorded image. According to the second aspect of the present invention, the ink to be ejected is randomly thinned in both the last scan and the penultimate scan, so that the amount of ink to be thinned out in one scan is larger than that in the case of increasing the ink to be thinned out. As a result, it is possible to eject ink more uniformly, smooth the image surface, and perform high-definition image recording.

  The amount of ink ejected in the last scan of each band has the most influence on the image quality when the recorded image is viewed. According to the invention described in claim 3, according to the invention described in claim 3, The ink to be ejected is randomly thinned out. For this reason, the ejected ink is randomly combined on the recording medium to prevent differences in the color tone and glossiness of the recorded image between the forward path and the backward path of the recording head moving in the main scanning direction. Thus, there is an effect that high-definition image recording can be performed.

  Further, since only the ink ejected in the last scan is thinned out, the ink amount of the entire image is not greatly reduced, and the density of the recorded image is not reduced. For this reason, it becomes possible to perform high-definition image recording by preventing only the difference in color tone and glossiness of the recorded image for each band.

  When performing many scans to form one band, most of the pixels are filled by the first few scans, so that the ink ejected in the second scan from the last as well as the last scan is randomly selected. Even if it is thinned out, the image quality is hardly affected. Then, after the pixels are almost filled, it is possible to prevent ink dots from being ejected as much as possible, thereby randomly connecting the ink dots and preventing differences in the color tone and glossiness of the recorded image. According to the fourth aspect of the present invention, the ink to be ejected is randomly thinned in both the last scan and the penultimate scan, so that the amount of ink to be thinned out in one scan is larger than that in the case of increasing the ink to be thinned out. As a result, it is possible to eject ink more uniformly, smooth the image surface, and perform high-definition image recording.

  According to the invention described in claim 5, since the amount of ink ejected in the last scan is equal to or greater than the inter-dot distance between the ink dots that land adjacently and the dot diameter when landed on the recording medium, The effect that it is possible to perform high-definition image recording by preventing adjacent inks from being randomly ejected in the last scan from being combined and causing differences in color tone and glossiness of the recorded image. Play.

  When image recording is performed using photo-curing ink, when the recording head is located near the light irradiation device, the ink ejected onto the recording medium is immediately irradiated with light, so that the ink is landed immediately after landing. To harden. On the other hand, when the recording head is at a position away from the light irradiation device, the ink discharged onto the recording medium is not immediately irradiated with light, so that the ink spreads around the ink until it hardens after landing. Smooth. According to the sixth aspect of the present invention, for example, the recording operation with different image recording speeds is switched by determining the thinning-out rate of the ink to be ejected in the last scan in consideration of such ink curing timing. Even in an ink jet recording apparatus that can be used, high-definition image recording can be performed.

  When image recording is performed using a plurality of colors of ink, there are cases where there are differences in the ease of combining ink dots and the way of curing depending on the type of ink. According to the seventh aspect of the invention, since the thinning rate of ink to be ejected in the last scan is determined according to the type of ink, high-definition image recording can be performed corresponding to various inks. There is an effect.

  Since the recording medium has different ink absorption and surface energy depending on the type, the way the ink spreads after landing on the recording medium varies depending on the type of the recording medium. According to the eighth aspect of the invention, it is possible to appropriately adjust the ink thinning rate in accordance with the recording medium, and it is possible to perform high-definition image recording.

  When image recording is performed using photocurable ink, if the image recording speed is high, the ink ejected onto the recording medium is immediately irradiated with light, so that the ink is cured immediately after landing. On the other hand, when the image recording speed is low, the ink ejected onto the recording medium is not immediately irradiated with light, so that the ink spreads out and is smoothed before it is cured after landing. According to the ninth aspect of the present invention, for example, a recording operation with different image recording speeds is switched by determining a thinning rate of ink to be ejected in the last scan in consideration of such ink curing timing. Even in an ink jet recording apparatus that can be used, high-definition image recording can be performed.

  The degree of curing of the ink ejected on the recording medium varies depending on the light irradiation amount of the light irradiation device. If the light irradiation amount is large, the ink cures immediately after landing on the recording medium, but the light irradiation amount is small. The ink does not cure immediately after landing, but spreads around and smoothes out. According to the tenth aspect of the present invention, scanning required before ink curing is performed by determining the thinning rate of ink to be ejected in the last scanning in consideration of such a difference in ink curing. Even when the number of times is different, it is possible to appropriately cope with it, and there is an effect that high-definition image recording can always be performed.

  Ink is hard to cure when the temperature around the recording head is low or when the humidity is high, and it does not cure immediately after landing on the recording medium, but spreads around and smoothes, but when the temperature is high or the humidity is low Has the property of being easily cured. According to the eleventh aspect of the present invention, it is possible to perform high-definition image recording by determining the thinning-out rate of ink to be ejected in the last scan in consideration of such ink characteristics. Play.

  According to the twelfth aspect of the invention, the user can arbitrarily select an image quality such as a matte tone and a glossy tone while preventing a difference in color tone and glossiness of an image for each band. As a result, high-definition image recording can be performed, and an image with desired image quality can be obtained.

  According to the thirteenth aspect of the invention, the dot diameter when the ink discharge amount discharged in at least one of the last scan and the second scan from the last is landed on the recording medium is adjacent. Since the distance between the ink dots and the landed ink dots is not less than the distance between adjacent dots, adjacent inks among the inks randomly ejected in the last scan or the second scan from the last are combined, and the color tone and glossiness of the recorded image are combined. Thus, it is possible to prevent the difference from occurring and to perform high-definition image recording.

  When image recording is performed using photo-curing ink, when the recording head is located near the light irradiation device, the ink ejected onto the recording medium is immediately irradiated with light, so that the ink is landed immediately after landing. To harden. On the other hand, when the recording head is at a position away from the light irradiation device, the ink discharged onto the recording medium is not immediately irradiated with light, so that the ink spreads around the ink until it hardens after landing. Smooth. According to the fourteenth aspect of the present invention, the ink thinning rate to be ejected in the last scan or the second to last scan is determined in consideration of such ink curing timing, for example, image recording. Even in an ink jet recording apparatus capable of switching recording operations at different speeds, there is an effect that high-definition image recording can be performed.

  When image recording is performed using a plurality of colors of ink, there are cases where there are differences in the ease of combining ink dots and the way of curing depending on the type of ink. According to the fifteenth aspect of the present invention, since the thinning rate of ink to be ejected in the last scan or the second scan from the last is determined according to the type of ink, high-definition corresponding to various inks can be obtained. There is an effect that image recording can be performed.

  Since the recording medium has different ink absorption and surface energy depending on the type, the way the ink spreads after landing on the recording medium varies depending on the type of the recording medium. According to the sixteenth aspect of the present invention, the ink thinning rate can be appropriately adjusted according to the recording medium, and an effect is achieved that high-definition image recording can be performed.

  When image recording is performed using photocurable ink, if the image recording speed is high, the ink ejected onto the recording medium is immediately irradiated with light, so that the ink is cured immediately after landing. On the other hand, when the image recording speed is low, the ink ejected onto the recording medium is not immediately irradiated with light, so that the ink spreads out and is smoothed before it is cured after landing. According to the seventeenth aspect of the present invention, the ink thinning rate to be ejected in the last scan or the second scan from the last is determined in consideration of such ink curing timing, for example, image recording. Even in an ink jet recording apparatus capable of switching recording operations at different speeds, there is an effect that high-definition image recording can be performed.

  The degree of curing of the ink ejected on the recording medium varies depending on the light irradiation amount of the light irradiation device. If the light irradiation amount is large, the ink cures immediately after landing on the recording medium, but the light irradiation amount is small. The ink does not cure immediately after landing, but spreads around and smoothes out. According to the invention described in claim 18, the ink curing is determined by determining the thinning-out rate of the ink ejected in the last scan or the second scan from the last in consideration of the difference in the degree of curing of the ink. Even when the number of scans required so far is different, it is possible to cope with it appropriately, and it is possible to always perform high-definition image recording.

  Ink is hard to cure when the temperature around the recording head is low or when the humidity is high, and it does not cure immediately after landing on the recording medium, but spreads around and smoothes, but when the temperature is high or the humidity is low Has the property of being easily cured. According to the nineteenth aspect of the present invention, high-definition image recording is performed by determining the thinning-out rate of ink ejected in the last scan or the second scan from the last in consideration of such ink characteristics. There is an effect that can be performed.

  According to the invention described in claim 20, the user can arbitrarily select an image quality such as a matte tone or a glossy tone while preventing a difference in color tone or glossiness of an image for each band. As a result, high-definition image recording can be performed, and an image with desired image quality can be obtained.

  The first embodiment of the ink jet recording apparatus according to the present invention will be described below with reference to FIGS.

  First, as shown in FIG. 1, in the present embodiment, an inkjet recording apparatus 1 is an inkjet recording apparatus 1 of a serial printing method, and the inkjet recording apparatus 1 is formed in a flat plate shape and a recording medium P is not used. A platen 2 that supports the recording surface is provided.

  Above the platen 2, a rod-shaped guide rail 3 extending in the longitudinal direction of the platen 2 is provided. A carriage 4 is supported on the guide rail 3, and the carriage 4 can be reciprocally scanned in the main scanning directions A and B along the guide rail 4 by a carriage driving mechanism 11 (see FIG. 2) as a head scanning unit. It has become.

  Further, the inkjet recording apparatus 1 includes a recording medium transport mechanism 12 (see FIG. 2) that is configured by a plurality of transport rollers 5 and the like, and that feeds the recording medium P in the transport direction X orthogonal to the main scanning directions A and B. Is provided. The recording medium transport mechanism 12 rotates the transport roller 5 to repeat transport and stop of the recording medium P in accordance with the operation of the carriage 4 during image recording, and the recording medium P is transported from the upstream side in the transport direction X. It is conveyed intermittently downstream.

  As shown in FIG. 1, the carriage 4 corresponds to each color (black (K), cyan (C), magenta (M), yellow (Y)) used in the inkjet recording apparatus 1 in the present embodiment. Four recording heads 6 are mounted. The recording heads 6 are formed in a substantially rectangular parallelepiped shape, and are arranged side by side so that their longitudinal directions are parallel to each other. A surface of the recording head 6 facing the recording medium P is provided with a plurality of ink ejection ports (not shown) formed in a line along the longitudinal direction of the recording head 6. Ink is discharged from each outlet. The ink used in the inkjet recording apparatus 1 is not limited to this, and for example, colors such as light yellow (LY), light magenta (LM), and light cyan (LC) can be used. In this case, a recording head corresponding to each color is mounted on the carriage.

  Further, a temperature / humidity sensor (see FIG. 2) is provided in the vicinity of the recording head 6 as temperature / humidity measuring means for measuring the temperature and humidity around the recording head 6. The temperature / humidity sensor includes, for example, a polymer resistance humidity sensor including a thermistor as a temperature detection element and a humidity detection element, and detects the ambient temperature / humidity around the recording head 6. The temperature / humidity measuring means is not limited to the one exemplified here, and other configurations may be applied.

  Between the recording head 6 provided adjacent to the side wall of the carriage 4 in the recording head 6 and both side walls of the carriage 4, an ultraviolet irradiation device 7 as a light irradiation device is disposed.

  The ultraviolet irradiation device 7 has an ultraviolet light source (not shown) that irradiates ultraviolet rays as light for curing and fixing the ink ejected and landed on the recording medium P. As this ultraviolet light source, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a semiconductor laser, a cold cathode tube, an excimer lamp, or an LED (Light Emitting Diode) can be applied.

  Further, an ultraviolet sensor (see FIG. 2) is provided in the vicinity of the ultraviolet irradiation device 7 as an irradiation intensity measuring means for measuring the irradiation intensity of ultraviolet rays emitted from the ultraviolet irradiation device 7. An ultraviolet sensor detects light illuminance by receiving light with a light receiving unit including a silicon sensor and an optical filter, for example. The irradiation intensity measuring means is not limited to those exemplified here, and other configurations may be applied.

  The ink used in the present embodiment is a photocurable ink having a property of being cured when irradiated with ultraviolet rays as light, and has at least a polymerizable compound (including a known polymerizable compound) as a main component. And a photoinitiator and a coloring material. The photocurable ink is roughly classified into a radical polymerization ink containing a radical polymerizable compound as a polymerizable compound and a cationic polymerization ink containing a cationic polymerizable compound. Both inks are included in this embodiment. Each can be applied as an ink to be used. Further, a hybrid ink in which a radical polymerization ink and a cation polymerization ink are combined may be applied as the ink used in this embodiment. However, since cationic polymerization inks that have little or no inhibitory action on polymerization reaction due to oxygen are superior in functionality and versatility, it is particularly preferable to use cationic polymerization inks. The cationic polymerization ink is a mixture containing at least a cationic polymerizable compound such as an oxetane compound, an epoxy compound, and a vinyl ether compound, a photocationic initiator, and a coloring material.

  Further, as the recording medium P, recording paper P made of various materials such as various papers such as plain paper, recycled paper, glossy paper, various fabrics, various non-woven fabrics, resin, metal, and glass can be applied. In addition, as the form of the recording medium P, various forms such as a roll form, a cut sheet form, and a plate form are applicable.

  Next, the control configuration of the ink jet recording apparatus 1 in the present embodiment will be described with reference to FIGS. 2 to 6.

  As shown in FIG. 2, the inkjet recording apparatus 1 is provided with a control unit 8 for controlling each part of the apparatus. The control unit 8 includes, for example, a CPU (Central Processing Unit) (not shown) and various types. A storage unit 9 including a ROM (Read Only Memory) for storing the processing program and the like, a RAM (Random Access Memory) for temporarily storing various data such as image data, and the like. The control unit 8 develops the processing program recorded in the ROM in the work area of the RAM and executes the processing program by the CPU.

  Further, the inkjet recording apparatus 1 has an input unit 10 for inputting the type of the recording medium P, image recording conditions, and the like, and information input from the input unit 10 is sent to the control unit 12. Yes. The input unit 10 is, for example, a keyboard or an operation panel, and the user operates the input unit 10 to select and set various recording conditions such as a recording medium P used for image recording and a desired image recording speed and resolution. Can be done.

  The control unit 8 is sent with measurement results measured by the temperature / humidity sensor 13 and the ultraviolet sensor 14, and the control unit 8 controls each unit based on the sent results. It has become.

  The control unit 8 controls the carriage driving mechanism 11 to reciprocate the carriage 4 in the main scanning directions A and B, and intermittently conveys the recording medium P in the conveyance direction X in accordance with the operation of the carriage 4. The operation of the recording medium transport mechanism 12 is controlled.

  Furthermore, image data related to a recorded image is sent to the control unit 8 from an external device (not shown). The control unit 8 is based on the sent image data, information input from the input unit 10, and the like. Then, the recording head 6 is operated. As a result, ink of an appropriate thinning rate is ejected from each recording head 6 and a predetermined image is recorded on the recording medium P.

  Here, the ink thinning rate is the number of ejection ports from which the ink is not ejected from the ejection ports of the recording head 6 with respect to the number of ejection ports of the recording head 6, and the control unit 8 performs each recording so as to eject ink of the determined thinning rate. The number of ejection ports ejected from the head 6 is adjusted.

  The control unit 8 controls the ultraviolet irradiation device 7 to irradiate the ink ejected on the recording medium P with ultraviolet rays.

  Here, control of the ink discharge amount by the control unit 8 in the present embodiment will be described.

  FIG. 3 is a diagram showing corresponding portions of the recording head 6 that performs image formation of each band when attention is focused on one recording head 6. As shown in FIG. 3, the feeding width of the recording medium P conveyed by one conveyance is called one band, and in this embodiment, image recording is performed by scanning one band three times. Yes. That is, for example, in the uppermost band of the recording medium in FIG. 3, the first scan is performed along the main scanning forward direction A, and the first scan image recording is performed by the ink ejected from one end side of the recording head 6. Done. Then, the second scanning is performed along the main scanning backward direction B, and the second scanning image recording is performed by the ink ejected from the substantially central portion of the recording head 6. Further, the third scan is performed again along the main scanning forward direction A, and the image of the third scan is performed by the ink ejected from the other end of the recording head 6, whereby all the pixels in one band are recorded. Recording is complete.

  The control unit applies ink to a portion of each ink ejection port of the recording head 6 that is recorded in the last scan in each band so that ink ejection in the last scan among the three scans is randomly thinned out. The recording head 6 is controlled so that ink is not randomly ejected from the ink ejection ports that eject the ink. The ink discharge amount is preferably such that the dot diameter when the ink lands on the recording medium P is equal to or greater than the inter-dot distance between the ink dots that land adjacently. By doing in this way, it can be ensured that the ink ejected in the last scan overlaps or is combined with the adjacent ink.

  Next, specific pixels to which the ink ejected at random is thinned out will be described with reference to FIG. FIG. 4A shows, as a dot matrix, the number of scans at which ink is ejected to each pixel when the head resolution and the image resolution are the same and one band is recorded by three scans. One row in the horizontal direction represents one band. Each square in the figure represents one pixel, and the numbers from 1 to 3 indicate how many times the ink is ejected for each pixel. For example, in FIG. 4A, when recording the band in the first column, the leftmost pixel (pixel 1 in the figure) in FIG. 4A is recorded in the first scan, and the second scan and the third scan. The pixels 2 and 3 are recorded in order by eye. Further, when recording the band in the second row, the second scan is the first scan in the recording of the band in the first row, and is counted from the first scan in the band in the first row. Each band is recorded while the scan for starting image recording is shifted by one scan so that the scan to be scanned is the third scan.

  When recording is performed in this way, the portion indicated by the oblique lines in FIG. 4A, that is, the ink ejection in the third scan, which is the last scan for recording each band, is randomly thinned out. ing.

  Note that the number of scans required to record one band is not limited to three. For example, one band may be formed by six scans. The ejection of ink ejected in the sixth scan, which is the scan, is randomly thinned out. For example, in the case where the main scanning is performed in six times and the image resolution is twice the head resolution, a dot matrix indicating at which scan ink is ejected to each pixel is shown in FIG. As shown in b). In FIG. 4B, two horizontal columns represent one band, and each square in the figure represents one pixel. The numbers from 1 to 6 indicate the number of scans for which ink is ejected for each pixel, and the control unit performs ink ejection in the sixth scan, which is the last scan for recording each band. It is designed to thin out at random.

  Next, how much the ink thinning rate is set depends on the dot diameter when the ink ejected in the last scan for landing to form one band and how much the dot diameter increases after landing. . The size of the dot diameter when landed on the recording medium P and the extent to which the dot diameter increases after landing are determined by the type of the recording medium P, the degree of curing of the ink that has landed first, the irradiation timing of ultraviolet rays, that is, the ink It varies depending on the time from ejection to irradiation with ultraviolet rays, the type of ink, the irradiation intensity of ultraviolet rays irradiated from the ultraviolet irradiation device 7, the ambient temperature and humidity around the recording head 6, and the like. In order to perform high-definition image formation while suppressing variations in color tone, glossiness, etc. for each band, the ink thinning rate in the last scan for recording each band is determined so that the ink is randomly distributed on the recording medium P. Since the combined amount is preferable, the thinning rate of ink ejected from the recording head 6 in the last scan is determined by the relationship between the dot diameter when landed and the degree of enlargement of the dot diameter after landing.

  First, as shown in FIG. 5, the ink has a difference in dot diameter after landing depending on the state of the ink that has landed first. When the ink that has landed first is uncured or in a semi-cured state, even if ink is ejected onto it, the dot diameter is small, whereas the ink that has landed first When the ink is sufficiently cured, the ink dot diameter tends to increase when ink is ejected onto the ink.

  Further, as shown in FIG. 6, the ink has a difference in dot diameter after landing depending on the ink absorbability of the landing recording medium P and the surface energy. For example, when landing on a recording medium P having a small surface energy such as OPP (stretched polypropylene), the dot diameter of the ink tends to increase on the recording medium P. On the other hand, when landing on the recording medium P having a relatively large surface energy such as YUPO, the ink dot diameter tends to be smaller on the recording medium P.

  Therefore, when the dot diameter of the ink increases depending on the degree of curing of the ink that has landed first and the type of the recording medium P, the control unit 8 compares it with the case where the ink dot diameter is reduced. The ink thinning rate discharged from the recording head 6 is increased.

  Next, as shown in FIGS. 5 and 6, generally, the dot diameter of the ink tends to increase as the irradiation timing is delayed. The irradiation timing depends on the distance between each recording head 6 and the ultraviolet irradiation device 7 and the speed of image recording. That is, for example, when ink is ejected from the recording head 6 located near the ultraviolet irradiation device 7 such as yellow (Y) or black (K) in FIG. 1, the ultraviolet rays are emitted immediately after the ink is ejected. In contrast, when ink is ejected from the recording head 6 at a position distant from the ultraviolet irradiation device 7 such as cyan (C) or magenta (M), the ultraviolet rays are emitted after the ink is ejected. It takes time to irradiate and the irradiation timing is delayed. Further, as the ink is ejected from the recording head 6 located on the downstream side in the moving direction of the carriage 4, it takes more time from the ejection of the ink to the irradiation of ultraviolet rays, and the irradiation timing is delayed. Furthermore, when the image recording speed is high, the moving speed of the carriage 4 on which the recording head 6 is mounted increases, so that the irradiation timing is advanced. Conversely, when the image recording speed is low, Since the moving speed of the carriage 4 on which the recording head 6 is mounted becomes slow, the irradiation timing becomes slow. When the irradiation timing is delayed, the ink that has landed on the recording medium P spreads until the ultraviolet ray is irradiated and the dot diameter increases, so the control unit 8 increases the ink as the irradiation timing is delayed. The recording head 6 is controlled to increase the thinning rate.

  In addition, when the ink is of a type in which the dot diameter is easy to expand or is hard to cure, adjacent ink dots are likely to be combined. Therefore, for the ink having such a property, the control unit 8 is configured to increase the ink thinning rate in the last scan of each band as compared with other types of ink.

  Further, the ink is more easily cured as the amount of ultraviolet light applied to the ink landed on the recording medium P increases. This amount of ultraviolet light is the product of the irradiation intensity irradiated from the ultraviolet irradiation device 7 and the irradiation time. . Therefore, even when the ultraviolet rays are irradiated at the same irradiation timing, the ink is more easily cured and the dot diameter is smaller as the irradiation intensity of the ultraviolet rays emitted from the ultraviolet irradiation device 7 is higher. For this reason, the control unit 8 is configured to increase the ink thinning rate in the last scan of each band as the irradiation intensity decreases based on the irradiation intensity of the ultraviolet rays detected by the ultraviolet sensor 14.

  Further, the ink has a characteristic that it is easily cured at high temperature and low humidity, and is difficult to cure at low temperature and high humidity. Therefore, based on the ambient temperature and humidity around the recording head 6 detected by the temperature and humidity sensor 13, the control unit 8 determines the ink in the last scan of each band when the ambient temperature and humidity are low temperature and high humidity. The decimation rate is reduced.

  The storage unit 9 of the control unit 8 stores, for example, an ink thinning rate correction table for determining the amount of ink discharged from the recording head 6 for each element that influences the degree of ink curing as described above (see FIG. (Not shown) is stored, and the control unit 8 determines the ink thinning rate to be ejected from the recording head 6 while referring to the ink thinning rate correction table.

  Next, the operation of this embodiment will be described.

  When image data input from an external device (not shown) is sent to the inkjet recording apparatus 1, the sent image data is stored in the storage unit 9 of the control unit 8. When the user inputs a signal for starting image recording, the type of the recording medium P, various image recording conditions, and the like from the input unit 10, and the result detected by the temperature / humidity sensor 13 and the ultraviolet sensor 14 is sent. The control unit 8 reads the ink thinning rate correction table from the storage unit 9 and scans necessary for forming one band so as to meet various conditions such as the input information and the results detected by various sensors. The ink thinning rate in the last scan is determined.

  When the ink thinning rate in the last scan among the scans necessary for forming one band is determined, the number of scans for recording one band, the image resolution with respect to the resolution of the recording head 6, etc. It is determined which part of the ink is to be thinned out to the ink discharge port of the head 6. Note that the determination of the ink thinning rate and the determination of which portion of ink to be thinned out to the ink discharge port in the last scan are not limited to the case where they are determined in the order illustrated here, and may be determined simultaneously, for example. .

  When the ink thinning rate or the like is determined, the control unit 8 controls the recording medium conveyance mechanism 12 so that the recording medium P is sequentially conveyed intermittently from the upstream side to the downstream side in the conveyance direction X. The control unit 8 controls the carriage driving mechanism 11 to reciprocate the carriage 4 on the recording medium P along the main scanning forward path direction A and the main scanning backward direction B, and the control unit 8 controls each recording head. By controlling 6, a predetermined ejection amount of ink is ejected to a predetermined pixel. The ink ejected onto the recording medium P is irradiated with ultraviolet rays from the ultraviolet irradiation device 7, whereby the ink is cured and fixed, and an image is recorded on the recording medium P.

  As described above, according to the present embodiment, the irradiation timing from when the ink is ejected to when the ultraviolet ray is irradiated, the type of the recording medium P used for ink or image recording, the irradiation intensity of the ultraviolet ray, the environment around the recording head. The ink discharge in the last scan among the scans necessary to form one band is randomly thinned according to various conditions such as temperature and humidity, so the color tone and gloss for each band that most affect the image quality of the recorded image It is possible to perform high-definition image recording with little difference in feeling.

  In the present embodiment, the distance between the recording head 6 and the ultraviolet irradiation device 7, the image recording speed, the type of ink, the type of the recording medium P, the irradiation intensity of the ultraviolet rays irradiated from the ultraviolet irradiation device 7, and the environmental temperature. In consideration of all the factors such as humidity, it was decided to determine the ink thinning rate to be ejected from the recording head 6 in the reciprocating scanning necessary for forming one band. The ink thinning rate may be determined based on any one or more elements. In this case, for example, when the irradiation intensity of the ultraviolet rays irradiated from the ultraviolet irradiation device 7 is not considered, it is not necessary to provide the ultraviolet sensor 14. Further, when the environmental temperature and humidity are not taken into consideration, it is not necessary to provide the temperature and humidity sensor 13, and the apparatus configuration can be simplified.

  In this embodiment, each control unit 8 causes the carriage 4 to reciprocate in the main scanning directions A and B by the carriage driving mechanism 11 and operates the recording head 7 to discharge predetermined ink. However, the control configuration is not limited to that illustrated here. For example, a control unit that causes the carriage to reciprocate in the main scanning direction and a recording head are operated by a carriage driving mechanism to operate a predetermined ink. You may make it provide separately the control part which controls discharge of this.

  Further, in the present embodiment, the ultraviolet irradiation device 7 is arranged on both sides of the recording heads 6 provided in a group. However, the arrangement of the ultraviolet irradiation devices 7 is not limited to this, and between the recording heads 6. In addition, each may be provided with an ultraviolet irradiation device 7. The ultraviolet irradiation device 7 is not limited to being mounted on the carriage 4 and may be provided outside the carriage 4.

  In this embodiment, image recording is performed using ink that is cured by irradiation with ultraviolet rays. However, the ink is not necessarily limited to this, and for example, ultraviolet rays, electron beams, X-rays, and visible rays. The ink may be cured by irradiating light other than ultraviolet rays such as electromagnetic waves such as infrared rays. In this case, a polymerizable compound that is polymerized and cured with light other than ultraviolet light and a photoinitiator that initiates a polymerization reaction between the polymerizable compounds with light other than ultraviolet light are applied to the ink. In the case of using a photocurable ink that is cured by light other than ultraviolet light, a light source that emits the light is applied instead of the ultraviolet light source.

  The recording head 6 used in the ink jet recording apparatus 1 according to the present invention may be an on-demand system or a continuous system. In addition, as a discharge method, for example, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, , Thermal ink jet type, bubble jet (registered trademark) type), electrostatic suction type (for example, electric field control type, slit jet type, etc.) and discharge type (for example, spark jet type, etc.) May be used.

  In addition, it is needless to say that the present invention is not limited to the above embodiment and can be modified as appropriate.

  Next, a second embodiment of the ink jet recording apparatus according to the present invention will be described. Since the second embodiment is different from the first embodiment only in the control configuration, the following description will focus on differences from the first embodiment.

  In the present embodiment, the ink jet recording apparatus includes a recording head and an ultraviolet irradiation device (not shown) similar to those in the first embodiment, and a control unit having a storage unit that stores various programs and the like (both are all). (Not shown). As in the first embodiment, detection results are sent from the temperature / humidity sensor and ultraviolet sensor to the control unit, and the control unit adjusts the ink thinning rate to be ejected from the recording head based on these results. It is like that.

  In particular, in the present embodiment, the control unit discharges from the print head both during the last scan and during the second scan from the last of the reciprocating scans necessary to form one band. As in the first embodiment, the controller controls the distance between the recording head and the ultraviolet irradiation device, the image recording speed, the type of ink, the type of recording medium, and the ultraviolet rays. Based on the irradiation intensity of ultraviolet rays emitted from the irradiation device and various conditions of environmental temperature and humidity, the thinning rate of ink ejected in the last scan and the thinning rate of ink ejected in the second scan from the last are determined. It has become. In this case, in order to ensure that the ink ejected in the last scan and the second scan from the last overlaps or is combined with the adjacent ink dots, the dots when the inks land on the recording medium are used. It is preferable that the diameter be equal to or greater than the inter-dot distance between the ink dots that land adjacently.

  As in the first embodiment, the storage unit of the control unit stores, for example, an ink thinning rate correction table (determining the ejection amount of ink ejected from the recording head for each of the various conditions as described above). (Not shown) is stored, and the control unit determines the ink thinning rate to be ejected from the recording head while referring to the ink thinning rate correction table. Note that the ink thinning rate correction table may be prepared for each of the last scan and the second to last scan, or one table in which both are associated may be prepared. Good.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Next, the operation of this embodiment will be described.

  When image data input from an external device (not shown) is sent to the ink jet recording apparatus, the sent image data is stored in the storage unit of the control unit. As in the case of the first embodiment, the control unit reads out the ink thinning rate correction table from the storage unit, and adjusts one band so as to conform to various conditions such as various information and results detected by various sensors. Among the scans necessary for forming the ink, the ink thinning rate in the last scan and the second scan from the last is determined.

  When the ink thinning rate in the last scan and the second scan from the last of the scans necessary to form one band is determined, how many scans are recorded in one band and the image resolution relative to the resolution of the recording head. The number of ink to be thinned out to the ink discharge port of the recording head is determined by several factors.

  When the ink thinning rate or the like is determined, the control unit controls the recording medium conveyance mechanism, whereby the recording medium P is intermittently conveyed from the upstream side to the downstream side in the conveyance direction. The control unit controls the carriage driving mechanism to reciprocate the carriage on the recording medium along the main scanning direction, and the control unit controls each recording head to supply a predetermined amount of ink. This is discharged to the pixels. The ink ejected onto the recording medium is irradiated with ultraviolet rays from an ultraviolet irradiation device, whereby the ink is cured and fixed, and an image is recorded on the recording medium.

  As described above, according to the present embodiment, the irradiation timing from when the ink is ejected to when the ultraviolet ray is irradiated, the type of the recording medium used for ink or image recording, the irradiation intensity of the ultraviolet ray, the environmental temperature around the recording head. Since the ink thinning rate in the last scan and the second to last scan among the scans necessary to form one band is changed depending on various conditions such as humidity, one band that most affects the image quality of the recorded image. Therefore, it is possible to perform high-definition image recording with little difference in color tone and glossiness.

  In this embodiment, the ink thinning rate discharged from the recording head is determined in both the last scanning and the second scanning from the last, but the ink thinning rate in both scannings is the same amount. Alternatively, the ink thinning rate discharged from the print head in the last scan may be larger than the ink thinning rate discharged from the print head in the second scan from the last. Since the last scan affects the image quality of the recorded image, the ink thinning rate in the last scan is the same as the ink thinning rate in the second scan from the last, or in the last scan. It is preferable to increase the ink thinning rate step by step so that the ink thinning rate becomes smaller.

  Note that the present invention is not limited to the present embodiment, as in the first embodiment.

  Next, a third embodiment of the ink jet recording apparatus according to the present invention will be described. Note that the third embodiment differs from the first embodiment only in part of the apparatus configuration and the control configuration, and therefore, in the following, differences from the first embodiment will be particularly described.

  In the present embodiment, the ink jet recording apparatus includes a recording head and an ultraviolet irradiation device (not shown) similar to those in the first embodiment, and a control unit having a storage unit that stores various programs and the like (both are all). (Not shown). As in the first embodiment, detection results are sent from the temperature / humidity sensor and ultraviolet sensor to the control unit, and the control unit adjusts the amount of ink discharged from the recording head based on these results. It is like that.

  In particular, in the present embodiment, it is possible to select a desired image quality from an input unit (not shown), and the control unit is necessary for forming one band so as to achieve the selected image quality. Among the reciprocating scans, in the last scan, the ink thinning rate discharged from the recording head is increased, and as in the first embodiment, the control unit is configured such that the distance between the recording head and the ultraviolet irradiation device, Based on various conditions such as image recording speed, ink type, recording medium type, UV irradiation intensity from UV irradiation device, and environmental temperature and humidity, the thinning rate of ink to be ejected in the last scan is determined. It has become.

  That is, if the ink dots land on the recording medium and then cure independently without being bonded to each other, the reflected light tends to scatter on the surface of the recorded image, so that a matte-quality image with no glossiness can be obtained. it can. On the other hand, when the ink dots are combined with each other, the surface of the recorded image is smoothed, and a glossy and glossy image can be obtained. Therefore, when the matte tone is selected as the desired image quality, the control unit increases the thinning rate of ink to be ejected in the last scan so that the number of places where the ink dots are combined with each other is small. On the other hand, when the glossy tone is selected as the desired image quality, it is necessary to combine the ink dots to some extent. Therefore, the control unit sets the ink to be ejected in the last scan compared to when the matte tone is selected. The thinning rate is reduced.

  The storage unit of the control unit stores, for example, an ink thinning rate correction table for determining the thinning rate of ink ejected from the recording head for each of various conditions such as image recording speed and ink type and desired image quality (see FIG. (Not shown) is stored, and the control unit determines the ink thinning rate to be ejected from the recording head while referring to the ink thinning rate correction table.

  In addition, since the other structure is the same as that of 1st embodiment and 2nd embodiment, the description is abbreviate | omitted.

  Next, the operation of this embodiment will be described.

  When image data input from an external device (not shown) is sent to the ink jet recording apparatus, the sent image data is stored in the storage unit of the control unit. Furthermore, desired image quality such as matte tone and gloss tone is selected and input from the input unit. As in the case of the first embodiment, the control unit reads the ink thinning rate correction table from the storage unit and conforms to various conditions such as various information, results detected by various sensors, and the selected image quality. Thus, the ink thinning rate in the last scan among the scans necessary to form one band is determined.

  When the ink thinning rate in the last scan among the scans necessary to form one band is determined, the number of scans for recording one band, the number of image resolutions relative to the resolution of the print head, etc. It is determined which part of the ink is to be thinned out to the ink discharge port.

  When the ink thinning rate or the like is determined, the control unit controls the recording medium conveyance mechanism, so that the recording medium is sequentially intermittently conveyed from the upstream side to the downstream side in the conveyance direction. The control unit controls the carriage driving mechanism to reciprocate the carriage on the recording medium along the main scanning direction, and the control unit controls each recording head to supply a predetermined amount of ink. This is discharged to the pixels. The ink ejected onto the recording medium is irradiated with ultraviolet rays from an ultraviolet irradiation device, whereby the ink is cured and fixed, and an image is recorded on the recording medium.

  As described above, according to the present embodiment, the irradiation timing from when the ink is ejected to when the ultraviolet ray is irradiated, the type of the recording medium used for ink or image recording, the irradiation intensity of the ultraviolet ray, the environmental temperature around the recording head. Since the ink thinning rate in the last scan among the scans necessary to form one band is changed according to various conditions such as humidity, the difference in glossiness for each band that most affects the image quality of the recorded image Therefore, high-definition image recording can be performed.

  Furthermore, since the ink thinning rate is adjusted according to the desired image quality, the user can arbitrarily select a matte tone image or a glossy image, and obtain an image with desired image quality.

  In this embodiment, among the reciprocating scans necessary to form one band, the thinning-out rate of ink ejected from the recording head is increased only during the last scan. Similarly, the ink thinning rate ejected from the print head may be increased both in the last scan and in the second scan from the last.

1 is a top view illustrating a configuration of a main part of a first embodiment of an ink jet recording apparatus according to the present invention. It is a principal block diagram showing an outline of a control configuration of the first embodiment of the ink jet recording apparatus according to the present embodiment. FIG. 6 is a diagram illustrating a corresponding portion of a recording head that performs image formation of each band. FIG. 4A shows a dot matrix in the case where one band image recording is performed by three main scans when the head resolution and the image resolution are the same. FIG. 4B shows a dot matrix in the case where one band image recording is performed by six main scans when the image resolution is twice the head resolution. It is the graph which showed the relationship between an ink dot diameter and irradiation timing according to the hardening state of the ink. 3 is a graph showing the relationship between ink dot diameter and irradiation timing for each recording medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 6 Recording head 7 Ultraviolet irradiation device 8 Control part 9 Storage part P Recording medium A Main scanning forward direction B Main scanning backward direction X Conveyance direction

Claims (20)

The recording head is reciprocally scanned a plurality of times, and photocurable ink is ejected from the recording head onto the recording medium. Light is irradiated from a light source irradiation device, and the ink is cured and fixed to form one band. In the image recording method,
An image recording method, wherein ink is ejected at random from the recording head during the last scanning of the reciprocating scanning forming the one band. The image recording method according to claim 1,
An image recording method, wherein ink is ejected at random from the recording head during the second scanning from the end of the reciprocating scanning forming the one band. A recording head for discharging a photocurable ink that is cured by irradiating light onto a recording medium;
A light irradiation device comprising a light source for irradiating the ejected ink with light;
Head scanning means for reciprocatingly scanning the recording head in a direction orthogonal to the conveyance direction of the recording medium;
In the last scan of the reciprocating scan necessary for forming one band when scanning and recording the head scanning means so as to form one band by reciprocating the recording head a plurality of times, An ink jet recording apparatus comprising: a control unit that controls the recording head so that ink ejected from the recording head is thinned out randomly.   The control unit controls the recording head to randomly thin out ink ejected from the recording head in a second scan from the end of a reciprocating scan necessary for forming one band. The ink jet recording apparatus according to claim 3.   In the last scanning of the reciprocating scanning necessary for forming one band, the control unit determines that the ink ejection amount ejected from the recording head is the ink that has the dot diameter landed adjacent to the recording medium. The inkjet recording apparatus according to claim 3, wherein the recording head is controlled so as to be equal to or longer than a distance between dots. A plurality of the recording heads are arranged,
The control unit determines a thinning rate of ink ejected from the recording head in the last scanning of the reciprocating scanning necessary for forming one band according to the distance between the recording head and the light irradiation device. The ink jet recording apparatus according to claim 3, wherein the ink jet recording apparatus is provided. A plurality of the recording heads are arranged for each color ink,
The control unit determines a thinning-out rate of ink ejected from the recording head in a final scan of a reciprocating scan necessary for forming one band according to the type of ink. The ink jet recording apparatus according to any one of claims 3, 5, and 6.   The control unit determines a thinning-out rate of ink ejected from the recording head in the last scan of the reciprocating scan necessary for forming one band according to the type of the recording medium. The ink jet recording apparatus according to any one of claims 3 and 5 to 7.   The control unit determines a thinning-out rate of ink ejected from the recording head in the last scanning of reciprocating scanning necessary for forming one band according to an image recording speed at the time of image recording. An ink jet recording apparatus according to any one of claims 3 and 5 to 8. Comprising irradiation intensity measuring means for measuring the irradiation intensity of the light irradiated from the light irradiation device;
The control unit determines a thinning rate of ink ejected from the recording head in the last scan of the reciprocating scan necessary for forming one band according to the irradiation intensity measured by the irradiation intensity measuring unit. The inkjet recording apparatus according to claim 3, wherein the inkjet recording apparatus is determined. Temperature / humidity measuring means for measuring at least one of temperature and humidity around the recording head;
In the last scan of the reciprocating scan necessary for forming one band according to at least one of the temperature and humidity around the recording head measured by the temperature and humidity measuring means, The ink jet recording apparatus according to claim 3, wherein a thinning rate of ink ejected from the recording head is determined.   The control unit determines a thinning rate of ink ejected from the recording head in the last scanning of the reciprocating scanning necessary to form one band according to a desired image quality of the recorded image. The ink jet recording apparatus according to claim 3, wherein the ink jet recording apparatus is characterized.   The controller controls the amount of ink ejected from the recording head in at least one of the last scanning and the second scanning from the last of the reciprocating scanning necessary for forming one band. The inkjet recording apparatus according to claim 4, wherein the recording head is controlled so that a dot diameter when landing on a medium is equal to or greater than a distance between dots with adjacent ink dots. A plurality of the recording heads are arranged,
The control unit includes at least one of a last scan and a second scan from the last in a reciprocating scan necessary for forming one band according to a distance between the recording head and the light irradiation device. The ink jet recording apparatus according to claim 4 or 13, wherein a thinning rate of ink ejected from the recording head in scanning is determined. A plurality of the recording heads are arranged for each color ink,
The control unit is ejected from the recording head in at least one of the last scanning and the second scanning from the last of the reciprocating scanning necessary for forming one band according to the type of ink. The ink jet recording apparatus according to claim 4, wherein the ink thinning rate is determined.   In accordance with the type of the recording medium, the control unit performs the operation from the recording head in at least one of the last scanning and the second scanning from the last of the reciprocating scanning necessary to form one band. 16. The ink jet recording apparatus according to claim 4, wherein a thinning rate of the ejected ink is determined.   The control unit, in at least one of the last scan and the second scan from the end of the reciprocating scan necessary for forming one band, according to the image recording speed at the time of image recording, The ink jet recording apparatus according to any one of claims 4 and 13, wherein a thinning rate of ink ejected from the recording head is determined. Comprising irradiation intensity measuring means for measuring the irradiation intensity of the light irradiated from the light irradiation device;
The control unit is at least one of a last scan and a second scan from the last required for forming one band according to the irradiation intensity measured by the irradiation intensity measuring unit. 18. The ink jet recording apparatus according to claim 4, wherein a thinning rate of ink ejected from the recording head in the scanning is determined. Temperature / humidity measuring means for measuring at least one of temperature and humidity around the recording head;
The control unit includes a last scan of a reciprocating scan necessary for forming one band according to at least one of a temperature and a humidity around the recording head measured by the temperature / humidity measuring unit, and 19. The thinning-out rate of ink ejected from the recording head in at least one of the second to last scans is determined. 2. An ink jet recording apparatus according to 1.   The control unit performs the scanning in at least one of the last scanning and the second scanning from the last of the reciprocating scanning necessary to form one band according to the desired image quality of the recorded image. 20. The ink jet recording apparatus according to claim 4, wherein a thinning rate of ink ejected from the recording head is determined.

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