JP5655457B2 - Printing apparatus and printing method - Google Patents

Description

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

As one of printing apparatuses, there is an ink jet printer (hereinafter referred to as a printer) including a nozzle row in which nozzles that eject ink (fluid) to a medium are arranged in a predetermined direction. Known printers include a printer that repeats an image forming operation in which ink is ejected from nozzles while moving a nozzle row in a moving direction that intersects a predetermined direction, and a transport operation that transports a medium in a transport direction that is a predetermined direction. .

In addition to a color ink such as cyan, magenta, and yellow, a printing apparatus that performs printing using a white ink is known (see, for example, Patent Document 1). In such a printer, for example, a color image with good color development can be printed without being influenced by the background color of the medium by printing a background image and a color image with white ink superimposed. For this reason, there are printers that perform printing by selecting one of a “background color ink use mode” in which a background image and a color image are printed and a “color mode” in which only a color image is printed.

JP 2002-38063 A

When the background color ink use mode is selected, among the background image and the color image, the nozzle for the image to be printed first on the medium is set to the nozzle on the upstream side in the medium transport direction from the nozzle for the image to be printed later. Set. By doing so, the image forming operation for forming the background image and the image forming operation for forming the color image can be made different. However, even if the image forming operation for printing the background image and the color image is different, if the time interval for forming the background image and the color image is short, bleeding or color mixing between the background image and the color image will occur. Will occur.
An object of the present invention is to suppress blurring and color mixing of an image when the background color ink and the color ink are overprinted.

The main invention for achieving the above object is to provide a background color ink nozzle array for ejecting background color ink to form background color ink dots on the medium, and a color ink for ejecting color ink to form color ink dots on the medium. A printing apparatus having a nozzle row and a control unit that controls the background color ink and the ejection operation of the color ink, wherein the background color ink dots and the color ink dots are formed on the medium in an overlapping manner. In this case, the control unit determines an interval between the timing at which the background color ink is ejected and the timing at which the color ink is ejected according to the conditions of the background color ink and the environment in which the color ink is ejected. The printing apparatus is characterized by being changed.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is a block diagram illustrating a configuration of a printer. FIG. 2A is a schematic diagram illustrating the configuration of the printer 1. FIG. 2B is a cross-sectional view illustrating the configuration of the printer 1. 4 is a cross-sectional view showing a structure of a head 41. FIG. 4 is an explanatory diagram of a nozzle Nz provided in the head 41. FIG. It is a figure explaining the example of printing in the case of forming the background image by background color ink, and the real image by color ink by "bidirectional printing" of "background color ink use mode." FIG. 7 is a diagram illustrating a flow of a printing process performed by a printer driver. It is a figure which shows the specific process flow for adjusting the ink ejection interval in 1st Embodiment. It is a figure explaining the method to adjust ink ejection timing by "unidirectional printing". FIG. 9 is a diagram illustrating a method of adjusting ink ejection timing by “unidirectional printing” different from FIG. 8. It is a figure which shows the mode of the time change of the brightness of a background color ink dot in different humidity conditions. It is a flowchart explaining the specific operation | movement performed by a humidity prediction process. It is a figure which shows an example of the test pattern used by humidity prediction processing. It is a flowchart explaining the specific operation | movement of the ink ejection interval adjustment process in 4th Embodiment. It is a flowchart explaining the specific operation | movement of the ink ejection interval adjustment process in 5th Embodiment. 2 is a block diagram illustrating an overall configuration of a printer. FIG. 2 is a schematic diagram illustrating a configuration of a printer 2. FIG. FIG. 4 is a diagram illustrating an arrangement of a plurality of small heads on the lower surface of the head 41.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A background color ink nozzle row for ejecting a background color ink containing hollow polymer fine particles to form a background color ink dot on the medium; a color ink nozzle row for ejecting the color ink to form a color ink dot on the medium; and A control unit that controls a background color ink and an ejection operation of the color ink, and when the background color ink dot and the color ink dot are formed on the medium, The control unit changes an interval between the timing at which the background color ink is ejected and the timing at which the color ink is ejected according to an environmental condition in which the background color ink and the color ink are ejected , and The lightness measured for the background color ink dots or the environmental conditions predicted based on the lightness are compared with a predetermined standard and Control unit, the printing apparatus characterized by lengthening the interval by the results of the comparison.
According to such a printing apparatus, when the background color ink and the color ink are overprinted,
It is possible to suppress bleeding and color mixing of the image.
In addition, according to such a printing apparatus, in consideration of the humidity condition, by increasing the ink ejection interval only when the humidity is high, it is possible to perform printing while suppressing bleeding and color mixing in as short a time as possible. .

This printing apparatus includes a temperature detection unit that detects a temperature, and when the temperature detected during printing is equal to or lower than a predetermined reference temperature, the control unit increases the interval. It is desirable.
According to such a printing apparatus, in consideration of the temperature condition, by increasing the ink ejection interval only when the temperature is low, it is possible to execute printing that suppresses bleeding and color mixing in as short a time as possible.

In this printing apparatus, a head unit having the background color ink nozzle row and the color ink nozzle row ejects the background color ink and the color ink while moving in a scanning direction that intersects the conveyance direction of the medium. In the printing apparatus, when the detected temperature is equal to or lower than the reference temperature, the control unit ejects the background color ink while the head unit moves in the scanning direction; and It is desirable that a pause time be provided between the second printing operation in which the head portion ejects the color ink while moving in the scanning direction.

According to such a printing apparatus, it is possible to sufficiently dry the previously formed ink dots by securing the ink ejection interval by the waiting time between the passes.

In this printing apparatus, the background color ink nozzle row and the color ink nozzle row are installed at a position facing the medium, and the background color ink nozzle row and the color are conveyed while the medium is transported in the transport direction. In the printing apparatus that ejects the background color ink and the color ink from the ink nozzle row, when the detected temperature is equal to or lower than the reference temperature,
It is preferable that the control unit slows the conveyance speed of the medium.
According to such a printing apparatus, it is possible to sufficiently dry the previously formed ink dots by ensuring the ink ejection interval by changing the medium conveyance speed.

In this printing apparatus, it is preferable that the background color ink and the color ink are inks containing water as a main solvent, and the medium is a medium that absorbs the water.
According to such a printing apparatus, when water-based ink is used for a hygroscopic medium, ink bleeding can be suppressed by ensuring the drying time of the ink dots formed on the medium.

In such a printing apparatus, it is preferable that at least one of the background color ink and the color ink contains glycerin.
According to such a printing apparatus, even when overprinting is performed using an ink that contains glycerin and is difficult to dry, bleeding of the ink can be suppressed.

Also, a background color ink containing hollow polymer fine particles is ejected from the background color ink nozzle row to form a background color ink dot on the medium, and a color ink dot is ejected from the color ink nozzle row to form a color ink dot on the medium. Forming, when the background color ink dots and the color ink dots are formed on the medium, the timing at which the background color ink is ejected and the timing at which the color ink is ejected. Changing the interval according to the background color ink and the environmental conditions from which the color ink is ejected, and the environmental conditions predicted based on the lightness or lightness measured for the background color ink dots; makes a comparison with a predetermined reference, be longer the interval by the results of the comparison, it clear that the printing method comprising .

=== Basic Configuration of Printing Apparatus ===
As a form of a printing apparatus for carrying out the invention, an ink jet printer (printer 1) will be described as an example.

<Printer configuration>
FIG. 1 is a block diagram illustrating the overall configuration of the printer 1.
The printer 1 is a liquid ejection device that records (prints) characters and images on a medium such as paper, cloth, and film, and is connected to a computer 110 that is an external device so as to be communicable.
A printer driver is installed in the computer 110. The printer driver is a program for displaying a user interface on a display device and converting image data output from an application program into print data. The printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. Also, the printer driver can be downloaded to the computer 110 via the Internet. In addition, this program is comprised from the code | cord | chord for implement | achieving various functions.
The computer 110 outputs print data corresponding to the image to be printed to the printer 1 in order to cause the printer 1 to print an image.

The printer 1 includes a transport unit 20, a carriage unit 30, and a head unit 4.
0, a detector group 50, and a controller 60. The controller 60 controls each unit based on print data received from the computer 110 that is an external device, and prints an image on a medium. The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the detector group 50.

<Transport unit 20>
FIG. 2A is a schematic diagram illustrating the configuration of the printer 1 of the present embodiment. FIG. 2B is a cross-sectional view illustrating the configuration of the printer 1.
The transport unit 20 feeds a medium (such as paper S) in a predetermined direction (hereinafter referred to as a transport direction).
It is for making it convey. Here, the transport direction is a direction that intersects the moving direction of the carriage. The transport unit 20 includes a paper feed roller 21, a transport motor 22, a transport roller 23, a platen 24, and a paper discharge roller 25 (FIGS. 2A and 2B).
The paper feed roller 21 is a roller for feeding the paper inserted into the paper insertion slot into the printer. The transport roller 23 is a roller that transports the paper S fed by the paper feed roller 21 to a printable region, and is driven by the transport motor 22. The operation of the transport motor 22 is controlled by a controller 60 on the printer side. The platen 24 is a member that supports the paper S being printed from the back side of the paper S. The paper discharge roller 25 is a roller for discharging the paper S to the outside of the printer, and is provided on the downstream side in the transport direction with respect to the printable area.

<Carriage unit 30>
The carriage unit 30 is for moving (also referred to as “scanning”) the carriage 31 to which the head unit 40 is attached in a predetermined direction (hereinafter referred to as a moving direction). The carriage unit 30 includes a carriage 31 and a carriage motor 32 (also referred to as a CR motor) (FIG. 2A).
The carriage 31 can reciprocate in the moving direction and is driven by a carriage motor 32. The operation of the carriage motor 32 is controlled by a controller 60 on the printer side. Further, the carriage 31 detachably holds an ink cartridge that stores ink.

<Head unit 40>
The head unit 40 is for ejecting ink onto the paper S. Head unit 4
0 includes a head 41 having a plurality of nozzles. The head 41 is provided on the carriage 31, and when the carriage 31 moves in the movement direction, the head 41 also moves in the movement direction. Then, when the head 41 is intermittently ejected while moving in the moving direction, dot lines (raster lines) along the moving direction are formed on the paper.

FIG. 3 is a cross-sectional view showing the structure of the head 41. The head 41 includes a case 411, a flow path unit 412, and a piezo element group PZT. Case 411 is a piezo element group PZ.
T is accommodated, and the flow path unit 412 is joined to the lower surface of the case 411. The flow path unit 412 includes a flow path forming plate 412a, an elastic plate 412b, and a nozzle plate 412c. The flow path forming plate 412a is formed with a groove portion serving as a pressure chamber 412d, a through hole serving as a nozzle communication port 412e, a through port serving as a common ink chamber 412f, and a groove portion serving as an ink supply path 412g. The elastic plate 412b has an island portion 412h to which the tip of the piezo element PZT is joined. An elastic region is formed by an elastic film 412i around the island portion 412h.

The ink stored in the ink cartridge is supplied to the pressure chamber 412d corresponding to each nozzle Nz via the common ink chamber 412f. The nozzle plate 412c is a plate on which the nozzles Nz are formed. On the nozzle surface, the yellow nozzle row Y that ejects yellow ink
A magenta nozzle array M that ejects magenta ink, a cyan nozzle array C that ejects cyan ink, a black nozzle array K that ejects black ink, and a background color nozzle array W that ejects background color ink. ing.

The piezo element group PZT has a plurality of comb-like piezo elements (drive elements), and is provided by the number corresponding to the nozzles Nz. A drive signal COM is applied to the piezo element by a wiring board (not shown) on which the head controller HC and the like are mounted, and the piezo element expands and contracts in the vertical direction according to the potential of the drive signal COM. When the piezo element PZT expands and contracts, the island portion 412h
Is pushed toward the pressure chamber 412d or pulled in the opposite direction. At this time, the elastic film 412i around the island portion 412h is deformed, and the pressure in the pressure chamber 412d rises and falls, thereby ejecting ink droplets from the nozzles.

FIG. 4 is an explanatory diagram of the nozzle Nz provided in the head 41. As shown in FIG.
In each MYKW nozzle row, nozzles Nz, which are ejection ports for ejecting ink of each color, are arranged at predetermined intervals D in the transport direction. Each nozzle row has # 1 to # 180.
180 nozzles Nz are provided respectively. Note that the actual number of nozzles in each nozzle row is not limited to 180. For example, the number of nozzles may be 90 or 360. In FIG. 4, the nozzle rows are arranged in parallel along the moving direction, but may be arranged in a vertical row along the transport direction. Further, instead of having one nozzle row for each color of CMYKW, it may be configured to have a plurality of nozzle rows for each color.

<Detector group 50>
The detector group 50 is for monitoring the status of the printer 1. The detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detection sensor 53, an optical sensor 54, and a temperature sensor 55 (FIGS. 2A and 2B).

The linear encoder 51 detects the position of the carriage 31 in the moving direction. The rotary encoder 52 detects the rotation amount of the transport roller 23. The paper detection sensor 53 detects the position of the leading edge of the paper S being fed. The optical sensor 54 detects the presence or absence of the paper S at the opposite position by the light emitting part and the light receiving part attached to the carriage 31, for example, detects the position of the edge of the paper while moving, and sets the width of the paper. Can be detected. The optical sensor 54 also has a leading edge (an end on the downstream side in the transport direction, also referred to as an upper end) and a rear end (an end on the upstream side in the transport direction, also referred to as the lower end) of the paper S depending on the situation. It can be detected.

The temperature sensor 55 detects the temperature around the printer 1. Thereby, the temperature at the time of printing is measured. As the temperature sensor 55, a thermocouple or a resistance thermometer using a thermistor can be used, and the temperature sensor 55 is installed at a position that is not easily affected by heat radiation from the printer 1 body and easily detects the temperature in the vicinity of the printing region. (See FIG. 2A).
The temperature sensor 55 is in response to a command from the CPU 62 at an arbitrary timing.
The ambient temperature of the printer (the temperature of the printing environment) can be detected.

<Controller 60>
The controller 60 is a control unit (control unit) for controlling the printer. The controller 60 includes an interface unit 61, a CPU 62, a memory 63,
And a unit control circuit 64.
The interface unit 61 transmits and receives data between the computer 110 that is an external device and the printer 1. The CPU 62 is an arithmetic processing device for performing overall control of the printer 1. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and is configured by a storage element such as a RAM or an EEPROM.
Then, the CPU 62 controls each unit such as the transport unit 20 via the unit control circuit 64 in accordance with a program stored in the memory 63.

<Colorimeter 150>
The colorimeter is a spectrocolorimeter for measuring a colorimetric value in a predetermined range of an image and acquiring it as a colorimetric value in the predetermined range, and is connected to the computer 110 (see FIG. 1). The colorimeter 150 is used to measure the lightness of the printed surface of a test pattern printed with background color ink described later.
In the test pattern color measurement described later, the color measurement value acquired by the color measuring device 150 is L *.
It is a value expressed as each color component value in the a * b * color space. However, other color spaces (for example, X
Each color component of YZ color space or L * u * v * color space) or a value expressed as spectral reflectance may be used.

<Printing operation of printer 1>
In the printer 1, a dot forming process in which ink droplets are intermittently ejected from the head 41 moving in the moving direction to form dots on the medium, and a conveying process in which the medium is conveyed in the conveying direction (for moving the medium) Equivalent). By doing so, dots can be formed in the subsequent dot formation process at a position on the medium that is different from the position of the dot formed by the previous dot formation process (hereinafter also referred to as pass). A two-dimensional image can be printed.
The controller 60 alternately repeats the dot formation process and the conveyance process until there is no more data to be recorded, and gradually records an image composed of dot lines on the paper. When there is no more data to be recorded, the paper discharge roller is rotated to discharge the paper. In addition,
The determination of whether or not to discharge paper may be based on a paper discharge command included in the recording data.
The same process is repeated when recording on the next sheet, and the recording operation is terminated when not recording.

=== Definition of white color ===
“White” ink is also included as an example of the background color ink used for printing in the present embodiment. Here, the term “white” is not limited to the white color in the strict sense that is the surface color of an object that reflects 100% of all wavelengths of visible light. The called color is also included in “white”.

“White” means, for example, (1) color measurement mode: spot color measurement, light source: D50, backing: Black, printing medium: measured with a transparent film using a colorimeter eye-one Pro manufactured by X-rite. If it is colored, the label in the Lab system is on the a * b * plane within the circumference of the radius 20 and inside thereof, and L * is in the hue range represented by 70 or more, or (2) Minolta When using the colorimeter CM2022 manufactured by the company with color measurement in the measurement mode D502 ° field of view, SCF mode, and white background, the label in the Lab system is on the circumference of the radius 20 and on the inside on the a * b * plane. , And L * is in the hue range represented by 70 or more, or (3) the color of the ink used as the background of the image as described in JP-A-2004-306591, as the background Limited to pure white if used No.

=== Description of Print Mode ===
<About unidirectional printing and bidirectional printing>
In the printer 1 of the present embodiment, the home position HP of the head 41 is located on the right side in the movement direction in FIG. 2A. The printer 1 ejects ink droplets from the nozzles when the head 41 moves from the right side of the moving direction (from the home position) to the left side, and ejects ink from the nozzles when the head 41 moves back from the left side of the moving direction to the right side. Printing can be carried out by selecting one of the two printing methods: “unidirectional printing” that does not eject droplets and “bidirectional printing” that ejects ink droplets from the nozzles during both forward and backward passes. .

In “bidirectional printing”, since ink droplets are ejected in a reciprocating manner, the printing speed is faster than “unidirectional printing”. On the other hand, in “bidirectional printing”, the landing position of the ink droplets on the medium may be different between the forward pass and the return pass, so if you want to print with priority on image quality, use “unidirectional print”.
Is often selected. In normal printing in the printer 1, the printing mode is set to “bidirectional printing” in order to ensure a comfortable printing speed.

In unidirectional printing, the operation during the forward pass corresponds to one pass. An operation in which the head 41 moves in the movement direction without ejecting ink droplets during the return pass of unidirectional printing is referred to as a “return operation”. In the unidirectional printing, ink droplets may be ejected from the nozzles during the backward pass without ejecting ink droplets from the nozzles during the forward pass. On the other hand, in bidirectional printing, the operation during the forward pass and the operation during the return pass each correspond to one pass.

<Printing in background ink use mode>
The printer 1 has a “color mode” that prints only a color image (including a monochrome image) on a medium using four color inks (CMYK), and a background image and a color image (main image) using a background color ink (W). The image is formed on the medium in any one of the “background color ink use modes” in which the image is printed on the medium. By providing a background image such as white on the background of the color image as in the background color ink use mode, an image with good color development can be printed even when the medium is not white. In the background color ink use mode,
It is also possible to print a color image first to form a background image and to form an image with background color ink thereon.

FIG. 5 is a diagram illustrating a printing example when a background image with a background color ink and an actual image with a color ink are formed by “bidirectional printing” in the “background color ink use mode”. In the figure, for simplicity of explanation, the number of nozzles belonging to one nozzle row is drawn as 10 (# 1 to # 10). In addition, the nozzle rows that eject the four color inks (CMYK) are collectively referred to as “color nozzle row Co”. That is, the head 41 includes the color nozzle row Co and the background color nozzle row W.
Consists of. In FIG. 5, each nozzle of the color nozzle row Co is represented by a circle, and each nozzle of the background color nozzle row W is represented by a triangle. The nozzles colored black represent nozzles that eject ink in the pass.

FIG. 5 shows band printing. Band printing is a printing method in which band images formed in one pass are arranged in the transport direction, and raster lines of other passes are arranged between raster lines (dot rows along the moving direction) formed in a certain pass. Is a printing method that does not form a film.

The head 41 moves from the left side (explained with the home position as the left side in FIG. 5) to the right side (forward movement) in the first pass, while the background color from each nozzle (# 1 to # 10) of the background color nozzle row W. A background color ink dot row is formed on each of the first to tenth raster lines along the moving direction by ejecting ink, and a background image is printed. Next, in a state where the medium is not conveyed, the head 41
Moves in the second pass from the right side to the left side (double-acting) while each nozzle (# 1 to # 1) of the Co nozzle row
Color ink is ejected from 0). As a result, a color ink dot row is formed on the background color ink dot row formed in each of the first to tenth raster lines, and an actual image is printed. That is, while the head 41 reciprocates once in the movement direction, a background image having a width of 10 raster lines is formed, and an actual image of 10 raster lines is formed on the background image.

Thereafter, the transport unit 20 transports the medium for 10 raster lines (10 nozzles) in the transport direction. Then, again while the head 41 reciprocates once in the moving direction (3 passes and 4
11th to 20th raster lines are formed in (pass). An image is printed by repeating this operation.

By the way, when the background image is printed using only the background color ink, the color of the background color ink itself for printing the background image becomes the color of the background image. However, for example, even in the case of “white” background color ink, the white color is slightly different depending on the ink material. Therefore, a background image having a color different from the color desired by the user may be printed depending on the background color ink used. Depending on the printed matter, a background image having a slight chromatic color instead of simple white color may be desired. When a white medium is used, the white color is slightly different depending on the type of medium even in the white medium. Therefore, when a background image is printed on a white medium, if the white color of the background image is different from the white color of the medium, the background image becomes conspicuous.

Therefore, in this embodiment, a small amount of color ink (CMYK) is used as appropriate together with the background color ink to print a background image of a desired color (for example, an adjusted white background image). In this case, when the background image is printed, at least one color ink among the color inks that can be ejected by the printer 1 may be used. For example, all four color inks may be used. Two color inks may be used. Thus, when the background color ink has a slight color, the background image can be made closer to an achromatic color by printing the background image together with the ink that cancels the color.

At this time, the position in the transport direction of the nozzles of the background color nozzle row W that prints the background image is made equal to the position in the transport direction of the nozzles of the color nozzle row Co that also prints the background image. Then, in order to print the background image, the background color ink and the color ink are ejected in the same pass with respect to a predetermined area of the medium. As a result, the background color ink and the color ink are mixed, and the graininess of the background image can be reduced. In addition, since the ratio of the color ink dots constituting the background image is relatively smaller than the ratio of the background color ink dots, in order to reduce the color ink graininess in the background image, the color ink dots are made as uniform as possible. It is preferable to be dispersed.

Note that print data for causing the printer 1 to print a background image of a desired color may be stored in advance by the printer 1 or may be created by a printer driver. When the user selects a desired background image color by looking at the monitor of the printer 1 or the computer screen, print data of the background image corresponding to the selected color may be generated. .

=== About ink and recording medium ===
In this embodiment, ink and an ink-absorbing medium (ink-absorbing recording medium) that absorbs the ink are used. As the ink absorptive recording medium, a recording medium composed of a substrate having ink absorptivity or a recording medium provided with an ink receiving layer on the substrate can be used. Examples of the substrate having ink absorptivity include paper and cloth.

The ink may be any ink that can be absorbed by the ink-absorbing medium, but preferably contains an evaporable solvent in order to ensure absorbability to the ink-absorbing medium. Further, “aqueous ink” containing at least water as a solvent is particularly preferable. As other components constituting the ink, there are dyes and pigments as color materials. In addition, it may contain a water-soluble organic solvent for the stability of ejection from the ink head, and it may contain a moisturizer, a penetration enhancer, a ph regulator, an insect repellent, an ultraviolet absorber, and the like as necessary. May be. As such a color ink, for example, JP-A-200200
The inks described in 8-81693, JP-A-2005-105135, and JP-A-2003-292934 can be used.

The recording medium fixes the color material of the ink composition by absorbing the solvent of the ink composition. For example, a medium using a base material that absorbs ink such as paper or cloth may be used, or a base material that absorbs ink or a base material that does not absorb ink may be provided with an ink receiving layer that absorbs ink. When a transparent medium is used, for example, recording media described in JP-A-2009-925, JP-A-9-99634, and JP-A-9-208870 can be used.

As the ink receiving layer, a known ink receiving layer usually provided on a recording medium for an ink jet recording method can be used. As the known ink receiving layer, for example, an ink receiving layer made of a resin is known. Examples of the resin used for the ink receiving layer include, for example, Japanese Patent Application Laid-Open Nos. 57-38185 and 62-184879. Polyvinylpyrrolidone or vinylpyrrolidone-vinyl acetate copolymer as disclosed in JP-A-60-16
A resin composition mainly composed of polyvinyl alcohol as disclosed in Japanese Patent No. 8651, 60-171143, 61-134290, and vinyl alcohol as disclosed in Japanese Patent Laid-Open No. 60-234879. Olefin or copolymer of styrene and maleic anhydride, cross-linked product of polyethylene oxide and isocyanate as disclosed in JP-A-61-74879, disclosed in JP-A-61-181679 A mixture of such carboxymethylcellulose and polyethylene oxide, JP 61-13
A polymer obtained by grafting methacrylamide to polyvinyl alcohol as disclosed in Japanese Patent No. 2377, an acrylic polymer having a carboxyl group as disclosed in Japanese Patent Laid-Open No. 62-220383, and Japanese Patent Laid-Open No. 4-214382 Polyvinyl acetal polymers such as those disclosed in JP-A-4-282282 and 4-28565
Various ink-absorbing polymers such as a crosslinkable acrylic polymer as disclosed in No. 0 publication can be exemplified.

Known ink receiving layers include those disclosed in JP-A-4-282282 and 4-285650.
In Japanese Patent Publication No. Gazette et al., An ink receiving layer using a polymer matrix composed of a crosslinkable polymer and an absorbent polymer is disclosed. Further, an ink receiving layer using alumina hydrate (cationic alumina hydrate) is also known, for example, JP-A-60-232990, JP-A-60-245588, and JP-B-3-24906. JP-A-6-199035,
JP 7-82694 A discloses a recording medium in which fine pseudo boehmite-type alumina hydrate is coated on a substrate surface together with a water-soluble binder. Also, for example, JP-A-10-20
Japanese Patent No. 3006 discloses an ink-receiving layer using a synthetic silica mainly having a primary particle diameter of 3 nm to 30 nm by a vapor phase method. Furthermore, JP 2001-328344 A.
The publication discloses an ink receiving layer containing an inorganic pigment and a polymer adhesive. In the present embodiment, it is preferable to use a film substrate provided with each of these ink receiving layers.

In the present embodiment, as the background color ink composition for the background image, any white ink composition that is usually used in the ink jet recording method can be used. Examples of such white pigments include inorganic white pigments, organic white pigments, and white hollow polymer fine particles. As the white ink composition, a water-based ink composition containing hollow polymer fine particles as a colorant component. Is preferably used.

Examples of inorganic white pigments include alkaline earth metal sulfates such as barium sulfate, alkaline earth metal carbonates such as calcium carbonate, silicas such as finely divided silicic acid and synthetic silicates, calcium silicate, alumina, alumina Hydrates, titanium oxide, zinc oxide, talc, clay and the like can be mentioned. In particular, titanium oxide is known as a white pigment having preferable hiding properties, coloring properties, and dispersed particle sizes.

Examples of the organic white pigment include organic compound salts disclosed in JP-A No. 11-129613 and alkylene bismelamine derivatives disclosed in JP-A Nos. 11-14365 and 2001-234093. As specific products of the above white pigment, Shigenox OWP
, Shigenox OWPL, Shigenox FWP, Shigenox FWG, Sh
igenoxUL, ShigenoxU (above, manufactured by Hakkor Chemical Co., Ltd., both trade names), and the like.

The hollow polymer fine particles to be contained as the colorant component have, for example, an outer diameter of about 0.1 to 1
It can be a fine particle having an inner diameter of about 0.05 to 0.8 μm, insoluble in the solvent of the white ink composition, and does not chemically react with other components such as a binder resin component. is necessary. The hollow polymer fine particles are made of a synthetic polymer whose walls are permeable to liquid, and the space at the center of the hollow polymer fine particles can pass through the walls and allow liquid to enter and exit. Therefore, the space in the center of the hollow polymer fine particles is filled with the solvent in the state of the ink composition, and the specific gravity of the hollow polymer fine particles and the specific gravity of the ink composition are substantially the same. It is stably dispersed inside. On the other hand, when the ink composition is printed on the printing surface and dried, the space at the center of the hollow polymer fine particles is replaced with air, so that incident light is diffusely reflected between the resin and the space, and substantially white. In the fourth embodiment described later, such properties of the hollow polymer fine particles are used.

Further, as described above, the hollow polymer fine particle contains a liquid in the fine particle before printing, but the liquid that has entered the fine particle passes through the fine particle wall after printing and diffuses. It can be of a type in which fine pores are filled with air or a completely sealed type in which air is initially contained inside. Since it is desired that the hollow polymer fine particles used in the white ink composition do not precipitate in the ink composition, those having a specific gravity approximately equal to the specific gravity of the ink composition solution are preferable. For this reason, it is preferable to adjust the specific gravity of the ink composition solution using a specific gravity adjusting agent such as glycerin as necessary. Glycerin also has a role as an anti-thickening agent for ensuring the moisture retention of the ink.

Examples of commercially available hollow polymer fine particles satisfying the above properties include, for example, Ropaque O commercially available from Rohm and Haas.
P-62 etc. can be mentioned. This is an aqueous dispersion containing 38% by weight of hollow polymer fine particles made of an acrylic / styrene copolymer. The inner diameter of the fine particles is about 0.3 μm,
The outer diameter is about 0.5 μm, and the inside is filled with water.

The hollow polymer fine particles are produced by a known production method such as US Pat. No. 4,089,8.
It can also be obtained by the method disclosed in No. 00 specification. The hollow polymer fine particles are substantially made of an organic polymer and exhibit mature plasticity. The thermoplastic resin used for the production of the hollow polymer fine particles is preferably a cellulose derivative, acrylic resin, polyolefin, polyamide, polycarbonate, polystyrene, styrene or other vinyl monomer copolymer, vinyl acetate, vinyl alcohol. And vinyl polymers such as vinyl chloride or vinyl butyral homopolymers or copolymers, diene homopolymers and copolymers, and the like. Particularly preferred thermoplastic polymers include copolymers of 2-hexyl acrylate, copolymers of methyl methacrylate, and copolymers of styrene and other vinyl monomers such as acrylonitrile. be able to.

The content of the hollow polymer fine particles in the background color ink composition used in the present embodiment is, for example,
It can be 0.1 to 20% by weight. When the content of the hollow polymer fine particles is 0.1% by weight or more, sufficient whiteness can be obtained. On the other hand, if it is 20% by weight or less, a sufficient amount of the ink binder resin component necessary for ensuring the viscosity required for the ink composition for ink jet printing can be contained, and as a result, sufficient printing adhesion can be achieved. Sex can be secured.

In the present embodiment, the white pigment may be used alone or in combination. For pigment dispersion, ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill,
A paint shaker or the like can be used. It is also possible to add a dispersant when dispersing the pigment.

In addition to the background colorant component, the background color ink composition used in the present embodiment includes various components usually contained in an ink composition for inkjet printing, such as a resin component, a dispersant component, and a solvent component (particularly water). ) And the like. Moreover, as a white ink composition containing hollow polymer fine particles as a white colorant, for example, the composition described in Japanese Patent No. 3562754 (Patent Document 1) or Japanese Patent No. 3639479 (Patent Document 2) is used. You can also.

The non-background color ink composition for color images used in the present embodiment is, for example, a color ink composition, a black ink composition, or a gray ink composition. Examples of the color ink composition include a cyan ink composition, a magenta ink composition, a yellow ink composition, a light cyan ink composition, a light magenta ink composition, and a red ink composition and a green ink composition. Or a blue ink composition. As the non-white ink composition, the various ink compositions described above can be used alone or in combination of two or more.

As the non-background color ink composition, any non-background color ink composition usually used in an ink jet recording method can be used, and a water-based ink composition containing a dye or pigment as a colorant component can be used. preferable. In particular, it is preferable to use an ink composition that exhibits good characteristics (for example, color developability and fixability) with respect to the transparent film substrate or the ink receiving layer.

Both the background color ink and the non-background color ink desirably contain glycerin (hereinafter also referred to as GLY) as a thickening preventive agent. GLY is excellent in moisture retention, and by including GLY in the ink, problems such as solidification of the ink in the nozzles are less likely to occur, and ink ejection stability can be ensured. Although the ease of thickening the ink also changes depending on the content of GLY, the background color ink assumed in this embodiment contains 7% or more of GLY, and the time required for the ink dots formed on the medium to dry Is longer than normal ink. for that reason,
In the case of overprinting with other inks, if the ink does not have a sufficient drying time, bleeding or color mixing tends to occur between the inks.

=== First Embodiment ===
In the first embodiment, when the background color ink and the color ink are overprinted, the background color ink ejection timing and the color ink ejection timing are changed according to the temperature during printing. Thus, after ink dots (background color ink dots) that become background images are formed on the medium, ink dots (color ink dots) that become actual images on the background color ink dots
The drying time until the film is formed is secured, and the occurrence of bleeding or the like is suppressed.

<Print processing by printer driver>
FIG. 6 shows a flow of printing processing performed by the printer driver during printing.
The printer driver receives image data from the application program, converts it into print data in a format that can be interpreted by the printer 1, and outputs the print data to the printer 1. When converting image data from an application program to print data, the printer driver performs resolution conversion processing, color conversion processing, halftone processing, rasterization processing,
Etc. Various processes performed by the printer driver will be described below.

Prior to the start of printing, the computer 110 and the printer 1 are first connected (see FIG. 1), and the printer driver stored in the CD-ROM included with the printer 1 (
Alternatively, a printer driver downloaded from the homepage of the printer manufacturer is installed in the computer 110. This printer driver includes a code for causing a computer to execute each process of FIG.

When printing is started by a user instructing printing from the application program, the printer driver is called, receives image data (print image data) to be printed from the application program (S101), and prints the print image data. Then, resolution conversion processing is performed (S102).

The resolution conversion process is a process of converting image data (text data, image data, etc.) to a resolution (print resolution) when printing on a medium. For example, the recording resolution is 720
When it is specified as × 720 dpi, the vector format image data received from the application program is converted into bitmap format image data with a resolution of 720 × 720 dpi. Each pixel data of the image data after the resolution conversion process is RGB data of each gradation (for example, 256 gradations) represented by the RGB color space.

Next, the printer driver performs color conversion processing (S103). The color conversion process is a process of converting image data in accordance with the color space of the ink color of the printer 1. here,
Image data in the RGB color space is converted into image data in the CMYK color space. This color conversion process is performed based on a 3D-LUT in which the gradation values of RGB data and the gradation values of CMYK data are associated with each other. As a result, image data in the CMYK color space is obtained. The pixel data after the color conversion processing is 8-bit CMYK data with 256 gradations represented by the CMYK color space.

After the color conversion process, the printer driver performs a halftone process (S104). The halftone process is a process of converting high gradation number data into low gradation number data that can be formed by the printer 1. Here, print image data of 256 gradations is converted into 1-bit data indicating 2 gradations or 2-bit data indicating 4 gradations. As a halftone processing method, a dither method, an error diffusion method, and the like are known, and this embodiment also performs such a halftone processing. The halftone processed data has a resolution equivalent to the recording resolution (for example, 720 × 720 dpi). The image data after halftone processing corresponds to 1-bit or 2-bit pixel data for each pixel, and this pixel data is data indicating the dot formation status (presence / absence of dot, dot size) in each pixel. Become.

Next, the printer driver performs rasterization processing (S105). The rasterization process is a process of changing the order of arrangement of pixel data on the print image data to the order of data to be transferred to the printer 1. For example, the pixel data is rearranged according to the arrangement order of the nozzles in each nozzle row. Thereafter, the printer driver generates print data by adding control data for controlling the printer 1 to the pixel data, and transmits the print data to the printer 1.

The printer 1 performs a printing operation according to the received print data. Specifically, the controller 60 of the printer 1 controls the transport unit 20 and the like according to the received print data control data, controls the head unit 40 according to the pixel data of the print data, and ejects ink from each nozzle.

<Adjustment of ink ejection interval according to temperature conditions>
In the present embodiment, when the background color ink and the color ink are overprinted, the operation of the head unit 40 (carriage unit 30) is changed according to the temperature condition, whereby the background color ink ejection timing and the color ink are changed. Increase the interval with the eruption timing. As a result, the next ink dot can be formed after adequately ensuring the drying time of the previously formed ink dot, and the occurrence of bleeding and color mixing between the ink dots is suppressed.

FIG. 7 shows a specific processing flow for adjusting the ink ejection interval.

(S201: Background color ink use mode determination)
First, the CPU 62 of the printer 1 determines whether or not the print data received from the printer driver is printing in the “background color ink use mode”. That is, it is determined whether the background color ink and the color ink are overprinted (S201). As described above, the background color ink used in the present embodiment contains GLY and has a property that it is difficult to dry. In addition, the background image formed by the background color ink and the color image formed by the color ink are formed so as to overlap each other on the medium. Therefore, if a sufficient drying time is not ensured after the background color ink dots are formed, bleeding or color mixing may occur when other inks are overprinted. On the other hand, in “color mode” printing in which a color image is formed without forming a background image, color inks are not overprinted with a high dot density in the formation of a color image, so there is no need to adjust the ink ejection interval. Problems such as bleeding are less likely to occur.

Therefore, when it is determined that the printing is in the “color mode”, the ink ejection interval is not adjusted, and the printing is executed as it is. On the other hand, if it is determined that the printing is in the “background color ink use mode”, the process proceeds to the next temperature detection process (S202).

Note that, instead of determining the “background color ink use mode” in S201, it may be determined whether the ink to be used contains a predetermined percentage or more of GLY. That is, it is directly determined whether or not the ink used for printing is difficult to dry (whether or not the ink ejection interval needs to be adjusted). In this case, based on the type of ink used for printing (information such as the GLY content rate), the user can make a determination at the start of printing.

(S202: Temperature detection)
As a result of S201, when it is determined that printing is performed in the background color ink use mode, temperature data is detected. In the present embodiment, the time required to dry the ink dots formed on the medium is greatly affected by the temperature during printing. For this reason, the temperature data detected in this step is a reference for adjusting the ink ejection interval.

The CPU 62 of the printer 1 detects the temperature (air temperature) k in the environment where the printer 1 is installed by the temperature sensor 55 and temporarily stores it in the memory 63. In addition, although temperature detection itself may be performed at the timing before the above-mentioned printing process (S101-S105),
In order to more accurately detect the temperature condition during printing, it is preferable to detect the temperature at a timing close to the stage where printing is actually performed.

(S203: Comparison between detected temperature k and reference temperature K)
Subsequently, the detected temperature k is compared with a predetermined reference temperature K. As previously mentioned,
Ink containing GLY may have poor drying properties due to the hygroscopicity of GLY, but this property is prominent when the temperature is below a certain level. For example, in the case of the background color ink (GLY content 7%) used for printing in the present embodiment, the drying property is remarkably lowered under a temperature condition of 20 ° C. or less. On the other hand, the drying property does not significantly decrease under temperature conditions higher than 20 ° C. Therefore, if the printing environment is 20 ° C. or lower, it is necessary to adjust the ejection interval between the background color ink and the color ink in order to ensure the drying time as long as possible. Conversely, if the printing environment is higher than 20 ° C., it is only necessary to ensure a normal drying time, so that printing can be performed as it is without adjusting the ink ejection interval. In this embodiment, each color ink has a GLY content of 16%.

The CPU 62 detects the temperature k of the printing environment detected in S202 and stored in the memory 63.
(C) is compared with a reference temperature K (° C.) (20 ° C. in the case of the above example) that is preset and stored in the memory 63, and the detected temperature k (C) is the reference temperature K ( If the temperature is less than (° C.), the ink ejection interval is adjusted (S204). If it is higher than K (° C.), printing is continued without adjusting the ink ejection interval.

Note that a plurality of reference temperatures K are set for each type of ink used, and when a user selects ink to be used via a user interface (not shown), a reference temperature corresponding to the ink is selected. . Further, after confirming the printed image, it is preferable that the user can change the setting of K via the user interface.

(S204: Ink ejection interval adjustment)
Method for adjusting background color ink ejection timing and color ink ejection timing (S20)
4) will be described using a specific example.

<Adjustment of waiting time between passes>
In printing in which the background color ink is ejected in the first pass (during forward movement) and the color ink is ejected in the second pass (during double action) in the “bidirectional printing” mode, the first pass printing operation is completed. Then, the time until the printing operation of the second pass is started (hereinafter also referred to as an inter-pass waiting time) is lengthened to secure the drying time of the background color ink dots formed in the first pass.

For example, in FIG. 5, the CPU 62 operates the head 41 (carriage unit 30) via the unit control circuit 64 to form background color ink dots during forward movement. Thereafter, the operation of the carriage unit 30 is controlled so that the double action is not started immediately but the double action is started after a predetermined time interval (for example, 2 seconds). That is, a pause time (interval) for drying the background image is provided after the background image is printed on a predetermined area of the medium until the printing of the next actual image is started. As a result, the first pass (during forward movement)
After the background color ink dots formed in step 1 are dried and cured to such an extent that they do not mix with other color ink dots, the next color ink dots can be formed on the background color ink dots. That is, it is easy to suppress bleeding and color mixing between the background color ink dots and the color ink dots.

It should be noted that the time setting for the waiting time between passes may be freely changed by the user via a user interface (not shown). The user can print without stress by checking the image quality of the printed image and setting the waiting time between passes in consideration of the balance between the desired print image quality and printing time.

Also, when the printing method is such that color ink is ejected in the first pass (during forward movement) and background color ink is ejected in the second pass (during double movement), the waiting time between passes is lengthened. The method is effective. In this case, the background color ink dots are formed on the color ink dots, but if the color ink dots are not sufficiently dried, the GL contained in the background color ink is contained.
There is a possibility that bleeding occurs when Y absorbs moisture of the color ink dots. Therefore, by increasing the waiting time between passes between the first pass and the second pass and drying the previously formed color ink dots, the background color formed on the color ink dots It is possible to suppress color mixing with ink dots.

<Effects of First Embodiment>
According to the method of the present embodiment, when the background color ink and the color ink are overprinted,
By sufficiently securing the drying time of the ink dots formed earlier, bleeding and color mixing between the ink dots can be suppressed, and a good printed image can be obtained.

Further, the ink ejection interval is appropriately adjusted according to the temperature condition. That is, the ink ejection interval is adjusted by increasing the waiting time between passes only when the temperature during printing is lower than the predetermined temperature and the ink dots are difficult to dry. As a result, it is possible to print an image with good image quality with little blurring and the like in as short a printing time as possible.

=== Second Embodiment ===
In the first embodiment, the ink ejection interval is adjusted by adjusting the “inter-pass waiting time” during bidirectional printing. In contrast, in the second embodiment, the ink ejection interval is adjusted by changing the print mode. That is, the process of (S204) is different from the adjustment process (S201 to S204) of the ink ejection interval in FIG. 7 of the first embodiment. The configuration of the printing apparatus and other printing processes are the same as those in the first embodiment.
Hereinafter, a method for adjusting the ejection timing of the background color ink and the ejection timing of the color ink in the second embodiment will be described.

<Change printing mode (unidirectional printing)>
In this embodiment, when it is determined that the ink ejection interval adjustment is necessary, the printing mode is set to “unidirectional printing”, and the background color ink and the color ink are ejected at the same time so that they do not overlap. The ejection timing and the color ink ejection timing are adjusted.

FIG. 8 is a diagram illustrating a method of adjusting the ink ejection timing by unidirectional printing. In the head 41 in which the same nozzle row W and nozzle row Co as those described in FIG. 5 are arranged, printing is performed using only half of the nozzles for each nozzle row. In FIG. 8, the left side of the moving direction is the home position of the head 41.

When the head 41 (carriage unit 30) moves from the left side (home position) to the right side in the first pass, in the nozzle row W, the nozzles on the upstream half in the transport direction (the colored nozzles # 6 to # 10 in FIG. 8) ) Is used to eject the background color ink. Similarly, the nozzle row Co in the first pass
Then, color ink is ejected using the nozzles on the downstream half in the transport direction (the colored nozzles # 1 to # 5 in FIG. 8). As a result, an actual image made of color ink is formed on the first to fifth raster lines, and a background image made of background color ink is formed on the sixth to tenth raster lines. In this case, the print start position is the sixth raster line.
After the printing of the first pass is completed, the head 41 returns from the right side to the left side without ejecting ink, and the medium is conveyed by 5 raster lines (5 nozzles) in the conveyance direction.
In the second pass operation, as in the first pass, in the nozzle row W, the nozzles on the upstream half in the transport direction (
The background color ink is ejected using # 6 to # 10), and the color ink is ejected using nozzles (# 1 to # 5) on the downstream half in the transport direction in the nozzle row Co. As a result, the actual image with color ink is printed in the second pass on the sixth to tenth raster lines on which the background image was printed in the first pass, and a new background image is printed on the eleventh to fifteenth raster lines. Is printed. after that,
The head 41 returns to the home position (left side in the movement direction in the figure) without ejecting ink.
By repeating this operation, printing in the background color ink use mode is performed.

By setting the print mode to “unidirectional printing”, the time from the end of printing of the previous image (background image) to the start of printing of the subsequent image (actual image) on a predetermined area of the medium That is, the drying time of the previous image is the total time of the medium transport time and the head 41 return operation time.
That is, by performing unidirectional printing in the background color ink use mode, the drying time of the previous image can be lengthened by the time of the return operation of the head 41, and a high-quality image with suppressed image bleeding. Can be printed.
Further, since the movement direction of the head 41 when ink is ejected is limited to one direction, it is difficult to cause a problem that the ink landing position is shifted depending on the movement direction between forward movement and double movement. Therefore, it is easy to realize printing with more stable image quality.

<Modified example of unidirectional printing>
Next, a modification of the method for adjusting the ink ejection timing by “unidirectional printing” will be described.
FIG. 9 is a diagram for explaining a method of adjusting the ink ejection timing by a method different from that in FIG. In the head 41 in which the nozzle row W and the nozzle row Co similar to those in FIG. 8 are arranged, one raster line is divided into two passes and printed using the total number of nozzles for each nozzle row.

In FIG. 9, when the head 41 (carriage unit 30) moves from the left side (home position) to the right side in the first pass, the background color ink is ejected using all the nozzles (# 1 to # 10) in the nozzle row W. To do. Thus, a background image is formed with the background color ink on the first to tenth raster lines in the first pass.
After the first pass printing is completed, the head 41 returns from the right side to the left side without ejecting ink. Subsequently, all the nozzles (# 1) in the nozzle row Co are operated in the second pass in a state where the medium is not conveyed.
Color ink is ejected from ~ # 10). As a result, an actual image is formed on the background image formed in the first pass. Thereafter, the medium is transported by 10 raster lines (10 nozzles) in the transport direction, and the background color ink ejection operation and the color ink ejection operation are repeated.

Also in the case of this modification, the time from when the previous image is printed to the predetermined area of the medium until the printing of the subsequent image is started, that is, the time for the return operation of the head 41, The drying time of the image can be extended, and a high-quality image with suppressed bleeding can be printed.

<Effects of Second Embodiment>
In the second embodiment, as in the first embodiment, when the background color ink and the color ink are overprinted, the ink ejection interval is adjusted according to the temperature condition. Thereby, it is possible to sufficiently ensure the drying time of the previously formed ink dots, and it is possible to obtain a good printed image by suppressing bleeding and color mixing between the ink dots.

Further, the adjustment of the ink ejection interval is performed by changing the printing mode from “bidirectional printing” to “unidirectional printing”. Since the head movement direction at the time of printing is unified in one direction, it is possible to print a higher quality image without causing a shift in the landing position of the ink dots.

=== Third Embodiment ===
In the third embodiment, the ink ejection interval is adjusted by combining the first embodiment and the second embodiment. That is, the method of (S204: Ink ejection interval adjustment) in FIG. 7 is different from the first and second embodiments. The configuration of the printing apparatus and other printing processes are the same as those in the first and second embodiments.

<Combination of adjustment of waiting time between passes and unidirectional printing mode>
In the unidirectional printing mode described in the second embodiment, it is possible to secure a longer drying time by adjusting the waiting time between passes described in the first embodiment.
For example, in FIG. 8, a predetermined time interval is provided after the first pass printing is completed and the head 41 returns to the home position until the next second pass operation is started. Thereby, it is possible to secure a longer drying time of the background image formed in the first pass.
In addition, the combination of the modes makes it easy to freely change the degree of adjustment of the time interval, so that it is possible to more effectively suppress bleeding and color mixing.

A selection or combination of these adjustment methods may be set in advance in the memory 63 so that the selection is made according to the user's preference. For example, if the highest priority is given to image quality, the combination of the unidirectional printing mode and the inter-pass waiting time adjustment is selected, and if you want to keep the printing time as short as possible, only the inter-pass waiting time adjustment is selected. deep.
Then, by making it possible for the user to change such settings, it is possible to perform printing that is more user-preferred with respect to printing time and print image quality.

=== Fourth Embodiment ===
In the fourth embodiment, the interval between the ejection timings of the background color ink and the color ink is adjusted by considering the humidity condition instead of the temperature condition of the printing environment.
As described above, GLY contained in the background color ink has a strong hygroscopic property. Therefore, if the humidity during printing is high, the GLY easily absorbs more moisture, and the background color ink is difficult to dry. Therefore, paying attention to the humidity condition, if the humidity during printing is higher than the predetermined reference humidity, the drying interval of the background color ink dots formed earlier is secured by increasing the ink ejection interval. To do.

In the present embodiment, the printer driver (1) shown in FIG.
After the processing of 01 to S105), the CPU 62 adjusts the ink ejection interval according to the humidity condition. The specific method for adjusting the ink ejection interval is the same as that in the first to third embodiments, except that the humidity condition is considered instead of the temperature condition.

<About humidity prediction>
In the present embodiment, it has been described that the ink ejection interval is adjusted according to the humidity condition, but a general printer often does not have a function of detecting humidity, such as a humidity sensor.
Therefore, in this embodiment, humidity is not detected, but the humidity is predicted by utilizing the property of the background color ink using the hollow polymer fine particles as a pigment due to a change in humidity.

As described above, the background color ink containing the hollow polymer fine particles as a pigment has a space (hereinafter also referred to as a hollow portion) in the center of the hollow polymer fine particles, and the hollow portion is formed by a solvent in the ink before printing. be satisfied. In the background color ink before being ejected from the nozzle, light is transmitted through the pigment particles (hollow polymer fine particles) filled with the solvent, so that the light is not reflected by the pigment particles, and the ink itself is “transparent”. It is a state. On the other hand, when this ink composition is printed (ink dots are formed) and sufficiently dried, the hollow portions of the hollow polymer fine particles filled with the solvent are replaced with air. For this reason, incident light is diffusely reflected in the hollow portion, so that it is substantially white.

Here, the transparency of the background color ink is affected by the amount of moisture contained in the hollow portion of the hollow polymer fine particles. For example, the light reflectance in the hollow portion is maximized in a completely dry state, and conversely, the light reflectance in the hollow portion is very small in a state completely filled with moisture. Therefore, the background color ink dots formed on the medium are initially in a transparent state (a state in which light is transmitted), and are dried and turn white as time passes.

On the other hand, when the humidity of the printing environment is high, the moisture in the hollow portion is difficult to dry, so the background color ink is unlikely to be completely white and exhibits a slightly transparent white. That is, the “white degree” of the image formed by the background color ink using the hollow polymer fine particles as the pigment changes depending on the humidity condition at the time of printing. For example, an image printed with the background color ink shows a nearly transparent color in an environment with a humidity of 90%. However, if the image is left in an environment with a humidity of 10%, the transparent part is dried. Turn white. Therefore, this “degree of whiteness”
Humidity can be predicted from the change in.

In the present embodiment, after a predetermined time has elapsed since the background color ink dot was formed, the background color ink dot was formed by measuring the “degree of whiteness” of the background color ink dot in a state where the color development was stable. Predict the humidity of the affected environment.

First, a test pattern is printed using background color ink, color measurement is performed on the background color ink dots formed on the test pattern after elapse of a predetermined time, and the L * value of the L * a * b * color space ( Hereinafter, it is also detected as brightness). Then, the humidity corresponding to the detected lightness is calculated using the relationship between the lightness and humidity checked in advance.

Here, the relationship between the brightness and humidity of the background color ink dots is obtained by measuring the brightness of the white ink dots in advance for each different humidity condition. Specifically, the lightness of the white ink dots is periodically measured under a certain humidity condition, and the state of the lightness of the background color ink dots over time is examined. This is repeated for different humidity conditions, and the results are stored in the memory 63 of the printer 1 as a table.

FIG. 10 shows an example of how the lightness of the background color ink dots changes with time under different humidity conditions. As shown in the figure, when the humidity is 50%, the brightness gradually increases after the end of printing (at time 0), and the brightness reaches the upper limit L1 after a predetermined time has elapsed. After that, a constant lightness L1 is shown. On the other hand, when the humidity is relatively low (for example, when the humidity is 30%), the brightness rapidly increases after the end of printing, and the upper limit of the brightness is L2 (L1 <L2). Also,
When the humidity is relatively high (for example, when the humidity is 80%), the brightness increases very slowly, and the upper limit of the brightness is L3 (L3 <L1).

Using this property, the brightness of the background color ink dot is measured t minutes after the test pattern is printed (after the color development is stabilized), and the corresponding humidity is predicted by comparing with the above table. become able to. If the brightness is measured before the elapse of t minutes after printing (before the color of the background ink dot is stabilized), an error is displayed when the brightness data is stored in the memory 63. With this, using highly reliable brightness data,
Accurate humidity can be predicted.

<Operation during humidity prediction>
FIG. 11 shows a flow of specific operation when performing humidity prediction.
First, using the printer 1, a background color ink having hollow polymer fine particles as a pigment is ejected onto a print medium to print a test pattern (S301). FIG. 12 shows an example of a test pattern to be printed. The test pattern is composed of a plurality of patches formed by the background color ink with a predetermined gradation value (for example, gradation value 255). The shape of each patch and the number of patches are arbitrary. In the figure, the outline of each patch is printed as a frame with CMYK color ink so that the position of the patch can be easily confirmed. Further, in order to measure the lightness of the background color, the background medium color is black or the like, and at least the color that can measure the lightness of the background color (for example, “white”) is selected.

After the printing of the test pattern is completed and the color development of the background color ink dots is stabilized, the lightness of each patch of the test pattern is measured using the colorimeter 150 (see FIG. 1) connected to the computer 110 (see FIG. 1). S302). The brightness value obtained by measuring each patch is stored in the memory 63 via the computer 110 (S303). Then, an average value of brightness measured for each of the plurality of patches is calculated (S304). This average value is the lightness value of the background color ink dots. The CPU 62 predicts the humidity h of the printing environment from the calculated brightness using a table of brightness and humidity stored in advance (S305).
.
For example, when a table as shown in FIG. 10 is stored, the humidity is 50% if the calculated average brightness is L1, and 30% if the calculated average brightness is L2. When the calculated average brightness is Ln (L1 <Ln <L2), the predicted humidity is calculated from the data of L1 and L2 by a method such as secondary interpolation.
Such humidity prediction processing (S301 to S305) including test pattern printing and colorimetry is performed in advance immediately before printing is started.

<Adjustment of ink ejection interval according to humidity conditions>
The ejection timing of each ink when overprinting the background color ink and the color ink is performed,
Adjustment is made based on the humidity condition predicted by the above-described method to ensure an appropriate ink drying time.
FIG. 13 shows a flow of specific operation in the ink ejection interval adjustment processing.
The step of determining the “background color ink use mode” in (S401) is the same as that in the first embodiment (S20).
Same as 1).
In (S402), the CPU 62 of the printer 1 performs the above-described (S301 to S305).
And a predetermined reference humidity H (for example, 60%) set in advance.
Compare with. If the predicted humidity h is greater than or equal to the reference humidity H, the ink ejection interval is adjusted (S403). If the predicted humidity h is lower than the reference humidity H, printing is continued without adjusting the ink ejection interval. . The magnitude of the reference humidity H may be set so that the user himself can change the setting using the user interface screen after confirming the actually printed image. This makes it possible to achieve both good print image quality and comfortable printing time.

As described above, the specific method for adjusting the ink ejection interval (S403) includes adjusting the waiting time between passes (see the first embodiment), changing the printing mode (see the second embodiment), and a combination thereof (third embodiment). To ensure the longest possible drying time. In FIG. 11, the predicted humidity is obtained from the measured brightness, and in FIG. 13, the predicted humidity is compared with the reference humidity (reference). However, the measured brightness is the reference brightness (reference) corresponding to the reference humidity. ).

<Effects of Fourth Embodiment>
According to the present embodiment, by considering the humidity condition, the ink ejection interval can be appropriately adjusted when the background color ink and the color ink containing a large amount of GLY are overprinted. That is, the ink ejection interval is adjusted to be long only when the humidity of the printing environment is equal to or higher than a predetermined humidity condition, and printing is performed as usual when the humidity is low (when adjustment is not necessary). As a result, the user can perform printing in a comfortable printing time while obtaining an image with good image quality that is hardly affected by humidity conditions.

<Modification of Fourth Embodiment>
In the fourth embodiment, the humidity condition is considered, but the temperature condition may be taken into consideration. As shown in FIG. 10, the phenomenon in which the change in brightness with the elapsed time is different when the humidity is different also occurs when the temperature is different. Therefore, the brightness may be measured, the temperature may be predicted from the measured brightness, the predicted temperature may be compared with a reference temperature (reference), and the ejection timing may be adjusted based on the comparison. The environmental condition predicted from the lightness may be temperature or humidity, or may be an environmental condition considering temperature and humidity. In addition, since the brightness change differs depending on the environmental condition, it can be said that the condition predicted from the brightness is the environmental condition. In addition, it is possible to adjust the ejection timing with high accuracy according to the environmental condition by using both the environmental condition predicted by the brightness measurement and the temperature condition detected by the temperature sensor.

=== Fifth Embodiment ===
In the fifth embodiment, the interval between the ejection timings of the background color ink and the color ink is adjusted by considering the humidity condition in addition to the temperature condition of the printing environment.

FIG. 14 shows a flow of specific operation in the ink ejection interval adjustment processing when both the temperature condition and the humidity condition are considered.
First, it is determined whether or not printing is performed in the background ink use mode (S501).
. When the background color ink use mode is selected, temperature detection is subsequently performed, and the temperature k of the printing environment is detected by the temperature sensor 55 (S502). Then, the preset reference temperature K is compared with the detected temperature k (S503).
If the detected temperature k is equal to or lower than the reference temperature K, the predicted humidity h and the reference humidity H are subsequently compared (S504). If the predicted humidity h is equal to or higher than the reference humidity H, the ink ejection interval is adjusted (S505). The specific method for adjusting the ink ejection interval is the same as in the first to third embodiments. The predicted humidity may be predicted by the same method as in the fourth embodiment, or the printer may include a humidity sensor, and the humidity detected by the humidity sensor may be used. However, by using the temperature detected by the temperature sensor and using the humidity predicted by measuring the lightness, it is not necessary to provide a humidity sensor, and the ink ejection environment can be adjusted with high accuracy according to environmental conditions. Is possible. In this case, what is predicted by the brightness measurement may be an environmental condition that is not limited to humidity.

Note that it is possible to reverse the order of the temperature condition comparison (S502 and S503) and the humidity condition comparison (S504). However, since the temperature condition has a greater influence on the ink drying time, it is preferable to compare the temperature condition first as shown in FIG.

<Effect of Fifth Embodiment>
According to the present embodiment, by considering the temperature condition and the humidity condition together, printing can be executed at a more appropriate ink ejection interval.

=== Sixth Embodiment ===
In the sixth embodiment, a line printer (printer 2) is used as a printing apparatus. The line printer is a printer that performs printing on a medium conveyed in a predetermined direction by ejecting ink from a head installed above the medium.

<About Printer 2>
FIG. 15 is a block diagram illustrating the overall configuration of the printer 2. FIG. 16 is a schematic diagram of the printer 2.
The printer 2 includes a transport unit 20, a head unit 40, a detector group 50, and a controller 60. The function of the controller 60 is almost the same as that of the printer 1 described above. Similarly to the printer 1, the computer 11 which is a control device at the time of printing.
Connected to 0. The computer 110 has a colorimeter 150 used for humidity prediction.
Is connected.

The transport unit 20 is for transporting a medium (for example, paper S) in a predetermined direction (hereinafter referred to as a transport direction). The transport unit 20 includes an upstream roller 26A and a downstream roller 26B, and a belt 27 (FIG. 16). When a conveyance motor (not shown) rotates, the upstream roller 26A and the downstream roller 26B rotate, and the belt 27 rotates. The fed paper S is conveyed by the belt 27 to a printable area (an area facing the head unit 40). The paper S being conveyed is electrostatically attracted or vacuum attracted to the belt 27.
A temperature sensor 55 is provided above the belt 27.

The head unit 40 is for ejecting ink onto a medium. The head unit 40 ejects ink onto the paper S being conveyed, thereby forming dots on the paper S and printing an image on the paper S. The head unit 40 can form dots for the paper width at a time. As a head unit, a background color ink head (W) 41 that ejects background color ink on the upstream side in the transport direction, and a color ink head (C, M, Y, K) that ejects CMYK color ink on the downstream side in the transport direction.
) 41 (FIG. 16).

FIG. 17 is an explanatory diagram of an arrangement of a plurality of small heads on the lower surface of the head 41. As shown in the figure, in the head 41, a plurality of small heads 43 are arranged in a staggered pattern along the paper width direction. Each small head 43 includes a nozzle row including a plurality of nozzles that eject ink. The plurality of nozzles in each nozzle row are arranged at a constant nozzle pitch along the paper width direction.

<About print processing>
In such a printer 2, when the controller 60 receives print data, first,
A paper feed roller (not shown) is rotated by the transport unit 20 so that the paper S to be printed is transferred to the belt 2.
7 Send on. The paper S is conveyed on the belt 27 without stopping at a constant speed, and passes under the head unit 40. While the paper S passes under the background color ink head (W) 41 of the head unit 40, the background color ink is intermittently ejected from each nozzle to form background color ink dots. That is, the dot formation process and the paper S transport process are performed simultaneously. The paper S on which the background color ink dots are formed is further conveyed downstream, and the color ink head (
C, M, Y, K) Color ink is ejected while passing under 41, and color ink dots are formed on the background color ink dots.
As a result, a dot row composed of a plurality of dots along the transport direction and the paper width direction is formed on the paper S, and an image is printed. Finally, the controller 60 discharges the paper S that has been printed.

<Adjustment of ink ejection interval>
Adjustment of the ejection interval between the background color ink and the color ink is performed by adjusting the medium conveyance speed. Other operations are the same as those in the above-described embodiments. That is, (S204) in FIG. 7 of the first to third embodiments, (S403) in FIG. 13 of the fourth embodiment, FIG.
Only the process of (S505) in 4 is different.

In the present embodiment, due to the characteristics of the printer 2 (line printer), settings such as waiting time between passes and unidirectional / bidirectional printing cannot be changed as in the first to fourth embodiments. Therefore, the time interval from when the background color ink is ejected to when the color ink is ejected is adjusted by slowing the medium conveyance speed, such as changing the rotation speed of the upstream and downstream rollers 26A and B for conveyance. The

For example, when temperature conditions and humidity conditions are considered, the detected temperature k (° C.) is the reference temperature K (° C.).
When the predicted humidity h (%) is equal to or higher than the reference humidity H (%), the CPU 6
No. 2 increases the medium conveyance speed by 0.5 times that during normal printing. Since the transport speed is slowed down, the paper S in FIG. 16 passes under the background color ink head (W) 41 to form the background color ink dots, and then the color ink heads (C, M, Y, K). Since the time until the color ink dots are formed after passing under 41 becomes long, the drying time of the background color ink dots formed earlier can be secured. The change rate of the conveyance speed is set so that the user can set an arbitrary magnification.
On the other hand, when the detected temperature k (° C.) is higher than the reference temperature K (° C.), or when the expected humidity h (%) is lower than the reference humidity H (%), the conveyance speed is not changed. That is, the ink ejection interval is not adjusted and normal printing is performed.

<Effects of Sixth Embodiment>
According to this embodiment, when overprinting background color ink and color ink using a line printer, the previously formed background color ink dots are dried and then placed on the background color ink dots. Color ink dots can be formed. As a result, it is possible to obtain a good printed image in which bleeding and color mixing are suppressed while shortening the printing time as much as possible.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention
Needless to say, the present invention includes equivalents thereof without departing from the spirit of the invention. In particular, the embodiments described below are also included in the present invention.

<About ink colors to be used>
In the above-described embodiment, an example in which recording is performed using four colors of CMYK as the color ink has been described. However, the present invention is not limited to this. For example, the present invention can also be applied to a case where recording is performed using inks of colors other than CMYK, such as light cyan, light magenta, and clear.

<About GLY contained in ink>
When at least one of the background color ink and the color ink contains GLY,
When a background image and a color image are overlaid, bleeding and color mixing may occur, so when overprinting the background color ink and the color ink, adjust the ink ejection interval to ensure the drying time. And it is sufficient. Of the background color ink and the color ink, even if only the ink to be overprinted later contains GLY, if the drying speed of the ink to be overprinted later is slow depending on the environmental conditions, the ink must be dried before drying. This is because color mixing with the ink on which dots are formed may occur. However, if the ink that forms dots earlier contains GLY, the ink that forms dots earlier does not contain GLY, and the ink that forms dots after overlapping contains GLY. Therefore, it is determined whether or not the ink for dot formation contains GLY first, and if it does, the ejection timing interval is adjusted. Therefore, the adjustment of the ejection timing interval may not be performed regardless of whether or not GLY is included in the ink for dot formation. Either the background color ink or the color ink may be dot-formed first. At least one color may be used as the color ink. When two or more colors are used, if the color ink contains GLY in at least one of the color inks used, the color ink contains GLY. Good. Further, when the ink contains GLY, if it contains at least GLY, bleeding or color mixing may occur when overprinting. Therefore, GLY is performed regardless of the GLY content rate.
If it contains, it is good also as containing GLY.

<Regarding the arrangement of nozzle rows>
In the above-described embodiment, the nozzle rows of the head portion are arranged in the order of CMYK. However, the present invention is not limited to this. For example, the order of the nozzle rows may be changed, or the number of nozzle rows for K ink may be greater than the number of nozzle rows for other inks.

<About the printer driver>
The printer driver processing may be performed on the printer side. In that case, a printer is constituted by the printer and the PC on which the driver is installed.

1 printer, 2 printer, 20 transport unit, 21 paper feed roller,
22 transport motor, 23 transport roller, 24 platen, 25 paper discharge roller,
26A upstream roller, 26B downstream roller, 27 belt,
30 Carriage unit, 31 Carriage, 32 Carriage motor,
40 head units, 41 heads, 411 case, 412 flow path unit,
412a flow path forming plate, 412b elastic plate, 412c nozzle plate,
412d pressure chamber, 412e nozzle communication port, 412f common ink chamber,
412g Ink supply path, 412h island part, 412i elastic film,
43 small head, 50 detector groups, 51 linear encoder,
52 Rotary encoder, 53 Paper detection sensor, 54 Optical sensor,
55 Temperature sensor, 60 controller, 61 interface part,
62 CPU, 63 memory, 64 unit control circuit,
110 Computer, 150 Colorimeter

Claims (7)

A background color ink nozzle row for ejecting a background color ink containing hollow polymer fine particles to form a background color ink dot on the medium; and
A color ink nozzle row for ejecting color ink to form color ink dots on the medium;
A control unit for controlling the ejection operation of the background color ink and the color ink;
A printing device comprising:
When the background color ink dots and the color ink dots are formed on the medium,
The controller is configured to determine an interval between the timing at which the background color ink is ejected and the timing at which the color ink is ejected.
Change according to the environmental conditions in which the background color ink and the color ink are ejected ,
Performing a comparison between the lightness measured for the background color ink dots or the environmental conditions predicted based on lightness and a predetermined standard;
The printing apparatus , wherein the control unit increases the interval according to the comparison result . The printing apparatus according to claim 1,
It has a temperature detector that detects the temperature,
When the temperature at the time of printing detected by the temperature detection unit is below a predetermined reference temperature,
The printing apparatus, wherein the control unit increases the interval. The printing apparatus according to claim 2,
In a printing apparatus that ejects the background color ink and the color ink while a head unit having the background color ink nozzle row and the color ink nozzle row moves in a scanning direction that intersects the conveyance direction of the medium.
If the detected temperature is below the reference temperature,
The control unit includes a first printing operation in which the head unit ejects the background color ink while moving in the scanning direction, and a second printing operation in which the head unit ejects the color ink while moving in the scanning direction. And a pause time between the two. The printing apparatus according to claim 2,
The background color ink nozzle row and the color ink nozzle row are installed at a position facing the medium, and the background color from the background color ink nozzle row and the color ink nozzle row while the medium is being carried in the carrying direction. In a printing apparatus for ejecting ink and the color ink,
If the detected temperature is below the reference temperature,
The control unit slows down the conveyance speed of the medium. The printing apparatus according to any one of claims 1 to 4,
The background color ink and the color ink are inks containing water as a main solvent,
The printing apparatus, wherein the medium is a medium that absorbs the water. The printing apparatus according to any one of claims 1 to 5,
At least one of the background color ink and the color ink contains glycerin. Ejecting a background color ink containing hollow polymer fine particles from a background color ink nozzle row to form a background color ink dot on the medium;
Ejecting color ink from the color ink nozzle row to form color ink dots on the medium;
When the background color ink dots and the color ink dots are formed on the medium,
An interval between the timing at which the background color ink is ejected and the timing at which the color ink is ejected,
Changing the background color ink and the color ink according to the conditions of the environment ,
The printing is characterized in that the lightness measured for the background color ink dots or the environmental condition predicted based on the lightness is compared with a predetermined standard, and the interval is lengthened according to the result of the comparison. Method.

Images