JP2011056868A - Printing apparatus, and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing apparatus which can suppress the deterioration of image quality. <P>SOLUTION: The printing apparatus has (A) a nozzle from which a dye ink of a certain color is delivered, (B) a nozzle from which a pigment ink of the certain color is ejected, (C) a sensor which outputs a signal corresponding to a temperature change of the ink, and (D) a control part (E) which prints an image by using both the dye ink and the pigment ink when the image including a certain color is printed, and prints the image by making larger a ratio of a delivering amount of the dye ink per unit area to a delivering amount of the pigment ink per unit area when the ink temperature is not higher than a threshold in comparison with the case that the ink temperature based on the output result of the sensor is higher than the threshold. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

As a printing apparatus, an ink jet printer (hereinafter referred to as a printer) that performs printing by ejecting ink from nozzles onto a medium such as paper or cloth is known. Ink used in a printer has a property that when the ink temperature (environment temperature of the printer) decreases, the ink viscosity increases and the amount of ink ejected from the nozzle decreases.
In view of this, there has been proposed a printer that adjusts parameters (voltage, etc.) of a drive waveform for causing ink to be ejected from a nozzle in accordance with the ink temperature. According to such a printer, the amount of ink discharged from the nozzle can be made constant regardless of the ink temperature, and a high-quality image can be printed.

Japanese Patent Laid-Open No. 11-20164

However, there is a limit to the ink discharge amount that can be corrected by adjusting the parameters of the drive waveform. For this reason, if the ink temperature drops significantly, the ink ejection amount cannot be corrected by adjusting the drive waveform parameters.
Further, in a printer that can eject dye ink and pigment ink of the same color, for example, in order to increase the printing speed, an image may be printed using both the dye ink and the pigment ink. Compared to dye ink, pigment ink has a large drop in ink discharge due to a drop in ink temperature. For this reason, when the ink temperature is lowered, the medium is particularly poorly filled with the pigment ink, and there is a possibility that white streaks or the like are generated in the image.
Therefore, an object of the present invention is to suppress image quality deterioration.

The main inventions for solving the above problems are (A) a nozzle from which a dye ink of a certain color is ejected, (B) a nozzle from which the pigment ink of a certain color is ejected, and (C) a temperature change of the ink. A sensor that outputs a corresponding signal; and (D) a control unit that prints the image using both the dye ink and the pigment ink when printing an image including the certain color. Compared with the case where the temperature of the ink based on the output result of the sensor is higher than the threshold value, the case where the temperature of the ink is equal to or lower than the threshold value per unit area with respect to the discharge amount of the pigment ink per unit area. A printing apparatus comprising: (E) a control unit that prints the image by increasing a ratio of the discharge amount of the dye ink.
Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

FIG. 1A is an overall configuration block diagram of a printing system, and FIG. 1B is a schematic perspective view of a printer. FIG. 2A is a diagram showing a nozzle arrangement on the lower surface of the head, and FIG. 2B is a diagram showing a head sensor provided on a relay substrate of the head. 3A is a diagram showing a change in the ink discharge amount with respect to the ink temperature, FIG. 3B is a diagram showing a driving waveform W, and FIG. 3C is a diagram showing a correction amount of the maximum potential with respect to the ink temperature. 4A is a diagram showing an image printed when the ink temperature is normal temperature, FIG. 4B is a diagram showing a monochrome image printed when the ink temperature is significantly lower than the normal temperature, and FIG. 4C is an ink temperature. It is a figure which shows the ink discharge amount fall by fall of this. 5A shows dots formed when the ink temperature is normal temperature, FIG. 5B shows dots formed when the ink temperature is lower than the threshold value, and FIG. 5C shows correction of the comparative example when the ink temperature is lower than the threshold value. The dot corrected by the method is shown. The dots corrected by the correction method of the present embodiment when the ink temperature is equal to or lower than the threshold value are shown. FIG. 7A is a table showing correction values of high gradation data with respect to ink temperature, FIG. 7B is another table showing correction values of high gradation data with respect to ink temperature, and FIG. 7C shows correction values of dot data with respect to ink temperature. It is a table to show. It is the figure which the dot formation position of pigment black ink and the dot formation position of dye black ink shifted in the movement direction. 9A and 9B are diagrams showing dots printed by a head in which the dye black nozzle row and the pigment black nozzle row are not shifted in the transport direction.

=== Summary of disclosure ===
At least the following will become apparent from the description of the present specification and the accompanying drawings.

That is, (A) a nozzle from which a dye ink of a certain color is ejected, (B) a nozzle from which the pigment ink of a certain color is ejected, (C) a sensor that outputs a signal corresponding to a temperature change of the ink, (D) a controller that prints the image using both the dye ink and the pigment ink when printing an image including a certain color, and the temperature of the ink based on the output result of the sensor The ratio of the discharge amount of the dye ink per unit area to the discharge amount of the pigment ink per unit area when the temperature of the ink is equal to or lower than the threshold value is higher than when the ink temperature is higher than the threshold value. A printing apparatus characterized by having a control unit that enlarges and prints the image, and (E).
According to such a printing apparatus, it is possible to increase the discharge amount of dye ink that has a high effect of improving the filling of the medium, and it is possible to suppress image deterioration due to a decrease in ink temperature.

In this printing apparatus, when the temperature of the ink is equal to or lower than the threshold value, the correction value for correcting the amount of the dye ink ejected per unit area is the pigment ejected per unit area. It must be larger than the correction value for correcting the ink amount.
According to such a printing apparatus, when the ink temperature becomes equal to or lower than the threshold value, the ratio of the discharge amount of the dye ink per unit area to the discharge amount of the pigment ink per unit area can be increased.

In such a printing apparatus, when the ink temperature is equal to or lower than the threshold value, the amount of the dye ink ejected per unit area is corrected, but the amount of the pigment ink ejected per unit area is Do not correct.
According to such a printing apparatus, when the ink temperature becomes equal to or lower than the threshold value, the ratio of the discharge amount of the dye ink per unit area to the discharge amount of the pigment ink per unit area can be increased.

In this printing apparatus, a nozzle row in which the plurality of nozzles ejecting the dye ink are arranged in a predetermined direction, a nozzle row in which the plurality of nozzles from which the pigment ink is ejected are arranged in the predetermined direction, and a medium By causing ink to be ejected from the nozzle row while relatively moving in a direction intersecting the predetermined direction, the dot row in which the dye ink dots are arranged in the intersecting direction and the dot in the pigment ink intersect Printing the image arranged in the predetermined direction with the dot rows arranged in the direction, and shifting the dot formation position of the dye ink and the dot formation position of the pigment ink in the intersecting direction.
According to such a printing apparatus, it is possible to improve the filling of the medium.

In this printing apparatus, a nozzle row in which the plurality of nozzles ejecting the dye ink are arranged in a predetermined direction, a nozzle row in which the plurality of nozzles from which the pigment ink is ejected are arranged in the predetermined direction, and a medium By causing ink to be ejected from the nozzle row while relatively moving in a direction intersecting the predetermined direction, the dye ink dots and the pigment ink dots are alternately arranged in the predetermined direction and the intersecting direction. Printing an image.
According to such a printing apparatus, it is possible to improve the filling of the medium.

In addition, the printing method of the printing apparatus includes a nozzle from which a dye ink of a certain color is ejected, a nozzle from which the pigment ink of a certain color is ejected, and a sensor that outputs a signal corresponding to a temperature change of the ink. When the image including the certain color is printed, the image is printed using both the dye ink and the pigment ink, and the temperature of the ink based on the output result of the sensor is higher than a threshold value. In contrast, when the ink temperature is equal to or lower than the threshold value, the ratio of the discharge amount of the dye ink per unit area to the discharge amount of the pigment ink per unit area is increased, and the image Is printed.
According to such a printing method, it is possible to increase the discharge amount of dye ink that has a high effect of improving the filling of the medium, and it is possible to suppress image deterioration due to a decrease in ink temperature.

=== About the printing system ===
The embodiment will be described by taking as an example a printing system in which an inkjet printer (hereinafter, printer 1) and a computer are connected.

  FIG. 1A is a block diagram of the overall configuration of a printing system in which the printer 1 and the computer 60 are connected, and FIG. 1B is a schematic perspective view of the printer 1. The printer 1 that has received the print data from the computer 60 that is an external device controls each unit (conveyance unit 20, carriage unit 30, head unit 40) by the controller 10, and forms an image on the paper S (medium). Further, the detector group 50 monitors the situation in the printer 1, and the controller 10 controls each unit based on the detection result.

  The controller 10 is a control unit for controlling the printer 1. The interface unit 11 is for transmitting and receiving data between the computer 60 as an external device and the printer 1. The CPU 12 is an arithmetic processing unit for controlling the entire printer 1. The memory 13 is for securing an area for storing a program of the CPU 12, a work area, and the like. The CPU 12 controls each unit by the control unit 14. The drive signal generation circuit 15 generates a drive signal COM for ejecting ink from the head 41 and transmits it to the head unit 40.

  The transport unit 20 is for transporting the paper S by a predetermined transport amount in the transport direction (predetermined direction) during printing after the paper S is sent to a printable position. The carriage unit 30 is for moving the head 41 in a direction crossing the transport direction (hereinafter referred to as a movement direction). The head unit 40 is for ejecting ink onto the paper S and has a head 41.

  FIG. 2A is a diagram showing a nozzle arrangement on the lower surface of the head 41, and FIG. 2B is a diagram showing a head sensor 51 provided on the relay substrate 42 of the head 41. A number of nozzles for ejecting ink are provided on the lower surface of the head 41. Each nozzle is provided with a pressure chamber (not shown) containing ink and a piezo element (driving element) for discharging ink by changing the capacity of the pressure chamber.

  The printer 1 according to the present embodiment can discharge yellow, magenta, cyan, and black dye inks and black pigment ink. Therefore, on the lower surface of the head 41 shown in FIG. 2A, a yellow nozzle row Yd that discharges yellow dye ink, a magenta nozzle row Md that discharges magenta dye ink, and a cyan nozzle row Cd that discharges cyan dye ink A dye black nozzle row Kd for discharging black dye ink and a pigment black nozzle row Kp for discharging black pigment ink are formed. Each nozzle row is composed of 180 nozzles (# 1 to # 180). In each nozzle row, the nozzles are arranged at a constant interval D (for example, 180 dpi) in the transport direction. The positions of the four color dye ink nozzle rows (Yd, Md, Cd, Kd) in the carrying direction are the same, but the four color dye ink nozzle rows and the pigment black nozzle row Kp are located at the nozzle pitch D in the carrying direction. Is shifted by half. For example, with respect to the nozzle # 1 on the most downstream side of the dye black nozzle row Kd, the nozzle # 1 on the most downstream side of the pigment black nozzle row Kp is positioned downstream in the transport direction by a half nozzle pitch. It should be noted that the nozzles belonging to each nozzle row are numbered in ascending order from the downstream nozzle in the transport direction (# 1 to # 180).

  Further, as shown in FIG. 2B, a head sensor 51 is provided on the relay substrate 42 of the head 41. The controller 10 can acquire the ambient temperature around the head 41 by the head sensor 51.

  In such a printer 1, a dot forming process for forming a dot row (raster line) along the moving direction on the paper S by intermittently discharging ink from the head 41 moving along the moving direction, and the paper S And the carrying process of carrying in the carrying direction are repeated alternately. As a result, dots can be formed at positions different from the positions of the dots formed by the previous dot formation processing, and a two-dimensional image can be printed on the paper S. Hereinafter, one operation (image forming operation) in which the head 41 moves in the moving direction to form an image is referred to as “pass”.

=== About Dye Ink and Pigment Ink ===
The printer 1 can discharge two types of ink (dye ink and pigment ink) with respect to black. Dye inks can print glossy images, but they have the property of being easy to bleed, and pigment inks are difficult to bleed and can express a strong black color (deep), but because the coloring material remains on the surface of the medium The image has a property that glossiness is difficult to appear.

  Therefore, the printer 1 uses the pigment black ink Kp when printing a black text image (when printing an image on plain paper). By doing so, it is possible to prevent text from being crushed due to blurring, and to print a text document with a high density of black and easy to read. On the other hand, when printing a color image such as a photograph (when printing an image on glossy paper), the dye black ink Kd (and the color dye ink YdMdCd) is used. By doing so, a glossy image can be printed.

  Further, on plain paper on which a text image is printed, not only an image using pigment ink but also an image using dye ink can be printed. On the other hand, when an image made of pigment ink is printed on glossy paper on which a color image is printed, a large amount of pigment ink color material stays on the medium surface, resulting in unevenness on the image surface, making it impossible to print a glossy image. That is, pigment ink is not suitable as ink for printing an image on glossy paper.

  Therefore, in the printer 1, when monochrome printing is performed on plain paper (when a monochrome text image is printed), the “clean mode” and the “fast mode” can be set by the user. Then, the black ink to be used is changed according to the mode selected by the user. When “clean mode” is selected, an image is printed using only the pigment black nozzle row Kp. By doing so, it is possible to print a black text document having a dark density without blur.

  On the other hand, when the “fast mode” is selected, an image is printed using both the pigment black ink Kp and the dye black ink Kd. By doing so, the image can be printed by the two nozzle rows of the pigment black nozzle row Kp and the dye black nozzle row Kd (because the number of nozzles for printing the image is increased), so the printing time can be shortened. . In the head 41 shown in FIG. 2A, since the positions in the transport direction of the pigment black nozzle row Kp and the dye black nozzle row Kd are shifted by a half nozzle pitch, a high-resolution image can be printed quickly. It should be noted that not only when monochrome printing is performed on plain paper, but also when printing an image including black on plain paper, whether only the pigment black nozzle row Kp is used, or the pigment and It may be possible to select whether to use both of the dye black nozzle rows Kp and Kd.

=== Correction of Ink Ejection Amount by Ink Temperature ===
FIG. 3A is a diagram showing a change in the ink ejection amount Iw (ink weight) with respect to the ink temperature Ti, FIG. 3B is a diagram showing a driving waveform W for ejecting ink from the nozzle, and FIG. It is a figure which shows correction amount (DELTA) Vh of the highest electric potential Vh with respect to temperature Ti. The ink used in this embodiment has a property that the viscosity of the ink increases when the ink temperature Ti decreases, and the viscosity of the ink decreases as the ink temperature Ti increases. This property is the same for both dye ink and pigment ink. The higher the viscosity of the ink, the more difficult it is to eject ink from the nozzle, and the lower the viscosity of the ink, the easier it is to eject ink from the nozzle. Therefore, when the same force (driving waveform W) is applied to the pressure chamber communicating with the nozzle and filled with ink and the ink is ejected from the nozzle, as shown in FIG. As the ink discharge amount Iw increases and the ink temperature Ti decreases, the ink discharge amount Iw from the nozzle decreases.

  As described above, when the ink discharge amount Iw from the nozzle fluctuates due to the ink temperature Ti, it becomes impossible to form dots of a specified size due to the environmental temperature of the printer 1 or the like. As a result, the print image quality deteriorates. Therefore, in this embodiment, the drive waveform W (FIG. 3B) generated in the drive signal COM for ejecting ink from the nozzles is corrected according to the ink temperature Ti.

  The drive waveform W shown in FIG. 3B includes a first expansion element S1 that increases in potential from the intermediate potential Vc to the maximum potential Vh, a first hold element S2 that holds the maximum potential Vh, and a potential from the maximum potential Vh to the minimum potential Vl. A contraction element S3 that lowers, a second hold element S4 that holds the lowest potential Vl, and a second expansion element S5 that increases the potential from the lowest potential Vl to the intermediate potential Vc.

  The volume of the pressure chamber when the intermediate potential Vc is applied to the piezo element (drive element) is defined as a reference volume. When the first expansion element S1 of the drive waveform W is applied to the piezo element, the piezo element contracts in the longitudinal direction, and the volume of the pressure chamber expands. When the first hold element S2 is applied to the piezo element, the contracted state of the piezo element is maintained, and accordingly, the expanded state of the pressure chamber is also maintained. Next, when the contraction element S3 is applied to the piezo element, the piezo element expands at a stretch from the contracted state, and the volume of the pressure chamber contracts at a stretch. Due to the contraction of the pressure chamber, the ink pressure in the pressure chamber rapidly increases, and ink droplets are ejected from the nozzles. After the second hold element S4 is applied to the piezo element and the expansion state of the piezo element and the contraction state of the pressure chamber are maintained for a while, the second expansion element S5 is applied to the piezo element, and the volume of the pressure chamber becomes the reference volume. Return.

  In the present embodiment, in order to make the ink discharge amount Iw constant regardless of the ink temperature Ti, the highest potential Vh among the parameters constituting the drive waveform W is corrected. The controller 10 acquires the ink temperature Ti, and causes the drive signal generation circuit 15 to generate a drive waveform W (drive signal COM) having the highest potential Vh according to the ink temperature Ti. Here, the drive waveform W used when the ink temperature Ti is normal temperature (25 ° C.) is set as the reference drive waveform W, and the maximum potential Vh of the reference drive waveform W is corrected with respect to the ink temperature Ti.

  When the ink temperature Ti is lower than the normal temperature (25 ° C.) and the ink discharge amount Iw decreases, it is necessary to increase the ink discharge amount Iw. Therefore, when the ink temperature Ti is low, as shown in FIG. 3C, the maximum potential of the drive waveform W is corrected to a potential Vh + ΔVh that is higher than the reference maximum potential Vh. Here, it is assumed that parameters of the drive waveform W other than the maximum potential Vh are not corrected. In this way, by correcting the maximum potential of the drive waveform W to the high potential Vh + ΔVh, the pressure chamber can be expanded more than the reference drive waveform W. As a result, since the contraction rate of the pressure chamber (the volume difference between the pressure chambers during expansion and contraction) can be increased, the ink discharge amount Iw from the nozzle (pressure chamber) can be increased.

  On the contrary, when the ink temperature Ti is higher than the normal temperature and the ink discharge amount Iw increases, it is necessary to reduce the ink discharge amount Iw. Therefore, when the ink temperature Ti is high, the maximum potential of the drive waveform W is corrected to a potential Vh−ΔVh that is lower than the reference maximum potential Vh. As a result, since the shrinkage rate of the pressure chamber can be reduced, the ink discharge amount Iw from the nozzle can be reduced. In addition, the maximum potential Vh of the drive waveform W is not corrected according to the ink temperature Ti, but another parameter of the drive waveform W may be corrected as long as the ink discharge amount Iw can be corrected.

  FIG. 4A is a diagram showing a monochrome image printed in the “fast mode” when the ink temperature Ti is normal temperature (25 ° C.), and FIG. 4B is “high” when the ink temperature Ti is significantly lower than the normal temperature. It is a figure which shows the monochrome image printed by mode. As described above, when a monochrome image (text image) is printed on plain paper and “fast mode” is selected, both the dye black nozzle row Kd and the pigment black nozzle row Kp are used. The image is printed. Assume that one square in the drawing is a pixel, and print data indicates that dots of a prescribed size are formed in all pixels. Here, the dot diameter of the prescribed size is set to be approximately the same as the length of one pixel.

  When the ink temperature Ti is normal temperature (25 ° C.), as shown in FIG. 4A, dots of a prescribed size are formed on all pixels, and the medium is pigment black ink dots (Kp dots / black dots) and dye black ink. The dots (Kd dots / hatched dots) are filled with no gaps. Since the dye ink is more likely to spread than the pigment ink, the dot diameter of the dye ink is larger than the dot diameter of the pigment ink even if the same ink amount is ejected to one pixel. Therefore, in the drawing, in order to make the dot diameter of the dye black ink Kd equal to the dot diameter of the pigment black ink Kp, the discharge amount (X-αpl) of the dye black ink Kd for one pixel is set to the pigment black ink for one pixel. The discharge amount is smaller than the discharge amount (Xpl) of Kp.

  As the ink temperature Ti deviates from the normal temperature (25 ° C.), the ink discharge amount Iw decreases or the ink discharge amount Iw increases. That is, it is necessary to increase the correction amount of the ink discharge amount Iw as the ink temperature Ti becomes farther from the normal temperature. Therefore, as shown in FIG. 3C, the maximum potential Vh is corrected to be higher as the ink temperature Ti is lowered, and the maximum potential Vh is corrected to be lower as the ink temperature Ti is increased. However, the maximum potential Vh (correction amount ΔVh) does not increase when the ink temperature Ti is 10 ° C. In the figure, the limit value (maximum value) of the corrected maximum potential Vh + Δh is 34V.

  This is because there is a limit to the amount of high-viscosity ink that can be ejected from a nozzle of a certain size even if the maximum potential Vh is corrected to be high. That is, when the ink temperature Ti is 10 ° C. or less, even if the ink is ejected from the nozzle with the driving waveform W having the maximum potential Vh higher than 34V (limit value) (34V + α), the ink ejection amount Iw can be reduced. Cannot be increased (cannot achieve the specified ink discharge amount). Further, when a potential (34V + α) that is significantly higher than the reference maximum potential (28V in FIG. 3C) is applied to the piezo element, there is a possibility that the life of the piezo element may be shortened or the piezo element may be destroyed. Therefore, when the ink temperature Ti is significantly lower than the normal temperature (25 ° C.), that is, when the ink temperature Ti is equal to or lower than a threshold value (eg, 10 ° C.), the drive waveform W is reduced even if the ink temperature Ti further decreases. The maximum potential Vh is constant (limit value, 34V).

  FIG. 4C is a diagram illustrating a decrease in the discharge amount of the dye ink and the pigment ink due to a decrease in the ink temperature Ti. The horizontal axis indicates the ink temperature Ti, and the vertical axis indicates the ink discharge amount Iw (ink weight). “Dotted line” indicates the change in ink discharge amount when dye ink is ejected from the nozzle with a constant drive waveform regardless of the ink temperature, and “dotted line” indicates the change from the nozzle with a constant drive waveform regardless of the ink temperature. A change in ink discharge amount when pigment ink is discharged is shown. The drive waveform for ejecting ink from the nozzle is a drive waveform W suitable for dye ink and pigment ink, and a drive waveform designed to eject a specified ink amount at room temperature. As shown in FIG. 4C, when the ink temperature Ti is near room temperature (25 ° C.), there is almost no difference in the discharge amount of the dye ink and the pigment ink, but when the ink temperature Ti is greatly reduced from the threshold (around 10 ° C.), the dye The amount of pigment ink discharged is smaller than the amount of ink discharged. That is, the reduction rate of the pigment ink discharge amount due to the decrease in the ink temperature Ti is larger than the decrease rate of the dye ink discharge amount due to the decrease in the ink temperature Ti.

  In the adjustment of the maximum potential Vh of the drive waveform W, there is a limit to the correction of the ink discharge amount. As shown in FIG. 3C described above, when the ink temperature Ti is equal to or lower than the threshold (10 ° C. or lower), It becomes impossible to correct by W. For this reason, in a dye ink having a small rate of decrease in the ink discharge amount with respect to the decrease in the ink temperature Ti, the difference between the ink discharge amount and the specified ink amount remains relatively small even when the ink temperature Ti is equal to or lower than the threshold. On the other hand, in a pigment ink having a large decrease rate of the ink discharge amount with respect to the decrease in the ink temperature Ti, the difference between the ink discharge amount and the specified ink amount becomes large when the ink temperature Ti is equal to or lower than the threshold value.

  As a result, as shown in FIG. 4B, in the image formed when the ink temperature Ti is equal to or lower than the threshold, the dots of the dye black ink Kd are slightly smaller than the dots of the prescribed size (FIG. 4A). However, the dot of the pigment ink Kp is significantly smaller than the dot of the specified size. For this reason, in the printed image, the surrounding medium on which the dots of the pigment black ink Kp are formed is particularly poorly filled, and white stripes are generated in the image. Further, the black ink has higher visibility than the color ink, and the poorly filled portion of the medium is conspicuous, and the degree of image quality deterioration increases.

That is, when the ink temperature Ti is significantly lower than the normal temperature and becomes equal to or lower than the threshold (10 ° C.), the ink discharge amount Iw cannot be corrected by the correction of the drive waveform W, and in particular, the discharge amount of the pigment ink (pigment black ink Kp). Is reduced, the medium of the printed image is poorly filled (the image density is light), and the image quality is deteriorated.
Therefore, the present embodiment aims to suppress image quality deterioration even when the ink temperature Ti is significantly lower than the normal temperature and the ink discharge amount (particularly, the discharge amount of the pigment black ink Kp) is reduced. And

=== Regarding Correction Method of Ink Discharge Amount ===
FIG. 5A shows dots formed when the ink temperature Ti is normal temperature (25 ° C.), FIG. 5B shows dots formed when the ink temperature Ti is equal to or lower than the threshold (5 ° C.), and FIG. The dots formed based on the print data corrected by the correction method of the comparative example when the ink temperature Ti is equal to or lower than the threshold value are shown. An example is a printing method in which dots of the dye black ink Kd and dots of the pigment black ink Kp are formed on a unit area composed of 24 pixels (6 × 4), with one square in the figure as a pixel. .

  Here, the creation of print data for the printer 1 to perform printing will be briefly described. In the printing system of this embodiment (FIG. 1A), a printer driver is installed in the computer 60 connected to the printer 1, and when the printer driver receives a print command and image data from various application programs, it creates print data.

  The printer driver first converts the resolution of the image data received from the application program into a print resolution. Next, the printer driver converts the image data, which is RGB data, into high gradation data S corresponding to the ink colors (Yd, Md, Cd, Kd, Kp) used for printing by color conversion processing. Thereafter, the printer driver converts the high gradation data S into low gradation data (data indicating dot on / off) that can be formed by the printer 1 by halftone processing. Finally, the printer driver rearranges the matrix-like image data in the order to be transferred to the printer 1 by rasterization processing, and transmits the image data together with the command data to the printer 1. Then, the printer 1 performs printing based on the print data received from the printer driver.

  The printer driver performs, by color conversion processing, yellow high gradation data S (Yd), magenta high gradation data S (Md), cyan high gradation data S (Cd), and dye black for each pixel constituting the image data. High gradation data S (Kd) and pigment black high gradation data S (Kp). In FIGS. 5A and 5B in which correction according to the ink temperature Ti is not performed, the high gradation data S (Kd) of the dye black ink Kd of each pixel belonging to the unit region (6 × 4 pixels) indicates “100”. Assume that the high gradation data S (Kp) of the pigment black ink Kp indicates “100”. The high gradation data S indicates the density of the pixel. It is assumed that the higher the gradation value, the higher the density, and the smaller the gradation value, the lighter the density.

  In addition, the printer 1 of the present embodiment can form three types of dots (large dot, medium dot, and small dot). For low gradation data after halftone processing (hereinafter, dot data), for each pixel, It indicates whether or not each ink (YMCKdKp) dot is to be formed on a pixel, and also indicates the size of the dot formed on that pixel. In FIG. 5A and FIG. 5B, as a result of halftone processing of the high gradation data (100) of the pigment black ink Kp and the high gradation data (100) of the dye black ink Kd, the printer driver has six pigments in the unit area. Medium dots of black ink Kp and medium dots of six dye black inks Kd are formed.

  As shown in FIG. 5A, if the ink temperature Ti is room temperature (25 ° C.), a medium-sized dot can be formed. However, as shown in FIG. 5B, the ink temperature Ti is less than the threshold value (5 ° C. or less). If there is, the correction of the maximum potential Vh of the drive waveform W cannot correct the ink discharge amount, and a medium dot smaller than the prescribed size is formed. In this case, the medium is poorly filled and the image quality deteriorates (the density becomes light).

  Therefore, in the correction method of the comparative example (FIG. 5C), the high gradation data S (Kd) and S (Kp) indicated by each pixel are corrected to a high gradation value (dark gradation value). In the comparative example, the tone value S (Kd) of the dye black ink before correction and the tone value S (Kp) of the pigment black ink are corrected at the same ratio (the same correction value). For example, if the correction value is “10%”, the tone values S (Kd) and S (Kp) before correction of dye black and pigment black are both “100”, and thus the tone value S (( Kd) ′ and S (Kp) ′ are both corrected to “110”.

  As a result of halftoning the data S (Kd) ′ and S (Kp) ′ corrected to high gradation values (dark gradation values) in this way, as shown in FIG. 5C, dye black ink Kd and pigment black ink Kp , 5 medium dots and 1 large dot are formed. That is, for the image with the gradation value (100) before correction (FIG. 5B), the image with the gradation value (110) after correction (FIG. 5C) has six dots formed by each ink KdKp. Of these, correction was made so that the size of one dot was increased. Therefore, compared with the image before correction (FIG. 5B), the corrected image of the comparative example (FIG. 5C) can improve the poorness of the medium filling.

  However, as shown in FIG. 4C described above, the pigment black ink Kp has a higher rate of decrease in the ink discharge amount due to the decrease in the ink temperature Ti than the dye black ink Kd. Therefore, in the pigment black ink Kp, the size of the large dot is small and the enlargement ratio from the medium dot to the large dot is also small compared to the dye black ink Kd. That is, even if correction for enlarging the dot size is performed to improve the poor filling of the medium (even if the medium dot is changed to the large dot), the pigment black ink Kp has a larger dot than the large dot of the dye black ink Kd. The large dot has a small area for filling the medium and a small correction area (an area for newly filling the medium). That is, when the ink temperature Ti is equal to or lower than the threshold value, the pigment black ink Kp has a lower increase rate of the ink discharge amount with respect to the increase in the high gradation data than the dye black ink Kd, and has the effect of improving the poor filling of the medium. small.

  Nevertheless, in the correction method of the comparative example (FIG. 5C), the high gradation data of the pigment black ink Kp and the high gradation data of the dye black ink Kd are corrected with the same correction value (same ratio) (100). → 110), the correction of the discharge amount of the pigment black ink Kp cannot completely improve the poor filling of the medium.

  Therefore, in this embodiment, in order to correct the ink discharge amount that cannot be corrected by the drive waveform W because the ink temperature Ti is equal to or lower than the threshold value, the correction value for the high gradation data S (Kp) of the pigment black ink Kp is The correction value for the high gradation data S (Kd) of the dye black ink Kd is increased.

  FIG. 6 shows dots formed based on the print data corrected by the correction method of the present embodiment when the ink temperature Ti is equal to or lower than the threshold value. In FIG. 6, the correction value for the high gradation data S (Kp) of the pigment black ink is set to “0%” in order to compensate for the ink discharge amount that cannot be corrected by adjusting the drive waveform W because the ink temperature Ti is below the threshold value. The correction value for the high gradation data S (Kd) of the dye black ink is “20%”. That is, when the ink temperature Ti is equal to or lower than the threshold value, the discharge amount of the pigment ink with a large decrease in the ink discharge amount with respect to the ink temperature Ti is not corrected, and the discharge of the dye ink with the small decrease in the ink discharge amount with respect to the ink temperature Ti is performed. Correct so that the amount increases.

  As a result, since the high gradation data S (Kp) of the pigment black ink before correction is “100”, the high gradation data S (Kp) ′ of the pigment black ink after correction is also “100”. Therefore, similarly to the unit area (FIG. 5B) printed based on the high gradation data S (Kp) before correction (without correction), printing is performed based on the corrected high gradation data S (Kp) ′. Six medium dots of the pigment black ink Kp are formed in the unit region (FIG. 6).

  On the other hand, the high gradation data S (Kd) of the dye black ink before correction is “100”, and the high gradation data S (Kd) ′ of the dye black ink after correction is “120”. Therefore, two large dots and five medium dots of the dye black ink Kd are formed in the unit area (FIG. 6) printed based on the corrected high gradation data S (Kd) '. In the correction method of the present embodiment, the high gradation data (ink discharge amount) of the pigment black ink Kp is not corrected, so that the high gradation data S (Kd) of the dye black ink Kd is compared with the correction method of the comparative example (FIG. 5C). ) Is increased (20%> 10%). Therefore, in the unit region (FIG. 6) printed based on the corrected high gradation data of this embodiment, compared to the unit region (FIG. 5C) printed based on the corrected high gradation data of the comparative example. The number of dots of the dye black ink Kd is increased or the dot size is increased.

  The dye black ink Kd has a lower rate of decrease in the ink discharge amount with respect to the decrease in the ink temperature Ti than the pigment black ink Kp (FIG. 4C). For this reason, the difference between the dot size formed when the ink temperature Ti is equal to or lower than the threshold (eg, 5 ° C.) and the specified dot size is small. Therefore, the ink temperature Ti becomes below the threshold value, and the ink discharge amount shortage (particularly the black discharge amount of the pigment black ink Kp) that cannot be corrected by adjusting the drive waveform W is increased, and the number of dots and the dot size of the dye black ink Kd are increased. This can be compensated. As a result, even if the ink temperature Ti becomes lower than the threshold value (10 ° C. or lower) and the ink discharge amount deficiency cannot be corrected by adjusting the drive waveform W, the poor filling of the medium (decrease in image density) can be improved, and the image quality Deterioration can be suppressed.

  That is, in the present embodiment, when the ink temperature Ti is higher than the threshold value, the number of dots and the dot size of the dye black ink Kd formed in the unit region, and the number of dots and the dots of the pigment black ink Kp formed in the same unit region. Even if the size is the same (both 6 medium dots), when the ink temperature Ti falls below the threshold, the number of dots of the dye black ink Kd formed in the unit area is made larger than the number of dots of the pigment black ink Kd, The dot size of the dye black ink Kd formed in the unit area is made larger than the dot size of the pigment black ink Kp. By doing so, the poor filling of the medium due to the decrease in the ink temperature Ti is corrected.

  If the ink temperature Ti falls below the threshold value, it is assumed that the dot size is increased by increasing the number of dots of the pigment black ink Kp instead of the dye black ink Kd (the number of medium dots is increased, Suppose the dot is corrected to a large dot). However, since the pigment black ink Kp has a large drop in ink discharge amount with respect to the drop in the ink temperature Ti, when the ink temperature Ti is equal to or lower than the threshold, the medium dots of the pigment black ink Kp are the medium dots (of the prescribed size). Smaller than (medium dot). Therefore, even if the number of small dots of the pigment black ink Kp is increased, the effect of improving the poor filling of the medium is low. Similarly, when the ink temperature Ti is equal to or lower than the threshold value, even if the medium dot of the pigment black ink Kp is enlarged to a large dot, the dot enlargement ratio is increased as the medium dot of the dye black ink Kd is enlarged to a large dot. Cannot be done (the area of the newly filled medium is small). Therefore, even if the dot size of the pigment black ink Kp is increased, the effect of improving the poor filling of the medium is low.

  Therefore, in the present embodiment, when the ink temperature Ti is equal to or lower than the threshold value, the high gradation of the dye black ink with respect to the high gradation data S (Kp) of the pigment black ink is compared with when the ink temperature Ti is higher than the threshold value. Correction is performed so that the ratio of the data S (Kd) is increased (100/100 = 1 → 120/100 = 1.2). In other words, the controller 10 (control unit) of the printer 1 (printing apparatus) performs “the dye black ink Kd per unit area relative to the discharge amount of the pigment black ink Kp per unit area” when the ink temperature Ti is higher than the threshold value. The ratio of the discharge amount of the pigment black ink Kp per unit area when the ink temperature Ti is equal to or less than the threshold than the ratio of the discharge amount (6 medium dots of dye / 6 medium dots of pigment). The ratio of the discharge amount of the dye black ink Kd (2 large dye dots, 5 medium dots / 6 medium pigment dots) is increased, and the image is printed.

  By doing so, even when the ink discharge amount cannot be corrected by adjusting the drive waveform W when the ink temperature Ti is equal to or lower than the threshold value, the discharge of the dye black ink with a small decrease rate of the ink discharge amount due to the decrease in the ink temperature Ti is performed. Since the amount increases, the poor filling of the medium (lightness of image density) can be improved. As a result, image quality deterioration can be suppressed.

  Therefore, in the present embodiment, when a text image is printed on plain paper in a fast mode, that is, when printing is performed using both the pigment black ink Kp and the dye black ink Kd, the printer driver The ink temperature Ti is acquired from the printer 1 during the creation of the print data, and the data S (Kp) is obtained with the high gradation data S (Kd) of the dye black ink Kd and the high gradation of the pigment black ink Kp according to the ink temperature Ti. ) Is corrected.

  Note that the temperature Ti of the ink ejected from the nozzles is affected by the ambient temperature of the head 41. Therefore, in the present embodiment, the temperature detected by the head sensor 51 provided on the relay substrate 42 of the head 41 shown in FIG. 2B is referred to as “ink temperature Ti (of pigment black and dye black)”. That is, the head sensor 51 corresponds to a sensor that outputs a signal corresponding to a change in ink temperature. However, the ink temperature Ti is not limited to the result output by the head sensor 51 on the head substrate, and the result of measuring the actual ink temperature in the head 41 may be used as the ink temperature Ti or the temperature of the ink in the ink cartridge. The result of the measurement may be the ink temperature Ti.

  Also, here, the printer driver indicates the media type (plain paper or glossy paper) indicated by the print data, or the data type (text or image), and the mode selected by the user (quick mode or clean mode). Thus, the ink (pigment black ink Kp, dye black ink kd) used for printing is determined. However, not limited to this, the controller 10 of the printer 1 may determine the ink used for printing.

  FIG. 7A is a table showing correction values of high gradation data (S) with respect to ink temperature Ti. After acquiring the high gradation value data of each of the three dye inks (YMC), dye black, and pigment black, the printer driver uses both the pigment black ink Kp and the dye black ink Kd (eg, plain paper, If the ink temperature Ti is acquired from the printer 1 in a text image (when the fast mode is selected) and the ink temperature Ti is larger than the threshold (Ti> 10 ° C.), the high gradation data S (for the pigment black ink Kp) Kp) and high gradation data S (Kd) of the dye black ink are determined not to be corrected, and the next halftone process is performed.

  On the other hand, in the printer driver, the ink temperature Ti acquired from the printer 1 is equal to or lower than the threshold (10 ° C. ≧ Ti), the high gradation data S (Kp) of the pigment black ink Kp, and the high gradation data S (Kd) of the dye black ink If it is determined that correction is necessary, the correction of the high gradation data is performed with reference to the correction value table of FIG. 7A. The correction value table of FIG. 7A is stored in the memory of the computer 60, and the ink temperature Ti is classified into a plurality of ranges, and for each range, the correction value ΔSd for the high gradation data S (Kd) of the dye black ink. The correction value ΔSp for the high gradation data S (Kp) of the pigment black ink is set. When the ink temperature Ti is higher than the threshold value (Ti> 10 ° C.), it is not necessary to correct the high gradation data of dye black and pigment black, so the correction value ΔSdΔSp is set to zero.

  When the ink temperature Ti is higher than 5 ° C. and equal to or lower than 10 ° C. (10 ° C. ≧ Ti> 5 ° C.), the printer driver does not correct the high gradation data S (Kp) of the pigment black ink (ΔSp = 0). ), The high gradation data S (Kd) of the dye black ink is corrected to a gradation value 10% higher than the gradation value (S (Kd) ′ = S (Kd) × 1.1). Similarly, when the ink temperature Ti is 5 ° C. or less (5 ° C. ≧ Ti), the printer driver does not correct the high gradation data S (Kp) of the pigment black ink (ΔSp = 0), and the higher order of the dye black ink. The tone data S (Kd) is corrected to a tone value that is 20% higher than the tone value (S (Kd) ′ = S (Kd) × 1.2). In this way, the printer driver performs halftone processing on the high gradation data corrected in accordance with the ink temperature Ti.

  As described above, when the ink temperature Ti is equal to or lower than the threshold value, the high gradation data S (Kd) of the dye black ink is corrected to a high gradation value (dark gradation value), but the high gradation data S (Kp) of the pigment black ink is corrected. Is not corrected. That is, the correction value for the discharge amount of the dye ink per unit area (for example, + 10%) is set larger than the correction value for the discharge amount of the pigment ink per unit area (for example, 0%). By doing so, compared to when the ink temperature Ti is higher than the threshold value, the discharge amount of the pigment black ink Kp per unit area (high gradation data S (Kp)) when the ink temperature Ti is lower than the threshold value. ), The ratio of the discharge amount of the dye black ink Kd per unit area (high gradation data S (Kd)) can be increased. As a result, the dye black ink Kd having a small ink discharge amount reduction rate with respect to the ink temperature Ti can correct the poor filling of the medium due to the decrease in the ink temperature Ti, and the image quality deterioration can be suppressed.

  Further, since the ink discharge amount decreases as the ink temperature Ti decreases, it is necessary to correct the high gradation data S (Kd) of dye black to a higher gradation value, that is, to increase the discharge amount of dye black ink. There is. Therefore, in the correction value table of FIG. 7A, the ink temperature Ti below the threshold is divided into two stages, and the lower the ink temperature Ti, the larger the correction value ΔSd for the high-tone data S (Kd) of dye black ( 20%> 10%). By doing so, image quality degradation can be suppressed regardless of the ink temperature Ti.

  The printer driver installed in the computer 60 connected to the printer 1 does not necessarily create print data, but the controller 10 of the printer 1 creates print data and corrects the high gradation data according to the ink temperature Ti. May be. In addition, when an image is printed using only the dye black ink Kd (or pigment black ink Kp), when the ink temperature Ti is equal to or lower than the threshold value, the unused pigment black ink Kp (or dye) is used. The ink discharge amount may be corrected by the black ink Kd). Further, the ink discharge amount that cannot be corrected by adjusting the drive waveform W may be corrected by forming black (composite black) dots by superimposing three-color dye inks (Yd, Md, Cd).

<Modification>
FIG. 7B is another table showing the correction value of the high gradation data S with respect to the ink temperature Ti. In the above-described embodiment (FIG. 7A), when the ink temperature Ti is equal to or lower than the threshold value, the high gradation data S (Kd) of the dye black is corrected (although it is corrected to a dark gradation value), the higher order of the pigment black. Although the tone data S (Kp) is not corrected, the present invention is not limited to this, and the high gradation data S (Kp) of pigment black may be corrected according to the ink temperature Ti. However, the correction value ΔSd of the dye black ink is set larger than the correction value ΔSp of the pigment black ink (for example, ΔSd = 10%> ΔSp = 5%). By doing so, it is possible to further increase the discharge amount of the dye black ink (that is, the dye black ink having a high correction effect on the filling of the medium) with a small decrease rate of the ink discharge amount with respect to the drop of the ink temperature Ti, and the filling of the medium Can be reliably corrected. Further, the high gradation data S (Kd) of the pigment black is corrected to a low gradation value (light gradation value), and instead, the high gradation data S (Kd) of the dye black having a good medium filling is changed to a high gradation value. You may correct | amend to (dark gradation value).

  FIG. 7C is a table showing dot data correction values for the ink temperature Ti. In the above-described embodiment, the high gradation data is corrected according to the ink temperature Ti. However, the present invention is not limited to this, and on / off data (hereinafter, dot data) of the dot after halftone processing may be corrected. In the dot data, whether or not to form each dot of five types of ink (YdMdCdKdKp) and the dot size to be formed are indicated for each pixel. The printer 1 of the present embodiment can form three types of size dots (large dots, medium dots, and small dots). When the ink temperature Ti is equal to or lower than the threshold value, the dot data of the pixel on which the dot of the dye black ink Kd is formed may be corrected so that a dot having a size larger than the dot size indicated by the pixel is formed.

  The printer driver may correct the dot data while creating the print data according to the ink temperature Ti, or print data (dot data) that has not been subjected to the correction process according to the ink temperature Ti from the printer driver. 1 may be received, and the controller 10 of the printer 1 may correct the dot data according to the ink temperature Ti. In FIG. 7C, the dot size of the pigment black ink Kp is not corrected, but the correction is not limited to this. However, it is assumed that the dot enlargement ratio of the pigment black ink Kp is smaller than the dot enlargement ratio of the dye black ink Kd.

  According to the correction value table in FIG. 7C, when the ink temperature Ti is higher than 5 ° C. and lower than or equal to 10 ° C. (10 ° C. ≧ Ti> 5 ° C.), the dot size indicated by the dye black dot data of a certain pixel It correct | amends so that the dot of the dye black ink Kd of a size larger 1 level may be formed. On the other hand, when the ink temperature Ti is 5 ° C. or less (5 ° C. ≧ Ti), the dots of the dye black ink Kd having a size two steps larger than the dot size indicated by the dye black dot data of a certain pixel are formed. Correct as follows.

  For example, it is assumed that the dot data of the dye black ink Kd indicates “small dot formation” in a certain pixel. In this case, if the ink temperature Ti is 8 ° C., the dye black dot data is corrected to “medium dot formation”, and if the ink temperature Ti is 5 ° C., the dye black dot data is changed to “large dot formation”. It is corrected. If the data before correction indicates, for example, “large dot formation” and correction cannot be performed so that the dot size becomes large, it is preferable to newly generate a small dot in the neighboring pixel.

=== Dot Forming Position of Dye Ink and Pigment Ink ===
FIG. 8 is a diagram in which the dot formation position of the pigment black ink Kp and the dot formation position of the dye black ink Kd are shifted in the movement direction. In order to improve the poor filling of the medium due to the decrease in the ink temperature Ti, the print data is set so that the dot size (large dot) of the dye black ink Kd is larger than the dot size (medium dot) of the pigment black ink Kp. Is corrected. In the head 41 (FIG. 2A) of this embodiment, the dye black nozzle row Kd and the pigment black nozzle row Kp are shifted by a half nozzle pitch (0.5) in the transport direction. According to such a head 41, for example, as shown in FIG. 4A, a raster line in which dots of pigment black ink Kp are arranged in the moving direction and a raster line in which dots of dye black ink Kd are arranged in the moving direction (Alternately) can be printed side by side. However, in FIG. 4A, the dot formation position in the movement direction of the pigment black ink Kp and the dot formation position in the movement direction of the dye black ink Kd are made equal.

  On the other hand, in FIG. 8, in the image in which the raster line of the pigment black ink Kp and the raster line of the dye black ink Kd are alternately arranged in the transport direction, the dot formation position of the pigment black ink Kp and the dye black ink Kd Printing is performed by shifting the dot formation position (center position of the dot) in the movement direction. In other words, the pixel in which the dye black nozzle row Kd forms a dot and the pixel in which the pigment black nozzle row Kp forms a dot are shifted in the movement direction. As a result, it is possible to improve the filling of the medium, and it is possible to suppress image quality deterioration (bad medium filling) due to a decrease in the ink temperature Ti. In order to perform printing in this way, it is preferable to adjust the timing of ink ejection from the pigment black nozzle row Kp and the timing of ink ejection from the dye black nozzle row Kd. Therefore, for example, in the drive signal COM (FIG. 3B), the generation timing of the drive waveform W for ejecting ink droplets from each nozzle may be shifted.

  9A and 9B are diagrams showing dots printed by the head 41 in which the dye black nozzle row Kd and the pigment black nozzle row Kp are not shifted in the transport direction. In the head 41 shown in FIG. 2A, the printing speed is increased by shifting the dye black nozzle row Kd and the pigment black nozzle row Kp in the transport direction and simultaneously using the two types of inks Kd and Kp.

  For example, when text printing is performed, two types of inks Kd and Kp may be used at the same time in order to print the outline of a character with pigment ink that does not easily spread and to print the inside of the character with dye ink that easily spreads. is there. In this case, the dye black nozzle row Kd and the pigment black nozzle row Kp do not have to be shifted in the transport direction as in the head 41 in FIG. 2A, and the dye black nozzle row in the head 41 shown in FIG. The positions of Kd and the pigment black nozzle row Kp in the transport direction may be aligned. Further, in the head 41 in which the positions in the transport direction of the dye black nozzle row Kd and the pigment black nozzle row Kp are aligned, as shown in FIG. 9A, a dot row (raster line) along the moving direction is formed with two types of dots. Printing speed can be increased during overlap printing. In the case where dots are formed at half nozzle pitches (0.5D) in the transport direction as shown in FIG. 8 by the head 41 in which the positions in the transport direction of the dye black nozzle row Kd and the pigment black nozzle row Kp are equal. In this case, after an image is formed in a certain pass, the medium is finely fed by a half nozzle pitch (0.5D) to print the image.

  In FIG. 9A, a dot of pigment black ink Kp is formed in a pixel at a certain position in the movement direction (example: left end), and the dye black ink Kd is formed in the adjacent pixel (example: second pixel from the left). The dot formation timing is aligned for each nozzle row KpKd, such as forming dots. As a result, a dot row in which the dots of the dye black ink Kd are arranged in the carrying direction and a dot row in which the dots of the pigment black ink Kp are arranged in the carrying direction are printed side by side in the moving direction (alternately).

  On the other hand, in FIG. 9B, even when the nozzles belong to the same nozzle row KpKd, the timing for forming dots is shifted. Specifically, the nozzle (# 2) belonging to a certain position in the transport direction forms a dot, and the nozzle (# 1, # 3) arranged in the downstream and upstream in the transport direction forms a dot. The timing to do is shifted. As a result, the dots of the dye black nozzle row Kd and the dots of the pigment black nozzle row Kp are alternately formed in both the transport direction and the movement direction. Therefore, the dots of the dye black ink Kd are formed around the dots of the pigment black ink Kp having a small dot size, so that the filling of the medium can be improved, and the image quality deteriorates due to the drop of the ink temperature Ti (the poor filling of the medium). ) Can be suppressed. Actually, as shown in FIG. 9B, since the dots are not necessarily formed in all the pixels, in other words, the pixels assigned to the dye black nozzle row Kd and the pixels assigned to the pigment black nozzle row Kp are: Alternately set in the transport direction and move direction.

=== Other Embodiments ===
Each of the above embodiments has been described mainly with respect to a printing system having an ink jet printer, but includes disclosure of a correction method for image quality degradation and the like. The above-described embodiments are for facilitating understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About black ink>
In the above-described embodiment, dye ink and pigment ink can be ejected only for black. Therefore, in order to correct the black ink discharge amount that cannot be corrected by adjusting the drive waveform W when the ink temperature Ti is equal to or lower than the threshold value, the discharge amount of the dye black ink is increased with respect to the discharge amount of the pigment black ink. Amendments have been made. However, the present invention is not limited to this, and other colors (for example, three-color color YMC) may be corrected when the dye ink and the pigment ink are included.

<About correction of drive waveform W>
In the above-described embodiment, the maximum potential Vh (FIG. 3B) of the drive waveform W is corrected according to the ink temperature Ti, the ink temperature Ti becomes equal to or less than a threshold (eg, 10 ° C. or less), and ink ejection is performed by adjusting the drive waveform W. When the amount cannot be corrected, the discharge amount of the dye ink is increased with respect to the discharge amount of the pigment ink, but the present invention is not limited to this. For example, when the ink temperature Ti falls below normal temperature (25 ° C.), the correction of increasing the discharge amount of the dye ink relative to the discharge amount of the pigment ink is performed without correcting the maximum potential Vh of the drive waveform W. May be.

<About the printer>
In the above-described embodiment, a printer (so-called serial printer) that repeats an image forming operation for forming an image while moving the head 41 in the moving direction and an operation for conveying the medium in the conveying direction is exemplified. Not limited to. For example, a printer (so-called line head printer) that forms an image by arranging a plurality of heads over the paper width and conveying the paper under a fixed head may be used. In addition, the continuous paper is conveyed to the printing area, and the head moves in the nozzle array direction while moving the head in the moving direction intersecting the nozzle array direction with respect to the paper portion located in the printing area. A printer that prints a two-dimensional image by repeating the operation and then transports a new paper portion to the printing area (moving direction) after printing on the paper in the printing area may be used.

<About printing devices>
The ink ejection method may be a piezo method in which a fluid is ejected by applying a voltage to the drive element (piezo element) to expand and contract the ink chamber, or by generating bubbles in the nozzle using a heating element, A thermal method in which liquid is ejected by the bubbles may be used.

1 Printer, 10 Controller, 11 Interface section,
12 CPU, 13 memory, 14 unit control circuit,
20 transport unit, 21 transport belt, 22A, 22B transport roller,
30 head units, 31 heads,
40 detector groups, 50 computers

Claims (6)

(A) a nozzle from which a dye ink of a certain color is discharged;
(B) a nozzle from which the pigment ink of a certain color is discharged;
(C) a sensor that outputs a signal corresponding to the temperature change of the ink;
(D) a controller that prints the image using both the dye ink and the pigment ink when printing an image including a certain color;
Compared with the case where the temperature of the ink based on the output result of the sensor is higher than the threshold value, the unit area with respect to the discharge amount of the pigment ink per unit area is more when the temperature of the ink is lower than the threshold value. A control unit that increases the ratio of the discharge amount of the dye ink and prints the image;
A printing apparatus comprising (E). The printing apparatus according to claim 1,
When the temperature of the ink is not more than the threshold value,
The correction value for correcting the amount of the dye ink ejected per unit area is larger than the correction value for correcting the amount of the pigment ink ejected per unit area.
Printing device. The printing apparatus according to claim 2,
When the temperature of the ink is not more than the threshold value,
The amount of the dye ink ejected per unit area is corrected, but the amount of the pigment ink ejected per unit area is not corrected.
Printing device. The printing apparatus according to any one of claims 1 to 3,
The nozzle row in which the plurality of nozzles ejecting the dye ink are arranged in a predetermined direction and the nozzle row in which the plurality of nozzles from which the pigment ink is ejected are arranged in the predetermined direction intersect the predetermined direction. By ejecting ink from the nozzle row while relatively moving in the direction, a dot row in which the dots of the dye ink are arranged in the intersecting direction, and a dot row in which the dots of the pigment ink are arranged in the intersecting direction, Prints the images arranged in the predetermined direction,
Shifting the dot formation position of the dye ink and the dot formation position of the pigment ink in the intersecting direction;
Printing device. The printing apparatus according to any one of claims 1 to 4, wherein:
The nozzle row in which the plurality of nozzles ejecting the dye ink are arranged in a predetermined direction and the nozzle row in which the plurality of nozzles from which the pigment ink is ejected are arranged in the predetermined direction intersect the predetermined direction. By ejecting ink from the nozzle row while relatively moving in the direction,
Printing the image in which the dots of the dye ink and the dots of the pigment ink are alternately arranged in the predetermined direction and the intersecting direction;
Printing device. A printing method for a printing apparatus comprising: a nozzle from which a dye ink of a certain color is ejected; a nozzle from which the pigment ink of a certain color is ejected; and a sensor that outputs a signal corresponding to a temperature change of the ink,
When printing an image containing the certain color, the image is printed using both the dye ink and the pigment ink,
Compared with the case where the temperature of the ink based on the output result of the sensor is higher than the threshold value, the unit area with respect to the discharge amount of the pigment ink per unit area is more when the temperature of the ink is lower than the threshold value. Increasing the ratio of the discharge amount of the dye ink, and printing the image,
A printing method characterized by the above.

Images