JP2005319636A - Print method, print method of print pattern, reading method, printer, reader, and print system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a print method capable of conditioning the density more appropriately. <P>SOLUTION: The print method comprises a first print step for printing a first print pattern, a second print step for printing a second print pattern requiring a shorter time for settling the density as compared with the first print pattern following to the first print pattern, and a third print step for printing an image with a density conditioned based on the densities of the first and second print patterns out of a plurality of printed print patterns. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing method, a reading method, a printing apparatus, a reading apparatus, and a printing system for suppressing image density unevenness.

A color inkjet printer (hereinafter referred to as a printer) is known as a printing apparatus that forms an image by ejecting a plurality of colors of ink onto a sheet of paper. Since such a printer prints an image by ejecting ink from a plurality of nozzles, it is necessary to adjust the image printed on the ink ejected from each nozzle to have an appropriate density. As this adjustment method, for example, a method is known in which a predetermined print pattern is printed for each nozzle, the printed print pattern is read by a predetermined reader, and the density is adjusted based on the read result (for example, (See Patent Document 1).
Japanese Patent Laid-Open No. 3-199052

  By the way, the density of the printed image may be different immediately after printing and after a while after printing. In particular, since the ink has different characteristics for each color, the time until the density is stabilized after printing may be different for each ink color. For this reason, if the time until reading after printing the print pattern for acquiring the information for adjusting the density is not appropriate, the density can be adjusted based on the information acquired from the print pattern. There is a problem that there is a fear that the image cannot be printed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a printing method, a printing pattern printing method, a reading method, a printing apparatus, and a reading apparatus capable of adjusting the density more appropriately. And to realize a printing system.

  The main invention is a printing method for printing an image by adjusting the density based on the density of a print pattern printed with a plurality of different colors of ink, and printing a first print pattern among the print patterns. A first printing step; a second printing step for printing a second printing pattern having a time shorter than the first printing pattern after the first printing step until the density is stabilized; and a density of the first printing pattern. And a third printing step for printing an image having a density adjusted on the basis of the density of the second print pattern.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  At least the following will be made clear by the description of the present specification and the accompanying drawings.

  In a printing method for printing an image by adjusting the density based on the density of a printing pattern printed with different colors of ink, a first printing step for printing a first printing pattern among the printing patterns And after the first printing step, a second printing step for printing a second printing pattern in which the time taken for the density to stabilize is shorter than the first printing pattern, the density of the first printing pattern, and the second And a third printing step of printing an image having a density adjusted based on the density of the print pattern.

  According to such a printing method, it is possible to reduce the time taken from the start of printing the first print pattern until the density of the first print pattern and the second print pattern is stabilized. In addition, since the density is adjusted based on a print pattern with a stable density, there is no variation in the adjusted density, and an image with an appropriate density can be stably obtained. That is, it is possible to obtain a print pattern having a stable density in a short time. Here, “stable density” means, for example, that a measured value converges to a predetermined value when a printed pattern is measured with a predetermined density measuring device.

In such a printing method, in a printing apparatus having a plurality of ink discharge portions arranged along a predetermined direction for each color of the ink, the ink is moved while moving the plurality of discharge portions in a moving direction intersecting the predetermined direction. When printing an image by discharging the ink, it is based on the density of the print pattern so as to suppress the density unevenness between the dot row regions in the medium on which the dot row along the moving direction is formed in each of the discharge portions. Thus, it is desirable to adjust the density for each dot row region.
According to such a printing method, since a stable print pattern can be obtained in a short time, the density of the print pattern is stabilized even after a short time after printing. Even in a short time after printing, it is possible to more appropriately suppress density unevenness between dot row regions based on a print pattern having a stable density.

In such a printing method, it is preferable that each of the printing patterns has a sub-pattern printed with a plurality of gradations.
An image to be printed may have a different gradation in each part, and a part having a different gradation has a different nozzle, a size of a dot to be formed, and the like. For this reason, it is possible to adjust the density according to a plurality of gradations by having a sub-pattern printed with a plurality of gradations. Therefore, it is possible to suppress density unevenness between the dot row regions more appropriately.

In this printing method, it is preferable that the sub-pattern is printed along the predetermined direction of the medium.
Density unevenness between the dot row regions occurs due to the printed dot row, and the situation of occurrence varies depending on the printing method, the ejection unit used, the relative position of the dot row to be formed with respect to the medium, and the like. For this reason, as in the printing method described above, the sub-pattern is printed along the predetermined direction of the medium, so that the printing method that actually prints, the discharge part that actually forms the dots, the relative position with respect to the medium, and the like. Appropriate correction can be executed in correspondence.

In the printing apparatus, it is preferable that the sub patterns are printed side by side along the moving direction.
According to such a printing method, since a plurality of print patterns are printed side by side along the movement direction, it is possible to print many print patterns when the ejection unit moves once in the movement direction. . Also, it is possible to print more sub-patterns with different gradations on one medium, printed along the transport direction and capable of effectively adjusting the density corresponding to the relative position with the medium. Is possible.

In such a printing method, the plurality of print patterns have a stable density from the print pattern that takes the longest time to stabilize the density after printing to the print pattern that takes the shortest time to stabilize the density. It is desirable to print in an order that shortens the time taken to do in order.
According to such a printing method, the printing pattern that takes the longest time for the density to stabilize after printing is printed first, and then the printing is performed in such an order that the time it takes for the density to stabilize gradually decreases. The pattern is printed. For this reason, a print pattern that takes a relatively long time to stabilize the density stabilizes while the other print pattern is being printed. It is possible to stabilize the concentration. In particular, the print pattern that takes the longest time to stabilize the density has the longest time from the end of printing to the end of printing the last print pattern, and the shortest time it takes for the density to stabilize Is set so that the time from the end of printing to the end of printing of the last print pattern is set so that the time from the end of printing to the end of printing of the last print pattern is the shortest. It is possible to print each print pattern efficiently.

In this printing method, it is preferable that the print pattern is printed on a different medium for each color of the ink.
According to such a printing method, since one print pattern is printed on one medium, the sub-pattern for each gradation printed along a predetermined direction is printed on the entire area in the predetermined direction of the medium. Is possible. For this reason, it is possible to print a print pattern capable of adjusting the density more effectively by making the dot row region and the medium correspond to their relative positions over the entire region in the predetermined direction. Also, for example, for each print pattern, the medium is moved to a predetermined print position, or the medium after printing is output, so the time spent for one print pattern increases, and all print patterns are printed. Later, it becomes possible to obtain a printed pattern having a more stable density.

In such a printing method, it is preferable that the print pattern is printed on one medium so that the length of time required for the density to stabilize is sequentially changed along the predetermined direction.
According to such a printing method, since one medium is used for printing all the print patterns, it is possible to reduce not only the medium but also the amount of ink used, and the cost can be reduced. Moreover, since printing is performed only on one medium, it is possible to reduce the time required for printing the print pattern. Also, since printing is performed on one medium so that the length of time required for the density to stabilize sequentially changes, the order of the length of time required for the density to stabilize and the correspondence between the print pattern and It is clear.

Further, in a printing pattern printing method for printing a printing pattern for each ink color using a plurality of different colors of ink, a first printing step for printing a first printing pattern among the printing patterns; And a second printing step for printing a second printing pattern that takes less time for the density to stabilize after the printing step than the first printing pattern.
According to such a printing method, it is possible to reduce at least the time taken from the start of printing the first print pattern until the density of the first print pattern and the second print pattern is stabilized. Further, the density of the first print pattern that takes a long time to stabilize the density can be set to a more appropriate density before all the print patterns are printed.

Further, in the reading method of reading the print patterns each printed with a plurality of different colors of ink, the first reading step of reading the first print pattern out of the print patterns and the density after the first reading step. And a second reading step of reading a second print pattern that takes a longer time to stabilize than the first print pattern.
According to such a reading method, since the first print pattern takes less time to stabilize the density than the second print pattern, even if the first print pattern is read first, the density of the first print pattern Is likely to be stable or is approaching a concentration to be stabilized. The second print pattern takes a longer time to stabilize the density than the first print pattern, but it is highly possible that the density of the second print pattern is stable by reading after the first print pattern. Or approaching a stable concentration. For this reason, it is possible to read the first printing pattern and the second printing pattern in a state where the density is more appropriate.

In such a reading method, the plurality of print patterns are stable in density from the print pattern that takes the shortest time for the density to stabilize after printing to the print pattern that takes the longest time for the density to stabilize. It is desirable to read in such an order that the time taken to do so becomes longer.
According to such a reading method, the print pattern that takes the shortest time to stabilize the density after printing is read first, and then the prints are sequentially performed in such a manner that the time required to stabilize the density becomes longer. The pattern is read. For this reason, a print pattern that takes a relatively long time to stabilize the density stabilizes while the other print pattern is being read. It is possible to read at close density. In particular, the print pattern that takes the shortest time to stabilize the density is read first, the time from the end of printing to the end of reading is the shortest, and the print pattern that takes the longest time to stabilize the density is Since the time is set so that the time from the end of printing to the end of reading becomes the longest, the print pattern can be read with a more accurate density.

In addition, the image forming apparatus includes a plurality of ejection units that eject different types of inks, and prints an image by adjusting the density based on the density of a print pattern that is printed with each of the ink ejected from the plurality of ejection units. In the printing apparatus, after the first print pattern is printed out of the print patterns, the second print pattern is printed with a time shorter than the first print pattern before the density is stabilized, and the density of the first print pattern And an image having a density adjusted based on the density of the second print pattern.
According to such a printing apparatus, it is possible to reduce the time required from the start of printing the first print pattern until the density of the first print pattern and the second print pattern is stabilized. In addition, since the density is adjusted based on a print pattern with a stable density, there is no variation in the adjusted density, and an image with an appropriate density can be stably obtained. In other words, it is possible to obtain a printing pattern with a stable density in a short time. Further, the ink has a plurality of ejection portions that eject a plurality of different types of ink, and the ink ejected from the plurality of ejection portions In the printing apparatus that prints the print pattern for each ink, after the first print pattern is printed out of the print patterns, the second print pattern that takes less time to stabilize the density than the first print pattern is printed. The printing apparatus is characterized by the above.
According to such a printing apparatus, it is possible to shorten at least the time taken from the start of printing the first print pattern until the density of the first print pattern and the second print pattern is stabilized.

In addition, a reading device that has a display unit for displaying information to be transmitted to the operator and that is printed with a plurality of different types of inks, reads the first print pattern out of the print patterns. In the reading apparatus, the display unit displays information for prompting an operation for reading the second print pattern, which takes a longer time for the density to stabilize after the first print pattern.
According to such a reading apparatus, the time required for the density to stabilize after reading the first print pattern by the operator's operation based on the information displayed on the display unit is longer than that of the first print pattern. It is possible to read a long second print pattern. For this reason, the operator can cause the reading device to read a print pattern having a density close to the original density simply by following the displayed information.

  In addition, (a) a computer main body, and (b) a plurality of ejection units that are connected to the computer main body and eject a plurality of different types of ink, and each printed with ink ejected from the plurality of ejection units Among the patterns, after printing the first print pattern, a printing apparatus that prints a second print pattern that takes less time than the first print pattern in the previous period to stabilize the density; and (c) connected to the computer main body, A display unit for displaying information to be transmitted to the operator, and after reading the second print pattern among the print patterns respectively printed with different types of ink, the first print pattern is displayed. A reading device that displays information prompting an operation for reading on the display unit, and (d) the first print pattern printed by the printing device Fine the second printing pattern, a printing system, characterized in that to print an image of the adjusted concentration based on the results read by the reading device.

  According to such a printing system, after printing the first print pattern, which takes a longer time than the second print pattern after the printing until the density is stabilized, after the first print pattern is printed by the printing apparatus, after the second print pattern, Reading is performed by a reading device. That is, it takes a long time for the density to stabilize after printing, and the time from the end of printing the first print pattern to the start of reading is set long, and the time it takes for the density to stabilize after printing is short. It is possible to set a short time from the end of printing of the two print patterns to the start of reading. For this reason, it is possible to read both the first print pattern and the second print pattern in a density state close to the original density. Further, since density unevenness between the dot row regions is suppressed by adjusting the density based on the density of the print pattern read in this way, it is possible to print a better image.

In addition, a plurality of ink ejection portions arranged along a predetermined direction for each of a plurality of different colors of ink, and ejecting ink while moving the plurality of ejection portions in a moving direction intersecting the predetermined direction In the printing method for printing an image, in the printing method in which the image is printed by adjusting the density based on the density of the printed pattern printed with each of the plurality of colors of ink, each of the printed patterns includes: It has a sub-pattern printed with a plurality of gradations, and is printed on a different medium for each color of the ink, and the sub-pattern is printed along the predetermined direction of the medium and the moving direction The first printing step of printing the first printing pattern among the printing patterns, and the time taken for the density to stabilize after the first printing step A second printing step for printing in order such that the time required for the density to stabilize is sequentially shortened to the shortest printing pattern, and a dot row along the moving direction is formed in each of the ejection portions. A third printing step of adjusting the density for each dot row region based on the density of the print pattern and printing an image having the adjusted density in order to suppress density unevenness between the dot row regions on the medium; It is a printing method characterized by having.
According to such a printing method, the effects of the present invention can be most effectively achieved because almost all the effects described above can be achieved.

=== Configuration of Printing System ===
Next, an embodiment of a printing system will be described with reference to the drawings.

FIG. 1 is an explanatory diagram showing the external configuration of the printing system, and FIG. 2 is a block diagram showing the configuration of the printing system shown in FIG.
The printing system 700 includes an inkjet printer (hereinafter referred to as a printer) 1 as a printing device, a computer 702, a display device 704, an input device 708, a recording / reproducing device 710, and a color scanner (hereinafter referred to as a reading device). 1). The printer 1 is a printing apparatus that prints an image on a medium such as paper, cloth, or film. In the following description, a sheet that is a typical medium will be described as an example.

  The computer 702 includes an internal memory 802 such as a RAM and an external memory such as a hard disk drive unit 804. Various application programs 714, a printer driver 711 (see FIG. 8), and the like are installed in these memories. The computer 702 is communicably connected to the printer 1 and the scanner 10 and outputs print data corresponding to the image to the printer 1 or reads image data from the scanner 10 in order to cause the printer 1 to print an image. Execute the process. The input device 708 is, for example, a keyboard 708A or a mouse 708B, and is used for input of operation of an application program, setting of a printer driver 711, and the like. As the recording / reproducing device 710, for example, a flexible disk drive device 710A or a CD-ROM drive device 710B is used.

  The printer driver 711 is a program for realizing a function of displaying a screen for setting printing conditions and the like on the display device 704 and a function of converting image data output from the application program into print data. is there. The printer driver 711 is recorded on a recording medium (computer-readable recording medium) such as a flexible disk or a CD-ROM. The printer driver 711 can also be downloaded to the computer 702 via the Internet. And this program is comprised from the code | cord | chord for implement | achieving various functions.

  The “printing apparatus” means the printer 1 in a narrow sense, but means a system of the printer 1 and the computer 702 in a broad sense.

=== Configuration of Scanner ===
FIG. 3 is an explanatory diagram showing a schematic configuration of a scanner as an example of a reading apparatus according to the present invention.
The scanner 10 presses the original table glass 7 on which the original document 5 to be read including the print pattern for adjustment and the like and the reading surface of the original document 5 placed on the original table glass 7 to the original table glass 7 side. A document table cover 6 for reading, a reading carriage 16 that faces the document table glass 7 and moves along the document 5 while maintaining a certain distance from the document 5, and a driving means 18 for moving the reading carriage 16. The regulation guide 12 for moving the reading carriage 16 in a stable state, the display unit 36 for displaying information to be transmitted to the operator, the operation unit 34 for operating the scanner 10, and the scanner 10 And a control unit 38 for controlling the driving of each element.

  The reading carriage 16 passes through the lens through a light source unit 8 as a light source for irradiating the original 5 with light of three colors through the original table glass 7, a rod lens array 14 for condensing the reflected light from the original 5 A contact image sensor unit that is integrated with a linear CCD sensor 15 as an image sensor that receives reflected light as light amount information and outputs the light amount information as a signal, and a guide that engages with the regulation guide 12 A receiving portion 29 is provided. In this embodiment, a CIS (Contact Image Sensor) unit 11 is used as the contact image sensor unit.

  The restriction guide 12 is provided along a direction in which the reading carriage 16 moves (hereinafter referred to as a moving direction) and is formed of a stainless steel cylindrical material. The restriction guide 12 is provided on the reading carriage 16 and passes through two guide receiving portions 29 made of thrust bearings. By widening the distance between the two guide receiving portions 29 provided in the reading carriage 16 in the moving direction, the reading carriage 16 can be moved more stably.

  The driving unit 18 includes an annular timing belt 181 fixed to the reading carriage 16, two pulleys 182 and 184 around which the timing belt 181 is bridged, and a pulse motor 183 to which one pulley 182 is attached. ing. The two pulleys 182 and 184 are arranged in the moving direction of the reading carriage 16 at a distance wider than the moving distance, one pulley 182 is fixed to the shaft of the pulse motor 183, and the other pulley 184 is attached to the timing belt 181. Tension is applied. The pulse motor 183 is driven by the motor driver of the control unit 38, and the read image can be enlarged and reduced in the moving direction by the moving speed of the reading carriage 16 changed according to the rotation speed of the pulse motor 183. Become.

  When the scanner 10 reads the document, the light source unit 8 emits light to irradiate the document 5, and the reflected light is condensed on the linear CCD sensor 15 by the rod lens array 14 while reading the carriage 16. Is moved along the document 5. At this time, the scanner 10 takes in a voltage value as light quantity information indicating the amount of light received by the linear CCD sensor 15 at a predetermined period, thereby obtaining an image corresponding to the distance the reading carriage 16 has moved during one period. Read as data corresponding to the line. At this time, since the amount of light received by the linear CCD sensor 15 differs depending on the density of the original, it is possible to detect the density of the original from the light quantity information.

=== Configuration of Printer ===
4 is a block diagram of the overall configuration of the printer 1 of the present embodiment, FIG. 5 is a schematic diagram of the overall configuration of the printer 1 of the present embodiment, and FIG. 6 is a side sectional view of the overall configuration of the printer 1 of the present embodiment. FIGS. 7A and 7B are explanatory diagrams showing the arrangement of nozzles on the lower surface of the head 41. Hereinafter, the basic configuration of the printer 1 of the present embodiment will be described with reference to these drawings.

  The printer 1 of this embodiment includes a transport unit 20, a print carriage unit 30, a head unit 40, a sensor 50, and a controller 60. The printer 1 that has received the print data from the computer 702 as an external device controls each unit (conveyance unit 20, print carriage unit 30, head unit 40) by the controller 60. The controller 60 controls each unit based on the print data received from the computer 702 and prints an image on the paper P. The situation in the printer 1 is monitored by a sensor 50, and the sensor 50 outputs a detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the sensor 50.

  The transport unit 20 functions as a transport mechanism that transports the paper P, transports the paper P to a printable position, and transports the paper P by a predetermined transport amount in a predetermined direction (hereinafter referred to as a transport direction) during printing. It is for making it happen.

  The transport unit 20 includes a paper feed roller 21, a transport motor 22 (also referred to as a PF motor), a transport roller 23, a platen 24, and a paper discharge roller 25. The paper feed roller 21 is a roller for feeding the paper P inserted into the paper insertion slot into the printer 1. The paper feed roller 21 has a D-shaped cross-sectional shape, and the length of the circumferential portion is set longer than the transport distance to the transport roller 23. For this reason, by rotating the paper feed roller once from a state in which the circumferential portion is separated from the surface of the paper, the paper P can be transported by the length of the circumferential portion and the leading end of the paper P can reach the transporting roller 23. Is possible. The transport motor 22 is a motor for transporting paper in the transport direction, and is constituted by, for example, a DC motor. The transport roller 23 is a roller that transports the paper P fed by the paper feed roller 21 to a printable area, and is driven by the transport motor 22. The platen 24 supports the paper P being printed from the back side of the paper P. The paper discharge roller 25 is a roller for transporting the paper P in the transport direction on the downstream side of the platen 24 in the transport direction. The paper discharge roller 25 rotates in synchronization with the transport roller 23.

  The print carriage unit 30 includes a print carriage 31 and a print carriage motor 32 (hereinafter also referred to as a CR motor). The print carriage motor 32 is a motor for reciprocating the print carriage 31 in a predetermined direction (hereinafter referred to as a print carriage movement direction), and is constituted by a DC motor, for example. The print carriage 31 detachably holds an ink cartridge 90 that stores ink. The print carriage 31 is attached with a head 41 that ejects ink from nozzles serving as ejection units. For this reason, as the print carriage 31 reciprocates, the head 41 and the nozzles also reciprocate in the print carriage movement direction. Therefore, this print carriage movement direction corresponds to the “movement direction” according to the claims.

  The head unit 40 is for ejecting ink onto the paper P. The head unit 40 has a head 41. The head 41 has a plurality of nozzles, and ejects ink intermittently from each nozzle. Then, the ink is intermittently ejected from the nozzles while the head 41 moves in the print carriage movement direction, so that a dot row along the print carriage movement direction is formed on the paper P. Further, an area for forming a dot row along the print carriage movement direction can be virtually determined on a sheet as a pixel row along the print carriage movement direction. It is expressed as “dot line area”. Here, the pixel is a square grid that is virtually defined on the paper in order to define the position at which dots are formed on the paper by ejecting ink from the nozzles serving as ejection portions. In other words, a pixel is an area on a medium where dots can be formed, and can also be expressed as a “dot formation unit”. The arrangement of the nozzles, the configuration of the head 41, the driving circuit for driving the head 41, and the driving method of the head 41 will be described later.

  The sensor 50 includes a linear encoder 51, a rotary encoder 52, a paper detection sensor 53, a paper width sensor 54, and the like. The linear encoder 51 is for detecting the position in the print carriage movement direction, and is attached to the print carriage 31 and formed in the slit plate. A photo interrupter for detecting the slit is provided. The rotary encoder 52 is for detecting the amount of rotation of the transport roller 23, and is a disc-shaped slit plate that rotates as the transport roller 23 rotates, and a photo interrupter that detects a slit formed in the slit plate. Have

  The paper detection sensor 53 is for detecting the leading end position of the paper P to be printed. The paper detection sensor 53 is provided at a position where the front end position of the paper P can be detected while the paper feed roller 21 is transporting the paper P toward the transport roller 23. The paper detection sensor 53 is a mechanical sensor that detects the leading edge of the paper P by a mechanical mechanism. More specifically, the paper detection sensor 53 has a lever that can rotate in the paper transport direction, and this lever is disposed so as to protrude into the transport path of the paper P. Then, as the paper P is transported, the leading edge of the paper comes into contact with the lever, and the lever is rotated. Therefore, the paper detection sensor 53 detects the position of the leading edge of the paper P and the presence or absence of the paper P by detecting the movement of the lever by a photo interrupter or the like.

  The paper width sensor 54 is attached to the print carriage 31. In the present embodiment, as shown in FIG. 7, the position in the transport direction is attached at substantially the same position as the nozzle on the most upstream side. The paper width sensor 54 is a reflection type optical sensor that receives the reflected light of the light irradiated on the paper P from the light emitting unit at the light receiving unit, and detects the presence or absence of the paper P based on the received light intensity at the light receiving unit. To do. The paper width sensor 54 detects the position of the edge of the paper P while being moved by the print carriage 31 and detects the width of the paper P. The paper width sensor 54 can also detect the leading edge of the paper P depending on the situation.

  The controller 60 is a control unit for controlling the printer 1. The controller 60 includes an interface unit (I / F) 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 is for transmitting and receiving data between the computer 702 which is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and has storage means such as a RAM, an EEPROM, and a ROM. The CPU 62 controls each unit 20, 30, 40 via the unit control circuit 64 in accordance with a program stored in the memory 63. In the present embodiment, a partial area of the memory 63 is used as a correction table storage unit 63a for storing a correction table described later.

<Regarding nozzle arrangement and head configuration>
As shown in FIG. 7, on the lower surface of the head 41. A black ink nozzle row N _K, a cyan ink nozzle row N _C, a magenta ink nozzle row N _M, yellow ink nozzle row N _Y is formed. That is, the printer 1 has four colors: black (K) ink, cyan (C) ink, and magenta (M) ink as dark-colored ink with high density, and yellow (Y) ink as light-colored ink with low density. Can be ejected. Each nozzle row includes n nozzles (for example, n = 180) that are ejection ports for ejecting ink of each color. The plurality of nozzles in each nozzle row are aligned at a constant interval (nozzle pitch: k · D) along the direction intersecting the moving direction of the print carriage 31, that is, the transport direction of the paper P. Here, D is the minimum dot pitch in the transport direction, that is, the interval at the highest resolution of dots formed on the paper P. K is an integer of 1 or more. For example, when the nozzle pitch is 180 dpi (1/180 inch) and the dot pitch in the transport direction is 720 dpi (1/720 inch), k = 4. In the illustrated example, the nozzles in each nozzle row are assigned a smaller number (# 1 to #n) toward the downstream nozzle. That is, the nozzle # 1 is located downstream of the nozzle #n in the transport direction. If such a nozzle array is provided in the head 41, the range in which dots are formed by a single dot forming operation is widened, and the printing time can be shortened. Further, since these nozzle rows are provided for each color of ink, multi-color printing can be performed by appropriately discharging ink from these nozzle rows.

  Each nozzle has an ink flow path communicating with an ink cartridge 90 containing ink, and a pressure chamber (not shown) is provided in the middle of the ink flow path. Each pressure chamber is configured such that its volume contracts and expands by, for example, a piezo element (not shown) as a drive element provided to eject ink droplets from each nozzle.

<About driving the head>
FIG. 8 is an explanatory diagram of a drive circuit for the head 41. This drive circuit is provided in the unit control circuit 64 described above. As illustrated, the drive circuit includes an original drive signal generation unit 644A and a drive signal shaping unit 644B. In the present embodiment, this drive circuit is provided for each nozzle row, that is, for each nozzle row of each color of black (K), cyan (C), magenta (M), and yellow (Y). The piezo elements are individually driven. In the figure, the numbers in parentheses at the end of each signal name indicate the number of the nozzle to which the signal is supplied.

  The above-described piezo element is deformed each time the driving pulses W1 and W2 (see FIG. 9) are supplied to cause pressure fluctuations in the ink in the pressure chamber. That is, when a voltage of a predetermined time width is applied between the electrodes provided at both ends of the piezoelectric element, the piezoelectric element is deformed according to the voltage application time, and an elastic film (side wall) that partitions a part of the pressure chamber is formed. Deform. The volume of the pressure chamber changes according to the deformation of the piezo element, and the pressure fluctuation occurs in the ink in the pressure chamber due to the volume change of the pressure chamber. Ink drops are ejected from the corresponding nozzles # 1 to #n due to pressure fluctuations generated in the ink.

The original drive signal generator 644A generates an original drive signal ODRV that is used in common by the nozzles # 1 to #n.
The drive signal shaping unit 644B receives the print signal PRT (i) together with the original drive signal ODRV from the original signal generation unit. The print signal PRT (i) is a signal whose level changes based on the above-described 2-bit print data. The drive signal shaping unit 644B shapes the original drive signal ODRV according to the level of the print signal PRT (i) and outputs it as the drive signal DRV (i) to the piezoelectric elements of the nozzles # 1 to #n. The piezo elements of the nozzles # 1 to #n are driven based on the drive signal DRV from the drive signal shaping unit 644B.

<About the head drive signal>
FIG. 9 is a timing chart illustrating each signal. That is, FIG. 3 shows a timing chart of each signal of the original drive signal ODRV, the print signal PRT (i), and the drive signal DRV (i).

  The original drive signal ODRV is a signal used in common for the nozzles # 1 to #n, and is output from the original drive signal generation unit 644A to the drive signal shaping unit 644B. The original drive signal ODRV of the present embodiment is a signal between the first pulse W1 and the second pulse W2 within a time during which the print carriage 31 moves a distance corresponding to one pixel corresponding to the print resolution (hereinafter referred to as one pixel section). It has two pulses. The first pulse W1 is a drive pulse for ejecting a small-sized ink droplet (hereinafter referred to as a small ink droplet) from the nozzle. The second pulse W2 is a drive pulse for discharging a medium size ink droplet (hereinafter referred to as a medium ink droplet) from the nozzle. That is, by supplying the first pulse W1 to the piezo element, a small ink droplet is ejected from the nozzle. When the small ink droplets land on the paper P, small sized dots (small dots) are formed. Similarly, by supplying the second pulse W2 to the piezo element, a medium ink droplet is ejected from the nozzle. When the medium ink droplets land on the paper P, medium-sized dots (medium dots) are formed.

  The print signal PRT (i) is a signal corresponding to each pixel data assigned to each pixel in the print data transferred from a computer or the like. That is, the print signal PRT (i) is a signal corresponding to the pixel data included in the print data. The print signal PRT (i) of this embodiment is a signal having 2-bit information for one pixel. Note that the drive signal shaping unit 644B shapes the original drive signal ODRV according to the signal level of the print signal PRT (i) and outputs the drive signal DRV (i).

  This drive signal DRV is a signal obtained by blocking the original drive signal ODRV in accordance with the level of the print signal PRT. That is, when the print data is “1”, the print signal PRT is at a high level, and the drive signal shaping unit 644B passes the drive pulse corresponding to the original drive signal ODRV as it is to obtain the drive signal DRV (i). On the other hand, when the print data is “0”, the print signal PRT becomes the low level, and the drive signal shaping unit 644B blocks the drive pulse corresponding to the original drive signal ODRV. Then, the drive signal DRV (i) from the drive signal shaping unit 644B is individually supplied to the corresponding piezoelectric element. Further, the piezo element is driven according to the supplied drive signal DRV (i).

  When the print signal PRT (i) corresponds to the 2-bit data “10”, only the first pulse W1 is output in the first half of one pixel section. As a result, medium ink droplets are ejected from the nozzles, and medium dots are formed on the paper P. When the print signal PRT (i) corresponds to the 2-bit data “01”, only the second pulse W2 is output in the second half of one pixel interval. Thereby, a small ink droplet is ejected from the nozzle, and a small dot is formed on the paper P. When the print signal PRT (i) corresponds to the 2-bit data “11”, the first pulse W1 and the second pulse W2 are output in one pixel section. As a result, medium ink droplets and small ink droplets are continuously ejected from the nozzles, and large-sized dots (large dots) are formed on the paper P. That is, the printer 1 can form dots of a plurality of types (here, three types). Further, when the print signal PRT (i) corresponds to the 2-bit data “00”, neither the first pulse W1 nor the second pulse W2 is output in one pixel section. As a result, no ink droplet of any size is ejected from the nozzle, and no dot is formed on the paper P.

  As described above, the drive signal DRV (i) in one pixel section is shaped to have four different waveforms according to four different values of the print signal PRT (i).

=== Printer driver ===
FIG. 10 is a schematic explanatory diagram of basic processing performed by the printer driver 711. In addition, about the component already demonstrated, the same code | symbol is attached | subjected and description is abbreviate | omitted.

In the computer 702, computer programs such as a video driver 712, an application program 714, and a printer driver 711 are operating under an operating system installed in the computer 702.
The video driver 712 has a function of displaying a predetermined screen on the display device 704 in accordance with a display command from the application program 714 or the printer driver 711.

  The application program 714 has a function of performing image editing, for example, and creates data (image data) related to an image. The user can give an instruction to print an image edited by the application program 714 via the user interface of the application program 714. When the application program 714 receives a print command, the application program 714 outputs image data to the printer driver 711.

  The printer driver 711 receives image data from the application program 714, converts the received image data into printable print data, and outputs the converted print data to the printer 1. The image data has pixel data as data corresponding to each pixel of the image to be printed. Each pixel data is expressed by a gradation value for each color such as RGB or CMYK, and the gradation value is converted according to each processing stage to be described later. In the stage, the print data (data such as dot color and size) corresponding to the dots formed on the paper is converted.

  The print data is data in a format that can be interpreted by the printer 1 and includes the pixel data and various command data. The command data is data for instructing the printer 1 to execute a specific operation, for example, data indicating the carry amount.

  The printer driver 711 performs resolution conversion processing, color conversion processing, halftone processing, rasterization processing, and the like in order to convert image data output from the application program 714 into print data. Hereinafter, various processes performed by the printer driver 711 will be described.

In the resolution conversion process, the resolution when printing the image data (text data, image data, etc.) output from the application program 714 on the paper P (the interval between dots when printing, also called the print resolution). It is processing to convert to. For example, when the print resolution is specified as 720 × 720 dpi, the image data received from the application program 714 is converted into image data having a resolution of 720 × 720 dpi.
In this resolution conversion process, image data is also adjusted in size so as to correspond to the size of a print area to be printed (referred to as an area where ink is actually ejected).

  Note that each pixel data in the image data output from the application program 714 is data indicating gradation values in multiple levels (for example, 256 levels) represented by the RGB color space. Hereinafter, pixel data indicating RGB gradation values is referred to as RGB pixel data, and image data composed of RGB pixel data is referred to as RGB image data.

  The color conversion process is a process of converting each RGB pixel data of the RGB image data into data indicating gradation values of multiple levels (for example, 256 levels) represented by a CMYK color space. Here, the notation CMYK means C is cyan, M is magenta, Y is yellow, and K is black. Hereinafter, pixel data indicating CMYK gradation values is referred to as CMYK pixel data, and image data composed of CMYK pixel data is referred to as CMYK image data. The color conversion processing is performed by the printer driver 711 referring to a table (color conversion lookup table LUT) in which RGB gradation values and CMYK gradation values are associated with each other.

  The halftone process is a process of converting CMYK pixel data having multi-stage gradation values into CMYK pixel data having small-stage gradation values that can be expressed by the printer 1. For example, CMYK pixel data indicating 256 gradation values is converted into 2-bit CMYK pixel data indicating 4 gradation values by halftone processing. The 2-bit CMYK pixel data includes, for example, “no dot formation” (binary value “00”), “small dot formation” (also “01”), and “medium dot formation” for each color. (Also “10”) and “large dot formation” (also “11”).

  In such a halftone process, for example, a so-called dither method, γ correction method, error diffusion method, or the like is used to create 2-bit (4-gradation) CMKY pixel data that can be formed by the printer 1 by dispersing dots. To do. In the present embodiment, in the halftone process, density correction described later, that is, correction performed for each dot row region to suppress density unevenness between the dot row regions is also executed.

  The rasterizing process is a process of changing the four-color four-tone CMYK image data subjected to the halftone process in the order of data to be transferred to the printer 1. The rasterized data is output to the printer 1 as the print data.

=== About printing operation ===
FIG. 11 is a flowchart of the operation during printing. Each operation described below is executed by the controller 60 controlling each unit according to a program stored in the memory. This program has code for executing each operation.

  Print command reception (S001): The controller 60 receives a print command from the computer 702 via the interface unit 61. This print command is included in the header of print data transmitted from the computer 702. Then, the controller 60 analyzes the contents of various commands included in the received print data, and performs the following paper feed operation, transport operation, dot formation operation, and the like using each unit.

  Paper feeding operation (S002): The controller 60 performs a paper feeding operation. The paper feeding operation is a process of moving the paper P to be printed and positioning it at a print start position (so-called cue position). That is, the controller 60 rotates the paper feed roller 21 to send the paper P to be printed to the transport roller 23. Subsequently, the controller 60 rotates the transport roller 23 to position the paper P sent from the paper feed roller 21 at the print start position. When the paper P is positioned at the printing start position, at least some of the nozzles of the head 41 are opposed to the paper P.

  Dot Formation Operation (S003): The controller 60 performs a dot formation operation. The dot forming operation is an operation of forming dots on the paper P by intermittently ejecting ink from the head 41 moving in the print carriage movement direction. At this time, the controller 60 drives the print carriage motor 32 to move the print carriage 31 in the print carriage movement direction. Further, the controller 60 ejects ink from the head 41 based on the print data while the print carriage 31 is moving. When the ink discharged from the head 41 lands on the paper P, dots are formed on the paper P as described above. At this time, when ink is ejected from the nozzles while moving the print carriage 31, dot rows (hereinafter also referred to as raster lines) along the moving direction are formed on the paper P.

  Transport Operation (S004): The controller 60 performs a transport operation. The transport operation is a process of moving the paper P relative to the head 41 along the transport direction. The controller 60 drives the transport motor 22 and rotates the transport roller 23 to transport the paper P in the transport direction. By this carrying operation, the head 41 can form dots at positions different from the positions of the dots formed by the dot forming operation described above.

  Paper discharge determination (S005): The controller 60 determines whether or not to discharge the paper P being printed. At this time, if data for printing on the paper P being printed remains, the paper is not discharged. Then, the controller 60 alternately repeats the dot formation operation and the transport operation until there is no more data to be printed, and gradually prints an image composed of dots on the paper P. If there is no more data to print on the paper P being printed, the controller 60 discharges the paper P. That is, the controller 60 rotates the paper discharge roller 25 to discharge the printed paper P to the outside. Note that whether or not to discharge paper may be determined based on a paper discharge command included in the print data.

  Print end determination (S006): The controller 60 determines whether or not to continue printing. When printing on the next sheet P, a new sheet is fed by the sheet feeding operation (S002), printing is continued, and printing is continued. If printing is not performed on the next paper P, the printing operation is terminated.

=== Regarding Cause of Density Unevenness in Image ===
Density unevenness that occurs in an image printed in multiple colors using CMYK inks is basically caused by density unevenness that occurs in each ink color. For this reason, usually, a method of suppressing density unevenness in an image printed in multiple colors by individually suppressing density unevenness of each ink color is employed. Therefore, in the following, the cause of density unevenness occurring in a monochrome printed image will be described.

  FIG. 12 is a diagram for explaining density unevenness that occurs in the transport direction of the paper P in a single-color printed image.

  The density unevenness in the conveyance direction illustrated in FIG. 12 appears as stripes parallel to the print carriage movement direction (also referred to as horizontal stripes for convenience). Such horizontal stripe-shaped density unevenness occurs due to, for example, variations in the ink discharge amount for each nozzle, but also due to variations in the processing accuracy of the nozzles. In other words, the flying direction of the ink ejected by the nozzles varies due to variations in nozzle processing accuracy. Due to the variation in the flight direction, the dot formation position by the ink that has landed on the paper P may be shifted from the target formation position in the transport direction. In this case, the formation position of the raster line r formed by these dots is inevitably shifted from the target formation position in the transport direction. For this reason, the interval between the raster lines r adjacent in the transport direction is periodically vacated or clogged. When viewed macroscopically, it appears as horizontal stripe-shaped density unevenness. That is, a dot row region in which more dots or a part of dots are formed in the dot row region than the dots originally formed by the interval between adjacent raster lines r being relatively widened or narrowed. When a dot or a part of a dot that should be originally formed in a dot row area is formed in an adjacent dot row area, the dot row area looks macroscopically thin. . Here, the raster line r indicates a dot row formed along the print carriage movement direction by intermittently ejecting ink while moving the print carriage 31.

  The cause of density unevenness is also applicable to other ink colors. If this tendency is observed even in one of cyan C, magenta M, yellow Y, and black K, density unevenness may appear in a multicolor image.

=== Image Printing Method According to the Present Embodiment ==
FIG. 13 is a flowchart showing a flow of processes and the like related to the image printing method according to the present embodiment. Hereinafter, the outline of each process will be described with reference to this flowchart. First, the printer 1 is assembled on the production line (S110). Next, a data table for suppressing density unevenness between the dot row regions is set in the printer 1 by the operator in charge of inspection (S120). In the present embodiment, since the correction target is image data indicating the gradation value of each pixel (dot formation unit), the gradation value corresponding to each pixel supplied as image data to be printed is corrected. A data table (hereinafter referred to as a correction table) is set. Here, a correction table indicating values for correcting the image data and converting it to new data is stored in the memory of the printer 1, more specifically, in the correction table storage unit 63a (see FIG. 4).

  Next, the printer 1 is shipped (S130). Then, the user who purchased the printer 1 performs the actual printing of the image. At the time of the actual printing, the printer 1 performs the raster printing for each raster line based on the correction table stored in the correction table storage unit 63a. Density correction is performed and an image is printed on the paper P (S140). Here, the main printing refers to printing of a desired image such as a natural image performed by a user or the like for printing a predetermined test pattern such as a correction pattern. The image printing method according to the present embodiment is realized by the correction table setting step (step S120) and the actual image printing (step S140). Accordingly, the contents of step S120 and step S140 will be described below.

<Step S120: Setting of correction table for suppressing density unevenness>
FIG. 14 is a block diagram illustrating devices used for setting the correction table. In addition, about the component already demonstrated, the same code | symbol is attached | subjected and description is abbreviate | omitted. In FIG. 14, a computer 702A is a computer 702A installed on the inspection line, and a process correction program is operating. The process correction program can execute a correction table generation process. This correction table generation process is based on a data group obtained by the scanner 10 reading a correction pattern as a print pattern printed on the paper P (for example, 256 gray scale data with a predetermined resolution). A correction table is generated for the target dot row region. The correction table generation process will be described later in detail. The application running on the computer 702A outputs print data for printing the correction pattern CP having the specified gradation value to the printer 1.

  FIG. 15 is a conceptual diagram of a recording table provided in the memory of the computer 702A. This recording table is prepared for each ink color, and in this embodiment, four recording colors of black, cyan, magenta, and yellow are provided corresponding to the ink colors. Then, the measurement value of the correction pattern CP printed in each section is recorded in the corresponding recording table.

  In this recording table, for example, measured values obtained by measuring the densities of a plurality of sub-patterns (described later) printed based on a plurality of gradation values (hereinafter referred to as specific gradation values) indicating different types of densities. The measured gradation value C and the specific gradation value S of each sub-pattern are recorded in association with each other. In the present embodiment, eight sub-patterns having different gradations are printed based on eight specific gradation values for each color, and the density of each sub-pattern is measured.

  In each recording table, two fields are prepared for each density. That is, eight measurement information in which the measurement gradation value C and the specific gradation value S are associated with each other is stored in the recording table for each dot row region. Specifically, in the leftmost field and the ninth field from the left in the figure, measurement information based on a correction pattern printed based on the lowest specific gradation value among eight specific gradation values. Is recorded. That is, the measured gradation value Ca of the correction pattern CPa is recorded in the leftmost field, and the specific gradation value Sa of the correction pattern CPa is recorded in the ninth field from the left. Further, in the second field from the left and the tenth field from the left, the measured gradation value Cb and the correction pattern of the correction pattern CPb having the second lowest specific gradation value among the eight types of specific gradation values are displayed. The specific gradation value Sb of CPb is recorded respectively. Thus, the measured gradation value C and the specific gradation value S corresponding to the density are sequentially recorded in each field, and the highest specific gradation among the eight kinds of specific gradation values is stored in the eighth field from the left. The measured gradation value Ch of the value correction pattern CPh, and in the rightmost field, the specific gradation value Sh of the correction pattern CPh having the highest specific gradation value among the eight types of specific gradation values. , Respectively.

  Each record is assigned a record number, and there are as many records as the number of dot row regions assumed as the length of the printable region of the paper in the transport direction. Further, the measurement gradation values Ca, Cb,..., Ch and the specific gradation values Sa, Sb corresponding to the same dot row region in the correction patterns CPa, CPb,. ,..., Sh are all recorded in records having the same record number.

FIG. 16 is a flowchart showing the procedure of step S120 in FIG. Hereinafter, the procedure for setting the correction table will be described with reference to this flowchart.
This setting procedure includes a step of printing the correction pattern CP (S121), a step of reading the correction pattern CP (S122), and a step of setting a correction table based on the measured density value for each dot row region (S123). Have Hereinafter, each step will be described in detail. In the present embodiment, the specific gradation values for printing the correction pattern are 8 kinds of gradation values, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, and 80%. To do. The printable density range is density 0 to density 100%, the gradation value corresponding to density 0 is the lowest value “0”, and the gradation value corresponding to density 100% is the highest value “ 255 ".

(1) Regarding printing of correction pattern CP (S121):
First, in step S121, the correction pattern CP is printed on the paper P for each ink color to be corrected. Here, the operator in charge of inspection and the operator of the printing system connects the printer 1 to a computer 702A installed on the inspection line in a communicable state, and the printer 1 corrects four colors of cyan, magenta, black, and yellow. The pattern CP for printing is printed. That is, the operator performs an operation for printing the correction pattern CP via the user interface of the computer 702A. By this operation, the computer 702A reads the print data of the correction pattern CP stored in the memory and outputs it to the printer 1. The printer 1 prints the correction pattern CP on the paper P based on the print data.

  At this time, the correction pattern is sequentially printed for each ink color in a preset order. The printing order is the order in which it takes a long time for the density to stabilize after printing when the correction pattern CP is printed. FIG. 17 is a diagram illustrating an example of a change in density of an image printed with ink attached to the printer 1 over time. In FIG. 17, the vertical axis represents the density of the printed image, and the horizontal axis represents the elapsed time after printing. At this time, the density of the printed image is indicated by a value measured by a known density measuring device. That is, when the measured density value hardly changes, the density is stabilized, and in FIG. 17, the graph becomes flat. In addition, an image having a large change in density immediately after printing and having a larger slope of the graph takes a shorter time to stabilize the density, and an image having a smaller slope takes a longer time to stabilize the density. In the example of FIG. 17, it takes the longest time for the image printed with cyan ink to stabilize the density, and the image printed with black ink takes the shortest time to stabilize the density. Is shown. Therefore, when the correction print pattern is printed, the correction pattern is printed in the order of cyan ink, magenta ink, yellow ink, and black ink.

  FIG. 18 is a diagram for explaining the correction pattern printing process. As shown in the drawing, when a correction pattern print command is executed (S201), first, a correction pattern is printed with cyan ink (S202). Next, a correction pattern is printed with magenta ink (S203). Subsequently, a correction pattern is printed with yellow ink (S204). Finally, a correction pattern is printed with black ink (S205).

  By the way, the time until the density is stabilized after printing varies depending on the type and components of the ink and the medium to be printed. Ink includes pigment ink and dye ink, but an image printed with dye ink has a greater change in density than pigment ink, and thus is particularly effective for a printer using dye ink. Further, when the medium is different, the time until the density is stabilized varies depending on the permeability of the ink. In the present embodiment, a correction pattern is printed that is used when the density is adjusted for each dot row region in order to suppress density unevenness between the dot row regions. For this reason, the time until the density stabilizes should be taken into consideration for a medium that is often used when printing an image for which density unevenness between dot row regions is to be suppressed. The image for which density unevenness between the dot row regions is to be suppressed is, for example, a so-called photographic image with high image quality. Therefore, the density when printed on glossy paper used for printing photographic images or the like, photographic dedicated paper, etc. It is desirable to set the order in which the correction pattern CP is printed based on the time until the image becomes stable.

  Note that the printer 1 that prints the correction pattern CP is the printer 1 that is a setting target of the correction table. That is, the correction table is set for each printer 1.

  FIG. 19 is a diagram for explaining an example of the printed correction pattern CP. FIG. 19A is a first example of a correction pattern CP in which a correction pattern for one color is printed on one print sheet, and FIG. 19B is a correction pattern for four colors on one print sheet. It is a 2nd example of the correction pattern currently printed.

  As shown in FIG. 19A, the correction pattern CP of the first example of the present embodiment has a plurality of gradation sub-patterns with different densities for each ink color, and in the order of cyan, magenta, yellow, and black. Are printed on different sheets. In this example, the correction patterns CP are printed on the basis of the eight types of specific gradation values S described above for each color of cyan, magenta, yellow, and black. That is, the eight types of density are 10%, 20%, 30%... 80%, and printing is performed based on the specific gradation value S corresponding to each density. The print data of the correction pattern CP is assumed to be cyan, magenta, yellow, and black image data in which specific gradation values S corresponding to eight different densities are assigned to all pixels, and each assumed image data is This is print data generated when halftone processing and rasterization processing are performed by the printer driver. For this reason, the print data of the correction pattern CP stored in the memory is obtained when the belt-shaped correction pattern CP is printed by an ideal printing device based on the gradation value indicating each density. Each is set to a uniform density. That is, each correction pattern CP printed by an ideal printing apparatus is printed at a substantially constant density over the entire area in the transport direction. Here, the ideal printing apparatus is a printing apparatus that is processed and manufactured as designed, and indicates a printing apparatus in which dots are formed at target positions by ink droplets ejected from nozzles.

  The difference between the correction patterns CP composed of eight sub-patterns of cyan, magenta, yellow, and black is basically only the ink color. Therefore, in the following, a correction pattern CPk composed of eight sub-patterns of black (K) will be described as a representative of the correction pattern. Further, as described above, suppression of density unevenness in multicolor printing is performed for each ink color used for the multicolor printing, but the method used for the suppression is the same. For this reason, the following description will be made in black (K), and in the following description, there is a place where only one color of black (K) is described. Is the same.

  The black (K) correction pattern CPk is printed in a band shape that is long in the transport direction at eight different densities based on the eight specific gradation values. In the example of FIG. 19A, the print range in the transport direction extends over the entire area of the paper P in the transport direction. That is, the paper P is formed in a series from the upper end to the lower end. Further, the correction pattern CPk is printed on one sheet in a state where eight sub-patterns having different densities are arranged along the print carriage movement direction.

  The correction pattern CPk is printed at a paper conveyance amount and an ink discharge timing of each nozzle according to each printing method according to a printing method such as an interlace method or a band feeding method. The raster lines of images printed by these interlace methods, band feed methods, and the like, and the nozzles that form each raster line differ depending on the printing method. For this reason, the correction pattern for suppressing the density unevenness for each dot row region where the raster line is to be formed is the paper conveyance amount actually used in the main printing and the ink ejection timing of each nozzle, that is, each printing method. It is desirable to print in each print processing mode. For example, in the case of the band feeding method, the correction pattern is printed in a print processing mode in which a sheet is conveyed by the length of the nozzle row and a raster line having the same pitch as the nozzle pitch is formed. With the interlace method, printing is performed in a processing mode in which a very small amount of paper is conveyed at the leading edge and the trailing edge of the paper and printing is performed with a specific number of nozzles. A correction pattern is printed in a print processing mode in which raster lines are formed using as many nozzles as possible while quantitatively conveying. In the case of so-called borderless printing in which printing is performed without margins on the paper, printing is performed only with the nozzles facing the grooves 24a (see FIG. 6) provided in the platen 24 at the front and rear end portions of the paper. In the portions other than the rear end, the correction pattern is printed in a print processing mode in which raster lines are formed using as many nozzles as possible while quantitatively conveying the paper. That is, when the printing method is a printing method that prints so as to generate a blank portion at the leading and trailing edges of the paper, each correction pattern is not printed over the entire area in the paper conveyance direction, A margin is formed at the rear end.

  As described above, the density correction performed based on the correction table obtained by the correction patterns printed at the same paper conveyance amount and the ink ejection timing of each nozzle as in the main printing is performed for each printing method and each printing processing mode. Since it is suitable, the accuracy of density correction is improved and density unevenness can be more reliably suppressed.

  In the correction pattern of the second example shown in FIG. 19B, the sheet is divided into four areas in the conveyance direction, and only the lengths of the correction patterns for the respective colors described in the first example are changed in the four areas. In this example, correction patterns are printed one color at a time. At this time, the correction patterns for each color are printed in the order of cyan ink, magenta ink, yellow ink, and black ink, and the cyan correction pattern CPc is printed in the region on the most downstream side in the paper transport direction. A magenta correction pattern CPm is printed in the second area, a yellow correction pattern CPy is printed in the third area from the downstream side, and a black correction pattern CPk is printed in the most upstream area. By printing in this way, the time required for the density to stabilize from the correction pattern, which takes a long time for the density to stabilize after printing, is not transported in the direction opposite to the transport direction. It is possible to print on one sheet so that the length changes sequentially.

  In this way, the correction pattern that takes the longest time for the density to stabilize after printing is printed first, and then the correction pattern is printed in the order in which the time it takes for the density to stabilize becomes shorter. As a result, the correction pattern that takes a relatively long time to stabilize the density stabilizes while the other correction patterns are printed. It is possible to stabilize the density of the pattern for use. In particular, the correction pattern that takes the longest time to stabilize the density has the longest time from the end of printing the correction pattern to the end of printing the last correction pattern until the density stabilizes. The correction pattern that takes the shortest time is the last print after printing in each correction pattern so that the time from the end of printing of the correction pattern to the end of printing of the last correction pattern is the shortest. Since the time until the end of pattern printing is set, each correction pattern can be printed more efficiently.

  In the present embodiment, an example of using a correction pattern printed based on eight types of gradation values for each color has been described, but the number of gradation values for each color is not limited to eight.

(2) Reading the correction pattern CP (step S122):
The density of each correction pattern CPka, CPkb,..., CPkh shown in FIG. 19 is measured for each dot row region by a density measuring device that can optically measure the density. This density measuring apparatus is an apparatus that can measure the average density of a predetermined number of pixels in the moving direction of the reading carriage, that is, in the direction along the dot row area, for each dot row area. Another example is a reading system having the scanner 10 and the computer 702A. The reason for evaluating the density of each dot row region with the average density of a predetermined number of pixels is that the size of dots formed on each pixel by the halftone process (including non-formation) is the floor of each pixel. This is because even if printing is performed based on image data with uniform tone values, it is different for each pixel, that is, the density of the dot row area for one line cannot be represented by one pixel.

  Reading of the correction pattern is executed by the operator setting a sheet on which the correction pattern is printed by the printer 1 in the scanner 10. At this time, the order of the correction patterns to be read is the order in which it takes a short time until the density is stabilized after the correction pattern CP is printed. That is, the correction patterns are read in the reverse order of printing and in the order of black, yellow, magenta, and cyan.

  FIG. 20 is a diagram for explaining reading processing of a correction pattern printed on different paper for each color.

  As shown in the drawing, when a command for executing a correction pattern reading process is input by the operator operating the operation unit 34 (S301), a black correction pattern is displayed on the display unit 36 of the scanner 10. Information for placing the printed paper on the platen glass 7 is displayed (S302). The display unit 36 is, for example, a liquid crystal panel capable of displaying characters, and displays “Please set a sheet of paper on which a black correction pattern is printed” on the document table. The operator places the paper on which the black correction pattern is printed on the platen glass 7 and operates the operation unit 34. At this time, the sheet on which the black correction pattern is printed is set on the platen glass 7 so that the moving direction of the reading carriage 16 and the longitudinal direction of the sub-pattern, that is, the sheet conveying direction at the time of printing coincide with each other. Is done. By operating the operation unit 34, a black correction pattern reading process is executed (S303). When the reading carriage 16 moves to the rear end side of the black correction pattern, information for placing the paper on which the yellow correction pattern is printed on the platen glass 7 is displayed on the display unit 36 ( S304). The operator places the paper on which the yellow correction pattern is printed on the platen glass 7 and operates the operation unit 34. By this operation, the yellow correction pattern reading process is executed (S305). When the reading carriage 16 moves to the rear end side of the yellow correction pattern, information for placing the paper on which the magenta correction pattern is printed on the platen glass 7 is displayed on the display unit 36 ( S306). The operator places a sheet on which a magenta correction pattern is printed on the platen glass 7 and operates the operation unit 34. By this operation, a magenta correction pattern reading process is executed (S307). When the reading carriage 16 moves to the rear end side of the magenta correction pattern, information for placing the paper on which the cyan correction pattern is printed on the platen glass 7 is displayed on the display unit 36 ( S308). The operator places a sheet on which a cyan correction pattern is printed on the platen glass 7 and operates the operation unit 34. By this operation, a cyan correction pattern reading process is executed (S309). Thereafter, when the reading carriage 16 moves to the rear end side of the cyan correction pattern, information indicating that the reading process of the correction pattern is completed is displayed on the display unit 36, and the scanner moves the 10 carriage to a predetermined position. The process returns to the standby state (S310).

  In this embodiment, the example in which the information to be transmitted to the operator is displayed on the display unit 36 of the scanner 10 has been described. However, the information may be displayed on the display device 704 connected to the scanner 10 via the computer 702. Further, although the example of operating the operation unit 34 of the scanner 10 has been described for executing the reading process, various commands are issued from the user interface on the computer 702 to which the scanner 10 is connected by operating the input device 708 of the computer 702. You may enter. FIG. 21 is a diagram for explaining an example of display on the display device 704 when the reading process is executed using the user interface of the computer.

  In this case, for example, when a command for executing a correction pattern reading process is input by the operator through the input device 708, the display device 704 displays a black correction correction as shown in FIG. Information including a comment that prompts the user to set the paper on which the pattern is printed on the document table and a radio button 704a for executing the reading process is displayed. When the operator sets a sheet on which the black correction pattern is printed on the platen glass 7 and operates the radio button, a screen indicating a state such as “reading” is displayed. When the reading carriage 16 moves to the rear end side of the black correction pattern, the display device 704 executes a reading process and a comment that prompts the user to set the paper on which the yellow correction pattern is printed on the document table. A radio button is displayed.

  When the operator sets the paper on which the yellow correction pattern is printed on the platen glass 7 and operates the radio button, a screen indicating a state such as “reading” is displayed. When the reading carriage 16 moves to the rear end side of the yellow correction pattern, the display device 704 executes a reading process and a comment that prompts the user to set a sheet on which the magenta correction pattern is printed on the document table. A radio button is displayed. When the operator sets a sheet on which the magenta correction pattern is printed on the platen glass 7 and operates the radio button, a screen indicating a state such as “reading” is displayed. When the reading carriage 16 moves to the rear end side of the magenta correction pattern, the display device 704 executes a reading process and a comment that prompts the user to set a sheet on which the cyan correction pattern is printed on the document table. A radio button is displayed. When the operator sets a sheet on which the cyan correction pattern is printed on the platen glass 7 and operates the radio button, a screen indicating a state such as “reading” is displayed. When the reading carriage 16 moves to the rear end side of the yellow correction pattern, a screen indicating “END” is displayed.

  FIG. 22 is a diagram for explaining a correction pattern reading process in which four colors are printed on one sheet.

  When reading a correction pattern printed for four colors on one sheet, when an operator inputs a command for executing a correction pattern reading process by operating the operation unit 34 (S401). Information for placing the sheet on which the correction pattern is printed on the original platen glass 7 is displayed on the display unit 36 of the scanner (S402). At this time, a message such as “Please set the paper on which the correction pattern is printed on the document table” is displayed on the display unit 36, and “A black correction pattern is printed on the paper on which the correction pattern is printed. A comment is also displayed prompting the user to position and set the end of the current side at the reading start position of the scanner 10. The operator instructs the display unit 36 to select the sheet on which the black correction pattern is printed. And the operation unit 34 is operated, whereby the correction pattern reading process is executed (S403), that is, the black correction pattern is first read (S403a). Next, the yellow correction pattern is read (S403b), then the magenta correction pattern is read (S403c), and finally the cyan correction pattern is read. Over emissions is read (S403d).

  In this case, since correction patterns for four colors are printed on one sheet, there is no need to reset the sheet. For this reason, the operator simply sets the paper on which the correction pattern is printed and operates the operation unit 34, and the reading process is executed to the end. Further, as described above, the paper set on the document table is printed in the order of cyan, magenta, yellow, and black in the transport direction. Accordingly, when the end of the paper on which the black correction pattern is printed is set to be positioned on the reading start position side of the scanner 10, the black correction pattern is first formed as the reading carriage 16 moves. Next, the yellow correction pattern is read, then the magenta correction pattern is read, and finally the cyan correction pattern is read. This order is the reverse of the order in which the correction patterns are printed. That is, when printing a correction pattern, the correction pattern that takes a long time until the density stabilizes after printing is printed sequentially from the correction pattern, and when reading, the correction that takes a short time to stabilize the density after printing is corrected. Will be read sequentially from the pattern.

  After that, when the reading carriage 16 moves to the rear end side of the cyan correction pattern, information indicating that the correction pattern reading processing has been completed is displayed on the display unit 36, and the scanner moves the 10 carriage to a predetermined position. The process returns to the standby state (S404).

  According to the present embodiment, the black correction pattern takes less time to stabilize the density than any of the yellow, magenta, and cyan correction patterns, so even if the black correction pattern is read first. The density of the black correction pattern is likely to be stable after printing another correction pattern, or is close to the density to be stabilized. The cyan correction pattern takes a longer time to stabilize the density than the black, yellow, and magenta correction patterns, but the cyan correction pattern density is stabilized by reading after the blank correction pattern. It is likely that the concentration is high or is approaching a stable concentration. For this reason, it is possible to read all the correction patterns with a more appropriate density. The first print pattern and the second print pattern of the claim are the time required for the density of one of the two correction patterns of black, yellow, magenta, and cyan to be stabilized after printing from the other. The longer one is the first print pattern, and the shorter one is the second print pattern.

  Further, according to the present embodiment, the correction pattern that takes the shortest time for the density to stabilize after printing is read first, and then the time that it takes for the density to stabilize becomes longer in order. A correction pattern is read. For this reason, a correction pattern that takes a relatively long time to stabilize the density stabilizes while the other correction patterns are being read, so that each correction pattern is inherently stable. It is possible to read at a density close to the power density. In particular, the correction pattern that takes the shortest time to stabilize the density is read first, the time from the end of printing until the end of reading is the shortest, and the correction pattern that takes the longest time to stabilize the density Since the time is set so that the time from the end of printing to the end of reading becomes the longest, the correction pattern can be read with a more accurate density.

  An example of the measured gradation value of the density of the correction pattern CPk is shown in FIG. In FIG. 23, the horizontal axis indicates the dot row area number, and the vertical axis indicates the density measurement gradation value. Here, the dot row area number is a number assigned to each dot row area virtually defined on the paper from the front end side of the paper.

  The measured gradation values shown in FIG. 23 are obtained for each dot row area even though all the dot row areas constituting the correction pattern CPk are printed based on the image data indicating the same density gradation value. Although it varies greatly in the vertical direction, this is the density unevenness caused by the variation in the ink ejection direction described above. That is, since the measured value is a value measured for each dot row area, when the interval between adjacent raster lines is narrow, a part of the adjacent raster line is also read in the dot area. On the other hand, when the interval is wide, since a part of the raster line that should be read is out of the dot row area, the density is measured small.

  By the way, the scanner 10 is connected to the printer 1 so as to be communicable. Then, each measured value of the density of the correction pattern read by the scanner 10 is recorded in a recording table prepared in the memory of the computer 702 while being associated with the dot row area number. The measured gradation value of the density output from the scanner 10 is a gray scale (data having no color information and created only by lightness) indicated by 256 gradation values. Here, the reason why this gray scale is used is that if the measured gradation value has color information, the process must express the measured gradation value only with the gradation value of the target ink color. This is because it becomes complicated.

  The density of each correction pattern CPka, CPkb,..., CPkh printed based on the eight kinds of gradation values is measured for each dot row region by the scanner 10, and the measured gradation values Ca, Cb,. ... Ch is recorded in the recording table shown in FIG.

(3) Step 123: Setting a correction table for each dot row area When density correction is performed to suppress density unevenness in the transport direction, one correction information, for example, a floor indicated by image data to be printed. It is also conceivable to correct all image data based on one correction information paired with a tone value and a corrected new gradation value. In the present embodiment, density unevenness is suppressed more appropriately and efficiently by performing correction based on a plurality of correction information corresponding to different densities. For this reason, a plurality of correction information is acquired, and an image data correction table is set using the acquired plurality of correction information.

<Setting of image data correction table>
FIG. 24 is a conceptual diagram of an image data correction table stored in a correction table storage unit 63 a provided in the memory 63 of the printer 1.

  The image data correction table shown in FIG. 24 is stored in the correction table storage unit 63a when image data is to be corrected. The image data correction table is prepared for each ink color to be corrected, and has a record for recording a new gradation value after correction. Each record is assigned a record number, and the new corrected gradation value calculated based on the measured value or the like is recorded in a record having the same record number as the record of the measured value. This record is also provided by the number of dot row areas corresponding to the length of the printable area of the paper in the transport direction.

  Eight pairs that are paired with specific gradation values Sa, Sb,..., Sh and measurement gradation values Ca, Cb,..., Ch recorded in each record of each recording table by the method described above. First, a plurality of correction information is acquired using the measurement information (Sa, Ca), (Sb, Cb),..., (Sh, Ch). When the image data correction table is set, for each dot row area (record), there is information that makes a pair of a gradation value indicating a predetermined density and a new gradation value after the correction of the density. It becomes correction information.

  Correction information corresponding to each gradation value is obtained as follows. First, certain correction information is acquired using three pieces of measurement information among the eight pieces of measurement information. Similarly, for example, a total of four pieces of correction information are acquired. Next, linear interpolation is performed using any two of the acquired four correction information, the highest gradation value and the lowest gradation value, and a new gradation after correction corresponding to another gradation value is obtained. Calculate the value. The calculated new gradation value after correction and the gradation value indicating each density are associated with each other as correction information, and stored in the field corresponding to the predetermined density in the image data correction table. For example, when acquiring correction information corresponding to a density of 30%, each density of a correction pattern having a density of 10%, a correction pattern having a density of 30%, and a correction pattern having a density of 50% is measured to obtain three pieces of measurement information. Is used for linear interpolation. Further, when acquiring correction information corresponding to a density of 50%, three pieces of measurement information obtained by measuring each density of a correction pattern having a density of 30%, a correction pattern having a density of 50%, and a correction pattern having a density of 70%. A new gradation after correction using three measurement information acquired from the correction pattern of a density for which a new gradation value is to be obtained and a density of, for example, ± 20%. Calculate the value.

  FIG. 25 is a graph for explaining primary interpolation performed using the three correction information. Note that the horizontal axis of the graph is the black (K) gradation value (hereinafter referred to as the data gradation value) S indicated by the image data, and the vertical axis is the gray scale gradation as the measurement value C. Values (hereinafter referred to as measurement gradation values) are associated with each other. In the following, the coordinates of each point on this graph are indicated by (S, C).

  As is well known, linear interpolation determines the function value between or outside two known quantities, assuming that the three plotted points are on a straight line. In the present embodiment, the known amount is the three pairs of measurement information (Sa, Ca), (Sb, Cb), (Sc, Cc), and the function value to be obtained is the measured gradation value C. Is the data gradation value S that becomes the target value Ss1. In the present embodiment, the target value Ss1 is a gradation value indicating the density of an image to be printed based on a predetermined gradation value, and an image having the density of the predetermined gradation value to be originally printed. Is a measured gradation value of a color sample (density sample) having the same density as. Here, the color sample (density sample) having the same density as the density that should be originally expressed by the gradation value of the measurement information that is the middle value of the three pieces of measurement information is output by the scanner 10. This is the gray scale measurement gradation value. This color sample indicates the absolute standard of density. That is, if the gradation value C measured by the scanner 10 indicates the target value Ss1, the measurement object appears to be the density of the middle value Sb. It is shown that. That is, the density that should be printed at the density that provides the target value Ss1 corresponds to the target density. This target density is not necessarily the density of the color sample, and may be an average value of measured values measured for each dot row region, for example. In the case of using a color sample, it is possible not only to suppress density unevenness but also to correct the density of the printed image on the basis of the density of the color sample. Further, when the average value of the measurement values is used, it is not necessary to measure the color sample, and it is possible to suppress the density unevenness while acquiring the correction information earlier.

  As shown in FIG. 25, for example, three pieces of measurement information (Sa, Ca), (Sb, Cb), and (Sc, Cc) out of eight pieces of measurement information have coordinates (Sa, Ca) on the graph, respectively. It is represented as point A, point B of (Sb, Cb), and point C of (Sc, Cc). A straight line BC connecting the two points B and C shows the relationship between the change in the data gradation value S and the change in the measured value C in the high density range, and the straight line connecting the two points A and B. AB indicates the relationship between the change in the data gradation value S and the change in the measured value C in the low density range.

  Then, from the graph constituted by the two straight lines AB and BC, the value So of the data gradation value S at which the measurement gradation value C becomes the target value Ss1 is read, and the middle value Sb of the three measurement information is obtained. Is the new gradation value So after the correction of the density of the measurement information. For example, as shown in the figure, when the target value Ss1 is larger than the measured value Cb of the point B, linear interpolation is performed using the straight line BC, and the data gradation at which the measured value C becomes the target value Ss1. A new gradation value So after correction corresponding to the value S is set. Conversely, when the target value Ss1 is smaller than the measured tone value Cb of the point B, linear interpolation is performed using the straight line AB, and the data tone value at which the measured tone value C becomes the target value Ss1. A new gradation value So after correction corresponding to S is assumed.

  In this way, for example, correction information corresponding to 30% from each correction pattern of 10% density, 30% density, and 50% density is obtained from each correction pattern of 20% density, 40% density, and 60% density. % Correction information corresponding to 50% from the correction patterns of density 30%, density 50% and density 70%, correction information corresponding to 50%, density correction patterns of density 40%, density 60% and density 80%. Correction information corresponding to 60% is acquired.

  FIG. 26 is a graph for explaining an image data correction table in which data gradation values given in supplied image data are associated with new gradation values after correction.

  In the graph of FIG. 26, the horizontal axis represents the data gradation value S of black (K) indicated by the image data, and the vertical axis represents the new gradation value after correction. Then, a data gradation value corresponding to a density of 30% (for example, 77), a data gradation value corresponding to a density of 40% (for example, 102), a data gradation value corresponding to a density of 50% (for example, 128), and a density of 60%. As the data corresponding to the data gradation value corresponding to (for example, 153), the acquired new gradation value after correction is plotted, and the respective pieces of correction information are connected by a straight line. Thus, when connecting two correction information with a straight line, one correction information connected becomes the 1st correction information, and the other becomes the 2nd correction information. At this time, the minimum density that can be expressed in the printed image, that is, the gradation value “0” corresponding to the density 0, the gradation value So “0” corresponding to the density 0, and the correction information corresponding to the density 30%. In a region connected by a straight line, the correction information corresponding to the density of 30% becomes the first correction information, and the gradation value “0” corresponding to the density 0 and the gradation value So “0” corresponding to the density 0 are displayed. Becomes the second correction information. Further, the gradation value “255” corresponding to the maximum density, that is, the density 100%, the gradation value So “255” corresponding to the density 100%, and the correction information corresponding to the density 60% are connected in a straight line. In the area, the correction information corresponding to the density of 60% becomes the first correction information, and the gradation value “255” corresponding to the density of 100% and the gradation value So “255” corresponding to the density of 100% are the second. It becomes correction information.

The correction table is set based on this graph. In the case of the present embodiment, new corrected gradation values acquired in the fields corresponding to densities 0, 30%, 40%, 50%, and 60% are stored. Then, for example, a new gradation value after correction of a density that is between 30% density and 40% density, that is, a density that excludes density 30% and density 40%, is the first gradation value indicating density 30%. The gradation value is a gradation value indicating 40% density as the second gradation value, the first correction information (C ₃₀ , So ₃₀ ) associated with the density 30% and the second correction associated with the density 40%. By linearly interpolating the information (C ₄₀ , So ₄₀ ), new tone values for printing all the dot row regions at the same density are obtained, and the corresponding values in the image data correction table are obtained. Remembered.

For example, when a gradation value C ₃₅ indicating a density of 35% is given as image data, it is converted to So ₃₅ as a new gradation value after correction based on the graph of FIG. A method for obtaining a new gradation value after correction corresponding to each data gradation value is expressed as follows.

A straight line connecting the first correction information associated with the density of 30% and the second correction information associated with the density of 40% can be expressed by Expression 1 shown below.
_{Sox = [(So 30 -So 40} ) / (C 30 -C 40)] · (Cx-C 30)
+ So ₃₀ …… Formula 1
Then, substituting C ₃₅ to an arbitrary gray scale value Cx of the formula 1, new gradation value Sox after correction for 35% density of the image data is obtained.
A program for performing a calculation for obtaining a new gradation value after correction is stored in a memory provided in the computer 702A of the inspection line described above.

  The new gradation value after correction for each density obtained by the calculation is stored in the corresponding field of the correction table shown in FIG. That is, the computer 702A first reads three pieces of measurement information (Sa, Ca), (Sb, Cb), and (Sc, Cc) from the same record of the recording table, and acquires four pieces of correction information. Next, after correcting between the two densities corresponding to the two correction information by substituting two correction information among the obtained four correction information, the correction information of the lowest density, and the correction information of the highest density into Equation 1. A new gradation value is calculated. The calculated new gradation value after correction is recorded in the record having the same record number in the image data correction table.

  When the actual printing is performed (S140), the image data supplied from the application is converted into print data (S140a). That is, the supplied image data is first subjected to resolution conversion processing and color conversion processing. Thereafter, each pixel data of the CMYK image data is processed by a dither method or the like by halftone processing, and each of the C, M, and K image data is corrected based on a correction table. Is converted to The converted CMYK image data is subjected to rasterization processing and converted into print data. Then, the printer prints based on the converted print data (S140b). By converting and printing the image data in this way, it is possible to print a good image with suppressed density unevenness in the paper transport direction.

  In addition, density unevenness between the dot row areas occurs due to the printed dot row, but the dot row is generated due to the difference in the printing method, the discharge unit used, the relative position of the dot row to be formed, etc. Is different. Therefore, as in the above-described printing apparatus, a belt-like correction pattern is printed along the paper conveyance direction for each gradation of cyan, magenta, yellow, and black to be corrected, and the printed correction pattern By executing the correction based on the result of reading the image, it is possible to execute an appropriate correction corresponding to the printing method for actually printing, the ejection unit for actually forming dots, the relative position with respect to the paper, and the like. .

=== Other Embodiments ===
The above embodiment is mainly described for the printer 1, but it goes without saying that the disclosure includes a printing apparatus, a printing method, a printing system, and the like.
Further, the printer 1 and the like as one embodiment have been described, but the above-described embodiment is for facilitating understanding of the present invention, and is 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.

  In the present embodiment, the printer 1 and the scanner 10 have been described in the printing system connected to the computer. However, the printer can print the correction pattern independently, or the scanner can read the correction pattern alone. If possible, the density can be adjusted using a printer as a printing apparatus and a scanner as a reading apparatus so as to suppress density unevenness between the dot row regions. Similarly, even in a form in which the reading unit and the printing unit are integrated, such as a so-called digital copying machine, the density can be adjusted to suppress density unevenness between the dot row regions.

  In the present embodiment, the printer and the printing method for correcting the density unevenness generated in the paper conveyance direction have been described. However, the correction method described above is based on the printer 1 such as vibration caused by the movement of the print carriage on which the head is mounted. The present invention can also be applied to vertical stripe-shaped density unevenness that occurs in the direction along the transport direction due to the mechanism to be configured.

<About the printer>
In the above-described embodiment, the printer 1 has been described as the printing apparatus. However, the present invention is not limited to this. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, liquid vaporizer, organic EL manufacturing apparatus (particularly polymer EL manufacturing apparatus), display manufacturing apparatus, film formation The same technique as that of the present embodiment may be applied to various recording apparatuses to which an ink jet technique is applied such as an apparatus and a DNA chip manufacturing apparatus. These methods and manufacturing methods are also within the scope of application.

<About ink>
Since the above-described embodiment is an embodiment of the printer 1, dye ink or pigment ink is ejected from the nozzle. However, the ink ejected from the nozzle is not limited to such ink.

<About nozzle>
In the above-described embodiment, ink is ejected using a piezoelectric element. However, the method of ejecting ink is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

<About the movement direction of the print carriage that ejects ink>
In the above-described embodiment, unidirectional printing in which ink is ejected only when the print carriage 31 moves in the forward direction has been described as an example. However, the present invention is not limited to this, and ink is ejected when the print carriage 31 reciprocates in both directions. In other words, so-called bidirectional printing may be performed.

It is explanatory drawing which showed the external appearance structure of the printing system. 1 is a block diagram of an overall configuration of a printing system. 1 is an explanatory diagram showing a schematic configuration of a scanner as an example of a reading apparatus according to the present invention. FIG. 1 is a block diagram of an overall configuration of a printer 1 according to an embodiment. 1 is a schematic diagram of an overall configuration of a printer 1 according to an embodiment. 1 is a side sectional view of an overall configuration of a printer 1 according to an embodiment. FIG. 4 is an explanatory diagram showing the arrangement of nozzles on the lower surface of a head 41. 4 is an explanatory diagram of a drive circuit of a head 41. FIG. It is a timing chart explaining each signal. 3 is a schematic explanatory diagram of basic processing performed by a printer driver 711. FIG. It is a flowchart of the operation | movement at the time of printing. FIG. 6 is a diagram for explaining density unevenness that occurs in the conveyance direction of a sheet P in an image printed in monochrome. 6 is a flowchart showing a flow of processes and the like related to the image printing method according to the embodiment. It is a block diagram explaining the apparatus used for the setting of the table for correction | amendment. FIG. 3 is a conceptual diagram of a recording table provided in a memory of a computer 702A. It is a flowchart which shows the procedure of step S120 in FIG. FIG. 4 is a diagram illustrating an example of a change in the density of an image printed with ink attached to the printer 1 over time. It is a figure for demonstrating the printing process of the pattern for a correction | amendment. FIG. 19A is a first example of a correction pattern CP in which a correction pattern for one color is printed on one printing paper, and FIG. 19B is a correction pattern for four colors on one printing paper. It is a 2nd example of the correction pattern currently printed. It is a figure for demonstrating the reading process of the correction pattern printed on the separate paper for every color. FIG. 20 is a diagram for explaining an example of display on the display device 704 when reading processing is executed using a user interface of a computer. It is a figure for demonstrating the reading process of the correction pattern printed by 4 colors on the paper of 1 sheet. It is a figure which shows an example of the measurement gradation value of the density | concentration of correction pattern CPk. 4 is a conceptual diagram of an image data correction table stored in a correction table storage unit 63a provided in the memory 63 of the printer 1. FIG. It is a graph for demonstrating the primary interpolation performed using three correction information. It is a graph for demonstrating the image data correction table which matches the data gradation value given with the supplied image data, and the new gradation value after correction | amendment.

Explanation of symbols

1 inkjet printer (printer), 5 original, 6 platen cover,
7 platen glass, 8 light source, 10 scanner, 11 CIS unit,
12 guides, 14 rod lens arrays, 15 CCD sensors,
16 reading carriage, 18 driving means, 20 transport unit, 21 paper feed roller,
22 conveying motor, 23 conveying roller, 24 platen, 24a groove,
25 paper discharge roller, 29 guide receiving part,
30 print carriage unit, 31 print carriage,
32 printing carriage motor, 34 operation unit, 36 display unit, 38 control unit,
40 head units, 41 heads, 50 sensors, 51 linear encoders,
52 Rotary encoder, 53 Paper detection sensor, 54 Paper width sensor,
60 controller, 61 interface unit, 62 CPU,
63 memory, 63a correction table storage,
64 unit control circuit, 644A original drive signal generation unit, 644B drive signal shaping unit,
90 ink cartridges,
181 timing belt, 182 pulley,
183 pulse motor, 184 pulley,
700 printing system, 702 (702A) computer,
704 display device, 708 input device, 708A keyboard, 708B mouse,
710 recording / reproducing apparatus,
710A flexible disk drive device,
710B CD-ROM drive device,
711 Printer driver, 712 Video driver,
714 application program,
802 memory, 804 hard disk drive unit,
CP correction pattern, ODRV original drive signal

Claims (16)

In a printing method for printing an image by adjusting the density based on the density of a printing pattern printed with different colors of ink,
A first printing step of printing a first printing pattern among the printing patterns;
After the first printing step, a second printing step for printing a second printing pattern in which the time taken for the density to stabilize is shorter than the first printing pattern;
A third printing step for printing an image having a density adjusted based on the density of the first print pattern and the density of the second print pattern;
A printing method characterized by comprising: The printing method according to claim 1,
In a printing apparatus having a plurality of ink discharge portions arranged along a predetermined direction for each color of the ink, ink is discharged while moving the plurality of discharge portions in a moving direction intersecting the predetermined direction. When printing
A printing method, wherein the density is adjusted for each dot row area in order to suppress density unevenness between the dot row areas in a medium in which the dot rows along the moving direction are formed in each of the ejection units. . The printing method according to claim 1 or 2,
Each of the printing patterns has a sub-pattern printed with a plurality of gradations. The printing method according to claim 3,
The printing method, wherein the sub-pattern is printed along the predetermined direction of the medium. In the printing method of Claim 3 or Claim 4,
The printing method, wherein the sub-patterns are printed side by side along the moving direction. The printing method according to any one of claims 1 to 5,
The plurality of print patterns, the time taken for the density to stabilize from the print pattern that takes the longest time for the density to stabilize after printing to the print pattern that takes the shortest time for the density to stabilize The printing method is characterized in that printing is performed in an order such that the lengths become shorter. The printing method according to any one of claims 1 to 6,
The printing method, wherein the print pattern is printed on a different medium for each color of the ink. The printing method according to any one of claims 1 to 6,
The printing method is characterized in that the printing pattern is printed on one medium so that the length of time required for the density to stabilize is sequentially changed along the predetermined direction. In a printing method of a printing pattern for printing a printing pattern for each ink color with a plurality of different colors of ink,
A first printing step of printing a first printing pattern among the printing patterns;
After the first printing step, a second printing step for printing a second printing pattern in which the time taken for the density to stabilize is shorter than the first printing pattern;
The printing method of the printing pattern characterized by having. In a reading method of reading a print pattern printed with each of a plurality of different colors of ink,
A first reading step of reading a first printing pattern among the printing patterns;
After the first reading step, a second reading step of reading a second print pattern that takes longer than the first print pattern to stabilize the density;
A reading method comprising: The reading method according to claim 10.
The plurality of print patterns, the time taken for the density to stabilize from the print pattern that takes the shortest time for the density to stabilize after printing to the print pattern that takes the longest time for the density to stabilize A reading method characterized in that reading is performed in the order of increasing length. It has a plurality of ejection units that eject a plurality of different types of ink,
In a printing apparatus that prints an image by adjusting the density based on the density of a print pattern printed with each of the ink ejected from the plurality of ejection units,
Among the print patterns, after printing the first print pattern, printing a second print pattern in which the time taken for the density to stabilize is shorter than the first print pattern in the previous period,
A printing apparatus that prints an image having an adjusted density based on the density of the first print pattern and the density of the second print pattern. It has a plurality of ejection units that eject a plurality of different types of ink,
In a printing apparatus that prints a print pattern for each ink using ink ejected from the plurality of ejection units,
A printing apparatus that prints a second print pattern shorter than the first print pattern in the previous period after the first print pattern is printed out of the print patterns. It has a display for displaying information to be communicated to the operator,
In a reading device for reading a print pattern printed with a plurality of different types of ink,
After reading the first print pattern among the print patterns,
A reading apparatus that displays information prompting an operation for reading a second print pattern, which takes a longer time to stabilize the density than the first print pattern, on the display unit. (A) a computer body;
(B) a plurality of ejection units that are connected to the computer main body and eject a plurality of different types of ink;
Of the print patterns printed with the ink ejected from the plurality of ejection sections, after the first print pattern is printed, the second print pattern that takes less time to stabilize the density than the first print pattern is printed. A printing device to
(C) having a display unit connected to the computer body for displaying information to be communicated to the operator;
A reading device that displays information prompting an operation for reading the first print pattern on the display unit after reading the second print pattern out of print patterns respectively printed with a plurality of different types of ink. When,
Have
(D) A printing system that prints an image having a density adjusted based on a result of reading the first printing pattern and the second printing pattern printed by the printing device with the reading device. . It has a plurality of ink discharge portions arranged along a predetermined direction for each of a plurality of different colors of ink, and discharges ink while moving the plurality of discharge portions in a moving direction crossing the predetermined direction. In the printing device that prints the image,
In the printing method of printing an image by adjusting the density based on the density of each printed pattern with the plurality of colors of ink,
Each of the print patterns has a sub-pattern printed at a plurality of gradations, and is printed on a different medium for each color of the ink,
The sub-pattern is printed along the predetermined direction of the medium, and arranged side by side along the moving direction,
A first printing step of printing a first printing pattern among the printing patterns;
After the first printing step, the second printing step for printing in an order such that the time required for the density to stabilize is sequentially reduced to the printing pattern that takes the shortest time for the density to stabilize;
The density is adjusted for each dot row area based on the density of the print pattern in order to suppress density unevenness between the dot row areas in the medium on which the dot rows along the moving direction are formed in each of the ejection units. And a third printing step for printing an image having the adjusted density,
A printing method characterized by comprising: