JP2005193645A - Discharge controlling device, head unit, ink-jet cartridge, ink discharging device, discharge controlling method, program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a constraint to the kinds of usable ink and the ink installing-position with an ink discharging device. <P>SOLUTION: The discharge controlling device 1 capable of controlling two or more kinds of head units 3 (1 to N) which differ in the combination of an ink cartridge 3B (for example, kinds of ink and ink arrangement) is provided. For this purpose, the discharging control section 1 is provided with a discrimination section 1A performing the task of discriminating the kinds of the head units 3 installed in the ink discharging device 2 and a mode selection section 1B performing the task of selecting the printing mode suitable for the discriminated head units 3 (1 to N). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  One embodiment of the present invention relates to an ink ejection device that ejects ink droplets and deposits them on an object, and an ejection control device that controls the ejection thereof. Another aspect of the invention relates to an ink cartridge filled with ink. Another aspect of the invention relates to a head unit to which an ink cartridge is mounted. Another embodiment of the present invention relates to a discharge control method and program for realizing a discharge control technique. Another aspect of the invention relates to a recording medium on which the program is recorded.

Current ink ejection devices can eject ink droplets with very high resolution. The higher the resolution, the greater the amount of information per unit area. Therefore, the current ink ejecting apparatus can print a much finer image than before.
By the way, the ink ejection apparatus expresses light and dark by the density of dots. A dot is a minimum unit ink droplet constituting one pixel. For this reason, the dot tends to become mottled in the highlight portion. In particular, when the dot diameter is large, the dots themselves are perceived. In this case, improvement in resolution does not lead to improvement in print quality.
Therefore, various ideas have been made now. For example, there is a method of reducing the ink density itself. In this case, the dots themselves can be hardly perceived. As a result, graininess is reduced and print quality is improved.

For example, there is a method of reducing the amount of ink droplets that can be ejected. In this case, the dot diameter is reduced. As a result, it becomes difficult to perceive the dots in the highlight portion. As a result, graininess is reduced and print quality is improved. In this method, it is necessary to hit many dots in the dark portion. That is, the printing speed becomes slow.
In addition, for example, there is a method using dedicated ink or dedicated paper. For example, when printing a photographic image, glossiness is expressed with dedicated ink. However, since the color development characteristics vary depending on the paper, image processing corresponding to the printing paper is required.
WO01 / 039981

  As described above, there are various techniques for improving the print quality. However, these techniques are a combination of just a few. In addition, the ink arrangement is fixed in advance. Thus, the current system lacks arbitraryness.

Based on the above fact recognition, the inventor proposes a print control technique that can use an abundant ink system with optimum print quality.
(A) Invention 1
In order to achieve this object, one invention proposes a discharge control device shown below. FIG. 1 shows an ink ejection apparatus 2 to which an ejection control apparatus 1 according to one invention is applied. This discharge control device 1 is suitable when a plurality of types of head units 3 having different combinations of ink cartridges are mounted in an exchangeable manner.
The discharge control device 1 includes an identification unit 1A and a mode selection unit 1B. The identification unit 1A is used to identify the type of the mounted head unit. The mode selection unit 1B is used to select a print mode suitable for the identified head unit.
With this configuration, the ejection control device 1 selects a print mode corresponding to a combination of ink cartridges mounted on the head unit. As a result, the printing result is optimized for the combination of ink cartridges.

The head unit 3 is mounted with a head 3A and an ink cartridge 3B. The head 3A is a group of nozzles that eject ink droplets. Usually, the same number of heads as ink cartridges are arranged.
The head 3A includes a fixed head type and a movable head type. In the fixed head type head unit 3, nozzles are arranged over the same length as the printing width. On the other hand, the movable head type head unit has nozzles arranged in a small range. In general, the difference between these head systems is determined by the drive mechanism on the side of the ink ejection apparatus to which the head unit is mounted.
The ink cartridge 3B is a container or space filled with ink. The ink cartridge 3A is, for example, built in or attached to the head unit 3 in advance. The ink cartridge 3A includes one in which each container corresponding to one print head is formed independently, and one in which a plurality of containers are integrally formed.

Various combinations of ink cartridges or inks mounted on the head unit 3 are possible depending on the purpose and application. For example, the type of ink and the ink arrangement are different. The head unit holds information that identifies the combination of these elements in an identifiable state. Based on this information, the discharge control device optimizes the print mode.
Here, the types of ink include color, density, application, printing object, colorant, solvent, and the like. For example, there are types of colors such as black ink and color ink. Usually, three colors of cyan, magenta, and yellow are used as color inks. Of course, colors other than these may be filled.
Further, for example, there are kinds of density such as dark, normal, and light. By having a plurality of densities, it is possible to use them according to the color density. If these are used under appropriate conditions, the print quality can be improved.
Further, for example, there are applications for characters, photographs, and the like. The performance required for inks varies depending on the application. For example, the performance that disappears after a certain time is required. In addition, for example, performance that can be erased by a certain process is required.

In addition, the machine is required to have a readable performance that is invisible to humans. Also in this case, the print quality can be improved by using it under appropriate conditions.
Further, for example, the print target includes paper (plain paper, photographic paper, cardboard, etc.), cloth, wood, metal, plastic, glass, and the like. A dedicated ink is used in accordance with these print targets.
Usually, the ink ejection apparatus has one or more of these as print targets. Also in this case, the print quality can be improved by using it under appropriate conditions.
In addition, for example, the color material has a classification of pigment ink and dye ink. Further, for example, the solvent includes a classification such as water-based ink and oil-based ink. The color development characteristics vary depending on the composition of these inks. For this reason, in order to improve print quality, it is necessary for the discharge control device to be able to identify these pieces of information.

As described above, there are various types of ink types, and signal processing corresponding to them is required. Furthermore, the present invention also contemplates ink cartridges or ink arrays. In the ink ejecting apparatus currently used, one ink cartridge for each color is arranged at a predetermined position.
In this case, the information about the ink arrangement is meaningless. This is because the ink arrangement is determined in advance so as to be compatible with the signal processing system of the ink ejection apparatus.
In contrast, the inventor proposes a technical method capable of handling a head unit in which various types of ink are mounted at arbitrary positions.
In the case of this technique, it is necessary to notify the ejection control apparatus 1 which ink cartridge is mounted at which position. Based on this information, the signal processing system to which the optimized printing mode is applied by the discharge control apparatus is determined.
Incidentally, this technique is suitable when the combination of the type of ink and the arrangement (position) of ink is arbitrary. The identification unit 1A identifies the type of the mounted head unit 3 based on, for example, an identification signal acquired from the head unit 3. In the case of this identification unit 1A, an identification signal can be automatically acquired. A mechanism that enables the processing to be automated will be described later.

In addition, the identification unit 1A identifies the type of the mounted head unit 3 based on, for example, a setting when the head unit 3 is mounted. This setting is manually performed by the user. For example, a slide type or rocker type dip switch is used. For example, the setting is made from the screen side of a computer connected by a user via a network or a cable.
Further, the mode selection unit 1B selects a print mode suitable for the identified head unit 3. By selecting the print mode, the contents of various signal processes executed by the ink ejection apparatus are determined. As a result, the printing result is optimized.
It is desirable that the mode selection unit 1B can select a print mode that uses a plurality of ink cartridges filled with ink of the same color and the same density. For example, there are two black ink cartridges and two ash ink cartridges.

In such a case, there may be a print mode in which one color is selectively used in addition to the case where printing is performed using ink cartridges of all colors. In this case, the printing mode corresponding to the position of the ink cartridge to be selected and the ink color is selected. This print mode is effective when one ink cartridge runs out of ink during use.
Further, it is desirable that the mode selection unit 1B can select a print mode in which a plurality of ink cartridges filled with the same color and the same density of ink are used uniformly. In this case, one color is printed using a plurality of heads.
In addition, even when there is a defect in ejection of ink droplets from one print head, a masking effect by ink droplets from a plurality of print heads can be expected. Here, the discharge failure includes a case where the discharge amount is insufficient (including a case where the discharge is not performed), a deviation of the landing position, and the like.

Further, it is desirable that the mode selection unit 1B corresponds to a color printing mode corresponding to a plurality of color inks and a monochrome printing mode corresponding to dark and light single color inks. In this case, the mode selection unit 1B can apply an optimum print mode corresponding to the replacement of the head unit. Further, it is desirable that the mode selection unit 1B can select the print mode to be used according to the position where the ink cartridge is not attached. This print mode is effective when no ink cartridge is installed in all of the installable slots.
In this case, only a print head capable of supplying ink can be used to achieve the required print quality. In addition, it is not necessary to mount unnecessary ink cartridges in the head unit by supporting this printing mode.

(B) Invention 2
In order to achieve the above-described object, one invention proposes the following discharge control device. FIG. 2 shows an example of an ink ejection device 12 to which the ejection control device 11 according to one invention is applied. This discharge control device 11 is suitable when a plurality of types of ink cartridges can be individually mounted on the head unit.
The discharge control device 11 also includes an identification unit 11A and a mode selection unit 11B. The identification unit 11A is used to identify the mounting state of the ink cartridge. The mode selection unit 11B is used to select a print mode suitable for the identified mounting state.
With this configuration, the ejection control device 11 can mount any ink cartridge 14 on the head unit in any combination. Then, the printing mode corresponding to the mounting state is selected. As a result, the printing result of the ink ejection device can be optimized for the combination of ink cartridges.

In FIG. 2, the head unit 13 is attached to the ink ejection device 12 in advance. However, as shown in FIG. 3, the head unit 13 itself may be detachable from the ink discharge device 12.
The present invention is suitable when the head 13A and the ink cartridge 14 are separated. Of course, the head 13A includes a fixed head type and a movable head type. Further, the ink cartridge 14 includes one in which each container corresponding to one print head is formed independently, and one in which a plurality of containers are integrally formed.
In the case of the present invention, the user can freely select the ink cartridge 14 to be mounted on the head unit 13. That is, the type of ink can be freely selected. Further, the user can freely select the position where the ink cartridge 14 is mounted. Examples of ink types and ink arrangements are the same as in the above-described invention.

Here, the identification unit 11 </ b> A identifies the mounting state of the mounted ink cartridge 14 based on, for example, an identification signal acquired from the head unit 13. In the case of this identification part 11A, an identification signal can be acquired automatically. A mechanism that enables an automatic mechanism will be described later.
In addition, the identification unit 11A identifies the mounting state of the ink cartridge 14 based on, for example, settings when the head unit 13 is mounted. This setting is manually performed by the user. For example, a slide type or rocker type dip switch is used. For example, the setting is made from the screen side of a computer connected by a user via a network or a cable.
Further, the mode selection unit 11B selects a print mode suitable for the identified mounting state. By selecting the print mode, the contents of various signal processes executed by the ink ejection apparatus are determined. As a result, the printing result is optimized.

It is desirable that the mode selection unit 11B can select a print mode that uses a plurality of ink cartridges filled with ink of the same color and the same density. For example, there are two black ink cartridges and two ash ink cartridges.
In such a case, there may be a print mode in which one color is selectively used in addition to the case where printing is performed using ink cartridges of all colors. In this case, the printing mode corresponding to the position of the ink cartridge to be selected and the ink color is selected. This print mode is effective when one ink cartridge runs out of ink during use.

Further, it is desirable that the mode selection unit 11B can select a print mode in which a plurality of ink cartridges filled with the same color and the same density of ink are used uniformly. In this case, one color is printed using a plurality of heads.
In this case, a masking effect by ink droplets from a plurality of print heads can be expected even when there is a defect in ejection of ink droplets from one print head. Here, the discharge failure includes a case where the discharge amount is insufficient (including a case where the discharge is not performed), a deviation of the landing position, and the like.
Further, it is desirable that the mode selection unit 11B corresponds to a color printing mode corresponding to a plurality of color inks and a monochrome printing mode corresponding to light and dark single color inks. In this case, the mode selection unit 1B can apply an optimum print mode corresponding to the replacement of the ink cartridge.

Further, it is desirable that the mode selection unit 11B can select the print mode to be used according to the position where the ink cartridge is not mounted. This print mode is effective when no ink cartridge is installed in all of the installable slots.
In this case, only a print head capable of supplying ink can be used to achieve the required print quality. In addition, it is not necessary to mount unnecessary ink cartridges in the head unit by supporting this printing mode.

(C) Invention 3
The head unit 3 in FIG. 1 is attached to the ink ejection device 2 in an exchangeable manner. Some of the head units 3 can automatically notify the ejection control device 1 of the type of the head unit when attached to the ink ejection device 2.
For example, when the ink ejection device 2 is mounted on the mounting mechanism, a mechanical structure capable of notifying the information about the combination of a plurality of ink cartridges held inside and the mounting position thereof in a distinguishable manner through mechanical coupling with the mounting mechanism. Some have.
Examples of such a mechanical structure are shown in FIGS. 4 (A) and 4 (B). In either case, a sensor or switch mechanism for detecting information is provided on the ink ejection device 2 side. By these, ON or OFF of the arranged switch group is electrically detected. For example, a switch whose potential changes when the switch is turned on or off is used.

FIG. 4A shows an example in which one or a plurality of identification protrusions 3 </ b> C are provided on one of the side surfaces of the head unit 3. For example, the identification information is associated with the number of protrusions 3C. Further, for example, the identification information is associated with the position where the protrusion 3C is provided. For example, these combinations are applied.
FIG. 4B is an example in which one or a plurality of identification recesses (holes, steps) 3D are provided on one of the side surfaces of the head unit 3. For example, the identification information is associated with the number of the recesses 3D. Further, for example, the identification information is associated with the position where the recess 3D is provided. For example, these combinations are applied.
In addition, for example, when the ink ejection device 2 is mounted on the mounting mechanism, a connection terminal that can identify information regarding the combination of a plurality of ink cartridges held inside and the mounting position thereof through electrical connection with the mounting mechanism. There is something to have.

Examples of such connection terminals are shown in FIGS. FIG. 4C shows an example in which one or a plurality of identification terminals (electrodes) 3E are provided on one of the side surfaces of the head unit 3. For example, the identification information is associated with the number of terminals 3E. For example, the identification information is associated with the position where the terminal 3E is provided. For example, these combinations are applied.
The ink ejection device 2 is provided with a sensor or a switch mechanism for detecting information. By these, ON or OFF of the arranged switch group is electrically detected. For example, a switch whose potential changes depending on whether or not the terminal is in contact is used.
FIG. 4D shows an example in which the memory 3F is built in the head unit 3, and identification information indicating the type is recorded in the memory 3F. In this case, the identification information of the memory 3F is read through the terminal 3G. The read identification information is given to the discharge control device 1.

(D) Invention 4
The head unit 13 shown in FIG. 2 has an ink cartridge 14 mounted in an exchangeable manner. Some of the head units 13 can automatically notify the ejection control device 11 of the mounting state of the ink cartridge 14 by mounting with the ink ejection device 12.
Here, the ink cartridge 14 and the head unit 13 are provided with a mechanical structure and connection terminals similar to those shown in FIG. An example in which identification is possible through mechanical coupling is shown in FIGS.
FIG. 5A shows an example in which an identification protrusion 14A is provided on the ink cartridge 14 and an information detection sensor or switch mechanism 13B is provided on the head unit 13. FIG. 5B shows an example in which the ink cartridge 14 is provided with an identification recess 14B, and the head unit 13 is provided with an information detection sensor or switch mechanism 13C.
In addition, examples in which identification is possible through connection terminals are shown in FIGS.
FIG. 5C shows an example in which an identification terminal (electrode) 14 </ b> C is provided in the ink cartridge 14 and an information detection sensor or switch mechanism 13 </ b> D is provided in the head unit 13.

FIG. 5D shows an example in which a memory 14D is built in the ink cartridge 14, and identification information indicating the type is recorded in the memory 14D. In this case, the identification information in the memory 14D is read to the ink information identification unit 13F through the terminals (electrodes) 14G and 13E. The terminal 13E can be connected to the discharge control device 11.
As described above, the information about the color and density of the ink filled in the ink cartridge 14 is notified to the head unit 13. Further, in the case of the present invention, the head unit 13 notifies the ejection control device 11 of information relating to the color and density of the ink filled in the ink cartridge 14 and its mounting position.
At this time, the head unit 13 can also convert these pieces of information into information representing the type of the head unit as in the third aspect. For example, this can be realized by providing a conversion table inside the head unit 13.

(E) Other Invention The above-described discharge control device can also be realized as a discharge control method and program as one aspect thereof. The program is executed on a computer or an information processing apparatus equipped with the computer.
The information processing device may be any electronic device that is electrically connected to the head unit and can function as an ink ejection device as a whole. For example, a portable information terminal, a mobile phone, or a game machine may be used.
In addition to the so-called printer device, the ink discharge device equipped with the discharge control device can be applied to a multi-function machine including a printer device and a scanner device.

  According to one aspect of the invention, restrictions on the type of ink and the mounting position of the ink can be eliminated. Further, according to one aspect of the invention, it is possible to select an optimum print mode according to the mounting state of the ink cartridge.

  Hereinafter, an embodiment of an ink ejection apparatus will be described by taking an ink jet printer that ejects ink droplets as an example. It should be noted that techniques not specifically shown or described in the present specification apply techniques known in the technical field.

(A) Ink Cartridge / Head Unit Here, a case where a separation type head unit and an ink cartridge are used will be described. That is, the ink cartridge is independent of the head unit. An ink cartridge having an independent container is used. One ink cartridge is filled with one type of ink.
Each ink cartridge can be individually installed or removed by the user. All of these ink cartridges have the same shape. Therefore, the ink cartridge can be installed in any slot of the head unit.
For example, a plurality of types of black ink having different densities can be attached. Of course, it is also possible to attach black ink having the same density. Color ink can also be attached.
Each slot may be used with a different color ink. Therefore, it is necessary to reduce the influence of color turbidity and nozzle clogging. In the case of this example, the ink remaining in the nozzle is forcibly discharged when the ink cartridge is mounted or removed. The ink is discharged by wiping, sucking, blowing, or the like.

FIG. 6 shows the lower surface (nozzle surface) of the head unit 20 used in this example. FIG. 6 shows an example in which a line head 20 </ b> A is used as the head unit 20. That is, a case where a fixed head is used will be described.
Four rows of nozzle groups 21A to 21D are arranged on the head surface at right angles to the moving direction of the recording medium. In each nozzle group, nozzles 22 are arranged at a specified pitch. Here, the nozzles 22 are arranged over the same length as the printing width.
Each nozzle group is arranged at a specified pitch in the moving direction of the recording medium. Each nozzle group corresponds to each ink cartridge described above. For example, the first nozzle group corresponds to the ink slot 1. Similarly, the second, third, and fourth nozzle groups correspond to the ink slots 2, 3, and 4, respectively.

Each nozzle 22 can eject a maximum of p ink droplets 23 (p is a natural number) to one pixel. The larger the natural number p, the higher the resolution. Note that one pixel can be formed by ink droplets ejected from a plurality of nozzles.
For example, one pixel can be formed by p droplets ejected from four nozzle groups. Further, for example, one pixel can be formed by p droplets ejected from a plurality of nozzles of one nozzle group. In this case, a deflection discharge technique that electrically deflects the discharge direction of the ink droplets is used.
FIG. 7 shows the top surface of the head unit 20. On the upper surface, four ink slots 24A to 24D for mounting the ink cartridge 30 shown in FIG. 8 are provided. The ink slot 24A corresponds to the nozzle group 21A. The ink slots 24B2 to 24D correspond to the nozzle groups 21B to 21D.
On the bottom surfaces of the ink slots 24A to 24D, ink supply openings are formed. Each opening is connected to a corresponding nozzle group by an ink flow path. The opening is formed near the center of the bottom surface. The ink supply port 31 of the ink cartridge 30 is inserted into this opening.

The ink cartridge 30 is provided with an ink identification pin 32. The ink identification pin 32 is disposed on the bottom surface of the ink cartridge 30. The ink identification pin 32 includes a plurality of protrusions. The ink identification pin 32 indicates the type of ink by a combination of the number and position of protrusions.
A detection device that detects the ink identification pin 32 is disposed in the head unit 20. The detection device is provided on the bottom surface of each ink slot 24A to 24D. The detection device is composed of a sensor or a switch. When the ink cartridge 30 is mounted, the position of the protrusion is detected by the detection device.
The detection device outputs information on the detected position of the protrusion and the detected ink slot to the printer body. This information is given to an ink system detection / control unit described later.
It can be seen from the position of the protrusion whether or not the ink cartridge is mounted. In addition, when it is mounted, it can be seen which type of ink is mounted in which ink slot.

(B) Dark / Monochrome Print Mode First, a monochrome print mode using dark / light single-color ink will be described. That is, a combination printing mode of black ink and gray ink will be described.
(B-1) Ink Mounting Example FIG. 9 shows an ink cartridge mounting example. FIG. 9 shows the relationship between the ink slots 24 </ b> A to 24 </ b> D and the ink filled in the ink cartridge 30.
In the drawing, “empty” indicates that the ink cartridge 30 is not mounted or that the ink in the ink cartridge has been used up.

(A) Example 1
In this mounting example, two gray inks having the same density and two black inks having the same density are mounted. This mounting example is a case where inks having the same density are adjacent to each other. In this example, it is possible to select a print mode in which ink droplets are ejected from two identical color inks to the same pixel position.
In this case, even if there is a partial ejection failure in one of the nozzles, one pixel density is averaged with ink droplets from the two nozzles. As a result, the occurrence of white stripes and density unevenness can be effectively suppressed.

(B) Example 2
This mounting example is a modification of Example 1. That is, two gray inks having the same density and two black inks having the same density are mounted. However, gray ink and black ink are mounted alternately.
In this case as well, high quality images can be printed by forming one pixel with ink droplets of the same density.

(C) Example 3
In this mounting example, gray ink and black ink are mounted one by one, and the remaining two ink slots are left empty. This can occur when the ink cartridge is insufficient. In this case, a print mode in which use of an ink slot in which no ink cartridge is mounted is suspended is selected.
In this print mode, emergency printing can be executed even if there is an empty slot. Of course, as long as the ejection of ink droplets from each nozzle is normal, high gradation expression is possible. In this case, the position of the empty slot can be freely changed.

Therefore, even if some of the ink heads have ejection failure and correction by signal processing is difficult, the quality may be recovered by mounting the ink cartridge in another ink slot.
This print mode can also be applied when ink is reduced in Example 1 or Example 2. For example, this is a case where one of the two inks is used up first in each of the dark and light inks. For example, this is the case where there is only one ink spare for each density.
In these cases, ink cartridges are installed in all ink slots. However, this is the same as Example 3 in that the ink cartridge has no ink and cannot be used for printing an image. This is the same as the print mode described above in that it requires signal processing without using an empty ink cartridge.

(D) Example 4
In this mounting example, two gray inks having the same density and one gray ink and black ink having a higher density are used. That is, in this example, three types of inks having different densities are used.
In this mounting example, gray can be drawn with ink droplets from two nozzles. Therefore, white streaks and density unevenness can be prevented.
Moreover, since two types of gray inks are used, gray can be expressed lighter than in Examples 1 to 3. For this reason, the graininess of the printed image can be further reduced and a smooth image can be formed.

(E) Example 5
In this mounting example, three types of gray ink and black ink having different densities are used one by one. That is, four types of ink droplets having different densities are ejected from the four nozzle groups. In the print mode corresponding to this mounting example, it is possible to realize a print image with improved graininess as compared to Example 4.
(F) Example 6
This mounting example is an example in which black ink is mounted on all four nozzle groups. In the printing mode corresponding to this mounting example, ink droplets from four nozzles can be used uniformly for one pixel. As a result, the occurrence of white stripes and density unevenness can be further improved. Also, since four inks are used simultaneously, the cartridge replacement time can be extended.

(G) Other As described above, the image quality can be freely changed according to preference by selecting the ink density, the number of the ink cartridges, and the mounting position. Also, it can be used as an emergency measure for ink ejection failure.
The above technique can also be applied when the ink cartridge is stored in the head unit in advance. Of course, as head unit identification information, information specifying the ink color, ink concentration, number of ink cartridges, and mounting position is stored.

(B-2) Configuration Example of Inkjet Printer FIG. 10 shows a main part of the ink jet printer main body 40 and a signal processing part of the head unit 20. The ink jet printer main body 40 has the following six main signal processing units.
That is, an ink system detection / control unit 41, a luminance / density conversion unit 42, a gamma conversion unit 43, a gamma conversion table storage unit 44, a gradation conversion unit 45, and a nozzle drive signal division unit 46 are included.
The head unit 20 includes a nozzle drive unit 25 that inputs a drive signal from the inkjet printer main body 40 and a print head 26 (21A to 21D) that includes a nozzle group that actually ejects ink droplets. Here, the nozzle driving unit 25 executes a driving method according to the driving method of the print head 26 to be driven.

For example, the drive system includes a valve system, a piezo system, a bubble system, and the like. The valve type is a system that ejects pressurized ink droplets by opening and closing a nozzle valve. The piezo method is a method in which ink droplets are ejected by vibration of a piezo element. The bubble method is a method in which ink droplets are ejected by expansion of bubbles generated by heating of a heater.
In some cases, the ejection direction of ink droplets can be electrically changed. In the case of a print head that supports the deflection ejection mode, the nozzle drive unit 25 also performs an ejection direction switching operation.

(A) Ink System Detection / Control Unit The ink system detection / control unit 41 is a key device that realizes optimal control according to the ink system. The ink system detection / control unit 41 receives two types or one of identification signals from the head unit 20.
One of the identification signals is the ink cartridge identification signal S1. Another one of the identification signals is the head unit identification signal S2.
The ink system detection / control unit 41 detects the ink system based on these identification signals. That is, it is detected which type of ink cartridge is loaded in each of the ink slots 24A to 24D.

Specifically, the ink color, density, and mounting position are detected. The ink system detection / control unit 41 selects the print mode based on these pieces of information. An example of the print mode corresponding to the mounting example is as described above. However, other print modes can be selected. In addition, the print mode can be changed by an instruction from an external computer.
The ink system detection / control unit 41 controls the entire system including various image processing units according to the selected print mode. The control here is performed by, for example, instructing the printing mode to each unit. The control here is performed by instructing specific control contents according to the print mode, for example.

(B) Luminance / Density Conversion Unit The luminance / density conversion unit 42 converts the luminance signal into a density signal. The converted density signal is output to the gamma conversion unit 43. The luminance signal is an image signal VIN in the bitmap format. A known technique is used for the luminance / density conversion unit 42.

(C) Gamma conversion unit (Gunman conversion table storage unit)
The gamma converter 43 converts the density signal of the original image into a density signal corresponding to the density reproduction characteristic. The gamma characteristic curve is used here.
Gamma refers to a saturation characteristic curve for density reproduction that varies depending on the ink absorption rate of the recording medium, the area filling rate of ink to the recording medium, and the like. An example of the gamma characteristic curve is shown in FIGS. FIG. 11 is an example of ink density characteristics. FIG. 12 is an example of normal gradation reproduction using ink.
In FIG. 11, the horizontal axis represents the number of ink droplets, and the vertical axis represents the density. As shown in FIG. 11, the reproduction density increases as the number of ink droplets increases. However, the amount of change gradually decreases. In FIG. 12, the horizontal axis is the input image, and the vertical axis is the quantized output. As shown in FIG. 12, the quantization value thresholds are not equally spaced.

Thus, the use of appropriate gamma characteristics is very important in achieving high print quality. Parameters that affect the gamma characteristics include ink density, ink absorption rate of the recording medium, ink dot diameter, dot density per unit area, and the like.
In general, the gamma characteristic curve is obtained by actually printing a specific pattern on a recording medium and actually measuring the printing result. As the specific pattern, a gradation pattern in which input changes stepwise with a certain level difference is used. When gamma conversion is not used, generally an image having a very dark middle portion of gradation is formed.
For this reason, an inverse characteristic curve corresponding to the printing environment is used for gamma conversion. The inverse characteristic curve is prepared in accordance with, for example, the difference in recording medium, print quality, and ink type. In general, these inverse characteristic curves are stored in a memory, and read and used at the time of printing.

The ink jet printer main body 40 stores these inverse characteristic curves in the gamma conversion table storage unit 44. FIG. 13 illustrates an internal configuration example of the gamma conversion table storage unit 44. The gamma conversion table storage unit 44 includes a gamma curve storage unit 44A and a curve / table data conversion unit 44B.
In the gamma curve storage unit 44A, n (n is a natural number) gamma curves are recorded. A single gamma curve is associated with a plurality of feature point data giving the shape of the curve. The reason for storing only the feature point data is that the amount of data is small.
For example, the feature point data is given as a plurality of point coordinates on an orthogonal two-dimensional plane. For example, four coordinate points are stored for each gamma curve. It is the ink system detection / control unit 41 that selects these gamma curves.

The ink system detection / control unit 41 outputs a curve selection instruction signal S3 corresponding to the printing conditions. The gamma curve storage unit 44A reads a gamma curve corresponding to the curve selection instruction signal S3 and provides it to the gamma / table data conversion unit 44B.
The gamma / table data conversion unit 44B converts the coordinate points into a continuous set of points (curve) using a curve method such as spline or Lagrange. The point data obtained by the conversion is written in the gamma conversion unit 43.
At this time, the point data is written in the conversion tables 43A to 43D to which each gamma curve is applied. These conversion tables 43A to 43D correspond to the ink slots 24A to 24D, respectively.

FIG. 14 shows a system configuration example realized by selecting a gamma curve. In the case of FIG. 14, the ink jet printer main body 40 has two signal processing units. There are two types, a gray ink system and a black ink system.
FIG. 14 shows an example in which the ink cartridge 30 is mounted as shown in Example 1 of FIG. That is, in this example, gray ink is loaded into the ink slots 1 and 2, and black ink is loaded into the ink slots 3 and 4.
In this case, the gamma curve for gray is stored in the gamma conversion tables 43A and 43B, and the gamma curve for black is stored in the gamma change tables 43C and 43D. As a result, the density signal for monochrome printing (gray scale) is branched and processed into independent systems for dark ink and light ink from the time of gamma conversion.
The density signals level-converted by the gamma converters 43a and 43b are subjected to gradation conversion by the gradation converters 45a and 45b, respectively. The tone-converted signal is converted into a signal suitable for driving the nozzles by the nozzle drive signal dividing units 46a and 46b.

(D) Gradation Conversion Unit The gradation conversion unit 45 executes processing for reducing the number of gradations of the density signal after gamma conversion. Here, the gradation conversion unit 45 converts the intermediate gradation signal having n values (n is a natural number) into a quantized signal having m values (m is a natural number, n> m).
First, the gradation converting unit 45 converts the image signal into a reduced number of gradations while maintaining the reproducibility of the intermediate gradation of the original image as much as possible. In general, n is 8 bits (256 values). On the other hand, m is a density that can be expressed by one nozzle for one pixel. For example, when one nozzle can eject a maximum of p ink droplets to form one pixel, m is p + 1 or less.
However, the output value after gradation conversion narrowed down from n to m is merely m values selected from 0 to 255. Therefore, it is not suitable as a nozzle drive signal. For this reason, processing for converting these output values into the number of ink droplets forming one pixel is provided.

FIG. 15 shows an internal configuration example of the gradation converting unit 45 that realizes these processes. The gradation conversion unit 45 includes conversion processing units 45A to 45D corresponding to each channel, and a gradation conversion control unit 45E that controls the conversion processing units 45A to 45D.
For example, the conversion processing unit 45A corresponding to channel 1 includes three functional units. The gradation conversion unit 45A1, the threshold value table 45A2, and the quantization unit 45A3. The other conversion processing units 45B to 45D have the same configuration.
Among these, the gradation converting unit 45A1 executes processing for reducing the density signal from n to m value. Further, the quantizing unit 45A3 executes a process of converting the m-value density signal into p quantized values. The threshold table 45A2 stores threshold values used for these conversion processes.

The gradation conversion control unit 45E sets an appropriate threshold in the threshold table 45A2. The gradation conversion control unit 45E inputs an ink mode signal S4 necessary for setting the threshold value from the ink system detection / control unit 41.
The gradation conversion control unit 45E decodes the ink mode signal S4 and obtains the number of steps necessary for gradation conversion of the density signal. That is, the m value corresponding to each channel is obtained. In addition, the gradation conversion control unit 45E determines a threshold value corresponding to the m value and creates a threshold value table. The created threshold value table is written in the corresponding conversion processing units 45A to 45D.
In addition, the gradation conversion control unit 45E decodes the ink mode signal S4 and determines a correspondence relationship for assigning the determined threshold value to an appropriate quantized output value. The determined correspondence is written in the corresponding conversion processing units 45A to 45D.

FIG. 16 shows a specific example of gradation conversion. First, in the gradation conversion unit 45A1, the multi-value image input is converted into a 5-value gradation image. The conversion threshold values here are “63”, “127”, “191”, and “255”. These values are written in the threshold value table 45A1.
As a result, the density signal of the gradation conversion unit 45 is converted into five values of “0”, “63” “127” “191” “255” according to the magnitude relationship with the threshold value. Next, the quantization unit 45A3 converts these numerical values into five quantized values “0” to “4”. Such processing is executed by the conversion processing units 45A to 45D corresponding to each channel.

(E) Nozzle drive signal dividing unit The nozzle drive signal dividing unit 46 executes a process of distributing the quantized nozzle drive signal to an appropriate nozzle group. FIG. 17 illustrates an internal configuration example of the nozzle drive signal dividing unit 46. The nozzle drive signal dividing unit 46 includes division processing units 46A to 46D corresponding to the respective channels, and an output control unit 46E that controls the division processing units 46A to 46D.
For example, the division processing unit 46A corresponding to the channel 1 includes two functional units. They are a multiplexer 46A1 and an arithmetic unit 46A2. The other division processing units 46B to 46D have the same configuration.
Among these, the multiplexer 46A1 performs quantization signal selection processing. That is, one of the quantized signals for four channels inputted in parallel is selected for the multiplexer 46A1.

As shown in FIG. 14, when a quantized signal of a certain channel is given to two nozzle groups, further division of the quantized signal is necessary. The division unit 46A2 performs this division processing.
For example, when the number of nozzle drive signals is q, the calculation unit 46A2 operates so as to distribute half (q / 2) to each nozzle group. If the quantized value q is an odd number and the remainder is “1”, the one is distributed according to, for example, a staggered pattern on the dot array.
At this time, the calculation unit 46A2 refers to the pixel position information S5 and confirms the position to be distributed. The pixel position information S5 is given from the ink system detection / control unit 41.
In addition, there are various variations for ejecting the same color ink with a plurality of nozzles. An example is shown in FIG. FIG. 18A shows an example in which one pixel is composed of ink droplets from four nozzles. This example can be performed in the case of Example 6 in FIG.

FIG. 18B is an example of switching nozzles that discharge for each pixel. This can be selected when the same color ink can be ejected from two nozzles. For example, this is the case of Example 1 and Example 2 in FIG.
In this case, since one pixel can be constituted by ink droplets from a plurality of nozzles having different nozzle groups, even if there is an ink ejection failure in one nozzle, the influence can be averaged. In addition, the discharge failure includes discharge bend, non-discharge, and other differences in density due to variations in discharge amount.
The output control unit 46E inputs an ink mode signal S5 defining these processing operations from the ink system detection / control unit 41. The output control unit 46E decodes the ink mode signal S6 and determines which channel of the quantization signal is to be given to each nozzle. The switch switching signal is given to the corresponding division processing units 46A to 46D.
Similarly, the output control unit 46E decodes the ink mode signal S6, and gives the division processing mode of the quantized signal to the corresponding division processing units 46A to 46D.

(B-3) Print Operation Example A typical processing operation example of the ink ejection apparatus will be described below.
(A) At the time of mounting or replacing the head unit When the head unit 20 is mounted, the arrangement of the unit identification pins is detected through a sensor provided in the ink jet printer main body 40. The detection result is given to the ink system detection / control unit 41.
The ink system detection / control unit 41 detects which type of ink is installed or not installed in each of the ink slots 24A to 24D. Thereafter, the ink system detection / control unit 41 determines a gamma curve, a gradation threshold value, a quantization value, and the like optimal for the ink system, and controls each unit.

(B) At the time of changing print quality / recording medium The print quality and the recording medium may be changed during use. For example, it is performed by designation on the computer side that is a transmission source of image data. Such information is also given to the ink system detection / control unit 41. At this time, the ink system detection / control unit 41 determines a print mode that can be selected for a usable ink system and satisfies the designated print quality and controls each unit.

(C) When replacing the ink cartridge The ink cartridge may be replaced during use. For example, one of four ink cartridges may be exchanged for another color or a different density. In such a case, a completely different printing mode is adopted because the presupposed ink system changes.
Even when the same ink cartridge is used, the mounting position may be changed. For example, inferior ink ejection is more noticeable in darker colors. Therefore, the mounting position of the ink cartridge may be changed. Further, when the removed ink cartridge is mounted again, it may be put in a position different from the previous time.
The result is the same whether intentional or not. However, the ink jet printer main body 40 can detect any ink at any position and can apply an optimum print mode. Accordingly, it is possible to obtain a printing result optimum for a usable ink system.

(D) When ink runs out during use The ink cartridge may run out during use. As long as the ink is used, as long as it is installed, if the signal processing is performed assuming that the ink is present, it is natural that the print quality deteriorates.
However, the ink system detection / control unit 41 determines that the ink cartridge is not installed when the ink is consumed and is not used. Then, as long as interpolation with ink from other ink cartridges is possible (when a plurality of inks having the same color or different densities are mounted), printing using other inks is instructed. These instructions are given to the nozzle drive signal divider 46.

(B-4) Effect of Embodiment As described above, if the ink jet printer main body 40 according to the present embodiment is used, the type of ink to be used and the mounting position can be provided with flexibility. As a result, optimal printing can be realized for printing applications and recording media.
In addition, as described above, even when there is no ink spare, the best printing can be realized using only the ink on hand.

(C) Automatic switching printing mode between color printing and monochrome printing Here, a printing mode for automatically switching between the color printing mode and the monochrome printing mode based on the combination information of the ink cartridges or the identification information of the head unit will be described. To do.
(C-1) Ink Mounting Example FIG. 19 shows an ink cartridge mounting example. FIG. 19 shows the relationship between the ink slots 24A to 24D (FIG. 7) and the type of ink filled in the ink cartridge 30 (FIG. 8).

(A) Color printing mode In this mounting example, inks corresponding to four colors of yellow, magenta, cyan, and black are mounted. Note that it is possible to mount inks of six or more colors including light magenta, light cyan, and the like.
In this example, an ink cartridge filled with yellow ink is installed in the ink slot 24A. An ink cartridge filled with magenta ink is installed in the ink slot 24B. Similarly, an ink cartridge filled with cyan ink is installed in the ink slot 24C, and an ink cartridge filled with black ink is installed in the ink slot 24D.
The corresponding relationship between the ink slot and the ink color is notified to the ink jet printer main body through the head unit.

(B) Dark / light monochrome printing mode In this mounting example, two gray inks and two black inks are mounted.
In the example of FIG. 19, ink cartridges filled with gray ink are mounted in the ink slots 24A and 24B. Ink slots 24C and 24D are mounted with ink cartridges filled with black ink.
In this case, even if there is a partial ejection failure in one of the nozzles, one pixel density is averaged with ink droplets from the two nozzles. As a result, the occurrence of white stripes and density unevenness can be effectively suppressed.

Note that the combination of gray ink and black ink illustrated in FIG. 9 can also be applied to this example.
The correspondence between the ink slot and the ink color is notified to the ink jet printer main body through the head unit.

(C-2) Configuration Example of Inkjet Printer Hereinafter, a configuration example of an inkjet printer that can realize a color printing mode and a light / dark monochrome printing mode using a common signal processing circuit will be described.
Note that a PNM (Pulse Number Modulation) method in which one pixel is formed by a plurality of ink droplets is applied to the print head drive method.

(A) Functional Configuration First, the processing functions required in each printing mode are conceptually shown.
FIG. 20 shows a basic configuration of the image processing unit corresponding to the color printing mode. The image processing unit mainly includes an image input buffer 51, a color conversion unit 52, gamma conversion units 53A to 53D, halftoning units 54A to 54D, and a nozzle drive unit 55.
In the case of this printing mode, the gamma conversion unit 53 and the halftoning unit 54 are required for the number of ink colors.
Incidentally, the color conversion unit 52 is a signal processing unit that converts color data (RGB 24 bits) of the original image into color data (YMCK 32 bits) of the print processing system. In general, a three-dimensional lookup table is used.

FIG. 21 shows a basic configuration of the image processing unit corresponding to the light / dark monochrome printing mode. This image processing unit mainly includes an image input buffer 61, a luminance / density conversion unit 62, gamma conversion units 63A and 63B, halftoning units 64A and 64B, nozzle drive signal distribution units 65A and 65B, and a nozzle drive unit 65. To do.
In the case of this print mode, the gamma conversion unit 63 and the halftoning unit may correspond to two systems of gray and black. Therefore, in this printing mode, the luminance / density conversion unit 62 that converts the luminance signal into the density signal is used.
Further, in this print mode, a nozzle drive signal distribution unit 65 that distributes pixel data to two rows of nozzle groups corresponding to the same color ink is used to suppress white stripes and density unevenness.

(B) Embodiment FIG. 22 shows an embodiment of the ink jet printer main body 70 corresponding to these two printing modes.
The ink jet printer main body 70 includes an image input buffer 71, a color conversion and luminance / density conversion unit 72, gamma correction units 73A to 73D, error diffusion units 74A to 74D, nozzle drive signal distribution units 75A and 75B, and nozzle drive units 76A to 76D. The table data storage units 77 and 78, the threshold / quantized representative value storage unit 79, and the ink system detection / control unit 80 are the main components.
For these signal processing units, those equipped with functions corresponding to two printing modes are used.

For example, a color conversion / brightness / density conversion unit 72 that can change the processing contents according to the print mode is used. The color conversion / brightness / density conversion unit 72 has a function of selectively stopping the operations of the gamma correction units 73A to 73D and the error diffusion units 74A to 74D according to the print mode.
Further, for example, nozzle drive signal distributors 75A and 75B that can switch the distribution processing method according to the print mode are used.
Hereinafter, the circuit configuration and processing contents of each processing unit will be described individually.

(1) Color Conversion and Luminance / Density Conversion Unit FIG. 23 shows a circuit configuration of the color conversion and luminance / density conversion unit 72. The color conversion / brightness / density conversion unit 72 includes a lookup table 72A for color conversion processing and an interpolation calculation unit 72B.
The change of the processing content according to the print mode is executed by the interpolation calculation unit 72B based on the mode signal Smode. For example, in the color printing mode, the interpolation calculation unit 72B sets the printing color signal (YMCK) input from the lookup table 72A as a processing target. In addition, for example, in the dark / light monochrome printing mode, the interpolation calculation unit 72B sets monochrome luminance data as a processing target.

FIG. 24 shows a color conversion unit 81 equivalent to the conversion process of the lookup table 72A. The color conversion unit 81 mainly includes three signal processing units (a LOG conversion unit 81A, a masking unit 81B, and a UCR / BG unit 81C).
The LOG conversion unit 81A is a processing unit that matches an input signal with human perceived luminance. The LOG converter 81A functions as a pre-process for the masking process.
The masking unit 81B is a processing unit for matching the color reproducibility during printing with the color of the original image. This is because the color reproducibility during printing varies slightly depending on the background color of the print medium, the nature of the color ink, and the like. Note that the conversion process is executed in the manner of twisting the color space.
The UCR / BG (Under Color Removal / Black Generation) unit 81C is a processing unit that replaces the achromatic color expressed by the three primary colors with black ink. As a result, the three primary colors are converted into Y, M, C, and K 8-bit density signals.

These three signal processes are all realized as input / output data conversion processes. The lookup table 72A uses a combination of these three conversion tables. As a result, RGB input is directly converted to CMYK output.
By the way, the input RGB data is 8 bits each. Accordingly, in order to store output values corresponding to all input values in the lookup table 72A, a memory space of 256 × 256 × 256 × 4 bytes is required.

Therefore, the lookup table 72A employs a method in which input data is thinned out at equal intervals and only output values corresponding to the remaining input data are stored. The output value corresponding to the thinned input value is obtained by interpolation processing based on the input / output relationship in the vicinity.
Therefore, in FIG. 23, only the upper 4 bits of the RGB data are input to the lookup table 72A, and the output value corresponding to the lower 4 bits is obtained by the interpolation calculation unit 72B.
Note that input / output-related data corresponding to the printing conditions (for example, the type of printing medium and the type of ink) is stored in the table data storage unit 77 and written to the lookup table 72A as necessary.

FIG. 25 shows a density / luminance conversion unit 82 equivalent to the interpolation calculation unit 72B in the light / dark monochrome printing mode. The density / luminance conversion unit 82 inputs the monochrome luminance data to the inverter 82A, and outputs the inverted value to one channel corresponding to the gray ink and the black ink. In this example, the data is output to channel 1 and channel 3. Since channel 2 and channel 4 are not used, 0 (zero) is output.
However, in principle, the function of the density / luminance conversion unit 82 can also be realized by the lookup table 72A. However, in this embodiment, since the processing time is short, it is realized as one function of the interpolation calculation unit 72B.

(2) Gamma Conversion Unit The density obtained when a plurality of ink droplets are overprinted in a limited area tends to saturate at a certain value. This tendency tends to be more noticeable as the ink density increases.
In addition, the shape of the dots formed when the ink droplets land on the paper that is the printing medium is approximately circular. For this reason, assuming that dots are arranged side by side at equal intervals in the vertical and horizontal directions, if the dot diameter is small enough not to touch the neighbors, the background is confirmed at the four corners. They overlap each other.

Due to the above factors, it is known that the resulting density with respect to the ink ejection amount does not have a simple proportional relationship with the number of ejections. That is, the density changes along a unique curve depending on paper or other recording medium, ink permeability to the recording medium, ink density, and the like.
This curve is called printing gamma. Therefore, if the input data is printed as it is, the gradation of the image is reproduced with distortion. For this reason, it is necessary to perform processing for converting the input density value with a curve having a characteristic opposite to the previous curve so that the output result with respect to the input density value becomes linear. This process is gamma correction.

  FIG. 26 shows an example of a gamma correction curve used in the color printing mode. The gamma correction curve is not for adjusting the color of the printed image, but for correcting the density due to ink. Therefore, the color conversion and luminance / density conversion unit 72 is arranged independently after the stage. Note that the color-specific gamma correction curves illustrated in FIG. 26 need to be changed according to the printing conditions. In this embodiment, the gamma correction curve data corresponding to each printing condition is stored in the table data storage unit 78, and the data of the gamma correction units 73A to 73D are changed as necessary.

FIG. 27 shows an example of a gamma correction curve used in the dark / light monochrome printing mode. In this case, there are two types of gamma correction curves. This is because the processing after luminance / density conversion is divided into two parts, a high density ink system and a low density ink system, from the gamma correction unit.
By the way, the conversion characteristics for low-density ink indicated by the broken line have a gentle curve so as to handle printing up to the middle of the input value, and the output for the input is reduced so that printing after the middle value is inherited by high-density ink. Will come to let you. That is, the output value for low density ink is determined not to exceed 127 for any input value.

In this way, the low density ink is gradually decreased from around the middle density value to suppress a rapid variation in the amount of scattered dots at the transition between the high density ink and the low density ink. As a result, the generation of pseudo contours in the vicinity of the intermediate density is suppressed, and unnaturalness at the transition of dark and light ink can be eliminated.
On the other hand, the conversion curve of the high density ink maintains the output zero until the intermediate value of the input in order to suppress the dot scattering in the image highlight portion that adversely affects the graininess. However, after the intermediate value, a curve in which high density dots are increased instead of low density dots is adopted.

(3) Error diffusion unit In the error diffusion units 74A to 74D, processing for converting the multi-value multi-gradation density data after gamma correction into n values (nozzle drive data) suitable for driving by the PNM method is executed. . n is a value of about 2 to 8.
Here, the maximum number of ink droplets that form one dot is n−1. In the color printing mode, the n values corresponding to the colors Y, M, C, and K do not have to be the same value. The optimum n value corresponding to each color is determined based on the ink density, the maximum number of allowable droplets for the print medium, and the like.
However, the conditions regarding the n value are the same in the dark / light monochrome printing mode. Rather, the possibility of using different n in the high density ink system and the low density ink system is higher than in the color printing mode.

Therefore, the n value also needs to be changed according to the print medium, print resolution, and the like. Note that the n value and the threshold value need to be handled as one set. For this reason, the threshold / quantization representative value storage unit 79 stores n-value and threshold combination data corresponding to the printing conditions.
The ink jet printer main body 70 calls necessary data at the start of printing and loads the data into the error diffusion units 74A to 74D.
FIG. 28 shows an internal configuration example of the error diffusion units 74A to 74D. Each error diffusion unit includes an error diffusion processing unit 91 and a quantization unit 92.
Here, the adder 91A functions as an arithmetic unit that adds the correction value to the density data (multi-value / multi-tone input value). This addition processing corresponds to correction processing for diffusing previously generated quantization errors to surrounding pixels. The correction value is given from the error buffer 91B.

The density data in which the quantization error is corrected is compared with five kinds of threshold values in the gradation conversion unit 91C. FIG. 29 shows a conceptual diagram thereof. In the case of FIG. 29, there are five threshold values: “0”, “63”, “127”, “191”, “255”. The density data is converted into one of five threshold values by the gradation conversion unit 91C. That is, the gradation conversion unit 91C performs rounding processing on the details of the density data.
A part of the density data after the rounding process is converted into numerical values “0” to “4” in the quantization unit 92.
A part of the density data after the rounding process is subtracted from the value before the rounding process in the subtractor 91D. This subtraction process corresponds to the quantization error calculation process.
The calculated quantization error is multiplied by the error diffusion coefficient in the error diffusion matrix 91E, and the multiplication result is stored in the error buffer 91B as a correction value.

(4) Nozzle Drive Signal Distribution Unit The line head described with reference to FIG. 6 moves only the print medium with the line head fixed, and completes all printing processes. For this reason, the occurrence of vertical streaks and density unevenness due to nozzle malfunction or non-ejection tends to be a problem.
Since the degree of freedom of the nozzle position with respect to the print medium is limited, it is difficult to correct even if a malfunctioning nozzle or a non-ejection nozzle can be identified. Making it inconspicuous is a major issue in improving image quality.

Therefore, a method is adopted in which the nozzle drive signal distribution units 75A and 75B are used to control the distribution destination of the nozzle drive signal to suppress the occurrence of streaks and density unevenness.
For example, if non-ejection is known in advance, the nozzle drive signal for the non-ejection nozzle is changed to another nozzle group capable of ejecting ink of the same density.
If one dot is formed by ink droplets ejected from two nozzles, even if ejection failure occurs in one nozzle, at least half of the ink droplets are output by another nozzle. Streaks can be made inconspicuous.

Accordingly, when one dot is formed by n ink droplets, the nozzle drive signal distribution units 75A and 75B operate so that the number of ink droplets forming one dot is evenly distributed to two nozzles as much as possible. To do.
However, there are cases where the n value is not divisible by 2. In this case, the remaining one assignment is determined according to a staggered pattern on the dot matrix forming the image. FIG. 30 shows an example of dot assignment. FIG. 30 shows four dot positions given by 2 rows and 2 columns by numbers “0” to “3”. In FIG. 30, when the number of ink droplets forming each pixel is an odd number at the dot positions “0” and “3”, the remaining ink droplets are assigned to the nozzle group 1. Further, when the number of ink droplets forming each pixel is an odd number at dot positions “1” and “2”, this indicates that the remaining ink droplets are allocated to the nozzle group 2.

FIGS. 31 to 33 are diagrams showing examples of ink droplet ejection when this allocation method is applied.
FIG. 31 shows an output example when the nozzle drive data is an even number (when PNM value = 6).
FIG. 32 shows an output example when the nozzle drive data is an odd number (when PNM value = 5) and the pixel position is “0” or “3” in FIG. 30.
FIG. 33 shows an output example when the nozzle drive data is an odd number (when PNM value = 5) and the pixel position is “1” or “2” in FIG. 30.

The nozzle drive signal distributors 75A and 75B execute the assignment function in the dark / monochrome printing mode. The nozzle drive signal distributors 75A and 75B operate so as to pass the input nozzle drive data of the channel to the corresponding nozzle group in the color printing mode.
By the way, the above distribution function can also be realized in the form of software. FIG. 34 shows an example of a program installed in the nozzle drive signal distributor 75A that shares the nozzle groups 1 and 2.

In the figure, the operator% that acts on the horizontal (x-direction) scan pointer or the vertical (y-direction) scan pointer determines the remainder of the division operation. For example, if “5% 2”, “1” is a desired value. In this example of dividing by 2, the value given by the operator% is either “0” or “1”.
Therefore, “2 * (y−ptr% 2) + x−ptr% 2” is the same as obtaining the four pixel positions in FIG.

The operator / is for obtaining the quotient of the division operation. For example, if “5/2”, “2” is a desired value.
This operator is used to determine the number of ink droplets assigned to the nozzle groups 1 and 2 from the nozzle drive data (PNM value) for the nozzle group 1. For example, when the nozzle drive data is an odd number (when PNM value = 5), “2” which is the quotient of the division operation is assigned to the nozzle group 1 or 2 according to the pixel position. A value obtained by subtracting the quotient of the division operation from the nozzle drive data is assigned to the other nozzle group.

The distribution of nozzle drive data (PNM value) can also be switched on a pixel-by-pixel basis. In other words, the ink droplets forming one pixel are ejected by a single nozzle group, but it is also possible to switch the nozzle group that is shared pixel by pixel.
FIG. 35 shows a configuration example of the nozzle drive signal distribution unit 75A in the case where the sharing switching is a staggered pattern. In this case, the nozzle drive signal distributor 75A can be realized with only the three switches SW1 to SW3. Incidentally, the switching of the terminals of the switches SW1 and SW2 is exactly the same.

Here, in the color printing mode, the switches SW1 to SW3 are all fixedly connected to the color terminal side. As a result, nozzle drive data corresponding to yellow ink is given only to nozzle group 1, and nozzle drive data corresponding to magenta ink is given only to nozzle group 2.
In the dark / light monochrome printing mode, the switches SW1 and SW2 are sequentially switched according to the control signal. On the other hand, the switch SW3 is fixedly connected to the output side of the switch SW2. As a result, nozzle drive data corresponding to the gray ink is distributed to the nozzle group 1 or 2.
It is assumed that the control signal for controlling the distribution operation is generated according to the above-described staggered lattice, random, or the like. This control pattern is preferably read out by calculation or from a lookup table.

(C-3) Example of printing operation (a) At the time of mounting or replacement of the head unit When the head unit 20 is mounted, the arrangement of the unit identification pins is detected through a sensor provided in the ink jet printer main body 70. The detection result is given to the ink system detection / control unit 80.
For example, the ink system detection / control unit 80 detects what type of ink is installed in each of the ink slots 24A to 24D or not. That is, it is determined whether the color printing mode or the light / dark monochrome printing mode.
Thereafter, the ink system detection / control unit 80 determines a gamma curve, a gradation threshold value, a quantization value, and the like optimal for the ink system, and controls each unit.

(B) At the time of changing print quality / recording medium The print quality and the recording medium may be changed during use. For example, it is performed by designation on the computer side that is a transmission source of image data. Such information is also given to the ink system detection / control unit 80. At this time, the ink system detection / control unit 80 determines each of the print modes that can be selected for the usable ink system and satisfies the designated print quality and controls each unit.

(C) When replacing the ink cartridge The ink cartridge may be replaced during use. For example, one of four ink cartridges may be exchanged for another color or a different density. In such a case, a completely different printing mode is adopted because the presupposed ink system changes.
Even when the same ink cartridge is used, the mounting position may be changed. For example, inferior ink ejection is more noticeable in darker colors. Therefore, the mounting position of the ink cartridge may be changed. Further, when the removed ink cartridge is mounted again, it may be put in a position different from the previous time.
The result is the same whether intentional or not. However, the ink jet printer main body 70 can detect what kind of ink is attached at any position and can apply an optimum print mode. Accordingly, it is possible to obtain a printing result optimum for a usable ink system.

(D) When ink runs out during use The ink cartridge may run out during use. As long as the ink is used, as long as it is installed, if the signal processing is performed assuming that the ink is present, it is natural that the print quality deteriorates.
However, the ink system detection / control unit 80 determines that the ink cartridge is not mounted when the ink is consumed and is no longer used. Then, as long as interpolation with ink from other ink cartridges is possible (for example, in the case of dark and light monochrome printing mode), printing using other ink is instructed. These instructions are given to the nozzle drive signal dividers 75A and 75B.

(C-4) Effects of Embodiment As described above, if the ink jet printer main body 70 according to this embodiment is used, it can be used as a color printer or a monochrome printer only by replacing the ink cartridge or the head unit.
As a result, user convenience and effective utilization of ink and other resources can be realized.
Manufacturers and vendors can also improve productivity and serviceability by sharing hardware and software. Of course, various cost reduction effects can also be realized.

(D) Other Embodiments (a) In the above-described embodiment, the case where the ejection control device 40 (41 to 46) or 70 (71 to 80) is mounted on the inkjet printer has been described. The processing 70 may be realized as a function on the information processing apparatus side on which the computer is mounted.
(B) The printer in the above-described embodiment may be a printing-only machine or a multi-function machine equipped with other functions. In addition, the usage of the printer is not limited to the one intended for use in the office or home, but includes medical usage. For example, the present invention can be applied to printing of an appearance image of an affected area, an X-ray image, an echo image, and other medical images.
(C) In the above-described embodiments, the signal processing in the printing apparatus has been described in hardware. However, when the signal processing in the printing apparatus is defined by firmware or an execution program, each signal processing is realized by software. You may do it.
The execution program is preferably stored in a semiconductor memory, hard disk, optical storage medium, or other storage medium.
(D) Various modifications can be considered in the above-described embodiments within the scope of the gist of the invention. Various modifications and applications created based on the description of the present specification are also conceivable.

It is a figure which shows an example of a head unit exchange type ink discharge system. It is a figure which shows an example of an ink discharge system of an ink cartridge exchange type. It is a figure which shows the other example of an ink discharge system of an ink cartridge exchange type. It is a figure which shows an example of the mechanical structure for the ink system identification mounted in a head unit. It is a figure which shows an example of the mechanical structure for the ink system identification mounted in an ink cartridge and a head unit. It is a figure which shows the example of a lower surface structure of a head unit. It is a figure which shows the upper surface structural example of a head unit. It is a figure which shows the example of a side surface of an ink cartridge. FIG. 6 is a diagram illustrating an example of loading ink into an ink slot. It is a figure which shows the main structural examples of an inkjet printer main body. FIG. 6 is a diagram illustrating an example of ink density characteristics. It is a figure which shows the gradation reproduction characteristic of an ink. It is a figure which shows the structural example of a gamma conversion table memory | storage part. It is a figure which shows the system configuration example according to an ink system. It is a figure which shows the structural example of a gradation conversion part. It is a figure which shows the conceptual structure of gradation conversion. It is a figure which shows the structural example of a nozzle drive signal division part. It is a figure which shows the execution example of the printing which distributed the nozzle. FIG. 6 is a diagram illustrating an example of loading ink into an ink slot. It is a figure which shows the signal processing system required in color printing mode. It is a figure which shows the signal processing system required in the light / dark monochrome printing mode. It is a figure which shows the main structural examples of an inkjet printer main body. It is a figure which shows the structural example of a color conversion and a luminance / density conversion part. It is a figure which shows the equivalent circuit of a color conversion part. It is a figure which shows the equivalent circuit of a brightness | luminance and density | concentration conversion part. It is a figure which shows the example of the gamma correction curve for color printing. It is a figure which shows the example of the gamma correction curve for light / dark monochrome printing. It is a figure which shows the structural example of an error-diffusion part. It is a figure which shows the conceptual structure of gradation conversion. It is a figure which shows the distribution principle of the ink droplet by a nozzle drive signal division part. It is a figure which shows the example of distribution in case nozzle drive data is an even number. It is a figure which shows the example of distribution in case nozzle drive data is an odd number. It is a figure which shows the example of distribution in case nozzle drive data is an odd number. It is a figure which shows the example of a program for implement | achieving a nozzle drive signal division part by software. It is a figure which shows the other structural example of a nozzle drive signal division part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Discharge control apparatus 2,12 Ink discharge apparatus 3,13,20 Head unit 20A Line head 21A-21D Nozzle group 22 Nozzle 24A-24D Ink slot 30 Ink cartridge 31 Ink supply port 32 Ink identification pin 40, 70 Inkjet printer Main body 41, 80 Ink system detection / control unit 43, 73 Gamma conversion unit 44 Gamma conversion table storage unit 45, 74 Tone conversion unit 46, 75 Nozzle drive signal division unit

Claims (25)

An ejection control device for controlling a plurality of types of head units with different combinations of ink cartridges,
An identification unit for identifying the type of the mounted head unit;
And a mode selection unit that selects a print mode suitable for the identified head unit. An ejection control device for controlling a head unit capable of individually mounting a plurality of types of ink cartridges,
An identification unit for identifying a mounting state of the ink cartridge with respect to the head unit;
A discharge control device comprising: a mode selection unit that selects a print mode suitable for the identified mounting state. The discharge control device according to claim 1,
The discharge control apparatus, wherein the identification unit identifies the type of the mounted head unit based on an identification signal acquired from the head unit. The discharge control device according to claim 1,
The discharge controller according to claim 1, wherein the identification unit identifies a type of the mounted head unit based on a setting when the head unit is mounted. The discharge control device according to claim 2,
The discharge control device, wherein the identification unit identifies a mounting state of the ink cartridge with respect to the head unit based on an identification signal acquired from the head unit. The discharge control device according to claim 2,
The discharge controller according to claim 1, wherein the identification unit identifies a mounting state of the ink cartridge with respect to the head unit based on a setting when the head unit is mounted. In the discharge control device according to claim 1 or 2,
The mode selection unit corresponds to a printing mode in which a plurality of ink cartridges filled with ink of the same color and the same density are used. In the discharge control device according to claim 7,
The mode selection unit corresponds to a printing mode in which a plurality of ink cartridges filled with ink of the same color and the same density are selectively used. In the discharge control device according to claim 7,
The mode selection unit corresponds to a print mode in which a plurality of ink cartridges filled with ink of the same color and the same density are equally used. In the discharge control device according to claim 1 or 2,
The discharge controller according to claim 1, wherein the mode selection unit corresponds to a color printing mode corresponding to a plurality of color inks and a monochrome printing mode corresponding to a light and dark single color ink. In the discharge control device according to claim 1 or 2,
The mode selection unit selects a print mode to be used in accordance with a position where an ink cartridge is not mounted. A head having a mechanical structure that enables information relating to a combination of a plurality of ink cartridges held therein and a mounting position thereof to be identified through mechanical coupling with the mounting mechanism when mounted on the mounting mechanism. unit. A head unit comprising: a connection terminal that enables identification of information relating to a combination of a plurality of ink cartridges held in the mounting mechanism and its mounting position through electrical connection with the mounting mechanism when mounted on the mounting mechanism. . An ink cartridge having a mechanical structure that enables at least information relating to the color and density of filled ink to be identified through mechanical coupling when mounted on a head unit. An ink cartridge comprising: a connection terminal that enables at least information relating to the color and density of filled ink to be identified through electrical connection when the head unit is mounted. A head unit characterized by having a mechanical structure that enables at least information relating to the color and density of ink filled in the ink cartridge and its mounting position to be identified through mechanical coupling when the ink cartridge is mounted. A head unit comprising: a connection terminal that enables identification of at least information about the color and density of ink filled in the ink cartridge and its mounting position through electrical connection when the ink cartridge is mounted. An ink discharge apparatus comprising the discharge control apparatus according to claim 1. An ink discharge apparatus comprising the discharge control apparatus according to claim 2. A discharge control method executed by a discharge control apparatus that controls a plurality of types of head units with different combinations of ink cartridges,
Identifying the type of installed head unit;
And a step of selecting a print mode suitable for the identified head unit. A discharge control method executed by a discharge control device that controls a head unit capable of individually mounting a plurality of types of ink cartridges,
Identifying the mounting state of the ink cartridge;
And a step of selecting a print mode suitable for the identified mounting state. In a computer that functions as an ejection control device that controls a plurality of types of head units with different combinations of ink cartridges,
An identification function for identifying the type of the mounted head unit;
A mode selection function that selects a print mode suitable for the identified head unit. In a computer that functions as an ejection control device that controls a head unit that can be individually mounted with multiple types of ink cartridges,
An identification function for identifying the mounting state of the ink cartridge;
A program for executing a mode selection function for selecting a print mode suitable for the identified mounting state.   A recording medium on which the program according to claim 22 is recorded. A recording medium on which the program according to claim 23 is recorded.

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