JP2002240328A - Inkjet printer - Google Patents

Abstract

(57) [Problem] To perform high-quality printing without causing an increase in the size and complexity of the apparatus, and to perform highly effective cleaning of ink nozzles by using a cleaning liquid. SOLUTION: Adjacent color ink discharge nozzles 40
a and the transparent ink discharged from the transparent ink discharge nozzle 40b are landed at the same point on the recording medium to form a mixed ink, and it is possible to form dots of a color lighter than the provided color ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer, and more particularly, to an ink jet printer capable of forming a high-quality image and suitably cleaning an ink head.

[0002]

2. Description of the Related Art In an ink jet printer, C (cyan), M (magenta), Y (yellow),
It is well known that color printing is performed using four color inks of Bk (black).

In recent years, however, it has been demanded for an ink jet printer to have a high image quality comparable to a photograph. In such a case, in addition to the four color inks, a thin C (light cyan) and a thin C (light cyan) are used. In general, printing is performed with six colors of ink using M (light magenta) ink. In addition to the above six color inks,
It is also possible to perform printing with seven colors of ink using deep Y (dark yellow) ink, or to perform eight colors of printing using light yellow (light yellow) and light black (light black).

In a conventional ink jet printer, cleaning of a nozzle surface of an ink head is generally performed by wiping with a blade or capping to prevent drying of the head.
In these methods, dry matter adheres to the nozzle surface due to ink drying (causing problems such as bending of the ink flying direction).
Also, clogging of the nozzle holes (which makes it impossible to fly ink and causes white streaks) could not be sufficiently prevented.

For this reason, for example, Japanese Patent Application Laid-Open No. 4-39055
Japanese Patent Application Laid-Open No. H11-163873 discloses a method for eliminating clogging by providing a cleaning chamber surrounding the tip of an ink nozzle and supplying a cleaning liquid to the ink nozzle for cleaning in the cleaning chamber.

In the configuration of the above publication, the lid constituting the cleaning chamber is moved to close the opening of the ink nozzle in a liquid-tight state, and then a voltage signal is applied to the piezo element of the multi-ink nozzle to apply a voltage signal to each nozzle. The cleaning liquid is jetted from the cleaning liquid jet nozzle while jetting the ink particles from the tip, and the ink is washed by colliding with the tip of the multi-ink nozzle. The ejection of the cleaning liquid may be performed continuously for a fixed time or may be performed intermittently. At the same time, a negative pressure is introduced into the discharge passage provided in the cleaning chamber, and the cleaning liquid, ink, dirt, and the like collected at the bottom of the cleaning chamber are discharged to the outside through the discharge passage. Note that various suction pumps may be used for suctioning the liquid in the discharge passage.

[0007]

However, the above-described conventional configuration has the following problems.

In an ink-jet printer that performs high-quality printing using six or seven colors of ink, the number of inks used increases, so that many ink tanks are required to store these inks. For this reason, there arises a problem that the device becomes large and the device becomes complicated.

That is, in a serial type ink jet printer, it is necessary to scan with a large number of ink tanks placed on a head carriage, which complicates the construction and replacement of the ink tanks. For example, as shown in FIGS. 11A and 11B, in a conventional serial type inkjet printer, Bk (black), Y (yellow), M (magenta),
When performing six-color printing using inks of (cyan), LM (light magenta), and LC (light cyan), the ink tank 101 for the six colors is used in the ink carriage 101.
02 must be installed. In addition, FIG.
In (b), as further described by a broken line,
In eight-color printing in which LY (light yellow) and LBk (light black) are added, it is necessary to mount the ink tanks 102 for eight colors.

Also, in an ink tank fixed type printer, as shown in FIG. 12, as the type of ink used increases, the number of ink supply tubes 105 for sending ink from the ink tank 103 to the head 104 increases. This makes it difficult to manage the ink.

Further, the configuration disclosed in Japanese Patent Application Laid-Open No. 4-39055 requires a configuration for jetting the cleaning liquid toward the nozzles when cleaning the ink nozzles, which causes a problem that the apparatus becomes large and complicated. Occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to enable high-quality printing without increasing the size and complexity of the apparatus and to use a cleaning liquid. An object of the present invention is to provide an ink jet printer capable of performing cleaning of an ink nozzle which is highly effective when used.

[0013]

In order to solve the above problems, an ink jet printer according to the present invention uses a plurality of color inks on a recording medium from a color ink discharge nozzle provided for each color used. In an ink jet printer that forms a color image on a recording medium by ejecting the color inks, at least two colors of the color ink to be used, each color ink ejection nozzle of a color ink ejection nozzle row arranged in a row and The thinning liquid discharge nozzles provided in a row in a one-to-one correspondence, and the thinning liquid from the thinning liquid discharge nozzle is caused to land on the same point as the discharge of the color ink at the time of forming dots having a predetermined density or less. And control means for causing the liquid to be ejected.

According to the above configuration, dots can be formed by using the provided color ink alone, and further, for at least two or more color inks provided with a diluting liquid discharge nozzle, By causing the color ink and the diluting liquid to land on the same point on the recording medium, it is possible to form lighter colored dots than when the color ink is used alone.

That is, only by newly providing a thinning liquid,
Furthermore, since dots of two or more colors can be formed, it is possible to obtain almost the same high image quality as in the case of performing multi-color printing while suppressing the number of ink tanks provided. The image quality can be improved at the same time.

Further, the ink jet printer is provided with a diluting liquid discharging nozzle provided corresponding to the color ink discharging nozzle for all colors of the color ink used, and the diluting liquid is supplied with the ink. The control means can be used for cleaning the head, and the control means causes the thinning liquid to flow out of the thinning liquid discharging nozzle at a low speed when the corresponding color ink discharging nozzle is washed with the thinning liquid. It can be configured.

According to the above arrangement, the control means controls the thinning liquid discharge nozzle to cause the thinning liquid to flow out at a low speed, so that the thinning liquid flowing out of the thinning liquid discharge nozzle is reduced to the thinning liquid. The ink spreads along the nozzle plate surface without being discharged from the discharge nozzle, and the color ink discharge nozzle can be covered with the thinning liquid. Thereby, the thinning liquid can be used as a cleaning liquid, and the cleaning of the ink nozzle which is highly effective by using the cleaning liquid can be performed.In addition, the ink jet printer has a color ink discharging nozzle and a thinning liquid discharging nozzle. It is preferable that the formed nozzle plate is divided into a plurality of nozzles according to the type of ink corresponding to the formed color ink discharging nozzle and the thinning liquid discharging nozzle.

According to the above configuration, by dividing the nozzle plate, it is possible to prevent the thinning liquid used for cleaning the ink head from flowing into the adjacent ink plate, and to mix different types of ink when cleaning the ink head. It can be prevented from fitting. In addition, as the ink type when dividing the nozzle plate, the nozzle plate may be divided into a pigment-based ink (for example, a black ink) and a dye-based ink (for example, a color ink other than black), or each ink color may be divided. Alternatively, the divided nozzle plate may be divided.

Accordingly, at the start of printing (that is, at the time of transition from washing to printing), it is not necessary to discharge a large amount of ink idle or vacuum suction to remove ink mixed during washing.

Preferably, the ink jet printer is provided with a capping means for capping the nozzle plate at the time of cleaning the ink head for each divided nozzle plate.

According to the above construction, the nozzle plate is covered with the capping means, and the space between the nozzle plate and the capping means is filled with the diluting liquid, so that the ink head is thinned while preventing the drying of the diluting liquid. The liquid ink can be covered for a long time, and the effect of preventing the color ink from drying can be maintained for a long time.

In cleaning the ink head,
By covering the nozzle plate with the capping means, the thinning liquid flowing out of the thinning liquid discharging nozzle can be efficiently guided to the color ink discharging nozzle, thereby suppressing consumption of the thinning liquid used for cleaning the ink head. can do.

In the above-mentioned ink jet printer,
The control means controls the first pressurizing means for pressurizing the ink discharged from the ink pressurizing chamber through the thinning liquid discharge nozzle when cleaning the ink head using the thinning liquid. A configuration may be adopted in which pressure is applied to the thinning liquid flowing out.

According to the above configuration, the ink discharge at the time of the printing operation and the ink outflow at the time of cleaning the ink head,
The same first pressurizing means can be used, and the configuration of the apparatus can be simplified.

In the above-mentioned ink jet printer,
The control means pressurizes the ink supplied to the ink pressurizing chamber in a common ink chamber for supplying the ink to the ink pressurizing chamber when cleaning the ink head using the thinning liquid. It is possible to adopt a configuration in which the second pressurizing means is controlled to pressurize the outflow diluent.

According to the above configuration, it is not necessary to switch the driving pulse between the printing operation and the ink head cleaning,
Ink ejection control becomes easy.

In the above-mentioned ink jet printer,
The corresponding color ink discharge nozzles and thinning liquid discharge nozzles are inclined by the same angle θ in the same plane and in the opposite direction to the normal of the nozzle plate, and the inclination angle θ When the distance between the surface and the recording medium is V, and the distance between the two ink nozzles is H, it is preferable that sin θ = H / 2V.

According to the above configuration, in the configuration in which the ink nozzles are inclined as described above, when the color ink and the diluting liquid are simultaneously discharged from the color ink discharging nozzle and the diluting liquid discharging nozzle, these are discharged. It is possible to land simultaneously on the same point on a recording medium. In other words, ink droplets and thinning droplets ejected from two ink nozzles at different positions on the ink plate surface can be landed at the same point without making the ejection timing different, thereby controlling the ink ejection timing. Becomes easier.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIGS. 2 and 3 show a schematic configuration of the ink jet printer according to the present embodiment. FIG. 2 is a perspective view showing an external view of the inkjet printer 2 according to the present embodiment. FIG. 3 is a schematic diagram showing the internal structure of the inkjet printer 2 of FIG. FIG. 3 shows a paper transport system and an inkjet printing system in the internal structure of the color inkjet printer 2.

As shown in FIG. 2, the ink jet printer 2 comprises an ink jet printer main body housed in a cabinet 4, and a paper feed tray 6 and a paper discharge tray 8 provided on one side of the cabinet 4. I have. The paper feed tray 6 is provided with a slide paper fixing plate 6a that can slide according to the width of the recording paper 20 to be used. The slide sheet fixing plate 6a has a function as a guide for the recording sheet 20.

As shown in FIG. 3, a pickup roller 12, a first paper feed roller 14, a paper feed path 16, a second paper feed roller (PS roller) 18, a star A roller 24 and a discharge roller 22 are provided. Further, the ink jet printing system includes an ink head 10 and carriage holding shafts 26. Further, a control device 28 is provided as a control unit. Hereinafter, each of these units will be described.

As shown in FIG. 3, the moving direction of the recording paper 20 at the position facing the head 10 is defined as the y direction, and the normal direction of the recording paper 20 at the position facing the head 10 is defined as the z direction. A direction orthogonal to the z direction and the y direction is defined as an x direction.

The pickup roller 12 is connected to the sheet tray 6.
1 is taken out of the recording paper 20 accommodated in the printer and carried into the paper transport system. First paper feed roller 14, paper transport path 1
6 and the second paper feed roller 18 convey the recording paper 20 carried in by the pickup roller 12 to a portion facing the head 10 which is a printing unit. The star roller 24 and the paper discharge roller 22 discharge the recording paper 20 on which printing (recording) with ink has been performed in the printing unit to the paper discharge tray 8 with the print surface facing upward.

The head 10 has a carriage holding shaft 2
The recording paper 20 is supported by the recording paper 6 and is swingable in the width direction of the recording paper 20, that is, in the direction (x direction) perpendicular to the transport direction in which the recording paper 20 is transported. And
The head 10 includes a control device 28 and a drive system (not shown).
Thus, the inkjet printing is performed while scanning the recording paper 20 based on the image data of the image to be printed and the position of the recording paper 20 transported by the paper transport system.

The head 10 has an ink tank containing ink used for ink-jet printing, and a nozzle (discussed later in detail) for discharging ink.

The color ink jet printer 2
The processes and operations in are controlled by the controller 28 unless otherwise specified.

When the printing operation is started in the color ink jet printer 2 having such a configuration, first, the recording paper 20 accommodated in the paper feed tray 6 is picked up by the pickup roller 12, the first paper feed roller 14, the paper Transport path 1
6 and by the second paper feed roller 18 are conveyed to the printing unit. Then, when the recording paper 20 passes through the printing unit,
Ink is ejected from the head 10 onto the recording paper 20 to form an image on the recording paper 20.

The recording sheet 20 on which the image has been formed is moved to the star roller 24 and the discharge roller 22 at the destination.
The discharge tray 8 outside the cabinet 4 (see FIG. 2)
Then, the paper is discharged with the printing surface facing up, that is, face-up. Here, the discharge roller 22 discharges the recording paper 20 by contacting the edge of the recording paper 20 and does not contact the portion of the recording paper 20 where the image is formed.

When an image is continuously formed on a plurality of recording sheets 20, the ink on the recording sheet 20 discharged first is dried by the time the next recording sheet 20 is discharged. Is desirable. As a result, the ink of the recording paper 20 discharged first is discharged from the recording paper 20 discharged next.
The recording paper 20 can be prevented from being contaminated.

Accordingly, the recording paper 20 to be discharged next is
It is desirable to adjust the drying time of the ink on the recording paper 20 that is discharged first in consideration of the printing time (printing time) of the image printed on the recording paper 20.

In the above ink jet printer,
C (cyan), M (magenta), Y (yellow), Bk
Color printing is performed using transparent ink in addition to the four (black) colored inks. The transparent ink is used to produce light cyan or light magenta color by landing on the same dot as cyan or magenta ink.

Therefore, in the ink head 10 of the ink jet printer, the ink nozzles are arranged as shown in FIG. 4A or 4B.

In the arrangement shown in FIG. 4A, black ink nozzles and yellow, magenta and cyan ink nozzles are formed on different nozzle plates 30 and 32, respectively. Two nozzle rows are formed in a direction orthogonal to the scanning direction (x direction) of the ink head 10. That is, in the nozzle plate 30, one nozzle row is provided as a black ink discharge nozzle row in which the black ink discharge nozzles 30a are arranged, and the other nozzle row is a transparent ink discharge nozzle (thinning liquid discharge nozzle) 30b. Are provided as a transparent ink discharge nozzle row in which are arranged. Nozzle plate 32
In one of the nozzle rows, one of the nozzle rows is
The nozzle row is provided as a color ink discharge nozzle row in which a is arranged, and the other nozzle row is provided as a transparent ink discharge nozzle row in which transparent ink discharge nozzles (thinning liquid discharge nozzles) 32b are arranged. Further, in the nozzle plate 32, each nozzle row of the color ink discharge nozzle 32a and the transparent ink discharge nozzle 32b is divided into three regions along the nozzle arrangement direction, and each region is used for forming a yellow dot. , Magenta dot formation and cyan dot formation.

In the arrangement shown in FIG. 4B, ink nozzles for black, yellow, magenta and cyan are formed on different nozzle plates 34, 36, 38 and 40, respectively. 2 in the direction orthogonal to the scanning direction (x direction) of the head 10
A row of nozzle rows is formed. That is, in each of the nozzle plates 34, 36, 38, and 40, nozzles 34a, 36a, 38a, and 40a for discharging black, yellow, magenta, or cyan ink are arranged in one nozzle row, and transparent in the other nozzle row. The ink discharge nozzles 34b, 36b, 38b, and 40b are arranged.

As described above, in the above-mentioned ink jet printer, the ink nozzle for discharging the transparent ink is formed adjacent to the ink nozzle for discharging the color ink (black, yellow, magenta, cyan). For this reason, as shown in FIG. 1, the color ink and the transparent ink used as the diluting liquid are both landed on the same point of the recording medium to form dots of a color lighter than the color of the mounted color ink. can do. In FIG. 1, FIG.
FIG. 3B illustrates the nozzle plate 40, which illustrates the ink discharge from the cyan color ink discharge nozzles 40a and the transparent ink discharge nozzles 40b. However, the other nozzle plates also perform color ink discharge. And the transparent ink discharge nozzle have the same configuration.

The landing of the color ink and the transparent ink on the same point is performed by controlling the ink ejection timing by a control device (control means) 28. In addition, the control device 28 controls the formation of the light-colored dots by landing the color ink and the transparent ink on the same point so as to be performed at the time of forming a dot having a density lower than a preset threshold density. .

More specifically, black, yellow, magenta or cyan dots can be formed by dots formed using color ink alone, and furthermore, cyan or magenta ink and transparent ink are used. In the dots formed by light cyan, light cyan or light magenta dots can be formed. As a result, in the above-described ink jet printer, the four colors of ink and the transparent ink are used and five types of inks are used, and the ink jet printer has almost the same high printing performance as that of six colors (black, yellow, magenta, cyan, light magenta, and light cyan). Image quality can be obtained.

In the above description, only the cyan and magenta inks are used for printing the transparent ink in a light color, and the black and yellow color inks are used in spite of the fact that the printing using the transparent ink is not performed. The transparent ink discharge nozzles 34b and 36b are provided adjacent to the discharge nozzles. This is because, in the ink jet printer according to the present embodiment, the transparent ink is used not only for printing the light color but also for cleaning the ink nozzles. If the transparent ink is not used for cleaning the ink nozzles, cyan ink is used. Alternatively, a configuration may be adopted in which a transparent ink discharge nozzle is provided only for magenta. Cleaning of the ink nozzle will be described later.

In the case of yellow, light yellow dots are not usually formed by simultaneously using the yellow ink and the transparent ink. However, dark yellow ink is used instead of yellow ink, and this ink is used. It is possible to form a dark yellow dot by using it alone, and to form a yellow dot by using the same path as the transparent ink. in this case,
Using four types of ink, four color inks and transparent ink, it is possible to obtain almost the same high image quality as in the case of printing in seven colors (black, dark yellow, magenta, cyan, yellow, light magenta, light cyan). It becomes possible.

As shown in FIG. 1, ink is supplied to the ink pressurizing chamber 42 provided one-to-one with respect to each ink nozzle in the ink jet printer. This is performed by applying pressure to the ink. That is, the ink in the ink pressurizing chamber 42 is ejected as ink droplets from the ink nozzle by pressurization. As the ink pressurizing method at this time, various methods such as a method using a piezoelectric element and a method using a thermal head have been proposed, but in the present invention, the ink pressurizing method is not particularly limited. .

The ink ejection directions of the color ink ejection nozzle and the transparent ink ejection nozzle are shown in FIG.
It is preferable to adopt a configuration in which the nozzle plate 40 is inclined without being aligned with the normal direction of the nozzle plate 40. More specifically, a color ink discharge nozzle 40a for forming light-colored dots by simultaneous landing of recording media
The two nozzles of the transparent ink discharge nozzle 40b are inclined at the same angle θ in the same plane and in the opposite direction to the normal line of the nozzle plate 40. Further, as for the inclination angle θ, when the distance between the nozzle plate 40 and the recording medium is V and the distance between the two ink nozzles is H, sin θ = H / 2V.

In the configuration in which the ink nozzles are inclined as described above, when the color ink and the transparent ink are simultaneously ejected from the color ink ejection nozzle 40a and the transparent ink ejection nozzle 40b, these two types of ink are recorded. Simultaneous impact can be made at the same point on the medium. In other words, ink droplets ejected from two ink nozzles at different positions on the ink plate surface can be landed at the same point without changing the ejection timing, thereby facilitating the control of the ink ejection timing. . Even if the ink nozzles are not inclined as described above, by appropriately controlling the ejection timing of the color ink and the transparent ink in consideration of the scanning speed of the ink head, these two types of ink can be used. Can land at the same point on the recording medium.

As described above, the ink jet printer according to the present embodiment obtains a high image quality equivalent to that of multicolor printing of six or more colors by using five types of inks by printing using transparent ink. However, the present invention is further characterized in that the ink head is cleaned using the transparent ink. Therefore, a method of cleaning the ink head will be described below.

The cleaning of the ink head in the ink jet printer is performed as shown in FIGS. 5 (a) and 5 (b).
The transparent ink is discharged from the transparent ink discharge nozzle 40b, and the color ink discharge nozzle 40a is
Is carried out. In addition, FIG.
1B also illustrates the nozzle plate 40 in FIG. 4B as in FIG. 1, but the other nozzle plates have the same configuration.

This cleaning of the ink head is preferably performed at the home position where the ink head is on standby, for example, at the start of use of the ink jet printer or at the end of the job. Further, when the above-mentioned inkjet is not used, by keeping the state where the transparent ink covers the nozzles for discharging the color ink, the color ink dries and the nozzle components are clogged due to precipitation of the pigment component or the dye component. Can be prevented.

FIG. 5A shows a structure in which the transparent ink alone covers the color ink discharge nozzles 40a when the ink head is washed and when drying is prevented. However, in the configuration in this case, in particular, when the inkjet printer is not used, the vaporization of the transparent ink on the nozzle plate 40 cannot be prevented, and when the inkjet printer is not used for a long time, the transparent ink dries and the color ink is dried. There is a possibility that the effect of preventing the drying of the film cannot be obtained.

Therefore, in practice, as shown in FIG. 5B, at the home position where the ink head stands by at the time of cleaning and prevention of drying of the ink head, the nozzle plate 40 is separated from and connected to the nozzle plate 40. Covered with a possible cap member (capping means) 44,
It is preferable that the space between the nozzle plate 40 and the cap member 44 be filled with transparent ink. Thereby, the transparent ink can be prevented, and the effect of preventing the color ink from drying can be maintained for a long time. Also, at the time of cleaning the ink head, by covering the nozzle plate 40 with the cap member 44, the transparent ink flowing from the transparent ink discharge nozzle 40b can be efficiently guided to the color ink discharge nozzle 40a. The consumption of the transparent ink used for cleaning the ink head can be suppressed.

The cap member 44 is preferably provided for each nozzle plate. That is, FIG.
In the ink head 10 having the nozzle plates 30 and 32 shown in FIG. 6A, a cap member 44a is provided for the nozzle plate 30 and the nozzle plate 32 is provided for the nozzle plate 32, as shown in FIG. Cap member 44b
Should be provided. In addition, in the ink head 10 having the configuration shown in FIG. 4B, as shown in FIG. 6B, cap members 44c, 44d, 44e, and 44f are provided for the nozzle plates 34, 36, 38, and 40, respectively. It is good to provide.

The provision of the cap member 44 for each nozzle plate has the following advantages. That is, in the above-described inkjet printer, a pigment-based ink is used as the black ink, and a dye-based ink is used as the yellow, magenta, and cyan color inks. However, by providing the cap member 44 for each nozzle plate, It is possible to prevent these kinds of different inks from being mixed at the time of cleaning the ink head. In the configuration of FIG. 6B in which the nozzle plate is divided for each color, it is possible to prevent inks of different colors from being mixed.

Thus, at the start of printing (that is, at the time of transition from washing to printing), it is not necessary to discharge a large amount of ink or vacuum suction to remove ink mixed during washing. Further, as shown in FIG. 5A, even in a configuration in which the cap member 44 is not provided,
By dividing the nozzle plate, it is possible to prevent the transparent ink used for cleaning the ink head from flowing into the adjacent ink plate.

As described above, in the above-described ink jet printer, the nozzles for cleaning and drying are prevented by covering the nozzles for discharging color ink with the transparent ink. However, the nozzles for discharging color ink are covered with the transparent ink. In this state, ink cannot be ejected. Therefore, at the start of printing, for example, the transparent ink on the nozzle plate surface is wiped off by wiping or the like. Also, in a configuration in which the cap member 44 is provided, an ink suction mechanism is provided on the cap member 44 and the nozzle plate surface is provided. It is preferred to aspirate the clear ink above.

In the above-mentioned ink jet printer,
2) Printing of transparent ink with light color and cleaning of ink head
However, in order to achieve these two effects, it is necessary to vary the speed of the transparent ink when discharging or flowing out the transparent ink from the transparent ink discharging nozzle.

Specifically, when the transparent ink is used for printing a light color (at the time of ink ejection), as shown in FIG. Is large. Accordingly, the speed of the ink ejected from the ink nozzle increases, and the ink is ejected toward the recording paper. On the other hand, when the transparent ink is used for cleaning the ink head (at the time of ink spill), the drive pulse used for ink spill is changed as shown in FIG.
As shown in the figure, the waveform has a long on period and a small amplitude. This reduces the speed of the ink ejected from the ink nozzles and spreads the ink along the nozzle plate surface without being ejected toward the recording paper. Can be. The drive pulses shown in FIGS. 7A and 7B are, for example, voltage-driven in a pressurizing method using a piezoelectric element, and current-driven in a pressurizing method using a thermal jet.

In the above-described ink discharge and outflow control method, as shown in FIGS. 8A and 8B, in the ink pressurizing chamber 42, a pressurizing method for pressurizing ink discharged from an ink nozzle is performed. This is a method for controlling the means (first pressurizing means) 46. However, when performing the ink head cleaning, it is not particularly necessary to control the outflow of the transparent ink for each nozzle, and it is sufficient that the outflow of all the ink nozzles is uniform. Therefore, in order to perform ink head cleaning,
In a common ink chamber 48 for supplying ink to the ink pressurizing chamber 42, pressurizing means 50 (second pressurizing means) for pressurizing the ink supplied to the ink pressurizing chamber 42 is provided,
By controlling the pressurizing means 50, it is possible to make the transparent ink uniformly flow out from all the transparent ink discharge nozzles.

The pressurizing means 4 in the ink pressurizing chamber 42
In the method of controlling 6, the same ink pressurizing means can be used for the ink discharge during the printing operation and the ink outflow during the ink head cleaning, and the configuration of the apparatus can be simplified. In the method of controlling the pressurizing means 50 in the common ink chamber 48, the pressurizing means 5 is newly added.
Although it is necessary to set 0, it is not necessary to switch the driving pulse between the printing operation and the ink head cleaning, and the ink ejection control becomes easy.

In the above-described ink jet printer, the transparent ink used for printing a light color and cleaning the ink head has a composition in which a pigment component and a dye component are removed from materials constituting other color inks. Is preferred. In other words, by making the basic constituent material of the transparent ink the same as that of the other color ink main body, when performing printing of a light color, the compatibility with other color inks is good and the print density can be reduced uniformly. It is possible. Further, when the ink head is cleaned, the cleaning effect is enhanced because the ink is well compatible with the solid material of the color ink (for example, dried ink) and is easy to dissolve the solid material.

As described above, in the ink jet printer according to the present embodiment, it is possible to obtain the same high image quality as when printing is performed using six types of inks using five types of inks. . That is, in the above-described inkjet printer, it is possible to mount five ink tanks, and it is possible to simultaneously achieve high image quality by multicolor printing and avoid complication of the configuration due to an increase in the number of ink tanks.

Here, the arrangement of the ink nozzles is shown in FIG.
FIG. 9 shows an example of the arrangement of the ink tanks in the case of the arrangement shown in FIG.
(A).

In the example of FIG. 9A, the ink carriage 5
2, nozzle plates 34, 36, 38 and 40 for black, yellow, magenta and cyan are provided. On the ink carriage 52, ink tanks 54a to 54d for black, yellow, magenta, and cyan, and an ink tank 54e for transparent ink are mounted, and the nozzle plates 34 and 36 are provided from these five ink tanks. Ink discharged at 38 and 40 is supplied.

The ink supplied from the ink tank is supplied from the common ink chamber 48 to the ink pressurizing chamber 50 as described above.
The ink is discharged (or discharged) by pressurization in the ink pressurizing chamber (see FIG. 8). Here, the arrangement of the common ink chamber is shown in FIG. In the example of this case, in the nozzle plate 34, a common ink chamber 48a is provided for the black ink discharge nozzle 34a, and the transparent ink discharge nozzle 34a is provided.
A common ink chamber 48b is provided for b. Similarly, in the nozzle plate 36, a common ink chamber 48c is provided for the yellow ink discharge nozzle 36a, and a common ink chamber 48d is provided for the transparent ink discharge nozzle 36b. In the nozzle plate 38, a magenta ink discharge Common ink chamber 48 for nozzle 38a
e, a common ink chamber 48f is provided for the transparent ink discharge nozzle 38b, and the common ink chamber 48g for the cyan ink discharge nozzle 40a and the common ink chamber 48g for the transparent ink discharge nozzle 40b in the nozzle plate 40. An ink chamber 48h is provided.

The common ink chamber 4 for color ink
Inks 8a, 48c, 48e, and 49g are supplied with ink from ink tanks 54a to 54d corresponding to the respective colors via communication holes 56a to 56d.
On the other hand, the common ink chambers 48b, 48d, 4
8f and 49h are communicated by a communication portion 48i,
These common ink chambers 48b, 48d, 48f, 49h
Is supplied with transparent ink from the ink 54e through the communication hole 56e. In FIG. 9B, illustration of the ink pressurizing chamber is omitted.

In FIGS. 9A and 9B, a serial ink head having an ink tank mounted on an ink carriage is illustrated, but an ink tube is passed from an ink tank fixed in the printer body. Also in the fixed ink head for supplying ink to the ink head, the arrangement of the common ink chamber in the ink head is shown in FIG.
It can be similar to (b). That is, in the case of a fixed ink head, as shown in FIG. 10, ink is supplied from the ink tanks 58a to 58e to the ink head 62 via the ink tubes 60a to 60e.

[0074]

As described above, the ink jet printer according to the present invention has a structure in which at least two colors of the used color inks are provided with the respective color ink discharge nozzles of the color ink discharge nozzle row arranged in a row. The thinning liquid discharge nozzles provided in a row in a one-to-one correspondence, and the thinning liquid from the thinning liquid discharge nozzle is caused to land on the same point as the discharge of the color ink at the time of forming dots having a predetermined density or less. And a control means for causing the liquid to be ejected to the nozzles.

Therefore, it is possible to form dots by using the provided color ink alone, and further, for at least two or more color inks provided with a diluting liquid discharge nozzle, a color ink By landing the liquid and the same point on the recording medium, it is possible to form dots of a lighter color than when using the color ink alone, and it is almost the same as when performing multicolor printing while suppressing the number of ink tanks provided. There is an effect that the same high image quality can be obtained.

In addition, the above-mentioned ink jet printer is provided with thinning liquid discharging nozzles provided corresponding to the color ink discharging nozzles for all the colors of the color ink to be used. The control means can be used for cleaning the head, and the control means causes the thinning liquid to flow out of the thinning liquid discharging nozzle at a low speed when the corresponding color ink discharging nozzle is washed with the thinning liquid. It can be configured.

Therefore, by controlling the thinning liquid to flow out at a low speed, the thinning liquid flowing out of the thinning liquid discharging nozzle is not discharged from the thinning liquid discharging nozzle but is discharged along the nozzle plate surface. The thinning liquid can be used as a cleaning liquid.

In the above-described ink jet printer, the nozzle plate on which the color ink discharging nozzles and the thinning liquid discharging nozzles are formed is formed by the ink plate corresponding to the formed color ink discharging nozzles and the thinning liquid discharging nozzles. It is preferable that the configuration is divided into a plurality according to the type.

Therefore, by dividing the nozzle plate, it is possible to prevent the thinning liquid used for cleaning the ink head from flowing into the adjacent ink plate, and to prevent different types of ink from being mixed at the time of cleaning the ink head. It has the effect of being able to.

Further, it is preferable that the ink jet printer is provided with a capping means for capping the nozzle plate at the time of cleaning the ink head for each divided nozzle plate.

Therefore, by filling the space between the nozzle plate and the capping means with the thinning liquid, the ink head can be covered with the thinning liquid for a long time while preventing the drying of the thinning liquid. This has the effect that the effect of preventing the color ink from drying can be maintained for a long time.

In cleaning the ink head,
By covering the nozzle plate with the capping means, the thinning liquid flowing out of the thinning liquid discharging nozzle can be efficiently guided to the color ink discharging nozzle, thereby suppressing consumption of the thinning liquid used for cleaning the ink head. It also has the effect of being able to do so.

In the above-mentioned ink jet printer,
The control means controls the first pressurizing means for pressurizing the ink discharged from the ink pressurizing chamber through the thinning liquid discharge nozzle when cleaning the ink head using the thinning liquid. A configuration may be adopted in which pressure is applied to the thinning liquid flowing out.

Therefore, the same first ejection is performed between the ink ejection during the printing operation and the ink outflow during the ink head cleaning.
Thus, there is an effect that the configuration of the apparatus can be simplified.

In the above-mentioned ink jet printer,
The control means pressurizes the ink supplied to the ink pressurizing chamber in a common ink chamber for supplying the ink to the ink pressurizing chamber when cleaning the ink head using the thinning liquid. It is possible to adopt a configuration in which the second pressurizing means is controlled to pressurize the outflow diluent.

Therefore, there is no need to switch the driving pulse between the printing operation and the ink head cleaning, and the effect of easily controlling the ink discharge can be obtained.

In the above-mentioned ink jet printer,
The corresponding color ink discharge nozzles and transparent ink discharge nozzles are inclined by the same angle θ in the same plane and in the opposite direction to the normal line of the nozzle plate, and the inclination angle θ When the distance between the surface and the recording medium is V, and the distance between the two ink nozzles is H, it is preferable that sin θ = H / 2V.

Therefore, when the color ink and the diluting liquid are simultaneously ejected from the color ink discharging nozzle and the diluting liquid discharging nozzle, these can be simultaneously landed on the same point on the recording medium, and the ink is discharged. The effect that timing control becomes easy is produced.

[Brief description of the drawings]

FIG. 1 illustrates one embodiment of the present invention, and is an explanatory diagram in a case where a dot of a light color is formed by simultaneously landing a color ink and a transparent ink.

FIG. 2 is a perspective view illustrating an example of a configuration of an inkjet printer to which the present invention is applied, and illustrating an appearance of the inkjet printer.

FIG. 3 is an explanatory diagram showing an internal structure of the ink jet printer.

FIG. 4 is an explanatory view showing an example of the arrangement of nozzle plates in the inkjet printer. FIG. 4A shows a case where a nozzle plate is divided by a pigment ink and a dye ink.
(B) shows a case where the nozzle plate is divided for each color.

FIGS. 5A and 5B are explanatory diagrams showing a state of the ink jet printer when the ink head is washed and when the ink head is prevented from drying. FIG.
Indicates a case where a cap member is provided.

FIGS. 6A and 6B are explanatory diagrams showing a configuration in which a cap member is provided for each nozzle plate in the inkjet printer. FIG. 6A is a diagram in which a nozzle plate is divided into a pigment ink and a dye ink, and FIG. The case where the nozzle plate is divided is shown.

FIGS. 7A and 7B are explanatory diagrams showing a drive pulse given at the time of ink ejection or outflow in the ink jet printer, wherein FIG. 7A shows an ink ejection drive waveform at the time of a printing operation, and FIG. 4 shows an outflow drive waveform.

8A and 8B are explanatory views showing a pressurizing unit when ink flows out in the ink jet printer, wherein FIG. 8A is a view of the ink head as viewed from the x direction in FIG. 3, and FIG.
Shows a view of the ink head viewed from the y direction in FIG.

FIGS. 9A and 9B are diagrams illustrating an example of the arrangement of ink tanks in a serial type ink head in the ink jet printer, wherein FIG. 9A is a perspective view and FIG. 9B is an explanatory diagram illustrating an arrangement of a common ink chamber.

FIG. 10 is a perspective view showing an example of the arrangement of ink tanks in a fixed type ink head in the inkjet printer.

11A and 11B are diagrams illustrating an example of the arrangement of ink tanks in a serial type ink head in a conventional inkjet printer, where FIG. 11A is a perspective view and FIG. 11B is an explanatory diagram illustrating an arrangement of a common ink chamber. .

FIG. 12 is a perspective view showing an arrangement example of ink tanks in a fixed ink head in a conventional ink jet printer.

[Explanation of symbols]

28 Control device (control means) 30, 32, 34, 36, 38, 40 nozzle plate 30a, 34a Black ink discharge nozzle (color ink discharge nozzle) 32a, 36a, 38a, 40a Color ink discharge nozzle 30b, 32b , 34b, 36b, 38b, 40b Nozzles for discharging transparent ink (nozzles for discharging thinning liquid) 42 Ink pressurizing chamber 44 Cap member (capping means) 46 Pressurizing means (first pressurizing means) 48 Common ink chamber 50 Pressure means (second pressure means)

Claims (7)

[Claims] An ink jet printer for discharging a plurality of color inks from a color ink discharge nozzle provided for each color to be used on a recording medium to form a color image on the recording medium. For at least two colors of ink, thinning liquid discharge nozzles provided in a row in a one-to-one correspondence with each color ink discharge nozzle in a color ink discharge nozzle row arranged in a row; An ink jet printer, comprising: control means for discharging a thinning liquid from a thinning liquid discharge nozzle so as to land on the same point as the discharge of color ink when forming dots having a predetermined density or less. 2. A diluting liquid discharging nozzle provided for each color of the color ink to be used in correspondence with a color ink discharging nozzle, and the diluting liquid is used for cleaning an ink head. The control means may cause the thinner liquid to flow out of the thinner liquid discharge nozzle at a low speed when the corresponding color ink discharge nozzle is washed with the thinner liquid. The inkjet printer according to claim 1. 3. A nozzle plate on which color ink discharge nozzles and thinning liquid discharge nozzles are formed, wherein a plurality of nozzle plates are provided in accordance with the type of ink corresponding to the formed color ink discharge nozzles and thinning liquid discharge nozzles. 3. The ink jet printer according to claim 2, wherein the ink jet printer is divided into two. 4. The ink jet printer according to claim 3, wherein a capping means for capping the nozzle plate when the ink head is washed is provided for each of the divided nozzle plates. 5. The method according to claim 1, wherein the control means pressurizes the ink ejected from the ink pressurizing chamber through the thinning liquid discharge nozzle when the ink head is cleaned using the thinning liquid.
The ink jet printer according to any one of claims 2 to 4, wherein the pressurizing means is controlled to pressurize the outflow diluent. 6. The ink supply device according to claim 6, wherein said control means includes a common ink chamber for supplying ink to the ink pressurizing chamber when the ink head is washed using said thinning liquid. The ink jet printer according to any one of claims 2 to 4, wherein a second pressurizing means for pressurizing the liquid is controlled to pressurize the thinning liquid flowing out. 7. The corresponding color ink discharge nozzle and thinning liquid discharge nozzle are inclined by the same angle θ in the same plane and in the opposite direction with respect to the normal of the nozzle plate. is set so as to satisfy sin θ = H / 2V, where V is the distance between the nozzle plate surface and the recording medium, and H is the distance between the two ink nozzles. 7. The ink jet printer according to any one of 1 to 6.