JPH06199031A - Method and apparatus for ink jet recording - Google Patents

Abstract

(57) [Summary] [Purpose] Of multiple inks with similar colors but different densities,
A desired image is obtained even when stable ejection of at least one kind of ink becomes difficult. [Structure] Having a plurality of distribution tables of dark and light inks having different densities, when it is difficult to stably discharge at least one kind of ink, the distribution table is selectively used to record using the remaining inks. By carrying out, stable recording can be continued.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method and apparatus for recording on a recording medium by ejecting ink from ejection ports of a recording head using a plurality of inks of similar colors but different in density.

[0002]

2. Description of the Related Art In a conventional ink jet recording system, ink is ejected from a plurality of ink ejection openings formed in a recording head based on a data signal, and ink droplets are adhered to a recording material such as paper for recording. ing. This recording method is
For example, it is used in printers, facsimiles, copiers, and the like.

In the above apparatus, in order to eject the ink, a heating element (electrical / thermal energy converter) is provided in the vicinity of the ejection port, and an electric signal is applied to the heating element to locally heat the ink. There are a method of using an electrical / thermal energy converter that causes a pressure change and ejects ink from an ejection port, and a method of using an electrical / mechanical converter such as a piezoelectric element.

In this type of recording method, a dot density control method is used in which the number of recording dots per unit area is controlled by recording dots of a fixed size to express a halftone, or the size of recording dots is controlled to express a halftone. The halftone recording control is performed by the dot diameter control method.

Here, the latter dot diameter control method is limited because complicated control for subtly changing the size of the recording dot is required, so the former dot density control method is generally used. Has been.

In addition, as an ink ejecting means, it is easy to manufacture, and high density is possible.
When the thermal energy converter is used, it is difficult to control the amount of pressure change and the diameter of the recording dot cannot be modulated, and therefore the dot density control method is used.

The systematic dither method is one of the typical halftone expression binarization methods used in the dot density control method, but this method has a problem that the number of gradations is limited by the matrix size. There is. That is, it is necessary to increase the matrix size in order to increase the number of gradations, but if the matrix size is increased, there is a problem that one pixel of a recorded image formed by one matrix becomes large and the resolution is impaired. It was Another typical binarization method is a conditional decision type dither method such as an error diffusion method. This is an independent decision type dither method in which the systematic dither method described above is binarized by using a threshold value unrelated to the input pixel, whereas the threshold value is changed in consideration of the peripheral pixels of the input pixel. Is the way. The conditional decision type dither method typified by this error diffusion method has good compatibility of gradation and resolution, and when the original image is a printed image,
Although it has the advantage that a moire pattern is rarely generated in the recorded image, it has a problem that the graininess is easily noticeable in the bright areas of the image and the image quality is poorly evaluated. This problem was particularly remarkable in a recording device having a low recording density.

Therefore, in order to make the above-mentioned graininess inconspicuous, the conventional ink jet recording apparatus is provided with two recording heads for respectively ejecting light-colored ink and dark-colored ink, and from the light portion to the halftone portion of the image. A recording method has been proposed in which recording dots are formed with light-colored ink and recording dots are formed with dark-colored ink from the halftone portion to the dark portion.

FIG. 4 is a block diagram showing the main part of a conventional color ink jet recording apparatus of the serial print type using dark and light inks.

A recording head Bkk for ejecting dark black color ink, a recording head Bku for ejecting light black color ink, and a recording head C for ejecting dark cyan color ink.
k, a recording head Cu for ejecting light cyan color ink, a recording head Mk for ejecting dark magenta color ink, a recording head Mu for ejecting light magenta color ink, a recording head Yk for ejecting dark yellow color ink, The recording head Yu that ejects light yellow color ink is installed on the carriage 401 at a predetermined distance.

A recording material made of paper, a plastic thin plate or the like is nipped by a paper discharge roller 402 via a conveyance roller (not shown), and is fed in the direction of an arrow when a conveyance motor (not shown) is driven.

The carriage is guided and supported by the guide shaft 403 and the encoder.

The carriage is reciprocated along the above-mentioned guide shaft by driving a carriage motor 405 via a drive belt 404.

A heating element (electrical / thermal energy converter) for generating thermal energy for ink ejection is provided inside the ink ejection port (liquid path) of the ink jet unit.

According to the reading timing of the encoder,
The heating element is driven based on the recording signal, dark black,
An image can be formed by ejecting and adhering ink droplets on the recording material in the order of light black, dark cyan, light cyan, dark magenta, light magenta, dark yellow, and light yellow.

At the home position of the carriage selected outside the recording area, a recovery unit having a cap portion 406 is provided to maintain the stability of ink ejection.

[0017]

However, in the ink jet recording apparatus using the dark and light inks, the multi-valued R, G, B luminance signals sent from the host are processed by Y, M, C, Bk in the color processing section. Convert to multi-valued density signal. Then, since the density signals are distributed to those recorded with dark ink and those recorded with light ink by the distribution table of the dot development unit, and the distributed signals are binarized and printing is performed by the recording head. When the amount of one of the dark and light inks of the same color has decreased or has disappeared, there is a problem in that the desired image cannot be obtained despite the colors required for image formation.

The present invention has been made in view of the above problems, and is desirable even when it is difficult to stably eject at least one kind of ink among a plurality of inks of the same color but having different densities. It is an object of the present invention to provide an inkjet recording method and an apparatus therefor capable of obtaining an image of.

[0019]

In order to achieve the above object, the present invention is an ink jet recording in which a plurality of inks of similar colors and different densities are used to eject ink from ejection ports of a recording head for recording on a recording medium. The method is characterized in that when stable ejection of at least one kind of ink among the plurality of inks becomes difficult, recording is performed using the remaining kind of ink.

Here, the recording head is a recording head for ejecting ink by utilizing heat energy, and is provided with a heat energy converter for generating heat energy applied to the ink. The applied thermal energy causes the ink to change state,
It is preferable that the recording head ejects ink from the ejection port based on the state change.

Further, according to the present invention, there is provided an ink jet recording apparatus for recording on a recording medium by ejecting the ink from the ejection port of the recording head by using a plurality of inks of the same color but having different densities. And a distribution unit for determining the degree to which each of the plurality of inks is used to form a pixel corresponding to the image signal, and stable ejection of at least one of the plurality of inks is difficult. Change means for judging that the ink has become stable, and a change for changing the degree determined by the distributing means for recording using ink other than the ink for which stable ejection becomes difficult based on the judgment result of the judging means. An inkjet recording apparatus is provided, which comprises:

[0022]

According to the present invention, a plurality of distribution tables for dark and light inks having different densities are provided, and when it is difficult to stably discharge at least one kind of ink, the distribution table is selectively used and the remaining table is used. Stable recording can be continued by performing recording using the above ink.

[0023]

EXAMPLE FIG. 5 is a perspective view showing a main structure of a color ink jet recording apparatus according to an example of the present invention.

Ejection port array for ejecting light black color ink, ejection port array for ejecting light cyan color ink, ejection port array for ejecting light magenta color ink, ejection port array for ejecting light yellow color ink An inkjet unit having each of them, an ejection port array that ejects dark black color ink, an ejection port array that ejects dark cyan color ink, an ejection port array that ejects dark magenta color ink, and a dark yellow color ink The inkjet unit having the respective ejection opening arrays is installed on the carriage 501 at a predetermined distance.

A recording material made of paper, a thin plastic plate or the like is nipped by a paper discharge roller 502 via a conveyance roller (not shown), and is fed in the direction of an arrow when a conveyance motor (not shown) is driven. The carriage is guided and supported by the guide shaft 503 and the encoder. The carriage is reciprocated along the aforementioned guide shaft by driving a carriage motor 505 via a drive belt 504. A heating element (electrical / thermal energy converter) that generates thermal energy for ejecting ink is provided inside the ink ejection port (liquid path) of the ink jet unit.

An image is formed by driving the heating element based on a recording signal according to the reading timing of the encoder and ejecting and depositing ink droplets on the recording material in the order of dark ink color and light ink color. can do. A recovery unit having a cap portion is disposed at the home position of the carriage selected outside the recording area.
When recording is not performed, move the carriage to the home position and seal the ink ejection port forming surface of the corresponding inkjet unit with each cap of the cap section,
It is possible to prevent clogging due to ink sticking or foreign matter such as dust adhering due to ink solvent evaporation.

In addition, the capping function of the cap portion is an empty ejection mode in which ink is ejected to the cap portion apart from the ink ejection port in order to eliminate ejection failure and clogging of the ink ejection port with low recording frequency. It is used for, or operates a pump (not shown) in a capped state,
The ink is sucked from the ink ejection port and is used to recover the ejection of the ink ejection port that has caused the ejection failure. Also, by arranging the blade and the wiping member at the position adjacent to the cap part,
It is possible to clean the surface on which the ink ejection port of the inkjet unit is formed.

FIG. 6 is an explanatory view of the constitution of the ink jet unit used in this embodiment. Wiring board 200
One end of the wiring board is interconnected with the wiring part of the heater board 100, and the other end of the wiring board 200 is provided with a plurality of electric / thermal energy converters for receiving electric signals from the apparatus. Pads are provided. As a result, the electric signals from the main unit are
It is supplied to the thermal energy converter.

The metal support 300 that supports the back surface of the wiring board 200 on a flat surface serves as a bottom plate of the ink jet unit. The presser spring 500 is a claw that is hooked by using a portion formed by bending a groove in the vicinity of the ink discharge port of the groove top 1300 in a substantially U-shaped cross section and an escape hole provided in the base plate to elastically exert a pressing force on the line. The base plate has a pair of rear legs that receive the force acting on the spring.

By this spring force, the wiring board 200 and the groove 1
It is in pressure contact with 300. Wiring board 20 for support
The attachment of 0 is performed by sticking with an adhesive or the like. A filter 700 is provided at the end of the ink supply pipe 2200. The ink supply member 600 is formed by molding, and the groove is also formed with a flow path leading to each ink supply port. To fix the ink supply member 600 to the support 300, two pins (not shown) on the back surface side of the ink supply member 600 are projected through the holes 1901 and 1902 of the support 300, respectively, and heat-sealed. Made easier by.

At this time, the gap between the orifice plate portion 410 and the ink supply member 600 is formed uniformly.
The encapsulant is injected from the upper encapsulant injection port of the ink supply member 600 to seal the wire bonding and at the same time seal the gap between the orifice plate part 410 and the ink supply member 600. Groove 31
0, the orifice plate portion 410 and the support base 30
0 The gap with the front end is completely sealed.

FIG. 7 is a perspective view of the groove top 1300 of the head unit used in this embodiment as seen from the heater board 100 side. A plurality of liquid chambers are provided, and each liquid chamber has a wall 1
It is divided by 0a to 10c. Each liquid chamber is provided with supply ports 20a to 20d for supplying ink.

Grooves 30a to 30c are provided on the pressure contact surfaces of the walls 10a to 10c for partitioning the liquid chambers with the heater board 100. This groove communicates with the outer peripheral portion of the groove top 1300. After the groove mound 1300 is pressed against and closely adhered to the heater board, the outer peripheral portion is sealed with the sealant as described above.
At this time, the sealant penetrates along the groove to fill the gap between the groove and the heater board. In this way, the liquid chamber can be completely separated by the technical process conventionally used in the head. The structure of this groove differs depending on the physical properties of the sealant, and it is necessary to make the shape corresponding to each.

By thus dividing the liquid chamber into a plurality of chambers, different inks can be supplied to the respective ink ejection ports.

The remaining ink amount detection will be described below.
FIG. 8 shows an example of the configuration of the control system according to this example. 200 is A
It is a control unit in the form of a microcomputer having a built-in / D converter, and includes a distribution means for determining the degree to which each of the plurality of inks in the present invention is used, a changing means for changing the degree determined by the distribution means, and the like. 10 is a recording head unit, 300 is a voltage conversion circuit, 4
Reference numeral 00 denotes an alarm device, which may be an indicator such as an LED, a sound generating device such as a buzzer, or a combination thereof. Reference numeral 500 denotes a main scanning mechanism for scanning the carriage HC for recording or the like, which includes a motor and the like. A sub-scanning mechanism 600 includes a motor that conveys a recording medium and the like. V is a remaining amount detection signal from the tank.

In this embodiment, basically, a constant current is passed between two electrodes provided in the ink chamber b to detect the remaining amount of ink in the ink chamber b based on the resistance value between the two electrodes. The relationship between the remaining ink amount and the interelectrode resistance in this case has a relationship as shown in FIG.

FIG. 10 shows the ink cartridge used in this embodiment, and shows the operation for detecting the remaining ink amount. The inside of the ink cartridge body 1 is partitioned into two ink chambers (a, b) and communicated with each other at the bottom, and one ink chamber a is filled with an ink absorber whose capillary force is adjusted and connected to an inkjet recording head. The ink supply unit 2, the atmosphere communication unit 3, the residual detection pin (electrode) 4, and the ink injection port 5 are provided. The ink inlet 5 is closed with a plug 51 such as rubber.

The positional relationship among the atmosphere communicating portion 3, the ink supply portion 2, the residual detection pin (electrode) 4 and the ink injection port 5 is not particularly limited to this. As shown in FIG. 10, when the ink surface of the ink chamber b is lower than the upper electrode of the two electrodes 4, the resistance between the two electrodes is suddenly increased and the voltage at that time is applied between the electrodes. Occur. This voltage is A / D converted by the A / D converter of the control unit directly or through the voltage conversion circuit 300. When the detected value thus obtained becomes larger than the preset value Rth, the table selection circuit in the control unit 200 is notified that the sorting table is switched.

In this embodiment, the method of detecting the remaining amount of ink has been described as the method of detecting from the resistance value between the electrodes provided in the tank, but the method of detecting the remaining amount is not particularly limited to this. Any method may be used, such as a mechanical measurement or an optical measurement. Incidentally, FIG. 15 is a sectional view showing a state in which the dark ink cartridge and the light ink cartridge are connected. In FIG. 15, the ink inlet 5 and the plug 51 are omitted.

(First Embodiment) FIG. 1 is a view best showing the features of the present invention. When either one of the dark and light of the same color is eliminated by printing with the ink of both the dark and light by table selection. 2 shows the flow of the process. In the figure, the color processing section inputs a red image brightness signal R, a green image brightness signal G, and a blue image brightness signal B into an input correction circuit for a cyan image density signal C, a magenta image density signal M, and a yellow image density signal. Convert to signal Y. And color correction (masking) circuit, UCR (undercolor removal)
After the color processing is performed by the black generation circuit, new image density signals C, M, Y and B of cyan, magenta, yellow and black are obtained.
Then, the output correction circuit gamma-converts the image density signals C, M, Y, and Bk of cyan, magenta, yellow, and black.

Subsequent dot development portions are C, M, Y, B.
Select a distribution table that distributes the density signal of k into a density signal for a recording head that prints high-density ink and a density signal for a recording head that prints low-density ink, and select a color processing unit according to the selected distribution table. The density signals of C, M, Y, and Bk generated by the above are used as image density signals Ck, Mk, Yk, and Bkk of dark cyan, dark magenta, dark yellow, and dark black having high dye densities and low cyan, light cyan, Image density signals of light magenta, light yellow, and light black are distributed to Cu, Mu, Yu, and Bku, and the distributed density signals are binarized, and ink is ejected from the corresponding ink ejection port array from each inkjet unit according to the signal value. Is discharged to form a color image.

In FIG. 1, a sorting table A is a sorting table for sorting the data to be printed in dark and light into the print data for dark ink and the print data for light ink so as to show the characteristics shown in FIG. The distribution table B is a distribution table when printing is performed using only dark ink without using light ink. The distribution table C is a distribution table when printing is performed only with light ink without using dark ink. In this figure, a case is shown in which two images are obtained with light ink and printing is performed twice. However, in practice, multiple images are obtained and those images are overlaid by multiple main scans to record the same image density as the image recorded with dark ink, using only light ink. Obtainable.

FIG. 3 shows each distribution table shown in FIG. The distribution table A shown in FIG. 3a is for distributing the data of each color generated by the color processing unit into the data for dark ink and the data for light ink, respectively. The light ink is shown by a solid line and the dark ink is shown by a dashed line. As is apparent from this, only the light ink is used until the input data is a, and when the input data is a or more, the light ink and the dark ink are combined. The distribution table B shown in FIG. 3B is for distributing the data of each color generated by the color processing unit only to each dark ink, and here, the relationship regarding the dark ink of the output data to the input data of the cyan ink is shown. It is represented by a one-dot chain line. The distribution table C shown in FIG. 3C is for distributing the data of each color generated by the color processing unit only to each light ink, and here, the light output data of the first image with respect to the input data of the cyan ink is light. The relationship regarding ink is represented by a solid line, and the relationship regarding light ink of the output data of the second image with respect to the input data is represented by a chain double-dashed line. As is clear from this, the input data is a
Up to the above, only the first image is printed, and when the input data is a or more, the first image and the second image are overlapped and printed to form an image of a high density portion.

In the table selection in FIG. 1, the sorting tables A to C are automatically selected in the sequence as shown in FIG. For this selection, in the sequence of FIG. 2 executed by the control unit 200 shown in FIG. 8, for example, when the printing of one page is completed, the remaining amount of ink is detected for all the colors.
Then, for example, when the cyan light ink does not have a predetermined remaining amount, the sorting table for printing only the dark ink without using the light ink only for cyan is selected, and the portion with low cyan density is not printed. And a good image can be obtained. Also, for example, when there is no predetermined amount of cyan dark ink remaining, a sorting table is selected for printing only dark ink instead of dark ink only for cyan, and the printing method is also recorded by multiple main scans. By using the overlapping recording on the pixels together, it is possible to prevent the high density portion from becoming unprintable and obtain a good image.

In this example, when one of the dark and light inks of cyan is used up, the distribution table which uses either the dark or light of cyan is selected, but the same distribution table is used for all colors. May be.

Further, each of the sorting tables A to C has a different table for each color, even if it has one table for sorting the shades like all the colors. It may be the one that is most suitable for each color.

Further, although the ink remaining amount is detected and the sorting table is automatically selected here, the sorting table selection switch may be provided so that the user can freely select.

The selection of the sorting table may be switched not only at the time of printing one page but also at a predetermined timing such as the time of printing one line.

Further, as described above, for each color, the shade 2
Although the table is a distribution table of printing methods using different types of ink, it may be a table having three types of dark, medium, and light, or more types.

Further, in the present embodiment, the determination that stable ejection of at least one kind of ink among a plurality of inks becomes difficult is made by detecting the decrease of the ink remaining amount. Not limited to this, the determination may be made by detecting another reason that is not caused by the decrease in the remaining ink amount, for example, by detecting non-ejection of ink due to clogging of the ejection port.

As described above, in the ink jet recording apparatus for printing using dark and light ink, C, M,
In addition to a distribution table that distributes the density signals of Y and Bk to a density signal for printing with high density ink and a density signal for printing with low density ink, a distribution table and density for distributing density signals only to high density ink By having a distribution table that distributes density signals only to low-density inks and having a means for selecting these tables, high-density inks or low-density inks of the same color have disappeared, or proper ejection cannot be performed. Even in such a case, according to the present invention, a normal image can be obtained.

(Second Embodiment) By scanning the output image for one page in advance and checking what kind of density distribution the image data has, for example, an image in which the density distribution is concentrated in a high place. In that case, the above-mentioned sorting table B (FIG. 3B) is selected and printing is performed using only dark ink. On the contrary, if the image is such that the density distribution is concentrated in a low place, the above-mentioned distribution table C (see FIG.
Select (c)) and print with only light ink.

As described above, by detecting the density distribution of the image data, it is possible to obtain a uniform image without the graininess due to the printing of the dark ink near the dark / light ink switching portion.

(Third Embodiment) FIG. 11 is a diagram showing a third embodiment, in which an ink remaining amount can be optically detected by using a transparent or translucent material for the tank wall. Is. In this case, a reflection plate 42 such as a mirror for reflecting light is provided on the ink chamber wall in the ink chamber b, and a photo sensor having a light emitting element 43 and a light receiving element 44 is provided outside the tank. The light emitting element 43 and the light receiving element 44 may be provided on the carriage or may be provided at a home position having a recovery system.

In FIG. 11, light is emitted from the light emitting element 43 at a certain angle, and the light reflected by the reflector is received by the light receiving element 44. For example, an LED is used as the light emitting element 43, and a phototransistor or the like is used as the light receiving element 44. FIG. 11A shows the time when the ink is almost full. In such a case, the light emitted from the light emitting element 43 is blocked by the ink in the ink chamber b, and almost no light reaches the light receiving element 44. The detection output is small. However, when the ink is consumed and the state becomes as shown in FIG. 11B, the light emitted from the light emitting element 43 is hardly blocked, and the detection output of the light receiving element becomes high.

Further, FIG. 12 shows a modification in which the light emitting element and the light receiving element are opposed to each other with the ink tank interposed therebetween. Also in this case, the tank material of the ink chamber b is transparent or translucent. In this example, it is not necessary to provide a reflector and the light is directly received, so that the detection sensitivity is good.

By configuring the remaining ink amount detecting means as described above, the light energy (detection output) received by the light receiving element 44 can be obtained as an analog signal, so that for each color of C, M, Y and Bk. In a color inkjet recording apparatus using two kinds of dark and light inks, it is possible to use the dark ink and the light ink almost at the same time by having a plurality of sorting tables according to the difference in the detection output of the dark ink and the light ink of each color and selecting them. it can.

(Fourth Embodiment) FIG. 13 shows how the internal pressure of the ink supply portion changes in accordance with the ink supply amount when the ink tank shown in FIG. 10 is used. In the initial state of recording, a small amount of ink is present in the ink chamber a, and non-pressure is generated due to the capillary force of the compressed ink absorber.
As the amount of ink in the ink chamber a decreases as the ink is supplied, the negative pressure of the ink chamber a gradually increases due to the capillary force according to the compression ratio distribution (pore distribution) of the compressed ink absorber.

When the ink is further consumed, the ink distribution in the ink chamber a is stabilized, and the atmosphere is introduced into the ink chamber b, so that a substantially constant internal pressure is maintained thereafter (ink stable supply period).

When the ink is further consumed and all the ink in the ink chamber b is consumed, the ink in the ink chamber a starts to be consumed again, and the negative pressure in the ink chamber a changes. When the negative pressure in the ink chamber a becomes larger than a predetermined value, a stable ejection state cannot be obtained. Therefore, it is possible to switch the ink distribution table by detecting the remaining ink amount and detecting the state where stable ejection cannot be obtained, and prevent image deterioration due to an unstable ejection state.

FIG. 14 is a schematic exploded perspective view of an ink tank in which the efficiency of use of ink has been improved. The ink chamber 13a for the dark ink and the ink chamber 13b for the clear ink (the ink containing only the solvent not containing the dye) are used. Ink supply ports 15a and 15b are divided by the partition plate 13c in the tank.
The color density is adjusted by the area ratio of. Further, the dark ink ink chamber 13a and the clear ink ink chamber 13b are used as a negative pressure generating portion, and the negative pressure generating portion and an ink containing portion 13e partitioned by partition plates 13g and 13h having an opening 13i on the bottom surface. 13f is formed. When ink in the negative pressure generating members 14a and 14b is used and then ink starts to be supplied from the ink containing portions 13e and 13f, the ink supply pressure is maintained at a constant head pressure, so that more uniform adjustment of ink is performed. Is possible. Incidentally, 13d is an atmosphere communication hole.

According to this ink tank, the area ratio of the supply port area of the ink tank corresponding to each shade of the head is changed by the partition plate disposed in the tank, and the ink of each color and the clear ink are divided into two partitioned chambers. When the ink is injected and connected to the head, each ink corresponding to the area ratio of the supply port flows into the head and is mixed in the head to form a dark and light halftone ink.
When the clear ink runs out, low density ink is no longer ejected and a normal image cannot be obtained. Therefore, by detecting the remaining ink amount for the clear ink and switching the ink distribution table when the clear ink is exhausted, a normal image can be obtained until each color ink is used up. Also, here, it is assumed that each color ink and clear ink are injected into two chambers,
Ink of the same color with different densities may be used. In that case, the remaining ink amount is detected for both light and shade, and the ink distribution table is switched based on the result, so that a normal image is recorded in the ink tank. All ink can be used up.

The present invention brings excellent effects particularly in an ink jet type recording head and a recording apparatus for recording by forming flying droplets by utilizing thermal energy among the ink jet recording systems.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal converter arranged corresponding to the sheet or liquid path in which is stored, which corresponds to the recorded information and causes a rapid temperature rise exceeding nucleate boiling. , It is effective because it generates heat energy in the electrothermal converter and causes film boiling on the heat-acting surface of the recording head, resulting in the formation of bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis. Is. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications, A configuration using US Pat. No. 4,558,333 or US Pat. No. 4,459,600, which discloses a configuration in which the heat acting portion is arranged in the bending region, may be used. In addition, Japanese Unexamined Patent Application Publication No. Sho 5-5 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters.
Japanese Patent Application Laid-Open No. 9-123670 and Japanese Patent Application Laid-Open No. Sho 5 (1993) -58
A configuration based on Japanese Patent Publication No. 9-138461 may also be used.

Further, as a full line type recording head having a length corresponding to the maximum recording medium width that can be recorded by the recording apparatus, a combination of a plurality of recording heads as disclosed in the above-mentioned specification provides the length. Either of the structure satisfying the requirement or the structure as one recording head integrally formed may be used.

In addition, by being mounted on the apparatus main body, it can be electrically connected to the apparatus main body and can be supplied with ink from the apparatus main body by a replaceable chip type recording head or the recording head itself. Alternatively, a cartridge type recording head provided with an ink tank may be used.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. If you list these specifically,
Capping means, cleaning means, pressurizing or sucking means for the recording head, preheating means using an electrothermal converter or another heating element or a combination thereof, and a preliminary ejection mode for performing ejection other than recording It is also effective to perform stable recording.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrally formed or a plurality of combinations may be used. Alternatively, the device may be provided with at least one of full colors by color mixing.

In the embodiments of the present invention described above, the ink is described as a liquid, but it is an ink that solidifies at room temperature or lower and that softens at room temperature, or is a liquid, or the above-mentioned. In the inkjet method, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. It may be in a liquid form.

In addition, the temperature rise due to the thermal energy is positively prevented by using it as the energy for changing the state of the ink from the solid state to the liquid state, or the ink is solidified in a standing state for the purpose of preventing evaporation of the ink. In some cases, such as ink that is liquefied by applying heat energy according to a recording signal and ejected as a liquid ink, or one that has already started to solidify when it reaches a recording medium. The use of an ink having a property of being liquefied only by heat energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or JP-A-60-71260, a mode in which the porous sheet is opposed to the electrothermal converter in the state of being held as a liquid or solid in the recess or through hole of the porous sheet. May be In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as a form of the recording apparatus according to the present invention, the recording apparatus according to the present invention may be provided integrally or separately as an image output terminal of information processing equipment such as a word processor or a computer, or may be combined with a reader or the like. It may be in the form of a copying machine or a facsimile machine having a transmission / reception function.

[0074]

As described in detail above, according to the present invention,
When performing recording on a recording medium by ejecting ink from the ejection port of the recording head using a plurality of inks of the same color and different densities, stable ejection of at least one of the plurality of inks becomes difficult. In this case, since recording is performed using the remaining types of ink, a normal image can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a flow of image signal processing.

FIG. 2 shows C, M, Y and Bk concentration signals as Ck, Cu and M.
It is a figure which shows the sequence which selects the table allocated to the density signal of k, Mu, Yk, Yu, Bkk, and Bku.

FIG. 3 shows Ck, Cu, Mk, Mu, Yk, Yu, Bkk, and Bku density signals (input data) of C, M, Y, and Bk.
It is a figure which shows the some distribution table which converts the density signal (output data) of.

FIG. 4 is a diagram showing a main part configuration diagram of a conventional color ink jet recording apparatus of a serial print type using dark and light ink.

FIG. 5 is a diagram showing a perspective view showing a main configuration of a color ink jet recording apparatus according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a configuration of an inkjet unit used in this embodiment.

FIG. 7 is a groove unit 130 of the head unit used in this embodiment.
It is the perspective view which looked at 0 from the heater board 100 side.

FIG. 8 is a block diagram showing a configuration example of a control system of the apparatus.

FIG. 9 is a diagram showing the relationship between the remaining ink amount and the resistance value between the detection electrodes.

FIG. 10 is a diagram showing a state at the time of detecting an ink residual amount according to the first embodiment.

FIG. 11 is an explanatory diagram of remaining ink amount detection in the third embodiment.

FIG. 12 is an explanatory diagram of a modified example of the remaining ink amount detection in the third embodiment.

FIG. 13 is an explanatory diagram illustrating a change in internal pressure of the ink supply unit.

FIG. 14 is a configuration diagram of an ink tank that produces dark and light ink by mixing ink in the head.

FIG. 15 is a cross-sectional view of a state in which the dark ink cartridge and the light ink cartridge are connected.

[Explanation of symbols]

 4 Residual detection pin (electrode) 10 Recording head 200 Control unit 300 Voltage conversion circuit 400 Alarm device 500 Main scanning mechanism 600 Sub-scanning mechanism

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiromitsu Hirabayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hitoshi Sugimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Miyuki Matsubara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Toshio Kashino 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (6)

[Claims] 1. An inkjet recording method for recording on a recording medium by ejecting ink from an ejection port of a recording head using a plurality of inks of the same color and different in density, wherein at least one of the plurality of inks is used. An ink jet recording method, wherein recording is performed using the remaining type of ink when stable ejection of one type of ink becomes difficult. 2. The recording head is a recording head that ejects ink by using thermal energy, and is an inkjet recording head that includes a thermal energy converter for generating thermal energy applied to the ink. Item 1
Inkjet recording method described. 3. The recording head causes the ink to undergo a state change by the thermal energy applied by the thermal energy converter, and ejects the ink from the ejection port based on the state change. Inkjet recording method. 4. An ink jet recording apparatus for recording on a recording medium by ejecting ink from an ejection port of a recording head using a plurality of inks of the same color but different in density, the image being recorded according to an image signal. Distribution means for determining the degree to which each of the plurality of inks is used to form a pixel corresponding to a signal, and that stable ejection of at least one kind of ink among the plurality of inks becomes difficult Determining means for making a determination, and changing means for changing the degree determined by the allocating means in order to perform recording using an ink other than the ink for which stable ejection is difficult, based on the determination result of the determining means. An inkjet recording apparatus, comprising: 5. The recording head is a recording head that ejects ink by utilizing thermal energy, and is an inkjet recording head that includes a thermal energy converter for generating thermal energy applied to the ink. Item 4
The inkjet recording device described. 6. The recording head according to claim 5, wherein the thermal energy applied by the thermal energy converter causes a state change in the ink, and the ink is ejected from the ejection port based on the state change. Inkjet recording device.