JPH09300666A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording device of a compact, new constitution for using properly the black printing and the color printing. SOLUTION: The single color black printing and the color printing using yellow, magenta and cyan are used properly by fitting a black printing head 50B or a color printing head 50YMC and replacing one with the other on one carriage 60. In the color printing, black is provided by mixing yellow, magenta and cyan all together, and the pixel diameter on a body to be recorded formed by one drop of ink at the time of color printing is smaller than the pixel diameter at the time of ink color black printing. Paper feed cassettes 61 and 62 are provided so as to use them properly in compliance with the printing modes (black and color).

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 apparatus, and more particularly to a color printing method that separates black printing and color printing by detachably replacing a black printing head and a color printing head. The present invention relates to an inkjet recording device capable of recording.

[0002]

2. Description of the Related Art The non-impact recording method has been attracting attention for office use and the like because the noise generation during recording is extremely small to a negligible level. inside that,
High-speed recording is possible, and recording can be performed on plain paper without the need for special fixing processing.
The inkjet recording method is an extremely effective recording method, and various methods have been proposed, or have already been commercialized and put into practical use.

In such an ink jet recording method, recording is performed by ejecting small droplets (ink droplets) of a recording liquid, so-called ink, and attaching the ink droplets to a recording medium. For example, the applicant has disclosed it in Japanese Patent Publication No. 56-9429.
To summarize the invention disclosed in this Japanese Patent Publication No. 56-9429, heating the ink in the liquid chamber to generate bubbles causes a pressure rise in the ink, and this ink is applied to the fine nozzle tip. Recording is performed by ejecting from the ink ejection port.

The ink jet recording method has an advantage that color recording can be easily performed by using ink jet recording heads of a plurality of colors, and in recent years, a characteristic small color printer has been disclosed by taking advantage of this merit. As an example, for example, one of the color printers under the trade name of Deskjet sold by Hewlett-Packard Company in the US is a black ink (B) head cartridge for monochrome printing, a yellow (Y), and a magenta. There is a type in which a head cartridge for color printing, in which three colors (M) and cyan (C) are integrated, is selectively used according to the application. this is,
A black ink (B) head cartridge is used for monochrome printing like a text document, and a black ink (B) head cartridge on the carriage is used for color printing like a color image document. Instead, the head cartridge for color printing is placed and printing is performed instead.

However, such a printer capable of easily performing monochrome printing / color printing has been positioned for low-end users, and it has not always been possible to realize high-quality recording. Specifically, there is no problem in monochrome printing, but in color printing, the color is dull, bleeding, or gradation recording is not possible, so only a low-quality image with graininess can be obtained. I have.

On the other hand, the inventions disclosed in JP-A-5-261941 and JP-A-5-293977 are known. In these inventions, black (B) is used when printing is performed using four color ink jet heads of black (B), yellow (Y), magenta (M), and cyan (C).
The pixel is designed to be large. Further, an example of performing gradation recording is also disclosed. However, in these inventions, monochrome (black) printing is
Since the black ink for exclusive use is used, black is not obtained by the color mixture of yellow (Y), magenta (M), and cyan (C). Therefore, no problem has been recognized from the viewpoint of image bleeding due to color mixture. The printers disclosed in these inventions are so-called full-scale color printers that use four color inkjet heads of black (B), yellow (Y), magenta (M), and cyan (C). Unlike a printer capable of monochrome printing / color printing by exchanging the head cartridge like this, the printer tended to be large.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art.
Another object is to propose a compact and novel inkjet recording apparatus that selectively uses black printing and color printing. More specifically, clarify the relationship between the pixel diameters of black and color. To clarify the relationship between the mass of black and color ink droplets in such a color ink jet recording apparatus, and thirdly, to the pixel on the recording medium formed by such a color ink jet recording device. Clarifying the resolution, fourth, improving the image quality formed by such a color inkjet recording apparatus, fifth, improving the operability of such a color inkjet recording apparatus, and sixth.
Another object of the present invention is to propose an inkjet recording apparatus having a novel structure for performing color gradation recording.

[0008]

According to a first aspect of the present invention, a black print head and a color print head are detachably mounted and replaced on a single carriage, so that a single color black print, yellow, and magenta are printed. In an ink jet recording apparatus that distinguishes between color printing with cyan and color printing, in the color printing, black is obtained by mixing yellow, magenta, and cyan, and a pixel on a recording medium is recorded by one drop of ink during color printing. The diameter is made smaller than that at the time of the black printing of the single color.

According to the second aspect of the present invention, the black print head and the color print head are detachably mounted and replaced on one carriage, whereby a black print of a single color and a color print of yellow, magenta, and cyan are printed. In an ink jet recording apparatus that uses different colors, black is obtained by a mixed color of yellow, magenta, and cyan in the color printing, and the mass of one drop of ink in color printing is the same as that in black printing of the single color. It is designed to be smaller than that.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the resolution of the pixels on the recording medium is the same when the single color black is printed and when the color is printed. .

[0011] The invention of claim 4 is the invention of claim 1 or 2 or 3.
In the invention, at least one of the color printing heads
The color nozzle group is formed at a position displaced from the nozzle group of another color by a distance that is a natural multiple of the distance between the nozzle centers.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the ink jet recording apparatus is
A plurality of recording medium supply means are provided.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, at the time of the color printing, one to a plurality of drops of ink are applied to almost the same location on the recording medium according to image information. The pixel diameter is made variable by driving.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION First, FIGS.
The principle of ink ejection will be described with reference to (e). Although the thermal inkjet method using heat is described here, ink is ejected in a drop-on-demand method using another piezo, or in a direction that is not perpendicular to the surface of the heating element (for example, a direction that is substantially parallel). It goes without saying that the present invention is also applied to the thermal ink jet system in which the present invention is applied.

1 (a) to 1 (e) are sectional views showing the vicinity of an ink ejection port in the thermal ink jet system, in which 10 is ink, 11 is a heating element, and FIG.
12 is a bubble, 13 is an ink column, and 14 is an ejected ink droplet. FIG. 1A shows a steady state, where the surface tension of the ink 10 and the external pressure are in equilibrium at the ink ejection port.
In FIG. 1B, the heating element 11 is heated and the surface temperature of the heating element 11 rapidly rises, causing a film boiling phenomenon in the adjacent ink layer.
The boiling film is formed, and the bubbles 12 are in a grown state. At this time, the pressure at the discharge port rises by the amount of bubbles that have grown,
The balance with the external pressure is lost, and the ink column 13 begins to grow from the ejection port. FIG. 1C shows a state in which the bubble 12 has grown to the maximum, and the ink column 13 is pushed out from the ejection port portion. At this time, no current is flowing in the heating element 11, and the surface temperature of the heating element 11 is decreasing. Bubbles 1
The maximum value of the volume of 2 is slightly delayed from the timing of electric pulse application.

FIG. 1 (d) shows a state in which the bubbles 12 are stored after being cooled by ink or the like. At the front end of the ink column 13, the ink column moves forward while keeping the pushing speed, and at the rear end, the ink flows backward due to the decrease of the discharge port inner pressure due to the contraction of the bubble 12, and the base of the ink column 13 becomes constricted, and then the constriction occurs. The ink droplets 14 are cut off from the parts and fly into the air. At the discharge port, the external pressure is higher than the internal pressure of the discharge port, so that a large meniscus enters the discharge port. The tip of the ink droplet 14 has a velocity of 10 to 18 m / s and flies toward the recording paper. In FIG. 1E, the ink is supplied (refilled) to the ejection port portion again by the capillary phenomenon, and the bubbles completely disappear in the process of returning to the state of FIG. 1A.

2A and 2B are views for explaining an example of a black (B) ink jet head unit to which the present invention is applied. FIG. 2A is an overall perspective view and FIG. 2B is an exploded perspective view. is there. This head unit 20 is 20 μm
A head chip 21 having nozzles for ejecting fine ink of ˜50 μm and an ink container portion 24 for supplying ink to the head chip 21 are integrally formed. The head chip 21 is connected to an FPC (flexible printed circuit) 22, and an electric contact provided on the FPC is brought into contact with a contact (not shown) on the carriage side,
An electric signal is received from the printer body side, and ink is ejected to perform recording. Reference numeral 25 is a back cover, 26 is an ink absorber, and the ink absorber 26 is a sponge impregnated with ink. Even if the carriage moves and vibrates, bubbles are generated in the ink inside the container. It has a structure that does not happen. When the ink impregnated in the ink absorber 26 is used up, the entire head unit is replaced.

FIG. 3 shows a head unit as shown in FIG. 2 in which the head portion 23 and the ink container portion 24 are separable. FIG. 3 (a) is an overall perspective view and FIG. 3 (b) is an exploded view. In a perspective view, in this case, the head portion 23 and the ink container portion 2
Since it is separable from No. 4 through the elastic member 24a, when the ink is used up, only the ink container portion 24 needs to be replaced, and the running cost can be reduced.
Of course, when the head portion 23 and the ink container portion 24 are connected to each other (FIG. 3A), the operability is as shown in FIG. Is the same as

FIG. 4 shows an example in which a head unit capable of ejecting a plurality of colors of ink (three colors of yellow (Y), magenta (M), and cyan (C) in this example) is formed integrally with the ink container portion. 4 (a) is an overall perspective view, FIG.
(B) is an exploded perspective view, in which 30 is a head unit,
31 is a head chip, 32 is a printed circuit, 33
Is an upper lid, 34 is a cartridge, 35 (35Y, 35M,
35C) is a filter, 36 (36Y, 36M, 36C)
Is an ink container, 37 is a bottom cover, and 38 is a cap. In this example, in the ink container integrated head unit as shown in FIG. 2 (in this case, black (B) single color), the head part and the ink communicating with it The container is internally divided into three parts, and the Y, M, and C inks are separately filled. In this way, the head unit that integrates multiple colors can be made very compact, so when mounted on a carriage it is lightweight and compact, so a small carriage is all that is needed, and the motor that drives the carriage is also compact. Energy saving can be realized.

FIG. 5 is a diagram for explaining an example in which the ink container integrated head unit for a plurality of colors shown in FIG. 4 has a structure in which only the ink container portion is separable, and FIG. Is an overall perspective view of the head unit 40, FIG.
FIG. 3B is a perspective view of the head unit 40 with the recording head portion 41 and the ink container portion 42 separated. As a result, even if a large amount of ink is consumed by printing a color image, only the ink container portion 42 needs to be replaced, so that cost reduction is realized. Moreover, the advantages of the color integrated head described with reference to FIG. 4 are maintained.

FIG. 6 is a diagram for explaining an example in which the ink container portion can be separated for each color of ink in the above-described integrated head unit, and FIG. 6A is an overall perspective view. 6B, the recording head portion 41 of the head unit 40 and the ink container portions 42 (42Y, 42M,
42C) is a perspective view showing a state of being separated. FIG. The merit of doing this is that the Y, M, and C inks are not always consumed at the same speed in color image printing, so if any of the inks in the examples of FIGS. Even if other ink remains when the ink runs out,
The head unit or the entire ink container must be replaced, which is disadvantageous in terms of running cost.By keeping the ink containers for each color separate, only the ink containers that are lost By replacing the, the running cost can be further reduced.

FIG. 7 is a view for explaining a concrete example of the ink jet recording apparatus of the present invention and its usage.
In the inkjet recording apparatus of the present invention, as shown in FIG. 7A, the head unit 50 to the carriage 60 of the inkjet recording apparatus is a black (B) inkjet head unit 50B shown in FIG. 7
The color (Y, M, C) inkjet head unit 50YMC shown in FIG. Further, the head units 50B and 50YMC have substantially similar outer shapes, and the electrical contact portion receives power from the printer body side in the same manner even when the head units 50B and 50YMC are replaced. As described above, the contact portions have the same shape. In the present invention, the black (B) inkjet head unit 50B (FIGS. 2 and 3) as described above and the colors (Y, M, and
C) Inkjet head unit 50YMC (Fig. 4,
5 and 6) are exchanged and used according to the intended use (printing of black characters, printing of color image).

According to the present invention, the head unit 50 is
Black and white (Y), magenta (M), and cyan (C) are used because the inkjet printer can be used by exchanging the B and 50YMC for monochrome printing and color printing as needed. ) Compared to a so-called full-scale color inkjet printer that has a head unit for each ink, it does not take up much space to install a head unit, which has the advantage that the entire printer can be made compact and compact. .

In the ink jet printer having such a structure, in the present invention, the pixel diameter on the recording medium by one drop of ink at the time of color printing is made smaller than that at the time of black printing of a single color. . Specifically, for example, the pixel diameter on the paper surface formed by the color (Y, M, C) inkjet head unit 50YMC is
The size is about 40 to 80% of the pixel diameter formed by the black (B) inkjet head unit 50B.

Further, in order to obtain such a pixel diameter, the mass of one ink drop at the time of color printing is made smaller than that at the time of black printing. Specifically, for example, the mass of ink ejected by the color (Y, M, C) inkjet head unit 50YMC is about 10 to 50% of the mass ejected by the black (B) inkjet head unit 50B. I am trying.

The pixel diameter or the mass of the ejected ink as described above is determined by the nozzle diameter of each ink jet head unit, the size of the energy acting portion such as the heating element or the piezo element, or the driving applied to the energy acting portion. It can be obtained by changing energy (voltage, application time, etc.). That is, color (Y, M,
C) The nozzle diameter of the inkjet head unit 50YMC, the size of the energy acting portion, or the driving energy to be input can be realized by making them smaller than those of the black (B) inkjet head unit 50B.

In the present invention, when a monochrome character document is operated, the black (B) ink jet head unit 50B is mounted on the carriage of the printer for printing. On the other hand, when creating a color (image) document,
The black (B) inkjet head unit 50
B is removed from the carriage, a color (Y, M, C) inkjet head unit 50YMC is mounted and printing is performed. During color printing, various colors are output by combining the inks of yellow (Y), magenta (M), and cyan (C). Needless to say, in this color (image) document, a black image (including characters)
When required, a combination of three color inks of yellow (Y), magenta (M) and cyan (C) is used for output.

In the present invention, since the pixel diameter on the recording medium or the mass of the ejected ink by one drop of ink at the time of color printing is made small as described above,
For example, one pixel (1 pixel) in color printing is
It is formed by ink droplets of Y, M, C, Y & M, C & M, Y & C, Y & M & C, that is, the number of pixels (or the number of ink droplets) in one picture element (1 pixel) is 1 to 3. However, compared to the conventional pixel diameter or the mass of the ejected ink that is equivalent to that of the black ink, ink of each color is mixed and the color is not turbid, and the image quality is not deteriorated. Since the ink has a small amount of water, it can be dried quickly.

The black (B) ink jet head unit 50B and the color (Y, M, C) ink jet head unit 50YM to which the present invention is applied.
C has different pixel diameters output by the respective head units (yellow (Y), magenta (M), cyan (C)).
Each pixel is smaller than the black (B) pixel), but the printing density (resolution) on the paper surface is the same. In the ink jet printer of the present invention, each head unit is exchanged for use, but the printer main body (carriage part other than the head unit and its control unit, paper transport mechanism and its control unit, control unit such as ink ejection timing) , Etc. are shared, so by making the printing density (resolution) the same, you can replace the head unit with almost no change to each control on the printer body side and you can change the black (monochrome) / color This is to make printing easy.

Next, another feature of the present invention will be described. In the present invention, as described above, one picture element (one pixel) at the time of color printing is, for example, Y, M, C, Y & M,
Since it is formed by ink droplets of C & M, Y & C, and Y & M & C (Y, M, and C represent, for example, yellow, magenta, and cyan colors), one picture element (1 pixel) = 1 to a plurality of (here, 3) pixels ( 1 to a plurality of dots). At this time, one pixel (1 pixel) is a color mixture of each pixel, and one pixel or more pixels are imprinted in one pixel to produce various colors. In order to reduce bleeding due to color mixing, the pixels of each color are prevented from being imprinted at positions where they completely overlap. Specifically, in the arrangement of the Y, M, and C nozzle groups of the color (Y, M, C) inkjet head unit as shown in FIG. 4, at least one color nozzle group is a nozzle group of another color. Is formed at a position displaced from a distance that is a natural multiple of the distance between the nozzle centers.

FIG. 8 is an enlarged view showing the relationship between the Y, M, and C nozzle rows. In the illustrated example, the number of nozzles for each color is
Although each has eight nozzles, the present invention is not limited to this number of nozzles. Further, although each nozzle row has a one-row arrangement, it is not limited to such an arrangement, and may have a staggered arrangement in order to increase the final printing density. good. Here, in order to simplify the explanation, an example of such a one-column array for each color is taken.

In FIG. 8, DYV, DMV, DCV
Indicates the distance between the centers of the adjacent nozzles of each color, and DYV = DMV = DCV, which means the distance between the centers of the adjacent pixels on the final recording medium (which means the resolution). ) Is equal to or a natural multiple of it. On the other hand, LV (YM) and LV (YC) indicate the center-to-center distances between the nozzle rows in the vertical direction, and LH (YM) and LH (CM) indicate the distances between the nozzle line center lines in the horizontal direction. Shows the distance. In the present invention, where L
V (YM) or LV (YC) is converted to DYV (= DM
V = DCV) does not match a natural number times (a nozzle group is formed at a position further displaced from a nozzle group of another color by a natural number times the distance between nozzle centers). Exist). By doing so, the pixels on the recording medium are not imprinted on the same position completely, but are imprinted on a slightly deviated position, and when the various colors are mixed with each pixel, the overlap does not occur. It is less likely that ink will be mixed with the ink to cause bleeding and the image quality will not be deteriorated. Needless to say, even if the pixels of each color are not typed in exactly the same place, if they are typed in close proximity, they will appear to the human eye as if they were typed in the same place. It appears as a pixel.

On the other hand, the distances LH (YM) and LH (CM) between the nozzle line center lines in the horizontal direction are also DYV (= DM).
It does not match a natural number times V = DCV).
Note that here, LV (YM), LV (YC), or LH (YM), LH (CM) are changed to color (Y, M,
C) In the arrangement of the Y, M, and C nozzle groups of the inkjet head unit, a nozzle group of a certain color is displaced from a nozzle group of another color by a distance that is a natural multiple of the nozzle center distance. The pixels are formed so as not to completely match when printed, but as a means for printing such that each pixel after printing does not completely match, It is not always necessary to solve the problem only by arranging the nozzle groups.

For example, depending on the placement of the ink jet head unit or the respective feeding directions of the carriage and the recording medium, the vertical direction (LV (YM),
LV (YC)), horizontal direction (LH (YM), LH (C
Although it cannot be said that M)), it is also possible to prevent each pixel from completely matching by shifting the ink ejection timing. In other words, as a practical problem, since the arrangement of the nozzle groups and the shift of the ink ejection timing are both realized, it is not necessary to realize the arrangement of the nozzle groups so that the pixels do not overlap.

FIG. 9 is a diagram for explaining another example in which the pixels do not overlap each other. In FIG. 9, LH (YM),
Although the nozzle group is arranged such that LH (CM) is a natural number multiple of DYV (= DMV = DCV) (not in the embodiment of FIG. 8), the ink ejection timing of M is It is possible to shift the M pixel from the Y or C ink ejection timing so that it does not completely coincide with the Y or C pixel. That is, the gist of the present invention is to form the nozzle groups of at least one color at positions displaced from the nozzle groups of other colors by a distance that is a natural multiple of the distance between the nozzle centers.

Next, another feature of the present invention will be described. FIG. 7 shows a specific example of the ink jet recording apparatus of the present invention. In the present invention, by attaching and detaching such a black printing head and a color printing head, it is possible to easily perform monochrome printing / color printing. In a printer capable of printing, a plurality of paper feed cassettes (two in this example) are provided, and a recording medium suitable for each printing mode is put in the paper feed cassette, and the paper feed cassette is set in accordance with the mode. The recording medium is used properly. Conventionally, such a simple printer has only one paper feed cassette,
In order to use it properly, the user manually performs a troublesome work such as inserting a recording medium or replacing all the recording mediums in the recording medium supplying means.

However, in the present invention, as shown in FIG. 7, in the printer capable of such monochrome printing / color printing, since a plurality of recording medium supplying means are provided, the black printing is performed. For recording and color printing, a recording medium suitable for each is put in a recording medium supply means such as a paper feed cassette, and the recording medium can be used properly according to the printing mode. Therefore, the optimum recording medium can be used for each mode,
Satisfactory printing results have come to be obtained in terms of cost and image quality. Further, it is no longer necessary to perform the troublesome manual insertion work of the recording medium or the total replacement work of the recording medium for each printing, and the operability can be greatly improved.

Next, another feature of the present invention will be described. In the present invention, the mass of one drop of the color ink is reduced, and the pixel diameter is changed according to the image information by changing the number of a plurality of drops to be ejected at the same location, thereby performing gradation recording. The principle is shown in FIG. Here, a method of forming one pixel with a plurality of ink droplets is shown, and by changing the number of drive pulses continuously input to the heating element,
It is shown that the number of ink droplets 71 forming one pixel 70 is changed and the size of the pixel 70 formed thereby is changed.

In FIG. 10A, one driving pulse is input to the heating element, and one ink droplet 71 is ejected from the nozzle so that one ink droplet 71 is ejected onto the recording medium. One pixel 70 is formed by being attached. FIG.
In (b), three drive pulses are input to the heating element, and three ink droplets 71 are ejected from the nozzle,
One pixel 70 is formed by hitting three ink droplets 71 at the same position on the recording medium.
In FIG. 10C, five driving pulses are input to the heating element, five ink droplets 71 are ejected from the nozzle, and the five ink droplets 71 are delivered to the same location on the recording medium. One pixel 70 is formed by being driven. In FIG. 10D, eight driving pulses are input to the heating element, and eight ink droplets 71 are ejected from the nozzle.
Is ejected, and eight ink droplets 71 are ejected to the same position on the recording medium to form one pixel 70.

It should be noted that the ink droplet 7 that is ejected at the same location
As the number of 1's increases, the pixels 70 to be formed become larger. In addition, in this figure, the flying ink droplet is drawn as one elongated droplet, but depending on the case (difference in the physical properties of the ink, etc.), the ink droplet may fly while separating into two or three. , In that case also, consider it as one drop. Further, the driving conditions are selected such that the longer the elongated droplet, the faster the flying speed and the stable flying, and the length is usually three times or more the diameter of the ink droplet (pillar). At that time, a flight speed of 10 m / s or more is obtained.

According to the present invention, the black print head and the color print head are detachably mounted on the single carriage, so that the black print of a single color and the color prints of yellow, magenta, and cyan are printed. Even in a printer capable of simple monochrome printing / color printing which is performed by separately using copying, very high quality color gradation recording can be obtained by the method of realizing such gradation recording. It became so.

Example 1 A black (B) inkjet head unit 50B as shown in FIG. 7C,
The color (Y, M, C) inkjet unit 50YMC as shown in FIG. 7B is detachable and replaceable.
An inkjet printer as shown in (a) was prepared. As shown in 61 and 62 in FIG. 7A, two paper feed cassettes are provided, and a matte coated paper NM made by Mitsubishi Paper Mill and a PPC paper 6200 made by Ricoh are put in the paper feed cassettes, respectively, and a printing mode is set. It is designed to be used properly according to.

The black (B) ink jet head unit 50B has the following specifications. Nozzle diameter: φ35 μm Nozzle array density: 127 μm pitch (one row array) Number of nozzles: 60 Heating element size: 50 μm × 50 μm Heating element resistance value: 82 Ω Driving pulse voltage: 23.5 V Driving pulse width: 5 μs Driving frequency: 10 kHz On paper Printing density: 400dpi (nozzle array density is 20
It is equivalent to 0dpi, but 400dpi by controlling the paper feed, carriage feed, and ejection timing.
Pixel diameter on paper: Approx. Φ94.5 μm (average value of 10 pieces on matte coated paper NM (manufactured by Mitsubishi Paper Mills)) Approximately φ90.3
μm (10 average values on Ricoh PPC paper 6200) 1 drop ink mass: 9.1215 × 10 ⁻⁸ g Ink composition: Glycerin ... 18.0%, Ethyl alcohol ... 4.8%, Water ... 75 0.0%, Dye (Direct Black 154) ... 2.2%

The color (Y, M, C) ink jet head unit 50YMC has the following specifications. The following values are the same for Y, M, and C. Nozzle diameter: φ28 μm Nozzle array density: 127 μm pitch (one-row array) Number of nozzles: 20 × 3 colors (Y, M, C) Nozzle array method: LV (YM), LV (YC) in FIG.
Of the nozzle array density (127 μm pitch) multiplied by a natural number plus 31.75 μm. Specifically, LV
(YM) = 2571.75 μm LV (YC) = 5143.5 μm. Heating element size: 45 μm × 45 μm Heating element resistance value: 80 Ω Driving pulse voltage: 22 V Driving pulse width: 4 μs Driving frequency: 10 kHz Printing density on paper: 400 dpi (nozzle array density is 20
It is equivalent to 0dpi, but 400dpi by controlling the paper feed, carriage feed, and ejection timing.
Pixel diameter on paper surface: Approx. Φ71.3 μm (average value of 10 pieces on matte coated paper NM (manufactured by Mitsubishi Paper Mills, actually measured with magenta ink)) Mass of one drop of ink: 4.5113 × 10 ^{− 8} g (actual measured value of magenta ink) Ink composition Y: glycerin ... 18.0%, ethyl alcohol ... 4.9%, water ... 75.0%, dye (acid yellow 17) ... 2.1% Ink composition M: Glycerin ... 18.0%, ethyl alcohol ... 4.7%, water ... 75.0%, dye (Acid Red 35) ... 2.3% Ink composition C: glycerin ... 18.0%, ethyl alcohol ... 4.8 %, Water ... 75.0%, dye (Acid Blue 29) ... 2.2%

An image of 400 dpi was printed with such a printer. Monochrome printing with the black (B) inkjet head unit is performed by Ricoh PPC paper 62
Using 00, an image quality with practically no problem was obtained. Needless to say, the printing density is 400 dpi. After that, the color (Y, M, C) ink-jet head unit was replaced, and a color image was printed on the matte coated paper NM (manufactured by Mitsubishi Paper Mills). Each pixel was very high with almost no blurring. A quality image was obtained.

<Embodiment 2> The black (B) ink jet head unit and the printer device are the same as those in Embodiment 1.
The same as the above, the color (Y, M, C) inkjet head unit was manufactured with the specifications changed as follows. The carriage speed of the printer is changed for this new color (Y, M, C) inkjet unit. Nozzle diameter: φ19 μm Nozzle array density: 127 μm pitch (one row array) Nozzle number: 20 × 3 colors (Y, M, C) Nozzle array method: LV (YM), LV (YC) in FIG.
Of the nozzle array density (127 μm pitch) multiplied by a natural number plus 31.75 μm. Specifically, LV
(YM) = 2571.75 μm LV (YC) = 5143.5 μm. Heating element size: 30 μm × 30 μm Heating element resistance value: 73Ω Driving pulse voltage: 20 V Driving pulse width: 3 μs Driving frequency: 20 kHz Printing density on paper: 400 dpi (nozzle array density is 20
It is equivalent to 0dpi, but 400dpi by controlling the paper feed, carriage feed, and ejection timing.
Pixel diameter on paper: Approx. Φ42.1 μm (printing with one drop) Approx. Φ61.5 μm (printing with double-drop printing) Approximately φ74.1 μm (printing with triple-drop printing) Approximately φ83.6 μm (printing with double-drop printing) 4 drops overprinted) Approx. 91.1 μm (5 drops overprinted) (Each pixel diameter is an average value of 10 on matte coated paper NM (manufactured by Mitsubishi Paper Mills, measured with magenta ink)) Pixel formation frequency : Ink mass of 1 drop at 4 kHz: 1.0071 × 10 ^-8 g (actual measured value of magenta ink) Ink composition Y: glycerin ... 18.0%, ethyl alcohol ... 4.9%, water ... 75.0%, dye (Acid Yellow 17) ... 2.1% Ink Composition M: Glycerin ... 18.0%, Ethyl Alcohol ... 4.7%, Water ... 75.0%, Dye (Acid Red 35) ... 2.3% Ink Composition C : Glycerin ... 18.0%, Ethyl alcohol ... 4.8%, Water ... 75.0 %, Dye (Acid Blue 29) ... 2.2%

With such a color (Y, M, C) ink jet head unit, a pixel diameter by multiple printing according to image density information at a printing density of 400 dpi on matte coated paper NM (manufactured by Mitsubishi Paper Mills). When color image printing was performed with variable printing (gradation recording), an excellent image was obtained, which was as good as silver halide photography.

[0048]

The effect corresponding to claim 1: In the present invention,
By attaching and detaching the black print head and the color print head on one carriage, the black print of a single color and the color print of yellow, magenta, and cyan can be selectively used. Now, it has become an ink jet recording device that is capable of color recording that is smaller and more compact than ever before.

Further, one picture element (one pixel) at the time of color printing is, for example, Y, M, C, Y & M, C & M, Y &
Since it is formed by the ink droplets of M, Y & M & C, one pixel (1 pixel) = 1 to a plurality (here, 3) pixels (1 to a plurality of dots). On the other hand, when black printing is performed by the black printing head as in the present invention, one pixel (1 pixel) = 1 pixel (1 dot). Therefore, generally, in color printing, 1 to 1 pixel (1 pixel) area
Ink for multiple pixels (1 to multiple dots) is applied,
There is a problem in that the inks of the respective colors are mixed and the colors become cloudy, and the amount of water in the ink is large, so that it is difficult to dry.

In the present invention, the pixel diameter (dot diameter) on the recording medium by one drop of ink at the time of color printing is made smaller than that at the time of black printing of a single color, so that one pixel (1 pixel) Even if a color ink of = 1 to a plurality of pixels (1 to a plurality of dots) is applied to the area), such a defect is reduced and high quality color recording is realized.

Effect corresponding to claim 2: In the present invention, the mass of one drop of ink at the time of color printing is made smaller than that at the time of black printing of a single color, so that one pixel (1 pixel) area = 1 to more than one color ink drop, causing a significant decrease in image quality due to the mixing of inks of each color, and reducing the problems such as difficulty in drying due to the large amount of water in the ink, high-quality color recording , Quick drying was realized.

Effect corresponding to claim 3: In the present invention, the resolution of the pixels on the recording medium is the same for black printing of a single color and for color printing. Even if the black print of a single color and the color prints of yellow, magenta, and cyan are used properly, the recording medium is conveyed, the scanning speed of the carriage, or the print timing of the black print and the color print (ink droplet ejection) Control of timing and the like is not complicated, and the cost of the entire inkjet recording apparatus can be reduced.

Effect corresponding to claim 4: In the present invention, the pixel diameter (dot diameter) on the recording medium by one drop of ink or the mass of one drop of ink at the time of color printing is determined by black printing of a single color. In addition to making them smaller than those at the time, not only the remarkable deterioration of the image quality due to the mixing of the inks of the respective colors is reduced, but also the nozzle group of at least one color of the color printing head is different from the nozzle groups of other colors and the nozzle center. By forming them at positions shifted from a distance that is a natural multiple of the distance between them, it is possible to prevent the printing positions from overlapping when printing on the recording medium. Almost no deterioration occurred, and excellent high-quality color record was obtained.

Effect corresponding to claim 5: Conventionally, in such a printer capable of easily performing monochrome printing / color printing, there is only one recording medium supplying means such as a paper feeding cassette, and Only one type of recording material could be used.
Therefore, the recording material used for monochrome printing is not necessarily suitable for color printing in terms of image quality.
On the contrary, it is not suitable for color printing, and when the optimum recording medium is used, the user must insert the recording medium manually or supply the recording medium every time. There was a lot of troublesome work such as replacing all the recording media in the means. However, in the present invention, such a printer capable of monochrome printing / color printing has a plurality of recording medium supply means, and therefore, black printing and color printing are suitable for each. The recording medium is put in a recording medium supply means such as a paper feed cassette, and the recording medium can be selectively used according to the printing mode.
It has become possible to perform printing with an optimum recording medium without performing the troublesome manual insertion work of the recording medium or the total replacement work of the recording medium.

Effect corresponding to claim 6: In the present invention, 1
By attaching and detaching the black print head and the color print head on one carriage, the black print of a single color and the color prints of yellow, magenta, and cyan can be used separately. It has become an inkjet recording device that is capable of color recording that is smaller and more compact than ever before. Furthermore, the mass of one drop of color ink is reduced, and the pixel diameter is changed according to the image information by changing the number of drops to be ejected at the same location.
Gradation recording has been realized, and the problem that it is difficult to dry due to the large amount of water in the ink has been reduced, and performance that could not be obtained with ink jet recording devices that are also capable of color recording of this type in the past. That is, high-quality color gradation recording and fast drying are realized at the same time.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part for explaining an operation principle of ink ejection.

FIG. 2 is a schematic configuration diagram for explaining an example of a black inkjet head used for implementing the present invention.

FIG. 3 is a schematic configuration diagram for explaining another example of the black inkjet head used for implementing the present invention.

FIG. 4 is a schematic configuration diagram for explaining an example of a color inkjet head used for implementing the present invention.

FIG. 5 is a schematic configuration diagram for explaining another example of the color inkjet head used for implementing the present invention.

FIG. 6 is a schematic configuration diagram for explaining still another example of the color inkjet head used for implementing the present invention.

FIG. 7 is a schematic configuration diagram for explaining an inkjet recording apparatus and a method of using the same according to the present invention.

FIG. 8 is a diagram illustrating an example of a relationship between nozzle rows of a color inkjet head.

FIG. 9 is a diagram for explaining another example of the relationship of the nozzle rows of the color inkjet head.

FIG. 10 is a diagram illustrating an ink droplet ejecting method according to the present invention.

[Explanation of symbols]

10 ... Ink, 11 ... Heating element, 12 ... Bubble, 13 ... Ink column, 14 ... Ink drop, 20 ... Head unit, 21 ...
Head chip, 22 ... FPC, 23 ... Head part, 24 ...
Ink container part, 25 ... Back cover, 26 ... Ink absorber, 30
... head unit, 31 ... head chip, 32 ... printed circuit, 33 ... upper lid, 34 ... cartridge, 35
... filter, 36 ... ink container, 37 ... bottom lid, 38 ... cap, 40 ... head unit, 41 ... recording head section,
42 ... Ink container part, 50 ... Head unit, 50B ...
Inkjet unit for black, 50YMC ... Inkjet head unit for color, 60 ... Carriage, 61, 62 ... Paper feed cassette, 70 ... Pixel, 71 ... Ink drop.

Claims (6)

[Claims] 1. A single color black print and a yellow, magenta, or cyan color print can be used by attaching and detaching a black print head and a color print head on one carriage. In an inkjet recording apparatus, black is obtained by a color mixture of yellow, magenta, and cyan in the color printing, and the pixel diameter on the recording medium by one drop of ink at the time of color printing is the black color of the single color. An inkjet recording device characterized by being smaller than the pixel diameter at the time of image capturing. 2. A single color black print and a yellow, magenta, or cyan color print can be used by detaching and replacing the black print head and the color print head on one carriage. In the inkjet recording apparatus, in the color printing, black is obtained by mixing yellow, magenta, and cyan, and the mass of one drop of ink at the time of color printing is smaller than the mass at the time of black printing of the single color. An inkjet recording device characterized by being small. 3. The ink jet recording apparatus according to claim 1, wherein the resolution of the pixel on the recording medium is the same during black printing of the single color and during color printing. 4. The nozzle group of at least one color of the color printing head is formed at a position displaced from a nozzle group of another color by a distance that is a natural multiple of the distance between nozzle centers. The ink jet recording apparatus according to claim 1, 2 or 3, characterized in that. 5. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus has a plurality of recording medium supply units. 6. The pixel diameter is variable by ejecting one or more drops of ink at substantially the same location on a recording medium according to image information during the color printing. 6. The inkjet recording device according to any one of 5 to 5.