JP3018474B2 - Inkjet recording method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording method capable of obtaining a high-quality print regardless of paper.

(Prior Art) The ink jet recording method has been widely used as a black and white recording method for personal computers and word processors because of its low noise, low running cost, and adoption of ink suitable for plain paper in black and white printing. Further, since it is easy to arrange the nozzles at a high density, it can be said that the recording method is suitable for colorization.

FIG. 6 is a schematic configuration diagram of a head portion of a conventional color ink jet printer. In the figure, 1b, 1c, 1m, and 1y are black, cyan, magenta, and yellow heads, 2 is a carriage plate, 3 is a carriage rail, 13 is a head holder, 14 is a maintenance station, and 15 is a cap for the head. . Color printing is performed using four color heads 1b, 1c, 1m, and 1y filled with black, cyan, magenta, and yellow inks, respectively, and character printing is performed using the black head 1b. When printing on plain paper used in copiers and the like with these heads, it was not possible to print both color images and monochrome characters with high image quality. The reason is due to ink.
When overprinting, using quick-drying ink with little bleeding gives high quality in color images, but printing monochrome characters causes bleeding along the paper fibers and degrades image quality . Conversely, using high-quality ink with less bleeding along the fiber of the paper provides high-quality images for monochrome characters, but because of slow drying, bleeding occurs when printing overlaid color images. And the image quality deteriorates.

Also, when printing a character in black with cyan, magenta, and yellow as the background, the time from printing cyan, magenta, and yellow to printing black is very short, so before the background is sufficiently dried. Will print a character on
There is also a problem that bleeding (inter color printing) occurs.

That is, when printing on plain paper, obtaining sharp and high-density image quality without feathering and obtaining a sharp image with no bleeding between colors in color printing are contradictory as ink properties. That is, both could not be satisfied with the same ink. For this reason, color ink jet printers usually perform printing using special paper.

Therefore, a four-color ink set that satisfies the three items of: printing high-quality characters on plain paper, printing high-quality color on special paper, and printing images with no image quality defects on plain paper. Although development of paper and paper have been carried out, they have not been achieved due to the above-mentioned circumstances.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned problems, and a color ink jet recording method which satisfies all of the above three items of image quality and has improved printing stability. It is intended to provide.

(Means for Solving the Problems) The invention according to claim 1 is a black printing head having a plurality of nozzles for performing printing by discharging ink from minute nozzles, and a plurality of heads each having a plurality of nozzles. In an ink jet recording method in which a head for color printing is used and the heads are simultaneously scanned in the main scanning direction to perform overlap printing, the plurality of heads for color printing are configured such that each of the plurality of nozzles has the main scanning direction. Are arranged so as to be orthogonal to the direction, and are arranged in a direction perpendicular to the sub-scanning direction, and the head for black printing is arranged such that a plurality of nozzles are arranged in a direction orthogonal to the main scanning direction. And the plurality of color printing heads are arranged downstream in the sub-scanning direction with respect to the plurality of color printing heads, and the plurality of color printing heads are arranged in the same printing area. Printing by the head is always performed in the same scan in one direction, scanning for printing in the same printing area by the black printing head is delayed from scanning for printing by the plurality of color printing heads, In addition, another scan is performed in the same direction as the one direction, and printing by the black printing head is superimposed on printing by the plurality of color printing heads. In addition, the invention according to claim 2 includes a head for black printing having a plurality of nozzles for performing printing by discharging ink from minute nozzles, and a plurality of color printing heads each having a plurality of nozzles. make use of,
In the inkjet recording method in which these heads are simultaneously scanned in the main scanning direction to perform overprinting, the plurality of color printing heads and the black printing head each have a plurality of nozzles orthogonal to the main scanning direction. Are arranged in a direction perpendicular to the sub-scanning direction, and printing by the plurality of color printing heads on the same printing area is always performed in the same scan in one direction, and the black printing The scan for printing on the same print area by the head is delayed from the scan for printing by the plurality of color print heads, and, with another scan in the same direction as the one direction, The printing by the black printing head is superimposed on the printing by the plurality of color printing heads. It is characterized in that shape.

(Operation) The present invention uses a black printing head having a plurality of nozzles for performing printing by discharging ink from minute nozzles, and a plurality of color printing heads each having a plurality of nozzles. In the ink jet recording method in which these heads are simultaneously scanned in the main scanning direction to perform overprinting, in the invention according to claim 1, the plurality of color printing heads each have a plurality of nozzles in the main scanning direction. Are arranged so as to be orthogonal to the direction, and are arranged in a direction perpendicular to the sub-scanning direction, and the head for black printing is arranged such that a plurality of nozzles are arranged in a direction orthogonal to the main scanning direction. As well as
A configuration is adopted in which the plurality of color printing heads are arranged downstream in the sub-scanning direction with respect to the plurality of color printing heads. In the invention according to claim 2, the plurality of color printing heads and the black printing head are Since the plurality of nozzles are arranged in a direction perpendicular to the main scanning direction and arranged in a direction perpendicular to the sub-scanning direction, the head configuration can be made compact. And while adopting such a head configuration,
In the invention according to claim 1, printing by the plurality of color printing heads on the same printing area is always performed by the same scan in one direction, and printing by the black printing head on the same printing area is performed. The scan is delayed from the scan for printing by the plurality of color printing heads, and is another scan in the same direction as the one direction, and the printing by the black printing head is performed by the plurality of heads. By performing overprinting on printing by the head for color printing, and in the invention according to claim 2, printing by the plurality of heads for color printing on the same printing area is always performed by the same scan in one direction, The scanning for printing on the same printing area by the black printing head is performed by the plurality of colors. Delaying from scanning for printing by the printing head, and performing another scan in the same direction as the one direction, and printing by the black printing head, printing by the plurality of color printing heads By printing over the print head, the print by the head for color print is always performed in the same scan in one direction, and the print time can be shortened. In addition, the print by the head for black print is printed with a delay of at least one scan. Therefore, the overprinting is performed by the black printing head in a state where the ink printed by the previously printed color printing head is dried, so that the bleeding of the ink can be avoided.

(Embodiment) FIG. 1 is an explanatory diagram of a head arrangement of an example of an ink jet recording apparatus used in an embodiment of the ink jet recording method of the present invention. In the figure, 1b, 1c, 1m, and 1y are black, cyan, magenta, and yellow heads, respectively, and 2 is a carriage plate.

In this embodiment, a direction x perpendicular to the paper feeding direction y
Further, cyan, magenta, and yellow heads 1c, 1m, and 1y are arranged, and black heads 1b are arranged in the same direction as the paper feeding direction y and mounted on the carriage plate 2. As described above, the carriage plate 2 is scanned by a timing belt and a carriage motor (not shown) to perform printing.

FIG. 2 is an explanatory diagram of one embodiment of the arrangement position of each head. In the figure, 1b, 1c, 1m, and 1y are black, cyan, magenta, and yellow heads, 2 is a carriage plate, and 4 is one of the nozzles in each head.

In this embodiment, the interval between the nozzle at the upper end of the cyan head 1c and the nozzle at the lower end of the black head 1b is set to p for one nozzle pitch, and the black head 1b is moved in the paper feeding direction y. It was attached to the carriage plate 2 so as to be downstream. In the printing sequence, first, printing is performed while scanning cyan, magenta, and yellow.
By feeding paper and printing black in the next scan, four colors can be printed in the same print area. In addition, black printing is performed when the ink has dried after a lapse of time from cyan, magenta, and yellow printing, so that no bleeding occurs.

FIG. 3 is a schematic configuration diagram of the head described in FIG. 1 and FIG. In the figure, 1b, 1c, 1m, and 1y are black, cyan, magenta, and yellow heads, 2 is a carriage plate, 3 is a carriage rail, 5b, 5c, 5m, and 5y are ink supply tubes for each color, 12b and 12c. , 12m and 12y are ink tanks for each color, 13 is a head holder, 14 is a maintenance station, and 15 is a cap. Each head 1b, 1c, 1m, 1y
Are screwed to the carriage plate 2 by the head holder 13. The nozzle spacing between the cyan, magenta, and yellow heads 1c, 1m, and 1y is an integral multiple of the nozzle pitch p, and the nozzles at the upper end of the cyan head 1c and the lower nozzles of the black head 1b are separated. As described above, the black head 1b is mounted downstream in the paper feed direction so that the interval is the nozzle pitch p of the head. To each head, ink is supplied from each color ink tank 12c, 12m, 12y, 12b using an ink tube 5c, 5m, 5y, 5b. The carriage plate 2 is scanned by a carriage rail 3, a timing belt (not shown), and a carriage motor. When not printing,
In order to prevent ink drying and dust adhesion on the nozzle surface,
The carriage plate is positioned at the home position, and is kept capped by the cap 15 at the maintenance station 14. When printing, release capping using a motor, cam, solenoid, etc., not shown, and output a print trigger signal corresponding to one pitch (for example, 84.5 μm in the case of 300 spi) according to scanning. The head is driven using the signal as a trigger.

When the first scan is performed, printing is performed in the order of yellow, magenta, and cyan. L is the head interval of each color,
Assuming that the driving frequency of the head is F and the pitch between nozzles is P, the printing time difference T for each color is T = L / PF.

 If L = 30 mm, P = 84.5 μm, and F = 4.5 kHz, T = 78.9 msec.

In the next scan, black is printed in the area where yellow, magenta, and cyan are printed in the previous scan, and the yellow, magenta, and cyan heads print in the next new area.

Here, assuming that the length of A4 in the vertical direction is 297 mm, the acceleration / deceleration area of the carriage motor is 20 mm, and the speed of the carriage in that area is half of the printing area on average, the scan time T2 for one scan is: T2 = 781 + 210 = 991 [msec] which is the sum of 2 × 20 / (PF / 2) = 210 [msec] in the acceleration / deceleration area in the printing area.

Therefore, when performing one-way printing, if the return time of the carriage is also T2 and the time for reversing the direction of the carriage is 200 msec, the time until black is printed in the area where yellow, magenta, and cyan are printed. Becomes 991 × 2 + 200 × 2 = 2.38 [sec]. 200 msec for reversing the direction of the carriage is a motor stop time between the rightward scan and the leftward scan, during which the paper feed data is transferred.

When there is no nozzle to the end of the head, in the head arrangement as described in FIG. 2, the distance between the nozzle ends of the cyan, magenta, and yellow heads 1c, 1m, and 1y and the black head 1b is determined by the nozzles. Cannot be set to p for one pitch. In this case, as shown in FIG. 4, a black head 1b is arranged between the cyan and magenta heads 1c and 1m, and the cyan, magenta and yellow heads are arranged.
The interval between 1c, 1m, 1y and the nozzle end of the black head 1b can be set to p for one pitch of the nozzle. In addition, the fifth
As shown, cyan, magenta and yellow heads
Distance d between nozzle ends between 1c, 1m, 1y and black head 1b
Can be set to (print width + twice the nozzle pitch) of the head. However, in this case, black printing is performed in the same area on the paper in the next scan after printing cyan, magenta, and yellow.

In this embodiment, the width of the carriage can be reduced by disposing the head for black printing on the downstream side in the paper feeding direction, and the outer width of the apparatus main body is reduced. Also, after printing the background with the head for color printing of cyan, magenta and yellow, and performing the overprinting with the head for black printing, the time from printing cyan, magenta and yellow to printing black is printed. Is relatively long, so that the background ink dries and has black overprinting,
Less bleeding.

Also, the present invention can be applied to the conventional head structure described with reference to FIG. First, in the first scan, cyan, magenta, and yellow heads 1c, 1m,
Perform color printing with 1y, and then without feeding paper,
Overprinting is performed in the same printing area by the black head 1b. That is, by performing two scans on the same print area to perform printing, when the color-printed ink in the first scan dries, black printing with the next ink can be performed.

In the case of this embodiment, it is not always necessary to scan each print area twice. When the print signal for one line is determined and, for example, there is no black print signal, the paper may be fed immediately after the first print to start printing for the next line.

Alternatively, the head may be divided into two parts by using two carriages and mounted on each carriage. For example, cyan, magenta, and yellow heads 1c, 1
m and 1y are mounted on the first carriage and arranged at the left home position, and the black head 1b is mounted on the second carriage and arranged at the right home position.

The printing method is to print cyan, magenta, and yellow while traveling in the right direction of the first carriage, and when the first carriage returns, the second carriage travels in the left direction together. Alternatively, printing may be performed when the second carriage travels rightward. Also in this case, printing can be performed efficiently by judging the print signal for each line and controlling the printing of both carriages and the control of paper feed.

(Effects of the Invention) As is apparent from the above description, according to the present invention, a black printing head in which ink bleeding is a problem,
Since there is a difference in printing time between the head for color printing and the ink printed by the head for color printing, overprinting with the head for black printing is performed on the dried state. This has the effect of reducing blurring of black printing by printing.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the arrangement of the heads in one embodiment of the color ink jet recording apparatus of the present invention, FIG. 2 is an explanatory view of the arrangement positions of the nozzles in FIG. 1, and FIG. FIGS. 4 and 5 are explanatory views of another embodiment of the nozzle arrangement position, and FIG. 6 is a schematic constitution of a head of a conventional color ink jet recording apparatus. FIG. 1b Black print head, 1y Yellow print head, 1m Magenta print head, 1c Cyan print head, 2 Carriage plate, 3 Carriage rail, 4 Nozzle.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-187865 (JP, A) JP-A-62-279954 (JP, A) JP-A-58-179655 (JP, A) JP-A-58-179655 194543 (JP, A) Table 2 504374 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B41J 2/21

Claims (2)

(57) [Claims] 1. A head for black printing having a plurality of nozzles for performing printing by discharging ink from minute nozzles, and a plurality of heads for color printing each having a plurality of nozzles, the heads being used for In the ink jet recording method of simultaneously scanning in the main scanning direction to perform overprinting, the plurality of color printing heads are arranged such that a plurality of nozzles are arranged in a direction orthogonal to the main scanning direction. Are arranged in a direction perpendicular to the sub-scanning direction, and the black printing head is arranged such that a plurality of nozzles are arranged in a direction orthogonal to the main scanning direction, and the plurality of nozzles are arranged in the plurality of color printing heads. The plurality of color printing heads for the same printing area are always arranged in the same scanning direction in one direction. The scanning for printing on the same printing area by the black printing head is delayed from the scanning for printing by the plurality of color printing heads, and is performed in the same direction as the one direction. An ink jet recording method, wherein printing by the black printing head is superimposed on printing by the plurality of color printing heads. 2. A head for black printing having a plurality of nozzles for performing printing by ejecting ink from minute nozzles, and a plurality of color printing heads each having a plurality of nozzles, the heads being used for the printing. In the ink jet recording method of simultaneously performing scanning in the main scanning direction and performing overprinting, the plurality of color printing heads and the black printing head are arranged such that each of the plurality of nozzles is in a direction orthogonal to the main scanning direction. Are arranged in a direction perpendicular to the sub-scanning direction, and printing by the plurality of color printing heads on the same printing area is always performed by the same scanning in one direction, and by the black printing head. The scan for printing on the same print area is performed by the plurality of color printing heads. Delaying from scanning, and performing another scan in the same direction as the one direction, and printing by the black printing head is superimposed on printing by the plurality of color printing heads. Ink jet recording method.