JP2002120361A - Ink jet recording device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a high-speed and high-quality drum type ink jet recording apparatus. SOLUTION: The ink jet recording apparatus has a drum for fixing paper, and a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction of the drum with respect to the drum. In an ink jet recording apparatus that performs color printing on paper, the time (color superimposition time) T until dots of different colors contact or overlap at the landing position is T ≧ 10.
msec.

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 drum for fixing paper,
The present invention relates to an ink jet recording apparatus having a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction with respect to the drum, and performing color printing on the paper by driving the ink jet head while rotating the drum. is there.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 9, a recording paper is wound around a drum-shaped recording paper conveyer and, for example, six colors (yellow, cyan, light cyan, magenta, light magenta, black ) Are equipped with six ink-jet heads that can independently control the ejection of ink, the nozzle rows of each ink-jet head are orthogonal to the drum rotation direction, and the nozzle arrangement of each color is positioned in the drum rotation direction. Has been proposed.

[0003]

At the recording point of this ink jet recording apparatus, as shown in FIG. 10, when forming adjacent dots with different colors, the first ink droplet lands on the recording paper. If the second ink droplet lands on an adjacent position before it is completely absorbed by the recording paper, the second ink drops on the surface of the recording paper before being absorbed by the recording paper. The ink droplet is pulled by the surface tension, causing a trouble called bleed. Due to the bleed, a dot larger than the original dot (see FIG. 10A) or a dot having a shape distorted by the bleed is formed (see FIG. 10B). The landing position was out of order. When such a phenomenon occurs, image quality defects such as color inconsistency, recording unevenness, and banding occur, and there is a problem that an output satisfying the user cannot be obtained.

An object of the present invention is to provide a high-speed and high-quality ink jet recording apparatus in order to solve such a problem.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, an ink jet recording apparatus according to claim 1 is provided.
A drum for fixing the paper, and a plurality of inkjet heads arranged at predetermined intervals in the circumferential direction with respect to the drum, and the inkjet head is driven while rotating the drum to perform color printing on the paper. Is characterized in that the time (color superimposition time) T until the dots of different colors contact or overlap at the impact position is T ≧ 10 msec.

According to the ink jet recording apparatus of the first aspect, since the color superposition time T is set so as to satisfy T ≧ 10 msec, bleeding is prevented from occurring and the original dot position and the original dot position and shape (size) can be reduced. Adjacent dots can be formed by close dots.

According to a second aspect of the present invention, there is provided an ink jet recording apparatus comprising: a drum for fixing a sheet; and a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction with respect to the drum. In the ink jet recording apparatus for performing color printing on the paper by driving the ink jet head while rotating, the drum speed S and the adjacent distance between the ink jet heads driven during the same rotation of the drum (between adjacent heads having the same driving rotation) (Distance) D is such that D / S ≧ 10 msec.

According to the ink jet recording apparatus of the second aspect, since the drum speed S and the distance D between adjacent heads in the same driving cycle satisfy D / S ≧ 10 msec, occurrence of bleed is prevented. Adjacent dots can be formed at dot positions and shapes (sizes) close to the original dots. Note that the relationship of T = D / S is established. Therefore, it can be said that T = D / S ≧ 10 msec.

According to a third aspect of the present invention, there is provided an ink jet recording apparatus comprising: a drum for fixing a sheet; and a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction with respect to the drum. In the ink jet recording apparatus which drives the ink jet head while performing color printing on the paper, the output resolution R
, The distance D between adjacent heads in the same driving circuit, and the number of passes n + 1
(N is the number of interleaves) and the head drive frequency f is such that RD / {(n + 1) f} ≧ 10 msec.

According to the ink jet recording apparatus of the third aspect, the output resolution R, the distance D between adjacent heads in the same driving cycle, the number of passes n + 1 (n is the number of interleaves),
RD / {(n + 1) f} ≧ 1
Since the configuration is made to be 0 msec, bleeding can be prevented, and adjacent dots can be formed with dots close to the original dot position and shape (size).
Note that a relationship of T = RD / {(n + 1) f} is established.
Therefore, T = D / S = RD / {(n + 1) f} ≧ 10 m
sec.

According to a fourth aspect of the present invention, there is provided an ink jet printer, comprising: a drum for fixing paper; and a plurality of ink jet heads arranged at predetermined intervals in the direction of rotation of the drum. In the ink jet recording apparatus for performing color printing on the paper by driving the ink jet head while the number of passes is n + 1
When (n is the number of interleaves) is 4 or more, dots formed by another inkjet head are formed in the middle of dots formed by one inkjet head in the same circuit of the drum so that the dots do not contact or overlap with each other. It is characterized by having such a configuration.

According to the ink jet printer of the present invention, the number of passes n + 1 (n is the number of interleaves) is 4
In the above case, in the same rotation of the drum, dots formed by another ink jet head are formed in the middle of dots formed by one ink jet head so that the dots do not contact or overlap with each other, so that dots can be formed efficiently at high speed. can do. Note that the number of paths n + 1
Is 6, two different color dots can be formed between the initially formed dots.

According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus comprising: a drum for fixing a sheet; and a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction with respect to the drum. 5. The ink jet recording apparatus that drives the ink jet head to perform color printing on the sheet while performing color printing using water-based ink on the sheet. 6. 3. The ink jet recording apparatus according to item 1.

This is because the bleeding problem is particularly important when color printing is performed using an aqueous ink.

[0015]

Next, an ink jet recording apparatus according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the inkjet recording apparatus 1 includes a paper winding drum 3 for winding and fixing a paper,
A head unit 7 having six color ink jet heads 5, 5,... Arranged at predetermined intervals in the circumferential direction of the paper winding drum 3 and the head unit 7 is slid in the axial direction of the paper winding drum 3. Slide motor 9 and head slide ball screw 1 for
Are driven to drive the inkjet heads 5, 5,... While rotating the paper winding drum 3 to execute color printing on the paper.

In this ink jet recording apparatus 1,
From the frequency of the head 5, the output resolution and the number of interleaves, the peripheral speed S of the drum 3 can be obtained according to the following equation.

[0017]

(Equation 1)

Generally, the photo output is 250-300 d
It is sufficient that at least 100 gradations can be expressed with pi resolution. When a 300 dpi pixel is divided vertically and horizontally into two and four pixels are composed of normal color ink, light color ink, and three types of ink dot diameters of large, medium and small, 210 gradations are theoretically possible. . That is, 210 is obtained by applying p = 4 and r = 7 to the theoretical formula of the following gradation.

[0019]

(Equation 2)

Therefore, a simple resolution of printing is 600d
pi. Here, the head drive frequency f = 10
When the kHz and the printing resolution are 600 dpi, the following table is obtained by calculating the drum speed S based on the number of Interleaf (thinned-out printing) using the above equation 1.

[0021]

[Table 1]

Next, the minimum head-to-head distance is determined from the drum speed and the ink absorption speed obtained from an experiment relating to bleeding described later. Here, for example, the layout of the heads is considered as shown in FIG. 2, and the relationship between the distance between the heads and the dot overlap time is graphed for each drum speed, as shown in FIG.

Next, a description will be given of experimental results on the color superimposition time and the occurrence of bleeding. In this experiment, the offset between the dots was 0 mm, 0.02 mm, 0.04 mm.
mm and 0.06 mm, dots of different colors were formed, and the occurrence of bleeding was observed when overlapping dots were formed while varying the color overlap time. FIG. 4 shows the results. Further, colorimetric patches based on the respective dots shown in FIG. 4 are created (dots are created at intervals of 150 dpi), and the results of numerically evaluating these print patches according to the CIELab rule are shown in the graph of FIG. As is clear from FIG. 5, when the color superposition time was set to 10 msec or more, the color difference (Delta E) became 1 or less, and it was verified that the influence of bleeding did not pose a practical problem. In addition, when the color superposition time is set to 20 msec or longer, the influence of bleeding hardly occurs.

As a result, when the color overlay time is set to 10 msec in the ink jet recording apparatus 1 according to the embodiment and applied to FIG. 3, the minimum head-to-head distance at each drum speed can be obtained.

Next, in an ink jet recording apparatus equipped with 300 dpi heads 5 each having 299 nozzles arranged in the axial direction of the drum 3, one head is used for printing at a resolution of 600 dpi and a width of 4 inches. The printing operation of No. 5 will be described as an example. In this case, as shown in FIG. 6, at the start position of the head, that is, at the first pass, nozzles Nos. 150 to 299 are driven and printing is performed for one rotation. Next, the head is moved for 149 nozzle pitches (15
(0 nozzle pitch-1 dot pitch) Slide horizontally to print the second pass with all nozzles being driven. In the second pass, the 1st to 149th nozzles are printed so as to fill the space printed in the first pass, and 600 dpi printing is completed in this portion. The same operation is repeated, and in the last ninth pass, only the 1st to 150th nozzles are driven (the remaining nozzles are turned off) to complete printing of 4 inches. The numbers 1 to 299 in the drawing are nozzle numbers.

Next, as described above, the drum diameter is 500 m.
Table 2 shows the results of a trial calculation of the printing time required for full-color printing with a width of 4 inches when the inkjet head 5 having a nozzle arrangement of 300 dpi is driven at a frequency of 10 kHz in the inkjet recording apparatus of m. That is, in order to satisfy the color superimposition time at each drum speed determined by the number of interleaves at least 10 msec, 1
The required number of rotations of the drum during the pass is obtained, and the actual printing time based thereon is shown in Table 2. At this time, since the head unit 7 is slid in the axial direction to achieve recording of a width of 4 inches, the head unit 7 moves to the adjacent printing position during one rotation of the drum. Incidentally, T in Table 2
totalTurn No. (TTN) is calculated by the following equation.

[0027]

(Equation 3)

[0028]

[Table 2]

In Table 2, the interleaf is 3
In the above case, as shown in FIG. 7A, dots of another color (for example, magenta M) are formed between yellow Y and yellow Y. Therefore, Color Turn No. Can be reduced as shown in parentheses in the table. As a result, T
total Run No. And Total Prin
t Time also becomes as shown in parentheses. Also,
When the interleaf becomes 5 or more, dots of two other colors (magenta M and cyan C) are formed between yellow Y and yellow Y as shown in FIG.
r TurnNo. , Total Run No. And Total Print Time are ()
It becomes as shown in.

As described above, according to the present embodiment, the time (color superimposition time) T until the dots of different colors contact or overlap at the landing position is T.
By setting ≧ 10 msec, practical adverse effects of bleeding can be eliminated, and occurrence of poor image quality such as uneven recording, banding, and color mismatch can be prevented.

When this relationship is expressed by other parameters, the drum speed S and the distance D between ink-jet heads driven during the same rotation of the drum (distance between adjacent heads having the same driving rotation) are D. / S ≧ 10ms
ec.

Further, when the above relationship is expressed by other parameters, the output resolution R, the distance D between adjacent heads in the same driving cycle, the number of passes n + 1 (n is the number of interleaves),
When the head drive frequency f is RD / {(n + 1) f} ≧ 1
It can be said that the time should be 0 msec.

When the number of passes n + 1 (n is the number of interleaves) is 4 or more, in the same rotation of the drum, a dot by another ink jet head is placed in the middle of a dot by one ink jet head, and the dots contact each other. It can be formed so as not to be overlapped, so that the printing time can be reduced while preventing bleeding.

Further, in general, it is necessary to consider the drying of the ink as irregular noise during ink jet recording.

In the meniscus of the ink jet head, the ink is always in contact with air and the moisture is evaporated.

If left as it is, the water content of the ink gradually evaporates and the viscosity of the ink increases, so that good ink cannot be ejected. For example, there are drop volume fluctuation, splash, non-discharge, drop bending, drop speed fluctuation, etc., all of which cause deterioration of image quality.

In order to prevent the ink from drying in the meniscus, the nozzle surface is capped at the time of printing standby, and the ink is periodically ejected at the non-printing portion (this is called flushing) at the time of printing. We always make an effort to form a stable ink meniscus.

The drying of the ink at the meniscus portion affects the ink ejection in seconds.

If the print standby state is shorter than 10 seconds, stable ejection can be achieved by devising the drive waveform of the head. This also varies in various conditions depending on the ink, but this is generally the case.

If this time is longer than 10 seconds, it is impossible to cope with it only by devising the driving waveform of the head.
Each time, a flushing operation in a non-printing portion is required.

In this embodiment, a drum printer having a diameter of 500 mm is assumed, and the drum circumference is about 1500 m.
The paper is wound and printed with a length of m.

The drum is provided with a flushing portion in a direction perpendicular to the circumferential direction (a direction parallel to the head nozzle row) (omitted in this figure), and at least one flushing is performed during one revolution of the drum. It has a configuration that allows it.

That is, the drum circumference 1500 mm is set to 10
One rotation is required in less than one second. Therefore, a speed of drum speed S = 1500/10 = 150 mm / s or more is required.

In this case, the distance D between the heads and the color overlap time T
The following equation is obtained when the relationship is expressed as shown in FIG.

[0045]

(Equation 4)

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and it is possible to adopt various forms without departing from the gist of the present invention. Of course.

[0047]

As described above, it is possible to provide a high-speed, high-quality drum type ink jet recording apparatus.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of an inkjet recording apparatus according to an embodiment.

FIG. 2 is a schematic diagram illustrating a configuration of an embodiment.

FIG. 3 is a graph showing a relationship between a head-to-head distance and a dot color superposition time for each drum speed.

FIG. 4 is an explanatory diagram created based on a photograph taken of a result of a bleeding test.

FIG. 5 is a graph showing the results of a bleeding test.

FIG. 6: 300 dpi resolution with a 300 dpi head
FIG. 4 is an explanatory diagram showing an example in which printing is performed with a width of 4 inches.

7A is an explanatory diagram showing a printing method when the number of interleaves is 3 or more, and FIG. 7B is an explanatory diagram showing a printing method when the number of interleaves is 5 or more.

FIG. 8 is a graph showing the relationship between the head distance and the color superposition time.

FIG. 9 is a schematic diagram showing a configuration of a conventional example.

FIG. 10 is an explanatory diagram showing a conventional problem.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ink jet recording apparatus, 3 ... Paper winding drum, 5 ... Ink jet head, 7 ... Head unit, 9 ... Head slide motor, 11
..Head slide ball screw.

Claims (5)

[Claims] 1. A drum for fixing paper, and a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction with respect to the drum, wherein the ink jet head is driven while rotating the drum. In the ink jet recording apparatus for performing color printing on the paper, a time (color superimposing time) T until dots of different colors contact or overlap each other at a landing position is T ≧ 1.
An ink jet recording apparatus, which is configured to be 0 msec. 2. A printing apparatus comprising: a drum for fixing a sheet; and a plurality of inkjet heads disposed at predetermined intervals in a circumferential direction with respect to the drum, wherein the inkjet head is driven while rotating the drum. In the ink jet recording apparatus for performing color printing on the paper, a drum speed S and an adjacent distance D between ink jet heads driven during the same rotation of the drum (distance between adjacent heads having the same driving rotation) D / S An ink jet recording apparatus configured to satisfy ≧ 10 msec. 3. A drum for fixing a sheet, and a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction with respect to the drum, wherein the ink jet head is driven while rotating the drum. In an ink jet recording apparatus for performing color printing on the paper, an output resolution R, a distance D between adjacent heads in the same driving revolution,
The number of passes n + 1 (n is the number of interleaves) and the head drive frequency f are RD / {(n + 1) f} ≧ 10 mse
c. An ink jet recording apparatus characterized by being configured to be c. 4. A drum for fixing paper, and a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction with respect to the drum, wherein the ink jet head is driven while rotating the drum. In the ink jet recording apparatus for performing color printing on the paper, if the number of passes n + 1 (n is the number of interleaves) is 4 or more, the other ink jet heads may be positioned between the dots of one ink jet head in the same rotation of the drum. An ink jet recording apparatus characterized in that dots are formed such that the dots do not contact or overlap with each other. 5. A drum for fixing a sheet, and a plurality of ink jet heads arranged at predetermined intervals in a circumferential direction with respect to the drum, wherein the ink jet head is driven while rotating the drum. The inkjet recording apparatus according to any one of claims 1 to 4, wherein the inkjet recording apparatus performs color printing on the paper, and performs color printing using water-based ink on the paper.