JP2002172765A - Architectural board printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an architectural board printer in which the need of a printing plate is eliminated utilizing an ink jet technology and small lot variety production can be dealt with. SOLUTION: Cells (grooves) 2a of specified shape are arranged, at a specified pitch, on the circumferential surface of a gravure roll 2. An ink jet mechanism 3 comprises recording heads 31, 32, 33 and 34 for ejecting cyan, magenta, yellow and black inks, respectively, to each cell, and an ink ejection controller 35. The ink ejection controller 35 controls ink ejection from each recording head 31, 32, 33, 34 based on the rotational position of the gravure roll 2 and preset ink ejection data (pixel data of an image to be written). Ink supplied to each cell 2a of the gravure roll 2 is transferred to the surface of an architectural board 8 through an offset roll 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a building board printing apparatus, and more particularly, to a building board printing apparatus using an ink-jet technique, which eliminates the need for a printing plate and is capable of coping with small lot multi-product production. Related to the device.

[0002]

2. Description of the Related Art A technique for printing a pattern on a building board using a gravure offset printing machine is known from Japanese Patent Application Laid-Open Nos. 9-30099 and 11-20297. JP-A-10-151722 describes a gravure printing apparatus in which a common gravure cylinder can be used and time-consuming production and plate making of a gravure cylinder are not required for each printing. This gravure printing apparatus includes a gravure cylinder having a large number of cells formed uniformly on its surface, ink filling means for filling the gravure cylinder with ink, and a part of the gravure cylinder filled with ink according to an image to be printed. An ink removing unit for removing the ink from the cells, a unit for collecting the removed ink, and a unit for printing by pressing the printing object against the gravure cylinder after removing a part of the ink.

[0003]

In the gravure offset printing method and the gravure printing method, gradation expression close to photographic quality can be achieved, but it is necessary to manufacture a gravure plate roll for each pattern. Further, in order to reproduce a multicolor image or a full-color image by this method, a plurality of color-separated gravure rolls is required. For example, in order to reproduce a full-color image, four types of gravure plates separated for each color such as cyan, magenta, yellow, and black are produced, and the respective inks corresponding to each plate are supplied and printed in order. Will go.

On the other hand, as in a general ink jet printer, cyan, magenta, yellow, and black inks are simultaneously ejected and supplied to paper as a printing material,
There is a printing system that realizes full-color printing. In such a system, since there is no need to produce a plate, it is possible to change the print contents for each sheet of paper, which is very convenient.

[0005] However, since many architectural boards have irregularities on the design surface (furthermore, thickness variations in the manufacture of the boards are added), it is supposed that the ink jet printing system is applied. However, since the distance between the ink jet nozzle and the printing surface is not constant,
It is extremely difficult to control for developing a desired print pattern.

In addition, the printing area of the building board is very large (for example, 455 mm × 1818 mm), and the production speed is as high as, for example, about 24 m / min. A printing system that requires 4 to 5 minutes to print a size cannot deal with multicolor printing on a building board at all.

Japanese Patent No. 3115136 (Japanese Patent Application No. 4-115) discloses a method of coating a building board using an ink jet system.
No. 3,310,042), an ink jet coating method for a building board using an ink jetting means of a valve opening / closing control method, or an ink jetting means of a piezo vibration control type disclosed in JP-A-9-201564. Although there is a method of ink-jet coating a building board as described above, none of the methods can cope with the above-mentioned state in which the distance between the ink jet nozzle and the surface to be printed is not constant.

Further, a pattern is drawn on the transfer belt using an ink jet coating machine as disclosed in Japanese Patent Application Laid-Open No. 10-128230 (in this case, the distance between the ink jet nozzle and the transfer belt becomes constant. There is also a method in which the transfer belt is pressed against the design surface of the building board to develop a pattern on the surface of the building board. However, there is a problem of running accuracy of the transfer belt (a problem of the ink supply device) and a problem of transfer. There are problems such as the occurrence of pattern misalignment due to the belt being interposed between the holding roll and the running building board, and it is hard to say that stable processing can be achieved.

On the other hand, Japanese Patent Application Laid-Open No. H10-151722
In the gravure printing apparatus described in the publication, a gravure cylinder can be commonly used for printing any image. However, it is necessary to produce a printing plate for removing the ink corresponding to the image to be printed.

It takes a certain number of days to manufacture a gravure roll or a printing plate for removing ink. Also,
When changing the pattern (image) to be printed, it is necessary to change the printing plate for removing the gravure plate roll and ink. For this reason, a printing method using a plate such as a gravure plate roll or a printing plate for removing ink cannot flexibly cope with small lot multi-product production.

Therefore, there is a demand for a technique capable of performing printing of a quality close to gravure printing or gravure offset printing without using a physical plate. Further, there is a demand for a technique that enables multi-color printing or full-color printing in one printing without overprinting, as in an ink jet printing system. The present invention has been made in order to solve such problems, without using a physical plate, building board printing that can perform printing of a quality close to gravure printing or gravure offset printing on a building board It is intended to provide a device.

[0012]

In order to solve the above-mentioned problems, a building board printing apparatus according to the present invention comprises a gravure roll that rotates while holding supplied ink in a plurality of cells, An ink jet mechanism for ejecting and supplying ink is provided, and an offset roll is transferred to the gravure roll and the ink held on the gravure roll is transferred and transferred to a building board.

The plurality of cell parts are squares each having the same size, and the diagonal line is parallel to the ridge line of the gravure roll, so that the pitch of ink ejection is smaller than the area of the cell part. I can afford it. The ink jet mechanism has a nozzle for selectively ejecting different inks to each of the cell portions, so that it is possible to form a color pattern with the cell portion as a pixel. The ink jet mechanism can improve color reproducibility by having nozzles for ejecting inks of the same dye and different densities.

By providing a cleaning head for removing untransferred ink remaining on the surface of the gravure roll from the gravure roll, it is possible to avoid color mixing between untransferred ink and new ink. The cleaning head includes:
The provision of the cleaning liquid ejection supply head for ejecting and supplying the cleaning liquid and the suction recovery head for suctioning and recovering the cleaning liquid ensure that the untransferred ink is removed.

[0015]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG.
1 is a schematic structural diagram of a building board printing apparatus according to the present invention.
The building board printing apparatus 1 shown in FIG.
, An inkjet mechanism 3, a gravure roll cleaning mechanism 4, an offset roll 5, an offset roll cleaning mechanism 6, a backup roll 7, and each of the rolls 2, 5, and 7.
(Not shown) for rotating the.

Reference numeral 8 denotes a ceramic building board. The ceramic building board 8 is transported by a transport mechanism (conveyor device) (not shown) and travels between the backup roll 7 and the offset roll 5. In the present embodiment, the building board 8 has been subjected to the undercoating and the drying treatment after the undercoating, and the intermediate coating and the drying treatment after the intermediate coating, and the entire surface of the building board is formed by the groove (recess) of the building board. It is colored. Also, as a base treatment before printing, for example, white, gray, light beige, etc., the convex part of the building board to be printed is subjected to convex part painting, so that the printing color is The effect becomes more pronounced.

On the peripheral surface of the gravure roll 2, a number of cells (grooves) 2a having the same shape and the same depth are arranged at uniform intervals. The ink jet mechanism 3 is a gravure roll 2
Recording heads 31, 32, 3 arranged opposite to
3 and 34 and an ink ejection control device 35.

The recording head 31 is an ink jet head for supplying cyan ink, the recording head 32 is an ink jet head for supplying magenta ink, and the recording head 33 is an ink jet head for supplying yellow ink. The recording head 34 is an ink jet head that supplies black ink. Each of the recording heads 31, 32, 33, and 34 has an inkjet head group C1, M1, Y1, and
K1 and inkjet head groups C2, M2, Y2, and K2 that supply light-colored ink are provided as a set, and a total of eight nozzle arrays are arranged to face the gravure roll 2.

In each of the recording heads 31 to 34, a number of nozzles for ejecting ink are arranged on the bottom surface. The ejection control of the ink from the individual nozzles in each of the recording heads 31 to 34 is based on the piezo element control method. The ink chambers constituting each nozzle section are connected to a common ink tank for ink supply. Each recording head 31
To 34, a large number of ink jet nozzles are integrated in order to cover a direction (transverse direction) intersecting with the traveling direction of the building board 8 to be printed.

Incidentally, the arrangement pitch of the nozzles is 1/360 inch (about 0.07 inch) in the field of office equipment.
mm) and 1/600 inch (approximately 0.04 mm) have been put to practical use. However, a pattern (image) printing on a building board is not required to have a very high resolution.

It is to be noted that the ink jet direction from the individual nozzles of each of the recording heads 31 to 34 is directed to the rotation center point of the gravure roll 2 so that the installation of each of the recording heads 31 to 34 is properly performed by appropriate means. Is positioned at Each of the recording heads 31 to 34 is detachably positioned by appropriate means. This facilitates replacement of the recording heads 31 to 34 and cleaning of the nozzle tip.

The ink jet control unit 35 controls each of the ink jet head groups C1, M1, Y1, K1, C2 based on the rotational position of the gravure roll 2 and preset ink jet data (pixel data of an image to be drawn). , M2, Y
2 and K2, the ink ejection is controlled for each nozzle.
Thereby, the color and the density of the ink supplied to the individual cells 2a of the gravure roll 2 are controlled.

The gravure roll 2 has a gravure roll cleaning mechanism 4 opposed to the recording head 31 at a position before the recording head 31. The gravure roll cleaning mechanism 4 includes a cleaning liquid jet supply head 41 for jetting and supplying a cleaning liquid to each cell 2a of the gravure roll 2, and a non-transferred ink remaining in the cell 2a together with the cleaning liquid supplied to the cell 2a. It comprises a suction and collection head 42 for suction and collection, a suction blower (not shown) and a collection tank.

In order to clean the surface of the gravure roll 2, each of the recording heads 31 to
A cleaning nozzle array similar to 34 is provided. The suction and collection head 42 is provided with a tapered suction hood having a slit-shaped opening, and the tip of the suction hood is collected in a collection tank by a suction blower through a collection pipe.

The offset roll 5 is a gravure roll 2
Has been transferred to The offset roll cleaning mechanism 6 includes a cleaning roll 61, a cleaning spray head 62,
It comprises a doctor roll 63 and a recovery bus 64. In order to clean the surface of the transferred offset roll 5 after the ink has been transferred to the building board 8, a cleaning roll (made of sponge) 61 is in rolling contact with the offset roll 5. Further, a cleaning spray head 62 for supplying a cleaning liquid from above is provided in a recess of a rolling contact portion between the cleaning roll 61 and the offset roll 5.

The cleaning spray head 62 is provided with a plurality of spray nozzles for supplying a cleaning liquid, and the cleaning liquid is ejected in an airless manner using a plunger pump or the like. The washed liquid transferred to the cleaning roll 61 is collected by a doctor roll (made of stainless steel) 63 which is brought into contact with the cleaning roll 61 in a collecting bath 64 provided below.

FIG. 2A is an external perspective view of the gravure roll, and FIG. 2B is an enlarged view of the roll surface of the gravure roll. As shown in FIG. 2B, the minute cells 2a formed on the roll surface are arranged at an inclination angle of 45 degrees with respect to the ridge direction of the gravure roll 2, that is, the diagonal lines of the cells 2a are arranged parallel to the ridge direction. Have been. By forming the cell array of 45 degrees in this manner, the halftone pitch becomes 1 / √2
It becomes possible to.

The cells 2a of the gravure roll 2 may be generated by an etching method or a mechanical engraving method. In general, in gravure printing, the lower limit of the opening width of each cell in the gravure printing roll is 30 to 35 μm from the viewpoint of ink transferability, and the cell depth is about 2 to 50 μm.

FIG. 3 is a diagram showing a specific example of the arrangement of cells and the arrangement of nozzles. FIG. 3A is a plan view of the cell, and FIG.
(B) shows a sectional view of the cell. In the present embodiment, the opening width of the cell 2a is 0.1 mm (100 μm), and the width of the bank between the cells is 0.02 mm. As a result, the cell pitch becomes 0.12 mm. Therefore, by arranging the cells at an inclination angle of 45 degrees as described above, the number of screens can be reduced to about 300 (= 25.4 × √2 / 0.12) / It can be on the order of inches. The opening width of the cell is about 1/3.
(About 33 μm), which can further increase the resolution.

In the present embodiment, the depth of the cell 2a is set to 50
μm. Assuming that 90% of the cell volume of ink is supplied so that the ink stored in the cell does not protrude outside the cell, the amount of ink stored in one cell is 4%.
It is about 50 pL (picoliter). The cell volume is basically determined by the coloring power of the ink. The amount of one ink ejection from one nozzle is set to 225
If it is set to about pL, by providing two nozzles for one cell having a necessary capacity of 450 pL, it is possible to supply a necessary amount of ink by one ejection.

FIG. 3C is a diagram showing the arrangement of nozzles for each cell. Therefore, as shown in FIG. 3C, each of the inkjet head groups C1, M1, Y1, and K is set so that two nozzles face one cell 2a.
1, C2, M2, Y2, and K2.

Assuming that the line speed (transport speed of the building board 8) is 24 m / min (0.4 m / sec), the time required for one cell to pass immediately below one recording head is the cell opening diagonal line width (140 μm). ) ÷ (0.4 m / sec) = 350 μsec, and the nozzle ejection frequency is 2860 times / sec. Normal,
Since injection control of about 10,000 times / second is possible, this value is a value that can be sufficiently controlled. More specifically, ink is ejected by applying a pulse voltage of a predetermined frequency set to each piezo element driving electrode. Ink ejection timing and the like are controlled synchronously with the transport control of the building board 8.

A single nozzle may face one cell, and a predetermined amount of ink may be supplied into the cell by a plurality of ink ejections. Further, ink may be sequentially supplied to each cell by scanning the recording head. In the present embodiment, since the capacity of each cell is the same, gradation expression cannot be performed by changing the amount of ink supplied to each cell. However, since the recording heads 31 to 34 are configured to be able to supply two sets of dark and light inks, the color density can be changed and the color reproducibility is excellent.

FIG. 4 is a diagram showing a specific example of multi-tone expression. One pixel is composed of nine cells as shown in FIG. 4A, and one pixel is composed of 16 cells as shown in FIG. By varying the density and the density, multi-gradation can be expressed.

FIG. 5 is a diagram showing a specific example of multi-gradation expression using nine cells. In FIG. 5, N indicates no ink,
C is dark cyan ink, c is light cyan ink, M
Is dark magenta ink, m is light magenta ink,
Y indicates yellow deep ink, y indicates yellow light ink, K indicates black dark ink, and k indicates black light ink.

One halftone dot is formed by ink contained in one cell. Here, one pixel is formed by a matrix of 9 (= 3 × 3) cells. In forming this pixel matrix, the same dye / density ink is placed in the squares located at the four corners, and each dye / density is set so that the squares around the center square are as symmetrical as possible. Place the ink. With such a pigment arrangement, even if the dot density is relatively large, the area for forming one pixel is made equal, the pixel pitch is made equal, and the color mixing effect due to the proximity of the ink to each cell is improved. I can do it. FIG. 5 shows an example in which inks of various dyes and densities are arranged by paying attention to cyan colors c and C.

As shown in FIG. 5, the hue expressed by each pixel is represented by the following equation (cyan * α + magenta * β +
Since the area ratio is represented by (yellow * γ + black * δ), actual printing on the printing plate with the ink to be used is performed under the conditions applicable to each equation. Then, the printed plate is determined as a reference color expression standard plate, and the color is measured to create a reference color conversion database, which is used for each image to be expressed on the plate surface every time. Calculation is performed to create print control data (data on which nozzles are to be fired and at what timing). The printing for creating the reference color conversion database need only be performed once, and thereafter, image processing calculations are performed based on this database to create necessary print control data. Note that by reducing the cell pitch, the pixel formation matrix can be made finer, and the resolution can be further increased.

In this embodiment, the digital image to be handled is a raster image.
In a raster image, an original image is divided into fine lattice-shaped regions (called pixels), and each region is handled in such a manner that color information is provided in each region. Raster images in CMYK format are C (cyan), M (magenta), Y
(Yellow) and K (black) four channels (1
An image in which the intensity of element colors of light and color materials is recorded. In this case, one channel records the amount of light and color material as a change in light and shade just like a black and white photograph.

This raster image has gradations. For example, in a printed matter or an ink jet printer, it is necessary to reproduce an image having 64 to 128 gradations in order to reproduce beautiful natural light and shade. On the other hand, in order to print the change in brightness of an image on a hard copy such as paper or film, a method called a continuous tone method (a thermal sublimation type printer or a silver halide type printer) and an area tone method are used. There is a way. In the former, each pixel can reproduce 128-256 steps of light-dark change on hard copy,
In the latter, ink dots of a certain density are arranged on a hard copy so as to reproduce a change in lightness and darkness from a distance.

The area gradation method includes a halftone gradation method (offset printing) and a dither pattern gradation method (inkjet printer). In the former, the diameter of the ink dots having a constant density is changed, whereas in the latter, the size of the dots is fixed and the density of the dots is changed.

By employing this area gradation method, there is no need to form a plurality of gravure plates corresponding to the decomposed images in accordance with the pattern, and the gravure roll 2 can be controlled simply by controlling the recording head. A full-color image is reproduced on the upper surface, and the image is transferred to the offset roll 5 and further transferred to the surface of a building board. This realizes a coloring method, which makes it possible to completely cope with small lot multi-product production. Furthermore, the pattern expression is rich, and it is characterized by realizing continuous full-color printing of building boards by combining inkjet printing technology with gravure offset printing technology.

FIG. 6 is a diagram showing the transfer of ink from a gravure roll to an offset roll. The offset roll 5 has a low rubber hardness (for example, a rubber hardness of 15 to 3).
5 degrees). By lowering the rubber hardness, the compatibility with the gravure roll 2 is improved.
As a result, the ink contained in each cell is effectively taken out of the cell and transferred to the surface of the offset roll 5.

That is, as shown in FIG. 6A, since the surface of the offset roll 5 reliably contacts the ink surface in each cell portion, the ink in the cell is drawn out of the cell due to its viscosity. As shown in FIG. 6B, the transfer to the surface of the offset roll 5 occurs. Further, the familiarity between the offset roll 5 and the surface of the building board 8 is good, and the ink can be surely transferred to the building board having unevenness on the surface.

[0044]

As described above, the building board printing apparatus according to the present invention supplies a gravure roll having cells of a predetermined shape arranged on the surface thereof at a predetermined pitch to each cell using an ink jet mechanism. By controlling the color and density of the ink to be formed, a color pattern with gradation expression is formed on the surface of the gravure roll, and the color pattern is transferred to the building board surface via the offset roll, thereby building the building. A color pattern with gradation expression is printed on the board surface. Therefore, the building board printing apparatus according to the present invention does not require a physical plate, and can flexibly cope with small lot multi-product production.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a building board printing apparatus according to the present invention.

FIG. 2 is an external perspective view of a gravure roll and an enlarged view of a roll surface of the gravure roll.

FIG. 3 is a diagram showing a specific example of an arrangement of cells and an arrangement of nozzles.

FIG. 4 is a diagram showing a specific example of multi-tone expression.

FIG. 5 is a diagram showing a specific example of multi-tone expression using nine cells.

FIG. 6 is a diagram illustrating transfer of ink from a gravure roll to an offset roll.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Building board printing apparatus 2 Gravure roll 3 Ink jet mechanism 4 Gravure roll cleaning mechanism 5 Offset roll 6 Offset roll cleaning mechanism 7 Backup roll 8 Building board

Claims (6)

[Claims] A gravure roll that rotates while holding the supplied ink in a plurality of cell parts; an inkjet mechanism that ejects and supplies ink to the cell part; An architectural board printing apparatus, comprising: an offset roll to which ink held by a gravure roll is transferred and transferred to a building board. 2. The building board printing apparatus according to claim 1, wherein each of the plurality of cell portions is a square having the same size, and a diagonal line is parallel to a ridge line of the gravure roll. . 3. The building board printing apparatus according to claim 1, wherein the ink-jet mechanism has a nozzle for selectively ejecting different inks to each of the cell portions. 4. The building board printing apparatus according to claim 1, wherein said ink jet mechanism has nozzles for ejecting inks of the same dye and different densities. 5. The building board printing apparatus according to claim 1, further comprising a cleaning head for removing untransferred ink remaining on the surface of the gravure roll from the gravure roll. 6. The building board printing apparatus according to claim 5, wherein the cleaning head includes a cleaning liquid ejection supply head that ejects and supplies the cleaning liquid, and a suction recovery head that suctions and recovers the cleaning liquid.