JPH03121853A - Non-contact type printing machine - Google Patents

Abstract

PURPOSE:To make a high speed printing of a large object under a non-contact condition and save labor for plate making and plate replacement, etc., by a method wherein while considering a travel detecting speed on an object to be printed and arranging positions of respective ink discharge ports, application of a pulse voltage onto an ink jet head is controlled. CONSTITUTION:When a corrugated fiberboard 1 is carried by a vacuum carrying device 2, to respective heads 12 in respective color units 7a-10b, a pulse voltage with an appropriately set frequency is applied, based on a printing pattern information which has previously been input in a control unit 21 and speed information detected through a speed detector 23, and a desired printing is full automatically performed. This printing can be done with a single color, two colors or multi-color. At this time, even when a designated color is printed, it can be expressed by a distribution on the surfaces of respective colors in the same manner as an ordinary multi-color printing. By this method, by simply inputting a printing pattern to the control unit 21, different printings can be continuously performed while a plate making is not required, and further replacement of a plate is not necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a non-contact printing device that is capable of high-speed printing even on large substrates in a non-contact manner.

<Prior Art and Problems to be Solved by the Invention> Most conventional printing machines are of the contact type in which the printing material comes into contact with a plate, etc., and printing pressure is always applied to the printing material.

On the other hand, an inkjet printer is known as a printing machine that does not require printing pressure.

However, conventional inkjet printers print one line by moving the head along a stationary printing medium, and print the entire line by sequentially feeding the paper. Therefore, compared to the above-mentioned contact type printing machine, the printing time is considerably longer, making it unsuitable for printing in large quantities or printing on large substrates.

Therefore, in the past, printing on corrugated cardboard required to suppress printing pressure as much as possible to prevent collapsing.
Contact rubber letterpress printing and flexo printing are used. Although flexographic printing has been improved to reduce the printing pressure to some extent compared to rubber letterpress printing, printing pressure is still applied to the printing material. When such unevenness occurs, the strength of the corrugated board deteriorates, and it is generally said that printing causes a deterioration in strength of about 14%.

In addition, with the diversification of products in recent years, the demand for corrugated cardboard has become small-quantity, high-mix. However, rubber letterpress printing and flexographic printing have the problem that it takes time and effort to make plates and replace plates every time the printing is changed, resulting in excessive costs.

In view of these circumstances, the present invention enables non-contact, high-speed printing on large-sized printing materials, and plate making.

The purpose is to provide a non-contact printing machine that does not require time and effort such as changing plates.

Means for Solving the Problems> A non-contact printing machine according to the present invention that achieves the above object is provided facing a moving printing material and disposed in a direction perpendicular to the conveyance direction thereof. an inkjet head that has a plurality of ink ejection ports and prints on a substrate with ink ejected from each ink ejection port in response to an applied pulse voltage; and an ink supply that supplies ink to the inkjet head. means, a speed detection means for detecting the moving speed of the printing medium, and application of a pulse voltage to the inkjet head while taking into consideration the speed detected by the speed detection means and the arrangement position of each of the ink discharge ports. is
The invention is characterized by comprising a control means for.

Effects> Whether ink droplets are ejected from each ink ejection port of the inkjet head and reaches the printing substrate depends on whether or not a pulse voltage corresponding to each ink ejection port is applied. Desired printing is performed on the printing material by applying a pulse voltage to each ink ejection port while taking into consideration the arrangement of each ink ejection port and the speed of the printing material detected by the speed detection means.

Example of implementation Hereinafter, the present invention will be explained based on examples.

FIG. 1 shows a schematic configuration of an operation in which printing on cardboard is performed using a non-contact printing machine according to an embodiment. As shown in the figure, a corrugated board 1 manufactured by a corrugator (not shown) is conveyed from the valve to the right in the figure by a vacuum conveying means 2 located above it. The vacuum conveying means 2 includes a pair of drive rolls 3a and 3b, a vacuum belt 4 driven by these, and a vacuum belt 4 provided opposite to the cardboard 1 on the side opposite to the side that contacts the cardboard 1. It has a plurality of vacuum boxes 5. The vacuum belt 4 has, for example, a mesh shape and is breathable, and the vacuum box 5 is designed to suck the cardboard 1 through the vacuum belt 4. Therefore, the cardboard 1 is connected to the vacuum belt 4
The vacuum belt 4 is moved together with the vacuum belt 4 in close contact with the vacuum belt 4. Note that a support roll 6 is disposed between each vacuum box 5 to prevent the vacuum belt 4 from shifting upward in the figure.

The color unit 7a of the inkjet head is located below the cardboard 1 being transported in this manner.

7b, 8a, 8b, 9a, 9b, 10a, and 10b are sequentially arranged in the transport direction. Here, each of the color units 7a to 10b has ink discharge ports extending in the width direction of the cardboard 1. For example, 7a and 7b are yellow ink, 8a and 8b are red ink, and 9a and 9b are ink discharge ports. Indigo ink, 10a and 10b are provided for black (black) ink and for different colors. That is, by using one set of color units 7a to 10a or color units 7b to 10b, full color printing is possible, and by using each set alternately, cleaning of one set can be done while the other is being used. etc. can now be done.

Here, detailed configurations of the color units 7a to 10b will be explained in detail with reference to FIGS. 2 to 4.

FIG. 2 shows a schematic configuration of each color unit 78 to 10b of this embodiment. As shown in the figure, each color unit 78 to 10b includes ten head blocks 11 (11
, ~111°) are arranged alternately in two stages so that the printable width a is continuous in the width direction, and each color unit 78 to 10b can print a range of width b (=10a). Further, each head block 11 has 128 heads 12 (12, to 1212.
) is 1 so that its printable width C is continuous in the width direction.
The head blocks 11 are arranged in four columns of 32 each, and a width of C×128 is the printable width a of each head block 11.

Each head 12 is an 8-dot type, that is, it has eight ink ejection ports in a printable width C, and its detailed configuration is shown in FIGS. 4(a) and 4(bl).As shown in both figures,
Eight ink discharge ports 13 are provided in a row at the tip of the head 12; each ink discharge port 13 is provided in the head 12.
Eight ink supply passages 14 communicating with the ink supply passages 3 are formed. All of the ink supply passages 14 communicate with an ink chamber 16 via a filter 15, and ink is supplied to the ink chamber 16 from an ink supply port 17 at the rear end. On the other hand, a piezoelectric element 18 is provided on the side surface of the head 12 in correspondence with each ink supply path 14. Each piezoelectric element 18 is wired to a connector 19 at the rear end, and a pulse voltage can be applied to each piezoelectric element 18 independently. When a pulse voltage is applied to the piezoelectric element 18, a volume change occurs in the ink supply path 14 corresponding to the piezoelectric element 18, and ink droplets are ejected on demand from the ink ejection port 13 at the tip of the ink supply path 14. They are one. That is, by controlling the application of pulse voltage to each piezoelectric element 18 in the head 12, desired printing is possible in the range of the radius C where the ink ejection ports 13 are connected.

In the end, each color unit 78-1. Ob is provided with 1280 heads 12 as described above so that the printable width C thereof is continuous, and 8X1280=1
Printed with 0.240 dots. The connectors 19 of each head 12 are collected in each head block, and
As shown in the figure, the control signals are collected in a control signal collection connector 20 formed for each color unit, and each collection connector 2
0 is connected to the control device 21. Also, each head 1
Ink is supplied to each color unit 7a to 10b.
The ink feed tube collection connector 22 is connected to an ink tank (not shown) for each color.

The control device 21 is input with pattern information to be printed, that is, pattern information for each color separated by a color scanner, and pulses are sent to each head 12 in each color unit 7a to 10b according to this pattern information. The timing of voltage application is controlled. At this time, the voltage applied to each piezoelectric element 18 of each head 12 is taken into consideration, taking into consideration the positional deviation of each color unit 7a to 10b in the cardboard transport direction and the positional deviation of each head 12 in each color unit 78 to 10b. timing is controlled.

Further, the timing of application of ink to each ink discharge port 13 of each head 12 must be determined in consideration of the transport speed of the cardboard 1. Therefore, a speed detecting device 2 such as a rotary encoder is installed at a position facing the drive roll 3a.
3 is provided. Furthermore, it is necessary to change the interval between ink droplets successively ejected from the ink ejection ports 13 of each head 12 depending on the conveyance speed of the cardboard 1. Therefore, the frequency of the pulse voltage applied to the piezoelectric element 18 of each head 12 is converted in accordance with the transport speed detected by the speed detection device 23. In addition,
Since the position at which the ejected ink droplets reach the cardboard 1 differs depending on the thickness of the cardboard 1, the vacuum conveying means 2 is configured, for example, in order to keep the distance between each color unit 78 to 10b and the cardboard 1 constant. It can be moved up and down in FIG. 1 within a range of several millimeters.

Each head block 1 in each color unit 78 to 10b
1 are each removable, and each head 12 in each head block 11 is also removable, providing convenience for cleaning, replacement, etc.

Furthermore, each head block 11 must be cleaned periodically or based on instructions from an abnormality detection system, which will be described later. Therefore, below each of the color units 78 to 10b, a corresponding leaning unit 24 is provided. During cleaning, each head block 11 is rotated 180 degrees by an arm (not shown) provided in the cleaning unit 24, and then cleaned by suction by a vacuum device (not shown). Served. Such cleaning is performed for each color unit 7a to 10b, for example, every 15 minutes. As a result, the actual M T B F (Mean Tim
e Between Failure) can be significantly extended. Note that the cleaning unit 24 does not necessarily have to be provided corresponding to each color unit 78 to 10b.
If the lower part of each color unit 7a-10b is made movable, for example, only one color unit may be required.

On the other hand, a dot detection device 25 is provided to monitor dot omission in each of the color units 78 to 7b. For this dot extraction, the detection device 25 prints markers using all the dots on each stamp surface, and
1-2 This is for monitoring the printing status of one line, and COD etc. are used. When the dot removal is detected by the detection device 25, the head block number and head number are notified, and each color unit 7a to 10b%
It is designed to issue a command to switch to another set, and the head block or head with missing dots should be cleaned or replaced. Also, as mentioned above, the color with missing dots should be removed. Switching of the units may be performed for each color or simultaneously for gold.The detection system for such dot extraction is performed by the control device 21.Also, the marker line by all dot printing mentioned above is For example, it is desirable that the marker also serves as a marker for cutting in subsequent work.

In the printing machine described above, when the cardboard 1 is transported by the vacuum transport means 2, the inside of each color unit 7a to IOb is determined based on the printing pattern information inputted in advance to the control means 21 and the speed information detected by the speed detection device 23. A pulse voltage of an appropriately set frequency is applied to each head 12, and desired printing is performed fully automatically. This printing can be done in one color, two colors, or multiple colors.

At this time, even when printing specified colors, it can also be expressed by the distribution of each color on the surface, similar to normal multicolor printing. This eliminates the need to stock up on inks of various colors. On the other hand, if monochromatic printing with a designated ink is particularly required, printing can be performed with one color unit using that ink. In addition, there is no need to make a plate by simply inputting a printing pattern to the control device 21, and different printing can be performed continuously without changing the plate.

The cardboard 1 printed in this way is printed without contact,
Since it is not subjected to printing pressure, it does not suffer from any strength deterioration.

Therefore, by subsequently performing non-contact cutting and scoring using a laser cutter or the like, it becomes possible to manufacture a corrugated box with no deterioration in strength at all. Of course, after the above-described printing, the sheet may be cut into a cut sheet in the conventional manner, and then cut using a die or the like.

Note that the above-described printing machine can print not only on corrugated cardboard as it is produced by a corrugator but also on cut sheet cardboard, and can also print on various printing materials other than cardboard.

Further, in the above-described embodiment, a pressure control type head 12 is used, but of course, other types such as an electric field control type or a charge control type head can also be used. When these types of heads are used, the voltage application to the electrodes for deflecting the ejected ink may be controlled.

Further, in the above-described embodiments, a contact type was used as the speed detection device for the printing material, but a non-contact type may be used, and it goes without saying that the detection system for dot extraction is not limited to the one described above. .

<Effects of the Invention> As explained above, according to the non-contact printing machine according to the present invention, it is possible to print at high speed in a non-contact state even on large substrates, and there is no need to replace the second printing plate. Nor. Therefore, it can be applied to, for example, corrugated board printing, and can also meet the demand for small quantities of a wide variety of products.When printing on corrugated board, it also has the effect of preventing a decrease in strength due to collapsing of the corrugated board. play.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the schematic configuration of the color unit, FIG. 3 is an explanatory diagram showing the schematic configuration of the head block, and FIG. The figure is an explanatory diagram showing the configuration of the head. In the drawing, 1 is cardboard, 5-6 2 is a vacuum conveyance means, 3a, 3b are drive rolls, 4 is a vacuum belt, 5 is a vacuum box, 7a, 7b are color units, 8a, 8b are color units, 9a, 9b is color unit l-1 10a, 1. Ob is the color unit, 11 (11, ~ 111°) is the head block, 12 (1
2, ~ 1212B) is a helad, 13 is an ink discharge port, 14 is an ink supply path, 15 is a filter, 16 is an ink chamber, 17 is an ink supply port, 18 is a piezoelectric element, 19 is a connector, 20 is a control signal set 21 is a control device, 22 is an ink feed tube collection connector, 23 is a speed detection device, 24 is a cleaning unit, and 25 is a dot detection device.

Claims (1)

[Claims] It has a plurality of ink ejection ports that are arranged to face the moving printing material and extend in a direction perpendicular to the conveyance direction thereof, and ink is ejected from each of the ink ejection ports in accordance with the applied pulse voltage. an inkjet head for printing on a substrate with ink, an ink supply means for supplying ink to the inkjet head, a speed detection means for detecting the moving speed of the substrate, and a speed detected by the speed detection means. A non-contact printing machine characterized by comprising: a control means for controlling application of a pulse voltage to the inkjet head while taking into consideration the arrangement position of each of the ink ejection ports.