JP2003311915A - On-board drawing lithographic printing method, and equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing method which can draws with a correct image dot density despite dispersion in the ink flying characteristics of an ink discharge means. <P>SOLUTION: This drawing lithographic printing method on board is contrived to discharge lipophilic inks from a plurality of ink discharge means under an ink jet system using an imaging means, which records a gradation by converting the density level to the size of each of recording dots, in manufacturing a printing plate by directly forming an image on a printing material mounted on a plate cylinder and performing a lithographic printing process under the described state. In the method, ink discharge means arrangement data showing the correspondence between each of the image dots and each of the discharge means to a plurality of the image dots are created, and the respective discharge means corresponding to the respective image dots are determined referring to the arrangement data. Further, the ink discharge amount control value of each of the image dots is determined using a discharge characteristics table of an image dot density and the ink discharge amount control value which are experimentally predetermined as corresponding to the described discharge means, so that the recording dot size corresponding to each of image dot densities of the corresponding discharge means can be obtained. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing method for performing digital plate making on a printing machine, and more specifically,
The present invention relates to a plate-making / printing method and a printing apparatus having good plate-making image quality and print image quality using an ink containing at least a lipophilic component.

[0002]

2. Description of the Related Art In planographic printing, ink-receptive and ink-repellent areas are provided on the surface of a printing plate corresponding to an image original, and printing is performed by adhering printing ink to the ink-receptive areas. Usually, hydrophilic and lipophilic (ink receptive) areas are formed in an image-like manner on the surface of the printing plate, and the hydrophilic areas are made to be ink repellent by using fountain solution.

Recording of an image on a printing original plate (plate material) (plate making)
First outputs the image original in an analog or digital format to a silver salt photographic film, exposes the diazo resin or photopolymerizable photopolymer photosensitive material through this, and elutes and removes the non-image area mainly using an alkaline solution. It is a common method to do it.

In recent years, in the planographic printing method, due to recent demands for improvement of digital drawing technology and process efficiency,
Many systems for directly drawing digital image information on a printing plate have been proposed. This is a CTP (Comput
er-to-plate) or DDPP (Dig
ital Direct Printing Plating
This is a technology called e). As a plate-making method, for example, there is a system for recording an image in an optical mode or a thermal mode by using a laser, and a part of the system has been put into practical use.

However, in this plate-making method, in both the optical mode and the heat mode, generally, after laser recording, the plate-making is carried out by treating with an alkaline developing solution to dissolve and remove the non-image area,
Alkaline waste liquid is discharged, which is not preferable for environmental protection.

Further, there is a method using the above-mentioned laser, but it is expensive and requires a large apparatus. Therefore, a system applying the inkjet method, which is an inexpensive and compact drawing device, has been tried.

Japanese Unexamined Patent Publication (Kokai) No. 64-27953 discloses a method in which a lipophilic wax ink is used on a hydrophilic plate material to perform drawing with an ink jet to make a plate. In this method, the plate material is disposable, but the ink ejection stability is high.

Further, Japanese Patent Laid-Open No. 11-70632 discloses a method in which a hydrophilic plate material is drawn with an ink jet using an aqueous solution or an aqueous colloidal dispersion of a hydrophobic organic acid salt to carry out plate making. ing.

However, in the above method, since it is necessary to manually install the plate material on the plate cylinder of the offset printing machine after the plate making, it takes a long time to load, especially when printing a plurality of colors. Is likely to cause color misregistration.

Further, as a means for improving the efficiency of the printing process, there is a system for applying an ink jet method to draw an image on a printing machine.

In JP-A-4-97848, a plate drum having a hydrophilic or lipophilic surface is provided in place of the conventional plate cylinder, and a lipophilic or hydrophilic image is formed on the plate drum by an ink jet method. However, there is disclosed a method of removing the image after completion of printing and cleaning the image. However, with this method, it is difficult to achieve both removal of the printed image (that is, ease of cleaning) and printing durability.

As described above, when the ink jet system is applied to the plate making process, the developing process which is necessary in the conventional plate making work becomes unnecessary, and therefore, the merit of further simplification of the system, running cost reduction, plate making time reduction, etc. Occurs.

However, the ink jet method has a drawback that the drawing speed is slow, and by changing the size of the drawing dot by adjusting the ink ejection amount and the ejection time,
It is necessary to reduce the resolution while maintaining the required number of gradations and improve the drawing speed.

Attempts have also been made to further improve efficiency by simultaneously using two or more ink ejecting means.
In this case, by using the interlaced scanning method, it is possible to draw an image with a dot interval smaller than the interval of the ink ejecting means. However, when a plurality of ink ejection means are used at the same time, drawing unevenness occurs due to a slight difference in ejection characteristics. Therefore, it is necessary to manufacture ink ejection means having the same ejection characteristics, resulting in an increase in apparatus cost. It was

Further, in the case of the ink jet system for forming an image by superimposing adjacent recording dots, a combination of ink ejecting means corresponding to adjacent recording dots is obtained due to a slight recording position deviation characteristic of each ink ejecting means. As a result, the overlapping amount of adjacent recording dots may change, and the image density may differ. This will be described with reference to FIG. In FIG. 7, it is assumed that there are the ink ejecting means 1 and the ink ejecting means 2, and the ink ejecting characteristic of the ink ejecting means 1 tends to be slightly deflected to the right on the paper surface from the landing target position. It is assumed that it is exactly at the target point of impact. Figure 7
(A) shows a case where two normal ink ejecting means 2 are adjacent to each other. In this case, of the two ink ejecting means, the dot 2L recorded by the ejecting means 2 on the left side and the dot 2R recorded by the ejecting means 2 on the right side on the paper are both landed at the landing target position, and therefore two dots are formed. The area Sa where 2L and 2R overlap has a target area. On the other hand, FIG. 7 (b)
Is a case where two ink ejection means 1 which tend to be deflected to the right are adjacent to each other, and the dot 1 recorded by the ejection means 1 on the left side
Both L and the dot 1R recorded by the right ejection unit 1 are eccentric from the target landing position. In this case, if the eccentricity amounts are the same, the overlapping portion Sb will be the same amount as Sa. On the other hand, FIG. 7C shows the case where the ink ejecting means 1 is adjacent to the left side and the ink ejecting means 2 is adjacent to the right side in the drawing. In this case, the dot 1L recorded by the left ejection unit 1
Is eccentric to the right from the landing target position, and the center of the dot 2R recorded by the ejection means 2 on the right side is the landing target position.
Therefore, in this case, the overlapping portion Sc becomes wider than the predetermined area. On the contrary, FIG. 7D shows a case where the ink ejecting means 2 is adjacent to the left side and the ink ejecting means 1 is adjacent to the right side in the drawing. In this case, the dot 1L recorded by the right ejection unit 1 is eccentric to the right from the landing target position, and the center of the dot 2R recorded by the left ejection unit 2 is the landing target position. Therefore, in this case, the overlapping portion Sc becomes narrower than the predetermined area. If there is an increase or decrease in the dot overlap area due to the flight characteristics of the ink ejecting means,
There is a drawback that a predetermined concentration cannot be obtained.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a digital-compatible lithographic printing method and printing apparatus that do not require development processing. Is to provide. Secondly, a lithographic printing method and a printing apparatus that perform image drawing by an inkjet method that realizes high-speed drawing with accurate image dot density by an inexpensive device and a simple method even if there are variations in the flight characteristics of the ink ejection means. Is to provide.

[0017]

According to the invention of an on-press drawing lithographic printing method as set forth in claim 1, a plate material is mounted on a plate cylinder of a printing machine,
An on-press lithographic printing method of forming a printing plate by directly forming an image on the plate material on the basis of a signal of image data, and then performing lithographic printing using the plate material in that state, Two or more ink ejecting means capable of ejecting ink containing at least a lipophilic component simultaneously or sequentially by using an image forming means for converting the density level of each image dot into a recording dot size and performing gradation recording. In the on-press drawing lithographic printing method in which an image is formed on the printing plate by an inkjet method of ejecting from each of the plurality of image dots of the image, a correspondence between each image dot and each ink ejection means The ink ejection means array data shown is prepared in advance, the ink ejection means array data is referenced to find the ink ejection means corresponding to each image dot, and the ink ejection means array By using the ejection characteristic table of the image dot density and the ink ejection amount control value that have been experimentally obtained in advance, it is possible to obtain the recording dot size corresponding to each image dot density of the corresponding ink ejecting means that has been obtained. In addition, the ink discharge amount control value of each image dot is determined. According to another aspect of the present invention, there is provided a plate material mounting unit for mounting a plate material on a plate cylinder of a printing machine, and an image forming apparatus for directly forming an image on the plate material based on a signal of image data. Means, a fixing means for fixing the image formed on the plate material, and an on-board lithographic printing apparatus for performing lithographic printing using the fixed plate material in that state, wherein the image forming means comprises: Two or more ink ejections in which the density level of each image dot of image data is converted into a recording dot size and gradation recording is performed, and ink containing at least a lipophilic component can be ejected simultaneously or sequentially In an on-board drawing lithographic printing apparatus that is of an inkjet type that is ejected from a means, the correspondence between each image dot and each ink ejection means is stored in advance in memory for all or some of a plurality of image dots of an image. Ink ejecting means array data, ink ejecting means selecting means for obtaining ink ejecting means corresponding to each image dot by referring to the ink ejecting means array data, and ink ejecting means prepared for each ink ejecting means Of the ink discharge amount control value corresponding to the image dot density to be recorded, which is experimentally obtained in advance, and the discharge characteristic table stored in the memory and the ink discharge means selected by the ink discharge means selecting means are recorded. And an ink discharge amount control value determining means for determining an ink discharge amount control value for a print dot of a target size by using this discharge characteristic table.

As another invention, the following configuration can be considered. (1) In the on-press drawing plate making method according to claim 1, the ink first ejection means corresponding to each image dot is obtained using the ink ejection means array data, and the ejection characteristic table of the corresponding ink first ejection means is obtained. When the ink ejection amount control value is determined using, the ink second ejection means corresponding to the image dot adjacent to the corresponding image dot is also obtained, and the ink first
The ejection characteristic table of the ejection unit and the ink first obtained in advance
The ink ejection amount control value of the recording dot corresponding to the image dot is determined by using the dot overlap correction table when the recording dots recorded by the ejection unit and the second ink ejection unit are adjacent to each other. (2) In the above-described on-press drawing plate making method, dust existing on the surface of the plate material is removed and / or at least the plate making is carried out before and / or during drawing on the plate material by the ink jet method using an ink discharge means. After the end, cleaning of the ink ejection means is performed. (3) In the on-press drawing planographic printing apparatus according to claim 2,
A dot overlap correction table that corrects the error in the recording dot area due to the overlap of adjacent recording dots,
And a third control arithmetic unit that corrects the density of the corresponding image dot using this dot overlap correction table. (4) In the above-mentioned on-press drawing lithographic printing apparatus, the direct image forming means includes plate material surface dust removing means for removing dust existing on the surface of the plate material before and / or during drawing on the plate material. ing. (5) In the above-described on-press drawing lithographic printing apparatus, at the time of drawing on the plate material, the image forming means performs main scanning by rotating the plate cylinder on which the plate material is mounted. (6) In the above-described on-press drawing lithographic printing apparatus, the image forming means performs sub-scanning by moving the ink ejecting means in the axial direction of the plate cylinder during drawing on the plate material. (7) In the above-described on-press drawing lithographic printing apparatus, the image forming means is composed of a full line head having a length substantially the same as the width of the plate cylinder. (8) In the above-mentioned on-press drawing lithographic printing apparatus, the ink jet recording device brings the ink ejecting means close to the plate material when drawing on the plate material, and the ink ejecting means is operated except when drawing on the plate material. An ink ejecting means separating / contacting means for separating from the plate cylinder is provided. (9) In the above-described on-press drawing lithographic printing apparatus, the direct image forming means includes an ink ejecting means cleaning means for cleaning the ink ejecting means at least after completion of plate making. (10) In the above-described on-press drawing lithographic printing apparatus, the lithographic printing means includes a paper dust removing means for removing paper dust generated during lithographic printing.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The present invention forms an image on a plate material (printing original plate) provided on a plate cylinder of a printing machine by an inkjet method of discharging an ink containing at least a lipophilic component,
Using a plurality of ink ejecting means, the density error caused by the combination of the adjacent ink ejecting means is corrected by referring to the ink ejecting means array data created in advance, and the ink ejection amount is calculated from the ejection correction table according to the ink ejecting means to be used. The control value is obtained and drawn.

As the ink jet method according to the present invention, any method can be used as long as the ink containing the lipophilic component can be ejected. Specifically, for example, the "Imaging part 2 latest hard copy printer technology" edited by the Electrophotographic Society of Japan Chapter 3 Photo Industry Publishing Co. (1988), edited by Hiroshi Komon "Handbook for Recording and Storage Technology" Maruzen Co., Ltd. (199
2 years), the piezo method, the thermal jet method, the electrostatic method, the discharge method, etc. described in the publications can be used.
Further, JP-A-10-175300 and JP-A-6-239.
86, JP-A-5-131633, and JP-A-10-11.
4073, JP-A-10-34967, and JP-A3-1.
No. 04650, JP-A No. 8-300803, and the like, which are applied or combined, are also preferably used. As described above, according to the present invention, when plate making is performed on a printing machine by the inkjet method, a plurality of ink ejecting means are used to correct the characteristics of each ink ejecting means. Thus, it becomes possible to print a large number of high-quality printed matter.

An example of the construction of an on-press drawing lithographic printing apparatus used for carrying out the lithographic printing method of the present invention is shown below.

FIGS. 1 to 3 are general construction diagrams of an on-press drawing single-color one-sided lithographic printing apparatus. FIG. 4 is a schematic configuration example of a drawing unit including a control unit, an ink supply unit, and an ink ejecting means separation / contact mechanism of the on-machine drawing lithographic printing apparatus. FIG. 6 shows an example of the overall configuration of an on-machine drawing 4-color single-sided lithographic printing apparatus according to the present invention.

First, the printing process according to the present invention will be described with reference to the entire construction diagram of the on-press drawing single-color one-sided lithographic printing machine shown in FIG. As shown in FIG. 1, an on-press drawing lithographic printing apparatus 1 (hereinafter also referred to as “printing apparatus”) has a plate cylinder 11, a blanket cylinder 12 and an impression cylinder 13, and at least when performing lithographic printing. Is arranged so that a transfer blanket cylinder 12 is pressed against the plate cylinder 11, and an impression cylinder 13 for transferring the printing ink image transferred onto the blanket cylinder 12 is pressed against the blanket cylinder 12. Are arranged as follows. FIG. 2 shows another example of the configuration of the printing apparatus according to the present invention, which is entirely covered by the hood F. The hood F has an intake port I and an exhaust port O, and a dustproof filter is attached to the intake port I and the exhaust port O. It is desirable to install a fan or the like in the hood to forcibly perform intake and exhaust. In addition, a removal device may be attached so that solvent vapor used for ink described later does not come out to the outside of the hood, so that the solvent vapor is not discharged to the outside, and a convenient printing device that does not cause problems such as odor generation. Can be Although the entire printing apparatus is covered with the hood F in FIG. 2, the hood may cover only a part of the printing apparatus as shown in FIG. 3, and the present invention is not limited to this embodiment.

The plate cylinder 11 is usually made of metal, and its surface is plated with, for example, chrome in order to enhance wear resistance, but it may have a heat insulating material on its surface as described later. .

Further, the printing apparatus 1 has an ink jet recording apparatus 2, which allows the image data calculation control unit 21 to operate.
Ink corresponding to the image data sent from the plate material 9 mounted on the plate cylinder 11 is ejected onto the plate material 9 to form an image area.

Further, the printing apparatus 1 is provided with a dampening water supply device 3 for supplying dampening water to the hydrophilic portion (non-image portion) on the plate material 9. In FIG. 1, a Molton water supply system is shown as a representative example of the dampening water supply device 3, but as the dampening water supply device 3, other known devices such as a Shinflo water supply system and a continuous water supply system can be used. Further, the printing device 1
It has a printing ink supply device 4 and, if necessary, a fixing device 5 for strengthening the ink image drawn on the plate material 9. Further, if necessary, the plate surface desensitizing device 6 may be installed for the purpose of enhancing the hydrophilicity of the surface of the plate material 9. Further, the printing apparatus 1 has means 10 for removing dust existing on the surface of the plate material before or / and during drawing on the plate material. As the dust removing means, a known non-contact method such as suction removal, blow-off removal, electrostatic removal, or the like, and a contact method using a brush, a roller, or the like can be used. In the present invention, either air suction or air blow-off is preferable. , Or a combination of them. In this case, the air pump normally used in the paper feeding device can be used for this purpose.

Further, an automatic plate feeder 7 for automatically supplying a plate material 9 for printing onto the plate cylinder 11 and an automatic plate discharge device 8 for automatically removing the plate material 9 after printing from the plate cylinder 11. May be installed and is known as an auxiliary device of a printing machine.
34A, B452A (Hamada Printing Machinery Co., Ltd.), Toko 8000PFA (Tokyo Aircraft Instrument Co., Ltd.), Ryobi 3
200ACD, 3200PFA (Ryobi Imagix Co., Ltd.), AMSIS Multi5150FA (Japan AM Co., Ltd.), Oliver 266EPZ (Sakurai Graphic Systems Co., Ltd.), Shinohara 66 ■ / P (Shinohara Shoji Co., Ltd.), etc. . Further, a blanket cleaning device 14 and an impression cylinder cleaning device 14 'may be installed. By using these devices 7, 8 and 14, the printing operation becomes simpler and the printing time can be shortened, so that the effect of the present invention can be further enhanced. Further, it is preferable to install a paper dust generation preventing device 15 in the vicinity of the impression cylinder 13, so that the paper dust adhered on the plate material can be prevented. As the paper dust generation prevention device 15, methods such as humidity control, suction by air or electrostatic force can be used.

The image data arithmetic control unit 21 receives image data from an image scanner, a magnetic disk device, an image data transmission device, etc., and performs color separation, and an appropriate number of pixels and gradation for the separated data. Divide into numbers. Further, the dot area ratio is also calculated in order to draw the ink image as halftone dots by using the ink ejecting means 22 (see FIG. 4, which will be described later in detail) included in the inkjet recording apparatus 2. In addition, the ink ejection means array data is created from the number of mounted ink ejection means, the interval, and the drawing method, and the ink ejection means corresponding to the image data is obtained from this ink ejection means array data, and the density error due to the overlapping of adjacent dots is calculated. The image density is corrected using the dot overlap correction table that is the data to be corrected, and the image data is corrected using the ejection characteristic table that associates the image dot density with the ink ejection amount control value, which corresponds to the ink ejecting means. Is converted into an ink ejection amount control value.

Further, as will be described later, the image data calculation control section 21 controls the movement of the ink ejecting means 22 and the ink ejection timing, and, if necessary, the plate cylinder 11,
It also controls the operation timing of the blanket cylinder 12, the impression cylinder 13, and the like.

A plate making process by the printing apparatus 1 will be described in detail below with reference to FIG. 1 and a part of FIG.

First, the plate material 9 is mounted on the plate cylinder 11 using the automatic plate feeder 7. At this time, the plate material is adhered and fixed on the plate cylinder by a mechanical method such as a known plate edge / edge gripping device, an air suction device, or an electrostatic method, which causes the plate edge to flutter and be drawn at the time of drawing. It is possible to prevent the inkjet recording device 2 from coming into contact with and being damaged. It is also possible to prevent the plate material from coming into contact with the inkjet recording device by providing a means for bringing the plate material into close contact with the plate cylinder only around the drawing position of the inkjet recording device and operating this at least when drawing is performed. . Specifically, for example, there is a method of arranging a pressing roller upstream and downstream of the plate cylinder drawing position. Further, by providing a means for preventing the plate edge from coming into contact with the ink supply roller in the process of fixing the plate, it is possible to prevent the plate surface from being soiled and reduce the wasted paper. Specifically, a pressing roller, a guide, or electrostatic attraction is effective.

Image data from the magnetic disk device, etc.
The image data calculation control unit 21 is provided, and the image data calculation control unit 21 calculates the ejection position of the ink containing the lipophilic component and the halftone dot area ratio at that position according to the input image data, and the dot overlap correction table. After the image density is corrected by, the image data is converted into an ink ejection amount control value using the ejection characteristic table of each ink ejecting unit. These calculation data are temporarily stored in the buffer. The image data arithmetic control unit 21 rotates the plate cylinder 11, and causes the ink ejecting means 22 to move by the ink ejecting means separating / connecting device 31.
And move closer to the position. The distance between the ink ejecting means 22 and the surface of the plate material 9 on the plate cylinder 11 is being drawn by a mechanical distance control such as an abutting roller or a head separation / contact device controlled by a signal from an optical distance detector. , Is kept at a predetermined distance. A multi-channel head or a full line head can be used as the ink ejecting means 22, and main scanning is performed by rotating the plate cylinder 11. The arrangement direction of the multi-channel head having a plurality of ejection parts or the full line head ejection part is arranged in the axial direction. Further, in the case of a multi-channel head, the image data calculation control unit 21 moves the ink ejection means 22 in the axial direction of the plate cylinder 11 every one rotation of the plate cylinder 11 to obtain the ejection position and the ink ejection amount obtained by the above calculation. Ink is ejected onto the plate material 9 mounted on the plate cylinder 11 at a control value. At this time, the ink discharge amount control value is converted into a voltage value, a current value, a charge amount, a heating temperature, a heating heat amount, a time for outputting these, or the like, and is input to the ink discharging means to discharge the ink. As a result, a halftone image corresponding to the shading of the printing original is drawn on the plate material 9 with ink. This operation continues until an ink image for one color of the printing original is formed on the plate material 9 and the printing plate is completed. On the other hand, when the ink ejecting means 22 is a full line head having a length substantially the same as the width of the plate cylinder, one rotation of the plate cylinder forms an ink image for one color of the printing original on the plate material 9. A printing plate is completed. By performing the main scanning by rotating the plate cylinder in this manner, it is possible to improve the position accuracy in the main scanning direction and perform high-speed drawing.

Next, in order to protect the ink ejecting means 22, the ink ejecting means 22 is retracted away from the position close to the plate cylinder 11. At this time, only the ink ejecting means 22 may be brought into and out of contact, but the ink ejecting means 22
It is also possible to separate and contact the ink discharging means and sub-scanning means 32 together, or to separate and contact all the ink discharging means 22, the ink supply unit 24 and the ink discharging means sub-scanning means 32 together.
In addition to the ink ejecting unit 22, the ink supplying unit 24, the ink ejecting unit sub-scanning unit 32, the fixing unit 5 and the dust removing unit 10 are also provided with contacting and detaching units so that they can be retracted, so that normal printing can be supported. .

This separating / connecting means operates so that the ink discharging means is separated from the plate cylinder by at least 500 μm or more except during drawing. The detaching / attaching operation may be performed by a sliding type, or the head may be fixed by an arm fixed to a certain axis and the arm may be moved around the axis to move like a pendulum. By retracting the ink ejecting means during non-drawing in this way, the ink ejecting means can be protected from physical damage or contamination and a long life can be achieved.

Further, the formed ink image is strengthened by heating, exposure and the like in the fixing device 5, if necessary. As the ink fixing means, known means such as heat fixing, solvent fixing, flash exposure and UV irradiation fixing can be used. In heat fixing, halogen lamp irradiation, hot air fixing using a heater, or heat roll fixing is generally used. In this case, in order to improve the fixing property, the plate cylinder is heated, the plate material is preheated, drawing is performed while applying hot air, the plate cylinder is coated with a heat insulating material, and the plate cylinder is only fixed. It is effective to separate the plate material from the above and heat only the plate material, alone or in combination. In the solvent fixing, a solvent capable of dissolving the resin component in the ink, such as methanol or ethyl acetate, is sprayed, and excess solvent vapor is collected. Further, flash fixing using a xenon lamp or the like is known as a fixing method for electrophotographic toner, and has an advantage that fixing can be performed in a short time. In addition, at least from the ink image formation by the ink ejecting means 22, the fixing device 5
It is desirable that the dampening water supply device 3, the printing ink supply device 4, and the blanket cylinder 12 be kept out of contact with the plate material 9 on the plate cylinder in the process up to fixing by.

The printing process after forming the printing plate is the same as the known lithographic printing method. That is, printing ink and dampening water are applied to the plate material 9 on which the ink image containing the lipophilic component is drawn to form a printing image, and the printing ink image is formed on the blanket cylinder 12 rotating with the plate cylinder 11. Then, the printing ink image on the blanket cylinder 12 is transferred onto the printing paper P passing between the blanket cylinder 12 and the impression cylinder 13 to print one color. The plate material 9 after printing is removed from the plate cylinder 11 by the automatic plate discharging device 8, and the blanket on the blanket cylinder 12 is cleaned by the blanket cleaning device 14 to be ready for the next printing.

Reference numeral 20a is a digital control means provided for the purpose of further improving the operability of the printing apparatus, and examples thereof include an ink usage amount display device and a plate inspection device. The ink usage amount display device displays the required amount of ink in advance based on the image data, and is very effective in the case of continuously performing plate making as in the present printing device. Moreover, since this device performs on-machine drawing, plate inspection cannot be performed. The plate inspection device compensates for the drawback. That is, the image drawn on the plate is detected by a CCD camera or the like installed in the machine, and the image is displayed on the monitor to enable plate inspection. At that time, it is possible to further improve the plate inspection property by digital processing as compared with visual inspection.

Next, the ink jet recording apparatus 2 will be described in detail. As shown in FIG. 4, the drawing unit used in the planographic printing apparatus includes a plurality of ink ejecting units 22,
It is composed of an ink ejection means protection means 20b and an ink supply section 24. The ink ejection unit protection unit includes a foreign substance adhesion prevention unit for the ink ejection unit, a drawing stop unit when an abnormality occurs, and the like. The foreign substance adhesion prevention unit includes, for example, an ink ejection unit protection cover. That is, when the drawing is not performed, the ink ejecting means is housed in the cover to prevent the adhesion of the foreign matter. FIG. 5 shows an embodiment of the cover according to the present invention. As shown in FIG. 5, the ink ejecting means is housed in a cover with a shutter, the shutter is opened at the time of drawing, and the ink ejecting means is moved to the drawing position. Move forward and draw. Ink or
It is also possible to fill the ink solvent, and in that case, even if the drawing is not performed for a long period of time, it is possible to prevent the trouble due to the sticking of the ink to the ink ejection means. As the drawing stop means upon occurrence of an abnormality, for example, a dust sensing device or an abnormal current sensing device of the head is connected to the image data arithmetic control unit 21, and when an abnormal signal from the device is generated, the ink ejection device By providing the mechanism for stopping the voltage signal, it is possible to prevent the ink ejection means from being damaged.

On the other hand, the ink supply section 24 further includes an ink tank 25, an ink supply device 26, and an ink density control means 2.
Have 9. The ink tank may include a stirring unit 27 and an ink temperature management unit 28, if necessary. In this case, the stirring means 27 suppresses precipitation / aggregation of the solid components of the ink. The ink temperature management unit 28 is arranged so that a high-quality image can be stably formed without changing the physical properties of the ink due to changes in the surrounding temperature and the dot diameter. Further, when drawing with high image quality, the ink density control means 29 is arranged as necessary. The ink density is measured by optical detection, measurement of electrical properties, measurement of physical properties such as viscosity, or control by the number of drawn images. When controlling by measuring physical properties, an optical detector, electric conductivity measuring device, viscosity measuring device are provided individually or in combination in the ink tank or ink flow path, and the output signal determines the number of images drawn. In the case of management by the method described above, the liquid supply from the replenishing concentrated ink tank or the diluting ink carrier tank (not shown) to the ink tank is controlled depending on the number of plates and the frequency.

As described above, the image data calculation control section 21 calculates the input image data, moves the ink discharging means by the ink discharging means separating / contacting device 31, or the ink discharging means sub-scanning means 32, and also the plate. The timing pulse from the encoder 30 installed on the cylinder is taken in, and the ink ejection means is driven according to the timing pulse. As a result, the positional accuracy in the sub-scanning direction can be improved. Further, it also controls the above-mentioned ink ejection means protection means 20b. Further, the position accuracy in the sub-scanning direction can be improved by using a high-precision driving means different from the driving means at the time of printing for performing the drawing by the inkjet recording device. It is desirable to drive only the plate cylinder by mechanically separating it from the impression cylinder and the like. Specifically, for example, there is a method in which the output from a high-precision motor is decelerated by a high-precision gear, a steel belt or the like to drive only the plate cylinder. When performing high-quality drawing, such means are used alone or in combination.

The ink ejecting means 22 may include a maintenance device such as a cleaning means, if necessary. For example, if the printer stays idle or if there is a problem with the image quality, wipe the tip of the ink ejector with a flexible brush, brush, cloth, circulate only the ink solvent, or supply only the ink solvent. Alternatively, a good drawing state can be maintained by performing a single means or a combination of means such as sucking the discharge portion while circulating. Further, in order to prevent the ink from sticking, it is effective to cool the ink discharging means to suppress the evaporation of the ink solvent. When the dirt is severe, ink is forcibly sucked from the discharge part, or air, ink, or a jet of ink solvent is forced into the ink flow path, or ultrasonic waves are applied while the head is immersed in the ink solvent. Is also effective, and these methods can be used alone or in combination.

Next, a method of determining the ink discharge amount control value will be described. First, ink ejection means array data describing which ink ejection means draws a recording dot on an output image is created in advance from the recording dot density, the ink ejection means interval, and the ink ejection means scan feed pitch. FIG. 8 is a diagram illustrating an example of a method of creating the ink ejection unit array data. In FIG. 8, the ink ejecting means H is four unit ejecting means (heads) H1,
The recording medium P consists of continuous channels of H2, H3, and H4. At the beginning of recording, the position shown in FIG.
It is assumed to be at the upper left position of. When the recording medium P moves in the direction of the white arrow in the figure, the ink ejecting means H moves relative to the recording medium P in the illustrated main scanning direction. At this time, the ejection means H1 can perform recording on the column indicated by 1 on the recording medium P. Similarly, the ejection means H2 is indicated on the column indicated by 2 on the recording medium P, and the ejection means H3 is indicated on the column indicated by 3 on the recording medium P. The ejecting means H4 can record on the columns indicated by 4 on the recording medium P, respectively. After the ink ejection means H has recorded up to the recording end portion in the main scanning direction M, the recording medium P then returns to the position of FIG. 8A, the ink ejection means H moves in the sub scanning direction, and the ejection means H1 performs recording. It stops when it moves to the unrecorded column next to the column indicated by 4 on the medium P. FIG. 8B shows this state. Then, when the recording medium P moves in the direction of the white arrow in the drawing, the ink ejecting means H moves relative to the main scanning direction M again, while the ejecting means H1 is in the row indicated by 1 on the recording medium P and the ejecting means H2 is the recording means. The ejection means H3 is in the column indicated by 2 of the medium P, the ejection means H3 is in the row indicated by 3 of the recording medium P, and the ejection means H3 is
4 can be recorded in the columns indicated by 4 on the recording medium P. Similarly, by continuing the recording in this manner, as shown in FIG.
As shown in (c), ink ejection means array data indicating which ejection means is in charge of recording is obtained for each pixel arranged vertically and horizontally in the main and sub-scanning directions of the recording medium P.

There is a method of preparing this ink ejection means array data corresponding to all the image dots of the input image, but depending on the arrangement of the ink ejection means and the scanning method, the ink ejection means may be ejected in the main scanning direction or the sub-scanning direction. When the arrangement of the means does not change, it is sufficient to prepare only one line of arrangement data and use it repeatedly.

FIG. 9 is a view for explaining another example of the method of creating the ink ejection means array data. In FIG. 9, the ink ejecting means H includes four unit ejecting means H1, H2, H.
3 and H4 are arranged one channel apart from each other, and they are located at the position of FIG. 9A at the beginning of recording, that is, at the upper left position of the recording medium P. Then, the recording medium P moves in the direction of the white arrow in the figure, whereby the ink ejecting means H relatively moves in the illustrated main scanning direction, while the ejecting means H1 records at the position indicated by 1 on the recording medium P, and so on. The ejecting means H2 jumps to the position indicated by 2 in the sub-scanning direction for one channel of the recording medium P, similarly the ejecting means H3 moves to the position indicated by 3 of the recording medium P, and the ejecting means H4 moves to the recording medium P.
The recording is performed at the positions indicated by 4 in the above, each position being skipped by one channel. When the ink ejecting means H has recorded up to the end portion in the main scanning direction M, the recording medium P is then changed to the one shown in FIG.
Returning to the position of (a), the ink ejecting means H moves in the sub-scanning direction of FIG. 9B so that the ejecting means H1 comes to the unrecorded position next to the already recorded position 1 of the recording medium P, and the ink is again ejected. While the ejecting means H moves in the main scanning direction M, the ejecting means H1 moves to the position indicated by 1 on the recording medium P, the ejecting means H2 moves to the position indicated by 2 on the recording medium P, and the ejecting means H3 moves on the recording medium P3. Recording is performed at the position indicated by 4 and by the ejection means H4 at the position indicated by 4 on the recording medium P. By continuing the printing in this manner, ink ejection means array data indicating which ejection means performs the printing for each pixel arranged in the vertical and horizontal directions of the recording medium P as shown in FIG. 9C is obtained.

Next, an ejection characteristic table is experimentally created for each of all the ink ejecting means. The ejection characteristic table is defined in each ink ejection unit.
It is a table that associates the image dot density to be drawn with the ink ejection control value. By using the ejection characteristic table, the ink ejection control value capable of outputting the recording dot size corresponding to the target image dot density can be obtained.

As a method of creating the discharge characteristic table,
For example, the grayscale image A in which the drawing dot density is gradually changed for every arbitrary number of dots as shown in FIG. 10A is an overall view of the gray scale image A, FIG. 10B is an enlarged view of a high density portion, and FIG. 10C is an enlarged view of a low density portion.
Therefore, as shown in the figure, the grayscale image A in which the drawing dot density is gradually changed for each arbitrary number of dots is used as input data, and only the target ink ejecting means is used, and a temporary ejection characteristic table, for example, the image minimum density is used. From the maximum density to the image, the ink ejection control value also linearly decreases from the maximum value to the minimum value, or increases from the minimum value to the maximum value. The image density of the recorded dots drawn with the ink ejection control value obtained in this way is measured. A true ejection characteristic table is created from the measured image density and the corresponding ink ejection control value. Cx: Density of image dot x CM: Measured density of recorded dot x TEtemp (C): Temporary ejection characteristic table TEi (C): Ink ejection characteristic table TEi (CM) = TEtemp (Cx)

Grayscale image A used at this time (see FIG.
0) accurately obtains the relationship between the measured density of the print dots and the ink ejection control value, it is necessary that each print dot does not overlap with other print dots.
As in (b) [High-density scale] and (c) [Low-density scale], image dots are arranged in a grid pattern every 1 dot or more, and the minimum density dot, for example, white dot (+ mark in the figure) is placed between them. ).

Next, a dot overlap correction table is experimentally created in advance. The dot overlap correction table is data for correcting an error in the recording dot size due to the overlap of the adjacent recording dots. As a method of creating the dot overlap correction table, for example, a grayscale image B in which the drawing dot density is gradually changed for every arbitrary number of dots as shown in FIG.
Is drawn by two ink ejecting means 1 and 2 that draw adjacent recording dots, and the measured density of the drawn recording dots and the grayscale image C drawn without being adjacent so that the recording dots do not overlap (FIG. 12 (e))
The dot overlap correction table is created by using the density difference from the measured density of the recording dots of No. 2 as a table value having the ink ejection control values of the two used ink ejecting means as indexes.

FIG. 11 shows a case where two ink ejection means 1 and 2 which are adjacent to each other are recorded in the same line.
The gray scale image B shown in (e) is a large dot recorded by the ink ejecting means 1 from the top to the bottom of the vertical axis to a small dot, and a large dot recorded by the ink ejecting means 2 from the left to the right on the horizontal axis.
It changes with small dots. Therefore, FIG. 11 (a) shows a high-concentration portion in which both dodds are large and overlap, (b)
In both (c) and (c), one dot is large and the other dot is small and overlaps with each other in a critical density medium density area, and (d) shows both low density areas where both dots are small and there is no overlapping area.

FIG. 12 shows a case where two ink ejecting means 1 and 2 which are adjacent to each other are recorded alternately in each row.
The gray scale image B shown in 2 (e) is a large dot to a small dot recorded by the ink ejecting means 1 from the top to the bottom of the vertical axis.
From the left to the right on the horizontal axis, the large dots to the small dots recorded by the ink ejecting means 2 change. Therefore, FIG. 12A shows the case where both the dodds are large, FIGS. 12B and 12C show the case where one is large and the other is a small dot, and FIG. 12D shows the case where both the dodds are small. The feature is that there is no overlap. Thus, according to the present invention, regardless of whether the dot position is normal or not,
The reason for using the image without dot overlap as shown in FIG. 12 is to correct the dot overlap between adjacent ink ejecting means, and the reason for using the image without dot overlap as shown in FIG. 12 is that the dot overlap method according to the present invention does not overlap the dots. This is because the image density of is used as a reference. This is because the overlap correction table is prepared from the image density of each dot obtained from the ejection characteristic table of each ink ejecting means and the actually measured image density. TCi-j (Cx, Cy): recording dot x of measured density Cx drawn by the ink ejecting means i and recording dot y of measured density Cy drawn by the ink ejecting means j located on the left side thereof
And dot overlap correction table C Mol: measurement of recording dots x and y drawn so as to be adjacent to each other Cdensity: measurement of recording dots x and y drawn with a space so that they cannot overlap Concentration TCi-j (Cx, Cy) = Cx x (CMop-CMol) / CMop

The grayscale image B at this time (see FIG.
1) is 1 between the dots which are not overlapped so that the respective recording dots drawn by the two ink ejecting means 1 and 2 can overlap at only one place.
A dot with the lowest density equal to or higher than the dot, for example, a white dot is arranged.

First, the procedure for correcting the density error due to the overlap between the recording dots will be described. In FIG. 13, first, with respect to the image dot a of the input image data to be output, the ink ejection unit 1 for drawing the image dot a is obtained by referring to the ink ejection unit array data. further,
The ink ejection means array data is also referred to find the ink ejection means for drawing on each of the adjacent recording dots b, c, d, e (for the dots b, d, the ink ejection means 1, for the dots c, e). Is the ink ejecting means 2.), and the density correction values ΔCa-b, ΔCa-c, and ΔC using the dot overlap correction tables corresponding to them.
Then, a−d and ΔCa−e are obtained and added to the density of the image dot a to obtain the corrected density. ΔCa-b: recording dot a of measured density Ca and measured density C
Overlap density correction value ΔCa-c of recording dot b of b: recording dot a of measured density Ca and measured density C
Overlap density correction value ΔCa-d of recording dot c of c: recording dot a of measured density Ca and measured density C
Overlap density correction value ΔCa-e of recording dot d of d: recording dot a of measurement density Ca and measurement density C
Overprint density correction value Ca 'of the recording dot e of e: correction density Tci-i (Cx, Cy) of the image dot a: recording dot x of the measured density Cx drawn by the ink ejecting means i and recording of the measured density Cy Dot overlap correction table TCi-j (Cx, Cy) with dot y: recording of measured density Cx drawn by ink ejecting means i and recording of measured density Cy drawn by ink ejecting means j located on the left side thereof Dot y
Dot overlap correction table with ΔCa-b = Tc1-1 (Ca, Cb) ΔCa-c = Tc1-2 (Ca, Cc) ΔCa-d = Tc1-1 (Ca, Cd) ΔCa-e = Tc2-1 (Ce, Ca) Ca ′ = Ca + ΔCa−b + ΔCa−c + ΔCa−d +
ΔCa−e As described above, the dot overlap correction table is
It is a two-dimensional table in which the input is the dot density of two adjacent dots (the dot density drawn by a single ink ejecting means without overlapping) and the output is the dot correction density, and the two target ink ejecting means are adjacent and overlap each other. Measure the density difference when dots are drawn with or without (drawing using each ejection characteristic table obtained in advance), and measure the measured density difference (that is, density loss due to dot overlap) for each dot. Calculate the dot correction density distributed at the density ratio,
The dot correction density becomes a dot overlap correction table (for the density of two drawn dots).

Next, the procedure for determining the ink discharge amount control value will be described. FIG. 14 shows an outline of the procedure for determining the ink discharge amount control value according to the present invention. Figure 1
4A shows input data (image dot density) of each pixel, FIG. 14B shows ink ejection means array data, and FIG.
14C is an image dot correction density of each pixel corrected using the dot overlap correction table according to the present invention, FIG. 14D is an ejection characteristic table of the ink ejecting means 1, and FIG. 14E is each pixel. Represents the ink ejection amount control value. Therefore, for each image dot a of the image data to be output (for example, the dot a in the first row, first column), first, the ink ejection unit array data (FIG. 14B) is referred to The ink ejection means for drawing is determined (in the figure, the ink ejection means 1 is in charge of the dot a in the first row, first column). On the other hand, the density of the input data of the image dot a (value 28 in FIG. 14A) is corrected as follows. First, using the ink ejection means array data of FIG. 14B, an ink ejection means for drawing the target dot a and an ink ejection means for drawing a dot adjacent to the target dot a are obtained (here, ink ejection means). Means 1 and 2), based on the formula of the correction density Ca ′ of the image dot a, obtain the overlap density correction value using the dot overlap correction table between the dots adjacent vertically and horizontally to the target dot a, The overlap density correction values thus obtained are all added to the target dot a density, and this is set as the corrected density of the target dot. Here, the corrected density (value 30 in FIG. 14C) is obtained. Then, using the ejection characteristic table of the ink ejecting means (here, the ink ejecting means 1) that draws the target dot a, the above-described corrected density of the target dot (see FIG. 14) is used.
The ink ejection amount control value (FIG. 14) for the value 30 in (c).
The value of (e) 1.5) is calculated. Ea: Ink ejection amount control value TEi (C) of recording dot a of measured density Ca: Ejection characteristic table Ca 'of ink ejecting means i: Corrected density Ea = TE1 (Ca') of image dot a

Next, an on-press drawing multicolor planographic printing machine will be described as a specific example of the present invention. FIG. 6 shows an example of the overall configuration of an on-press drawing four-color single-sided lithographic printing press. As shown in FIG. 6, the four-color single-sided printing device is basically a plate cylinder 11, a blanket cylinder 12, and an impression cylinder 1 of the single-color single-sided printing device shown in FIG.
It is a structure having four 3 so that printing is performed on the same side of the printing paper P. Although not shown,
To transfer the printing paper indicated by K in the figure between the adjacent impression cylinders,
A known transfer cylinder method or the like is used. Although detailed description is omitted, as easily imagined from the example of FIG. 10, the other multicolor single-sided printing devices are basically the plate cylinder 11 of the single-color single-sided printing device.
The blanket cylinder 12 and the impression cylinder 13 are provided in a plural number so that printing is performed on the same side of the printing paper P. When only one color plate is prepared on the plate cylinder, the number of colors to be printed It has a plate cylinder and a blanket cylinder by the amount. (Such a printing device is referred to as a unit-type printing device.) On the other hand, a common impression cylinder type that shares one impression cylinder having a diameter that is an integral multiple of the impression cylinder diameter with respect to the plate cylinders and blanket cylinders for a plurality of colors. When the present invention is carried out in a printing apparatus, it is possible to have a structure in which one impression cylinder is shared by the number of printing colors and blanket cylinders, or one impression cylinder is used for multiple color plate cylinders and blanket cylinders. A structure having a plurality of shared structures and having a total number of plate cylinders and blanket cylinders for the number of colors to be printed may be used. In this case, the printing paper is delivered between the adjacent common impression cylinders by the above-mentioned known transfer cylinder. Use the method.

On the other hand, when a plurality of color plates are formed on the plate cylinder, the plate cylinder and the blanket cylinder are required by the number of colors to be printed divided by the number of plates on one plate cylinder. For example, when a plate material for two colors is created on the plate cylinder, it is possible to perform one-sided four-color printing with a printing machine having two plate cylinders and two blanket cylinders. In this case, the impression cylinder diameter is the same as the plate cylinder diameter for one color,
If necessary, a means for holding the printing paper until the printing of the required colors is completed is installed in the impression cylinder, and a known transfer cylinder method or the like is used to transfer the printing paper between the impression cylinders. For example, in the case of a printing machine having two plate cylinders and two blanket cylinders for which the above-described plate materials for two colors are created, when one impression cylinder holds the printing paper and makes two rotations, two-color printing is performed. When the printing paper is transferred between the impression cylinders, and then the other impression cylinder holds the printing paper and rotates twice, two-color printing is further performed and four-color printing is completed. Further, the number of impression cylinders may be the same as that of the plate cylinder, but one plate cylinder may be shared by several plate cylinders and blanket cylinders.

On the other hand, when the present invention is embodied as an on-press drawing multicolor double-sided lithographic printing machine, a known printing paper reversing means is provided between at least one adjacent impression cylinder of the above-mentioned unit type printing apparatus, or A structure in which a plurality of the above-mentioned common impression cylinder type printing devices are arranged and a known printing paper reversing means is provided between at least one adjacent impression cylinders, or the plate cylinder 11 and the blanket cylinder 12 of the single-color single-sided printing device shown in FIG. Is provided so that printing is performed on both sides of the printing paper P. In the case of the latter structure, printing is performed on both sides of the printing paper when only one color plate is created on the plate cylinder. It has plate cylinders and blanket cylinders for the number of colors required for printing. On the other hand, when a plurality of color plates are formed on the plate cylinder as described above, the number of plate cylinders, blanket cylinders, and impression cylinders can be reduced. Further, when several impression cylinders and blanket cylinders share one impression cylinder, the number of impression cylinders can be further reduced. If necessary, the plate cylinder is provided with a means for holding the printing paper until printing of the required colors is completed. The details are omitted because they can be easily analogized by the example of the above-described on-press drawing multicolor one-sided lithographic printing machine.

An example of a sheet-fed printing press has been described above as an embodiment of the on-press drawing multicolor lithographic printing press of the present invention. On the other hand, when the present invention is embodied as an on-press drawing multicolor WEB (rolling paper) lithographic printing machine, the above-mentioned unit type and common impression cylinder type can be preferably used. When the present invention is embodied as an on-press drawing multi-color WEB (rolling paper) double-sided printing machine, a known WEB reversing means is provided between at least one adjacent impression cylinders for both the unit type and the common impression cylinder type. It can be achieved by a structure having a plurality of sheets so that both sides of the printing paper P can be printed. Further, the BB (blanket to blanket) type is most suitable as the on-machine drawing multicolor WEB (rolling paper) double-sided printing machine. This is a one-color plate cylinder for printing one side of the WEB, a blanket cylinder (no impression cylinder) and a one-color plate cylinder for printing the other side, a blanket cylinder (also no impression cylinder). Has a structure in which the blanket cylinders are pressed against each other during printing for the number of colors, and the space between the pressed blankets during printing is W
Multi-color double-sided printing is achieved by passing the EB.

Further, as another example of the on-press drawing lithographic printing machine, it is possible to have two plate cylinders per blanket cylinder and to print on the other plate cylinder while printing on the other hand. . In this case, it is desirable that the driving of the plate cylinder performing drawing is mechanically independent of the blanket. As a result, it becomes possible to perform drawing without suspending the printing press. As can be easily analogized, this can also be applied to an on-press drawing multicolor one-sided lithographic printing machine and an on-press drawing multicolor two-sided lithographic printing machine.

Although not described in order to avoid duplication, the hood, the digital control means, and the ink ejection means protection means are appropriately used in all printing devices to improve the operability of the printing devices.

Next, the plate material (printing original plate) used in the present invention will be described.

Examples of the printing original plate include metal plates such as aluminum and a chrome-plated steel plate. An aluminum plate is particularly preferred because it has excellent water retention and abrasion resistance due to graining and anodizing. As a cheaper plate material, a plate material provided with an image receiving layer on a water-resistant support such as paper to which water resistance is imparted, a plastic film, or a paper laminated with plastic can be used. The thickness of this plate is 100
The range of ˜300 μm is suitable, and the thickness of the image receiving layer provided therein is suitable in the range of 5˜30 μm.

As the image receiving layer, a hydrophilic layer composed of an inorganic pigment and a binder, or a layer which can be rendered hydrophilic by a desensitizing treatment can be used.

As the inorganic pigment used in the hydrophilic image receiving layer, clay, silica, calcium carbonate, zinc oxide, aluminum oxide, barium sulfate or the like can be used. As the binder, polyvinyl alcohol, starch,
A hydrophilic binder such as carboxymethyl cellulose, hydroxyethyl cellulose, casein, gelatin, polyacrylic acid salt, polyvinylpyrrolidone, polymethyl ether-maleic anhydride copolymer can be used, and water resistance is imparted if necessary. Melamine formalin resin, urea formalin resin, and other crosslinking agents may be added.

On the other hand, examples of the image receiving layer used after desensitizing treatment include a layer using zinc oxide and a hydrophobic binder.

The zinc oxide to be used in the present invention is, for example, as described in “New Edition Facial Medicine Handbook” edited by the Japan Facial Technology Association, page 319, Seibundou Co., Ltd. (published in 1968). Any of those commercially available as flower, wet zinc flower, or activated zinc flower may be used.

That is, zinc oxide is classified into a dry method, which is called a French method (indirect method), an American method (direct method), and a wet method, depending on a starting material and a manufacturing method, for example, Shodo Kagaku Co., Ltd., Sakai. Chemical Co., Ltd., Shiramizu Chemical Co., Ltd.,
Examples include those commercially available from companies such as Honjo Chemical Co., Ltd., Toho Zinc Co., Ltd., and Mitsui Kinzoku Kogyo Co., Ltd.

As the resin used as the binder, specifically, vinyl chloride-vinyl acetate copolymer, styrene-
Butadiene copolymer, styrene-methacrylate copolymer, methacrylate copolymer, acrylate copolymer,
Examples thereof include vinyl acetate copolymer, polyvinyl butyral, alkyd resin, epoxy resin, epoxy ester resin, polyester resin, polyurethane resin and the like. These resins may be used alone or in combination of two or more.

The resin content in the image receiving layer is preferably 9/91 to 20/80 in terms of resin / zinc oxide weight ratio.

For desensitizing zinc oxide, conventionally, as this type of desensitizing treatment liquid, a ferrocyanine salt, a cyanide-containing treatment liquid containing ferricyanide as a main component, an amminecobalt complex, phytic acid and its derivatives are used. A cyan-free treatment liquid containing a guanidine derivative as a main component, a treatment liquid containing an inorganic acid or an organic acid forming a chelate with zinc ions as a main component, or a treatment liquid containing a water-soluble polymer is known.

For example, as a cyanide-containing treatment liquid,
Japanese Patent Publications No. 44-9045, No. 46-39403, No. 52-76101, No. 57-107889, No. 5
4-117201 etc. are mentioned.

The surface of the plate material opposite to the image receiving layer is
The Beck's smoothness is preferably in the range of 150 to 700 (sec / 10 cc). As a result, good printing can be performed on the printing plate without causing misalignment or slippage on the plate cylinder even during printing.

The Beck's smoothness can be measured by a Beck's smoothness tester. Beck's smoothness tester presses a test piece at a constant pressure (1 kgf / cm ² ) on a circular glass plate with a hole in the center that has been finished to a highly smooth surface. It measures the time required for air to pass between the glass surface and the test piece.

The lipophilic component contained in the ink of the present invention is preferably a hydrophobic resin or wax having a good affinity with the ink solvent. The hydrophobic resin may be dissolved in the ink solvent or may be dispersed as a solid.

When the resin is used as the lipophilic component, the weight average molecular weight Mw of the resin is 1 × 10 ² to 1 × 10 ⁶ , preferably 5 × 10 ² to 8 × 10 ⁵ , and more preferably 1. It is x10 < ³ > -5 * 10 < ⁵ >.

Specific examples of such a resin include olefin polymers and copolymers (for example, polyethylene, polypropylene, polyisobutylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, ethylene-methacrylate copolymer). , Ethylene-methacrylic acid copolymers, etc.), vinyl chloride polymers and copolymers (eg,
Polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, etc.), vinylidene chloride copolymer, vinyl alkanoate polymer and copolymer, allyl alkanoate polymer and copolymer, polymer and copolymer of styrene and its derivatives. Polymer (for example, butadiene-styrene copolymer, isoprene-styrene copolymer, styrene-methacrylate copolymer, styrene-acrylate copolymer, etc.), acrylonitrile copolymer, methacrylonitrile copolymer, alkyl vinyl ether copolymer Copolymers, acrylic acid ester polymers and copolymers, methacrylic acid ester polymers and copolymers, itaconic acid diester polymers and copolymers, maleic anhydride copolymers, acrylamide copolymers, methacrylamide copolymers, Phenolic resin, alkyd resin, polycarbonate Resin, ketone resin, polyester resin, silicone resin, amide resin, hydroxyl group and carboxyl group modified polyester resin, butyral resin, polyvinyl acetal resin, urethane resin, rosin resin, hydrogenated rosin resin, petroleum resin, hydrogenated petroleum resin, malein Acid resin, terpene resin, hydrogenated terpene resin, coumarone-indene resin, cyclized rubber-methacrylic acid ester copolymer, cyclized rubber-acrylic acid ester copolymer, copolymer containing nitrogen atom-free heterocycle A compound (for example, a furan ring, a tetrahydrofuran ring, a thiophene ring, a dioxane ring, a dioxofuran ring, a lactone ring, a benzofuran ring, a benzothiophene ring, a 1,3-dioxetane ring, and the like), an epoxy resin, and the like can be given.

The content of the dispersed resin in the ink of the present invention is preferably 0.5 to 20 wt% of the total ink. When the content is low, problems such as deterioration of printing durability tend to occur. On the other hand, when the content is high, it is difficult to obtain a uniform dispersion liquid, or ink is easily clogged in the ejection head. However, there is a problem that it is difficult to obtain stable ink ejection.

On the other hand, examples of the use of wax as a lipophilic component include compounds used in solid ink jet, which are disclosed in JP-A-2-69282, JP-A-5-186723 and JP-A-6-206368, U.S. Pat. Nos. 3653932, 3715219, and 4
No. 390369, No. 4484948, No. 465938
No. 3, No. 4684956, No. 4830671, No. 4
889560, 4889761, 499230
No. 4, No. 5084099, PCT publication WO91 / 10
No. 711, etc.

In the ink to be used in the present invention, it is preferable to include a coloring material as a coloring component together with the above-mentioned dispersed resin particles in order to inspect the plate after plate making.

As the color material, any pigment and dye conventionally used in ink compositions or liquid developers for electrostatic photography can be used.

As the pigment, regardless of whether it is an inorganic pigment or an organic pigment, those generally used in the technical field of printing can be used. Specifically, for example, carbon black, cadmium red, molybdenum red, chrome yellow, cadmium yellow, titanium yellow, chromium oxide, viridian, cobalt green, ultramarine blue, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment. In particular, conventionally known pigments such as quinacridone pigments, isoindolinone pigments, dioxazine pigments, slene pigments, perylene pigments, perinone pigments, thioindigo pigments, quinophthalone pigments, and metal complex pigments are particularly limited. Can be used without any.

As the dyes, azo dyes, metal complex salt dyes,
Naphthol dye, anthraquinone dye, indigo dye,
Dyes such as carbonium dyes, quinone imine dyes, xanthene dyes, aniline dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes and metal phthalocyanine dyes are preferable.

These pigments and dyes may be used alone or in an appropriate combination, but they are contained in the range of 0.01 to 5% by weight based on the whole ink. desirable.

The present invention is described in detail below with reference to examples, but the contents of the present invention are not limited to these.

EXAMPLE An ink jet recording apparatus mounted on four plate cylinders of a single-sided four-color printing apparatus (see FIG. 6) has a share mode of 50.
A 0-channel piezo inkjet device (Xaar Jet500S manufactured by Xaar) was used, and oil-based ink (manufactured by the same company) or UV ink (manufactured by the same company) was used. The gap adjustment (gap 0.8 mm) is performed by a contact roller made of Teflon (registered trademark), the image data to be printed is transmitted to the image data calculation control unit, and the ejection characteristic table of each ink ejecting unit that is obtained in advance by experiments. Then, an ink ejection control value is obtained using a dot overlap correction table obtained by an experiment in advance, and the 500-channel ink ejection means is moved while rotating the plate cylinder.
Inks were simultaneously ejected onto the aluminum plates on one plate cylinder to form an image, and the oil-based ink and the UV ink were each subjected to plate making 500 times. When drawing, drawing resolution 360 dp
The gradation is expressed by changing the size of the dot in 8 steps to i. As a result, the drawing defects due to dust and the influence of changes in the outside temperature were not observed at all. Although there was some change in the dot diameter due to an increase in the number of plate making, it was within the range where there was no effect. When the UV ink was used, the plate made was cured by irradiation with a UV lamp (low pressure mercury lamp UL2-350USP manufactured by Ushio Inc.). As a result, an extremely clear full-color printed matter was obtained without skipping or blurring in the printed image even after passing 5,000 sheets. In particular, when UV ink was used, an extremely clear full-color printed matter was obtained without skipping or blurring in the printed image even after passing 20,000 sheets.

After the completion of plate making, the ejection portion of the ink ejection means is wiped with a non-woven paper and then stored in the cover to produce a good printed matter for 3 months without requiring maintenance work. did it.

[0086]

According to the present invention, it is possible to print a large number of printed matters having clear images. Further, a printing plate directly corresponding to digital image data can be stably produced with high image quality on a printing machine, and inexpensive and high-speed flat plate printing can be performed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram schematically showing an example of an on-press drawing monochromatic lithographic printing apparatus used in the present invention.

FIG. 2 is an overall configuration diagram schematically showing another example of the on-press drawing monochromatic lithographic printing apparatus according to the present invention.

FIG. 3 is an overall configuration diagram schematically showing another example of the on-press drawing single color lithographic printing apparatus according to the present invention.

FIG. 4 is a configuration diagram schematically showing an example of a drawing unit of the on-board drawing lithographic printing apparatus used in the present invention.

FIG. 5 is a configuration diagram schematically showing an embodiment of an ink ejection unit protection cover used in the present invention.

FIG. 6 is an overall configuration diagram schematically showing an on-press drawing four-color single-sided lithographic printing machine as an example of a multicolor machine according to the present invention.

FIG. 7 is a schematic diagram showing that when the adjacent recording dots are drawn, the overlapping manner of the recording dots changes due to the difference in the characteristics of the ink ejecting means used for drawing each.

FIG. 8 is a schematic diagram showing an example of a scanning method of an ink ejection unit and corresponding ink ejection unit array data.

FIG. 9 is a schematic view showing another example of the scanning method of the ink ejecting means and another example of the ink ejecting means array data corresponding thereto.

FIG. 10 is a schematic diagram showing an example of a grayscale image used when experimentally obtaining the ejection characteristic table and the dot overlap correction table in the present invention. FIG. 10A is an overall view of the grayscale image A,
(B) is an enlarged view of a high density part and (c) is an enlarged view of a low density part.

FIG. 11 shows a case where two ink ejecting means adjacent to each other are recorded in the same row. FIG. 11A shows a high density portion in which both doddles are large and overlaps, and FIGS. 11B and 11C show In each case, one is large and the other is a small density medium area where dots overlap each other in a critical state, (d) shows a low density area where both dods are small and there is no overlap area, and (e) shows a grayscale image. .

FIG. 12 shows a case where two ink ejection means adjacent to each other are alternately printed in each row, and FIG. 12 (a) shows a high-density portion having large overlapping portions in both dods, (b) and (c). Shows a medium density part where one dot is large and the other dot is small and overlaps each other in a critical state, (d) is a low density part in which both dots are small and has no overlapping part, and (e) is a grayscale image. There is.

FIG. 13 is a schematic diagram showing an example of overlapping of adjacent recording dots.

FIG. 14 is a schematic diagram of a method of obtaining an ink ejection amount control value using an ejection characteristic table.

[Explanation of symbols]

1 On-board drawing lithographic printing system 2 Inkjet recording device 3 Dampening water supply device 4 Printing ink supply device 5 Fixing device 6 Plate desensitizing device 7 Plate material automatic plate feeder 8 Automatic plate discharge device 9 Plate material (printing original plate) 10 Dust remover 11 plate cylinder 12 blanket torso 13 impression cylinder 14 Blanket cleaning device 14 'impression cylinder cleaning device 15 Paper dust generation prevention device 20a Digital control means 20b Ink ejection means protection means 21 Image data calculation controller 22 Ink ejection means P printing paper F food

Claims (2)

[Claims] 1. A plate material is mounted on a plate cylinder of a printing machine, an image is directly formed on the plate material based on a signal of image data to form a printing plate, and the plate material is continuously used in that state. An on-press lithographic printing method for performing lithographic printing, comprising using an image forming means for converting the density level of each image dot of the image data into a size of a recording dot and recording the gradation by using at least a lipophilic component. In an on-press drawing lithographic printing method for forming an image on the printing plate by an inkjet method in which the contained ink is ejected from two or more ink ejecting means capable of ejecting simultaneously or sequentially, plural images of all or part of the image Ink ejection means array data indicating the correspondence between each image dot and each ink ejection means for a dot is created in advance, and the ink ejection means array data is referenced to refer to the ink ejection means array data corresponding to each image dot. Image of each corresponding ink ejecting means obtained by utilizing the ejection characteristic table of the image dot density and the ink ejection amount control value obtained experimentally in advance corresponding to the ink ejecting means. An on-machine drawing lithographic printing method characterized in that an ink ejection amount control value of each image dot is determined so that a recording dot size corresponding to a dot density can be obtained. 2. A plate material mounting means for mounting a plate material on a plate cylinder of a printing machine, an image forming means for directly forming an image on the plate material based on a signal of image data, and an image forming means formed on the plate material. A fixing means for fixing an image, and an on-press lithographic printing apparatus for performing lithographic printing using the fixed plate material in that state,
The image forming means converts the density level of each image dot of the image data into a recording dot size and performs gradation recording, and can eject ink containing at least a lipophilic component simultaneously or sequentially. Correspondence between each image dot and each ink ejecting unit in advance for all or a part of plural image dots of an image in an on-press drawing lithographic printing apparatus which is of an ink jet system for ejecting from two or more ink ejecting units And an ink ejecting means selecting means for obtaining ink ejecting means corresponding to each image dot by referring to the ink ejecting means array data,
An ejection characteristic table stored in a memory by experimentally obtaining a relationship with an ink ejection amount control value corresponding to an image dot density recorded by each ink ejecting means prepared for each ink ejecting means, and the ink ejecting table. An ink discharge amount control value determining means for determining an ink discharge amount control value for a recording dot of a target size to be recorded by the ink discharging means selected by the means selecting means, using the discharge characteristic table. A special on-press drawing planographic printing device.