JPS61163344A - Exposure method - Google Patents

Abstract

PURPOSE:To prevent the abrasive fog due to a contact screen (CS) and the damage of the CS by using a copying camera, to and from which the CS can be attached and detached, to expose an original, on which continuous tone pictures and line pictures exist together, on one sensitive material in a light room by a specific operation. CONSTITUTION:In the method where the original on which continuous tone pictures and line pictures exist together is exposed twice through a lens 8 of a light room-type copying camera to form exposed image on a sensitive material 2, the material 2 is set to an exposure part having an approximately vertically provided attracting mechanism 4; and if the first exposure is performed for photographing of continuous tone pictures, a CS7 is moved from the position facing the sensitive material 2 and is brought closely into contact with the sensitive material 2 to expose the original, and the CS7 is moved in a machine to the position facing the sensitive material 2 and off the exposure part while holding the sensitive material 2 as it is, and the second exposure is performed. If the first exposure is performed for line pictures, the CS7 which is placed in the position facing the sensitive material 2 and off the exposure part is moved while holding the sensitive material 2 as it is after the first exposure, and the CS7 is brought closely into contact with the sensitive material 2, and the second exposure for continuous tone pictures is performed. Thus, a planographic plate which has a high resolving capacity, a high print resisting capacity, and a high color reproducibility is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Q. Industrial Field of Application The present invention relates to a method of exposing a photosensitive material, and in particular to the production of continuous-tone images using a so-called bright-room type plate-making camera that allows exposure and processing operations to be performed under bright room light. The present invention relates to a method of exposing an original containing a mixture of line images and line images to a photosensitive lithographic printing plate for direct plate making.

■ Prior art and its problems Today, a wide variety of lithographic printing plates are known and put into practical use. Examples include presensitized plates (so-called 28 plates) using diazonium compounds, electrophotographic printing plates using zinc oxide or organic photoconductors, and silver salt photolithographic printing plates using silver halide emulsions. It is listed as a typical example. However, like the latter two, lithographic printing plates with high photosensitivity can be easily and quickly made using an automatic plate-making machine, from photographing the original to be printed to processing. It has become rapidly popular as a lithographic printing plate suitable for the Tokoroura direct plate making method.

In particular, lithographic printing plates for direct plate making using silver salt as a photosensitive component are useful because they have extremely high photosensitivity, contrast, and resolution.

Lithographic printing plates for direct plate making have such excellent properties and have improved in quality, but to date, it has been difficult to convert continuous tone color originals such as multicolor photographs to rainbow multicolor printed matter using direct plate making. There may be various reasons why this has not been commercialized, but one important one is that 28
This is considerably inferior to the image reproduction ability and printing durability of the plate.

In other words, while the 28th plate can achieve high image reproducibility by contact printing from expensive lithographic film as an intermediate manuscript, the direct plate making method can only obtain poor image reproducibility because it is photographed with a camera through a lens. The fact that there is no such thing is a well-known retrogression. Furthermore, JP-A-48-8
As described in 9007, a prepress camera has a built-in prism or reflective mirror in order to obtain correct prints on the left and right sides of the image, but this prism or reflective mirror does not affect the optical properties and may 9 is known to deteriorate image reproducibility. All of the cameras for plate making that are in widespread use today use a method of photographing using reflected light. Therefore, the originals to be used include characters and lines created with high-contrast image-forming materials using light-impermeable supports such as phototypesetting paper and positive paper produced by silver complex diffusion transfer. It is only a so-called reflected image of an image obtained by converting a continuous tone image such as a photograph into a halftone image (this is called a halftone image), and these reflected images are assembled into a desired composition and printed. The reality was that it was a preliminary draft.

When such a halftone dot reflection image plate is used as a manuscript and is directly plate-made using a silver halide lithographic printing plate or an electrophotographic lithographic printing plate, there are 980 halftone dots per inch, or at most 100 dots per inch. Point images could only be reproduced to an acceptable level for practical purposes.

Therefore, in conventional multicolor direct plate making,
Not only was it necessary to create multiple black and white dot reflection images using panchromatically spectrally sensitized continuous tone film for color separation or film as a draft for color printing, but also Even if color printing is performed using a lithographic printing plate obtained by direct plate making using a reflective plate original containing a mixture of halftone images and line images, only color printed images with unsatisfactory image reproducibility are obtained.
The printing durability was also not sufficient.

It is proposed in Japanese Patent Application No. 59-21221 that these problems can be solved by a method of color separation exposure by directly contacting a contact screen to a lithographic printing plate having a photosensitive layer that is spectrally sensitized in a panchromatic manner. This method itself is now well known.

However, in this known method, the contact screen and the lithographic printing plate are superimposed on a transparent platen installed horizontally, and after exposure is performed from the underside of the platen, the contact screen is manually pulled out of the machine. When the contact screen is pulled out or inserted, it rubs against the photosensitive surface of the lithographic printing plate, causing scratches, fogging, and background stains on the lithographic printing plate.
There was a drawback to adding an l. This drawback is that the constituent layers of the lithographic printing plate have a thickness of several μm (for example, 2 to 2 μm) for the purpose of improving water retention.
This is particularly noticeable when containing fine powders (10 μm), for example silica particles.

In addition, in multicolor direct plate making, multiple plates such as cyan, magenta, yellow, and black plates are overprinted, so continuous tone images (e.g., color photographs) and line images (e.g., text) are printed overlappingly. ) cannot be photographed with high positional accuracy on a lithographic printing plate, or printed matter with good color reproducibility cannot be produced.

Bright room plate making cameras on the market today include those set on an exposure platen that is installed approximately vertically and equipped with a suction mechanism, such as those shown in Japanese Patent Application Laid-Open No. 56-70542 and 1983-204032. There is a type of photosensitive material in which a preset contact screen is moved and brought into close contact with the photosensitive material for image exposure. However, since these plate-making cameras originally take line images and continuous tone images on separate photosensitive materials, under bright room light, the above two types of images are combined into one line image and halftone image. It was not possible to expose photosensitive materials.

0 Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and uses a copying camera in which a contact screen can be attached and detached by a simple operation under bright room light, and is capable of producing continuous-tone images and line images. One object of the present invention is to provide an exposure method that can expose an original containing a mixture of photosensitive materials to one photosensitive material Kjtl, and can prevent scratches and fog caused by a contact screen of the photosensitive material and damage to the contact screen.

In addition to the above objects, another object of the present invention is to provide a method for obtaining a lithographic printing plate with high resolution and high printing durability, and in particular, a multicolor color direct plate making method capable of obtaining a printing plate with good color reproducibility. It provides law.

■) Structure of the Invention The above-mentioned objects of the present invention are to image an original containing a mixture of continuous tone images and line images onto a photosensitive material by first exposure and second exposure through the lens of a bright room type copying camera. A method of exposing, in which the photosensitive material is conveyed and set to an exposure unit provided approximately vertically and equipped with a suction mechanism, and when the first exposure is to capture a continuous tone image, (a ) Moving the contact screen from the opposite side of the photosensitive material to bring it into close contact with the photosensitive material and imagewise exposing it, and then (b-1) moving the contact screen from the opposite side of the photosensitive material to the opposite side of the photosensitive material while holding the photosensitive material in that state, and Either move the contact screen on the plane so it is out of the exposure area, or
(b-2) After moving the contact screen to face the photosensitive material within the machine, the photosensitive material is brought into a light state that can be released during the second exposure, and during the second exposure, the contact screen is At least it does not exist in the happy light range, and continues (o)
? applying a second exposure of the fMIm image; if the first exposure is a line image, (4') applying the first exposure;
(1/-1) While holding the photosensitive material in that state, move the contact screen located outside the exposure area facing the photosensitive material and bring it into close contact with the photosensitive material, or <b'-
2) Bring the photosensitive material into a light-shielding state that can be released when it comes into close contact with the contact screen, move the contact screen from the opposite side of the photosensitive material and bring it into close contact with the photosensitive material, and then (G') This was achieved using a photosensitive material exposure method consisting of the following two exposures.

Hereinafter, the present invention will be explained in more detail using FIG. 1, which is shown as an example of a typical plate-making camera used in the method of the present invention.

In this specification, facing the photosensitive material means not only the case where the photosensitive material and the contact screen are in a positional relationship where they can be brought into close contact with each other by horizontal movement, as shown in FIG.
The contact screen may be located apart from the photosensitive material and on the lower, upper, left, or right side of the photosensitive material. This means that any position that does not give substantial sliding friction to the surface is good. Furthermore, moving within the machine means moving within the copying camera so as not to expose the photosensitive material to bright room light. In addition, the 1st Fukumitsu and the 2nd JL! Light refers to so-called main exposure, in which a continuous tone image and a line image of the original are taken separately, but it also means so-called sub-exposure, such as flood exposure, highlight exposure, back exposure from the back of the original, etc. may be further applied as necessary.

(E) Embodiment FIG. 1 is an example of a plate-making camera suitable for carrying out the present invention of a direct plate-making method using a photosensitive lithographic printing plate, and shows the main parts thereof. The size of each element, position, and position are exaggerated for understanding.

Multicolor color direct g printing method? In order to carry out the experiment, a photosensitive lithographic printing plate (2) as follows is produced.

A silver chlorobromide gelatin emulsion containing 3 mol of silver bromide was prepared by a conventional method for producing photosensitive lithographic printing plates. This silver halide has an average grain size of 0.4 μm.
After chemical sensitization, the following dye f1j~(3) was added to perform panromantic optical sensitization. Stabilizers, hardeners, and coating agents were added to the values.

An antihalation layer of carbon black containing silica particles with an average particle size of 7 μm, hydroquinone and phenidone was provided on a subbed-treated polyester film of 100 μm, and the emulsion layer (AgNo a 15 g/m
We have established one.

Dye (1): 901F/silver halide 1 mol dye (
2): 7ooq/silver halide 1 mol dye +31
A photosensitive lithographic printing plate (2) was prepared by coating an image nucleus layer of 500 #/mole of silver halogenide.

The printing plate (2) is stored in a roll in the magazine (1) and is conveyed to the exposure section by a predetermined length. The light path section is la9 from the suction bonder (4) and the multi-hole imaging platen (3), perpendicularly, or slightly inclined in some cases (e.g. vertically).
' (approximately 20"!). The printing plate (2) is fed by a reversible roller (6).
This is done while adhering to the perforated belt (5) that moves on the platen (3). The conveyance of a photosensitive material using a perforated belt is, for example, disclosed in Japanese Patent Application Laid-open No. 56-7 (J542, No. 59-2).
No. 04032 is also disclosed.

The close-up camera used in the present invention is the above-mentioned Japanese Patent Laid-Open No. 59-2
Photosensitive lithographic printing plate (2) as described in U41J32
The trap may be configured to transport the material from the bottom to the top. In FIG. 1, a horizontal piece of rice (not shown) is provided below the lens (8). Exposure light from a not-shown light source (it is preferable to have a transmission light device in addition to a reflection light device) passes through a lens (8) and a reflection mirror (9).
The printing plate (2) is reversed horizontally (tp) and reaches the printing plate (2) set on the platen (3) and the perforated belt (5).

A color separation filter ff1 (not shown) is provided before (or after) the lens (8), and each color separation filter can be set in a rotary manner.

The printing plate (2), which has been completely exposed, is conveyed along the guide plate 02 to two pairs of conveyor rows (not shown) by the movement of the perforated belt (5), and is further transferred to a developing tank as necessary. Processor (P) equipped with neutralization tank, desensitization tank, etc.
The paper is then transported to the factory, where it is processed and the plate making process is completed.

Next, the present invention will be explained in detail. The printing version (2) above is
Cassette) (1) The printing plate is manually or automatically cut by a rotary blade cutter (not shown) installed near the outlet, transported to a predetermined length to the exposure section, and set at a predetermined position. be done. The printing plate (2) may be cut after the exposure is completed. The manuscript shelf was prepared with a mixture of continuous-tone multicolor photographs and letters. Red for heading text, green for heading B, text C for main text
was decided to be printed in black.

In any of the yellow plate, magenta plate, cyan plate, and black plate, when the first m light is a continuous tone multicolor photograph and the second light is a text, exposure is performed under the following conditions.

During the first exposure, it is necessary to mask the text original, and during the second exposure, it is necessary to mask the photograph and the unnecessary text original.

■ indicates with a contact screen, ■ indicates without a contact screen.

In addition to the main path light time (Et), the photographic original was given a flood exposure (f) according to a known method. All exposures were performed at m, f=16. The contact screens used were GCDN150J/inch, manufactured by Dainippon Screen Mfg. Co., Ltd., with different screen angles (cyan version: 15°, magente version: 45″, yellow version O″, surface version: 75°).

The contact screen is attached to the contact screen frame, and before transporting the printing plate (21) to the exposure section, the contact screen is separated and released at step 13, and placed on the contact screen rack (set to the force) in advance under light in a bright room. Then, after the printing plate (2) is set as described above, by pressing a button outside the machine, the contact screen rack (force is moved horizontally to bring it into close contact with the photosensitive surface of the printing plate (2), and the first As mentioned above, the contact screen was set in advance on the contact screen rack (the force was applied to the first
As shown in the figure, it is not only located directly in front of the printing plate (2), but also at a position outside the exposure area of the lower, upper, left, or right side of the printing plate (2), and the position shown in Figure 1. the printing plate (2) after moving to or directly from that position.
It is also possible to move toward and approach the object, and when they come into close contact, they can come into close contact by substantially horizontal movement.

The method of providing a contact screen (7) at 1C, which is outside of this exposure area, is to use a contact screen in 1A! After the light has been spun, and before performing the second exposure of the character image, leave the printing plate (2) suction set in the exposure area and place it on the contact screen rack (simply by returning the force to the original position). , the subsequent second exposure is possible under bright room light, but of course the contact screen may be devised so that it can be taken out of the machine under bright room light. Another method for applying the irradiation is to horizontally return the contact screen rack (7) to its original position as shown in Figure 1 after the first exposure of the continuous iAmi image is completed, and then the printing plate (2) is placed in a light-shielding state. (In this light-shielding state, it is natural that the contact screen rack (2) may be moved outside the exposure area as described above.) This light-shielding state must be able to be released when the light continues to be <M2s+. A preferred method is to, as shown in FIG. The processor of the Inyu J version (2) (
Guide to P)? ! The container 0υ, which is fixed to the UZ and fixed to a drive chain (not shown), is raised by operating a button outside the machine, and the printing plate 121r is pulled out and suctioned as if it were hooked. This is a method of adsorption.This method of using a light-shielding sheeter is similar to the method of moving the contact screen plate (7) to the outside of the exposure area, which is similar to the method of moving the contact screen plate (7) to the outside of the exposure area.
2) does not move when set under suction, making it suitable for multicolor direct plate making. Light-shielding sheet container (
111 is made of a spring, for example, so that the rotation of the roller always wraps around the light shielding sheet Q (1) on both ends of the roller, and when it descends, it can wrap around the light shielding sheet Q (1). The sheet tIl'm may be shielded from light by being lowered or moved, or may be manually moved from outside the machine. A pair of reversible rollers is provided as an inlet and an inlet of the printing plate (2), and a 1jth!
& After the attachment and detachment of the light and contact screen is completed, the printing plate (2) is housed in the dark box by moving the perforated belt (5) upward to make the printing plate (2) in a light-shielded state.
but not limited to.

In the camera shown in Fig. 1, if the printing plate (2) becomes poorly light-shielded, the exposure section and the contact screen rack (7) are designed so that they can be opened by a minute N at zero. Remove the contact screen frame from the contact screen rack (7) under bright room light, then return to the above-mentioned separated state, and then remove the light-shielding condition of the printing plate (2), that is, the continuous light sheet OI'' ft: After making him groan and return to the street, I will give him 2 happy lights.

As mentioned above, the first M light is a continuous tone multicolor photograph, and the second M light is a continuous tone multicolor photograph.
Although the case where the M light is a character has been described, the case where the order of the first exposure and the second exposure is reversed will be omitted because it can be understood from the above description.

In this manner, the exposure of the original was completed, and the resulting color plates were sent to the round processor (P) for plate-making processing.

The following treatment liquid was used.

[Transfer developer]

Water 700 Potassium hydroxide 202 Anhydrous sodium sulfite 5 (12-mercaptobenzoic acid 1.5v2-methylaminoethanol 152 Dilute to 14 with water.

[Jun Kowa]

Water 60〇-Citric acid 1 (1 Sodium citric powder 352 Colloidal silica (2
0%-WL) 5m ethylene glycol
5- Add water to bring the total volume to IIJ.

[Desensitizing liquid]

Water 6UOm
t Isopropyl alcohol 400-Ethylene glycol 502: 3-Mercapto-4-acetamido-5-〇-to-1 methyl-1,2,4-triazole 1t Each of these lithographic printing plates was injected with offset printing ink of the corresponding color. When I layered it using paulownia, I could not only write text but also
Polychromatic power 2 - Original yuzu is also a stamped material with good color reproducibility with a range of dot area from 5% to 95%, no background stains or capri, and high rope resistance of s, ooo sheets or more. In addition, the contact screen was not damaged even in a large number of cases.

Although the method of the present invention is particularly suitable for multicolor direct plate making, it will be appreciated that it can also be applied to photosensitive materials for preparing direct lithographic printing plates for monochrome printing.

(F) Effects of the Invention The method of the present invention is useful for continuous tone images, especially color photography and fine a! When an original containing a mixture of +i images can be photographed under bright room light using an easy-to-operate copying camera, and when applied to the multi-color (color direct plate making) method, it is possible to produce prints with no background stains and good color reproducibility. You can get a lot of illumination and you won't damage your expensive contact screens.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main parts of an example of a bright room type plate-making camera used to carry out the present invention. In the figure, 1... Magazine 2... Photosensitive planographic printing plate 3...
...Porous photographic filter/4 ...Suction pump 5 ...Porous belt 6.6''...Porous belt feed and return roller 7
......Contact screen rack 8...-
..... Lens 9 ..... Inversion Mi 2- IO ..... Light shielding sheet 11 ..... Light shielding sheet storage container 12 ...
. . . Guide P . . . Part of the processor is shown.

Claims (3)

[Claims] (1) A method in which an original containing a mixture of continuous-tone images and line images is image-exposed onto a photosensitive material by first exposure and second exposure through the lens of a bright-room type copying camera, and the method is approximately perpendicular. The photosensitive material is transported to and set in an exposure section provided with a suction mechanism, and when the first exposure is to capture a continuous tone image, (a) a contact screen is removed from the opposite side of the photosensitive material; (b-1) While holding the photosensitive material in that state, move the contact screen into the machine so that it is facing the photosensitive material and out of the exposure area. or (b-2) after moving the contact screen in the machine to face the photosensitive material, the photosensitive material is placed in a light-shielding state that can be released during the second exposure, and during the second exposure, The contact screen is not present in at least the exposure area, followed by (c) applying a second exposure of a line image; if the first exposure is a line image, then (a'
) Performing the first exposure, and then (b'-1) While holding the photosensitive material in that state, move the contact screen located outside the exposure area facing the photosensitive material to bring it into close contact with the photosensitive material. or (b'-2) bring the photosensitive material into a light-shielding state that can be released when the photosensitive material is brought into close contact with the contact screen, move the contact screen from the opposite side of the photosensitive material to come into close contact with the photosensitive material, and then (c ') A method of exposing a light-sensitive material, comprising: applying a second exposure of a continuous tone image. (2) The exposure method according to claim 1, wherein the photosensitive material is a photosensitive lithographic printing plate. (3) The exposure method according to claim 2, wherein the photosensitive lithographic printing plate is spectrally sensitized in a panchromatic manner.