JPS6150154A - Moire checking device for plate making - Google Patents

Abstract

PURPOSE:To simplify a checking work by projecting four kinds of moire checking patterns and a color original image to a screen to superpose one on the other optically and checking four kinds of moire simultaneously. CONSTITUTION:Four kinds of checking pattern corresponding to dot patterns for yellow, magenta, cyan, and black used at the plate making are recorded in colors different from one another on a moire simulator 10 while superposed on one another, and the moire simulator 10 is freely rotated. Images of the simulator 10 and a color original 1 are projected to a screen 5 by optical systems 12 and 3. Meanwhile, a half mirror 4 arranged in front of the screen 5 permits the light from the original 1 to transmit through but reflects the light from the simulator 10 and leads them to the screen and synthesizes two images on the screen 5. Consequently, four kinds of moire generated between four kinds of dot pattern and the original 1 are checked simultaneously.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention predicts the presence or absence of a moire phenomenon that occurs between a mesh pattern used in a shading process and a color document, and detects the occurrence of the moire phenomenon. The shaded area relates to a moiré inspection device for plate making for determining conditions.

[Prior art]

The technology of converting the shading of an original image into the size of the halftone dot area and reproducing it as a printed image is widely practiced in the fields of platemaking and printing as a camera method using a contact screen or halftone processing using a direct color scanner.

The contact screen has a regularly arranged pattern of shades, so if there is a part of the image of the original in which the shades of a are regularly arranged, such as a pattern on clothing, these will optically interfere with each other. , shading patterns that are not present in the original often occur.

This shading pattern is called moire stripes (hereinafter simply referred to as moire).
This results in a significant loss of image quality. Particularly in the case of color printing, overprinting is performed using four halftone plates for yellow ink, magenta ink, cyan ink, and black ink, which increases the chances of moire occurring. In addition, in the case of color printing, moiré occurs between each color plate, so the screen angle (the angle between the straight line extending in the direction in which the halftone dots are lined up and the perpendicular line that serves as the basis) is different for each color. A contact screen is placed.

Various combinations of screen angles are used in practice, but the contact screen angle used for plate-making cameras is 0 degrees for yellow plates.

The magenta version is often set at 15 degrees, the cyan version is set at 75 degrees, and the blank version is set at 45 degrees. Further, in a color scanner, for example, Magnascan 520 (manufactured by Crossfield), the yellow plate is 90 degrees, the magenta plate is 45 degrees, and the cyan plate is 75 degrees.

The black version is 15 degrees.

If moiré occurs in the halftone photograph, it is necessary to shift the arrangement angle of the contact screen or shift the arrangement angle of the color original, and then create the halftone photograph again. Therefore, to prevent moire,
Much time and material loss was involved. In particular, in color printing, if the placement angle of the contact screen is shifted, moiré may occur between the two different contact screens, and if the placement angle of the color document is shifted, other Since new moiré occurs between the color-corresponding contact screen and the color original, the moiré cannot be eliminated with a single correction, and multiple mesh separations are required, which is extremely troublesome. Ta.

In order to deal with this troublesome moiré problem, a moiré pre-search system has been proposed that can predict whether moiré will occur before creating a halftone photograph. This moiré pre-search gauge records the same moiré inspection patterns as the four types of mesh patterns output from a direct color scanner that electrically processes the shading. It consists of a sheet and a scale plate that rotatably holds the sheet and has an angle scale on its outer periphery. In some cases, a moire pre-search gauge is set on a projection device, a real image of a transparent color document is projected, and the image is optically superimposed on the moire pre-search gauge to determine whether moire occurs between each pattern. Predict what will happen. However, with this device, four types of moire inspection patterns are recorded separately in four rectangular areas, so it is difficult to check whether four types of moire occur at the same time. could not. Therefore, in order to check whether moire occurs on the entire surface of a transparent color original, it is necessary to move the transparent color original or the moire pre-search gauge and check whether moire occurs for each color plate and the screen angle at which it disappears. Therefore, a large amount of time is required for the inspection work. In addition, when separating four versions simultaneously with a direct color scanner, it is impossible to change the mounting angle for each color version, so we comprehensively evaluate the four types of moiré.
It is necessary to check the angle when mounting a color original where the effect is the least, but since the moiré pre-search gauge mentioned above is designed to check moiré for each color plate, it is possible to
There is a drawback in that it is extremely difficult to check the angle when mounting a common color original, which eliminates the influence of moiré.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a moire inspection device for plate making that can simultaneously inspect four types of cheek moire that occur between four types of mesh patterns used during plate making and a color original. It is something.

Another object of the present invention is to provide a moiré inspection device for plate making that can inspect a color document regardless of whether it is transmitted or reflected.

[Features of the invention]

In order to achieve the above object, the present invention provides a moire simulator in which four types of moire inspection patterns are recorded in different colors and overlapped, and a moire simulator that transmits light from either a color original or the moire simulator. , and a half mirror that reflects the light from the other side and combines it on the screen.

When inspecting moire that occurs in a plate-making camera, the moire inspection pattern includes a contact screen for black, a contact screen for magenta,
The same pattern as the cyan contact screen and yellow contact screen is used. Furthermore, when inspecting moire generated in a direct color scanner, the same mesh pattern as the electrically generated 4fffi type and parallel lines corresponding to scanning lines are recorded in a reflection type moire simulator.

[Summary of the invention]

FIG. 1 shows a case where moiré of a color reflective original is preliminarily inspected using a reflective moiré miniaturator. As the color reflective original 1, for example, there is a color printed photograph, etc., and it is placed on a stage (with the recorded image facing down).
(not shown). This color reflective layer f&1
is illuminated by a light source 2 placed diagonally in front of it. The light reflected by the color reflective original 1 passes through an optical system 3 with variable magnification and a half mirror 4, and reaches a screen 5.

This optical system 3 is movable along an optical axis 6, and thereby enlarges or reduces the image recorded on the color reflective original 1 to the same size as that at the time of plate making, or focuses it on the screen 5 as it is (same size). can be imaged. Note that as the optical system 3, a zoom lens or a variable focus lens is also used. be able to.

The image formed on the screen 5 is observed by the eyes 7 from behind. A reference line is recorded on this screen 5, and it is movable along the optical axis 8. Note that instead of the screen 5, either the color reflective original 1 or the reflective moiré simulator 10 may be moved along the optical axis.

The reflective moiré simulator 10 is opaque as a whole and is illuminated by a light source 1) placed diagonally in front of it. The light reflected by this reflective moiré simulator 10 passes through an optical system 12 with variable magnification and passes through the half mirror 4.
It is reflected and reaches the screen 5. This optical system 12 is movable along the optical axis 13, thereby making it possible to change the pitch of the screen lines. Therefore, if the optical system 12 is doubled, the number of screen lines will be 20.
Since 0 lines becomes 100 lines, it can be used as a substitute for this 100 lines.

In the reflective moire simulator 10, four types of moire inspection patterns having the same patterns as a cyan contact screen and a yellow contact screen are recorded on an opaque sheet in an overlapping state in each color. This reflective moiré simulator IO is rotatable within a plane perpendicular to the optical axis 13.

The reflective moire smitter 10 has two types of moire inspection patterns recorded on four transparent sheets and then polymerized on one sheet. It can be divided into four types of moiré inspection patterns recorded.

The former type of reflective moiré simulator uses a large-diameter opaque sheet and has the four transparent sheets fixed to a scale plate with an angular scale on its outer periphery; There is one that is fixed to an opaque sheet and then rotatably attached to a scale plate that is shaped like a disc or a stepped ring and has an angular scale on its outer periphery. The latter type of reflective moire simulator includes one in which four types of moire inspection patterns are recorded on one opaque sheet with an angle scale on the outer periphery, and one in which four types of moire inspection patterns are recorded on one opaque sheet. After recording, this is fixed or rotatably attached to a scale plate, or a transparent sheet with four types of moiré inspection patterns recorded is fixed to an opaque sheet, and then this is attached to a scale. There are those that are fixed to the board or rotatably attached.

FIG. 2 shows an example of a reflection type moiré simulator. This reflective moiré simulator 10 includes a yellow sheet 20. Magenta sheet 21, cyan sheet 22. It is composed of a black sheet 23 and a scale plate 24 with an angle scale. Each of the sheets 20 to 23 has a moiré inspection pattern recorded on a transparent film in a different color, preferably the same color as the color plate, for example yellow in the case of the yellow sheet 20, and having an appropriate light transmittance. An opaque scale plate 2 with an angle scale on the outer periphery.
It is attached to 4. Since it is desirable that the moiré inspection pattern be the same as the contact screen used for printing, a reflective moiré minimulator is selected and used in accordance with the contact screen actually used.

Generally, a contact screen has a pattern shape, 1
It is specified by the number of halftone dots per inch and the screen angle. The shapes of this pattern include cross lines, squares, chains, and dot ovals.

There are triangles, etc. The screen angle represents the angle between a straight line extending in the direction in which the halftone dots are lined up and a perpendicular line that serves as the base, and is determined by the specifications of the plate-making camera or scanner used.

When inspecting moire, first move the optical system 3 along the optical axis 6 and adjust the projection magnification of the color reflective original 1 to the same value as during platemaking. Adjust the projection magnification.

Thereafter, the reflective mower resistor 10 is rotated so that its angular scale "zero" matches the reference line recorded on the screen 5.

By the optical system 3, the image of the color reflective original 1 is transmitted through the half mirror 4 and formed on the screen 5. On the other hand,
The image of the reflective moiré simulator IO is reflected by the half mirror 4 and formed on the screen 5 by the optical system 12 . Therefore, the images of the color reflective original 1 and the reflective moiré simulator 10 are formed on the screen 5 in a superimposed manner.

If the image recorded on the color reflective original 1 includes a part where the density changes periodically, optical interference will occur between the image and the image of the moiré inspection pattern. If you look at it, you can see the same moiré that occurs during plate making.

In this reflective moire simulator 10, each moire inspection pattern is recorded in a color corresponding to the color plate, so by examining the color of moire, it can be determined with which contact screen moire will occur during plate making. Can be predicted. If this moire is occurring, the reflective moire simulator 10 is rotated in a plane perpendicular to the optical axis 13.

When the reflective moire mini-rake 10 is rotated, the moire inspection pattern recorded thereon is rotated. Then, find a place where the four types of moiré disappear or can be ignored, and check the rotation angle at that time with reference to the reference line of the screen 5.

If the moire does not disappear even after rotating the reflective moire simulator 10, set the reflective moire simulator 10 at an angle that will reduce the four types of moire the most, and in this state, illuminate the screen 5! l[I Shift little by little along 8. While shifting this focus, find a place where the moiré disappears or can be ignored, and then adjust the amount of focus shift at that time.

Depending on the angle obtained as described above, the inclination of the color reflective original 1 mounted on the original drum of a direct color scanner is changed.
When the solid angle is 15 degrees, the color original 1 is rotated 15 degrees from the normal position and set on the original drum. In addition, if the moire disappears by adjusting the focus, shift the focus of the reading head or exposure head by the amount of shift. If the moire only occurs on a color plate, change the focus from the moire color to which color plate. Since you can see if this occurs, all you have to do is shift the focus of that color plate.

In the case of a scanner that uses a plate-making camera and a contact screen, since the screen angle can be changed for each color plate, the occurrence of moire can also be eliminated by the following method, which is different from the method described above. That is, since it is possible to know in which color plate moire occurs from the color of moire, the rotation angle of the reflective moire simulator 10 at which moire disappears for each color plate is checked, and the angle with the moire inspection pattern is determined. In consideration of this, a screen angle is calculated, and the color reflective original 1 is rotated according to this screen angle to explode a halftone photograph. Furthermore, if the moire does not disappear, it is sufficient to perform a focus shift procedure 83 for each color plate and shift the focus for that color plate.

Furthermore, a combination of direct scanners that electrically process shading can also be processed based on the same principle.

Figure 3 shows the case of pre-inspecting moiré of color transmission accumulation using a transmission type moiré simulator.
The same members as in FIG. 1 are given the same reference numerals. The color transmissive original 30 is illuminated by a light source 31 placed behind it, and the transmissive moiré simulator 32 is illuminated from behind by a light source 33. The color transmission thickness f
As g30, for example, a color reversal film is used. The transmission type moire simulator 32 may be one in which four types of moire inspection patterns are recorded on four transparent sheets, or one in which four types of moire inspection patterns are recorded on one transparent sheet. These transparent sheets are fixedly or rotatably connected to a scale plate having an angle scale on its outer periphery.

〔Example〕

FIG. 4 shows an example of an apparatus implementing the present invention. The case 40 is partially partitioned by a partition wall 41, and transparent stages 42 and 43 are arranged below each chamber. The reflective moire simulator 10 or the transmission moire simulator 32 is inserted into the stage 42 through the opening 40a. The light source 33 is arranged below the stage 42, and a plurality of the lights i1'ill are arranged above the stage 42. Note that these light sources 1). Behind 33 is a mirror 44 as is well known.
are installed respectively.

The color reflective original 1 or the color transparent original 30 is inserted into the stage 43 through the opening 40b. The light source 31 is arranged below the stage 43, and a plurality of the light sources 2 are arranged above the stage 43.

The optical system 12 is arranged above the stage 42, and the optical system 3 is arranged above the stage 43. These optical systems 3.12 have bellows 45.4
6 are installed respectively. Optical axis 6 of the optical system 3
is bent horizontally at right angles by a mirror 48. The half mirror 4 is placed in front of the mirror 48, and allows the light from the mirror 48 to pass therethrough, while also reflecting the light that has passed through the optical system 12 toward the screen 5. A knob 49 is attached to the screen 5, and the knob 49 allows the screen 5 to be moved along the optical axis 8.

When using the color reflective original l and the reflective moiré simulator lO in combination, the light sources 2 and 1) are turned on. The light reflected by the color reflective original 1 passes through the optical system 3, is reflected at a right angle by the mirror 48, and then passes through the half mirror 4 and reaches the screen 5.The light reflected by the zero-reflection type moiré simulator 10 is The light passes through the system 12, is reflected laterally by the half mirror 4, and then reaches the screen 5. On this screen 5, the images of the color reflective original 1 and the reflective moire simulator 10 are projected in an overlapping state, so that the occurrence of moire can be checked in advance.

When using the color transparent original 30 and the transparent moiré simulator 32 in combination, the light sources 31 and 33 are turned on. Since the light transmitted through the color transparent original 30 and the transparent moire simulator 32 reaches the screen 5, the same moire as that generated during plate making can be observed in this case as well.

In addition, color reflective original 1 and transmission type moiré simulator 3
2, it is sufficient to turn on the light sources 2 and 33. Furthermore, when using the color transparent original 30 and the reflective moiré simulator 10, it is sufficient to turn on the light sources 31 and 1).

Therefore, color originals and moiré simulators are
Any can be used regardless of reflection.

FIG. 5 shows another embodiment of the reflection type moiré simulator. In the reflective moire simulator 50, four moire inspection patterns (not shown) are recorded overlappingly on a single opaque base 52 in the same color as the color plate. Further, the base 52 is formed with a finger hole 52a, a stepped portion 52b, and an index 52C. Scale plate 51
The flange 51a is provided with a flange 51a having an angle scale, and the flange 51a abuts against the stepped portion 52b of the base 52 to hold the base 52 so as to rotate without coming out.

〔Effect of the invention〕

The present invention having the above configuration uses a moire simulator in which four types of moire inspection patterns are recorded in different colors, and each of the four types of moire inspection patterns and an image of a color document are displayed on a screen using an optical system. At the same time, a half mirror was placed in front of this screen to optically superimpose the two images, making it possible to simultaneously inspect four types of moiré. Either the transmissive or reflective type can be used. Furthermore, since it is possible to know in which color plate moire occurs based on the color of the moire, it is possible to know the screen angle at which moire is minimized for each color plate. Therefore, unlike conventional devices, there is no need to move the moire simulator, which simplifies inspection work and allows the reflective moire simulator to be made more compact.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention when a reflective moire simulator and a color reflective original are used. FIG. 2 is an exploded perspective view showing an example of a reflective moiré simulator. FIG. 3 is a diagram illustrating the principle of the present invention when a transmission type moiré simulator and a color transmission original are used. FIG. 4 is a sectional view showing an embodiment of the present invention. FIG. 5 is an exploded perspective view showing another embodiment of the reflective moiré simulator. l...Color reflective original 4...Half mirror 5...Screen 10...Reflective moire simulator 30...Color transparent original 32...Transparent moiré simulator 42.43...Stage 48...Mirror 50... -Reflection type moiré simulator 51...Scale plate 52...Base.

Claims (5)

[Claims] (1) In a plate-making moire inspection device for pre-inspecting moire that occurs when making a halftone plate from a color original, the yellow mesh pattern, magenta mesh pattern, cyan mesh pattern, and black mesh pattern used during plate making are used. a rotatable moire simulator that records four types of moire inspection patterns corresponding to mesh patterns in different colors and overlapping each other; an optical system that projects images of the color original and the moire simulator onto a screen; a half mirror disposed in front of the screen, transmitting light from either the color original or the moiré simulator, reflecting light from the other and guiding it to the screen to synthesize the two images on the screen; A moiré inspection device for plate making, characterized by comprising: (2) The moire simulator includes four transparent sheets each recording four types of moire inspection patterns;
2. The moiré inspection device for plate making according to claim 1, further comprising an angle scale on the outer periphery, and a base formed by polymerizing the transparent sheet. (3) The moire simulator consists of a sheet on which four types of moire inspection patterns are recorded, and a scale plate having angle scales attached to the outer periphery and rotatably combined with the sheet. A moiré inspection device for plate making according to claim 1, characterized in that: (4) The moiré inspection device for plate making according to claim 1, wherein the screen is movable in the optical axis direction. (5) The moire inspection device for plate making according to claim 1, wherein the moire inspection pattern is recorded in the same color as the color of the plate.