JPS59176745A - Formation of halftone reproduced picture from original and photoscreen apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an integrated photoscreen for forming halftone reproductions from photographs, and a method of using a photo screen to produce such halftone reproductions suitable for offset printing. It is.

[Long Blue L1] Until now, there have been many difficulties when creating a printing plate from a photograph using a conventional electrostatic plate-making device.

This difficulty occurred primarily when reproducing colors or gradations of light and shade. In this regard, unless some kind of screening technique is used, the printing plate will not have a certain gradation of light or dark, but a continuous light or dark, light or light tones, and dark or dark tones. It will appear on top of.

One previously proposed solution to the problem of creating an intermediate version was to form a printable dot contact screen sold by Eastman Co. Tank Company under the trademark KODAK PMT. . In the case of this PMT (trademark) sugelene, even one halftone can be reproduced well depending on the capabilities of the printing press. In other words, the tonal range from light to dark in many original images is typically larger than the printing capacity of a printing press.

The KODAK(TM) system determines the printing press's ability to record or print light dots and dark dots, and then leaves the press to produce the halftones to be created by the imaging device. Determine the size of the dot you need ・2!
Good reproduction is achieved by the second method. Photographic plates used in electrostatic platemaking are manufactured by a number of companies, such as 3M Company, which manufactures the 21'l 1165 All Matting Exposure Plate Maker;
, A, B, D, ri Company is AB.

Maddux Graphics Products, Inc. manufactures the Dick 145 Photomat(TM) Blate Maker and the Eight B. Dick 155 Electrostatic Master Maker, Maddux Graphics Products Inc. Maddux VF
Manufactures the V 215 Varia-Pull Focus Veriris System.

For the KODAK (trademark) PIIIT system,
A number of steps are required to produce good quality photographic reproduction with an electrostatic imaging device. When loading a copy, first attach the KODAK Reflection Density Guide Q-16 to the copyboard.

A KODAK PMT negative paper sheet AD is then placed on the back of the imager and covered with a KODAK PMT gray contact screen. Next, this is exposed using only the No. 13 exposure device.

Thirdly, the image with this screen on is KODAK.
Transfer to KODAK PMT transfer paper in a special diffusion transfer processor containing a PMT activator.

Fourth, the resulting screen print is
The 6,000 steps in the KODAK Reflection Density Guide should burn out the first two steps in the KODAK Reflection Density Guide and expose just enough to photograph the door in the third step. It should be black.

In the fifth step, the screened print is mounted on a copyboard and exposed to a KODAK PMT paper plate material sheet at the same size using conventional exposure.

In a sixth step, the PMT negative is processed with a '0DAK PMT prepress in a diffusion transfer processor that includes a KODAK PMT activator.

After making preparations, the operator can then run the press sheet from this printing plate onto the stylus that will be used in the printing process.

Then, in an eighth step, the operator inspects this press sheet and picks out the smallest printable dot from any density step, picks the largest printable dot from any density step, and produces these dots. Record the concentration step.

Finally, compare the printed sheet and the original screen print to find the screen print stencil with the smallest printable dots appearing on the printed sheet. The dots that appeared at that step in the original screenprint should then become the operator's "object light" dots for all screenprints made using the PMT product.

Comparing the printed sheet with the original screenprint also reveals the step in the screenprinting in which large printable dots appeared in the printed sheet, and therefore the dots that appeared in the screenprint in this stamp. This results in a "1" dark area for all screen prints made using PMT products for that printing process.

As will be explained in more detail below, the integrated photoscreen of the present invention allows for the production of good quality halftone print reproductions on photolithography without the lengthy and cumbersome process of creating special PMT™ products. It provides a simple method for forming. A number of proposals have been made to improve the formation of halftone reproduction images, some of which involve the use of film masks, and various forms of film masks have been described, and some of them have been proposed to improve the formation of halftone reproduction images. An example of l! is given in the following US patent: I'm still here.

Ll Female Dwarf-1! L3 1L1” 3.152,528 Pendry 3.905
,822 Marks 3.192,510
-y-kus 3, Hl, 847 Bendley 4.003,649 Goren et al. 4.01
2.137 Goreng 4.027,962
Mayroos 47,080.055 force'-1) - 4,083, H2 Mayroos and others 4.090,78fi Bopu 4, +43,867 Lightscar - 4,227
, 795 Bob et al.-1 - and other patents, various techniques have been proposed to improve the creation of halftone reproduction images using electrophotographic or electrostatic processes.

Although uniform large area development has been a major problem with electrophotography, electrophotographic and electrostatic processes have produced excellent results for typed text and simple line drawings. . The idea of creating electrostatic offset plates has led to great advances in producing good quality printing of type and line drawings. Reproducing continuous-tone images or transparencies using electrophotographic or electrostatic processes is a method of reproducing continuous-tone images or transparencies, since these processes are very high-contrast processes. 1. Cannot be identified with certainty. Uniform images of large areas have been an important problem in electrophotography.

One solution to the problem of uniform large areas of electrophotographic receivers has been to employ development techniques other than open cascade development that alter the charge pattern present in large areas of adjacent charges in the receiver. . Many other techniques are well known. For example, magnetic brush,
These include powder cloud or liquid development systems1 or those using development electrodes, such as those described in Kantochik, U.S. Pat. No. 2,777,418, or Kutek et al., U.S. Pat. I'll be there in the morning.

Other techniques use mechanical, optical or electronic techniques to destroy adjacent charges on the photoreceiver.

For example, Carlson, U.S. Pat. No. 2,599,542, describes the use of electrophotographic engraving with similar notching in one-full (lattice shapes), and Weibull, U.S. Pat. No. 3,248,218, describes selectively discharging an electrostatographic plate to form a pattern that disrupts uniform areas.

Optical techniques to improve uniform field development have been used to discharge uniform fields using screened light sources. The screen may be or take the form of a linear or comb-like screen, or a grid or dot pattern. The electrostatic plate is selectively discharged in areas where light is transmitted through the screen but whose charge remains blocked by opaque areas of the screen. An example of an optical technique for improving the development of such regions is U.S. Pat.
No. 598.732, No. 3,121,010.

No. 3,212,888, No. 3,335,003,
and No. 3,535,031b%.

These previously proposed techniques relate in fact to electrophotographic reproduction devices, but in particular do not concern techniques for producing halftone reproductions of continuous tone originals by screen technology.

Prenday's U.S. Patent No. 3,152,528
Shadow casing members are described that consist of an array of opaque line or opaque dot elements that break up the light into a pattern of midtones. The resulting electrostatic image, when exposed to light, resolves into a halftone pattern, which creates an electrostatic field on the photoconductive surface and develops a uniform large area of uniform halftones. As a result, continuous gradations are generated.

This patent thus teaches the use of a screen consisting of a mating opaque area and a transparent area interposed between the original document to be reproduced and the lens system of an electronic photocopying device. There is. What is this technology? 1! The uniform area of the electrophotographic process has been improved in making IF-indeterminate copies of continuous tone originals.

Another solution has been to use a composite original screen such as that described and described in Marks US Pat. No. 3,905,822 and No. 3,912.510. More specifically, this Marks patent 1"
In the copy formed using the 5 true process - C1
It shows the use of a composite screen that expands the range of input densities transferred or reflected from a document with variations in output density.

The purpose of Marks' technology in , - is to extend the scope of electrophotographic processes by the use of synthetic original screens, which consist of a bright transparent substrate material with a uniform surface on at least one side of it. The screen has a plurality of substantially opaque dots of high density and is in close proximity to, preferably in contact with, the document surface to be copied between the V-lens system of the electrophotographic reproduction system and the document surface. configured to be placed. The dots in this screen consist of a plurality of substantially light-absorbing dots and a plurality of substantially light-reflecting dots.

The frequency and arrangement of these dots are such that the light reflected from the screen is modulated by the lens according to the modulation transfer function of the lens system used in the electrophotographic reproduction machine.

This half-tone screen therefore consists of a plurality of mixed opaque dots of uniform density, half of which have substantially equal light absorption dots, and half of which have substantially equal light reflection dots. Met. A dot that substantially absorbs light, called a black dot, absorbs at least 80 degrees of that light.
The concentration should be such that it absorbs z. In addition, a light reflecting dot called a white dot reflects at least 80x of the light.
should be reflected, with optimal effectiveness as both values approach 10 oz.

However, it is this lens system that modulates the light transmitted or reflected from the original document according to the modulation transfer function (MTF) of the particular tons system used in the electrostatographic reproduction machine. For a given lens system MTF, if the dot pattern is photographed IF accurately by a suitable focusing lens, the wave number of the dot pattern is too low. in this case,
The virtual image of the dot pattern is a rectangular wave, which according to conventional Fourier analysis consists of a sine wave at the fundamental dot pattern frequency and many higher harmonics.

Lens systems used in conventional electrophotographic equipment exhibit relatively large MTFs compared to current high quality lens systems used in electrostatic offset plate making equipment. As a result, the screen described in the Marks patent does not provide desirable results when performing halftone reproduction in printing plates of continuous tone originals using electrostatic offset platemaking equipment. In this regard, the composite screen merely exhibits a substantially uniform dot size that does not vary in size due to the effects of image transmission or reflectance through the composite screen.

In contrast, the integrated photoscreen of the present invention uses varying density vignetting dots and light modulating white dots to vary the amount of light reflected or transmitted. The vignetting dots vary in density from the brightest at the periphery of the dot to the darkest center at the center of the dot, and the white dots are actually modulated from the continuous tone surface of the 1-1 original through the transparent substrate. Ru. The integrated photoscreen of the present invention modulates reflected or transmitted light by changing the continuous-tone density of the original, i.e., narrows the continuous-tone density range of the original to be suitable for offset printing processes, and is suitable for electrostatic printing processes. Forms a halftone reproduced image used for plate making.

None of the prior art patents mentioned above disclose a film mask that: That is, this film mask narrows the continuous tone density range of the original document and includes a variable density light modulating pinending light I grade mixed with an array of light modulating oriented dots on a transparent film material NEGL I grade. It has an arrangement of points.

Turner et al. U.S. Patent No. 3. Hl, No. 847 describes an electrophotographic printing device that combines arcuate photoconductive members. When the arcuate screen member is mounted on the printing device and brought into close proximity to the photoconductive member, a halftone image of the document is formed.

The screen member itself has a plurality of lines or dots printed on it through a transparent sheet.

US Pat. No. 4,003,849 to Goren et al. describes a phase screen having a substrate made of a non-absorbing transparent material such as Karas or Plastiac. A plurality of rectangularly cut rulings or grooves of predetermined screen frequencies extend linearly across the substrate. This phase screen is placed in the plane 42 and arranged so that the rulings are parallel to the direction of rotation of the drum l and perpendicular to its axis.

Goren et al. U.S. Patent No. 4. ot2. No. 37 describes a continuously rotating screen member having a rectangular array of dots on its second side. Monochromatic light image, i.e. red,
Blue and green light passes through the screen member and is incident on the charged photoconductive member. The photoconductive member discharges its charge to form a monochromatic electrostatic latent image.

Mayroos U.S. Patent No. 3,027,9 [12]
An electrostatic printing device is described having a dot screen and a transparent platen with an opaque sheet interposed therebetween. A color-filtered light image of the transparency is formed on the platen, which causes the tont screen to modulate the image of the color transparency to form a halftone image, which is combined with the image of the composition frame. to form a combined image. In this way, a combined image is formed on the transparent platen, and by driving the scanning system it forms a smooth halftone image, and only then a combined smooth light image that passes through the dot screen and composite frame. can do.

U.S. Pat. No. 4,080,055 to Gurley describes a screen member having a transparent disk having a plurality of dots arranged thereon. The screen is placed at discrete predetermined angles through which a series of color filtered light images are passed.

One of the predetermined angles for the filtered light image
2).

U.S. Patent No. A, O3E: E32 to Mayroos et al.
A halftone screen is described that includes a bright transparent substrate having a plurality of spaced apart opaque areas. These opaque regions are arranged in at least a high frequency repeating pattern and a low frequency repeating pattern. This screen can be used to modulate the light image of a color transparency that is reproduced on an electrophotographic printing device.

U.S. Pat. No. 4,090,788 to Bob describes a screen member that includes a transparent sheet having a plurality of hard dots. Multiple sets of dots are arranged on a transparent sheet, each set functioning as an optical filter capable of passing light rays having discrete spatial bandwidths. Each set of light filter regions is substantially complementary in color to the filtered light image and then rotated by a predetermined angle relative to an adjacent set of light filter regions.

Leitzka, US Pat. No. 4,143,967, describes a dark screen having small apertures arranged at an angle to the screen member. The screen has two perforations that indicate the axis of the screen and are used to align the screen with the film located below the midtones. This patent thus describes a method of forming a latent image photograph by using photographic reproductions in the form of negatives and positives and photographing the negatives and positives in sequential alignment through this dark screen. .

U.S. Pat. No. 4,227,79θ to Bob et al. describes an optical system for exposing a movable photosensitive member to a light image of a document, which includes a light source illuminating a screen having at least two adjacent rows of opaque dots. It has the following. This screen has an opaque frame with slits, T9
17) arranged in successive rows. In this way, finely separated charge patterns are recorded on the photosensitive member.

+ti7 None of the prior art patents mentioned above describe a film mask that: In other words, this film mask fills in the continuous gradation density range of the original (photo),
As will be explained in more detail in the following description, a variable density light modulating hinning light grade dot mixed with a light modulating internal dot array is added to a sheet of transparent film material as provided by the integrated photoscreen of the present invention. It has an array of

According to the present invention, a method for forming a halftone reproduction image from a photograph is provided by the following steps. That is, a photograph is placed at the photographing position of the reproduction device, a transparent photo screen is inserted between the photograph and the reproduction means of the reproduction device, and this photo screen has Uf mixed with a white dot array for light modulation.
Consists of a sheet of transparent substrate material having an array of vignetting light grades for variable degree light modulation, where the vignetting dots vary in concentration from the brightest concentration region at the outer periphery of the dot to the darkest core concentration at the center of the dot. However, these gray vignetting dots for light modulation and white dots for light modulation have the function of modulating the light passing through the transparent substrate in the continuous tone of the original, and operate the reproduction device to reproduce the halftone reproduction image of the photograph. It forms the

Further, according to the present invention, there is provided a photo screen that creates a halftone reproduction image from a photograph in the next step. That is, a photograph is placed at the photographing position of the reproduction device, the photo screen is inserted between the photograph and the reproduction means of the reproduction device, and the reproduction device is operated to form a half-tone reproduction image. This photoscreen consists of a sheet of transparent substrate material having a variable density light modulating vignetting light grade dot mixed with an array of light modulating white dots, the density of the vignetting dots varying from the brightest area at the outer periphery of the dot. It varies up to the darkest core concentration at the center of the dot. This integrated photoscreen modulates the reflected or transmitted light by changing the continuous-tone density of the original, that is, it narrows the continuous-tone density range of the original, making it suitable for one-culm offset printing and used in electrostatic platemaking. A halftone reproduced image is formed.

χ''1 Sail Lb SakautaIf we refer to the drawing in more detail, Figure 11 shows
An i'tt prepress photographing apparatus is shown, which is generally designated by the reference numeral 10. This device 10 includes A and B.

The Dick 145 Photomant Blate Maker may be of the type sold by the Defuku Company under the trade name AB, Dick 155 Electrostatink Master Maker A, B.

Such an electrostatic plate making photographing apparatus 10 includes a cabinet 1-12 having a table 14, and an image placement area 16 is located in the cabinet 1-12.

From the rear side of gear hinge 12 to 1-force, fly 1, part 18
The lens mounting overhead structure 20 extends in a direction 611 from the frame portion 18. Lamps 22 and 24 are supported from the open structure 20, which is [
: "It is positioned so as to illuminate the image mounting surface 16 of the first surface 14.

A photo 30 is placed in contact with the image placement surface 1B,
According to the present invention, an electrostatic integrated photoscreen 32 formed in accordance with the present invention is shown in photo 30 at 1, and an enlarged perspective view of photo 30 is shown in FIG. The screen 32 is shown in Figure 1 as an enlarged oblique view. Photoscreen 32 is made of a transparent film material such as acerate or mylar. In one preferred embodiment, the photoscreen 32 is made of 0.102 to 0.178 millimeters ('O, Q 04 to 0.007 inches) of transparent Mylarphy 1'/Z.
Consists of.

, , 4; According to 5 for optical use, the photo screen 32 includes an array of otting light grades for light modulation;
A third light gray vignetting dot and a footrest or an interposed array of uniform white dots for light modulation are placed 41 therebelow. The vignette is designated as a whole by the reference numeral 34 in FIG.
As shown in FIGS. 9 to 11 for the dot 72, the brightest area 76 (FIGS. 9 to 11) on the circumference of the dot 77 is the center of the dot 34.
The density varies up to the darkest core region 36.

Referring now to FIG. 3, there is shown a reproduction of a corner 38 of the first left portion of a photograph 30 showing a corner of a building.

FIG. 4 is a reproduction of a reproduced image of the corner 38 shown in FIG. 3 using the prepress photographing apparatus 10 without using a photo screen or mask on the photograph 30. The contrast is very high, with almost no midtones, printing as dark areas or black and bright areas as white. Figure 5 shows
When creating the reproduced image 50, the photo screen 32 of the present invention is superimposed on 1- of the photograph 30, and a copy of the reproduced image 50 of the corner 38 of the photograph 30 shown in FIG. be. Here, the dark areas are brighter, the bright areas are darker, and the areas in between are more accurately shown.

FIG. 6 is an enlarged view of the corner of photoscreen 60, which has variable density light gray pinending dots 62 for light modulation, these dots being photographically formed on photoscreen 60 at an angle of 45''. has been done.

In this regard, it can be seen that the hinged 7+-62 appears as a line making an angle of approximately 45'' with the horizontal.

According to the present invention, the arrangement of the light modulating white dots overlaps the vignetting pattern). Such a dot arrangement is shown in FIG. Here, a photoscreen 7 having an array of photographically formed pinenting dots 72 across the photoscreen 70 at an angle of about 456 is shown.
0 is shown. Therefore, a plurality of light modulating directions 1 and doors 4 are stacked on top of the photo screen 70, and the screen 70 is printed with lines at an angle of about 45 degrees.Photo screen 1.1-770 In this embodiment, white dots 74 are arranged side by side with pinene/diagonal dots 72;
As shown in FIG. They are lined up 11-2.

The pinenting dots 72 are formed on the photo screen 70 using so-called Levy glass green having 60 to 160 lines per inch, and have a dot density of 60 to 160 lines per inch. Pinenting dots can be formed.

As shown in FIG. 9, a light modulation white door 4 is placed on a photo screen 701- outside the light gray vignetting dot 72. The arrangement of the white dots 74 is performed by transferring the ink fill 1 to the transparent substrate through a printing process. 40 to 16 per inch
The same Levy crow screen with 0 tree lines and 1 is used for printing this printing white dot.

9 and 10, the filter bottom surface 75 of the photo screen 70 is shown in a greatly enlarged manner. This is a light gray pinenting dot of varying density.7 This is shown as a small black dot for simplicity.

As you will see, the outer periphery 78 of each hinged tip 72 is a very light gray color, and the dots 72 gradually darken inwardly toward the center 77 of the tip.
The center is the darkest gray part of Tonto.

The structure described above is also shown in the enlarged cross-sectional view of FIG. Here, the transparent film substrate 78 is 0.102 to 0.178 mm (0.004 to 0.00 mm).
The white dot 4 is printed on the top surface 79 of the photo screen 70, and the center 74a of the dot 7 is the thickest part of the dot 4, and the periphery 74b is thinner than this, and the white dot 4 is printed on the top surface 79 of the photo screen 70. is tilted towards. This is due to the molecular attraction of the material, and such a thin periphery 74b modulates the light passing through the photoscreen. As shown, the white dots 74 are located in one bright area 7 of the bottom surface 75 between the pinenting dots 72.
It is printed on the surface 79 above 5a.

+s: The best results will be obtained if the mr 7 5 is directed toward the photograph and the top surface 79 is directed toward the no.j of the photoreceptor. There, as the light passes through the photo screen 79 and onto the continuous tone document or photograph, the light is reflected from the surface of the document through the screen. This reflected light is sequentially modulated by the light modulating function of the photo screen, narrowing the density range of the original, and being transmitted to the light receiving device by the photo screen depending on the transfer pitch or dot size. The pattern is imaged.

The preferred dot density for vignetting dots 72 and white dots 4 is approximately 85 dots per inch.

The optical density of the pinending dots 72 and the white dots 74 relative to the photoscreen 70 ranges from 5% to 4%.
It may be up to 0χ. This means: That is, the size of the dot is 5z to 40x of the entire space of the photo screen. Oz means no dots, ie a bright transparent photoscreen 70, and 100% density means the photoscreen 70 is completely covered with dots.

A desirable vignetting dot size is in the range of 25 to 30%. This also means the following: That is, each vignetting dot occupies 25 to 30% of the total space available on photo screen 70. The preferred white dot size is 25x of the total photoscreen space, and the preferred pinenting dot size is 25% of the total photoscreen space.

As shown in FIG. 7, the preferred dot line angle is 45°, but other possible striation angles are +05°. Such dot line angles are shown in FIG.

In the same figure, one corner of the photo screen 8o is “I”.
It is shown by the line of pinning dots 82 at 105°, and the line of white dots 84 is adjacent to the line of vignetting dots 82, which also has a degree of sterilization of +05°. One pinnenting dot 82 is indicated by reference numeral 86, and one M-contacting white dot 84 is indicated by reference numeral 8.

Figures 7 and 8 show dot line angles of 45° and 1
056 is shown, but it should be understood that the vignetting dots 72 or 82 may be oriented in any line from o'' to 18o.
or 84 may have any chisel angle from oo to 18o0.

In another embodiment (not shown), the hinting dots are formed at 45 degrees and the white dots are formed at 45 degrees.
105". Therefore, the white dots have a different degree or orientation than the vignetting dots, so that some white dots are partially vignetting dots. − is printed.

In addition to having different fimbriality orientations, rung 1,
or vignetting2. White dots may be printed in a predetermined relationship with the vignetting dots in a predetermined relationship with the vignetting dot array. In this case, as shown in Fig. 7, the white door 4 is completely closed.

They are arranged in alignment with the door 2 and distributed therebetween. On the other hand, each white dot 84 shown in FIG. 8 is located at the upper left of the pinenting dot 82. Again, as mentioned above, these white dots may have different degrees of fungi,
The array may be superimposed on the pinenting dot array.

We conducted an experiment using an electrostatic plate-making photographic device, and detected a light gray area between uniformly bright areas and uniformly dark areas.

A reproduced image of very good quality with halftones that reproduces the turf gray area well was obtained. An array of different fimbacterial degrees,
and black vignate, tington!・Confirm all the arrangement of various white uniform dot arrays.
Although this may not be the case, good intermediate color reproduction was obtained in the experiments. Therefore, any photoscreen with vignetting donts and white dots according to the invention will significantly improve halftone reproduction.

FIG. 12 shows a graph 88 of document density versus output density when plate-making printing is performed without using a photo screen. As you will see, the bright area (density 0.
50 or less) are printed brightly, and dark areas (density 0.80 or less) are printed brightly.
)- is printed dark, in this case density=logical 1/R. However, R is reflectance or transmittance.

Figure i13 is a graph 80 showing document density versus output print density for printing plates formed using the uninvented photoscreen 70 or 80. Graph 90 shows that the various tones of the original are printed very well using photoscreens 70 or 80, and this is clearly demonstrated by the gradually increasing midtones between densities 0.10 and 0.65.
j is shown. From densities 0.65 and 1.20, the slope increases sharply or still gives the gradation of halftone reproduction. Therefore, from the concentration 1.20 to 2.10, this increase becomes gradual again.

FIG. 13 also shows a graph 9 showing the percentage of dot printing printed on paper using the halftone printing plate formed using the photo screen of the present invention versus the original density number.
2 is shown.

The spatially improved reproduction effect shown in FIG. 13 is obtained by using the integrated photoscreen 70 or 80 of the present invention. This kind of screen 1st screen 7
0 or 80 is constructed of a bright transparent substrate material, at least one side of which has a plurality of light modulating beams and glide grades of varying densities; The concentration changes from the periphery to the center). The photo screen 70 or BO is also formed with a plurality of light modulating white dots mainly on one side, which are essentially doors that modulate reflected or transmitted light. both doors) represent a reduction in the continuous tone density range of the original. The density range of the photo screen in combination with the 1m degree range of the original is then reflected by the light transmitted through the excellent lens system and projected onto the surface of the electrostatic off-cent plate-making and photographing device A, element f. Indicates the ideal range for modulation. The projected light is converted into a modulated light pattern C by the integration effect of the continuous tone of the original, the vignetting light grade lens for variable density light modulation, and the white dot photo screen. Let it discharge.

The pattern resulting from this discharge represents a negative image of the document, which is actually referred to herein as a halftone reproduction image. It can be seen that this halftone consists of a plurality of dots, and the size changes from the smallest dot, 7 dots, to the larger dots that overlap adjacent dots. By this effect, a continuous tone optical effect can be obtained by changing the size of the dot according to the discharge charge.

Therefore, the half-tone negative latent image on the photosensitive layer 1- is developed by bringing it into contact with a finely dispersed electrostatic adsorption material such as a synthetic resin colored powder or liquid called toner. The discharged areas of the image do not attract toner powder or liquid. It is the opposite or undischarged area that receives the toner or liquid and becomes the positive image. The toner is held to the photosensitive layer by the electrostatic field in the areas of the positive image. The toner is retained in response to the electric field, so the greatest amount of material will land where the electric field is strongest. The least charged areas have little or no material deposited. There, a negative latent image is formed on the light receiving device, which is opposite to the previously formed halftone negative latent image.

It is this relationship between the halftone negative latent image and the toner image that produces the halftone positive image from which offset printing plates can be formed.

In an electrostatic plate making system, a boss image is formed by applying i-ner to the support surface of a printing plate and properly fixing it thereon. This fixing may be accomplished by heat or air, which dissolves the toner and causes it to adhere to the support material on which it was supported. In this way, the continuous tone halftone positive image of the original is formed. So this continuous tone of the manuscript goes from a very small black dot to a very large black dot.
These are halftone dots that vary in size up to a black dot.

Minute changes in the density of the original are transmitted as minute changes in size in electrostatic offset printing plate making.

Therefore, it is possible to convey information accurately indicating the density gradient of the original and print a halftone reproduction image from an electrostatic offset printing plate formed with an integrated photo screen without using a halftone screened original. This process is what makes it possible.

This photo screen is not only often used to form printing plates from photographs in electrostatic plate making equipment, but also
It can also be used in other electrostatic devices, such as copying machines, for example.

As will be apparent from the following description, the photoscreen of the present invention has distinct advantages over the more complex prior art techniques from which halftone printing plates and reproductions are produced by electrostatic platemaking and photographing equipment.

The photo I/screen of the present invention can also be used with office copying machines and offset cameras to produce halftone positive or negative films, or halftone photographs made therefrom.

It will also be apparent that various modifications may be made to the photoscreen of the present invention without departing from the teachings of the present invention. Accordingly, the scope of the invention is limited only as necessary by the claims.

To summarize the invention, a photo screen 32, 70 or 8o that creates a halftone reproduction image 50 from a photograph 3o is used in the following process. That is, the photo 3o is played back by the playback device 1.
The device is placed at the shooting position 16 of 0, and the photo 3o and the playback device 10 are
When the reproducing apparatus 1o is operated with a screen 32, 70 or 80 interposed between the first stage of reproduction and the first stage of reproduction, a halftone reproduced image 50 is formed. Photo screen 7° or 80
has a sheet 78 of transparent material on its bottom surface 75.
Light gray pinen original Ingdot 7 for variable degree light modulation
An array of 2 or 82 light modulating dots (74) preferably printed on the -H of the -face 78 thereof is provided.
't or mixed with 84 arrays

[Brief explanation of drawings]

Fig. 1 is a perspective view of an electrostatic plate making photographing device, and Fig. 2 shows a photo screen formed according to the present invention on which the photo screen formed according to the present invention can be easily placed at 1- of the photograph in the photographing device shown in Fig. 1. Figure 33 is a plan view showing one corner of the image as seen in a photograph, and Figure 4 is a perspective view of the photograph placed in the photographing position. FIG. 3 is a plan view showing a reproduced image at the corner of the image; FIG. 5 is a plan view showing the corner of the image formed using the photo screen of the present invention; FIG. An enlarged view showing one corner of a screen or mask with vignetting dots at -1, 45°, with vignetting dots at 456, An enlarged view showing one corner of a screen or mask with an array of white dots intermixed with, i.e. arranged between, pinenting dots at an angle of about 45°, FIG. FIG. 9 is a plan view showing one corner of a photoscreen formed with an array of white dots located between, i.e. intermixed with, an array of pinenting dots with a sterility of about 105'; FIG. FIG. 10 is an enlarged view of a photoscreen according to the invention showing light gray pinending dots for variable density light modulation and small black dots for light modulation; FIG. 10 is an enlarged view of the photoscreen shown in FIG. The enlarged view, FIG. 11, shows the photoscreen according to the invention along the line +1. of FIG. 1O. Enlarged sectional view taken along -11, ppJ
Fig. 12 is a graph showing the color density of an original or photograph versus output print density when the photo screen of the present invention is not used, and Fig. 13 is a graph showing the color density versus output print density of an original or photo using the photo screen of the present invention. and is a graph showing dot m degrees versus percentage of printed dots. 2: Sign of P part 1 103. Electrostatic plate making photographing device 161. Image input surface 30...Photo 32.70. , Photoscreen 34.82. , pinenting dot? 4,84.
, white dot 75 , , F side 783. Bright part 77, Don't center 78
,,,Transparent film substrate 79...Top patent applicant Edmund Varnish Zincification Rinto Katori Roshio "Sweaty, -"Shinino Josaki (no change in content) rtc, e FIG,
7 Procedural Amendment Il/1 February 10, 1959 Kazuo Wakasugi, Commissioner of the Patent Office 1, ,! l (Indication of the matter 1982 Patent Application No. 002776 2, Name of the invention Method for forming a halftone reproduction image from a manuscript and photo screen device 3, Relationship with the case of the person making the amendment Patent filing order address Illinois 60016, United States of America death
Plains, East Birding 148 Name: Nationality: United States of America 4. Agent address: 1-13-4 Toranomon, Minato-ku, Tokyo 105 5. Subject of Supplementary IE (1) Drawings (2) Power of attorney and translation (3) No changes to the application form). April 5, 1984: Submit a revision 11: morning letter stating the number of the United States patent publication. 7. List of attached documents (1) 1.2 drawings
1 letter, 1 report, tF#I's "Name of the invention J" is different from the "Name of the invention" stated in the power of attorney, but the contents are the same.

Claims (1)

[Claims] 1. A method for forming a halftone reproduced image from an original such as a photograph, which includes the steps of placing the original at the photographing position of a reproduction device, and connecting the original to reproduction means of the reproduction device. interposing a transparent photo screen therebetween, the photo screen including a sheet of transparent substrate material, the sheet of substrate material having a variable density light modulating light gray mixed with an inner dot array for light modulating.・Has a vignetting dont arrangement,
The binenting dots 71 vary in density from the lightest density area to the darkest core density at the center of the dot, and the method further includes operating the playback device so that the photo screen continuously hydrates the document. 1. A method of forming a halftone reproduction image from an original document, the method comprising the step of: forming a halftone reproduction image of the original document in a manner that reduces the degree range of the original document. 2. The method according to claim 1, characterized in that the photo screen is placed on top of the document. 3. In the method described in claim 1, 1■■
The recording and reproducing device is an electrostatic plate making device. )
Way I no. 4. The device according to claim 1, wherein the reproduction device is a copying device. 5. In the method according to claim 1, the reproduction device is an offset photographing device, and the halftone reproduction image is used to form a halftone positive image or a halftone negative image in offset platemaking. A method characterized in that the film is a half-tone negative film. 6. The method according to claim 1, characterized in that the dot occupies 1z to 4 (H) of the photoscreen space. 7. The method according to claim 1, characterized in that
The vignetting method is characterized in that it occupies about 40% of the entire photo screen. 8. In the method according to claim 7. The hinting dots are 25 of the entire photo screen.
% to 30χ. 9. The method of claim 7, wherein the vignetting dots occupy 25% of the total photoscreen space.
A method characterized by occupying . 10. The method according to claim 1, wherein the white dots occupy 1% to 40% of the total photoscreen space.
A method characterized by occupying . 11. The method according to claim 1O, in which the white dot is located between 25x and 3x of the total photoscreen space.
A method characterized by occupying 0%. 12. A method according to claim 10, characterized in that the white dot occupies 25.chi. of dot position space per 1 line. 13. The method according to claim 1, wherein the screen is made of a film. 14. A method according to claim 13, characterized in that the quill 1 is made of mylar or acetate. 15. The method of claim 13, wherein the film is a 0.102 to 0.178 mm sigma film. 16. The method of claim 13, wherein said screen is formed using a glass screen having between 60 and 160 lines per inch in each case. +7. 17. The method of claim 16, wherein said glass screen has approximately 85 lines per inch. 18.4-'F-fraction The method of claim 16, wherein the vignetting dots are photographically formed on one side of the film using the glass screen, and the white dots are formed on one side of the film using the glass screen. A method characterized in that printing is performed on the other side of the film forming the film. 19. The method of claim 1, wherein the vignetting dont is formed with a line angle of 06 to 1806. 2. The method according to claim 1, wherein the white dots are formed at a linear angle of 0° to 180°. 2. The method according to claim 1, wherein the white dot and the vignetting dot each have an angle of about 45°.
, and the white dot is located between the vignetting dots. 2. In the method according to claim 1. the vignetting toat has a line angle of about 45″;
A method characterized in that the white dot has a line angle of about 105'. 23. A process of placing a photograph at the photographing position of a reproduction device, inserting a photo screen between the photograph and the reproduction means of the reproduction device, and operating the reproduction device to form halftones of the original. In a photoscreen apparatus for forming a halftone reproduction image from an original, such as a photograph, by a method, the photoscreen apparatus includes a sheet of transparent substrate material, the sheet of substrate material. A variable density light gray vignetting dot array for light modulation is mixed with a white dot array for light modulation, and the vignetting dots range from the brightest density area at the outer periphery of the dots to the darkest area at the center of the dots. A photo screen device that forms a halftone reproduced image from an original whose density changes up to the core density. 2. In the photo screen device according to claim 23, the dot occupies one of the entire photo screen space.
% to 40%. 2. The photo screen device according to claim 23, wherein the vignetting portion occupies 1 to 40% of the entire photo screen space. 2. The photo screen device according to claim 25, wherein the vignetting ton] occupies 25% to 30x of the total photo screen space. 2. The photo screen device according to claim 25, wherein the vignetting dots occupy about 25% of the total photo screen space. 2. The photo screen device according to claim 23, wherein the white dot occupies 1.chi. to 40% of the total photo screen space. 2. The photoscreen device according to claim 2θ, wherein the white dot occupies 25χ to 30% of the total photoscreen space. 30. The photo screen device according to claim 28, wherein the white dots occupy about 25% of the square dot position space per line. 31. The photo screen device according to claim 23, wherein the screen is made of a film. 32. The photoscreen device according to claim 31, wherein the film J1 is made of mylar or ahitate. 33. In the photo screen device according to claim 31, the film has a thickness of 0.102 to Q, +
FoI screen device characterized by being a 78 mm Mylar film. 34. The photo screen device according to claim 31, characterized in that the photo screen is formed using a lath screen having 60 to 180 lines per inch even at +tij screen deviation. screen device. 35. The photoscreen device of claim 34, wherein the force-grass screen has approximately 85 lines per inch. 3e, 4￥ In the photoscreen apparatus of claim 34, the vignetting dots 7) are photographically formed on one side of the film using the glass screen, and the white dots are formed on one side of the film using the glass screen. A photoscreen device, characterized in that it is printed on the other side of the film forming the photoscreen. 37. The photo screen device according to claim 23, wherein the vignetting dots are formed at a linear angle of 0° to 180°. 38. The photo screen device according to claim 23, wherein the white dot is formed at a linear angle of 0° to 180°. 38. The photo screen device according to claim 23, wherein the white dot and the vignetting dot are each formed at a linear angle of about 45°, and the white dot is located between the pinning dots. Features photo screen device. 40. The photo screen device according to claim 23, wherein the vignetting dots are arranged at an angle of about 45°.
, and the white dot has a line angle of about 105°.