DE1207798B - Process for the production of printing forms - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

G03f

German KL: STd-I

Number 1207 798

File number: W 26753IX a / 57 d

Filing date: November 20, 1959

Opening day: December 23, 1965

The invention relates to a method of manufacture flat or cylindrical printing forms using halftone negatives produced in the contact process were obtained from retouched halftone positives and then also using the contact method can be converted into grid positives.

It is known to produce a printing form from a transparent halftone image on an etching plate first a raster alone and then the transparent halftone image leaving the raster as it is to expose between the halftone image and the etching plate.

In contrast, the essence of the invention is that as a support of the photosensitive layer a lith film is used, against the layer side of which the carrier side of a negative film grid rests, whose bars are translucent and have a uniform density of about 0.20 Layer strips are formed, and a halftone positive is used as a halftone image whose Layer rests against the layer of the film grid, and from the grid negative produced in this way in on In a known manner, a grid positive is produced in the contact process.

The thickness of the transparent carrier layer of the film grid, which is advantageously about 0.1 mm in In the case of a 60 grid and about 0.25 mm in the case of a 30 grid, it is of particular importance because this determines the distance between the grid and the lith film. The individual opaque Points of the film grid, which advantageously have a uniform density value of about 4.00, are preferably formed by essentially square surfaces that are directly attached to connect the translucent surfaces.

The ratio of the total translucent area to the individual opaque points is determined by the number of grid lines per centimeter. For all grids with 30 to The strips forming the translucent surface have a width of 60 lines per centimeter about 0.05 mm, so that the width of the individual opaque square points is accordingly changes.

This ratio arises, for example, with a 40 grid with a width of the translucent Strips of about 0.05 mm and a corresponding width of the opaque Points of about 0.2 mm to 1: 4, while with a 60 grid with a width of the translucent Strips of about 0.05 mm gives a ratio of about 1: 2.5.

Process for the production of printing forms

Applicant:

Francis Ernest Wattier,

New York, N.Y. (V. St. A.)

Representative:

Dr.-Ing. E. Maier, patent attorney,

Stuttgart 1, Werastr. 24

Named as inventor:
Francis Ernest Wattier,
New York, NY (V. St. A.)

so The screen negative is produced according to the invention in the following way:

The contact film grid is made with the face of the clear base layer against the layer of a unexposed contrast line film (lith film) or such a film plate. On it will the contrast line film covered in this way is preferably exposed by means of a point light lamp in order to focus on it Way to form the webs on the grid negative and the individual ones on the etching plate or the etching cylinder Separate points or cells from one another. Then the retouched halftone positive flag brought with its layer side with the layer side of the contact film grid in contact, this its position in relation to the contrast line film does not change. This is then preferably by means of a point light lamp through the retouched halftone positive and the contact film grid a second Times exposed in order to obtain a halftone negative in this way.

The remaining process steps are the usual. The raster negative is made in the contact process a positive raster produced, which is exactly covering on the already printed on the pigment paper retouched halftone positive is printed.

The individual process steps are shown schematically in the drawings. It shows F i g. 1 is a plan view of the particular contact film grid;

FIG. 2 is a side view of the grid according to FIG. 1,

3 shows a side view of the contact film grid exposed onto a lith film;

509 759/331

Claims (1)

3 * 4 F i g. 4 shows a plan view of the screen negative strip W of the screen film S,. so about 0.05 mm. according to the exposed bar structure, the copied lattice bars are 21, the uncovered 5 shows a side view of the raster negative with cleared areas designated by 23, the contact film grid and placed on this in the same mutual position of the grid and retouched halftone positive for carrying out the 5 'of the once exposed film becomes a retouched one Next step, the exposure '"of the halftone positive with the layer side PE on the Raster ^negative; . \ ... layer side SE of the raster film S is placed and the F i g. 6 a plan view of the raster negative after negative N exposed a second time, performed exposure, 'The -different degrees of density PE of the silver- F i g. 7 is a side view of a cutout in the grain of the emulsion layer of the halftone positive P. Contact with the raster negative after the con are shown schematically in a section in FIG. tact film grid and the halftone positive is removed. These differences in density PE determine the were, and light intensity falling on the negative and so that 8 shows a plan view of a section of a ratio of the opaque surface 21 to that 15 translucent 23 of the raster negative produced according to the method according to the invention. These Raster negatives. Areas correspond in their size and shape The particular one shown in FIGS. 1 and 2 corresponds to the tonal values of the retouched halftone positive.
Contact film grid 5 was produced on a photographic The translucent surfaces 23 later result in paths in the contact process by means of a glass, the cells in the etched printing form or the etching engraving grid and consists of a through-plate. In Fig. 6 are the base layer 15 visible through the first exposure, on which the grid-shaped raster webs are marked with 21 and the hatched dated 17 caused by the arrangement of a number of opaque qua- the second exposure, with intersecting, intersecting marked areas marked with 21 ^ 4,
translucent strips 19 are applied. In order to separate out parts or places that should remain ineffective original glass engraving grid during printing, for example, opaque angles of 90 ° intersecting opaque to avoid a white background in a negative grid and lines formed between these lines , the retouched halftone become dramatic translucent surfaces. positive P and the contact film grid removed and on The width of the intersecting opaque point of a plate DP with opaque lines of the original glass engraving grid is 30 areas 41 and translucent areas 43, a 0.05 mm. The translucent intermediate surfaces of so-called cut-outs or a stencil, in which the number of lines of the grid correspond to the exact coverage with the grid negative layer against expansion. Layer placed on this and the raster negative To produce the contact film grid, it is exposed a third time (FIG. 7). Film exposed to a uniform exposure, so 35 With the screen produced according to the invention that a density of 0.20 is achieved. On these so negatively, the contours correspond to both the light- The pre-exposed film will be transparent to the original engraved glass, 23 as well as the opaque one raster exposed, so that for the opaque areas 21 exactly the tonal values of the retouched casual square individual fields produce a uniform halftone positive, as can be seen from FIG. 8. Dar- Density of 4.00 is obtained. 40 beyond are the contrasts between the A grid with only translucent surfaces between different light intensities areas in place of one with clear, clear and the light and dark areas sharp term area is used because it is limited. Production of a Screen Negative According to the Invention The remaining steps of the process should, too a grid with only translucent surfaces on 45 if they are conventional in themselves, in the back ground the slight scattering of light to a view of its special meaning in the collective-negative with much better highlight details than with the method according to the invention still leads a grid with transparent intermediate surfaces. be mentioned. The purpose and mode of operation of the grid result from the grid negative shown in FIG from the following description of the invention, a raster positive is produced on the printing plate. according to the procedure. represents that shows all the details of the halftone negative. First the screen negative is produced as follows: The opaque screen dot structure shows The screen film S with its underside SB has a uniform density and sharp outlines against the layer side NE of the unexposed. Film N placed (Fig. 3). The grid spacing SS between 55 patent claims:
see the layer SE and the layer NE is everywhere the same and is through the thickness of the transparent 1. Process for the production of a printing form Layer 15 of the contact grid S given. In the form of a transparent halftone image in which In order as shown in Fig. 3, the film N is first applied to a photosensitive layer Grid S exposed by means of a point light lamp L. 60 grid alone and then the transparent half This exposure is done for the purpose of leaving the grid in between on the tone image later raster negative to apply a web grating, the halftone image and the light-sensitive and the individual points or cells on the layer are exposed, thereby identifying etched printing form or plate to draw from each other that the light-sensitive separate. 65 borrowed layer a lith film is used, In this case, the exposure is only the carrier side of a layer against the layer side strongly chosen that the exposed lattice bars are applied to the negative film grid, the bars of which have the same width as the translucent through translucent, a uniform one Layer strips having a density value of about 0.20 can be formed, and as a halftone image a halftone positive is used, the layer of which lies against the layer of the screen grid, and from the screen negative produced in this way in a manner known per se in the contact process a grid positive is produced. 2. The method according to claim 1, characterized in that the thickness of the transparent Carrier layer of the film grid is about 0.1 to 0.25 mm. 3. The method according to claims 1 and 2, characterized in that the opaque, a uniform density value of about 4.00 having areas of the screen raster Are squares and the translucent strips running between the squares are one Have a width of about 0.05 mm. Considered publications:
German patent specification No. 45 654. For this purpose 2 sheets of drawings 509 759ß31 12.65 © Bundesdruckerei Berlin