SU1463125A3 - Method and apparatus for manufacturing screen printing plates - Google Patents

Abstract

A method for producing half-tone printing blocks having an optional screen angle and screen line spacing by line-wise scanning of an original and recording by means of a recording element displaced over a recording medium is described. The recording medium has co-ordinated with it an UV co-ordinate system directed in the line direction and and XY co-ordinate system turned through the screen angle, both co-ordinate systems being subdivided into areal elements from which the picture elements or half-tone dots to be produced are collated. Notwithstanding the screen angle beta , screen threshold values are associated with the areal elements of a limited scanning pattern range which corresponds to at least one mesh element of the screen which is to be recorded, as a function of their XY locus co-ordinates. During the recording operation, the UV locus co-ordinates of the areal elements momentarily traversed by the recording element are registered on the recording medium, are recalculated in the form of the corresponding XY locus co-ordinates of the limited screen scanning range under consideration of the screen angle, and the screen threshold values associated with the XY locus co-ordinates determined are "called up". A control signal which determines whether the areal element in question is or is not recorded on the recording medium as part of a screen element, is generated for the recording element by current comparison of the screen threshold values called up with the image signal obtained by scanning an original. <IMAGE>

Description

one

 The invention relates to the printing industry and can be used in the manufacture of screened plates.

The aim of the invention is to improve the quality of manufacturing rasterized printing forms by using arbitrary nodes and screen patterns.

FIG. 1 is a block diagram of an apparatus for manufacturing screened plates; in fig. 2 - part of the recording medium; in fig. 3 - diagram of the transforming cascade.

The device for carrying out the method comprises a carrier 1, a clip, a record carrier 2, a shaft 3 moved by an electric motor 4 (ippraying its rotation so far: 3ano on yig. 1

arrow 5). On the nosepiece I, a colored original 6 is drawn, which is deployed point by point and line by line using a greenhouse point of the light source. With an opaque original reflected, and with a transparent original, a missing module modulated by brightness and the image of the original 6 expands the contact (rm falls on the reading organ 7. The organ 7, by color separation using a color filter and an electron-optical conversion of the expanding light, produces three centners) Zetovsk; Sig, nal, which substitute the color fragments of the expanded raster points of the image. The device also has an electric motor of 8 g, a spindle 9 moving in the direction of the arrow 10, an accelerator 1, an; a; digital-to-digital converters 12 -. 14 divider cascade 15 frequencies, oscillator 16 clock pulses, color channels 17, color correction circuit 18, signal switch 19, recording org 20, electrode: ngatel 21, spindle 22. FIG. 1 shows the carrier 23, the recording beams 24 ,. recording lines 25, raster point 26, corresponding channels 27, non-inverted raster coordinate system, raster grid 29 and rotated raster coordinate system 30, as well as transform; cascade 3, divider cascade 32, information channel. 33, pulse sensor 34 that converts channel 35. The device includes setting units 36 for programs of the transforming cascade 31, ra-str generators 37-39, information channel: s 40 and 41, comparators 42-44, infrashcheny channels 45 and 46. Fig. 2 shows raster cell 47, sections 48 square, raster cell 49 any line urs raster soogvetgtvuyusch i1M element 50 records the video line 51, the scale indicia 52 cycles of the device.

FIG. 3 shows the registers 53 56 accumulation of information counters

57 and 58, multiplication schemes 59–62, adders 63 and 64, address registers 65 and 66, days 67–70 and p &amp; 71 71 results about

The registration block of reference luminance values includes hall 3,

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A device that implements a method for manufacturing rastrivated printing plates functions in the following manner.

The analog color signals from the reading unit 7 are connected via consecutively usi; 1 1 1 get to analog-to-digital converters (ADC) 2-4, in which they are converted into digital color signals with a recording density, for example 8 bits. At the same time, each time a sequence of razvarshshanil T sequence corresponds to one raster point of the image.

The sequence of the sweep cycle T is obtained by dividing the frequency in the separating cascade 15 from the sequence t, the act T, which is produced due to the rotational movement of the cylinders by the generator 16 clock pulses. The sequence of the clock cycle is transmitted to the ADC 12 - 4 via channels 1-7.

Digital color signals in digital format; 1–8 color corrections are converted to corrected signals to record color-separated negatives: Magenta, Cyan, and Yellow.

In the digital correction circuit 18, according to the requirements of the repriduction process, color separation and / or gradation correction is performed; / - pa.

The digital signals are sent to the signal switch 19, with which each time one of the digital signals is selected for rasterizing this recording of the necessary color-separated negative,

Recording body 20 using another electric motor. Ill 2i and spindle 22 moves axially in opposite direction of arrow 10 along a rotating medium (recording cylinder) 2, Recording body 20 performs line-by-line and pointwise exposure of raster points on the photosensitive recording medium 23 located on 2 "recording cylinder

The recording beams 24 focused by recording body 20 on recording medium 23, expose recording points Rd, which, due to relative movement between recording body 20 and recording cylinder 2, pass along the perimeter (in recording direction) of recording line 25 on recording medium 23.

Each raster point consists of several tightly attached to each other lines 22 entries. The shape and size of the raster point depends on the length of the recording lines or on the duration of the inclusion of individual recording rays. The recording beams are turned on and off by means of the recording signals A. which are transmitted to the recording authority 20 via communication channels 27,

In the framework of the invention, it is envisaged to expose the lines of a raster dot recording line with a single recordable beam in the recording direction.

Receive recording signals A ,.

The instantaneous location of the exposure points P on the recording medium 23 is determined by the UV coordinate system 28 not dependent on the raster angle on the recording cylinder 2, the axis of which is oriented along the perimeter of the recording cylinder, 2, and the axis V - in the direction of feeding of the scanning and recording bodies . The 28-point U-V coordinate system is divided into a MULTIPLE of area plots from which recording raster points are constructed.

The location of the raster points 26 on the recording medium 23 is specified by raster grid 29 on the X-Y coordinate system 30, which is rotated by a raster angle relative to the U-V coordinate system.

The raster grid 29 consists of a set of raster cells, the size of which depends on the recorded screen frequency of the raster. Each raster cell consists of sections of the pond that have the corresponding x coordinates; y

For a raster cell and a reference cell that is not dependent on the raster angle and screen frequency, the Ras (x; y) spatial function is assigned to a range of values limited to the reference cell, which determine the size of raster points depending on different amplitudes

video signal (image tone) and 6 o vry raster dots. In this function, R is the threshold of sensitivity of the recording element raster, and x, y are the corresponding coordinates of a point in the 30-coordinate system X-Y.

The range of values related to pptxs to a given function of the coordinates of the point x, 0 Y is limited compared to the range of pot-values during the passage, the entire area of the recording of the coordinates of the point X, at the points P of the exposure. The representation of f}, T1-ktsii R § (x; y) 5 in space is also called the raster peak, the main area of which fills the reference cell and in which the transverse area 0 located at the height of the instantaneous amplitude of the video signal sets the raster point size for corresponding tonality of the image. During the reproduction, the current coordinates of the point x, 5 are at the points of exposure P, in the 30 coordinate system X-Y, recalculated for a limited range of coordinate values of the point of the reference cell and the corresponding values of the luminous characteristic m are determined. The value is compared with the video signal and after comparing the resolution, write the corresponding area in the system 28 of the U-V coordinates as part of the raster point or not.

To determine the coordinates of the point u, ..., the unitary unit of the exposure points P in the system of 28 coordinates U – V, the axis U and the axis V 0 are divided into main steps / 3U and uV;

The coordinates of the Up point are obtained as a multiple of the basic steps yi 5 and V.

At the first stage of the method implementation, the instantaneous coordinates of the point Up, V of the points of exposure of the RP are determined from the current reference or summation of the basic steps and dV by means of two tact sequences T (, and T in the conversion cascade 21. The sequence of tact T ,.

and

is obtained by dividing the frequency in division 5 stage 32 from the clock cycle T of the clock generator 16, and is introduced into the conversion stage 31 via a communication channel. Each measure of the TV corresponds to the main step Dee.

7

llnvma main step can be changed by the frequency of the sequence of tact 1y,

The peripheral sensor 34 pulses, also connected to recording 1 cylinder 2, produces once per revolution, i.e. after each step of supplying the reading body 7 and the recording body 20, one peripheral impulse Tu, which corresponds to each basic step UV, the peripheral impulses TV are inserted into the conversion stage 23 via channel 35.

The coordinates of point V, for the first point of exposure P, follow from the equations:

and, C-4U;

V,

With v. dV,

Where is and LU - the main steps in the system of 28 U-V coordinates; Su and C y is the number of cycles T i-shi

Pairs of point coordinates for other points of exposure can be calculated from a pair of coordinates of one point of exposure 5, for example, the first exposure point P, "The position of the exposure points relative to each other can be any, usually the exposure points are on the same straight line.

In this case, the distances U and V between the points of exposure are constant and depend only on the design of the recording body 20 and the scale of the image. The coordinates U and V of the other points of exposure P can be calculated using the equations:

I

Uf, and, + (n-l) ir and V, n- (n-l) V

But often the points of exposure of the races are reported directly on the generator of the recording cylinder 2, and tog-t da and 0.

In the second stage of implementation of the method in the transforming cascade, the 31 coordinates of the point U ,, V | systems: 28 coordinates of the U-V point, taking into account the raster angle, fl- and different raster lineatures are constantly converted to the corresponding coordinates of a point of the 30-coordinate system X-Y.

During conversion, the largest range of values encountered when exposing the entire area

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Record body 23, is limited to the PS range of values set by this function, 1 and R g Cx, y).

The recalculation of the coordinates of a point in the transformation cascade 3 is carried out according to the equations:

X K and cos / -I- K. -V sin / i; y sin /; K ,, - V cos p

(2)

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five

0

five

0

-55 0

g

g g

In equations (2), the coefficients K y and K take into account various raster lineatures of the recorded raster image: ykk and reference cell.

Angle 1 and rasters are pre-set ng. inputs transform .cc cascade 3.

The transforming cascade 31 vysod1-; t at its outputs; No. I of each exposure spot P corresponds to a Cie of a pair of coordinates k ,, y ,.

The raster generators 37, 38, and 39 produce, from the proposed coordinate pairs x, y for a given function, R g (x; y), the corresponding level values of the sensitivity threshold R of the raster, which, like digital spectral filtering filters, - eh, have a recording density of 8 bits.

To compare the raster sensitivity threshold values with the signal selected on the signal switch 19, digital comparatives 2 43 and 44 are provided, including writing recordings to the PA signals that control the exposure of the pixel points 26 to the recording medium 23.

The raster generators can be made, for example, from a constant value accumulator, E of which stores the same function R g (x; y).

The constant-value accumulator is made up of matrices, for example, 5 with 32x32 memory cells for raster threshold values. Memory cells can be dialed: 32 x X and 32 hell, res Y.

It would also be possible to address all accumulators of constant values by the coordinates of the point x j at one of the points of exposure. Different values of the raster sensitivity threshold for other points of exposure are obtained by taking a sample: when programming separate drives of constant values, the corresponding U and V distances of other points of exposure converted to the 30 X-Y coordinate system are learned.

To save accumulators of constant values, different pairs of coordinates X can be used; y for the points of exposure can be addressed sequentially to a single accumulator of constant values by the multiplex method.

The raster generators 37, 38, and 39 can consist of functional transducers that simulate the function R g (x, y).

In the device according to FIG. 1, the feeding motion of the reading body 7 and the writing body 20 may be periodic or non-linear.

In the case of periodic feeding, deployment and recording are carried out around the cylinders onto circular lines of the image, the distance between which corresponds to the feeding step. With a continuous feed, the unwrapping and recording is carried out along spiral lines running around the cylinder lines of the image. In this case, the recording produces small errors that can be compensated by correcting the factors S sin /} or S x X cos / 3 in equations (2) transform, and Sy means the pitch of the helix line, and ((raster angle ,. The transformation equations are as follows:

x KIJ-U COS / 3 + Ku V-sin / i; KL.-U sin f + KV-V cosA (3)

where and, V are the coordinates of the recording elements in the coordinate system of the non-inverted recording raster; p, is the specified angle of rotation

raster;

x, y are the coordinates of the elements of the record in the coordinate system of the printing raster;

K, K - scale factors.

X X .nod

y-mod NO ,.

X, y - the values of the coordinates of the eta bar elements within the reference cell; M,, and - the number of reference elements in both

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g

50

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reference cell boards.

For a better understanding of the bitmap entry in FIG. 2 shows an enlarged detail of the recording medium 23 with a U-V coordinate system 28 related to the device (recording direction and direction) and a grid 29 recorded to be turned into a raster on which the X-Y coordinate system 30 is oriented, and the coordinate systems include a raster angle /.

The raster cell 47 of the rotated raster grid 29 with the raster point 26 represents a kind of basic structure of the raster pattern, which periodically moves forward in the X and Y directions throughout the entire recording area.

The raster point 26 consists of several adjacent ones, in the direction of the recording lines 25 of the record. Each recording line 25 consists of individual recording elements 48, which correspond to the order coordinates of a point, and, V or x, y.

In addition, the reference make-up 49 of any raster screen frequency is indicated, which is also composed of several recording elements 50. Each recording element 50 corresponds to the threshold value of the raster R and the xj y coordinate pair, the range of values of which, however, is limited to the reference cell 49.

During recording, for each recording element 48, which instantly passes the exposure point, a value of the element characteristic is calculated for the congruent area 50 in the reference cell 49 and compared with the video signal to obtain recording signals.

Receive video signals. In the example above, the following: FIG. I recording body 23 reproduces, for example, three recording beams 24 and thus also several adjacent exposure points P, which in one turn of recording cylinder 2 expose a corresponding number of lines 25 of recording.

If there are three exposure points from P, from PJ, as shown in FIG. 2, and the raster point 26 consists of recording lines 25, then raster point 26 will be displayed after two cylinder turns or feed steps of the reading body 7 and recording body 20. In this cjrynae for all Lins 1 and 25 raster point recordings 26 there are only two expanded adjacent video line 51 information image; Original 6, the accuracy of the recording can be increased. if for each recording line 25 there is information contained in the image obtained from the video line with the location.

This can be achieved in the case when the original. 6, a plurality of adjacent image points located in the direction V of the system 28 of the coordinates U-V are scanned at a time and each time a video signal of that image point is selected for controlling the recording device, the location of which on the original 6 coincides with the recording line 25 being currently recorded,

The recording body 20 can produce a thickness of the single beam 24 and, accordingly, only one point P at the same time exhibited on the record carrier 23. In this case, one write 1 LSR 25 records per revolution of the recording cylinder 2, and the reading body 7 and the recording Authority 20, after each rotation, performs one step of feeding the recording line to the width, therefore, for each line 25 of the recording of the raster point 26, the image information is obtained from the line 31 of the 31 This method is very accurate, however it is very slow.

The distances between the image points on image line 51 are chosen, for example, t 1 ki, so that in the direction and on ka: "(one raster point 26 turns one point of the image. Since the clock of the sequence of the deployment cycle T corresponds to the distance, They can be adjusted by changing the frequency of the sweep sequence T.

FIG. 3 shows an example of the transforming cascade 31, in which the order coordinates of the point U, V of the system 28 of the coordinates U-V are determined by counting the main steps dU and uV and

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five

0

five

0

five

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five

five

recalculate according to equation (2) in coordinates). X., Y for controlling the raster generators 37, 38 and 39.

The values of and Ky J ,, as well as cos / 3 and sin / 3 are accumulated in registers 53 and 56,

Tacts Tu and TV are counted in counters 57 and 58. The readings of the counters correspond to the factors Su and C ,. According to equation (2), the factors are multiplied in multiplication schemes 59-62, and then the product cyi iMHpyTOT- with in adders 63 and 6A, the result is the order coordinates for the first point P of the exposure as information in 32 bits.

Since 32 addresses X and 32 addresses Y of the accumulator of constant values can be dialed in the raster generators 37, 38 and 39, respectively, with information in 5 bits, the calculated Kooip values of the point (32 bits) are recalculated to the limited range of addresses x, y from 0-31 (5 bits) with respect to X, x, mod 32 or y, - y mod 32 in the registers: 65 and 66. Recalculation is performed by resetting the higher bits,

The output signals of the cascades of registers 65 and 66 are the address pair for point P of exposure of the constant value accumulator.

Other pairs of addresses x, y for other points of exposure P are found by summing the magnitude of 1-sh (ni) x and (p-Oy with the calculated coordinates of the point x and y in copiers 67-70 by dropping it in regs of axes 71-74, The values are calculated by the given distances U and V; by the points in the exhibit (F, P,

Also, address pairs x, y for other points of exposure P ,, can also be found by combining {po вел вел вел led # 1in (n-OU and) Y from the coordinate point U and V, the first point of exposure P, and the next iipe education.

Raster acquisition can be further improved by accumulating more than 32x32 raster sensitivity thresholds in accumulators, constant values of raster generators 37, 38 and 39. Improvement is preferable: is achieved without a corresponding increase in 3 U capacity, if the converted coordinates of a point of one of the exposure points to op13

In the case of constant value accumulators, superimpose auxiliary values, the values of which are determined quasi-randomly and which are less than the coordinates of a point.

The use of the invention increases the manufacturing quality of screened plates.

Claims (3)

Invention Formula 1 A method of manufacturing rasterized printing forms, consisting in forming raster points arranged in raster cells of a printing raster from printing elements in a raster using a recording organ, reading point by line and line by line, measuring the velocity values of the read points of the original image, point by point and line by line relative movement of the recording body relative to the elements of the records, determining the corresponding position of the recording body in the coordinate system returning a recording raster, determining the reference luminance values of individual recording elements corresponding to the position of the recording authority, comparing the reference luminance values of individual recording elements with the luminance values of the corresponding image points of the original and registering recording elements, characterized in that, in order to improve the quality of manufacturing the use of arbitrary angles and screen lengths of the raster, after the determination of the position of the recording organ and the corresponding element The recording elements in the coordinate system of the non-rotated recording raster establish the position of the recording element in the coordinate system of the printing raster rotated relative to the non-rotated recording raster at a given raster angle, then determine its position inside the corresponding raster cell of the printing raster and determine the reference values of the brightness of individual recording elements and , a reference cell of the reference cell is determined, the position of which within the reference cell is set to correspond to the position of the recording element i wipe the raster cell raster print, then U fixed one-) the value of luminance and compare it with the corresponding reference element. 2. The way according to. Clause I., characterized in that the coordinate values of the recording elements are mathematically determined in the coordinate system of the printing raster rotated by a given raster angle relative to the coordinate system of the non-rotated recording raster, in accordance with the system of equations 15 x K, j U cos / 3 + K ,. V-sin / i, for KL, Usin / i + Ky V-cos / 5 where and, V - the coordinates of the elements of the record in the system of 20 coordinates of the untapped recording raster; p, is the specified angle of rotation raster; x, y - values of the coordinates of the 25 entry elements in the system the coordinates of the print raster Kj ,, K are scale factors and then mathematically determine the coordinates of the reference elements within the 30 reference cell, whose position corresponds to the position of the recording elements inside the printing raster, in accordance with the system of equations 35 X x mod-Mp.y y mod Np where X, y are the coordinate values of the reference elements within the reference cell; MO NO is the number of reference elements in both directions of the reference cell. 3. A device for making printed plates, containing an optoelectronic reading organ, optically connected to the read carrier, optically coupled to a recording medium, recording organ, kinematically coupled to a read carrier and a recording medium, a coordinate registration unit pacTi pa, a recording unit reference values of luminance and a read and write transfer unit, kinematically connected with carriers for writing and writing, and comparators, which is comprehensible by the fact that The RRD is one of arbitrary angles and lineatures of the raster, it is equipped with an analog digital converter 5 And the unit for registering the reference brightness values consists of raster generators and a converter cascade at 3TON and the codes of the raster coordinate registration unit are connected to the input transforming cascade and first anag inputs; its digital converters, the second inputs are pbix are connected to the corresponding outputs of the optoelectronic connection of the organ, and the CC outputs are connected to the first – 1 inputs of the respective comparators; Moreover, the outputs of the HF-forming cascade are connected to the inputs of raster generators. H f6 fiyo. 2 TU Tv 35 Fig.Z